Abstract: A continuously variable transmission pump limited stop controls system includes a continuously variable transmission (CVT) including primary and secondary variator pulleys. The primary and the secondary variator pulley each have a mating half with a conical face, defining a variable-width gap between each pulley and its mating half. A flexible member is positioned within the gap and is movable on the conical faces defining a CVT ratio. A secondary pulley valve controls flow of a fluid to the secondary variator pulley. A secondary pulley pressure boost system identifies if a rapid stop event is occurring and issues a command to fully open the secondary pulley valve during the rapid stop event. As the CVT ratio reaches a predetermined threshold of a desired relaunch ratio during the rapid stop event, an engine speed request is issued to an engine connected to the CVT to increase engine speed.

Abstract: A method and apparatus for controlling a continuously variable transmission (CVT) of a powertrain system includes determining a target clamping pressure and an actual clamping pressure, and determining a proportional correction term and an integral correction term based upon the target clamping pressure and the actual clamping pressure. An adapt correction term is determined based upon the target clamping pressure and a temperature of the CVT. A commanded clamping pressure for controlling the CVT is determined based upon the proportional correction term, the integral correction term and the adapt correction term. A pressure command is employed to drive an actuator of a moveable sheave of a pulley of a variator of the CVT based upon the commanded clamping pressure.

Abstract: A continuously variable transmission (CVT) for use with a torque generating mechanism includes an input member connectable to the torque generating mechanism, an output member, a variator assembly, and a controller. The controller is programmed to control a change-of-mind shift of the CVT requesting a transition from an initially-requested shift to a next-requested shift before completion of the initially-requested shift. Additionally, the controller is programmed to execute a method by detecting the change-of-mind shift, determining an acceleration profile of the input member for the change-of-mind shift using a calibration map indexed by a starting and target ratio of the variator assembly, and calculating a required ratio of the input and output pulleys using the acceleration profile. The controller then commands a clamping pressure of the variator assembly to thereby achieve the calculated required ratio. A vehicle includes an engine and the CVT noted above.

Abstract: An apparatus for ratio control of a continuously variable transmission includes a driver commanded ratio unit outputting a signal defining a commanded ratio. A clamp control portion is in communication with the driver commanded ratio unit. The clamp control portion includes: a ratio limits and override ring selecting a ratio matching the commanded ratio from an executable functions having stored ratio code data; a screening monitor continuously receiving output from the executable functions and using an input from a vehicle speed signal to compute minimum and maximum ratio limits for the ratio selected by the ratio limits and override ring; and a ratio control execution ring in communication with the screening monitor. The ratio control execution ring calculates a range of pressures allowed for operation of both primary and secondary pulleys of the continuously variable transmission.

Abstract: A continuously variable transmission (CVT) and a method is provided for CVT variator gross slip detection includes determining if a difference between a commanded variator speed ratio and a real variator speed ratio is greater than a predetermined variator speed ratio threshold, and then determining if a variator rate of change ratio is outside of predetermined variator rate of change ratio limits. Further, the method includes determining if a real torque capacity ratio is greater than a predetermined torque capacity ratio threshold, and performing at least one remedial action when the variator rate of change ratio is outside of predetermined variator rate of change ratio limits, and the real torque capacity ratio is greater than the predetermined torque capacity ratio threshold when the difference between the commanded variator speed ratio and the real variator speed ratio is greater than the predetermined variator speed ratio threshold.

Abstract: A target module determines a target ratio between a speed of an input shaft and a speed of an output shaft of a continuously variable transmission (CVT) based on an accelerator pedal position. A maximum rate of change (ROC) module determines a maximum ROC of the target ratio. A switching valve control module, based on a comparison of the maximum ROC and a ROC of the target ratio, selectively actuates a switching valve of the CVT one of (i) from a closed position to an open position and (ii) from the open position to the closed position. The switching valve prevents transmission fluid flow through a flow path between a transmission fluid pump and a pressure regulator valve of the CVT when the switching valve is in the closed position. The switching valve allows transmission fluid flow through the flow path when the switching valve is in the open position.

Abstract: A controller for a vehicle propulsion system that includes a prime mover, a transmission connected to the prime mover to receive input torque on an input shaft and to convert the input torque to an output torque on an output shaft, a transmission input shaft speed sensor, and a transmission output shaft speed sensor. The controller provides a gear ratio value that is based upon a signal indicating an operating condition of the transmission other than a signal from the transmission input shaft speed sensor and the transmission output shaft sensor.

Abstract: A continuously variable transmission (CVT) includes an input member, an output member, a variator assembly having a primary variator pulley operable for receiving an input torque via the input member, a secondary variator pulley operable for transmitting an output torque via the output member, and an endless rotatable drive element in frictional engagement with the primary and secondary variator pulleys, first and second speed sensors operable for measuring a respective rotational speed of the primary and secondary variator pulleys, and a controller. The controller executes a method to detect gross slip of the endless rotatable drive element with respect to the primary and secondary variator pulleys using the measured rotational speeds, and in response to the detected gross slip, to request a reduction in the input torque by a calculated amount over a calibrated duration until a level of the detected gross slip reaches a calibrated slip level.

Abstract: A clutch latching system is provided for latching and draining a torque transmitting mechanism. The latching clutch control system may include a latching valve, a release valve, and an accumulator. The clutch latching system may include a clutch feed channel configured to provide hydraulic fluid from a pressurized source to a torque transmitting device when the torque transmitting device is engaged and the engine is running. A latching valve connects the clutch feed channel to the torque transmitting device. The latching valve is configured to selectively trap pressurized hydraulic fluid within the torque transmitting device. A hydraulic pressure storage circuit configured to selectively provide pressurized hydraulic fluid to the latching valve to unlatch the latching valve. A multiple speed transmission is also provided.

Abstract: A target module determines a target ratio between a speed of an input shaft and a speed of an output shaft of a continuously variable transmission (CVT) based on an accelerator pedal position. A maximum rate of change (ROC) module determines a maximum ROC of the target ratio. A switching valve control module, based on a comparison of the maximum ROC and a ROC of the target ratio, selectively actuates a switching valve of the CVT one of (i) from a closed position to an open position and (ii) from the open position to the closed position. The switching valve prevents transmission fluid flow through a flow path between a transmission fluid pump and a pressure regulator valve of the CVT when the switching valve is in the closed position. The switching valve allows transmission fluid flow through the flow path when the switching valve is in the open position.

Abstract: A powertrain system including an internal combustion engine rotatably coupled to a variator of a continuously variable transmission (CVT) is described. A method for controlling the CVT includes determining an actual speed ratio, a desired speed ratio and a commanded speed ratio. A total speed ratio change rate is determined based upon the actual speed ratio, the desired speed ratio and the commanded speed ratio, and a commanded speed ratio trajectory is determined based upon the desired speed ratio and the commanded speed ratio. A ratio change coefficient and a force ratio factor are determined based upon the commanded speed ratio trajectory, and a shift force is determined based upon the total speed ratio change rate and the ratio change coefficient. A primary pulley force and a secondary pulley force for the CVT are controlled based upon the shift force and the force ratio factor.

Abstract: A continuously variable transmission (CVT) for use with a torque generating mechanism includes an input member connectable to the torque generating mechanism, an output member, a variator assembly, and a controller. The controller is programmed to control a change-of-mind shift of the CVT requesting a transition from an initially-requested shift to a next-requested shift before completion of the initially-requested shift. Additionally, the controller is programmed to execute a method by detecting the change-of-mind shift, determining an acceleration profile of the input member for the change-of-mind shift using a calibration map indexed by a starting and target ratio of the variator assembly, and calculating a required ratio of the input and output pulleys using the acceleration profile. The controller then commands a clamping pressure of the variator assembly to thereby achieve the calculated required ratio. A vehicle includes an engine and the CVT noted above.

Abstract: A powertrain system including an internal combustion engine rotatably coupled to a variator of a continuously variable transmission (CVT) is described. A method for controlling the CVT includes determining a first speed ratio change rate based upon a desired speed ratio and a commanded speed ratio, and determining a commanded speed ratio trajectory based upon the first speed ratio change rate, an actual speed ratio and a commanded speed ratio. A ratio change coefficient and a force ratio factor are determined based upon the commanded speed ratio trajectory. A shift force is determined based upon the ratio change coefficient and a total speed ratio change rate. A primary pulley pressure and a secondary pulley pressure for the CVT are controlled based upon the shift force and the force ratio factor.

Abstract: A continuously variable transmission (CVT) includes an input member, an output member, a variator assembly having a primary variator pulley operable for receiving an input torque via the input member, a secondary variator pulley operable for transmitting an output torque via the output member, and an endless rotatable drive element in frictional engagement with the primary and secondary variator pulleys, first and second speed sensors operable for measuring a respective rotational speed of the primary and secondary variator pulleys, and a controller. The controller executes a method to detect gross slip of the endless rotatable drive element with respect to the primary and secondary variator pulleys using the measured rotational speeds, and in response to the detected gross slip, to request a reduction in the input torque by a calculated amount over a calibrated duration until a level of the detected gross slip reaches a calibrated slip level.

Abstract: A continuously variable transmission (CVT) including a hydraulically-controllable variator is described. A method for controlling the CVT includes detecting a transient event causing a commanded change in a speed ratio of the variator and disabling feedback control of hydraulic pressure to the variator during the transient event. A target pressure that achieves the commanded change in the speed ratio of the variator is determined, and a pressure trajectory is determined based upon the target pressure. A feed-forward control of the hydraulic pressure to the variator is executed in response to the pressure trajectory during the transient event.

Abstract: A powertrain system including an internal combustion engine rotatably coupled to a variator of a continuously variable transmission (CVT) is described. A method for controlling the CVT includes determining a first speed ratio change rate based upon a desired speed ratio and a commanded speed ratio, and determining a commanded speed ratio trajectory based upon the first speed ratio change rate, an actual speed ratio and a commanded speed ratio. A ratio change coefficient and a force ratio factor are determined based upon the commanded speed ratio trajectory. A shift force is determined based upon the ratio change coefficient and a total speed ratio change rate. A primary pulley pressure and a secondary pulley pressure for the CVT are controlled based upon the shift force and the force ratio factor.

Abstract: A powertrain system including an internal combustion engine rotatably coupled to a variator of a continuously variable transmission (CVT) is described. A method for controlling the CVT includes determining an actual speed ratio, a desired speed ratio and a commanded speed ratio. A total speed ratio change rate is determined based upon the actual speed ratio, the desired speed ratio and the commanded speed ratio, and a commanded speed ratio trajectory is determined based upon the desired speed ratio and the commanded speed ratio. A ratio change coefficient and a force ratio factor are determined based upon the commanded speed ratio trajectory, and a shift force is determined based upon the total speed ratio change rate and the ratio change coefficient. A primary pulley force and a secondary pulley force for the CVT are controlled based upon the shift force and the force ratio factor.

Abstract: A powertrain system including a continuously variable transmission (CVT) is described. A method for controlling the CVT includes determining a target clamping pressure and an actual clamping pressure, and determining a proportional correction term and an integral correction term based upon the target clamping pressure and the actual clamping pressure. An adapt correction term is determined based upon the target clamping pressure and a temperature of the CVT. A commanded clamping pressure for controlling the CVT is determined based upon the proportional correction term, the integral correction term and the adapt correction term. A pressure command is employed to drive an actuator of a moveable sheave of a pulley of a variator of the CVT based upon the commanded clamping pressure.

Abstract: A powertrain system including an internal combustion engine rotatably coupled to a variator of a continuously variable transmission (CVT) is described. A method for controlling the CVT includes determining a desired variator speed ratio in response to a command to increase output power from the powertrain system and executing a step-down shift in the CVT based upon the desired variator speed ratio, the step-down shift. The step-down shift includes determining a preferred CVT input acceleration profile based upon the desired variator speed ratio, a present variator speed ratio, and a preferred shift time and synchronizing the preferred CVT input acceleration profile with engine torque. A change rate for the variator speed ratio is based upon the preferred CVT input acceleration profile, and the CVT is controlled in response to the change rate for the variator speed ratio and the desired variator speed ratio.

Abstract: A system is provided for latching and draining a torque transmitting device. The system may include a clutch feed channel having an inlet portion and a clutch portion. The inlet portion is configured to provide hydraulic fluid from a pressurized source to the clutch portion. The clutch portion is configured to provide hydraulic fluid to a torque transmitting device. An inlet valve connects the inlet portion of the clutch feed channel to the clutch portion of the clutch feed channel. The inlet valve is configured to open to allow the hydraulic fluid to flow from the inlet portion to the clutch portion when the torque transmitting device is engaged. The inlet valve is configured to close and to trap hydraulic fluid within the torque transmitting device when the torque transmitting device is not actively pressurized. A multispeed transmission is also provided.