JPH10159540A - Exhaust emission control device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold ash stored in an ash storing part in a condition capable of delivering easily by arranging the recessed shaped ash storing part having a part opened to an engine exhaust passage in the vicinity of an exhaust upstream side of a filter for collecting particulate, and arranging a dam around the opening part. SOLUTION: In a filter 1 for collecting particulate, a first flange pipe 2 connected to a downstream exhaust pipe is connected to an exhaust downstream side, and a second flange pipe 3 is connected to an exhaust upstream side. The filter 1 is slantly arranged below the exhaust upstream side, and a recessed shaped ash storing part 30 is formed on a lower side of the second flange pipe 3, and is opened nearly opposing to a vertical projection surface of an exhaust upstream side end surface of the filter 1. A dam 30a is formed around an opening part of the ash storing part 30. It is thus possible to prevent water directed to the ash storing part 30 along an inner wall surface of the second flange pipe 3 from flowing into the ash storing part 30, and it is also possible to deliver its water easily without fixing ash.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an exhaust gas purifying apparatus for a diesel engine.

[0002]

2. Description of the Related Art The exhaust gas of a diesel engine contains a relatively large amount of exhaust particulates (particulates) containing carbon as a main component, which causes environmental pollution before the exhaust gas is released to the atmosphere. Preferably, the filter is removed, and a filter for trapping particulates is disposed in an exhaust passage of the diesel engine.

[0003] If the amount of particulates collected in the filter increases with the use of a diesel engine, the exhaust resistance increases and the engine performance deteriorates. Therefore, the collected particulates are periodically burned, and the filter is regenerated. It is supposed to be.

[0004] In the combustion of a diesel engine, not only fuel but also engine oil that has entered the cylinder is burned, so that oxides and sulfides such as calcium and phosphorus, which are components thereof, are generated. Usually, particulates have these as components. Since oxides or sulfides of calcium or phosphorus are very difficult to burn and remain in the filter as ash in the above-mentioned filter regeneration and are not discharged to the exhaust downstream side through the filter,
Accumulates in the filter and increases exhaust resistance.

Therefore, it is necessary to discharge such ash to the upstream side of the filter exhaust so as not to flow into the filter again. 58-1495
Japanese Patent Application Laid-Open No. 11-111699 proposes forming a concave ash accommodating portion near the filter exhaust upstream side of the exhaust passage and accommodating the ash discharged to the filter exhaust upstream side in the ash accommodating portion. . The capacity of the ash storage unit is limited, and the ash stored in the ash storage unit must be periodically discharged.

[0006]

The ash contains a large amount of calcium sulfate as a component thereof. In the above-described prior art, when the temperature of the exhaust system decreases after the engine is stopped, water vapor contained in the exhaust gas in the exhaust system is condensed on the inner wall surface of the exhaust system, and the concave ash accommodating portion has an inner wall surface of the ash accommodating portion. In addition to the water condensed in the above, part of the water condensed on the inner wall surface of the exhaust passage flows. Since the above-mentioned calcium sulfate is a raw material of gypsum, the ash containing a large amount of calcium sulfate sticks in the ash storage portion when a large amount of water is present in the ash storage portion in this way, and the ash is discharged from the ash storage portion. It becomes difficult.

Accordingly, an object of the present invention is to provide an exhaust gas purifying apparatus for a diesel engine capable of always maintaining the ash stored in the ash storage section in a state where the ash can be easily discharged.

[0008]

According to a first aspect of the present invention, there is provided an exhaust gas purifying apparatus for a diesel engine, comprising: a filter for collecting particulates disposed in an engine exhaust passage; A concave ash storage portion having an opening to the engine exhaust passage,
A weir is provided around the opening of the ash storage unit.

According to a second aspect of the present invention, there is provided a diesel engine exhaust purifying apparatus, comprising: a filter for collecting particulates disposed in an engine exhaust passage; A concave ash storage portion having an opening, and a water storage portion provided around the opening of the ash storage portion.

According to a third aspect of the present invention, there is provided an exhaust gas purifying apparatus for a diesel engine, comprising: a filter for collecting particulates disposed in an engine exhaust passage; A concave ash storage section having an opening, wherein the ash storage section is provided with a heat retaining means.

According to a fourth aspect of the present invention, there is provided an exhaust gas purifying apparatus for a diesel engine, comprising: a filter for collecting particulates disposed in an engine exhaust passage; A concave ash accommodating portion having an opening, and a cooling means provided in the engine exhaust passage on the exhaust upstream side of the filter.

According to a fifth aspect of the present invention, there is provided an exhaust gas purifying apparatus for a diesel engine, comprising: a filter for collecting particulates disposed in an engine exhaust passage; A concave ash accommodating portion having an opening, wherein the emissivity of the ash accommodating portion is smaller than the emissivity of the engine exhaust passage on the exhaust upstream side of the filter.

[0013]

FIG. 1 is a schematic longitudinal sectional view of a part of an engine exhaust system showing a first embodiment of an exhaust gas purifying apparatus for a diesel engine according to the present invention. In the figure, reference numeral 1 denotes a filter for collecting particulates. Reference numeral 2 denotes a first flange pipe connected to the exhaust downstream side of the filter 1, and reference numeral 3 denotes a second flange pipe connected to the exhaust upstream side of the filter 1. The first flange pipe 2 is connected to a downstream exhaust pipe via a turbocharger turbine.

As shown in the drawing, the filter 1 is disposed obliquely with the exhaust upstream side down, and the lower side of the second flange pipe 3 is substantially opposed to the vertical projection surface of the exhaust upstream end face of the filter 1. A recessed ash accommodating portion 30 is formed. FIG. 2 shows a cross section AA in FIG. As shown in these drawings, each side wall of the ash accommodating portion 30 projects into the second flange pipe 3 and forms a weir 30 a around the opening of the ash accommodating portion 30.

The filter 1 is a general filter, for example, a honeycomb filter having a honeycomb-shaped partition wall made of a porous material, and one of two adjacent passages surrounded by the partition wall has an exhaust upstream side. The other side is closed with a ceramic closing member on the downstream side of the exhaust gas. As a result, the exhaust gas passes through the partition, and at that time, the particulates are collected by the partition made of a porous material. The filter 1 is provided with an electric heater.

If the amount of trapped particulates in the filter 1 is considerably increased, the exhaust resistance is greatly increased.
At this time, the electric heater is energized and heated to burn the particulates periodically. of course,
Instead of the electric heater or in addition to the electric heater, it is also possible to provide another particulate combustion means for supplying fuel and secondary air to the particulate collection filter.

By such a particulate combustion means, the combustible components of the particulates are removed from the filter. However, oxides or sulfides of calcium or phosphorus contained as particulate components are converted into ash without burning. Deposits on the particulate collection filter.

Such ash is discharged to the exhaust upstream side of the filter 1 by engine vibration at the time of starting or operation because the filter 1 is obliquely arranged with the exhaust upstream side down, and the ash accommodating section 30 Housed within. If the ash is not sufficiently discharged due to engine vibration, the filter may be provided with a vibrating device or any ash discharging means. The capacity of the ash storage unit is limited, and it is necessary to periodically discharge ash from the ash storage unit.

The exhaust gas contains water vapor. As a result, when the temperature of the engine exhaust system decreases after the engine stops, water vapor in the exhaust gas in the exhaust system is condensed on the inner wall surface of the exhaust system. Part of the water condensed on the inner wall surface of the second flange pipe 3 is transferred to the ash storage portion 30 located on the lower side along the inner wall surface.
Head to.

Ash has a high content of calcium sulfate as its component. Since calcium sulfate is a raw material for gypsum, if a large amount of water is present in the ash storage unit 30, the ash containing a large amount of calcium sulfate is sufficiently fixed in the ash storage unit, making it difficult to discharge from the ash storage unit. Become.

According to the structure of the present embodiment, the water flowing along the inner wall surface of the second flange pipe 3 toward the ash accommodating portion 30 is discharged from the weir 3 formed around the opening of the ash accommodating portion 30.
Oa prevents flow into the ash storage unit 30. As a result, since only water that has condensed in the ash storage unit 30 is present in the ash storage unit 30, the ash is not sufficiently fixed in the ash storage unit 30, and the ash is easily removed from the ash storage unit 30. Can be discharged.

FIG. 3 is a sectional view similar to FIG. 1 showing a second embodiment of the exhaust gas purifying apparatus for a diesel engine according to the present invention, and FIG. 4 is a sectional view taken along line BB of FIG. Only the differences from the first embodiment will be described below. As shown in FIGS. 3 and 4, in the present embodiment, a depression 30 b is formed around the opening of the ash accommodating portion 30.

According to such a structure, dew condensation occurs on the inner wall surface of the second flange pipe 3 and the ash accommodating portion 3 is formed along the inner wall surface.
The water heading to the ash storage part 3
Inflow to zero is prevented. Thereby, similarly to the first embodiment, the ash storage unit 3 includes the ash storage unit 3.
The ash can be easily discharged from the ash accommodating section 30 because there is only water condensed in the ash 0 and the ash does not sufficiently adhere in the ash accommodating section 30.

In the first and second embodiments described above, the ash storage portion 3 is provided outside the weir 30a and inside the depression 30b.
In order to accumulate dew condensation water heading to zero, a drain for periodically discharging this water may be provided.

FIG. 5 is a sectional view similar to FIG. 1 showing a third embodiment of the exhaust gas purifying apparatus for a diesel engine according to the present invention, and FIG. 6 is a sectional view taken along line CC of FIG. Only the differences from the first embodiment will be described below. As shown in FIGS. 5 and 6, in the present embodiment, a water absorption zone 30 c is arranged around the opening of the ash storage unit 30. This water absorption zone 3
0c is made of a porous material or a fiber material, and can absorb water.

According to such a structure, dew condensation occurs on the inner wall surface of the second flange pipe 3 and the ash accommodating portion 3 is formed along the inner wall surface.
The water going to zero is absorbed by the water absorption zone 30 and is prevented from flowing into the ash storage unit 30. Thereby, the first
As in the embodiment, since only water condensed in the ash accommodating portion 30 exists in the ash accommodating portion 30 and the ash is not sufficiently fixed in the ash accommodating portion 30, the ash is accommodated in the ash accommodating portion 30. It can be easily discharged from the part 30.

FIG. 7 is a sectional view similar to FIG. 1 showing a fourth embodiment of the exhaust gas purifying apparatus for a diesel engine according to the present invention, and FIG. 8 is a sectional view taken along line DD of FIG. Only the differences from the first embodiment will be described below. As shown in FIGS. 7 and 8, in the present embodiment, the ash storage unit 30 has a double structure including an inner wall 31 and an outer wall 32, and an air layer 30 d is provided around the ash storage unit 30. Is formed.

According to such a structure, after the engine is stopped, the ash accommodating portion 30 is kept warm by the air layer 30d, and the temperature is hardly lowered compared to the second flange tube 3. Thereby, the water vapor in the exhaust gas in the second flange pipe 3 and the ash storage part 30 is mainly dew-condensed on the inner wall surface of the second flange pipe 3 where the temperature is lowered quickly, and the ash storage part 3
When the temperature of the inner wall surface of the ash storage unit 3 decreases, the concentration of water vapor in the exhaust gas is considerably low.

The inner wall 31 forming the ash accommodating portion 30
Is supported by the support posts 33 and the like with respect to the outer wall 32,
The space that forms the air layer 30 d is open around the opening of the ash storage unit 30. As a result, a part of the water condensed in the second flange pipe 3 flows toward the ash accommodating portion 30 along the inner wall surface, but flows into the space forming the air layer 30 d, and enters the ash accommodating portion 30. Does not flow at all. As described above, since there is almost no water in the ash storage unit 30, the ash is stored in the ash storage unit 3.
The ash can be easily discharged from the ash accommodating portion 30 without being fixed at all in the area of zero.

FIG. 9 is a sectional view similar to FIG. 1 showing a fifth embodiment of the exhaust gas purifying apparatus for a diesel engine according to the present invention, and FIG. 10 is a sectional view taken along line EE of FIG. Only the differences from the fourth embodiment will be described below. 9 and 10
As shown in FIG.
Has a double structure consisting of an inner wall 34 and an outer wall 35, and a heat insulating material or a heat insulating material 30 e having a large heat capacity is arranged around the ash accommodating portion 30.

According to such a structure, after the engine is stopped, the ash accommodating portion 30 is kept warm by the heat retaining material 30e, and the temperature is hardly lowered as compared with the second flange tube 3. As a result, the water vapor in the exhaust gas in the second flange pipe 3 and the ash accommodating portion 30 mainly becomes
Dew condensation occurs on the inner wall surface of the flange pipe 3 and hardly forms on the inner wall surface of the ash storage unit 30.

The inner wall 34 forming the ash accommodating portion 30
The outer wall 3 near the opening of the ash storage unit 30
5, and the above-mentioned heat insulating material 30e is arranged in a closed space. Thus, unlike the fourth embodiment, part of the water condensed on the inner wall surface of the second flange pipe 3 flows into the ash accommodating portion 30 along the inner wall surface. However, since the dew condensation hardly occurs on the inner wall surface of the ash accommodating portion 30, the amount of water in the ash accommodating portion 30 can be reduced as compared with the conventional case, and the ash is sufficiently fixed in the ash accommodating portion 30. However, the ash can be easily discharged from the ash storage unit 30.

In the fourth embodiment, the inner wall 31
If the heat insulating material or the heat insulating material having excellent water resistance is arranged so as to be separated from the outer wall 32 around the surroundings, the heat insulating property in the ash accommodating portion 30 is improved, and the dew condensation on the inner wall surface of the second flange pipe 3 is achieved. As in the fourth embodiment, a part of the water that has flowed can be prevented from flowing into the ash storage unit 30.

FIG. 11 is a sectional view similar to FIG. 1 showing a sixth embodiment of the exhaust gas purifying apparatus for a diesel engine according to the present invention. Only the differences from the fifth embodiment will be described below. As shown in FIG. 11, in the present embodiment, the ash accommodating portion 30 has a double bottom structure, and an electric heater 30f is arranged in a space between the double bottom structures. The electric heater 30f is energized at least for a while after the engine stops.

According to such a structure, after the engine is stopped, the electric heater 30f is energized, so that the ash accommodating portion 30 is kept warm by the electric heater 30f and has a higher temperature than the second flange pipe 3. Is difficult to fall. Thereby, the water vapor in the exhaust gas in the second flange pipe 3 and the ash accommodating portion 30 is condensed mainly on the inner wall surface of the second flange pipe 3 as described above, and is hardly condensed on the inner wall surface of the ash accommodating portion 30. . Thereby, similarly to the fifth embodiment, the amount of water in the ash storage unit 30 can be reduced as compared with the conventional case, and the ash is stored in the ash storage unit 30.
The ash can be easily discharged from the ash accommodating portion 30 without being sufficiently fixed in the inside.

FIG. 12 is a sectional view similar to FIG. 2, showing a seventh embodiment of the exhaust gas purifying apparatus for a diesel engine according to the present invention. In the present embodiment, as shown in FIG. 12, cooling fins 3a are provided around the second flange pipe 3.

According to such a structure, after the engine is stopped, only the second flange pipe 3 is cooled by the cooling fins 3a at an early stage. Thereby, the water vapor in the exhaust gas in the second flange pipe 3 and the ash accommodating portion 30 is condensed mainly on the inner wall surface of the second flange pipe 3 as described above, and is hardly condensed on the inner wall surface of the ash accommodating portion 30. . Thereby, similarly to the fifth embodiment, the amount of water in the ash accommodating portion 30 can be reduced as compared with the related art, and the ash does not sufficiently adhere in the ash accommodating portion 30.
The ash can be easily discharged from the ash storage unit 30. In the present embodiment, other cooling means such as water cooling or air cooling may be arranged around the second flange pipe 3 instead of the cooling fins.

FIG. 13 is a sectional view similar to FIG. 2 showing an eighth embodiment of the exhaust gas purifying apparatus for a diesel engine according to the present invention. In the present embodiment, as shown in FIG. 13, at least one of the inner wall surface and the outer wall surface of the second flange pipe 3 is coated with a black body paint.

According to such a structure, the black body coating portion 3b
The emissivity of the second flange pipe 3
The temperature is increased as compared to 0, and after the engine is stopped, only the second flange pipe 3 is cooled early, so that the temperature is easily lowered as compared with the ash storage section 30. Thereby, the second
Water vapor in the exhaust gas in the flange pipe 3 and the ash storage part 30 is condensed mainly on the inner wall surface of the second flange pipe 3 and hardly condenses on the inner wall surface of the ash storage part 30 as described above. Thereby, similarly to the fifth embodiment, the amount of water in the ash accommodating portion 30 can be reduced as compared with the related art, and the ash is not sufficiently fixed in the ash accommodating portion 30 and the ash is stored It can be easily discharged from the part 30.

In the present embodiment, a heat insulator that covers the second flange pipe 3 and the entire ash accommodating portion 30 is provided, and the second flange pipe 3 of the heat insulator is provided.
A black body paint may be applied to at least one of the inner surface and the outer surface of the portion facing the surface. In order to increase the emissivity of the second flange pipe 3, the second flange pipe 3
The surface roughness of at least one of the inner wall surface and the outer wall surface may be made coarser than that of the ash accommodating portion 30.

FIG. 14 is a sectional view similar to FIG. 1 showing a ninth embodiment of the exhaust gas purifying apparatus for a diesel engine according to the present invention. In the present embodiment, as shown in FIG. 14, at least a part of the ash accommodating portion 30, for example, a bottom wall is in contact with or close to the upstream exhaust pipe 4 of the second flange pipe 3.

During the operation of the engine, in the engine exhaust system, the higher the temperature on the exhaust upstream side, which is closer to the engine body, the higher the temperature. As a result, the temperature of the upstream exhaust pipe 4 is higher than that of the second flange pipe 3 and the ash storage section 30, and the ash storage section 30 that comes into contact with or comes close to the upstream exhaust pipe 4 after the engine stops. The temperature is hardly lowered compared to the two-flange tube 3. Therefore, the second flange pipe 3 and the ash accommodating section 3
As described above, the water vapor in the exhaust gas in the pipe 0 mainly forms dew on the inner wall surface of the second flange pipe 3 and hardly forms dew on the inner wall surface of the ash accommodating section 30. Thereby, similarly to the fifth embodiment, the amount of water in the ash storage unit 30 can be reduced as compared with the conventional case, and the ash is stored in the ash storage unit 3.
The ash is not sufficiently fixed within 0, and the ash can be easily discharged from the ash accommodating portion 30.

In all of the above-described embodiments, the filter for collecting particulates is disposed obliquely with the exhaust upstream side downward so as to discharge ash to the filter exhaust upstream side by engine vibration. The present invention is not limited to the present invention, and can be arranged so that the ash is discharged to the exhaust upstream side of the filter by any selected ash discharging means.

Any combination in all of the above-described embodiments can be performed as freely as possible. Also,
In all the embodiments, the ash is discharged from the ash storage unit 30 by, for example, forming a normally-closed discharge port below the ash storage unit 30, and performing manual or exhaust gas pressure from the discharge port. be able to.

[0045]

As described above, according to the exhaust gas purifying apparatus for a diesel engine according to the first aspect of the present invention, since the weir is provided around the opening of the ash accommodating section, the engine is stopped after the engine stops. Water condensed on the inner wall surface of the exhaust passage is prevented from flowing into the ash storage unit, and ash containing calcium sulfate, which is a raw material of gypsum, does not sufficiently adhere in the ash storage unit. Can be easily discharged.

According to the exhaust gas purifying apparatus for a diesel engine according to the second aspect of the present invention, the water storage section is provided around the opening of the ash accommodating section.
The same effect as the exhaust gas purifying apparatus for a diesel engine described in (1) can be obtained.

Further, according to the exhaust gas purifying apparatus for a diesel engine according to the third aspect of the present invention, since the heat retaining means is provided in the ash accommodating section, the exhaust passage is moved from the ash accommodating section after the engine is stopped. Early low temperature,
By actively condensing the water vapor in the exhaust gas on the inner wall of the exhaust passage, dew condensation in the ash storage section is prevented,
Since the ash is not sufficiently fixed in the ash accommodating portion, the ash can be easily discharged from the ash accommodating portion.

According to the exhaust gas purifying apparatus for a diesel engine according to the fourth aspect of the present invention, the cooling means is provided in the engine exhaust passage on the exhaust gas upstream side of the filter. The temperature of the exhaust passage becomes lower at a temperature earlier than that of the ash accommodating portion, and the same effect as the exhaust gas purifying apparatus for a diesel engine according to the third aspect can be obtained.

According to the exhaust gas purifying apparatus for a diesel engine according to the fifth aspect of the present invention, the emissivity of the ash accommodating portion is made smaller than the emissivity of the engine exhaust passage on the exhaust gas upstream side of the filter. After the engine stopped, the temperature of the exhaust passage became low earlier than the ash storage section,
The same effect as the diesel engine exhaust gas purification device according to the third aspect can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a part of an engine exhaust system showing a first embodiment of an exhaust gas purifying apparatus for a diesel engine according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view similar to FIG. 1, showing a second embodiment of the exhaust gas purifying apparatus for a diesel engine according to the present invention.

FIG. 4 is a sectional view taken along line BB of FIG. 3;

FIG. 5 is a sectional view similar to FIG. 1, showing a third embodiment of the exhaust gas purifying apparatus for a diesel engine according to the present invention.

FIG. 6 is a sectional view taken along the line CC of FIG. 5;

FIG. 7 is a sectional view similar to FIG. 1, showing a fourth embodiment of the exhaust gas purifying apparatus for a diesel engine according to the present invention.

8 is a sectional view taken along the line DD of FIG. 7;

FIG. 9 is a sectional view similar to FIG. 1 showing a fifth embodiment of the exhaust gas purification apparatus for a diesel engine according to the present invention.

FIG. 10 is a sectional view taken along line EE of FIG. 9;

FIG. 11 is a sectional view similar to FIG. 1, showing a sixth embodiment of the exhaust gas purifying apparatus for a diesel engine according to the present invention.

FIG. 12 is a sectional view similar to FIG. 2, showing a seventh embodiment of the exhaust gas purification apparatus for a diesel engine according to the present invention.

FIG. 13 is a sectional view similar to FIG. 2, showing an eighth embodiment of the exhaust gas purification apparatus for a diesel engine according to the present invention.

FIG. 14 is a sectional view similar to FIG. 1, showing a ninth embodiment of the exhaust gas purification apparatus for a diesel engine according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Filter 2 ... 1st flange pipe 3 ... 2nd flange pipe 3a ... Fin 3b ... Black body coating part 30 ... Ash accommodating part 30a ... Weir part 30b ... Depression part 30c ... Water absorption zone 30d ... Air layer 30e ... Heat insulation or heat insulation Material 30f ... heater

Claims (5)

[Claims] 1. A filter for collecting particulates disposed in an engine exhaust passage, and a concave ash accommodating portion having an opening to the engine exhaust passage near an exhaust upstream side of the filter. An exhaust purification device for a diesel engine, wherein a weir is provided around the opening of the ash storage unit. 2. A filter for collecting particulates arranged in an engine exhaust passage, and a concave ash accommodating portion having an opening to the engine exhaust passage near an exhaust upstream side of the filter, An exhaust gas purification device for a diesel engine, wherein a water storage section is provided around the opening of the ash storage section. 3. A filter for collecting particulates disposed in an engine exhaust passage, and a concave ash accommodating portion having an opening to the engine exhaust passage near an exhaust upstream side of the filter. An exhaust gas purification device for a diesel engine, wherein a heat retaining means is provided in an ash accommodating portion. 4. A filter for collecting particulates arranged in an engine exhaust passage, and a concave ash accommodating portion having an opening to the engine exhaust passage near an exhaust upstream side of the filter, An exhaust purification device for a diesel engine, wherein cooling means is provided in the engine exhaust passage on the exhaust upstream side of a filter. 5. A filter for collecting particulates arranged in an engine exhaust passage, and a concave ash accommodating portion having an opening to the engine exhaust passage near an exhaust upstream side of the filter. An exhaust gas purification apparatus for a diesel engine, wherein an emissivity of an ash accommodating portion is made smaller than an emissivity of the engine exhaust passage on an exhaust gas upstream side of the filter.