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:
Apr. 19, 1988
Filed:
Sep. 05, 1986
Yoshihisa Nomura, Toyota, JP;
Koichi Suda, Aichi, JP;
Toyota Jidosha Kabushiki Kaisha, Aichi, JP;
Abstract
In the vacuum boosting system for the brake of a vehicle wherein the boosting vacuum is supplied from the intake manifold of the engine and also, as an assistance thereto, from a vacuum pump which is to be occasionally operated when the intake vacuum of the engine is insufficient to boost the brake, the operation of the vacuum pump is controlled in two alternative modes. In the first mode, when the vehicle is running at a relatively high speed with the transmission being shifted to a relatively high speed stage, the vacuum pump is switched on when the brake boosting vacuum has dropped below a first relatively high threshold value to be operated for a first relatively short period so as to recover the vacuum. In the second mode, when the vehicle is running at a relatively low speed and/or the transmission is shifted to a relatively low speed stage, the vacuum pump is switched on when the brake boosting vacuum has dropped below a second threshold value substantially lower than the above-mentioned first threshold value to be operated for a second period which is substantially longer than the above-mentioned first period.