JPH085321Y2 - Bead of metal gasket - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a structure of a seal bead of a metal gasket for a cylinder head of an engine.

[Conventional technology]

The metal gasket has a loop-shaped bead that surrounds the hole to be sealed and bulges a thin metal plate on one side.
It is well known that it usually has a shape in which a plurality of plates are laminated. When this metal gasket is used as a cylinder head gasket to be mounted between the cylinder head and the cylinder body of the engine, as is well known,
It is usually necessary to provide a plurality of holes such as cooling water holes, lubricating oil holes, push rod holes, and the like, in addition to the bolt holes through which the cylinder bore and the head bolt are inserted, on a single metal plate.

[Problems to be solved by the device]

The head bolts are arranged so that the beads that seal the cylinder bores are tightened most efficiently. Therefore, the other holes are not necessarily arranged so that the tightening force is evenly obtained. Therefore, with the bead provided in the hole that opens in the part where the tightening force becomes uneven between the near and far parts of the bolt hole, tightening will be completed before the bead is completely crushed (compressed) when tightening the bolt. There is a danger of being lost.

In such a case, there is a problem that the elastic force of the bead is weakened by load fluctuation due to vibration and heat load during engine operation, the bead is crushed and the bolt tightening force is reduced, and the sealing performance is deteriorated.

The present invention was made by focusing on the above problems,
In metal gaskets for engine cylinder heads,
Regarding the sealing performance of the hole provided on the peripheral side of the corner of the gasket, the tightening force becomes uneven because the position of the head bolt is unevenly distributed with respect to the hole. An object of the present invention is to provide a cylinder head gasket provided with a bead having a structure that prevents deterioration of the sealing performance when the engine is used for a long period of time.

[Means for solving the problem]

The metal gasket bead of the present invention for achieving the above object is a hole opened outside the bolt hole provided around the combustion chamber hole of the cylinder head gasket of the engine and at the corner side of the gasket. A bead for sealing the hole, surrounding the periphery of the hole, narrowing the width of the bead on the side farther than the bead on the side close to the bolt hole,
Moreover, the bead height is formed to be substantially equal to or less than the height on the near side, and the spring force on the side closer to the bolt hole is made weaker than the spring force on the far side.

[Action]

When the height of the bead provided around the hole that opens around the corner of the gasket on the side far from the outer bolt hole is made higher than the height of the inner bead on the side close to the bolt hole, when compressing the bead In addition, the force of pushing up the tip end side of the corner portion of the cylinder head, which becomes weaker in rigidity, acts from the beginning of tightening, and the corner portion of the cylinder head may warp during long-term use. Therefore, when the elastic force of the bead due to vibration or heat is weakened, the sealing performance on the side farther from the bolt hole from the outside of the bead may be reduced. However, the bead of the present invention having the above-described configuration, the bead height on the side far from the outer bolt hole is set to be substantially the same as the height on the side close to the bolt hole in the bead hole, or less than that. It acts to avoid the above problems.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings according to an embodiment.

First, the overall structure of the metal gasket of this embodiment will be described with reference to the partial plan view shown in FIG. The cylinder head gasket 1 is provided with a cylinder bore Hc, a bolt hole Hb, a cooling water hole Hw, a lubricating oil hole Ho, and a push rod hole Hp at predetermined positions. The dashed line in the figure indicates the bead position.

The cylinder head gasket 1 is usually formed by laminating metal plates for various purposes, such as a surface plate, a bead plate, a thickness adjusting plate, and a compression height adjusting plate, and usually one surface plate on the hole side to be sealed. With the structure of a normal metal laminated gasket, such as folding back on one side to prevent the laminated part from being exposed on the hole side for sealing, and providing a grommet to prevent leakage of the fluid that seals between laminated plates. You can do it, or use only one bead plate,
It may also be simply laminated.

As shown in FIG. 1, the bead plate 2 of this embodiment has a bead 4 and a lubricating oil hole Ho provided around the cylinder bore Hc.
The beads 6 provided around the respective are provided.

As shown in FIG. 3, the cylinder bore Hc is provided with bolt holes Hb around the periphery at substantially equal intervals, so that the bead 4 has a uniform thickness. Further, in the present embodiment, the bead is not provided in the push rod hole Hp, but naturally the present invention can be applied to this portion if necessary. In this case, when the plurality of bolt holes Hb are approaching, a plurality of portions weakens the spring force.

On the other hand, the bead 6 provided in the lubricating oil hole Ho is most strongly affected by the tightening from the bolt hole Hb shown in FIG. Therefore, as shown in FIG. ₁ , the bead width d ₁ on the side a near the bolt hole Hb is widest and the height h ₁ is the highest.
The bead width d ₂ on the distant side b was formed to be the smallest and the height h ₂ was formed to be the smallest (d ₁ > d ₂ , h ₁ > h ₂ ).

When the bead 6 has an arc-shaped cross section, the bead 6 on the side a closer to the bolt hole Hb has a smaller curvature 1 / r ₁ and the bead 6 on the side b farther from the bolt hole Hb has a curvature 1 / r ₂ Adjust the spring force by increasing (1 / r ₁ <1 / r ₂ ).
As described above, the means for changing the spring force of the bead can be realized not only by changing the width or the curvature, but also by simply widening the width, changing the bead height, or a combination thereof.

Next, the operation of the cylinder head gasket 1 of this embodiment will be described in the case of FIG. With regard to the bead 6, the portion a where the tightening force from the bolt hole Hb acts strongly even if the bead has the same plate thickness, is more easily compressed than the portion b where the force becomes weaker. , B
Side will be more influential. By the way, as can be seen from FIG. 1, the width of the cylinder head is much lower in rigidity on the b side than on the a side in FIG. However, in this embodiment, the b-side bead height h ₂ is slightly lower than the a-side height h ₁ of the bead 6. Therefore, even in the case of an engine with a low material strength, such as an aluminum alloy cylinder head, for example, the tightening force consumed for the corner portion of the cylinder head, that is, the warp on the side b in FIG. Reduce.

Therefore, even if the bead 6 materially sags due to future load fluctuation or heat load, it is possible to prevent a risk that the bead 6 is crushed and the tightening force of the bolt is decreased to deteriorate the sealing performance.

[Effect of device]

Since the bead of the metal gasket of the present invention is configured as described above, the bead arranged at the corner where the rigidity of the cylinder head is reduced does not push up the tip of the corner and warp the cylinder head. Since the positions are unevenly distributed, the bead can be compressed more evenly with an uneven tightening force, and the sealing performance is maintained even if the tightening force is reduced due to deterioration of elastic force due to engine vibration and heat. You can

[Brief description of drawings]

FIG. 1 is a plan view of an essential part of a bead plate according to an embodiment, FIG. 2 is a sectional view of an essential part of FIG. 1, and FIG. 3 is a partial plan view of a metal gasket of the embodiment of FIG. 1 ... metal gasket, 2 ... bead plate, 6 a bead, Hb ... bolt hole, Ho ... lubricant hole, r _1, r ₂ ... bead radius.

Claims (1)

[Scope of utility model registration request] 1. A bead for sealing a hole, the hole being provided outside a bolt hole provided around a combustion chamber hole of a cylinder head casket of an engine and at a corner side of the gasket, and sealing the hole. Surround the periphery of the hole, narrower the bead on the far side than the bead on the side closer to the bolt hole,
A bead of a metal gasket having a bead height substantially equal to or less than the height on the near side, and a spring force on the side closer to the bolt hole is weaker than a spring force on the far side.