| 摘要 |
The 4-way valve used to control the operation of a pneumatic motor can be pneumatically operated such as by a pilot valve. The pilot valve (20) works by creating a restriction at the high-pressure air/signal port (22) regardless of the pressure drop up-stream of the pilot valve (20) while still allowing for adequate flow once the valve (20) is actuated. An additional slide valve (24) is added to the pilot valve (20) that restricts the inlet 30 of the pilot valve (20) above the poppet valve (28) that creates a pressure drop, see FIG. 3. The extra pressure drop forces the valve (20) to snap open once the actuator pin (32) contacts the poppet valve (20) to create the hysteresis. Once the valve (20) snaps open, the slide valve (24) moves to uncover the high-pressure ports (22), removing the 24 restriction to ensure that the main 4-way (10) fully actuates. |
