In a cylinder drive device, a throttle valve and a second check valve are provided between a switch valve and a first cylinder chamber of a fluid pressure cylinder. The cylinder drive device has a flow channel unit which is interposed between a manifold and the switch valve, which allows communication between the throttle valve and the second check valve and switch valve, and which communicates with a plurality of holes in the manifold to allow a fluid to flow to the switch valve.

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 fluid circuit includes a pressure fluid source configured to supply pressure fluid, multiple actuators connected to the pressure fluid source, a direction switching valve configured to switch a supply destination of the pressure fluid supplied from the pressure fluid source, and a discharge amount control mechanism configured to control the output pressure of the pressure fluid source such that a pressure difference ΔP between the output pressure of the pressure fluid source and the maximum load pressure of the load pressures of the multiple actuators reaches a target value ΔPt. The fluid circuit further includes an accumulator configured to accumulate part of return fluid from the actuators.

A hydrostatic drive includes at least one hydrostatic pump configured to supply at least one hydrostatic consumer and an apparatus for an energy recovery procedure of at least a part of the energy that is output by the consumer. An electronic control unit or at least one software component is further included, with which the energy recovery procedure is controlled in a variable manner and depends upon detected influencing variables.

A hydraulic system includes: a cylinder that moves a moving object in a vertical direction by extension and retraction of a rod; a first bidirectional pump connected to a head-side chamber of the cylinder by a first supply/discharge line; a second bidirectional pump connected to a rod-side chamber of the cylinder by a second supply/discharge line and coupled to the first bidirectional pump in a manner enabling torque to be transmitted between the first and second bidirectional pumps; a relay line connecting the first and second bidirectional pumps such that a hydraulic liquid discharged from one of the first and second bidirectional pumps is introduced into the other of the first and second bidirectional pumps; and a servomotor that drives the first or second bidirectional pump. At least one of the first and second bidirectional pumps is a variable displacement pump whose delivery capacity per rotation is freely variable.

A hydraulic excavator is provided which can suppress the fuel consumption amount and improve the work efficiency by reducing the hydraulic pressure loss generated when a plurality of hydraulic actuators different in load are operated simultaneously. The hydraulic excavator includes a center bypass flow control valve that is arranged at the most downstream of a center bypass line and limits the flow rate of hydraulic fluid passing through the center bypass line in response to the operation amount of the second operation device in a case where a second operation device is operated, and a spool stroke limitation device that, in a case where a first operation device and the second operation device are operated simultaneously, limits the spool stroke amount of a second directional control valve in response to the operation amount of the first operation device in a state in which the spool stroke amount of a third directional control valve is controlled in response to the operation amount of the second operation device.

An embodiment of the present invention provides a regeneration system of energy released from a working implement, which includes an actuator configured to move up and down the working implement, an accumulator configured to communicate with the actuator, and a controller configured to receive a pressure value of the actuator and a pressure value of the accumulator to control a discharge operation of the accumulator based on a pressure difference value between the actuator and the accumulator.

An open center hydraulic system (100) includes a tank configured to hold hydraulic fluid, a pump configured to provide pressurized hydraulic fluid from the tank, and a shunt valve configured to adapt a first opening area between a first input port and a first output port of the shunt valve dependent on a first control signal. The first input port is coupled to the pump, and the first output port is coupled to the tank. A first actuator valve is coupled to the first input port and configured to adapt a second opening area of the first actuator valve dependent on a second control signal. A hydraulic valve control unit is configured to determine a first opening area value and a second opening area value based on user input data and a predetermined relation dependent on the user input data, sending the first control signal, indicative of the first opening area value and sending the second control signal indicative of the second opening area value.

The self-contained energy efficient hydraulic actuator system of the present invention includes a hydraulic cylinder, a servo motor that is configured to produce rated torque from zero RPM to maximum rated RPM with rotor speed/position feedback to a servo motor, a pump, and a solenoid valve that enables the hydraulic cylinder to maintain its position without the motor running. The system has the ability to hold a load in place without motor operation via the use of the solenoid valve, and therefore saves energy and extends the motor lifetime by minimizing the motor running time.

A hydraulic system includes a hydraulic pump, a first hydraulic actuator, a second hydraulic actuator, a first control valve to control the first hydraulic actuator, a second control valve to control the second hydraulic actuator, the second control valve being arranged on a downstream side of the first control valve, and a discharge fluid tube in which the operation fluid flows. The hydraulic system further includes a first fluid tube in which a return fluid flows toward the second control valve. The hydraulic system further includes a second fluid tube in which a supply fluid flows toward the first hydraulic actuator, a third fluid tube coupling the first fluid tube to the discharge fluid tube, and a fourth fluid tube in which the return fluid flows toward the second fluid tube, the fourth fluid tube being connected to the first fluid tube.