The disclosure provides a hydraulic control device capable of suppressing an excessive increase in the rotation speed of a second pump and stabilizing the discharge pressure of the second pump. The target rotation speed of the second pump for making a pressure value of a first oil close to an estimated value of a pressure value of a third oil is calculated, and a feedback amount with respect to the target rotation speed is calculated by subtracting the estimated value of the pressure value of the third oil from the pressure value of the first oil detected by a hydraulic sensor. Time regions for performing calculation of the feedback amount include an update region in which the feedback amount with respect to the target rotation speed is updated, and a hold region in which update of the feedback amount with respect to the target rotation speed is temporarily stopped.

In a hydraulic control device switchable between a first state in which a first oil is supplied from a first pump to a hydraulic operation part via a bypass valve and a second state in which the first oil supplied from the first pump is pressurized by using the second pump and the pressurized first oil is supplied, as a second oil, to the hydraulic operation part, control that adds a correction hydraulic pressure of a predetermined amount to the hydraulic pressure of the oil discharged from a valve for adjusting the pressure of the oil supplied to the hydraulic operation part is performed when the second state is switched to the first state due to a stop or a low rotation state of the second pump.

A hydraulic actuator can be provided for actuating a functional part by a movement of a force transmission element, with a working piston which can be acted upon by a hydraulic pressure of a pressure supply and is movable thereover between a first extreme position and a second extreme position in a piston/cylinder unit, wherein two chambers separated from one another by the working piston are present and a first chamber is formed as a first working chamber with a pressure inlet and a hydraulic pressure applied to the first pressure inlet urges the working piston in the direction of the first extreme position in order to enlarge the first working chamber. At least one retaining means is provided which is capable of automatically locking the working piston in one of the extreme positions when this extreme position is reached, even without any hydraulic pressure being applied.

A hydraulic arrangement for a vehicle transmission includes a hydraulic pump for providing a system pressure for a first hydraulic system circuit and a lubrication pressure for a second hydraulic lubrication circuit. The arrangement also includes a control valve connected between a pump outlet of the pump and the two hydraulic circuits and has two different switching positions. The control valve, depending on the switching position, acts as a hydraulic connection between the pump and the system circuit or between the pump and the lubrication circuit.

A method of controlling an EOP of a hybrid vehicle may include controlling the EOP in a predetermined high-speed mode when the vehicle is started; controlling the EOP in a predetermined middle-speed mode in which the EOP is driven at revolutions per minute (RPM) lower than RPM of the high-speed mode when the high-speed mode is terminated; and controlling the EOP in a predetermined low-speed mode in which the EOP is driven at RPM lower than the RPM of the middle-speed mode when the vehicle is stopped.

Provided is a hydraulic control device in which in the rotation control of the second pump, the required discharge pressure of the second pump can be more reliably maintained below a predetermined pressure in the control that keeps the target rotation speed constant after the feedback control ends. In the rotation control of the second pump, in the control which keeps the target rotation speed constant after the feedback control ends, the rotation of the second pump is controlled by adding a predetermined addition rotation speed to the target rotation speed corresponding to the required discharge pressure. Since the required discharge pressure of the second pump can be maintained below a predetermined pressure in the fixed mode by the addition rotation speed, it can reliably obtain the effect of reducing the work load of the first pump and contribute to the improvement of the fuel efficiency of the vehicle.

Methods and systems for a vehicle transmission are provided. A transmission system includes, in one example, an intermediate shaft rotationally coupled to an input shaft and an output shaft, wherein the input shaft is configured to receive rotational input from an electric machine. The system further includes a first gear coupled to the intermediate shaft, and a plurality of clutches coupled to the input shaft and the output shaft and configured to in a first mode, transfer power directly between a second gear coupled to the input shaft, the first gear, and a third gear coupled to the output shaft, and in a second mode, transfer power indirectly between the second gear, the first gear, and/or the third gear.

Since an oil level of oil in a first space housing a transmission mechanism is lower than an oil level of the oil in a second space housing a differential gear, not only is it possible to lubricate a drive pinion and a ring gear housed in the second space with a sufficient amount of oil while cutting the total amount of oil compared with a case in which the oil levels of the first space and the second space are both high, but it is also possible to reduce the resistance of oil to stirring in the second space by discharging excess oil building up in the second space to the first space via a second oil passage formed along an axial center of a pinion shaft, and to prevent the oil level of the first space from decreasing excessively, thus avoiding aeration of an oil pump.

A hydraulic circuit for the transmissions of industrial and agricultural vehicles. The circuit comprises a feed pump driven by an internal combustion engine; a lubricating circuit; a main pressure regulator capable of bringing about a first change in the pressure of the working fluid in the circuit, this change in pressure being capable of regulation in relation to a first regulation pressure; a maximum pressure regulator for the lubrication circuit capable of bringing about a second change in pressure of the working fluid depending upon a second regulating pressure; and means for regulating regulation of the first and second regulating pressures.

A continuously variable transmission is provided with a drive belt (6) drive belt (3), fitted between a primary pulley (1) and a secondary pulley (2) of the transmission, each pulley having two pulley sheaves (4, 5) of which at least one pulley sheave (4) in each case is axially movable under the influence of a hydraulic pressure exerted in a pressure cylinder (11; 12) of a respective pulley (1; 2), and with a hydraulic control system for controlling these respective cylinder pressures (Pp, Ps) including two oil pumps (41, 42). A pump flow control valve (100, 48) is provided and is arranged to connect to or disconnect from the main hydraulic line (46) the one oil pump (42) in dependency on a difference between an actual line pressure (Ps) in the main hydraulic line (46) and a desired pressure level there for.