Back-up device for an electronic control system of an automatic transmission
This patent describes an electronic control system of an automatic transmission in an automotive vehicle, the automatic transmission having at least two speed ratios including a first speed ratio for lower speed running of the vehicle and a second speed ratio for higher speed running of the vehicle, and forming part of a power transmission system connected between an engine of the vehicle and driving wheels of the vehicle. The electronic control system includes a first frictionally engaging element hydraulically actuatable for establishing the first speed ratio, and second frictionally engaging element hydraulically actuatable for establishing the second speed ratio, and operating fluid source, and selector valve means for selectively connecting the operating fluid source to the first and second, frictionally engaging elements. The selector valve means is adapted to selectively assume a first position for establishing the first speed ratio and a second position for establishing the second speed ratio. An electromagnetic valve means drives the selector valve means to select the first position or the second position, and an electronic control means selectively energizes and deenergizes the electromagnetic valve means in accordance with a predetermined gear shifting manner responsive to an electrical signal indicative of the speed of the vehicle and an electrical signal indicative of output from the engine. The improvement described here comprises a back-up device comprising vehicle speed sensing means for generating an output signal having a value thereof increasing as the speed of the vehicle increases, and control means for causing the selector valve means to assume the second position irrespective of the operation of the electromagnetic valve means, when the value of the output signal from the vehicle speed sensing means exceeds a predetermined value.
- Assignee:
- Honda Giken Kogyo Kabushiki Kaisha, Tokyo
- Patent Number(s):
- US 4628772
- OSTI ID:
- 6859302
- Resource Relation:
- Patent File Date: Filed date 13 Sep 1985
- Country of Publication:
- United States
- Language:
- English
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