JPH0156260B2 - - Google Patents

Description

TECHNICAL FIELD The present invention relates to a gasket structure disposed at a mounting surface between an exhaust manifold and a cylinder head in an internal combustion engine.

Prior Art A gasket provided on a mounting surface between an exhaust manifold and a cylinder head of an internal combustion engine is made of metal in consideration of heat resistance against the high temperature exhaust manifold. In this case, it has been conventionally known to form the gasket into a laminated structure in order to improve the sealing performance. In this case, when comparing the cylinders of an engine, there may be differences in thermal expansion, for example, if the engine is equipped with a turbocharger. That is, depending on the position where the turbocharger is installed, the heat from the turbocharger is transmitted in a concentrated manner to one specific cylinder, and the thermal expansion between that cylinder and the adjacent cylinder becomes large. Therefore, in order to prevent damage to the gasket by absorbing thermal expansion, it is recommended to separate the gasket between cylinders with large thermal expansion, or to provide slack in the gasket between cylinders with large thermal expansion. It is being done. However, in the former case, the assembly is inevitably poor due to the separate structure, and in the latter case, each layer must be made with a different curvature in the part of the gasket to provide slack, which reduces productivity. . In addition, the strength becomes too large, making it difficult to use as a means for loosening.

OBJECTS OF THE INVENTION In view of the drawbacks of the prior art, it is an object of the present invention to provide a laminated gasket structure that can improve both ease of assembly and productivity.

Structure of the Invention In the exhaust manifold gasket of the present invention, the gasket has a single layer in the portion between the cylinder with large thermal expansion and the cylinder with small thermal expansion, and has a multilayer structure in the other portions. The part of the gasket consisting of a single layer between the cylinder and the cylinder with low thermal expansion is slackened. Additionally, each layer is held together by connecting means such as rivets.

Embodiment In FIG. 1, 10 is a cylinder head of an internal combustion engine, and 12 is an exhaust manifold, which has mounting surfaces 10' and 12' facing each other. This internal combustion engine is a four-cylinder engine, and the cylinder head has four exhaust ports 10-1, 10-2, 10-
3, 10-4, while the exhaust manifold 12 has correspondingly four branch pipes 12-1, 12-2,
It has 12-3 and 12-4. Cylinder head 10
A gasket 14 is located between the exhaust manifold 12 and the exhaust manifold 12, and the exhaust manifold 12 is attached to the screw hole 15 of the cylinder head 10 by bolts 18 with the gasket 14 in between. Gaskets are exhaust ports 10-1, 10-2, 10-3, 10-4
It serves to communicate with the corresponding exhaust manifold branch pipes 12-1, 12-2, 12-3, and 12-4 while maintaining a seal with the outside. In the present invention, the gasket is formed by laminating metal plates to improve sealing performance. However, if the cylinders are simply laminated, if there is a difference in thermal expansion between the cylinders, the gasket will not be able to follow such a difference in thermal expansion coefficient, resulting in damage to the gasket. That is, the internal combustion engine of the present invention is equipped with a turbocharger, and the turbocharger is installed above the fourth cylinder. Since the heat load of the turbocharger is large, the thermal expansion of the portion 12-4 of the exhaust manifold below it is large compared to the other first to third portions. As a result, the gasket 14 stretches significantly between the third and fourth cylinders, making it impossible to absorb the expansion. Therefore, the gasket 14 may be damaged during this time.

In order to deal with this problem, the gasket of the present invention has a single layer between the third and fourth cylinders, where thermal expansion is large, and a multilayer in the other parts.
The part of the gasket consisting of a single layer between the 4th and 4th cylinders is slackened. That is, to explain the structure of such a gasket in more detail with reference to FIG. 3, 14a is the first layer of the gasket, which has a size and shape that covers the entire first to fourth cylinders. Motsu. Numeral 14b is a seal plate dedicated to the fourth cylinder, and a plurality (4) of them are stacked on the first layer 14a, which is common to each cylinder. 20,
22 are rivets which hold them together in the assembled state.

On the other hand, the second and subsequent layers of the first to third cylinders are made by stacking the plates 14c and similarly fastened to each other with rivets 28 and 30. As a result, the gasket 14 constitutes one assembly as a whole, thereby improving ease of assembly.
In the assembled state, the gasket 14 has holes 32 through which the bolts 18 that attach the exhaust manifold 12 to the cylinder head 10 pass, and holes 34-1, 34-2, 34-3, 3 through which exhaust gas from each cylinder passes.
Form 4-4.

According to the present invention, the third and fourth
The metal plate constituting the first layer between the cylinders is provided with slack 14a-1. This slack is intended to absorb thermal expansion.

As shown in FIG. 4A, rectangular beads 40 are provided on the metal plates of the top layer and the third layer. This bead 40 has a hole 34 through which exhaust gas passes.
1, 34-2, 34-3, and 34-4. When assembling, this bead 40
This improves the sealing performance to the opposing cylinder head wall surface 10' and the opposing gasket surface, resulting in good sealing performance.

According to the gasket structure of the present invention, only the first layer 14a remains in the gasket at the portion between the third and fourth layers where thermal expansion is large, and there is slack 14a-1 at that portion. During thermal expansion, this slack allows the gasket 14 to stretch and prevents undue stress from being applied to it. Therefore, no damage occurs.

FIG. 4B shows the structure of the #4 cylinder in another embodiment, in which another thin metal plate 14d is provided second from the bottom, resulting in a six-plate structure. On the other hand, #1 to #3 have a five-layer structure, which is the same as in FIG. 4A.

Effects of the Invention The gasket is composed of multiple layers except for the part between the cylinders where thermal expansion is large, and the part of the gasket made of one layer between them is slackened, and each layer is connected by means such as rivets to form a single assembly. By doing so, it is possible to improve productivity and absorb the difference in thermal expansion even if there is a difference in assemblability in the slightest.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the gasket structure of the present invention before assembly between the cylinder head and the exhaust manifold, FIG. 2 is a front view of the gasket of the present invention, and FIG. 3 is the same as that shown in FIG. FIG. 4 is a further enlarged top view showing the structure of each layer of the gasket of the present invention. 10... Cylinder head, 12... Exhaust manifold, 14... Gasket, 14a... First layer, 14
b, 14c... 2nd-5th layer, 14a-1... slackness.

Claims (1)

[Claims] 1. In the exhaust manifold gasket placed on the mounting surface between the exhaust manifold and the cylinder head, the gasket has a single layer in the part between the cylinder with large thermal expansion and the cylinder with small thermal expansion, and has a multilayer in the other part. The gasket is composed of a single layer between a cylinder with a large thermal expansion and a cylinder with a small thermal expansion, and the gasket part is slack, and each layer forms one assembly by a connecting means. Manifold gasket structure.