JPH09292029A - Metal gasket for cylinder head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of permanent set to a bead for seal even when vibration of a cylinder head is exerted by a method wherein a substantially non-compressive and non-deformable protection protrusion having height lower than that of a bead for seal is formed outside a part positioned facing the outer peripheral edge of the gasket of the bead for seal. SOLUTION: A substantially non-compressive and non-deformable protection protrusion 9 protruding in the same direction as that of a bead 8 for seal having height h2 lower than the height h1 of a bead 8 for seal is formed around a liquid passage hole 4a, formed in the vicinity of the end parts in a longitudinal direction of a gasket G on which a specially high vibration load is exerted, and outside a part, positioned facing the outer peripheral edge of a gasket, togetherwith the bead 8 for seal. This constitution serves the protection protrusion 9 as a stopper part and prevents excessive fastening of the bead 8 for seal and limits the amplitude of expansion and contraction deformation of the bead 8 due to a repetition load, exerted on the bead 8 for seal due to vibration of the outer peripheral part of a cylinder head during operation of an engine, and prevents the occurrence of permanent set thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder head gasket of an engine for automobiles and the like.

[0002]

2. Description of the Related Art In a cylinder head gasket having liquid passage holes such as combustion chamber holes, water holes and oil holes and bolt holes, a sealing bead is provided around the combustion chamber holes and the liquid passage holes, and the combustion chamber holes are also provided. It is known to provide a stopper portion, such as a folded-back or shim plate, on the peripheral edge of the portion closer to the combustion chamber hole than the sealing bead.

With the operation of the engine, a large vibration is generated in the outer peripheral portion of the cylinder head, which causes a repeated load to act on the sealing bead around the liquid passage hole located in the outer peripheral portion of the cylinder head gasket, thereby causing the seal. Since there is a problem that the bead for use is easily settled, in order to prevent this, it is necessary to form a stopper part by providing a folded-back part on the outer peripheral edge of the gasket facing the sealing bead. No.

Also, for the same purpose, the sealing bead is partially surrounded by the bead for sealing around the liquid passage hole located on the outer peripheral portion of the gasket and is opposed to the outer peripheral edge of the gasket. The height of the gasket is high, and it is possible to provide a protective bead that gives a higher surface pressure than the sealing bead when the gasket is tightened between the joining surfaces of the cylinder head and the block. US Pat. No. 5,199,723
No. specification.

[0005]

In a cylinder head gasket in which a stopper portion by a folded portion is provided on the outer peripheral edge portion of the gasket facing the sealing bead, the folded portion is formed on the outer peripheral edge of the metal plate constituting the gasket. Since it is necessary to provide a projecting piece for doing so, there is a problem that the yield of the material when punching a metal plate from the material strip is reduced and the cost is increased. Also, the thickness (height) of the stopper
Is determined by the thickness of the metal plate, and the thickness of the stopper cannot be adjusted appropriately.

In the cylinder head gasket provided with the protective bead, the surface pressure of the protective bead is set to be larger than the surface pressure of the sealing bead, which adversely affects the sealing performance of the sealing bead. Further, there is a problem that the protective bead itself is apt to be settled due to the repeated load caused by the vibration.

An object of the present invention is to provide a novel protection means for the sealing bead around the liquid passage hole located near the outer peripheral edge of the gasket, and to eliminate the above problems and difficulties.

[0008]

SUMMARY OF THE INVENTION To achieve the above object, the present invention is a metal for a cylinder head, which is made of an elastic metal plate and is provided with combustion chamber holes, water holes, liquid passage holes such as oil holes, and bolt holes. In the gasket, a sealing bead surrounding the liquid passage hole is provided around at least one liquid passage hole located near the outer peripheral edge of the gasket, and extends outside the portion of the sealing bead that faces the outer peripheral edge of the gasket. However, the height of the protective bead is lower than that of the sealing bead, and the protective bead is substantially incompressible and non-deformable.

As described above, the metal gasket for a cylinder head of the present invention has a height outside the portion of the sealing bead around the liquid passage hole located near the outer peripheral edge of the gasket facing the outer peripheral edge of the gasket. Since the protective bead is lower than the sealing bead and is substantially incompressible and non-deformable, the protective bead serves as a stopper to tighten the gasket between the joining surfaces of the cylinder head and the cylinder block. At this time, the sealing bead is prevented from being excessively tightened, and the amplitude of expansion / contraction deformation of the sealing bead due to the repeated load applied to the sealing bead due to the vibration of the outer peripheral portion of the cylinder head during engine operation is suppressed. It is possible to limit and prevent the bead for sealing from getting settled.

The height of the protective bead which acts as described above and protects the sealing bead around the liquid passage hole located on the outer peripheral portion of the gasket is preferably 0.05 to 0.2 m.
m, and the difference between the height of the sealing bead and the height of the sealing bead is preferably 0.1 to 0.15 mm when the sealing bead is a stepped bead. When the bead comprises a bead having a convex cross section, it is preferably selected to be in the range of 0.03 to 0.05 mm.

The protective ridge in the present invention includes, as will be described later, a hard ridge formed by curing a ridge of a liquid coating material such as an epoxy resin applied by screen printing on a metal plate, and a metal plate. There are two types, a ridge formed by filling a hard synthetic resin layer such as an epoxy resin layer into the internal space portion, that is, the recessed portion of the embossed bead that is integrally provided with the stopper. There is no problem of deterioration of material yield as in the case of providing parts,
The height of the protrusion, that is, the height of the stopper portion can be adjusted as appropriate, and the protective protrusion itself does not become depressed and the sealing performance of the sealing bead is not adversely affected.
That is, according to the present invention, the problems and difficulties in the above-mentioned conventional sealing bead protecting means are eliminated.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Details and embodiments of a metal gasket for a cylinder head of the present invention will be described below with reference to the drawings. 1 is a plan view of the right half of the gasket of the first embodiment of the present invention, and FIG. 2 is an enlarged sectional view taken along the line AA of FIG. FIG. 3 is an enlarged sectional view similar to FIG. 2 of the gasket of the second embodiment of the present invention, and FIG. 4 is an enlarged sectional view similar to FIG. 2 of the third embodiment of the present invention. The same reference numerals indicate the same parts.

1 and 2, a metal gasket G according to the present invention comprises a metal plate 1 having elasticity such as a stainless steel plate, a plurality of combustion chamber holes 3 having a shape matching the combustion chamber of the engine, and engine cooling water. A liquid passage hole 4 such as a water hole and an oil hole that communicates with the passage and the lubricating oil passage, and a bolt hole 5 for inserting a bolt that fastens the cylinder head and the cylinder block are provided. A bead 7 is provided around the combustion chamber hole 3 to concentrically surround and seal the combustion chamber hole 3.
If necessary, a stopper portion (not shown) such as a folded-back portion is provided on the combustion chamber hole side of the bead 7. In FIG. 1, in order to simplify the drawing, the bead 7 is represented by a chain line showing the apex thereof.

Around the liquid passage hole 4, there is provided a sealing bead 8 which surrounds the liquid passage hole 4 and has a convex cross section such as a mountain shape or a semicircular shape. In FIG. 1, the bead 8 is represented by a dotted line showing its apex. In the liquid passage hole 4, the liquid passage hole located near the outer peripheral portion of the gasket G, that is, in the vicinity of the outer peripheral edge 6 of the gasket G is indicated by the reference numeral 4a. Around the liquid passage hole 4a located near both ends in the longitudinal direction of the gasket that receives a large vibration load, the bead 8 for sealing is provided on the outside of the portion 8a of the bead 8 facing the outer peripheral edge 6 of the gasket. It is provided with a protection ridge 9 which projects in the same direction as the bead and has a height h ₂ lower than the height h ₁ of the sealing bead and which is substantially incompressible and non-deformable.

The protective ridge 9 serves as a stopper portion to prevent the sealing bead 8 from being excessively tightened when the gasket G is tightened between the joint surfaces of the cylinder head and the cylinder block, and also to prevent the engine from running. The bead 8 for sealing is accompanied by the vibration of the outer peripheral portion of the cylinder head during operation.
The amplitude of expansion / contraction deformation of the bead 8 due to the repeated load that acts on the bead 8 is limited to prevent the bead 8 from settling. Protective ridge 9
1 may extend in an arc shape along a portion 8a of the sealing bead 8 facing the gasket outer peripheral edge 6 as shown in FIG. 1, or may be formed outside the sealing bead portion 8a. It may be extended in a straight line in parallel with, or both ends of the linear protection ridge may be bent and extended inward. The point is that the portion of the sealing bead 8 facing the outer peripheral edge of the gasket may be extended so as to be effectively protected.

Protective ridge 9 in the first embodiment of the present invention
Is a non-compressible, non-compressible material that does not deform and is not substantially deformed even when a compressive force is applied by curing the ridges of a liquid coating material applied on a metal plate by screen printing or the like by heat drying or heat curing. It is deformable and has a rectangular cross section. The cross-sectional shape of the protective ridge 9 is not limited to a rectangular shape, but may be trapezoidal, chevron-shaped, semicircular, or the like.
It is preferable that the protective ridge 9 has a cross-sectional shape having a flat top portion so that the top portion is not deformed when repeatedly subjected to a compressive load. An epoxy resin is preferably used as the liquid coating material. The width w of the ridge is preferably 0.
In the range of 5 to 2.0 mm, the height h ₂ of the ridges is preferably selected in the range of 0.05 to 0.2 mm, and the sealing bead having a convex cross section (height is usually 0.1 to 0. The height is preferably 0.03 to 0.05 mm lower than the height h _{1 of} 25 mm). Since the protective ridge 9 of the first embodiment can be formed by screen printing or the like as described above, the degree of freedom in setting the installation position of the ridge, the height of the ridge, the width, etc. is large, and adjustment is possible. Also has the advantage of being easy.

In the second embodiment shown in FIG. 3, the protective ridge 9'is provided with the sealing bead 8 having a convex cross-section and the metal plate 1.
The embossed bead 10 having a chevron cross section formed in the above and a substantially incompressible and non-deformable hard synthetic resin layer 12 such as an epoxy resin layer filled in the recessed portion on the back side of the protrusion of the bead, that is, the internal space portion 11. Has been formed. The cross-sectional shape of the embossed bead 10 is not limited to the illustrated mountain shape, but may be an appropriate shape such as a trapezoid. Embossed bead 10
Selected height h _'2 is preferably the difference between h ₁ -h 0.05 to 0.2 mm, the height h ₁ of the sealing bead 8' is preferably ₂ to 0.03 to 0.05mm Be done.
The hard synthetic resin layer 12 is filled so as to substantially fill the internal space of the bead 10. Since the protective ridge 9'in the second embodiment is constructed as described above, there is no risk of the protective ridge 9'being deformed even after the gasket has been used for a long time. The sealing bead 8 in the first and second embodiments may be a stepped bead described later, instead of the bead having a convex cross section shown in the drawing.

FIG. 1 shows an example in which the protective ridge 9 is provided on the outer side of the sealing bead only in the liquid passage holes 4a located on the outer peripheral portion of the gasket G, which are located on both ends in the longitudinal direction of the gasket. However, as mentioned above, the sealing bead around the liquid passage hole located on the outer peripheral portion of the gasket is subject to repeated load due to the vibration of the cylinder head caused by the operation of the engine, and tends to cause fatigue. All liquid passage holes 4 located on the outer periphery of the gasket.
A protective ridge 9 or 9'may be provided around the a together with the sealing bead 8, and what range of the protective ridge 9 or 9'may be provided in the liquid passage hole 4a on the outer peripheral portion of the gasket. It can be freely selected depending on the gasket design.

The present invention can also be applied to a laminated metal gasket, and a third embodiment constructed as a laminated gasket is shown in FIG. In the third embodiment, a metal plate 1 having a step bead 8'which surrounds and seals the liquid passage hole 4a as a bead for sealing, and a liquid coating on the outside of the portion of the step bead 8'which faces the outer peripheral edge of the gasket. A metal plate 2 provided with a protective ridge 9 having a rectangular cross section formed by curing a material is laminated so that the protective ridge 9 faces the metal plate 1. Height h of the step bead 8 ′ around the liquid passage hole
₄ is usually in the range of 0.25 to 0.35 mm, and the difference h ₃ -h _{4 from} the height h ₃ of the step bead is preferably 0.1.
To 0.15 mm.

In FIG. 5 showing a modification of the third embodiment, the protective ridge 9 is provided on the metal plate 1 and protrudes in the same direction as the step bead 8 '. The protective ridges 9 provided on the metal plate 1 or the metal plate 2 can be replaced with protective ridges 9'made of embossed beads filled with a hard synthetic resin layer as shown in FIG. The sealing bead around the liquid passage hole 4a may be a chevron bead as shown in FIGS. Although the third embodiment shown in FIG. 4 shows the simplest two-layer structure as the laminated gasket, it is possible to form the laminated gaskets of various structures by applying the well-known laminated constitution technique for the cylinder head gasket.

In each of the embodiments described above,
For simplification of the drawings and the description, the sealing material layer made of heat-resistant rubber or the like which is usually coated on the metal plate in the metal gasket is not shown in the drawings and the description is omitted. A sealing material layer may be coated around the combustion chamber holes and liquid passage holes of the plate or over the entire surface of the metal plate, in which case the sealing material layer may or may not also cover the protective ridges. It does not matter which method is used.

[0022]

As has been described in detail above, according to the present invention, a protrusion in the same direction as the sealing bead is formed on the outer side of the portion of the sealing bead located around the outer peripheral portion of the gasket facing the outer peripheral edge of the gasket. However, since the height of the protective bead is lower than that of the sealing bead, and the protective bead is substantially incompressible and non-deformable, when the gasket is assembled between the joint surfaces of the cylinder head and the cylinder block, the protective bead is Functions as a stopper to protect the sealing bead, and the sealing bead does not become depressed even when the cylinder head is vibrated. Further, according to the present invention, since the material yield is not deteriorated due to the provision of such a stopper portion, there is an advantage that the height of the protective ridge that is the stopper portion can be arbitrarily set and adjusted, and the protective ridge is It is possible to eliminate the problems and difficulties in the conventional technique without causing the settling and without adversely affecting the sealing performance of the sealing bead.

[Brief description of drawings]

FIG. 1 is a plan view of a right half portion of a gasket according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line AA of FIG.

FIG. 3 is an enlarged cross-sectional view similar to FIG. 2 of the gasket of the second embodiment of the present invention.

FIG. 4 is an enlarged sectional view similar to FIG. 2 of a gasket of a third embodiment of the present invention.

FIG. 5 is a sectional view similar to FIG. 4, showing a modification of the third embodiment of the present invention.

[Explanation of symbols]

 4 and 4a Liquid passage hole 8 Sealing bead 9 and 9'Protective ridge

Claims (7)

[Claims] 1. A metal gasket for a cylinder head, which is made of an elastic metal plate and has a liquid passage hole such as a combustion chamber hole, a water hole and an oil hole, and a bolt hole, at least located near the outer peripheral edge of the gasket. A sealing bead that surrounds the liquid passage hole is provided around one liquid passage hole, and the sealing bead extends outside the portion of the sealing bead that faces the outer peripheral edge of the gasket. A metal gasket for a cylinder head, characterized in that it is provided with a protective ridge that is substantially lower than the above and is substantially incompressible and non-deformable. 2. The metal gasket for a cylinder head according to claim 1, wherein the protective ridge is a hard ridge formed by curing a liquid coating material applied on a metal plate. 3. The metal gasket for a cylinder head according to claim 2, wherein the hard ridge is made of epoxy resin. 4. The metal gasket for a cylinder head according to claim 1, wherein the protective ridge comprises an embossed bead provided on a metal plate and a hard synthetic resin filled in an internal space of the bead. 5. The metal gasket for a cylinder head according to claim 1, wherein the protective ridge has a flat top in cross-sectional shape. 6. The cylinder head metal according to claim 1, wherein the sealing bead is a stepped bead, and a difference in height between the sealing bead and the protective ridge is within a range of 0.1 to 0.15 mm. gasket. 7. The cylinder according to claim 1, wherein the sealing bead is a bead having a convex cross-section, and a difference in height between the sealing bead and the protective ridge is within a range of 0.03 to 0.05 mm. Metal gasket for head.