JPH089489Y2 - Composite gasket for cylinder head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of use) The present invention relates to a cylinder head gasket mounted between the joint surfaces of a cylinder head and a cylinder block of an engine.

(Prior art) A heat resistant compound mainly composed of expanded graphite or a heat resistant compound mainly composed of heat resistant high elastic fiber and heat resistant filler such as heat resistant rubber is coated on both sides of a metal core material layer such as an iron plate with a hook. A cylinder head gasket made of a soft material gasket provided with a heat-resistant compound layer and having a metal grommet on the periphery of the cylinder bore has been in practical use for a long time.

Further, the cylinder bore, which is made of an elastic metal plate,
Metal plate gaskets for cylinder heads, in which a bead for enclosing and sealing a seal portion around a seal portion such as an oil hole or a water hole is provided, have already been put into practical use. As a metal plate gasket for a cylinder head, a laminated metal gasket in which a plurality of metal plates are laminated is usually used. Various cross-sectional shapes (for example, arc-shaped cross section) are used for the shape of the bead surrounding the seal portion.
There are uneven beads and step beads composed of inclined surfaces,
Any one of the above beads or a bead formed by appropriately combining these is formed on an elastic metal plate such as a stainless plate.

Furthermore, a soft material gasket (having no core material layer) made of the heat resistant compound as described above is provided on both sides of the metal plate having the above-described bead-like deformed portion around the cylinder bore, oil hole, water hole, or the like. A combination laminated gasket in which a soft material gasket coated with the above-mentioned heat resistant compound is laminated on both sides of the core material layer is a Japanese Patent Publication No.
Already known from No. 1326.

(Problems to be solved by the invention) In the cylinder head gasket made of the soft material gasket having the metal grommet described above, since the metal grommet on the peripheral edge of the cylinder bore increases the thickness of the gasket on the peripheral edge of the cylinder bore, the gasket is used as a cylinder head. When mounted on a cylinder block and fastened with bolts, a large load is applied to the grommet portion at the peripheral edge of the cylinder bore, and a large surface pressure is generated at the portion as a reaction force. Therefore, leakage of high-pressure gas can be prevented. However, on the other hand, the load applied to the periphery of the water hole and the oil hole becomes relatively small, and the surface pressure of the gasket that seals around the water hole and the oil hole becomes small, which makes it difficult to seal water and oil. There is also a risk of water and oil leakage due to displacement of the cylinder head joint surface due to explosion internal pressure while the engine is being driven, and fluctuation of surface pressure due to deformation of the joint surface due to vibration or thermal strain. For this reason, the sealing force is often supplemented by attaching eyelets or rubber rings to the water holes and oil holes and applying a seal compound around the water holes and oil holes, but this is not always satisfactory.

On the other hand, in the cylinder head gasket composed of the above-mentioned laminated metal gasket, by appropriately selecting the thickness of the metal plate, the shape of the bead, etc., the spring constant of the bead that surrounds and seals the water hole and the oil hole, the restoration amount, etc. Since it can be set appropriately, the water hole and the oil hole can be advantageously and appropriately sealed. However, regarding the sealing of high-pressure gas in the cylinder bore, the bead surrounding the cylinder bore alone is insufficient in surface pressure around the cylinder bore when the bolt is fastened, which makes it difficult to seal the high-pressure gas. For this reason, a stopper formed by shim or folding back of a metal plate is provided on the inside of the bead, that is, on the cylinder bore side to increase the surface pressure around the cylinder bore. However, these rigid stoppers are small in elastic compression amount and restoration amount, and it is difficult to follow the displacement of the cylinder head joint surface as described above.

SUMMARY OF THE INVENTION The present invention provides a cylinder head gasket having excellent sealing performance that is free from all the problems around the cylinder bore, the water hole, and the oil hole in view of the above-mentioned drawbacks of the conventional cylinder head gaskets. The purpose is to do.

(Means for Solving the Problem) The composite gasket for a cylinder head of the present invention is a soft gasket base material in which a heat-resistant compound layer is coated on both sides of a metal core material layer such as an iron plate with a hook to form oil holes and water on one side or both sides. An elastic metal plate provided with a stepped bead formed of an inclined surface surrounding the hole is laminated, and a metal grommet is provided on the periphery of the cylinder bore of the soft gasket base material.

(Example) Hereinafter, an example of the composite gasket for a cylinder head of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a partially cutaway plan view of the gasket of the present invention, and FIGS. 2 and 3 are sectional views taken along the lines AA and BB of FIG. Reference numeral 1 denotes a soft gasket base material, which is a heat-resistant compound layer 3 mainly composed of expanded graphite on both sides of a metal core material layer 2 such as an iron plate with a hook, or a heat-resistant highly elastic fiber such as aramid fiber and a butadiene-acrylonitrile mixture. The heat-resistant compound layer 3 is mainly composed of a heat-resistant filler such as polymer rubber. Reference numeral 4 is an elastic metal plate laminated on one side of the soft gasket base material 1. The soft gasket base material 1 and the elastic metal plate 4 have the same shapes as the joint surfaces of the cylinder head and the cylinder block, respectively, and are provided with a cylinder bore 6, an oil hole 7, a water hole 8 and a bolt hole 9. A metal grommet 5 is provided on the periphery of the cylinder bore 6 of the soft gasket base material 1, and step beads 10, 11, and 12 formed of inclined surfaces around the cylinder bore 6, oil hole 7, and water hole 8 of the elastic metal plate 4. Are formed so as to surround each hole. 13 is a soft gasket base material 1 to facilitate handling of the gasket.
And the elastic metal plate 4 are integrally connected to each other. a and b show the top and the base of the inclined surface of each step bead.

When the gasket of the present invention having the above-described structure is mounted between the joint surface of the cylinder head and the joint surface of the cylinder block so that the elastic metal plate 4 side is in contact with the joint surface of the cylinder head and bolted, the periphery of the cylinder bore is Due to the added thickness of the metal grommet 5, a large load is applied, and a large surface pressure sufficient to seal the high pressure gas in the cylinder bore is generated. In addition, the apex a of the inclined surface of the step beads 10, 11, and 12 formed on the elastic metal plate 4
And the base b is pressed against the joint surface of the cylinder head to generate a relatively large surface pressure, and the surface pressure of the base b is transmitted to the soft gasket base material 1 to apply a relatively large surface pressure to the corresponding portion of the soft gasket base material. Give rise to.

4 to 7 are cross-sectional views showing other different embodiments, and show cross-sectional views corresponding to the cross-sectional view taken along the line AA of FIG.

In the embodiment shown in FIG. 4, the metal grommet 5 is provided so as to cover the peripheral edge of the cylinder bore in which the soft gasket base material 1 and the elastic metal plate 4 are laminated in close contact, and the elastic metal plate 4 has The difference from the case of the embodiment shown in FIG. 2 is that the step beads surrounding the cylinder bore 6 are not provided. In the embodiment shown in FIG. 5, a metal wire ring 14 having an outer diameter substantially equal to the thickness of the soft gasket base material is provided inside a metal grommet 5 that covers the cylinder bore periphery of the soft gasket base material and the elastic metal plate. There is. The edge of the cylinder bore portion of the elastic metal plate 4 is extended to above the wire ring 14, and the metal grommet 5 is applied to cover the extended edge portion. Metal wiring
When the gasket is mounted on the joint surface and is tightened with a bolt, 14 can generate a higher surface pressure on the metal grommet portion which is in direct contact with the wiring or through the extended edge of the elastic metal plate. The metal wire rings mounted in the metal grommet may be two metal wire rings arranged in parallel. Further, such metal wiring can be applied to the embodiment of FIG. 2 and the embodiments of FIGS. 6 and 7 described later.

The embodiment shown in FIG. 6 differs from the embodiment shown in FIG. 4 in that a step bead 1 in which an elastic metal plate surrounds a cylinder bore is used.
The numbers 0 and 10 are duplicated. FIG. 7 shows an embodiment in which elastic metal plates provided with step beads 10, 10, 11 and 12, not shown, are laminated on both sides of the soft gasket base material 1. Therefore, in this case, the top portion a and the base portion b of the stepped bead are pressed by the joining surfaces on the cylinder head side and the cylinder bore side, respectively, and a relatively large surface pressure is generated on the pressed top portion a and the base portion b.

In each of the above-described embodiments, the elastic metal plate 4 provided on one side or both sides of the soft gasket base material 1 is a single elastic metal plate. However, a laminated metal plate in which a plurality of elastic metal plates are laminated as required. Can also be used. Further, the elastic metal plate does not have to extend to the peripheral edge of the cylinder bore. However, in this case, it is necessary to consider the thickness adjustment such as inserting an adjustment plate so that the thickness of the gasket around the cylinder bore is not reduced and the function of the metal grommet provided on the peripheral edge of the cylinder bore is not impaired. is there.
As the metal core material layer of the soft gasket base material, in addition to the iron plate with hooks described above, a wire mesh woven of metal wires can be used. This metal core material layer is indispensable in order to provide the soft gasket base material with appropriate compression resistance and restoration property.

(Operation and effect of the invention) As described above, the composite gasket for a cylinder head of the present invention has oil holes and water holes on one side or both sides of a soft gasket base material in which both surfaces of a metal core material layer are coated with a heat-resistant compound layer. Since the elastic metal plates provided with stepped beads composed of inclined surfaces are laminated around the metal gasket grommets on the soft gasket base material or on the soft gasket base material and the elastic metal plate at the peripheral edge of the cylinder bore, the metal rim is attached to the peripheral edge of the cylinder bore. The thickness of the grommet is added, and due to this thickness addition effect, a large load is applied to the peripheral edge of the cylinder bore when the gasket is mounted between the joint surfaces and the bolts are tightened.
It creates a high enough surface pressure to seal the high pressure in the cylinder bore.

Further, the top and the base of the stepped bead, which is formed by the oil hole formed in the elastic metal plate and the inclined surface surrounding the water hole, are pressed by the joint surface when bolted to generate a relatively large surface pressure. Moreover, the spring constant of the bead can be appropriately selected by appropriately selecting the plate thickness of the elastic metal plate, the width and height of the bead, etc., so that the relatively large surface pressure can be used for sealing low pressure oil holes and water holes. It is easy to adjust to a suitable surface pressure, and in the gasket of the present invention, oil holes and water holes can be effectively sealed. Further, the stepped bead composed of the inclined surface has a large elastic recovery amount even compared with the uneven bead, and has a good followability with respect to the displacement of the joint surface such as the cylinder head, and the displacement of the joint surface occurs as described below. There is an advantage that the reduction of the surface pressure is small.

FIG. 8 shows the metal gasket grommet part (curve B) around the cylinder bore of the soft gasket base material, which is the constituent part of the gasket of the present invention, the soft gasket base material without the grommet (curve B) and the step bead of the elastic metal plate. FIG. 6 is a characteristic diagram showing a relationship between a load and a strain when the portions (curve c) are sandwiched between joint surfaces and tightened with bolts. In the cylinder head gasket, a large load equal to or more than the load E is applied in order to obtain a surface pressure sufficient to prevent gas leakage around the cylinder bore that seals high-pressure gas. On the other hand, since the pressure inside the water and oil holes is low, the surface pressure to prevent water and oil leaks is relatively small. The applied load is small compared to the load applied around the cylinder bore, and a relatively low load is imposed, such as between the load and load in the figure.

In the high load area required around the cylinder bore, the grommet coating on the peripheral edge of the soft gasket substrate bore is
The distortion characteristic curve is relatively gentle as shown by the curve a. This tendency is not only when the metal grommet covers not only the cylinder bore peripheral edge of the soft gasket base material but also the cylinder bore peripheral edge of the elastic metal plate,
Essentially unchanged. Therefore, even if the joint surface of the cylinder head is displaced due to lifting of the cylinder head due to the internal pressure of the explosion in the combustion chamber during operation of the engine or deformation of the cylinder head due to thermal stress and the strain changes by ΔH, the change in load due to this ΔW ₁ is relatively small. That is, even if the displacement of the joint surface as described above occurs, the load that can generate the surface pressure of a sufficient magnitude to prevent the leakage of the high pressure gas is maintained. Further, when a bead is provided around the cylinder bore of the elastic metal plate 4 as shown in FIGS. 2 and 6, the elastic restoring amount of this bead is added to the series in the soft gasket base material. , Can better follow the displacement of the joint surface. Incidentally, the load-strain characteristic curve of the bead portion of the elastic metal plate is steep in the high load region required around the cylinder bore as shown by the curve C, and the load-strain characteristic curve of the load when the strain changes by ΔH. The change ΔW ₂ is extremely large. This tendency is essentially the same even in a laminated metal gasket in which elastic metal plates having beads are laminated, and also when a stopper such as a shim or a metal plate is folded inside the beads.

On the other hand, in the load region around the water holes and oil holes, the load-strain characteristic curve of the soft gasket base material alone is relatively gradual, and the load fluctuation ΔW ₄ value itself with respect to the strain change Δh due to the displacement of the joint surface Is relatively small, but the load applied to the soft gasket base material is small, so that the relative variation value with respect to the load is large, and water and oil leaks easily occur. On the other hand, the load-strain characteristic curve in the load region of the step bead of the elastic metal plate is extremely gentle,
The variation in load ΔW _{3 with} respect to Δh is smaller than in the case of the soft gasket base material, and the relative variation value with respect to the applied load is also sufficiently small. In the composite gasket of the present invention,
Since the above-mentioned stepped beads of the elastic metal plate around the water and oil holes are added in series to the soft material gasket base material, even if the above-mentioned displacement of the joint surface occurs, there is little change in the surface pressure. , Maintain sufficient surface pressure to prevent oil leaks.

Since the composite gasket for a cylinder head of the present invention is as described above, the following significant effects can be achieved.

A cylinder with excellent sealing performance that eliminates the drawbacks of conventional cylinder head gaskets made of soft material gaskets and cylinder head gaskets made of metal gaskets by combining them, and has no difficulties at all around the cylinder bore, water holes, and oil holes. A head gasket can be obtained.

Around the cylinder bore, the high surface pressure required to seal high-pressure gas can be secured by the thickness effect of the metal grommet, and the surface pressure does not decrease even when the strain changes due to displacement of the joint surface. Since it is possible to follow the lift of the cylinder head due to combustion pressure,
Leakage of combustion gas can be prevented.

Further, by providing a bead around the cylinder bore of the elastic metal plate, it is possible to further improve the followability to a large displacement of the joint surface.

Around the water holes and oil holes, the step bead of the elastic metal plate is laminated on the soft gasket base material because the load-strain identification curve in the load region is extremely gentle and the fluctuation of the load with respect to the displacement of the joint surface is extremely small. Therefore, it is possible to keep a sufficient surface pressure to prevent water and oil leaks and follow a large displacement of the joint surface well.

Incidentally, a combination laminated gasket obtained by laminating soft material gaskets on both sides of a metal plate having a bead-like deformed portion known from the above-mentioned Japanese Patent Publication No. 49-1326,
Since there is a soft material on both sides of the metal plate, it basically has the same characteristics as the conventional soft material gasket, and cannot exert the action and effect as in the present invention.

[Brief description of drawings]

FIG. 1 is a partially cutaway plan view of an embodiment of the gasket of the present invention, and FIGS. 2 and 3 are sectional views taken along the lines AA and BB of FIG. 4 to 7 are sectional views showing other different embodiments. FIG. 8 is a characteristic diagram showing the load-strain characteristics of the constituent parts of the present invention. (Explanation of reference numerals) 1: Soft gasket base material, 2: Metal core material layer, 3: Heat resistant compound layer, 4: Elastic metal plate, 5: Metal grommet, 6: Cylinder bore, 7: Oil hole, 8: Water hole, 10, 11 and 12: Step beads, 1
4: Metal wiring

Claims (3)

[Scope of utility model registration request] 1. An elastic metal in which a stepped bead composed of an inclined surface is provided around an oil hole or a water hole on at least one side of a soft gasket base material in which both surfaces of a core material layer such as an iron plate with a hook are coated with a heat resistant compound layer. A composite gasket for a cylinder head, characterized by stacking plates and providing a metal grommet around the cylinder bore of a soft gasket base material. 2. The composite gasket for a cylinder head according to claim 1, wherein the elastic metal plate is also provided with beads around the cylinder bore. 3. The cylinder head according to claim 1, wherein the metal grommet provided on the peripheral edge of the cylinder bore of the soft gasket base material also covers the peripheral edge of the cylinder bore of the elastic metal plate. Composite gasket for.