Valve control system for air powered vacuum pump

In combination with a fluid motor having a piston displaceable through a power stroke and a return stroke under the force exerted by pressurization of a pressure chamber, a control valve assembly comprising a valve body, a valve element displaceable between operative positions respectively pressurizing and depressurizing said pressure chamber, flow restrictor means for conducting a restricted flow of fluid into the pressure chamber when the valve element is in one of the operative positions thereof, a source of fluid under pressure from which said fluid is conducted to the pressure chamber through said flow restrictor means, actuating means engageable by the piston for displacing the valve element to said one of the operative positions, means continuously biasing the valve element to the other of the operative positions, and means responsive to said restricted flow of fluid to the pressure chamber for holding the valve element in said one of the operative positions against said continuous bias during the return stroke of the piston, said flow responsive means including pressure responsive valve operator means connected to the valve element, venturi passage means through which said restricted flow into the pressure chamber is conducted for producing a reduced pressure, and means for applying said reduced pressure in the venturi passage means to the pressure responsive valve operator means.

In combination with a source of fluid under intensity regulated pressure and a power output member reciprocated through a fixed power stroke by a constant force, a fluid motor device for displacing the power output member through a return stroke from one end of said power stroke, comprising a housing enclosing a motor pressure chamber, a motor piston connected to the power output member within said chamber, a control valve assembly for establishing fluid communication between said source and the motor pressure chamber to effect displacement of the motor piston through the return stroke, including a valve body, a valve element movably mounted in the valve body and displaceable between operative positions, respectively conducting pressurized fluid from said source to the motor pressure chamber and depressurizing the chamber, means for continuously biasing the valve element to one of said operative positions, actuating means engageable by the motor piston at said one end of the power stroke for displacement of the valve element to the other of the operative positions in which pressurized fluid is conducted from the source to the motor pressure chamber, and valve holding means fluidly connected to the pressure source for holding the valve element in said other of the operative positions during the return stroke, comprising a diaphragm connected to the valve element, means within the housing enclosing opposing pressure chambers on opposite sides of the diaphragm, said valve element conducting unrestricted flow of the pressurized fluid from the source to one of the opposing pressure chambers in said other of the operative positions thereof, and pressure reducing means fluidly connected to the other of the opposing chambers for unbalancing equalized pressures in said opposing pressure chambers only during the return stroke, whereby the valve element returns to said one of the operative positions under the continuous bias exerted thereon at the end of the stroke.