JP2003020939A - Catalytic converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent damage to a catalyst carrier 13 due to movement of foreign matters such as welding spatters on an end face of the catalyst carrier 13. SOLUTION: The end face on an exhaust flow direction upstream side of the catalyst carrier 13 is disposed to be inclined in the vertical direction. A recessed groove 17 for trapping foreign matters is provided in the vicinity of a position to be a lowest point in the vertical direction on the end face on the exhaust flow direction upstream side of a carrier holding mat 14 wound on the catalyst carrier 13. When at least a part of the recessed groove 17 is extended in a direction crossing the exhaust flow direction, popping of foreign matters can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalytic converter for purifying exhaust gas of an internal combustion engine, and more particularly to a technique for preventing damage to a catalyst carrier due to foreign matter such as welding spatter.

[0002]

2. Description of the Related Art In general, a catalytic converter for purifying exhaust gas of an internal combustion engine has a carrier holding mat wound around an outer periphery of a catalyst carrier carrying a catalyst, and a part of an exhaust passage is provided through the carrier holding mat. It is stored in the case that constitutes it.

[0003]

However, in such a conventional catalytic converter, the welding spatter when the exhaust manifold is formed by pipe welding or the like in the manufacturing stage, the residual sand in the case of casting, When chips and further foreign matter such as metal oxides generated during the operation of the internal combustion engine reach the catalyst carrier, they cannot pass through the catalyst carrier and remain on the upstream end face, and foreign matter such as welding spatter moves around. It has been found that there is a problem that the end surface shape of the catalyst carrier is deformed.

[0004] Such a problem is caused by the fact that, in recent years, in the ceramic monolith catalyst carrier, in order to improve the exhaust gas purification performance, the honeycomb structure has been made thin-walled and has a high cell density, and the strength of the catalyst carrier has decreased. It became remarkable. Therefore, the inventors of the present invention considered trapping foreign matter such as welding spatter with a carrier holding mat so as not to move around on the end surface of the catalyst carrier. Here, JP 2000
No. 240404 discloses that the carrier holding mat is wound in a flat plate state of natural length before winding in order to prevent exhaust gas bypass (bypass) at the joints of both ends in the winding direction of the carrier holding mat. Form large grooves near both ends in the direction,
In addition, a large notch is formed near the center in the winding direction, the mat is extended when winding, and the hook-shaped portion of the groove is fitted, and at the same time, the mat is made to adhere by restoring force. It is disclosed. Thus, in the wound state, a large rectangular groove and a large V-shaped groove are formed on the upstream end surface of the carrier holding mat.

However, if only the groove is provided on the upstream end surface of the carrier holding mat, even if foreign matter such as welding spatter gets on the upstream end surface of the catalyst carrier, it immediately moves to the upstream end surface of the carrier holding mat. There is no problem, by staying on the end surface of the catalyst carrier as it is and rolling on it,
This will cause damage to the catalyst carrier. In view of such an actual situation, the present invention provides a catalytic converter capable of reliably trapping foreign matter such as welding spatter so that the foreign matter remains on the end surface of the catalyst carrier and does not move thereover. With the goal.

[0006]

According to a first aspect of the present invention, exhaust gas is housed in a case forming a part of an exhaust passage of an internal combustion engine via a carrier holding mat having an outer periphery wound around the catalyst carrier. In a catalytic converter for purification, the catalyst carrier is mounted so that the end surface on the upstream side in the exhaust flow direction is not a surface perpendicular to the vertical direction, and a foreign matter trap is provided on the end surface on the upstream side in the exhaust flow direction of the carrier holding mat. It is characterized in that a concave groove for use is provided.

In this case, the invention of claim 2 is characterized in that the catalyst carrier is arranged obliquely with respect to the vertical direction together with the case. The invention according to claim 3 is characterized in that the end surface of the catalyst carrier on the upstream side in the exhaust flow direction is formed to be inclined with respect to the exhaust flow direction. In addition, claim 4
In the invention, the end face on the upstream side in the exhaust flow direction of the catalyst carrier is a convex face. Furthermore, the invention of claim 5 is characterized in that the concave groove is provided on the side that becomes lower in the inclination direction of the end face of the catalyst carrier on the upstream side in the exhaust flow direction.

According to a sixth aspect of the present invention, there is provided a catalytic converter for exhaust gas purification, wherein a catalyst carrier is housed in a case forming a part of an exhaust passage of an internal combustion engine through a carrier holding mat wound around the outer periphery of the case. A concave groove for trapping foreign matter is opened in an end surface of the carrier holding mat on the upstream side in the exhaust gas flow direction, and at least a part of the concave groove extends in a direction intersecting the exhaust gas flow direction. . In this case, the invention of claim 7 is characterized in that the concave groove has a bent portion midway in the extending direction.

Further, in the invention of claim 8, the end surface of the carrier holding mat on the upstream side in the exhaust flow direction is inclined in the circumferential direction, and the recessed groove is the end surface on the upstream side in the exhaust flow direction of the carrier holding mat. It is characterized in that it is provided in the vicinity of the lowest point in the vertical direction. Furthermore, in the invention of claim 9, from the end face on the upstream side in the exhaust flow direction of the catalyst carrier,
The end surface of the carrier holding mat on the upstream side in the exhaust flow direction is located on the downstream side in the exhaust flow direction.

Furthermore, the invention of claim 10 is characterized in that the recessed groove is formed in a fitting portion by unevenness at both end portions in the winding direction of the carrier holding mat. Furthermore, the invention of claim 11 is characterized in that at least the deepest portion of the concave groove is formed in a tapered shape.
According to a twelfth aspect of the invention, the groove is directly formed in the carrier holding mat.

According to a thirteenth aspect of the present invention, the concave groove is formed in advance on the inner surface of the case at a position facing the planned formation position of the concave groove to be formed on the carrier holding mat. The concave groove is formed at the planned formation position of the carrier holding mat by wind erosion due to engine operation. In the invention of claim 14, the recessed groove is an outer peripheral wall of the catalyst carrier, and a recessed part is formed in advance at a position facing a planned position of the recessed groove to be formed in the carrier holding mat. The concave groove is formed at the planned formation position of the carrier holding mat by wind erosion due to engine operation.

[0012]

According to the present invention, when foreign matter such as welding spatter reaches the catalyst carrier of the catalytic converter,
Since the end surface of the catalyst carrier is not a surface perpendicular to the vertical direction, it falls on the end surface of the carrier holding mat around it along the slope of this surface and quickly enters the concave groove provided here, so that To be trapped. Therefore, it is possible to reliably prevent damage to the catalyst carrier due to foreign matter such as welding spatter remaining on the end surface of the catalyst carrier and moving around.

According to the second aspect of the present invention, it suffices to dispose the catalytic converter at a slant, which is easy to implement. According to the third aspect of the invention, when the catalytic converter cannot be mounted in a tilted manner due to the vehicle layout, it can be dealt with only by changing the shape of the catalyst carrier by tilting the upstream end surface of the catalyst carrier.

According to the fourth aspect of the present invention, when the catalytic converter cannot be mounted in a tilted manner due to the vehicle layout, it can be dealt with only by changing the shape of the catalyst carrier such that the upstream end surface of the catalyst carrier is convex. No matter what angle the converter is mounted, foreign matter such as welding spatter can be promptly removed from the end surface of the catalyst carrier. According to the invention of claim 5, since the concave groove for trapping foreign matter is provided on the lower side in the inclination direction of the upstream end surface of the catalyst carrier, it moves on the carrier holding mat along the inclination of the end surface of the catalyst carrier. The foreign matter immediately enters the groove and is trapped.

According to the sixth aspect of the present invention, a groove for trapping foreign matter is opened in the upstream end surface of the carrier holding mat, and at least a part of the groove extends in a direction intersecting the exhaust flow direction. Therefore, once foreign matter such as welding spatter enters the groove, it is unlikely to be affected by vibration input in the exhaust flow direction and exhaust pulsation, and it becomes a physical obstacle that cannot be easily ejected. You can definitely trap.
Therefore, it is possible to reliably prevent damage to the catalyst carrier due to foreign matter such as welding spatter moving around on the end surface of the catalyst carrier.

According to the invention of claim 7, since the concave groove has a bent portion in the middle of its extending direction, this is sure against the protrusion of foreign matter such as welding spatter that once entered the concave groove. It becomes a physical obstacle. According to the invention of claim 8, since the upstream end surface of the carrier holding mat is inclined in the circumferential direction and the concave groove is located at the lowest portion, foreign matter such as welding spatter that has fallen onto the end surface of the carrier holding mat. Rapidly moves into the groove along this inclination, so that it easily enters the groove and is reliably trapped.

According to the ninth aspect of the present invention, by locating the upstream end surface of the carrier holding mat on the downstream side of the upstream end surface of the catalyst carrier, the end surface of the carrier holding mat is positioned with respect to the end surface of the catalyst carrier. Since it forms an annular groove, if foreign matter such as welding spatter moves on the end surface of the carrier holding mat, this portion will become an annular groove and will not return to the end surface of the catalyst carrier again. While moving around in the groove, it is trapped in the groove.

According to the tenth aspect of the present invention, the concave groove is formed in the fitting portion by the concavities and convexities at both ends in the winding direction of the carrier holding mat, so that the strength reduction of the carrier holding mat due to the formation of the concave groove is prevented. can do. According to the invention of claim 11, at least the deepest part of the concave groove is formed in a tapered shape, becomes narrower as it goes deeper, and the movement can be contained, and the pop-out can be prevented more reliably, and It can also prevent the mat from being damaged.

According to the twelfth aspect of the invention, by directly forming the concave groove on the carrier holding mat, it becomes easy to obtain a desired size, shape, etc. of the concave groove. According to the thirteenth aspect of the present invention, a concave portion is formed in advance on the inner surface of the case at a position facing the planned formation position of the concave groove to be formed in the carrier holding mat, and the surface pressure of the carrier holding mat at this portion is adjusted. By lowering and operating the engine, the mat material is scattered at this portion, thereby forming a concave groove in the carrier holding mat by wind erosion. Therefore, when directly forming the concave groove on the carrier holding mat, when assembling the carrier holding mat with the concave groove,
It is necessary to manage the position when assembling so that the position of the concave groove will be the desired position, but by forming the concave part by positioning it in the case where the position management is easy, The groove can be formed, and the position management of the concave groove becomes easy.

According to the fourteenth aspect of the present invention, a concave portion is formed in advance on the outer peripheral wall of the catalyst carrier at a position facing the planned formation position of the concave groove to be formed on the carrier holding mat, and the carrier holding portion of this portion is held. The surface pressure of the mat is reduced, and the mat material in this portion is scattered by the operation of the engine, so that a concave groove is formed in the carrier holding mat by wind erosion. Therefore, when the concave groove is directly formed on the carrier holding mat, when the carrier holding mat with the concave groove is assembled, it is necessary to manage the position of the concave groove so that the position of the concave groove becomes a desired position. On the other hand, by locating and forming the concave portion on the catalyst carrier whose position is relatively easy to manage, the concave groove can be formed at that position, and the position management of the concave groove becomes relatively easy.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of a catalytic converter mounted in an engine exhaust system, and FIG. 2 is a view of the case of the catalytic converter as seen in half from the left side of FIG.

A catalytic converter 3 is provided obliquely below the vertical direction immediately below a collecting portion of an exhaust manifold 2 which is connected and fixed to a cylinder head 1 of an engine, and an exhaust pipe (front tube) is provided on an outlet side of the catalytic converter 3. ) 4 is connected and fixed. 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. However, the case of the catalytic converter 3 is formed separately from the exhaust manifold 2, The flange portions may be bolted together.

Case (container) of catalytic converter 3
Is a part of the exhaust passage, and is composed of a cylindrical main case 10 and diffuser parts 11 and 12 of substantially conical shape, which are connected to the inlet side and the outlet side thereof by welding, respectively. Then, the catalyst carrier 13 is housed in the main case 10 via a carrier holding mat 14 wound around the outer periphery thereof. Reference numeral 15 is a locking washer member.

The catalyst carrier 13 is a ceramic monolithic catalyst carrier having a honeycomb structure having a cylindrical outer shape. Particularly, the honeycomb partition wall has a thin wall, for example, a wall thickness of 0.1 mm or less, preferably 2 mils (= 0.064 mm). In this way, the cell density is increased. This is a much thinner wall as compared with a carrier having a wall thickness of 8 mils (= 0.220 mm) or 4 mils (= 0.110 mm) which is generally used in the past. The surface of the carrier is coated with a catalyst.

The carrier holding mat 14 is a non-expandable interram mat made of, for example, ceramic fiber, alumina fiber or vermiculite, and is wound around the outer periphery of the catalyst carrier 13. Further, as shown in the development view of the carrier holding mat 14 in FIG.
It has a length L corresponding to the outer peripheral length when wound around 3, and a width W corresponding to the exhaust flow direction length of the catalyst carrier 13.

However, when 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, but the carrier holding mat The mat 14 is lowered so that an annular groove is formed around the catalyst carrier 13. Also,
Of the both ends of the carrier holding mat 14 in the direction corresponding to the outer peripheral length of the catalyst carrier 13, a rectangular convex portion 16a is formed at one end in the width center in the exhaust flow direction, and the other end is formed at the other end. , A rectangular concave portion 16b at a position corresponding to the convex portion 16a
Are formed.

Therefore, when the carrier holding mat 14 is wrapped 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, so that the exhaust gas is prevented from coming out from the joint portions at both ends. To prevent. put it here,
On the end surface of the carrier holding mat 14 on the upstream side in the exhaust flow direction,
A concave groove 17 for trapping a foreign substance is formed.

As shown in the developed view of FIG. 3, the concave groove 17 is formed separately from the fitting concaves and convexes at both ends, and also the dotted line portion K of FIG. 3 (one of the upstream side portion of the rectangular concave portion 16b). Part)
May be cut out in comparison with the downstream side portion, and as shown in FIG. 4, it may be formed on the upstream side in the exhaust flow direction of the fitting concave and convex portions at both ends. Further, in the development view of FIG. 3, as shown by a dotted line, the carrier holding mat 1
If a groove 17 ′ is also provided on the end surface of the No. 4 downstream side in the exhaust flow direction, it may be turned upside down when winding, and the workability at the time of winding is improved.

In the catalytic converter 3 placed obliquely with respect to the vertical direction, the groove 17 becomes lower in the direction of inclination of the upstream end face of the catalyst carrier 13, that is, on the upstream side of the carrier holding mat 14. It should be placed near the lowest point on the end face in the vertical direction. According to the above configuration, welding spatter such as when the exhaust manifold 2 is formed by pipe welding at the manufacturing stage, residual casting sand in the case of casting, swarf of machining, and further metal oxidation generated in the operating process of the internal combustion engine. When foreign matter such as an object falls due to vibration or thermal fatigue and reaches on the catalyst carrier 13 of the catalytic converter 3, the end surface of the catalyst carrier 13 is inclined with respect to the vertical direction. Surrounding carrier holding mat 14
Fall on the upstream end face. Therefore, foreign matter such as welding spatter does not remain on the end surface of the catalyst carrier 13,
It is possible to prevent the catalyst carrier 13 from moving around and being damaged.

Foreign matter such as welding spatter that has fallen onto the end surface of the carrier holding mat 14 enters the concave groove 17 because it has a concave groove 17 in the direction in which it falls, and even in a portion away from the concave groove 17. Even if it falls, since this portion forms an annular groove and is inclined, it reaches the concave groove 17 along the inclination of this annular groove and enters it. Therefore, foreign matter such as welding spatter can be reliably trapped in the groove 17.

If the concave groove 17 is formed in a concave shape, that is, in a V-shape, foreign matter such as welding spatter is more likely to enter and the movement is restricted as it goes deeper. It is possible to trap more reliably,
It is also possible to prevent the mat from being damaged by moving around in the groove 17. Next, a second embodiment of the present invention will be described with reference to FIGS. In the second and subsequent embodiments, elements corresponding to those in the first embodiment are given the same reference numerals to simplify the description.

The second embodiment is a case where the catalytic converter 3 is arranged vertically, and in this case, the end face of the catalyst carrier 13 on the upstream side in the exhaust flow direction is inclined with respect to the vertical direction, that is, It is formed so as to be inclined with respect to the exhaust flow direction so as not to be horizontal. The concave groove 17 of the carrier holding mat 13 is arranged on the side that becomes lower in the inclination direction of the upstream end surface of the catalyst carrier 13.

Even in this way, when foreign matter such as welding spatter falls due to vibration or thermal fatigue and reaches the catalyst carrier 13 of the catalytic converter 3, the end face of the catalyst carrier 13 is inclined, and therefore this inclination is caused. Along the edge of the carrier holding mat 14 on the upstream side end face thereof, and enters the groove 17.
To be trapped. Next, a third embodiment of the present invention will be described with reference to FIGS.

In the third embodiment, in addition to the structure of the second embodiment, the end surface of the carrier holding mat 14 on the upstream side in the exhaust flow direction is inclined in the circumferential direction, and is the lowest portion thereof, and the catalyst carrier 13 In the part that becomes lower in the direction of inclination of the end surface,
A groove 17 is formed. Carrier holding mat 1 in this case
A development view of No. 4 is shown in FIG. By doing so, when foreign matter such as welding spatter falls due to vibration or thermal fatigue and reaches the catalyst carrier 13 of the catalytic converter 3, the end surface of the catalyst carrier 13 is inclined, and therefore along this inclination. , Falls on the upstream end face of the carrier holding mat 14 around it, and at this time, even if it falls on a part away from the concave groove 17,
Since this portion forms an annular groove and is inclined, it reaches the concave groove 17 along the inclination of the annular groove and enters it. Therefore, foreign matter such as welding spatter can be reliably trapped in the groove 17.

Next, a fourth embodiment of the present invention will be described with reference to FIG. In the fourth embodiment, when the catalytic converter is arranged vertically (vertically) or obliquely with respect to the vertical, the upstream end surface of the catalyst carrier 13 is a convex surface. The convex surface may be a spherical surface, a conical surface, or any other convex curved surface as long as the central portion is raised and is inclined downward toward the peripheral edge.

Also in this way, when foreign matter such as welding spatter falls due to vibration or heat fatigue and reaches the catalyst carrier 13 of the catalytic converter 3, since the end surface of the catalyst carrier 13 is a convex surface, welding spatter etc. The foreign matter does not stay here, but slides down, falls on the upstream end face of the carrier holding mat 14 around the foreign substance, and while moving around on this end face, enters the concave groove 17 and is trapped.

Next, FIG. 10 shows the fifth embodiment of the present invention.
~ It demonstrates by FIG. 10 is a cross-sectional view of the catalytic converter mounted in the engine exhaust system, and FIG. 11 is a perspective view of the catalytic converter as seen from the left side (obliquely upper side) of FIG. 10 with the case of the catalytic converter removed. In the fifth embodiment, in the vertical catalytic converter 3 shown in FIG. 10 or in the catalytic converter obliquely placed with respect to the vertical direction shown in FIG. 1, the carrier holding mat 14 has an end face on the upstream side in the exhaust flow direction. A concave groove 17 for trapping a foreign substance is formed.

At least a part of the groove 17 extends in a direction intersecting with the exhaust gas flow direction. Specifically, the groove 17 has a bent portion in the extending direction, and a portion in the middle thereof. Extends in the circumferential direction. By doing this, when foreign matter such as welding spatter enters the concave groove 17, the concave groove 17 is bent, which is a physical obstacle and reliably prevents the foreign matter that has entered the concave groove 17 from jumping out. can do.

FIG. 12 shows a development view of the carrier holding mat 14 in this case. Further, the shape of the fitting concavities and convexities at both ends may be partially changed into a step shape, and the recessed groove 17 may be formed in a step shape on the exhaust upstream side end surface as shown in FIG. Next, a sixth embodiment of the present invention will be described with reference to FIG. In the sixth embodiment, only the shape of the concave groove 17 is changed from the fifth embodiment, and at least a part of the concave groove 17 extends in a direction intersecting the exhaust gas flow direction. Specifically, it first extends obliquely in one direction from the opening, then bends in the middle and extends obliquely in the other direction (opposite direction). Even with such a shape, the same effect as that of the fifth embodiment can be obtained.

Next, FIG. 15 shows the seventh embodiment of the present invention.
Will be described. The seventh embodiment differs from the fifth embodiment only in the shape of the groove 17, and
Has at least a portion extending in a direction intersecting the exhaust flow direction, and specifically, first extends straight from the opening, then bends and extends diagonally, and finally extends straight. The deepest part is V-shaped with a tapered end.

With such a shape, the same effect as that of the fifth embodiment can be obtained, and since the deepest portion has a V-shape with a tapered shape, foreign matter such as welding spatter moves in the deepest portion. Can be trapped and trapped more reliably. Next, an eighth embodiment of the present invention will be described with reference to FIG. FIG.
In (a) to (c), in the fifth to seventh embodiments, the end surface of the carrier holding mat 14 on the upstream side in the exhaust flow direction is inclined in the circumferential direction, and the concave groove 17 with a bent portion is formed in the lowest portion. It is something that is done.

Further, in any case, the concave groove 17 is formed in an uneven portion for fitting at both ends of the carrier holding mat 14 in the winding direction. Figure 16 (a)
FIG. 17 shows a development view of the carrier holding mat 14 in the case of.
With this configuration, when foreign matter such as welding spatter falls from the end surface of the catalyst carrier 13 onto the end surface of the carrier holding mat 14, the end surface of the carrier holding mat 14 causes the catalyst carrier 13 to have an end surface.
Since an annular groove is formed with respect to the end face and the concave groove portion 17 is inclined so as to be the lowermost portion, the concave groove 17 is reached along the inclination of the annular groove and enters therein. Therefore, foreign matter such as welding spatter can be reliably trapped in the concave groove 17 with the bent portion.

The concave groove 17 with a bent portion shown in the fifth to seventh embodiments may be applied to the concave groove 17 of the first to fourth embodiments. In the above embodiment, the concave groove 17 for trapping a foreign substance is directly formed in the carrier holding mat 14, and when the concave groove 17 is previously formed in the carrier holding mat 14 before assembly in this manner, the concave groove 17 is formed. Although it is easy to make the size, shape, etc. of the concave shape desired, it is possible to set the position of the concave groove 17 to an optimum position in the assembled state in which the concave shape is wound around the catalyst carrier 13 and arranged in the main case 10. It can be difficult.

That is, for example, when the catalytic converter 13 is mounted and the end face on the upstream side of the catalyst carrier 13 is inclined, it is desired to install the concave groove 17 at the lowest point of the inclination that can trap foreign matters efficiently. This can be difficult in some cases. Further, it is necessary to confirm and correct the position and direction of the concave groove 17 of the carrier holding mat 14 at the time of assembling, and it is possible that the time required for the assembling increases and the manufacturing cost increases.

Further, since it is difficult to dispose the concave groove 17 at a desired position, it is possible to provide a plurality of concave grooves 17 on the carrier holding mat 14 in advance. In addition to the increase, the holding area of the carrier holding mat 14 is reduced and the holding force is reduced. The ninth and tenth embodiments of the present invention described below solve such problems.

The ninth embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 18 and 20 (a), in a catalytic converter in which a carrier holding mat 14 is wound around a catalyst carrier 13 and housed in a main case (hereinafter, simply referred to as a case) 10, the inner surface of the case 10 is A concave portion 21 is formed in advance at a position facing a formation position of a concave groove for trapping a foreign substance to be formed on the carrier holding mat 14. That is, a concave portion 21 is provided on the inner surface of the case 10 so that a portion overlapping the carrier holding mat 14 has a shape of a concave groove for trapping a foreign substance to be provided on the carrier holding mat 14. Here, the periphery of the recess 21 is tapered so that the case 10 can be easily press-fitted when the catalyst carrier 13 having the carrier holding mat 14 wound thereon is press-fitted.

When the engine is operated in this state, the recess 2
Since the surface pressure of the part of the carrier holding mat 14 facing 1 is lowered, the mat material in this part scatters, and due to wind erosion, as shown in FIG. 19 and FIG. A concave groove 17 for trapping a foreign substance is formed in 14. Therefore, when the recessed groove 17 is directly formed in the carrier holding mat 14, when the carrier holding mat 14 with the recessed groove 17 is assembled, the position of the recessed groove 17 is managed so that the position of the recessed groove 17 becomes a desired position. On the other hand, by positioning and forming the concave portion 21 in the case 10 whose position is easily managed, the concave groove 17 can be formed at that position, and the position management of the concave groove 17 can be performed. It will be easy.

That is, as shown in FIG. 21, when the upstream end surface of the catalyst carrier 13 is inclined in the mounted state of the catalytic converter, the inner surface of the case 10 located at the lowermost portion in the vertical direction of the inclination. By providing the concave portion 21, it is possible to form the concave groove 17 for trapping the foreign matter at the lowermost portion in the vertical direction of the inclination after the engine is operated, without managing the circumferential position of the carrier holding mat 13.

Here, the concave portion 2 provided on the inner surface of the case 10
The size of 1 is as shown in FIG.
7 is V-shaped, and the width of the opening is W (= 8 to 20 m
m) and the length is H (= 10 to 20 mm), the dimensions are almost the same, and the dimensions may be increased by the taper portion. The depth is about 1.5 to 2 mm. Next, a tenth embodiment of the present invention will be described with reference to FIGS. 23 and 24.

In the present embodiment, as shown in FIG. 23, the carrier holding mat 14 is wrapped around the catalyst carrier 13 to form the case 10.
In the catalytic converter housed inside, a concave portion 22 is formed in advance on the outer peripheral wall of the catalyst carrier 13 at a position facing the formation position of the concave groove for trapping a foreign substance to be formed on the carrier holding mat 14. That is, the catalyst carrier 13
A concave portion 22 is provided on the outer peripheral wall so that the portion overlapping the carrier holding mat 14 has the shape of a concave groove for trapping a foreign substance to be provided on the carrier holding mat 14.

When the engine is operated in this state, the recess 2
Since the surface pressure of the part of the carrier holding mat 14 facing the surface 2 is lowered, the mat material in this part scatters and wind erosion causes the carrier holding mat 14 to trap foreign matters as shown in FIG. The groove 17 is formed. Therefore, when the concave groove 17 is directly formed in the carrier holding mat 14, when the carrier holding mat 14 with the concave groove 17 is assembled, the concave groove 17 is formed.
While it is necessary to manage the position at the time of assembly so that the position will be the desired position, the concave portion 22 is formed by positioning it on the catalyst carrier 13 where the position management is relatively easy. The groove 17 can be formed at the position, and the groove 1
Position management of 7 becomes comparatively easy.

Here, as shown in FIG. 24, the size of the recess 22 provided on the outer peripheral wall of the catalyst carrier 13 is such that the desired groove 17 is V-shaped and the width of the opening is W (= 8 to 20 m).
m) and the length is H (= 10 to 20 mm), the size is almost the same, and the catalyst carrier 13 is larger than the carrier holding mat 14 in the exhaust flow direction. Good. The depth is 2.
In the case of 5 mm, it is about 1.5 to 2 mm.

In the ninth and tenth embodiments, the finally formed concave groove 17 for trapping a foreign substance is a V-shaped groove, but at least a part of the concave groove 17 can be formed by setting the shapes of the concave portions 21 and 22. It is also possible to form a groove extending in a direction intersecting the exhaust flow direction.

[Brief description of drawings]

FIG. 1 is a sectional view of a catalytic converter mounted on an engine exhaust system showing a first embodiment of the present invention.

FIG. 2 is a view of the catalyst carrier and carrier holding mat viewed from the left side of FIG.

FIG. 3 is a development view of a carrier holding mat showing an example of forming a groove.

FIG. 4 is a perspective view of a carrier holding mat showing an example of forming a groove.

FIG. 5 is a sectional view of a catalytic converter installed in an engine exhaust system showing a second embodiment of the present invention.

FIG. 6 is a view of the catalyst carrier and carrier holding mat viewed from the left side of FIG.

FIG. 7 is a sectional view and a side view of a catalyst carrier and a carrier holding mat showing a third embodiment of the present invention.

FIG. 8 is a development view of a carrier holding mat according to the third embodiment.

FIG. 9 is a sectional view and a side view of a catalyst carrier and a carrier holding mat showing a fourth embodiment of the present invention.

FIG. 10 is a sectional view of a catalytic converter mounted in an engine exhaust system showing a fifth embodiment of the present invention.

FIG. 11 is a perspective view of a catalyst carrier and a carrier holding mat according to a fifth embodiment.

FIG. 12 is a development view of a carrier holding mat showing an example of forming a groove according to the fifth embodiment.

FIG. 13 is a perspective view of a carrier holding mat showing an example of forming a groove according to the fifth embodiment.

FIG. 14 is a perspective view of a catalyst carrier and a carrier holding mat showing a sixth embodiment of the present invention.

FIG. 15 is a perspective view of a catalyst carrier and a carrier holding mat showing a seventh embodiment of the present invention.

FIG. 16 is a perspective view when the end surface of the carrier holding mat is inclined in the fifth to seventh embodiments showing the eighth embodiment of the present invention.

FIG. 17 is a development view of the carrier holding mat in the case of FIG.

FIG. 18 is a perspective view and a sectional view taken along the line AA of the catalytic converter immediately after the assembly showing the ninth embodiment of the present invention.

FIG. 19 is a perspective view and a cross-sectional view taken along line BB of the catalytic converter after engine operation according to the ninth embodiment.

FIG. 20 is a detailed view of the inner surface of the case according to the ninth embodiment.

FIG. 21 is a perspective view of a mounted catalytic converter according to a ninth embodiment.

FIG. 22 is a detailed view of recesses and grooves in the ninth embodiment.

FIG. 23 is a detailed view of the outer peripheral wall of the catalyst carrier showing the tenth embodiment of the present invention.

FIG. 24 is a detailed view of recesses and grooves in the tenth embodiment.

[Explanation 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 member 16a, 16b Convex part and concave part of fitting part 17 groove 21,22 recess

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ken Ouchi             Nissan, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan             Inside the automobile corporation F-term (reference) 3G091 AB01 BA07 BA21 GA06 GA12                       GA16 HA03 HA27 HA31                 4D048 BB02 BB18 BC10 CA02 CA07                       CC02 CC04 CC06 CC08 CC35                 4G069 AA01 CA02 CA03 EA18 EA27                       ED03 EE01

Claims (14)

[Claims] 1. A catalytic converter for exhaust gas purification, wherein a catalyst carrier is housed in a case forming a part of an exhaust passage of an internal combustion engine via a carrier holding mat wound around the outer periphery of the case. The upstream end face in the exhaust flow direction is mounted so as not to be a surface perpendicular to the vertical direction, and a concave groove for trapping foreign matter is provided on the upstream end face in the exhaust flow direction of the carrier holding mat. Catalytic converter to. 2. The catalytic converter according to claim 1, wherein the catalyst carrier is arranged obliquely with respect to the vertical direction together with the case. 3. The catalytic converter according to claim 1, wherein an end surface of the catalyst carrier on the upstream side in the exhaust gas flow direction is formed to be inclined with respect to the exhaust gas flow direction. 4. The catalytic converter according to claim 1, wherein the upstream end surface of the catalyst carrier in the exhaust flow direction is a convex surface. 5. The method according to claim 1, wherein the concave groove is provided on a side of the catalyst carrier which is lower in an inclination direction of an end surface of an upstream side in an exhaust flow direction. Catalytic converter. 6. A catalytic converter for exhaust gas purification, wherein a catalyst carrier is housed in a case forming a part of an exhaust passage of an internal combustion engine via a carrier holding mat wound around its outer periphery, wherein the carrier holding mat A catalytic converter in which a concave groove for trapping a foreign substance is opened at an end surface on the upstream side in the exhaust flow direction of the above, and at least a part of the concave groove extends in a direction intersecting the exhaust flow direction. 7. The catalytic converter according to claim 6, wherein the concave groove has a bent portion midway in the extending direction. 8. An end face on the upstream side in the exhaust flow direction of the carrier holding mat is inclined in the circumferential direction, and the recessed groove is the lowermost point with respect to the vertical direction on the end face on the upstream side in the exhaust flow direction of the carrier holding mat. It provided in the vicinity of the part used as the following.
Catalytic converter according to item 1. 9. The exhaust gas flow direction upstream end surface of the carrier holding mat is located downstream of the exhaust gas flow direction upstream end surface of the catalyst carrier. The catalytic converter according to claim 8. 10. The groove according to claim 1, wherein the groove is formed in a fitting portion formed by concavities and convexities at both ends in the winding direction of the carrier holding mat. Catalytic converter. 11. The recessed groove is formed such that at least the deepest portion is formed in a tapered shape.
0. The catalytic converter according to any one of 0. 12. The catalytic converter according to claim 1, wherein the concave groove is formed directly on the carrier holding mat. 13. The concave groove is formed in advance on the inner surface of the case at a position facing the formation planned position of the concave groove to be formed on the carrier holding mat, and the concave groove is formed by operating the engine. The catalytic converter according to any one of claims 1 to 11, wherein the concave groove is formed at the planned formation position of the carrier holding mat by wind erosion. 14. The concave groove is a peripheral wall of the catalyst carrier, and is previously formed in a position facing a planned formation position of the concave groove to be formed on the carrier holding mat,
The catalytic converter according to any one of claims 1 to 11, wherein the concave groove is formed at the planned formation position of the carrier holding mat by wind erosion due to engine operation.