Combustible-gas sensor, diagnostic device for intake-oxygen concentration sensor, and air-fuel ratio control device for internal combustion engines

• US 6,739,177 B2
• Filed: 03/05/2002
• Issued: 05/25/2004
• Est. Priority Date: 03/05/2001
• Status: Expired due to Fees

• Current Assignee: Nippon Soken, Inc. (DENSO Corporation), Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Nippon Soken, Inc. (DENSO Corporation), Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Matsubara, Takuji, Hyoudo, Yoshihiko, Sato, Fumihiko, Yoshioka, Mamoru, Takeuchi, Takayuki, Daido, Shigeki, Oyama, Naohisa
• Primary Examiner(s): SOLIS, ERICK R
• Application Number:
  US10/087,738
• Publication Number:
  US 20020139360A1
• Time in Patent Office: 812 Days
• Field of Search: 73/233.2, 73/233.1, 73/310.5, 73/310.6, 731/182
• US Class Current: 73/23.31
• CPC Class Codes: F02D 41/0037 for diagnosing the engine diagnosis of purge control systems F02M25/0809
• CPC Class Codes: F02D 41/0042 Controlling the combustible mixture as a function of the canister purging, e.g. control of injected fuel to compensate for deviation of air fuel ratio when purging
• CPC Class Codes: F02D 41/144 Sensor in intake manifold
• CPC Class Codes: F02D 41/1456 with sensor output signal being linear or quasi-linear with the concentration of oxygen
• CPC Class Codes: F02D 41/1495 Detection of abnormalities in the air/fuel ratio feedback system
• CPC Class Codes: F02M 25/08 adding fuel vapours drawn from engine fuel reservoir electrical control of purge system F02D41/003
• CPC Class Codes: F02M 26/19 Means for improving the mixing of air and recirculated exhaust gases, e.g. venturis or multiple openings to the intake system
• CPC Class Codes: F02M 26/46 for determining the characteristics of gases, e.g. composition

Abstract

Correction of a fuel injection amount in an internal combustion engine during purge of evaporative fuel is performed on the basis of an output from an intake-oxygen concentration sensor disposed in an intake passage of the internal combustion engine. If the amplitude of fluctuations in engine speed becomes equal to or greater than a predetermined value, it is determined that there is an anomaly in engine output. In addition, if an anomaly in engine output is detected during purge and if no anomaly in engine output is detected during stoppage of purge, an ECU determines that an anomaly has occurred in the intake-oxygen concentration sensor, cancels correction of the fuel injection amount based on an output from the intake-oxygen concentration sensor during purge, and corrects the fuel injection amount on the basis of outputs from exhaust-gas air-fuel ratio sensors.

Claims

1. A combustible-gas sensor that is equipped with a sensor device having a pair of electrodes which are formed on the surface of an oxygen-ion conductor and one of the electrodes is disposed in a space where measurement-target gas containing combustible gas and oxygen exists and that detects a concentration of combustible gas on the basis of a change in the concentration of oxygen contained in measurement-target gas resulting from an oxidizing reaction of combustible gas, comprising:

a correction portion that corrects a deviation in sensor output resulting from a pressure of measurement-target gas, on the basis of a sensor output in the atmosphere of a reference gas.

2. The combustible-gas sensor according to claim 1, wherein:

the correction portion has a relation between a pressure measured in advance in the atmosphere of the reference gas and a sensor output at the pressure stored as a map, calculates a ratio of an output value of the sensor device at a given pressure to be measured to the sensor output at the given pressure as a reference output value, on the based of the map, and calculates a concentration of combustible gas from the ratio.

3. A combustible-gas sensor that is equipped with a sensor device having a pair of electrodes which are formed on the surface of an oxygen-ion conductor and one of the electrodes is disposed in a space where measurement-target gas containing combustible gas and oxygen exists and that detects a concentration of combustible gas on the basis of a change in the concentration of oxygen contained in measurement-target gas resulting from an oxidizing reaction of combustible gas, comprising:

a correction portion corrects a deviation in sensor output resulting from a pressure of the measurement-target gas, on the basis of a map of a relation between a flow speed of measurement-target gas and a sensor output.

4. The combustible-gas sensor according to claim 3, wherein

the correction portion determines that the flow speed of measurement-target gas affects the output only if the flow speed of measurement-target gas is lower than a predetermined value, and then performs to correct the deviation in the sensor output.

5. A combustible-gas sensor that is equipped with a sensor device having a pair of electrodes which are formed on the surface of an oxygen-ion conductor and one of the electrodes is disposed in a space where measurement-target gas containing combustible gas and oxygen exists and that detects a concentration of combustible gas on the basis of a change in the concentration of oxygen contained in measurement-target gas resulting from an oxidizing reaction of combustible gas, comprising:

a correction portion that corrects a sensor output on the basis of a pressure-change speed or a rate of change in concentration of combustible gas during a certain period if the pressure-change speed remains higher than a predetermined speed for the period or more.

6. The combustible-gas sensor according to claim 5, wherein

the correction portion corrects the sensor output through multiplication of a predetermined value that is set in advance in accordance with the pressure-change speed, until the pressure-change speed becomes equal to or lower than the predetermined speed.

7. The combustible-gas sensor according to claim 5, wherein

the correction portion estimates the concentration of combustible gas on the basis of the rate of change in concentration of combustible gas and the sensor output during the period, until the pressure-change speed becomes equal to or lower than the predetermined speed.