JP3867513B2 - Catalytic converter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a catalytic converter for exhaust purification of an internal combustion engine, and more particularly to a technique for protecting a catalyst carrier from foreign matters such as welding spatter.
[0002]
[Prior art]
Generally, a catalytic converter for purifying exhaust gas of an internal combustion engine has a carrier holding mat wound around the outer periphery of a catalyst carrier carrying a catalyst, and a case constituting a part of an exhaust passage through the carrier holding mat. Stored.
[0003]
[Problems to be solved by the invention]
However, in such a conventional catalytic converter, welding spatter when the exhaust manifold is formed by pipe welding or the like at the manufacturing stage, residual casting sand in the case of casting, machining chips, and use of an internal combustion engine When foreign matter such as metal oxides generated in the process reaches the catalyst carrier, it cannot pass through the catalyst carrier and stays on the upstream end surface, and the foreign matter such as welding spatter moves around to deform the shape of the end surface of the catalyst carrier. It turns out that there is a problem that it ends up.
[0004]
Such problems have become prominent in ceramic monolithic catalyst carriers in recent years due to the reduction in the strength of the catalyst carrier due to a reduction in the honeycomb structure's thin walls and high cell density in order to improve exhaust purification performance. Is.
Therefore, the present inventors considered trapping with a carrier holding mat so that foreign matters such as welding spatter do not move around on the end face of the catalyst carrier. Here, Japanese Patent Laid-Open No. 2000-240440 discloses a natural length before winding of the carrier holding mat in order to prevent exhaust escape (bypass) at the mating portions at both ends in the winding direction of the carrier holding mat. In the flat plate state, a large groove is formed near both ends in the winding direction, and a large notch is formed near the center in the winding direction. It is disclosed that the shape portions are fitted together and are brought into close contact with a restoring force. Thereby, in the winding state, a large rectangular groove and a large V-shaped groove are formed on the upstream end face of the carrier holding mat.
[0005]
However, with such a carrier holding mat, the grooves are too large and deep,
(1) The original holding power is reduced and the catalyst carrier cannot be securely held. (2) Since there is a place where the width of the mat becomes extremely narrow, exhaust is likely to escape from there. (3) Strength of the mat (4) Even if spatter or the like enters the groove, the groove is large, so that the shape of the groove cannot be maintained. Sputtering moves and damages the mat. (5) Depending on the degree of fitting and extension, the size of the final groove changes and the gap may become zero.
[0006]
In the first place, the above publication does not disclose a catalytic converter disposed in the vertical direction or obliquely with respect to the vertical direction, or a catalytic converter disposed in the vicinity immediately below the exhaust manifold. Traps such as sputtering cannot be effectively performed.
The present invention provides a catalytic converter capable of reliably trapping foreign matters such as welding spatters so as not to move around on the end face of the catalyst carrier by devising the carrier holding mat in view of such a situation. The purpose is to do.
[0007]
[Means for Solving the Problems]
For this reason, according to the first aspect of the present invention, there is provided a catalytic converter for purifying exhaust gas in which a catalyst carrier is housed in a case constituting a part of an exhaust passage of an internal combustion engine via a carrier holding mat wound around the outer periphery thereof. A recess for trapping foreign matter is provided on the upstream end surface of the carrier holding mat in the exhaust flow direction, and the remaining width of the carrier holding mat in the portion where the recess is provided is at both end portions in the winding direction of the carrier holding mat. The depth of the dent is set so as to be longer than the width of the convex portion of the fitting portion due to the unevenness.
[0008]
In the invention of claim 4 (2) , in the catalytic converter for purifying exhaust gas, the catalyst carrier is housed in a case constituting a part of the exhaust passage of the internal combustion engine via a carrier holding mat wound around the outer periphery thereof. , Existing on the end face upstream of the carrier holding mat in the exhaust flow direction, from a flat state of a natural length prior to winding of the carrier holding mat, other than the fitting portions at both ends in the winding direction of the carrier holding mat A recess for foreign matter trapping, and the fitting portion by the irregularities at both ends in the winding direction of the carrier holding mat has a convex portion protruding from one end portion in the winding direction and the other end portion It is characterized by comprising a concave portion formed corresponding to the convex portion .
[0009]
In the invention of claim 5 (3) , in the catalytic converter for purifying exhaust gas, the catalyst carrier is housed in a case constituting a part of the exhaust passage of the internal combustion engine via a carrier holding mat wound around the outer periphery thereof. The catalyst carrier is arranged in the vertical direction or obliquely with respect to the vertical direction, and the end surface on the upstream side in the exhaust flow direction of the carrier holding mat is arranged in the exhaust flow direction from the end surface on the upstream side in the exhaust flow direction of the catalyst carrier. It is located on the downstream side, and a recess for foreign matter trap is provided on the upstream end surface of the carrier holding mat in the exhaust flow direction.
[0010]
In the invention of claim 6, wherein the catalyst support is characterized by being disposed close to directly below the exhaust manifold.
[0011]
In the invention of claim 7, the recess is a groove, and in the invention of claim 8 , the groove is V-shaped.
The invention according to claim 9 is characterized in that a plurality of the recesses are provided so as to be arranged at substantially equal intervals in the circumferential direction in a state where the carrier holding mat is wound around the catalyst carrier.
The invention of claim 10 is characterized in that the recess is provided also on an end face of the carrier holding mat on the downstream side in the exhaust flow direction.
[0012]
According to an eleventh aspect of the present invention, the catalyst carrier is a ceramic monolithic catalyst carrier, and the twelfth aspect of the invention is characterized by a thin-walled honeycomb structure having a wall thickness of 0.1 mm or less.
[0013]
In the invention of claim 13 , the exhaust manifold is formed by pipe welding, and in the invention of claim 14 , the case of the catalytic converter is integrally welded with the exhaust manifold formed by pipe welding. To do.
[0014]
【The invention's effect】
According to the first to fifth aspects of the present invention, when foreign matter such as welding spatter reaches the catalyst carrier, it moves into the recess on the surrounding end surface of the carrier holding mat and is trapped thereby. Accordingly, it is possible to reliably prevent damage to the catalyst carrier due to foreign matters such as welding spatter moving around the end surface of the catalyst carrier.
[0015]
In particular, in the case of the invention of claim 1, the remaining width W1 of the carrier holding mat in the portion provided with the recess is longer than the width W2 of the convex portion of the fitting portion due to the irregularities at both ends in the winding direction of the carrier holding mat. Thus, since the depth of the dent is set , that is, even if the dent is provided, the portion (W1) is less likely to cause the exhaust gas to escape than the portion (W2) where the exhaust gas is most likely to escape. Therefore, it is possible to achieve a sufficient holding function and prevention of exhaust escape.
[0016]
In particular, in the case of the invention of claim 4 (2), since no excessive force is applied to the carrier holding mat in the wound state, a sufficient holding function can be maintained and the shape is not changed. There is no variation.
[0017]
In particular, in the case of the invention of claim 5 (3) , the catalyst carrier is disposed in the vertical direction or obliquely with respect to the vertical direction. Can be trapped in.
Further, by positioning the upstream end surface of the carrier holding mat downstream from the upstream end surface of the catalyst carrier, the upstream end surface of the carrier holding mat is annular with respect to the upstream end surface of the catalyst carrier. Since it forms a groove, if foreign matter such as welding spatter moves on the end face of the carrier holding mat, this part will become an annular groove, so it will not return to the end face of the catalyst carrier again. Since trapped in the dent, trapping efficiency can be further improved.
According to the sixth aspect of the invention, since the catalyst carrier is disposed in the vicinity immediately below the exhaust manifold, foreign matters such as welding spatter from the exhaust manifold can be reliably trapped.
[0018]
According to the invention of claim 7 , since the recess is a groove, it can be easily manufactured. Further, according to the invention of claim 8 , the groove is V-shaped, If a foreign object enters the dent, it becomes narrower as it enters the back, so that the movement can be confined, and slipping out and damage to the mat can be prevented.
According to the ninth aspect of the present invention, a plurality of the recesses are provided so as to be arranged at substantially equal intervals in the circumferential direction in the wound state of the carrier holding mat, so that the trap efficiency can be further improved, and the mat It is also possible to prevent a change in trap efficiency due to the winding position.
[0019]
According to the invention of claim 10 , by providing the recess also on the end face on the downstream side in the exhaust flow direction of the carrier holding mat, it is not necessary to consider the direction when the mat is wound, and the winding work is facilitated.
[0020]
According to the invention of claim 11, the strength is further reduced by applying to a ceramic monolith catalyst carrier, and further according to the invention of claim 12 by applying to a thin wall honeycomb structure. The effect of the present invention becomes more remarkable.
According to the invention of claim 13, by applying to an exhaust manifold formed by a pipe welding, since they are more welding spatters is likely to occur, the effect of the present invention becomes more remarkable, yet the invention of claim 14 According to the present invention, it is difficult to disassemble the catalytic converter and remove the welding spatter by applying it to an exhaust manifold formed by pipe welding and integrated with the catalytic converter. It becomes even more prominent.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows an embodiment of the present invention, in the vertical direction as shown in FIG. 1 (a), or in the same figure (b) immediately below a collecting portion of an exhaust manifold 2 connected and fixed to a cylinder head 1 of an engine. ), The catalytic converter 3 is provided obliquely with respect to the vertical direction, and an exhaust pipe (front tube) 4 is connected and fixed to the outlet side of the catalytic converter 3.
[0022]
In the example of FIG. 1, the case of the catalytic converter 3 is fixed by welding integrally with the exhaust manifold 2 formed by pipe welding, but the case of the catalytic converter 3 is formed separately from the exhaust manifold 2, You may make it bolt a mutual flange part.
The case of the catalytic converter 3 constitutes a part of the exhaust passage, and includes a cylindrical main case 10 and substantially conical diffusers 11 and 12 connected to the inlet side and the outlet side thereof by welding, respectively. .
[0023]
A catalyst carrier 13 is accommodated in the main case 10 via a carrier holding mat 14 wound around the outer periphery thereof. Reference numeral 15 denotes a locking washer member.
The catalyst carrier 13 is a ceramic monolithic catalyst carrier having a honeycomb structure having a cylindrical outer shape. In particular, the honeycomb-shaped partition walls are thin walls, for example, a wall thickness of 0.1 mm or less, preferably 2 mils (= 0.064 mm), This is intended to increase the cell density. This is a remarkably thin wall as compared with a carrier having a wall thickness of 8 mil (= 0.220 mm) or 4 mil (= 0.110 mm) generally used in the past. The support surface is coated with a catalyst.
[0024]
The carrier holding mat 14 is a non-expandable interlam mat made of, for example, ceramic fiber, alumina fiber, vermiculite, or the like, and is wound around the outer periphery of the catalyst carrier 13 as shown in FIG. Further, as shown in a development view of the carrier holding mat 14 in FIG. 3, a length L corresponding to the outer peripheral length when the catalyst carrier 13 is wound and a width W corresponding to the exhaust flow direction length of the catalyst carrier 13. And have.
[0025]
However, in the state where the carrier holding mat 14 is wound around the outer periphery of the catalyst carrier 13, the upstream end surface of the catalyst carrier 13 and the upstream end surface of the carrier holding mat 14 are not flush with each other, as shown in FIG. In addition, it is desirable that the carrier holding mat 14 is lower so that an annular groove is formed around the catalyst carrier 13.
Further, of the both ends of the carrier holding mat 14 in the winding direction, a rectangular convex portion 16a is formed at one end portion at the width central portion in the exhaust flow direction, and the convex portion is formed at the other end portion. A rectangular recess 16b is formed at a position corresponding to 16a.
[0026]
Accordingly, as shown in FIG. 2, when the carrier holding mat 14 is wound around the outer periphery of the catalyst carrier 13, the convex portions 16a and the concave portions 16b at both ends are fitted to each other, thereby exhausting from the mating portions at both ends. Is prevented from coming off.
Here, a V-shaped concave groove 17 is formed on the end face of the carrier holding mat 14 on the upstream side in the exhaust flow direction as a concave for trapping foreign matter. FIG. 4 shows a detailed view of the concave groove 17.
[0027]
The number of the concave grooves 17 may be one, but here, in order to increase trapping efficiency, two grooves are formed so as to have an interval of 180 ° in the winding state. Of course, as shown in FIG. 5, a larger number may be formed at equal intervals.
As shown in FIG. 4, the V-shaped groove 17 has a depth d of about 10 to 20 mm and an opening size s of about 8 to 20 mm. In addition, a round R is attached to the intersection of the V-shape so that the mat is not avoided, but this R is preferably 2 mm or less so that trapped welding spatter and the like can be contained.
[0028]
In this case, referring to FIG. 3, at least the remaining width W1 (= Wd) in the exhaust flow direction of the carrier holding mat 14 in the portion where the V-shaped concave groove 17 is formed is the convex portion of the fitting portion. The depth d of the V-shaped groove 17 is set to be larger than the width W2 of the exhaust flow direction of 16a. Here, W2 is the width in the exhaust flow direction of the portion where exhaust exhaust is most likely to occur, and is larger than the width W2 in the exhaust flow direction, and the remainder of the carrier holding mat 14 in the portion where the V-shaped concave groove 17 is formed. By securing the width W1 in the exhaust flow direction of the exhaust gas, even if the V-shaped concave groove 17 is formed, the escape of exhaust gas is not promoted or the holding force is not reduced.
[0029]
As shown in FIG. 6 (a), if the groove 17 is provided on the downstream end face in addition to the upstream end face in the exhaust flow direction in the deployed state, the upstream and downstream directions are considered when winding. There is no need, and the assembly work becomes easy. In this case as well, although W1> W2, the width W1 of the portion of the carrier holding mat 14 where the V-shaped concave groove 17 is formed in the remaining exhaust flow direction is W1 = W−2 × d.
[0030]
Further, as shown in FIG. 6B, even if the concave grooves 17 are formed on the upstream side and the downstream side, if the positions of the concave grooves 17 on the upstream side and the downstream side are shifted, W1 = W−d. Become.
In addition, as shown in FIG. 6C, when the concave and convex portions 16a and 16b of the fitting portion are formed, W2 in the figure is a reference.
According to the above configuration, welding spatter when the exhaust manifold 2 is formed by pipe welding or the like at the manufacturing stage, residual cast sand in the case of casting, cutting chips, and metal oxidation generated during the operation of the internal combustion engine Even if a foreign object such as an object falls due to vibration or thermal fatigue and reaches the catalyst carrier 13 of the catalytic converter 3, if it falls on the end surface of the carrier holding mat 14, the V-shaped Once inside the concave groove 17, it is trapped, and once inside the concave groove 17, it is V-shaped and tapered, so that it does not jump out and is trapped reliably.
[0031]
Therefore, foreign matter such as welding spatter can be reliably trapped and damage to the catalyst carrier 13 can be prevented without causing a reduction in holding force of the carrier holding mat 14 or exhaust exhaust.
In addition, when the catalytic converter is placed obliquely with respect to the vertical direction, if the concave groove is arranged near the position that becomes the lowest point in the vertical direction on the upstream end face of the carrier holding mat, Can be trapped reliably.
[0032]
Further, when the thickness of the carrier holding mat is sufficient, a conical conical hole may be provided instead of the V-shaped groove as a foreign substance trap recess.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a catalytic converter showing an embodiment of the present invention. FIG. 2 is a perspective view of a catalyst carrier in which a carrier holding mat is wound. FIG. 3 is a developed view of the carrier holding mat. FIG. 5 is a perspective view showing another embodiment. FIG. 6 is a development view showing another embodiment.
DESCRIPTION OF SYMBOLS 1 Engine cylinder head 2 Exhaust manifold 3 Catalytic converter 4 Exhaust pipe 10 Main cases 11, 12 Diffuser 13 Catalyst carrier 14 Carrier holding mat 15 Locking washer members 16a, 16b Convex portion and concave portion 17 V-shaped Ditch

Claims (14)

In an exhaust purification catalytic converter in which a catalyst carrier is housed in a case constituting a part of an exhaust passage of an internal combustion engine via a carrier holding mat wound around the outer periphery thereof,
Provide a trap for foreign matter trapping on the upstream end face of the carrier holding mat in the exhaust flow direction,
The depth of the dent is set so that the remaining width of the carrier holding mat in the portion provided with the dent is longer than the width of the convex portion of the fitting portion due to the irregularities at both ends in the winding direction of the carrier holding mat. A catalytic converter characterized by that. The dent for trapping foreign matter is formed on the end surface upstream of the carrier holding mat in the exhaust flow direction, except for the fitting portions formed by the irregularities at both ends in the winding direction of the carrier holding mat. It exists from the flat state of natural length,
The mating portion by the irregularities at both ends in the winding direction of the carrier holding mat includes a convex portion protruding from one end portion in the winding direction, and a concave portion formed corresponding to the convex portion at the other end portion. The catalytic converter according to claim 1, comprising: The catalyst carrier is arranged in a vertical direction or oblique to the vertical direction,
The end face on the upstream side in the exhaust flow direction of the carrier holding mat is located on the downstream side in the exhaust flow direction from the end face on the upstream side in the exhaust flow direction of the catalyst carrier. Catalytic converter. In an exhaust purification catalytic converter in which a catalyst carrier is housed in a case constituting a part of an exhaust passage of an internal combustion engine via a carrier holding mat wound around the outer periphery thereof,
Existing from the flat plate state of the natural length before winding of the carrier holding mat, on the upstream end surface of the carrier holding mat in the exhaust flow direction, except for the fitting portions by the irregularities at both ends in the winding direction of the carrier holding mat. , Provide a trap for foreign material traps ,
The fitting portion by the unevenness at both ends in the winding direction of the carrier holding mat includes a convex portion protruding from one end portion in the winding direction, and a concave portion formed corresponding to the convex portion at the other end portion. catalytic converter, characterized in that consisted. In an exhaust purification catalytic converter in which a catalyst carrier is housed in a case constituting a part of an exhaust passage of an internal combustion engine via a carrier holding mat wound around the outer periphery thereof,
The catalyst carrier is arranged vertically or obliquely with respect to the vertical direction,
The end surface on the upstream side in the exhaust flow direction of the carrier holding mat is located on the downstream side in the exhaust flow direction from the end surface on the upstream side in the exhaust flow direction of the catalyst carrier,
A catalytic converter characterized in that a recess for trapping foreign matter is provided on an end face on the upstream side in the exhaust flow direction of the carrier holding mat. The catalytic converter according to any one of claims 1 to 5, wherein the catalyst carrier is disposed in close proximity to an exhaust manifold. The catalytic converter according to any one of claims 1 to 6 , wherein the recess is a recess groove. The catalytic converter according to claim 7 , wherein the concave groove is V-shaped. Said recess, the carrier supporting mat in a state wound on the catalyst carrier, so as to be arranged at substantially equal intervals in the circumferential direction, any one of claims 1 to 8, characterized in that plurality The catalytic converter described. The catalytic converter according to any one of claims 1 to 9 , wherein the recess is also provided on an end surface of the carrier holding mat on the downstream side in the exhaust flow direction. The catalytic converter according to any one of claims 1 to 10 , wherein the catalyst carrier is a ceramic monolith catalyst carrier. 12. The catalytic converter according to claim 11 , wherein the catalyst carrier has a thin-walled honeycomb structure with a wall thickness of 0.1 mm or less. The catalytic converter according to any one of claims 1 to 12 , wherein the exhaust manifold is formed by pipe welding. The catalytic converter according to claim 13 , wherein the case of the catalytic converter is welded integrally with an exhaust manifold formed by pipe welding.

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