| 摘要 |
1456256 Fluid pressure winch control circuits POCLAIN 9 May 1974 [25 May 1973] 20604/74 Heading B8B A control circuit for a winch (not shown) coupled to a fluid pressure motor 7 is shown in the configuration particular to unwinding of the winch as when a trawl net (not shown) is being paid out. Fluid from a tank 3 is fed through pipe 4 at pressure PA (Fig. 3) and pipe 10 to chamber 8 of the motor 7. Fluid from chamber 9 of the motor 7 at pressure PR is fed by pipe 11, and pipe 18 to the tank 3. A first calibrated discharge valve 19 (set at 150 bars) and a second calibrated discharge valve (set at 100 bars) are arranged in the pipe 18 and a tie-pipe 22 with a constriction 23 connects the pipe 4 to a point in the pipe 18 between the two valves 19, 20. Also shown in the circuit are a flow limiter 12 (not essential) acting in known manner to limit the motor speed and a third calibrated valve 21 (set at 10 bars). When the motor 7 is rotating at slow speed, O to N2 (Fig. 3), the flow from the pump 1 exceeds the requirements of the motor 7 and the excess passes to the tank 3 through tie pipe 22 and constriction 23 and valves 20, 21. At very slow speed (less than N1) the load loss created by the constriction 23 is greater than the calibration pressure of the valve 19 and the motor torque is then positive. When the speed of the motor driven by the trawl net lies between N1 and N2 the load loss due to the constriction 23 is less than the calibration pressure of the valve 19 and the motor torque is negative corresponding to braking the motor 7. When the speed of the motor 7 driven by the trawl net lies between N2 and N3 the pump flow is insufficient and the motor requirement is made up by the return flow from the motor passing through pipe 22 and the constriction 23. In the limit, beyond N3, between N3 and N4 closure of the speed limiter 12 brings about a very considerable increase in the pressure PR causing powerful braking of the motor 7.
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