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Performance CUSTOMER MAGAZINE COMPONENTS AND SYSTEMS FOR THE ENGINE AND ITS PERIPHERY 2013

STRONG AND LIGHT:

NEW PISTONSFOR MODERN COMBUSTION ENGINES



2 MAHLE Performance 2013

CONTENTS

NEWS BRIEFS

MAHLE + Behr = Mehr (More)

ENGINE SYSTEMS AND COMPONENTS

Strong and light: new pistons for modern combustion engines


Light and cooled: valve technology for optimized thermal management


Versatile and resistant: oil control r ing for high-performance,

friction-optimized engines

FILTRATION AND ENGINE PERIPHERALS

High-efficiency water separation system: active fuel prefilter module

for diesel engines used around the world


Higher torque, lower consumption: air intake module with integrated

cascaded charge air cooling


Replacement for petroleum: bio-based raw materials for air duct components


Simple construction, significant effect: controlled mechanical

coolant pump for shorter engine warm-up phases


Synthetic and stable: spin-on oil filter for modern downsizing engines


With and without activated carbon: new filter media for cabin air filters

MAHLE POWERTRAIN

For more effective component design: new measurement methods

of valve temperatures

IMPRINT

Published by MAHLE International GmbHPragstrasse 26 – 4670376 Stuttgart/Germanywww.mahle.com

Responsible for contents

Arnd Franz

[email protected] +49 711 501-14612Fax +49 711 501- 4414612

Photography/picture creditsMAHLE GmbH, Stuttgart/Germany

Design & productionfreelance project GmbH,Stuttgart/Germany

Reprint, even partially, onlyin accordance with and afterauthorization by the publisher.© MAHLE GmbH, 2013

MAHLE Performance—also as continuously updated version online:

www.performance.mahle.com

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MAHLE Performance 2013 3

EDITORIAL

Ladies and Gentlemen,

The widespread use of direct injection

and turbocharging, as well as the product

technologies influenced thereby, in gasoline

engines in Europe is now seeing ever greater

acceptance also in other world regions. The

trend toward engine downsizing is continu-

ing. As a key supplier, MAHLE plays a lead-

ing role in the development of new materials,

innovative product designs, and excellent

manufacturing processes as a partner to our

customers in the engine and automotive in-

dustry—both today and in the future. In the

crank mechanism, valve train, air supply, and

in oil and coolant management, MAHLE

components ensure advancement in termsof consumption, emissions, reliability, perfor-

mance, and durability of modern assemblies.

More and more customers are counting

on MAHLE’s overall technical expertise for

modules or systems, including its support in

the development and testing of complete

engines.

In this edition of MAHLE Performance, we

would like to present the most important

innovations and achievements from our de-

velopment work in seven R&D centers

around the world. MAHLE pistons together

with complementary MAHLE piston rings will

make a significant contribution to achieving

higher power density and thermomechanical

loading while simultaneously optimizing

weight and reducing CO2, such as is the

case with the EVOLITE® pistons presented in

this edition. For diesel engines, steel piston

concepts are gaining in significance. MAHLE

offers various concepts for passenger car

diesel steel pistons, such as MONOTHERM®, TopWeld

®, and MonoGuide

®, which generate

considerable reductions in consumption for

engines with not only gray cast iron but also

aluminum blocks. This is achieved by opti-

mizing friction and, in particular, thermody-

namic advantages. Valves have represented

another focus of development in order to ac-

commodate the higher exhaust gas temper-

atures and to make an active contribution to

Arnd Franz

Member of the Management Board,

Automotive Sales and Application Engineer ing,

Business Unit Aftermarket

thermal management in the cylinder head

with EvoTherm® and TopTherm

® valves.

Further substantial challenges await in

thermal and liquid management. MAHLE is

pursuing a comprehensive strategy of incor-

porating various relevant aspects relating to

feeding, cooling, and filtration of the operat-

ing media in modern gasoline and diesel

engines. The application of the patented

MAHLE pump technology has recently been

expanded to controlled mechanical coolant

pumps, once again with the ultimate goal of

increasing efficiency and reducing consump-

tion. The increasing global use of passenger

car diesel engines, even in countries with

irregular fuel quality and high water content,is being addressed by MAHLE with a new

fuel prefilter module that sets new standards

in fuel filtration with active high-efficiency

water separation.

The growing significance of thermal manage-

ment in modern engine technology is ex-

pressly taken into account through the

completion of the majority acquisition of

Behr. Together, MAHLE and Behr will be a

leading technology partner to all of our cus-

tomers’ thermomechanical tasks in diverse

combustion engine applications, including

hybrid forms. Joint projects that have already

advanced to series production, such as indi-

rect integrated charge air coolers, document

the vast potential of this technologically as

well as commercially fascinating alliance that

serves to benefit our customers in all auto-

motive markets around the world.

We look forward to continuing our close

collaboration with you.

Arnd Franz




MAHLE has taken over a majority share

in Behr. Behr is becoming part of the

MAHLE Group—two globally renowned

automotive suppliers with rich tradi-

tions will pursue a common goal in the

future. The companies fit together per-

fectly: they are each worldwide leaders

in their respective fields and can look

back on a company history rich in tradi-

tion. Above all, however, their product

portfol ios complement each other very

well—particularly in the promising area

of energy-efficient mobility.

The motto for this integrat ion is “MAHLE +

Behr = Mehr (More)”—which is not just an

empty slogan. The equation yields more at

the bottom line than the sum of its parts.Nevertheless, for orientation purposes we will

start with a simple addition of the figures.

Number four in the industry

in Germany

Around 17,300 employees work at Behr in

a global network of 38 production locations

and research and development centers.

MAHLE employs almost 48,000 people at

over 100 production plants and seven re-

search and development centers worldwide.

In 2012, Behr had sales of about EUR 3.6

billion, while MAHLE recorded around EUR6.2 billion.

The Group will thus have approximately

65,000 employees going forward and gener-

ate sales of about EUR 10 billion at around

140 locations. This will elevate MAHLE to

number four in the industry in Germany.

MAHLE + BEHR

= MEHR (MORE)




NEWS BRIEFS

Innovation leader

Behr has specialized in vehicle air conditioning

and engine cooling and is among the global

OEM leaders for passenger cars and com-

mercial vehicles. In the last years, engine cool-

ing has been further developed to become a

dynamic thermal management system, which

regulates the heat flows in the vehicle as re-

quired—an important contribution to ensure

compliance with the stringent emissions and

consumption legislations. A similar trend is

seen in air conditioning, with which nearly all

vehicles are equipped nowadays. New areas

of application result from air conditioning in the

powertrain, such as cooling sensitive lithium-

ion batteries. All of these Behr activities will

be integrated into the MAHLE Group as part

of the Thermal Management business unit.

With its business units Engine Systems and

Components as well as Filtration and Engine

Peripherals, the MAHLE Group ranks among

the top three systems suppliers worldwide.

The complete range of MAHLE’s industrial

activities are combined in the Industry busi-

ness unit. The Aftermarket business unit

serves the independent spare parts market.

BUSINESS UNITS PROFIT CENTERS

Mechatronics

Engine

Systems and

Components

Filtration

and Engine

Peripherals

Thermal

Management

Aftermarket Industry

Engineering Services

Sintered Components

Motorsports

and Special Engines

Small Engine

Components

As a result, MAHLE and Behr provide pas-

senger car and commercial vehicle custom-

ers around the globe with technologies and

products that offer significant potential with

respect to CO2 and energy efficiency, and that

contribute to safe, comfortable, and ecologi-

cally sustainable mobility. Their bundled ex-

pertise also opens up new perspectives for

research and development. Best example:

the continued success story of integrated in-

direct charge air cooling (see Page 16).

Aftermarket

Not only can MAHLE and Behr mutually

benefit when it comes to OE customers, but

they can also do so in the independent spare

parts business. With its thermostats, for

example, Behr Thermot-tronik (BTT) hasproducts in its portfolio that are in demand

around the world. MAHLE possesses vast

experience and a strong sales network. From

now on, BTT will therefore concentrate on

development and production. Logistics and

packaging were transferred to the MAHLE

Aftermarket logistics center in Schorndorf/

Germany. The key advantage for the cus-

tomers: the thermostats can now be collated

with MAHLE products on one invoice and in

one delivery. Furthermore, MAHLE can de-

velop an expanded range of products for

workshop equipment.

Personnel development and recruiting

Since 2012, further training and personnel

development activities for executives and

talented recruits of MAHLE and Behr have

already been interlinked. With the MAHLE

Talent Management System, the Group avails

of an instrument that makes it possible to

bundle all relevant information worldwide.

The promotion of young talent has always

been an important topic at both companies,

as evidenced particularly well by Formula

Student. For a long time, Behr and MAHLEhave supported the competition for up-and-

coming engineers with “fuel in their blood.”

Now they are pursuing common goals in

sponsoring and present themselves as an

even more attractive partner for teams.

The MAHLE Group structure with the new business unit Thermal Management




STRONG AND LIGHT:

NEW PISTONSFOR MODERN COMBUSTION ENGINES

The thermal and mechanical loads on

pistons in modern gasoline and diesel

engines have seen a massive increase,

primarily due to higher levels of specific

power output. Furthermore, the pistons

are intended to increase engine efficien-

cy, for example through reduced weight

and friction. MAHLE has thus developed

pistons for both types of combustion

that increase load capacity and contrib-

ute to reduced fuel consumption.





The mechanical and thermal loads that act

on a piston are largely determined by the

combustion process. Apart from inertia

forces in high-speed concepts, the mechani-

cal load is dominated by peak cylinder pres-

sures. The specific engine output can be

thought of as a representative physical di-

mension for the thermal load in similar com-

bustion processes. The current levels of

power density can be above 100 kW/L, and

peak cylinder pressures can reach 12 MPa

(Figure 1). The higher heat input in line with

the increase in power density causes the

piston temperature to rise.

As turbocharging becomes more wide-

spread, it can be expected that specific out-

put will continue to increase and that the field

of application for new developments in com-

ing years will include power densities of up to

130 kW/L, in even more applications.

EVOTEC® SC gasoline engine piston

The EVOTEC® 2 piston, with its weight-

optimized design, is currently a very good

basis for prevailing power densities of around

100 kW/L. In comparison with the EVOTEC® 2

piston, the EVOTEC® SC piston has an ad-

ditional cooling channel, which is created by

inserting a salt core during casting. The inte-

grated cooling channel causes temperatures

at the piston crown and in the region of the

first ring land to drop by up to 25 K (Figure 2).

The load capacity at these locations is signifi-

cantly increased, which makes power densi-

ties of considerably more than 100 kW/L

possible. In addition, such pistons reach op-

erating temperatures more quickly, which has

a favorable effect on exhaust gas emissions.

New EVOLITE® gasoline engine piston

In addition to expecting the pistons to with-

stand extremely high stresses, manufactur-

ers require that the oscillating masses of the

piston be lowered. These are very significant

for the transient responsiveness of the en-

gine as speeds increase. They are also criti-

cal if an acceptable engine vibration behavior

must be achieved through mass balancing.

This presents the challenge of handling high

external loads with minimal piston weight. It

must also be ensured that design changes to

Fig. 1: Peak cylinder pressure and specific output are primary factors that influence part loads (example:turbocharged gasoline engines)

Fig. 2: The cooling channel brings about significant temperature reductions and thus greater component strength

EVOTEC® 2 (with spray jet cooling) EVOTEC

® SC

276 ˚C 251˚C

20 40 60 80 100 120 140

16

14

12

10

8

6

4

Specific output [kW/L]

Passenger car

road applications

= Current

maximum value

for downsizing

high-performance

engines in

A 45 AMG/ CLA 45 AMG

I g n i t i o n p r e s s u r e [ M p

a ]





life time in that area by nearly eight times in

comparison with the EVOTEC® 2, while the

weight has been reduced by 5 percent

(Figure 3). The EVOLITE® piston design

offers potential in every respect to provide

a low-weight solution, particularly for four-

cylinder engines where the oscillating masses

are very significant to noise emissions due to

vibration.

Both test bench and engine test results have

proven that friction, crucial to low CO2 emis-

sions, is further reduced in comparison with the

EVOTEC® 2. A CO2 advantage of 0.46 g/km

was thus determined for the EVOLITE® pis-

ton in the NEDC. The process development

of this piston is currently being completed.

MAHLE steel pistons for diesel engines

In diesel engines, steel pistons provide sig-

nificant potential for reducing CO2 emissions

in comparison with the aluminum pistons

that have been typical up to now. MAHLE

has therefore developed steel pistons for

passenger car diesel engines to readiness

for series production. The fundamental design

advantages in comparison with aluminum

pistons have already been discussed exten-

the piston do not compromise its behavior in

terms of frictional loss or noise, but instead

improve them if possible.

With the development of EVOLITE®, the lat-

est generation of gasoline engine pistons,

MAHLE demonstrates that the limits of light-

weight design can still be extended. The new

piston design for modern, highly loaded

gasoline engines that are optimized for fric-

tional loss represents the next step in the

ongoing development of the EVOTEC® 2

design, which has been tried and tested in

series production. The goal of development

was to update the EVOTEC® principle and to

use ultramodern simulation tools to uncover

additional potential for mass savings and in-corporate them in a manufacturable product.

A numerical 3D topology optimization of the

EVOTEC® 2 piston concept was performed

in order to develop the EVOLITE®. Due to the

advanced state of technology in piston con-

struction, additional improvements to the

design are often possible only by means of

such numerical structural optimizations.

An improvement in the connection between

the skirt and the box wall has increased the

sively. On the one hand, the benefits are

found mainly in the area of frictional loss. In

collaboration with a manufacturer, MAHLEhas again demonstrated this frictional loss

advantage in test bench analyses under both

partial load and full load. Thermodynamic

conditions additionally result in advantages

in combustion that lead to a reduction in fuel

consumption and emission levels. The lower

compression height of a steel piston can also

be utilized to increase the displacement or to

decrease the height of the engine.Fig. 3: Changes to the box wall design in the EVOLITE® piston (TS: thrust side, ATS: antithrust side)

EVOLITE®

EVOTEC® 2

TS

Volume

TS/ATS

ATS

< 0.6 : 10.7 : 1




MOTORSYSTEME UND -KOMPONENTEN

The MONOTHERM® piston from MAHLE,

which has been tried and tested many times

over in commercial vehicle engine applica-tions, combines these advantages. It will be

used in a series production passenger car

diesel engine for the first time in 2014.

As a further development of the single-piece

MONOTHERM® piston, the new two-piece

MonoGuide® piston closes the gap to the

TopWeld® steel piston introduced in 2012. In

comparison with the MONOTHERM® piston,

Fig. 4: MAHLE steel pistons for passenger car

diesel engines: MONOTHERM® , TopWeld

® , and

MonoGuide® (left to right)

the MonoGuide® has a longer skirt, which

remains decoupled from the piston crown in

contrast to the TopWeld® (Figure 4). Thisflexible design significantly improves the

NVH behavior of such a piston and therefore

seems to be well-suited for the use in alumi-

num engine blocks as well.

Author: Dr. Stefan Spangenberg




The development trends of recent years

toward higher specific engine output

have led to the gas exchange valves be-

ing subjected to increasing thermal

loads. The component temperatures at

the exhaust valve are already above

800°C in many cases, which is a chal-

lenge for typical high-strength valve

materials. Combustion optimization by

thermal management of the valves also

plays an increasing role.

Typical limitations in terms of operational re li-

ability of λ = 1 concepts are the maximum

temperature at the exhaust valve, the turbine

inlet temperature, and/or the maximum per-

missible inlet temperature of the exhaust gas

at the first catalytic converter. In order to

protect the components, enrichment of the

mixture is often necessary at high engine

speeds and loads to limit the maximum ex-

haust gas temperature and prevent the com-

ponents from being thermally overloaded.

Currently, the knock limit additionally pres-

ents a substantial obstacle to optimizing fuel

consumption in gasoline downsizing en-

gines. The “knocking” phenomenon is critical

to the further development of CO2-optimized

gasoline engines.

MAHLE has developed a new technology onthe basis of a conventional hollow valve with

cylindrical bore, whereby an extended hollow

cavity can be made in the valve head with

just one additional process: electrochemical

machining (Figure 1). This enlarged hollow

space allows liquid sodium to dissipate the

heat during engine operation even better.

The valve head is cooled by the shaker ef-

fect: the hollow space is not completely filled

LIGHT AND COOLED:

VALVE TECHNOLOGY

FOR OPTIMIZED THERMAL MANAGEMENT

with sodium, so that it is shaken as the valve

moves; the sodium breaks down and thereby

produces significantly greater heat dissipa-

tion via the valve guide.

This technology can be used for both intake

and exhaust valves. The surfaces in the

combustion chamber are cooler as a result

(reduction of approx. 30 to 50 K), allowing

the knock limit to be shifted and thus en-

abling a more optimal selection of the firingpoint in the design of the gasoline engine

cycle. The goal is to achieve a reduction in

fuel consumption. The valve mass is likewise

reduced by 3 to 6 percent compared with

conventional hollow valves. Measurements

substantiate the temperature reduction on

the exhaust side. An internal high-stress en-

durance test to establish service life has also

been concluded positively. The EvoTherm®





valve is an important addition to the MAHLE

product portfolio. The necessity of applying

such technologies is already clearly evident

today.

MAHLE takes a globally leading position in

the area of hollow valves, with decades of

experience. The MAHLE EvoTherm® valve is

the latest development to support engine

manufacturers even more fully as they con-

front current and future challenges in engine

development. Because the EvoTherm® valve

is based on a conventional hollow valve, it

can be considered a low-cost solution.

Beyond the potential of the EvoTherm® valve,

the thermodynamic advantages and indus-

trial feasibility of the MAHLE TopTherm® valve(Figure 2) are now being evaluated. This

valve concept is designed as a lightweight

valve, and its advantages have been proven

with respect to reduced friction in the valve

train, which can lead to a reduction in con-

sumption in the NEDC by up to 0.5 percent.

At the same time, the composite valve offers

more extensive potential for reducing tem-

peratures at the thermally highly loaded com-

Fig. 1: Electrochemical machining is used to create

an expanded ho llow space in the valve head of the

EvoTherm® valve (right)

Fig. 2: The TopTherm® valve has a lightweight design and offers additional potential

for temperature reduction

conventional solid and hollow valves, the

composite hollow valve demonstrated sig-

nificant advantages in fuel consumption in

the full-load range while maintaining the

maximum permissible intake temperatures at

the catalytic converter and turbocharger.

These are a result of the shifted knock limit,

with the resulting improvement in the center

of combustion mass and leaner full-load

mixture. Good potential is evident in the tran-

sient range as well, because the shifted

knock limit allows a higher basic compres-

sion ratio and comparable performance tar-

gets can be achieved with lower boost pres-

sure. A study of the industrial feasibility of

this challenging valve technology with regard

to production is nearly complete.

Authors : Chris toph Luven, A lexander Puck

ponent surfaces due to its construction as a

rigid, rotation-symmetrical surface structure

with a large sodium-filled cavity. Based on

thermal simulations and temperature mea-

surements, there seems to be a potential to

reduce the disk temperature by significantly

more than 100 K.

In addition, this concept provides opportuni-

ties for the reduction of component protec-

tion measures when used as an exhaust

valve, due to the more uniform component

temperature distribution and its proven high

thermal load capacity. While the maximum

permissible temperature of the exhaust valve

is typically a limiting factor, besides the in-

take temperature at both the catalytic con-verter and the turbocharger, the MAHLE

TopTherm® can be designed even closer to

the target of λ = 1. In comparative tests with




VERSATILE AND RESISTANT:

OIL CONTROL RINGFOR HIGH-PERFORMANCE, FRICTION-OPTIMIZED ENGINES

Eng ine-internal components are in-

creasingly subject to mechanical and

thermal loads due to rising levels of

specif ic eng ine output . At the same

time, their properties should improve

further in order to contribute to the ef-

ficiency of the powertrain. MAHLE has

developed a new oil control ring, on the

basis of a cast iron ring, that has ex-

tremely low friction properties thanks

to the combination of innovative design

and PVD coating and that remains

wear-resistant even under high loads.





trend is toward reducing the cross-sectional

area of the rings. The contact land area must

be adapted at the same time, however, in

order to retain the surface pressure of the

land, which is ultimately responsible for

scraping off the oil. Starting from the origi-

nally common land width of about 0.3 mm,

current development has arrived at a nomi-

nal value of down to 0.1 mm—about the

thickness of a sheet of paper, which pres-

ents considerable challenges with respect to

wear resistance.

Therefore, MAHLE counts on a

combination of the so-called

X-taper design (Figure 1) and

a PVD coating. The X-taperdesign stands for a shallow

rise of the lands, in particular.

The land width thus remains low even if there

is slight abrasion, and the surface pressure is

kept intact. Since galvanic plating reaches its

limits at this land width, a coating made of

MIP 230 chromium nitrite is applied (Figure 2)

to increase wear resistance. This coating

also resists abrasive conditions—such as

can occur more severely with thermal spray

coatings on the cylinder running surface—,

features very high thermal stability, and is not

sensitive to reactions with additives. Further-

more, it has a lower friction coefficient in

comparison with galvanic coatings, resulting

in additional advantages in the mixed friction

range.

The new MAHLE oil control ring thus contrib-

utes to increasing system efficiency in the

combustion engine and is particularly suit-

able for use in highly loaded, friction-opti-

mized combustion engines that meet futureemissions limits.

Author: Dr. Daniel Lopez

In modern engines with high specific output,

it is particularly important that as little oil

residue as possible remains on the combus-

tion chamber walls. Therefore, it is a prereq-uisite that the oil control ring is highly flexible

and exhibits good conformability behavior. If,

for example, cylinder distortion occurs, the

ring will still maintain contact with the running

surface and retain its effective scraping ca-

pability.

In order to increase the flexibility of the rings

and to lower tangential loads, the general

Fig. 1: X-taper design in detail

Fig. 2: PVD coating with MIP 230 chromium nitrite




MAHLE has developed an active fuel

pref ilter for diesel engines that allows

an engine to be used around the world,

even with biofuel, due to its reliable

separation of water and contaminants.

The strategies of part replication and modu-

lar design offer great potential for serving

global markets efficiently in high quantities.

On the powertrain side, the pinnacle of this

approach is the so-called world engine, an

engine platform for use in every region. This

concept presents substantial technical chal-lenges. On the one hand, the engine must

meet the partly strict exhaust gas legislation,

which leads to a high level of technological

advancement. On the other hand, it is this

sophisticated level of technology that is con-

fronted with different biofuel shares and fuel

quality levels.

In order to comply with demanding emis-

sions limits, modern diesel engines typically

employ common rail injection systems.

These are extremely sensitive to solid parti-

cles and diesel fuel containing unsolved wa-

ter. Since world engines are also used in

countries with poor fuel quality and varying

shares of biofuel, it is necessary to enable

optimal separation of contaminants and wa-

ter even under these conditions. Biodiesel is

critical because it has a hygroscopic effect

and consequently binds additional moisture

from its environment. If fuel does not con-

tain any special additives to prevent corro-

sion along with its increased water content,

the risk of damage to the injection system

increases.

HIGH-EFFICIENCY WATER SEPARATION SYSTEM:

ACTIVE FUEL PREFILTERFOR DIESEL ENGINES USED AROUND THE WORLD

Fig. 1: Simplified system overview





MODULE

sient volume flow as a function of the load

state of the engine. The active prefilter is now

located in a separate circuit (Figure 1), which

due to the integration of a so-called hopper

tank that acts as an intermediate tank can be

charged with a largely constant volume flow

rate. This rate is optimized for the filter me-

dium. In addition, this so-called suction-side

arrangement can prevent fine diesel-water

emulsions that are difficult to separate and

are generally caused by the primary pump.

The fuel is fed into the prefilter from the maintank and cleaned of large contaminants and

water in sequential steps. This process is

based on the proven principle of two- or

three-stage water separation (Figure 2) from

the latest series of heavy-duty fuel modules. It

utilizes a filter medium for coarse separation,

a hydrophilic nonwoven fabric, and a hydro-

phobic final separator medium, if needed.

The cleaned fuel then flows into the hopper

tank, from where it is extracted toward theengine through the primary pump. The un-

used fuel returns from the engine via a return

line to the hopper tank, which in turn is con-

nected to the fuel tank through another re-

turn line. By means of this line, the excess

diesel fuel can be discharged and otherwise

serves to provide pressure compensation.

The separated water is collected. A sensor

detects the water level and sends a signal to

the vehicle via the integrated electronic con-

troller. The separated water is discharged

manually or automatically using the patented

BlueDrain® system.

The amount of fuel held in the hopper tank

can be specified depending on the control

strategy. It is possible to actuate the transfer

As a high degree of water separation is re-

quired in order to protect the fuel system

components, regardless of service life, dirt

content, or fuel quality, MAHLE has devel-

oped a solution with the active prefilter mod-

ule that achieves a separation level of up to

98 percent in new condition. The separation

of water from fuel is fundamentally depen-

dent on the volume flow rate; separation

levels drop particularly at high volume flow

rates. Previously, separation systems were

integrated in the fuel filter module near the

engine on the high-pressure side. This meant

that separation was dependent on the tran- Fig. 2: Water separation in detail

pump as needed, for example, to maintain

the volume flow within defined limits depend-

ing on the load cycle of the engine (Figure 3).

In the future, this can be further optimized by

networking with topographical data and the

navigation system. The expected fuel con-

sumption would then be predictable and

could be held available as a buffer.

By positioning the active prefilter upstream of

the primary pump, MAHLE has been able to

produce a highly efficient water separation

system that achieves a very high degree of

performance throughout the service life of

the filter medium. The module thus allows a

diesel engine to be used throughout the

world, regardless of fuel quality and biofuelshare. At the same time, the design of the

components that are subject to loading can

be simplified by shifting them out of the low-

pressure region, which nearly compensates

for the additional effort of providing a sepa-

rate circuit. The active prefilter was con-

structed as a functional prototype at MAHLE

and tested extensively on the test bench and

engine test rig. The application is currently

being prepared for predevelopment together

with a manufacturer.

Authors : Stefan Jauß, Jörn Wetzel

Fig. 3: Fuel quantity regulation and application

Unfiltered fuel Preheated fuel

Filtered fuel Water

Particle medium Transfer pumplocated on thesuction side

Water levelsensor

Water drain screw

Coalescer medium

Functional opti-mization in avail-able installationspace

Flow directionfrom inside tooutside

Feed line from tank

Electroniccontrol module

Return line to tank

Customerconnection plug

Return linefrom engine

Multilevel sensor

Feed line to engine

Transfer pump

Unfiltered fuel Preheated fuel Filtered fuel




One of the chief measures used to re-

duce fuel consumption and thus CO 2

emissions is to reduce the displace-

ment, typically in combination with tur-

bocharging, in order to maintain or im-

prove power output and torque. As the

degree of turbocharging increases, the

necessity of cooling the compressed air

grows simultaneously. Charge air cool-

ing therefore takes on an ever more

critical role.

The reduction of pressure loss of the charge

air across the cooling system is a source of

great potential in charge air cooling. When

the charge air is indirectly cooled by means

of a low-temperature coolant circuit, the

cooler can be installed near the engine be-

HIGHER TORQUE, LOWER CONSUMPTION:

AIR INTAKE MODULEWITH INTEGRATED CASCADED CHARGE AIR COOLING

tween the turbocharger and throttle valve.

The large-volume charge air pipes for direct

charge air cooling are thus eliminated and

are replaced with substantially thinner cool-

ant lines, simplifying the integration of the

system in various engine architectures. In

particular, the pressure loss is reduced by

about 50 percent compared with the direct

system. In addition, the engine is providedwith cool air for a significantly longer time in

case of a sudden load step.

The advantages are greatly ampl ified by inte-

grating the indirect charge air cooler in the

air intake module (i2CAC). The packaging is

optimized considerably once again, and the

pressure loss is reduced by up to 80 percent

compared with direct charge air cooling.

The share of integrated indirect charge air

cooling will therefore continue to increase

across all vehicle classes in the coming years.

MAHLE develops air intake modules, and

Behr the charge air cooling system. This

integrated concept is a prime example of

how the technologies of the two companies

complement each other. Together, they can

provide customers in this dynamic marketwith solutions from a single source.

Effect of charge air temperature on

engine dynamics and fuel consumption

The temperature of the charge air prior to

entering the cylinder has a substantial effect

on combustion and consequently on the effi-

ciency of the engine. After compression, it can

reach well over 200°C in highly turbocharged





engines in the full-load range. As a result, the

density of the air flow is lowered, while the

thermal load on the engine components in-

creases. These effects prevent efficient charge

air cooling.

MAHLE has now investigated the impact

on a 1.2-liter three-cylinder gasoline engine.

Cooling the charge air leads to greater mass

volume flow on the intake side. Combustion

is thereby substantially improved, suscepti-

bility to knocking is reduced, and the ignition

point can be advanced. Correspondingly, the

density of the volume flow in the exhaust is

also increased, which makes the turbocharger

more responsive. At low engine speeds, this

results in improved dynamics and increasedtorque. At high engine speeds and loads, the

cooled charge air reduces the need for over-

fueling.

At an ambient temperature of 24°C, an incre-

mental charge air temperature reduction from

60 to 30°C was investigated in the test en-

gine. The most significant improvements were

seen between 45 and 30°C.

The maximum potential for the 1.2-liter three-

cylinder engine was reached under full load

at constant torque, with fuel savings of up to

5 percent, by advancing the ignition point.

The positive effect is further amplified to a

remarkable degree for larger engines with

higher performance.

An alternative approach would be to take

advantage of the lower charge air tempera-

ture in order to increase torque at the same

level of consumption. The result: 7 percent

more torque under full load at low enginespeeds. The low charge air temperature can

thus be utilized in two ways: either for reduc-

ing consumption or for increasing torque.

The lower temperature level of the charge air,

however, cannot be achieved with conven-

tional cooling.

Potential for cascaded charge

air cooling

The larger the engine and the greater the

power output, the greater is the quantity of

heat to be dissipated to the charge air. The

lowest achievable temperature level, in the-

ory, is the ambient temperature. Another

condition is that the total quantity of heat

must be dissipated to the environment via

one or more heat exchangers. The limiting

element at the end of the chain, therefore, is

always an air/air or air/coolant cooler.

In order to achieve an ideal charge air tem-

perature level with increasingly higher power

output requirements, cooling must be per-

formed in two stages. In this “cascaded”charge air cooling system, the charge air can

be precooled in a first stage in an indirect

charge air cooler by means of the high-

temperature coolant circuit of the engine

(Figure 1). In the simulation on the three-

cylinder engine, with an external temperature

of 24°C, the air measures about 170°C as it

encounters the cooling water at around 90 to

100°C, and is consequently cooled down to

about 120°C.

In a second stage, the precooled charge air

is then cooled down further through the low-

temperature coolant circuit in a second indi-

Fig. 1: Schematic design of integrated cascaded charge air cooling

Fig. 2: Prototype of integrated cascaded charge

air coo ling

rect charge air cooler. At the full-load operat-

ing point of 4,000 rpm, for example, the

cascaded cooling system achieves a charge

air temperature of 38°C. For comparison: apreviously optimized single-stage indirect

charge air cooling system only reaches 44°C

under the same conditions. At the full-load

operating point at 6,000 rpm, the cascaded

charge air cooling system even manages to

achieve a temperature level of 32°C.

Prototypes of integrated cascaded charge

air cooling (Figure 2) have already been

tested by MAHLE and Behr on engine test

benches. The results confirm the high ex-

pectations.

Author: Jürgen Stehlig




FILTRATION AND ENGI NE PERIPHERALS

REPLACEMENT FOR PETROLEUM:

FOR AIR DUCT COMPONENTS

BIO-BASED RAW MATERIALS

The plastics used in the automotive in-

dustry are primarily based on petro-

leum. In its search for alternatives,

MAHLE tested various bio-based plas-

tics and ultimately validated one mate-

rial as ready for series production. This

new bioplastic is first being used for air

duct products.

Large quantities of various types of plastic

are found in vehicles. Due to the limited avail-

ability and rising prices of petroleum-based

plastics, it seems reasonable to investigate

alternatives and develop them to readiness for

series production. These alternatives should

protect the environment and not representFig. 1: Bio-based raw material for blow molding




In an effort to validate the properties of the

new bio-based blow mold material, first pro-

totypes were initially produced without modi-

fications to the sample and series production

mold. In comparison with a conventional, pe-

an encroachment on the food chain, i.e., they

should not be based on starch as a raw ma-

terial, for example. Bio-based plastics must

also be available in sufficient quantity.

As part of a predevelopment project, MAHLE,

in conjunction with DuPont Performance

Polymers, has investigated a bio-based blow

mold material (Figure 1) for pipes for unfiltered

air as well as clean air, and advanced it to

series production readiness. Furthermore, a

comparison with conventional petroleum-

based blow mold plastics was performed.

Regardless of the material selection, the re-

quirements for air ducts, such as unfiltered

and clean air lines, continue to rise. The trendtoward a modular system approach demands

more flexible and lightweight components

that can be employed even under very tight

installation space conditions. Another chal-

lenge consists in the low-cost, effective

production of what are often very complex

shapes. The increasingly difficult installation

and removal conditions for service purposes

are central aspects in the development of

current air duct products.

troleum-based material, the bio-based plastic

is convincing, with improved machinability

and excellent flow properties. Better surface

quality means less air turbulence within the

air duct system. Extensive validation work in

accordance with typical OEM specifications

demonstrates better flexibility of the blow

mold parts due to greater motility of folds

before aging (Figure 2). The greater compo-

nent flexibility not only allows more freedom

in shape design, but also provides advan-

tages in the installation and removal of air

duct products for the customer and in main-

tenance service. After simulated aging, the

components were tested for rigidity, elonga-

tion at fracture, deflection, and pull-off forces.

All recorded values are at least as good

as the comparable values from the conven-tional material that was evaluated in parallel

(Figure 3). Flawless functionality is thus estab-

lished in prototypes. Another positive aspect

is the achieved weight reduction, which can

amount up to 25 percent, depending on the

component size.

Authors : Andreas Enderich, Daniel Zielinski

Fig. 3: Strength of conventional plastic and bio-based plastic under simulated aging and

different temperature loads

Fig. 2: Fold motility of conventional plastic in comparison with the new bioplastic


0 200 400 600 800 1000

Distance [mm]

Conventional plastic

Bioplastic

Conventional plasticafter aging

Bioplastic after aging

Conventional plastic 130°C

Bioplastic 130°C


Bioplastic 150°C


Bioplastic 160°C

Fold motility

Strength

35

30

25

20

15

10

5

0

Agin g [h ]

F o r c e [ N ]

F o r c e [ N ]

0 5 10 15 20 25

160

140

120

100

80

60

40

20

0




Reaching the optimal operating tem-

perature of a combustion engine more

quickly is one of the remaining levers

for further reducing CO 2 emissions in

vehicles. Keeping the coolant flow at a

standsti ll after cold-starting the engine

supports an effective warm-up phase,

as the coolant in the engine will not im-

mediately dissipate any heat generated

by the engine. MAHLE has developed a

hydraulically controlled coolant pump,

a system that is attractive due to its

simple design.

Shortening the engine warm-up phase by

keeping the coolant still leads to direct fuel

savings and thus to reduced CO2 emissions.

The simply constructed, robust coolant

pump from MAHLE has a low system weightand can be adapted to existing engine cool-

ing circuits.

The coolant can be kept st ill in various ways

with a mechanically driven coolant pump,

depending on the installation space condi-

tions for the pump on the engine. With the

patented MAHLE valve control, a bell-shaped

slider closes the impeller outlet of the pump

SIMPLE CONSTRUCTION, SIGNIFICANT EFFECT:

CONTROLLED MECHANICALFOR SHORTER ENGINE WARM-UP PHASES

on demand and completely prevents the flow

of coolant (Figures 1 and 2). The force re-

quired to move the slider is generated by the

coolant pressure. For this purpose, the pump

housing contains an additional positive dis-placement phase, which provides adequate

pressure for moving the slider, even at low

engine speeds. The positive displacement

phase is designed as a centrifugal impeller

pump and is characterized by a single-piece,

robust design. A solenoid valve controls the

generation of hydraulic pressure. In normal

driving operation with a warm engine, the

solenoid valve on the centrifugal impeller





pump engages a direct permanent bypass

from the pressure side to the suction side,

preventing the buildup of pressure for shift-

ing the slider. When the engine is cold, such

as after cold-starting the engine, the sole-

noid valve receives an electrical signal from

the engine control unit and closes the per-

manent bypass. The centrifugal impeller now

generates a hydraulic pressure that acts di-

rectly on the valve slider and causes the im-

peller to be covered (Figure 3). The use of

COOLANT PUMP

Fig. 3: Controlled coolant pump with peripheral wheel and valve slider

Solenoid valve

Pump housing

Impeller

Valve slider

Belt pulley

Peripheral wheel

coolant as the auxiliary medium eliminates

additional dynamic seals in the coolant pump.

In tests on the component test bench and in

the combustion engine, MAHLE has suc-

cessfully demonstrated the function of the

hydraulic valve control. Above a pump speed

of 800 rpm, the impeller provides sufficiently

high coolant pressure to shift the slider.

The measured volume flow rates of less than

0.5 L/min with a fully covered impeller lead to

a significant shortening of the engine warm-

up phase, thus representing an important

contribution to further reductions in CO2 emis-

sions in passenger cars.

Authors : Michael Baumann, Dr. Mar tin Janßen

Fig. 1: Impeller outlet, closed Fig. 2: Impeller outlet, open

Valve slider

Scraper

Pump bearing

Peripheral wheel

Slider seal

Sliding ring seal

Impeller

Impeller outletResetting spring




The spin-on oil filter, or exchangeable

oil filter, is one of the filter systems that

has been on the market for the longest

time. The exterior of the spin-on oil filter

has hardly changed over the years, but it

has nevertheless been under continuous

development due to new challenges. Its

field of application has a wide range

and includes passenger car diesel and

gasoline engines, commercial vehicles,

motorcycles, and small engines. Spin-on

oil filters are even used in motor sport.

SYNTHETIC AND STABLE:

SPIN-ON OIL FILTERFOR MODERN DOWNSIZING ENGINES





solutions are based on media with plastic

and/or fiberglass content (Figure 1).

With downsizing engines, it is not only the

size of the actual engine that changes; spin-

on oil filters also shrink correspondingly. The

improvement of differential pressure must

therefore be considered by all means in the

development of spin-on oil filters. This can

be achieved, for example, by employing fully

synthetic filter media (Figure 2). Particularly

for cold starts, these media have a clear ad-

vantage over media based on cellulose fibers.

In addition, fully synthetic media are charac-

terized by significantly better chemical resis-

tance. The introduction of fuel and water intothe oil-conveying system today also exerts an

aggressive impact on the filter medium, thus

requiring a high level of basic resistance that

synthetic fibers are more suitab le to provide.

Turbocharged downsizing engines reach

higher engine temperatures. Here again, syn-

thetic media stand out as superior, as they

are much more thermally stable than media

based on cellulose.

Due to this broad scope of application, the

spin-on oil filter has had to meet many new

challenges over the course of time, whether

in ecologically critical applications for renew-

able or alternative fuels, such as biodiesel or

E10, the rising use of stop-start technology,

or the important trend toward downsizing

engines. New spin-on oil filters also require

improved cleanliness of components in order

to prevent the introduction of dirt into the oil-

conveying system. Spin-on oil filters have

gained a stable market share in Europe of

about 35 percent, which will remain constant

for the next few years. In countries such as

Japan or the USA, spin-on oil filters are used

almost exclusively.

Media such as cellulose are employed as

standard for spin-on oil filters, with appropri-

ate impregnation of the paper. Maintenance

intervals of about 30,000 km are thus

achieved. There is a strong trend in filter

media, however, toward higher separation

levels in an effort to protect the engine and

the oil circuit against dirt, abrasion, and soot

to the greatest extent possible. This is the re-

sult of using very fine fibers. Series-production

Fig. 2: Fully synthetic oil filter medium

Fig. 1: Particle retention efficiency of filter media for spin-on oil filters

Cellulosemedium

Mischfasermedium

Glasfasermedium

Due to the current set of requirements in

the area of oil filtration and the advantages

of synthetic fibers, mixed fibers or fully syn-

thetic fibers are now experiencing a rising

trend. MAHLE has the right solutions for

these requirements. In the course of thisyear, we will commission a new, highly auto-

mated production line at our St. Michael/

Austr ia location. We wi ll thus continue to be

able to meet the growing requirements of

the market in the future, both technically

and commercially.

Authors : Frank Rohde, Peter Zausnig

100

90

80

70

60

50

40

30

20

10

0

0 5 10 15 20 25 30 35 40 45 50

Cellulose medium

Mixed-fiber medium

Glass-fiber medium

P a r t i c l e r e t e n t i o n e f f i c i e n c y [ % ]

Particle size [µm(c)]

Particle retention efficiency according to ISO 4548/12




Today, nearly all new vehicles are sup-

plied with HVAC systems, equipped

with cabin air filters to treat the air for

passengers. Due to its direct integra-

tion in the HVAC system, the cabin air

filter is likewise a product that high-

lights the potential synergistic effects

of the holding in Behr. Synergies with

respect to sealing filter elements can

be utilized even in early inquiry phases.

With the use of new filter media, the

new cabin air filters also meet the high-

est technical requirements.

WITH AND WITHOUT ACTIVATED CARBON:

NEW FILTER MEDIA FOR CABIN AIR FILTERS





Filter media for cabin air filters are differen-

tiated as filter media with and without acti-

vated carbon. The media are constructed in

a gradient structure, which means that the

medium becomes denser in the direction of

flow. At the same time, however, such media

have a preferred direction with respect to

their filtration properties. This must be con-

sidered when designing the filter elements,

as this is the only way to achieve optimal

filtration properties. As a rule, additional mea-

sures must be taken on the filter element itself

or during the production process to ensure

that the installation orientation is obvious.

In order to eliminate such measures, filter

media are needed that exhibit the samefiltration properties, regardless of the direc-

tion of flow. Increasing requirements for filtra-

tion performance, particularly with respect to

effective retention of very small particles, are

another challenge for new filter media.

Cabin air filter without activated carbon

MAHLE has now developed a new series of

filter media that meets the requirements of

different customer specifications. These new

filter media satisfy the ambitious targets re-

garding filtration properties, irrespective of

the direction of flow. In comparison with cur-

rent media, the new MAHLE filter media have

significant advantages with respect to pres-

sure loss of the filter element and, at the

same time, exhibit very high values for fine

particle retention.

The new media are manufactured in a single-

step production process that extends from

resins in bulk form to the finished filter me-

dium cut to width. Thanks to this flexible

production process, we can produce a wide

range of filter media with different filtration

performance properties simply by modifying

the process parameters. This enables us to

react quickly and effectively to changes inour customers’ requirements (Figure 1).

Cabin air filter with activated carbon

When it comes to adsorbing gases that are

present in the environment, we use filter

media with a separate layer of activated car-

bon. The combination of the activated carbon

layer with one or more filtration layers ensures

the filtration performance of the filter element,

regardless of the direction of flow. At the

same time, the modification of the filtration

layer design allows the incorporation of filter

media with different filtration performance

levels for even very small particles (Figure 2).

Whether with or without activated carbon,

our new filter media can optimally meet both

current and future market requirements.

Authors : Birgi t Renz, Frank Rohde

Fig. 1: Single-layer cabin air filter medium without

activated carbon

Fig. 2: Multilayer cabin air filter medium with activated carbon

Synthetic filter media layer

for retaining coarse particles

Activated carbon la yer

for adsorbing odors

Synthetic filter media layer

for retaining fine particles




Since specific loads, and thus tempera-

tures, are continuously rising in modern

engines, thermal load testing that is as

close to reality as possible is becoming

more and more important to the design

of hot components. To support current

engine development, MAHLE has devel-

oped a special process that converts ana-

log measurement signals to digital ones,

thereby enabling transient temperature

measurements in the valve area.

Modern gasoline engines enrich the com-

bustion mixture with fuel when the engine

load is drastically raised. The essential result

is increased internal cooling, which serves to

protect the components. Especially under

full load, however, this leads to significantly

higher fuel consumption.

If the engine is calibrated closer to a stoi-

chiometric ratio of air to fuel for consumption

or emissions reasons, then the exhaust gas

temperature rapidly rises so much that it

causes markedly higher thermal loads on the

components.

Similar problems arise in commercial vehicle

diesel engines. These are typically operated

under consistently high engine loads, which

once again results in high thermal loads.

Complicating factors can include poor-qual-ity fuels and heating operation, which further

increase thermal loading of the exhaust re-

gion due to lagging combustion.

Since the specific load, and consequently

the temperatures, in modern engines con-

tinue to rise, the design of hot components,

and the valve assembly in particular, requires

realistic testing of thermal loads.

FOR MORE EFFECTIVE COMPONENT DESIGN:

NEW MEASUREMENT METHODSOF VALVE TEMPERATURES

In the past, there was a lack of information

about the progression of temperatures in the

valve area under real operating conditions,

such as during transient engine operation

without the effects of natural valve rotation.

This circumstance has previously made it

difficult or even impossible to draw any use-

fulness from the following findings:

■ Determining the heat balance between

the valve, seat insert, and guide

■ Scale of the temperature drop at theexhaust valve due to alcohol fuel

additives

■ Effect of cooled exhaust manifolds with

internal or external guidance on tempera-

tures of the valve, seat insert, and guide

components

■ Determining real temperatures of light-

weight and conventional valves (intake

and exhaust) during engine operation





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