A method for the control of a hydraulic system of a motor vehicle is provided. A high-pressure branch is fed by a main oil pump which is driven by an internal combustion engine. The high-pressure branch or a low-pressure branch is fed by an additional oil pump depending on a switch position of a switching valve. The additional oil pump is used for feeding the high-pressure branch or the low-pressure branch depending on a total volume flow demand and on the volume flow available from the main oil pump. A nominal rotation speed of an electric motor which drives the additional oil pump is determined based on a volume flow balance, a valve status of the switching valve, a low-pressure pump map or a high-pressure pump map. Depending on the valve status, either the low-pressure pump map or the high-pressure pump map is used to determine the nominal rotation speed.

A pressurized fluid supply system for a vehicle transmission is provided. The fluid supply system has a pump with at least high and low pressure outputs that supplies high and low pressure components via a directional valve. The pressurized fluid supply system minimizes the parasitic loss upon a vehicle engine.

A hydraulic arrangement for a vehicle transmission includes a hydraulic system path leading to a hydraulic system circuit with a system pressure, a hydraulic lubrication path leading to a hydraulic lubrication circuit with a lubrication pressure, and a branching point connected to an output side of the system and lubrication paths. A variable displacement pump or a pump combination includes at least two fixed displacement pumps hydraulically connected to an input side of the branching point, and a variable displacement pump or at least one fixed displacement pump are hydraulically connected to the output side of the branching point and integrated into the hydraulic system path.

A dual clutch transmission comprises a housing formed therein with a gear chamber incorporating an odd-numbered speed gear train group and an even-numbered speed gear train group. An end of the input shaft is connected to an engine, and a cover is detachably attached to the housing opposite the end of the input shaft so as to define a clutch chamber divided from the gear chamber. A first clutch for the odd-numbered speed gear train group and a second clutch for the even-numbered speed gear train group are disposed in the clutch chamber. Fluid passages for supplying hydraulic fluid to the first and second clutches are formed in the cover.

An electric oil pump control method for operating a transmission of a hybrid vehicle which is driven by a first motor, a second motor, and an engine is provided. The method includes determining a number of revolutions of a low-pressure pump of an electric oil pump based on lubrication flow amount of the first motor, lubrication flow amount of the second motor, cooling flow amount of the first motor, and cooling flow amount of the second motor and determining a number of revolutions of a high-pressure pump of the electric oil pump based on control flow amount of a clutch of the transmission and lubrication flow amount of a rotation driver included in the transmission. A maximum value is determined of the determined number of revolutions of the low-pressure pump and the determined number of revolutions of the high-pressure pump as a number of revolutions of the electric oil pump.

A power transmission device for a hybrid vehicle has a first clutch device (1a) disposed in a drivetrain between an engine (E) and a driving wheel (D). A second clutch device (1b) disposed in a drivetrain extends from a motor (M) to the driving wheel (D). The oil pump (P), connected to the motor (M), supplies oil to a predetermined moving component disposed in the vehicle by using driving power of the motor (M). A transmission (A) is disposed in a drivetrain between the engine (E) and the motor (M) and the driving wheel (D). The transmission adjusts rotation speed of the motor (M). The power transmission device supplying oil by causing the motor (M) to rotate the oil pump (P) at an appropriate rotation speed.

A hydraulic pressure supply apparatus for automatic transmission having a first and a second regulator valves 50, 52 that are installed in a first and a second oil passages 46, 48 that connect a hydraulic pump 44 for pumping and discharging hydraulic oil from a reservoir 42 and a plurality of hydraulic actuators and depressurize the hydraulic oil discharged from the pump to pressure required by the hydraulic actuators, a third and a fourth oil passages 56, 58 that convey discharged hydraulic oil to lubrication system 54 and an ejector 60 having a nozzle 60a connected to one of the third and fourth oil passages and an intake 60b connected to the reservoir 42 such that hydraulic oil merged at a diffuser 60c is conveyed to the lubrication system 54 through a fifth oil passage 62, hydraulic energy generated by the hydraulic pump can be effectively utilized in an automatic transmission having the hydraulic actuators and lubrication system.

A gearbox for a motor vehicle. The gearbox comprises at least one fluid supply system. The fluid supply system comprises at least one pump. The fluid supply system comprises at least one fluid sump. The fluid supply system comprises at least one fluid reservoir. The fluid reservoir comprises at least a first fluid outflow leading into the fluid sump. The first fluid outflow can be controlled as a function of a state variable.

A hydraulically actuated transmission includes a reducing valve provided at a lubricant oil supplying circuit and configured to reduce a pressure of a lubricant oil having a predetermined pressure and output the lubricant oil with a reduced pressure; and a switching device (switching valve) configured to selectively switch between a first path and a second path as the path for supplying the lubricant oil from the reducing valve to a to-be-lubricated portion. The reducing valve is configured such that an output pressure of the lubricant oil from the reducing valve is higher when the second path is selected by the switching device, than when the first path is selected by the switching device.

A method for operating a fluid circuit of a motor vehicle, used for operating via a main circuit, and with a secondary circuit that is connected through a mechanical thermostatic valve to the main circuit, and an electric fluid conveying device for conveying a fluid. In a test mode, during a test period, the fluid conveying device is adjusted to a test operational speed and the actual amperage of the current required for the fluid conveying device is determined, wherein with an actual temperature of the fluid, which is lower than a switching temperature of the thermostatic value, the actual current amperage is stored as the first amperage value, and with an actual temperature, which is higher than the switching temperature, a second amperage value is stored, so that a proper function of the thermostatic valve is recognized when the second amperage is higher than the first amperage value.