JPH0477832B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement in a metal gasket that performs sealing by forming beads on an elastic metal plate, and particularly relates to improvements in the curvature of the planar shape of the beads formed on the elastic metal plate. The present invention relates to a metal gasket that can equalize the surface pressure acting on the joint surfaces by forming the gasket with a radius that changes according to the fastening force.

[Prior Art] Metal gaskets are used to seal the joining surfaces of members to be joined, for example, the seal between the deck surfaces of a cylinder head and a cylinder block of an internal combustion engine. In a metal gasket, a bead surrounding a combustion chamber hole, which is a sealing part formed on an elastic metal plate, is elastically deformed by the fastening force of a bolt or the like that joins the cylinder head and cylinder block, which are the members to be joined. The elastic restoring force and the amount of elastic restoring apply surface pressure to the deck surface, which is the joint surface between the cylinder head and the cylinder block, where the combustion chamber hole, which is the sealing part, is formed, thereby forming an elastic seal line. This achieves a seal between the deck surfaces and maintains the sealing effect by following the distortion of the deck surfaces.

[Problems to be Solved by the Invention] However, since the fastening force acting on the bead is different between the part near the bolt hole and the part distant from the bolt hole, the surface pressure acting on the deck surface is different, and the bolt hole The surface pressure is smaller in the area separated from the bolt hole than in the area near the bolt hole. For this reason, the surface pressure became uneven, causing a problem in which the surface pressure could not be applied evenly to the deck surface. As a result, a stable sealing effect cannot be achieved, resulting in the inconvenience of leakage.

Furthermore, the cylinder head and cylinder block of an internal combustion engine in which the combustion chamber is formed by a sleeve has the disadvantage that the roundness of the sleeve changes and the cylinder head moves up and down due to combustion pressure. The deck gap expands and contracts due to the vertical movement of the metal gasket, which causes combustion gas to enter, staining the metal gasket and reducing the sealing effect.
Furthermore, there is a problem in that the bead becomes sagging due to the action of alternating loads.

In order to solve this problem, it is possible to increase the bolt tightening force and increase the contact pressure in the area away from the bolt hole, but on the other hand, the contact pressure in the area near the bolt hole becomes larger than necessary, and the As a result, there is a risk that the deck surface may be damaged or the bead may become sagging due to the bead in the vicinity of the bolt hole, making it impossible to easily increase the bolt fastening force.

[Object of the Invention] Therefore, an object of the present invention is to change the radius of curvature of the planar shape of the bead formed on an elastic metal plate in accordance with the fastening force, so that even though the fastening force acting on the bead is different, First, it is possible to equalize the surface pressure acting on the joint surfaces, thereby achieving a stable sealing effect, and avoiding the inconvenience of changing the roundness of the sleeve, suppressing the vertical movement of the cylinder head. The objective is to realize a metal gasket that can obtain the desired results.

[Means for Solving the Problem] In order to achieve this object, the present invention includes a combustion chamber hole in an elastic metal plate, a plurality of bolt holes around the combustion chamber hole, and a bead surrounding the combustion chamber hole. In the metal gasket, the bead is elastically deformed by the fastening force of the bolt inserted through the bolt hole to effect a seal, and the radius of curvature of the planar shape of the bead is made small in a portion spaced apart from the bolt hole. The present invention is characterized in that the radius of curvature of the planar shape of the bead is increased in the vicinity of the hole and is varied according to the fastening force.

[Function] According to the configuration of the present invention, the radius of curvature of the planar shape of the bead formed on the elastic metal plate is changed according to the fastening force. In other words, by forming the radius of curvature of the planar shape of the bead to be small in areas where the fastening force is small and away from the bolt hole, the bead is prevented from sliding in the radial direction and the spring constant becomes large. This fastening force can prevent the surface pressure from becoming small. On the other hand, by forming a large radius of curvature of the planar shape of the bead near the bolt hole where the fastening force is large, the bead is allowed to slide in the radial direction and the spring constant becomes small, resulting in a large fastening force. This can prevent surface pressure from increasing due to force.

Thereby, the surface pressure can be equalized regardless of the difference in the fastening force acting on the bead, and the surface pressure can be applied uniformly to the joint surfaces.

[Example] Next, an example of the present invention will be described in detail based on the drawings.

Figures 1 and 2 show an embodiment of this invention. In FIG. 1, reference numeral 2 denotes a single-plate metal gasket, and the metal gasket 2 is composed of a substrate 4 made of an elastic metal plate. A combustion chamber hole 6 is formed in this substrate 4, and
A plurality of bolt holes 8 are formed around this combustion chamber hole 6. Further, a bead 10 is formed on the substrate 4 so as to surround the combustion chamber hole 6 and to extend around the inside of the bolt hole 8 .

The bead 10 is formed by changing the radius of curvature of the planar shape according to the fastening force of the fastening bolt 16 installed in the front bolt hole 8. That is, bolt hole 8
The radius of curvature r1 of the planar shape of the bead 10 is
is formed into a small size. On the other hand, in a region near the bolt hole 8 where the fastening force is large, the radius of curvature r2 of the planar shape of the bead 10 is formed to be large.

As a result, the bead 10 in the spaced apart portion between the bolt holes 8, 8 where the fastening force is small is suppressed from sliding in the radial direction, and the spring constant becomes large. On the other hand, the bead 10 in the vicinity of the bolt hole 8 is allowed to slide in the radial direction and has a small spring constant.

Next, the operation of this embodiment will be explained.

As shown in FIG. 2, the metal gasket 2 interposed between the deck surfaces 12a and 14a of the cylinder head 12 and cylinder block 14 is compressed by the fastening force of the fastening bolt 16, and the bead 10 is thereby compressed. It is elastically deformed by reducing its height. Due to this elastic deformation, the bead 10 is attached to the cylinder head 12.
and deck surfaces 12a, 1 of cylinder block 14
4a with a predetermined surface pressure to achieve a seal.

At this time, conventionally, the fastening force of the fastening bolt 16 acting on the bead 10 is small in the area between the bolt holes 8 and 8 that are spaced apart from the bolt hole 8, but becomes large in the area near the bolt hole 8. There was a problem in that the surface pressure became uneven and it was not possible to apply the surface pressure evenly to the deck surface.

According to the embodiment of the present invention, the bead 10 has a small radius of curvature r1 of the planar shape of the bead 10 at a portion between the bolt holes 8 and 8, which are spaced apart from the bolt hole 8 and have a small fastening force. The radius of curvature r2 of the planar shape of the bead 10 is formed to be large in a region near the hole 8 where the fastening force is large.

As a result, the bead 10 at the spaced apart portion between the bolt holes 8 and 8 where the fastening force is small is suppressed from sliding in the radial direction and the spring constant becomes large, so the surface pressure is reduced due to the small fastening force. This can be prevented. On the other hand, since the bead 10 in the vicinity of the bolt hole 8 is allowed to slide in the radial direction and has a small spring constant, it is possible to prevent the surface pressure from increasing due to a large fastening force.

Therefore, the surface pressure can be equalized regardless of the difference in the fastening force acting on the bead 10, and the surface pressure can be applied equally to the deck surfaces 12a, 14a of the cylinder head 12 and cylinder block 14.
As a result, a stable sealing effect can be achieved, so that no leakage occurs.

Furthermore, in the case of the cylinder head 12 and cylinder block 14 of an internal combustion engine (not shown) in which the combustion chamber is formed by a sleeve, it is possible to avoid the inconvenience of changing the roundness of the sleeve, and to prevent the cylinder head 12 from changing due to combustion pressure. Vertical movement can be suppressed. By suppressing the vertical movement of the cylinder head 12, it is possible to prevent the gap between the deck surfaces 12a and 14a from expanding or contracting, and to prevent combustion gas from entering.
It is possible to prevent the inconvenience of staining the metal gasket 2 or reducing the sealing effect, and furthermore, it is possible to prevent the inconvenience of the bead 10 becoming sag due to the action of alternating loads.

Further, the bolt holes 8, 8 with a small fastening force can be separated from the bolt hole 8 without increasing the bolt fastening force.
Since it is possible to prevent the contact pressure in the area between the two from becoming small, the contact pressure in the area near the bolt hole 8 will not become larger than necessary. For this reason, the deck surfaces 12a and 14a formed by the beads 10 at the bolt hole 8 locations are
There is no risk of damage to the bead 10 or fatigue of the bead 10.

In this embodiment, the radius of curvature r of the planar shape of the bead 10 is changed depending on the fastening force of the fastening bolt 16, but the height, width, or width of the bead 10 can be changed depending on the fastening force. It is also possible to change the thickness of the substrate 4 at the portion where the bead 10 is formed. Although this embodiment has been explained using a single-plate metal gasket 2, a laminated metal gasket in which a sub-plate is interposed between two or more substrates 4, or two or more substrates 4 may also be used. A sub-plate is interposed between the deck surface 12a of the substrate 4,
It is clear that the present invention can also be applied to a laminated metal gasket in which a sub-plate is superimposed on the side of the contact surface with 14a.
Further, the shape of the bead is not limited to a convex bead, a step bead, etc., and can be formed into various shapes.

〔Effect of the invention〕

As described above, according to the present invention, the radius of curvature of the planar shape of the bead formed on the elastic metal plate is changed according to the fastening force. In other words, by forming the radius of curvature of the planar shape of the bead to be small in areas where the fastening force is small and away from the bolt hole, the bead is prevented from sliding in the radial direction and the spring constant becomes large. This fastening force can prevent the surface pressure from becoming small. On the other hand, in areas where the fastening force is large near the bolt hole, by increasing the radius of curvature of the planar shape of the bead, the bead is allowed to slide in the radial direction and the spring constant becomes small, resulting in a large fastening force. This can prevent surface pressure from increasing due to force.

Thereby, the surface pressure can be equalized regardless of the difference in the fastening force acting on the bead, and the surface pressure can be applied uniformly to the joint surfaces. Therefore, stable sealing can be achieved and no leakage occurs. Furthermore, in the case of a cylinder head and a cylinder block of an internal combustion engine in which the combustion chamber is formed by a sleeve, it is possible to avoid the disadvantage that the roundness of the sleeve changes, and it is also possible to suppress vertical movement of the cylinder head due to combustion pressure. By suppressing the vertical movement of the cylinder head, it is possible to prevent the joint surface gap from expanding or contracting, and to prevent combustion gas from entering.
It is possible to prevent the inconvenience of staining the metal gasket and reducing the sealing effect, and furthermore, it is possible to prevent the inconvenience of bead settling due to the action of alternating loads.

In addition, since it is possible to prevent the contact pressure from becoming small in areas where the fastening force is small and which are away from the bolt hole without increasing the bolt fastening force, the contact pressure in the areas near the bolt hole can be prevented from becoming unnecessarily large. do not have. Therefore, there is no risk of damage to the decking surface or sagging of the bead caused by the bead in the vicinity of the bolt hole.

[Brief explanation of the drawing]

Figures 1 and 2 show an embodiment of the present invention.
The figure is a plan view of the metal gasket, and FIG. 2 is an enlarged sectional view of the metal gasket interposed between the deck surfaces and the bolts tightened. In the figure, 2 is a metal gasket, 4 is a substrate,
6 is a combustion chamber hole, 8 is a bolt hole, 10 is a bead, 1
2 is a cylinder head, 12a is a deck surface, 14 is a cylinder block, 14a is a deck surface, and 16 is a fastening bolt.

Claims (1)

[Claims] 1 A combustion chamber hole, a plurality of bolt holes around the combustion chamber hole, and a bead surrounding the combustion chamber hole are formed in an elastic metal plate, and the bead is elastically deformed by the fastening force of the bolt inserted through the bolt hole. In the metal gasket, the radius of curvature of the planar shape of the bead is small in a portion away from the bolt hole, and the radius of curvature of the planar shape of the bead is increased in a portion near the bolt hole, and the radius of curvature of the planar shape of the bead is changed in accordance with the fastening force. A metal gasket characterized by being formed by.