JPH051730Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a cylinder head gasket disposed between a cylinder head and a cylinder block of an internal combustion engine, and in particular to a gasket having a single metal plate structure.

BACKGROUND TECHNOLOGY As a cylinder head gasket made of a metal plate, a so-called metal gasket, one having a single-plate structure composed of a single thin metal plate having beads is already known, and this is disclosed in, for example, Japanese Patent Application Laid-open No. 1983-1996. It is shown in Publication No. 255253.

The metal gasket has a spring bead with a semicircular cross section around the opening of the combustion chamber, and the bead is elastically deformed when a fastening force is applied from a bolt that fastens the cylinder head and the cylinder block. Due to the restoring force caused by the elastic deformation of this bead, it comes into close contact with the joint surfaces of the cylinder head and cylinder block, thereby performing a sealing action on the combustion chamber.

Problems to be solved by the invention Metal gaskets used as cylinder head gaskets are generally made of spring steel plates, stainless steel plates, etc. with a thickness of about 0.2 to 0.4 mm, and the height of the bead provided on this steel plate is The larger the bead, the greater the elastic deformation of the bead during fastening, producing a greater restoring force, that is, sealing force. However, in general, from the viewpoint of formability, it is best to obtain a bead height of about 0.2 to 0.3 mm, and the bead Since the bead is partially plastically deformed when fastened, the effective height of the bead is extremely small, and therefore a single gasket cannot provide sufficient sealing force, limiting the range of internal combustion engines to which it can be applied.

In addition, as internal combustion engines become smaller and lighter, the rigidity of the cylinder head tends to decrease, and if the cylinder head is not sufficiently rigid, the cylinder head will suffer local compressive deformation around the bolts when it is fastened to the cylinder block with bolts. The gasket floats up and deforms in the direction away from the gasket around the combustion chamber, and as a result, the gasket bead is not sufficiently elastically deformed.
A single gasket is insufficient to seal the high-pressure combustion gas in the combustion chamber, and several gaskets must be used in combination to obtain sufficient sealing performance.

The present invention provides an improved metal cylinder head gasket that can obtain sufficient sealing performance even with a single gasket and can reliably avoid leakage of high-pressure combustion gas in the combustion chamber. The purpose is to

Means for Solving the Problems According to the present invention, in a metal cylinder head gasket having an annular bead around the combustion chamber opening, bolt holes are directed toward the combustion chamber opening. This is achieved by a metal cylinder head gasket such as that enlarged.

Effects and effects of the invention According to the above-described structure, the gasket is missing on the combustion chamber opening side of the bolt that fastens the cylinder head and cylinder block to each other, and the cylinder head in this area is partially damaged. Compressive deformation is avoided, and since the tightening force of the bolt acts on the gasket from the peripheral edge of the bolt through hole, the position of the bolt tightening force acting on the gasket shifts to the side closer to the combustion chamber opening,
As a result, sufficient surface pressure acts on the bead around the opening of the combustion chamber, causing the bead to undergo sufficient elastic deformation in the compression direction, and from this elastic deformation, even a single gasket can form a sufficient seal. power is available and ensures that leakage of high-pressure combustion gases in the combustion chamber is avoided.

Embodiments Hereinafter, the present invention will be described in detail with reference to embodiments with reference to the accompanying drawings.

1 and 2 show one embodiment of a metal cylinder head gasket according to the present invention. In the figure, 10 indicates a cylinder head gasket, and the cylinder head gasket 10 is
It is made of a stainless steel plate with a thickness of about 0.2 to 0.4 mm or a steel plate with appropriate spring properties, such as a spring steel plate, and includes a combustion chamber opening 12, a cooling water passage opening 14, and a lubricating oil passage opening 16. , bolt through holes 18a and 18b are provided, respectively. A bead 20 having a smooth planar shape and a semicircular cross section is formed concentrically around the combustion chamber opening 12 by pressing or the like.

The bolt through holes 18a are provided at the four corners of the gasket 10, whereas the bolt through holes 18b are provided on both sides between the adjacent combustion chamber openings 12, and are each enlarged into a long hole shape toward the combustion chamber opening 12. ing. The direction of expansion of the bolt through holes 18a and 18b is from the center of the bolt through hole to the adjacent combustion chamber opening 1.
2, and the so-called end bolt holes 18a located at the four corners of the gasket 10 have a waterdrop-shaped opening shape because the enlarged portion 22 thereof becomes narrower toward the combustion chamber opening 12. is doing. The enlarged portion 24 of the so-called intermediate bolt hole 18b located on the side between the combustion chamber openings is bifurcated so as to extend toward the center of each of the two adjacent combustion chamber openings 12.

A gap A between the tip of the enlarged portion 24 of the intermediate bolt hole 18b and the bead 20 is smaller than a gap B between the tip of the enlarged portion 22 of the end bolt hole 18a and the bead 20. That is, the enlarged portion 24 of the intermediate bolt through hole 18 is connected to the end bolt through hole 18.
It is larger than the enlarged part 22 of.

FIG. 2 shows the gasket 10 shown in FIG. 1 installed between a cylinder head H and a cylinder block B. As shown in FIG. The cylinder head H and the cylinder block B are fastened together with the gasket 10 sandwiched therebetween by fastening bolts 30 provided through bolt holes 18a and 18b of the gasket 10. The fastening force by the fastening bolt 30 acts on the gasket 10, thereby causing the bead 2
0 is elastically deformed in the compression direction while being sandwiched between the cylinder head H and the cylinder block B, and the repulsive force generates a sealing force. gasket 10
The fastening bolt 30 is tightened by the enlarged portion 22 or 24.
The side of the combustion chamber opening 12 is cut out, thereby preventing the cylinder head H from being locally compressed and deformed in this area. The bolt tightening force acts on the gasket 4 from the peripheral edge E of the enlarged portions 22 and 24 of 18a and 18b, and the position where the bolt fastening force acts on the gasket 4 is located close to the bead 20, and the relative height of the bead 20 is increased. Due to the defects, sufficient surface pressure acts on the bead 20, and the bead 20 is sufficiently elastically deformed in the compression direction, and from this elastic deformation, a sufficient seal is formed. You will gain power.

Assuming that the fastening force of the fastening bolt 30 passed through the bolt through holes 18a and 18b is the same at each part, the fastening bolt passed through the end bolt through hole 18 and the fastening bolt passed through the intermediate bolt through hole 18b. In this case, the loads for tightening the beads 20 of the gasket 10 are different from each other, and the force for tightening the beads 20 between the combustion chambers becomes weaker. In view of this, in order to make the tightening force acting on the bead 20 uniform at each part, the enlarged portions 22 of the bolt holes 18a, 18b,
24 are different in size from each other, and the gap A is set smaller than the gap B. This compensates for the fastening force. Incidentally, an adjusting shim 26 having a predetermined thickness for compensating the tightening force may be further disposed in the enlarged portion 22 or 24.

As mentioned above, the tightening force acting on the bead 20 of the gasket 10 can be freely modified by the size of the enlarged portion 22 or 24 and the thickness of the adjustment shim 26 disposed on the enlarged portion 22 or 24. With these settings, the bead 20
It becomes possible to appropriately adjust the tightening force acting on each part, thereby making it possible to obtain the required sealing performance.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited thereto, and various embodiments are possible within the scope of the present invention. It will be clear to those skilled in the art.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing one embodiment of the metal cylinder head gasket according to the present invention, and Fig. 2 is an enlarged longitudinal section showing the installed state of the metal cylinder head gasket according to the invention shown in Fig. 1. The plan view and FIG. 3 are enlarged vertical sectional views showing another embodiment of the metal cylinder head gasket according to the present invention in its installed state. 10... Cylinder head gasket, 12...
Combustion chamber opening, 14...Cooling water passage opening, 16...
...Lubricating oil passage opening, 18a... End bolt through hole, 18b... Intermediate bolt through hole, 20... Bead, 22, 24... Enlarged portion, 26... Adjustment shim, 30... Fastening bolt.

Claims (1)

[Scope of utility model registration request] A metal cylinder head gasket having an annular bead around a combustion chamber opening, characterized in that a bolt through hole is enlarged toward the combustion chamber opening.