| 摘要 |
A hydraulically actuated device includes a device body which defines an inlet passage and an outlet passage. The inlet passage is separated from the outlet passage by a first valve seat and a second valve seat. The device body also defines a control passage that opens into an area between the first valve seat and the second valve seat. Trapped between the first valve seat and the second valve seat is a ball valve member. When the ball valve member is in contact with the first valve seat, it acts to close the inlet passage to the control passage. Likewise, when the ball valve member is in contact with the second valve seat, it acts to close the outlet passage to the control passage. Attached to the device body is an electrical actuator. When the electrical actuator is de-energized, a compression spring positioned in the device body biases the ball valve member into contact with the first valve seat. The ball valve member is biased into contact with the second valve seat when the electrical actuator is energized A pumping element including a first end and a second end is positioned within the device body. The first end of the pumping element is exposed to pressure in the control passage while the second end is exposed to pressure in a pumping chamber. An area defined by the second end is smaller than an area defined by the first end.
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