2010, the first Porsche Cayenne will come with hybrid drive on the market. He is the next consumption-reducing innovation, with the Stuttgart their SUV range will wean the excessive drinking habits.
Basis for the hybrid powertrain is a V6 petrol engine from Audi stocks. The aggregate three-liter, direct injection and supercharging, Audi has developed just last year. While it makes the brand with the four rings from 213 to 245 kilowatts, it offers only Porsche with 245 kilowatts of power and 440 newton meters. The charge by riemengetriebenem compressor means two things. By the power requirements of the compressor in this technique, the fuel consumption in comparison with an equally strong engine with a turbocharger is not quite as high. However ensures the compressor in the lower speed ranges for much more agility. "We use the electric motor and the battery capacity for mainly electric starting and steady cruising at higher speeds," says Dr.-Ing. Michael Head, Project Manager for the Cayenne Hybrid.
The 38-kilowatt synchronous electric motor from Bosch, together with the clutch only 15 inches long and fits relatively easily between the V6 and the eight-speed torque converter automatic by Aisin. This configuration allows the first three normal modes: conventional drive with a combustion engine, accelerating with combustion engine and electric motor (boosting) and driving with only the electric motor. There is also a control strategy for converting kinetic energy into electrical energy and subsequent storage in the nickel-metal hydride battery (regeneration) by Sanyo and the stop-start function.
Two other modes
The engineers have the Cayenne Hybrid but still planted two additional modes that make up the majority of the approximately 2.5 liters less fuel consumption compared to conventional Cayenne with VR6 engine: the load point shift modes and sailing. When the load point of the V6 engine, for example, is used not only for propulsion, it also simultaneously charges the battery. This higher load, he works in map areas that are more fuel efficient.
Solely by the load point displacement and further optimization of engine measures implemented 44 percent of under Porsche Cayenne Hybrid (8.9 liters per 100 kilometers, 210 grams of CO2 per kilometer) compared to a conventional Cayenne with VR6 engine (12.4 liters, 294 grams CO2) emissions. Other measures include the modern V6 engine, demand-controlled ancillary components, and an eight-speed automatic transmission with torque converter lockup instead of the current six-speed automatic. Using the new dual clutch transmission have been discarded because the automatic transmission, especially when starting with a trailer is better.
Electric driving contributes to an additional 26 percent of under-spending. Porsche concentrates on the electric motor operating mainly on purely electrically powered driving. Less on the supportive boost function during acceleration because the supercharged V6 compressor already has a good torque curve. The Cayenne Hybrid will be driven in large areas with low load demand, or only with the electric motor. In addition, here's the clutch between the combustion engine and electric motor into play. It decouples the engine from the rest anyway dormant drivetrain, preventing unnecessary braking drag torques. The first German production hybrid Mercedes-Benz S 400 is still the way to a rigid engine-transmission connection to the market.
Reactivation of the internal combustion engine in 0.3 seconds
Calls to the driver more torque and the energy storage is exhausted, the combustion engine is in less than 0.3 seconds is coupled to the drive train, and from the electric motor is started. "The sails are phases in the current testbed possible up to a speed of 138 kilometers per hour, to the start of this mode should be extended until at 157 pace," said Head. Overall, the process developed by Bosch hybrid management for the complex control strategy more than 20,000 parameters. For comparison, a conventional motor control comes from with 6,000 parameters.
The introduction of the sail and their expansion phase up to a brisk highway speeds makes sense, since the typical driving profile of the Cayenne contains more intercity and highway routes and smaller urban units with stop-and-go traffic.
The sailing mode, the Cayenne ruled on a splash and sail around Stuttgart already very well when the driver's foot on the accelerator and curbing the flow of traffic as evenly as possible about his death. The reactivation of the engine is almost imperceptible to the driver. The hybrid Cayenne consumed on the average driving profile approximated circuit just over nine liters per kilometer. Remarkably, after all he is about 170 kilograms heavier than his brother, with series six-cylinder. Since the electric motor in addition to the rather moderate power of 38 kW but develops 285 Nm of torque, comply with the performance and acceleration values which the larger V8 engine. This approval, however, the cycle 15 liters of petrol per 100 kilometers, 355 grams of CO2.
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