Browse Publications Technical Papers 2015-36-0331
2015-09-22

Garage Shift Calibration for Automatic Transmission in Front Wheel Drive Powertrains 2015-36-0331

In order to illustrate the constant development of the automatic transmission controls area, this paper describes how the garage shift calibration works in vehicles with transverse front wheel drive powertrains.A garage shift (GS) is the turbine speed transient commanded by the shift lever movement from Park to Drive or Reverse, from Neutral to Drive or Reverse, from Drive to Reverse, from Reverse to Drive, or from Drive or Reverse to Neutral [1].A usual metric to verify the garage shift comfort is the data acquisition of the fore-aft acceleration on the seat track, but also the shift time should be considered, as well as the clutch energy and the repeatability of the shift feeling for different temperatures and engine idle speed levels.This paper demonstrates the transmission calibration strategies to determine a sensitive and a non-sensitive garage shift and its interactions with the engine calibration.Many factors may affect the garage shift calibration, like hardware controls (software and calibration), hydraulic system (fluid and actuators), clutches (design and friction material) step ratios, and non-transmission factors such as idle control and engine torque signal accuracy [2]. The vehicle’s sensitivity to torsional driveline inputs and the powertrain mounts configuration also influence the shift quality perception.

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