The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 04, 1994
Filed:
May. 25, 1993
Fumiaki Baba, Higashi-Hiroshima, JP;
Masahito Kitada, Hiroshima, JP;
Mazda Motor Corporation, Hiroshima, JP;
Abstract
A shift control system for an automatic transmission includes a shift gear mechanism for providing a plurality of shift stages of different speed ratios, a plurality of frictional elements, a first valve for controlling a hydraulic fluid supply, a second valve provided in a hydraulic release line to control hydraulic fluid release, a first frictional element included in the plurality of the frictional elements, a second frictional element included in the plurality of the frictional elements, a piston provided in the second frictional element, a timing valve for controlling a supply timing of the hydraulic pressure for the releasing chamber of the second frictional element in response to actuating hydraulic pressure introduced into the first frictional element, an oil temperature detecting device, and a start detecting device for detecting start of engaging operation of the first frictional element. A shift judging device for judging whether or not a shift command in the control unit is made to a specific shift stage in which the first frictional element is engaged and the second frictional element, is released. A shift control mode switching device switches between a first shift control mode and a second shift control mode, the shift control mode switching device selecting the first shift control mode when the temperature of the hydraulic fluid is relatively high, and selecting the second shift control mode when the temperature of the hydraulic fluid is relatively low. Torque shock and engine speed racing can be avoided through the shift operation.