Patent ID: 7681392
Filing Date: 2010-03-23
Classification: B60K,B60W,F04B,F16D,Y02T

Abstract:
1. A hydraulic drive system comprising: a high pressure storage device; a low pressure storage device; a pump-motor operating at a range of pump-motor speeds for converting between hydraulic energy and mechanical energy, said pump-motor disposed between said high pressure storage device and said low pressure storage device; a selectively rotating shaft associated with mechanical energy; and a variable clutch for selectively transferring mechanical energy between said selectively rotating shaft and said pump-motor, said clutch including a proportional valve, wherein a clamping signal controls a clamping force to said clutch, said clutch entering an engaging state once a time for clamping said clutch elapses or a change in pump-motor speed exceeds a predetermined offset, said clamping signal is stronger than an engaging signal applied while said clutch is in said engaging state.