Gm Global Technolgoy Operations, Inc.

Robert L Williams

Matthew D Whitton

Mark A Schang

Steven Patrick Moorman

Christopher Jay Weingartz

Craig J Hawkins

Harinath Atmaram

Kurt J Mitts

Cheol W Kim

David Szpara

Daniel Deras

Mark A Yacoub

Shashikanth Rangaraju

A method of controlling a transmission includes estimating an expected coefficient of friction of the clutch, estimating a value of an expected torque required to maintain a constant slip of the clutch for a current input torque applied to the transmission, and determining a value of an actual torque applied to the clutch to maintain the constant slip of the clutch at the current input torque. An actual coefficient of friction of the clutch is calculated by dividing the actual torque applied to the clutch by the expected torque applied to the clutch, and multiplying that quotient by the expected coefficient of friction of the clutch. A feed forward torque command is then adjusted based upon the actual coefficient of friction of the clutch to define a revised value of the feed forward torque command, which may then be used to control the clutch for various control operations.

Real time compensation of changing friction characteristics of a clutch in a transmission

A method of controlling engine crankshaft torque on a vehicle requests crankshaft torque modification using multiple types of torque actuators prior to and during a single commanded shift, such as an upshift. Appropriate levels of torque modification for the request, as well as appropriate times to make determinations regarding actuator type and make crankshaft torque reduction requests are determined in light of timing of key events during the shift.

Method for crankshaft torque modification during transmission shifts using multiple torque actuators and control system for same

A vehicle includes an engine, transmission, and controller. The transmission includes a clutch pack, a clutch piston, and a position sensor. The sensor measures a changing magnetic field with respect to the piston, and encodes the measured magnetic field as a raw position signal. The controller receives the raw position signal and processes the raw position signal through a signal processing module to generate a filtered signal attenuating signal noise in the position signal. The controller determines a commanded position of the piston, and calculates separate proportional (P), derivative (D), and integral (I) control terms using the commanded position and filtered position signal. The controller also calculates a feed-forward control term using the commanded position, and a required flow rate for actuating the clutch pack as a function of the PID terms and the feed-forward commanded position term. The controller actuates the clutch pack using the commanded flow rate.

Closed-loop clutch control using a filtered piston position signal

A control system for a transmission includes a memory module, a position module, an error module, an integral module, and an adjustment module. The memory stores a control value as a function of clutch torque. The position module controls a position of a clutch based on the control value. The error module periodically determines a slip speed error based on a difference between a target slip speed and an estimated slip speed of the clutch. The integral module periodically determines an integral of the slip speed error. The adjustment module adjusts the control value based on the integral. A method for controlling a transmission is also provided.

System and method for adaptive transmission clutch torque control

A clutch control system for a vehicle includes a shift command module and an offgoing clutch control module. The shift command module commands an upshift of a clutch-to-clutch transmission when an engine torque is less than a predetermined negative torque. The offgoing clutch control module increases an offgoing clutch pressure above a predetermined apply pressure in response to the command. An offgoing clutch is fully engaged when the offgoing clutch pressure is greater than the predetermined apply pressure.

Negative torque upshift offgoing clutch control systems and methods

A control system includes a shift stage determination module and a clutch control module. The shift stage determination module determines a duration of a first power-on downshift when a second power-on downshift is requested, where a power-on downshift is a downshift of a transmission that occurs when an accelerator pedal is depressed. The clutch control module completes the first power-on downshift and selectively starts controlling the second power-on downshift before the first power-on downshift ends.

Quick skip-at-sync control system and method

A transmission shift control system includes a transmission shift control module that executes an upshift or a closed-throttle downshift, a shift stage determination module, and a clutch control module. The stage determination module determines a stage of the upshift or the closed throttle downshift when a downshift is requested. The clutch control module determines a downshift type based on the stage of the upshift or the closed throttle downshift and selectively executes a downshift before the upshift or the closed throttle downshift is completed.

Shift control systems and methods for an automatic transmission

The present invention provides a method and apparatus for mathematically calculating an optimal transmission input torque value for the inertia phase and the torque phase of a ratio change. Engine output is then altered by an amount necessary to change the actual value of the transmission input torque to the calculated optimal value of transmission input torque. The timing of the clutch elements during the power-on skip through neutral downshift is established by calculating delay periods for the off-going and on-coming clutches such that a predetermined desired shift time is met. The power-on skip through neutral downshift is thereafter adaptively controlled so that aberrations are diagnosed and corrected during subsequent downshifts. The invention is carried out by monitoring engine and/or transmission characteristics including input speed, output speed and shift duration during a downshift and identifying departures from acceptable patterns. Each type of departure calls for a particular remedy, and a suitable adjustment is calculated thereafter implemented by changing one or more initial conditions for the next shift of the same type.

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Holly, MI, United States of America

Robert L Williams