Abstract: An apparatus for multiplexing gear engagement control in an automatic transmission is provided. At least two friction engagement devices are configured to selectively engage and disengage a different gear ratio of the transmission. A trim system is configured to selectively supply engagement and disengagement pressures to at least one fluid passageway. A first control valve is fluidly coupled directly to the at least one fluid passageway and directly to each of the at least two friction engagement devices. The first control valve is configured to selectively route the engagement and disengagement pressures through the first control valve directly to the at least two friction devices.

Abstract: A variator fault detection system for a continuously variable transmission is incorporated into a hydraulic control circuit that controls fluid pressure applied to a variator of the continuously variable transmission. The hydraulic control circuit for the variator includes a number of electrically-controlled shift valves and pressure control valves. Sensing devices are multiplexed to these valves to detect a number of different possible fault states relating to the variator shift valves and the variator pressure control valves.

Abstract: A fail-to-neutral diagnostic technique for a transmission that includes a variator may include monitoring a state of a pressure differential valve fluidly coupled to a high side pressure applied to at least one actuator coupled to at least one corresponding roller of the variator and also fluidly coupled to a low side pressure applied to the at least one actuator, determining from the state of the pressure differential valve a variator torque sign corresponding to whether torque transferred by the at least one roller is positive or negative, determining an expected variator torque sign based on current operating conditions of the transmission, and commanding the transmission to a true neutral condition if the determined variator torque sign is different from the expected variator torque sign.

Abstract: A variator fault detection system for a continuously variable transmission is incorporated into a hydraulic control circuit that controls fluid pressure applied to a variator of the continuously variable transmission. The hydraulic control circuit for the variator includes a number of electrically-controlled shift valves and pressure control valves. Sensing devices are multiplexed to these valves to detect a number of different possible fault states relating to the variator shift valves and the variator pressure control valves.

Abstract: A fail-to-neutral diagnostic technique for a transmission that includes a variator may include monitoring a state of a pressure differential valve fluidly coupled to a high side pressure applied to at least one actuator coupled to at least one corresponding roller of the variator and also fluidly coupled to a low side pressure applied to the at least one actuator, determining from the state of the pressure differential valve a variator torque sign corresponding to whether torque transferred by the at least one roller is positive or negative, determining an expected variator torque sign based on current operating conditions of the transmission, and commanding the transmission to a true neutral condition if the determined variator torque sign is different from the expected variator torque sign.

Abstract: A method, apparatus and system for controlling transmission clutch and/or variator system pressures is provided. A transmission control unit and a pressure control device including an electro-hydraulic valve and a pressure switch cooperate to provide self-calibrating clutch and/or variator pressure control systems.

Abstract: An apparatus and method are disclosed for controlling fluid flow to a variator which responsive to separate high and low pressure fluids to control an output torque thereof. A first trim valve may be responsive to a first control signal to supply a first fluid at a fluid outlet thereof. A second trim valve may be responsive to a second control signal to supply a second fluid at a fluid outlet thereof. A variator switching sub-system may controllably supply the high pressure fluid and the low pressure fluid to the variator. A multiplex valve may be fluidly coupled to the outlets of the first and second trim valves, and may supply the first fluid as the high pressure fluid to the variator switching sub-system during at least one predefined operating condition and may otherwise supply the second fluid as the high pressure fluid to the variator switching sub-system.

Abstract: An apparatus and method are disclosed for controlling fluid flow in a motor vehicle transmission. At least one friction engagement device is fluidly coupled to a first pump, and a lubrication and cooling sub-system is normally fluidly coupled to a second pump. Illustratively, when a flow rate of the fluid in the first fluid passageway is less than a threshold fluid flow rate, a temperature of the fluid is greater than a temperature threshold and a fluid flow demand is greater than a fluid flow demand threshold, fluid flow from the second pump to the lubrication and cooling sub-system is blocked and fluid supplied by the second pump is instead directed to the at least one friction engagement device such that fluid is supplied by both the first and second pumps only to the at least one friction engagement device.

Abstract: An apparatus for controlling a variator having at least one roller between two torroidal disks may include at least one actuator responsive to fluid pressure at separate high side and low side fluid inlets thereof to control torque applied by the at least one roller to the disks. First and second variator switching valves may each receive a first fluid at a first pressure and a second fluid at a second lesser pressure. The first and second variator switching valves supply the first fluid to the high side fluid inlet and the second fluid to the low side fluid inlet during two of four different operational states together defined by the variator switching valves, and supply the second fluid to the high side fluid inlet and the first fluid to the low side fluid inlet during each of the remaining two of the four different operational states.

Abstract: An electro-hydraulic control system is provided for a transmission with a torque-transmitting mechanism that has a dual area piston. When pressurized fluid is provided to a first of the two piston areas, the position of a spring-biased shift valve controls whether pressurized fluid communicates with the second piston area. A solenoid valve in fluid communication with the shift valve is energizable to direct pressurized fluid to the shift valve to urge the shift valve to the unstroked position to which the spring also urges. The shift valve may also be urged by pressurized fluid to the stroked position, but only when the solenoid valve is not energized. The spring maintains the shift valve in the unstroked position when pressurized fluid is directed to the shift valve to act both against and with the spring.

Abstract: An electro-hydraulic control system is provided that utilizes a shift solenoid and shift valve to multiplex a single pressure control solenoid to control both modulation of a main pressure regulator valve and retarder operation (fill and pressure).

Abstract: A variator fault detection system for a continuously variable transmission is incorporated into a hydraulic control circuit that controls fluid pressure applied to a variator of the continuously variable transmission. The hydraulic control circuit for the variator includes a number of electrically-controlled shift valves and pressure control valves. Sensing devices are multiplexed to these valves to detect a number of different possible fault states relating to the variator shift valves and the variator pressure control valves.

Abstract: A fast valve actuation system for an automatic vehicle transmission includes a pair of spring-biased shift valves. Solenoids control the application of pressurized hydraulic fluid to the head of each of the shift valves. Each shift valve has at least one port that is coupled to a fluid chamber of a torque transferring mechanism of an automatic transmission. The position of each of the shift valves determines whether its ports are connected with fluid pressure. Fluid passages connect the head of each shift valve to the spring pocket of the other shift valve.

Abstract: A fail-to-neutral diagnostic technique for a transmission that includes a variator may include monitoring a state of a pressure differential valve fluidly coupled to a high side pressure applied to at least one actuator coupled to at least one corresponding roller of the variator and also fluidly coupled to a low side pressure applied to the at least one actuator, determining from the state of the pressure differential valve a variator torque sign corresponding to whether torque transferred by the at least one roller is positive or negative, determining an expected variator torque sign based on current operating conditions of the transmission, and commanding the transmission to a true neutral condition if the determined variator torque sign is different from the expected variator torque sign.

Abstract: A fault diagnostic method for an automatic transmission may include monitoring an operating state of a trim system configured to selectively supply clutch engagement pressure and exhaust to at least one clutch control valve, determining an expected operating state of the trim system based on current operating conditions of the transmission, and generating a fault signal if the monitored operating state of the trim system is different from the expected operating state of the trim system.

Abstract: An apparatus for multiplexing gear engagement control in an automatic transmission is provided. At least two friction engagement devices are configured to selectively engage and disengage a different gear ratio of the transmission. A trim system is configured to selectively supply engagement and disengagement pressures to at least one fluid passageway. A first control valve is fluidly coupled directly to the at least one fluid passageway and directly to each of the at least two friction engagement devices. The first control valve is configured to selectively route the engagement and disengagement pressures through the first control valve directly to the at least two friction devices.

Abstract: A variator lockout valve system for a continuously variable transmission includes a pair of shift valves. Each shift valve has at least one port that is fluidly coupled to a variator of the continuously variable transmission. Electro-hydraulic actuators control the position of each of the shift valves. When the shift valves are in one position, pressure control valves supply fluid pressure to the variator. If one of the shift valves is in another position, one of the pressure control valves is blocked from supplying fluid pressure to the variator.

Abstract: A plugged filter detection system includes a valve housed within a cavity defining an initial inlet for receiving fluid at an inlet pressure before fluid enters a filter, a final inlet for receiving fluid at an outlet pressure after the fluid exits the filter, and a switch port for directing fluid to a switch to activate the switch. The inlet pressure biases the valve in a first direction and the outlet pressure biases the valve in a second direction substantially opposing the first direction. The valve is movable from a first position to a second position to unblock the switch port, thereby allowing the switch to be activated when inlet pressure is greater than outlet pressure. A spring preferably biases the valve in the second direction, such that inlet pressure must be greater than outlet pressure by at least the spring constant to allow switch activation.

Abstract: An electro-hydraulic control system is provided for a transmission with a torque-transmitting mechanism that has a dual area piston. When pressurized fluid is provided to a first of the two piston areas, the position of a spring-biased shift valve controls whether pressurized fluid communicates with the second piston area. A solenoid valve in fluid communication with the shift valve is energizable to direct pressurized fluid to the shift valve to urge the shift valve to the unstroked position to which the spring also urges. The shift valve may also be urged by pressurized fluid to the stroked position, but only when the solenoid valve is not energized. The spring maintains the shift valve in the unstroked position when pressurized fluid is directed to the shift valve to act both against and with the spring.

Abstract: An electro-hydraulic control mechanism for use with a multi-speed transmission includes a pair of logic valves, which are manipulated during the ratio interchanges and the ratio establishment by aiding in the distribution of fluid pressure from a plurality of trim valves. The logic valves are retained in specific drive ranges in the event of electrical discontinuance.