GB1486822A - Actuator devices - Google Patents

Abstract

1486822 Pneumatic actuators ASSOCIATED ENG Ltd 13 Jan 1975 [17 Jan 1974 4 March 1974] 23062/75 and 23063/75 Divided out of 1486821 Heading F1D An actuator device includes a chamber with a movable wall and connected to atmosphere by a permanently open orifice. A normally closed electromagnetic valve controls the connection of the chamber to a volume of gas at a pressure different from atmosphere. As shown in Fig. 1, a chamber 40 is defined by a steel movable wall 32 and a light alloy body 30 joined by corrugated bellows 31. The wall 32 can be linked to an engine throttle cable by a bracket 35. A cavity 41 has an orifice 43 which admits air into the chamber 40 through a plastics foam filter 42, and contains an electromagnetic valve comprising a solenoid 46 and an armature 50 which is normally biased by a U-shaped spring member 52, Fig. 2 (not shown), so as to close an orifice 45 communicating with the air inlet manifold of an engine at sub-atmospheric pressure. In use, the solenoid 46 receives a succession of variable width electrical pulses from a vehicle speed sensing circuit, Fig. 3 (not shown), causing the electromagnetic valve to be opened and closed, thereby admitting pulses of reduced gas-pressure into the chamber 40. The actuator effectively integrates the pressure pulses and the wall 32 is moved smoothly against the action of a spring 37 so as to control the engine throttle setting. In a modification, the bellows 31 and movable wall 32 may be replaced by a piston sliding within a rigid side wall. The vehicle speed responsive circuit of Fig. 3 is described and claimed' in Parent Specification, see Division G3.