A pressure regulator includes an outlet pressure sensor, loading and unloading electromagnetic valves, and a regulator control circuit operatively connected to the loading and unloading electromagnetic valves and configured to pilot the loading and unloading electromagnetic valves to cancel an error signal given by a difference between an inlet signal corresponding to a desired outlet pressure and a feedback signal provided by the outlet pressure sensor. The pressure regulator includes an engaging current analysis circuit to detect and store reference characteristics of the engaging current of the solenoid of the loading electromagnetic valve in a stable inlet pressure condition, monitor the engaging current to detect any variation of its characteristics with respect to the corresponding reference characteristics, and, in the event of variation, provide a pilot modulation signal to at least one of the loading or unloading electromagnetic valves or a pressure variation signal to the regulator control circuit.

A hydraulic system is provided. The hydraulic system may include a fluid pressure source in fluid communication with a supply line, a return line in fluid communication with a tank, a hydraulic function having a workport, a first control valve having a first proportional solenoid, a second control valve having a second proportional solenoid, and a controller. The controller being configured to selectively energize the first proportional solenoid, the second proportional solenoid, or the first proportional solenoid and the second proportional solenoid to control a system pressure differential, defined between the return line and the workport, within a range that is defined by a sum of a first predefined range defined by the first control valve and a second predefined range defined by the second control valve.

A method for operating a hydraulic valve of a hydraulic device of a motor vehicle transmission device, wherein an actuating current of the hydraulic valve is superposed with a modulation alternating current in order to adjust a shaking vibration of the hydraulic valve by a control device, wherein a deviation between an actual pressure resulting from the actuating current and a setpoint pressure determined as a function of the actuating current is determined for the hydraulic device by means of an electronic computing device, and an amplitude and/or a frequency of the modulation alternating current is increased as compared to a starting value equalizing a hysteresis of the actual pressure relative to the setpoint pressure, as a function of a tolerance range being exceeded by the determined deviation.

A method of calibrating a solenoid actuated valve includes: providing a brake system including a fluid pressure source: providing a valve having a solenoid, and wherein the valve is in fluid communication with the fluid pressure source; operating the fluid pressure source to provide a constant flow of fluid to the valve; energizing the solenoid of the valve with a constant current such that fluid flows through the valve; measuring the pressure of the fluid flowing at the valve; adjusting the current sent to the solenoid until a predetermined pressure has been obtained; storing a nominal current value of the current required to obtain the predetermined pressure; and calibrating the valve by adding a correction offset factor to the nominal current value for future actuation of the solenoid of the valve.

The present invention provides an engineering machinery hydraulic system with compensation differential pressure controllable, uses an electronic pressure compensating valve to solve the problem of flow mismatch under conditions of pressure over-limit and flow saturation, and realizes proportional shunt control and high-precision flow distribution of the system. The engineering machinery hydraulic system disclosed in the present invention has the advantages of low energy consumption, fast response speed, and high flow control precision.

An example valve includes: a main piston comprising: a channel that is fluidly coupled to a first port of the valve, a pilot seat, and one or more cross-holes fluidly coupled to a second port of the valve; a pilot check member configured to be subjected to a fluid force of fluid in the channel of the main piston acting on the pilot check member in a proximal direction; a solenoid actuator sleeve comprising a chamber; a first setting spring disposed in the chamber and configured to bias the solenoid actuator sleeve in a distal direction; and a second setting spring configured to bias the pilot check member in the distal direction, such that the first setting spring and the second setting spring cooperate to apply a biasing force in the distal direction on the pilot check member toward the pilot seat against the fluid force.

The present invention relates to a hydraulic valve control unit for an open center hydraulic system, the open center hydraulic system comprising a pump, a shunt valve and one or more actuator valves coupled to the shunt valve, wherein each actuator valve is controlling a corresponding actuator's position, the hydraulic valve control unit comprising a processor and a memory, said memory containing instructions executable by said processor, wherein said hydraulic valve control unit is configured to obtain user input data indicative of at least a desired actuator's position, determining opening area values of the one or more actuator valves using a predetermined relation dependent on the user input data, determining an opening area value of the shunt valve using the predetermined relation dependent on the user input data, controlling the shunt valve based on the opening area value of the shunt valve, and controlling the one or more actuator valves based on the opening area values of the one or more actuator valves. The invention further relates to an open center hydraulic system.

A method for controlling a hydraulic actuator (2) of a system (1) by means of a valve having a valve element is described. A position of the valve element determines a pressure supplied to a hydraulic actuator (2). In such a method a variable dead band should be minimized. To this end a start position of the valve element is preadjusted as a function of at least one parameter outside the hydraulic actuator (2).

A valve block arrangement configured as a closed center system includes at least one main spool for controlling a hydraulic consumer. The main spool is configured to open and close at least one pressure medium connection between a hydraulic pump and the consumer in controlled, continuous fashion and, in at least one embodiment, is electrically activated. A bypass flow path with a cut valve branches off between the adjustable, hydraulic pump and the main spool. The cut valve is configured to open and close a pressure medium connection between the hydraulic pump and a tank in controlled, continuous fashion. The cut valve is electrically activatable.

A hydraulic circuit is disclosed. The hydraulic circuit may comprise an actuation valve configured to actuate a flow of hydraulic fluid to and from the hydraulic consumer, a first control valve in fluid communication with the actuation valve through a first pilot line and configured to displace the actuation valve to a first position when actuated, and a second control valve in fluid communication with the actuation valve through a second pilot line and configured to displace the actuation valve to a second position when actuated. The first pilot line and the second line may each have a fixed minimum back pressure sufficient to maintain dissolved air in the hydraulic fluid.