The present disclosure relates to a hydraulic valve arrangement comprising a first pilot operated proportional directional control valve having a first valve member that is displaceable in a first and a second axial direction for controlling direction of supply and discharge of hydraulic fluid to and from a hydraulic actuator, a first proportional electro-hydraulic control valve for controlling displacement of the first valve member in the first axial direction, a second proportional electro-hydraulic control valve for controlling displacement of the first valve member in the second axial direction, and a second pilot operated proportional control valve having a second valve member configured to be controlled by the first and second proportional electro-hydraulic control valves via a shuttle valve arrangement. Individual meter-in and meter-out control of the hydraulic actuator is providable by having the second pilot operated proportional control valve configured to operate as a meter-in valve of the hydraulic actuator and the first pilot operated proportional directional control valve configured to operate as a meter-out valve of the hydraulic actuator, or by having the first pilot operated proportional directional control valve configured to operate as a meter-in valve of the hydraulic actuator and the second pilot operated proportional control valve configured to operate as a meter-out valve of the hydraulic actuator. The present disclosure also relates to a vehicle comprising a hydraulic actuator and a hydraulic valve arrangement for controlling the motion of the hydraulic actuator.

The present invention allows the number of components to be reduced and assembly work to be easily performed. A cylinder drive manifold device that constitutes a cylinder drive apparatus is provided with a block-shaped manifold in which a plurality of holes are formed for circulating a fluid used for driving a plurality of fluid pressure cylinders. The manifold is configured such that a plurality of switching valves for supplying a fluid alternately to a first cylinder chamber and a second cylinder chamber of each of the fluid pressure cylinders are attachable. A plurality of check valves and a plurality of throttle valves are incorporated into the plurality of holes of the manifold.

A prime mover and hydraulic actuators, a hydraulic machine having a rotatable shaft engaged with the prime mover and having a plurality of working chambers, a hydraulic circuit extending between a group of working chambers of the hydraulic machine and the hydraulic actuators, each working chamber of the hydraulic machine having a low-pressure and a high-pressure valve regulating the flow of hydraulic fluid between the working chamber and a corresponding low-pressure manifold and a high-pressure manifold. The hydraulic machine controlling the low-pressure valves of the group of working chambers to select the net displacement of hydraulic fluid by each working chamber on each cycle of working chamber volume, and thereby the net displacement of hydraulic fluid by the group of working chambers, responsive to a demand signal, the apparatus further having a controller calculating the demand signal responsive to a measured property of the hydraulic circuit or an actuator.

An example valve includes: a seat member; a spool configured to be seated on the seat member to block fluid flow from a first port to a second port when the valve is in a closed state, wherein fluid at the first port applies a fluid force on the spool; a spring applying a biasing force on the spool toward the seat member, wherein as the fluid force overcomes the biasing force, the spool moves in the proximal direction off the seat member, thereby allowing fluid flow from the first port to the second port through a flow area formed between the spool and the seat member; a turbine configured to rotate as fluid flowing through the flow area flows downstream across the turbine; and an electric generator coupled to the turbine, such that rotation of the turbine causes the electric generator to generate electric power.

An example valve includes: a pressure compensation spool configured to be subjected to a first fluid force of fluid received at a first port acting in a proximal direction; a pressure compensation spring disposed in a pressure compensation chamber and applying a biasing force on the pressure compensation spool in a distal direction; a turbine configured to rotate as fluid flows through the valve; and a flow area configured to throttle fluid flow from the first port to the pressure compensation chamber, wherein fluid in the pressure compensation chamber applies a second fluid force on the pressure compensation spool in the distal direction, such that the pressure compensation spool moves to a particular axial position based on force equilibrium between the first fluid force, the second fluid force, and the biasing force to throttle fluid flow from the pressure compensation chamber to a second port.

There is provided a construction machine that is capable of measuring a minute leakage flow rate of a one-sided tilting variable displacement hydraulic pump. The construction machine includes a pressure sensor that detects a pressure of a hydraulic pump, a bleed-off adjusting device that is enabled to adjust a bleed-off flow rate of the hydraulic pump, and an input device that gives an instruction for measurement of a leakage flow rate of the hydraulic pump. The controller is configured to measure, when the controller determines that the operation device is in a non-operated state and when a measuring command is inputted from the input device, a pressure of the hydraulic pump while changing a control command value for the bleed-off adjusting device in a state in which a flow rate of the hydraulic pump is maintained, and calculate the leakage flow rate of the hydraulic pump on the basis of the control command value for the bleed-off adjusting device at the time that the pressure of the hydraulic pump is stabilized at a predetermined pressure.

A hydraulic system includes a first system discharge fluid tube that discharges fluid flowing through a first supply fluid tube, a second system discharge fluid tube that discharges fluid, a first control valve, and a second control valve connected to a second supply fluid tube, the first system discharge fluid tube, and the second system discharge fluid tube, configured to be switched between: a supply position that supplies fluid from the second supply fluid tube to the first supply fluid tube; a first stop position that stops supply of fluid from the second to the first supply fluid tube and supplies fluid from the first supply fluid tube to the first system discharge fluid tube; and a second stop position that stops supply of fluid from the second to the first supply fluid tube and supplies fluid from the first supply fluid tube to the second system discharge fluid tube.

The present disclosure relates to a hydraulic valve arrangement comprising a first pilot operated proportional directional control valve having a first valve member that is displaceable in a first and a second axial direction for controlling direction of supply and discharge of hydraulic fluid to and from a hydraulic actuator, a first proportional electro-hydraulic control valve for controlling displacement of the first valve member in the first axial direction, a second proportional electro-hydraulic control valve for controlling displacement of the first valve member in the second axial direction, and a second pilot operated proportional control valve having a second valve member configured to be controlled by the first and second proportional electro-hydraulic control valves via a shuttle valve arrangement. Individual meter-in and meter-out control of the hydraulic actuator is providable by having the second pilot operated proportional control valve configured to operate as a meter-in valve of the hydraulic actuator and the first pilot operated proportional directional control valve configured to operate as a meter-out valve of the hydraulic actuator, or by having the first pilot operated proportional directional control valve configured to operate as a meter-in valve of the hydraulic actuator and the second pilot operated proportional control valve configured to operate as a meter-out valve of the hydraulic actuator. The present disclosure also relates to a vehicle comprising a hydraulic actuator and a hydraulic valve arrangement for controlling the motion of the hydraulic actuator.

A shovel includes a hydraulic pump, multiple hydraulic actuators, a center bypass oil passage supplied with hydraulic oil discharged from the hydraulic pump, multiple directional control valves, and a bleed-off valve. The directional control valves are arranged in tandem in the center bypass oil passage and configured to supply the hydraulic actuators with the hydraulic oil from the center bypass oil passage. At least a directional control valve other than the most downstream directional control valve in the center bypass oil passage among the directional control valves opens the center bypass oil passage. The bleed-off valve is connected to part of the center bypass oil passage upstream of at least one of the directional control valves.

A hydraulic system of a construction machine includes: a pump that supplies hydraulic oil to a hydraulic actuator; a control valve on a center bypass line extending from the pump to a tank, the control valve including a bypass passage; an unloading valve on the center bypass line downstream of the control valve; and a controller that controls the unloading valve. The control valve is configured such that an opening area of the bypass passage is greater than an opening area of the unloading valve while an operation signal outputted from an operation device increases from a predetermined value to a first setting value, and such that the opening area of the bypass passage is less than or equal to ¼ of a maximum opening area of the bypass passage when the operation signal is greater than or equal to a second setting value greater than the first setting value.