JPH11294587A - Stacked metal gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure stable sealing performance by forming a spring constant of beads surrounding a combustion chamber hole of a surface plate into being just the same as two layers of the surface plate, or extending over a plurality of thickness ranks as a whole, in a stacked metal gasket, consisting of the two layers of the surface plate and an intermediate plate and having the plural thickness ranks for selective assembling use. SOLUTION: This metal gasket is comprised of two layers of surface plates H and B having the same form beads 2 and 2' surrounding combustion chamber holes 1, and an intermediate plate M being stacked in space between these plates and having a turnup part 3 in each peripheral edge of the combustion chamber holes, and it is provided with a plurality of thickness ranks different in thickness alone for selective assembling use. Each thickness of the two-layer surface plates is equal, and it is just the same extending over the whole thickness rank, but only thickness of the intermediate plate differs at each thickness rank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A two-layer metal plate having a ridge bead surrounding a combustion chamber hole, an intermediate plate having a folded portion at the periphery of the combustion chamber laminated between the surface plates, and a flat plate thickness adjusting plate. Laminated metal gaskets are known. The adjustment of the thickness of the gasket is mainly performed by adjusting the thickness of the thickness adjusting plate, and the thickness of the intermediate plate having the folded portion is not adjusted for the purpose of adjusting the thickness of the gasket.

[0003] Since the gap between the piston and the cylinder head, the so-called top clearance, affects the engine output and exhaust gas, the top clearance is strictly controlled. This top clearance is usually adjusted by the thickness of the cylinder head gasket, and a predetermined top clearance is obtained by a so-called select assembly in which gaskets having different thickness ranks are selectively assembled to the engine. Accordingly, a plurality of thickness rank gaskets with slightly different thicknesses for the same type of engine are required. The gaskets of the plurality of thickness ranks differ only in the thickness, and all other gasket configurations are the same.

[0004]

The laminated metal gasket for adjusting the thickness of the gasket by the thickness adjusting plate is as follows.
Since the thickness of the adjustment plate cannot be made too thin, it may be difficult to adjust the slight difference in thickness between the above-mentioned multiple thickness ranks for selective assembly. It is costly to provide a thickness adjusting plate. Therefore, a laminated metal gasket having a plurality of thickness ranks for selective assembly has heretofore been constituted by a two-layer face plate having a bead and a one-layer intermediate plate having a folded portion.
It was usual that the thickness of the surface plate of the layer was changed appropriately.

In the gaskets of each thickness rank, the shape of the bead surrounding the combustion chamber hole of the face plate is the same.
If the thickness of the surface plate is different for each thickness rank as described above,
The bead of the face plate has a different spring constant for each thickness rank. However, when assembling the gasket to the engine, the gasket is assembled under the same conditions (tightening torque) regardless of the thickness rank, so that, for example, the tightening torque is equal to the thickness rank 1 (the thinnest thickness). If it is most suitable for gasket, thickness rank 3 with large spring constant
A (thick) gasket has insufficient tightening torque, and it is difficult to obtain stable sealing performance over the entire thickness rank.

Also, the thickness of the surface plate H on the cylinder head side and the thickness of the surface plate B on the cylinder block side may differ depending on the thickness rank. In this case, the beads of the surface plate H and the beads of the surface plate B may be different. Since the spring constant of the gasket is different from that of the gasket, the beads are liable to crack during long-term use, and the durability of the gasket tends to decrease.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to solve the problem by selecting a spring constant of a bead surrounding a combustion chamber hole of a face plate by selecting a two-layer face plate. The aim is to make it the same across a plurality of thickness ranks for assembly.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention comprises a bead having an identical shape surrounding a combustion chamber hole.
A laminated metal gasket comprising a surface plate of two layers and an intermediate plate laminated between the surface plates of two layers and having a folded portion at the periphery of the hole of the combustion chamber, wherein the laminated metal gasket differs only in thickness, except for the thickness. It has a plurality of thickness ranks for selective assembly having the same configuration, wherein the thickness of the two-layer face plate is equal to each other and the same at each thickness rank, and only the thickness of the intermediate plate is different. It is characterized in that it differs for each thickness rank.

In the present invention having the above-described structure, the shapes of the beads surrounding the combustion chamber holes of the two-layer surface plate are the same as each other and are the same in each thickness rank. Similarly, the thicknesses of the two-layer face plates are not only equal to each other, but are also constant at each thickness rank. Therefore, the spring constants of the beads in the two-layer faceplate are equal to each other and the same throughout the thickness rank. Therefore, in the gasket of the present invention, the gaskets of each thickness rank can be assembled in the optimum condition under the same condition (tightening torque), and stable sealing performance can be obtained.
In addition, the gasket has good durability without cracking during long-term use.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details and embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of a cylinder head gasket which is an embodiment of a laminated metal gasket according to the present invention, and FIG. 2 is an enlarged sectional view taken along line II-II of FIG. However, in FIG. 1, illustration of cooling water passage holes, oil passage holes, and the like is omitted for simplification of the drawing.

A cylinder head gasket G according to an embodiment of the present invention has a surface plate H on the cylinder head side made of an elastic metal plate such as a stainless steel plate, and a cylinder block gasket G made of a metal plate of the same material as the surface plate H. A face plate B and an intermediate plate M made of a metal plate such as a stainless steel plate or a steel plate softer than the surface plates H and B and laminated between the surface plate H and the surface plate B
Consists of

The front plate H and the front plate B are each provided with a ridge bead 2 or 2 'which surrounds and seals the combustion chamber hole 1 at a position outside the folded portion 3 described later. The surface plate H and the surface plate B made of the same material metal plate have the same thickness. The beads 2 and 2 'have the same shape, and the height and width of the beads are equal to each other. Therefore, beads 2 and 2 'have the same spring constant. The projection direction of the bead is opposite to that of the bead 2 and the bead 2 ', and both project toward the intermediate plate M.

The intermediate plate M has a folded portion 3 formed by folding the peripheral edge of the combustion chamber hole at the peripheral edge of the combustion chamber hole 1. The gasket thickness is larger in the folded portion 3 than in other portions of the gasket, and the folded portion 3 seals the combustion chamber hole 1 by its thickness effect, and also has the convex bead 2,
It functions as a stopper for restricting the compression of 2 ', reduces the amplitude of expansion and contraction of the beads 2, 2' which are repeated based on the gas pressure in the combustion chamber, and reduces the bead 2, 2 'during long-term use of the gasket. Prevent damage. 4 is a bolt hole.

The cylinder head gasket according to the present invention comprising the surface plate H, the surface plate B, and the intermediate plate M as described above, is selectively assembled with gaskets having slightly different thicknesses so as to obtain a predetermined top clearance. For so-called select assemblies, it includes gaskets of thickness ranks 1, 2 and 3 which have the same configuration except for the thickness of the gasket, which differs only slightly. According to the present invention, the thicknesses of the surface plates H and B do not change at each thickness rank and are constant, and only the intermediate plate has a different thickness at each rank. Table 1 shows examples of the thickness of the surface plates H and B and the thickness of the intermediate plate M at each thickness rank.

[0015]

[Table 1]

Intermediate plate M having a different thickness for each thickness rank
Is different depending on the hardness of the intermediate plate in view of the formation of the folded portion 3, but it is usually desirable to select the thickness within the range of 0.1 to 0.25 mm. According to the present invention,
As shown in Table 1, the thicknesses of the surface plate H and the surface plate B are not only equal to each other, but also constant at each thickness rank, so that the beads 2 and 2 'having the same shape have the same spring constant. In addition, the same applies to the gaskets of each thickness rank.

Therefore, the gaskets of each thickness rank can be tightened under the same conditions in an optimum state, and stable sealing performance can be obtained. Further, since the bead 2 of the surface plate H and the bead 2 'of the surface plate B always have the same spring constant, the beads do not crack during long-term use of the gasket.

The embodiments of the present invention are not limited to those described above, and can be variously modified. For example, the projecting directions of the convex beads 2, 2 'may be opposite to those in FIG. 2, and the projecting beads 2 and 2' may project toward the outside of the gasket. The shape of the bead is not limited to the illustrated mountain shape, but may be other shapes such as a trapezoid. Further, the bead is not limited to a convex bead, and may be a step bead. The thickness rank is not limited to three ranks.

[0019]

As described above, according to the present invention,
The following effects can be obtained. The spring constants of the beads surrounding the combustion chamber holes of the two-layer faceplate are equal to each other and do not change at each thickness rank. Therefore, the gaskets of each thickness rank can be assembled optimally under the same conditions, and stable sealing performance can be obtained. Since the spring constant of the bead of the two-layer faceplate is always the same at each thickness rank, no cracking occurs during long-term use of the gasket.

[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 II-II of FIG.

[Explanation of symbols]

 H Surface plate (cylinder head side) B Surface plate (cylinder block side) M Intermediate plate 2, 2 'Convex bead 3 Folded portion

Claims (1)

[Claims] 1. A laminated metal gasket comprising a two-layer face plate provided with beads of the same shape surrounding a combustion chamber hole, and an intermediate plate laminated between the two surface plates and having a folded portion at the periphery of the combustion chamber hole. The laminated metal gasket differs only in thickness, has a plurality of thickness ranks for selective assembly having the same configuration except for the thickness, and the thickness of the two-layer face plate is equal to each other and A laminated metal gasket having the same thickness in each thickness rank, wherein only the thickness of the intermediate plate is different in each thickness rank.