Porsche Engineering Magazine 2012/1

Shift into gear for the future.

911 (Type 991): fuel consumption (in l/100 km) urban 12.8 · extra-urban 6.8 · combined 9.0; CO2 emissions 212 g/km

Issue 1/2012

Porsche Engineering Magazine

Use our drive.

911 (Type 991): fuel consumption (in l/100 km) combined 9.7-8.2; CO2 emissions 229-194 g/km

Porsche Engineering Magazine

Issue 1/2012

At Porsche Engineering, engineers areworking on your behalf to come upwith new and unusual ideas for vehi-cles and industrial products. At the re-quest of our customers we develop avariety of solutions – ranging from thedesign of individual components andthe layout of complex modules to theplanning and implementation of com-plete vehicles, including productionstart-up management. What makes ourservices special is that they are basedon the expertise of a premium car man -

About Porsche Engineering

ufacturer. Whether you need an auto-motive developer for your project orprefer a specialist systems developer,we offer our customers both becausePorsche Engineering works success -fully across both of these areas. Theextensive knowledge of Porsche Engi-neering converges in Weissach – andyet it is globally available, includ ingat your company’s offices or produc-tion fa cil ities. Regardless of where wework – we always bring a part of Porschewith us.

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About Porsche Engineering

www.porsche-engineering.com

Porsche Engineering Magazine 1/2012

Editorial

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Dear Readers,

When we analyze our company’s more recent projects, onething is clear: sustainability and environmental concernshave changed demand behavior and have now become adriving force of technical innovation in many areas ofautomotive development.

Tighter political and legal regulations for the mobility oftomorrow play an important role in this. It seems to us,however, that another important factor here is the con-stantly changing values of automotive industry customers.This has a direct effect on clear trends in automotive devel - opment.

At the same time though, the “old economy” of automotivedevelopment, such as body construction and drive tech -nology, is experiencing another renaissance. Lightweightconstruction has been an essential part of bodywork devel -opment for some time now. But the potential of combustionengines has also still not been fully exhausted yet.

The mobility of today and tomorrow is increasingly electric.With the hybridization of vehicles, we are experiencing ahighly complex step towards electromobility. There hasalready been plenty of hard work on the further develop-ment of battery and electric vehicle designs, in order to

increase operating distances without having to noticeablycompromise the comfort of the vehicle user.

In order to contribute actively to these developments for ourcustomers, we are continuously investing in our expertiseand capacity at Porsche. Whether this is on a grand scale,such as the consistent expansion of the Weissach Devel -opment Center, or on a smaller scale, such as the opera-tion start-up of new high-voltage and thermodynamicstesting stands.

We invite you – not without pride – to take a look at this andother Porsche developments: Discover for yourself howPorsche is setting new standards in the areas of efficiency,lightweight construction, performance and emotions withthe latest generation of the 911 Carrera.

If reading our magazine awakens your interest in devel -oping something with us, then we look forward to workingwith you to meet the challenges you set us.

We hope you enjoy reading our first issue of 2012.

Yours, Malte Radmann and Dirk LappeManaging Directors Porsche Engineering



The new 911The most efficient and sportiest Carrera ever

About Porsche EngineeringEditorialImpressumNext Up

Weissach is growingExpansion at the Weissach Development Center

Keeping cool in futureVehicle interior climate control in electromobility

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Contents

Cover

We develop the future, for example the seven-speed manual transmission in the new 911. Shiftinto gear for the future with us – what will you useour drive for?

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Smoother starts using roboticsPorsche Engineering clutch robot 30

News

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High voltage: 300 kW source/drainHigh-voltage and thermodynamics test stand

Contents

Who developed it? Porsche.Special exhibition “80 Years of Engineering Services by Porsche”


Identity

The new 911: innovative, cutting-edge technology for newbenchmarks in efficiency, perfor-mance, lightweight constructionand emotions

Growth

Expansion of the Weissach Development Center fordemanding customer projects

Innovation

High-voltage and thermodynamics teststand for the development and testing of high-performance batteries

Analysis

Unique robot for the efficient testing of clutch charac -teristics in vehicles

Contents

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7Porsche Engineering Magazine 1/2012

Thanks to continuing growth, activitiesat Porsche Engineering in Wolfsburghave been expanded. At the project officein Wolfsburg, there are not only special -ists in the development of electric/electronic systems, but also first-classexperts in the layout and developmentof modules, assemblies and complexcom ponents. The Wolfsburg office playsan important role in Porsche’s projectsfor external customers and thereforecontributes significantly to the inte gratedengineering services within the corpo-rate group.

Wolfsburg: PorscheEngineering grows

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News

Along with 80 years of Porsche engi-neering services, 2011 also markedthe tenth anniversary of the Praguesubsidiary of Porsche Engineering.The branch office in the Czech Repub -lic is an integral part of engineeringservices by Porsche. It specializes incomplex technical calculations andsimulations, and has expertise thatstretches way beyond the automo -tive industry to a wide range of areasand sectors. It was established after asuccessful partnership with the Tech -nical University of Prague. Through

the intensive and valueable collabo-ration between the industry and dif-ferent fields of science, the latest

results from scientific engineering re-search are also channeled into PorscheEngineering.

Porsche Engineering Prague: ten-year anniversary

CURRENT NEWS

Milan Simadl, head ofthe commercial sectionof the German Embassyin the Czech Republicand Dr. Milos Polásek,head of Porsche Engi-neering Prague, at the10 year anniversarycelebrations

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News

A Porsche to carryin your hand

Porsche Engineering has carried out adetailed breakdown, analysis and docu-mentation of the historical Type 360“Cisitalia” engine on behalf of the Stutt-gart-based Porsche Museum. The leg -endary Grand Prix racing car, completedat the Porsche engineering office in

1948, was technically way ahead of itstime in many respects. By analyzing andexamining the engine today, new dataabout the innovative technologies ofthe past can be gathered and a uniquepiece of documentation for automobileenthusiasts will be created.

A Porsche for travel, a Porsche for din-ner and even a Porsche for the bath-room – rarely has the visual connectionbetween the sports car and PorscheDriver’s Selection products been soclose. This attractive product series, of-ficially called “Porsche Travel SystemSoft Top Luggage”, is pure Porschedesign. It includes items such as travelcases and bags in various sizes, a hand-bag, as well as a washbag manufactu-red in the same original soft-top mate-rial that is used for the folding tops ofPorsche Cabriolets. “The idea to utilize

this material for bags came aboutthrough working on the material for thesoft-top of the Boxster Spyder and the

corresponding marketing brochure,”explains Heidi Zink, project engineer forthe Boxster Spyder.

The bags are available online at: www.porsche.com/shop

Historical analysis

QUALITY

Porsche Engineering Group GmbHhas once again successfully com-pleted a quality management auditaccording to the industrial standardDIN EN ISO 9001:2008. The exter-nal auditor from the German Orga-nization for the Certification of Man -agement Systems (DQS) awardedthe engineering services by Porschea high standard of qual ity for itsprojects. Amongst other aspects,both the project management andthe motivation of staff at the engi-neering services by Porsche wasassessed as “very good”.

Awarded

Identity shaping in threedigits: the new 911

THIS MODEL HAS BEEN THE GOLD STANDARD IN ITS CLASS FOR GENERATIONS.BUT NOW THE 911 SETS THE BENCHMARKS IN PERFORMANCE AND EFFICIENCY

EVEN HIGHER – DEMONSTRATING ONE HUNDRED PERCENT PURE PORSCHEINGENIOUS ENGINEERING.

The most efficient and sportiest Carrera ever

Cutting-edge 911 technology

Cutting-edge technology in every area

With the new generation of the 911,Porsche engineers have once again com -bined the latest technological develop-ments in an exceptional way, in order toprovide maximum driving pleasure andefficiency. This ingenious engineeringis not just evident in the sports cars,but also in a wide range of engineeringprojects for external customers. Aspects

like lightweight construction, perfor-mance, efficiency and emotions are in-creasingly playing an equally importantrole here as in the 911.

Efficiency

Lightweight construction throughoutthe vehicle and extremely economical

engines in comparison to their outputhave always given the 911 Carrera anexceptional power-to-weight ratio andexemplary fuel consumption. The newgeneration differentiates itself from thecompetition even further in both areas:with a power-to-weight ratio of 4.7 kilo-grams per kW (10.3 lb per kW), the new911 Carrera S clearly comes out top of

The new 911 Carrera embodies the competence, passion and technological expertise of

Porsche more than any other model generation. Four key development aspects define

the new 911: lightweight construction, performance, efficiency and emotions. Porsche

Engineering has also played a significant part in creating the new generation of the 911

by developing the new seven-speed manual transmission.


12 Porsche Engineering Magazine 1/2012

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its class. And in NEDC consumption,the 911 Carrera and the 911 Carrera S,each with Porsche Doppelkupplungs -getriebe (PDK), once again boast un-matched and exceptional figures, with8.2 l/100 km (28.6 mpg imp.) and 8.7l/100 km (27 mpg imp.) respectively.

This huge step forward rests on thedesign: the entire new 911 Carrera hasbeen designed for more efficiency, mini-mized rolling resistance and optimizedoperating strategies. The main basis forthis efficiency is lightweight construction.The completely new aluminum-steel con-struction of the body not only enablesthe new model to be up to 45 kilograms(99 lbs) lighter than previous genera-tions, but also ensures a weight advan -tage of more than 100 kilograms (220lbs) over the lightest of competitors.

The mechanical components of the en -gines have been made even more friction-less, and to reduce consumption evenmore, vehicle electrical system recupera-tion and a map-controlled coolant ther-mal management system have beenadded. Through innovations and corre-sponding improvements in these twoareas, Porsche has succeeded in re -ducing consumption in the NEDC by0.45 l/100 km (522.7 mpg imp.). Theefficiency target has also been achievedwith the help of the first ever seven-speed transmission in automotive con-struction and the Porsche Doppelkupp -lungsgetriebe (PDK), also with sevenspeeds. Porsche Engineering led the de-velopment of the manual seven-speedtransmission, working together with thetransmission manufacturer ZF Friedrichs -hafen AG (see info box on pages 14/15).

spoiler was widened from 898 millime-ters to 1,137 millimeters. It is extendedautomatically at 120 km/h (75 mph) andretracted at 80 km/h (50 mph), but canalso be extended below these speedlimits at the push of a button. Furtheraerodynamic improvements were se -cured by optimized air brake spoilers,aerodynamically optimized exterior mir-rors, improved engine ventilation andoptimized fairings on the front wheels.

With the new 911 Carrera generation,Porsche has also further improved thefine details of the previous generation’sexemplary aerodynamics. The basic build -ing blocks of the aerodynamic designare the streamlined body surface, thenew rear spoiler and the cooling system,which does not require large air intakesunderneath the vehicle, thereby enablingthe smoothest possible vehicle floor. Theaerodynamically effective area of the rear


The extremely impressive 911 Carrera and 911 Carrera S models are highly efficient with maximum performance

Using the latest technology for more performance and efficiency

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911 (Type 991): Fuel consumption (in l/100 km) combined 9.7-8.2; CO2 emissions 229-194 g/km

1. Lightweight structures2. Low drag, variable

aerodynamics3. Start/stop function,

coasting, on-board elec-trical system recuperation

4. Electro-mechanical steering

5. Drive train incl. seven-speed PDK/world’s first seven-speed MT

6. Engine technology7. Thermal management

of engine + transmission8. Reduced residual braking

torque9. Reduced tire

rolling resistance



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Porsche Engineering led the development of the world’s firstand only manual seven-speed transmission in the automotivesector, working together with the transmission manufacturerZF Friedrichshafen AG. The new transmission was based onthe Porsche Doppelkupplungsgetriebe (PDK). Taking theman ual gear changes into consideration, the ratios of thethird and seventh gears were modified in comparison withthe PDK. The third gear has a higher ratio, which reducesconsumption. The seventh gear has a lower ratio to maintainpulling power even at comparatively low speeds.

Shifting gears

Gears are shifted out via two cable winch mechanisms. Onecable is for selecting the gear and the other is for shifting it.The transmission uses an H-shaped shift pattern. As theman ual transmission is based on the PDK transmission, andneighboring gears (for example first gear and second gear)

are not positioned directly opposite each other in the PDKtransmission, a completely new internal gear shift had to bedeveloped. The goal here was to covert the shift pattern toan H-shaped shift pattern with a new internal gear shift. Themechanism that enables this conversion is based on an in-vention by the company ZF Friedrichshafen AG.

The development of the new seven-speed manual transmission

Ingenious Porsche Engineering

3 6 5R R 1 3 5

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Shift pattern before conversion Shift pattern after conversion

The world’s first ever seven-speed manual transmission, developed by PorscheEngineering


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Through this invention, any gear arrangement in the gear setof the transmission can be converted into an H-shaped shiftpattern that is familiar and comprehensible for the driver.The main element of the gear shift is the carrier shaft, whichcan move translationally (in a straight line) and rotationally(turning). The carrier shaft’s movement is transmitted to thecable winches outside it and transferred to the gears by thelever mechanism on the shift cover. In order to select a gear,the carrier shaft is pushed axially in the shift gear frame. Thecarrier shaft is then turned in order to shift gears. The shiftforks are linked to the individual shift gear frames via theshift rods. Through the unique arrangement of the shift fin-gers on the carrier shaft, the shift gear frames of each gearare moved at the same time through this rotation during theshift from first gear into second gear.

Seventh gear shift lock

In order to prevent inadvertently shifting to seventh gear, aspecial shift lock was developed. That means that it is onlypossible to change into the gate for seventh gear if fifth orsixth gear was selected beforehand. However, the driver canshift back down at any time.

Martin Kuhn

1. Fitted bolt2. Cover plate3. Flange bushing4. Spring5. Locking ring6. Carrier shaft

1 2 3 4

Figure 1Gate 3/4 selected Locking ring is decoupled from the carrier shaft by 1 mm

Figure 2Gate 5/6 selected Carrier shaft pushes the locking ring upwards and blocks gate 7

Figure 3Shift into fifth or sixth gear Carrier shaft rotates by 29° Locking ring moves back in axial directionand releases gate 7

Shifting out of fifth or sixth gear Carrier shaft rotates back to neutral position Locking ring is radiallypretensioned by the rotating spring

Figure 4Shifting to gate 7 Carrier shaft pushes the locking ring upwards

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In this way, like its forerunners, the new911 Carrera characteristically combinesexciting sportiness with exemplary effi-ciency. The formula for this: Porsche In-telligent Performance.

Performance

The proof of the 911 Carrera’s perfor-mance gain speaks for itself: the new911 Carrera with optimal sporty equip-ment can lap the Nürburgring’s Nord-schleife in 7:40 minutes – 14 secondsfaster than the previous model.

The overall design of the new 911 Car-rera provides the foundation for this sig-nificant improvement in performance.The lengthening of the wheelbase by100 millimeters and the wider fronttrack width alone – 46 millimeters widerin the 911 Carrera and 52 millimeterswider in the 911 Carrera S – results incompletely new vehicle geometry witheven more driving stability at highspeeds, when on the straight and whencornering.

developed from scratch for the new911 Carrera. This also has a tangible ef-fect on performance: When braking onroad surfaces with different levels ofgrip, a tug on the steering wheel im-parts a steering input in the desired di-rection, making it easier for the driverto stabilize the vehicle and keep it in thedesired lane.

Another decisive contribution to the im-pressive increased performance of thenew 911 Carrera is provided by the en -tirely newly developed optional PorscheDynamic Chassis Control (PDCC). Theintelligent control of the PDCC systemis, for example, able to exercise indi -vidual control over the hydraulic actua-tors, depending on the driving situation,influencing self-steering behavior in theprocess and consequently improvingvehicle stabilization.

Lightweight construction

With the new 911 Carrera, Porsche setsnew standards in lightweight construc-tion. Up to 45 kilograms less total weightthan the previous generation means atotal weight reduction of 98 kilogramsin the basic vehicle design. The reasonfor this difference: increased safety re-quirements, a longer wheelbase, fuelconsumption reduction measures and amore powerful product firstly led to aweight increase of around 58 kilogramsin comparison to the previous models.

The key to success was lightweight con-struction throughout the vehicle. For thefirst time in the new 911 Carrera, an alu-minum-steel body construction has beenused. The underlying idea of this design

The second main reason for improvedperformance is the new drive unit. Bothengines, with 3.5 liters and 3.8 liters dis -placement, have been designed accord -ing to motor racing principles for highrevs. The maximum engine speed of thesix-cylinder engines has been increasedby 300 rpm to 7,800 rpm. The entire in-take manifold has also been optimized.The intake air flows through flow-opti-mized channels, new multi-hole injec-tors inject the fuel more efficiently andexhaust emissions exit the 911 Carrerathrough a system with reduced back -pressure. The fine-tuning of the aero-dynamics has succeeded in reducingthe total lift (CA) of the new 911 Carreramodels by 0.02, to a mere 0.05.

Even more agility in the new 911 Carrerais provided by Porsche Torque Vectoring(PTV). This system consists of a mechan -ical limited-slip rear differential and vari-able torque distribution to the rear axle.

For the first time ever, Porsche hasused electro-mechanical power steering

Porsche identity: the unmistakable performance of the new 911



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The targeted use of awide range of materialshas resulted in a signifi-cant reduction in weight

Porsche Engineering contributed to the development and implementation of the leather interior design

styling meant that the engineers werefaced with quite significant challenges.Engineers at Porsche Engineering con-tributed to the development and imple-mentation of the overall leather designby designing the instrument cluster andthe center console as well as the carpet-covered elements. Specifically, they wereresponsible for creating a strategy forcomponent and tolerance layout andfor carrying out covering tests. Manag -ing system and component suppliersand cooperation with the Porsche leathermanufactory were also an important partof their job.

The driving experience in the 911 is de-fined by the design, the sound and thevehicle providing feedback from theroad to the driver through shifting gearsand revving the engine. The driver expe-riences real driving pleasure when hefeels the performance of the vehicle di-rectly. The main communicator of this is

the sound. Mechanical engine soundsare characterized by higher frequenciesand have tonal elements.

The basis of the sound design for the airintake and exhaust systems in the new911 Carrera was created in the very earlystages of the vehicle’s design. The lay-out and dimensions of the manifolds,pipes, catalytic converters and mufflerswere all visually illustrated and evalu -ated with the help of a computer modelbefore there was even any hardware.

The development of muffler systems isone of the core competencies at Porscheand is always carried out at the WeissachDevelopment Center. In order to allowthe driver to feel the revs and the powerof the engine, the pathways of the airintake and mechanical engine soundsare tuned so that messages from thenew 911 to the driver are transmittedin as pure and unadulterated form aspossible in all driving conditions.

Like no other sports car, the new 911Carrera shows that by combining thelatest cutting-edge technology, excep-tional performance and the highest effi-ciency can be achieved at the same time.Porsche engineers love the challenge ofreaching ever higher levels of perfor-mance – whether in a sports car or inan external customer project. There’s abit of 911 in all Porsche Engineeringprojects.

is using the right material in the rightplace. The extensive use of aluminum toreduce the vehicle’s weight is thereforebalanced with elements of steel of vary-ing degrees of strength for a more rigidbody and optimum occupant protection.

Parts that are especially important forpassive safety, such as the inner roofframe and the B-pillar, have been madein ultra high-strength, boron-alloyedsteels. The new modular roof designalso provides advantages in terms ofweight. For the series model without asliding roof, the steel outer skin of theroof has been replaced with significantlylighter aluminum.

The drive train, chassis and electricalequipment have all also been compre-hensively redesigned to be lighter. Thechassis accounts for more than five kilo-grams of weight reduction, mostly thanksto the newly constructed front axle withcompact lightweight suspension strut.

Emotions

A highlight of the 911 design is the leatherinterior of the vehicle. Typical Porsche



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With its completely newly developed and unique roof de-sign, the Cabriolet continues what the Coupé began withits new aluminum-steel body. The typical 911 roof contourshave been entirely preserved for the first time. Intelligentlightweight construction, which also includes the use ofmagnesium for the construction of the convertible top, hasensured less weight and more sportiness, as well as lowerconsumption and greater comfort. Porsche has managedto reverse the weight spiral for all convertible 911s and hasmanaged to make the new Cabriolet models significantlylighter than their predecessors.

Both new Cabriolets have the same drive system as theCarrera Coupés. A 3.4-liter boxer engine with 257 kW (350 hp)

operates in the rear of the 911 Carrera Cabriolet, and its poweris transmitted to the rear wheels by the seven-speed manualtransmission. The open-top 911 Carrera S has a 3.8-litersix-cylinder engine with 294 kW (400 hp) and also comeswith a seven-speed manual transmission as standard. Theconvertible 911s also differentiate themselves stronglyfrom the competition in another way: in the NEDC bothmodels consume less than ten liters of fuel for 100 kilome-ters (23.5 mpg imp.). Alternatively, Porsche Doppelkupp -lungsgetriebe (PDK) can also be optionally selected for theCabriolet models, which makes even lower fuel consumptionand shorter acceleration times possible.

The longer wheelbase compared to the previous model,the wider front track at the front axle and the new electro-mechanical power steering give the new Cabriolets evensportier driving characteristics, more precision and increasedagility. On top of that, additional active control systems areavailable as standard or as an option depending on the model,which will improve driving dynamics even further.

The new open-top models of the 911 Carreraand the 911 Carrera S also belong to the newgeneration of the classic 911 sports car – theopen-air season can begin.

The 911 Carrera Cabriolet debuts an innovative new roof design

Out in the open


High-voltage and thermodynamics test stand

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High voltage: 300 kW source/drain

Electrical characteristics

Since the end of 2010, Porsche Engi-neering has been using a so-called“direct current source/drain” with amaximum capa c ity of 300 kW for theoperation start-up of high-voltage bat-teries developed in-house.

In its function as a source (first quad -rant), it is possible to charge the batteryin constant-current and constant-voltage

modes. When it is used as a drain (secondquadrant), it fully replicates the powerelectronics, including the drive motors,which consume large amounts of power.An interesting side effect is that thepower taken from the battery can be fedback into the power grid.

Thermal characteristics

Since 2011, Porsche has also been usinga thermodynamics test stand. This pro-

vides the batteries with the right tem-perature by means of air, coolant orrefrig erant.

By using the thermodynamics test stand,all battery types with various types ofcooling systems can be tested andstarted up. There is also the option tosimulate extreme thermal conditions inthe upper limits of what the batterycan withstand, for which the battery canalso be preconditioned.

The high-voltage battery is the heart of electric and hybrid vehicles. When developing

high-voltage batteries, testing the battery with predefined profiles in both quadrants

i.e. when charging and discharging requires special attention. Porsche Engineering has

developed a special high-voltage infrastructure for testing a diverse range of batteries

and cell modules.

Particular electrical characteristics

• DC output voltage range: 8 to 800 volt• DC output current range: +/800 amps• Power range: up to 300 kW• Power factor: 0,99• Efficiency at 300 kW: 91%• Voltage tolerance: +/–1%/current tolerance 0.3%• Controllable using a CAN

control unit• Short-circuit resistant

1. AC input2. Transformer3. Controlled rectifier4. 800 volt intermediate circuit5. Bidirectional buck/boost

converter

Particular thermal characteristics

• Coolant temperature management: 20 kW cooling and heating power

• Coolant temperature: 5 to +105 degrees Celsius

• Coolant flow: 3 to 60 liters per minute at maxi-mum operating pressure of 4 bar

• Refrigerant cooling: up to 15 kW with R134a• Air cooling: 1,000 liters per second at

5 to +80 degrees Celsius


Simplified diagram of the source/drain

S.19-21_Quelle-Senke_RZ-EN+Feindaten_PE_Magazin_S4-9_RZ 18.04.12 18:40 Seite 1

Safety tests

High-voltage batteries and conventionalbatteries must fulfill the highest safetystandards. In particular, the high voltageof the battery requires a high level of in-sulation resistance against the chassisof the vehicle at both terminals. High loadprofiles also result in significant powerdissipation in the battery, which in turnleads to it heating up. During safetytests, derating functions including deac-tivation are checked by conditioning thebattery and running it through load pro-files. These are then mapped in hard-ware-in-the-loop test vectors, which weredeveloped especially for this purpose byPorsche Engineering. Typical safety testcases can be seen in the table above.

Classification/fatigue testing

Along with testing the perfect construc-tion of the battery with the naked eye,the battery is also the subject of tar -geted testing for hidden thermal andelectrical resistance at its source/drain.Above all this makes sense in endurance


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tests and the testing of electric vehi-cles, in order to attain a precise de scrip -tion of the current state of the batteryduring every revision. As part of theBoxster E research project, for ex am ple,

(see issue 01/2011 of the Porsche En-gineering Magazine), the internal re sis -tance of the battery was repeatedlytested on the cell level, thereby identify-ing the health of the battery (see figure"State of Health" below).

Porsche Engineering integrates expertisefrom various areas for the developmentof high-voltage batteries. With individualtests and analysis tailored for customerrequirements, Porsche Engineering canprovide engineering services for diverseprojects, from an electric scooter to afully electric sports car all according tothe principle of Porsche Intelligent Per-formance.

Emmanuel Dhollande, Volker Sonn,Björn Pehnert


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Cross section of the high-voltagebattery in the Boxster E research vehicle,which was testedthoroughly on the high-voltage testing stand

extremely dependent on cell chemistry,are tested using an external power mea-surement and Coulomb counting device.

Design verification

Based on electrical load profiles andthe necessary minimum capacity of thepower storage unit, the battery cells areselected and the high-voltage powercircuit and the thermal circuitry in thebattery system are designed. For thisthe temperature measurement points,which optimally define the thermal stateof the battery, also have to be laid out.

Electrical and thermal design character -istics are significantly defined by thebasic electrical power capacity, safetyand reliability, and the lifespan of thepower storage system.

In order to make sure that the design ofthe system is correct, a combination ofvarious testing methods is used. Usingsyn thetic load profiles, the character isticsof the electrical and thermal cir cuitry canbe established.

The internal resistance of the batterysystem can be precisely measured. Byallocating internal resistance parts andvarious system components (cells, cellconnectors, busbars, etc.), potentialareas for optimization can be preciselyidentified.

The testing and optimization of the con-trol strategies of the BMS for thermalmanagement and the approval of power/voltage limits are generally carried outusing load profiles, which are based onreal driving cycles.

The source/drain is connected to thethree-phase current (see point 1 in thefigure on page 19). The AC voltage isdoubled via a transformer (see point 2).A controlled rectifier (see point 3) con-verts the AC voltage into a direct voltageof 800 volt DC. A capacitor forms theintermediate circuit, and typical voltagescan be simulated using a bidirectional,buck/boost converter.

The system has two separate currentcontrollers. These enable the extremelydynamic control of the current with ad-justable low-voltage and surge protec-tion settings.

The battery under test and the testingfacility are physically separate and arecontrolled from a control room. Thetesting chamber is also equipped withan array of safety mechanisms.

Using the testing facility

The facility is used for the operationstart-up testing and design verification

Typical safety test cases

1. Testing of the BMS deactivation function: Charging or discharging power above the maximum permitted limit is fed in or out. This tests whether the BMS disables the contactors within the required time frame.

2. Precharging against a short-circuit: The facility is configured for a short-circuit. The precharging algorithms in the BMS must recognize this situation and log a fault. The main contactors must not be activated.

3. Insulation resistance: a defined parasitic resistance is connected between the chassisand the negative terminal of the battery. The BMS must clearly detect this.

4. Overcharging protection: The battery is charged until it has reached end-of-charge voltage. During the constant-voltage phase a higher voltage is fed in carefully. The BMS must disable the contactors.

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of prototype batteries. After checkingtheir component arrangement, a seriesof electrical and thermal safety testscan be carried out. This includes a fa -tigue test and the classification of differ -ent batteries.

Operation start-up of the BatteryManagement System (BMS)

Starting up a high-voltage battery systemfirstly requires the calibration of theBattery Management System in order tocheck the basic system functions. Thecell voltage in the cell controllers, theactivation of the contactors, the man -agement of charging and discharging,and the thermal management are allchecked one by one in this process.

Through an iterative process, the resis -tance- and temperature-dependent pa -ram eters are defined (for example tem -per ature-dependent electrical chargingand discharging limits). The electricalsensor in the battery and the state-of-charge (SOC) BMS algorithms, which are

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Analysis of internalresistance usingpulse dischargingprovides precisedata about the state of health ofthe battery

Load pulse3.75 C (280 amps)

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Load pulse 1 C (80 amps)

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OCV (before the discharge pulse)

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State of Health

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State of Health



Expansion at the Weissach Development Center

22

Weissach is growing.And so are the engineering services by Porsche.

With extensive construction projects, Porsche is now implementing a long-term strategic

site plan for its research and development center in Weissach. The sports car manufacturer

is investing around €150 million in a high-tech wind tunnel, a state-of-the-art design center,

and an innovative electronics integration center. This means one thing above all for engi-

neering services by Porsche: first-class resources for demanding projects.

New high-tech wind tunnel

With the new wind tunnel, Porsche isequipping itself to be able to fully meetand overcome the technological chal-lenges involved in automotive develop-ment in the future. “Good aerodynamicsmakes an important contribution to-wards lower fuel consumption and betterperfor mance – which are both impor-tant aspects of implementing PorscheIntelligent Performance,” explains Wolf-gang Hatz, board member in charge ofresearch and development at PorscheAG. These new facilities will help Porscheto maintain its top position in the fieldof aerodynamics and to further extendits lead.

been scattered across several buildingsat the Weissach site belonging to Porschecan be bundled under one roof. Workingin close proximity is a major advantage.Especially in electronics, which now playsa role in almost every vehicle component,the close interaction between differentelectrical system/electronics experts fromrelated specialist fields during develop-ment contributes significantly to the suc-cess of projects. With the new electronicsintegration center, Porsche is creatingthe optimum conditions for its objectiveto “continue developing electric and hy-brid technology,” according to Hatz.

As the facility will not just be used exclu-sively for development work by Porsche,

Cutting-edge design studio

Outstanding design has always been oneof Porsche’s strongest areas of expertise.Above all, the new studio will providemore space for the Porsche designers,who are closely involved in the earliestconcept phases of every vehicle devel-opment process. Due to an increasedworkload, greater capacity for sportscar construction is urgently needed atthe Weissach center of competence.

An electronics integrationcenter for the future

In the new electronics integration center,various subdivisions that had previously


23

Expansion at the Weissach Development Center

WEISSACH MILESTONES

16 October 1961 Work begins on the test track (construction of the skid pad)

1967–1970 Construction of circuit and “rough-road” trackfacilities for further testing purposes

1969 Construction of additional testing stands, workshops, and facilities for experiments; the cornerstone of today’sWeissach Development Center

1974 Construction of an office building in the shapeof a hexagon, which provides the ideal layout for close cooperation and teamwork

1982 The Environmental Technology Measurement Centermoves into building 26 (with testing stands that will fulfillregulations for decades to come)

1983 Construction of testing building for engines and units

1986 Inauguration of the most modern wind tunnel of its time with the best possible air flow quality and completion of the crash testing facilities

2002–2004 Completion of additional office buildings and the tire center(testing facility for fatigue and brake tests)

2007 Opening of a four-story drivetrain center (a combinedworkshop and office)

2011 Construction begins for the long-term strategic site plan with a high-tech wind tunnel, state-of-the-art design center, and electronics integration center for the future

but will also continue to be availablefor Porsche projects with external cus-tomers, it can be accessed directlyfrom the design center located besideit, but also has its own entrance for thediscreet fulfillment of confidential cus-tomer projects.

Prepared for the future

The comprehensive range of resourcesalready available for external customerprojects at the Weissach DevelopmentCenter today is now being invested inand expanded significantly.

“The symbiotic connection with theWeissach Development Center is aunique feature of Porsche Engineeringin the automotive sector,” says MalteRadmann, managing director of PorscheEngineering. With the development cen-ter’s unique and high-tech infrastruc-ture, Porsche Engineering will continueto be able to provide the optimal condi-tions for engineering services projectsin the future.


Vehicle interior climate control

24

Keeping cool in future

Comfortable vehicle climate

Customers today expect a comfortabletemperature in the interior of their ve-hicles – regardless of the conditionsprevailing outside. Multi-zone climatecontrol units in the front and back, pro-vide the option to create a comfortableclimate for each passenger, as is thecase, for example, with the PorschePanamera’s state-of-the-art optionalFour-Zone Climate Control.

A moderate interior climate, or “com-fort” in the vehicle, can be basically re-duced to the “absence of disturbing fac-tors”. The factors influencing this senseof comfort can be subjective as well asphysical or physiological.

Along with creating and maintaininga comfortable vehicle interior climatethrough cooling and/or heating it, cli-mate control must also fulfill legislativeand safety requirements. This includes

de-icing the windshield and windowswithin a defined time (for example, whencold-starting in the winter) and keepingthe windows free from condensation.

It is also important to remember that thedriver’s reaction capabilities and concen-tration in difficult situations will be betterthe more comfortable he or she feels.This means that the temperature mustbe right from head to toe (what is knownas stratification: “a cool head and warm

Some factors that influence the climate of the vehicle interior

Physiology

• Physical constitution

• Sex

• Age

• Ethnic factors

• Food intake

Subjective factors

• Clothing

• Level of activity

• Level of acclimatization

• Daily/annual rhythm

“Comfort is the absence of disturbing factors”➥

Due to new alternative drivetrain designs for the vehicles of today and tomorrow, the

entire basis of vehicle interior climate control is changing. Porsche Engineering is there-

fore ensuring that an integrated thermal management system is being developed now.

Panamera: fuel consumption (in l/100 km) combined 12.5-6.3; CO2 emissions 293-159 g/km


Physical factors

• Air temperature

• Relative humidity

• Thermal stratification,vertical/horizontal

• Thermal radiation

• Air circulation

• Air quality

• Atmospheric electricity

• Acoustics

• Visual factors

• Number of passengers

• Seasonal changes to important physical factors


25

are taken into account and checked inthe early stages of vehicle development,before the climate control system is de-signed, as their effects can vary widelydepending on the vehicle in question.

How a conventional refrigerationcircuit works

The most important parts of a climatecontrol system are the refrigeration andcooling circuits. While the refrigerationcircuit provides the energy to cool downthe vehicle, the cooling circuit for thecombustion engine collects the energyfor heating up the vehicle interior.

Refrigerant sucked in by the compressorcirculates in the refrigeration circuit. Thiscircuit is divided into two sections: ahigh-pressure and a low-pressure sec-tion. The refrigerant, in the form of agas, is heated in the compressor bybeing compressed and then channeledthrough the condenser under high pres-sure. There, heat is absorbed from thehot gaseous refrigerant, leading to a liq-uefaction of the gas.

feet”). The air distribution, cleanlinessand humidity must also be exactly right.

How a conventional climate controlsystem works

Basically there are three main operatingmodes for the climate control system ina vehicle:

• Pure heating mode: quickly heatingthe cold interior of the vehicle in winterand de-icing the windshield when tem-peratures outside are low.

• Combination mode: automatic con-trol of the vehicle climate (“car climate 22 degrees Celsius”/71.6 degreesFahren heit). Additional fresh air is firstdehumidified and is then brought tothe right temperature, to keep thewindshield and windows free fromcondensation. This combined mode is the most common one for climatecontrol systems in Central Europe, dueto the climate conditions there.

• Pure cooling mode: quickly coolingthe warm vehicle interior of the vehiclein summer, when temperatures out-side are high.

A conventional vehicle climate controlsystem design consists of the followingcomponents in addition to the actualclimate control unit: a refrigeration cir-cuit (provision of cold air) and a coolingcircuit (provision of warm air), air ductswith outlet vents, a climate control op-erating unit and a climate control de-vice (with its corresponding electricalparts such as a cable harness and sen-sors, for example).

The climate control unit measures theconditions outside as well as the currentconditions in the vehicle interior andcompares them with the target require-ments. Thus, the climate control systemcan achieve the required climate usingthe three modes. Targeted individual cli-mate control can be achieved in this way,which the two-zone automatic climatecontrol system of the new Porsche 911is capable of, for example.

These are the basic customer require-ments and expectations for future cli-mate control systems, regardless of thedrive unit design of the vehicle.

Factors that influence vehicle climate control system designs

Climate control in vehicles is influencedby many different factors. These includethe size of the passenger space, the de-sign of the dashboard, the size and angleof the windshield, the thermal mass thatneeds to be climate controlled, the ex -terior aerodynamics and thermal manage -ment in the vehicle. All of these factors

The optional Four-Zone Climate Control in the Porsche Panamera enables individual, targeted climatecontrol



Then the refrigerant enters the drier/collector. In order to protect the refriger-ation circuit from damage, impuritiesand water are separated from the refrig-erant in the drier. The refrigerant is thenpassed from the drier to the expansionvalve and enters the evaporator in amostly liquid form. There it is vaporizedby absorbing heat. Because it hasabsorbed heat from the surrounding en-vironment, the air is cooled and dehu-midified. The moisture created by dehu-midifying the air is taken away via tubes.On very humid days, this moisture canappear in the form of a puddle underthe vehicle. In the low-pressure section,the gaseous refrigerant is sucked backinto the compressor and the cycle beginsall over again.

Future challenges

In conventional drive unit designs suffi-cient „free“ energy for a comfortable cli-mate inside the vehicle is available inform of „waste heat“ from the combus-tion engine. With alternative drive unitdesigns such as those in electric vehi-cles, however, the energy for heating thevehicle must be additionally generated.The efficiency of the individual electricalcomponents is significantly higher inelectric vehicles than in combustion en-gines. The missing energy in the form ofheat that must be electrically generatedin vehicles with electric vehicle driveunits means that there is less energyavailable to propel the vehicle. The chal-lenge therefore consists of maintaining acomfortable climate in the vehicle inte -rior with as little energy as possible, inorder to affect the vehicle’s driving rangeas little as possible.

Hybridization

Vehicles with hybrid drive units have aconventional combustion engine sup -ported by an electric motor. Electricpower is stored in a battery, which alsomust be kept cool. In the Panamera S Hy-brid, the high-voltage nickel metal hydridebattery is cooled by air. The challenge forthe climate control system in a vehiclewith a hybrid drive is the additional cool-ing required for the electrical compo-nents such as the battery, power elec-tronics and the electric motor. As hybriddrives also usually have a start/stop func-tion and can drive a certain distance onelectric power alone, the climate controlsystem must be designed so that it canoperate without a combustion engine.

This means that the refrigeration andcooling circuit components, such as thecompressor, must be powered electri -cally and can no longer be mechanicallylinked to the combustion engine, in or-der to ensure that the climate controlsystem still functions when the vehiclehas stopped at traffic lights, for example.

This is made possible by special evapora-tors, which can store the cooling energyfor a certain period (storage evapora-tors), and by high-voltage PTCs for elec-trical heating. Another major challengefor climate control and thermal manage-ment system design is ensuring that thedrivetrain heats up quickly in order to re-duce fuel consumption and emissions.

Electric vehicles

Electric vehicles – like the PorscheBoxster E research vehicle – use batter-ies that require a temperature range ofbetween 20 and 30 degrees Celsius (be-tween 68 and 86 degrees Fahrenheit) intheir drivetrains. This temperature rangeensures that the batteries function prop-erly and prevents them from “getting old”too quickly. This means that the batteriesdo not just need to be cooled down, butsometimes also warmed up, dependingon ambient temperatures.

Cooling with air, which is currently thestandard method in hybrid drives, is nolonger sufficient and must be replaced


26

Hybrid components in the Panamera S Hybrid

1. High-voltage nickel metal hydride battery2. Air supply duct3. Power electronics

4. Hybrid module5. Supercharged 3.0-liter V6 engine

1

2

3

45


with liquid cooling methods using appro-priate refrigerants or coolants. Climatecontrol and thermal management aretherefore becoming more complex andrequire new thinking.

The aim of the thinking behind the newdesigns at Porsche Engineering is to re-duce the amount of heating required inthe vehicle. There is potential in improvedinsulation, which will result in the loss ofless heat via the body and the windows,and the reduction of the thermal massto be heated in the vehicle’s interior.

Innovative solutions

Options for new climate control systemdesign being considered strongly atPorsche Engineering are the use of aux -iliary heating systems (such as heatpumps, electric auxiliary heaters, fuel-powered auxiliary heaters) and targetedclimate control according to the numberof passengers in the vehicle. Other areasbeing focused on are the use of thermalstorage systems, the preheating or pre-cooling of the vehicle interior while thevehicle is being charged at the electricalpower outlet, or the use of direct andsurface heating devices in the seats andthe steering wheel.

The cooling agents and cooling andheating methods are selected by engi-neers in the earliest stages of the designprocess. For this purpose, Porsche Engi-neering has developed its own thermalsimulation tool, which was validated bytests. This can be used to work out anddefine the optimum climate control andthermal management system design atan early stage of vehicle development,

using previously identified performancedata, cooling and heating needs, anddriving profile requirements.

Conclusion: challenges and solutions

Climate control and thermal manage-ment play a very important role whendesigning hybrid and electric vehicles,as the increasing electrification of vehi-cles leads to a decrease in the numberof available sources of heat. As a result,today’s standard method of reusing the(free) engine waste heat is becomingincreasingly difficult or even impossible.

The more effective use of heated orcooled air in the vehicle interior, betterinsulation and further modifications inthe vehicle contribute to reducing en -ergy consumption for the heating andcooling of the vehicle interior. The same

is true for the inclusion of new compo-nents in climate control and thermalmanagement system design. Along withcooling the batteries in order to increasetheir lifespan, heating the batteries isalso becoming more important.

Porsche Engineering is developing solu-tions for these challenges based on com-prehensive electromobility experiencefrom internal and external engineeringprojects, as well as thermal managementexpertise from classic sports car design.Using all the tools available to them, fromsimulation and calculation tools to com-ponent testing on test stands and thetesting of entire vehicles in the climatewind tunnel and on the test track, engi-neers at Porsche Engineering are creatingthe climate control and thermal manage-ment system designs of the future.

Sebastian Ost, Michael Müller, Patrik Gisch

27


Batteries like those in the Boxster E research vehicle need to be warmed up as well as cooled down,depending on ambient temperatures

Panamera S Hybrid: fuel consumption (in l/100 km) urban 7.6-7.4 · extra-urban 6.8-6.6 · combined 7.1-6.8, CO2 emissions 167-159 g/km


Special exhibition “80 Years of Engineering Services by Porsche”

28

Who developed it? Porsche.

“In the special exhibition ‘80 Years ofEngineering Services by Porsche’, thePorsche Museum and Porsche Engineer-ing presented a selection of excitingprojects and in this way, we have built abridge from the past into the future,”says Achim Stejskal, head of the PorscheMuseum. “As an engineering servicesprovider, Ferdinand Porsche and histeam have established an internationalreputation for excellence – thousands ofcustomer projects have been completedsince the foundation of the engineeringservices office in 1931.”

A large number of invited guests and for-mer Porsche employees, including racinglegends Herbert Linge and Peter Falk, at-tended the opening celebrations of theexhibition, which ran from June 21 to Sep-tember 11, 2011 in the Porsche Museum.

One of the first ever engineering services projects byPorsche: the Wanderer W 22 from 1931

Around 20 projects from 80 years of engineering services by Porsche were exhibited in the Porsche Museum

For more than 80 years, Porsche has been globally active as an engineering services provider

for external clients. Engineering services are an essential part of the Porsche brand core, and

some of its most interesting developments were presented in the Porsche Museum.

cylinder, light-alloy engine with 1.7 or 2.0liters displacement, which would lateralso power the famous Audi Front.

Two years later, Auto Union contractedthe design of a Grand Prix racing car –one of the most legendary racing cars ofall time. Driven by racing heroes likeHans Stuck and Bernd Rosemeyer, theAuto Union “P-Rennwagen” achieved noless than 30 Grand Prix victories and 15world records between 1934 and 1937.

“The engineering services by Porscheare the oldest business segment in thePorsche company. When the companywas founded, there were no plans tobuild its own sports cars yet,” saysStejskal. And so, as part of the specialexhibition, around 20 special exhibitswere on display, ranging from the deve l -opment of entire vehicles, through en-gines and transmissions, to extraordinaryindustrial projects in the present.

One of the exhibits was one of the firstever Porsche development projects,which was contracted to the engineer-ing office by the Wanderer automotivemanufacturing company in Chemnitz in1931: the Wanderer W 22, also knownas Model 7 in the internal classificationsystem created by Porsche. The mid-sizesedan W 22 was well-known for its six-


29

The Opel Zafira compact MPV, designedby Porsche in 1994 for Adam Opel AG,was also exhibited, along with the Mer-cedes Benz 500 E, the series productionof which was even carried out in thePorsche factory in Zuffenhausen between1990 and 1994.

The anniversary exhibition, the mostelaborate special exhibition to date inthe museum, also surprised visitorswith many unusual Porsche develop-ment projects from outside the automo-tive sector: along with a Harley-DavidsonV-Rod and the sports watercraft Seabob,the Porsche Museum also showed anoriginal bobsled developed by Porscheengineers in collaboration with the pro-fessional sportsman Georg Hackl. TheOlympic sledding champion apparently

wanted to see for himself how hisPorsche bobsled was being exhibited atthe “80 Years of Engineering Servicesby Porsche” exhibition – and so hon-ored the Porsche Museum with a per-sonal visit. Hackl won the silver medalat the 2002 Olympics in Salt Lake Citywith that very sled. Another unusualexhibit was the Adventure electric, full-suspension wheel chair, which was de-signed by Porsche in 2004 for the com-pany Ulrich Alber GmbH.

“80 Years of Engineering Services byPorsche” was a unique exhibition: first-

time guests, car lovers and technologyenthusiasts alike marveled at astonishingengineering projects for external cus-tomers, some on show for the first timeever. The exhibition organizers weremore than happy with the positive re-sponse: with around 90,000 enthusiasticvisitors, the special exhibition for the 80-year anniversary of Porsche engineeringservices was a complete success.

A compact history: the history of engi-neering services by Porsche, includinglots of background information and ad-ditional pictures, is available as the an-niversary special edition “80 years ofpioneering solutions - Porsche Engi-neering” from bookstores and the mu-seum shop at the Porsche Museum inStuttgart-Zuffenhausen (ISBN 978-3-9812816-8-2).

Special exhibition “80 Years of Engineering Services by Porsche”

Above: Porsche engineers developed a bobsled forthe professional sportsman Georg Hackl

Left: Porsche Engineering developed a new enginefor the V-Rod model by Harley-Davidson

Thinking outside the box: Porsche was con tractedto design the Opel Zafira for Adam Opel AG

Around 90,000 visitors marveled at the variety ofPorsche developments


Clutch robot

30

Smoother control using robotics

Robotic systems have been used in vehi-cle pedal operation testing for some timenow. The existing systems present var -ious problems, however. Because theyrequire external sources of power andlots of space for their computer hard-

ware, in most cases they are used onlyto simulate distance profiles on rollerdynamometer test stands. Using thesesystems for vehicles actually driving out-doors is basically impossible. Further-more, only open-loop control but not

closed-loop control is possible for thesesystems, and the pedals cannot be posi-tioned precisely so that conditions canbe reproduced. They are therefore notvery useful for the analysis of clutch en-gagement characteristics. For this reason,

Requirements for vehicle drivetrains are constantly increasing, especially with regard to the

comfortable start-up of vehicles with manual clutches. In order to efficiently analyze the clutch

characteristics (clutch engagement and start-up characteristics) and to be able to reproduce

these results, Porsche Engineering has developed a unique clutch robot in collaboration with

the Münster University of Applied Sciences (Automation and Robotics department).


Clutch robot

31

The clutch robot is linked to the useroperator laptop by an Ethernet interfaceand is operated simply via an easy-to-use user interface.

Adjusting the position

The cable pull sensor first detects thecurrent position of the clutch pedal.Based on the current position and thetarget position, the controller imple-mented in the RTOS calculates the cor-recting variable for the linear motor.The implemented controller must beprecise and extremely stable through -out the whole application area. Differ entdriver’s seats in particular make thesetup of the controller more difficult inthis regard. In sports cars the seats aregenerally very firm, while in small carsthey are generally softer. In order to takethe varying dynamics of driver’s seatsinto account, various components havebeen added to the PI controller. Thecontroller is therefore completely stablethroughout the whole area of applica-tion, and there is no need for the userto modify it any further.

Areas of application

Various testing processes can be carriedout with the clutch robot. The followingthree kinds of tests are the most impor-tant applications:

• Pedal pressure measurement• Start-up testing• Stall testing

With the aid of powerful analysis soft-ware, at the start of testing, the user

Porsche Engineering has developed anew clutch robot that solves these prob -lems (an overview of the requirements ithad to meet is shown in the informationbox above).

Hardware configuration

The main unit of the clutch robot con-sists of aluminum plates, which can bemodified to fit the shape of the driver’sseat and the interior of the vehicle. Inthe main unit, three independent, closed-loop controllable linear motors are usedto operate the three pedals.

The motors are connected to the pedalsvia adapter plates and a coupling barthat can be adjusted in length, and thepressure on the pedals is measured by aload cell integrated into the coupling bar.The pedal position is detected by cablepull sensors, which are fixed firmly in thefootwell of the driver’s seat and can there - fore be used for position control with outinfluence by the seating dynamics.

After the main unit has been fitted inthe vehicle, a head unit is mounted ontop of it. The three motors are then con-nected directly to the head unit via adocking connecter, so that there is noneed for extra cables when setting upthe robot in the vehicle. The controllersfor the motors, and the computer sys -tem with a real time operating system(RTOS) and sensor signal processing,are located in the head unit. The exter-nal sensors, such as the cable pull sen-sors or the vehicle CAN bus, can beconnected to the system with standardconnecters.

Power is provided by a separate blockand is connected to the head unit via acable. This set-up makes it possible toposition the power supply anywhere inthe vehicle. Because the whole systemis separated into three components(see figure on page 32) – the main unit,the head unit and the power unit – itcan be transported easily and installedin the vehicle quickly.

Optimum analysis of clutch characteristics

Requirements

• Compact setup for the hardware and the power source, so that the system can also be used in vehicles without much space in the interior

• Simple assembly of the system without having to modify the seat or thedriver’s footwell in all vehicle classes

• Logging of variables to be measured in real time• Logging of pedal positions independently of the dynamics of the driver’s seat• Definition of the pressure placed on the pedal independently of the position of the robot

• Operation of all three pedals by the robot• Highly dynamic processes that can be reproduced exactly (e.g. snap starts/racing starts)


Clutch robot

32

Design of the clutch robot:1. Head unit2. Connection panel3. Connection to power supply4. Main unit5. Linear motors6. Coupling bars7. Load cell8. Cable pull sensors9. Power supply

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an initial evaluation of the measure-ments while the test is still going on.

Pedal pressure measurement

During the pedal pressure measure-ment test, the pressure placed on theclutch pedal and the pedal travel arerecorded. Before the test begins, thecombustion engine speed can be set tothe desired number of revolutions viathe clutch robot. The clutch pedal isthen pressed down fully and subse-quently brought back to its startingposition. The number of test repetitions

7

can choose which correcting variablesshould be saved in a measurement fileby the system with up to 1 kHz. Theuser also has the option to directly con-nect external temperature sensors tothe system. There are also interfaceswith the vehicle CAN bus and/or withCAN-based measurement systems. Datacollection is carried out by the roboticsystem itself, and the recorded datacan be uploaded to the user PC afterthe test has been carried out, in orderto visually illustrate and evaluate theresults. A live readout of the test en -ables the testing engineer to carry out


kept in a constant position by the clutchrobot during the entire test. The clutchengagement speed during vehicle start-up is then varied.

The brake pedal can also be set at adesired position in order to prevent themovement of the vehicle before the testbegins or to simulate vehicle start-up inrelation to braking power. Dependingon the set-up of the test, the brakes canbe automatically released before theclutch pedal engages at a previously de-fined, constant speed. After the test hasfinished, the robot disengages and theaccelerator pedal returns to the idle po-sition. Because the tests can be repro -duced in different vehicles, objective com-parisons can be made between them.

Stall testing

Stall testing is similar to the vehiclestart-up test, although here the vehicleis fixed in position with a tow bar. Theobjective of this test is to establish thedrive dynamics and the stability of theengine control unit in relation to the en-gagement characteristics of the clutch.The tractive power is recorded by theelaborate robotic system. The behav iorof the engine is recorded at variableclutch engagement speeds, all the waydown to standstill.

Conclusion

With the new clutch robot, the engi-neers at Porsche Engineering have de-veloped a system that intelligently meetsa number of current challenges: the sys -tem has an integrated source of power,which can be fed from the vehicle powercircuit or can be supplied with electricityby an independent battery pack. Thismakes it possible to carry out tests onvehicles driving outdoors. Measurementdata collection is carried out by the ro-bot itself. The simple setup and removalof the robot does not require the re -moval of any vehicle components. Thisenables benchmark testing in severalvehicles within a very short period oftime. Finally, by utilizing its own sensorsand carrying out its own data collec-tion, no additional measurement pro-cesses are required – the clutch robottherefore significantly simplifies test - ing the functions of man ually operatedclutches in vehicles.

Philipp Kamping, Johannes Aehling,Dr. Jan-Peter Müller-Kose

as well as the speed of pedal operationcan be selected by the user. The resultconsists of curve graphs depicting pedalpressure in relation to combustion en -gine speed.

Start-up testing

The aim of the start-up test is to mea -sure the clutch engagement limit speed.What is meant by this is the maximumspeed with which the clutch pedal canbe operated, and at which starting upthe vehicle is still safe.

Before the test starts, the clutch pedalis pressed down completely. Then theuser can set the desired combustionengine speed. The accelerator pedal is

33

Clutch robot

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Analysis software enables a preliminary assessment during the pedal pressure test

Pedal pressure measurement

Force [N]

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Force/displacement curve


Impressum

34

EditorFrederic Damköhler

Design: Agentur Designwolf, Stuttgart Repro: Piltz Reproduktionen, StuttgartPrinting: Leibfarth&Schwarz, Dettingen/ErmsTranslation: TransMission Übersetzungen, Stuttgart

All rights reserved. No part of this publication may be repro -duced without the prior permission of the publisher. We cannotguarantee that unrequested photos, slides, videos or manuscriptswill be returned.

Porsche Engineering is a 100% subsidiary of Dr. Ing. h.c. F. Porsche AG.

PublisherPorsche Engineering Group GmbH

AddressPorsche Engineering Group GmbHPorschestrasse71287 Weissach, Germany

Tel. +49 711 911 - 8 88 88Fax +49 711 911 - 8 89 99

E-mail: [email protected]: www.porsche-engineering.com

Impressum Porsche Engineering Magazine

www.porsche-engineering.com


Next Up

New. Dynamic. Trailblazing.

Ready for some new spirit?Issue 2/2012 of the

Porsche Engineering Magazinewill provide you with latest news on

our engineering projects including details about the development of the new Boxster.

Boxster (Type 981): fuel consumption (in l/100 km) combined 8.8-7.7; CO2 emissions 206-180 g/km

For further information, please visit www.porsche-consulting.com.

You don’t need to build sports cars

to deliver fast solutions, but it helps.

Porsche Consulting.

Porsche Engineering Magazine 2012/1

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