A method of controlling an actuator includes switching a primary solenoid valve to a first mode to fluidically connect a supply pressure source to a control chamber of a pilot valve. A fluid from the supply pressure source is directed through the primary solenoid valve to fill the control chamber of the pilot valve and put the pilot valve in a first position. The first position fluidically connects a second chamber of the actuator to a return pressure source. The actuator includes a cylinder between the first chamber and the second chamber and a rod attached to the cylinder. The fluid from the supply pressure source is directed into the first chamber of the actuator to move the cylinder and the rod in a first direction while the pilot valve is in the first position.

A valve device that changes the direction of flow of a hydraulic fluid supplied to and discharged from a cylinder mechanism to actuate the cylinder mechanism, the valve device including: a control valve including a main spool axially movable between different positions; a lock valve including a plunger and a pressure chamber; and a selector valve including a selector spool operable in conjunction with the main spool to axially move between different positions, the selector spool being located adjacent to the main spool and having an axis crossing an axis of the main spool.

Embodiments of the disclosure relate to a system designed to compensate for flow disturbances when changing a flow rate in the system. The system includes a flow source device having an inlet and an outlet. The inlet is configured to receive fluid at a first pressure, and the outlet is configured to output the fluid at a second pressure that is higher than the first pressure. The system also includes a fluid control device having an inlet port and a drain port. The inlet port of the fluid control device is configured to receive flow from the outlet of the flow source device. Further, the system includes a constant flow regulator configured to provide a leakage flow to a drain output. The constant flow regulator is configured to decrease the leakage flow in response to the drain port of the fluid control device.

A fluidic control system (1) for controlling a vehicle, which includes a controller (2) and a closed fluidic circuit. The circuit includes a pump (3) for pressurizing fluid in the circuit, valve means (40, 50, 60), an actuator (4, 5, 6) and a precharge accumulator (7). The valve means (40, 50, 60) is fluidly connected to the inlet and outlet of the pump (3) and the actuator (4, 6) is fluidly connected to the valve means (40, 50, 60) for selectively receiving pressurized fluid therefrom. The precharge accumulator (7) includes a movable member (73, FIG. 2) that describes a variable volume (71) fluidly connected to the circuit between the valve means (40, 50, 60) and the inlet of the pump (3). The system (1) also includes a sensor (70) for determining the position of the movable member (73) for estimating the quantity of fluid and/or detecting an abnormal pressure variation within the circuit.

A fluidic control system (1) for controlling a vehicle, which includes a controller (2) and a closed fluidic circuit. The circuit includes a pump (3) for pressurizing fluid in the circuit, valve means (40, 50, 60), an actuator (4, 5, 6) and a precharge accumulator (7). The valve means (40, 50, 60) is fluidly connected to the inlet and outlet of the pump (3) and the actuator (4, 6) is fluidly connected to the valve means (40, 50, 60) for selectively receiving pressurized fluid therefrom. The precharge accumulator (7) includes a movable member (73, FIG. 2) that describes a variable volume (71) fluidly connected to the circuit between the valve means (40, 50, 60) and the inlet of the pump (3). The system (1) also includes a sensor (70) for determining the position of the movable member (73) for estimating the quantity of fluid and/or detecting an abnormal pressure variation within the circuit.

A hydraulic valve comprises a proportional piloted valve that controls pressure and includes means for restricting pilot flow through the pilot flow passage. The means for restricting pilot flow defines a restriction in the pilot flow passage when a movable spool disposed in an axial bore of the body of the valve is in a neutral position. The restriction varies as a function of spool movement such that flow of hydraulic fluid through the pilot flow passage is variably restricted as a function of the position of the spool over its range of travel.

An example valve assembly includes a first workport fluidly coupled to a first actuator; a second workport fluidly coupled to the first actuator; a third workport fluidly coupled to a second actuator, wherein the third workport is fluidly coupled to the first workport via a first fluid passage; a fourth workport fluidly coupled to the second actuator, wherein the fourth workport is fluidly coupled to the second workport via a second fluid passage; and a spool axially movable in a bore within the valve assembly, wherein when the spool is shifted axially in a first axial direction, pressurized fluid is provided to the first workport and to the third workport via the first fluid passage, and when the spool is shifted axially in a second axial direction opposite the first axial direction, pressurized fluid is provided to the second workport and to the fourth workport via the second fluid passage.

A hydraulic device with the position sensor feedback-controlled by a servo amplifier on the basis of a deviation between a command value of a command signal and a position sensing value from a position sensor includes: a computation processing section that outputs the position sensing value as a sensing signal; a communication device that transmits the sensing signal to the servo amplifier, and receives a signal from the servo amplifier; and a storage section storing characteristics information of the hydraulic device to be read via the communication device. The characteristics information at least includes: calibration information which is measured and acquired in advance in a test stand in a manufacturing process of the hydraulic device, and includes a position sensing value from the position sensor and a characteristics value of the hydraulic device, associated with each other; and flow rate characteristics information including a flow rate of the hydraulic device.

Disclosed is a hydraulic control valve assembly of automatic steering system for agricultural machine including a proportional directional valve (3). A balancing valve (1) is arranged between the proportional directional valve (3) and the steering cylinder. A first shuttle valve (2) is arranged between the proportional directional valve (3) and the balancing valve (1). The first shuttle valve (2) is positioned on one side of the proportional directional valve (3). An overflow valve (4) is positioned on another side of the proportional directional valve (3). The overflow valve (4) is connected to a second shuttle valve (6) and a logic valve (5) respectively. The hydraulic control valve assembly has a large control power, a rapid response, and is more suitable for the autonomous navigation operation of agricultural machine. Moreover, the system saves more energy, such that the autonomous navigation operation of agricultural machine is more stable.

An electrohydraulic transmission control system having a parking lock valve by which a parking lock cylinder of a parking lock device can be charged with an actuation pressure adjustable in an operating-state-dependent manner by at least one pilot pressure adjustable in the region of an electrohydraulic pressure adjuster and/or one pressure source. Above a defined actuation pressure level, the parking lock valve can be held in a defined operating state in which the actuation pressure can be applied to the parking lock cylinder. The actuation and pilot pressures can be applied to a valve device such that when the actuation and pilot pressure levels approximately correspond to one another, the region of the control system which conducts the actuation pressure is operatively connected, upstream of the parking lock valve, to a pressure region in the region of the valve device with a pressure lower than the defined actuation pressure level.