A hydraulic system includes first and second valve assemblies connected to a common pump. The first valve assembly includes a main valve housed inside a manifold. A pressure compensator valve maintains a constant pressure drop across a variable orifice of the main valve. A pressure limiter valve is in communication with the main valve and the pressure compensator valve, and allows an actuator connected to the first valve assembly to operate independently of the second valve assembly so that fluid flow to a work port of the first valve assembly is not interrupted by operation of the second valve assembly.

An example valve includes a first port fluidly coupled to a source of fluid, a second port fluidly coupled to an actuator, a third port fluidly coupled to a reservoir, and a fourth port configured to export a load-sense (LS) fluid signal. The valve can operate in: a neutral state, wherein fluid is allowed to flow from the second port to the third port, while the first port and the fourth port are blocked; a first actuated state, wherein fluid flow is throttled from the second port to the third port, while the first port and the fourth port remain blocked; or a second actuated state, wherein fluid flow from the second port to the third port is blocked, while fluid flow is allowed from the first port to the second port and from the second port to the fourth port.

To provide a construction machine that has a hydraulic system mounted thereon in which a closed-circuit pump, and an open-circuit pump and a proportional valve are arranged as a pair, and that makes it possible to use an unused open-circuit pump or proportional valve to accelerate the speed of a single rod hydraulic cylinder when the single rod hydraulic cylinder and a hydraulic motor are driven simultaneously. A controller (51) controls a cap-side selector valve (46) and a rod-side selector valve (47) such that a particular open-circuit pump (15) not connected to a single rod hydraulic cylinder (3) is connected to the single rod hydraulic cylinder, and controls an opening area of a particular proportional valve (49) provided on a flow line that connects a delivery port of the particular open-circuit pump to a tank, when the single rod hydraulic cylinder and a hydraulic motor (7) are driven simultaneously.

A manipulator includes an articulated boom configured to be folded out. The articulated boom includes a turntable that can be rotated about a vertical axis, a plurality of boom segments, electrically-actuated proportional valves, and a remote control. The boom segments are pivotable via respective drive assemblies. The electrically-actuated proportional valves are respectively arranged directly on or in proximity to the respective drive assemblies to be controlled. The remote control includes at least one control lever configured to be displaced in a plurality of actuating directions. The manipulator further includes an electronic controller configured to actuate the drive assemblies via a travel command. The travel command indicates a desired movement of the boom tip. The travel command is generated in response to displacement of the control lever into at least one of the plurality of actuating directions. And, the travel command causes actuation of the respective electrically-actuated proportional valves.

The present invention discloses a load-sensing multi-way valve with a variable differential pressure, where each valve group uses a new element: an electro-hydraulic pressure compensation valve, so as to implement continuous real-time adjustment and control of compensated differential pressure and real-time position feedback and monitoring of a compensation valve trim, and overcome a flow mismatch problem of a conventional LS system in a flow saturation working condition and problems of a fixed shunting proportion of an LUDV system and poor operation coordination of actuators. The load-sensing multi-way valve with a variable differential pressure disclosed in the present invention has advantages such as strong working condition applicability, high flow distribution accuracy, and strong technicality.

A hydraulic system for an aircraft. The hydraulic system can include a hydraulic actuator that is operatively coupled to a flight control member. Hydraulic fluid is moved through the hydraulic system by an engine driven pump that delivers hydraulic fluid to the actuator at a first pressure, and a boost pump that delivers hydraulic fluid to the actuator at a second pressure that is higher than the first pressure. The hydraulic system is configured such that the hydraulic fluid returning from the actuator to the engine driven pump can be delivered to the boost pump prior to reaching the engine driven pump.

A hydraulic actuator system includes a load sense assembly that is configured to transmit a load sense signal to a variable pump to vary a flow of pressurized fluid from the variable pump in response to the load sense signal to generate a desired flow to the actuator. The load sense assembly includes a load sense boost valve (LSBV) configured to dynamically boost the load-sense signal according to the desired margin pressure and the flow demand from the system. When flow demands are low, margin pressure will be above the set threshold of the adjustable LSBV, and no boosting occurs. When flow demands are high and pressure in the load sense line drops to the set threshold, or minimum margin pressure, the LSBV begins boosting the load sense signal pressure dynamically. The boosted load sense signal signals the variable pump to stroke and displace more fluid to increase flow to the actuator.

An example valve includes a first port fluidly coupled to a source of fluid, a second port fluidly coupled to an actuator, a third port fluidly coupled to a reservoir, and a fourth port configured to export a load-sense (LS) fluid signal. The valve can operate in: a neutral state, wherein fluid is allowed to flow from the second port to the third port, while the first port and the fourth port are blocked; a first actuated state, wherein fluid flow is throttled from the second port to the third port, while the first port and the fourth port remain blocked; or a second actuated state, wherein fluid flow from the second port to the third port is blocked, while fluid flow is allowed from the first port to the second port and from the second port to the fourth port.

A hydraulic system includes first and second valve assemblies connected to a common pump. The first valve assembly includes a main valve housed inside a manifold. A pressure compensator valve maintains a constant pressure drop across a variable orifice of the main valve. A pressure limiter valve is in communication with the main valve and the pressure compensator valve, and allows an actuator connected to the first valve assembly to operate independently of the second valve assembly so that fluid flow to a work port of the first valve assembly is not interrupted by operation of the second valve assembly.

A hydraulic system includes first and second valve assemblies connected to a common pump. The first valve assembly includes a main valve housed inside a manifold. A pressure compensator valve maintains a constant pressure drop across a variable orifice of the main valve. A pressure limiter valve is in communication with the main valve and the pressure compensator valve, and allows an actuator connected to the first valve assembly to operate independently of the second valve assembly so that fluid flow to a work port of the first valve assembly is not interrupted by operation of the second valve assembly.