Please read this manual in detail before operation

CY4102-N3B CNG engine

Operation Manual

DONGFENG CHAOYANG DIESEL CO., LTD

一

Foreword

CY4102-N3B natural gas engine is developed on the base of our existing

CY4102BZLQ diesel engine, by the means of redesign piston, fuel supplying

system, performance optimize and reasonable match, increasing

corresponding natural supplying system and electric ignition system and the

other equipment. The engine every assembly components are very

interchangeable with our current CY4102BZLQ series engines.

CY4102-N3B natural gas engine is single point injection fuel engine. They have the advantages of small volume, light weight, strong power, good in climbing, low emission, low fuel consumption, easy start, low noise and long service life. The engine every assembly components are very interchangeable with our current CY4102BZLQ series engines. They are the ideal power for city medium bus and light-duty cargo vehicles, and they also can be used in other power machine by changing the version. The overall connection dimension is basic same with all kinds of varies of CY4102BZLQ engine. Through stand performance test and reliability test, vehicle road performance test and operation of customers showed, its structure become more reasonable, all the index of performance is more advance, and have higher service reliability. So if you purchase this kind of engine or the vehicles with the engine and all kinds of mechanisms will gain good efficient of economy, the engine is your ideal green environment protection power. In order to bring engine into full play, keep the engine in good technical condition all the time, we herein work out this manual for operator and service people. With technical continuous development of natural gas engine, the diesel engine will be continuously improving, therefore detail specifications in this manual may be different with practicality because of products renovating, please customers understand, but will not affect customers’ normal operation. Except our revision when it is reprint, we kindly ask our customer to pay more attention to it in operation. The customers’ satisfaction is our tenet, please you point out mistakes to the

book so that we can correct. When you use our products, if you have some

suggestions and opinions, please contact us in time, and we can’t bear to very

appreciate.

When you use our products, if you have some problems and difficulties,

please contact us in time too, we will service with all our heart.

二

I

Cautions

Due to these engines use CNG (compress natural gas) as fuel, so there are obvious differences in some aspects with engine as diesel oil in operation and maintenance, please pay more attention to it!—

1 Engine CNG supplying system must ensure good sealing performance. Before dispatch a vehicle, besides perform routine checking, and also must check leakage and abnormal phenomenon to steel bottles, damper, mixer, tie-in subassembly, high-low pressure pipes and joint of CNG supplying system, if found the problems, must repair and get rid of them. Service or maintenance to CNG supplying system should be completed by professional persons. Note: Air pressure of gas bottle can reach 20Mpa, prohibit to disassembly high-pressure pipes with pressure. 2. Engine ignition system and electric controlling equipments should be normal. CNG vehicles should park the drafty space, at the same time there is no obvious low-lying on the ground. Should set obvious Strictly prohibit fireworks symbol. When vehicles park for long time, should close bottle mouth valve every steel bottle, manual close valve in high-pressure pipes or high pressure electric magnetism valve. 3. Before start vehicles or during running, should pay attention to check CNG residual gas at any moment. When gas volume display meter pointer value is low prescriptive value, should charge to scale or when pressure meter showed inadequate, should charge in time. 4. Must invite working persons to charge CNG in the compress natural gas station, close ignition switch when charge natural gas, and must charge to meet national standard vehicle CNG. Finish to charge, and after you can ensure filling gun has came away with CNG charge valve, charge valve cover has been covered, and supplying system has no leakage. Then you may start vehicles. 5.After the engine was started or before it stops, it should be run at idle for 3-5 minutes to ensure the heating or cooling of the engine is done evenly. Generally, you shouldn’t change speed and load, running at idle should no more than 10 minutes, running at idle with big acceleration is not allowed. 6.Recommend to use Greatwall brand natural gas engine special lubrication oil, at least adopt CF grade oil, select the brand according to the ambient temperature, change it regularly, it must be precipitated and filtered before filling.

III

Contents Outside characteristic curves of engines Chapter I Technical Characteristics of Engine A. Characteristic of engine B. Main performance index of engine C. Technical specification of engine D. The main technical index of engine E. The difference of CNG engine with the main spare parts of original

engine Chapter II Engine installing and operation A. Notes items for installing & operation A. Natural gas, lubrication oil and cooling water B. Preparation before start C. Engine start D. Run-in maintenance regulation of engine E. Operation of engine F. Stop of engine Chapter III Maintenance of Engine A. Daily maintenance for CNG supplying system B. CNG system maintenance and regulations C. Notice items for CNG system maintenance D. The other system maintenance Chapter IV Engine normal adjustment A. Valve clearance B. Fan belt Chapter V The main spare parts of engine A. Cylinder block assembly B. Cylinder head assembly C. Crankshaft and flywheel D. Piston and con’rod E. Driving system Chapter VI Fuel supply system A. Combustion and combustion chamber. B. Turbo-charge inter-cooling system

IV

C. Valve system D. Air supply system E. Controlling system Chapter VII Engine auxiliary system A. Lubrication system B. Cooling system C. Electric system D. Clutch Chapter VIII Failure Diagnosis of Diesel Engine and Way of shooting A. Ordinary failure and way of shooting (mechanism) 1. Ordinary failure diagnosis and shooting 2. Ordinary checking steps of natural gas equipment B. Ordinary failure and way of shooting (Electric controlling) 1. Note items 2. Failure shooting 3. Failure instrument diagnosis Appendix 1 Meaning of the unit symbols used in this manual and

Conversion table Appendix 2 Character compare between gas fuel and petrol

V

Chapter I Technical Characteristics of Engine

VI

A. Characteristic of engine Besides natural gas engine inherit original engine merits, it also with following characters: 1. During starter idle, accelerate and decelerate transition running period, electric controlling unit (ECU) may rapidly make timing, capacity natural gas supply engine, make engine idle stabilization, start and accelerate reaction rapidly, ensure engine with good dynamical, economic, emission characteristics. 2. Decrease cut-off gas function: when decrease, throttle valve close, engine

still run with high speed, make vacuum in intake pipe enlarge. In mixer

system, now it will supply gas greatly, make mix become thicker, then cause

non-complete combustion, thus make CO and HC increase in exhaust gas, at

the same time gas exhaust will increase too. But after adopt electric control

gas injection, electric control unit (ECU) may adopt cut-off methods

according to relative speed and throttle signal, can reduce emission, save

natural gas. When engine speed reduce certain extent or step throttle, then

restore supply gas.

3.Intake channel adopt direct current channel, ensure enough gas-filled capacity. Spark plug installing mode on the cylinder head can make spark plug cool sufficiently, and ensure good ignition performance. 4. Adopt high-energy ignition system, choose optimal ignition time according

to engine behavior, ignition mix gas with max. energy, and ensure engine

synthesis performance.

5.In order to meet gas fuel requirement, design combustion type of tiny turbulence effect with adoptive to it, and ensure compressive ration requirements that combust fuel. 6. Inlet, exhaust valve & valve seats two pairs of friction assembly: valve

adopt alloy material, ensure abrasion resistance in high temperature and good

self-lubrication, and made up poor lubrication condition of engine itself.

7.Fuel reserves display may put in cab, and supply information to drivers in

time.

1

B. The main performance index for engine

4102- N3B Rated power kW(Ps) 88 Rated RPM r/min 2800 Max. torque N.m(kgf.m) 343 Max. torque RPM r/min 1400~1600 Min fuel consumption rate at full load

g/(kW.h) 210

Exhaust temperature ℃ ≤750 Max. idling steadily RPM r/min 3100

Percentage of oil & natural gas consumption

% ≤0.8

Emission Euro Ⅲ

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C. Technical specification of engine 1. Engine：

Type Vertical, in-line, water cooled, 4-stroke, Turbo-charge inter-cooled, electric-controlling injection intake, electric-controlling ignition, ternary catalyze after treatment

Cyl. No.-bore x stroke 4－102×118mm Liner Thin wall, dry

Shape of combustion chamber Basin combustion chamber Compression ratio 10:1

Piston displacement 3.856L Working order 1-3-4-2 Direction of rotation (view from flywheel end) Counter clockwise

Way of start Electric start Way of stop Cut-off, stop electricity Way of lubrication Pressure lubrication combined with splash

lubrication Way of cooling water cooling Overall dimension 790.5×661.5×813mm Net weight 340kg

2. Oil pump Gear type, or rotor type Oil filer Full flow Oil cooler water cooled, built-in plate case Water pump Centrifugal impeller Thermostat Wax type, first opening temperature: 76℃,

full opening temperature: 86℃ Fan Seven vanes, axial flux, ￠450 Air filter cyclone dust collecting, paper element Starter Electromagnetic control 24V、3.7kW Alternator Silicon controlled rectifier 24V、70A vacuum pump Vane Reducer three-grade diaphragm/membrane

D. Main technical data of engine 1. Valve timing (according to crankshaft angle) Intake valve opening 14° before.T.D.C. Intake valve closing 50°After.B.D.C. Exhaust valve opening 56°Before B.D.C. Exhaust Valve Closing 16°After.T.D.C. 2. Clearance between the valve and rocker arm (cool engine):

Intake valve 0.30-0.40mm

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Exhaust valve 0.30-0.40mm 3.Spark plug extrude height of cylinder head bottom

4.5－5.5mm 4.Oil pressure :

Pressure at idle ≥118 Mpa Operation pressure 196-490kpa

5.Outlet temperature of cooling water: 75－90℃，，the cooling water shouldn’t boil during running

6.Capacity of cooling water: 8 L (only engine) 7.Oil capacity of oil pan: 5.7 L (oil filter and oil cooler not include) 8. Fan belt tension

Apply 39 N (4kgf) force on single belt, the single belt deflection should be within 10－15mm

9. Torque of main bolts and nuts Cylinder head bolt 108－118N.m (11－12kgf.m) Main bearing bolt 216－235 N.m (22－24kgf.m) Connecting rod bolt 118－127N.m (12－13kgf.m) Flywheel bolt 196－216N.m (20－22kgf.m) Flywheel housing bolt 127－147N.m (13－15kgf.m) Tighten bolts of idler shaft gear 108－118N.m (11－12kgf.m) Front end nut of crankshaft (or start paw) 392－441N.m (40－45kgf.m) Relief valve of main oil gallery 29－39N.m (3－4kgf.m) Spark plug 29－39N.m (3－4kgf.m) Bracket bolts of front hang 78－98N.m (8－10kgf.m) Attention: a). If there is on locking washer, the torque value must be kept. b) Tightening with lubrication oil when assembly. If the thread of the bolt

was damaged, don’t use it. c). Alternately tighten every bolt 2 ~ 3 times with required order. 10. Torque of normal bolts: (unit: N.m)

M6 4-6 M8 18-23 M10 32-42 M12 55-70 M14 90-110

E. The main parts difference between natural gas engine and original engine Change parts: piston, cylinder head, valve seat, valve, intake manifold, water cooled turbocharger Revocatory parts: high pressure pump assembly, injection nozzle and high pressure fuel pipe, low pressure fuel pipe Increased parts: Natural gas supply system and controlling system such as:

4

Reductor, ECU, whiff nozzle, wiring harness, ignition coil, spark plug, high pressure wires, all kinds of sensors and all kinds of pipe and ect.

Chapter II Installing and operation of Engine To operate the diesel engine correctly, it not only can keep the engine running properly, but it also can extend the service life of the engine. A. Installing & operation note items for natural gas engine

When natural gas engine was installed on automobile chassis, follow the

general principles: every joints of natural gas pipe should be fastened, steady.

electric assembly and lines should adopt dustproof, waterproof and

anticorrosive materials. Electric unit installing mode must correct, fasten,

intake system and exhaust system resistance is small, accelerate handle stroke

must match with peddle throttle stroke, oxygen sensor and ternary catalyze

converter position must be right. Natural gas special equipment installing

must be right. The integral collocation should be concise, beautiful, pipeline

circuitry should be flat & straight, fluency, engine room ventilation, heat

radiation are good, and ensure engine to keep good work state.

Operation note items:

1.Engine natural gas system must be checked and installed according to

relative state standard. During operation, if must change spare parts, after

installation, before operation, carry out checking. If don’t have special

equipment, may use foam of soap to check tie-in of every natural gas pipeline,

and observing time should not be less than one minute. Natural gas steel

bottle of engine all have checking certificate that state appointed department.

The period of validity of the certificate is fifteen years, operation unit should

keep it properly. The first checking and the second checking are carried out

for gas bottle every three years for one time, after second time checking, it

will be checked one time every two years. The period of validity for the

second time checking is one year. The gas in gas bottle can’t exhaust

completely, should ensure 0.1 MPa residual pressure.

2. Air pressure reached 20Mpa for gas bottle, prohibit to disassemble high

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E. Regulations of run-in maintenance

The new engine must do run-in operation before it is normally used, so that the different parts can match well, to avoid the abnormal damage and wear. Experience proves that engine service life, reliability and economy mainly depend on primary wear of the engine. Can customers please carry out the regulation of run-in maintenance. For overhauled engine, it also should perform the run-in maintenance with this regulations.

The regulations are the basis for DCD and its service stations to perform

“run-in maintenance” service. When the service station performes its run-in

maintenance service, it must be registered and stamped, which will be as the

basis for customers to “guarantee service.”

1. Specification of engine run-in: (1) Run-in period:

Engine run-in is normally about 60 hours, it can be done together with vehicle. If it calculates by mileage, engine must be run-in for about 1500~3,000 km.

(2). The load and speed required in run-in period:

Mileage (km) Max. load Max. speed 0~200 Idle >200~800 50% rated load 70% rated speed >800~1500 70% rated load 75% rated speed >1500~3000 75% rated load Not over the most

speed

2. Conditions in run-in maintenance： (1)Vehicle mileage is between 1,500~3,000 km.

(2)Engine is surely not repaired or adjusted by the customer. (3)If the mileage meter was damaged or failed on the vehicle, (count from the second date when customers collect the vehicle or engine) customer can apply for run-in maintenance service to the service center within 15 days.

3. Detail regulations of run-in maintenance (1)When run-in operation finished, customer can apply for run-in maintenance at nearest technical service center of DCD.

(2)When the service center found the engine meet the second term of run-in maintenance, it can get the run-in maintenance service.

(3)When the run-in maintenance operation finished, the service center

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should write down clearly item by item and give the maintenance sheet and

certification with an official seal and customer stamp or personal signature on

it to the customer.

(4) The customers who bought the Dongfeng’s vehicle against Quality Warranty Manual of the vehicle, for the others vehicle, invoice (copy is ok) of the vehicle and duplicate of certification can be used as the certificate of run-in maintenance and quality warranty for a new engine.

(5) If the mileage of a vehicle is over 3,000km (or over 15 days), but

that the engine did not perform “run-in maintenance”, and once find fault on

the engine, the technical service center will not give “guarantee

maintenance”.

4. The contents and standards for run-in maintenance：

No. Contents Standards 1 Change lubrication oil in the

oil pan: special lubrication oil or CF grade engine oil.

According to operation manual stipulation.

2 Clean oil pan, change paper element of oil filter

Parts from official suppler

3 Clean air filter element and dust disk

Parts from official suppler

4 Check torque of connect rod bolt

118-127N.m(12-13kgf.m)

5 Check torque of main bearing bolt

216-235N.m(22-24kgf.m)

6 Check cylinder head bolt torque

108-118N.m(11-12kgf.m)

7 Check and adjust valve clearance

Cold engine, intake & exhaust clearance is 0.4mm

8 Check and tighten the nut of water pump shaft, fill grease

40~45N.m torque, calcium base grease

9 Check belts tension of the fan Vertically single belt 39N,deflection 10~15mm

10 Tighten external bolt and nut According to the requirements 11 Check reductor and mixer

sealing Can’t leak

12 Check CNG steel bottle, connection pipe and tie-in/adoptor

Can’t leak or damage

9

13 Check electric controlling line and spark plug

Work must be normal, no carbon deposit according to the operation manual.

F. Operation of engine The speed and load of the engine as well as the running speed of the

vehicle should be gradually and evenly increased or decreased, it’s not allowed to change the speed and load suddenly, except for special circumstances.

Constant attention is paid to the readings of all meters and engine operation conditions (noisy operation and exhaust smoke) during engines or vehicles in operation, and emergency measures must be taken whenever engine operated abnormally.

The water temperature is about 358K (85℃) when engine operated normally, oil pressure is about 196~540kPa.

Vehicle is forbidden to apply the way of measure “accelerate --- flameout---idling coast---put into gear with clutch”, because engine is flameout suddenly at high speed and high temperature, oil pump and water pump will all stop working, so lubrication oil and coolant can’t take away the heat of internal parts. Besides lubrication, lubrication oil has another important roles, that is to cool internal high temperature parts of engine. In addition, catch fire pulled by clutch, make RPM of engine starting over big, now the shock is very big, it’s quite harmful to the engine. G. Stop of diesel engine

Speed and load should be gradually reduced before engine stop. After engine stopped, it should idle 3-5minutes, then to stop in order to make engine cool evenly and gradually, thus it can prevent from parts damage due to the engine is overheat.

Chapter III Maintenance of Engine Regular maintenance is one of the important items to operate engine

rationally. Therefore, carefully maintenance can be performed under criterions if the customers want to keep the engine in excellent working condition and serve reliably for long term.

The maintenance criterions below are the content on limited maintenance period and minimal operation when engine works under good and normal condition. When the working condition and environment of the engine is worse (such as too much dust, wet etc.), the maintenance period should be shortened accordingly.

A. Routine maintenance for CNG supplying gas system 1. Before dispatch a vehicle every time, should check fastening of every parts, deal with loosen parts in time, check gas bottle, pipeline and connection

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whether there is leakage or not (may use suds), if there is leakage, must deal with it in time. 2. When gas bottle is charged, must pull grip brake, and turn off electric

source, do it by special person in filling station.

3. After charged, pay attention to whether there is leakage in supply system,

after ensure there is no wrong, then may start.

4. Check whether valve core sealing rubber gasket of reductor

electromagnetism valve every month distorts or not. Before check and

disassemble, should make manual stopping valve of combination valve on

steel bottle close, start engine, run out of natural gas in supplying pipe, then

can discharge electromagnetism valve, otherwise high pressure work is with

serious danger, and unsafe.

5. Driver should often pay attention to check whether gas display is the same

with displayed contents on the steel bottle display meter. If found problems,

should adjust or change in time.

6. Reductor is the important parts of natural gas supplying system, must pay

attention to the running, once found bad working or leakage, must carry out

maintenance. Disassemble pollution draining off plug on reductor, let out dirt

and coagulum, if jam object can’t be drained off, will influence the

performance seriously.

7. Check regularly whether the low pressure pipe was wore, aging, and there

is leakage gas on the adoptor.

8. Check regularly whether there is damage and aging to water circulate

system, and there is leakage circulate water on the adoptor.

9. According to the operation manual, clean or change spark plug regularly

10. Driver should often keep air filter element clean. If filter element is too

dirty or damage, it will cause vacuum change of mixer location, will

influence supplying system performance of natural gas, lead to engine start

difficultly, idling and accelerate

11. Store bottle was installed vehicles chassis, attachment damp clay in

running, will corrupt to store bottle and tie-in parts ect., so should often clean

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vehicles, and keep parts clean.

12. When didn’t used vehicles for a long time, should close manual switch on

the gas bottle and general switch of electrical source.

13. Should check natural gas system one time for half a year, and adjust the

total system according to the requirements.

14. Drivers should be responsible for work, during maintenance, must record

failure treatment and changing of parts in order to overhaul vehicles for

special maintenance personnel.

B. CNG system maintenance regulations Item Content Position Contents Methods

The adoptor between high pressure pipe and outlet of charging valve

Whether loose or leakage or not

The adoptor between high pressure pipe and inlet of electromagnetic valve

Whether loose or leakage or not

The adoptor between high pressure pipe and outlet of electromagnetic valve

Whether loose or leakage or not

The adoptor between high pressure pipe and reductor

Whether loose or leakage or not

The adoptor between low pressure pipe and reductor

Whether loose or leakage or not

The adoptor between water pipe and inlet tie-in of reductor

Whether loose or leakage or not

Measure leakage appearance or check leakage liquid or odor

The adoptor between water pipe and outlet tie-in of reductor

Whether loose or leakage or not

Whether there is leakage for all kinds of pipes in CNG system.

The bracket of gas store bottle Whether loose or not

Visualization or handle

The connection between gas store bottle and bracket

Whether loose or not

Reductor bracket Whether loose or not

The connection between reductor and bracket

Whether loose or not

Check

Whether there is loose for all kinds of parts in CNG system.

The connection between charging valve and bracket

Whether loose or not

Handle and torque wrench

cleanliness

Reductor film/ membrane

Clean Clean by lotion or change

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C. Note items for CNG system maintenance

● CNG system maintenance must be done by DCD authorizing special

person.

● Don’t operate with pressure (except check-up), when carry out to

maintain to gas store and natural gas system of CNG system.

● Should cut off electric source when carry out to maintain the controlling

system of CNG system.

● When need to disassemble spare parts of natural gas system, should keep

clean, and prevent impurity to enter into supply system, and cause to

block.

● Electric controlling unit, sensor and executing unit must pay attention to

prevent moisture, static, strong electric disturbing, when maintain, must

prevent fall off and impact.

● Don’t wash engine directly by water, avoid to influence sensor and other

electric spare parts, especially although ECU is with moistureproof

function, but can’t wash outside shell by water directly.

● Cleanliness and state for air filter, spark plug, high pressure and other

spare parts influence greatly to use, please clean, change above spare

parts in time.

● When maintain, gas bottle, reductor, high pressure pipe lines strictly

prohibit to knock and bump, and it musn’t be less than 10m about the

distance between gas bottle and fire.

● When open bottle valve, people can’t stand face of gas bottle valve, and

stop valve should open slowly, after ventilate, increase gradually, prevent

to impact pressure meter, decompression valve and other spare parts.

D The maintenance for other system

A. Daily (shift) maintenance 1. Checking lubrication oil in the pan, if it is not sufficient, it should be

refilled. And finding out the reason when lubrication oil level rises and reduces, to refill it to the set value.

2. Checking cooling water.

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3. When does not use deicing liquid, cooling water should be drained out

when engines are placed in environment below 5℃.

4. Check if the there is leakage in oil and coolant, if it exists, we should get rid of it.

5. Discharge exhausting pollution plug on the reductor, drain off oil pollution

and coagulum.

6. Check whether high pressure, low pressure pipeline wore, aging, and there

is mixture gas leakage on the adopter.

7. Check whether the connection between high pressure line and spark plug

fasten or not.

8. Keeping engine clean and necessary wash is required. 9.Getting rid of all troubles and abnormal phenomena.

B. The maintenance after 2000 km (accumulative 50 hours in operation).

1. Complete daily maintenance items and contents. 2. Check all external bolts, nuts and accessories and tighten it by stipulated torque. 3. Checking the tension of belts of fan, if necessary, must adjust. 4. Clean oil element, when vehicle ran every 3000~4000 km, change oil and paper element during maintaining. when vehicle ran every 8000～1000 km for maintenance, change spiral one-time oil filtrate can. 5. Cleaning the dust in air filter disk. If the element was damaged, replace it 6. Fill grease. C. The maintenance after run 8000km (about accumulative 200 hours). 1. Complete maintenance items and contents after every run 2000 km. 2. Check and adjust the valve clearance . 3. Cleaning oil pan and oil suction tray under the oil pump. 4. Clean air filter element and ash tray.

5. Blowing away the dust in alternator and starter by compressed air, lubricate

the bearing and check all parts, and keeping every part in good working

condition, meanwhile, the improper part should be corrected.

6. Check electric corruption of spark plug and deposit carbon, must clean and

change.

D. The maintenance after run 45000km (about accumulative 1000 hours).

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and exhaust manifold. It is not allowed to remove the accumulated carbon from the rotor mechanically, instead gasoline or detergent for cleaning the compressor parts which made of aluminium should be used. Note: Any dismantled rotating parts of the turbocharger should not be damaged or deformed, otherwise it will effect the balance of turbine, any rubber sealing parts can’t damage either. Chapter IV Regular Adjustment of Engine

A. Adjustment of valve gap

To adjust gap of valve according to the following ways, use the 6102.29.10 valve gauge provided with engine. To rotate crankshaft according to rotation direction of engine, align the T.D.C. mark on the damper pulley with the timing mark on gear case cover, the first and fourth cylinder piston are in the position of top dead center, shake the rocker of the first cylinder intake and exhaust valve with hand from up to down, if there is gap in these two rockers, it shows that piston of the first cylinder is in the position of compression top dead center. If both of them do not exist gap, but rocker of intake and exhaust valve of the fourth cylinder exist gap, it shows that the piston of the fourth cylinder is in the position of compression top dead center.

Finishing adjustment of valve gap is in two times: No. cylinder 1 2 3 4 Valve IN EXH IN EXH IN EXH IN EXH

First ○ ○ ○ ○ No. of cylinder in compression T.D.C

Fourth ★ ★

★ ★

Remark: ○—It shows the valve gap which should be adjusted when the first cylinder is in the position of compression top dead center. ★------ It shows the valve gap which should be adjusted when the fourth cylinder is in the position of compression top dead center.

B. Belt of fan Apply 39N force to the single belt which located in the middle position of two wheels, its deflection is 10~15mm, or it should be adjusted.

Chapter V Main Parts of Engine

A. Engine cylinder block assembly Engine block is an integral casting of crankcase and cylinders, in which

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full-support main bearings are used, and it is made of alloy casting iron. The liner is dry steel with thin wall, the wall thickness is 1.5mm, the

liner match the bore through interference (-0.02~0 mm), divide into three groups, assemble with the same group, the shoulder is 0.05~0.12mm above the top surface of the block, the height difference of adjacent cylinder is no more than 0.03mm.

To dismantle the liner, must use special tool and press. First measure the diameter of cylinder bore to select matching liner, the required interference must be ensured, then clean inside of cylinder barrel and outside, keep dry, don’t apply oil, the pressure should be controlled at 4950N (505kgf) when press in the liner, finally press it firmly with 24500N (2500kgf).

Test the water chamber of the block with 392kPa (4kgf/cm2) for 3 minutes, leaking is not allowed. Test the oil passage with 784kPa (8kgf/cm2) for 3 minutes, leaking is not allowed. Before the block is assembled, all oil passages, main bearing hole, camshaft

bore, tappet hole and all joint surfaces must be cleaned, the oil passages should

be unblocked.

There are two windows in the tappet chamber in the left of the block, in which a pipe from the rear end or front cover is connected to the breather (ventilating pipe of crankcase), the oil cooler is installed in the right of the block. In the internal chamber of the block, there is an oil hole in the main gallery, which for fixing cooling nozzle for piston injection, one for each cylinder, all together 4. The torque for draining plug of oil pan is 69～78N.m (7~8kgf.m), when it is leaking, check whether the washer is good, otherwise the draining plug is over tightened, the threads will be damaged.

There is an oil dipstick on the left of the block, the oil level should be in the middle of the two scales.

The front brackets of the engine are fixed with 8 bolts on the left side and right side, the rear bracket is on the top of the clutch or gearbox. B. Cylinder head and gasket

The cylinder head is a four-cylinder unit, made of alloy cast iron. The water chamber of the head must withstand 392kPa (4kgf / cm 2 ) hydraulic pressure test, at least for 3 minutes without any leakage.

The head inlaid with intake/exhaust valve and guide pipe, the head cover is on the top plane, on which there is oil filler.

Cylinder gasket is put on the joint between the bottom of the head and the top of the block, it becomes gas sealed chamber under high strength bolts of the head, allow the incendiary gas to push piston acting instead of leak off, meanwhile, it also has the function of sealing for the circulated cooling water and the pressure oil which goes to the head lubrication rocker mechanism. So

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it has higher requirement for the seal ability and heat-resisting of the gasket. Compound plate gasket is used in this engine, the edge of the cylinder bore is covered with steel sheet, steel wire retainer is inside, the edges of water hole and oil hole are all covered with copper sheet or have special treatment, which have very good sealing ability and higher life time. Piston top gap (between the bottom of the head ) must be measured, the value must keep at 0.9~1.1 mm when new gasket is replaced. Before assemble cylinder head, 20g lubrication oil should be applied uniformly into internal wall of each cylinder. Then cylinder head and block can be fixed with locating bushes and connected with bolts and screws, the tightening torque is 108—118N.m(11—12kgf.m), first tight to 59N·m (6kgf·m) loose all of them, then tight them again to the set value in sequence as figure. The tight sequence is as following:

15 7 6 14

16 8 1 5 13

Ⅰ Ⅱ Ⅲ Ⅳ

17 9 2 4 12

18 10 3 11

C. Crankshaft and flywheel The crankshaft is made of high strength alloy steel 42CrMo with four

balance weights, one time formed by forging. It has soft nitride treatment after finish machining, so its strength and stiffness and wear-resisting are all good.

The main bearing is steel back three elements alloy plated copper lead shell, which has big capacity of bearing, totally 10 pieces. No.3 main bearing shell (down) is different from others, no oil groove on the shell face, don’t apply oil on the shell back when assemble the shell. The material of thrust washer is steel back high tin aluminum alloy installed on the fourth bearing and positioned by the lower thrust washer extended tail, keeping the working surface (the side with oil trough) towards crank-web.

The crankshaft must be washed carefully before put it into the block, special attention must be paid to the cleanliness on the surface of the journal, opening of the oil passage and the surface of the bearing seat. When the main bearing shell with oil hole fit on the bearing seat of the block, the oil holes should be coincided. No.3 main bearing cover should fit with the main shell (down) without oil hole and groove, apply some lubrication oil on the surface of the journal and working face of the shell when assembling.

The main bearing caps and engine block are machined in pairs, there are numbers and serial numbers on the caps. Besides positioned by lug, like other caps, the fourth bearing cap also has pin bush for position. The tip of triangle

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mark of caps is facing the front of engine block, and numbered begin from the front when assemble them. Don’t make mistake.

The main bearing bolts are lubricated with diesel engine oil, the tighten torque is 216~235N·m (22~24 kgf·m), it should start to tighten alternatively from the center (no.3 main bearing) towards both sides. After tightening, the crankshaft can be rotated smoothly. When install the flywheel case and rear oil seal seat, it’s not allowed to knock against the external cylindrical surface and chamfer area of the big end of the crankshaft. It should use the special tool to fix the rear oil seal, to make sure not to damage the seal lip. The torque for flywheel case bolts is 127~147N.m (13~15kgf.m).

The flywheel is fixed at the rear of the crankshaft, positioned by a pin, and it is connected with high load alloy steel bolts. The bolt tightening torque is 196~216 N.m (20~22kgf.m), it should be tighten in diagonal line alternatively by two times. The run-out of flywheel end is less than 0.2mm.

The pulley with damper is fitted at the front end of the crankshaft, the tightening torque is 392~441N.m (40~45kgf.m).

Crankshaft, flywheel and damper pulley are all balanced, please pay attention to its balance when changing parts.

D. Piston and con’rod The top of piston is thermal flow, the skirt is a variable oval barrel

camber, the lower part is slipper structure. The material is eutectic aluminium silicon alloy. The first ring is inlaid with annular austenite cast iron to improve the wear-resisting and reliability. There are two compression rings and one oil ring. The first ring is square barrel with chrome-coated surface , please notice that the end with mark is upwards when it is assembled; The second one is cylindrical micro-taper and chamfered twist ring, the end with chamfer is downwards when it is assembled; The oil ring has an coiled spring expanding ring, the spring connecting point and oil ring opening is at 180°when it is assembled. Special expander should be used when piston rings are assembled, don’t expand too much to avoid broken. The rings should be rotated freely in the groove and fallen freely into bottom of the groove by gravity. When the rings are put into cylinders ,the first ring opening and thrust plane is at an angle of 45°. The second ring and the first ring is at an angle of 180°,the oil ring and first ring and second ring is at an angle of 90°.The recess on the piston top is towards the front, don’t make mistake. And all friction parts must be applied with lu’boil.

Connecting rod is made of forged steel which are numbered on its cap and body in pair, to avoid errors and mistakes in direction. The tightening torque of connecting rod bolts is 117~127N.m (12~13kgf.m). Connecting rod shell material is the same as main bearings. The working surface of the shell should coat some oil, but not the back of it, otherwise it will affect radiation.

Pistons must be heated to 60~80℃ when piston pins are assembled.

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When connecting rod is assembled. When the operator is facing the top of piston, and the intake valve recess is on the left side, the locating notch inside the big end of connecting rod should be at lower part. The weight of big and small ends of connecting rod is strictly controlled , the total connecting rod assembly weight deviation in each engine is below 25g, which must pay attention to it when change parts.

Note: The piston of the engine is special piston, and it is different with CY4102BZLQ piston combustion chamber, the head is round, mustn’t install wrong, otherwise will produce heavy effect, and customers will be responsible for it by themselves.

E. Transmission system

The transmission of the gears is shown in following figure.

The timing mark on gear end must be aligned when gears are assembled, in order to ensure correct valve timing and fuel supply timing.

The installation of idler shaft must keep the oil hole towards camshaft gear.

All bolts should be tightened, and the gears drive freely.

Chapter Ⅵ Fuel supply System of Engine A. Combustion and combustion chamber The way of fire is firing, the mixed gas is formed in the inlet pipe. This

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engine is using round combustion chamber, it located on the top of piston. When the fresh air entered inlet pipe by turbocharger inter-cooling, ECU

collected air flow signal by intake pressure sensor, and by RPM sensor, water temperature sensor, oxygen sensor gathering signal, inquire pulse chart in ECU to confirm natural gas injection quantity, to control engine air & fuel ratio exactly, and confirm right ignition advancer, make mix gas ignite. By great amount of experiment, the intake and fuel supply is ideally matched with the combustion chamber, hence the targets of engine such as power, economy, emission and noise are very good.

B. Turbo-charging and inter-cooling system

The exhaust gas turbo-charging water cooling and air to air inter-cooling system we used in this engine is as following figure: 1. Basic principle: The turbo-charging technology: Exhaust turbocharger is using the exhaust energy (it has certain temperature and pressure) which comes from engine, converted it into return mechanism of the rotor through turbine, hence bring the compressor impeller share the same axle with it to turn rapidly, after the pressure is given to the fresh air and increased its density, passes through the intercooler, then sent to the cylinder through intake manifold, increases the charge quantity of the cylinder, to increase the power of the engine. Inter-cooling technology: Inter-cooling technology is to use the radiator to cool, make high temperature and high pressure air into many small pipeline. There is environmental air around the pipeline passing by with high speed, to cool down the temperature (could low down the air temperature from 1500 C to 500 C). Under the condition of no increase of engine displacement or no increase of engine speed, turbocharged inter-cooling is an effective way to increase engine power, to improve engine economy, and to low down engine emission. 2. Lubrication: The lubrication oil of the turbocharger is delivered by the main oil gallery of engine, returned oil directly flows back oil pan by its weight. In order to avoid leakage of turbocharger, to ensure turbocharger to work properly and reliably, oil feeding and returning must be smoothly, no any leakage. 3. Brief introduction of the structure of turbocharger Typically, turbocharger is consists of turbine, middle part and compressor. In order to further improve acceleration and slope crawling ability of TC engine, to meet the requirement of application, there is an exhaust release valve in this turbocharger, the sketch of its structure is as following:

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(1) Turbine: It mainly consists of turbine housing, single radial flow turbine, which is a energy converter. When the waste gas exhausted from the diesel engine goes into the nozzle through turbine housing, and injects towards turbine blade with certain direction, the heat energy and pressure becomes kinetic, hence allow the turbine turning with high speed. (2) Middle part: The middle part is a middle supporting body to support the rotor assembly, turbine housing and compressor housing. It’s also a lubrication oil tank for lubrication and cooling the floating bearing rotor. In order to ensure turbo-charger to influence reliability by high hot load, turbo-charger adopt cooling water to cool, this is different from the other engine. (3)Compressor

It consists of single centrifugal compressor blade, pressure expander and compressor housing. The air passes through the air filter and absorbed by rapidly rotated blade of the compressor, enable the speed of air flow to increase and pressure to boost, then passes the pressure expander and compressor housing, allow the kinetic energy of air flow become pressure energy. When the pressure is further increased, it passes the intercooler again, goes into the cylinder by intake manifold of the engine when the air is cooled, hence the air density entered the engine cylinder is increased.

The turbine shaft and turbine are connected by friction welding. The compressor blade is fixed in the turbine shaft by transit fit, and the pressed tight with self-lock nut. The whole rotor assembly is very dynamic balanced to ensure the proper operation at high speed. The support of rotor assembly is inner support, i.e. two full floating float bearing are arranged in the middle part between the two blades, the axial force of rotor is borne by the thrust bearing which fitted in the middle part.

The lubrication of turbocharger is done by pressure lubrication, its function is to ensure the rotor and bearing to get enough lubrication and cooling under

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normal operation. (4) Exhaust release valve The purpose to use an exhaust release valve in turbocharger is to ensure the engine and turbocharger to have best matching result within low and medium speed, so that the engine can get enough air, which will adapt with the fuel quantity supplied later, to increase the torque at low speed, to improve fuel consumption. In the range of high speed, by means of exhaust release (i.e. partial exhaust directly goes into exhaust manifold without passes through the turbine) to avoid over fire pressure in cylinder and intensify the mechanical load of engine caused by over speed of turbocharger rotor or caused by over boost pressure, that is to say, turbocharger uses exhaust release valve, mainly is to improve the torque characteristic of the engine at low speed, meanwhile it is to improve the performance target and reliability of engine at high speed. The close and open of the exhaust release valve is automatically controlled by the boost pressure, it’s shown as the figure: guide the boost pressure from outlet of the compressor into the sealed pressure room of the regulator of the release valve, when the boost pressure reach or exceed the specified value, the diaphragm will overcome the spring force from the left, and move towards the left together with joint moved push rod, push the rocker arm to rotate around the pin shaft, enable the release valve open and the exhaust bypass release, to control the increasing of turbocharger speed. Note: (1) The opening pressure value of the release valve is set by the manufacturer, customer is not allowed to make any adjustment, i.e. the adjusting nut in the joint moved push rod can’t tight, otherwise it will be very harmful to the power, economy and operation reliability of the engine. (2) Under any circumstances, it is not allowed to use the joint moved push rod as a lever or a step to bear load or pedal. (3) In operation, if it is found that the gas guide pipe leaking or the joint moved push rod is not nimble, should stop the engine at once and shoot the trouble, but please note that the release valve and the sealed pressure room is not repairable, if it is damaged, the whole turbine housing must be replaced. 4.Maintenance of turbocharger

In order ensure the turbocharger to work effectively and reliably, besides to operate properly, the turbocharger also must be given regular maintenance, but please note that turbocharger is a precise machine with high speed. The max. speed is 170,000 rpm/min. even more, the normal speed is also at 80,000~90,000 rpm/min., so if it’s not necessary, don’t dismantle the turbocharger assembly at will. When the rotor can’t turn freely or the performance of the engine become worse due to too much sticky pollutant or carbon, simply clean and wash under the condition of don’t dismantle the turbocharger, the specific procedure is as following:

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(1) Clean away the dust and greasy dirt on the surface of the turbocharger (2) Remove the turbocharger from the engine, don’t carry the turbocharger by

the joint moving pusher. (3) The gas pipe should be removed first, then take off the adjusting device of

the gas release valve. (4) Take off the housing of the compressor, turbine case and in /return flange. (5) Clean the housing of the compressor, turbine case and the surface of the

two impellers. (6) Fill some clean detergent from the oil inlet, meanwhile turn the impeller by hand, don’t stop until it turns freely. (7) Assemble and fix in the engine. Note: It’s not allowed to knock against the impeller during dismantle and washing, if it is happened, deformed and calibrated impeller can’t be used. Cleaning agent must use kerosene, gasoline or better quality diesel. 5. Inspection of turbocharger (1) Check the radial clearance of the rotor: Press the compressor impeller with your hand along the radial direction when checking, and measure the min. clearance between the compressor blade and compressor housing with thick/thin gauge, such value should be no less than 0.10 mm. If it is smaller than this, the floating bearing should be changed.

(2) Check the axial clearance of the rotor Put a magnetic seat on the outlet flange of turbine housing when checking, allow percent meter touches the end of turbine rotor shaft, then push or pull the turbine rotor along the axial direction, the measured different value is the axial clearance. The clearance of a new turbocharger should be ≤0.10 mm, the limit is 0.25 mm. Now the assembly should be dismantled and replace the worn parts.

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6. Intercooler

This engine is using aluminium air to air intercooler. The hot air goes into the intercooler after boosted through turbocharger, when the air is cooled down until it is about 50℃ (or lower), it goes into the cylinder through intake manifold. By using inter-cooling technology to increase the density of intake, reduce the temperature of intake, hence can increase the intake quantity. By means of good matching with injection system and combustion system, to improve the power of the engine, reduce the fuel consumption and improve the waste gas pollution. During operation, it should avoid to impact the intercooler and ensure no leakage in the connecting pipe in order to affect the performance of the engine.

C. Valve System The valve train of this engine is an middle laid valve type. Camshaft is

made of specially selected 45# steel on which three bearing journals and eight cam lobes are all case-hardened. There is thrust plate (bearing the axial force come from camshaft ) in front of the first bearing journal, and the camshaft axial clearance is 0.06~0.138 mm. There is a discontinuous oil groove in the first journal to feed oil to the rocker. The tappet is ball barrel shape, made of chilled cast iron. The tappet continuously rotates, thus may evenly wear and prevent from scuffing.

The push rod is a hollow steel tube with steel ball and bowl head by friction welded in either end.

The rocker is made of forged steel, and rocker bracket is made of cast aluminum with three different kinds and six pieces. In which there is a oil hole in the front rocker, there is a oil passage in the bolt, the washer is made of copper, don’t make mistake when assembling. The rocker and its shaft is lubricated by the pressure oil come from the head. The material of valve is alloy steel, the cone is build-up welded with cobalt base alloy.

The seat ring is made of powder metallurgy. When the valve and seat ring are lapping, the contact band is a continuous uniform ring band of 1.0~2.0 mm in width, the sealing tightness should be good, put some kerosene into the port for 2 minutes without leakage.

Valve leakage may affect operation of engine, and even lead to the valve and seat ring burning. Checking the sealing during operation must be done according to the maintenance requirement and practical working condition. Valve lapping has to be done or change the valve seat ring if necessary.

Valve guide is installed with an oil seal to avoid oil from flowing into cylinder.

The rocker, rocker shaft, rocker seat and valve components should be cleaned when assembling, they should move freely, the plugs in both ends of the rocker shaft should be well sealed.

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The air filter is cyclone dust collecting paper element, please pay attention to the position and direction of the dust receiver when assembling. When the element is damaged or the sealing is not good, please handle it at once. When it operates under too mush dust, it should be maintained early and change the element.

The life- time of the engine is related very much with the working quality of the air filter, so it is absolutely not allowed to operate the engine without air filter or air filter failure.

D. Natural gas supply system

Natural gas supply system is made up of following parts: High pressure store

gas bottle, high pressure electromagnetism cut-off valve, reductor, air jet

nozzle, gas volume display unit, high pressure pipe and low pressure pipe and

etc.

1. High pressure store gas bottle

High pressure store gas bottle used to store 20MPa compress natural gas,

there is manual stopping valve on the steel bottle, there is a temperature

safety valve on the bottle valve (100℃ automatic discharge pressure) and

pressure safety valve(26MPa automatic discharge pressure), use it to protect

store gas bottle, avoiding to explode at high temperature and high pressure.

And every gas bottle has valve, and they can close separately.

2. High pressure electromagnetism cut off valve

High pressure electromagnetism cut off valve was installed on the outlet

of high pressure store gas bottle. When high pressure pipe occurred failure,

we can close key urgent cutting off system high pressure gas route.

3. Reductor

CNG reductor: Make 20Mpa CNG gas decompress to 0.25~0.3Mpa by

three grade decompressing for supplying engine. There is a fix quantity

adjusting bolt and an idling adjusting bolt on reductor. Fix quantity adjusting

bolt is: when engine is idling, adjust supplying gas of reductor by adjusting

fix quantity adjusting bolt. Idling adjusting bolt is: when engine is idling,

making-up and adjust shortage of supplying gas of engine and adjust

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transition smoothness of engine.

4.Natural gas injection nozzle

Natural gas injection nozzle was installed gas rail, special driving circuit

controlled by ECU, there is a power supply end for every natural gas

injection nozzle, every natural gas injection nozzle has a power supply end,

natural gas injection nozzle controlling end controls the opening of natural

gas injection nozzle by ECU. ECU controls the opening time of natural gas

injection nozzle, called “Injection gas pulse width”. Injection gas pulse width

bases on all kinds of input signal, and calculates by ECU.

Natural gas injection nozzle connected with pressure gas source. Before

natural gas injects intake valve of every cylinder from natural gas injection

gas nozzle, then enter combustion chamber. Natural gas injection nozzle

depends on electromagnetism strength and spring strength, open and close

natural gas measuring plunger. When coil in natural gas injection gas nozzle

electrify, it becomes an electromagnetism iron. Magnetic field that coil

produced can overcome enough spring strength, lift plunger, and leave the

valve seat. When ECU cuts circuit of Natural gas injection nozzle, magnetic

field disappears, spring strength forced plunger to seal the seat.

5. Gas volume display unit

It includes pressure sensor, harness and pressure display meter. Pressure

sensor that installed in high pressure pipeline make gas pressure in steel

bottle show by digital in pressure display meter, and judge how much gas

volume does steel bottle store.

6. High pressure pipeline

High pressure pipeline is made of stainless steel pipe with PVC

wrapped, outer diameter 6mm, thickness of wall is 1mm, max. bearing

pressure is 26Mpa. High pressure pipeline connected among high pressure

gas stored bottle, high pressure electromagnetism cutting valve, filter,

limiting flow valve and reductor, and connected with reductor at the end.

Before connect high pressure pipeline by special connecting unit, first check

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whether it is clean in high pressure pipe (blow by compress air.). When install,

should try to calibrate connecting unit, reduce bend cam stress. High pressure

pipeline should cling vehicle body and fix well, and make some hoop part in

pipe in order to reduce vibration and reduce shape change that expand with

heat and contract with cold produced.

7. Low pressure pipeline

Low pressure pipeline inner diameter is 19mm. The length of rubber

pipe is with limit, can’t be too long.

8. Throttle valve body

Throttle valve body was installed on intake pipe of engine, control air

volume that enter engine cylinder, and make engine gain max. power. The

idling stepping motor on it controls intake volume of air when engine is

idling, the position sensor of throttle on it supplies signal for ECU that engine

is running.

9. Closed loop controlling system (ECU confects according to

different vehicles.)

Closed loop system is made up of closed loop controlling unit (ECU),

natural gas injection nozzle, the position sensor of throttle, RPM signal

sensor, water temperature sensor, intake pressure temperature sensor and

oxygen sensor.

E. Controlling system

A. Basic work principle:

Natural gas engine work principle is similar with gasoline

engine—firing combustion. The following instruction is movement principle

about the engine natural gas and ignition relative spare parts.

Electric controlling unit（ECU）check pulse chart in ECU and control

exactly injection gas pulse of engine and ignition advance angle by camshaft

position sensor signal, pressure temperature sensor signal, water temperature

sensor signal, oxygen sensor signal etc. of engine, meet current speed and

load requirements.

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ECU confirmed appropriate air & fuel ratio, control pulse width of

natural gas injection nozzle. In order to ensure appropriate mix ratio of air &

natural gas, all kinds of sensors supply feedback signal to engine controlling

unit in order to calculate injection gas pulse width of natural gas injection

nozzle. By measure intake manifold pipe pressure and temperature, and by

pressure &temperature sensor supplying load information that engines need,

camshaft position sensor supply RPM information of engine. Check pulse

chart in ECU by engine load and RPM, and gain controlling signal of engine

corresponding injection pulse width and ignition advance angle.

Camshaft position sensor supply camshaft position and engine RPM

information, these requirements that control natural gas injection nozzle and

ignition timing. Oxygen sensor, intake temperature and water temperature

sensor supply temperature information for correcting air & fuel ratio. It based

on all information from sensors, engine controlling element can calculate

basic pulse width of natural gas injection nozzle.

When ECU pass throttle valve body position sensor and gather signal

that close throttle valve body, and engine RPM is higher certain RPM, engine

is in speed-down state, natural gas injection nozzle stop supplying gas. When

RPM reduced lower fix RPM (it is related with engine working condition) or

stepped on accelerating pedal, then restore injection gas.

After vehicle circuit system connected (i.e. ignition key switched to

ignition position), already begin to supply 12V DC to ECU. At the same time

closed loop system controlling unit controls natural gas cut-off valve,

reductor electromagnetism valve opens instantly, exhaust air in air route, it is

convenient for engine to start. When oxygen sensor was heated to working

temperature, then the engine entered closed hoop controlling state. Under the

state, and engine is closed hoop system and ternary catalyst case action

together, exhaust gas emission can reach EURO III level.

Closed hoop electric controlling system is made up of controlling unit

（ECU）, sensor and executor (element).

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B. System assembly :

1. ECU 2. Electric source switching equipment 3. Ignition key 4.Battery 5.Oxygen sensor 6.Gas tin 7. Reductor 8.Natural injection nozzle 9. Ignition coil 10. Spark plug 11.Intake pressure temperature sensor 12. Throttle position sensor 13.Idling stepping motor 14.RPM sensor C. Controlling unit （ECU）

Engine controlling unit (Shortened:ECU) is the core parts of electric

controlling system, ECU continuous controlling and inspect engine running.

Controlling unit is made up of multi-grade electric source, signal packing up,

CPU central information treatment, integrated drive. So it is with high

precision controlling, rapid speed controlling, better real time, and working

reliability ect..

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2.1 ECU working principle drawing

2.2 ECU is with following function：

Engine ignition timing control, starting auxiliary and safety control,

battery low electric pressure compensate control, air condition hoisting

speed control, engine over-speed limit, system self-study, system failure

limping, system real time monitor.

Electric control unit by gather electric pressure signal of sensor can

measure engine working condition instantly, and make corresponding

reaction. At the same time electric controlling unit utilized natural gas

nozzle etc. output device, give response directly or indirectly to engine

work condition information that all kinds sensors sent. For example, if

oxygen sensors checked thick mix gas, then engine controlling unit may

directly reduce injection gas pulse width, if produced thinner mix gas, then

engine controlling unit may directly increase injection gas pulse width.

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2.3. Hardware resource is following in ECU:

16 bit CPU single CMOS CHIP

8KRAM

Flash program memorizer in 256 KB slice（12V programme

voltage ）

16 route 10 bit A/D convertor

8PWM output

CAN module （CAN2.0B）

2.4. ECU software structure was separated two parts for datum

treatment

Apply: A part of them used engineering parameters that sensor checked

to calculate controlling parameters of injection gas valve ignition coil &

idling stepping motor to control engine.

Basis: A part of them gathered datum from sensor and transform

engineering datum by applying, and parameters controlling executor of

software calculated and manage self-diagnosis program of all kinds of

sensors and executors, and also may communicate with out connecting ECU

diagnosis software by series ports failure diagnosis lines.

Operation system can ensure the incidents with related time (for

example: timing and delay management ) and angles managements properly

(be related with engine running orders), this management integrated in

software and calculated according to exact priority, even at high speed, also

can ensure engine priority managements, this kind of modularize structure

allow realize all kinds of the most flexible controls, at the same time don’t

damage system integrated characteristic.

The following gather datum were transferred ECU.

- Battery voltage

- Output voltage of electrical source convertor

- Absolute pressure and temperature in inlet manifolds.

-RPM signals/ top dead center

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- The position of throttle opening

- Coolant temperature of engine

-Oxygen sensor signal

-Air condition operation requirements

Inlet efficiency was gained that calculated by treatment absolute

pressure, inlet temperature, engine RPM and throttle position etc. signals,

thereby gained inlet volume in cylinder.

ECU interior electrical source modules control following functions:

- Open time controlling injection gas volume by controlling injection

valve

- Idling stepping motor

- Four high pressure output ignition coil

- Failure indicting light

- Electromagnetism valve

Technical parameters for electric controlling unit：

1. Working temperature：－40℃～＋85℃

2. Working electric voltage： 8V<V<16V

3.Atmospheric pressure of work：60KPa≤PA≤110KPa

2.5 Installing requirements of electric controlling unit（ECU）:

1.May be installed under instrument table in cab, but ventilation & dispersing

condition must be well, and there is no special requirements for installing

angles.

2.Controlling unit can’t be impacted.

3.ECU is with dampproof function, but can’t flush directly outer case of

controller by water.

ECU located under instruments in cab, adopted SMD technology, and

connected with harness by 80 stitches interfaces ECU dealt with signals from

all kinds of sensors and controlled executor in order to gain better running

conditions. Because used a lot of customize circuit with special function,

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integration function is strong, so make structures be compact quite, and size

reduced.

Installing criterions:

- ECU must be far from the places that water can spatter and

overheat, and cooling & dispersing are well.

- ECU must be protected by bracket.

- ECU tight bracket can’t contact with ECU metal back.

- Protect treatment of ECU tight bracket must ensure ECU

connecting ground.

If connecting ground is realized by ECU tight bracket, bracket must be

smooth, it is: metal connect ECU by electricity, the contact point with bracket

and the contacts between bracket and ground must ensure electricity contact

well(note: avoid to contact spare parts that were painted or spare parts that

have been pre-dust treatment.).

- ECU connection output end must lay downwards, prevent tie-in

of ECU side seep water.

- Let ECU tie-in insert & pull easily. (for example: must

consider harness length, ECU position etc.)

- Don’t make ECU approach electromagnetism interference

source for ever.(For example: high pressure coil, generator etc.)

2.6 ECU inspect interface

After make diagnosis debug software connect with system, can show

following datum that operators need:

Engine parameter:

Engine RPM, intake pressure, intake temperature, water temperature, oxygen

sensor, throttle, ignition angle, injection fuel pulse width, idling stepping

motor, negative pressure control, executor electric source, relay, air condition

refrigeration, voltage of electrical source, voltage of battery, failure indication

light etc.

Check interface is following:

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Detail instruction for interface:

RPM：Display current engine RPM 0～3500

Throttle position：Display current throttle position range 0～100

Water temperature：Display cooling water temperature of current

engine -30～150

Pressure：Display intake pressure value of current engine, display

current engine load 0～190

Oxygen ：Display oxygen content in exhaust gas of engine,

display thick and rare of engine fuel 0～850

Ignition advance angle：Display angle value from engine ignition to

T.D.C 0～40

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Injection gas width：Display duty-cycle that current engine natural gas

injection nozzle open

Stepping motor step: Display current stepping motor step, display

idling valve opening 0～250

Ignition advance angle +1：Plus, minus 1 degree on the base original

ignition advance angle

Injection gas pulse width：Plus, minus N on the base original injection

gas pulse width

N ：Input N value by manual keyboard

Reserve datum：Reserve inspecting datum that engine ran

4. Sensor

4.1 RPM sensor

RPM sensor signal is the main signal of electric control system, if there

is failure, engine will not run.

RPM sensor produces electric pressure to relative movement of flywheel

signal gear by inducing head, supplying ignition signal to ECU. RPM sensor

is made up of electromagnetism iron, high magnetic conductivity iron core

and helical coil in the iron core, when gear pan running on the signal pan

cuts to magnetic line of force on sensor iron core, magnetic flux happened

change on the iron core, sensor coil induction produced pulse electric

pressure, the electric pressure high & low is in direct proportion to RPM.

Technical parameter： Coil resistance （＋20℃）：860Ω±10﹪ Air gap ：1.2±0.2mm Signal voltage： ＞1750mV Work temperature: －40～＋150℃

The main technical parameter and principle drawing

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Installing type and corresponding wave shape drawing

4.2. Intake pipe absolute pressure/temperature sensor

Intake pipe absolute pressure sensor is ECU used to calibrate main

signal of engine supplying gas. According to engine load state, measure

vacuum change in intake pipe, and convert electric signal, decide basic

injection gas volume as electric control unit.

Pressure sensor is made up of piezoresistance bridge and temperature

compensating circuit. When felt pressure,

piezoresistance resistance happened change,

then produced an output signal that it is in

direct proportion to input pressure, and

proportionate with participating voltage.

4.3. Throttle position sensor

Throttle position sensor check opening angle of throttle.

Throttle position sensor was installed on the throttle flow valve body,

Technical parameter Pressure range：20KPa—190KPa Input pressure： 5.0V ± 0.5V

Working current: 9mＡ Temperature sensor resistance （when it

is 20℃ ）: 2.5K Work temperature: -40 --+125℃

(V)

( )

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connects with throttle rotating shaft and synchronization. There is a variable

resistance in throttle position sensor, the resistance was changed voltage

signal valve with throttle opening increasing and increasing, the changing

voltage value showed throttle current position and opening speed, and supply

to ECU and judge whether the current is idling working condition or

transition working condition to realize to control engine. When absolute

pressure sensor damaged or ECU system failure, combined with engine RPM

to convert standby program “limp” control, making driver drive to garage for

repair.

4.4 Water temperature sensor

Its function is: Make water temperature change convert change of resistance value, and supply to ECU by voltage. When engine located cool state, the signal was used to correct injection gas pulse width. Temperature changes from water temperature, also effect idling controlling valve position and ignition advance angle. ECU receives water temperature sensor signal, when water temperature is lower than 43℃, increasing natural gas supplying, make engine run speedup, and rapidly increasing temperature to warm engine. When water temperature is higher than 43℃, will restore normal natural gas supplying, make engine run normally.

Water sensor is a thermistor resistance model sensor(interior resistance change is contradiction to temperature change). When water temperature was increased, the resistance was reduced.

Work parameter: Electric angle range ： ＜９６degree Running direction ： random Resistance ： ２KΩ±２０﹪ Work voltage ： ５Ｖ Work temperature： －３０～＋１１０℃

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4.5 Oxygen sensor

Oxygen sensor used to check oxygen content of exhaust gas, and it is the

main element that ensure air & fuel ratio to approach theory air & fuel ratio.

Oxygen sensor was asked to install outlet 150～200mm from exhaust pipe to

exhaust manifold of ternary catalyst case pipeline.

By chemical reaction with exhaust gas, can produce voltage change at

the end of sensor, according to voltage change, ECU can adjust basic

injection gas pulse width, make air & fuel ratio of mix gas maintain near

theory air & fuel ratio. When mix gas is scarce, oxygen sensor will have low

electric pressure output, when mix gas is dense, oxygen sensor will have high

electric pressure output. There is a ceramic resistance model heater in oxygen

sensor case.

1.Oxygen sensor work temperature：350℃--800℃

2. Rated voltage：12—14V DC

E. Executor （Element）

5.1 Ignition coil

Dual ignition coil assembly was installed one body by two separate coils,

and electric source shares together. Supply high pressure electricity high

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energy for spark plug work. Every coil has two secondary output ends.

Separately using high pressure line in series formed loop with engine 1,4

cylinder, 2,3 cylinder spark plug, and formed high pressure ignition system.

Ignition was carried out on T.D.C of compress and exhaust at the same time.

Thereinto 90% energy was used to ignite mix gas (efficiency ignition), about

10% energy was used to ignite loop ignition (inefficiency ignition).

Secondary output for every separate coil only connected with two spark

plugs of corresponding cylinder sequence serial number. May exchange, but

can’t connect wrong, otherwise will cause disorder cylinders.

5.2 Natural gas injection nozzle

Natural gas injection nozzle was installed gas rail, ECU by special

driving circuit control, every natural gas injection nozzle is with one power

supply end, natural gas injection nozzle controlling end by ECU controls

opening of natural gas injection nozzle. ECU controls opening time of natural

gas injection nozzle, called “Injection gas pulse width”. Injection gas pulse

width based on all kinds input signals, and calculates by ECU.

Natural gas injection nozzle communicated with pressure gas source.

Before natural gas injects into intake valve of every cylinder from natural gas

injection nozzle, then enters into combustion chamber. Natural gas injection

nozzle depends on electromagnetism strength and spring strength, open and

close natural gas measure plunger. When coil in natural gas injection nozzle

electrify, it becomes an electromagnetic iron. Magnetic field that coil

produced overcomes enough spring strength, lift plunger. Leave the valve

Work parameter: Rated work voltage ：１２Ｖ

Limit work voltage：８Ｖ－１６Ｖ

Max. work current：９Ａ Hypo-grade output voltage：３５ＫＶ Elementary grade resistance ：０．５Ω±

Ｏ．Ｏ５Ω Hypo-grade resistance：

５２００Ω±３００Ω

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seat. When ECU cut circuit of natural gas injection nozzle, magnetic fields

disappear, spring strength forced plunger to seal the seat.

When open natural gas nozzle, because the pressure difference by

injection gas valve was fixed, and velocity of flow for natural gas was

invariable also, only opening time of natural gas injection nozzle is variable,

by opening time (injection gas pulse width) of controlling natural gas

injection nozzle, ECU supply less natural gas at the idling, or increase pulse

width to meet max. injection gas requirements at full opening throttle.

After injection gas valve matched controlling system, control the

switch by ECU emitting signal, make CNG fuel by relatively high supersonic

speed air flow speed timing inject into gas air flow that is entering into

cylinder. The injection gas volume adopted PWM pulse width modulating

mode, work frequency can reach 100 Hz, so ensure gas fuel to mix with air

flow, and carry out fuel delamination injection gas combustion, make engine

power increase, and reducing greatly engine displacement and fuel

consumption.

Structure & work principle of natural gas injection nozzle of electromagnetism:

Structure principle drawing of natural gas injection nozzle of electromagnetism

1.Valve body 2. O ring 3. Electromagnetism coil 4. End terminal 5. Armature subassembly 6. Valve seat 7. Steel ball 8. Return position spring 9. Spring seat

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Working principle of injection nozzle of electromagnetism natural gas: When injection valve don’t electrify, under return spring, ball valve located to close state, when electric controller drives module to emit driving current, ball valve open, natural gas injects into engine by ball valve.

Injection gas nozzle sketch map

Note：

1. Natural gas injection nozzle can’t fall off, otherwise it will damage.

2. Prohibit to make natural gas injection nozzle immerge lubrication

agent, prevent to block injection hole.

Technical parameter of natural gas injection nozzle：

1. Work voltage： 6V～14V DC

2.Coil resistance： 1.2Ω±0.2Ω

3.Work temperature：－40℃～＋125℃

5.3 Idling stepping motor

The idling stepping motor （±25r/m）of high precision, locating well

used to control idle RPM.: It directly fixed on the throttle body, it is made up

of stepping motor, screw/worm reductor, it can convert rotating moving of

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locking pin （3） to change linearity movement. After received ECU

controlling commands, stepping motor by screw/worm framework shaft

moved valve core (about 0.04mm/step), and changed by-pass intake volume

of engine idling, and confirmed idling steady. The change was adjusted

according to engine coolant temperature.

Intake efficiency of engine idling is: When producing, the throttle opening

by adjusting by-pass intake channel closing starts to calibrate.

Stepping motor directly connects with throttle body, don’t need to use

tightening bolts, and fixed on the throttle body by one rapid hoop.

The drawing as follows:

1. Idling stepping motor 5. Throttle body 2. By-pass pipe 6. ECU controlling unit 3. Lock pin 7. Steel check ring Qo. Air leakage volume of throttle Q. By-pass air volume of step motor

5.4 Impedance high pressure wire

High pressure wire make ignition coil produce hype-grade high electric

pressure transfer in turn ignition mixer of spark plug every cylinder. (Prohibit

to bend and break, circumgyrate and shake high pressure wire, avoid many

positions break of interior carbon center, cause resistance increase, then hit

insulation.)

Rated work resistance: 5K – 10K

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5.5 Spark plug

Installed on the cylinder head, under 35000 V voltage, produce high

energy spark, then ignition mix gas in cylinder of engine, make engine run.

Rated work resistance： 5.5K –10K

Standard clearance： 0.9mm—1.1mm

5.6 Pipeline entrance electromagnetism valve （High pressure）

When engines don’t work, close high pressure natural gas

Work voltage： 12V

5.7 Electromagnetism valve of reductor

When engines don’t work, close low pressure natural gas

Work voltage： 12V

5.8 Harness （Accordance to vehicle model and ECU work voltage

match ）

Make closed hoop controlling unit（ECU）by insert parts connect with all

sensor and execute parts, realize to transmit to controlling signal.

5.9 Electric source convertor

Make battery 24V voltage convert stable 12V voltage to supply for system.

Description：

1. Input electric voltage range 15～32V, all can work normally, green

light bright showed that electric source converted normal work.

2. Max. output current of electric source is 30A.

3. When output end shutoff or input voltage is low, red light is bright.

4. When work temperature is -40℃～85℃, all can work normally.

Installment：

-Electric source convertor should be installed

near ECU, and should be waterproof,

anti-oil on the installing position, and heat dissipation

well.

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-Indicting lamp and tie-in should be downwards, and tie-in inserts and pulls

easily.

- Case bottom should connect well to ground with the installing position.

- Installing should fasten, no loose.

Chapter Ⅶ Auxiliary System of Engine

A. Lubrication system

Lubrication system lubricates moving parts to reduce friction loss and wear. Besides, lu’boil also plays part of cooling, washing and sealing. Lubrication system consists of oil pump, oil filter, oil cooler, pressure control valve and pipe line etc. Details see forced lubrication system diagram of the engine.

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48

Chapter VIII Failure Diagnosis of Engine and Way of shooting

A. Ordinary failure and way of shooting (mechanism) 1. Ordinary failure diagnosis and shooting

Sort Phenomenon

Failure judgement and shooting

1.Electric system troubles a. Electricity is not enough, voltage is lower 18v. b. Contacting of battery connection iron is bad. c. Start motor existed failure. d. Ignition system existed failure. Way of shooting： 1）Check whether voltage is 20~24V or not, that supply to electric controlling ECU. 2）Check whether contacting is fasten or not at the two ends of ECU output signal line. 3）Check when starting motor to drive engine for running by timing ignition light, whether timing light blink or not, if blink regularly, showed that ignition system worked normally, if not ignition timing light, may pull high pressure line from cylinder, then install a spark plug, put on the engine, observe whether there is spark or not.

1 Start with difficulties.

2.Supply gas system failure: 1）Manual valve on store bottle closed. 2）Reductor or electric valve on the reductor damaged. 3）Electric pressure of electrical source is too low, can’t open electromagnetism valve on pipeline and electromagnetism valve on reductor, replace battery or charge for battery in time. 4）Electromagnetism valve connected with ground badly. 5）Fuel showing switch damaged or not turn to the “Open”, so make electromagnetism valve not open on the reductor. 6）High pressure pipeline blocked. Way of shooting： Slightly loose clip tie-in by wrench, if natural gas leakage, prove the front sect is good, check every sect one by one. 7）Low pressure pipeline bent or broke. 8）Air filter is too dirty.

2 Idle Speed Is Unstable

1. Reductor seal is not tight. 2. Check whether tightening bolt on the mixer was loose or not, check every positions between mixer and inlet pipe leaked or not.

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3 Engine run is unsteady.

1. The T.D.C. signal on the first cylinder is improper. 2. The RPM signal is improper. Way of shooting： Check or rep lace sensor. 3. Sensor signal of intake is improper. Way of shooting： Check or replace sensor. 4. Temperature of reductor is too low. 5. Reductor work is abnormal, repair or replace. 6. Cylinders flee： Way of shooting： Check cyl inder head bol ts , i f necessary, rep lace cyl inder head gaske t and check ext rus ion height on cyl inder top sur face of cy l inder bush shoulder and he ight d i ffe rence

4 Power isn’t enough, sudden fall of power and natural gas consumption is increasing

1.Low pressure pipeline bend (Tidy up) 2. Low pressure pipeline is too long.(Adjust) 3. Ignition system energy is not enough. 4.The contacting place between high pressure line and high pressure bag is bad. 5. The contacting between high pressure line and spark plug is bad. 6. There is one or a few cylinder misfire in some cylinders. Treatment methods of item 3、4、5、6: 1）Pull out spark plug, observe electrode top whether there is ablated mark, if there is, replace spark plug. 2）Measure resistance of high pressure line by multimeter （XKΩ grade）, if turnoff, replace high pressure line. 7. Compress pressure of cylinder is not enough (Check & adjust valve clearance and check & replace piston ring.) 8. High pressure pipeline blocked or distortion (blow, sweep or tidy up) 9. Too dirty or leakage change vacuume(Check & repair or clean air filter.) 10.Mixer seal is not tight (replace). 11.The joint of mixer and throttle leaked.(Tidy up) 12. Reductor flee or membrane broke (Repair or replace reductor). 13. Check whether natural gas meet requirement or not. 14、Quantity of heat for reductor is little. Check whether connection of inlet & outlet water pipe reductor is right, tough reductor case by hand, if water circulation is smooth, hand will warm, otherwise check whether waterway is blocked.

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5 Engine stopped suddenly

1.Fuse slice is burnt. 2. Manual switch of fuel conversion switch contacts badly. 3. Connected iron badly. 4. Water circulation in reductor caused to ice block. Way of shooting： Make water circulation smooth. 5. Reductor low pressure chamber leakage gas or membrane broke, repair or replace. 6. Air filter leakage or too dirty, should check & repair or clean.

6 Operation with abnormal noise

1. Early ignition, brings about deflagrating. 2. Late ignition, brings about mix gas continue to combust in exhaust pipe or mix gas backfire. Way of shooting： Adjus t t ime of ign i t ion 3. Large clearance between piston and cylinder liner causes striking noise in cylinder which becomes lower when engine heat. 4 . Large clearance between piston pin and pin hole cause light and sharp noise which becomes clearer when at idling 5. Large clearance causes between main bearing and connecting rod bearing causes parts striking when engine’s speed sudden drop. The noise loud and strong when engine runs at low speed. 6. Large crankshaft axial clearance causes crankshaft floating front and end striking noise at low speed. 7. Valve spring broken, large valve clearance causes un-orderly noise or light rhythmic knocking sound near cylinder head. Way of shooting： Replace parts, ensure specified clearance 8. Piston strike cylinder head causes metal striking noise near cylinder heat at low speed. Way of shooting： Checking piston and valve whether touch each other and further checking gears timing mark 9. Large gear clearance because of wearing causes striking in gear box at speed sudden drop. Way of shooting： Replace gears.

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7 Excessive oil temperature

1. Check whether instrument is normal. 2. Excessive load. 3.Engine oil shortage or excess 4. Excessive blow-by Way of shooting： Replace piston ring or cylinder liner. 5. Engine oil cooler blocked, improper oil temperature controlling valve, and out shell clogged by dirt

8 Low oil pressure

1.Manometer or induction plug damage or disconnection. Way of shooting ： Change the manometer or induction plug and check circuit. 2. Oil shortage in oil pan Way of shooting： Fill oil to specified level 3. Oil pump gears worn out. Way of shooting： Change oil pump. 4. Oil screen or oil filter clogged 5. Pressure control valve and by-pass valve spring broken or valve seized 6. Oil line clogged or leak. Way of shooting： Replace spare parts.

9 Excessive temperature of cooling water from engine

1. Temperature gage or induction plug damage. Way of shooting： Check and rep lace 2. Water shortage 3. Excessive load.

10 Troubles of alternator

1. Not charge completely 2. Insufficient charge 3. Excessive charge 4. Unsteady charged current Way of shooting： These four problems can be solved according to the feature of different model of alternator.

11 Troubles of starter

1. Starter fails to rotate 2 .Sta r te r id l ing s ta r t wi thout s t rength . 3. It’s difficult to return the original position for gear. Way of shooting：Check whether battery voltage and all connections are well, and judge whether it needs to replace.

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2.Routine checking process for natural gas equipment

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B. Ordinary failure and way of shooting (Electric controlling) 1. Note items when shoot failure: Failure diagnosis note items about electric controlling natural gas injection system: 1.When operate and maintain engine, pay attention not to make water splash harness of electric controlling system and sensor, cause short circuit. 2.During disassembly, must connect every interface well, and seal well. 3.Failure of wire and wire interface: It’s mainly shutdown and short circuit.

Shutdown: It is due to wire broke and bad connection. Broke commonly is on the connection position, so must carefully check wire connection position. If bad connection, may cause terminal oxidation and enter into eyewinker.

Short circuit was caused by wire and vehicle body join iron or short circuit in switch. Check whether it is short circuit between wire and vehicle body, should check whether there is wire card in vehicle or there is friction with vehicle body and vehicle frame, make insulation layer damage, so electric leakage. 4. When check circuitry shutoff failure, should first turn off electric controlling unit (ECU) and relative interface of sensor, then measure resistance that connect terminals, then confirm whether shutoff or badly contact.

Maintenance note items about electric controlling natural gas injection system: 1. In spite of engine run or not, as long as during ignition switch connected, can’t insert and connect any elements in system, for example: any cable of battery, idling controlling valve, natural gas injection nozzle, ignition system wire, electric controlling unit (ECU) circuitry, and air condition circuitry etc. 2. If want to check high pressure ignition circuitry, must first cut off fuel route and waiting for checking some circuitry, then start engine again.It isn’t permited to cut off high pressure or low pressure ignition circuitry during engine in operating. 3. Before weld circuitry of vehicle, must take off battery and connection wire of the system. When use arc welding on the vehicle, can’t be close to electric controlling unit (ECU) and sensors. 4. Check multi-meter of sensor & electric controlling unit(ECU), and electric resistance of indication light must hyper 10K, otherwise will damage sensor and electric controlling unit (ECU). 5. Generally reliability of electric controlling system spare parts is higher, when found abnormity, first check relative electromechanical spare parts/ system connection & inserting parts/ harness etc. parts , before confirm electric controlling spare parts damaged, should repeat to replace and check. 6.Pull out high pressure wire, start engine, check spark plug whether it operates or need rotate engine to check sensor, but can’t start, must turn off electric source of electromagnetism valve on reductor, because engine running, it produced RPM signal, electric system will drive high pressure

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entrance electromagnetism valve and electromagnetism valve of reductor to open, natural gas that didn’t combust entered into cylinder, then discharged, stored in exhaust pipe and muffler, once engine operate, natural gas was ignited and exploded that was stored , will damage exhaust pipe and muffler. 7.When battery voltage is not enough or starter failure, can’t start engine by outside force for a long time. Because system electrified, if received engine running signal, high pressure entrance electromagnetism and electromagnetism valve of redcutor will open at once, natural gas enter into cylinder, if can’t start for a long time, non flaming natural gas stored in exhaust pipe and muffler, once engine work, natural gas was ignited and exploded that stored , will damage exhaust pipe and muffler. 8. System should use anti-jamming spark plug and high pressure wire, non-impedance spark plug and high pressure wire will produce bad influence to driving module ignition coil in ECU, even damage ECU. 9. Most of vehicle electric spare parts can’t repair, after replaced, checked and confirmed spare parts damaged, should adopt to replace.

2. Failure shooting

2.1 Simply check up 1.Whether electric source is normal or not, working voltage is normal or not. 2.Whether natural gas store is enough or not, and whether

electromagnetism valve of gas tin open or not. 3.Whether entrance and electromagnetism valve of reductor opening is

normal. 4.Whether high pressure electricity is normal (spark plug). 5.Whether RPM sensor signal is normal or not. 6.Observe exhaust gas emission (odor, color, sound, feeling). 7.Summary cases, make checking range shrink to the one object or parts. 2.2 Substitution methods for checkup 1.Change doubting failure elements by the same model new elements, run

engine to observe. 2.Failure disappear, make failure elements exchange, run engine to

observe. 3.Failure appeared again, confirm failure elements damaged, so change them by good same model elements. 4.Integrating failure, first shorten lookup range, then check by substitution

methods. 2.3. Checking program of closed loop system status A. Static test Cool engine, electromagnetism valve of store tin close, electric switch

turn to the “ON” position, engine is static. Check items system state and limit

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1. Reductor electric valve After opening 3 seconds, should close automatically.

2. Battery voltage 12 v 3. Temperature sensor environment temperature 4. Absolute pressure sensor (display value) about ~160 5. Throttle position sensor (display value) all close 10

all open 98 B. Electric switch turn to the “OFF” position System state check programme 1 Electromagnetism valve all close natural gas no leakage 2 ECU and all executor voltage OV C. Run test System state check programme Start generator (When start, don’t start operate any mechanism and throttle on engine)

Check items system state and limit 1.Electromagnetism valve open 2.Start time < 8S 3.Start RPM at normal temperature < 200~300/ r/min 4.After start at normal temperature, idling RPM 650~750/r/min D. Idling check---low idling System state check programme (After start, pre-heat engine to reach normal water temperature) Check items system state and limit 1.Throttle position (display value) 20~ 24 3 Voltage (display value) 100~125 (23v~26v) 4.RPM 650±30r/min 5. Ignition advance angle 8º~14º 6. Absolute pressure sensor (display value) 40~60 E. Idling check- high idler System state check programme (After start, pre-heat engine to reach normal water temperature) Check items system state and limit 1. RPM (display value) 1500 ±50r/min 2. Throttle (display value) 10~15 3. Voltage (display value) 110~130 (10~12v) 4. Ignition advance angle 20º~30º Observe by computer and check engine running state: 1. Make communication line connect with communication faucet 2. Turn on ECU inspecting interface on computer 3.There are many group data displayed on the top interface, under static working condition, observe data change, then can know about running of

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engine, the displayed value is real time data at present. 3. Failure instrument diagnosis Ordinary failure diagnosis

Failure phenomena Check methods Check electric source and grounding lines whether it is normal or not. Check electric source by communication whether it is normal or not.

Abnormal

Whether checking ECU insert parts fasten or not.

Ignition switch to “ ON ”，whether system electrical source is normal or not.

Normal Whether checking natural gas electromagnetism valve or not. Whether checking communication connection is normal or not. Judge it with another ECU.

Abnormal

Change the other communication line to judge.

Whether communication is normal or not.

Normal Observe and judge by communication interface. Whether check RPM sensor connection is normal or not. Whether check sensor clearance is big or not. Whether sensor damage or not.

No

Judge it with another ECU.Whether observing RPM is too low or not.

Whether has RPM signal or not

Yes

When have RPM, to observe whether natural gas electromagnetism valve opens or not.

Unable start

Whether has fire or not.

No.

Check ignition coil whether the connection is normal or not.

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Judge it with another ECU. Judge it with another ignition coil.

Yes Check whether spark plug, high pressure connection line is normal, wrong injection order or not. Check whether there is gas in gas storage or not. Check whether every electromagnetism valve in pipe is normal or not.

No.

Check whether fuel controlling valve can open normally or not

Whether has fuel or not.

Yes Observe when start, whether oxygen sensor display too scarce or not.

RPM sensor whether clearance is too big or not, and so make RPM signal not continue.

Check whether electric source line, ground line connection is reliable or not. Check whether high pressure line is right with every cylinder connection.

Can’t start and explosion in exhaust pipe with backfire.

Check whether pipe high pressure electromagnetism valve and injector open normally or not.

Check idling controlling valve connection is reliable or not. Check whether idling controlling valve movement is right or not.

Check idling controlling system

Observe whether throttle valve position signal is fluctuate or not with inspecting program.

Check natural gas system

Observe whether it is too scarce or too thick with inspecting program. Check ignition coil, high pressure line whether there is electric leakage or not. Check spark plug clearance.

Idling unsteadily

Check ignition system

Check whether spark plug damage or not.

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Observe whether throttle valve position sensor signal is too big with communication inspecting program, and check whether throttle valve return to the original position or not.

Check whether there is leakage in the inlet pipe.

Too high idling

Check whether idling controlling valve can’t move. Whether inlet/exhaust system block or not. Check whether idling controlling valve move or not.

No idling

Too low idling Observe whether oxygen sensor display too scarce or not. Check whether natural gas storage is sufficient or not. Check whether air filter block or not. Check whether exhaust system block or not, such as: ternary catalyze equipment burnt oil or crashed, so blocked.

Accelerate Incapability

Check whether natural gas, ignition system is normal or not.

Slightly lost fire

Check whether every spark plug clearance is in the range or not, the clearance should be same.

Whether natural gas is too scarce. Backfire Whether RPM signal, ignition system is normal or not. Whether electric source, ground line connect well or not Explosion in

exhaust pipe Whether ignition system is normal or not. Check whether natural gas leak or not. Check whether valve clearance is normal or not. Check whether oxygen sensor damage or not, fuel controlling valve damage or not.

Gas consumption extremely high Check ignition system is normal or not.

Before test, high speed run engine several minutes, first do high idling test, last do low idling test. Observe oxide sensor display data, if fluctuate is abnormal, check valve clearance, every cylinder pressure. Check whether engine water temperature and water sensor is normal or not.

Idling exhaust abnormal

Check whether every insert parts connection is credible or not.

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Appendix I Meaning of the unit symbols used in this Manual and its conversion

Item Unit symbols Conversion

power kW 1 kW=1.36 Ps Torque N.m 1 kgf.m=9.81 N.m Speed R/min Oil/fuel consumption

G/kW.h 1 g/Ps=1.36 g/kW.h

Swept volume L 1 L=1000 ml Area Cm2 1 m2 =10000 cm2 Pressure KPa

MPa 1 kgf/ cm2=98.1 kPa=0.0981 Mpa

Force N 1 kgf=9.8 N Length m 1 m=1000m Time Min(s) 1 min=60 s Temperature K(ºC) 273 K=0 (ºC) Voltage V Current A Crankshaft angle ºCA Mass g 1 kg=1000 g

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Appendix II

Character compare between gas fuel and petrol Liquefied petroleum gas

Combustion type Character

Methane (Natural gas) Dimeth

ylmethane

Butane Gasoline

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Liquid density /kg.m-3 424 528 602 750 Gas relatively density 0.715 2.02 2.598 2.081 Boiling point/ ° C（0.1MPa）

-162 -42.17 -0.5 30~90

Vapourization carburate & latent heat (boiling point and below 0.1013MPa/k)\ (kj/kg)

Vapourization carburate

510 427.1 386.0 367.6

20°C 0.817 0.201 Steam pressure / MPa 50°C 1.71 0.481

Liquid state 49000 46099 45458 43900

Low heat value (0.1013 Mpa15.6 ° C)/ (kj/kg) Gaseo

us state

88388 115561

Self-ignite point (in air)°C 540 450 365 390~420

Ratio between air and fuel on theory (quality ratio )

17.25 15.65 15.43 14.8

Octane rating RON ＞120 112 95 92 Upper limit

15 9.5 8.41 7.6 Percentage for explode limit/volume Lower

limit 5.0 2.37 1.7 1.3