Innovative Clutch Systems for Switching Ancillary Aggregates of Heavy Duty Diesel Engines

The situation of the raw material markets has a clear tendency in the future: raw material will be more and scarcer and so steadily more expensive. Concerning that issue we have only seen the beginning of this development. Fleet owners of commercial vehicles so have to cope with increasing operation cost due to higher fuel cost. The progressing development of the exhaust gas restrictions being found in all relevant world markets contributes to the demand of reducing fuel consumption, as each drop of fuel not burned does not affect the exhaust gas bill of a commercial vehicle. Some years ago increasing engine efficiency was the main path to reduce the fuel consumption. Starting with the global exhaust gas emissions restrictions the chemical engineers got the last word during engine development, as only if their demands are fulfilled completely the latest exhaust gas regulations can be matched. So, the ancillary aggregates came into the focus by searching new possibilities for saving fuel. The power consumption of these aggregates like fans, water pumps etc. are sometimes called "parasitic losses". Many aggregates are driven permanently, although there are many operation conditions, where they are not used. Besides the unnecessary fuel consumption this causes also more wear and reduces their lifetime. However, some very innovative approaches (up to series products) have been made during the last years to cope with this topic: switched fan drives promising the biggest savings, switched water pumps, switched break air compressors and switched alternators all are devices consuming many kW although often not being used for long time periods during driving. Sometimes completely new system control aspects have to be taken into consideration, even if they seem to be unusual at a first glance. But comparing applications of different aggregates show rapidly that it is worth to think beyond present well known horizons.