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:
Oct. 31, 1995
Filed:
Oct. 05, 1994
Yoichi Iwata, Susono, JP;
Toyota Jidosha Kabushiki Kaisha, Aichi, JP;
Abstract
An oxygen sensor heat controlling apparatus includes: a current-limiting type oxygen sensor whose electrical characteristic varies with a change in an oxygen concentration of exhaust gases from an internal combustion engine, and whose alternating current resistance varies with a change in an operating temperature of the sensor; a voltage source connected with the sensor through a resistor to supply a given voltage to the sensor; a differential amplifier having a first input connected with the sensor and a second input connected with the voltage source through the resistor, the amplifier producing at its output an output signal derived from the difference between the given voltage and an output voltage from the sensor, the output signal being representative of the oxygen concentration of the exhaust gases; a first closed loop circuit which connects the output of the amplifier with the first input of the amplifier via a first feedback resistor so as to control a current flow through the sensor; a second closed loop circuit which connects the output of the amplifier with the second input thereof via a second feedback resistor; a heater for heating the sensor; an oscillation detecting circuit for detecting occurrence of an oscillation at the output of the amplifier and for outputting a pulse when the occurrence of the oscillation is detected; and a current control circuit for applying current to the heater when the oscillation has not occurred, and for stopping the application of current to the heater in response to the pulse.