Improving Automatic Transmission Shift Quality by Feedback Control with a Turbine Speed Sensor

Paper #:
  • 911938

Published:
  • 1991-09-01
Citation:
Narita, Y., "Improving Automatic Transmission Shift Quality by Feedback Control with a Turbine Speed Sensor," SAE Technical Paper 911938, 1991, https://doi.org/10.4271/911938.
Author(s):
Pages:
10
Abstract:
Shift quality in automatic transmissions is greatly affected by deterioration and variation of engine torque, hydraulic pressure control valves, friction elements and other factors. This paper presents a new control system that improves shift quality by using a turbine speed sensor to monitor the shift duration, particularly the duration of the inertia phase.The use of feedback control to vary the line pressure according to the shift duration makes it possible to eliminate the effects of aging and component variability. Other factors affecting shift quality, such as atmospheric pressure, road gradient and additional engine load from the air conditioner and alternator, were also examined, and it was found that their effects can be virtually eliminated through feedback control. The inertia phase usually becomes shorter as the engaging clutch capacity increases. However, an extremely small torque capacity can cause a short inertia phase, resulting in a large torque disturbance. This problem is avoided by measuring the interval from the initiation of the shift command to the completion of the inertia phase, this making it possible to distinguish between small and large torque capacity conditions.Power-off upshifts, resulting from abrupt throttle closing, can cause shock and chatter. These disturbances are eliminated through synchronized clutch engagement, achieved by sensing the speed ratio between the turbine and output shaft.Power-on downshifts when going downhill pose a critical condition for clutch slip. Friction elements are protected from damage in this system by controlling the timing and capacity of the engaging and releasing elements.
Access
Now
SAE MOBILUS Subscriber? You may already have access.
Buy
Select
Price
List
Download
$27.00
Mail
$27.00
Members save up to 40% off list price.
Share
HTML for Linking to Page
Page URL

Related Items

Training / Education
2008-08-26
Training / Education
2007-03-01
Technical Paper / Journal Article
2010-09-28
Training / Education
2005-11-15
Technical Paper / Journal Article
2011-04-12
Technical Paper / Journal Article
2011-04-12
Article
2017-03-13
Training / Education
2018-05-14