An unmanned underwater vehicle (UUV) with a hydraulic system (100) for use in cold surroundings and method of controlling such hydraulic system. The hydraulic system (100) comprises a hydraulic circuit (10). One or more tools (21,22) may be hydraulically operable via the hydraulic circuit (10). A pump (32) is configured to pressurize a flow of hydraulic fluid (F) via the hydraulic circuit (10) e.g. for actuating the tools (21,22). A valve system (40) comprises control valves (41,42,43) disposed in the hydraulic circuit (10) for controlling the flow of hydraulic fluid (F) through the hydraulic circuit (10). A controller (50) is configured to control one or more of the control valves (43) as a function of a temperature (T) of the hydraulic fluid (F).

A hydraulic unit is provided with: a manifold which forms a hydraulic circuit; a tank which is joined to the manifold; and a hydraulic pump which suctions hydraulic fluid in the tank and supplies the hydraulic fluid to the manifold, wherein the base end portion of a suction strainer is fitted into the hydraulic pump, and the suction strainer has such a shape that the base end portion of the suction strainer is not separated from the hydraulic pump in a state where the leading end portion of the suction strainer is in contact with the tank and an opening through which the hydraulic fluid is introduced from the tank is provided at the leading end portion.

Provided is a system and method to generate and control hydraulic fluid flow that exceeds the fluid flow capacity of an electrically driven pump to achieve high actuator retraction/extension speeds and/or electrical flow capacity of an electrical storage system to better control electrical storage. Electric machines and hydraulic pumps generally have a maximum speed beyond which they cannot be operated at. Further, electrical storage systems typically have storage capacities and rates beyond which they cannot be operated at. While an alternate approach could be to increase the hydraulic pump displacement, thus lowering the required electric machine and pump speed to generate a certain flow, it is typically desirable to reduce pump displacement in order to reduce required electric machine torque and minimize component size and losses.

A flow distribution control method for a hydraulic system, the hydraulic system comprising N loops L1-LN. The flow distribution control method comprises the following steps: S1: comparing pressures P1-PN at an inlet of an actuator in each loop of the hydraulic system; S2: according to the comparison result, determining a loop Lp1 which requires flow compensation; and S3: conducting flow compensation on the loop Lp1 according to the theoretical flow of the loop Lp1 and an actual flow in the loop Lp1 which flows into the actuator, wherein the number of loops in the loop Lp1 is less than or equal to N. Also disclosed are a flow distribution control device and a flow distribution control apparatus for the hydraulic system, the hydraulic system and a non-transitory computer-readable medium. An electric control pressure pump and a flow supplementing valve are employed to replace a constant pressure difference valve, and the flow of all branches may be supplemented, thereby avoiding the phenomenon of unequal flow distribution being generated due to flow distribution characteristics of a pressure compensation system being affected by the overflow area of the constant pressure difference valve. The foregoing employs a flow compensation scheme, has a simple structure, is insensitive to pollution, and has low investment costs.

The disclosure provides a flow self-compensating load sensing pump/valve coordinated electro-hydraulic system, including a prime mover, an electronically controlled variable pump, a flow control valve, a hydraulic actuator, a shuttle valve, an electronic control joystick, a bypass control valve, two pressure sensors, a bypass throttle valve, and a control system, where an oil outlet of the shuttle valve is connected to a right spring chamber of the bypass control valve, a left chamber and an oil inlet of the bypass control valve are connected to an oil outlet of the electronically controlled variable pump, an oil inlet and an oil outlet of the bypass throttle valve are connected to an oil outlet of the bypass control valve and an oil tank, two ends of the oil inlet and the oil outlet of the bypass throttle valve are provided with the first pressure sensor and the second pressure sensor, respectively.

The disclosure provides a flow self-compensating load sensing pump/valve coordinated electro-hydraulic system, including a prime mover, an electronically controlled variable pump, a flow control valve, a hydraulic actuator, a shuttle valve, an electronic control joystick, a bypass control valve, two pressure sensors, a bypass throttle valve, and a control system, where an oil outlet of the shuttle valve is connected to a right spring chamber of the bypass control valve, a left chamber and an oil inlet of the bypass control valve are connected to an oil outlet of the electronically controlled variable pump, an oil inlet and an oil outlet of the bypass throttle valve are connected to an oil outlet of the bypass control valve and an oil tank, two ends of the oil inlet and the oil outlet of the bypass throttle valve are provided with the first pressure sensor and the second pressure sensor, respectively.

A flow rate controller and a drive device are provided with a cylinder flow passage connected to an air cylinder; a main flow passage for supplying air to and discharging air from the air cylinder; an auxiliary flow passage that has a first throttle valve and through which exhaust air discharged from the air cylinder passes with a smaller flow rate than that of the main flow passage; a switch valve that switches between a first position in which the cylinder flow passage communicates with the main flow passage and a second position in which the cylinder flow passage communicates with the auxiliary flow passage; and a pilot air adjustment part that guides a portion of the exhaust air from the air cylinder as pilot air to the switch valve.

A gas-powered drive system has a drive which includes a first chamber and a second chamber which are separated from one another by a piston. One of the chambers is connected to a gas source to drive the work element and the other chamber is connected via an exhaust air throttle to a gas sink by means of a reversing valve to movement of the piston. A control valve is assigned to the driving chamber through which the driving chamber can be filled with gas from the gas source. The opening cross-section of the control valve is set as a function of a control pressure.

A fluid pressure system includes an actuator, an operating valve, and a spool valve. The spool valve is connected to a pressure source and a tank by a pressure source line and a tank line, respectively, and connected to the actuator by a first movement line and a second movement line. The spool valve moves from a neutral position to a movement position by a moving amount corresponding to a pilot pressure outputted from the operating valve, the movement position being a position at which the spool valve allows the pressure source line to communicate with the first movement line and allows the second movement line to communicate with the tank line. A relief line branches off from the second movement line, and the relief line connects to a tank. A variable throttle valve is provided on the relief line.

An actuation pressure to actuate one or more hydraulic actuators may be determined based on a load on the one or more hydraulic actuators of a robotic device. Based on the determined actuation pressure, a pressure rail from among a set of pressure rails at respective pressures may be selected. One or more valves may connect the selected pressure rail to a metering valve. The hydraulic drive system may operate in a discrete mode in which the metering valve opens such that hydraulic fluid flows from the selected pressure rail through the metering valve to the one or more hydraulic actuators at approximately the supply pressure. Responsive to a control state of the robotic device, the hydraulic drive system may operate in a continuous mode in which the metering valve throttles the hydraulic fluid such that the supply pressure is reduced to the determined actuation pressure.