| 摘要 |
<p>The present invention relates to a hydraulic valve that can be used in hydraulic systems that use low-viscosity working fluids such as water-oil emulsions, mainly in the hydraulic systems of mining machines. This hydraulic valve includes a body comprising a pressure chamber and a working chamber as well as a stepped axial opening for receiving a stepped slide valve. The hydraulic valve also includes an actuator for axially displacing the slide valve as well as closure organ with a seal located in a closed annular cavity, wherein said cavity is defined by the walls of the stepped opening, of the slide valve and of a spring-loaded protection insert arranged between the annular protrusions of the slide valve. This valve is characterised in that the annular closed cavity communicates with the pressure chamber. In another embodiment the annular closed cavity may communicate with the pressure chamber through one or more channels. It is thus possible to exclude any risk of junction break at the closed annular cavity until the seal passes under the protection insert, and to prevent said seal from being expelled into the gap thus formed.</p> |
