| 摘要 |
1474650 Hydraulic control circuits GENERAL SIGNAL CORP 22 July 1975 [22 July 1974 (2)] 30585/75 Heading F1P [Also in Division G3] A hydraulic circuit includes a pump 12 driven by a motor 44, actuators 34, 35 and a control circuit 50 connected to both the pump and the motor for permitting the delivery of power to the actuators when the motor is operating up to a predetermined speed, and for stopping delivery of power when the motor is running above the predetermined speed. As described, the circuit is used in a refuse vehicle in which the actuators compress refuse. When the motor 44 is idling, the pump 12 delivers fluid through a restrictor 18, thus, the difference in pressure between lines 20, 22 is 200 p.s.i. A speed control pump 52 is supplying fluid at a low flow rate through a line 56 and a throttle 58 and at this rate of flow no pressure drop occurs across the throttle 58. The fluid then passes to a reservoir 25 through a check-valve 63 and solenoid valve 160. When the motor 44 speeds up, the pump 12 delivers fluid at a greater rate of flow. The pressure drop across the restrictor 18 increases and this is sensed by a flow control valve 100 via signal lines 20, 22. This causes control plunger 107 to move towards the spring chamber end 104 until a land 108 allows fluid to pass from a line 66 to destroke line 88. Reservoir line 92 is restricted by land 110 and pressure builds up in line 88 and fluid flows through line 90 into destroke chamber 128. Here it moves rod 134 and destrokes the pump 12. If the supply to actuator 34 is cut off by operating a valve 32 pressure in line 16 rises and moves a plunger 136 to the left thus allowing fluid to pass through lines 88, 90 into chamber 128. This causes further destroking of the pump 12. If the motor is speeded up by driving the vehicle, speed control pump 52 delivers more fluid to line 56 and flow is choked by the throttle 58. This causes plunger 78 to move to the left which again causes destroking. Operation of solenoid valve 160 also causes destroking by dead leading the flow from pump 52. |
