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:
Sep. 24, 2002
Filed:
Apr. 14, 1999
Nissan Motor Co., LTD, Yokohama, JP;
Abstract
An EGR system comprises a vacuum-operated EGR valve and an auxiliary valve of a diaphragm type for assisting the operation of the EGR valve. A diagnostic control unit monitors an engine rotational fluctuation parameter such as a misfire parameter under the condition of EGR and judges that there is a possibility of abnormality in the auxiliary valve when the fluctuation parameter is greater than a first judgment value. In response to this judgment, the diagnostic control unit forcibly cuts off the EGR and calculates the fluctuation parameter under the condition of EGR cutoff. The diagnostic control unit concludes that the auxiliary valve is abnormal when the fluctuation parameter in the EGR cutoff state is smaller than or equal to a second judgment value which is smaller than the first judgment value.