A power transmission device outputting torque from a first power source and a second power source to axles, is provided with: a first shaft coupled with the first power source; a differential configured to differentially distribute the torque to the axles; a first gear set configured to drivingly couple the first shaft with the differential; a second shaft coupled with the second power source; a second gear set drivingly coupled with the second shaft; a clutch configured to receive fluid pressure to drivingly and releasably couple the second gear set with the first gear set; and a pump driven by a third power source at least independent of the first power source and the clutch to generate the fluid pressure, the pump being disposed separate from the clutch and in fluid connection with the clutch to supply the fluid pressure.

This clutch control device is provided with: a supply valve and a supply valve control unit, which control the supply of an operating fluid to a pressure chamber; a first discharge valve and a first discharge valve control unit, which control the discharge of the operating fluid in the pressure chamber; and a second discharge valve and a second discharge valve control unit, which control the discharge of the operating fluid in the pressure chamber. When it is determined that the engagement and disengagement switching of a clutch device 2, which is necessitated by the discharge of the operating fluid in the pressure chamber, is required, the first discharge valve is controlled to be opened and then the second discharge valve is controlled to be opened.

A vehicle control device applicable to a vehicle including an engine includes an electric motor coupled to the engine, a hydraulic clutch, a solenoid control valve, a first travel control unit, a second travel control unit, and a fail-safe control unit. The hydraulic clutch is engaged when hydraulic oil is supplied and disengaged when the hydraulic oil is discharged. The solenoid control valve includes a solenoid. The solenoid control valve supplies the hydraulic oil to the hydraulic clutch when the solenoid is in a non-energized state, and discharges the hydraulic oil when the solenoid is in the energized state. The first travel control unit executes an engine traveling mode, and the second travel control unit executes an inertial traveling mode. The fail-safe control unit drives the electric motor when the solenoid is switched from the energized state to the non-energized state while the inertial traveling mode is executed.

A hydraulic control device with a pressure control valve that has a control piston and a modulating piston which can move relative to one another. The control piston and the modulating piston are pushed apart from one another by at least one spring. At one end face of the modulating piston there is arranged a pressure chamber in such a manner that when the pressure chamber is filled, the modulating piston is caused to move in the direction toward the control piston. The pressure chamber can be filled by a first volume flow Q1 of a pressure medium. A venting line, with at least one further throttle, is connected to the pressure chamber. A second volume flow Q2 can be discharged, via the venting line, from the pressure chamber. The hydraulic control device can be utilized in a marine transmission.

A method actuates a hydraulic system for an actuation device of a motor vehicle. The hydraulic system has a pump and multiple valves which are each arranged between a system rail connected to a pump outlet and a hydraulic consumer. The pump is switched between a normal operation and an enhanced operation according to an existing total energy demand of the hydraulic consumers. In normal operation, the pump is driven when the system pressure is below a lower pressure threshold and switched off when the system pressure is above an upper pressure threshold. In the enhanced operation, the pump is permanently driven and each of the valves is operated according to an individual energy demand of the respective hydraulic consumer as soon as the system pressure achieves or exceeds a threshold value.

A hydraulically actuatable shift element (100) includes a clutch piston (101), a fast fill piston (102), a fast fill valve (103), a fast fill pressure chamber (126), and a clutch pressure chamber (117). The fast fill valve (103) includes a sealing body (132) and a control body (131). Before the actuation of the shift element (100), the sealing body (132) is in a first switching position, in which the fast fill pressure chamber (126) is connected to a pressurized oil source (108) and, after the actuation of the shift element (100) in a second switching position, seals off the fast fill pressure chamber (126) with respect to the rest of the hydraulic system. The control body (131) has a first pressure surface (A18) and a second pressure surface (A19), wherein, in the first switching position, only the first pressure surface (A18) is pressurizable from the pressurized oil source (108). The fast fill valve (103) is configured such that, in the second switching position or between the first switching position and the second switching position of the control body (131), the second pressure surface (A19), in addition to the first pressure surface (A18), is pressurizable.

Methods and systems are provided for wet clutch pressure control to reduce drag and degradation of rotary seals in a transmission. In one example, a method may include determining an upper threshold pressure based on a rotational speed of a shaft of the transmission, determining a lower threshold pressure based on the rotational speed of the shaft, and adjusting a pressure of hydraulic fluid applied to the clutch to be between the upper threshold pressure and the lower threshold pressure. In this way, the pressure of the hydraulic fluid applied to the clutch may be maintained at a level that allows full torque transfer by the wet clutch while reducing drag on the rotary seals.

A drive force transfer device includes a multi-plate clutch that transfers a drive force using a friction force generated between a plurality of clutch plates; a housing that houses the multi-plate clutch; a piston that presses the multi-plate clutch using a hydraulic pressure of operating oil supplied to a hydraulic chamber provided in the housing; a hydraulic unit configured to supply the operating oil to the hydraulic chamber; and a control device configured to control the hydraulic unit, the control device being configured to correct a control amount for the hydraulic unit based on a result of a temperature estimation based on operation of the hydraulic unit.

An automatic transmission includes a clutch having a drum section, a hub, a friction plate, a piston that presses the friction plate, a hydraulic chamber to which hydraulic oil is supplied to urge the piston in a direction toward the friction plate, and a cancellation chamber to which hydraulic oil is supplied to cancel a centrifugal hydraulic pressure applied to the hydraulic oil in the hydraulic chamber, and the piston is interposed between the hydraulic chamber and the cancellation chamber. The drum section includes communication passages that extend in a radial direction and respectively communicate with the hydraulic chamber and the cancellation chamber. Of the communication passages, in the communication passage that communicates with the cancellation chamber, an adjustment member is provided at an end portion on a radially inner side, and can adjust an atmospheric air release position of the communication passage in the radial direction.

Method for determining a kisspoint of a clutch. A method is provided of determining a kisspoint of a clutch in a driveline of a vehicle comprising a. increasing a target clutch pressure of a clutch piston up to a first predetermined test target pressure, b. increasing the target clutch pressure up to an upper target pressure and subsequently keeping the target clutch pressure stable for a predetermined time interval, c. monitoring a parameter indicative for the filling of the clutch piston, e.g. the rotational speed of a pump, during the predetermined time interval, d. repeating steps a., b., and c. for at least one further predetermined test target pressure, and e. determining the kisspoint based on the monitored parameter indicative for the filling of the clutch piston.