US 3,943,823 AGranted

Control system for double acting air motor

AssigneeNordson Corporation

InventorSimon Z. Tammy

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Abstract

A system for controlling a reciprocable double acting air motor including a pair of power valves for reversing the inlet and exhaust air to and from opposite sides of the piston in the air motor. The control apparatus includes a pair of snap opening pilot valves which are unseated in response to momentary mechanical engagement with the piston of the air motor and which are then pneumatically shifted open so that the energy to effect the pilot valve shift is derived from the air supply line and not from the air motor piston. The return of the pilot valves to the closed position is in response to pressure reversal in the air motor. The power valves each include a pair of chokes, one of which is continuously operable and is of moderate flow restriction and the other of which is intermittently operable and is of high flow restriction. These chokes cooperate to (1) cause completion or reversal of a shift cycle in the event of a loss of the pilot signal during the shift cycle and to (2) stabilize the valve and prevent bounce back from a seated condition. The control apparatus also includes a poppet type pressure regulating valve with self-aligning poppet seals.

Claims4

Dependent claims

Apparatus for controlling the transmission of fluid pressure to a double-acting fluid motor cylinder for driving a reciprocating piston therein, comprising directional control valve means, fluid pressure supply means, first and second pilot operating valves for transmitting fluid pressure from said pressure supply means alternately to opposite ends of said directional control valve means, said directional control valve means being operable to alternately supply fluid pressure to one end of said motor cylinder while exhausting fluid from the opposite end of said motor cylinder, said directional control valve means comprising

a valve body having a pair of stepped bores therein, each of said stepped bores being intersected and in fluid communication with an exhaust channel, a pressure supply channel and a motor supply channel,
a valve spool slidably mounted within each of said stepped bores, said spools each having two poppet sealing elements thereon operable with respect to said motor supply channel to alternatively connect said motor supply channel to said exhaust channel and supply channel,
means including a pair of chokes operable to assist in axially positioning each of said spools in said stepped bores,
one of said pair of chokes being a continuously operable choke of moderate restriction between said spool and said stepped bore,
the other of said pair of chokes being an intermittently operable choke of high restriction between said spool and said stepped bore, and
a spring in each of said bores operable to bias said spools axially toward one end position in said stepped bores.

3 more elements

Dependencies are inferred from the claim text.