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 hydraulic 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 at least two valves controlling a rotational speed of the motor, wherein one of the valves provides coarser flow control resolution and another of the valves provides finer flow control resolution.

The present disclosure relates to an implement connectable to a working vehicle. The implement includes an arm, a fastening arrangement arranged at a first part of the arm, and an attaching arrangement connected to a second part of the arm. The fastening arrangement is connectable to the working vehicle. The attaching arrangement is attachable to a working tool. The implement further includes a first hydraulic circuit configured to carry hydraulic fluid to at least one first hydraulic function and a local control element. The implement further includes a digital interface to the working vehicle. The local control element is arranged to receive an operator control signal via said digital interface for operator control of the at least one first hydraulic function.

A servo actuator is provided which may comprise a controller configured to control a plurality of solenoid valves based upon an output signal. The plurality of solenoid valves may be used to control the position of the object. For example, a set of solenoid valves, of the plurality of solenoid valves, may be configured to conduct fluid from a tank into a first chamber of the cylinder, conduct fluid from the tank into a second chamber of the cylinder, conduct fluid from the second chamber of the cylinder into a first solenoid valve and/or conduct fluid from the first chamber of the cylinder into the first solenoid valve. The first solenoid valve, of the plurality of solenoid valves, may be configured to conduct fluid from the set of solenoid valves into a vent valve based upon a pulse width modulation (PWM) signal received from the controller.

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 hydraulic unit includes an oil tank, a hydraulic pump, a first return pipe, and a first heat exchanger. The oil tank stores a hydraulic oil. The hydraulic pump supplies the hydraulic oil in the oil tank to an actuator. The first return pipe returns the hydraulic oil from a flow path between a discharge port of the hydraulic pump and the actuator to the oil tank. The first heat exchanger causes a coolant to exchange heat with the hydraulic oil returning to the oil tank through the first return pipe.

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 hydraulic system includes a pump to pressurize and output hydraulic fluid, an electric motor selectively driving the pump, and a controller to selectively control a target speed of the electric motor based on input from an operator control. A proportional directional control valve is in the load circuit and communicates with the pump and the controller. The proportional directional control valve controls a flow of hydraulic fluid to a hydraulic actuator associated with the load circuit such that the flow of hydraulic fluid to the hydraulic actuator is proportional to a signal provided by the controller. The signal is a function of the input from the operator control. Flow of hydraulic fluid to the hydraulic actuator through the proportional directional control valve is varied by the controller making a) variations of the target speed of the motor, and b) variations of the signal to the proportional directional control valve.

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.

In accordance with at least one aspect of this disclosure, a system includes, a servo configured to control a position of a valve, a driver operatively connected to control movement of the servo, a control module operatively connected to control the driver, can configured to control the driver with pulse width modulated output to control a frequency of a generator through movement of the servo.