The present disclosure relates to a limited-slip clutch system and method. In one aspect, the limited-slip clutch actuation system can include a hydraulic pump operated by a variable speed drive wherein the pump can be configured to generate hydraulic flow in a hydraulic circuit including an actuation branch line that actuates a clutch. The circuit may also include a flow regulating valve for regulating a hydraulic fluid flow rate through the hydraulic circuit wherein the flow regulating valve can be configured to prevent the hydraulic fluid flow rate from exceeding a set maximum flow rate regardless of a magnitude of the hydraulic pressure in the hydraulic circuit. In operation, the pump speed can be controlled based on a command pressure set point and the measured pressure in the actuation branch line and to minimize operational costs by operating the pump at a transition region of the system pressure-pump speed curve.

In a vehicle having a continuously variable transmission, a controller selectively performs a first control mode in which a transmission ratio is controlled in a stepless manner, and a second control mode in which the transmission ratio is controlled in a stepwise manner to perform an upshift after a vehicle speed has increased. When the second control mode is selected in response to a driver's acceleration request, the controller continuously downshifts the transmission ratio until the upshift is performed.

A multi-speed transmission with hydraulically actuated shift rods, wherein an actuating pressure (p_B) is applicable by a valve device (15) and shuttle valves (2C to 6D) to piston chambers (2A to 6B) of pistons (2 to 6), the actuating pressure being adjustable by valves (16, 17). The piston chambers (2A to 6B) can be brought into operative connection with a low-pressure region (52) by the shuttle valves (2C to 6D) and a prefilling valve (32, 33) or by the shuttle valves (2C to 6D), the valve device (15), and the valves (16, 17). Each of the shuttle valves (2C to 6D) has a spring assembly (2E to 6F), by which the shuttle valves (2C to 6D) are held below a pressure threshold of the actuating pressure (p_B) in an operating state that connects the piston chambers (2A to 6B) to the low-pressure region (52) by the prefilling valve (32, 33).

A hydraulic control circuit includes a first pressure regulating valve for regulating a pump discharge pressure, a second pressure regulating valve for adjusting a pilot pressure to a torque converter pressure, and a first oil passage that connects an output port of the first pressure regulating valve and a torque-converter input-side oil passage, the second pressure regulating valve having an input port connected to the first oil passage through a second oil passage, a drive port connected to the first oil passage through a third oil passage, a spool axially displaced according to a drive pressure inputted into the drive port for regulating the torque converter pressure, and an output port. A throttle is provided between the connection section of the first and third oil passages and the connection section of the first and second oil passages, for adjusting the torque converter pressure to an appropriate pressure.

A control apparatus for a stepped automatic transmission in which one of a plurality of shift speeds is established by selectively engaging a plurality of frictional engagement elements, the stepped automatic transmission mounted on a vehicle, the control apparatus includes: an electronic control unit configured to perform a control of prohibiting a plurality of shift that is transitioning from an upshift speed change to a downshift speed change, for a predetermined period, when a downshift speed change requirement is requested by an occurrence of an accelerator depression operation during an inertia phase of the upshift speed change in a driven state of a vehicle.

In a vehicle having a continuously variable transmission, a controller selectively performs a first control mode in which a transmission ratio is controlled in a stepless manner, and a second control mode in which the transmission ratio is controlled in a stepwise manner to perform an upshift after a vehicle speed has increased. When the second control mode is selected in response to a driver's acceleration request, the controller continuously downshifts the transmission ratio until the upshift is performed.

A method for starting or stopping an internal combustion engine which reduces starter loading and engine vibrations is provided. The method includes varying a valve stroke of at least one cylinder of the engine such that during the starting or stopping procedure the at least one cylinder undergoes decompression.

A control apparatus for a stepped automatic transmission in which one of a plurality of shift speeds is established by selectively engaging a plurality of frictional engagement elements, the stepped automatic transmission mounted on a vehicle, the control apparatus includes: an electronic control unit configured to perform a control of prohibiting a plurality of shift that is transitioning from an upshift speed change to a downshift speed change, for a predetermined period, when a downshift speed change requirement is requested by an occurrence of an accelerator depression operation during an inertia phase of the upshift speed change in a driven state of a vehicle.

A hydraulic control circuit includes a first pressure regulating valve for regulating a pump discharge pressure, a second pressure regulating valve for adjusting a pilot pressure to a torque converter pressure, and a first oil passage that connects an output port of the first pressure regulating valve and a torque-converter input-side oil passage, the second pressure regulating valve having an input port connected to the first oil passage through a second oil passage, a drive port connected to the first oil passage through a third oil passage, a spool axially displaced according to a drive pressure inputted into the drive port for regulating the torque converter pressure, and an output port. A throttle is provided between the connection section of the first and third oil passages and the connection section of the first and second oil passages, for adjusting the torque converter pressure to an appropriate pressure.

A multi-speed transmission with hydraulically actuated shift rods, wherein an actuating pressure (p_B) is applicable by a valve device (15) and shuttle valves (2C to 6D) to piston chambers (2A to 6B) of pistons (2 to 6), the actuating pressure being adjustable by valves (16, 17). The piston chambers (2A to 6B) can be brought into operative connection with a low-pressure region (52) by the shuttle valves (2C to 6D) and a prefilling valve (32, 33) or by the shuttle valves (2C to 6D), the valve device (15), and the valves (16, 17). Each of the shuttle valves (2C to 6D) has a spring assembly (2E to 6F), by which the shuttle valves (2C to 6D) are held below a pressure threshold of the actuating pressure (p_B) in an operating state that connects the piston chambers (2A to 6B) to the low-pressure region (52) by the prefilling valve (32, 33).