Controller for air-fuel ratio sensor, and program for detecting failure of air-fuel ratio sensor
AssigneeDenso Wave Incorporated
InventorTakayuki Urakawa
Life of this patent
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Abstract
A controller is used for an air-fuel ratio sensor. The air-fuel sensor includes a detection element that detects an oxygen concentration, and a PWM-controlled heater that receives a PWM signal for temperature control of the detection element. The controller includes a resistance detection circuit configured to detect a resistance of the detection element, and a processor. The processor is programmed to generate the PWM signal for the heater based on the detected resistance such that the resistance of the detection element is kept at a predetermined target resistance, and determine whether a failure has occurred in the air-fuel ratio sensor based on a manner of time-series increase in duty cycle of the PWM signal.
Claims7
A controller for an air-fuel ratio sensor, the air-fuel ratio sensor including a detection element that is made of solid electrolyte and detects an oxygen concentration, and a PWM-controlled heater that receives a PWM signal for temperature control of the detection element, the controller comprising:
- a resistance detection circuit configured to detect a resistance of the detection element;
- and
- a processor programmed to:
- generate the PWM signal for the heater based on the detected resistance such that the resistance of the detection element is kept at a predetermined target resistance;
- and
- determine whether a failure has occurred in the air-fuel ratio sensor based on a manner of time-series increase in duty cycle of the PWM signal.
A non-transitory storage medium storing a failure detection program executable by a controller for an air-fuel ratio sensor, the air-fuel ratio sensor including a detection element that is made of solid electrolyte and detects an oxygen concentration, and a PWM-controlled heater that receives a PWM signal generated based on a resistance of the detection element for temperature control of the detection element such that the resistance of the detection element is kept at a predetermined target resistance, the failure detection program being configured to cause the controller to execute:
- determining whether a failure has occurred in the air-fuel ratio sensor based on a manner of time-series increase in duty cycle of the PWM signal.
Dependencies are inferred from the claim text.