JPH04103214U - Internal combustion engine exhaust aftertreatment device - Google Patents

Abstract

(57) [Summary] [Purpose] To spray fuel onto a catalyst-equipped filter for collecting exhaust particulates to promote regeneration of the filter, by uniformly supplying fuel to the front of the filter and preventing uneven combustion. . Structure: A catalyst-equipped filter 3 made of ceramics or the like for collecting exhaust particulates is disposed in a casing 4, and a thin fuel-trapping filter 9 is disposed in front of it. The fuel trapping filter 9 has relatively coarse mesh so that particulates can pass therethrough. Further, a fuel injection valve 6 is arranged toward the fuel trapping filter 9. The fuel trapping filter 9 and the catalyst-equipped filter 3 have an elliptical shape so as to follow the spray shape of the fuel injection valve 6.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This idea is mainly based on carbon particles emitted from internal combustion engines such as diesel engines. The present invention relates to an exhaust aftertreatment device for collecting and removing exhaust particulates such as particles.

0002

[Conventional technology]

For example, in order to treat carbon particulates that are a problem in diesel engines, In exhaust aftertreatment equipment that has a filter installed in the system, back pressure increases due to clogging can be avoided. In order to avoid It is necessary to revitalize the country. Generally, filters with deposits of particulate matter are exhausted by exhaust heat. In order to regenerate by In the engine operating range corresponding to normal city driving, the exhaust temperature is between 200℃ and 300℃. Therefore, reliable regeneration of the filter cannot be expected.

0003 Therefore, in the past, a catalyst was supported on the filter and a fuel injection device was installed. There is a known device that performs forced regeneration.

0004 FIG. 7 shows an example of the exhaust aftertreatment described in Japanese Patent Application Laid-open No. 122721/1983. The device is shown in which an exhaust passage 12 of an internal combustion engine 11 is made of, for example, a three-dimensional porous body. A ceramic filter 13 is interposed, and the filter 13 is provided with an oxidizing catalyst. Coated with medium. Then, an exhaust passage 12 upstream of the filter 13 An electromagnetic valve type fuel injection valve 14 is disposed in the fuel injection valve 14, and the fuel pressurized by the pump 15 is injected into the fuel injection valve 14. is injected and supplied into the exhaust passage 12 at an appropriate regeneration timing. This way According to the combination of a sea urchin catalyst and fuel injection, the heat of reaction between the fuel and the catalyst is used. A relatively low exhaust temperature, e.g. 150°C, can initiate particulate combustion The filter can be regenerated to a certain degree.

[0005]

[Problem that the idea aims to solve] However, in the above-mentioned conventional exhaust aftertreatment device, the fuel injection valve 14 injects The injected fuel spray collides with the wall surface of the exhaust passage 12 upstream of the filter 13. Therefore, most of the injected fuel adheres to the wall of the exhaust passage 12 and flows downstream. Therefore, it is difficult to distribute the particles uniformly on the filter 13.

[0006] Therefore, the filter 13 cannot be regenerated uniformly, and for example, the filter 13 cannot be regenerated uniformly. During the next regeneration, a large amount of particulate matter accumulates and the filter 13 becomes too hot during the next regeneration. There was a risk of burnout, etc.

[0007] Moreover, a large amount of fuel accumulates near the surrounding passage walls, making it difficult for the catalyst and Since it cannot come into contact with oxygen, the fuel components are not sufficiently oxidized and are emitted directly into the atmosphere. There is a possibility that it will be lost.

[0008] In addition, in order to avoid the fuel wall flow as described above, the Although it is possible to inject direct fuel, generally the spread angle of the fuel injector's spray Since the angle is about 20 to 30 degrees, it is difficult to spray over a wide area, and the filter It is not possible to uniformly distribute the fuel in the tank 13. In particular, in this case, the filter A large amount of fuel accumulates in the center of the tank 13 and is not sufficiently oxidized and is discharged downstream. At the same time, fuel tends to run out in the surrounding areas.

[0009]

[Means to solve the problem]

Therefore, this idea was developed to use a catalyst installed in the exhaust passage of an internal combustion engine to collect exhaust particulates. An internal combustion engine equipped with a media filter and a fuel injection device for regenerating this filter. In an engine exhaust aftertreatment device, the filter is formed to have an elliptical cross section and , located at a predetermined distance from the front surface, has an elliptical shape that is approximately the same as the above filter. A fine-mesh fuel capture filter is provided, and the fuel injection device is the fuel trapping filter so that its shadow shape approximately matches the front shape of the fuel trapping filter. It is characterized by being arranged diagonally toward the filter.

0010

[Effect]

In the above configuration, the fuel capture filter has relatively coarse mesh, so it is difficult to remove carbon, etc. Particulates pass through this fuel trapping filter and are collected by the catalyst-equipped filter.

[0011] On the other hand, the fuel spray injected from the fuel injection device at the appropriate regeneration timing Since the particle size is very large compared to exhaust particulates, they are captured by the fuel capture filter, It spreads over the entire surface of the fuel trapping filter. Here, the fuel capture filter is installed diagonally. An elliptical shape that approximately matches the projected shape of the fuel spray that is injected conically from the opposite direction. As a result, fuel adheres to the entire surface more evenly.

0012 The fuel adhering to the entire surface of this fuel trapping filter is then blown away by the exhaust flow. The particles are blown away, further atomized, and distributed almost uniformly on the front surface of the catalyst-equipped filter located downstream. Attach to. This fuel uniformly promotes regeneration of the catalytic filter in all parts. .

[0013]

【Example】

Hereinafter, one embodiment of this invention will be described in detail based on the drawings.

[0014] FIG. 3 shows an embodiment of the exhaust aftertreatment device according to this invention, in which an internal combustion engine 1 A catalyst-equipped filter 3 for collecting exhaust particulates is interposed in the exhaust passage 2 together with a casing 4. equipped.

[0015] As shown in FIGS. 1 and 2, the casing 4 has a larger cross section than the exhaust passage 2. It has a flat elliptical cross-sectional shape. And on one side there is a roughly conical shape. A substantially conical inlet portion 4a is formed on the other side, and a substantially conical outlet portion 4b is formed on the other side. It is connected to the rear exhaust passage 2. Further, a cylindrical cylinder is provided on one side of the inlet portion 4a. A shaped fuel spray introduction pipe 5 is formed protrudingly.

[0016] The fuel spray introduction pipe 5 is arranged at an angle of, for example, 60° with respect to the central axis of the fuel passage 2. It is formed in a somewhat slanted state, and at the bottom there is an electric terminal that is the main part of the fuel injection device. A magnetic valve type fuel injection valve 6 is attached. In addition, the injection direction of the fuel injection valve 6 is coaxial with the fuel spray introduction pipe 5, and the fuel spray spreads in a conical shape (its spread The diameter of the fuel spray introduction pipe 5 is set so as not to interfere with the angle shown as θ). There is.

[0017] As shown in FIG. 3, the fuel injection valve 6 is pressurized by a fuel pump 7. Fuel is being supplied, and the fuel injection valve 6 is opened by a drive signal from the control circuit 8. Then, fuel is injected into the casing 4.

[0018] The catalyst filter 3 is a three-dimensional ceramic porous body (so-called ceramic foam) or metal mesh structures made by laminating many thin metal plates with lattice-like meshes, etc. It consists of exhaust particulates such as carbon (usually, the particle size is about 0.1 to 0.2 μm) The coarseness of the mesh and the length in the axial direction are set so that it can sufficiently collect In addition, a catalyst such as palladium is supported on the surface. And the above catalyst The attached filter 3 has an elliptical cross section along the casing 4, and is provided with a cushioning material (not shown). and is held within the casing 4.

[0019] In front of the catalyst filter 3, there is a relatively thin (short axial length) fuel trap. A filter 9 for use is provided. This fuel trapping filter 9 is a filter with a catalyst. Similar to 3, it is formed from a three-dimensional porous ceramic body or a metal structure. However, unlike the catalyst-equipped filter 3, no catalyst is supported. Also, this fuel trap The trapping filter 9 traps fuel spray (spray particle size is approximately 200 μm). However, the eyes are designed to allow exhaust particulates such as fine carbon to pass through without being collected. The roughness is set relatively large.

[0020] The fuel trapping filter 9 has the same elliptical shape as the catalyst-equipped filter 3. None, it is held within the casing 4 via a cushioning material (not shown).

[0021] Here, the fuel trapping filter 9 is arranged at a predetermined distance from the front surface of the catalyst-equipped filter 3. located at a remote location and arranged perpendicular to the central axis of the exhaust passage 2 . Furthermore, the projected shape of the fuel spray injected from the fuel injection valve 6 described above and the fuel capture The front shape of the trapping filter 9 substantially matches. In other words, it is sprayed from an angle. Projected shape of a conical fuel spray cut perpendicular to the central axis of the exhaust passage 2 The injection direction and the elliptical shape of the fuel capture filter 9, etc. are set to match the It is.

[0022] In the configuration of the above embodiment, exhaust particulates such as carbon emitted from the internal combustion engine The fuel passes through the coarse fuel trapping filter 9 as it is, and then passes through the downstream filter with catalyst. It is collected in 3. Then, the engine is operated at a certain high speed and high load range, and the exhaust temperature When the temperature reaches about 400℃, the particulate matter that had accumulated on the filter 3 due to the catalytic action The fuel will be re-burned and the filter 3 will be regenerated naturally.

[0023] On the other hand, if operating conditions with low exhaust gas temperature, equivalent to city driving, continue for a long time, Since regeneration by air heat alone cannot be expected, the cumulative mileage and driving time when driving at low speeds The control circuit 8 controls the combustion based on the integrated value or the detection of the differential pressure across the filter 3. An appropriate amount of fuel is injected from the fuel injection valve 6. This fuel spray is produced by a fuel trapping filter. The particles collide with the filter 9, are captured by the filter 9, and spread over the entire surface thereof. Here, the fuel trap Since the front shape of the trapping filter 9 approximately matches the projected shape of the spray, the filter Fuel is sprayed evenly over the entire surface of the tank 9.

[0024] The fuel adhering to the fuel trapping filter 9 in this way is removed by the exhaust flow. It is blown away and adheres to the front surface of the catalyst-equipped filter 3 located downstream. Therefore, touch The fuel can be evenly deposited on the front surface of the mediated filter 3, and the catalytic action Uniform regeneration of each part is possible with a low exhaust temperature of about 50 to 200℃. Becomes Noh.

[0025] 4 to 6 model the fuel trapping filter 9 as a simple grid-like network structure. FIG. 4 is an explanatory diagram showing that the exhaust flow flows through the fuel capture filter as shown by arrow A. While the fuel spray enters the router 9 vertically, it collides from an oblique direction as shown by arrow B. do. Therefore, when viewed from the exhaust flow direction, the lattice pattern that looks like Figure 5 is When viewed from the fuel spray direction, the actual grid spacing changes as shown in Figure 6. L becomes smaller. In the illustrated example, in order to inject fuel at an inclination angle of 60°, the grid The interval L is L/2.

[0026] Therefore, the network structure becomes dense for fuel spray, and as a result, fuel particles cannot pass through. It is captured reliably without being lost.

[0027] On the other hand, the mesh structure is coarse for the exhaust flow, so the fuel capture filter Once the fuel has adhered to 9, it is easily blown away by the exhaust flow and is ensured to flow downstream. It will be done. When the fuel leaves the fuel trapping filter 9 and flows downstream in this way, , the fuel particles become even more atomized, so that they adhere more uniformly to the catalyst-equipped filter 3. At the same time, it comes into sufficient contact with the catalyst of the catalyst-equipped filter 3, and oxidation and heat generation occur quickly. will be started on.

[0028] Additionally, this forced regeneration by supplying fuel is generally carried out when the exhaust temperature is low. However, since the fuel trapping filter 9 is thin and has a small heat capacity, it absorbs exhaust heat. Therefore, it is easily heated. Therefore, the fuel collides toward this fuel trapping filter 9. By doing so, the fuel becomes easier to atomize.

[0029]

[Effect of the idea]

As is clear from the above explanation, the exhaust aftertreatment device for internal combustion engines according to this invention If so, insert it diagonally into a coarse fuel trapping filter that has an oval shape to match the spray projection shape. The fuel is collided with the fuel from the direction, and then the exhaust flow causes the front surface of the catalyst-equipped filter downstream. When injecting fuel directly to the filter with catalyst, Compared to this, fuel components can be supplied very evenly to the front of the filter with catalyst, It can be brought into efficient contact with the catalyst and oxygen. Therefore, it is equivalent to city driving. This makes it possible to uniformly regenerate each part of the catalyst-equipped filter even at low exhaust temperatures. follow Therefore, the filter may be burnt out due to rapid combustion of locally deposited large amounts of particulate components. Otherwise, the supplied fuel components are not sufficiently oxidized and are discharged to the outside. It is possible to prevent such problems.

[Brief explanation of drawings]

FIG. 1 is a sectional view of essential parts showing an embodiment of this invention.

FIG. 2 is a side view as well.

FIG. 3 is an explanatory diagram showing the overall configuration of the exhaust aftertreatment device.

FIG. 4 is an explanatory diagram showing a model of the lattice spacing of the fuel trapping filter.

FIG. 5 is an explanatory diagram showing a lattice pattern when this modeled fuel trapping filter is viewed from the exhaust flow direction.

FIG. 6 is an explanatory diagram showing a lattice pattern similarly viewed from the fuel spray direction.

FIG. 7 is an explanatory diagram showing an example of a conventional exhaust aftertreatment device.

[Explanation of symbols]

3... Filter with catalyst 6...Fuel injection valve 9...Fuel capture filter

Claims (1)

[Scope of utility model registration request] 1. An exhaust aftertreatment device for an internal combustion engine, comprising: a filter with a catalyst for collecting exhaust particulates installed in an exhaust passage of the internal combustion engine; and a fuel injection device for regenerating the filter; The filter is formed to have an elliptical cross section, and a fine fuel trapping filter having substantially the same elliptical shape as the filter is disposed at a predetermined distance from the front surface of the filter, and the fuel injection device is configured to include: An exhaust aftertreatment device for an internal combustion engine, characterized in that the spray is disposed obliquely toward the fuel trapping filter so that the projected shape of the spray substantially matches the front shape of the fuel trapping filter.