JP3249740B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine, and more particularly to an exhaust gas purifying apparatus capable of effectively removing exhaust particulates such as black smoke and nitrogen oxides contained in exhaust gas. Related to the device.

[0002]

2. Description of the Related Art For example, since the exhaust gas of a diesel engine contains a large amount of exhaust fine particles, that is, particulates, a honeycomb structure for collecting the particulates is mounted in the exhaust system. . This honeycomb structure is composed of a number of elongated filter cells defined in a honeycomb (honeycomb) shape by partitions of a porous ceramic material, and one end of each cell is usually closed by a plug member, Between adjacent filter cells, the plug members are located on opposite sides of each other.
Accordingly, the exhaust gas flowing from one filter cell enters the adjacent filter cell through the partition and flows out from the open end of the cell. When passing through the partition, the particulates in the exhaust gas are captured by the partition.

[0003] In such a filter, a catalyst is coated on a ceramic material (eg, cordierite ceramics) as a forming material, and in addition to the original collection of particulates, nitrogen oxides which are considered harmful are coated. Some have also tried to remove.

[0004]

By the way, when the amount of particulates stored in the filter increases as the filter is used, the air permeability gradually deteriorates, and the engine performance also decreases. In the filter coated with the catalyst, the accumulated particulates gradually cover the catalyst, so that the catalyst performance is reduced and the nitrogen oxide purification rate is deteriorated. For this reason, the filter itself must be periodically regenerated in accordance with the amount of trapped particulates. At present, in the filter regeneration process, an electric heater is provided near the end face and the outer periphery of the filter to periodically energize and heat to ignite and burn the particulates in the filter. For the purpose of curated combustion propagation, a regeneration gas typified by, for example, air or exhaust gas is introduced.

Accordingly, the exhaust gas purifying apparatus provided with the regenerating device generally has a complicated structure and a high manufacturing cost. Further, at the time of the regenerating operation, a large amount of battery power is required for energizing the heater. There is a problem of consumption.

The present invention has been made in view of the above-mentioned problems of the conventional exhaust gas purifying apparatus, and has always been capable of effectively purifying particulates and nitrogen oxides in exhaust gas without using means such as an electric heater. An object of the present invention is to provide a possible exhaust gas purification device.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust gas purifying apparatus provided in an exhaust system of an internal combustion engine for removing fine particles and nitrogen oxides in exhaust gas, which is connected to an exhaust passage of the internal combustion engine. A cylindrical casing, a honeycomb structure in which a number of cells arranged in the casing and partitioned by a ceramic partition and extending in the exhaust gas flow direction are arranged in a honeycomb shape, and a space inside the casing.
And a plurality of hollow ceramic spheres filled around the honeycomb structure .

[0008] Preferably, in this exhaust gas purification apparatus,
The honeycomb structure is disposed on the exhaust upstream side in the casing, and is guided into the casing.
Of the exhaust gas flowing into the cell,
Exhaust dynamic pressure changes to high static pressure in the cell space
It is configured to

[0009] More preferably, the honeycomb structure is formed of cordierite ceramics.

The hollow spheres each have a thickness of 0.3 m.
It is preferable that it is formed of a ceramic material having an outer dimension of not more than m and a diameter of not more than 3 mm and having far-infrared ray generation characteristics.

In the exhaust gas purifying apparatus, it is preferable that the casing is formed of a stainless steel plate or Ulster steel plate in a cylindrical shape.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an exhaust gas purifying apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a longitudinal section of an exhaust gas purifying apparatus according to the present invention.

Referring to FIG. 1, reference numeral 1 denotes an exhaust gas purifying apparatus mounted on an exhaust system of an internal combustion engine (for example, a diesel engine) not shown, and arrows in the figure show the flow direction of exhaust gas discharged from the engine body. ing. As is apparent from this figure, this exhaust gas purification apparatus 1 has a substantially cylindrical casing 2 made of a stainless steel plate or Ulster steel plate.
And both ends thereof are connected to an exhaust pipe 3a extending from the engine main body and an exhaust pipe 3b for discharging purified exhaust gas, respectively.

In the casing 2, a circular stainless steel net 4 and a stainless steel punching plate 5 adjacent to the circular net 4 are arranged near both ends in the axial direction. FIGS. 2 and 3 show the end faces of the stainless steel net 4 and the punching plate 5, respectively.

As shown, the net 4 is formed, for example, by knitting a large number of stainless steel wires, and the pieces and the punching plate 5 are formed by making a large number of holes in a single stainless steel plate. Each is provided for holding a ceramic material described later.

In the space inside the casing 2 sandwiched between the two sets of nets 4 / punching plates 5, a honeycomb structure 6 is provided adjacent to the exhaust upstream side punching plate 5.
Are arranged, and the remaining space is filled with countless ceramic balloons 7.

The honeycomb structure 6 has a rectangular cross section as shown in FIG. 4 and is made of, for example, a heat-resistant ceramic such as cordierite or mullite, and is formed of a casing 2 by a frame 9 joined to the punching plate 5 on the exhaust upstream side. It is held almost in the center. The structure is
As shown in FIG. 1, it is composed of a number of honeycomb cells 11 defined by cell partition walls 10 and extending in the exhaust gas flow direction.

On the other hand, the ceramic balloon 7 is made of a ceramic material capable of radiating far-infrared rays. Each of the ceramic balloons 7 has a hollow inside to reduce the heat capacity so that the surface can be effectively heated with a small amount of heat. It is formed as a small hollow spherical body (within a diameter of 3 mm and a wall thickness of preferably 0.3 mm). These ceramic balloon particles were placed on a stainless steel punching plate 5 as shown in FIG.
The space between the casings is filled without gaps by omitting the honeycomb structure 6, and microscopically, as shown in FIG. 5, for example, between three adjacent balloons 7a, 7b, 7c in one layer, It is preferable to fill as densely as possible a single crystal structure so that one of the balloons 7d of the layer enters.

The exhaust gas purifying operation of the exhaust gas purifying apparatus 1 configured as described above will be described below. The exhaust gas discharged from the engine body by the engine operation flows inside the exhaust pipe 3a under the exhaust dynamic pressure, is guided into the casing 2 of the exhaust gas purification device 1, further passes through the net 4 and the punching plate 5, A part thereof flows into the honeycomb cells 11 of the honeycomb structure 6, and the rest flows into a filling region of the ceramic balloon 7.

At this time, the exhaust dynamic pressure, which is the flow energy of the exhaust gas, changes to a high static pressure in the space inside each honeycomb cell, and the temperature of the exhaust gas further rises with the increase in the pressure, and the honeycomb structure The temperature of the body itself will also rise.

On the other hand, in the filling region of the ceramic balloon 7, due to the densely arranged structure described above, exhaust waves (also called exhaust pulsation) from the exhaust upstream side pass through the gaps between the balloons and the gap, and the ceramic balloon 7 of the next layer is discharged. It hits the center (see FIG. 5), and the vibration of all the balloons in this way modulates them into microwaves. As a result, the microwaves generated in the balloon filling region induce far infrared rays in the ceramic balloon 7 itself, and increase the temperature of the balloon. Accordingly, the above-described heat storage effect of the honeycomb structure 6 is also helped, and finally, the temperature of the ceramic balloon 7 reaches a high temperature of 600 to 800 ° C., and the inner surface of the honeycomb cell 11 and the outer surface of each ceramic balloon 7 Particulates such as attached black smoke are burned.

At this time, the steam contained in the exhaust gas changes into superheated steam (super steam) by passing through a high temperature range of 600 to 800 ° C.
This super steam has an effect as a catalyst that further promotes the oxidative combustion reaction of particulates (particularly carbon) due to its activity, and liberates oxygen (Ox) from nitrogen oxides (NOx) in exhaust gas. This has the effect of supplying oxygen to the particulate combustion described above. As a result, the exhaust gas passing through the present exhaust gas purification device 1 is effectively removed of particulates and nitrogen oxides by the honeycomb structure 6 and the ceramic balloon 7, and colorless and odorless to the exhaust downstream side. Exhaust gas can be discharged in a close state.

As described above, according to this embodiment, by filling the honeycomb structure 6 on the exhaust gas upstream side of the exhaust gas purification device 1 and the ceramic balloon 7 at least around the honeycomb structure 6, only the energy of the exhaust gas itself can be obtained. Therefore, it is possible to always reduce the particulates and nitrogen oxides such as black smoke by raising the temperature of the exhaust purification device 1 itself to a high temperature (in the experiments of the inventor, both particulates and nitrogen oxides were 5%).
A reduction of 0% or more has been confirmed). Further, since the exhaust gas purifying apparatus 1 basically does not use a heating means such as an electric heater, the exhaust gas purifying apparatus 1 has a simpler structure than the conventional exhaust gas purifying apparatus and can reduce the manufacturing and running costs.

Further, according to this embodiment, the exhaust sound pressure level can be attenuated by the modulation action of the ceramic pulsation 7 from the exhaust pulsation to the microwave, and the muffler can be eliminated from the exhaust pipe by the noise reduction effect. it can.

In the above, the exhaust gas purifying apparatus 1 according to the present invention has been described as an example of a purifying apparatus in which the honeycomb structure 6 is arranged at the center of the casing on the exhaust upstream side. It is not limited to the example.

[0027]

As described above, according to the present invention, by providing a honeycomb structure and a ceramic balloon without any gap inside the exhaust gas purifying apparatus, the particulates in the exhaust gas can be burned using only the energy of the exhaust gas. And nitrogen oxides can also be effectively reduced. Also, by filling the ceramic balloon,
An effect that the exhaust pulsation is modulated to the microwave and the exhaust noise can be reduced can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an exhaust gas purification device according to the present invention.

FIG. 2 is a plan view of the stainless steel net shown in FIG.

FIG. 3 is a plan view of the stainless steel punching plate shown in FIG.

FIG. 4 is an end view of the honeycomb structure taken along a line AA in FIG. 1;

FIG. 5 is a view showing an arrangement state of a ceramic balloon.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Exhaust gas purifier 2 ... Casing 3a, 3b ... Exhaust pipe 4 ... Stainless steel net 5 ... Stainless steel punching plate 6 ... Honeycomb structure 7 ... Ceramic balloon 9 ... Frame 10 ... Cell partition 11 ... Honeycomb cell

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01N 3/02 F01N 3/08

Claims (2)

(57) [Claims] 1. An exhaust purification device provided in an exhaust system of an internal combustion engine for removing exhaust particulates and nitrogen oxides in exhaust gas, comprising: a cylindrical casing connected to an exhaust passage of the internal combustion engine; while being disposed in a casing, a honeycomb structure disposed a large number of cells partitioned by ceramic partition walls and extending in an exhaust flow direction in a honeycomb shape, around the Oite honeycomb structure into the casing space <br / > filled, possess a number of ceramic hollow spheres, wherein the honeycomb structure is evacuated within the casing
It is located on the upstream side and leads into the casing.
Of the exhaust gas flowing into the cell,
Exhaust dynamic pressure changes to high static pressure in the cell space
Configured to, the hollow spheres, ceramics with far-infrared ray generating properties
Characterized that you have been formed from scan material, an exhaust purification system of an internal combustion engine. 2. The exhaust gas purifying apparatus according to claim 1, wherein
Each of the hollow spheres has a thickness of 0.3 mm or less.
The outer dimensions are within 3mm in diameter.
An exhaust purification device for an internal combustion engine.