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.

Date of Patent:
Aug. 19, 1997

Filed:

Mar. 16, 1995
Applicant:
Inventors:

Yasushi Aoki, Saitama, JP;

Takeshi Ohba, Saitama, JP;

Yukihisa Ishii, Saitama, JP;

Hiroyuki Matsuo, Saitama, JP;

Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
F04B / ;
U.S. Cl.
CPC ...
417 442 ; 417 17 ;
Abstract

An electric pump is turned ON and OFF by a main drive circuit including a negative pressure sensor for detecting a negative pressure in an accumulator, a first relay and a control device, and also turned ON and OFF by a back-up drive circuit including a negative pressure switch for detecting a negative pressure in an accumulator, and a second relay. For a period from the starting of the electric pump by the back-up drive circuit to the stopping of the electric pump by the main drive circuit, there is a period during which the electric pump is being driven only by the back-up drive circuit and a period during which the electric pump is being driven only by the main drive circuit. For each of these periods, a trouble of the main drive circuit and/or the back-up drive circuit can be determined by reference to a check signal indicative of the operational state of the electric pump. Thus, it is possible to reliably detect a trouble with the driving of the electric pump connected to the accumulator.


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