JPH06100285B2 - Cylinder / Head / Gasket - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cylinder head gasket interposed between a cylinder head and a cylinder block of an engine.

2. Description of the Related Art FIG. 6 shows a cylinder head gasket which has been widely used in the past. The gasket body 1 is composed of a relatively thin steel plate 3 having both sides punched with claws 2 and a relatively thick sheet-like compressive material 4 pressed onto both surfaces of the steel plate 3. It consists of a mixture of rubber and asbestos. A bore / grommet 6 for sealing the combustion gas in the cylinder of the engine is attached to a portion of the gasket body 1 around the cylinder hole 5 so as to sandwich the gasket body 1. In addition, a water hole 7 and an oil hole (not shown) in the gasket body 1
A liquid gasket 8 is applied to the peripheral portion of () (instead of applying the liquid gasket 8 in this way, a rubber ring may be fitted to the water hole 7 and the oil hole).

FIG. 7 shows another conventional cylinder head gasket, in which the gasket body 11 comprises a relatively thick steel plate 12 and a relatively thin compressible material composed of a mixture of compressible fibers such as asbestos and rubber on both sides. 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 a portion of the gasket body 11 around the cylinder hole 14. A bead 17 is provided around the water hole 15 and the oil hole in the gasket body 11.
Is provided, and this bead 17 projects to 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 speed, and this tendency has led to an increase in combustion pressure and an increase in thermal load. At the same time, in recent years, engines have tended to be lighter in weight, and this tendency has led to a reduction in the rigidity of the cylinder head and the cylinder block. For this reason,
The structural deformation of the cylinder head and the cylinder block due to the combustion pressure and the thermal deformation due to the thermal load are increasing more and more, and the cylinder head gasket is placed under extremely severe conditions. .

However, in the conventional cylinder head gasket shown in FIG. 6, (a) when a large stress acts on the mounting portion of the bore grommet 6, the compressible material 4 exceeds the compression elastic limit, so the bore grommet 6 The compression elastic limit will be exceeded for the entire mounting portion. As a result, the reduction of sealing stress,
It is easy to develop a sealing gap, expansion of gas, and eventually gas leakage and damage to the grommet 6.

(B) Due to a large thermal load, the compressive material 4 is liable to settle (creep) in the mounting portion of the bore / grommet 6, which also causes gas leakage.

(C) Since the water holes 7 and the periphery of the oil holes tend to be insufficiently sealed, the liquid gasket 8 was applied or the rubber ring was attached as described above. Takes time and reduces productivity. Further, when the liquid gasket 8 is applied, it is not always possible to obtain a satisfactory sealing effect.

(D) When the tightening force of the bolt is increased in order to sufficiently seal the periphery of the water hole 7 and the oil hole, an excessive load acts on the compressive material 4 in the peripheral portion of the bolt, and the compression elastic limit is increased. If it exceeds, the gasket body 1 will be destroyed.

There were various drawbacks such as.

On the other hand, in the conventional cylinder head gasket of FIG. 7, since the compressible material layer 13 is relatively thin and the main body of the gasket body 11 is the steel plate 12, a large stress is applied to the mounting portion of the bore grommet 16. It is possible to prevent the compression elastic limit from being exceeded even if it acts, and thus the sixth
Decrease in sealing stress, as in the case of the gasket in the figure,
There is also no increase in the sealing gap, no gas leakage, and no damage to the bore / grommet 16.

Further, as described above, since the thickness of the compressible material layer 13 is relatively thin and the main body of the gasket body 11 is the steel plate 12, compared with the gasket of FIG. I'm sorry

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

However, this conventional cylinder head gasket has the following problems.

(I) Generally, when the cylinder head gasket is mounted between the cylinder head and the cylinder block, the thickness during tightening is regulated in order to control the compression ratio in the cylinder. On the other hand, the compressive material layer 13 is naturally restricted to 0.2 mm or less on one side in consideration of the fatigue of the entire gasket. Therefore, in this type of cylinder head gasket, in general, the plate thickness of the steel plate 12 must be increased in order to obtain a required tightened thickness of the entire gasket. When the bead 17 is formed on the steel plate 12 having such a large plate thickness, the compressibility of the bead 17 portion becomes low.
As a result, in an engine such as a gasoline engine where the rigidity of the cylinder head and the cylinder block is weak, the surface pressure is distributed so that a stable seal stress can be obtained in the water hole 15 and the oil hole arranged on each part of the entire gasket surface. Is difficult.

(Ii) Since the compressive material layer 13 is interposed between the bore / grommet 16 and the steel plate 12, the heat dissipation of the bore / grommet 16 mounting portion is poor and the combustion chamber gas seal portion (bore / grommet mounting portion) The sag resistance is not sufficiently improved.

An object of the present invention is to provide a cylinder head gasket capable of maintaining stable seal stress in a bead portion formed in a water / oil seal portion and simultaneously maintaining stable seal stress in a combustion chamber gas seal portion. The purpose is to do.

Means for Solving the Problems A cylinder head gasket according to the present invention includes a core plate made of metal, a cylinder hole provided in the core plate, and a circumference of the cylinder hole on both sides of the core plate. Two surface plates respectively superposed on the excepted portion, a bore / grommet made of metal and attached to the portion of the core plate around the cylinder hole so as to sandwich the core plate from both sides, and the core plate. And a water hole and an oil hole penetrating the surface plate, and a bead portion that is provided around each of the water hole and the oil hole in each of the surface plates and that protrudes to the outer surface side of the surface plate. Each of the surface plates comprises a metal plate and both surfaces thereof covered with a thin compressible material layer made of a mixture of compressive fibers and an elastomer.

Action In the present invention, since the bore / grommet mounting portion (combustion chamber gas seal portion) can be entirely made of metal, even if excessive thermal deformation stress acts on the bore / grommet mounting portion, the compression elastic limit may be exceeded. Also, naturally, there is little sag and a high torque holding force can be obtained, so that stable and excellent gas sealing performance can be maintained.

Further, since the compressive material layer is not interposed in the bore / grommet mounting portion and heat is dissipated from the bore / grommet to the core plate only through the metal, the heat dissipation of the bore / grommet mounting portion is good, and from this point as well -The sag resistance of the grommet mounting part is improved.

Further, since the gasket body is configured by superposing the two surface plates on the core plate, the metal plate used for each surface plate can be made sufficiently thin. Since beads are formed on these thin metal plates, the bead portion (that is, water and oil seal portion) can have a relatively high compressibility, so that a stable and uniform surface pressure distribution state can be obtained. As a result, a stable seal stress can be maintained at the bead portion, and a water / oil seal can be maintained extremely well.

Also, parts other than water and oil seals (parts other than beads)
Also, since the compressive material layer is thin, the sag property is extremely small, and a high torque holding force is obtained as a whole.

Examples Hereinafter, the present invention will be described based on examples shown in the drawings.

The gasket body 21 is formed by stacking two surface plates 23 and 24 on both sides of a core plate 22 made of a steel plate. And
Each of the surface plates 23 and 24 is formed by coating a thin steel plate 23a on both sides with a thin compressible material layer 23b made of a mixture of ascompressible fibers such as asbestos and aramid fibers and an elastomer such as rubber. Similarly, the surface plate 24 is formed by coating both sides of a thin steel plate 24a with a thin compressible material layer 24b made of a mixture of compressible fibers such as asbestos and aramid fibers and an elastomer such as rubber.

The core plate 22 is provided with a cylinder hole 25, and in the portion around the cylinder hole 25, the surface plates 23 and 24 are not overlapped with the core plate 22. Then, two annular beads 26, 27 are formed in a portion of the core plate 22 around the cylinder hole 25 in a concentric shape with the cylinder hole 25 by press working. In addition, the cylinder hole of the core plate 22
Around the periphery of 25, a bore grommet 28 made of stainless steel is attached so as to sandwich the beads 26, 27.

Water holes 29 for passing cooling water, oil holes 30 for letting lubricating oil pass (see FIG. 2), and tightening bolts for inserting the core plate 22 and the surface plates 23, 24 Bolt holes 31 are provided. Water holes 2 of the surface plates 23, 24
As shown in FIG. 1, beads 32, 33 having an arcuate cross-section protruding outward are formed by pressing in the peripheral portion of 9 and the oil hole 30, and these beads 32, 22 are It surrounds the water hole 29 and the oil hole 30, respectively (note that
Although only the cross-sectional shape of the beads 32, 33 formed around the water hole 29 is shown in FIG. 1, the cross-sectional shape of the beads 32, 33 formed around the oil hole 30 has the same shape. Is). A bolt hole 34 is provided in the gasket body 21, and a grommet 35 is attached to the bolt hole 34 as shown in FIG.

With this cylinder head gasket,
The grommet 28 mounting part (combustion chamber gas seal part) consists of the core plate 22 and the bore grommet 28, and since they are all metal, even if excessive heat deformation stress acts on the boring grommet 28 mounting part, Does not exceed the compression resilience limit, thus reducing the sealing stress, expanding the sealing gap, as in the case of the conventional gasket of FIG.
As a result, gas leakage and damage to the bore / grommet 28 will not occur. And, of course, there is little sag and high torque holding power is obtained, so stable and excellent gas
The sealing performance can be maintained.

In addition, the compressive material layers 23b, 24
Since heat is dissipated directly from the bore / grommet 27 to the core plate 25 without b being interposed, the heat dissipated at the portion where the bore / grommet 28 is attached is good, and from this point as well Is improved.

Also, since the beads 32 and 33 are provided, the contact area with the cylinder head and the cylinder block is limited, so a small bolt tightening force can be applied to the water hole.
29, a sufficiently high contact pressure can be obtained around the oil hole 30.

Further, since the gasket body 21 is constructed by superposing the two surface plates 23, 24 on the core plate 22, the plate thickness of the steel plates 23a, 24a used for the surface plates 23, 24 can be made sufficiently thin. .
Since the beads 32 and 33 are formed on these thin steel plates 23a and 24a, respectively, these beads 32 and 33 portions (that is, water and oil seal portions) can have relatively high compressibility. A stable and uniform surface pressure distribution can be obtained, a stable seal stress can be maintained at the beads 32, 33, and water and oil sealing can be maintained extremely well.

Moreover, looking at the parts of the gasket body 21 other than the water and oil seals (the parts other than the beads 32 and 33),
Since the compressive material layers 23b and 24b are thin as described above, the sag property is extremely small, and a high torque holding force can be obtained as a whole.

Since the beads 32 and 33 can be formed by pressing, compared to the conventional case where a liquid gasket is applied around the water holes and oil holes or a rubber ring is attached, the cylinder head, The productivity of the gasket can be improved.

FIG. 4 shows another embodiment of the present invention. In this embodiment, only one bead 36 is provided on the portion of the core plate 22 around the cylinder hole 25. Other configurations are the same as those in the above-mentioned respective embodiments. Also in this embodiment, the same effect as that of the above embodiment can be obtained.

FIG. 5 shows still another embodiment of the present invention. An annular steel plate 37 is laminated on the core plate 22 around the cylinder hole 25, and the bore / grommet 28 includes the core plate 22 and the core plate 22. steel sheet
37 is sandwiched from both sides. Other configurations are the same as those in the above-mentioned respective embodiments. Also in this embodiment, it is possible to obtain the same effects as those of the above embodiments.

EFFECTS OF THE INVENTION As described above, the cylinder head gasket according to the present invention can maintain a stable seal stress in the bead portion formed in the water / oil hole seal portion, and also in the combustion chamber gasket portion at the same time. It is possible to obtain excellent effects such as maintaining the above.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the bore / grommet mounting portion and the vicinity of a water hole in one embodiment of the cylinder head gasket according to the present invention (the cross-sectional position is the line II in FIG. 2), and FIG. FIG. 3 is a plan view showing an example, FIG. 3 is a sectional view showing the vicinity of a bolt hole of the above embodiment, FIG. 4 is a sectional view showing a vicinity of a bore / grommet mounting portion and a water hole of another embodiment of the present invention,
FIG. 6 is a sectional view showing a bore / grommet mounting portion and the vicinity of a water hole of still another embodiment of the present invention, and FIG. 6 is a sectional view showing a bore / grommet mounting portion and the vicinity of a water hole of a conventional cylinder head gasket. FIG. 7 is a cross-sectional view showing the vicinity of a bore / grommet mounting portion and a water hole of another conventional cylinder head gasket. 21 ... Gasket body, 22 ... Core plate, 23, 24 ... Surface plate, 23a, 2
4a ... steel plate, 23b, 24b ... compressed material layer, 25 ... cylinder hole, 2
8 ... bore grommet, 29 ... water hole, 30 ... oil hole, 32,33 ... bead part.

Claims (1)

[Claims] 1. A core plate made of metal, a cylinder hole provided in the core plate, and two surface plates superposed on portions of both surfaces of the core plate excluding the periphery of the cylinder hole. , A bore / grommet made of metal, which is attached to the portion of the core plate around the cylinder hole so as to sandwich the core plate from both sides, and a water hole and an oil hole which are penetrated through the core plate and the surface plate. And provided around the water hole and the oil hole of each of the surface plates,
A bead portion protruding to the outer surface side of the surface plate,
Each of the surface plates is a cylinder head gasket in which both sides of a metal plate are coated with a thin compressible material layer made of a mixture of compressible fibers and an elastomer.