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. 15, 1991
Filed:
Sep. 28, 1989
Takuji Fujiwara, Hiroshima, JP;
Hiroshi Yoshimura, Hiroshima, JP;
Kozo Ishii, Hiroshima, JP;
Kazuo Takemoto, Hiroshima, JP;
Mazda Motor Corporation, Shinchi, JP;
Abstract
An automatic transmission of a vehicle has a transmission gear mechanism having at least a lower gear-speed and a higher gear-speed, and first and second friction coupling members which are applied or released by hydraulic pressures applied thereto. The first friction coupling member is kept applied when the transmission is in the lower gear-speed and the second friction coupling member is kept applied when the transmission is in the higher gear-speed. A control system for the automatic transmission has a hydraulic control circuit which controls the hydraulic pressure applied to the respective friction coupling members, thereby changing the condition of application of the friction coupling members and causing the automatic transmission to shift, and a control unit which controls the hydraulic control circuit according to the running condition of the vehicle. The control unit normally makes lower the hydraulic pressure applied to the second friction coupling member when it is kept applied than that applied to the first friction coupling member when it is kept applied by a predetermined value. When the vehicle is starting with the transmission in the higher gear-speed, the control unit inhibits itself from making lower the hydraulic pressure applied to the second friction coupling member when it is kept applied than that applied to the first friction coupling member when it is kept applied.