JP2002332834A - Catalytic converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent damages to a catalyst support 13 due to movement of foreign matter around such as weld spatters, on an end face of the catalytic carrier 13. SOLUTION: On an end face on the upstream side in the exhaust flow direction of a catalyst support mat 14 wrapped around the catalyst carrier 13, a recess groove 17 in the V-shaped for trapping the foreign matter is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a catalytic converter for purifying exhaust gas of an internal combustion engine, and more particularly to a technique for protecting a catalyst carrier from foreign substances 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 a catalyst carrier carrying a catalyst, and a part of an exhaust passage is formed through the carrier holding mat. It is stored in the case that constitutes it.

[0003]

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 molding sand in the case of casting, and processing of the casting. When foreign materials such as chips and metal oxides generated in the process of using the internal combustion engine reach the catalyst carrier, they cannot pass through the catalyst carrier and remain on the upstream end face, and the foreign materials such as welding spatter move around. It has been found that there is a problem that the end face shape of the catalyst carrier is deformed.

[0004] Such a problem is remarkable in ceramic monolithic catalyst carriers, in recent years, in order to improve exhaust purification performance, the honeycomb structure has been made thinner and higher in cell density, and the strength of the catalyst carriers has been reduced. It has become.
Then, the present inventors considered trapping with a carrier holding mat so that foreign matter such as welding spatter would not move around on the end surface of the catalyst carrier. Here, JP-A-2000-2
Japanese Patent Application Publication No. 40440 discloses that the carrier holding mat is wound in a natural length flat plate state before the winding of the carrier holding mat before the carrier holding mat is wound in order to prevent the exhaust air from passing (bypassing) at a joint portion of both ends in the winding direction of the carrier holding mat. A large groove is formed in the vicinity of both ends, and a large cut is formed in the vicinity of the center in the winding direction, and the mat is extended at the time of winding, and the hook-shaped portion of the groove is fitted together. A structure in which the components are brought into close contact with each other by a restoring force 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, in such a carrier holding mat, the grooves are too large and too deep, so that (1) the original holding force is reduced and the catalyst carrier cannot be reliably held. (2) The width of the mat is extremely large. Exhaust air is likely to escape from there because there is a narrow part. (3) The strength of the mat decreases, and the shape of the mat cannot be maintained.
As a result, the exhaust gas may escape or the mat may be scattered. (4) Even if spatters enter the grooves, the sputters move in the grooves because the grooves are large, and the mats are damaged. (5) Fitting The size of the final groove changes depending on the degree of alignment and the degree of extension, which causes a problem that the gap may become zero.

[0006] In addition, in the first place, the above publication discloses a catalytic converter arranged vertically or obliquely to the vertical direction,
Since a catalytic converter arranged immediately below the exhaust manifold is not disclosed, trapping such as sputtering cannot be performed effectively from these points. In view of such circumstances, the present invention provides a catalytic converter capable of reliably trapping foreign substances such as welding spatter on the end face of the catalyst carrier by devising a carrier holding mat so as not to move around on the end face of the catalyst carrier. The purpose is to do.

[0007]

Therefore, according to the present invention, the catalyst carrier is accommodated 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. In a catalytic converter for purifying exhaust gas,
A concave portion for trapping foreign matter is provided on the end face on the upstream side in the exhaust flow direction of the carrier holding mat, and the remaining width of the portion of the carrier holding mat where the recess is provided is uneven at both ends in the winding direction of the carrier holding mat. The depth of the recess is set so as to be longer than the width of the protrusion of the fitting portion.

According to a second aspect of the present invention, there is provided a catalytic converter for purifying exhaust gas, wherein a catalyst carrier is accommodated 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. At the end face on the upstream side in the exhaust flow direction of the carrier holding mat, there is a natural-length flat plate state before the winding of the carrier holding mat, except at a fitting portion formed by unevenness at both ends in the winding direction of the carrier holding mat. And a recess for trapping foreign matter is provided.

According to a third aspect of the present invention, there is provided a catalytic converter for purifying exhaust gas, wherein a catalyst carrier is accommodated 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 disposed vertically or obliquely to the vertical direction, and a concave portion for trapping foreign matter is provided on an end face of the carrier holding mat on the upstream side in the exhaust flow direction.

According to a fourth aspect of the present invention, there is provided a catalytic converter for purifying exhaust gas, wherein a catalyst carrier is accommodated in a case constituting a part of an exhaust passage of an internal combustion engine via a carrier holding mat wound around the periphery thereof. The catalyst carrier is disposed immediately below the exhaust manifold and is provided with a foreign matter trapping recess on the end face of the carrier holding mat on the upstream side in the exhaust flow direction.

According to a fifth aspect of the present invention, the concave is a concave groove, and in the sixth aspect of the present invention, the concave is V-shaped. The invention according to claim 7 is characterized in that a plurality of the recesses are provided so as to be arranged at substantially equal intervals in a circumferential direction in a state where the carrier holding mat is wound around the catalyst carrier. The invention according to claim 8 is characterized in that the recess is provided also on the end face on the downstream side in the exhaust flow direction of the carrier holding mat.

According to a ninth aspect of the present invention, the end face of the carrier holding mat upstream of the exhaust flow direction is located downstream of the end face of the catalyst carrier upstream of the exhaust flow direction. I do. According to a tenth aspect of the present invention, the catalyst carrier is a ceramic monolith catalyst carrier, and in the eleventh aspect of the present invention, the catalyst carrier has a thin-walled honeycomb structure having a wall thickness of 0.1 mm or less.

In the twelfth aspect of the present invention, the exhaust manifold is formed by pipe welding. In the thirteenth aspect of the present invention, the case of the catalytic converter is integrally welded to the exhaust manifold formed by pipe welding. It is characterized by.

[0014]

According to the first to fourth aspects of the present invention, when foreign matter such as welding spatter reaches the catalyst carrier, the foreign matter enters the recess when moving around the end surface of the surrounding carrier holding mat. Be trapped. Therefore, breakage of the catalyst carrier due to foreign matter such as welding spatter moving around the end surface of the catalyst carrier can be reliably prevented.

In particular, in the case of the first aspect of the present invention, the remaining width W1 of the carrier holding mat in the recessed portion is the width W2 of the convex portion of the fitting portion due to the unevenness of both ends in the winding direction of the carrier holding mat. Since the depth of the dent is set so as to be longer, that is, even if the dent is provided, the part (W1) is the part (W2) where exhaust is most likely to escape.
Rather, it is difficult for the exhaust gas to escape, so that a sufficient holding function and prevention of the exhaust gas from being emitted can be achieved.

In particular, in the case of the second aspect of the present invention, the dent exists from a state of a flat plate having a natural length before winding of the carrier holding mat, except at a fitting portion formed by irregularities at both ends in the winding direction of the carrier holding mat. As a result, no extra force is applied to the carrier holding mat in the wound state, so that a sufficient holding function can be maintained, and since the shape is not changed, the size of the trap recess does not vary.

In particular, in the case of the third aspect of the present invention, since the catalyst carrier is disposed in the vertical direction or obliquely to the vertical direction, once foreign matter such as welding spatter enters the dent, it does not come off, so Can be trapped. In particular, in the case of the invention of claim 4, since the catalyst carrier is arranged immediately below the exhaust manifold, foreign substances such as welding spatter from the exhaust manifold can be reliably trapped.

According to the fifth aspect of the present invention, since the recess is a concave groove, it can be easily manufactured. Further, according to the sixth aspect of the present invention, since the concave groove is V-shaped, it can be welded once. If a foreign substance such as spatter enters the dent, it becomes narrower as it goes deeper, so that the movement can be confined, and the mat can be prevented from slipping out and damaging the mat. According to the invention of claim 7, since a plurality of the recesses are provided so as to be arranged at substantially equal intervals in the circumferential direction in a wound state of the carrier holding mat, trap efficiency can be further improved, and It is also possible to prevent a change in trap efficiency due to the winding position of the trap.

According to the eighth aspect of the present invention, since the recess is provided also on the end face of the carrier holding mat on the downstream side in the exhaust flow direction, it is not necessary to consider the direction when winding the mat, and the winding operation is easy. Becomes According to the ninth aspect of the present invention, the upstream end face of the carrier holding mat is located downstream from the upstream end face of the catalyst carrier, so that the carrier holding mat is positioned with respect to the upstream end face of the catalyst carrier. Since the upstream end surface forms an annular groove, if foreign matter such as welding spatter moves on the end surface of the carrier holding mat, this portion is formed as an annular groove, so that it returns to the end surface of the catalyst carrier again. But as it moves around here, it gets trapped in a dent,
The trap efficiency can be further improved.

According to the tenth aspect of the present invention, the present invention is applied to a ceramic monolith catalyst carrier, and according to the eleventh aspect of the present invention, the present invention is applied to a thin-walled honeycomb structure, whereby the strength is further reduced. Therefore, the effect of the present invention becomes more remarkable. According to the twelfth aspect of the present invention, by applying to an exhaust manifold formed by pipe welding, welding spatter is more likely to occur, so that the effects of the present invention become more remarkable, and further, the invention of the thirteenth aspect According to the present invention, it is difficult to disassemble the catalytic converter to remove welding spatter by applying the present invention to an exhaust manifold formed by pipe welding and an integral type catalytic converter. It becomes even more noticeable.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention, in which a vertical direction as shown in FIG. 1A or a vertical direction as shown in FIG. 1B immediately below a collecting portion of an exhaust manifold 2 connected and fixed to a cylinder head 1 of an engine. 2), the catalytic converter 3 is provided obliquely to the vertical direction, and an exhaust pipe (front tube) 4 is connected and fixed to the outlet side of the catalytic converter 3.

In the example of FIG. 1, the case of the catalytic converter 3 is fixed by welding to the exhaust manifold 2 formed by pipe welding, but the case of the catalytic converter 3 is formed separately from the exhaust manifold 2. Then, the flange portions may be bolted to each other. The case of the catalytic converter 3 constitutes a part of an exhaust passage, and includes a cylindrical main case 10 and substantially conical diffusers 11, 12 connected to the inlet side and the outlet side by welding, respectively. .

The catalyst carrier 13 is provided in the main case 10.
Via a carrier holding mat 14 wound around the outer periphery thereof,
It is stored. Reference numeral 15 denotes a locking washer member. The catalyst carrier 13 is a ceramic monolith catalyst carrier of a honeycomb structure having a columnar outer shape. This is to increase the cell density. This is equivalent to the wall thickness of 8 which has been generally used in the past.
Mill (= 0.220 mm) or 4 mil (= 0.11)
(0 mm). The catalyst is coated on the support surface.

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

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. It is desirable that the support holding mat 14 be lower and an annular groove be formed around the catalyst support 13 as shown in FIG. In addition, a rectangular projection 16a is formed at one end of the winding direction of the carrier holding mat 14 at the center in the exhaust flow direction, and the projection is formed at the other end. A rectangular recess 16b is formed at a position corresponding to 16a.

Therefore, as shown in FIG.
When the carrier holding mat 14 is wound around the outer periphery of the, the projections 16a and the recesses 16b at both ends are fitted to each other to prevent the exhaust from being released from the mating portion at both ends. 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.

The number of the concave grooves 17 may be one, but here, in order to enhance the trapping efficiency, 180 ° in the wound state.
Two are formed so as to have an interval. Of course, FIG.
As shown in (1), a larger number may be formed at regular intervals. V
The size of the U-shaped groove 17 is, as shown in FIG.
Is about 10-20 mm, and the size s of the opening is 8-20.
mm. At the intersection of the V-shape, a radius R is attached so that the mat is not scattered, and it is desirable that the radius R is 2 mm or less so that trapped welding spatter or the like can be contained.

In this case, referring to FIG.
The remaining width W1 (= W−d) in the exhaust flow direction of the carrier holding mat 14 in the portion where the U-shaped concave groove 17 is formed is larger than the width W2 in the exhaust flow direction of the projection 16a of the fitting portion. Next, the depth d of the V-shaped concave groove 17 is set. Here, W2 is the width in the exhaust flow direction of the portion where the exhaust is most likely to escape, 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
Even if the V-shaped concave groove 17 is formed, the escape of the exhaust is not promoted and the holding force is not reduced.

As shown in FIG. 6 (a), if a groove 17 is provided on the downstream end face in addition to the upstream end face in the exhaust flow direction in the unfolded state, the upstream and downstream ends can be wound during winding. There is no need to consider the direction, and the assembling work becomes easier. In this case as well, W1> W2, but the width W1 of the carrier holding mat 14 in the exhaust flow direction at the portion where the V-shaped concave groove 17 is formed is W1 = W−2 × d.

As shown in FIG. 6B, even if the grooves 17 are formed on the upstream side and the downstream side, if the positions of the grooves 17 on the upstream side and the downstream side are shifted, W1 = W −d. Further, as shown in FIG.
When a and 16b are formed, W2 in the drawing is used as a reference. According to the above configuration, welding spatter when the exhaust manifold 2 is formed by pipe welding or the like in a manufacturing stage, residual molding sand in the case of a casting, processing chips, and metal oxidation generated in the operation process of the internal combustion engine Even if a foreign substance 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 face of the carrier holding mat 14,
While moving on the end face, it enters the V-shaped concave groove 17 and is trapped. Once in the concave groove 17, it does not jump out because it is V-shaped and narrows. Certainly trapped.

Accordingly, foreign matters such as welding spatters can be reliably trapped without causing a decrease in the holding force of the carrier holding mat 14 or the escape of exhaust gas, and the catalyst carrier 13 can be prevented from being damaged. When the catalytic converter is placed obliquely with respect to the vertical direction, it is more preferable that the concave groove be arranged near the position that is the lowest point in the vertical direction on the upstream end surface of the carrier holding mat. Can be trapped reliably.

When the thickness of the carrier holding mat is sufficient, a conical tapered hole may be provided instead of the V-shaped concave groove as the concave for trapping foreign matter.

[Brief description of the drawings]

FIG. 1 is a sectional view of a catalytic converter showing one embodiment of the present invention.

FIG. 2 is a perspective view of a state where a carrier holding mat is wound around a catalyst carrier.

FIG. 3 is a development view of the carrier holding mat.

FIG. 4 is a detailed view of a concave groove.

FIG. 5 is a perspective view showing another embodiment.

FIG. 6 is a development view showing another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine cylinder head 2 Exhaust manifold 3 Catalytic converter 4 Exhaust pipe 10 Main case 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 V-shaped Groove

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B01J 33/00 F01N 3/24 F F01N 3/24 7/18 7/18 B01D 53/36 C (72) Inventor large Ken Uchi 2 Nissan Motor Co., Ltd., Nissan Motor Co., Ltd. (72) Kura Nishizawa, Nissan Motor Co., Ltd. 2 Nissan Motor Co., Ltd. Nissan Motor Co., Ltd. 3G004 BA06 DA04 FA04 GA06 3G091 AA28 AB01 BA07 BA39 GA06 HA03 HA27 HB01 4D048 BB02 BB05 BB08 BB13 BB18 BC06 CA01 4G069 AA01 CA03 DA06 EA09 EA16 FB72

Claims (13)

[Claims] 1. A catalyst converter for purifying exhaust gas, wherein 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 of the catalyst carrier. A recess for foreign matter traps is provided on the end face on the upstream side in the exhaust flow direction of the exhaust gas, and the remaining width of the carrier holding mat in the portion provided with the recess is
A catalytic converter characterized in that the depth of the recess is set so as to be longer than the width of the protrusion of the fitting portion due to the unevenness of both ends in the winding direction of the carrier holding mat. 2. A catalytic converter for purifying exhaust gas, wherein a catalyst carrier is accommodated 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 of the catalyst carrier. For the foreign matter trap, which exists in the end face on the upstream side in the exhaust flow direction, except for the fitting portion due to the unevenness of the both ends in the winding direction of the carrier holding mat, from the flat state of the natural length before the winding of the carrier holding mat. A catalytic converter characterized by having a concave portion. 3. A catalytic converter for purifying an exhaust gas, wherein a catalyst carrier is accommodated 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 of the catalyst carrier. A catalytic converter, which is arranged in a vertical direction or obliquely with respect to the vertical direction, and has a concave portion for trapping foreign matter on an end face of the carrier holding mat on the upstream side in an exhaust flow direction. 4. A catalytic converter for purifying exhaust gas, wherein a catalyst carrier is accommodated 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 of the catalyst carrier. A catalytic converter, which is disposed immediately below an exhaust manifold and is provided with a concave portion for trapping foreign matter on an end face of the carrier holding mat on an upstream side in an exhaust flow direction. 5. The catalytic converter according to claim 1, wherein said recess is a groove. 6. The catalytic converter according to claim 5, wherein said groove has a V-shape. 7. The method according to claim 1, wherein the recesses are arranged at substantially equal intervals in a circumferential direction in a state where the carrier holding mat is wound around the catalyst carrier.
The catalytic converter according to any one of claims 1 to 6, wherein a plurality of the catalytic converters are provided. 8. The apparatus according to claim 1, wherein said recess is provided also on an end face of the carrier holding mat on the downstream side in the exhaust flow direction.
A catalytic converter according to claim 7. 9. An exhaust gas flow direction upstream end face of the carrier holding mat is located on an exhaust flow direction downstream side of an exhaust flow direction upstream end face of the catalyst carrier. A catalytic converter according to claim 8. 10. The catalytic converter according to claim 1, wherein the catalyst carrier is a ceramic monolith catalyst carrier. 11. The catalytic converter according to claim 10, wherein said catalyst carrier has a thin-walled honeycomb structure having a wall thickness of 0.1 mm or less. 12. The catalytic converter according to claim 1, wherein the exhaust manifold is formed by pipe welding. 13. The catalytic converter according to claim 12, wherein a case of the catalytic converter is integrally welded to an exhaust manifold formed by pipe welding.