US 5,665,020 AGranted

Automatic transmission control system

AssigneeMazda Motor Corporation

InventorsShinya Kamada, Koichi Yamamoto, Tomoo Sawazaki, Hiroshi Shinozuka, Kazushi Kurokawa, Takamichi Teraoka, Masakazu Hombo, Naotaka Hirami, Yasunori Kanda, Akinobu Aoki, Tatsuhiko Iwasaki, Takeyoshi Kawa, Kenji Sawa

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Abstract

A control system for an automatic transmission having at least a friction coupling element which is coupled with a hydraulic pressure increasing by way of a leveled transitional pressure has an accumulator which discharge a high level of pressure accumulated therein into the fiction coupling element during a gear shift under the condition where the line pressure is low.

Claims26

Dependent claims

A hydraulic control system for an automatic transmission of the type having first to fourth friction coupling elements which are selectively locked and unlocked with hydraulic pressure for placing the automatic transmission into desired gears, each of said first, third and fourth friction coupling elements being provided with a single pressure chamber for receiving operating pressure for locking, and said second friction coupling element being provided with a locking pressure chamber for receiving operating pressure for locking and an unlocking pressure chamber for receiving operating pressure for unlocking, said automatic transmission control system comprising:

source pressure supplying means for supplying source pressure to said friction coupling elements;
first pressure control means for controlling said source pressure as operating pressure and supplying said controlled operating pressure to said pressure chamber of said first friction coupling element and said unlocking pressure chamber of said second friction coupling element;
second pressure control means for controlling said source pressure as operating pressure and supplying said controlled operating pressure to said pressure chamber of said third friction coupling element and said unlocking pressure chamber of said second friction coupling dement;
third pressure control means for controlling said source pressure as operating pressure and supplying said controlled operating pressure to said pressure chamber of said fourth friction coupling element and said locking pressure chamber of said second friction coupling dement;
first switching means for causing hydraulic communication of said unlocking pressure chamber of said second friction coupling element alternatively with said first pressure control means and with said second pressure control means;
and
second switching means for causing hydraulic communication alternatively between said third pressure control means and said locking pressure chamber of said second friction coupling element and between said third pressure control means said pressure chamber of said fourth friction coupling element.

4 more elements

first pressure control means for controlling said source pressure as operating pressure and supplying said controlled operating pressure to said pressure chamber of said first friction coupling element and said unlocking pressure chamber of said second friction coupling element;
second pressure control means for controlling said source pressure as operating pressure and supplying said controlled operating pressure to said pressure chamber of said third friction coupling element and said unlocking pressure chamber of said second friction coupling element;
third pressure control means for controlling said source pressure as operating pressure and supplying said controlled operating pressure to said pressure chamber of said fourth friction coupling element and said locking pressure chamber of said second friction coupling element;
first switching means for causing hydraulic communication of said unlocking pressure chamber of said second friction coupling element alternatively with said first pressure control means and with said second pressure control means;
and
second switching means for causing hydraulic communication of said second pressure control means alternatively with said pressure chamber of said third pressure control means and with said pressure chamber of said fourth friction coupling element.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/594,116Filed 30 Jan 1996 · continuation
Priority: JP 6-26124330 Sep 1994
Granted: 9 Sep 1997
Term ends: Not estimatedThe source records don’t support an estimate.

Classification12 codes

F16H 61/061
By controlling rate of change of fluid pressure: using electric control means
F16H 61/0206
For gearshift control, e.g. control functions for performing shifting or generation of shift signal: layout of electro-hydraulic control circuits,…
F16H 61/0021
Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid…
F16H 61/067
Using fluid control means: using an accumulator