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Engine
Operation &
Construction
History
1876 - Nikolaus Otto, working with Gottlieb Daimler
developed the four-cycle engine. (Otto Cycle)
1893 – Rudolf Diesel patents the compression
ignition engine. (Diesel Engine)
1902 – Daimler-Mercedes begins production on
the first gasoline powered car
One of the FIRST!
Where we use them
Brainstorm
Basic Engine Operation & ConstructionPurpose of an engine - To create power for a specific use!
Use for What?
How do you create Power?
A Potato Gun !!! How does it work!!
What are other uses for straight line power ?
Easy !!
Rotary Power is more useful !
Purpose of an Piston type engine - To create power for a specific use and
convert reciprocating power to rotary power
Basic Engine Operation & Construction
Converting reciprocating power to rotary power is done with three basic parts
It’s just like
riding a bike !
External Combustion or Internal
CombustionCombustion: the act or process of burning, creating pressure for a specific use!
External Combustion: Pressure/Power created outside of the engine
Ex: Steam Engines
The slide valve allows high-pressure
steam to act alternately on both sides
of the piston
Internal Combustion: Pressure/Power created inside of the engine
Ex: Four Stroke Engines
External Combustion or Internal
Combustion
Pull a tiny amount of high energy fuel into a small space (INTAKE),
COMPRESS it to an even smaller space, ignite it & BOOM!
The POWER stroke takes place and EXHAUST is forced out of the cylinder
Creating Internal Combustion
Vacuum – Low Pressure Area, air/fuel moves “High to Low”
Intake Valve Opens while piston moves
down creating a low pressure area
(vacuum) inside the cylinder pulling in
an air/fuel mixture
INTAKE STROKE
Creating Internal Combustion
Compressing the
A/F mixture
makes it more volatile!
Why?
Compression Creates
-Energy
-Heat
-An super active
A/F mixture
Compress the A/F to much add !
Pre-Ignition!
COMPRESSION STROKE
Creating Internal Combustion
Spark plug Ignites A/F mixture
A/F mixture starts to burn
Burning gases force the piston down in the cylinder
Combustion completes
POWER STROKE
Creating Internal Combustion
Start Over! How?
Remove the burnt
A/F Mixture via pressure
Done!
EXHAUST STROKE
Welcome to the Four Stroke
Cycle
Intake Compression Power Exhaust
What were they again?
Basic Engine Terminology
The Four Stroke Cycle
Intake - Intake valve opens, piston travels from TDC to BDC, creating
a vacuum, drawing in air/fuel mixture into the combustion camber.
Intake valve closes.
Compression - Both valves closed, piston travels from BDC to TDC
compressing the air/fuel mixture. A volatile mixture, and heat are
created.
Power - air/fuel mixture is ignited and begins to burn, and expand.
the pressure forces the piston down from TDC to BDC causing the
crankshaft to turn.
Exhaust - exhaust valve opens, piston moves from BDC to TDC forcing
out the burnt gases remaining from the created power. Exhaust valve
closes
CYCLE REPEATS
Connecting Rod: Connects the piston to
the crankshaft
Crankshaft: Converts the vertical motion of
the piston into usable rotary motion
Parts
Piston: Moves up and down in the cylinder to
pump air and fuel into and out of the motor
Valves: Open and close to allow air and fuel
into and out of the motor
Parts that make you go
Hmmm.
Camshaft: Moves the valves up and down
which opens and closes them.
Cylinder Head: Holds the valves in place,
provides a spot for the spark plug, controls combustion, and helps cool the engine.
Parts
Engine Classification
Number of Cylinders:
Cylinder Arrangements:
.
Number of Cylinders & Cylinder Arrangements
Inline V-Type Opposed / Boxer
1, 2, 3, 4, 5, 6, 8 2, 4,6, 8, 10,12, 16 2, 4, 6
Cylinder Numbering
Firing Order: the order in which each cylinder begins its power stroke
Other Piston Cylinder Arrangements
Radial W12
Rotary / Wankel
Other Engine Types
Other Engine Types
Rotary Combustion
Basic Operating Principles – Stages
Stage 1 - rotor clears intake port, chamber
increases in size, creating a vacuum
drawing in A/F mixture
Stage 2 - rotor continues to rotate, intake
port closed off, chamber begins to
compress A/F mixture
Stage 3 - A/F mixture ignited by spark
plug, burning creating power against
rotor continuing rotary motion
Stage 4 - turning rotor uncovers exhaust
port, forcing out exhaust gases as chamber
is decreasing
STAGES REPEAT
Other operating principles
- Three chambers acting at the same time
doing different stages
- Some motors with two rotors therefore six
power thrust for one revolution
- Power to crankshaft done with gears on an
eccentric
- 3 to 1 ratio of rotor to crankshaft rotation
Other Engine TypesRotary Combustion
Other Engine Types
Rotary Combustion
Advantages
- fewer moving parts
- less power loss to friction
- 1/2 size / hp of piston engine
- almost vibration less
- quite running
- great acceleration
- constant torque
- high RPM obtained
Disadvantages
-rapid wear of appex seals
- repair costs
- poor fuel economy
- high in air pollutants
Other Engine Types
Rotary Combustion
Turbine / Jet engines
Engine Classification
.Number of Cylinders:
Cylinder Arrangements:
Valve Train Types:
Valve Train Types
T Head
F Head
L Head
I Head
How valves Open and Close
Briggs & Stratton L Head Design
Mechanically with
A Cam Lobe
Valve Timing with gear ratio’s
1 : 1 1 : 2
Camshaft CamshaftCrankshaftCrankshaft
How valves Open and Close
DOHCDouble Over Head Cam
Overhead Camshaft
Engine Classification
Fuel Types / Systems:
.Number of Cylinders:
Cylinder Arrangements:
Valve Train Types:
Fuel Types
Gasoline
Propane
Natural Gas
Alcohol
Diesel
Advantages Disadvantages
- different octane levels
- availability
- highest polluting
- cost
- low polluting
- power loss 10%
- availability
- cost, cheapest
- very low polluting
- power loss 20%
- availability
- carrying danger
- high octane
- Very low polluting
- high cost
- poor fuel economy
- cost, better fuel economy
- lots power/torque
- long lasting
- high polluting
- engine cost
- noise / low RPM
Carburetion – Air passes through a Venturi
which causes an area of low pressure. The fuel is
drawn into the Venturi where it mixes with the
moving air.
Fuel Systems
Low Pressure Area
Carburetors are “oldschool” Carburetor Video
Mechanical Fuel Injection – Only used in very
early gasoline engines (1957 Corvette) and most diesel engines
Computer Controlled Injection – Fuel is regulated
by a computer and an array of sensors
Fuel Injection
Fuel Injection Video
Fuel Injection is Nice
Engine Classification
Number of Cylinders:
Cylinder Arrangements:
Valve Train Types:
Cooling / Ignition Types:
Fuel Types:
.
Cooling System / Ignition Type
Air
CooledSpark
Liquid
CooledCompression
Engine Classification
Number of Cylinders:
Cylinder Arrangements:
Valve Train types:
Cooling System:
Fuel Types:
Other Engine Types:
Other Engine Types
Diesel Engine
Diesel Fuel oil – by product from the crude oil refining process.
- rated by cetane number, difficult to ignite
Intake
Air Only
Compression
Air Only
Creating Heat
Power
Hot Air Ignites
Injected Diesel
Exhaust
Burnt A/F
Pushed Out
Other Engine Types
Diesel Engine
Diesel Injectors must:
-Enter correct amount of fuel
-Be at the right time
-Control the rate of fuel
-Start and stop abruptly
Advantages
- cost, better fuel
economy
- lots power/torque
- long lasting
Disadvantages
- slow acceleration
- low RPM
- engine cost
- fuel system repairs
- noise
Other Engine Types
Two Stroke Cycle
Basic operating principles
- similar to a 4 stroke, operating principles of Intake, Compression, Power
and Exhaust.
- the above principles are completed in two strokes instead of four, stages
are combined
How do you combine
4 strokes into 2?
Intake Compression Power Exhaust
Other Engine Types
Two Stroke CycleIntake
Compression
Intake
- intake port is cleared by the piston
- Air/Fuel mixture is pushed into
the combustion chamber.
Compression
-only occurs for aprox. 1/2
of the piston movement up
Other Engine Types
Two Stroke Cycle
Power
Exhaust
Power
- only occurs for aprox. the first 1/2 of the
piston moving down.
CYCLE REPEATS
Exhaust
- exhaust port is cleared by the piston.
exhaust to escapes from the pressure
of the power stroke
Other Engine Types
Two Stroke Cycle
Other Operating Principles
-A/F/Oil mixture is
drawn into the
crankcase by a
vacuum as the piston
moves up during the
compression stage
As the moves down on the
power stage, pressure is
created in the crankcase,
therefore forcing the A/F/Oil
mixture into the combustion
camber
How is the A/F pushed into the combustion camber?
Other Engine Types
Two Stroke Cycle
Disadvantages
- high wear rate
- low torque
- lubrication needs to be mixed
or injected
- high in pollutants
Advantages
- less moving parts,
no valves
- runs at any angle
- high revving
- fast acceleration
Other Engine Types
Two Stroke DieselSimilar operating principle of the two stoke gasoline engine.
However: the crankcase is not used to create pressure!
Air is forced by a blower!
Other Engine Types
Two Stroke Diesel
Disadvantages
- engine cost
- fuel system repairs
- noise
Advantages
- better fuel economy
- lots power/torque
- long lasting
- less moving parts
- higher revving
- faster acceleration
