GB1289901A - - Google Patents

Abstract

1289901 Fluid operated linear and oscillating vane actuators IBM UNITED KINGDOM Ltd 3 March 1970 10021/70 Headings F1P and F1F A hydraulic or pneumatically operated actuator capable of assuming a plurality of predetermined selected positions comprises (1) a member e.g. a linear piston 10, Fig. 1 or a rotary vane 80, Fig. 4 which sealingly divides a rotable cylindrical sleeve 13, 82 into two portions 11 and which is displaced in response to a fluid-pressure difference in said cylinder portions, (2) working fluid control means 20 for supplying through lines 22, 23 both cylinder portions 11 simultaneously and (3) means for venting one port or a group of ports of a plurality of ports 16α-16e, Fig. 1α, 85a, b, c-n, Fig. 4 spaced apart along the sleeve wall 13 in accordance with the desired selected positions of the member 10, 80 whereby the resulting pressure drop in the vented portion of the cylinder results (a) in movement of the member 10, 80 towards the member 10, 80 towards the vented port or vented group of ports until the vented port or ports become sealed by the member 10, 80 and (b) in the flow rate through the control means 20 to the vented cylinder portion automatically being reduced to below that to the non-vented chamber. The venting means of the linear actuator comprises an outer fixed cylindrical casing 14 having a vented port 19 leading from a longitudinal channel 18 along its inner wall which channel is in register with one of ports 16α-e according to the angular position of sleeve 13, which is adjusted by a pawl and rachet means 17, Fig. 1b (not shown). The venting means of the rotary actuator comprises a helical channel 84 in a ported cylindrical casing (not shown). The fluid control means 20 comprises restrictions 63, 65, Fig. 3 between a supply line 21 and lines 22, 23 and by-pass valves 66, 67 in parallel with restrictions 63, 65 and normally held closed by pressure downstream of restrictors 65, 63 respectively but in operation the value in the line leading to the non-vented chamber is opened in response to the pressure drop in the vented chamber.