Self-latching solenoid valve assembly and control circuit

摘要

A self-latching solenoid valve assembly (10) including a valve body (12) having a pressurized air supply inlet port (16) for communicating with a source of pressurized air and at least one cylinder port (18,20). A valve member (22) is supported in the valve body (12) so as to be movable between predetermined positions to selectively direct pressurized air from the inlet port (16) to at least one cylinder port (18,20). A biasing member (46) is employed to move the valve member (22) in one direction and a solenoid assembly (14) is used to move the valve member (22) in an opposite direction. The solenoid assembly (14) includes a housing (48) with a solenoid coil (56) supported therein and a fixed ferromagnetic pole piece (74) having a passage (82) extending therethrough with a pushpin (84) movably supported in the passage (82). A ferromagnetic latch (88) is also supported by the housing and spaced from the pole piece. A permanent magnet (90) is disposed between the latch (88) and the pole piece (74). The magnet (90) is movable toward the pole piece (74) under the influence of an electromagnetic flux generated by a pulse of current generated through the coil (56) in one direction thereby driving the permanent magnet (90) against the pushpin (84) to move the valve member (22) to one predetermined position. In addition, the permanent magnet (90) is also movable away from the pole piece (74) and toward the latch (88) under the influence of an electromagnetic flux generated by a pulse of current flowing through the coil (56) in an opposite direction. When this occurs, the biasing member (46) moves the valve member (22) to another predetermined position. A control circuit for changing the direction of the current through the coil is also disclosed.