JPH0598941A - Exhaust emission control device for internal combustion device - Google Patents

Abstract

PURPOSE:To detect the generation of a crack of a filter quickly and securely by providing an optical reflectance processing device for detecting a crack of a filter on the basis of the input signal. CONSTITUTION:A light source 17 and a photometer 18 are electrically connected to an ECU 14 through a wiring 20. In the case that a crack is generated in a filter 6, color of a part of the periphery of the crack is changed to black by the exhaust leaked from the crack of a filter end surface 6b, and the irradiation quantity of the light source 17 is lowered by the particulate component adhered to an optical reflectance meter 12. Since the optical reflectance of the periphery of the crack to be detected by the reflectance meter 12 is lowered, abnormality of the filter is announced by the ECU 14. At this stage, since the ECU 14 informs abnormality of the filter to a driver with an abnormality lamp and an alarm buzzer or the like, quick change of the filter 6, in which a crack is generated, is enabled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purification device used in a diesel engine, and more particularly to a crack generation detection device for a filter that purifies exhaust gas.

[0002]

2. Description of the Related Art As an exhaust emission control device for a diesel engine, there is known a device in which a filter made of porous ceramic is provided in the middle of an exhaust passage to collect particulate components (particulates) made of carbon contained in exhaust gas. Has been. This type of filter regenerates the filter by burning the particulate component with an electric heater or the like in order to suppress clogging of the filter when the amount of the particulate component collected reaches a predetermined value. However, if the amount of the fine particle components attached to the filter is non-uniform, the temperature of the filter during regeneration is likely to cause a crack in the filter due to local temperature rise, and in this case, the exhaust gas leaking from the crack is a fine particle. It tends to become black smoke containing a large amount of components.

Conventionally, almost no known crack detecting device is capable of detecting such cracks in the filter.
For this reason, when detecting a crack in the filter, it is necessary to disassemble the exhaust gas purification device to directly investigate the crack in the filter, or to visually observe the color of exhaust gas on the downstream side of the filter. There is a problem that it is likely to cause adverse effects such as delay in replacement time.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and improves the reliability of a filter by automatically detecting cracks generated in the filter quickly and accurately. It is an object of the present invention to provide an exhaust gas purification device for an internal combustion engine as described above.

[0005]

An exhaust gas purifying apparatus for an internal combustion engine according to a first aspect of the present invention for solving the above-mentioned problems, comprises:
An exhaust purification device comprising a filter made of a porous ceramic capable of purifying exhaust gas in an exhaust passage of an internal combustion engine,
A light projecting portion provided on the downstream side of the filter in the exhaust passage, a wall body that is in contact with exhaust gas and is irradiated with light generated from the light projecting portion, and a light receiving device that receives reflected light from the wall body. And a light reflectance processing device that receives a signal detected by the light receiving unit and detects a crack in the filter based on the input signal.

An exhaust gas purifying apparatus for an internal combustion engine according to a second aspect of the present invention is an exhaust gas purifying apparatus having a filter made of a porous ceramic capable of purifying exhaust gas in an exhaust passage of the internal combustion engine, wherein A light transmittance meter provided on the filter downstream side to detect the light transmittance of the exhaust gas on the filter downstream side, and a light transmittance to detect cracks in the filter based on a detection signal detected by the light transmittance meter. And a processing device.

[0007]

According to the exhaust gas purifying apparatus of the first aspect of the present invention, when a crack is generated in the filter, the exhaust gas-containing fine particle component adheres to the wall in the exhaust passage on the downstream side of the filter. The light reflectance decreases, and cracks in the filter are detected by detecting this light reflectance. Also,
According to the exhaust gas purifying apparatus of the second invention, when exhaust gas leaks to the downstream side of the filter from the crack of the filter, the light transmittance in the exhaust passage on the downstream side of the filter is lower than that in the exhaust passage on the upstream side of the filter. The abnormality of the filter is detected by detecting the.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show an exhaust emission control device according to a first embodiment of the present invention.
As shown in FIG. As shown in FIG. 2, the exhaust emission control device 1 includes a case 5 having a diameter larger than that of the exhaust pipe 4 in an exhaust pipe 4 between the internal combustion engine body 2 and the muffler 3, and a honeycomb-shaped case 5 is provided in the case 5. It contains the filter 6. In the exhaust pipe 4,
A bypass pipe 7 that bypasses the filter 6 from the branch portion 4a of the exhaust pipe 4 to the muffler 3 is provided, and the exhaust gas from the internal combustion engine body 2 is exhausted by the exhaust switching valve 8 to the exhaust pipe 4 or the bypass pipe 7.
It can be switched to. The filter 6 is of a wall flow monolith type formed of a porous ceramic such as cordierite or alumina, and the porous partition wall extending in the exhaust gas flow direction of the filter 6 collects fine particle components in the exhaust gas. ing.

An electrothermal heater 10 made of a nichrome material or a kanthal material is provided on the upstream end surface 6a of the filter 6. As a result, when the particulate component captured by the filter 6 reaches a predetermined amount, the exhaust switching valve 8 is moved to the position shown by the broken line in FIG. 2 and the electric heater 10 is energized to regenerate the filter 6. As shown in FIG. 1, the filter 6
An optical reflectometer 12 is provided on the downstream side of the filter so as to face the filter downstream end face 6b. The light reflectometer 12 has an end face 6b.
In order to make it possible to measure the reflectance of the entire surface, a plurality of them are arranged at regular intervals on the end face 6b, for example, on concentric circles at equal intervals. The adjacent light reflectometers 12 are kept at intervals so as not to obstruct the flow path of the exhaust gas. A control unit (ECU) 14 that inputs a signal generated by the light reflectometer 12 performs arithmetic processing on this input signal, and as a result of the processing, it is determined that the amount of change in light reflectance has reached a predetermined value or more. And the abnormal lamp,
A warning signal is output to the buzzer. The reflectance detection timing of the light reflectometer 12 may be constantly performed or may be performed at predetermined time intervals.

As shown in FIG. 3, for example, the optical reflectometer 12 has a bottomed cylindrical case 15 in which a mirror 16 having a concave shape along the inner wall of the case is housed.
The light source 17 is attached to the concave portion 16 a of 6. Mirror 16
A photometer 18, into which the reflected light is input, in the opening 16b of the
A convex lens 19 that concentrates the reflected light is fixed to the light receiving portion of the photometer 18. Light source 17 and photometer 18
Are electrically connected to the ECU 14 by the wiring 20.

When a crack is generated in the filter 6, the exhaust gas leaked from the crack on the filter end face 6b changes the black color around the crack, and the fine particle component adhering to the light reflectometer 12 causes the irradiation amount of the light source 17 to be increased. Is reduced. Then, the light reflectance around the crack detected by the light reflectometer 12 decreases, so that the ECU 14 detects the abnormality of the filter. At this time, the ECU 14 informs the driver of the abnormality of the filter by an abnormality lamp, an alarm buzzer, etc. mounted in the vehicle, so that the cracked filter 6 can be quickly replaced.

An exhaust emission control device according to a second embodiment of the present invention is shown in FIG. The exhaust emission control device 30 according to the second embodiment is provided with a reflection plate 33 capable of collecting fine particle components in exhaust gas leaked from cracks of the filter 6 in the center of a cavity 31 formed on the downstream side of the filter 6. Is. The reflector 33 has
An electric heater 34 for burning and removing the collected fine particle components is built in. The light reflectometer 12 has the same structure as that shown in FIG. 3, and is fixed to the case 5 with the light receiving portion of the photometer 18 facing the reflecting surface 33a.

When the exhaust gas leaking from the cracks in the filter end face 6a passes through the cavity 31, a part of the fine particle component in the exhaust gas is collected by the reflecting plate 33. As a result, the reflecting surface 33a of the reflecting plate 33 changes to black, so that the reflecting plate 3
The light reflectance of No. 3 decreases, and the ECU 14 detects the abnormality of the filter 6. After that, the reflection plate 33 is heated by the electric heater 34 to remove the fine particle component, so that the reflectance of the reflection plate 33 returns to the initial value.
This makes it possible to re-detect cracks caused by. The timing of regenerating the reflection plate 33 is not limited to when the abnormality of the filter is detected, and may be periodically set every predetermined time in order to prevent excessive deposits on the reflection plate 33. Good.

An exhaust emission control device according to a third embodiment of the present invention is shown in FIGS. The exhaust gas purification device 40 is provided with light transmittance meters 41 and 42 on the exhaust pipes 4b and 4c on the upstream side and the downstream side of the filter 6, respectively. Light transmittance meter 41, 4
As shown in FIG. 6, 2 is a light projecting portion 4 having a light emitting body 43.
4 and a light receiving section 46 having a photometer 45,
The radiated light from the light emitting body 43 is received by the photometer 45. The light transmittance meters 41, 42 are arranged so that their optical axes are orthogonal to the exhaust gas flow direction.
It is fixed to b and 4c. In the exhaust pipes 4b and 4c, turbulent flow of exhaust gas does not cause a measurement error of the transmittance,
Rectifier plates 47 and 48 are attached immediately upstream of the light transmittance meters 41 and 42. The ECU 14, which receives the signals generated by the light transmittance meters 41 and 42, compares the respective input signals and calculates the purification rate of the filter 6 based on the result of the comparison calculation.

When black exhaust gas is discharged from the crack of the filter 6 to the downstream side of the filter 6, the difference between the light transmittance detected by the light transmittance meter 41 and the light transmittance detected by the light transmittance meter 42. The value decreases, and the purification rate of the filter 6 calculated by the ECU 14 decreases. Therefore, the ECU 14 can detect an abnormality such as a crack in the filter. In the third embodiment, the light transmittance meters 41 and 42 are provided on the upstream side and the downstream side of the filter 6, respectively. However, the light transmittance meters are provided only on the downstream side of the filter 6, and the light transmittance is equal to or more than a predetermined value. It may be determined that the filter 6 is cracked when the value becomes.

[0016]

As described above, according to the exhaust gas purifying apparatus for an internal combustion engine of the present invention, the exhaust gas is detected by the light reflectance meter or the light transmittance meter provided on the upstream side and the downstream side of the filter through which the exhaust gas flows. Since the abnormality of the filter is detected based on the electric signal that is generated, it is possible to detect the occurrence of cracks in the filter quickly and reliably.

[Brief description of drawings]

FIG. 1 is a partial schematic diagram showing an exhaust emission control device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing an exhaust emission control device according to a first embodiment of the present invention.

FIG. 3 is a schematic diagram showing a reflectometer according to a first embodiment of the present invention.

FIG. 4 is a partial schematic view showing an exhaust emission control device according to a second embodiment of the present invention.

FIG. 5 is a partial schematic diagram showing an exhaust emission control device according to a third embodiment of the present invention.

FIG. 6 is a schematic diagram showing a light transmittance meter according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Exhaust gas purification device 4 Exhaust pipe (exhaust passage) 6 Filter 6a Filter end face (wall body) 12 Optical reflectance meter 14 ECU (Light reflectance processing device, Light transmittance processing device) 33 Reflecting plate (Reflecting wall) 41, 42 Light transmittance meter

Claims (2)

[Claims] 1. An exhaust gas purification device comprising a filter made of a porous ceramic capable of purifying exhaust gas in an exhaust passage of an internal combustion engine, wherein: A wall body that is contactable and is irradiated with light generated from the light projecting section, a light receiving section that receives reflected light from the wall body, and a signal detected by the light receiving section are input, and this input signal is input. And a light reflectance processing device for detecting cracks in the filter based on the above. 2. An exhaust gas purification device comprising a filter made of a porous ceramic capable of purifying exhaust gas in an exhaust passage of an internal combustion engine, the exhaust gas purification device being provided on the downstream side of the filter in the exhaust passage, the exhaust gas on the downstream side of the filter. An exhaust emission control device, comprising: a light transmittance meter for detecting the light transmittance of the filter; and a light transmittance processing device for detecting a crack in the filter based on a detection signal detected by the light transmittance meter. ..