Porsche releases more Cayenne Hybrid details
The Cayenne S Hybrid will deliver the power of a V8 and the efficiency of a four-cylinder
Porsche AG today released more information about its Cayenne S Hybrid, which will debut next year. Using a parallel full hybrid design with the electric motor between the combustion engine and the transmission, Porsche engineers have been able to drive at speeds up to 140 km/h without using the combustion engine.
This engineering achievement allows the Cayenne S Hybrid to coast at highway speeds without the gasoline engine on, greatly minimizing emissions and fuel consumption. This differs from current hybrids that deliver benefits mainly in city traffic. Porsche, in cooperation with Volkswagen, opted for a parallel full hybrid as it also significantly improves acceleration, a concept that matches the company’s philosophy of combining performance and efficiency. It also fits in the Cayenne with minimal alterations, without affecting interior or luggage space.
When it comes to market in 2010, the Cayenne S Hybrid is expected to emit 20 percent less C02 than comparably powerful combustion engine vehicles. Covering a 0-to-100 km/h sprint in just 6.8 seconds, it delivers V8 performance and four-cylinder efficiency.
The Cayenne S Hybrid uses a supercharged Audi 3.0-litre V6 engine with Direct Fuel Injection (DFI), 333 horsepower and 324 lb-ft of torque. It is mated with a 52-hp three-phase electric motor that produces up to 221 lb-ft of torque and also acts as an alternator. The combined power units are joined to an eight-speed automatic transmission. Also on board is a no-maintenance, 38-kW nickel metal hydride (NiMH) battery that fits in the spare tire well.
The heart of these technologies is the powerful Hybrid Manager, which juggles some 20,000 data parameters. Since a parallel full hybrid operates in three classic hybrid modes – power generated by the combustion engine and electric motor, power generated by the combustion engine only, and power generated by the electric motor only – the Hybrid Manager coordinates these modes to deliver optimal performance and efficiency.
With a clutch being the key connection between the combustion engine and the electric motor, the Hybrid Manager has the tough job of providing smooth but quick switching among the three hybrid modes without delay or a noticeable transition felt by the driver and passengers. For example, the Cayenne S Hybrid can motor along solely on electric power for up to 1.9 km with the gas engine off, and the Hybrid Manager will fire up the engine as soon as the driver presses the accelerator, increase engine speed appropriately and engage the clutch to transfer power to the transmission without the driver or passengers noticing what is happening. All within 300 milliseconds.
When driving with just the combustion engine, the Hybrid Manager also will ensure the engine is operating as efficiently as possible. It switches the electric motor to an alternator mode, so the fuel consumed by the combustion engine not only powers the Cayenne but also generates electricity that can be “parked” in the battery. Finally, when the driver presses the brake, the Hybrid Manager feeds as much energy as possible from the electric motor (again running as an alternator) to the battery.
The Cayenne S Hybrid uses an eight-speed automatic. Porsche engineers added to the conventional transmission oil pump a new electrical drive pump to shift gears smoothly and efficiently in electric mode. Top speed comes in sixth gear, while the two higher gears serve to further reduce engine speed to enhance fuel economy. It also has electrically-driven ancillary components such as the air conditioning compressor and the power steering pump.
Porsche expects the Cayenne S Hybrid to consume less than 9 L/100 km in the New European Driving Cycle. Transport Canada fuel economy figures are not yet available.
