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:
Dec. 05, 1995
Filed:
Jun. 02, 1994
Masahiko Ando, Okazaki, JP;
Akira Fukatsu, Anjo, JP;
Yoshihisa Yamamoto, Anjo, JP;
Mamoru Niimi, Hanada, JP;
Kunihiro Iwatsuki, Toyota, JP;
Hiromichi Kimura, Okazaki, JP;
Hidehiro Oba, Aichi, JP;
Yasuo Hojo, Nagoya, JP;
Masato Kaigawa, Toyota, JP;
Aisin AW Co., Ltd., both of, JP;
Toyota Jidosha Kabushiki Kaisha, both of, JP;
Abstract
A hydraulic control for an automatic transmission is composed of a gear shift mechanism having first and second frictional engagement elements, a hydraulic control unit for the engagement elements, and an electronic control unit for the hydraulic control unit. The first element is engaged to achieve a first speed stage and the second element is engaged to achieve a second speed stage faster than and closest to the first speed stage. The hydraulic control unit has a first directional control valve for switching the feeding and discharge of hydraulic pressure between the first and second engagement elements, responsive to a first solenoid signal from the electronic control unit. A second directional control valve is adapted to be switched by a second solenoid signal from the electronic control unit to achieve a third speed stage yet faster than the second speed stage. The first engagement element has a discharge line connected to a drain line via the second directional control valve. The electronic control unit has a detector for determination of tie-up of either or both of the engagement elements, whereby upon detection of tie-up by the detector, the second solenoid signal is output to the second directional control valve.