Gm Global Technolgoy Operations, Inc.

David H Vu

Xuefeng Tim Tao

Christopher Jay Weingartz

Jeryl McIver

Steven Patrick Moorman

Craig J Hawkins

Matthew Kempeinen

Jayson S Schwalm

Pratap Atchutha Naick

A powertrain system including an internal combustion engine rotatably coupled to a continuously variable transmission (CVT) is described. A method for controlling the CVT includes determining minimum and maximum CVT input speeds in response to an accelerator pedal position, and monitoring vehicle speed and a CVT input speed. A target CVT input acceleration rate is determined based upon the vehicle speed, and a desired speed ratio is determined that is responsive to the target CVT input acceleration rate. The CVT is controlled based upon the desired speed ratio.

Method and apparatus to control a continuously variable transmission

A method for learning the bite point of a position-controlled clutch in a vehicle having an engine and a transmission includes commanding an engagement of a clutch fork via a controller when the transmission is in park and the engine is idling. The method also includes controlling an apply position of the clutch via the controller, calculating a clutch torque capacity of the clutch, and measuring the apply position via a position sensor. The apply position is recorded as the clutch bite point when the calculated clutch torque capacity equals a calibrated clutch torque capacity. The transmission is then controlled using the recorded clutch bite point. A system includes the transmission, input clutches, and a controller configured to execute the method. A vehicle includes an engine, the transmission, the position-controlled input clutch, and the controller, as well as a clutch position sensor.

Transmission system with clutch bite point learning logic

A vehicle includes an engine, first clutch, transmission, and controller. The transmission includes a gearbox, position sensors, and a fluid circuit. The gearbox contains a second clutch. The fluid circuit includes a pump and a flow control solenoid valve. The controller opens the valve via flow control signals to allow fluid to pass into or from the particular clutch it feeds. The controller executes steps of a method to determine an actual flow rate through the valve as the clutch moves, and also calculates a compensation scale factor as a ratio of the commanded and actual flow rates. The controller modifies the flow control signals in a subsequent clutch actuation using the compensation scale factor, such as by multiplying a commanded flow rate corresponding to the flow control signals by the compensation scale factor. A system includes rotatable members connected by a clutch, the controller, valve, and position sensor.

Adaptive control of a flow control solenoid valve

A method of identifying a synchronous position of a synchronizer actuator fork includes sensing a deceleration rate of a first shaft, when a synchronizer is positioned in a neutral position, to define a first rate of deceleration. The synchronizer is moved along the first shaft from the neutral position toward a gear with a synchronizer actuator fork. A deceleration rate of the first shaft is sensed, while the synchronizer actuator fork moves the synchronizer along the first shaft, to identify a change from the first rate of deceleration to a second rate of deceleration. The location, of the synchronizer actuator fork relative to the first shaft, at which the rate of acceleration of the first shaft changes from the first rate of deceleration to the second rate of deceleration, is identified as the synchronous position of the synchronizer actuator fork.

Method of identifying a synchronous position of a synchronizer actuator fork of a dual clutch transmission

A vehicle includes an engine, a transmission, and a controller which executes a method. The transmission includes a clutch having an actuator which applies the clutch using position-based control logic. The transmission also includes a fluid pump and a variable-force or other solenoid valve positioned downstream of the pump and upstream of the clutch. The valve outputs a flow rate (Q) for a corresponding solenoid control current (I). The controller adapts a calibrated Q vs. I characteristic table of the valve for different transmission temperatures by applying closed-loop position control signals to the actuator at the different transmission temperatures and recording a null point(s) describing the corresponding solenoid control current (I) at a zero flow rate condition. The controller calculates an offset value for solenoid control current (I) using the recorded null point(s), applies the offset value to the characteristic table, and controls the clutch using the adapted characteristic table.

Adaptive control of a flow control solenoid

A method of controlling a dual clutch transmission includes repeatedly moving a synchronizer into interlocking engagement with a first gear with an actuator fork, and repeatedly sensing a position of the actuator fork for each occurrence that the actuator fork moves the synchronizer into the interlocking engagement with the first gear. The sensed positions of the actuator fork are averaged to define a first engaged position of the actuator fork for engaging the first gear. A second engaged position at which the actuator fork couples the synchronizer to a second gear may be determined in the same manner. A neutral position may be determined by identifying the axial locations of peak acceleration of the actuator fork while moving between the first engaged position and the second engaged position. The identified axial locations are averaged to define the neutral position of the actuator fork.

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East Lansing, MI, United States of America

David H Vu