JPH11210889A - Cylinder head gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide excellent sealing performance even when a casting void, a flaw or the like exists in a mating joining face, particularly to provide high bearing pressure in a thick wall part to result in excellent sealing performance by bringing a full bead part into pressure contact with a mating member at high bearing pressure by a spacer. SOLUTION: This cylinder gasket 1 is provided with two sheets of gasket base plates 3 having combustion chamber holes 3A, and a spacer 4 surrounding endlessly a cylinder bore 2 and nipped by the gasket base plates 3. A full bead part 3a and, if necessary, a half bead part 3b are formed in each gasket base plate 3 within a range overlapped with the spacer 4, and are sandwiched continuously along the circumfrential direction of the cylinder bore 2 between a cylinder head 5 and a cylinder block 6. A thick wall part 4a thicker than the outer circumferential side of the spacer 4 is provided in the inner circumferential side of the spacer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an engine cylinder head gasket.

[0002]

2. Description of the Related Art Conventionally, as a cylinder head gasket, two gasket substrates sandwiched between a cylinder head and a cylinder block and having a combustion chamber hole formed in accordance with a cylinder bore are arranged around the cylinder bore. There is a known type that includes a spacer that surrounds this endlessly and that is sandwiched between the two gasket substrates, and a full bead portion or a half bead portion provided at an appropriate position on the gasket substrate (actually). JP-A-4-71865, JP-A-4-165167).

[0003]

Conventionally, when only a gasket substrate having a full bead portion and a half bead portion is arranged, if there is a burrow or a flaw in the joint surface of the cylinder block or the cylinder head, the influence is easily affected. There is a danger that the sealing performance will be reduced. The present invention has been made in view of such circumstances, and provides a cylinder head gasket capable of always obtaining good sealing performance even if there is a cavity or a flaw on a mating joint surface.

[0004]

That is, the present invention provides two gasket substrates sandwiched between a cylinder head and a cylinder block and having a combustion chamber hole formed in accordance with a cylinder bore, and having a periphery of the cylinder bore. A spacer disposed endlessly around the gasket substrate, and a spacer sandwiched between the two gasket substrates, and a full bead provided on each of the two gasket substrates within a range where the spacer overlaps with the spacer. The spacer and the full bead portion of each gasket substrate are continuously sandwiched between the cylinder head and the cylinder block along the circumferential direction of the cylinder bore, and are further thicker on the inner circumferential side of the spacer than on the outer circumferential side. A thick portion is provided.

[0005]

According to the above construction, the full bead portion of each gasket substrate provided around the combustion chamber hole is sandwiched between the cylinder head and the cylinder block, and at the same time a spacer is provided in that portion. The part can be pressed against the mating material with a high surface pressure and with a relatively large contact area. As a result, even if there is a cavity or a flaw on the mating surface of the mating member, it is less likely to be affected by such a cavity and a good sealing performance can be secured. In addition, since the thicker portion that is thicker than the outer circumferential side is provided on the inner circumferential side of the spacer, the sealing performance with respect to the combustion chamber hole can be further ensured.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a cylinder head gasket for an in-line four-cylinder engine will be described below. 1 to 3, a cylinder head gasket 1 includes two gasket substrates 3 each having four combustion chamber holes 3A drilled in accordance with a cylinder bore 2 (see FIG. 1). And a spacer 4 interposed therebetween and held therebetween. The spacer 4 is arranged around each cylinder bore 2 and surrounds it endlessly. However, in the illustrated embodiment, the interval between the cylinder bores 2 and therefore the interval between each combustion chamber hole 3A is narrow. Therefore, the four spacers 4 are mutually connected between the adjacent combustion chamber holes 3A to be integrally formed. When the space between the combustion chamber holes 3A is wide, it is needless to say that the four spacers 4 may be formed separately. In each of the gasket substrates 3, a full bead portion 3a and a half bead portion 3b surrounding each combustion chamber hole 3A are formed so as to protrude toward the spacer 4 within a range where the gasket substrate 3 overlaps with the spacer 4. And full bead portion 3a and half bead portion 3
and b are formed in that order from the center side of each combustion chamber to the outside. The spacer 4 is provided with a thicker portion 4a thicker than the outer circumferential side by folding back the inner circumferential side, that is, the portion on the combustion chamber side. It is formed on the inner peripheral side of the full bead portion 3a so as not to polymerize on the full bead portion 3a. In the present embodiment, the thick portion 4a is formed continuously in the circumferential direction and has a uniform thickness in the circumferential direction. Each of the gasket substrates 3 is, for example, 0.20 mm thick S
US301-H can be used.
It is preferable to coat with an R layer. As the spacer 4, for example, SUS304 having a thickness of 0.08 mm can be used. The thickness and material of the gasket substrate 3 can be appropriately selected depending on the model of the engine to which the gasket substrate 3 is applied.

As shown in FIG. 1, the cylinder head gasket 1 is interposed between a cylinder head 5 and a cylinder block 6 of an engine, and integrally connects the cylinder head 5 and the cylinder block 6 by fastening bolts 7. As a result, they are sandwiched between them to seal between them. At this time, the spacer 4, the full bead portion 3 a and the half bead portion 3 b of each gasket substrate 3 are combined with the cylinder head 5 and the cylinder block 6.
And the half bead portion 3b whose circumferential continuity is interrupted or located outside, in the circumferential direction of the cylinder bore 2.
Of the cooling water passages 5a and 6a formed on the joint surface of the cylinder head 5 and the cylinder block 6 so as not to make it impossible to sandwich the portion. The cylinder head 5 and the cylinder block 6
In the embodiment shown in the drawings, the cooling water passage 5 is formed as an open deck block made of aluminum die casting.
The cylinder heads 5 and the cylinder blocks 6a and 6a are provided outside the half bead portion 3b, which is the outermost, so as to integrally surround the four combustion chamber holes 3A.
Respectively formed on the joint surface with the substrate.

According to the above configuration, the periphery of each combustion chamber hole 3A can be endlessly surrounded by the full bead portion 3a and the half bead portion 3b, and the portion where the full bead portion 3a and the half bead portion 3b are provided is provided. Since the spacer 4 is provided, the full bead portion 3a and the half bead portion 3
b can be pressed against the cylinder head 5 and the cylinder block 6 with a high surface pressure and a relatively large contact area. As a result, even if there are cavities or scratches on the joint surface between the cylinder head 5 and the cylinder block 6, the effects are less likely to be caused by such cavities or scratches, and good sealing performance can always be ensured. In addition, since the thick portion 4a is provided on the inner peripheral side of the spacer 4, the surface pressure on each combustion chamber hole 3A side can be further increased, and the sealing performance of that portion can be further improved. it can. In the present embodiment, the thick portion 4
Since a serves as a bead stopper for preventing the full bead portion 3a from being excessively crushed, the crack resistance of the full bead portion 3a can be improved.

FIG. 4 shows a second embodiment of the present invention. In this embodiment, a full bead portion 3a and a half bead portion 3b formed on each gasket substrate 3 are respectively opposite to the first embodiment. It is formed so as to protrude from the spacer 4. The thick portion 4a formed on the spacer 4
Are formed so as to surround the upper and lower surfaces of the combustion chamber hole 3A of one gasket substrate 3. Other configurations are first
The configuration is the same as that of the embodiment.
The same operation and effect as the embodiment can be obtained.

FIG. 5 shows a third embodiment of the present invention. In this embodiment, the half bead portion 3 of the first embodiment is used.
b is omitted. In the first embodiment, the thick portion is formed by folding back the inner peripheral portion of the spacer 4, whereas in the present embodiment, a shim is welded to the inner peripheral side of the spacer 4. The thick part 4a is formed. Other configurations are the same as those of the first embodiment.
Depending on the type of engine, sufficient sealing performance can be obtained even if the half bead portion 3b is omitted as in this embodiment.

In each of the above embodiments, the projecting direction of the full bead portion 3a and the half bead portion 3b is
Are formed symmetrically with respect to the center, but the present invention is not limited to this and can be an appropriate combination. Further, the thick portion formed by folding back the first embodiment may be applied to the third embodiment, or the thick portion formed by the shim of the third embodiment may be applied to the first embodiment or the second embodiment. Of course. Further, in each of the above embodiments, the thick portion 4a
Although the thickness is made uniform in the circumferential direction, the surface pressure is large near the fastening bolt 7 and the surface pressure is small near the fastening bolt 7. The thickness of the thick portion 4a can be reduced, and the thickness of the thick portion 4a can be increased in a distant portion, so that the circumferential surface pressure can be set as uniform as possible. in this case,
The thickness of the thick portion in the circumferential direction may be changed by partially forming the thick portion in the circumferential direction of the cylinder bore. In this case, in particular, in this case, the gasket substrate 3
Such a thick portion can be formed by partially turning back a part of the. Further, as shown in FIGS. 6 to 8, a plurality of spacers 4 may be provided.

[0012]

As described above, according to the present invention, even if there are cavities or scratches on the mating surface of the mating part, it is hard to be affected by such cavities or scratches, so that good sealing performance can be ensured. In addition, the thick portion formed on the inner peripheral side of the spacer can provide an effect that the sealing performance can be further ensured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a plan view of the cylinder head gasket 1 of FIG.

FIG. 3 is an enlarged view of a main part of FIG. 1;

FIG. 4 is a schematic sectional view showing a second embodiment of the present invention.

FIG. 5 is a schematic sectional view showing a third embodiment of the present invention.

FIG. 6 is a schematic sectional view showing a fourth embodiment of the present invention.

FIG. 7 is a schematic sectional view showing a fifth embodiment of the present invention.

FIG. 8 is a schematic sectional view showing a sixth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cylinder head gasket 2 ... Cylinder bore 3 ... Gasket board 3A ... Combustion chamber hole 3a ... Full bead part 3b ... Half bead part 4 ... Spacer 4a ... Thick part 5 ... Cylinder head 6 ... Cylinder block 5a, 6a ... Cooling water passage

Claims (8)

[Claims] 1. A gasket substrate sandwiched between a cylinder head and a cylinder block and having a combustion chamber hole drilled in accordance with a cylinder bore, disposed around the cylinder bore and surrounding it endlessly. And the above 2
A spacer sandwiched between the gasket substrates, and a full bead provided on each of the two gasket substrates within a range where the spacer overlaps with the spacer. The spacer and the full bead of each gasket substrate are provided with the cylinder head and Between the cylinder block
A cylinder head gasket characterized by being continuously sandwiched along a circumferential direction of a cylinder bore, and further provided with a thicker portion on the inner circumferential side of the spacer than on the outer circumferential side. 2. A half bead portion is provided on each of the two gasket substrates within a range overlapping with the spacer, and each half bead portion is provided between the cylinder head and the cylinder block in a circumferential direction of a cylinder bore. The cylinder head gasket according to claim 1, wherein the cylinder head gasket is continuously held along the cylinder. 3. The cylinder head gasket according to claim 1, wherein the thick portion is formed by folding an inner peripheral portion of the spacer toward an outer peripheral side. 4. The cylinder head gasket according to claim 1, wherein the thick portion is formed by welding a shim to an inner peripheral side portion of the spacer. 5. The cylinder head gasket according to claim 1, wherein the thickness of the thick portion is different in a circumferential direction of the cylinder bore. 6. The cylinder head gasket according to claim 1, wherein the thick portion is formed partially in a circumferential direction of the cylinder bore. 7. The cylinder head gasket according to claim 1, wherein the thick portion is formed continuously along a circumferential direction of the cylinder bore. 8. At least one of the cylinder head and the cylinder block is formed as an open deck having a cooling water passage surrounding the spacer and a full bead portion and a half bead portion of each gasket substrate. The cylinder head gasket according to any one of claims 1 to 7, wherein