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. 08, 1991
Filed:
Sep. 22, 1988
Toyota Jidosha Kabushiki Kaisha, Aichi, JP;
Aisin AW Co., Ltd., Aichi, JP;
Abstract
A method and an apparatus for controlling a 4-wheel drive system of a motor vehicle having front wheels and rear wheels and a power transmission. The 4-wheel drive system includes a differential control clutch having input and output elements which are rotatable relative to each other with a controlled amount of engagement therebetween, so as to control a ratio of distribution of a torque from the power transmission to front and rear wheels. When it is determined that the power transmission is commanded to be shifted from a first gear position to a second gear position whose speed ratio is different from that of the first gear position, the differential control clutch is temporarily placed in a fully disengaged position thereof for a predetermined time duration. With the clutch placed in the fully disengaged position upon each shifting operation of the transmission to the second gear position, the separated friction surfaces of the clutch may be lubricated to maintain high durability of the clutch.