| 摘要 |
<p>A hydraulic valve includes a valve body which is provided with a fluid inlet chamber, a pair of user chambers arranged for communication with users of the fluid admitted into the valve body and a pair of return chambers for recovering fluid from the users and recycling the fluid to a source of the same. The valve body further includes a longitudinal passage which connects the various chambers. A spool is slidably mounted in the longitudinal passage and, depending upon the position thereof, permits a user chamber to communicate with the fluid inlet chamber while the corresponding return chamber is sealed from the user chamber or permits the user chamber to communicate with the corresponding return chamber while the user chamber is sealed from the fluid inlet chamber. A flow channel extends across the width of the valve body and opens to either side of the latter. The flow channel is arranged for communication with the source of the fluid and with the fluid inlet chamber. The flow channel is positioned between the spool and the connections provided in the valve body for connecting the user chambers to the users and is symmetrically arranged with respect to the user chambers. A valve element is provided for selectively sealing the flow channel from the fluid inlet chamber and for selectively providing communication between the flow channel and the fluid inlet chamber. The valve element includes a slidable sealing member which has a closed position in which the flow channel is sealed from the fluid inlet chamber and an open position in which the flow channel is in communication with the fluid inlet chamber. The sealing member is arranged in the flow channel and is provided with a bore which forms part of the flow channel. The sealing member has a face which is exposed to the flow channel so as to be subjected to the pressure acting in the latter. A biasing member biases the sealing member towards its closed position.</p> |
