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:
Jul. 04, 2000
Filed:
Mar. 11, 1998
Masayuki Takami, Kariya, JP;
Tomomichi Mizoguchi, Nagoya, JP;
Satoshi Haseda, Okazaki, JP;
Kazuhiro Okazaki, Anjo, JP;
Koji Jono, Obu, JP;
Denso Corporation, Kariya, JP;
Abstract
An air-fuel ratio sensor generates linear air-fuel ratio detection signals proportional to concentration of oxygen in exhaust gas from an engine in response to a command voltage from a microprocessor. A bias command signal generated by the microprocessor is provided to a D/A converter which converts it to an analog signal. Thereafter, the signal is provided to an LPF for removing the high frequency components of the analog signal. Output voltage of the LPF is provided to a bias control circuit. A single AC signal which has a predetermined frequency and which is provided with a predetermined time constant (about 159 .mu.s) by the LPF is applied to the air-fuel ratio sensor. Element resistance of the air-fuel ratio sensor is detected based on the voltage of the AC signal and the change in the current level of the air-fuel ratio sensor caused by the application of the AC signal.