The present disclosure describes a hydraulic control system comprising a first pressure chamber and a second pressure chamber, each pressure chamber configured to receive a hydraulic fluid, a first movable member configured to assume a position depending on a hydraulic pressure of the hydraulic fluid in the first pressure chamber and a second movable member configured to assume a position depending on a hydraulic pressure of the hydraulic fluid in the second pressure chamber, a hydraulic command circuit configured to provide the hydraulic fluid and to control the hydraulic pressure of the hydraulic fluid in the first pressure chamber and/or the second pressure chamber, having a switchable valve in fluid communication with the first pressure chamber, wherein the switchable valve is configured to be pilotable depending on the hydraulic pressure of the hydraulic fluid in the second pressure chamber.

A hydraulic assembly with a lubricant output, a control output and a pump which can supply a hydraulic fluid flow to the lubricant output and the control output. A switching valve with structurally predefined hysteresis is arranged between a pump output and the control output of the hydraulic assembly. Depending on the pressure in the branch between the pump output and the control output, the valve can be switched between an open position in which the control output is connected to the pump output, and a blocking position in which the control output is blocked off. The switching valve switches from the open position to the blocking position when the pressure provided by the pump exceeds an upper switching threshold, and returns from the blocking position to the open position when the pressure provided by the pump falls below a lower switching threshold. A clutch can be switched by means of such a hydraulic assembly, and a method for actuating the clutch.

Methods and systems for operating a plurality of electrical loads are described. In one example, the systems include electrical circuits for operating solenoid valves of a transmission that may be operated to simultaneously control two or more clutches for engaging and disengaging transmission gears. The systems and method may reduce hardware costs.

A valve device (2), of a pneumatically actuatable friction clutch engageable by spring force, includes at least one inlet valve (16, 18) connected on the input side to a pressurized supply line and on the output side to an actuating cylinder of the friction clutch. A pressure-sustaining valve (20, 28) is upstream or downstream of the inlet valve and is designed as a check valve closing in the backflow direction. The pressure-sustaining valve is a springless check valve and includes a housing ring (22, 30) having a retaining basket (36), a closing element (24, 32), and a valve seat (26, 34). The closing element, in the depressurized state and with a positive pressure gradient is held in the retaining basket (36) of the housing ring (22, 30) and, with a negative pressure gradient is pressed out of the retaining basket (36) and against the valve seat (26, 34).

The present invention is a hydraulic pressure control device for an automatic transmission that performs a gear shift by switching between engagement and disengagement of a plurality of friction engagement elements and includes solenoid valves, provided corresponding to the friction engagement elements, respectively, that switches between engagement and disengagement of the friction engagement elements by switching between supply and non-supply of hydraulic pressures to the friction engagement elements, and a control device that switches between supply and non-supply of the hydraulic pressures to the friction engagement elements by supplying a predetermined control current to the solenoid valves, in which the control device supplies a fixation preventing current lower than the control current to at least one of the solenoid valves corresponding to the friction engagement elements in a disengagement state of the plurality of friction engagement elements.

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 disconnected, hydraulic disc coupling (4) in an AWD vehicle with a hydraulic cylinder (14) for its actuation is to be quickly connected or engaged. The effective piston area in the cylinder (14) is for that reason reduced during the connection phase.

The invention relates to a hydraulic circuit (1) of a torque transmission device, wherein at least two, in particular closed in a non-actuated state (normally closed), clutches (2, 3) of the torque transmission device can be element (12, 13) of the hydraulic circuit, wherein in a clutch opening state, every clutch valve element (12, 13) is connected to a high-pressure line (30) that is applied with the pressure of a high-pressure hydraulic accumulator (31) and/or generator (32), by means of a pressurisation line (22, 23) for the deflection of the clutch (2, 3), and in a closing state, same is connected to a low-pressure tank (40) by means of a tank line (42, 43, 44, 45, 46, 47, 48, 49) for releasing a deflection pressure, and wherein the tank lines (42, 43, 44, 45, 46, 47, 48, 49) of the clutch valve elements (12, 33) are guided to a safety valve (50), in particular by means of a common collection tank line (41), which safety valve can be switched in such a way that the tank lines (42, 43, 44, 45, 46, 47, 48, 49) can be applied with the pressure of the high-pressure line (30).

A method for controlling clutch pressure in an electronically controlled limited slip differential comprises receiving a target clutch pressure command indicative of a desired differential torque transfer setting. Processing the target clutch pressure command comprises estimating one of a motor current or a motor speed, calculating an integrated error of a target motor current or an integrated error of a target motor speed, calculating gains over time based on the estimated motor current or the estimated motor speed and based on the integrated error of the target motor current or the integrated error of the target motor speed, applying the calculated gains thereby forming a closed loop feedback, and calculating an oscillation. The target motor current or the target motor speed is applied to a motor connected to a clutch in the differential according to the calculated oscillation to control the clutch pressure of the differential.

A fluid control device includes: a valve body accommodating chamber having an inner space divided into a first chamber and a second chamber by a first valve body; a receiving port, which opens to the first chamber and through which a fluid from an accumulator is received in the first chamber, and a discharge port, which opens to the first chamber and through which the fluid is discharged from the first chamber; a guide path guiding the fluid from the accumulator to the second chamber such that the first valve body moves to a valve-closed position to close the discharge port; a second valve body switchable between a state of maintaining pressure of the fluid guided to the second chamber and a state of releasing the pressure; and a bias member biasing the first valve body to the valve-closed position.