Deteriorated state evaluation device of exhaust emission control equipment

• US 20040231322A1
• Filed: 01/30/2004
• Published: 11/25/2004
• Est. Priority Date: 08/31/2001
• Status: Active Grant

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Ohmori, Kenichi, Miyahara, Yasuyuki, Sato, Masahiro, Ueno, Masaki
• Granted Patent: US 6,935,099 B2
• Time in Patent Office: Days
• 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 2550/03 of sorbing activity of adsorbents or absorbents
• CPC Class Codes: F01N 2560/028 for measuring or detecting humidity or water
• CPC Class Codes: F01N 2570/12 Hydrocarbons
• CPC Class Codes: F01N 3/0807 by using absorbents or adsorbents
• CPC Class Codes: F01N 3/0835 Hydrocarbons
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

After an engine 1 has started to operate, a state in which a humidity represented by an output of a humidity sensor 19 downstream of a hydrocarbon adsorbent 7 takes a minimum value is sequentially searched for, and a timing at which the humidity changes from the minimum value to a monotonously increasing state is grasped as a timing at which the adsorption of moisture and hydrocarbons by the hydrocarbon adsorbent 7 is saturated. After the engine has started to operate, a parameter representing an integrated amount of moisture given to the hydrocarbon adsorbent 7 by the exhaust gas is sequentially generated, and a deteriorated state of the hydrocarbon adsorbent 7 is evaluated based on the value of the parameter at the timing at which the adsorption is saturated. The deteriorated state of the hydrocarbon adsorbent 7 can thus accurately be evaluated by an inexpensive arrangement which employs the humidity sensor 19 disposed downstream of the hydrocarbon adsorbent 7.

Claims

1. An apparatus for evaluating a deteriorated state of an exhaust gas purifier disposed in an exhaust passage of an internal combustion engine and having a hydrocarbon adsorbent for adsorbing hydrocarbons in an exhaust gas flowing through the exhaust passage, comprising:

a humidity sensor disposed downstream of said hydrocarbon adsorbent for outputting a signal depending on the humidity of said exhaust gas;

means for sequentially generating a deterioration evaluating parameter representative of an integrated amount of moisture that is supplied to said hydrocarbon adsorbent by said exhaust gas, after said internal combustion engine has started to operate; and

means for sequentially searching for a state in which the humidity represented by an output of said humidity sensor takes a minimum value, and detecting a changing timing at which said humidity changes from the state in which the humidity takes a minimum value to a monotonously increasing state, after said internal combustion engine has started to operate;

wherein a deteriorated state of said hydrocarbon adsorbent is evaluated based on the value of the deterioration evaluating parameter at said changing timing.

2. An apparatus according to claim 1, wherein said means for sequentially generating a deterioration evaluating parameter sequentially integrates data representative of an amount of moisture contained in the exhaust gas produced by said internal combustion engine from the time when said internal combustion engine starts to operate, and generates an integrated value as the deterioration evaluating parameter.

3. An apparatus according to claim 1, wherein a value of the deterioration evaluating parameter at said changing timing is compared with a predetermined threshold which is established depending on the temperature of said hydrocarbon adsorbent at the time when said internal combustion engine starts to operate, for thereby evaluating the deteriorated state of said hydrocarbon adsorbent.

4. An apparatus according to claim 1, wherein said means for detecting a changing timing detects a time when the humidity represented by the output of said humidity sensor increases a predetermined quantity or more from said minimum value after the humidity has taken the minimum value, as said changing timing.

5. An apparatus according to claim 1, wherein said means for detecting a changing timing stores the value of said deterioration evaluating parameter at a time, regarded as a temporary changing timing, when the humidity represented by the output of said humidity sensor increases a predetermined quantity or more from said minimum value after the humidity has taken the minimum value, and thereafter determines said temporary changing timing as a true changing timing when the humidity represented by the output of said humidity sensor increases to a predetermined upper limit value without taking a minimum value.

6. An apparatus according to claim 5, wherein the deteriorated state of said hydrocarbon adsorbent is evaluated based on the value of the deterioration evaluating parameter at said true changing timing only if the difference between a value which is the sum of said minimum value immediately prior to said temporary changing timing and said predetermined quantity, and said predetermined upper limit value is equal to or greater than a predetermined lower limit value, when said temporary changing timing is determined as said true changing timing.

7. An apparatus for evaluating a deteriorated state of an exhaust gas purifier disposed in an exhaust passage of an internal combustion engine and having a hydrocarbon adsorbent for adsorbing hydrocarbons in an exhaust gas flowing through the exhaust passage, comprising:

a downstream humidity sensor and an upstream humidity sensor disposed respectively downstream and upstream of said hydrocarbon adsorbent for outputting signals depending on the humidity of said exhaust gas;

means for sequentially searching for a state in which the humidity represented by an output of said upstream humidity sensor takes a minimum value, and detecting a timing at which said humidity changes from the state in which the humidity takes a minimum value to a monotonously increasing state as an upstream changing timing, after said internal combustion engine has started to operate;

means for sequentially searching for a state in which the humidity represented by an output of said downstream humidity sensor takes a minimum value, and detecting a timing at which said humidity changes from the state in which the humidity takes a minimum value to a monotonously increasing state as a downstream changing timing, after said internal combustion engine has started to operate; and

means for generating a deterioration evaluating parameter representative of an integrated amount of moisture that is supplied to said hydrocarbon adsorbent by the exhaust gas from said internal combustion engine from said upstream changing timing to said downstream changing timing;

wherein a deteriorated state of said hydrocarbon adsorbent is evaluated based on the value of the deterioration evaluating parameter.

8. An apparatus according to claim 7, wherein said means for sequentially generating a deterioration evaluating parameter sequentially integrates data representative of an amount of moisture contained in the exhaust gas produced by said internal combustion engine from the time when said internal combustion engine starts to operate, and determines the deviation between an integrated value at the changing timing relative to said upstream humidity sensor and an integrated value at the changing timing relative to said downstream humidity sensor, as the deterioration evaluating parameter.

9. An apparatus according to claim 7, wherein the deteriorated state of said hydrocarbon adsorbent is evaluated by comparing the value of said deterioration evaluating parameter with a predetermined threshold that is established depending on the temperature of said hydrocarbon adsorbent at the time when said internal combustion engine starts to operate.

10. An apparatus according to claim 7, wherein said means for detecting an upstream changing timing detects a time when the humidity represented by the output of said upstream humidity sensor increases a first predetermined quantity or more from said minimum value after the humidity has taken the minimum value, as said upstream changing timing, and said means for detecting a downstream changing timing detects a time when the humidity represented by the output of said downstream humidity sensor increases a second predetermined quantity or more from said minimum value after the humidity has taken the minimum value, as said downstream changing timing.

11. An apparatus according to claim 7, wherein said means for detecting an upstream changing timing detects a time when the humidity represented by the output of said upstream humidity sensor increases a first predetermined quantity or more from said minimum value after the humidity has taken the minimum value, as a temporary upstream changing timing, and thereafter determines said temporary upstream changing timing as a true upstream changing timing when the humidity represented by the output of said upstream humidity sensor increases to a predetermined first upper limit value without taking a minimum value, and wherein said means for detecting a downstream changing timing detects a time when the humidity represented by the output of said downstream humidity sensor increases a second predetermined quantity or more from said minimum value after the humidity has taken the minimum value, as a temporary downstream changing timing, and thereafter determines said temporary downstream changing timing as a true downstream changing timing when the humidity represented by the output of said downstream humidity sensor increases to a predetermined second upper limit value without taking a minimum value.

12. An apparatus according to claim 11, wherein the deteriorated state of said hydrocarbon adsorbent is evaluated based on the value of the deterioration evaluating parameter representing said integrated amount of moisture from said true downstream changing timing to said upstream changing timing only if the difference between a value which is the sum of the minimum value of the humidity relative to said upstream humidity sensor immediately prior to said temporary upstream changing timing and said first predetermined quantity, and said predetermined first upper limit value is equal to or greater than a predetermined first lower limit value, and if the difference between a value which is the sum of the minimum value of the humidity relative to said downstream humidity sensor immediately prior to said temporary downstream changing timing and said second predetermined quantity, and said predetermined second upper limit value is equal to or greater than a predetermined second lower limit value, when said temporary upstream changing timing is determined as said true upstream changing timing and said temporary downstream changing timing is determined as said true downstream changing timing.