Hydraulic device and a hydraulic system for controlling a hydraulic actuator

A hydraulic system for controlling a hydraulic actuator, the hydraulic system comprising:

• an actuator control valve for controlling a flow of hydraulic fluid to the hydraulic actuator, the actuator control valve comprising a service port, and a first actuator port for fluid communication with a first chamber of the hydraulic actuator;
• a service network comprising one or more fluid flow channels in fluid communication with a hydraulic pump and with the service port of the actuator control valve;
• a storage network for connecting to an energy storage device;
• and
• a flow channel for connecting the storage network and the service network via the actuator control valve;
• wherein the actuator control valve is configurable to:
• a first actuation configuration in which the first actuator port is in fluid communication with the service port, and fluid flow from the storage network to the service network is blocked, such that the actuator control valve allows, in use, the hydraulic actuator to be controlled using the hydraulic pump;
• and
• a second actuation configuration in which the first actuator port is in fluid communication with the service port, and fluid flow from the storage network to the service network is permitted, and wherein the actuator control valve is configured to provide, in use, proportional control of the hydraulic actuator using hydraulic pressure provided by the energy storage device.

A hydraulic device comprising:

• a piston arrangement comprising a plurality of pistons, wherein each of the pistons is arranged to reciprocate within a cylinder in a cycle comprising an in-stroke wherein a fluid flows into the cylinder and an out-stroke wherein the fluid flows out of the cylinder, wherein reciprocation of the pistons is collectively driven by, or drives, a rotatable piston drive element;
• a piston switching valve arrangement comprising a plurality of piston switching valves, wherein each of the pistons is associated with one of the piston switching valves, wherein each of the piston switching valves is configured to control fluid flow into and out of the cylinder of the piston associated with the piston switching valve;
• and
• a controller configured to electronically control the piston switching valves;
• wherein each of the piston switching valves is configurable between:
• a first configuration in which the cylinder of the piston associated with the piston switching valve is in fluid communication with a first port, and a second configuration in which the cylinder of the piston associated with the piston switching valve is in fluid communication with a second port;
• wherein the controller is configured to control the piston switching valves such that in use each of the pistons can selectively perform:
• (i) pumping and/or motoring, in which the fluid is transferred from one of the first or second ports to another of the first or second ports during the cycle, and (ii) idling, in which the fluid is not transferred between the first or second ports during the cycle;
• wherein the controller is configured to receive a demand and control whether each of the pistons performs (i) the pumping and/or motoring, or (ii) the idling, during one or more of the cycles in response to the demand;
• wherein the plurality of pistons are provided in a radial arrangement, wherein the piston arrangement is internally impinged;
• and
• wherein two or more of the pistons are associated with each of the piston switching valves.