JP2006110459A - Exhaust gas filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive exhaust gas filter having a porosity and a gas permeability relating to soot collection imparted as designed and stable in quality and shape. <P>SOLUTION: This exhaust gas filter is installed inside a tubular case 4, and traps particulate matter contained in the exhaust gas (a). A strip-like wire net or a metal fiber felt-like material or their composite matter is spirally rolled into a roll cake shape 18, and the roll cake-shaped object 18 is compressed in the direction of its core to be three-dimensionally compression-molded. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exhaust gas filter, and more particularly to an exhaust gas filter for removing particulates (particulate matter) contained in exhaust gas from a diesel engine.

  Particulates (particulate matter) discharged from diesel engines are mainly composed of soot made of carbon and SOF (soluble organic component) made of high-boiling hydrocarbon components, and a small amount of sulfate (mist form). Although it is composed of a composition containing sulfuric acid component), as a measure to reduce this type of particulates, it is considered to equip a particulate filter in the middle of the exhaust pipe through which exhaust gas from a diesel engine flows. Yes.

As this type of exhaust purification device, conventionally, a flow-through type SOF partial oxidation catalyst having an oxidizing power capable of oxidizing and purifying SOF content in exhaust gas in a filter case provided in the middle of the exhaust pipe, and the SOF There has been proposed an exhaust emission control device equipped with a soot trapping filter having a porous structure that is provided immediately after a partial oxidation catalyst and has a coarse structure so that soot in exhaust gas can be filtered (see, for example, Patent Document 1). .).
Japanese Patent Laid-Open No. 2002-97927 (page 3-4, FIG. 1)

  However, since the conventional soot collection filter using metal fibers is composed of a wire mesh or a sintered metal alternately stacked in the flow direction perpendicular to the exhaust gas, the former easily passes particulates, and the latter Then, there was a problem that the pressure loss was high and easy to clog.

  The present invention has been made to solve such a problem, and the object of the present invention is only to be able to manufacture the filter porosity and gas passage amount related to soot collection as designed. In other words, it is to provide an inexpensive exhaust gas filter having a stable quality and shape.

  In order to solve the above problems, the present invention is configured as follows.

  The invention according to claim 1 is an exhaust gas filter that is provided in a cylindrical case and captures particulates contained in the exhaust gas. In the exhaust gas filter, a belt-like wire mesh, a metal fiber felt-like material, or a composite thereof. The exhaust gas filter is characterized by three-dimensionally compression-molding the roll cake-like body by compressing the roll cake-like body in the direction of the winding core.

  The invention according to claim 2 is the exhaust gas filter according to claim 1, characterized in that the wire mesh is a knitted wire mesh formed by knitting metal fine wires with a knitting machine.

The invention according to claim 3 is the exhaust gas filter according to claim 1, wherein the apparent density of the filter is 1 to 3 g / cm ³ .

  As described above, the invention according to claim 1 is an exhaust gas filter that is provided in a cylindrical case and captures particulates contained in exhaust gas. Alternatively, these composites are wound into a roll cake to form a roll cake, and the roll cake is compressed in the direction of the winding core and three-dimensionally compression-molded to form a wire mesh or a metal fiber felt. Thus, the filter was formed by three-dimensionally intricately intermingling metal fine wires.

  As a result, the following excellent effects could be obtained.

That is,
(1) As described above, the fine metal wires constituting the metal mesh or metal fiber felt-like material are intricately intertwined in three dimensions, so that the particulate is a metal mesh or metal fiber felt-like material. Although the number of collisions with the metal fine wire constituting the wire increases and the increase in the exhaust gas resistance is smaller than the rate of increase in the number of collisions of the particulates, the differential pressure (ΔP) of the filter is small. Therefore, the capture rate of the particulates in the exhaust gas is greatly increased.

  (2) Since the metal ultrafine wires constituting the metal mesh, the metal fiber felt-like material, and the like are intricately entangled three-dimensionally, the variation in the particle capture rate can be reduced.

  (3) Further, since the metal ultrafine wires constituting the metal mesh or the metal fiber felt-like material are intricately entangled three-dimensionally, the strength of the filter increases, and it can be used at a high differential pressure. it can. Further, the deformation of the filter in use is extremely small.

  (4) It can be manufactured with an inexpensive metal material as compared with a conventional filter using a sintered material.

  (5) Optimal wire mesh by controlling the tension for winding wire mesh or metal fiber felts in a spiral shape with respect to the wire diameter, material, knitting method, filter shape, and volume density of the ultrafine wire wire. The filter can be manufactured. As a result, filters with various specifications can be manufactured for different purposes.

  (6) As a result of winding a wire mesh metal fiber felt or the like under tension, lateral displacement during compression molding is eliminated, and the outer shape of the filter can be made accurately. For this reason, when the filter is loaded in the case, the generation of a gap between the filter and the case is prevented, and the decrease in the particle capture rate can be prevented.

  In the invention according to claim 2, since the wire mesh is a knitted wire mesh formed by knitting a metal fine wire with a knitting machine, when the metal wire is compression-molded as compared with a wire mesh assembled in a vertical and horizontal mesh shape, Becomes three-dimensionally deformed, and it becomes easy to capture particulates in the exhaust gas.

In the third aspect of the present invention, the apparent density of the filter is 1 to 3 g / cm ³ , so that the capture rate of particulates in the exhaust gas is greatly increased.

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

  In FIG. 1, reference numeral 3 denotes an exhaust gas purification device, which is disposed in a cylindrical case 4 in a harmful gas purification device 5 that purifies CO (carbon monoxide), HC (hydrocarbon), and the like, and in exhaust gas a of a diesel engine. A particulate removal device 6 for removing the contained particulate matter is sequentially provided.

  In the harmful gas purification device 5, an oxidation catalyst such as Pt (platinum) is attached to or coated on the cell walls 8 of the honeycomb core 7 as in the conventional case. On the other hand, the filter 15 applied to the particulate removal device 6 is formed in a roll cake shape or a spiral shape (hereinafter simply referred to as a roll cake shape) as shown in FIG.

  In order to make the structure of the filter 15 easy to understand, a method for manufacturing the filter 15 will be described.

  (A) First, a knitted wire mesh 17 is prepared by knitting a plurality of ultrafine wires 16 made of stainless steel with a knitting machine (not shown) (see FIG. 3).

  (B) A roll cake-like intermediate body 18 is formed by winding the knitted wire mesh 17 in a spiral shape while applying a predetermined tension (see FIG. 4).

  (C) This roll cake-like intermediate body 18 is inserted into a concave mold 19 (see FIG. 5).

  (D) Next, the piston 20 of the press machine is set on the roll cake-like intermediate body 18 installed in the concave mold 19 (see FIG. 6).

  (E) Next, as shown in FIG. 7, when the roll cake-like intermediate body 18 is compressed in the direction of the winding core (axial core) b by the piston 20 of the press, the roll in the concave mold 19 is obtained. The cake-like intermediate body 18 is compressed in the direction of the winding core (axial core) b, and at the same time, pressed against the bottom surface and the side wall surface of the mold 19 as indicated by arrows.

  For this reason, the roll cake-like intermediate body 18 has a three-dimensionally complex filter 15 in which a plurality of ultrafine wires 16 constituting the wire mesh 17 are regulated while the outer shape is regulated by the concave mold 19. It becomes.

  Here, although the ratio which compresses the intermediate body 18 is based also on the knitting method of a wire mesh, and the tension | tensile_strength of winding, about 10 to 90% reduction of the thickness of the intermediate body 18 is preferable, More preferably, about 30 to 50% reduction preferable.

  The filter 15 can be manufactured in a disk shape as well as a polygonal shape such as a hexagonal shape and an octagonal shape for final press molding.

The apparent density of the filter 15 is preferably in the range of 1 to ³ g / cm ³ . When the apparent density of the filter is less than 1 g / cm ³ , there is a problem that the collection rate decreases. On the other hand, when the apparent density of the filter exceeds ³ g / cm ³ , the collection rate increases, but there is a problem that the differential pressure increases.

  The ventilation resistance of the filter 15 is preferably in the range of 10 to 15 kPa at the engine rated load.

  As the strands (metal wires) 16 constituting the wire mesh 17, for example, stainless steel wires are desirable. Further, the wire diameter of the wire 26 is desirably in the range of 0.1 to 0.5 mm. Further, the mesh interval of the metal mesh 15 is preferably in the range of 1 to 4 mm.

  Furthermore, the ultrafine wire 16 constituting this wire mesh is impregnated and coated with a metal or metal oxide such as Pt (platinum), V (vanadium), Cu (copper), Mn (manganese), as in the conventional case. It is also possible to adhere and coat.

  When the filter 15 is installed in the case 4 of the exhaust gas purification device 3, as shown in FIG. 1, the winding core (axial core) b of the filter 15 is coincident with or parallel to the axial core c of the case 4. Install to be.

  Next, the effect | action of this exhaust gas purification apparatus 3 is demonstrated.

  As shown in FIG. 8, when diesel exhaust gas a is introduced from the inlet 21 of the exhaust gas purification device 3, Pt (platinum) or the like adhered or coated on the cell walls 8 of the honeycomb core 7 constituting the harmful gas purification device 5. This oxidation catalyst oxidizes, burns and removes CO, HC, etc. in the exhaust gas a.

  The exhaust gas a that has passed through the harmful gas purification device 5 flows into the particulate removal device 6 at the subsequent stage.

  As already described, the filter 15 as the particulate removal device 6 is included in the exhaust gas a because the plurality of ultrafine wires 16 constituting the wire mesh 17 are intricately entangled three-dimensionally. The number of times that the particulates collide with the plurality of ultrafine wires 16 constituting the metal mesh 17 is increased, and is easily captured by the ultrafine wires 16 constituting the metal mesh 17.

  In other words, as shown in the schematic diagram (see FIG. 9), the wire mesh 17 wound in a roll cake shape is bent in a wave shape in the direction of the winding core (shaft core) b, so that it is included in the exhaust gas a. The number of times the particulates collide with the plurality of ultrafine wires 16 constituting the wire mesh 17 increases. As a result, the particulates contained in the exhaust gas a are likely to be captured by the ultrafine wire 16 constituting the wire mesh 17.

The NO ₂ (nitrogen dioxide) generated by the harmful gas purification device 5 becomes NO (nitrogen oxide) on the wire mesh 17 of the particulate removal device 6. On the other hand, C (carbon) is oxidized on the wire mesh 17 to become CO ₂ (carbon dioxide) and discharged from the outlet 22.

  On the other hand, the particulates trapped and accumulated in the filter 15 are impregnated, coated, adhered, and coated on the metal wire 16, such as Pt (platinum), V (vanadium), Cu (copper), Mn (manganese), and metal oxides. Oxidized and burned by things.

  In addition, the filter 15 itself is also regenerated through a series of operations of “capturing and accumulating” → “oxidation and combustion” of the particulates.

  The filter is manufactured by winding a wire mesh in a spiral shape and then compression-molding the wire mesh in the direction of the winding core. The filter is, for example, a metal fiber felt-like material, or a wire mesh and a metal fiber felt-like material. It is also possible to produce a composite with

  On the other hand, as shown in FIG. 10, the filter 15 is changed to a symbol X by changing the wire mesh knitting pattern, the wire diameter of the wire, etc. in the central portion A, the outer intermediate portion B, and the outermost outer portion C. A smooth convex flow velocity distribution can be leveled as indicated by symbol Y.

(Example)
A stainless steel wire mesh was wound in a spiral shape and then compression molded in the direction of the core to produce a roll cake filter. The dimensions and apparent density of the filter are as follows.

(1) Outer diameter: 350 mm,
(2) Thickness: 60mm
(3) Apparent density: 1.5 g / cm ³
An exhaust gas purification device 3 (see FIG. 1) having this filter 6 mounted on the rear stage of the harmful gas purification device 5 is installed in an exhaust gas passage of a 440 kw 6-cylinder light oil-fired supercharged diesel engine, and is contained in the exhaust gas. The particulate capture rate was measured.

  As a result, the particulate capture rate was 42 to 56% depending on the engine load, and the filter differential pressure was 4 to 10 kPa. At that time, since the nitrogen oxides oxidized by the harmful gas purification device 5 burn carbon particles, the differential pressure of the filter did not further increase.

It is sectional drawing of the exhaust gas purification apparatus to which the filter for exhaust gas of this invention is applied. 1 is a perspective view of an exhaust gas filter according to the present invention. It is a top view of the metal mesh applied to the filter of the present invention. It is a perspective view of the intermediate body of the filter of this invention. It is explanatory drawing which inserted the intermediate body of the filter in the concave mold. It is explanatory drawing which set the piston of the press to the intermediate body of the filter. It is press work explanatory drawing of the intermediate body of a filter. It is operation | movement explanatory drawing of the exhaust gas purification apparatus to which the filter for exhaust gas of this invention is applied. It is action | operation explanatory drawing of the filter of this invention. It is explanatory drawing which shows other embodiment of the filter of this invention.

Explanation of symbols

a exhaust gas 4 cylindrical case 15 exhaust gas filter 17 wire mesh 18 roll cake

Claims (3)

In an exhaust gas filter that is provided in a cylindrical case and captures particulates contained in the exhaust gas, a strip-shaped wire mesh or metal fiber felt-like material or a composite of these is wound into a roll cake shape An exhaust gas filter, wherein the roll cake-like body is compressed in the direction of the winding core and three-dimensionally compression-molded. 2. The exhaust gas filter according to claim 1, wherein the wire mesh is a knitted wire mesh formed by knitting metal fine wires with a knitting machine. The exhaust gas filter according to claim 1, wherein the apparent density of the filter is 1 to ³ g / cm ³ .

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