Failure determination device for humidity sensor and control system for exhaust passage changeover valve

• US 6,581,370 B2
• Filed: 11/06/2001
• Issued: 06/24/2003
• Est. Priority Date: 11/06/2000
• Status: Expired due to Fees

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Sato, Masahiro, Ueno, Masaki, Akazaki, Shusuke, Haga, Takashi, Sato, Tadashi, Iwaki, Yoshihisa, Miyahara, Yasuyuki
• Primary Examiner(s): Denion, Thomas
• Assistant Examiner(s): TRAN, BINH Q
• Application Number:
  US09/985,764
• Publication Number:
  US 20020053199A1
• Time in Patent Office: 595 Days
• Field of Search: 602/77, 602/76, 602/87, 602/88, 602/89, 602/78, 602/97, 602/99, 602/91, 123/479, 123/688, 731/181
• US Class Current: 60/277
• CPC Class Codes: F01N 11/00 Monitoring or diagnostic devices for exhaust-gas treatment apparatus , e.g. for catalytic activity safety, indicating or supervising devices for internal combustion engines F02B77/08; testing of machines G01M13/00
• CPC Class Codes: F01N 2550/06 By-pass systems
• CPC Class Codes: F01N 2560/028 for measuring or detecting humidity or water
• CPC Class Codes: F01N 3/0835 Hydrocarbons
• CPC Class Codes: F01N 3/0878 Bypassing absorbents or adsorbents
• CPC Class Codes: F02D 2200/0418 Air humidity
• CPC Class Codes: F02D 41/1439 characterised by the position of the sensor
• CPC Class Codes: F02D 41/1441 Plural sensors
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: G01N 33/007 Arrangements to check the analyser calibrating gas analysers G01N33/0006
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A failure determination device that detects the humidity of exhaust gases from an internal combustion engine and a control system for an exhaust passage changeover valve, which can switch the changeover valve with appropriate timing, thereby enabling sufficient purification of exhaust gases. An operating condition of the engine is detected. Based on the detected operating condition of the engine, it is determined whether the engine is in an operating condition in which failure determination of the humidity sensor can be executed. It is determined whether the humidity sensor has failed, based on a result of detection by the humidity sensor, when it has been judged that the failure determination of the humidity sensor can be executed.

Claims

1. A failure determination device for a humidity sensor that detects humidity of exhaust gases from an internal combustion engine,

the failure determination device comprising:

operating condition-detecting means for detecting an operating condition of the engine;

failure determination execution-judging means for judging whether or not the engine is in a predetermined operating condition in which failure determination of the humidity sensor can be executed, based on a result of detection by said operating condition-detecting means; and

humidity sensor failure-determining means for determining whether or not the humidity sensor has failed, based on a result of detection by the humidity sensor, when said failure determination execution-judging means judged that the failure determination of the humidity sensor can be executed engine is in said predetermined operating condition.

2. A failure determination device according to claim 1, wherein an exhaust passage for the exhaust gases is configured such that to switch the exhaust passage can be switched between a main exhaust passage and a bypass exhaust passage having an adsorber arranged in an intermediate portion thereof, the adsorber being capable of for adsorbing hydrocarbons and water in the exhaust gases,

the humidity sensor being arranged at a location downstream of the adsorber in the bypass exhaust passage, and

wherein said failure determination execution-judging means judges that the failure determination of the humidity sensor can be executed engine is in said predetermined operating condition when the exhaust passage has been switched to the bypass exhaust passage, and at the same time the adsorber is adsorbing hydrocarbons in the exhaust gases guided into the bypass exhaust passage.

3. A failure determination device according to claim 2, wherein the hydrocarbons are desorbed from the adsorber by switching the exhaust passage to the main exhaust passage,

the failure determination device further comprising desorption state-detecting means for detecting a state of desorption of the hydrocarbons from the adsorber,

wherein said failure determination execution-judging means judges whether or not the failure determination of the humidity sensor can be executed engine is in said predetermined operation condition, based on the state of the desorption of the hydrocarbons from the adsorber at a time of termination of a preceding operation of the engine, detected by the desorption state-detecting means.

4. A failure determination device according to claim 2, wherein said failure determination execution-judging means further includes timer means for measuring a time period after a start of the engine, and determines whether or not failure determination of the humidity sensor can be executed the engine is in said predetermined operating condition further based on the time period measured by said timer means.

5. A failure determination device according to claim 3, wherein said failure determination execution-judging means further includes fuel injection time-integrating means for calculating a cumulative value of fuel injection time periods after a start of the engine, and determines whether or not failure determination of the humidity sensor can be executed the engine is in said predetermined operating condition further based on the cumulative value calculated by said fuel injection time-integrating means.

6. A failure determination device according to claim 1, wherein said humidity sensor failure-determining means determines that the humidity sensor has failed when the value of humidity detected by the humidity sensor is lower than a predetermined value.

7. A control system for controlling an exhaust passage changeover valve of an internal combustion engine, the changeover valve switching an exhaust passage having a catalytic device arranged therein for purifying exhaust gases from the engine between a main exhaust passage and a bypass exhaust passage bypassing the main exhaust passage and having an adsorber arranged therein which is capable of adsorbing hydrocarbons and water in the exhaust gases,

the control system comprising:

a humidity sensor arranged at a location downstream of the adsorber in the bypass exhaust passage, for detecting humidity of the exhaust gases guided into the bypass exhaust passage; and

changeover valve drive means for driving the changeover valve based on a result of detection by said humidity sensor.

8. A control system according to claim 7, further comprising delayed response compensation means for compensating for a delayed response of said humidity sensor.

9. A control system according to claim 7, wherein said humidity sensor includes a sensor element for being exposed to the exhaust gases for detecting humidity thereof,

the control system further comprising:

a heater for heating said sensor element;

operating condition-detecting means for detecting an operating condition of the engine; and

heater control means for controlling an operation of said heater depending on the operating condition detected by said operating condition-detecting means.

10. A control system according to claim 7, further comprising upstream-side humidity-estimating means for estimating humidity at a location upstream of the adsorber, based on a value of the humidity detected by said humidity sensor.

11. A control system according to claim 10, wherein said changeover valve drive means drives the changeover valve based on a difference between the value of the humidity detected by said humidity sensor and a value of the humidity estimated by said upstream-side humidity-estimating means.

12. A control system according to claim 11, wherein said changeover valve drive means drives the changeover valve further based on a cumulative value of the difference between the value of the humidity detected by said humidity sensor and the value of the humidity estimated by said upstream-side humidity-estimating means.

13. A control system according to claim 7, further comprising an upstream-side humidity sensor for detecting humidity at a location upstream of the adsorber.

14. A control system according to claim 10, wherein said changeover valve drive means drives the changeover valve based on a difference between a value of the humidity detected by said humidity sensor and a value of the humidity detected by said upstream-side humidity sensor.

15. A control system according to claim 11, wherein said changeover valve drive means drives the changeover valve further based on a cumulative value of the difference between the value of the humidity detected by said humidity sensor and the value of the humidity detected by said upstream-side humidity sensor.