Control system of exhaust sensor

Patent metadata

Field	Value
Publication number	US-2017292433-A1
Application number	US-201715482217-A
Country	US
Kind code	A1
Filing date	Apr 7, 2017
Priority date	Apr 11, 2016
Publication date	Oct 12, 2017
Grant date	—

Abstract

A control system of an exhaust sensor controlling an exhaust sensor comprises a heater control part controlling a heater and a temperature estimating part estimating a temperature of an exhaust pipe around the exhaust sensor. The heater control part sets the target temperature to a first target temperature after startup of the internal combustion engine and until the estimated temperature of the exhaust pipe reaches a first exhaust pipe temperature, sets the target temperature to a second target temperature from when the estimated temperature of the exhaust pipe reaches the first exhaust pipe temperature to when it reaches a second exhaust pipe temperature, and sets the target temperature to an operating temperature of the electrochemical cell when the estimated temperature of the exhaust pipe reaches the second exhaust pipe temperature.

First claim

1 . A control system of an exhaust sensor controlling an exhaust sensor arranged in an exhaust passage of an internal combustion engine and detecting a specific component in exhaust gas, wherein
the exhaust sensor comprises an element body provided with an electrochemical cell, a protective layer formed on an outer surface of the element body and comprised of a porous ceramic, and a heater heating the element body and the protective layer, the control system comprises a heater control part configured to set a target temperature of the electrochemical cell and control the heater so that a temperature of the electrochemical cell becomes the target temperature, and a temperature estimating part configured to estimate a temperature of an exhaust pipe around the exhaust sensor, the heater control part is configured to set the target temperature to a first target temperature after startup of the internal combustion engine and until the estimated temperature of the exhaust pipe estimated by the temperature estimating part reaches a first exhaust pipe temperature, set the target temperature to a second target temperature from when the estimated temperature of the exhaust pipe reaches the first exhaust pipe temperature to when it reaches a second exhaust pipe temperature, and set the target temperature to an operating temperature of the electrochemical cell when the estimated temperature of the exhaust pipe reaches the second exhaust pipe temperature, and the first exhaust pipe temperature is a temperature of a dew point of water to less than a boiling point of water, the second exhaust pipe temperature is a temperature of the boiling point of water or more, the first target temperature is a temperature higher than the operating temperature, and the second target temperature is a temperature higher than the operating temperature and lower than the first target temperature.

2 . The control system of an exhaust sensor according to claim 1 , wherein
the temperature estimating part is configured to estimate or detect an outside air temperature of the internal combustion engine, and the heater control part is configured to set the first target temperature higher when the temperature of the outside air temperature estimated or detected by the temperature estimating part at the time of startup of the internal combustion engine is relatively low compared with when the temperature of the outside air temperature is relatively high.

3 . The control system of an exhaust sensor according to claim 1 , wherein
the temperature estimating part is configured to judge that the estimated temperature of the exhaust pipe has reached the first exhaust pipe temperature when an elapsed time from when the internal combustion engine is started up reaches a first elapsed time, and judge that the estimated temperature of the exhaust pipe has reached the second exhaust pipe temperature when the elapsed time reaches a second elapsed time longer than the first elapsed time and the temperature estimating part is configured to estimate or detect an outside air temperature of the internal combustion engine and set the first elapsed time and the second elapsed time longer when the temperature of the outside air temperature estimated or detected at the time of startup of the internal combustion engine is relatively low compared with when the temperature of the outside air temperature is relatively high.

4 . The control system of an exhaust sensor according to claim 2 , wherein
the temperature estimating part is configured to judge that the estimated temperature of the exhaust pipe has reached the first exhaust pipe temperature when an elapsed time from when the internal combustion engine is started up reaches a first elapsed time, and judge that the estimated temperature of the exhaust pipe has reached the second exhaust pipe temperature when the elapsed time reaches a second elapsed time longer than the first elapsed time and the temperature estimating part is configured to estimate or detect an outside air temperature of the internal combustion engine and set the first elapsed time and the second elapsed time longer when the temperature of the outside air temperature estimated or detected at the time of startup of the internal combustion engine is relatively low compared with when the temperature of the outside air temperature is relatively high.

5 . The control system of an exhaust sensor according to claim 1 wherein
the temperature estimating part is configured to judge that the estimated temperature of the exhaust pipe has reached the first exhaust pipe temperature when a cumulative value of an intake air amount supplied to combustion chambers of the internal combustion engine from when the internal combustion engine is started up reaches a first cumulative air amount, and judge that the estimated temperature of the exhaust pipe has reached the second exhaust pipe temperature when the cumulative value reaches a second cumulative air amount greater than the first cumulative air amount and
the temperature estimating part is configured to estimate or detect an outside air temperature of the internal combustion engine and set the first cumulative air amount and the second cumulative air amount greater when the temperature of the outside air temperature estimated or detected at the time of startup of the internal combustion engine is relatively low compared with when the temperature of the outside air temperature is relatively high.

6 . The control system of an exhaust sensor according to claim 2 wherein
the temperature estimating part is configured to judge that the estimated temperature of the exhaust pipe has reached the first exhaust pipe temperature when a cumulative value of an intake air amount supplied to combustion chambers of the internal combustion engine from when the internal combustion engine is started up reaches a first cumulative air amount, and judge that the estimated temperature of the exhaust pipe has reached the second exhaust pipe temperature when the cumulative value reaches a second cumulative air amount greater than the first cumulative air amount and
the temperature estimating part is configured to estimate or detect an outside air temperature of the internal combustion engine and set the first cumulative air amount and the second cumulative air amount greater when the temperature of the outside air temperature estimated or detected at the time of startup of the internal combustion engine is relatively low compared with when the temperature of the outside air temperature is relatively high.

7 . The control system of an exhaust sensor according to claim 1 wherein
the exhaust sensor includes an upstream side exhaust sensor, and a downstream side exhaust sensor positioned at a downstream side of the upstream side exhaust sensor in a direction of exhaust flow, and
the heater control part is configured to set the first target temperature and the second target temperature at the downstream side exhaust sensor higher than the first target temperature and the second target temperature at the upstream side exhaust sensor.

8 . The control system of an exhaust sensor according to claim 2 wherein
the exhaust sensor includes an upstream side exhaust sensor, and a downstream side exhaust sensor positioned at a downstream side of the upstream side exhaust sensor in a direction of exhaust flow, and
the heater control part is configured to set the first target temperature and the second target temperature at the downstream side exhaust sensor higher than the first target temperature and the second target temperature at the upstream side exhaust sensor.

9 . The control system of an exhaust sensor according to claim 3 wherein
the exhaust sensor includes an

Assignees

• Toyota Motor Co Ltd

Inventors

• Hayashita Go

Classifications

• F01N2560/20

  Sensor having heating means · CPC title

• G01N27/4077 Primary

  Means for protecting the electrolyte or the electrodes · CPC title

• G01N27/4075

  Composition or fabrication of the electrodes and coatings thereon, e.g. catalysts · CPC title

• F01N9/00

  Electrical control of exhaust gas treating apparatus (monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00) · CPC title

• G05D23/20

  with sensing elements having variation of electric or magnetic properties with change of temperature (G05D23/13 takes precedence) · CPC title