An electrohydraulic servo valve (EHSV) includes a housing assembly, a spool valve, an armature, a control mechanism, and a feedback spring. The spool valve is movably disposed within the housing assembly. The armature is rotationally mounted on the housing assembly. The control mechanism is coupled to the armature and is rotatable therewith. The feedback spring is coupled between the control mechanism and the spool valve, and includes a helical coil that is disposed on and engages the control mechanism, and a cantilever portion that extends from the helical portion to a terminus that engages the spool valve.

An electro hydraulic servo valve and a method of controlling pressure therein includes a first stage unit including a moveable direct drive valve, a second stage unit including a centering spring and a second stage spool valve that is fluidly connected to the moveable direct drive valve, and at least one pressure feedback fluid line fluidly connected to the first stage unit. The moveable direct drive valve selectively supplies fluid pressure to the second stage unit. Motion of the second stage unit is arrested using the centering spring and motion of the first stage unit is arrested when pressure is fed back to the first stage unit. A supply pressure or a return pressure is metered using the pressure feedback fluid line.

The present disclosure relates to a method, a device, and a system for controlling a hydraulic pump of a construction machine, the system comprising: an engine; an engine control unit configured to control the engine by using engine limit torque information and current engine torque information of the engine; a hydraulic pump operated by power supplied from the engine; at least one actuator driven by a hydraulic pressure discharged from the hydraulic pump; and a hydraulic pump control device configured to control a limited swash plate angle of the hydraulic pump by using a torque of the hydraulic pump and the engine limit torque information received from the engine control unit.

The present disclosure relates to a method, a device, and a system for controlling a hydraulic pump of a construction machine, the system comprising: an engine; an engine control unit configured to control the engine by using engine limit torque information and current engine torque information of the engine; a hydraulic pump operated by power supplied from the engine; at least one actuator driven by a hydraulic pressure discharged from the hydraulic pump; and a hydraulic pump control device configured to control a limited swash plate angle of the hydraulic pump by using a torque of the hydraulic pump and the engine limit torque information received from the engine control unit.

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 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 hydraulic control system for a machine is provided. The hydraulic control system includes a fluid reservoir and a pump motor. The pump motor is fluidly coupled to the fluid reservoir. The pump motor is configured to provide pressurized fluid and to receive fluid to provide a power output to the shaft. The hydraulic control system further includes an actuator and an accumulator fluidly coupled to the pump motor and the actuator. The hydraulic control system further includes an accumulator valve and a controller. The accumulator valve is fluidly coupled between the accumulator and the pump motor. The controller is in communication with the pump motor and the accumulator valve. The controller is configured to detect an operator command to operate the power source; determine pressure at the accumulator; and selectively move the accumulator valve to fluidly connect the accumulator with the pump motor.

A hydraulic control system for a machine is provided. The hydraulic control system includes a fluid reservoir and a pump motor. The pump motor is fluidly coupled to the fluid reservoir. The pump motor is configured to provide pressurized fluid and to receive fluid to provide a power output to the shaft. The hydraulic control system further includes an actuator and an accumulator fluidly coupled to the pump motor and the actuator. The hydraulic control system further includes an accumulator valve and a controller. The accumulator valve is fluidly coupled between the accumulator and the pump motor. The controller is in communication with the pump motor and the accumulator valve. The controller is configured to detect an operator command to operate the power source; determine pressure at the accumulator; and selectively move the accumulator valve to fluidly connect the accumulator with the pump motor.

A hydraulic assembly for supplying an attachment with hydraulic power of an agricultural towing vehicle, including a hydraulic work port for the passage of a hydraulic medium delivered by a pump, a pressure port, hydraulically connected to the work port, for delivering hydraulic power to the attachment, a hydraulic feedback port for receiving a hydraulic feedback pressure from the attachment, a signal port for delivering a feedback signal in dependence on the hydraulic feedback pressure, and a pressure sensor, between the hydraulic feedback port and the signal port, for conversion of the feedback pressure into the feedback signal.

A hydraulic assembly for supplying an attachment with hydraulic power of an agricultural towing vehicle, including a hydraulic work port for the passage of a hydraulic medium delivered by a pump, a pressure port, hydraulically connected to the work port, for delivering hydraulic power to the attachment, a hydraulic feedback port for receiving a hydraulic feedback pressure from the attachment, a signal port for delivering a feedback signal in dependence on the hydraulic feedback pressure, and a pressure sensor, between the hydraulic feedback port and the signal port, for conversion of the feedback pressure into the feedback signal.