GB1141261A - Improvements in radial piston pumps or motors - Google Patents

Abstract

1,141,261. Hydraulic reciprocating motors and pumps. OLEODINAMICA RUHRITAL S. p. A. Feb. 3, 1966 [Feb. 5, 1965], No.4758/66. Heading F1A. A multi-cylinder pump or motor comprises cylinders 16 disposed in a stator 43 with their axes arranged tangentially to a circle centred on drive shaft axis 11 and of a radius less than, e.g. half, the eccentricity of eccentric 10, which is engaged by piston slippers 19 with recesses 22 connected to the corresponding cylinders. The cylinders are secured in the stator by threaded members 47 carrying inlet valves 50. Discharge takes place through valves 54. In the pump embodiment shown, selected cylinders may be de-activated by by-passing their delivery to the stator interior, when predetermined delivery pressures are exceeded. By-passing of the cylinders is effected by respective valves 64 each biased by a spring 68, 69 of a predetermined load associated with the predetermined delivery pressures and actuated by the delivery pressure in outlet 62 acting on a piston 67. Valve 64 incorporates a damping device 65. A pressure relief valve, Fig. 2 (not shown), connects the stator interior to a tank in which the pump is mounted. The inclination of the cylinders to the shaft axis is such that the angle between the pistons and their slippers is less driving their working strokes than driving their return strokes, to reduce side thrusts on the cylinders. The piston 17 may be of a material of high coefficient of thermal expansion, e. g. aluminium with anodically oxidized surfaces, so that as the working fluid viscosity decreases with increasing temperature, the piston expands so as to be a closer fit in its cylinder. Sealing between components may be effected by rings 53, 59, with sharp edges which cut into the surfaces they engage.