Issue 02/2004 Porsche Engineering Magazine Ceramic clutch: The PCCC (Porsche Ceramic Composite Clutch) from Porsche – a world first fitted as standard in the Carrera GT super sports car. Wheelchair chassis: The electric wheelchair from the Alber company sets new standards in its segment. Porsche Engineering played an instrumental role in the development of the chassis. Focus on the complete car: Porsche's competence in the development of high-perform- ance variants is particularly evident in the 911 GT3 RS, which has been fitted out especially for motor racing. Contents Porsche Engineering Group GmbH Porsche is the only car manu- Together with its subsidiaries in (PEG), a subsidiary of facturer to place its comprehensive Germany and abroad, the Porsche Dr. Ing. h.c. F. Porsche AG, is engineering know-how at the dis- Engineering Group offers engineer- responsible for the sports car posal of international customers ing services relating to the area of manufacturer's worldwide contract from various branches of industry. cars and transportation worldwide development activities. under the joint brand name of Porsche Engineering. Editorial Page 4 Drivetrain Testing Body & Safety Engine Chassis Thoroughbred racing engineering for safe and enjoyable driving Page 9 The ceramic clutch – a world first from A wheelchair all set Porsche for adventure Page 5 Page 14 To this end, Porsche Engineering is If you would like to know more able to draw on the capabilities of about Porsche Engineering, please over 3,000 employees from the send an e-mail requesting our areas of design, prototype con- image brochure to the following struction, testing, process planning, address: procurement, logistics or produc- [email protected] Insights tion. The new Porsche 911 comes in two variants Page 21 Electrics & Electronics Complete Vehicle Industrial Engineering Styling Production Support Expertise in complete vehicle development Page 17 Special Design and testing working hand in hand for 30 years Page 22 Editorial Dear readers, Lightweight design. In this issue we High performance. Porsche present the Carrera GT's innovative Engineering has long been a part- body structure made of carbon ner to international vehicle manufac- fiber materials. The development of turers in developing high-perform- this structure called on our engi- ance variants of standard produc- neers to to optimize existing tech- tion vehicles. Early examples here nologies and to try out a whole include the Audi RS2 or the range of new approaches. In addi- Mercedes-Benz 500E in the 1990s. tion to the monocoque, the sub- This issue illustrates the special frame has also been developed in challenges involved in developing a carbon fibre-reinforced plastic high-performance derivative on the (CFRP) - an absolute first for a stan- basis of a standard production dard production vehicle and a highly vehicle by reference to the current practical development for everyday 911 GT3 RS. use. One quality which our customers Once again, this issue presents a small selection of value is our willingness and projects from Porsche's development activities. capability to venture into other fields of application. We develop an Porsche Engineering stands for innovative solutions. array of other products, in addition Solutions which we also offer to you, our international to cars. One area is medical engi- customers. After all, why should you need to re-invent neering. Our experience from the automotive field led to astounding the wheel? results in developing the chassis for an electric wheelchair. Low position design. Another tech- nological highlight is the new We hope you enjoy reading this Porsche Ceramic Composite Clutch issue. (PCCC), which has initially been developed especially for the Carrera GT. In addition to optimis- ing the weight of the vehicle, the lowest possible position has also been achieved for the powertrain. This called for a small clutch, how- ever. Here again, the focus is on practicality in everyday use. 4 Porsche Engineering Magazine 02/2004 Porsche Ceramic Composite Clutch Drivetrain The ceramic clutch – a world first from Porsche The ceramic clutch enables a particularly low center of gravity for the engine. The Carrera GT super sports car is the first standard production vehicle in the world to be fitted with the Porsche Ceramic Composite Clutch (PCCC). The double-disk dry clutch developed by Porsche meets the typical racing require- ments of a small diameter and low weight combined with a long service life. Porsche set itself ambitious aims in in diameter as possible, as the ter of gravity will be. Previously, developing the Carrera GT: The position of the center of gravity is a only a carbon-fiber clutch had been overall objective was to evolve a crucial factor in a vehicle which able to provide these typical racing super sports car from existing sets out to be a super sports car. characteristics. This option would racing vehicle concepts which The smaller the clutch and the have fallen short of the given would be suitable for everyday use shorter the distance between the requirements with regard to service and which could be produced in center of the crankshaft bearings life, driver comfort and practicality small batches. One of the central and the underside of the engine in everyday use, however. topics here was the clutch, which housing, the lower the engine can needed to be as light and as small be installed and the lower the cen- Porsche Engineering Magazine 02/2004 5 Drivetrain Porsche Ceramic Composite Clutch robust, heat-resistant and durable option here. In the first test, a conventional clutch was configured with a short- staple fiber ceramic material. The conventional material failed to with- stand the stress induced by centri- fugal force and friction heat. The special innovative arrangement of a fabric structure consisting of car- bon fibers as the load-bearing ele- ment enabled the strength of the carbon fibre-reinforced silicon car- bide disks to be increased to such a degree that the clutch system was able to withstand engine speeds of up to 20,000 rpm com- bined with extreme thermal loads without incurring any damage. The Carrera GT is the first standard pro- duction vehicle worldwide to be fitted with the new ceramic clutch. As no appropriate clutch system for the Carrera GT was available on the market, Porsche's engineers teamed up with selected partners to develop a completely new clutch using innovative materials for fric- tion disks and linings. In the course of these development efforts, the specialists were able to draw on experience which they had acquired with the Porsche Ceramic Composite Brake (PCCB). The short-staple reinforced ceramic material proved an extremely A water jet cuts the friction disk out of the ceramic plate at around 3,000 bar. 6 Porsche Engineering Magazine 02/2004 Porsche Ceramic Composite Clutch Drivetrain Several layers of carbon fibre fabric are processed with carbon-rich resin to produce plate material, which is subsequently converted into carbon at approximately 800 degrees Celsius and then siliconized at 1,400 degrees Celsius. The individ- ual disks are cut out of the result- ant ceramic plates by means of a high-pressure water jet. The subsequent tests confirmed that these disks were now able to cope with the high levels of stress, displaying only a very slow rate of wear. The driver comfort aspect also had to be taken into account. The dynamic ten-cylinder engine with its extremely low rotational mass made moving off with the necessary com- fort a particular challenge for the Porsche developers. The PCCC in the overload test on the Porsche test bench. The synchronization of the manual The maximum thermal load for the Comprehensive tests on the test transmission was optimized so as disks made of carbon fibre-reinforced bench and extensive trials in the to require only low shifting forces. silicon carbide is over 1,400 degrees vehicle under extreme loads Celsius and is thus not a critical showed that the PCCC is able to at When tests carried out on the test factor. least match the service intervals of bench to examine misuse revealed conventional clutches. temperatures of over 800 degrees Lining carrier disks made of titani- Celsius in the ceramic friction um with rivetted-on sinter linings disks, it became clear that the were chosen for the driving disks. materials for all the components in This choice combines resistance to the clutch would have to be select- centrifugal forces and high temper- ed with corresponding care. atures with low weight and a sub- sequent low rotating mass. Porsche Engineering Magazine 02/2004 7 Drivetrain Porsche Ceramic Composite Clutch development which possesses excellent future prospects for high- stress applications in standard pro- duction vehicles, too. The comprehensive experience which Porsche's engineers have acquired in the fields of composite ceramics, PCCC and series produc- tion can be applied in the develop- ment of the most diverse types of drives - particularly in the high revs range. Porsche Engineering offers this knowledge in the international arena. ■ The small diameter of the clutch disks enables a low position for the crankshaft. The engineers have thus more than met the requirements for the clutch Technical information of the Carrera GT. Notwithstanding Type Two-disk dry clutch the fact that the costs are substan- External diameter 192 mm tially higher than that of a conven- Weight 3.5 kg tional clutch on account of the high- Materials Carbon fibre-reinforced silicon carbide ly involved production process and Transmission Maximum of more than 1,000 Nm the small quantity produced to Run-out speed Over 20,000 r.p.m. date.The PCCC trailblazes a line of 8 Porsche Engineering Magazine 02/2004 Body structure of the Carrera GT Body & Safety Thoroughbred racing engineering for safe and enjoyable driving Just like thoroughbred racing vehicles, the Carrera GT has a rolling chassis.