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:
May. 16, 1989
Filed:
Jul. 01, 1987
Hans D Sommer, Graz, AT;
Steyr-Daimler-Puch Aktiengesellschaft, Vienna, AT;
Abstract
A four-wheel drive of a motor vehicle is arranged to effect automatic changes between a two-wheel drive mode and a four-wheel drive mode in dependence on the slip of two wheels (5) which are permanently driven. A frequent change from the four-wheel drive mode to the two-wheel drive mode for a speed comparison is to be avoided in a four-wheel drive which has a relatively simple structure. Two sensors (12) are associated with the two permanently driven wheels (5) and the output signals of said sensors are delivered to a computer (11), which determines for consecutive units of time the occurrences of the speed difference between said two wheels in excess of a predetermined threshold value and generates a distribution curve of said occurrences in consecutive units of time. That distribution curve is compared in the computer with a corresponding stored limiting curve, which is applicable to a minimum coefficient of road friction. The computer (11) controls a final control element (10) for effecting a change to the four-wheel drive mode when said distribution curve exceeds said limiting curve.