JPH0925813A - Exhaust emission control device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To speedily regenerate a filter body by evenly supplying regenerating air to the filter body from a front end to a rear end, heating and burning exhaust particulates which are captured. SOLUTION: A plurality of filters 21 are parallelly arranged. In each filter 21, an inner cylinder 8 is arranged between an outer cylinder 7 and a cylindrical filter body 25. A number of through-holes 8a are formed on the inner cylinder 8. An air supply pipe 9 is connected to a substantially center portion of the outer cylinder 7 in an axial direction for supplying regenerating air to an outer peripheral surface of the filter body 25. The filter body 25 is prepared by superposing a conductive mesh on at least an outer surface of a felt body made up of ceramic fiber.

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 for a diesel engine, and more particularly, to collect exhaust particulates (patty cylates) in exhaust gas with a filter and regenerate the filter by burning the collected exhaust particulates with electric heat. The present invention relates to such an exhaust gas purification device.

[0002]

2. Description of the Related Art In an exhaust gas purification device for a diesel engine disclosed in Japanese Patent Laid-Open No. 5-156927, regeneration air necessary for burning exhaust particulates is introduced to the front end and the rear end of a heated filter body (filter). By connecting each of the air supply pipes to the outer cylinder, disposing a control valve and an air pump in the air supply pipe, and changing the circulation direction of the regeneration air, the filter body may be left with unburned exhaust particulates or overheated. It prevents the filter body from melting. However, in the above-mentioned exhaust gas purification device, the temperature rise in the vicinity of the central portion in the axial direction of the filter body becomes insufficient, and the state of oxygen deficiency is likely to occur, and exhaust particulate matter may remain unburned. Also, while supplying the regeneration air until the axial center of the filter body is completely regenerated,
Since the filter body is cooled, there is a problem that power consumption required for regeneration increases.

[0003]

In view of the above problems, the object of the present invention is to uniformly supply regeneration air from the front end to the rear end of the filter to heat and burn the collected exhaust particulates. An object of the present invention is to provide an exhaust emission control device for a diesel engine that rapidly regenerates a filter body.

[0004]

In order to achieve the above object, the structure of the present invention comprises an outer cylinder of a recyclable filter provided in the middle of an exhaust pipe and a filter body arranged inside the outer cylinder. Between,
An inner cylinder having a large number of through holes is coaxially arranged, and an air supply pipe for introducing the regeneration air of the filter body to the outer peripheral surface of the inner cylinder is connected to the outer cylinder.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, an inner cylinder is coaxially arranged between an outer cylinder and a filter body made of a tubular felt-like body, and a large number of through holes are provided in the inner cylinder. When the filter is regenerated by connecting the air supply pipe to the outer cylinder, the regeneration air supplied to the chamber between the outer cylinder and the inner cylinder is passed through a large number of through holes provided in the inner cylinder, and the entire peripheral surface of the filter is Is almost evenly dispersed and supplied to at least one of the wire nets superposed on the inner and outer surfaces of the filter. Therefore, the exhaust particulates collected by the filter body are heated and simultaneously react with the regeneration air and burn. Since the regenerating air is supplied to the entire circumferential surface of the filter body substantially evenly, the exhaust fine particles are burned substantially uniformly in the axial direction and the circumferential direction of the filter body, and the filter body is quickly regenerated.

[0006]

1 is a partial cross-sectional side view showing a first embodiment of an exhaust purification system for a diesel engine according to the present invention. In the exhaust gas purification device, a plurality of (two in the illustrated embodiment) filters 21 are connected in parallel, and an inlet end of an outer cylinder 7 that houses the filters 21 passes through a conical cylinder 6 and a branch pipe 3. It is connected to the inlet pipe 2. At the connection between the inlet pipe 2 and the branch pipe 3,
The switching valve 4 is supported by the support shaft 5, and the filters 21 arranged in parallel in the vertical and horizontal directions are alternately regenerated. The outlet end of the outer cylinder 7 is connected to the end plate 7a.
It is connected via 5 to the outlet pipe 16. The inlet pipe 2 is connected to the exhaust pipe of the diesel engine, and the outlet pipe 16 is connected to an exhaust muffler (not shown).

One end of the air supply pipe 9 is connected to the central portion of the outer cylinder 7 in the axial direction. The other end of the air supply pipe 9 is connected to the regeneration air source 30, and an opening / closing valve or control valve 10 for adjusting the amount of regeneration air supplied to the inside of the outer cylinder 7 is inserted and connected in the middle of the air supply pipe 9. An inner cylinder 8 having a large number of through holes 8a coaxial with the outer cylinder 7.
And a filter body 25 having a star-shaped cross section inside the inner cylinder 8.
Is arranged. The left end of the inner cylinder 8 is connected to the conical cylinder 6, and the right end of the inner cylinder 8 is connected to the end plate 7a of the outer cylinder 7.

As shown in FIG. 2, the regeneration air in the chamber 22 between the outer cylinder 7 and the inner cylinder 8 is blown through the inner cylinder 8 to the entire peripheral surface of the filter body 25 almost uniformly. A large number of through holes 8a are provided in the inner cylinder 8. That is, as shown by expanding the inner cylinder 8 in FIG. 3, the inner diameter of the through hole 8 a is equal to the outer cylinder 7 of the air supply pipe 9.
It becomes larger as it gets farther from the connection part. FIG.
As shown in FIG. 5, the filter body 25 has a tubular shape with a star-shaped cross section, and in FIG. 4, the left end is closed by an end plate, and the right end is connected to the collecting pipe 15 via an annular end plate. To be done.

As shown in FIG. 6, the filter body 25 has a fine non-woven fabric or a felt-like body 27 formed by laminating heat-resistant fibers, for example, ceramic long fibers, and entangled irregularly.
And a similar coarse felt-like body 28 are overlapped with each other, and a wire mesh 26 knitted from a heat-resistant metal wire is further formed on the inner surfaces of the felt-like bodies 27 and 28, and a heater formed by knitting a heat-resistant metal wire on the outer surface is energized. It is composed of a laminated body in which possible wire nets 29 are overlapped with each other. That is, the laminated body is curved in a corrugated cross section, and is also curved as a whole in a cylindrical shape, and the insulating plate 19 is sandwiched between both end edges of the laminated body so as to be superposed and coupled to each other. The electrode 12 is fastened to one end edge of the wire net 29, and the electrode 13 is fastened to the other end edge of the wire net 29.

As shown in FIG. 1, the conductors connected to the electrodes 12 and 13 are drawn out from the conical cylinder 6 to the outside, and the filter 2
At the time of reproduction of No. 5, power is supplied from a battery as a power source. The inner space 23 of the filter body 25 communicates with the collecting pipe 15. Thermocouples 14a to 14c are provided at both axial ends and the central portion of the filter body 25, and are configured to detect the temperature of the outer surface of the filter body 25 when the filter body 25 is regenerated.

As shown in FIG. 1, when the switching valve 4 is in the illustrated state, the control valve 10 of the air supply pipe 9 of the upper filter 21 is opened, and the control of the air supply pipe 9 of the lower filter 21 is controlled. The valve 10 is closed. During the operation of the diesel engine, the exhaust gas passes through the inlet pipe 2 and the branch pipe 3 and enters the inside of the inner cylinder 8 of the lower filter 21, and passes through the outer peripheral surface of the filter body 25 to the inner space 23, and then the exhaust particulates. Is removed. The exhaust gas that has entered the inner space 23 flows out to the outlet pipe 16 via the collecting pipe 15.

On the other hand, in the upper filter 21, regeneration air is supplied to the entire peripheral surface of the filter body 25 through the air supply pipe 9 and the through hole 8a of the chamber 22. At the same time, the wire mesh 29 on the outer surface of the filter body 25 is energized from the power source battery to heat the wire mesh 29. Therefore, the exhaust particulates collected in the filter body 25 are heated and burned, and the filter body 25 is regenerated. The combustion gas flows into the inner space 23, and further flows out through the collecting pipe 15 to the outlet pipe 16. Since the regeneration air from the air supply pipe 9 is evenly supplied to the entire peripheral surface of the filter body 25 through the through holes 8a having different inner diameters of the inner cylinder 8, the exhaust particulates of the filter body 25 are quickly and uniformly burned. , No unburned residue.

The maximum outer diameter according to the present invention is about 18c.
A regeneration test was conducted on an exhaust gas purification device having a length of m and a length of about 54 cm at a supply rate of about 200 lt / min, and as shown in FIG. 10, each thermocouple 14a, 14b, 1
The temperature detected by 4c changed with the energization time to the wire net 29 as a heater, and the exhaust fine particles of the filter body 25 were completely burned down in about 15 minutes, and the filter body 25 was regenerated.

For comparison, as shown in FIG. 11, the inner cylinder is eliminated, the branch pipe 3 is provided with the air supply pipe 31, and the outer cylinder 7 is provided with the end plate 7.
A similar regeneration test was conducted on the exhaust gas purifying apparatus in which the air supply pipes 32 were connected to a, respectively. As a result, as shown in FIG. 12, combustion of exhaust particulates in the rear part of the filter body 25 started first and in the central part. The combustion was delayed, and it took about 20 minutes before the filter body 25 was regenerated.

FIG. 7 is a partial cross-sectional side view showing an exhaust gas purification apparatus of the type in which exhaust gas is regenerated as a second embodiment of the present invention. In this embodiment, the air supply pipe 9a is connected to the inlet pipe 2, and exhaust gas is introduced as regeneration air. The exhaust gas used as the regenerating air is not limited to the example shown in FIG.
The exhaust gas from the upstream side or the downstream side of 1 may be introduced. In this embodiment, the configuration and operation are the same as those of the above-described first embodiment except that the exhaust air is introduced as regeneration air.

FIG. 8 is a side view, partly in section, showing an exhaust purification system of the type having a bypass as a third embodiment of the present invention. In this embodiment, a single renewable filter 21
On the other hand, a bypass pipe 40 connecting the upstream side and the downstream side of the filter 21 is provided, and the exhaust gas during regeneration of the filter 21 passes through the bypass pipe 40. The structure and operation of the filter 21 are similar to those of the first embodiment.

FIG. 9 is a partial sectional side view showing a fourth embodiment as a modification of the third embodiment of the present invention. In this embodiment, the air supply pipe 9a is connected to the inlet pipe 2 and exhaust gas is introduced as regeneration air. The exhaust gas used as the regeneration air is not limited to the example shown in FIG. 9, but may be the central portion of the bypass pipe 40, the upstream portion of the bypass pipe 40, or the bypass pipe 40.
You may make it introduce | transduce the exhaust_gas | exhaustion from the downstream part.
In this embodiment, the configuration and operation are the same as those of the above-described third embodiment except that exhaust air is introduced as regeneration air.

In each of the above-mentioned embodiments, the connection position of the air supply pipes 9 and 9a to the outer cylinder 7 is set to the central portion in the axial direction, but if the regenerating air is introduced to the outer peripheral surface of the inner cylinder 8, it is not necessarily the axial direction. It is not limited to the central portion.

[0019]

According to the present invention, since the regenerating air is uniformly supplied from the front end portion to the rear end portion of the filter body, the exhaust fine particles collected in the filter body are heated and burned, and the filter body is Played quickly. That is, as the exhaust gas purification device, it is possible to obtain a highly reliable device which has a short regeneration time, a small amount of power consumption, no unburned exhaust particles and no clogging of the filter body.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional side view showing an exhaust emission control device according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing an outer cylinder and an inner cylinder in the exhaust emission control device of the embodiment in a cutaway manner.

FIG. 3 is a development view of an inner cylinder in the exhaust emission control device of the same embodiment.

FIG. 4 is a side view of a filter body in the exhaust emission control device of the same embodiment.

FIG. 5 is a front cross-sectional view of the exhaust emission control device of the same embodiment.

FIG. 6 is an enlarged front sectional view showing a main part of a filter body in the exhaust emission control device.

FIG. 7 is a partial cross-sectional side view of an exhaust emission control device according to a second embodiment of the present invention.

FIG. 8 is a partial cross-sectional side view of an exhaust emission control device according to a third embodiment of the present invention.

FIG. 9 is a partial cross-sectional side view of an exhaust emission control device according to a fourth embodiment of the present invention.

FIG. 10 is a diagram showing a result of a regeneration test of the exhaust emission control device according to the present invention.

FIG. 11 is a partial cross-sectional side view of an exhaust emission control device as a comparative example for a regeneration test.

FIG. 12 is a diagram showing the results of a regeneration test on an exhaust emission control device as a comparative example.

[Explanation of symbols]

2: Inlet pipe 3: Branch pipe 4: Switching valve 5: Support shaft 6:
Cone cylinder 7: Outer cylinder 8: Inner cylinder 9, 9a: Air supply pipe 1
0: Control valve 11: Filter body 12, 13: Electrode 15:
Collecting pipe 16: Outlet pipe 19: Insulating plate 21: Filter
22: Room 23: Inner space 25: Filter body 26, 29:
Wire mesh 27, 28: felt-like body 40: bypass pipe

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location F01N 3/02 301 F01N 3/02 301B (72) Inventor Takamoto Suzuki 474 Ishikawa, Fujisawa City, Kanagawa Prefecture None Gray One 201

Claims (4)

[Claims] 1. An inner cylinder having a large number of through holes is coaxially arranged between an outer cylinder of a recyclable filter provided in the middle of an exhaust pipe and a filter body arranged inside the outer cylinder. An exhaust purification device for a diesel engine, wherein an air supply pipe for introducing the regeneration air of the filter body to the outer peripheral surface of the inner cylinder is connected to the outer cylinder. 2. The exhaust gas purifying apparatus for a diesel engine according to claim 1, wherein the inner diameter of the through hole of the inner cylinder increases as the distance from the connecting portion of the air supply pipe to the outer cylinder increases. 3. The exhaust gas purifying apparatus for a diesel engine according to claim 2, wherein the filter body is formed by superposing an energizable wire mesh on at least one of the inner and outer surfaces of a felt-like body made of ceramic fibers. 4. The exhaust gas purification device for a diesel engine according to claim 1, wherein exhaust gas from an exhaust pipe upstream of the filter is used as the regeneration air.