| 摘要 |
<p>In a power transmission system (T) for a four-wheel drive vehicle, a multiple disk clutch (11) for distributing a proportion of the torque of the front wheels to the rear wheels is provided between a driving shaft (5) which is connected to the front wheels which are main driven wheels and a driven shaft (6) which is connected to the rear wheels which are auxiliary driven wheels. Between the driving shaft (5) and the driven shaft (6) a torque cam mechanism (12), a hydraulic pump (13) and a bidirectional clutch mechanism (14) are provided, in that order. When the rotational rate of the front wheels exceeds the rotational rate of the rear wheels, the bidirectional clutch mechanism (14) is engaged, a first rotor (23) of the hydraulic pump (13) which is operatively connected to the front wheels and a second rotor (24) which is operatively connected to the rear wheels rotate relative to each other, and a rotational load is generated by a hydraulic circuit (25). A first cam element (19) and a second cam element (21) of the torque cam mechanism (12) rotate relative to each other as a result of the above-mentioned rotational load so as to generate a thrust force, and this thrust force causes engagement of the multiple disk clutch (11) so as to put the vehicle into a four-wheel drive mode. It is thus possible to decrease the torque transmission capacity of the bidirectional clutch mechanism (14) so reducing its size and cost. <IMAGE></p> |
