Patent GB-547960-A (GB)
Title: Improvements in or relating to fluid pressure remote control systems
IPC: F16H61/02
Filed: 1941-03-24
Abstract: 547,960. Fluid-pressure servomotor-control systems. AUTOMOTIVE PRODUCTS CO., Ltd., and CARLTON, Q. H. March 24, 1941, No. 3976. [Class 135] In a liquid pressure remote control system having a double-acting motor cylinder unit, main pipe lines are provided for moving the piston to its end positions and one or more auxiliary pipe lines for moving it to an intermediate position or positions, all pipes not being fed with pressure liquid being connected to a reservoir. Each auxiliary pipe line contains a change over valve operated by the piston and a time-controlled device may be provided for limiting the duration of liquid supply to any pipe line. The form shown in Fig. 1 comprises a reservoir C, pump B, accumulator D, a motor unit E to operate a gear box, a throttle actuating motor G, a device H for determining initial setting of the throttle, and a control device A having plungers 16 ... 19 maintained in contact with cams 20-23 on a shaft with an operating handle 10 movable in either direction from a neutral position 107. In the neutral position shown, the plungers 16, 17 are in their intermediate positions, the plungers 18, 19 are fully raised, and pipe lines 43, 44 and 45 communicate with the reservoir. The initial part of the movement of the handle 10 to either side of the neutral position causes a lobe 100 or 110 fully to depress the plunger 18 ; subsequently, the plungers 16, 17 are operated equally, the plunger returns at a rate governed by a constriction 28 in a piston 25, and pressure liquid is delivered from the accumulator D to the main pipe line 43 or 44 until the plunger 18 has completed its return, thus causing the piston 53 to be moved to one or other end of its cylinder. Movement of the handle 10 beyond predetermined positions causes the depression of the plunger 19, liquid thus forced through the pipe line 83 acting on the piston 85 of the throttle actuator G, the initial position of the piston 85 having been determined by adjusting a piston 93 acting through a hydraulic link. When the handle 10 is returned to its neutral position, the valves 16 and 17 are restored to the positions shown, and owing to the new depression and subsequent slow rise of the plunger 18, pressure liquid is supplied for a short time from the accumulator D to the auxiliary pipe line 45, from which it passes via a valve 66 or 67- opened through a rocker 60 during the previous movement of the piston 53 from its central position, to operate a valve 72 or 74 and thus obtain access to the appropriate cylinder end to return the piston 53 to its central position where the valve 66 or 67 is in closed position. Movement of the piston 53 past its central position causes the other valve 66 or 67 to be forced off its seat to allow entrance of pressure liquid to return the piston 53. The arrangement may be modified to hold the piston 53 in one or each of its end positions by extending the lobes 100 and/or 110. In the modification shown in Fig. 2, a single plunger 115 replaces the plungers 16, 17, the cams engage rollers on pivoted arms, the arm for the plunger 18 being pressed up by a spring, and the accumulator D is dispensed with. When the plunger 18 is up, liquid from the pump outlet 33 passes through passages 138 and 119 and returns to the pump inlet 31, and the pipe lines 43,44,45 communicate with the reservoir C. While the plunger 18 is returning slowly after depression, ports 120, 121, 122 are blocked, the pump builds up pressure, which passes through a passage 128 and a pipe line 43 or 44, depending on whether the plunger 115 has been raised or lowered. As in the first form, return of the handle 10 to its neutral position, causes pressure to be supplied to the pipe line 45. In the motor unit shown in Fig. 5, the push rods for operating the valves 66, 67 are pressed down by strong springs 150, and pistons 153, 154 replacing the pistons 75, 81, Fig. 1, have axially spaced lands 161, 162 each narrower in width than the ports 159, 160, the lower lands being drilled and provided with a non-return valve 164, the arrangement preventing blockage in the event of the pistons not returning fully to their lowest positions. The rocker 60 consists of a pair of spaced plates between which the piston rod 54 passes. The arrangement shown in Fig. 6, in which the piston has two intermediate positions 53a, 53b, has two rocker members 60a, 60b, the first adapted to operate valves 66a, 67a, and the other valves 66b, 67b, pairs of these valves being in operative connection with the valves 72, 74, Fig. 1. The system includes pipe lines 45a, 45b, with branches 170a, 170b, 171a, 171b, each branch having a valve such as 172a closed hydraulically when there is pressure in another branch such as 170b. Each branch has also a valve box, such as 174a, in which is a relatively heavily loaded valve opening to permit flow to the valve, such as 66a, and a lightly loaded valve to permit flow in the opposite direction.