JP2002303122A - Particulate filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve pressure resistance and durability of a particulate filter formed by piling a corrugated panel made of heat resistant metal and non-woven fabric and winding them like a roll, and joining mutual contact parts of the corrugated panel and the non-woven fabric in a thermal diffusion joining method. SOLUTION: The corrugated panel 12 interposed between layers of metal non-woven fabric 13 is provided with a stair shaped buffer part 18. The buffer part 18 absorbs a radial force generated by thermal strain, thereby decreasing stress applied to a joint part 16 between the corrugated panel 12 and the metal non-woven fabric 13 and preventing removal of the joint part to keep pressure resistance and durability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particulate filter for collecting suspended particles (particulate matter represented by soot, hereinafter referred to as PM) contained in exhaust gas of a diesel engine or the like.

[0002]

2. Description of the Related Art Diesel engines have lower fuel consumption than gasoline engines, but have a problem that exhaust gas contains PM which causes air pollution.

For this reason, a technology has been developed in which a trap is attached to the exhaust system of an engine, and PM in the exhaust gas is collected and removed by a particulate filter loaded in a container of the trap.

[0004] The particulate filter is required to have not only excellent PM collection performance but also excellent resistance to vibration, gas pressure and heat cycle.

[0005] In order to meet the demand,
The present applicants have proposed Fe-Cr-Al alloy, Ni-Cr-A
A nonwoven fabric of a heat-resistant metal fiber formed of an alloy or the like and a metal corrugated sheet are superimposed and wound into a roll on a core, which is then loaded into a heat-resistant container of a trap.
0-223144.

[0006] In the particulate filter, one end of a space formed between layers of the nonwoven fabric is fastened by joining adjacent nonwoven fabrics, and the stitching is performed in a staggered manner, so that an exhaust gas inflow space whose inlet is open is opened. And, the outlet is formed in the radial direction of the exhaust gas outflow space opened alternately,
Deformation damage due to vibration and repeated thermal stress of the nonwoven fabric acting as a filter material is prevented by a corrugated sheet sandwiched between layers.

Further, the mutual contact portion between the nonwoven fabric and the corrugated sheet is joined by a thermal diffusion bonding method to stop the relative movement in the axial direction between the nonwoven fabric and the corrugated sheet which are wound up in a spiral shape. Prevents damage.

[0008]

Problems to be Solved by the Invention Japanese Patent Application No. 2000-223
Although the particulate filter of No. 144 has taken various measures to ensure durability, the temperature change is remarkable and extremely severe conditions such as being subject to strong vibration and high gas pressure when the temperature is high are high. When used below, the joint between the corrugated sheet and the nonwoven fabric was detached, the reinforcement by the corrugated sheet was insufficient, and the possibility that the nonwoven fabric was damaged by the gas pressure remained.

Therefore, the present invention prevents the joint between the nonwoven fabric and the corrugated sheet from coming off even under severe use conditions, and achieves high reliability,
It is an object of the present invention to provide a particulate filter that maintains high durability and a particulate filter that maintains high durability even when a joint is detached.

[0010]

In order to solve the above-mentioned problems, according to the present invention, a corrugated sheet made of a heat-resistant metal and a nonwoven fabric are stacked and wound in a roll shape, and one end of a space formed between layers of the nonwoven fabric is formed. In a particulate filter formed by radially creating an inflow space and an outflow space of the exhaust gas defined by the nonwoven fabric and joining the mutual contact portions of the corrugated sheet and the nonwoven fabric, The plate is provided with a buffer for absorbing a force in the radial direction of the filter and a buffer for absorbing a force in the axial direction of the filter.

The former buffer portion is provided between the peaks and valleys of the wave of the corrugated sheet, and the latter buffer portion is provided on the corrugated sheet in the middle of the filter axis. The buffer for absorbing the radial force and the buffer for absorbing the axial force may be provided independently, but a better effect can be expected by using both together.

The buffer for absorbing the force in the radial direction of the filter includes: (1) a metal fiber nonwoven fabric, a three-dimensional network structure, a wire mesh, etc.
It is made of a heat-resistant metal material having a lower Young's modulus than a corrugated sheet material and is easily deformed. (2) Make folds between the peaks and valleys of the corrugated sheet to allow deformation. (3) The corrugation of the corrugated plate is stepped. It can be formed by the method described above.

The buffer for absorbing the axial force is made of (4) the same heat-resistant metal material as in (1) above. (5) Divide the corrugated sheet in the filter axis direction, and arrange the divided corrugated sheets with a gap. It can be formed by the method described above.

As another measure for solving the above-mentioned problems, in the present invention, a laminated material of a corrugated sheet and a nonwoven fabric is wound into a roll shape, necessary portions are sealed, and a contact portion between the corrugated sheet and the nonwoven fabric is subjected to heat diffusion welding. The invention also provides a structure in which a filter formed by joining by a legal method or the like is divided into concentric multiple cylindrical shapes, and a heat-resistant cylindrical member held by a filter support is interposed between the divided filters.

This structure and the above-mentioned buffer may be used in combination.

[0016]

The thermal diffusion joint between the nonwoven fabric and the corrugated sheet is likely to come off when subjected to a radial pulling force (peeling force) or an axially shifting force (shearing force).

The buffer portion provided on the corrugated plate in the present invention protects the joint portion by absorbing the force.

That is, the buffer absorbing the force in the radial direction of the filter expands and contracts when a radial tensile stress or a compressive stress is generated between the nonwoven fabric and the corrugated sheet due to thermal strain, and absorbs the stress.

Further, when a relative moving force in the axial direction is generated between the nonwoven fabric and the corrugated sheet due to thermal strain, the cushioning portion absorbing the force in the axial direction of the filter expands and contracts and absorbs the force. In the case where the corrugated sheet is divided into strips and arranged with a gap, the nonwoven fabric is hardly restrained by the corrugated sheet, and the nonwoven fabric easily expands and contracts, thereby reducing the axial stress itself.

Therefore, the force applied to the heat diffusion bonding portion between the nonwoven fabric and the corrugated sheet is smaller than that without the buffer portion, and the bonding portion does not come off even under severe conditions. Thereby, sufficient pressure resistance is maintained, breakage of the filter is prevented, and high durability is maintained.

Next, in the case where the filter is divided into multiple cylinders and a cylindrical member is interposed between the divided filters, the thermal strain generated in the filter is reduced by the division of the filter, and the stress applied to the filter is smaller than that of the non-divided filter. Smaller. In addition, since the radial force applied to the split filter is received by the cylindrical member, the separating force due to the gas pressure applied to the joint is reduced, thereby preventing the joint from coming off. Furthermore, even if the joints come off,
Because the cylindrical member suppresses the swelling of the nonwoven fabric due to gas pressure,
Sufficient pressure resistance is maintained, and high durability is maintained.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a particulate filter of the present invention in a state where it is loaded in a container of a trap.

FIG. 1 shows a particulate trap incorporated in the exhaust pipe of the engine. This trap 1
Is a cylindrical container 2 with a flange, a filter support 3,
Particulate filter 10 loaded in cylindrical container 2
Consisting of The cylindrical container 2 and the filter support 3 are attached to the exhaust pipe 4 by inserting the cylindrical container 2 into the exhaust pipe 4 and clamping the outer peripheral flanges 5 and 6 with a pipe joint for connecting the exhaust pipe.

The filter support 3 has a cantilever support shaft 7 at the center, and the support shaft 7 is
And a hole between the arms 8 is formed as a passage for the exhaust gas passing through the filter.

The particulate filter 10 has a core 11 inserted on the support shaft 7 of the support. A laminated material in which a corrugated sheet 12 made of a heat-resistant metal and a nonwoven fabric 13 made by assembling and bonding countless heat-resistant metal fibers to have a predetermined porosity on the core 11 is rolled. Wrapped around. In addition, one end of the space formed between the layers of the nonwoven fabric 13 is joined and joined by joining the ends of the nonwoven fabric which are radially adjacent to each other, and the joining is performed so that the nonwoven fabric of each layer is connected in a zigzag manner in a longitudinal sectional view of the filter. Thus, exhaust gas inflow spaces 14 with open openings and exhaust gas outflow spaces 15 with open outlets defined by the nonwoven fabric 13 are alternately formed in the radial direction.

Further, the contact portion between the corrugated sheet 12 and the nonwoven fabric 13 is joined by an industrially advantageous diffusion joining method. The joint is shown at 16 in FIG.

Reference numeral 17 denotes a spacer to be inserted between the filter 10 and the cylindrical container 2. However, the spacer 17 may be omitted by forming a structure in which the outer periphery of the filter 10 is directly supported by the inner surface of the cylindrical container 2.

FIG. 2 is an expanded view of a part of a cross section perpendicular to the axis of the particulate filter 10 of FIG.

As shown in FIG. 2, the corrugated plate 12 is formed by forming a wave into a step shape to form a step between a peak and a valley. Buffer 18 for
Becomes

FIG. 3 shows that a portion made of a heat-resistant material having a Young's modulus lower than that of the corrugated sheet material is provided between the peaks and valleys of the corrugated sheet 12 so as to act as the buffer 19. FIG. 4 shows a structure in which a fold is provided between the peaks and valleys of the corrugated sheet 12 so as to function as a buffer 20.

The buffer 19 shown in FIG. 3 is formed of a nonwoven fabric made of a heat-resistant metal, a three-dimensional net structure, a wire mesh, or the like. Also requires a pleating step, which complicates manufacturing. On the other hand, the buffer portion 18 in FIG. 2 has an advantage that it can be easily manufactured by a method of corrugating a metal plate with a mold having a step-shaped molding surface.

FIGS. 5 and 6 show examples in which buffer portions 21 and 22 are provided in the middle of the corrugated plate 12 in the filter axis direction.

The buffer 21 shown in FIG. 5 is formed by dividing the corrugated plate 12 into strips with a width W, and leaving a gap g between the divided corrugated plates. 6 is formed by replacing a part of the corrugated sheet 12 with a heat-resistant material having a Young's modulus lower than that of the corrugated sheet material, for example, a nonwoven fabric of a metal fiber, a three-dimensional network structure, a wire mesh, or the like. ing. Although the structure of FIG. 6 requires joining of materials similarly to that of FIG. 3, the structure of FIG. 5 does not require such trouble.

The shock absorbers shown in FIGS. 2 to 6 are required to withstand gas pressure and vibration during use, in addition to the function of relaxing stress. Then, when the Young's modulus of the buffer part of the filter mounted on the vehicle was examined, the Young's modulus of the buffer part of FIGS. 2 to 4 was in the range of 100 to 3000 MPa, and that of the buffer part of FIG. Was preferred.

Further, the cushioning portion shown in FIG. 5 has a dividing width W of the corrugated sheet of 3 to 20 mm and a gap g between the divided corrugated sheets of 0.1 to 10 mm.
I liked it. If the division width W of the corrugated sheet is too small or the gap g is too wide, the corrugated sheet 12 is easily crushed, the reinforcement of the nonwoven fabric by the corrugated sheet becomes unstable, and the pressure resistance becomes unstable. On the other hand, if the width W of the corrugated sheet 12 is too large or the gap g is too small, the buffer effect becomes small, which is not preferable.

The appropriate values of the Young's modulus, the division width W of the corrugated sheet, and the gap g vary depending on the size of the particulate trap and the use environment.

FIG. 7 shows an embodiment of a particulate filter divided into multiple cylinders.

Here, the particulate filter 10 loaded in the cylindrical container 2 is made up of a cylindrical inner filter 23,
It is divided into two cylindrical outer filters 24 arranged concentrically on the outer periphery of the inner filter. A cylindrical member 25 made of a heat-resistant metal is provided between the inner and outer filters 23 and 24.
Is inserted.

The cylindrical member 25 is supported by the filter support 3 in a cantilever manner.
And supports the inner periphery of the outer filter 24 to receive the radial stress applied to both filters. The filter 10
Is divided into a plurality of parts, the thermal strain is dispersed, and the stress applied to the inner filter and the outer filter becomes smaller than that of the non-divided filter. As a result, the joint 16 is protected, and swelling of the nonwoven fabric due to gas pressure is suppressed. Therefore, this structure does not particularly require a buffer, but if the above-mentioned buffer is used in combination, a more preferable filter can be obtained.

The number of filter divisions in the structure of FIG.
About 3 to 3, the thickness of the cylindrical member 25 is 0.5 to 1.5 mm
The degree was desirable. If the number of divisions is too large, not only the production becomes complicated, but also loading of the filter into the container becomes troublesome. In addition, the effective filtration area of the filter decreases, and the trapping performance also decreases. If the thickness of the cylindrical member 25 is too large, the filtration area is reduced. Therefore, it is preferable to reduce the thickness of the cylindrical member 25 as far as possible without impairing the supporting strength.

A test for confirming the effect and the like will be described below.

A filter having an outer diameter of 60 mm and an inner diameter of 10 mm was provided with a corrugated plate formed in a step shape as shown in FIG.
Using the normal corrugated sheet of (b), the filter is
The maximum thermal stress in the radial direction generated at the joint between the nonwoven fabric and the corrugated sheet when the temperature change was repeated between 00 ° C was determined by simulation. As a result, the stress when using the corrugated sheet (Young's modulus E = 200000 MPa) shown in FIG.
Pa. On the other hand, the stress when using the corrugated sheet (E of buffer part = 2000 MPa) in FIG.
a was extremely small.

Next, a particulate filter using the corrugated sheet shown in FIGS. 8A and 8B was placed at 800 ° C. every 2 minutes.
And then cooled to 100 ° C., and a heat cycle test in which this was repeated 5000 cycles was performed.
In the ordinary filter using the corrugated sheet, the pressure resistance at the end of the test was reduced by 30% compared to the initial level. In contrast, FIG.
The filter using the corrugated sheet of FIG.
It was reduced to 0%.

Further, as shown in FIG.
= 10 mm, divided into strips, separated by a gap (g = 3 mm) where mutual interference of the divided corrugated sheets does not occur, and the maximum axial thermal stress generated at the joint between the corrugated sheet and the nonwoven fabric is calculated. Determined by simulation. As a result, the stress when using the non-divided corrugated sheet (E = 200000 MPa, W = 36 mm) is 7 MPa, while the stress when using the divided corrugated sheet is 2 M
Pa, and it was confirmed that this structure was also effective for stress absorption.

With respect to the structure shown in FIG. 7, the difference between the generated stress and the non-divided filter was examined. A model in which a cylindrical member 25 is interposed between divided filters using a filter (outer diameter φ60 mm, inner diameter φ10 mm) divided into two at the radial midpoint, and assuming that an exhaust gas pressure of 500 kPa is applied thereto, The maximum stress generated in the nonwoven fabric was determined by simulation. As a result, the maximum stress when using a non-divided filter is 12MPa, and when using a divided filter is 6MPa.
a.

When these were subjected to a pressure resistance test at room temperature, the pressure resistance of the non-divided filter was 2000 kPa, and the pressure resistance of the divided filter was 4000 kPa. This improvement in the pressure resistance is due to the stress distribution by the division and the support by the cylindrical member.

[0047]

As described above, in the present invention, since the corrugated sheet inserted between the layers of the nonwoven fabric is provided with the buffer for absorbing the radial force and the axial force, the joint between the nonwoven fabric and the corrugated sheet is provided. Is reduced, the detachment of the joint is prevented, and a decrease in the pressure resistance is suppressed.

In the case where the filter is divided into multiple cylinders and a supporting cylindrical member is interposed between the divided filters, the thermal strain is dispersed and the stress applied to the joint is reduced. In addition, in this structure, since the radial force applied to the split filter is received by the cylindrical member, a decrease in pressure resistance is suppressed even if the joint is disconnected, and breakage of the nonwoven fabric due to gas pressure is effectively prevented. Is done.

Therefore, the filter of the present invention withstands severe use conditions and maintains high durability.

[Brief description of the drawings]

FIG. 1 is a partially broken perspective view showing an outline of an embodiment of a particulate filter of the present invention.

FIG. 2 is an expanded sectional view showing details of a buffer provided on the corrugated sheet.

FIG. 3 is a developed cross-sectional view showing another example of the buffer unit.

FIG. 4 is a developed cross-sectional view showing still another example of the buffer unit.

FIG. 5 is an exploded perspective view showing an example of a buffer unit that absorbs an axial force.

FIG. 6 is an exploded perspective view showing another example of a buffer unit that absorbs an axial force.

FIG. 7 is a longitudinal sectional view of a filter obtained by dividing the filter into multiple cylindrical shapes.

8 (a) is a perspective view of a step-like corrugated sheet forming the buffer section of FIG. 2; and (b) is a perspective view of a conventional corrugated sheet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Particulate trap 2 Cylindrical container 3 Filter support 10 Particulate filter 11 Core 12 Corrugated plate 13 Nonwoven fabric 14 Exhaust gas inflow space 15 Exhaust gas outflow space 16 Thermal diffusion joint part 18, 19, 20, 21, 22 Buffer part 23 Inner filter 24 Outer filter 25 Cylindrical member

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Satoshi Gomei 1-1-1, Koyokita, Itami-shi In Itami Works, Sumitomo Electric Industries, Ltd. (72) Inventor Sadayoshi Otsubo 1-1-1, Koyokita, Itami-shi No. Sumitomo Electric Industries, Ltd. Itami Works (72) Inventor Takahiro Matsuura 1-1-1, Koyokita-Kita, Itami City Sumitomo Electric Industries, Ltd. Itami Works (72) Inventor Zenichiro Kato 1 Toyota Town, Toyota City Toyota In-vehicle company (72) Inventor Hiromichi Yanagihara 1 Toyota Town, Toyota City F-term in Toyota Motor Company (reference) 3G090 AA01 EA01 4D019 AA01 BA02 BB03 BB10 BD01 CA03 CB06 4D058 JA33 JB03 JB25 KA03 KA08 KA11 MA41 SA08

Claims (4)

[Claims] 1. An exhaust gas inflow space and an outflow space defined by a nonwoven fabric by superposing a corrugated sheet and a nonwoven fabric, each made of a heat-resistant metal, and winding the roll into a roll, and fixing one end of a space formed between layers of the nonwoven fabric. In a particulate filter made by alternately creating a space in the radial direction and joining the mutually contacting portions of the corrugated sheet and the non-woven fabric, the corrugated sheet is provided with a buffer portion for absorbing a force in a filter radial direction. A particulate filter characterized by the following. 2. The particulate filter according to claim 1, wherein the corrugated plate has a corrugated shape with a stepped shape, and a step formed between the peaks and valleys of the wave serves as the buffer. 3. A corrugated sheet made of a heat-resistant metal and a nonwoven fabric are superimposed on each other and wound in a roll. In a particulate filter made by alternately creating a space in the radial direction and joining the mutually contacting portions of the corrugated sheet and the nonwoven fabric, the corrugated sheet is provided with a buffer section for absorbing a force in a filter axial direction. A particulate filter characterized by the following. 4. A corrugated sheet made of a heat-resistant metal and a nonwoven fabric are superimposed on each other and wound into a roll, and one end of a space formed between the layers of the nonwoven fabric is caught and an inflow space and an outflow space of the exhaust gas partitioned by the nonwoven fabric are provided. In a particulate filter made by alternately creating spaces in the radial direction, and joining the mutually contacting parts of the corrugated sheet and the nonwoven fabric, the filter is divided into concentric multiple cylinders, and a filter is provided between each divided filter. A particulate filter comprising a heat-resistant cylindrical member held by a support.