JP2001164923A - Particulate removal filter unit and method of manufacturing the filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a particulate removing filter unit formed in a compact manner and be simple in structure. SOLUTION: This particulate removing filter unit comprises a case 10 located in an exhaust system; and a filter 12 disposed in the case 10 and having a plurality of mesh holes 24 to capture particulate as an exhaust gas flow passes therethrough. The particulate removing filter unit is formed such that the filter 12 is formed of a high heat-resisting material, such as a nichrome foil, so that the captured particulate are directly heated and burnt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particulate (fine particle) removing filter unit having a filter regenerating function, which is interposed in a vehicle exhaust system or the like, and a method of manufacturing a filter used in the unit.

[0002]

2. Description of the Related Art Conventionally, in order to prevent air pollution due to particulates such as carbon, soot and HC contained in exhaust gas of an engine or the like, a particulate filter for trapping these in an exhaust gas passage is provided. ing. When a certain amount of these particulates generated by incomplete combustion accumulates on the filter, they are incinerated by some heating means and the filter is regenerated.

[0003] However, in particular, the particulate filter unit mounted on an exhaust system of a vehicle or the like is desirably of a compact configuration due to space limitations, but there is a limit to downsizing. This is because, in the conventional technology, ceramic or stainless steel is usually used as a filter material. However, if the temperature is excessively high, the filter is damaged by oxidation or the like. This is because the particulates deposited on the substrate were indirectly heated.

[0004] For example, Japanese Patent Application No. 9-130542 discloses a filter regenerating apparatus in which a high temperature gas is blown onto a filter on which graphite or the like is deposited and burned. In this technique, in addition to the filter main body, components such as an air blower that sucks air that is a source of high-temperature gas, a preheating unit that heats the sucked air, a fuel addition unit, an oxidation catalyst, and the like are further supplied. Various sensors and control controllers are also required to control the fuel addition means so that the hot gas does not become excessively hot.The filter unit as a whole requires a very large number of parts and requires delicate control. It was a very complicated structure.

[0005]

SUMMARY OF THE INVENTION On the other hand, Japanese Patent Application No. Hei.
-226108 describes a filter structure in which a wire mesh heater in contact with a particulate filter is arranged. In this technique, when a predetermined amount of particulates accumulates, the heater is energized and indirectly heated to burn the particulates.

However, in the filter structure described in this publication, a heater must be provided separately from the filter, so that the number of parts is increased, and a filter made of a ceramic material needs to avoid excessive heating. Therefore, there is a problem that the configuration is relatively complicated, for example, the wire of the heater wire mesh has a double structure so as to uniformly heat the filter.

The present invention has been made in consideration of the above-mentioned problems of the prior art.
Provided is a particulate removal filter unit having a compact and simple structure. Further, the present invention provides a particulate removal filter unit having high particulate collection efficiency and a long product life. Further, the present invention provides a method of manufacturing a filter used in the filter unit, which is low in cost and excellent in mass productivity.

[0008]

In order to achieve the above object, a particulate removal filter unit according to the present invention is provided with a case interposed in an exhaust system, and disposed in the case to reduce an exhaust gas flow. A particulate removal filter unit comprising a filter having a plurality of mesh holes for collecting particulates while ventilating,
The filter is characterized by being formed of a high heat-resistant material such as nichrome foil so that the collected particulates can be directly burned off by heating.

In the present invention, it is preferable that a plurality of the filters are arranged in a multilayer shape in the case, and the plurality of filters have different mesh hole diameters.

[0010] Further, the method for producing a particulate removal filter according to the present invention comprises the steps of:
The method includes a step of masking into a filter shape, a step of forming a mesh hole in a part of the filter shape by etching, and a step of cutting into a filter shape.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

== Configuration of Particulate Removal Filter Unit == FIG. 1 is a diagram showing a conceptual configuration in which the particulate removal filter unit of the present embodiment is interposed in an exhaust system such as a vehicle engine. FIG. 2 is an enlarged view showing the filter part of FIG. 1 in detail. This unit is, in particular, EGR
It is suitably used as a part of a filter system.

The case 10 has an exhaust gas intake port 10a and an exhaust port 10b, and a filter 12 is provided at the center of the case 10. The terminal 14 of the filter 12 is connected to the electric wire 1 from the current control unit 16.
8 is connected so that the entire filter 12 can be energized.

The filter 12 has a substantially elliptical plate shape made of heat-resistant nichrome foil, and includes a filter body 20 and terminal portions 14 protruding from both ends of the major axis of the ellipse. . The filter main body 20 is formed with a mesh 22 having a sufficiently small hole diameter to collect particulates such as carbon, soot, and HC contained in the exhaust gas. For example, to remove graphite, very fine mesh holes 24 having a hole diameter of 30 microns or less are used.
Must be accurately formed.

== Operation of Filter Unit == Next, the operation of the particulate filter unit having the above configuration will be described. The exhaust gas sent from the intake port 10a flows through the mesh hole 24 of the filter 12 to the exhaust port 10b. The exhaust gas contains various particulates such as carbon generated by incomplete combustion, and these are collected by the mesh portion 22 of the filter. When the accumulated amount of the collected particulate exceeds a certain value and the clogging of the mesh hole 24 considerably proceeds, the filter 12 is energized through the electrode terminal portion 14 and the filter itself is heated to a high temperature. Then, the particulates attached to the mesh part 22 are burned off. For example, to burn graphite, about 7
It is necessary to heat to above 00 ° C. By burning off the particulates, the filter 12 is regenerated and again traps the particulates in the exhaust gas.

The filter 12 of this embodiment has a case 1 in which the outer peripheral portion of the filter body 20 is sealed.
0, and all the exhaust gas sent into the case 10 from the intake port 10a is configured to pass through the mesh portion. However, a plurality of similar filter units may be provided in parallel or a bypass passage may be appropriately provided. And the filter 12
The exhaust gas may be guided to the bypass passage at the time of power supply regeneration.

== Comparison of Heat Resistance and Oxidation Resistance == The heat resistance and oxidation resistance of the nichrome filter of this embodiment were compared with the stainless steel filter described in the conventional example. The comparison between the two was performed by heating each sample in an electric furnace and examining the degree of oxidation of each sample over time. Tests were conducted at various heating temperatures, and FIG.
It is a graph which shows a mode until 24 hours progress as a result of having performed at ° C. The vertical axis of the graph indicates the mass increase (g / m ² ) due to oxidation per unit area. As can be seen from the results shown in the figure, the oxidation progress rate of the nichrome filter is much slower than that of the stainless steel filter. Thus, the heat resistance and oxidation resistance (耐, ×, □ in the figure) of the nichrome filter are far superior to those of the stainless steel filter (図 in the figure).
Although the test results are not shown, the same applies to ceramic filters. In the present invention, since the filter itself is energized and the filter is directly heated, a material having high heat resistance such as nichrome is used as the material of the filter.

In the above-described embodiment, one filter having a mesh hole having a single hole diameter is provided in the case. However, more preferably, a plurality of filters are provided, and filters having different mesh hole diameters are provided in multiple layers. I do. The mesh holes are arranged in descending order of the mesh hole diameter from the upstream side of the exhaust gas passage, and each filter is controlled so as to be separately energized. The energization is performed when each filter is clogged to a predetermined level. In the filter unit having such a configuration, various particulates having different sizes can be collected by the filters having the mesh hole diameters corresponding to the respective sizes, so that the collection efficiency and the life of each filter are further improved. Is done.

== Method of Manufacturing Heating Filter == Next, a method of manufacturing the nichrome foil filter of the above embodiment will be described with reference to FIG. First, a nichrome foil having a predetermined thickness is prepared, and masked into a filter shape, that is, a substantially elliptical shape having end support protrusions in this embodiment. Next, a mesh hole is formed in the masked inside by etching. Finally, cut out according to the shape of the filter.

The above etching method will be described in detail. First, degreasing and cleaning of fingerprints and dust on the nichrome foil masked into a filter shape are performed. Next, a film-shaped photosensitive resist is attached to the portion (lamination process), and the film is cured by irradiating ultraviolet rays to portions other than the portions where the mesh holes are formed (exposure process). The uncured portion of the film is dissolved and removed with a sodium carbonate solution (development step). Furthermore, using ferric chloride and cupric chloride solution,
The nichrome foil in the portion where the photosensitive resist sheet has been dissolved and removed is etched. Finally, the remaining photosensitive resist is
Peel off using sodium hydroxide solution. According to such an etching technique, a mesh hole having a small hole diameter of, for example, 30 μm or less can be accurately formed in a thin foil material made of nichrome. Moreover, this method is low cost and excellent in mass productivity.

[0021]

According to the particulate removal filter unit of the present invention, a filter having excellent heat resistance and durability is directly energized and heated to regenerate the filter, so that a compact and simple structure exhaust system filter unit is provided. can do.

When a plurality of filters having different mesh hole diameters are arranged in a multilayer structure in the case, the collection efficiency of particulates is further improved, and the product life of each filter can be extended.

According to the filter manufacturing method of the present invention, a filter excellent in heat resistance and durability which can be used in the above-mentioned particulate removal filter unit can be manufactured at low cost and with good mass productivity. can do.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conceptual configuration in which a particulate removal filter unit of the present invention is interposed in an exhaust system.

FIG. 2 is an enlarged view showing a filter portion of FIG. 1 in detail.

FIG. 3 is a graph showing test results comparing heat resistance and oxidation resistance of a nichrome filter and a stainless steel filter.

FIG. 4 is a block diagram showing steps of manufacturing the nichrome filter of the present invention.

[Explanation of symbols]

 10 case 12 filter 24 mesh hole

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroaki Komatsu 3-12-3 Nakamachidai, Tsuzuki-ku, Yokohama-shi, Kanagawa Prefecture Inside Tokyo Roki Co., Ltd. (72) Inventor Teru Kageyama 5 Asahioka, Kanbe-cho, Shenzhen-gun, Hiroshima, Inc. Within Ishii Notation (72) Inventor Kajioka Hide 2-10-1 Agananami, Kure City, Hiroshima Prefecture Inside Hiroshima Prefectural Industrial Technology Center (72) Inventor Takahiro Tsutsumoto 2-10-1 Agananami, Kure City, Hiroshima Hiroshima Prefectural Western Industrial Technology Center (72) Inventor Seiwa Tokayama 2-10-1 Agananami, Kure City, Hiroshima Pref. Hiroshima Prefectural Western Industrial Technology Center F-term (reference) CB06 CB08 4D058 JA12 JB03 JB39 KB11 MA42 SA08

Claims (3)

[Claims] 1. A particulate filter comprising: a case interposed in an exhaust system; and a filter disposed in the case and having a plurality of mesh holes for trapping particulates while ventilating an exhaust gas flow. A particulate removal filter unit, wherein the filter is made of a high heat-resistant material such as nichrome foil so that the collected particulates can be directly heated and burned off. Filter unit. 2. The particulate removal filter unit according to claim 1, wherein a plurality of the filters are arranged in a multilayer shape in the case, and the plurality of filters have different mesh hole diameters. 3. A step of masking a sheet made of a high heat-resistant material into a shape of a filter; and a step of forming a mesh hole in a part of the shape of the filter by etching.
A method for producing a particulate removal filter, the method including cutting out into a filter shape.