Gas concentration detection device

Patent metadata

Field	Value
Publication number	US-10082480-B2
Application number	US-201715597826-A
Country	US
Kind code	B2
Filing date	May 17, 2017
Priority date	May 19, 2016
Publication date	Sep 25, 2018
Grant date	Sep 25, 2018

Abstract

A gas concentration detection device for detecting a gas concentration using a limiting current type gas concentration sensor. In an application voltage line set to pass through a plurality of limiting current regions for different values of gas concentration, a ratio for lean is set as a ratio of change in current with respect to a change in voltage when an air/fuel ratio corresponding to the gas concentration is lean, and a ratio of rich different from the ratio for lean is set when the air/fuel ratio is rich.

First claim

What is claimed is:

1. A gas concentration detection device, adapted for a gas concentration sensor including a sensor element having: a solid electrolyte having oxygen ion conductivity; and a pair of electrodes formed on the solid electrolyte, the gas concentration detection device being configured to apply a voltage between the pair of electrodes based on an application voltage line which is a linear function having an intercept at a predetermined voltage value, detect a limiting current flowing between the pair of electrodes in accordance with the voltage, and detect a gas concentration of a specific component in a gas to be measured, based on the limiting current, wherein
in a detection range for detecting the gas concentration, the application voltage line is set so as to pass through a plurality of limiting current regions of respective limiting current regions for different values of the gas concentration; and a region in which respective limiting current regions for different temperature conditions of the sensor element overlap each other, and
a ratio of change in current with respect to a change in voltage in the application voltage line is set as a ratio for lean when an air/fuel ratio corresponding to the gas concentration is lean, and a ratio for rich different from the ratio for lean is set when the air/fuel ratio is rich.

2. The gas concentration detection device as claimed in claim 1 , wherein
the ratio for lean is greater than the ratio for rich.

3. The gas concentration detection device as claimed in claim 1 ,
which is configured to switch between the ratio for rich and the ratio for lean based on the limiting current flowing between the pair of electrodes.

4. The gas concentration detection device as claimed in claim 1 , wherein
when the air/fuel ratio is lean and the ratio for lean is set, the gas concentration device is configured so that the ratio for lean remains set within a rich-side hysteresis range set in a predetermined rich-side range from a stoichiometric state when the air/fuel ratio changes from lean to rich.

5. The gas concentration detection device as claimed in claim 1 , wherein
when the air/fuel ratio is rich and the ratio for rich is set, the gas concentration device is configured so that the ratio for rich remains set within a lean-side hysteresis range set in a predetermined lean-side range from a stoichiometric state when the air/fuel ratio changes from rich to lean.

Assignees

• Ngk Spark Plug Co

Inventors

• Abe Satoru
• Uemura Tomonori
• Ito Tetsuya
• Teramoto Satoshi

Classifications

• G01N33/0036 Primary

  specially adapted to detect a particular component (physical analysis of gaseous biological material G01N33/497) · CPC title

• G01N27/4073

  Composition or fabrication of the solid electrolyte · CPC title

• G01N27/409 Primary

  Oxygen concentration cells · CPC title

• F02D41/1446

  the characteristics being exhaust temperatures · CPC title

• F02D41/1456

  with sensor output signal being linear or quasi-linear with the concentration of oxygen · CPC title