Exhaust gas purifier for internal combustion engines

• US 6,711,892 B2
• Filed: 11/18/2002
• Issued: 03/30/2004
• Est. Priority Date: 02/26/2001
• Status: Active Grant

• Current Assignee: Mitsubishi Jidosha Kogyo Kabushiki Kaisha
• Original Assignee: Mitsubishi Jidosha Kogyo Kabushiki Kaisha
• Inventors: Koga, Kazuo, Ohashi, Tomohiro, Okada, Kojiro, Yamada, Naoto, Tamura, Yasuki
• Primary Examiner(s): Denion, Thomas
• Assistant Examiner(s): NGUYEN, TU MINH
• Application Number:
  US10/276,824
• Publication Number:
  US 20030115854A1
• Time in Patent Office: 498 Days
• Field of Search: 602/74, 602/76, 602/77, 602/78, 602/79, 602/85, 602/86, 602/97, 603/01, 603/11, 73/232, 73/233.1, 73/233.2, 204/424, 204/425, 204/426
• 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 11/007 the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus
• CPC Class Codes: F01N 13/009 having two or more separate purifying devices arranged in series
• CPC Class Codes: F01N 2260/14 for modifying or adapting flow area or back-pressure
• CPC Class Codes: F01N 2550/02 Catalytic activity of catalytic converters
• CPC Class Codes: F01N 3/0814 combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts
• CPC Class Codes: F01N 3/0821 combined with particulate filters catalysed diesel particulate filters F01N3/035
• CPC Class Codes: F01N 3/0842 Nitrogen oxides
• CPC Class Codes: F02D 2011/102 at least one throttle being moved only by an electric actuator
• CPC Class Codes: F02D 2041/147 the characteristics being a hydrogen content or concentration of the exhaust gases
• CPC Class Codes: F02D 2041/228 Warning displays
• CPC Class Codes: F02D 41/0052 Feedback control of engine parameters, e.g. for control of air/fuel ratio or intake air amount
• CPC Class Codes: F02D 41/029 the exhaust gas treating apparatus being a particulate filter
• CPC Class Codes: F02D 41/1448 the characteristics being an exhaust gas pressure
• CPC Class Codes: F02D 41/1454 the characteristics being an oxygen content or concentration or the air-fuel ratio
• 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: F02D 9/04 concerning exhaust conduits throttle valves, or arrangements thereof in conduits F02D9/08
• CPC Class Codes: F02M 26/15 in relation to engine exhaust purifying apparatus
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An exhaust passage (20) of an internal-combustion engine (1) is provided with an exhaust emission control unit (40) capable of reducing harmful substances in exhaust gas under a given exhaust pressure condition and an exhaust sensor (22) for detecting the concentration of a specific exhaust component (H₂, O₂) in the exhaust gas, and a performance lowering identifying unit identifies lowering of the performance of the exhaust emission control (40) by detecting a failure to fulfill the given exhaust pressure condition in accordance with the output of the exhaust sensor.

Claims

1. An exhaust emission control device of an internal-combustion engine, comprising:

exhaust emission control means located in an exhaust passage of the internal-combustion engine and adapted to reduce harmful substances in exhaust gas under a given exhaust pressure condition;

an exhaust sensor, provided in the exhaust passage and upstream of said exhaust emission control means, for detecting and outputting the concentration of a specific exhaust component in said exhaust gas at an upstream of the exhaust emission control means, the output of the exhaust sensor being also indicative of an actual exhaust gas pressure upstream of said exhaust emission control means, and said exhaust sensor being the only exhaust sensor provided in the exhaust passage; and

performance lowering identifying means for identifying lowering of the performance of said exhaust emission control means by detecting a failure to fulfill said given exhaust pressure condition based on the output of said exhaust sensor.

2. An exhaust emission control device of an internal-combustion engine according to claim 1, wherein said exhaust emission control means includes an exhaust flow control valve adapted to adjust the flow area of the exhaust passage, and said performance lowering identifying means identifies abnormality of said exhaust flow control valve.

3. An exhaust emission control device of an internal-combustion engine according to claim 1, wherein said performance lowering identifying means identifies lowering of the performance of said exhaust emission control means by comparing the output from said exhaust sensor and a target output with the same exhaust component concentration under a reference pressure.

4. An exhaust emission control device of an internal-combustion engine according to claim 1, wherein said exhaust sensor is adapted to detect at least two exhaust component concentrations and is adapted to detect the concentration of at least one specific exhaust component when the exhaust air-fuel ratio is a lean air-fuel ratio and to detect the respective concentrations of other specific exhaust components when the air-fuel ratio is a rich air-fuel ratio.

5. An exhaust emission control device of an internal-combustion engine according to claim 1, wherein said exhaust emission control means is a post-exhaust processor, and said performance lowering identifying means determines the necessity of regeneration of said post-exhaust processor.

6. An exhaust emission control device of an internal-combustion engine according to claim 5, wherein said performance lowering identifying means sets a decision value for determining the necessity of regeneration of said post-exhaust processor in accordance with the operating conditions of the internal-combustion engine and said specific exhaust component concentration, and determines the necessity of regeneration of said post-exhaust processor by comparing the output of said exhaust sensor and said decision value using the same operating conditions and the same exhaust component concentration.

7. An exhaust emission control device of an internal-combustion engine according to claim 5, wherein said exhaust sensor is an O₂ sensor, said post-exhaust processor includes an occlusion-type NOx catalyst, and said performance lowering identifying means determines the necessity of regeneration of said post-exhaust processor when the exhaust air-fuel ratio is adjusted to a rich air-fuel ratio in order to release NOx from said occlusion-type NOx catalyst.

8. An exhaust emission control device of an internal-combustion engine according to claim 5, wherein said performance lowering identifying means sets, in accordance with the operating conditions of the internal-combustion engine, a target output under a reference exhaust pressure with said post-exhaust processor nonoperating, sets a decision value for determining the necessity of regeneration of said post-exhaust processor in accordance with the exhaust component concentration, and concludes that regeneration of said post-exhaust processor is necessary if the deviation between the output of said exhaust sensor and said target output exceeds said decision value with the same operating conditions and the same exhaust component concentration.

9. An exhaust emission control device of an internal-combustion engine according to claim 5, wherein said exhaust sensor is a linear air-fuel ratio sensor, and said performance lowering identifying means determines the necessity of regeneration of said post-exhaust processor when the exhaust air-fuel ratio is a lean air-fuel ratio during injection quantity feedback control using said linear air-fuel ratio sensor and based on the excess air factor of the internal-combustion engine.

10. An exhaust emission control device of an internal-combustion engine according to claim 5, wherein said exhaust sensor is a linear air-fuel ratio sensor, said post-exhaust processor includes an occlusion-type NOx catalyst, and said performance lowering identifying means determines the necessity of regeneration of said post-exhaust processor when the exhaust air-fuel ratio is adjusted to a rich air-fuel ratio in order to release NOx from said Occlusion-type NOx catalyst.

11. An exhaust emission control device of an internal-combustion engine, comprising:

exhaust emission control means located in an exhaust passage of the internal-combustion engine and adapted to reduce harmful substances in exhaust gas under a given exhaust pressure condition;

an exhaust sensor for detecting the concentration of a specific exhaust component in said exhaust gas; and

performance lowering identifying means for identifying lowering of the performance of said exhaust emission control means by detecting a failure to fulfill said given exhaust pressure condition in accordance with the output of said exhaust sensor,

wherein said exhaust emission control means is a post-exhaust processor, and said performance lowering identifying means determines the necessity of regeneration of said post-exhaust processor, and

wherein said exhaust sensor is a linear air-fuel ratio sensor, and said performance lowering identifying means determines the necessity of regeneration of said post-exhaust processor when the exhaust air-fuel ratio is a lean air-fuel ratio during exhaust reflux feedback control using said linear air-fuel ratio sensor.

12. An exhaust emission control device of an internal-combustion engine, comprising:

exhaust emission control means located in an exhaust passage of the internal-combustion engine and adapted to reduce substances in exhaust gas under a given exhaust pressure condition;

an exhaust sensor for detecting the concentration of a specific exhaust component in said exhaust gas; and

performance lowering identifying means for identifying lowering of the performance of said exhaust emission control means by detecting a failure to fulfill said given exhaust pressure condition in accordance with the output of said exhaust sensor, wherein said performance lowering identifying means identifies lowering of the performance of said exhaust emission control means in accordance with relations between a plurality of outputs with different exhaust component concentrations from said exhaust sensor and a plurality of target outputs with said individual exhaust component concentrations under the reference pressure.