JPH0217136Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to an exhaust gas purification device for a diesel engine.

Prior Art In order to prevent exhaust particulates contained in the exhaust gas of a diesel engine from being released into the atmosphere, ideas have been made to place a filter in the middle of the exhaust pipe. A typical example of such a filter is a honeycomb filter.
As shown in FIG. 1, this has a honeycomb structure consisting of a large number of cells extending substantially parallel to each other across thin walls in the axial direction of the filter, and these cells are divided into a first cell group 14 and a second cell group 15. It is separated into two parts, and one end of each part is sealed tightly. When exhaust gas flows in the direction of arrow A in Fig. 1, particulates 17 tend to accumulate in the seal plug facing in the direction of flow of exhaust gas, and if additives are mixed in the fuel, the components is easy to adhere to. Therefore, the entrance area of the cell 14 into which the exhaust gas is introduced becomes smaller, and the pressure loss of the exhaust gas becomes larger.
Fuel efficiency worsens.

Purpose of the invention In view of the above, the purpose of the invention is to prevent adhesion near the cell inlet by devising the inlet end face of the honeycomb filter, and even if adhesion occurs, the inlet area will not be narrowed and an increase in pressure loss will be prevented. The object of the present invention is to obtain a diesel exhaust purification device that is similar to the above.

Structure of the invention According to the invention, a honeycomb filter is disposed in the middle of the exhaust pipe, and the honeycomb filter has a honeycomb structure consisting of a large number of cells extending substantially parallel to each other across thin walls in the axial direction of the filter. The cells are separated into a first cell group and a second cell group, and one end face on the opposite side of each is sealed, and all the sealed parts facing the exhaust gas flow direction form a polygonal pyramid shape from the end face of the honeycomb filter. Provided is a diesel exhaust gas purification device characterized in that it is formed in a protruding manner and that exhaust gas is guided along the slope portion of the polygonal pyramid shape.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In Figure 2, 1 is a diesel engine, 2
is the fuel tank. A known fuel supply system is supplied with a fuel tank 2, a supply pipe 3, and a fuel injection pump 4, and the supply pipe 3 includes a fuel filter 5,
and a fuel sedimentor 6 are arranged. 7 is a return pipe. On the other hand, an additive tank 8 is provided and connected to the fuel supply pipe 3 through a supply pipe 9.
An additive supply pump 10 is arranged in the additive supply pipe 9 . The additive is appropriately selected from manganese, calcium, copper, lead, etc., and is used to lower the ignition temperature of particulates in the exhaust gas. The additive supply pump 10 mixes the additive into the fuel in an optimally small amount.

Exhaust pipe 1 connected from exhaust manifold 11
A filter 13 is placed in the middle of 2.

This filter 13 is a honeycomb filter as shown in FIG. The honeycomb filter 13 is made up of a large number of cells 1 extending substantially parallel to the axial direction of the filter across a thin wall 18 made of porous ceramic.
It has a honeycomb structure consisting of 4,15 pieces. These cells 14, 15 are separated into two groups by seal plugs 16, 19. The first group of cells 14 are hermetically sealed with a seal plug 19 on the right end surface in FIG. 3, and their left end portions are opened to serve as an exhaust gas inlet. Conversely, the left end faces of the second group of cells 15 are sealed by seal plugs 16, and their right ends are opened to serve as exhaust gas outlets. That is, the exhaust gas flows along arrow A, crosses the thin wall 18 from the first group of cells 14 as arrow B, and exits from the second group of cells 15.
It is filtered at this time. Incidentally, a general cell arrangement is shown in FIG.

The feature of the present invention lies in the shape of the seal plug 16 facing the exhaust gas flow direction as shown in FIG. These seals 1
6 all protrude from the end face of the honeycomb filter 13 and are formed into a quadrangular pyramid shape that is pointed outward.
For this reason, the portion of the exhaust gas that has flowed toward the front of the seal plug 16 does not hit the surface of the square pyramid-shaped inclined surface of the seal plug 16 at right angles, and as shown by arrow A, the portion of the exhaust gas that has flowed toward the front of the seal plug 16 It is guided to the adjacent cell 14 along the surface of the quadrangular pyramid-shaped inclined surface so as to be substantially parallel to the same surface. Not only exhaust particles but also sticky substances, for example, can easily adhere to a wall surface if it is sprayed at a right angle to the wall surface, but it is difficult to adhere to the wall surface if the same sticky substance is sprayed at an angle to the wall surface. Therefore, the exhaust particles are less likely to adhere to the square pyramid-shaped seal plug 16. For exhaust particulates that have adhered to the seal plug 16,
Close the plug 1 so that the exhaust gas is shown by arrow A.
Since the air flows parallel to the surface of the slope portion 6, it exerts a shearing action on the attached exhaust particles, causing them to fall off before they grow large. Therefore, the inlet area of the upstream open end of the cell 14 adjacent to the seal plug 16 is not narrowed. For this reason, the angle defined by θ in FIG. 3 is preferably less than 45 degrees. This feature is even more effective when combined with an engine in which additives are mixed into the fuel as described in FIG. This is because the mixture of additives lowers the ignition temperature of particulates in the exhaust gas, and therefore the filter 13 not only captures the particulates, but also re-burns them and processes them before they are released to the outside. Because it will be done. However, ash tends to be generated in the exhaust gas due to the additives, and these tend to adhere as shown at 17 in FIG. 1, resulting in a narrowing of the inlet area. Therefore, if the seal plug 16 is formed as shown in FIG. 3, such adhesion of ash will be prevented and the advantages of the additive can be brought out.

Effects of the Invention As explained above, according to the present invention, all the seal plugs facing the exhaust gas flow direction are formed in a polygonal pyramidal shape protruding from the end face of the honeycomb filter, and the exhaust gas is directed into the polygonal pyramidal shape. Since the filter is guided along the slope, adhesion of particulates to the filter inlet is prevented or alleviated, thereby suppressing the increase in pressure loss and achieving both exhaust gas purification performance and engine performance.

[Brief explanation of the drawing]

Fig. 1 is a partial cross-sectional view of a conventional honeycomb filter, Fig. 2 is a schematic configuration diagram of a diesel engine applied to the present invention, Fig. 3 is a partial cross-sectional view of a honeycomb filter according to the present invention, and Fig. 4 is a partial cross-sectional view of a honeycomb filter according to the present invention. FIG. 2 is a schematic diagram showing the front side of the honeycomb filter shown in the figure. 1... Diesel engine, 13... Honeycomb filter, 14, 15... Cell, 16, 19, 2
0...Dense pillar, 18...Thin wall.

Claims (1)

[Scope of utility model registration request] A honeycomb filter is disposed in the middle of the exhaust pipe, and the honeycomb filter has a honeycomb structure consisting of a large number of cells extending substantially parallel to each other in the axial direction of the filter with a thin wall in between, and the large number of cells is a first cell group. The cells are separated into a second cell group, and one end face on the opposite side of each is hermetically plugged, and all the hermetic plugs facing the exhaust gas flow direction are formed in a polygonal pyramidal shape protruding from the end face of the honeycomb filter, and the exhaust gas A diesel exhaust purification device characterized in that the fuel is guided along the polygonal pyramidal slope to the opening of an adjacent cell.