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:
May. 19, 1998
Filed:
Jun. 17, 1997
Shinichi Abe, Aichi-gen, JP;
Toshio Inoue, Susono, JP;
Toyota Jidosha Kabushiki Kaisha, Aichi, JP;
Abstract
A heater control apparatus for an air-fuel ratio sensor that is capable of supplying optimum power, regardless of the coolant temperature of an internal combustion engine at the engine start-up, is provided. When the internal combustion engine is started, a switching element 122 is continuously held at ON state, to continuously supply power to a heater 112 of the air-fuel ratio sensor 11. The duty cycle of the switching element is controlled so that the heater temperature is maintained at 1100.degree. C., after the heater resistance, which is calculated from the voltage applied to the heater and the current flowing through the heater, has reached a predetermined value, and so that a sensing element 111 is maintained at a temperature of 710.degree. C., after the air-fuel ratio sensor was activated. In performing the control, the power supplied to the heater is increased by adding an auxiliary power calculated as a function of the coolant temperature detected by a coolant temperature sensor 142 and the time elapsed since the engine was started up, thereby preventing an excessive temperature rise of the heater and a delay in the activation of the air-fuel ratio sensor.