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Deterioration detecting apparatus for catalyst

a detection apparatus and catalyst technology, applied in mechanical devices, machines/engines, electric control, etc., can solve the problem of prolonged time period in which the exhaust characteristics are getting worse, and achieve the effect of accurate oxygen amount calculation

Inactive Publication Date: 2007-09-27
HONDA MOTOR CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a deterioration detecting apparatus for a catalyst in an exhaust system of an internal combustion engine. The apparatus can accurately detect the degree of deterioration of the catalyst without affecting the exhaust characteristics. It uses an intake air flow rate detecting means, oxygen concentration sensors, and an air-fuel ratio switching control means to calculate the amount of oxygen flowing into the catalyst and the air-fuel ratio based on the oxygen concentration sensors. The deterioration degree of the catalyst is detected based on the output of the second oxygen concentration sensor during an operation of the air-fuel ratio switching control means. The apparatus can prevent the deterioration of the exhaust characteristics and can accurately detect the deterioration degree of the catalyst.

Problems solved by technology

Therefore, there is a problem that the time period in which the exhaust characteristics are getting worse is likely to be prolonged by performing the deterioration detection.

Method used

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  • Deterioration detecting apparatus for catalyst
  • Deterioration detecting apparatus for catalyst
  • Deterioration detecting apparatus for catalyst

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first embodiment

[0040]FIG. 1 is a schematic diagram showing a general configuration of an internal combustion engine (hereinafter referred to as “engine”) and a control system therefor, including a deterioration detecting apparatus for a catalyst according to one embodiment of the present invention. The engine is, for example, a four-cylinder engine 1 having an intake pipe 2 provided with a throttle valve 3. A throttle valve opening (TH) sensor 4 is connected to the throttle valve 3, outputting an electrical signal according to an opening of the throttle valve 3 and supplying the electrical signal to an electronic control unit 5 (hereinafter referred to as “ECU”).

[0041]Fuel injection valves 6 are inserted into the intake pipe 2 at locations intermediate the cylinder block of the engine 1 and the throttle valve 3 and slightly upstream of the respective intake valves (not shown). These fuel injection valves 6 are connected to a fuel pump (not shown) and are electrically connected to the ECU 5. A valv...

second embodiment

[0110]In the second embodiment, the deterioration of catalyst determination process shown in the first embodiment is further improved. The second embodiment is the same as the first embodiment except for the points described below.

[0111]1) During the fuel cut operation in which the fuel supply to the engine 1 is interrupted, a fuel cut output VLAFFC, which is a characteristic change parameter indicative of a change in the output characteristic of the LAF sensor 17, is detected, and the LAF sensor output VLAF is corrected according to the fuel cut output VLAFFC.

[0112]2) A rich condition updating value of Δ KCMDR and a lean condition updating value Δ KCMDL are used instead of the predetermined Δ KCMD of the target equivalent ratio KCMD. The rich condition updating value Δ KCMDR is set according to the intake air flow rate GAIR and the rich limit value OSOBJR. The lean condition updating value Δ KCMDL is set according to the intake air flow rate GAIR and the lean limit value OSOBJL.

[01...

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Abstract

A deterioration detecting method for a catalyst in an exhaust system of an internal combustion engine for purifying exhaust gases. The system includes a first oxygen concentration sensor and a second oxygen concentration sensor disposed, respectively, upstream and downstream of the catalyst. Intake air flow rate of the engine is detected. An amount of oxygen flowing into the catalyst is calculated according to an oxygen concentration detected by the first sensor and the detected intake air flow rate. An air-fuel ratio of an air-fuel mixture supplied to the engine is controlled by alternately switching between lean and rich with respect to the stoichiometric ratio according to a result of comparison between the calculated and target values of the inflowing oxygen amount. A deterioration degree of the catalyst is detected based on an output of the second sensor when performing the switching control of the air-fuel ratio.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a deterioration detecting apparatus for a catalyst which is provided in an exhaust system of an internal combustion engine for purifying exhaust gases and, particularly, to the deterioration detecting apparatus that detects a degree of deterioration of the catalyst.[0003]2. Description of the Related Art[0004]A technique for determining deterioration of the catalyst which is provided in an exhaust system of an internal combustion engine for purifying exhaust gases (hereinafter referred to simply as “catalyst”) is conventionally known. For example, Japanese Patent Laid-open No. H02-207159 discloses an apparatus for detecting deterioration of the catalyst. This apparatus measures a first time period CB and / or a second time period CA and determines deterioration of the catalyst based on the first time period CB and / or the second time period CA. The first time period CB is a time period from...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): F01N3/00F01N7/00F01N3/20F01N3/24F02D41/02F02D41/14F02D45/00
CPCF01N3/101F01N11/007F01N2560/025F01N2560/14F02D41/0295F02D41/1441F01N13/0093F02D41/1495F02D41/182F02D2200/0816Y02T10/47Y02T10/22F01N13/009F02D41/1456Y02T10/12Y02T10/40
Inventor SUEHIRO, YUKIOIIDA, JUN
Owner HONDA MOTOR CO LTD