A hydraulic circuit includes a prime mover that is configured to generate an oscillating flow of hydraulic fluid, and an actuator that is driven by the prime mover and configured to provide oscillating motion and to be connected to a load in each direction of the motion. The hydraulic circuit also includes a reclamation device that is disposed in the hydraulic circuit between the prime mover and the actuator. The reclamation device captures and stores a portion of hydraulic fluid displaced from the actuator during a transition between opposed motions, where the portion of hydraulic fluid corresponds to an amount of hydraulic fluid equal to a volume of fluid required to compensate for compression of fluid within the hydraulic circuit due to system pressure and load pressure. The stored fluid is used by the circuit in a subsequent motion.

A vehicle includes: a prime mover; a hydraulic fluid manifold; a hydraulic machine; a hydraulic accumulator; one or more hydraulic actuators; a valve arrangement; and a controller. The controller is configured to receive an actuator demand signal indicative of a demand to move the one or more hydraulic actuators; and to control the hydraulic machine and the valve arrangement to cause movement of the one or more actuators in accordance with the actuator demand signal by bringing the hydraulic accumulator into fluid communication with a first actuator chamber of the one or more hydraulic actuators, and to synchronise therewith changing a pressure in a second actuator chamber of the one or more hydraulic actuators. The second actuator chamber is in fluid communication with the hydraulic machine.

A vehicle includes: a prime mover; a hydraulic fluid manifold; a hydraulic machine; a hydraulic accumulator; one or more hydraulic actuators; a valve arrangement; and a controller. The controller is configured to receive an actuator demand signal indicative of a demand to move the one or more hydraulic actuators; and to control the hydraulic machine and the valve arrangement to cause movement of the one or more actuators in accordance with the actuator demand signal by bringing the hydraulic accumulator into fluid communication with a first actuator chamber of the one or more hydraulic actuators, and to synchronise therewith changing a pressure in a second actuator chamber of the one or more hydraulic actuators. The second actuator chamber is in fluid communication with the hydraulic machine.

A system for charging and discharging at least one hydraulic accumulator (10) can be connected to a valve control device (12). The valve control device (12) has at least one logic valve (14). A shuttle valve (16) and a hydraulically operated switching valve (18) are also provided. The valves (14, 16, 18) are interconnected such that the hydraulically actuatable switching valve (18) compares the accumulator pressure (p.sub.A) to a minimum accumulator pressure (p.sub.A0) that can be adjusted via the control pressure setting of this switching valve (18).

A system for charging and discharging at least one hydraulic accumulator (10) can be connected to a valve control device (12). The valve control device (12) has at least one logic valve (14). A shuttle valve (16) and a hydraulically operated switching valve (18) are also provided. The valves (14, 16, 18) are interconnected such that the hydraulically actuatable switching valve (18) compares the accumulator pressure (p.sub.A) to a minimum accumulator pressure (p.sub.A0) that can be adjusted via the control pressure setting of this switching valve (18).

An active accumulator system which automatically adjusts or adapts the charge pressure or volume of an accumulator to maintain an optimal charge pressure or volume of the accumulator may provide optimal operation of a pump. An active accumulator system may comprise a flow line coupled to a pump, wherein a fluid flows through the flow line to the pump, an accumulator coupled to the flow line, a transducer coupled to the pump, wherein the transducer detects a parameter of the pump at an inlet of the pump, and a controller coupled to the transducer and the accumulator, wherein the controller receives the parameter, and wherein the controller regulates air flow to the accumulator such that the accumulator is adjusted to an optimal charge pressure based at least in part on the parameter.

An active accumulator system which automatically adjusts or adapts the charge pressure or volume of an accumulator to maintain an optimal charge pressure or volume of the accumulator may provide optimal operation of a pump. An active accumulator system may comprise a flow line coupled to a pump, wherein a fluid flows through the flow line to the pump, an accumulator coupled to the flow line, a transducer coupled to the pump, wherein the transducer detects a parameter of the pump at an inlet of the pump, and a controller coupled to the transducer and the accumulator, wherein the controller receives the parameter, and wherein the controller regulates air flow to the accumulator such that the accumulator is adjusted to an optimal charge pressure based at least in part on the parameter.

An example valve assembly includes a housing having an accumulator fluid passage configured to be fluidly coupled to an accumulator, a supply fluid cavity configured to be fluidly coupled to a source of fluid, a reservoir fluid cavity configured to be fluidly coupled to a reservoir of fluid, a head fluid cavity configured to be fluidly coupled to a head-side chamber of a hydraulic actuator, and a rod fluid cavity configured to be fluidly coupled to a rod-side chamber of the hydraulic actuator; a main spool that is axially-movable within the housing; and a balancing spool that is axially-movable within the housing based on an axial position of the main spool.

An example valve assembly includes a housing having an accumulator fluid passage configured to be fluidly coupled to an accumulator, a supply fluid cavity configured to be fluidly coupled to a source of fluid, a reservoir fluid cavity configured to be fluidly coupled to a reservoir of fluid, a head fluid cavity configured to be fluidly coupled to a head-side chamber of a hydraulic actuator, and a rod fluid cavity configured to be fluidly coupled to a rod-side chamber of the hydraulic actuator; a main spool that is axially-movable within the housing; and a balancing spool that is axially-movable within the housing based on an axial position of the main spool.

The invention relates to a hydraulic system for a work machine. The system comprising: a main hydraulic machine connected to an output shaft of an engine of the work machine for providing power to working hydraulics of the work machine; a main pressure line connecting the main hydraulic machine to the working hydraulics; a support hydraulic machine connected to the output shaft; a hydraulic accumulator; a discharge valve connected between the accumulator and an input side of the support hydraulic machine; a charge valve connected between an output side of the support hydraulic machine and the hydraulic accumulator to selectively allow a flow from the support hydraulic machine to the hydraulic accumulator; a flow support valve connected between the output side of the support hydraulic machine and the main pressure line to selectively allow a flow from the support hydraulic machine to the main pressure line; and a hydraulic tank connected to the input side of the support hydraulic machine.