Title:
ABNORMALITY DETECTING DEVICE FOR AIR-FUEL RATIO SENSOR
Document Type and Number:
Japanese Patent JP3149693
Kind Code:
B2
Abstract:
PURPOSE: To prevent the inside and the outside of a detecting part from being decided to be normal even when the inside and the outside of the detecting part are temporarily brought into the same state as that when they are normal by a method wherein gas flowing through an exhaust passage is switched from only air to exhaust gas occasioned by combustion when the detecting part of an air-fuel ratio sensor is defected and the inside and the outside thereof are intercommunicated.
CONSTITUTION: An oxygen sensor 29 is formed in a tubular shape and has a detecting part filled with air and based on a difference in density between the inside and the outside of the detecting part, an air-fuel ratio is detected. An electronic control unit (ECU) 35 measures a lean time in which an air-fuel ratio is rendered rich after it is rendered more lean than a theoretical air-fuel ratio, and decides that the oxygen sensor 29 is abnormal when the measurements exceeds a preset value. When during measurement of a lean time, gas flowing through an exhaust passage 8 is switched from air to exhaust gas occasioned by combustion, during a time in which a predetermined time starting from this point of time elapses, the ECU 35 forcibly continues measurement of a lean time even when an air-fuel ratio by the oxygen sensor 29 is switched from lean to rich.
Inventors:
Seiji Hino
Application Number:
JP15394394A
Publication Date:
March 26, 2001
Filing Date:
July 05, 1994
Export Citation:
Assignee:
TOYOTA JIDOSHA KABUSHIKI KAISHA
International Classes:
F02D45/00; F02D35/00; F02D41/14; F02D41/22; (IPC1-7): F02D45/00; F02D41/14
Domestic Patent References:
| JP5203611A | ||||
| JP63208640A | ||||
| JP1117961A |
Attorney, Agent or Firm:
Hironobu Onda