JP3728579B2 - Connection structure of exhaust manifold and catalyst case - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a connection structure between an exhaust manifold and a catalyst case.
[0002]
[Prior art and problems]
Conventionally, as shown in FIG. 7, when connecting the exhaust manifold 1 and the catalyst case 2 containing the catalyst, a structure in which the pressure contact surface 51 is joined by friction welding is disclosed in, for example, Japanese Patent Laid-Open No. 10-266838. This connection method by friction welding eliminates the need for flanges and bolts, enables effective use of space, reduces the heat capacity, and has an advantage in raising the temperature of the catalyst. As shown in FIG. The case 2 is rotated by the spindle while being pressed by the friction pressure P1 on the pressure contact surface 51, and when the temperature becomes high due to the frictional heat, the oxide compound is pushed out by the dimension of the margin U at the upset pressure P2 and solid-bonded.
The extruded oxide compound (scale) is a cementite structure and is a fragile structure, and therefore cracks inside due to temperature changes during engine operation, and is easily peeled off. In particular, the oxide compound (scale) was pushed inside the pressure contact surface 51. Oxide may fall off during operation, and this may be violated at the top of the catalyst or the like, causing the catalyst to wear or destroying the catalyst.
However, a tool is not used to mechanically remove the oxide compound pushed inward, and if it is attempted to remove it manually, the catalyst itself is damaged, and it is difficult to remove the oxide pushed inward. There was a problem.
[0003]
[Means for Solving the Problems]
The present invention has been devised in view of the above-described conventional problems, and does not provide a connection structure between an exhaust manifold and a catalyst case that can prevent a catalyst from being damaged by an oxidized compound pushed inside the pressure contact surface. The first gist of the present invention is to provide a connection structure in which an exhaust manifold and a catalyst case are connected by friction welding at a pressure contact surface, and an outer wall joined to each of the exhaust manifold and the catalyst case by friction welding. A flange portion projecting in parallel with the outer wall in the radial direction of the outer wall, and a trap groove between the outer wall and the flange portion are integrally formed, and the flange portion of the catalyst case and the flange of the exhaust manifold And the inner surface side of the trap groove is closed .
The second gist is that the radial outer diameter of the flange portion of the exhaust manifold and the radial inner diameter of the flange portion of the catalyst case are set to be substantially the same diameter.
The third gist is that the radial inner diameter of the flange portion of the exhaust manifold and the radial outer diameter of the flange portion of the catalyst case are set to substantially the same diameter.
[0004]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
1 and 2 show the first embodiment. In FIG. 1 , the height of the flange portion 2b on the catalyst case 2 side is set to be substantially equal to the height of the outer wall 2a. A trap groove M1 is formed on the inner side of the outer wall 1a, and a flange 1b is formed so as to protrude in parallel with the outer wall 1a. The width of the trap groove M1 on the exhaust manifold 1 side is the same as that on the catalyst case 2 side. has become those set wider than the width of the trap grooves M, in such a structure, when friction welding is brought into contact with the upper end of the lower end and the outer wall 2a of the catalyst case 2 of the outer wall 1a of the exhaust manifold 1, 2 as shown in, pressure bonding surface P and outer respectively oxidized compound 4a inside, but 4b is pushed, as shown in FIG. 2, the exhaust manifold 1 side of the flange 1b is a catalyst casing 2 side flange portion 2b The trap grooves M and M1 are closed inside by the flange portion 2b and the flange 1b, and the oxidized compound 4a pushed into the trap grooves M and M1 is blocked by the flange portions 2b and 1b. Therefore, the oxidized compound 4a does not act on the inner catalyst 3, and the damage of the catalyst 3 is surely prevented. Even when the oxide compound 4a is peeled off and dropped, the oxide compound 4a cannot come out of the trap grooves M and M1, and the entry to the catalyst 3 side can be surely prevented.
[0005]
Next, FIGS. 3 and 4 show a second embodiment. In this second embodiment, the width of the trap groove M on the catalyst case 2 side is made larger than the width of the trap groove M1 on the exhaust manifold 1 side. is obtained by setting the large, when the outer wall 1a and the outer wall 2a of the catalyst case 2 of the exhaust manifold 1 is abutted to friction welding, as shown in FIG. 4, the catalyst case 2 inside the flange 1b of the exhaust manifold 1 The flange portion 2b is placed in an overlapping manner, the inside of the trap grooves M and M1 is closed by the flange 1b and the flange portion 2b, and the oxidized compound 4a pushed inward from the joint surface is trapped in the trap grooves M and M1. It is impossible to enter from the inside to the inside, and the oxide compound 4a can be reliably stored in the trap grooves M and M1, and the entry of the oxide compound to the catalyst 3 side is reliably prevented. It becomes capable of reliably preventing damage to the catalyst 3.
[0006]
FIG. 5 shows a reference example, which is an enlarged configuration diagram of a main part of a connection portion between the exhaust manifold and the catalyst case, and is located inside the outer wall 2a of the catalyst case 2 connected to the lower end of the exhaust manifold 1 by friction welding. The trap groove M is formed in a concave shape, and a flange portion 2b is integrally formed in a rising shape inside the trap groove M. The height of the flange portion 2b is determined by the friction welding of the exhaust manifold 1. Is set to be equal to or longer than the sum of the shift margin a of the outer wall 2a of the catalyst case 2 and the bottom surface of the trap groove M is lower than the lower end of the shift margin b of the outer wall 2a. The upper end of the outer wall 2a of the catalyst case 2 in which the trap groove M is formed and the lower end of the exhaust manifold 1 are brought into contact with each other and friction welding is performed. Portion of Redirecting a a and b are is pressed, as shown in FIG. 6, respectively oxidized compound 4a inside and outside the pressure bonding surface P to be joined, but so that the 4b is extruded, in the present example, this Since the trap groove M is formed on the inner side of the pressure contact surface P, the oxidized compound 4a pushed inward is blocked by the flange portion 2b and cannot get over the flange portion 2b and is accommodated in the trap groove M. In such a state, even if the oxide compound 4a protruding inward by the operation of the engine is peeled off and dropped off, the oxide compound 4a is stored in the bottom surface of the trap groove M. Thus, the oxidized compound 4a does not contact the catalyst 3, and the catalyst 3 is not destroyed.
[0007]
【The invention's effect】
The present invention provides a connection structure in which an exhaust manifold and a catalyst case are connected by friction welding at a pressure contact surface, an outer wall joined to each of the exhaust manifold and the catalyst case by friction welding, and a radially inner side of the outer wall. A flange portion projecting in parallel with the outer wall and a trap groove between the outer wall and the flange portion are integrally formed, and the flange portion of the catalyst case and the flange portion of the exhaust manifold are overlapped to overlap the trap Since the inner surface side of the groove is closed, the trap groove inside is closed by the overlapped flange, and the compound pushed into the trap groove during friction welding is blocked by the overlapped flange. not to enter into, can leave videos compounds trap groove, can be prevented from entering the catalyst side of the compound, compound It has the effect that it is possible to reliably prevent damage to the catalyst due.
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration diagram of a bonding structure according to a first embodiment.
FIG. 2 is a cross-sectional configuration diagram of the state connected from the state of FIG. 1 by friction welding.
FIG. 3 is a cross-sectional configuration diagram of a connecting portion of a second embodiment.
FIG. 4 is a cross-sectional configuration diagram of the state connected from the state of FIG. 3 by friction welding.
FIG. 5 is an enlarged cross-sectional configuration diagram of a connection portion between an exhaust manifold and a catalyst case of a reference example.
FIG. 6 is an enlarged cross-sectional configuration diagram showing a state in which they are joined by friction welding.
FIG. 7 is a perspective configuration diagram of an exhaust manifold and a catalyst case connected by friction welding.
FIG. 8 is a pressure diagram showing the work process of friction welding.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Exhaust manifold 1a Outer wall 1b Flange 2 Catalyst case 2a Outer wall 2b Flange part 3 Catalyst 4a, 4b Oxidized compound M, M1 Trap groove P Pressure welding interface

Claims (3)

In the connection structure in which the exhaust manifold and catalyst case are connected by friction welding on the pressure contact surface,
In each of the exhaust manifold and the catalyst case,
An outer wall joined by friction welding, a flange portion projecting in parallel with the outer wall on the radially inner side of the outer wall, and a trap groove between the outer wall and the flange portion are integrally formed,
A connection structure between an exhaust manifold and a catalyst case, wherein a flange portion of the catalyst case and a flange portion of the exhaust manifold are overlapped to close an inner surface side of the trap groove . The exhaust manifold-catalyst case connection structure according to claim 1, wherein a radial outer diameter of the flange portion of the exhaust manifold and a radial inner diameter of the flange portion of the catalyst case are set to substantially the same diameter. The exhaust manifold and catalyst case connection structure according to claim 1, wherein a radial inner diameter of the flange portion of the exhaust manifold and a radial outer diameter of the flange portion of the catalyst case are set to be substantially the same diameter.

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