JP2002054436A - Exhaust manifold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust manifold capable of protecting a catalyst holding material in good performance and being embodied at a low cost by means of lessening of the number of component parts. SOLUTION: The exhaust manifold 5 is to be joined with upstream of a catalyst case 1 fitted internally with a catalyst 2 whereon a catalyst holding material 3 is fitted, wherein a weir 5d for preventing the exhaust gas from direct bombardment is formed consolidatedly in such a way as preventing the exhaust gas from directly blowing to the upstream end of the catalyst holding material 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust manifold joined upstream of a catalyst case containing a catalyst.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional catalyst holding structure, and FIG. 5 is an exploded perspective view of constituent members. The catalyst 2 is held in the catalyst case 1 with a catalyst holding material 3 interposed therebetween. A flange portion 1c formed on the upstream end side of the catalyst case 1 is in contact with a flange portion 5a of the exhaust manifold 5. They are connected by bolts 54. The catalyst 2 purifies the exhaust gas, and is formed by coating a ceramic or metal honeycomb-shaped carrier with a noble metal such as platinum, rhodium, or palladium, thereby increasing the catalyst conversion efficiency for the exhaust gas. For this reason, the walls between each cell are very thin honeycomb-shaped, and if a gap is formed between the catalyst case 1 and the catalyst case 1 due to vibration during engine operation.
There is a possibility that the catalyst may be damaged by colliding with the inner wall of the engine, and in order to fill the gap, it is protected by a catalyst holding material 3 made of metal mesh or glass fiber. The catalyst case 1 is provided with a stopper step 1d to prevent the catalyst 2 from moving downstream, and the surface pressure of the catalyst 2 against the stopper step 1d is increased. When the exhaust gas pressure is high, an elastic buffer material 53 may be attached between the bottom cap 52 and the downstream end of the catalyst holding material 3 when the exhaust gas pressure is high. . Further, an upper cap 51 is provided on the upstream side in order to prevent the catalyst holding member 3 from being degraded by heat or corrosion due to a direct hit of the exhaust gas.

[0003] The conventional structure has a problem that the number of components is large and the assembly is complicated. Further, when the catalyst case 1 and the exhaust manifold 5 are joined by friction welding, the catalyst case 1 and the exhaust manifold 5 are connected to each other. There is a problem that the upper cap 51 rotates together with the exhaust manifold 5 in order to provide a continuous relative rotational movement, thereby damaging the catalyst 2 and the catalyst holding material 3.

In order to solve such a problem, the inventor has already applied for a structure as shown in a sectional view of FIG. 6 and an exploded perspective view of components shown in FIG. That is, in FIGS. 6 and 7, the spacer 4 is interposed on the outer peripheral side of the catalyst holding material 3, and the spacer 4 is configured such that the overlapping portion 4 a is overlapped so that the diameter can be increased in the radial direction. A flange portion 4b is integrally formed on the end side in an inwardly bent shape, and a plurality of claw portions 4c are formed on the downstream end side. On the other hand, the catalyst case 1 has a funnel having a tapered surface. A portion 1a is formed on the downstream side, and the downstream end of the catalyst holding material 3 and the claw portion 4c of the spacer 4 are bent along the tapered funnel portion 1a, so that the catalyst 2 and the catalyst holding material 3 are separated. It is configured so that it can be fixed in the axial direction. Further, the flange portion 4b of the spacer 4 covers the upstream end of the catalyst holding member 3 so as to prevent the catalyst holding member 3 from being degraded due to heat or corrosion due to direct impact of exhaust gas. . However, many steps are required to form the spacer 4 in such a shape that the claws 4c are provided at the downstream end and the flanges 4b are provided at the upstream end and the diameter of the spacer 4 can be increased. In addition, since the upstream flange 4b is formed, wrinkles and cracks are likely to occur during forging, and there is a problem that the manufacturing cost of the spacer 4 increases.

[0005]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned conventional problems, and has an exhaust manifold which can be formed at a low cost with a small number of parts and can protect the catalyst holding material well. The first gist of the present invention is to provide an exhaust manifold joined to an upstream side of a catalyst case including a catalyst in which a catalyst holding material is fitted, and the exhaust manifold includes the exhaust manifold. An exhaust gas direct hit prevention weir that can prevent exhaust gas from directly hitting the upstream end of the catalyst holding material is integrally formed. The second gist is that, in a state where the exhaust manifold is joined to the catalyst case, the inner periphery of the downstream end of the exhaust gas direct hit prevention weir is
It is arranged at a position of 3 mm or less inward from the inner periphery of the catalyst holding material, and is set so that the gap between the downstream end of the exhaust gas direct impact prevention dam and the upstream end of the catalyst is 5 mm or less. A third gist is that an exhaust gas direct hit prevention weir is formed on the inner side of the joint where the exhaust manifold is joined to the catalyst case in a shape of a diameter decreasing in a direction parallel to the flow direction of the exhaust gas or in a downstream direction. That is, it is formed to protrude.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a state in which a catalyst case and an exhaust manifold are joined. In the catalyst case 1, a catalyst 2 having a catalyst holding material 3 fitted therein is provided, and is formed in the catalyst case 1. Cap 52 on the stopper step 1d
The catalyst holding member 3 and the catalyst 2 are fixed in a state where the movement to the downstream side is prevented by the cap 52, and the upstream end of the catalyst case 1 protrudes outward and has a flange portion 1c.
Is formed on the inner side of the flange portion 1c, and an anti-burr weir 1b is formed integrally and protrudes upstream.

Further, the flange portion 1c of the catalyst case 1
A joining convex portion 5b is formed to project from the outer periphery of the downstream end of the exhaust manifold 5 joined by friction welding, and the joining convex portion 5b is friction-welded to the flange portion 1c at the friction joining surface P. A concave portion 5c is formed on the inner side of the joining convex portion 5b of the exhaust manifold 5 so as to be concave toward the upstream side.
5d, which protrudes to the downstream side and that prevents exhaust gas
Are integrally formed in a protruding shape over the entire circumference.

The diameter D2 of the inner peripheral surface of the exhaust gas direct hit prevention weir 5d is equal to the inner diameter of the catalyst holding member 3 (outer diameter of the catalyst 2) D1
Is set so that D1−D2 ≧ 0 to 6 mm. That is, the exhaust gas direct hit prevention weir 5d is set so that the inner periphery of the exhaust gas direct hit prevention weir 5d is located inside the inner periphery of the catalyst holding member 3, and the exhaust gas direct hit prevention weir 5d is in the flow direction of the exhaust gas passing through the exhaust manifold 5. Are formed in parallel.
Therefore, the exhaust gas flowing in the exhaust manifold 5 directly hits the catalyst 2 through the inner circumference of the exhaust gas direct hit prevention weir 5d,
The exhaust gas does not hit the upper end of the catalyst holding material 3 directly,
The catalyst holding member 3 is configured to favorably prevent heat sag or deterioration due to direct impact of exhaust gas.

The burr-preventing weir 1b is inserted into the concave portion 5c outside the exhaust gas direct-hit burr 5d. When the friction welding is performed on the friction-welding surface P, the burr is prevented. In order to prevent the catalyst 2 from entering inside and damaging the catalyst 2, the burrs 1 b prevent the burrs from entering the inside.

FIG. 2 is an enlarged sectional view of a main part of a modified example of the exhaust gas direct hit prevention dam 5d. As shown in the exhaust gas direct hit prevention dam 5d of FIG. 5
e may be formed. The inclined surface 5e is
The diameter can be reduced from the upstream side to the downstream side so that the angle θ is θ ≧ 0 °. When the inclined surface 5e is formed as described above, the exhaust gas passing through the exhaust manifold 5 flows inward along the inclined surface 5e, and it is possible to prevent the exhaust gas from directly hitting the upper end of the catalyst holding member 3. You can do it.

In order to prevent the exhaust gas from directly hitting the catalyst holding member 3, the inside diameter D2 of the exhaust gas direct hit prevention weir 5d is
It is only necessary to set the size to be considerably smaller than the inner diameter D1 of the catalyst holding member 3. However, in this case, many inert areas through which exhaust gas does not pass are generated on the outer peripheral side of the catalyst 2, and the purification of the catalyst 2 is performed. Since the performance cannot be sufficiently exhibited, the dimension of D2 can be set such that the dimension of the inactive area of the catalyst shown in FIG. 2D is 1 to 3 mm or less. That is, from the inner periphery of the catalyst holding material 3 to the inside, 1
It is preferable to set the inner circumference of the exhaust gas direct hit prevention weir 5d within a range of not more than 3 mm. In addition, it is preferable that the dimension of d is set to be 1 to 3 mm or less in consideration of the deviation of the axis when joining at the friction pressure contact surface P.

Further, in the state where the joining by the friction welding is completed,
It is preferable to set the gap t between the downstream end of the exhaust gas direct hit prevention dam 5d and the upstream end of the catalyst 2 to be 5 mm or less. That is, the smaller the size of the gap t, the smaller the amount of exhaust gas flowing around, so that it is possible to prevent the exhaust gas from directly hitting the catalyst holding member 3. If t is too small, the downstream end of the exhaust gas direct impact prevention weir 5d may contact the upstream end of the catalyst 2 and cause damage to the catalyst 2, so that the gap t is 5 mm or less in relation to friction welding. It is good to set in the range.

As described above, the exhaust gas direct hit prevention weir 5d is formed integrally with the exhaust manifold 5 so as to protrude in parallel with the flow direction of the exhaust gas or with a reduced diameter toward the downstream direction.
Omit parts such as caps and spacers as in the past,
The catalyst holding member 3 can be protected well, the number of parts is small, and the whole can be manufactured at low cost.

In addition, such an exhaust gas direct hit prevention weir 5d
The exhaust manifold 5 in which the flange 5a is formed as shown in the modified example of FIG.
The structure can be adopted also in a structure in which the exhaust gas is prevented from directly hitting the upstream end of the catalyst holding member 3 by the exhaust direct hit prevention weir 5d. And can be formed inexpensively.

[0015]

According to the present invention, there is provided an exhaust manifold joined to an upstream side of a catalyst case in which a catalyst in which a catalyst holding material is fitted is provided, and the exhaust manifold is provided with an exhaust gas at an upstream end of the catalyst holding material. Exhaust gas direct hit prevention weir that can prevent gas from hitting directly is integrally formed,
The catalyst holding material can be protected well without using a cap or a spacer to prevent the deterioration of the catalyst holding material, the number of parts is reduced, and the whole can be manufactured at low cost.

Further, in a state where the exhaust manifold is joined to the catalyst case, the inner periphery of the downstream end of the exhaust gas direct hit prevention weir is
It is preferably located at a position of 3 mm or less inward from the inner periphery of the catalyst holding material, and the gap between the downstream end of the exhaust gas direct impact prevention dam and the upstream end of the catalyst is set to 5 mm or less. While protecting the catalyst holding material, the inactive area of the catalyst can be reduced to improve the performance of the catalyst.

In addition, an exhaust gas direct hit prevention weir is formed on the inner side of the joint where the exhaust manifold is joined to the catalyst case, in a direction parallel to the flow direction of the exhaust gas or in a reduced diameter toward the downstream direction. As a result, the exhaust manifold is satisfactorily joined to the catalyst case by friction pressure welding, etc., and the exhaust gas direct hit prevention weir protects the catalyst holding material inside the catalyst case well, reduces the number of parts and manufactures at low cost Can be done.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram illustrating a joined state of a catalyst case and an exhaust manifold according to a first embodiment.

FIG. 2 is an enlarged sectional configuration view of a main part of a second embodiment.

FIG. 3 is a cross-sectional configuration diagram of a joined state of a catalyst case and an exhaust manifold according to a third embodiment.

FIG. 4 is a cross-sectional configuration diagram of a conventional structure.

FIG. 5 is an exploded perspective view of the components of FIG.

FIG. 6 is a cross-sectional configuration diagram when a spacer is used.

FIG. 7 is an exploded perspective view of the constituent members of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Catalyst case 1b Melting prevention barrier 1c Flange part 1d Stopper step part 2 Catalyst 3 Catalyst holding material 5 Exhaust manifold 5a Flange part 5b Joining convex part 5c Concave part 5d Exhaust gas direct hit prevention weir 52 Cap 54 Bolt P Friction joining surface D1 Catalyst holding Inner diameter of material D2 Inner diameter of exhaust gas direct hit prevention dam d Distance from inner circumference to inside of catalyst holding material (dimension of inactive area) t Clearance between lower end of exhaust gas direct hit prevention dam and upstream end of catalyst

 ──────────────────────────────────────────────────続 き Continued on front page F-term (reference) 3G004 BA06 DA02 DA12 3G091 AA28 AB01 BA07 BA39 CA27 GA07 GA21 GB01Z HA03 HA27 HA28 HA31 HA46 HB01 4D048 AA06 AA13 AA18 AB01 AB02 BA10X BA30X BA31X BA33X BA39X BB02 CA01 CC02 CC03 CC03

Claims (3)

[Claims] An exhaust manifold joined to an upstream side of a catalyst case having a catalyst inside which a catalyst holding material is fitted, wherein exhaust gas is supplied to an upstream end of the catalyst holding material. An exhaust manifold, wherein an exhaust gas direct hit prevention weir that can prevent direct hitting is integrally formed. 2. The exhaust gas direct hit prevention weir in a state in which the exhaust manifold is joined to the catalyst case, wherein the inner periphery of the downstream end of the weir is disposed at a position of 3 mm or less inward from the inner periphery of the catalyst holding material. The exhaust manifold according to claim 1, wherein a gap between a downstream end of the prevention weir and an upstream end of the catalyst is set to be 5 mm or less. 3. An exhaust gas direct impact prevention weir is formed on the inner side of a joint portion where the exhaust manifold is joined to the catalyst case, in a direction parallel to or in a downstream direction of the exhaust gas so as to have a diameter decreasing toward the entire circumference. The exhaust manifold according to claim 1, wherein the exhaust manifold is provided.