JP2008309072A - Exhaust emission control device for internal combustion engine and retaining member for exhaust emission control element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique capable of improving efficiency of assembling work of an exhaust emission control device for an internal combustion engine. <P>SOLUTION: The exhaust emission control device 1 is formed by winding a retaining mat 5 made of ceramic fiber sheet around a side face of a filter 3 serving as an exhaust emission control element and in this state, press-fitting the filter 3 into a hollow part 7a of a case 7. The end part on the press-fitted side of the retaining mat 5 is hardened by sintering. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust gas purification device for an internal combustion engine that purifies exhaust gas from the internal combustion engine, and a holding member that holds an exhaust gas purification element in the exhaust gas purification device.

  The exhaust gas of the internal combustion engine contains particulate matter (PM) containing carbon as a main component. A technique for providing a particulate filter (hereinafter referred to as “filter”) for collecting particulate matter in an exhaust system of an internal combustion engine is known in order to prevent such particulate matter from being released into the atmosphere.

Further, the exhaust gas from the internal combustion engine contains harmful substances such as NOx. In order to reduce the emission of these harmful substances, it is known to provide a NOx catalyst for purifying NOx in the exhaust gas in the exhaust system of the internal combustion engine. As described above, exhaust purification devices such as filters and NOx catalysts are generally provided in the exhaust passage of the internal combustion engine.

Here, the conventional exhaust purification apparatus is formed by housing exhaust purification elements such as an oxidation catalyst, a NOx catalyst and a filter in a case. In addition, the conventional exhaust purification device includes an oxidation catalyst, NOx
It is manufactured by winding a holding member such as a non-inflatable mat or an expansion mat around the outer periphery of an exhaust purification element such as a catalyst or a filter, and press-fitting the exhaust purification element around which the holding member is wound from one of the openings of the case.

  In this connection, for example, when the exhaust purification device includes two or more exhaust purification elements such as an oxidation catalyst and a filter, the filter is provided between the outer periphery of the filter and the inner periphery of the case. Has been proposed that regulates the movement of the oxidation catalyst in the axial direction by a stopper portion provided on the inner periphery of the case and a filter held in the case. (See Patent Document 1).

  In addition, in order to synergistically use the characteristics of the respective exhaust purification elements, a technique for combining exhaust purification elements having different characteristics on the inner peripheral side and the outer peripheral side in the exhaust purification device has been proposed. A technique is known in which the outer peripheral cell is made of a material having a higher thermal conductivity than that of the inner peripheral cell (see Patent Document 2). Even in such a case, it is conceivable that a holding member is wound around the exhaust purification element on the inner peripheral side and press-fitted into the exhaust purification element on the outer peripheral side.

However, the conventional holding member is often formed of a ceramic fiber or the like formed into a sheet shape, and has a large thickness and is often crushed in the thickness direction during press-fitting. For this reason, when the holding member is wound around the outer periphery of the exhaust purification element and then press-fitted into the case or the exhaust purification element on the outer peripheral side, the press-fit cannot be performed smoothly, and workability may be deteriorated.
JP 2005-98168 A JP 2006-07100 A

  An object of the present invention is to provide a technique capable of improving the workability of assembling work of an exhaust purification device for an internal combustion engine.

  In order to achieve the above object, the present invention provides an exhaust purification apparatus formed by inserting an exhaust purification element into an insertion hole of a support member in a state where the exhaust purification element is covered with a holding member. The greatest feature is that a curing treatment is performed.

More specifically, an exhaust purification device for an internal combustion engine that is provided in an exhaust passage of the internal combustion engine and purifies exhaust gas that passes through the exhaust passage,
A columnar exhaust purification element for removing the purification substance in the exhaust gas flowing from the end face from the exhaust;
A holding member provided to cover a side surface of the exhaust purification element and holding the exhaust purification element;
The exhaust purification element has an insertion hole inserted in an axial direction, and the exhaust purification element and the holding member are supported by being inserted into the insertion hole while being held by the holding member. A supporting member to be
With
An end portion of the holding member on the side inserted into the insertion hole of the support member is subjected to a hardening process for increasing hardness.

  Here, the holding member is flexible enough to cover at least the side surface of the exhaust purification element and is generally formed of a material having a low hardness (soft). Then, when the exhaust purification element is inserted into the insertion hole of the support member while being held by the holding member, the distal end portion of the holding member may be deformed and turned, which may make it difficult to insert. .

  On the other hand, in the present invention, the end of the holding member on the side inserted into the insertion hole of the support member is subjected to a curing treatment, so that at least deformation of the portion can be suppressed, The insertion operation of the exhaust purification element can be facilitated.

  In the present invention, the holding member is made of a ceramic fiber formed into a sheet shape, and the hardening treatment is performed by sintering an end portion of the ceramic fiber formed into the sheet shape. You may do it.

  When the holding member is made of a ceramic fiber formed into a sheet like this, the end of the holding member is sintered, and at least a part of the ceramic fiber at the end is baked and hardened to increase the hardness. It is possible to raise. According to this, it becomes possible to perform a hardening process more reliably by simpler operation | work.

  In the present invention, the end of the holding member on the side inserted into the insertion hole of the support member has an outer diameter in a state where the exhaust purification element is covered by the holding member. A taper process may be applied so that the taper becomes smaller toward the side inserted into the insertion hole.

  That is, when the exhaust purification element is inserted into the support member while being covered with the holding member, the end of the holding member is arranged so that the entire outer diameter of the exhaust purification element covered with the holding member becomes smaller toward the distal end side. The part is formed in a tapered shape. According to this, the workability of the insertion work when inserting the exhaust purification element into the support member in a state where the exhaust purification element is covered with the holding member can be further improved.

  In the present invention, the exhaust purification element may carry an exhaust purification catalyst, and the holding member may carry the same catalyst as the exhaust purification catalyst carried by the exhaust purification element. Then, the holding member can be used for exhaust gas purification together with the exhaust gas purification element, and the exhaust gas purification efficiency of the exhaust gas purification device as a whole can be increased.

The present invention also relates to an exhaust gas purification device for an internal combustion engine in which a columnar exhaust gas purification element that removes a purification substance in exhaust gas from the exhaust gas is inserted into an insertion hole of a support member in the axial direction. Is a sheet-like holding member wound around the side surface of the exhaust purification element when inserted into the insertion hole of the support member,
Formed by ceramic fibers,
At least a part of the ceramic fiber is hardened by a sintering process at an end on the side facing the insertion hole when wound around the exhaust purification element and inserted into the insertion hole of the support member. It is good also as a holding member of the exhaust gas purification element.

  Further, at that time, the thickness in the vicinity of the end portion is such that the outer diameter in a state of being wound around the side surface of the exhaust purification element becomes smaller toward the end of the support member inserted into the insertion hole. May be changed to a tapered shape.

  The means for solving the problems in the present invention can be used in combination as much as possible.

  In the present invention, it is possible to improve the workability of the assembly work of the exhaust gas purification device for the internal combustion engine.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings.

  FIG. 1 is an example of an exploded perspective view of a conventional exhaust purification device 1. As shown in FIG. 1, the exhaust purification device 1 conventionally includes a filter 3 as an exhaust purification element, a holding mat 5 as a holding member, and a case 7 as a support member.

  Here, the filter 3 is an element that is made of a wall flow type ceramic substrate and reduces harmful substances contained in the exhaust gas by collecting particulate matter contained in the exhaust gas from the internal combustion engine. And in this filter 3, since the back pressure in the exhaust passage may become excessively high if the amount of the collected particulate matter exceeds a predetermined value, the PM regeneration process is periodically performed and collected. The particulate matter is removed by oxidation. As shown in the figure, the filter 3 has a substantially cylindrical shape composed of a plurality of sealed cells 3a. The diameter is set smaller than the diameter of the hollow portion 7 a of the case 7.

  Next, the holding mat 5 as a holding member is formed of ceramic fibers and has a flat plate shape in the initial state. The holding mat 5 is wound around the filter 3 to form a hollow cylinder. Further, the thickness of the holding mat 5 is set to be slightly larger than half the difference between the diameter of the hollow portion 7 a of the case 7 and the diameter of the filter 3. This is because when the filter 3 is stored in the hollow portion 7 a of the case 7, the holding mat 5 wound around the filter 3 is deformed, that is, crushed, and holds the filter 3 in the hollow portion 7 a of the case 7. Because. The length of the holding mat 5 in the direction perpendicular to the axial direction of the filter 3 is set to be the same as or slightly shorter than the length of the outer periphery of the filter 3.

When assembling the exhaust gas purification device 1, the filter 3 having the holding mat 5 wound around the outer periphery thereof is press-fitted into the case 7, that is, into the hollow portion 7a using a press-fitting jig (not shown). The press-fitting of the filter 3 into the case 7 is at least one side surface of the filter 3 (FIG. 1).
Then, the process is repeated until the left side abuts against a stopper (not shown) in the case 7. As a result, the filter 3 housed in the hollow portion 7 a of the case 7 is securely held by the holding mat 5 that is a holding member provided in a deformed state between the filter 3 and the case 7. That is, the filter 3 is restricted from moving in the axial direction or the rotational direction with respect to the case 7.

  Here, as described above, the outer diameter in a state where the holding mat 5 is wound around the filter 3 (hereinafter, this state is referred to as a filter unit 6) is larger than the diameter of the hollow portion 7a of the case 7. It has become. Accordingly, when the filter unit 6 is press-fitted into the case 7, the tip of the holding mat 5 interferes with the outer peripheral portion 7 b of the opening of the case 7. Then, since the holding mat 5 itself is formed of flexible ceramic fibers, the ceramic fibers may be frayed, broken or turned up. As a result, since it is necessary to press-fit the filter unit 6 into the case 7 while suppressing fraying, breakage, and turning of the ceramic fiber, the workability of the press-fit operation may be reduced.

  Therefore, in this embodiment, the end of the holding mat 5 that is press-fitted into the case 7 (hereinafter referred to simply as the press-fitting side) is preliminarily sintered to burn at least part of the ceramic fibers. By hardening, the end of the holding mat 5 on the press-fitting side was cured. In FIG. 2, the part which sinters the holding mat 5 in this embodiment is shown by hatching.

  According to this, when press-fitting the filter unit 6 into the case 7, the end of the holding mat 5 on the press-fitting side is cured, so that fraying, breakage, turning, etc. of the ceramic fibers can be suppressed. .

  Further, when the holding mat 15 formed of ceramic fibers is sintered, the ceramic fibers in the portions are bonded to each other and are baked and hardened, so that the density of the portions of the holding mat 5 is increased and the thickness is increased. Tend to decrease. As a result, the outer diameter of the filter unit 6 is reduced only at the end portion on the press-fitting side that has been subjected to the sintering treatment, so that the press-fitting operation becomes easier.

  Further, since the confidentiality of the portion subjected to the sintering process in the holding mat 5 is increased, in the exhaust purification device 1 after assembly, the exhaust gas does not pass through the filter 3 but is not purified through the holding mat 5. It is possible to suppress the release to the outside.

  This sintering process may be performed before or after the holding mat 5 is wound around the filter 3. That is, when the degree of baking and hardening by sintering is relatively low and the holding mat 5 can be deformed without causing cracks, the sintering treatment is performed before the holding mat 5 is wound around the filter 3. May be. Further, when the degree of calcination by sintering is relatively high and the flexibility of the sintered portion is lost, the sintering process may be performed after the holding mat 5 is wound around the filter 3.

  Further, when sintering is performed on the press-fitting side end of the holding mat 5, the outer diameter of the press-fitting side end of the filter unit 6 is not stable due to variations in the sintered state of the ceramic fibers. It is considered that the inconvenience occurs.

  Therefore, in the present embodiment, a taper application process for applying a taper surface to the end of the holding mat 5 on the press-fitting side may be performed.

Specifically, for example, press shaping may be performed such that the tip is tapered before or after the sintering process. When the press shaping is performed after the sintering process, the elasticity of the holding mat 5 is lowered by the sintering process, and therefore the taper shape can be favorably maintained by the press shaping. Further, the end shape of the holding mat 5 may be cut into a taper before or after the sintering process.

  FIG. 3 shows an example of a cross-sectional shape of the filter unit 6 when a taper is formed at the press-fitting side end portion of the holding mat 5 by the taper applying process.

  In the above-described embodiment, the example in which the press-fit side end portion of the holding mat 5 is cured by performing the sintering process has been described. However, the process for hardening the press-fit side end portion of the holding mat 5 is not limited thereto. I can't. For example, a heat-resistant resin or molten glass may be injected into the press-fitting side end of the holding mat 5, or the holding mat 5 may be cured only with a high-pressure press.

  In the above embodiment, the case where the holding mat 5 is made of ceramic fibers has been described. However, other materials such as metal fibers and glass fibers may be used. Even when the holding mat 5 is made of metal fibers or glass fibers, the metal mats or the glass fibers are melt-bonded to each other by applying heat treatment to the press-fitting side end of the holding mat 5. May be performed. Alternatively, the metal fiber may be oxidized to deprive its elasticity and as a result be cured.

In the above embodiment, the example in which the holding mat 5 is wound around the filter 3 as the exhaust purification element has been described. However, the exhaust purification element as an object to which the present invention is applied is not limited to the filter 3. Of course. For example, the present invention may be applied to an oxidation catalyst having oxidation ability on a straight flow type ceramic base material or an exhaust purification catalyst carrying a NOx purification catalyst. Furthermore, the present invention may be applied to a DPNR in which an NOx storage reduction catalyst is supported on a filter.

  When the present invention is applied to an exhaust purification element that supports a catalyst, the same catalyst may be supported on the holding mat 5. Then, the effective volume of the catalyst in the exhaust purification device can be increased, and the exhaust purification efficiency can be increased.

  In the above embodiment, the case where the filter unit 6 is press-fitted into the case 7 as a support member has been described. However, the support member to which the present invention is applied is a filter or an exhaust purification catalyst having characteristics different from those of the filter 3. It does not matter. In other words, the present invention may be applied when the filter 3 is press-fitted into another filter or an exhaust purification catalyst to form an exhaust purification device.

  Further, in the above-described embodiment, the example in which only the curing process or the curing process and the taper applying process are performed on the press-fitting side end portion of the holding mat 5 has been described. It is also possible to obtain the effect of improving the workability of the assembly operation of the exhaust gas purification device by applying it to the press-fitting side end portion of the mat 5.

  In the above embodiment, the thickness of the holding mat 5 is set to be slightly larger than half the difference between the diameter of the hollow portion 7 a of the case 7 and the diameter of the filter 3. The example which press-fits the unit 6 was demonstrated. On the other hand, the thickness of the holding mat 5 is set to be smaller than half the difference between the diameter of the hollow portion 7 a of the case 7 and the diameter of the filter 3, and press fitting is performed when the filter unit 6 is stored in the case 7. The present invention may be applied when it is not necessary to do so. Even in this case, it can be suppressed that the insertion side end portion of the holding mat 5 interferes with the outer peripheral portion 7b of the case 7 and the workability of the storing work is deteriorated.

It is a disassembled perspective view which shows schematic structure of the conventional exhaust gas purification apparatus. It is a disassembled perspective view of the exhaust gas purification apparatus for demonstrating the site | part which performs the sintering process of this invention. It is an example of sectional drawing of the press-fit side edge part of a filter unit after implementation of the taper provision process in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Exhaust gas purification device 3 ... Filter 5 ... Holding mat 6 ... Filter unit 7 ... Case

Claims (6)

An exhaust purification device for an internal combustion engine that is provided in an exhaust passage of the internal combustion engine and purifies exhaust that passes through the exhaust passage,
A columnar exhaust purification element for removing the purification substance in the exhaust gas flowing from the end face from the exhaust;
A holding member provided to cover a side surface of the exhaust purification element and holding the exhaust purification element;
The exhaust purification element has an insertion hole inserted in an axial direction, and the exhaust purification element and the holding member are supported by being inserted into the insertion hole while being held by the holding member. A supporting member to be
With
An exhaust gas purifying apparatus for an internal combustion engine, wherein an end portion of the holding member on the side inserted into the insertion hole of the support member is subjected to a hardening process for increasing hardness.   The holding member is made of a ceramic fiber formed into a sheet shape, and the hardening process is performed by sintering an end portion of the ceramic fiber formed into a sheet shape. 2. An exhaust emission control device for an internal combustion engine according to 1.   An outer diameter of the holding member in the state where the exhaust purification element is covered with the holding member is inserted into the insertion hole of the support member at the end of the holding member that is inserted into the insertion hole of the support member. 3. The exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein a taper process is performed so as to become smaller toward the side. The exhaust purification element carries an exhaust purification catalyst,
The exhaust purification device for an internal combustion engine according to any one of claims 1 to 3, wherein the holding member carries the same catalyst as the exhaust purification catalyst carried on the exhaust purification element. In an exhaust gas purification apparatus for an internal combustion engine in which a columnar exhaust gas purification element for removing a purification substance in exhaust gas from an exhaust gas is inserted into an insertion hole of a support member in an axial direction, the exhaust gas purification element is inserted into the support member. A sheet-like holding member wound around a side surface of the exhaust purification element when inserted into the hole,
Formed by ceramic fibers,
At least a part of the ceramic fiber is hardened by a sintering process at an end on the side facing the insertion hole when wound around the exhaust purification element and inserted into the insertion hole of the support member. An exhaust purification element holding member.   The thickness in the vicinity of the end portion changes in a taper shape so that the outer diameter in a state wound around the side surface of the exhaust purification element becomes smaller toward the end of the support member inserted into the insertion hole. The holding member for an exhaust purification element according to claim 5.

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