JPH08144736A - Exhaust particulates filtering device for diesel engine - Google Patents

Abstract

PURPOSE: To suppress axial extention of metal meshes by selecting physical properties independently in respect to longitudinal and transverse wires composing the metal meshes. CONSTITUTION: Filter bodies A, B are formed by cylindrically winding a nonwoven fabric 8 prepared by laminating ceramic fibers and irregularly tangling them, on both sides of which fabric 8 metal meshes 7 are superposed. In the metal mesh 7, heat expansion coefficients of longitudinal wires arranged axially in the filter bodies A, B exceed those of transverse wires arranged circumferehtially.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to exhaust fine particles for a diesel engine equipped with a filter body formed by cylindrically winding a wire mesh on both sides of a non-woven fabric formed by laminating ceramic fibers and irregularly intertwined with each other. The present invention relates to a filtering device.

[0002]

2. Description of the Related Art Filter bodies of conventional exhaust particulate filter devices for diesel engines include a so-called reverse plug type and a heat regeneration type. It has been proposed that the heating and regenerating type filter main body uses a felt or a non-woven fabric made of ceramic fiber having a high heat resistance temperature, and a wire mesh for electric heating is laminated on the non-woven fabric like a sandwitch.

As shown in FIG. 5, in the case where the filter main body A has the non-woven fabric 28 and the wire nets 27 superposed on both sides, the wire net 2
7 are arranged in the axial direction of the tubular filter body, and the horizontal lines 27b are arranged in the circumferential direction. Since the axial expansion of the wire net 27 due to the thermal expansion is restricted by the partition plate and the holding plate (see the partition plate 4 and the holding plate 14 in FIG. 1), when the wire net 27 is energized, the wire net 27 bends and the nonwoven fabric It may be partially peeled from 28 and may not return to its original shape even after de-energization, which may cause wrinkles. That is,
When the filter main body A is heated and regenerated, a difference in temperature between the wire netting 27 and the case and a difference in material cause a difference in elongation due to thermal expansion.
Since the wire net 27 has a large elongation, wrinkles are generated on the wire net 27, resulting in incomplete contact with the non-woven fabric 28 and overheating, which impairs durability. In addition, the temperature distribution of the fetal main body A becomes uneven, and the regeneration incomplete part occurs in the fetal main body A.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, the object of the present invention is to suppress the elongation of the wire mesh in the axial direction by individually selecting the physical characteristics of the vertical lines and the horizontal lines which form the wire mesh. Another object of the present invention is to provide an exhaust particulate filter for a diesel engine.

Another object of the present invention is to obtain a uniform temperature distribution of the wire mesh by individually selecting the physical characteristics of the vertical lines and the horizontal lines which form the wire mesh, and an exhaust particulate filter for a diesel engine. To provide.

[0006]

In order to achieve the above object, the constitution of the present invention is a non-woven fabric formed by laminating ceramic fibers and randomly entwined with each other. In the exhaust particulate filter of a diesel engine equipped with the filter main body, the wire mesh has a coefficient of thermal expansion of a horizontal line arranged in the circumferential direction larger than a coefficient of thermal expansion of a vertical line arranged in the axial direction of the filter main body.

[0007]

[Function] Regarding the material used for the wire mesh, a material having a smaller coefficient of thermal expansion than the horizontal wire is used for the vertical wire, and the vertical wire is arranged in the axial direction and the horizontal wire is arranged in the circumferential direction with respect to the tubular filter body. By attaching the filter body to the case in a twisted state with respect to the central axis during the assembling of the filter body, the vertical lines are arranged in a spiral shape and the axial expansion due to the thermal expansion of the wire mesh is suppressed. In other words, the horizontal wire uses a material having a coefficient of thermal expansion larger than that of the vertical wire, thereby converting the axial extension into the radial extension.

Further, by using a material having a large temperature resistance coefficient for the vertical line of the wire mesh and a material having a small temperature resistance coefficient for the horizontal wire, the current flowing in the high temperature portion of the wire mesh is reduced and the main body of the filter is made horizontal. In the case of the arrangement, the temperature difference between the upper and lower parts is reduced and the temperature distribution of the wire mesh is made uniform.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a side sectional view of an exhaust particulate filter according to the present invention, FIG. 2 is an enlarged side sectional view of a main part of a filter body, and FIG. 3 is a perspective view of a wire mesh in the exhaust particulate filter. FIG. 4 is an explanatory diagram of the elongation of the wire mesh.

As shown in FIG. 1, the exhaust particulate filter comprises a cylindrical case 5 and a pair of inner and outer cylindrical filter bodies A and B. The case 5 is connected to the inlet pipe 2 at the right end through the conical cylinder 3, the end plate 15 is connected to the left end, and the outlet pipe 16 is connected to the opening 15a at the axial center of the end plate 15.
The partition plate 4 having a large number of openings 4a arranged in the circumferential direction on the left end side of the case 5 is coupled, and the openings 14a arranged in the circumferential direction on the right end side.
And a holding plate 14 having an axial center opening 14b are joined together, and the filter body A and the filter body B are concentrically joined between the partition plate 4 and the holding plate 14. For details, see Filter main body A
The right end of the filter body B is connected to the annular plate 12, and is also connected to the holding plate 14 via the heat insulating ring 13.

As shown in FIG. 2, each filter body A, B
Is a non-woven fabric 8 formed by laminating ceramic fibers and entangled irregularly, and wire mesh 7 is superposed on both inner and outer surfaces. In the present invention, in order to suppress the elongation of the wire net 7 in the axial direction, the horizontal lines 7b of the tubular filter bodies A and B are arranged in the circumferential direction, while the vertical lines 7a are related to the central axis line x (see FIG. 3). Tilt by the twist angle θ. In practice, before assembling, the vertical lines 7a of each wire mesh 7 are arranged in the axial direction and the horizontal lines 7b are arranged in the circumferential direction, and the nonwoven fabric 8 is superposed on the inner and outer surfaces thereof to form the filter bodies A and B. It suffices that the main bodies A and B are twisted with respect to the central axis line x by a twist angle θ and then connected between the partition plate 4 and the holding plate 14.

Exhaust gas enters from the inlet pipe 2 through the opening 4a of the partition plate 4 into the annular space 10 between the filter body A and the filter body B, and the exhaust particulates pass through the filter body A or the filter body B. Filtered. The exhaust gas that has passed through the filter body A from the empty space 10 is vacated by the empty space 6 between the case 5 and
Exhaust gas that has flowed through the opening 14a of the holding plate 14 to the outlet pipe 16 and has passed through the filter body B from the empty space 10 is discharged to the empty space 21,
It flows out to the outlet pipe 16 through the opening 14b of the holding plate 14.

When the filter bodies A and B are clogged,
When the wire nets 7 are energized, the wire nets 7 generate heat to heat the nonwoven fabric 8 and burn the exhaust particulates collected in the nonwoven fabric 8 to regenerate the filter bodies A and B.

As shown in FIG. 4, the vertical line 7a is inclined by a lead angle θ with respect to the central axis line, and when heated by energization,
When the vertical line 7a is heated and extends by ΔL1, the horizontal line 7b (actually the circumferential length) extends by ΔL2 and the radius increases. At this time, the coefficient of thermal expansion of the vertical line 7a is smaller than the coefficient of thermal expansion of the horizontal line 7b, and the vertical line 7 with respect to a predetermined temperature change is
If the elongation ΔL1 of a and the elongation ΔL2 of the horizontal line 7b have a relationship as shown in FIG. 4, the wire netting 7 does not extend in the axial direction but only expands radially outward. Therefore, the wire netting 7 does not expand in a complicated manner and is not partially peeled off from the nonwoven fabric 8 to form wrinkles.

In the second embodiment of the present invention, the temperature resistance coefficient of the vertical line 7a is made larger than that of the horizontal line 7b. For example, platinum, tungsten, etc. are used for the vertical line 7a, and stainless steel, Fe-Cr-Al alloy, etc. are used for the horizontal line 7b. If the vertical wire 7a is energized from one end side to the other end side during regeneration of the filter main bodies A and B, the resistance of the high temperature part increases when the vertical line 7a locally becomes hot, and the current bypasses the high temperature part. To the other vertical line 7a via the horizontal line 7b,
Moreover, since the temperature resistance coefficient of the horizontal line 7b is smaller, the current easily flows in the circumferential direction. As a result, the temperature distribution of the wire mesh 7 becomes uniform, the exhaust particulates of the filter bodies A and B are removed by combustion, and the filter bodies A and B are evenly and uniformly regenerated.

[0016]

INDUSTRIAL APPLICABILITY As described above, the present invention relates to a diesel engine equipped with a filter body in which a non-woven fabric formed by laminating ceramic fibers and entangled irregularly with a wire mesh on both sides is wound in a tubular shape. In the exhaust particulate filter, since the wire mesh has a coefficient of thermal expansion of a horizontal line arranged in the circumferential direction larger than a coefficient of thermal expansion of a vertical line arranged in the axial direction of the filter main body, during regeneration of the filter main body, By suppressing the elongation in the axial direction due to the temperature rise, the separation between the non-woven fabric and the wire mesh is suppressed, and the wire mesh is always kept in close contact with the non-woven cloth. Can be played back.

Since the temperature distribution with respect to the non-woven fabric becomes uniform, the main body of the filter can be regenerated in a short time, and the exhaust fine particles do not remain unburned.

[Brief description of drawings]

FIG. 1 is a side sectional view of an exhaust particulate filter for a diesel engine according to the present invention.

FIG. 2 is a side sectional view showing an enlarged main part of the filter body.

FIG. 3 is a perspective view of a wire mesh in the exhaust particulate filter.

FIG. 4 is an explanatory diagram of elongation of a wire net.

FIG. 5 is a side sectional view showing a modification of a conventional wire mesh.

[Explanation of symbols]

A, B: Filter main body θ: Lead angle 2: Inlet pipe
3: conical cylinder 4: partition plate 4a: opening 5: case 6: empty part 7: wire mesh 7a:
Vertical line 7b: Horizontal line 8: Nonwoven fabric 10: Empty part 12: Annular plate 13: Adiabatic ring 14: Holding plate 14a, 14b:
Opening 15: End plate 15a: Opening 16: Outlet pipe 2
1: empty space

Claims (3)

[Claims] 1. An exhaust particulate filter for a diesel engine equipped with a filter main body, which comprises a non-woven fabric formed by laminating ceramic fibers and irregularly intertwined with each other and wrapping a metal net on both sides in a tubular shape. Is an exhaust particulate filter device for a diesel engine, wherein the coefficient of thermal expansion of a horizontal line in the circumferential direction is larger than the coefficient of thermal expansion of a vertical line in the axial direction of the filter body. 2. An exhaust particulate filter for a diesel engine equipped with a filter main body, which comprises a non-woven fabric formed by laminating ceramic fibers and irregularly intertwined with each other and wrapping a metal mesh on both sides in a tubular shape. Is an exhaust particulate filter for a diesel engine, wherein the coefficient of temperature resistance of a vertical line aligned in the axial direction of the filter body is made larger than the coefficient of temperature resistance of a horizontal line aligned in the circumferential direction. 3. The exhaust gas of a diesel engine according to claim 1, wherein the vertical line is spirally twisted by an angle of twist given by a ratio of thermal expansion coefficients of the vertical line and the horizontal line of the wire mesh. Fine particle filter.