Reciprocating pneumatic motor servo system - has orifice in valve plate moved across it by differential pressure

摘要

The motor piston (3) is moved by fluid pressure in a cylinder (1) against a spring (12). Entering fluid raises a valve plate (8). As the plate rises it closes the discharge valve (11) and the fluid enters the working space (4) through a throttling orifice (10) in the valve plate. At the end of the stroke pressure builds up in the working space and as it acts on a greater area of the valve plate than the inlet pressure it closes the plate again. This opens the discharge valve (11) and the valve plate stays closed until flow through the orifice (10) has sufficiently reduced the pressure in the working space.