JPH08277936A - Gasket of engine - Google Patents

Abstract

PURPOSE: To provide the gasket of an engine, which has a good sealing property around a cylinder bore hole, and which has a simple structure, in the case where a cylinder is assembled. CONSTITUTION: An annular bead 5 is formed on a flat shaped gasket 1 interposed between a cylinder head and a cylinder block, and the bead 5 is bent along a bore circumferential rim while holding the height of the head 5 constant, and the width thereof is enlarged axisymmetrically on a circumference in several positions. The gasket 1 is held between the cylinder head and the cylinder block, the width of the bead near a bolt hole 3 is reduced, the width of the bead between the bolt holes is enlarged, and thereby, the bead having spring characteristic such that it is hard near the bolt hole and be soft between the bolt holes, is formed. The surface pressure of the bore circumferential rim of the gasket 1 is equalized when bolt is fastened, and deformation of the cylinder head corresponding thereto is also equalized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to automobiles, motorcycles,
The present invention relates to a gasket used for an engine such as an outboard motor.

[0002]

2. Description of the Related Art Conventionally, in engines used in automobiles, motorcycles, outboard motors, etc., a cylinder block and a cylinder head are connected with a bolt for tightening through a gasket,
The operation of the piston inside this prevents gas leakage when inhaling and exhausting gas.

When the gasket is tightened with bolts, the gasket is crushed along the connecting surface between the cylinder block and the cylinder head, so that the adhesion is improved. As an example, the gasket 1 shown in FIGS. 8 and 9 has four bolt holes 3 formed around the hole 2 for the cylinder bore, and the gasket 1 has a three-layer structure. A bead 5 protruding in a shape is provided, and when it is tightened with a bolt, the crushed state is effectively made.

By the way, at the locations a, b, and c around the cylinder bore 2 of the gasket 1 shown in FIG. 8, the force applied to the gasket 1 at that portion changes depending on the distance from the bolt, so as shown in FIG. There is a difference in surface pressure. Therefore, as disclosed in Japanese Utility Model Publication No. 2-16048, the gasket portion around the cylinder bore, which is far from the bolt, is made of a soft material to have a thickness, and the vicinity of the bolt and the location apart from the bolt are The surface pressure is made uniform. Further, Japanese Utility Model Application Laid-Open No. 58-148247 discloses that a portion apart from the bolt in the vicinity of the cylinder bore is made thicker than other portions.

[0005]

However, as a measure for making the surface pressure uniform, as in the above publication, the gasket 1 is used.
It is difficult and costly in manufacturing to partially change the thickness and the material of the material in the vicinity of the bolt and in a portion apart from the bolt. Further, when only the thickness of the gasket is partially changed, a load is applied to the cylinder head side due to the difference in the thickness of the gasket, and noise or the like may occur due to the stress generated in the mechanism inside the cylinder head.

According to the present invention, when the cylinder is assembled,
An object of the present invention is to provide an engine gasket having a simple structure in which the surface pressure around the cylinder bore hole is made uniform.

[0007]

In order to achieve the above object, the present invention folds a flat gasket, which is interposed between a cylinder head and a cylinder block, at a constant height along the peripheral edge of the bore, and It is characterized in that an annular bead whose width is enlarged at several positions on the circumference of the circumference is formed.

Further, in the above-mentioned structure, the place where the width of the bead is maximized is a position corresponding to an intermediate portion between two adjacent bolt holes among a plurality of bolt holes provided in the peripheral edge of the bore. To do.

[0009]

The present invention is configured as described above, and the width of the bead of the gasket continuously changes in the circumferential direction, and the wider bead has a softer spring characteristic and the narrower bead has a harder spring characteristic. When this gasket is used for bolting the cylinder, by reducing the bead width near the bolt, the surface pressure on the peripheral edge of the bore of the gasket becomes uniform and the assemblability is improved.

Further, a gasket is sandwiched between the cylinder head and the cylinder block, and the bead width is small near the bolt holes of the gasket, and the bead width is large between the bolt holes, so that the bead is hard between the bolts. It will have a bead with a soft spring characteristic. Therefore, the surface pressure on the periphery of the bore of the gasket becomes uniform, and
The corresponding deformation of the cylinder head is also uniform.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. A gasket 1 shown in FIG. 1 has a bead 5 formed around a hole 2 for a cylinder bore, and bolt holes 3 are arranged at four equal intervals on the circumference of the hole 2 for a cylinder bore. The bead 5 is formed in an annular shape between the cylinder bore hole 2 and the bolt hole 3, and in the vicinity of the bolt position, as shown in FIG.
The triangular width of the cross section is L1, and between the bolts, as shown in FIG. 3, the triangular width of the cross section (BB cross section of FIG. 1) is L2, and the mutual relationship is L1 <L2. Is. The heights H of the two are the same.

Although the above structure has four bolt holes 3,
The value taken by the bead width is not limited to the number of bolt holes 3 and may be determined by the following equation. L = a · cos Nθ + b L: bead width θ: angle a, b: coefficient N: number of bolts N = 4 in the embodiment

In a gasket in which the width of the bead 5 is widened at required points, the result of the difference in the width is that the wide bead B has a soft spring characteristic and the narrow bead A has a hard spring characteristic, as shown in FIG. Become. As shown in FIG. 5, a model in which an upper plate 6 that serves as a cylinder head, a gasket 7, and a lower plate 8 that serves as a cylinder block are stacked is tightened with bolts 9,
When inspecting points d (between bolts), e (bolt position), and f (near bolts), as shown in FIGS. 6 and 7, a bead having a certain hardness is hardened around the bolt. The bead with a softer space has more uniform surface pressure and displacement.

Therefore, the gasket 1 of the present invention has a bead 5 having a spring characteristic that is hard in the vicinity of the bolts and soft between the bolts. When the gasket 1 having such a spring characteristic is sandwiched between the cylinder head and the cylinder, it becomes uniform. Compared with a gasket having spring characteristics, the surface pressure between the bolts is large, and the cylinder head is evenly deformed. Then, by using this gasket 1, the sealing property is improved and the deformation of the cylinder can be reduced.

Further, since the characteristics can be changed only by changing the shape of the bead 5 of the gasket 1, the manufacturing cost can be reduced, and the height is constant, which facilitates transportation and packing. Is. Besides, it can be applied not only to the engine but also to bolting of manifold pipes, oil supply pipes and the like.

[0015]

Since the present invention is configured as described above, the gasket is sandwiched between the cylinder head and the cylinder block, the bead width near the bolts is small, and the bead width between the bolts is large. By
A bead having a spring characteristic that is hard near the bolts and soft between the bolts is provided, and since the surface pressure of the gasket is made uniform, it becomes possible to reliably prevent gas leakage.
In addition, since the deformation of the cylinder head is made uniform when tightening the bolts, the function of the mechanism inside the head is improved, and noise is reduced and durability is improved.

[Brief description of drawings]

FIG. 1 is a plan view of essential parts showing a gasket of an embodiment according to the present invention.

2 is a cross-sectional view taken along the line AA of the gasket shown in FIG.

FIG. 3 is a sectional view taken along line BB of the gasket shown in FIG.

FIG. 4 is a graph showing the deformation of the gasket shown in FIG. 1 at positions A and B.

FIG. 5 is a cross-sectional view showing a model of the gasket of the embodiment.

6 is a graph of the surface pressure according to the position of the gasket shown in FIG. 5 with respect to a bolt.

7 is a graph of displacement of the gasket shown in FIG. 5 with respect to a bolt position.

FIG. 8 is a perspective view showing a gasket used in a conventional engine.

9 is a cross-sectional view showing the structure of the gasket shown in FIG.

10 is a graph showing the pressing force applied to the periphery of the cylinder bore hole of the gasket shown in FIG.

[Explanation of symbols]

 1 gasket. 2 Bore hole 3 Bolt hole 5 Bead

Claims (2)

[Claims] 1. A flat gasket interposed between a cylinder head and a cylinder block is bent at a constant height along a peripheral edge of a bore, and its width is increased at several positions on an axis symmetrically on the circumference. An engine gasket characterized by forming an annular bead. 2. The position where the width of the bead is maximized is a position corresponding to an intermediate portion between two adjacent bolt holes among a plurality of bolt holes provided on the peripheral edge of the bore. The engine gasket according to claim 1.