Method of reducing output degradation of gas sensor

Patent metadata

Field	Value
Publication number	US-2018128771-A1
Application number	US-201715795463-A
Country	US
Kind code	A1
Filing date	Oct 27, 2017
Priority date	Nov 9, 2016
Publication date	May 10, 2018
Grant date	—

Abstract

A gas sensor includes a sensor element made of an oxygen-ion conductive solid electrolyte, at least one electrode provided to the sensor element so as to contact a measurement gas, and a controller configured to control the gas sensor. The sensor element is heated, by a heater provided to the sensor element, at a temperature higher than an operating temperature set in advance for a predetermined time period at start of the gas sensor, and then the temperature of the sensor element is decreased to the operating temperature.

First claim

What is claimed is:

1 . A method of reducing output degradation of a gas sensor, said gas sensor including:
a sensor element made of an oxygen-ion conductive solid electrolyte; at least one electrode provided to said sensor element so as to contact a measurement gas; a heater provided to said sensor element and configured to heat said sensor element; and a controller configured to control said gas sensor, said method comprising the steps of: a) heating, by said heater, said sensor element at a temperature higher than an operating temperature set in advance for a predetermined time period at start of said gas sensor; and b) decreasing, to said operating temperature, the temperature of said sensor element heated to the temperature higher than said operating temperature.

2 . The method of reducing output degradation of a gas sensor according to claim 1 , wherein
a performance evaluation value of output degradation reduction of said gas sensor is defined to be a time integral value of a difference between the temperature of said sensor element and said operating temperature over a range in which the temperature of said sensor element is higher than said operating temperature, and in said step a), at start of said gas sensor, said heater heats said sensor element with such temperature and time that said performance evaluation value is larger than a threshold set in advance based on an output degradation allowable range of said gas sensor.

3 . The method of reducing output degradation of a gas sensor according to claim 1 , wherein
said gas sensor is a mixed-potential type gas sensor, and said gas sensor includes, as said at least one electrode, a sensing electrode, catalytic activity of which is disabled against a predetermined measurement gas component in said measurement gas; said gas sensor further includes a reference electrode provided so as to contact a predetermined reference gas, and said gas sensor measures the concentration of said predetermined measurement gas component based on a potential difference that occurs between said sensing electrode and said reference electrode.

4 . The method of reducing output degradation of a gas sensor according to claim 3 , wherein
said predetermined measurement gas components are hydrocarbon and carbon monoxide, said sensing electrode is made of Pt—Au alloy, and in said step a), a highest temperature of heating of said sensor element at start of said gas sensor is 850° C. or lower.

5 . The method of reducing output degradation of a gas sensor according to claim 2 , wherein
said gas sensor is a mixed-potential type gas sensor, and said gas sensor includes, as said at least one electrode, a sensing electrode, catalytic activity of which is disabled against a predetermined measurement gas component in said measurement gas, said gas sensor further includes a reference electrode provided so as to contact a predetermined reference gas, and said gas sensor measures the concentration of said predetermined measurement gas component based on a potential difference that occurs between said sensing electrode and said reference electrode.

6 . The method of reducing output degradation of a gas sensor according to claim 5 , wherein
said predetermined measurement gas components are hydrocarbon and carbon monoxide, said sensing electrode is made of Pt—Au alloy, and in said step a), a highest temperature of heating of said sensor element at start of said gas sensor is 850° C. or lower.

Assignees

• Ngk Insulators Ltd

Inventors

• Okamoto Taku
• Hirata Noriko
• Nakayama Yuki

Classifications

• G01N27/4067 Primary

  Means for heating or controlling the temperature of the solid electrolyte · CPC title

• G01N27/407 Primary

  for investigating or analysing gases {(G01N27/411 takes precedence)} · CPC title

• F01N2560/20

  Sensor having heating means · CPC title

• F01N2560/02

  the means being an exhaust gas sensor · CPC title

• F01N13/008

  Mounting or arrangement of exhaust sensors in or on exhaust apparatus (sensor arrangements for engine control F02D41/1439) · CPC title