| 摘要 |
A 2-position, 3-way directional control valve is described which prevents reverse flow from an actuator port to a pressure port in one position. In the preferred embodiment described, the valve is solenoid actuated and is spring biased to a drain position, wherein an extension central to a spool assembly penetrates through a check valve seat and lifts a check valve ball from its seat to permit flow from an actuator port to a drain port. In the actuated or energized position, an armature assembly is shifted by a solenoid, drawing the spool assembly within the valve body and establishing a fluid path between a pressure port and the actuator port. In this position the extension of the spool assembly is withdrawn from the check valve seat. The check valve can be unseated by pressure from the pressure port to permit flow from the pressure port, through the spool and the check valve assembly. In the event of loss of pressure from the pressure port, such as due to shifting of other valves coupled to a pressure source, the check valve reseats to prevent reverse flow from the actuator port to the pressure port. The valve assembly is preferably configured as a cartridge valve for use in pre-drilled manifolds.
|
