Porsche Cayenne Hybrid At The Los Angeles Auto Show
Published 11-12-07
Automotive Tech
Dr. Ing. h.c. F. Porsche AG, Stuttgart, is presenting drive concepts particularly friendly to the environment at the Los Angeles Auto Show starting on November 16, 2007: The highlight of this event at the Los Angeles Convention Center is the first appearance of the Cayenne Hybrid in America.
Porsche will be offering a hybrid version of the Cayenne sports utility vehicle by the end of this decade. Based on the Cayenne with its V6 power unit, prototypes of the Cayenne Hybrid are already on the road today. This revolutionary new model will combine Porsche’s 3.6-litre gasoline engine featuring Direct Fuel Injection (DFI) with an electric motor, already giving the vehicle composite fuel consumption of 9.8 litres on 100 kilometres in the new European driving cycle (NEDC) and 28 miles per gallon in the US FTP cycle. And making further improvements, Porsche is looking at a further reduction of fuel consumption to just 8.9 litres/100 kilometres by the time the Cayenne Hybrid enters the market.
Porsche is taking a new approach, opting for parallel full hybrid instead of the branched or split power hybrid concept. Indeed, many reasons speak in favour of parallel full hybrid:
* The high degree of compatibility of the hybrid components, on the one hand, and the existing platform of the Cayenne, on the other. The risk of having to accept restrictions affecting the capacity of the luggage compartment or all-wheel drive, for example, is reduced to a minimum by parallel full hybrid.
* Greater fuel savings when driving overland and on the autobahn. Contrary to other hybrid concepts which offer their benefits primarily in city traffic, the system chosen by Porsche provides the option to run the vehicle without the combustion engine at speeds of up to 120 km/h or 75 mph.
* Parallel full hybrid significantly improves both acceleration and elasticity, making the concept a perfect match for Porsche’s philosophy to offer exceptional performance combined with maximum efficiency in one.
System with three main components
Parallel full hybrid is made up of the combustion engine, the electric motor, and the battery. These components are coordinated and masterminded by the Hybrid Manager receiving all driving and energy information and controlling the electric motor as well as the combustion engine for optimum fuel economy under all driving conditions and at all times.
Some 20,000 data parameters have to be defined for the Hybrid Manager. For comparison, conventional engine management requires just 6,000 parameters.
The system battery is housed in the trough beneath the luggage compartment of the Cayenne normally accommodating the spare wheel. It is made up of 240 cells generating overall output of 288 volts. The battery operates at an output of 38 kW and stores the energy generated while driving by the recuperative brakes and the shift in the load point of the combustion engine serving to optimise fuel economy. The energy recovered in this way can then be used to drive without the combustion engine exclusively on electric power or to support the combustion engine while in use.
Electrohydraulic steering making its debut
Hybrid technology requires solutions also to other challenges. On a conventional vehicle, for example, the power steering and brake servo depend on the combustion engine running at all times. In the case of hybrid drive, by contrast, the steering and underpressure pump for the brake servo have been electrified and the mechanical oil pump on the automatic transmission has been replaced by an electrical oil pump. An important first-time achievement by Porsche in this segment is the introduction of electrohydraulic steering offering the control and precision so typical of Porsche and Porsche cars.
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Print | posted on Monday, November 12, 2007 2:33 PM