IHT controlled serial hydraulic hybrid passenger cars

The 'hydrid' is a fairly new serial hydraulic hybrid drive line concept. The term ‘hydrid’ is used for hydraulic drive lines in which four constant displacement Floating Cup (FC) wheel drive units are pressure controlled by means of two Innas Hydraulic Transformers (IHT). It has been shown in earlier publications that a four wheel drive hydrid drive line with wheel hub motors realises reductions of fuel consumption and CO2 emission of more than 50%. In modern passenger cars, there is a large gap between - on one hand - the engine power and wheel torque necessary to fulfil the maximum performance requirements and - on the other hand - the quite modest power and torque demand in normal, every-day use. This gap is the main reason for the rather bad energy efficiency of modern passenger cars. Contrary to other hybrid concepts, the hydrid can bridge this gap and achieve large reductions without compromising performance. This paper shows how the use of floating cup technology, the pressure amplification capability of the Innas hydraulic transformer (IHT) and a four wheel drive line topology, come together to realise this. After that a serial hydrid front wheel drive line is presented, which can realise similar reductions but uses only one IHT and two FC drive units, which attach to the front axle differential. Finally, some ideas for other serial hydrid drive lines are given.