GB1378345A - Drive control system for a hydraulic elevator - Google Patents

Abstract

1378345 Hydraulic control systems for lifts R W BLAIN 16 Feb 1972 [20 Feb 1971] 7134/72 Heading B8L [Also in Division F2] A drive control system for selectively driving an hydraulic elevator at either full or creeping speed, comprises a check valve 2, between a fluid pump 10 and the elevator cylinder 17, a circulating valve 3 between the pump 10 and fluid reservoir 30, and a setting valve 4 operable by a sealing element 14 of the check valve 2 and between the circulating valve 3 and the fluid reservoir 30, the elevator travelling at full speed when the check valve 2 is fully open and all the fluid from the pump 10 passes to the cylinder 17 and travelling at creeping speed when the circulating valve 3 opens to exhaust some of the supplied fluid to reservoir 30. The sealing element 14 of the check valve 2 is spring biased towards the closed position and has tapered peripheral orifices in its cylindrical wall, whereas the valve element 32 of the circulating valve 3 is spring biased to the open position and also has tapering orifices. Fluid supplied from the pump 10 passes into a pump chamber 13, along a passage 36 and 34 to a chamber 18 beneath the movable element 32, and through one line 68 to a first solenoid operated two-position valve 29 and through another line 19 to the setting valve 4 from which the fluid passes along a line 27 to a second solenoid operated two position valve 28. For full speed operation of the elevator, both valves 28, 29 are closed whereby the full pressure fluid from the pump is held in the chamber 18 causing the circulating valve 3 to close against its spring 33 and the full pump pressure opens the check valve element 14 for full flow to the elevator cylinder 17. To obtain the creeping speed, the valve 28 is opened and pressure is released from the chamber 18 through passages 21, 22 and 53 in the setting valve 4, permitting the spring 33 to open the element 32 to exhaust fluid from the chamber 13, whereby the element 14 partially closes restricting the fluid supply to the cylinder 17. Closing movement of the element 14 however raises a contoured stem 42 of the setting valve 4 relative to the passage 53 in the setting valve sleeve 47 to reduce the rate of exhaust of fluid to the valve 28 whereby the pressure in the chamber 18 is stabilized in relation to the movement of the sealing element 14 of the check valve. The sleeve 47 is vertically adjustable (in Fig.) to pre-set the relative positions of the passage 22 and the contoured part 51 of the stem 47, whereby the creeping speed may be pre-set. When the elevator is to be stopped, the solenoid valve 29 is opened to exhaust all the pressure from the chamber 18 and the circulating valve completely opens exhausting all the pumped fluid. The opening limit of the valve 3 is adjustable by a screwed stop 61, 62.