JP2006022737A - Discharge tube supporting structure for exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means capable of facilitating an assembly process in holding a plurality of discharge tubes in parallel with each other in an exhaust emission control device for purifying exhaust gas by effect of a high voltage. <P>SOLUTION: A supporting block 15 is constituted by an outer annular body 15a through which the plurality of the discharge tubes 4a pass, and a positioning piece 15b for positioning the plurality of the discharge tubes 4a mutually. The plurality of the discharge tubes 4a are inserted into the outer annular body 15a, and then, the positioning piece 15b is inserted between the plurality of the discharge tubes 4a, and thereby the plurality of the discharge tubes 4a can be mutually positioned. Accurate work such as inserting each of the discharge tubes 4a into a large number of through holes corresponding to a cross section shape of the discharge tube 4a can be dispensed with, and the assembly process can be facilitated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exhaust gas purifying apparatus for treating exhaust gas of an internal combustion engine by applying a high voltage, and more particularly to a discharge tube support structure for supporting a plurality of discharge tubes.

As a technique for purifying exhaust gas from an internal combustion engine such as a vehicle, in recent years, it has a cylindrical outer peripheral electrode and a rod-shaped inner electrode extending in the exhaust gas flow direction along the axis of the outer peripheral electrode. In other words, a so-called transmission type or straight flow type exhaust gas purifying apparatus has been proposed in which a high voltage is applied to the gas to generate a plasma state and purify the passing exhaust gas (see, for example, Patent Document 1). In such an apparatus, a substance such as NOx in the exhaust gas passing through is converted to N ₂ etc., and PM (particulate matter) in the exhaust gas is charged by discharge from the internal electrode, and the charge and PM is adsorbed on the outer peripheral electrode side by interaction with the electric field between the inner and outer electrodes, or is captured by a collecting device provided at the rear, and is generated by active gas (NO ₂ , O ₃ , OH, etc.) generated by discharge Incinerated at low temperature.

JP 2002-30920 A

  By the way, in the apparatus of Patent Document 1, a plurality of discharge tubes having outer peripheral electrodes formed on the outer peripheral surface are integrally fixed to the container via an insulating mounting frame. However, a large number of through holes for accommodating the discharge tube formed in the mounting frame have a shape and a size that substantially match the cross-sectional shape of the discharge tube in order to provide airtightness. There is a drawback in that the operation of passing the discharge tubes one by one through the through holes requires accuracy.

  Accordingly, an object of the present invention is to provide means capable of facilitating the assembly process when integrally supporting a plurality of parallel discharge tubes in an exhaust gas purification apparatus that purifies exhaust gas by the action of a high voltage.

  A first aspect of the present invention is a discharge tube support structure that integrally supports a plurality of parallel discharge tubes of an exhaust gas purification apparatus, wherein the plurality of discharge tubes pass through an outer annular body, and the plurality of discharge tubes. A discharge tube support structure for an exhaust gas purifying apparatus, comprising a positioning piece for mutual positioning.

In the first aspect of the present invention, a plurality of discharge tubes can be positioned relative to each other by inserting a plurality of discharge tubes through the outer annular body and then inserting a positioning piece between the plurality of discharge tubes.
An accurate operation of passing the discharge tubes one by one through the many through holes corresponding to the cross-sectional shape of the discharge tube is not necessary, and the assembly process can be facilitated.

  According to a second aspect of the present invention, there is provided a discharge tube support structure for an exhaust gas purifying apparatus according to claim 1, wherein an outer edge of the outer annular body is in close contact with an inner peripheral surface of a container of the exhaust gas purifying apparatus, and the outer annular shape is provided. The discharge tube support structure is characterized in that a space between an upstream side and a downstream side in the container is sealed by a body and the positioning piece.

  In the second aspect of the present invention, the discharge tube support structure can be provided with a function as a sealing member by sealing between the upstream side and the downstream side in the container.

  In the discharge tube support structure according to the present invention, the outer annular body and the positioning piece may be composed of an insulator as in the third aspect of the present invention, and these are composed of a conductor as in the fourth aspect of the present invention. May be. When the discharge tube support structure is made of an insulator, the discharge tube support structure supports the internal electrode together with the discharge tube by fixing the discharge tube support structure to the upstream and / or downstream ends of the discharge tube. It becomes possible. When the discharge tube support structure is made of a conductor, an outer peripheral electrode is disposed on the outer periphery of the discharge tube, and the discharge tube support structure and the outer peripheral electrode are electrically connected to each other, so that the discharge tube support structure is connected to each outer peripheral electrode. A function as a conduction means can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  In FIG. 1, an exhaust gas purification apparatus 1 according to an embodiment of the present invention is suitable when applied to a vehicle, and is configured as a plasma reactor or a corona reactor. This exhaust gas purification device 1 is incorporated in an exhaust pipe constituting an exhaust system of the internal combustion engine in order to purify exhaust gas discharged from a combustion chamber of an internal combustion engine (not shown).

  The exhaust gas purification apparatus 1 includes an upstream case 2a, a downstream case 2b, and an intermediate case 3. The upstream case 2a, the downstream case 2b, and the intermediate case 3 are formed of a metal, particularly a heat resistant material such as SUS. The exhaust gas discharged from the combustion chamber of the internal combustion engine is introduced into the upstream case 2a in the direction indicated by the white arrow in FIG. The exhaust gas purified inside the intermediate case 3 is discharged to the outside from the downstream case 2b through an exhaust pipe (not shown).

  The upstream case 2a and the downstream case 2b have substantially the same diameter as the exhaust pipe and end portions 21a and 21b having a substantially cylindrical shape, and an oval or racetrack cross-sectional shape having a larger cross-sectional area than the exhaust pipe. Large diameter portions 22a and 22b, and cone portions 24a and 24b formed between the end portion 21a and the large diameter portion 22a and between the end portion 21b and the large diameter portion 22b are included. The end portions 21a and 21b constitute an inlet or an outlet for connecting to the exhaust pipe. Between the upstream case 2a and the downstream case 2b, a cylindrical intermediate case 3 having an oval or racetrack cross-sectional shape is airtightly coupled.

  In the present embodiment, the processing unit 6 is configured by the discharge tube 4 a, the outer peripheral electrode 4 b, and the internal electrode 5. Each discharge tube 4a has a cylindrical shape, and a cylindrical outer peripheral electrode 4b is formed on the outer peripheral surface thereof. Flat annular end faces perpendicular to the axial direction are formed at both ends in the longitudinal direction of the discharge tube 4a, that is, upstream and downstream ends, respectively. It is preferable to use a ceramic such as an insulator or an insulator such as alumina for the discharge tube 4a. For the outer peripheral electrode 4b, it is preferable to use a conductor having heat resistance and corrosion resistance, such as Li plating or shrink fitting of a SUS cylinder, and to install the conductor in an airtight manner with respect to the discharge tube 4a. is there.

  Support blocks 15 and 15, which are discharge tube support structures in the present invention, are airtightly fixed to the upstream and downstream openings of the intermediate case 3 via annular alumina mats 17 and 17. A plurality of (24 in this embodiment) discharge tubes 4a are fixed between the support blocks 15 and 15 in parallel with each other.

  As shown in FIG. 2, the support block 15 includes an outer annular body 15a through which the plurality of discharge tubes 4a pass, and a positioning piece 15b for positioning the plurality of discharge tubes 4a relative to each other. Both the outer annular body 15a and the positioning piece 15b are made of an insulator such as alumina.

  The outer annular body 15a is formed by adhering two arc-shaped pieces 51 and two connecting pieces 52 in an annular shape. These arc-shaped pieces 51 and connecting pieces 52 have a support arc-shaped surface 53 having substantially the same curvature as that of the outer peripheral surface of the discharge tube 4a when viewed from the front, and a joining plane 54 that is also linear when viewed from the front.

  The positioning piece 15b has a joining plane 55 that forms an equilateral triangle when viewed from the front, and a support arcuate surface 56 that forms an arc centered on each vertex of the equilateral triangle, and the curvature of the support arcuate surface 56 is the discharge tube 4a. Is substantially equal to the curvature of the outer peripheral surface.

  A mounting abutment surface 25 (see FIG. 1) is formed on the outer edge of the outer annular body 15a and the support arcuate surfaces 53 and 56 of the positioning piece 15b on the outer side of the apparatus. The mounting abutment surface 25 has an annular shape complementary to the end shape of the discharge tube 4a (cylindrical in this embodiment). The upstream end and the downstream end of each discharge tube 4a are fixed to the mounting abutment surface 25 of the support block 15 with a flat and annular gasket (not shown) having heat resistance and elasticity, respectively. As a material of the gasket 27, asbestos, heat resistant resin, heat resistant rubber, metal, or the like can be used. The inner diameter of the outer edge of the circular through-hole formed by the outer annular body 15a and the positioning piece 15b or the plurality of positioning pieces 15b is made equal to the inner diameter of the discharge tube 4a. The axes are aligned.

  The positioning piece 15b is fixed to the outer peripheral surface of the discharge tube 4a set on the support arcuate surface 53 of the outer annular body 15a as shown in the drawing so that the support arcuate surface 56 is adapted. Another discharge tube 4a (not shown) is set on the other support arcuate surface 56 of the positioning piece 15b. By repeating this alternately, the space inside the outer annular body 15a is sealed. Further, the outer edge of the outer annular body 15 a is airtightly joined to the inner peripheral surface of the intermediate case 3 via an alumina mat 17. Therefore, the space between the upstream side and the downstream side in the intermediate case 3 is sealed by the outer annular body 15a and the positioning piece 15b. In addition, it is preferable to arrange a sheet-like sealing member or a fluid sealing material such as a ceramic adhesive on each joint surface of the outer annular body 15a, the positioning piece 15b, and the discharge tube 4a. Alternatively, the use of a sealing material can improve the hermeticity of the apparatus, and the dimensional variations of the individual discharge tubes 4a can be varied depending on the degree of freedom of the posture of the individual positioning pieces 15b due to the elasticity of these sealing materials or sealing members. Can be absorbed.

  The arrangement of the discharge tubes 4a in the support block 15 is as shown in FIG. That is, a set of four discharge tubes 4a in a vertical row is arranged in parallel with each other in three rows, and a set of three discharge tubes 4a in a vertical row is arranged between these columns and on both sides, for a total of four rows. Arranged in columns. The discharge tubes 4a in each column are arranged with their vertical positions shifted by the approximate radius of the discharge tube 4a with respect to the adjacent discharge tubes 4a, thereby reducing the distance between the columns and thus the width dimension of the entire apparatus. The reduction of is planned.

  On the other hand, as shown in FIG. 1, a support block 115, which is another discharge tube support structure, is airtightly fixed via an annular alumina mat 117 inside the intermediate portion of the intermediate case 3. As shown in FIG. 4, the support block 115 includes an outer annular body 115a through which the plurality of discharge tubes 4a pass, and a plurality of positioning pieces 115b for positioning the plurality of discharge tubes 4a relative to each other. Both the outer annular body 115a and the positioning piece 115b are made of a conductor such as SUS.

  The outer annular body 115a is formed by adhering two arc-shaped pieces 151 and two connecting pieces 152 in an annular shape. These arc-shaped pieces 151 and connecting pieces 152 have a support arc-shaped surface 153 having substantially the same curvature as that of the outer peripheral surface of the outer peripheral electrode 4b when viewed from the front, and a joining plane 154 that also forms a straight line when viewed from the front.

  The positioning piece 115b has a joining plane 155 that forms an equilateral triangle when viewed from the front, and three support arcuate surfaces 156 that form an arc centered on each vertex of the equilateral triangle, and the curvature of the support arcuate surface 156 has an outer periphery. The curvature is substantially equal to the curvature of the outer peripheral surface of the electrode 4b.

  The positioning piece 115b is fixed so that the support arcuate surface 156 is fitted to the outer peripheral electrode 4b of the outer peripheral surface of the discharge tube 4a set on the support arcuate surface 153 of the outer annular body 115a as shown in the figure. Another discharge arc 4a (not shown) is set on the other support arcuate surface 156 of the positioning piece 115b, and the space inside the outer annular body 115a is sealed by repeating this alternately. The outer edge of the outer annular body 115 a is airtightly joined to the inner peripheral surface of the intermediate case 3 via an alumina mat 117. Therefore, the space between the upstream side and the downstream side in the intermediate case 3 is sealed by the outer annular body 115a and the positioning piece 115b. Note that it is preferable to impart conductivity and airtightness to each joint between the support block 115 and the outer peripheral electrode 4b by brazing or the like.

  In FIG. 1 again, the internal electrode 5 is substantially rigid and is disposed on the central axis of the discharge tube 4a and the central axis of the outer peripheral electrode 4b and extends in the flow direction of the exhaust gas. For each internal electrode 5, it is preferable to use a tungsten press-fired product or SUS having good discharge characteristics.

  The upstream end of each internal electrode 5 is fixed to an electrode support frame 8 as shown in FIG. 1 and FIG. 3 outside the discharge tube 4a and the outer peripheral electrode 4b, whereby the two are electrically connected. . The electrode support frame 8 is made of a heat-resistant conductive material such as metal, particularly SUS, and as shown in FIG. 3, the seven support arms 8a are arranged with the vertical direction as the longitudinal direction, and the seven support arms 8a. And a single support arm 8a that intersects in a substantially orthogonal direction.

  The downstream side of each internal electrode 5 is fixed to the electrode support frame 18 outside the discharge tube 4a and the outer peripheral electrode 4b. In addition, by making the coupling between one or both ends of the internal electrode 5 and one or both of the electrode support frames 8 and 18 slidable, bending due to the elongation of the internal electrode 5 can be suppressed. .

  In FIG. 1 again, a power supply line 10 is connected to the electrode support frame 8, and the power supply line 10 is connected to a power supply unit (not shown). Further, a sleeve 11 covering the power supply line 10 and a holding material 12 are fixed to the electrode support frame 8, and the electrode support frame 8 is fixed to a support block 15 via the sleeve 11 and the holding material 12. . The sleeve 11 and the holding material 12 are made of an insulating material such as an insulator.

  A conductive wire 13 is connected to the support block 115, and the conductive wire 13 is electrically grounded by being connected to an appropriate body earth point of a vehicle body (not shown). The conductive wire 13 is covered with a sleeve 14 made of an insulator such as an insulator, and the sleeve 14 is fixed to the intermediate case 3. Since the plurality of outer peripheral electrodes 4b are electrically connected to each other by the support block 115, all the outer peripheral electrodes 4b are grounded. As the power supply unit, any one of a DC high-voltage power supply, an AC high-voltage power supply, a DC pulse power supply, and a DC / pulse superimposed power supply can be used.

In the exhaust gas purification apparatus 1 configured as described above, a high voltage is applied between the outer peripheral electrode 4b and the internal electrode 5 of each processing unit 6 by using the internal electrode 5 as an anode in accordance with the start of the internal combustion engine. Applied. When the exhaust gas from the combustion chamber of the started internal combustion engine is introduced from the upstream case 2a into the discharge tube 4a, air discharge between the internal electrode 5 and the outer peripheral electrode 4b of each processing unit 6 occurs. plasma state occurs, the predetermined substance such as NOx in the exhaust gas is activated and is the reaction is promoted is converted into substances such as N _2. Further, PM in the supplied exhaust gas is charged by the discharge from the internal electrode 5 and is adsorbed by the discharge tube 4a due to the interaction with the electric field between the internal electrode 5 and the outer peripheral electrode 4b. The combustion or oxidation is promoted by the active gas generated.

  Here, in the present embodiment, the support blocks 15 and 115 which are the discharge tube support structure in the present invention are positioned with respect to the outer annular bodies 15a and 115a through which the plurality of discharge tubes 4a pass, and the plurality of discharge tubes 4a. Since the positioning pieces 15b and 115b are configured, a plurality of discharge tubes 4a are inserted into the outer annular bodies 15a and 115a, and then the positioning pieces 15b and 115b are inserted between the plurality of discharge tubes 4a. The discharge tubes 4a can be positioned relative to each other. Therefore, in this embodiment, an accurate operation of passing the discharge tubes 4a one by one through the many through holes corresponding to the cross-sectional shape of the discharge tube 4a is not required, and the assembly process can be facilitated.

  In the present embodiment, the outer edges of the outer annular bodies 15a and 115a are in close contact with the inner peripheral surface of the intermediate case 3, and the upstream and downstream sides in the intermediate case 3 are formed by the outer annular bodies 15a and 115a and the positioning pieces 15b and 115b. Since the gap between the sides is sealed, the sealing can provide a function as a sealing member to the support blocks 15 and 115 which are discharge tube support structures.

  In this embodiment, since the support block 15 is made of an insulator and fixed to the upstream and downstream ends of the discharge tube 4a, the support block 15 holds the internal electrode 5 together with the discharge tube 4a. And increase in the number of parts can be suppressed.

  In the present embodiment, the support block 115 is made of a conductor, and the outer peripheral electrode 4b is arranged on the outer periphery of the discharge tube 4a so that the support block 115 and the outer peripheral electrode 4b are electrically connected. The function as a conduction means between 4b can be provided, and the connection of the conductive wire 13 to the support block 115 can be made only in one place by this.

  In addition, this invention is not limited to the aspect as described in the said embodiment, A various deformation | transformation is possible. For example, in the above embodiment, the positioning pieces 15b and 115b are in contact with the three discharge tubes 4a, but four or more positioning pieces in the present invention are used, for example, the positioning piece 215b shown in FIG. The shape may be in contact with the discharge tube 4a, and the number of parts can be reduced by increasing the number of discharge tubes with which the positioning pieces are in contact. Moreover, in the said embodiment, although the discharge tube support structure which concerns on this invention was provided in three places, the discharge tube support structure which concerns on this invention may be only one place.

  In the above embodiment, the block-shaped support blocks 15 and 115 are used as the discharge tube support structure. However, the discharge tube support structure in the present invention is, for example, a press-molded product having a boss portion that can regulate the posture of the discharge tube. Such a thin plate member may be included.

  In the above embodiment, the discharge tube 4a and the outer peripheral electrode 4b are cylindrical, but the discharge tube and the outer peripheral electrode in the present invention may have other shapes such as a rectangular tube. In the present invention, a catalyst substance may be supported on the outer peripheral electrode or the inner electrode. Furthermore, in the present invention, a honeycomb structure such as ceramics is installed in a space surrounded by the outer peripheral electrode 4b, and the exhaust gas can be reformed by the action of electric power regardless of whether plasma is used or whether PM is filtered. Various configurations can be used, and all belong to the category of the present invention. Needless to say, the present invention can be applied to internal combustion engines other than vehicles.

It is a vertical side view which shows the exhaust gas purification apparatus which concerns on embodiment of this invention. It is a front view which shows an intermediate | middle case and an insulating support block. It is a front view which shows an electrode support block. It is a perspective view which shows an electroconductive support block and its assembly method. It is a front view which shows the modification of an insulating support block.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exhaust gas purification apparatus 2a Upstream side case 2b Downstream side case 3 Intermediate case 4a Discharge tube 4b Outer electrode 5 Internal electrode 6 Processing unit 8, 18 Electrode support frame 10 Feed line 15,115,215 Support block 15a, 115a Outer annular body 15b 115b Positioning piece

Claims (4)

A discharge tube support structure that integrally supports a plurality of parallel discharge tubes of an exhaust gas purification device,
An outer annular body through which the plurality of discharge tubes pass;
A positioning piece for positioning the plurality of discharge tubes with respect to each other;
A discharge tube support structure for an exhaust gas purifying apparatus. A discharge tube support structure for an exhaust gas purifying apparatus according to claim 1,
While the outer edge of the outer annular body is in close contact with the inner peripheral surface of the container of the exhaust gas purification device,
A discharge tube support structure characterized in that a space between an upstream side and a downstream side in the container is sealed by the outer annular body and the positioning piece. The exhaust gas purifying apparatus according to claim 1 or 2,
A discharge tube support structure, wherein the outer annular body and the positioning piece are made of an insulator. The exhaust gas purifying apparatus according to claim 1 or 2,
A discharge tube support structure, wherein the outer annular body and the positioning piece are made of a conductor.

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