JPH06147325A - Laminated metallic plate gasket - Google Patents

Abstract

PURPOSE:To improve a seal property and to lengthen the life of a metallic plate gasket wherein a bead plate formed by an elastic metallic plate and wherein a projecting bead is provided around a cylinder bore is laminated to a sub plate wherein a thick part by a turn-up part is provided on a-cylinder bore peripheral edge. CONSTITUTION:Graphite covering layers 7, 7' to which graphite sheets whose thickness is 50 to 200mum are sutck are provided on both surfaces of a bead plate 6 wherein an angled bead 8 is provided around a cylinder bore 2. A graphite covering layer 14 is provides also on the surface to come in contact with a surface to be sealed of a sub plate 11 on which a thick part is formed by a turn-up part 12, a shim plate, etc., on the peripheral edge of the cylinder bore 2. The thick part is positioned on the cylinder bore side to the bead 8 by laminating the bead plate to the sub plate, thereby a compensation part 15 is formed on the cylinder bore peripheral edge of a gasket 1.

Description

Detailed Description of the Invention

[0001]

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

[0002]

BACKGROUND OF THE INVENTION In a cylinder head gasket mounted between a cylinder block and a cylinder head of an engine, a bead plate (substrate) made of an elastic metal plate and provided with a convex bead around a cylinder bore, and a relatively soft bead plate. By laminating a sub plate made of a metal plate and provided with a folded-back portion on the peripheral edge of the cylinder bore, a compensating portion having a thicker thickness than other portions is formed on the cylinder bore side of the bead portion around the cylinder bore of the laminated metal plate gasket. It has been proposed by JP-A-62-155374 and JP-A-62-115562 that the bead is protected by the compensator to prevent damage and fatigue of the bead.

In the above proposal, it is not shown that both the front and back outer surfaces of the entire laminated metal plate gasket and the opposing surfaces of the laminated metal plates are coated with the sealing material coating layer. Is a seal that has a so-called micro-seal function that absorbs and compensates for surface roughness and irregularities such as tool marks and scratches on the mating surfaces of the cylinder head and cylinder block, and on the opposing side surfaces where the laminated metal plates face each other. It is desirable to provide a material coating layer.

However, even if heat-resistant rubber or plastic is used for the conventional sealing material coating layer made of rubber or plastic, the heat resistance is limited because it is an organic material.
When used in a state where it is exposed to high-temperature combustion gas like a cylinder head gasket, there is a risk that the sealing material coating layer will be thermally deteriorated during long-term use and the function of the microseal cannot be achieved. Further, when the sealing material coating layer is thermally deteriorated, the friction when the convex bead in contact with the sealing material coating layer expands and contracts increases, and the expansion and contraction tend to be hindered, so that the bead is liable to be damaged or settled. is there.

Therefore, even if the convex bead is effectively protected by the compensating portion and the bead is prevented from being damaged or settled to prolong the life of the gasket as in the case of the laminated metal plate gasket, the sealing material is also used. If the improvement of the coating layer is not accompanied by this, there is a problem that it is difficult to achieve the effect.

Further, the thickness of the conventional sealing material coating layer made of rubber or plastic is relatively thin, for example, 5 to 30 μm when it is formed by coating of fluororubber.
It is a degree. It is desirable to make the thickness of the seal coating layer thicker in order to fully exert the function of the microseal for a long period of time, but it is difficult to form a thick coating layer having a uniform thickness by one coating. It also has the drawback of requiring multiple coatings, which is costly.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and a laminated metal in which a compensating portion having a thicker thickness than other portions is formed on the cylinder bore side of the bead portion around the cylinder bore. It is intended to improve the heat resistance of the sealing material coating layer and the function of the microseal in the plate gasket.

[0008]

A laminated metal plate gasket of the present invention which achieves the above object comprises a bead plate made of an elastic metal plate having a convex bead around a cylinder bore, and a relatively soft metal plate. A sub-plate having a folded-back portion and a thick portion formed by a shim or the like is laminated on the peripheral edge of the cylinder bore, and at least one of the front and back outer surfaces of the entire laminated metal plate gasket and the facing surface of the laminated metal plates. A coating of a graphite sheet having a thickness of 50 to 200 μm is provided.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings of the embodiments. 1 is a plan view of an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG. FIG. 3 is a sectional view showing another embodiment of the present invention, which is a sectional view corresponding to the section taken along the line AA of FIG. The same reference numerals indicate the same parts.

1 and 2, reference numeral 1 denotes a cylinder head gasket according to the present invention, which includes a cylinder bore 2, a cooling water passage hole 3, an oil passage hole 4 and a bolt insertion hole 5. As shown in the sectional view of FIG. 2, the cylinder head gasket 1 includes a bead plate 6 made of a hard metal plate having spring elasticity such as a stainless steel plate and an iron plate or a soft stainless plate, for example, a blunted material of SUS304. And a sub plate 11 made of a relatively soft metal plate.

A convex chevron bead 8 is formed on the bead plate 6 around the cylinder bore 2, and the beads 8, 8 ,.
A mountain-shaped bead 9 that collectively surrounds the cooling water passage holes 3, 3, ... Is formed. Furthermore, a mountain-shaped bead 10 is formed around the oil passage hole 4 to surround and seal the oil passage hole 4. These beads are preferably formed so as to project to the same side of the bead plate. In FIG. 1, these beads 8, 9 and 10 are shown by dotted lines.

When the cylinder head gasket 1 is mounted between the cylinder blocks, which are the surfaces to be sealed, and the deck surfaces of the cylinder head and tightened with the fastening bolts, the beads 8, 9 and 10 are pressed and raised to the respective deck surfaces. Generates sealing surface pressure. The thickness of the bead plate 6 is 50 to 200 μm on both front and back sides as a sealing material coating layer.
Graphite coating layers 7 and 7'where m graphite sheets are bonded by an adhesive material are provided.

In the sub-plate 11, a thick-walled portion is formed on the peripheral edge of the cylinder bore by providing a folded-back portion 12 which is formed by folding back the peripheral edge of the cylinder bore 2. Further, a graphite coating layer 14 is provided on one surface of the sub-plate 11 that is in contact with the sealed surface, and a graphite sheet having a thickness of 50 to 200 μm is adhered by an adhesive material. In addition, in FIG. 1, the folding | returning part 12 is shown with the dotted line.

The graphite sheets forming the above graphite coating layers 7 and 14 are sheets of graphite having a layered structure of a hexagonal net plane of carbon atoms, and the graphite is preferably oxidized with an oxidizing agent in the presence of sulfuric acid. By rapidly heating the oxidized graphite obtained by the treatment at high temperature, the inserts inside the graphite layers are decomposed and gasified to form expanded graphite that expands the graphite layers, and this is continuously pressed to form a sheet. Is obtained (however, it is not limited to the graphite sheet produced by such a production method). Graphite has excellent compressibility, resilience, stress relaxation and flexibility in addition to the excellent heat resistance and chemical stability inherent in graphite. Further, a uniform sheet having a thickness range of 50 to 200 μm can be easily obtained.

In the cylinder head gasket formed by laminating the bead plate 6 and the sub plate 11 described above,
As shown in, the thick portion formed by the folded-back portion 12 is located further on the cylinder bore side than the position of the mountain-shaped beads 8 around the cylinder bore 2. That is, the bead plate 6 and the sub plate 1
A compensating portion 15 having a joint thickness with 1 that is larger than that of other portions of the gasket 1 is formed on the cylinder bore side with respect to the position of the bead 8.

When the laminated cylinder head gasket 1 is mounted so as to be sandwiched between the deck surfaces of the cylinder head and the cylinder block of the engine and is bolted, the compensating section 15 forms the cylinder head and the cylinder block. Compensating for the deck surface clearance around the cylinder bore that occurs when the bolts are fastened, and the high temperature gas in the combustion chamber is compensated by the compensator 15.
The angled bead 8 and the angled bead 8 seal in two stages, the sealing effect is improved, and the high temperature gas in the combustion chamber can be prevented from directly hitting the angled bead 8. Further, since the compensator 15 compensates for the deck surface gap, the chevron bead does not deform until it becomes completely flat, and the alternating load applied to the bead 8 during engine operation is weakened. Therefore, the compensation unit 1
The presence of 5 improves the sealing effect and prevents the bead 8 from being damaged or settled to prolong the service life of the gasket.

At this time, the graphite coating layer 7 provided on the outer surface of the bead plate 6 and the graphite coating layer 14 provided on the outer surface of the sub plate 11 are the tool marks on the sealed surface, that is, the deck surface of the cylinder block and the cylinder head. , The micro seal function that compensates and absorbs roughness such as scratches and irregular surface is absorbed, and secures a good seal between deck surfaces. The graphite coating layer 7'provided on the surface of the bead plate 6 on the side in contact with the sub plate 11 also has the function of a microseal for compensating for and absorbing the roughness and irregularity of the mating surface.
Since graphite has a low coefficient of friction, the bead compression,
It has the effect of smoothing the restoration, and the compensation unit 1 described above
Synergistic with the effect of 5, the bead 8 is prevented from sagging, which contributes to a longer service life of the gasket.

The thickness of the graphite sheet forming the graphite coating layers 7, 7'and 14 having the above-mentioned functions is selected in the range of 50 to 200 μm. If the thickness of the graphite sheet is 50 μm or less, the function of the microseal cannot be sufficiently fulfilled for a long period of time, and if the thickness of the graphite sheet exceeds 200 μm, the thickness becomes too thick and easily causes fatigue, and the oil resistance decreases. This is because there is a tendency to The thickness of the bead plate 6 and the thickness of the sub plate 11 are
Both are preferably selected in the range of 0.1 to 0.3 mm from the viewpoint of mechanical strength and conformability to the surface to be sealed.

In another embodiment of the gasket of the present invention shown in FIG. 3, the thick portion of the peripheral edge of the cylinder bore of the sub-plate 11 is formed by welding or brazing the shim plate 13.
The bead plate 6 is provided with the graphite coating layer 7 only on the outer surface in contact with the surface to be sealed, and the sub-plate 11 is provided with the graphite coating layers 14 and 14 'on both surfaces thereof. It is of course possible to provide the graphite coating layers 7 and 7'on both sides of the bead plate 6 and the graphite coating layers 14 and 14 'on both sides of the sub plate 11. Further, the thick portion on the peripheral edge of the cylinder bore of the sub-plate 11 can be formed by thermal spraying of metal or bulging by pressing.

In the above description of the embodiment, the bead 9 surrounds the cooling water passage holes 3, 3, ... In the bead plate 6 and the bead 1 surrounds and seals the oil passage holes.
Although 0 is a convex mountain-shaped bead, these beads may be replaced with a well-known step-shaped bead. Also, the bead plate 6
It is also possible to stack a sub plate or a surface plate having a graphite coating layer on the side not in contact with the sub plate 11.

[0021]

The laminated metal gasket of the present invention has the structure and operation as described above, and the graphite coating layer formed by the graphite sheet having a thickness of 50 to 200 μm is exposed to the high temperature gas in the combustion chamber of the engine. Also performs a sufficient micro-sealing function for a long period of time without thermal deterioration, improves the sealing performance of the gasket in combination with the action of the compensating portion formed by the thick portion of the peripheral edge of the cylinder bore of the auxiliary plate, and Contributes to longer life.

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along the line AA of FIG.

3 is a sectional view of another embodiment of the present invention, which is taken along the line AA of FIG.
It is sectional drawing equivalent to the sectional view by a line.

[Explanation of symbols]

 2 cylinder bore 6 bead plate 7 and 7'graphite coating layer 8 and 9 chevron bead 11 sub-plate 12 folded part 13 shim plate 14 and 14 'graphite coating layer 15 compensation part

Claims (1)

[Claims] 1. A bead plate made of an elastic metal plate provided with a convex bead around a cylinder bore, and a sub-plate made of a relatively soft metal plate and having a fold-back portion and a thick portion such as a shim formed on the peripheral edge of the cylinder bore. And a thickness of 50 on at least one of the front and back outer surfaces of the entire laminated metal plate gasket and the opposing surface of the laminated metal plate.
A laminated metal plate gasket having a coating of a graphite sheet of ˜200 μm.