Patent GB-1078115-A (GB)
Title: Improvements in or relating to control systems for hydraulic pumps and motors
Inventor: GREEN JACK RAYMOND
IPC: F01B3/10
Filed: 1963-05-06
Abstract: 1,078,115. Fluid-pressure servomotor systems. VICKERS Ltd. May 6, 1964 [May 6, 1963], No. 17890/63. Heading G3P. [Also in Divisions F1 and ,F2]' In a radial cylinder pump or motor the valve means controlling the flow of liquid into and out of the cylinders 1A, 1B, 1C is arranged to cutoff each cylinder both from the inlet and outlet for a period or periods in each cycle and the stroke of the pistons is varied by variation in the eccentricity of the crank-pin 5. The crank-pin 5 is slidable in a guide 4 in the face of a rotary member 3 and connected to the symmetrically spaced pistons 7A, 7B, 7C. The cylinders 1A, 1B, 1C have respective inlet and outlet valves 10A, B, C and 11A, B, C operated by cams 41 and 42 mounted on the member 3 and extending over an arc of 120. With valves 10 and 11 closed the piston 7 will be substantially fixed in position and the crank-pin 5 is constrained to move in an arc determined by the connecting rod 6. Over a cycle the locus of the crank-pin 5 will approximate to a hexagon, (G, H, J, K, L, M), Fig. 2 (not shown). Further valves 50A and 49A may be associated with each of the cylinders 1A, 1B, 1C and actuated by cams 45 and 46, respectively, each extending over an arc of 60. The valves 50A and 49A place the cylinders in communication with a source of liquid under pressure or exhaust under the control of a spool valve 53. Operation of the spool valve provides means for varying the eccentricity of the crank-pin (GH', GH") Fig. 2. In an alternative control arrangement, Fig. 1B (not shown), a plate (3A) containing the guide (4) and rigidly fixed to a rotary shaft (55) mounts a block (3B) having valve actuating cams (40, 41). The block (3B) is rotatable but axially fixed relative to the shaft (55). A sleeve (55) provided with a projection (56C) which engages a helical slot (3C) in the block (3B), is mounted on the shaft (55) for axial movement relative thereto. Axial movement of the sleeve (56) produces corresponding rotational movement of the block (3B) to increase or decrease the duration of the cut-off period and thereby increase or decrease the eccentricity of the crank-pin. The spool valve 53 or the sleeve (56) may be controlled by a device, Fig. 1A (not shown) sensitive to the eccentricity of the crank-pin. The device comprises a piston and cylinder, to which a control pressure is applied, e.g. the output pressure of the pump, connected to the spool valve or sleeve and operating the spool valve or sleeve to increase or decrease the crank-pin eccentricity until the required conditions are restored. In further control arrangements, Figs. 3, 3A, 3B (not shown), the guide (4') is mounted for movement relative to the rotary member (3) at right angles to the axis of the guide by a piston and cylinder assembly (12), compression springs (80) or a centrifugal governor (87), respectively. In another control arrangement, Fig. 3A (not shown), piston and cylinder assemblies on opposite sides of the guide (4') are connected to source of high pressure fluid or exhaust under the control of a spool valve (71). The supply of high pressure fluid may be controlled by a regulator (71) which may in turn be controlled by the device of Fig. 1A. In a still further control arrangement, Fig. 4 (not shown), the guide (4") is mounted for movement perpendicular to its axis and rotationally relative to the member (3) by piston and cylinder assemblies (12' and 14). The pressures in the cylinders may be controlled to produce any desired operating characteristics of the pump or motor. In a pump or motor having an even number of cylinders, diametrically opposed cylinders are cut-off simultaneously. Further combinations of the above described control arrangement are disclosed in the Specification.