Actuator valve

DETAILED DESCRIPTION The present invention pertains to an actuator valve for a reciprocating air driven device.
In a first aspect of the present invention, additional energy is provided to the valve piston during shifting to insure proper actuation of the valve piston.
In a second aspect of the present invention, leakage of compressed air under stall conditions is eliminated.
Thus, an improved actuator valve is available for air driven reciprocating devices.
In providing additional shifting energy to the valve piston, axially spaced inlet ports selectively bias the valve piston toward completion of its stroke.
The inlet ports may be arranged, in a further aspect of the present invention, so that one of the inlet ports is symmetrically positioned over a transverse passage on the valve piston at each end of the valve piston stroke.
In an additional feature, the axial spacing of the inlet ports also may be such that a center position in the valve piston stroke is created where incoming compressed air does not pass directly through the transverse passage of the valve piston.
To further enhance the biasing of the valve piston, inlet passages to the ports may be inclined.
These several features may individually or collectively act to enhance the shifting and proper locating of the piston in the cylinder.
As a mechanism for eliminating leakage flow under stall conditions of the device, the vent passages for the valve piston cylinder are so positioned as to be selectively closed off by the valve piston with the valve piston at an end of its stroke.
Naturally, proper location of the valve piston at the ends of its stroke enhances this result.
Thus, no matter where the control rod is stalled, the valve piston vent passage which may be vented to atmosphere will be closed to the incoming compressed air.
Accordingly, it is an object of the present invention to provide an improved actuator valve for an air driven reciprocating device.
Other and further objects and advantages will appear hereinafter.