| 摘要 |
<p>An automatic transmission is operated by a hydraulic actuation system comprising an electric motor driven pump 223 delivering pressure, via non-return valve 276, to a main control valve 120, gear engagement control valves 144, 146, a clutch actuator 22 and to gear engagement actuators 114, 115. Main control valve 120 selectively connects the clutch actuator 22 to an accumulator 275 or to a reservoir 278 and also controls connection of the gear engagement actuators 114, 115 to the pump 223. A port 326 of recuperation valve 320 is connected to the reservoir 278 via gear engagement control valves 144, 146 so that spring (334, fig 10) urges piston (321) away from valve seat (328) opening inlet (330) and connecting displacement valve 300 and clutch actuator 22 to the reservoir 278 which delivers low pressure fluid to the actuator 22, thereby replenishing fluid, when actuator 22 is not under fluid pressure, required as a result of clutch wear. The gear engagement control valves 144, 146 selectively connect first and second working chambers 118, 119 of actuators 114, 115 to the main control valve 120 or to the reservoir 278. A pressure sensor 282 may be used, in a closed loop feedback control system, to control the pressure produced by the pump 223. Potentiometers 226, 227 may also be used in a closed loop control system to control valves 144, 146.</p> |
