A fluid distribution system includes a boost supply providing a fluid flow, and a fluid metering system downstream of the boost supply. The fluid metering system supplies fluid to a downstream device. A main fluid pump supplies at least a portion of the fluid flow to the fluid metering system. A shut-off valve is positioned upstream of a main fluid pump inlet. An actuation system is positioned downstream of the boost supply. The actuation system supplies fluid to one or more hydraulically-operated devices. An actuation pump supplies at least a portion of the fluid flow to the fluid metering system and to the actuation system. A first valve is positioned between the actuation pump and the fluid metering system. The first valve and the shut-off valve are operable to switch between the main fluid pump and the actuation pump as a source of fluid supply to the fluid metering system.

A fluid distribution system includes a boost supply providing a fluid flow, and a fluid metering system downstream of the boost supply. The fluid metering system supplies fluid to a downstream device. A main fluid pump supplies at least a portion of the fluid flow to the fluid metering system. A shut-off valve is positioned upstream of a main fluid pump inlet. An actuation system is positioned downstream of the boost supply. The actuation system supplies fluid to one or more hydraulically-operated devices. An actuation pump supplies at least a portion of the fluid flow to the fluid metering system and to the actuation system. A first valve is positioned between the actuation pump and the fluid metering system. The first valve and the shut-off valve are operable to switch between the main fluid pump and the actuation pump as a source of fluid supply to the fluid metering system.

Method for controlling and damping the motion of a hydraulic actuator in an electro hydrostatic actuator (EHA) system comprising an electric motor, a hydraulic pump and a hydraulic fluid circuit connecting the hydraulic pump and the hydraulic actuator includes comprising: energising the electric motor to drive the hydraulic pump to supply hydraulic fluid to the hydraulic actuator through the hydraulic fluid circuit in an active mode of operation; providing a flow path between the hydraulic actuator and the hydraulic pump in a damping mode of operation such that hydraulic fluid can flow via the flow path through the hydraulic pump when the hydraulic actuator is driven by an external force; and determining a desired amount of damping to be applied to the hydraulic actuator in the damping mode of operation and providing the electric motor with one or more energy consuming means configured to provide the desired amount of damping.

A hydraulic excavator drive system includes: a first pump connected to a head-side chamber of a boom cylinder; and a second pump that supplies hydraulic oil to one of, or both, an arm cylinder and a bucket cylinder. The first pump is driven by an electric motor. The drive system further includes a switching valve that is in a first position at a boom raising operation and in a second position at a vehicle body lifting operation. The first position is a position in which the switching valve brings a rod-side chamber of the boom cylinder into communication with a tank, and the second position is a position in which the switching valve brings the rod-side chamber into communication with the second pump.

A hydraulic excavator drive system includes: a first pump connected to a head-side chamber of a boom cylinder; and a second pump that supplies hydraulic oil to one of, or both, an arm cylinder and a bucket cylinder. The first pump is driven by an electric motor. The drive system further includes a switching valve that is in a first position at a boom raising operation and in a second position at a vehicle body lifting operation. The first position is a position in which the switching valve brings a rod-side chamber of the boom cylinder into communication with a tank, and the second position is a position in which the switching valve brings the rod-side chamber into communication with the second pump.

A control system of a hybrid construction machine includes fluid pressure pumps, a regeneration motor, a rotating electric motor coupled to the regeneration motor, a storage battery configured to store electric power generated by the rotating electric motor, an assist pump provided coaxially to the regeneration motor to be driven by the rotating electric motor, the assist pump being configured to supply a working fluid to a fluid pressure actuator, and load adjusting units configured to change a load of the assist pump in accordance with a state of the storage battery.

A control system of a hybrid construction machine includes fluid pressure pumps, a regeneration motor, a rotating electric motor coupled to the regeneration motor, a storage battery configured to store electric power generated by the rotating electric motor, an assist pump provided coaxially to the regeneration motor to be driven by the rotating electric motor, the assist pump being configured to supply a working fluid to a fluid pressure actuator, and load adjusting units configured to change a load of the assist pump in accordance with a state of the storage battery.

A hydraulic system includes: hydraulic actuators; a control valve for controlling the hydraulic actuators; a tank for storing a hydraulic operation fluid; a variable displacement pump for supplying the hydraulic operation fluid to the hydraulic actuators; a regulator for controlling the variable displacement pump; a pilot pump for discharging a hydraulic pilot fluid; a load sensing system for maintaining a differential pressure to be a constant pressure, the differential pressure being obtained by subtracting a second signal pressure from a first signal pressure that is the discharge pressure of the variable displacement pump, the second signal pressure being the maximum one of the load pressures generated in the hydraulic actuators; a signal tube for sending the second signal pressure to the regulator; a throttle provided on the signal tube; and a warm-up circuit for supplying the hydraulic pilot fluid to a downstream side of the throttle.

A bi-directional pump connected to a motor by a pair of supply/discharge lines; a regulator changes the bi-directional pump tilting angle; and a controller controls the regulator based on a turning signal outputted from a turning operation valve. At the turning acceleration, at which the signal increases, the controller calculates a motor flow rate passing through the motor and an instruction flow rate determined based on the turning signal. If the instruction flow rate is greater than a reference flow rate obtained by adding a predetermined value to the motor flow rate, the controller controls the regulator so the bi-directional pump tilting angle is adjusted to a tilting angle realizing the reference flow rate. If the instruction flow rate is not greater than the reference flow rate, the controller controls the regulator so the bi-directional pump tilting angle is adjusted to a tilting angle realizing the instruction flow rate.

An energy storage and regeneration system that converts irregular, non-constant, and variable input power to regular, constant, and controlled output power using hydraulics whereby the irregular input power is used to pump hydraulic fluid into an accumulator array where it is stored pressurized. Energy is released in a controlled fashion using a hydraulic motor operated by the pressurized hydraulic fluid from the accumulator array, in accordance with the specified power demand. One or more power units may be deployed depending on the amount of energy required at the output. Each power unit includes a hydraulic motor and associated floating accumulator whose internal pressure is controlled to maintain a substantially constant pressure differential across its associated motor. The system can be integrated into various energy system sources including renewable energy such as wind, PV or thermal solar, wave, tidal, etc. as well as various types of vehicles such as cars, trucks, motorcycles, trains, boats, etc.