GB1128575A - Improvements relating to radial piston fluid motors - Google Patents

Abstract

1,128,575. Fluid pressure reciprocating motors. H.D. PASCHKE. July 25, 1967 [July 29, 1966], No.34639/67. Headings F1A and F1S. A hydraulic or compressed gas operated motor comprises radial cylinders 7 with part-spherical pistons 18 engaging a part-spherical eccentric 5 on a drive shaft 4, operating fluid entering cylinder 7 through an inlet valve 22 biased to its closed position by the pressure in the inlet passage 14 and biased to its open position by the pressure in the cylinder 7, the operating fluid being exhausted through piston 18 and an outlet port 30 or 31 in the eccentric 5, and the arrangement being such that the outlet port moves out of communication with the cylinder before the piston reaches its T.D.C. position, so that the increase in cylinder pressure opens the inlet valve. In the embodiment shown, the inlet valve is opened by the cylinder pressure acting on a plate 24 of larger surface area than valve plate 23 and acting on valve plate 23 through a lifter 25 having an inlet port 26. The relative areas of plates 23 and 24 determine the time during which the inlet valve is open in relation to the rate of rotation of the drive shaft. To prevent all of the inlet valves of the motor from closing at the same motor speed, the valves have different surface area ratios. At least one valve has it surface areas such that at high speed the valve does not close until the outlet port opens. The inlet valve is also biased by springs 27 and 36. In the embodiment of Fig. 3 (not shown), plate 24 and lifter 25 are omitted, and valve plate 23 is biased open by a spring (38), the spring rate being different for the various inlet valves to prevent them from all closing at the same motor speed. In Fig. 1, the cylinder head 10 has a groove 32 vented to the motor casing to prevent build up of pressure between plate 24 and the cylinder head when the inlet valve is open. For starting, springs 36 hold all of the inlet valves open so that the cylinders are all filled with pressure fluid, an adjustable restrictor acting to throttle the exhaust passage 29 until pressure builds up in the cylinders to hold the inlet valves open. The restrictor is then opened to release the pressure in the cylinders registering with outlet port 30 or 31, and the pressure in the other cylinders acts to start the motor. The direction of rotation is reversed by moving shaft 4 axially to bring outlet port 31 into register with the pistons instead of port 30. The leading edges of ports 30 and 31 are inclined to the axis of rotation, so that the timing of the opening of the outlet port is adjustable by axial movement of the drive shaft.