Gm Global Technolgoy Operations, Inc.

Brian James Pellerito

Todd Thor

David W Wright

Craig A Brunstetter

Joel H Gunderson

Craig J Hawkins

Dara Monajemi

Brian H Fiore

Greg J Perantoni

Cheol W Kim

Michael Chernyak

Emmanuel V Yabes

Lucius B Allen

A transmission control system of a vehicle includes an estimated acceleration module and a pressure control module. The estimated acceleration module determines an estimated longitudinal acceleration of the vehicle based on a force at axles of the vehicle corresponding to engine torque, a braking force imposed by mechanical brakes of the vehicle, an aerodynamic drag force of the vehicle, and a road load force imposed on the vehicle by contact between tires of the vehicle and a road surface. The pressure control module, when a measured longitudinal acceleration of the vehicle is negative and the estimated longitudinal acceleration is greater than the measured longitudinal acceleration of the vehicle, adjusts transmission fluid pressure applied to one or more clutches of the transmission and shifts the transmission to neutral.

Vehicle deceleration control systems and methods

A method for monitoring a fixed-gear transmission includes deriving a node speed relationship for each of the planetary gear sets based upon a center distance and a gear ratio and determining equivalent speed parameters for nodes of the planetary gear sets based upon a transmission input speed state, an intermediate node speed state and a transmission output speed state. A clutch slip speed relationship is determined for each of the clutches based upon the node speed relationships for the planetary gear sets and the equivalent speed parameters for nodes of the planetary gear sets. Rotational speed sensors monitor the input transmission speed, the intermediate node speed and the transmission output speed. A clutch slip speed for each of the clutches is determined based upon the respective clutch slip speed relationship and the monitored input transmission speed, the monitored intermediate node speed and the monitored transmission output speed.

Transmission node speed monitoring

A method of controlling a vehicle includes signaling a transmission to shift into a first gear ratio and sensing a current gear ratio of the transmission after signaling the transmission to shift into the first gear ratio. The method further includes implementing a diagnostic transmission shift control strategy to override a normal transmission shift control strategy when the current sensed gear ratio is not equal to the requested first gear ratio to verify proper functionality of a mode control valve that is responsible for shifting the transmission into the first gear ratio.

Method of controlling a vehicle during an auxiliary pump failure

A method of controlling a clutch-to-clutch transmission. The method includes detecting transmission slip speed that exceeds a predetermined amount for a predetermined time period. Based on the detecting, a shift of a gear ratio of the transmission is forced. When this method is implemented in a vehicle, loss of driver control of the vehicle can be prevented in the event of a non-commanded neutral condition in the transmission.

Resolving a non-commanded neutral state in a clutch-to-clutch transmission

A vehicle including a transmission having a plurality of clutches for providing a plurality of speed ratios. A control module of the vehicle detects a possible tie-up of at least two of the clutches. Based on the detecting, the control module releases one of the possibly tied-up clutches. After the release, the control module determines whether a tie-up condition occurred. Based on the determining, the control module reapplies pressure to the released clutch. Loss of driver control of the vehicle thus can be prevented in the event of clutch tie-up.

Resolving tie-up in a clutch-to-clutch transmission

A method for detecting a clutch fault of an automatic transmission includes determining a current clutch energy density of a clutch during a range shift and comparing the current clutch energy density to a first energy density threshold. A diagnostic alert is activated if the current clutch energy density exceeds the first energy density threshold.

Clutch fault detection

In a powertrain including an internal combustion engine coupled to a transmission, engine ignition timing is controlled to minimize the impact of severe mechanical load disturbances, such as resulting from transmission shifts into or out of park or neutral positions, wherein the ignition timing is gradually varied to match the characteristic of the load disturbance being compensated, and variation in ignition timing is delayed in accord with transmission responsiveness, such as indicated by transmission temperature, until the disturbance is actually impacting powertrain mechanical load. Control stability is improved by temporarily suspending potentially duplicate control operations until the mechanical load disturbance has been compensated.

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Ortonville, MI, United States of America

Brian James Pellerito