Gm Global Technolgoy Operations, Inc.

Sindu Sebastian

Ronald F Lochocki, Jr

Min K Kim

David W Wright

Joseph J Page

A transmission assembly for a vehicle includes a transmission and a controller. The transmission includes an input member, at least one clutch and gear set, and an output member. The input member receives an input torque from an engine. The output member receives an output torque from the clutch and gear set(s). The clutch and gear set(s) connect to the input member and establish a plurality of operating states including a neutral idle (NI) state. A designated NI clutch is selectively actuated to enter the NI state when the transmission is in a drive state and the vehicle is stationary. The controller calculates a reference slip error as a function of engine and turbine speed, and detects when the designated NI clutch is exhausting fluid while operating in the NI state using a function of the reference slip error. A control action executes when the exhausting NI clutch is detected.

Detection of an exhausting clutch in a neutral idle-equipped transmission

A vehicle includes an engine, a torque converter, a transmission, and a controller. The transmission has an input member connected to a turbine of the torque converter. The transmission includes a neutral idle (NI) state and a designated NI clutch actuated to enter the NI state. The controller calculates a reference slip error as a function of engine speed and turbine speed, detects when the designated NI clutch is exhausting while operating in the NI state as a function of the reference slip error, and executes a control action when the exhausting NI clutch is detected. A method includes measuring engine and turbine speed, calculating the reference slip error value as a function of the engine and turbine speeds, detecting when the designated NI clutch is exhausting while operating in the NI state using the reference slip error, and executing a control action when the exhausting NI clutch is detected.

A transmission includes a plurality of clutches that are selectively engageable alone or in combination with each other to establish a plurality of forward drive modes, wherein one of the clutches is configured as a neutral idle (NI) clutch that is selectively actuated to shift the transmission into an NI state, and a controller. The controller is adapted to shift the transmission from a forward drive mode into the NI state during a coast-down maneuver prior to the transmission reaching a zero output speed. A method of shifting the transmission into the NI state includes determining the presence of a predetermined one of the forward drive modes using the controller, and using the controller to actuate a designated one of the clutches as an NI clutch to enter the NI state during the forward drive mode, during a coast-down maneuver, and prior to the transmission reaching a zero output speed.

Method and apparatus for entering neutral idle from a forward drive mode

A vehicle includes an engine, torque converter, transmission, accumulator, sensor, and controller. The engine is automatically restarted in response to a start signal during an engine auto-start event. The transmission has a calibrated line pressure and a plurality (n) of clutches. The (n) clutches are engaged to execute the engine auto-start event. The accumulator delivers fluid under pressure to the transmission in response to the start signal. The controller controls (n&#x2212;1) of the plurality (n) of clutches to the calibrated line pressure in response to detecting the start signal. The controller also modifies clutch fill parameters which control a fill sequence of the remaining clutch, i.e., the designated control clutch, as a function of a deviation of the measured turbine speed from a theoretical no-slip turbine speed. A system includes the transmission, sensor, accumulator, and controller. A method for controlling the designated clutch is also disclosed.

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Raleigh, NC, United States of America

Sindu Sebastian