JPS62101873A - Cylinder head gasket - Google Patents

Abstract

PURPOSE:To obtain stabilized sealing stress by forming a main part of a gasket with two sheets of metallic plate covered with layers of compressible material and joined together, and providing the circumference of water holes and oil holes with bead parts and by providing the circumference of cylinder holes with bore grommets. CONSTITUTION:This gasket has a main part 21 formed by overlapping two sheet materials 22a and 22b. Each of the sheets 22a and 22b is formed with a thin steel sheet 23 with its both sides covered with a thin layer of compressible material consisting of, mixture of compressible fibers such as asbestos and alamide fiber and elastomer such as rubber. While the main part 21 of the gasket is provided with cylinder holes 25's, coolant holes 26's, lubricant holes 27's and bolt holes 31's, on the peripheries of the coolant holes 26's and lubricant holes 27's are press-formed beads 28 and 29 of arc-shaped cross section projecting toward outside. On the peripheries of the cylinder holes 25's are attached bore grommets 30's of stainless steel and U-shaped cross section.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a cylinder head gasket interposed between a cylinder head and a cylinder block of an engine.

BACKGROUND OF THE INVENTION FIG. 3 shows a cylinder head gasket that has been widely used in the past. The gasket 1 body 1 consists of a relatively thin steel plate 3 with nails 2 hammered on both sides, and a relatively thick compressible material 4 crimped onto both sides of the steel plate 3. Consists of a mixture of rubber and asbestos. and,
A bore grommet 6 for sealing combustion gas in the cylinder of the engine is attached to the peripheral edge of the cylinder hole 5 at the back of the cassette main body 1 so as to sandwich both sides of the peripheral edge. In addition, a liquid gasket 8 is applied around the water hole 7 and the oil hole (not shown) in the gasket body 1 (instead of applying the liquid gasket 8 in this way, 7 and a rubber ring may be fitted into the oil hole).

FIG. 4 shows another conventional cylinder head gasket, in which the gasket body 11 is made of a relatively thin compressible gasket made of a mixture of compressible fibers such as asbestos and rubber on both sides of a relatively thick steel plate 12. A material layer 13 is provided. The gasket body 11 is provided with a cylinder hole 14, a water hole 15, and an oil hole (not shown). A bore grommet 16 made of stainless steel is attached to the peripheral edge of the cylinder hole 14 of the gasket body 11.

A bead 17 is provided around the water hole 15 and the oil hole in the gasket body 11.
7 protrudes from one side of the gasket body 11.

Problems to be Solved by the Invention In recent years, engines have tended to have higher horsepower and higher rotation speeds, and this trend has resulted in increased combustion pressure and increased thermal load. At the same time, in recent years, there has been a trend toward lighter engines, and this trend has led to a decrease in the rigidity of cylinder heads (hereinafter simply referred to as heads) and cylinder blocks (hereinafter simply referred to as blocks). For this reason, structural deformation of the head and block due to combustion pressure and thermal deformation due to thermal load are increasing, and cylinder head gaskets are placed under extremely severe conditions.

However, in the conventional cylinder head gasket shown in FIG.
Since the compressible material 14 exceeds the compressive elastic limit, the grommet 6 mounting portion as a whole also exceeds the compressive elastic limit, as shown by curve A in FIG. As a result, the sealing stress decreases, the sealing gap widens, and gas leakage and grommet 6 breakage tend to occur.

(b) Due to a large thermal load, the grommet 6
At the mounting portion, the compressible material 4 tends to settle (creep), which also tends to cause gas leakage.

(c) Seal around the water hole 7 and oil hole tends to be insufficient, so as mentioned above, liquid gasket 8 was applied or rubber rings were attached, but these steps is time-consuming and reduces productivity. Furthermore, when applying the liquid gasket 8, it is not always possible to achieve a satisfactory sealing effect.

(d) In order to ensure a sufficient seal around the water hole 7 and the oil hole, if the bolt is tightened with a large force, an excessive load will be applied to the compressible material 4 around the bolt, causing its compressive elasticity to increase. The limit will be exceeded and the gasket body 1 will be destroyed.

There were various drawbacks such as.

On the other hand, in the conventional cylinder head gasket shown in FIG. 4, the compressible material layer 13 is relatively thin and the main body of the gasket body 11 is the steel plate 12, so a large stress is applied to the grommet 16 mounting portion. Therefore, as in the case of the gasket shown in FIG. I don't even invite you.

Furthermore, as described above, the thickness of the compressible material layer 13 is relatively thin and the gasket body 11 is mainly made of the steel plate 12, so that it does not easily collapse even when subjected to a large thermal load.

In addition, in this cylinder head gasket,
Because the bead 17 is provided, the contact area with the head and block is limited, so a small bolt can be tightened with force, and high contact pressure can be obtained around the water hole 15 and oil hole 15, and the water can be tightened with force. It also becomes possible to improve oil sealing properties.

However, this conventional cylinder head gasket often suffers from the following problems.

When a cylinder head gasket is installed between the head and the block, the thickness when tightened is regulated in order to control the compression ratio in the cylinder.The thickness when tightened is generally 1. In many cases, the thickness is set to about 2s to 1.5m, but when the tightening thickness is set to such a value, the thickness of the gasket body 11 is naturally set to about 1.2m to 1.2m.
．． 5# is required.

However, in the cylinder head gasket shown in FIG. 4, the compressible material layer 13 is naturally limited to about 0.2 m on one side in consideration of the fatigue of the gasket body. For this reason, 1. When the gasket body 11 has a thickness of 1.2#,
The steel plate 12 has a thickness of 0.8. I have no choice but to do the above. When the bead 17 is formed on the thick steel plate 12 in this way, the compression characteristic of the bead 17 portion is as shown by the curve B in FIG.
As shown in Figure 6, the compression ratio becomes lower (in Figure 6,
Compressive load indicates the load per 1 cm of bead). As a result, in engines with weak head and block rigidity, such as gasoline engines, it is difficult to create a blood pressure distribution that provides stable sealing stress in the water holes 15 and oil holes located throughout the gasket. Ta.

Purpose of the Invention The present invention provides a cylinder head gasket that is capable of maintaining stable sealing stress in the bead portion formed in the water and oil sealing portions, and at the same time maintaining stable sealing stress in the combustion chamber gas sealing portion. The purpose is to

Means for Solving the Problems The cylinder head gasket according to the present invention has a thin compressible gasket made of a mixture of compressible fibers such as asbestos or aramid fibers and an elastomer such as rubber on both sides of a metal plate such as a steel plate. A gasket body formed by overlapping a first plate material and a second plate material coated with a material layer, a cylinder hole, a water hole and an oil hole provided in the gasket 1 body, and the first plate material. and bead portions protruding toward the outer surfaces of the first plate material and the second plate material, respectively provided around the water hole and the oil hole of the second plate material;
A bore grommet made of metal such as stainless steel is attached to the peripheral edge of the cylinder hole of the gasket body so as to sandwich the first plate material and the second plate material from both sides. be.

In the present invention, the compressible material layer is thin and the main body of the gasket is made of two metal plates, so even if excessive thermal deformation stress is applied to the grommet attachment part, the compressive elasticity limit will not be exceeded. . In addition, as mentioned above, the compressible material layer is thin and the main body of the gasket is made of two metal plates, so it naturally has less tendency to sag and can maintain a high torque retention force of 1q, providing stable and excellent gas・Sealing performance can be maintained.

Furthermore, since the gasket body is constructed by overlapping the first plate material and the second plate material, the thickness of the metal plate used for each plate material can be made sufficiently thin. Since beads are formed on these thin metal plates, the bead parts (i.e., water and oil sealing parts) can have relatively high compressibility, so a stable and uniform blood pressure distribution state can be obtained. , maintains stable sealing stress at the bead, and prevents water,
Oil seal can be maintained extremely well.

Also, parts other than water and oil seal parts (parts other than beads)
Also, since the compressible material layer is thin, there is very little tendency for it to sag, and a high torque holding power can be obtained as a whole.

Example Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

1 and 2 illustrate one embodiment of the invention.

In this embodiment, the gasket body 21 is formed by stacking a first plate material 22a and a second plate material 22b on top of each other. Then, the first plate material 22a and the second plate material 2
2b is formed by coating both surfaces of a thin steel plate 23 with a thin compressible material layer 24 made of a mixture of compressible fibers such as asbestos or aramid I fiber and an elastomer such as rubber.

As shown in FIGS. 1 and 2, the gasket body 21 includes a cylinder hole 25, a water hole 26 for letting cooling water pass, an oil hole 27 for letting lubricating oil pass, and a bolt hole. 31 are provided. In addition, in the portions around the water hole 26 and the oil hole 27 of the first plate material 22a and the second plate material 22b, there are press-processed screws 28 and 29 having an arcuate cross section that protrudes outward. These beads 28 and 29 are respectively formed by water holes 2
6 and the oil hole 27 (although only the cross-sectional shape of the bead 2B formed around the water hole 26 is shown in FIG. 1, the bead 29 formed around the armhole 27 The cross-sectional shape of the bead 28 is also similar to that of the bead 28.

At the peripheral edge of the cylinder hole 25 of the gasket body 21, a bore grommet 30 made of stainless steel and having a U-shaped cross section is attached to the first plate member 22a and the second plate member 22b.
It is attached so that it is sandwiched from both sides.

Here, for example, if this gasket is required to be tightened to 1.2#, the thickness of the steel plate 23 should be set to 0.
4. , the thickness of each compressible material layer 24 is 0.1 m. In addition, in this case, the bore grommet 30 portion is pressurized and compressed, and the first plate material 22a and the second plate material 22b are
From the thickness of the combined gasket body 21, 0.1# to 0.
The thickness should be about 15M.

This cylinder head gasket has a layer of compressible material 24.
is thin, and the main body of the gasket body 21 is the two steel plates 23, so even if excessive thermal deformation stress is applied to the grommet 30 mounting portion, the compressive elastic limit is maintained as shown by curve C in FIG. Therefore, unlike the conventional gasket shown in FIG. 3, the sealing stress does not decrease, the sealing gap widens, and gas leakage and grommet 30 breakage do not occur.

In addition, since the main body of the gasket body 21 is made of two steel plates 23 and the compressible material layer 24 is thin, it naturally has less tendency to sag and can obtain high torque retention, resulting in a stable and excellent gas seal. performance can be maintained.

In addition, in this cylinder head gasket,
Because the beads 28 and 29 are provided, the contact area with the head and block is limited, so it is possible to tighten a small bolt with force, but it is not possible to obtain a sufficiently high contact pressure around the water hole 26 and sleeve hole 27. can.

Moreover, the curved line in FIG. 6 shows the compression characteristics of the bead 28 and 29 portions. As is clear from this curve, in this cylinder head gasket, beads 28 and 29 are formed on the thin steel plate 23, so the bead 28 and 29 portions (i.e., water and oil seal portions) are relatively Since high compressibility can be provided, a stable and uniform surface pressure distribution state can be obtained, stable sealing stress can be maintained at the bead 28 and 29 portions, and water and oil sealing can be maintained extremely well.

Moreover, even in the parts of the gasket 21 other than the water and oil seal parts (parts other than the beads 28 and 29), since the compressible material layer 24 is thin as described above, the tendency to set is extremely small, and the overall As a result, high torque holding power can be obtained.

In addition, since the beads 28 and 29 can be formed by press processing, compared to the conventional case where liquid gasket is applied around the water hole and sleeve hole or rubber rings are attached, it is possible to - Gasket productivity can be improved.

In addition, in the present invention, the steel plate 23 in the above embodiment
It is also possible to use other types of metal plates instead.

Further, as the material of the bore grommet 30, it is also possible to use a metal material other than stainless steel.

Effects of the Invention As described above, the cylinder head gasket according to the present invention can maintain stable sealing stress in the bead formed in the water and oil hole sealing parts, and also maintain stable sealing in the combustion chamber gas sealing part. This provides excellent effects such as being able to maintain stress.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing an embodiment of the cylinder head gasket according to the present invention (the cross-sectional position is taken from the line ■-■ in Fig. 2).
, FIG. 2 is a plan view showing the above embodiment, FIG. 3 is a sectional view showing a conventional cylinder head gasket, and FIG. 4 is a sectional view showing another conventional cylinder head gasket.
FIG. 5 is a characteristic diagram showing the relationship between compressive stress and compression ratio of the grommet attachment part in the case of the conventional cylinder head gasket shown in FIG. 3 and in the case of the example, and FIG. FIG. 3 is a characteristic diagram showing the relationship between compressive load and compressive strain of a bead portion in the case of a conventional cylinder head gasket and in the case of the above embodiment. 21... Gasket body, 22a... First plate material,
22b... second plate material, 23... steel plate, 24...
Compressible abrasive layer, 25... Cylinder hole, 26... Water hole, 27... Oil hole, 28.29... Bead portion, 30.
...boa grommet. Patent applicant Neesan Gasket Co., Ltd. Agent
Patent Attorney Izumi Omori Figure 5

Claims (1)

[Claims] A gasket body is formed by overlapping a first plate material and a second plate material, each of which is formed by coating both sides of a metal plate with a thin compressible material layer made of a mixture of compressible fibers and an elastomer; A cylinder hole, a water hole, and an oil hole provided, and the first plate material and the second plate material provided around the water hole and the oil hole of the first plate material and the second plate material, respectively. and a metal bore grommet attached to the peripheral edge of the cylinder hole of the gasket body so as to sandwich the first plate material and the second plate material from both sides. Cylinder head gasket.