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. 20, 2004
Filed:
May. 30, 2002
Shingo Shigihama, Aki-gun, JP;
Tetsushi Hosokai, Aki-gun, JP;
Yoshimi Yamamoto, Aki-gun, JP;
Seiji Makimoto, Aki-gun, JP;
Mazda Motor Corporation, Hiroshima, JP;
Abstract
The present invention provides a malfunction diagnostic apparatus for an evaporated fuel purge system in an internal combustion engine, capable of detecting abnormalities such as looseness or clogging in the purge line between a purge valve and an engine intake passage. An electric pump is turned on when a purge valve is in a closed state and a selector valve is in an open state. After the lapse of a given time period Tref, a load-current initial value I of the electric pump is detected at the moment switching the selector valve to a closed state. After the lapse of a given time period Tpump, the purge valve is switched to an open state, and a load-current final value at the moment after the lapse of a given time period Tpurge. As in the curve A, when a load current final value I is equal to or less than the load current initial value I , it is determined that the gaseous communication state in the purge line between the purge valve and the intake passage is normal. On the other hand, as in the curves B and C, when load current final values I and I are greater than the load current initial value I , it is determined that the gaseous communication state is abnormal. In case of abnormality, when the difference I −I therebetween is less than a gaseous-communication-state determination threshold f as in the curve B, it is determined that the purge line is in an open-air state. If the difference I −I is equal to or greater than the gaseous-communication-state determination threshold f as in the curve C, it is determined that the purge line is in a clogging state.