Electrically controllable hydraulic system for a vehicle transmission and method for controlling the same An electrically controllable hydraulic system (1) for a vehicle transmission comprises a pressure pump system (4a, 4b) and a subsystem (1A) comprising a transmission element (2) and an electrically controlled hydraulic pressure controlling module (1B) including a hydraulic valve element (15) for controlling a hydraulic pressure for actuating the transmission element (2) and an electromagnetically controllable operating element (21) for operating the hydraulic valve element (15). The subsystem (1A) and the pressure controlling module (1B) have a first and a second cut-off frequency (f1, f2) with f2>f1. The hydraulic system includes a driver circuit (32) for driving the pressure controlling module (1B) that comprises a full bridge circuit and a control circuit (42) for simultaneously controlling both switching elements of the driver circuit with a duty cycle according to an input value of the input signal (Iset) dithered with a frequency (f.sub.dith) in the range (f1, f2).

A control system includes a variable displacement hydraulic pump, the pump having an inlet for receiving fluid, an outlet for discharging fluid under pressure, and a pump displacement input, a hydraulic motor having an inlet and an outlet, a fluid circuit including a supply conduit for conducting fluid discharged by the pump to the motor and a return conduit for returning fluid discharged by the motor to the pump, a pump displacement control cooperating with the pump displacement input in order to vary a displacement of the pump, a control circuit in communication with the pump displacement control for controlling the pump output such that the motor is driven at a constant rotational speed, and a system controller in communication with the control circuit and a remote location to transmit and receive information to and from the remote location.

A counter pressure valve arrangement for controlling a pressure level of a hydraulic fluid in a return line from a hydraulic actuator arrangement. The counter pressure valve arrangement comprises a counter pressure valve having: a moveable valve member; a counter pressure regulating port configured for being connected to the hydraulic actuator arrangement via the return line; a tank port configured for being connected to a tank or low pressure reservoir for storing low pressure hydraulic fluid; and a pump port configured for being connected to a source of pressurised hydraulic fluid. A first position of the valve member effects fluid communication between the pump port and the counter pressure regulating port for supplying pressurised hydraulic fluid to the return line (4), and a second position of the valve member effects fluid communication between the counter pressure regulating port and the tank port for discharging hydraulic fluid from the return line to the tank.

A counter pressure valve arrangement for controlling a pressure level of a hydraulic fluid in a return line from a hydraulic actuator arrangement. The counter pressure valve arrangement comprises a counter pressure valve having: a moveable valve member; a counter pressure regulating port configured for being connected to the hydraulic actuator arrangement via the return line; a tank port configured for being connected to a tank or low pressure reservoir for storing low pressure hydraulic fluid; and a pump port configured for being connected to a source of pressurised hydraulic fluid. A first position of the valve member effects fluid communication between the pump port and the counter pressure regulating port for supplying pressurised hydraulic fluid to the return line, and a second position of the valve member effects fluid communication between the counter pressure regulating port and the tank port for discharging hydraulic fluid from the return line to the tank.

The energy recovery system includes an inertial fluid container, a low pressure container, a high pressure container, a low pressure valve, and a high pressure valve, a valve flow conduit, and a valve controller. The valve controller switches, in response to a decrease in volume of the fluid chamber, the inertial fluid container between communicating with the low pressure container and the high pressure container, thereby generating inertial forces of the working fluid flowing toward the low pressure container in the inertial fluid container, and causing the working fluid to flow into the high pressure container by the inertial forces. The valve controller sets a switching frequency for the valves to a frequency close to an Nth-order (where N is a natural number) anti-resonance frequency of a flow conduit for the working fluid.

A fluid power control system for load handling mobile equipment includes a pair of hydraulic actuators for moving respective cooperating load-engaging members selectively toward or away from each other, or in a common direction, at respective asynchronous speeds to selectively attain either synchronous or asynchronous respective positions of the actuators. The actuators have sensors enabling a controller to monitor their respective movements and correct unintended differences in the actuators' respective movements, such as unintended differences in relative intended positions, speeds, or rates of change of speeds. Respective hydraulic valves responsive to the controller separately and nonsimultaneously decrease respective flows through the respective actuators to more accurately and rapidly correct differences from the intended relative movements of the actuators.

A fluid power control system for load handling mobile equipment includes a pair of hydraulic actuators for moving respective cooperating load-engaging members selectively toward or away from each other, or in a common direction, at respective asynchronous speeds to selectively attain either synchronous or asynchronous respective positions of the actuators. The actuators have sensors enabling a controller to monitor their respective movements and correct unintended differences in the actuators' respective movements, such as unintended differences in relative intended positions, speeds, or rates of change of speeds. Respective hydraulic valves responsive to the controller separately and nonsimultaneously decrease respective flows through the respective actuators to more accurately and rapidly correct differences from the intended relative movements of the actuators.

Multi-rotor hydraulic drone (1) comprising: a plurality of hydraulic motors (6) each receiving a pressurised fluid, propellers (5) driven by the hydraulic motors (6), at least one hydraulic pump (10) driven by at least one motor (11) for pressurising the fluid, a system for supplying the hydraulic motors (6) with pressurised fluid, a flight controller (14) for controlling the supply system according to the desired rotation speed for the hydraulic motors (6), the supply system comprising several channels (35; 36; 37; 38) for adjusting the power of at least one portion of the hydraulic motors (6).

A solenoid valve control system comprising a solenoid valve drive circuit applying a drive current to the solenoid valve; a pressure data calculation unit calculating a pressure data including a band and a cycle of pressure fluctuation from a pressure value; a pressure hysteresis calculation unit calculating a difference between the pressure value when the drive current value is increased and the pressure value when the drive current value is decrease as a hysteresis amount; a vibration determination unit determining whether or not the pressure data is included in an area outside the pressure data range, which is outside a first predetermined range; a hysteresis determination unit determining whether or not the pressure hysteresis amount is included in an area outside the pressure hysteresis amount range, which is outside a second predetermined range; and a drive frequency adjustment unit adjusting a drive frequency based on the determination result.