| 摘要 |
<p>A hydraulic system (40) for an excavator (10) which utilizes regeneration, minimizes cavitation, and provides hose break protection is disclosed. A valve assembly (50) is permanently connected to a hydraulic actuator (30) which is to be controlled. A hydraulic power supply (42) remote from the hydraulic actuator is connected to the valve assembly (50) through a pair of flexible hoses (56, 58). Pressurized hydraulic fluid can flow to the valve assembly through either of the flexible hydraulic hoses, but the valve assembly (50) includes a check valve (60) so hydraulic fluid return is only possible through one hose (56). A two position valve (62) is provided in the valve assembly (50) between a pair of operating ports (36, 38) on the hydraulic actuator (30). The two position valve (62) can be opened in response to a signal from the operator, connecting the two ports (36, 38) together to permit regeneration. The valve assembly (50) also includes a pressure relief valve (64) connected to one of the ports (38) to limit overpressure. A second check valve (66) is connected around the pressure relief valve (64) to permit hydraulic fluid to flow from a reservoir (43) to the hydraulic actuator (30). The reservoir (43) is pressurized at a relatively low pressure, so when the pressure at the associated port (38) drops below the reservoir pressure hydraulic fluid flows through the second check valve (66) to the port (38) and minimizes cavitation.</p> |
