A system for controlling fluid flow to and from a clutch includes a motor, a pump, and a valve assembly. The valve assembly includes a housing defining an interior. The housing defines a first orifice operably coupled to the pump and a second orifice operably coupled to the clutch. The valve assembly also includes a piston operably coupled to the motor and disposed within the interior of said housing. The piston is movable between a first position for allowing the fluid flow between the first orifice and the second orifice, a second position for obstructing the fluid flow between the first orifice and the second orifice, and a third position for limiting the fluid flow between the first orifice and the second orifice. The valve assembly additionally includes a biasing member coupled to the piston. The biasing member biases the piston toward the first position.

An apparatus to be applied to a vehicle including a transmission configured to execute a gear shifting operation for changing a gear ratio by engaging or disengaging friction engagement elements having friction members pushed by a piston that moves through hydraulic pressure supply to an oil chamber, the apparatus including: a memory storing mapping data for defining mapping, the mapping including a pressure variable and a period variable as input variables, the mapping including a stroke amount as an output variable, the pressure variable indicating a waiting pressure, the period variable indicating a waiting period; and a processor configured to: acquire values of the input variables, and calculate a value of the output variable by inputting, to the mapping, the acquired values of the input variables.

A method of controlling the electric current of a linear solenoid valve by performing pulse width modulation on a coil current for energizing a linear solenoid of the linear solenoid valve to adjust the hydraulic pressure of a working oil in a hydraulic clutch for transmitting and interrupting the rotational drive power from a power source to a drive wheel of a vehicle. The method includes setting the period of the pulse width modulation to a shorter value as the degree to which the hydraulic clutch is engaged increases from a disengaged state thereof. Here, the period of the pulse width modulation may be set in accordance with the variation of a duty ratio depending on the hydraulic pressure corresponding to the degree to which the hydraulic clutch is engaged.

Systems and methods for operating a driveline disconnect clutch of a hybrid vehicle are presented. In one example, torque capacity of a driveline disconnect is adjusted in response to a change in commanded line pressure. The torque capacity of the driveline disconnect clutch may be adjusted in according to a maximum transmission line pressure.

An apparatus to be applied to a vehicle including a transmission configured to execute a gear shifting operation for changing a gear ratio by engaging or disengaging friction engagement elements having friction members pushed by a piston that moves through hydraulic pressure supply to an oil chamber, the apparatus including: a memory storing mapping data for defining mapping, the mapping including a pressure variable and a period variable as input variables, the mapping including a stroke amount as an output variable, the pressure variable indicating a waiting pressure, the period variable indicating a waiting period; and a processor configured to: acquire values of the input variables, and calculate a value of the output variable by inputting, to the mapping, the acquired values of the input variables.

A system for controlling fluid flow to and from a clutch includes a motor, a pump, and a valve assembly, which includes a housing defining an interior and a first orifice operably coupled to the pump, a second orifice operably coupled to the clutch, and a third orifice fluidly coupled to one of said first and second orifices. A piston is operably coupled to the motor, is disposed within the interior, is movable between a first position for allowing a fluid flow between the first and second orifices, a second position for obstructing the fluid flow between the first and second orifices, and a third position for limiting the fluid flow between the first and second orifices. A biasing member is coupled to the piston, and biases the piston toward the first position when the motor is off. When the pump is activated and a pressure proximate the first orifice is equal to a pressure proximate the second orifice, the motor is energized and moves the piston to the second position. When pressure proximate the second orifice exceeds a predetermined threshold pressure, the energized motor is turned off and the biasing member moves the piston to the first position, or power in the energized motor is reduced and the piston moves to the third position.

A system for controlling fluid flow to and from a clutch includes a motor, a pump, and a valve assembly, which includes a housing defining an interior and a first orifice operably coupled to the pump, a second orifice operably coupled to the clutch, and a third orifice fluidly coupled to one of said first and second orifices. A piston is operably coupled to the motor, is disposed within the interior, is movable between a first position for allowing a fluid flow between the first and second orifices, a second position for obstructing the fluid flow between the first and second orifices, and a third position for limiting the fluid flow between the first and second orifices. A biasing member is coupled to the piston, and biases the piston toward the first position when the motor is off. When the pump is activated and a pressure proximate the first orifice is equal to a pressure proximate the second orifice, the motor is energized and moves the piston to the second position. When pressure proximate the second orifice exceeds a predetermined threshold pressure, the energized motor is turned off and the biasing member moves the piston to the first position, or power in the energized motor is reduced and the piston moves to the third position.

A system for controlling fluid flow to and from a clutch includes a motor, a pump, and a valve assembly. The valve assembly includes a housing defining an interior. The housing defines a first orifice operably coupled to the pump and a second orifice operably coupled to the clutch. The valve assembly also includes a piston operably coupled to the motor and disposed within the interior of said housing. The piston is movable between a first position for allowing the fluid flow between the first orifice and the second orifice, a second position for obstructing the fluid flow between the first orifice and the second orifice, and a third position for limiting the fluid flow between the first orifice and the second orifice. The valve assembly additionally includes a biasing member coupled to the piston. The biasing member biases the piston toward the first position.

A rotational system can include a shaft assembly rotationally coupling a first rotor, a second rotor, and a fluid pump. A fluid circuit can include the fluid pump that can be configured to motivate a working fluid through the fluid circuit. A pressurizing valve can be disposed downstream of the fluid pump wherein the rotational system can be configured to rotationally decouple the first rotor from the second rotor by closing the pressurizing valve. The pressurizing valve can be actuated by a controller. A method can include raising a pressure differential across a fluid pump driven by a shaft assembly thereby applying an increased braking torque to the shaft assembly. The pressure differential can be raised by actuating a valve in hydraulic communication with the fluid pump. The shaft assembly can rotationally couple a first rotor with a second rotor, and increasing the braking torque can decouple the rotors.

A rotational system can include a shaft assembly rotationally coupling a first rotor, a second rotor, and a fluid pump. A fluid circuit can include the fluid pump that can be configured to motivate a working fluid through the fluid circuit. A pressurizing valve can be disposed downstream of the fluid pump wherein the rotational system can be configured to rotationally decouple the first rotor from the second rotor by closing the pressurizing valve. The pressurizing valve can be actuated by a controller. A method can include raising a pressure differential across a fluid pump driven by a shaft assembly thereby applying an increased braking torque to the shaft assembly. The pressure differential can be raised by actuating a valve in hydraulic communication with the fluid pump. The shaft assembly can rotationally couple a first rotor with a second rotor, and increasing the braking torque can decouple the rotors.