JPH10196790A - Cylinder head gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a local surface pressure so as to improve the effect of preventing the leakage of combustion gas by setting the folding width of a portion positioned in both end sides of the width and longitudinal directions of a gasket and separated from a bolt hole to be larger than that of the other portion in a cylinder head gasket having a folded part in the peripheral end of a cylinder bore. SOLUTION: A cylinder head gasket G is constructed by laminating an elastic metal plate 1 and a thin metal plate 2, the metal plate 2 has a folded part 5 formed by folding the metal plate 2 of the peripheral end part of a cylinder bore 3, and the metal plate 1 has a bead 6 surrounding the cylinder bore 3 in a position outside more than the folded part 5. In this case, regarding the folding width of the folded part 5, the folding width of a portion 5b positioned in both end sides of the longitudinal direction of the gasket G and separated from a bolt hole 4 is set wider than that of a portion 5d close to the bolt hole 4. Sealing material layers 71 to 73 are provided so as to cover the entire part where the folded part 5 is positioned in the gasket part having the narrow portion 5d located therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal gasket used as a cylinder head gasket for an engine.

[0002]

2. Description of the Related Art In a metal gasket for a cylinder head gasket, a gasket is formed of at least two metal plates, and a stopper portion is formed by providing a folded portion of the metal plate around the periphery of a cylinder bore of one metal plate. It is already well known and practical to form a bead surrounding the cylinder bore in another metal plate at a position outside the folded portion.

Further, in such a metal plate gasket for a cylinder head gasket, one or both of a metal plate surface abutting on a bonding surface of a cylinder head or a cylinder block and a metal plate surface abutting on each other have a bonding surface or a metal plate. It is also well known to cover a sealing material layer made of rubber, synthetic resin, or the like as a microseal that compensates for irregularities such as surface scratches and roughness of the sealing material layer. Is formed so as to cover the entire surface.

[0004]

When the metal gasket for a cylinder head is mounted between the cylinder head and the cylinder block and fastened by bolts, the cylinder head and the cylinder block are vertically or vertically perpendicular to the cylinder head and the cylinder block. Because it bends slightly in the width direction so that the center of the lower surface of the cylinder head is concave downward, and the center of the upper surface of the cylinder block is depressed upward,
Leakage of combustion gas in the cylinder bore tends to occur from the peripheral edges of the cylinder bores at both ends in the longitudinal direction and from the peripheral edges of the cylinder bores at both ends in the width direction. For this reason, the folded width of the folded portion is reduced at the portion where leakage is likely to occur, that is, at the peripheral portions at both ends in the gasket longitudinal direction of the cylinder bore and at the peripheral portions at both ends in the gasket width direction of the cylinder bore and separated from the bolt holes. It may be larger than the turn width of the other part of the turn part.

[0005] However, the portion where the folded width of the folded portion is widened has a larger pressure receiving area for the clamping force than the other portions of the folded portion, and the clamping force is dispersed. Therefore, only the wide folded portion is provided. Then, there is a regret that the improvement effect of the prevention of the leak of the combustion gas is not enough.

The present invention has been made in view of the above points, and the present invention increases the local surface pressure without increasing the pressure receiving area of the tightening force in a portion where the folded width of the folded portion at the periphery of the cylinder bore is increased. It is an object of the present invention to improve the effect of preventing combustion gas leakage in a cylinder bore.

[0007]

SUMMARY OF THE INVENTION The present invention, which achieves the above object, comprises at least one metal plate having a cylinder bore and a bolt hole, and has a folded portion formed by folding the metal plate around the periphery of the cylinder bore. In a cylinder head gasket provided with a bead surrounding a cylinder bore at a position outside the turn-up portion, a portion located at both widthwise ends and / or both ends in a longitudinal direction of the gasket in the turn-up portion and separated from the bolt hole is provided. In the gasket portion where the wide folded portion is located, at least one layer of the sealing material layer coated on the surface of the metal plate has a folded width larger than the folded width of the other portion. Only the portion located on the outer peripheral side is covered.

In the gasket of the present invention, at the portions located at both ends in the gasket width direction and / or both ends in the longitudinal direction as described above and separated from the bolt hole, the folded width of the folded portion at the peripheral edge of the cylinder bore is set to the other portion. Although the width is wider than the folded width, at least one of the sealing material layers made of rubber, synthetic resin, or the like coated on the surface of the metal plate constituting the gasket has an outer periphery of the folded portion in the gasket portion where the wide folded portion is located. Only the part located on the side is covered.

Therefore, in the gasket portion where the wide folded portion is located, the thickness of the gasket is reduced by that amount in the inner peripheral portion where at least one layer of the sealing material layer is not covered, and the gasket is connected to the cylinder head and the cylinder block. When tightening is performed, the inner peripheral side portion is not substantially subjected to the tightening force, and the tightening force is concentrated on the outer peripheral side portion covered with the sealing material layer, and the pressure receiving area of the tightening force is reduced. As a result, a high sealing surface pressure is generated in the outer peripheral portion. This high sealing surface pressure, combined with the widening effect of increasing the folded width of the folded portion, effectively prevents the leakage of the combustion gas in the cylinder bore and enhances the sealing performance of the gasket.

In the present invention, the reason why at least one of the sealing material layers is covered with the sealing material layer only on the outer peripheral side, not on the inner peripheral side, of the portion where the wide folded portion is located is as follows.
If the seal material layer is coated only on the inner peripheral side, sufficient surface pressure may not be obtained due to the influence of the bending of the cylinder head and the cylinder block. This is to ensure that a high surface pressure is obtained in the covering portion. It is preferable that the covering width of the sealing material layer covering only the outer peripheral side is substantially equal to the folded width of the folded portion other than the wide folded portion, so that a high surface pressure portion having a width substantially equal to the entire periphery of the cylinder bore is formed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings of embodiments. FIG. 1 is a plan view of a cylinder head gasket according to an embodiment of the present invention. For simplicity and simplicity of the drawing, only a cylinder bore and a bolt hole, and a folded portion and a bead around the cylinder bore are illustrated. The illustration of the passage holes and the beads surrounding them is omitted. FIG. 2 is an enlarged sectional view taken along line AA of FIG. 1, and FIG. 3 is an enlarged sectional view taken along line BB of FIG. The same reference numerals indicate the same parts.

In the figure, a cylinder head gasket G
Is an elastic metal plate 1 having a thickness of 0.2 to 0.3 mm such as a stainless steel plate, and a metal plate 2 having a thickness of 0.1 to 0.15 mm such as a stainless steel plate or an iron plate.
The metal plate 2 is provided with a folded portion 5 formed by folding the metal plate of the peripheral portion of the cylinder bore 3 by 180 degrees on the periphery of the cylinder bore 3, and the metal plate 1 is located at a position outside the folded portion 5. A ridge-shaped bead 6 surrounding the cylinder bore is provided. The folded portion 5 of the metal plate 2 is folded toward the metal plate 1, and the bead 6 of the metal plate 1 projects toward the metal plate 2. Reference numeral 4 in the figure denotes a bolt hole through which a fastening bolt is inserted.

The folded width of the folded portion 5 is not uniform at each part around the cylinder bore 3, and the folded width of each portion of the folded portion varies depending on its position. That is, the folded width is narrowed (for example, 1.0 to 1.5 mm) in the portion 5 d close to the bolt hole 4, located at both ends in the width direction of the gasket (vertical direction of the gasket in FIG. 1), and separated from the bolt hole 4. The folded width is widened (for example, 2.0 to 2.5 mm) in the portion 5a and the portion 5b located at both ends in the longitudinal direction of the gasket (the left and right direction of the gasket in FIG. 1) and separated from the bolt hole 4. ,
In the portion 5c located between the cylinder bores, the turning width is selected to be an intermediate width between the wide turning width of the portions 5a and 5b and the narrow turning width of the portion 5d.

The deflection of the cylinder head and the cylinder block caused when the cylinder head is bolted to the cylinder block with the cylinder head interposed between the cylinder head and the cylinder block depends on the design of the engine. Is formed in accordance with this bending of the engine. That is, when the bending is large only at both ends in the width direction of the engine, the wide folded portion having a large folded width is formed only in the portion 5a, and the folded width of the portion 5b is the same as that of the portion 5c. Width.

When the bending is large only at both ends in the longitudinal direction of the engine, the wide folded portion having a large folded width is formed only in the portion 5b, and the folded width in the portion 5a is the same as the intermediate width similar to that of the portion 5c. Is done. If the deflection is large at both ends in the width direction and both ends in the longitudinal direction of the engine, as shown in FIG.
In both cases, the folded width is increased.

The surface 11 of the metal plate 1 contacting the cylinder head and the surface 2 of the metal plate 2 contacting the cylinder block
1 is covered with a sealing material layer 71, 72 of 10 to 50 μm, preferably 15 to 35 μm in thickness, made of a rubber having heat resistance and flexibility, such as fluoro rubber or silicone resin, or a synthetic resin. One or both of the inner surfaces 12 and 22 of the metal plates 1 and 2 where the metal plate 1 and the metal plate 2 abut each other are similarly coated with a sealing material layer. In the figure, a sealing material layer 73 is coated on the inner surface 12 of the metal plate 1.

These sealing material layers 71, 72 and 73
As shown in FIG. 3, the gasket portion in which the folded portion 5d of the folded portion 5 is located is covered so as to cover the entire portion in which the folded portion is located. On the other hand, the wide folded portion 5 having a large folded width.
In the gasket portion where “a” is located, as shown in FIG. 2, the sealing material layer 72 is covered so as to cover the entire portion where the folded portion is located.
3 covers only the portion o located on the outer peripheral side (far side from the cylinder bore) of the folded portion, and the portion i located on the inner peripheral side
Not coated.

Also in the gasket portion where the folded portion 5c having an intermediate folded width is located, as shown in FIG. 1, the sealing material layers 71 and 73 have the sealing material layer on the inner peripheral side of the folded portion. The part which is not covered is left. After all, in the gasket of the embodiment, the sealing material layer 7
Numerals 1 and 73 cover the outer periphery of the gasket portion where the folded portion 5 is located at a width substantially equal to the width of the sealing material layer covered at the portion where the folded portion 5d having a narrow folded width is located over the entire circumference around the cylinder bore. Have been.

When the gasket of the embodiment having such a structure is mounted between the cylinder head and the cylinder block and fastened by bolts, the sealing material layers 71 and 73 are not covered and the thickness is reduced accordingly. No tightening force acts on the inner peripheral side part i, and the tightening force is not dispersed. Accordingly, even in the gasket portion where the wide folded portions 5a and 5b are located, the tightening force is concentrated on the outer peripheral portion o having a width substantially equal to the narrow folded width of the folded portion 5d, and a high surface pressure can be obtained.

The embodiments described above can be variously modified within the scope of the present invention. For example, the sealing material layer 72 applied to the outer surface 21 of the metal plate 2 also has the wide folded portion 5.
a and 5b may cover only the outer peripheral side in the position portion, or the sealing material layers 71 and 73 may be a sealing material layer covering the entire portion where the folded portion is located,
Only the sealing material layer 72 may be a sealing material layer that does not cover the inner peripheral side of the portion where the folded portion is located.

The folded portion 5 of the metal plate 2 may be folded toward the outer surface 21. In this case, gasket G
Is mounted between the cylinder head H and the cylinder block B and fastened with bolts, the metal plate 2 is bent adjacent to the outside of the folded portion 5 as shown in FIG. 4 (a cross-sectional view similar to FIG. 2). A portion 8 is formed, and the folded portion 5 functions as a stopper as in the embodiment of FIGS. Further, the present invention is not limited to a laminated gasket, but can be applied to a single-plate gasket.

[0022]

As described above, the cylinder head gasket of the present invention has both ends and / or lengths in the width direction of the cylinder head and the cylinder block which are generated when the gasket is mounted between the cylinder head and the cylinder block and bolted. In order to respond to the bending at the both ends in the direction, in the wide folded portion formed at the both ends in the gasket width direction and / or at both longitudinal ends in the folded portion of the peripheral edge of the cylinder bore of the gasket,
Tightening force is not distributed over the entire area where the wide folded part is located, but concentrated on the outer peripheral side covered with the sealing material layer, and high surface pressure can be obtained, so the sealing performance around the cylinder bore of the gasket is improved I do.

[Brief description of the drawings]

FIG. 1 is a plan view of a cylinder head gasket according to an embodiment of the present invention.

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

FIG. 3 is an enlarged sectional view taken along line BB of FIG. 1;

FIG. 4 is a sectional view similar to FIG. 2 of another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 3 Cylinder bore 5 Folded part 5a, 5b, 5c, 5d Folded part 6 Bead 71, 72, 73 Seal material layer

Claims (4)

[Claims] A metal plate having at least one metal plate provided with a cylinder bore and a bolt hole, having a folded portion formed by folding the metal plate around the periphery of the cylinder bore, and surrounding the cylinder bore at a position outside the folded portion; In a cylinder head gasket including a bead, a portion located at both ends in the gasket width direction in the folded portion and separated from the bolt hole is a wide folded portion having a folded width larger than a folded width of another portion,
A cylinder head gasket, wherein at least one of the sealing material layers coated on the surface of the metal plate is coated only on a portion located on the outer peripheral side of the folded portion in the gasket portion where the wide folded portion is located. . A metal plate having at least one metal plate provided with a cylinder bore and a bolt hole, having a folded portion formed by folding the metal plate around a periphery of the cylinder bore, and surrounding the cylinder bore at a position outside the folded portion. In a cylinder head gasket including a bead, a portion located at both ends in the gasket longitudinal direction in the folded portion and separated from the bolt hole is a wide folded portion having a folded width larger than a folded width of another portion, A cylinder head gasket, wherein at least one of the sealing material layers coated on the surface of the metal plate is coated only on a portion located on the outer peripheral side of the folded portion in the gasket portion where the wide folded portion is located. . 3. A cylinder comprising a metal plate having a cylinder bore and a bolt hole, having a folded portion formed by folding the metal plate around the periphery of the cylinder bore, and surrounding the cylinder bore at a position outside the folded portion. In a cylinder head gasket provided with a bead, a portion of the folded portion located at both ends in the gasket width direction and both ends in the longitudinal direction and separated from the bolt holes has a folded width wider than the folded width of the other portion. In addition, at least one layer of the sealing material layer coated on the surface of the metal plate is coated only on the outer circumferential side of the folded portion in the gasket portion where the wide folded portion is located. Cylinder head gasket. 4. The sealing material layer covering width only in a portion of the gasket where the wide folded portion is located and located on an outer peripheral side of the folded portion has a sealing material layer covering width in another portion of the folded portion. 4. The cylinder head gasket according to claim 1, wherein the cylinder head gasket is substantially equal to: