JPH0612095B2 - Veneer metal gasket - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [Industrial application] The present invention relates to a single-plate metal gasket, and in particular, the spring constant is made small as a whole, and the sealing pressure at a position separated from a bolt fastening part is increased. TECHNICAL FIELD The present invention relates to a single-plate metal gasket that secures a substantially uniform surface pressure on a joint surface by a bead and improves sealing performance.

[Prior Art] A metal gasket is known in which a bead is formed on an elastic metal plate and the bead is used to efficiently seal, for example, a joint between a cylinder head and a cylinder block of an internal combustion engine. This metal gasket is compressed and deformed by the bolt fastening force between the cylinder head and the cylinder block to form a seal line on the joint surface to achieve a seal.

[Problems to be Solved by the Invention] However, in the bead of the substrate, the surface pressure is different between the bolt fastening portion and the portion separated from the fastening portion, and the surface pressure at the separated portion is lower than that of the bolt fastening portion. Similarly, the sealing pressure was low and there was a drawback that leaks were likely to occur. As a means for eliminating this drawback, it is sufficient to increase the bolt fastening force, but on the other hand, the surface pressure of the bolt fastening part becomes higher than necessary, and as a result, the bead may damage the joining surface, It was not possible to easily increase the bolt tightening force. For this reason, it is the current situation that the gasket is additionally treated with a liquid sealant or the like to provide a first aid seal, particularly at a portion where the pitch of the fastening bolt is longer than necessary, and drastic measures are desired. Was there.

[Object of the invention] Therefore, an object of the present invention is to eliminate the above-mentioned inconveniences.
The bead that gives the surface pressure is made into a stepped bead to reduce the spring constant as a whole, the bolt tightening force is small, and the sealing pressure at the part separated from the bolt tightening part is increased to increase the surface pressure to the joint surface. The purpose of the present invention is to realize a single-plate metal gasket capable of ensuring a substantially uniform temperature, preventing leakage, and improving the sealing performance.

[Means for Solving the Problems] In order to achieve this object, the present invention provides a substrate made of an elastic metal plate with a combustion chamber hole and a plurality of bolt holes around the combustion chamber hole. Is provided with a stepped bead that surrounds the combustion chamber hole and is separated from the bolt hole without surrounding the bolt hole, and the spring constant is increased as it is separated from the bolt hole side of the bolt fastening portion. The height of the step-shaped bead is formed to be larger than the height of the step-shaped bead of the bolt-fastened portion as the distance from the bolt-fastened portion is increased, and the width of the step-shaped bead is increased as the distance from the bolt-fastened portion is increased. It is formed to be smaller than the width of the step-shaped bead of the bolt fastening portion, and the step-shaped bead between the combustion chamber hole and the bolt hole is formed on the inner peripheral surface of the combustion chamber hole and the It is characterized in that it is arranged at a substantially central portion of the inner peripheral surface of the bolt hole.

[Operation] According to the configuration of the present invention, the single-plate metal gasket interposed in the joint portion reduces the bolt fastening force by the stepped bead, and at the bolt fastening portion and the portion separated from the bolt fastening portion. The surface pressure ratio is made small and uniform sealing pressure is applied to the joint surfaces to improve the sealing performance. Also, by providing a stepped bead on the substrate, the spring constant is made small overall, thereby reducing the fastening force, avoiding damage to the joint surface by the bead, and allowing horizontal sliding. Ensures good sealability. Further, since the stepped bead between the combustion chamber hole and the bolt hole is arranged at a substantially central portion between the inner peripheral surface of the combustion chamber hole and the inner peripheral surface of the bolt hole, the fastening force is a step with a small spring constant. It is possible to prevent functional deterioration of the step-shaped bead without greatly affecting the shaped bead, and to secure a predetermined surface pressure to the joint surface to improve the sealing property.

Embodiments Embodiments of the present invention will be described in detail and specifically below with reference to the drawings.

1 to 4 show an embodiment of the present invention. In the figure, 2 is a single plate metal gasket. The single plate metal gasket 2 is composed of a substrate 4 made of an elastic metal plate. A combustion chamber hole 6 is formed in the substrate 4, and a plurality of bolt holes 8 are formed around the combustion chamber hole 6.

In addition, the substrate 4 surrounds the inner peripheral edge 10 of the combustion chamber hole 6 and circulates inside the bolt hole 8, that is, apart from the bolt hole 8 and does not surround the bolt hole 8, and has a stepwise sectional shape. Stepped beads 12 are formed.

The stepped bead 12 has a different cross-sectional shape in the vicinity of the bolt hole 8 which is a bolt fastening portion and between the bolt holes 8 and 8 which is a portion separated from the bolt fastening portion. That is, as shown in FIG. 2, on the bolt hole 8 side that is the bolt fastening portion, the cross-sectional shape of the first step-shaped bead 12a of the step-shaped bead 12 is formed such that the bead height is H ₁ and the bead width is L ₁ . Has been done. On the other hand, as shown in FIG. 3, the second step-shaped bead 12b of the step-shaped bead 12 is located between the bolt holes 8 and 8 separated from the bolt-fastened portion, and the bead height H increases as the second step-shaped bead 12b moves away from the bolt-fastened portion. It is by connexion formed bead width L ₂ made smaller than the large consisting bead height H ₂ and the bead width L ₁ than _1. As a result, the metal gasket 2 is configured to have a small spring constant as a whole, and is configured to have a large spring constant as it is separated from the bolt hole 8 side. The step-shaped bead 12 is not limited to the above-described shape in cross-section, as long as the spring constant of the step-shaped bead 12 at the portion separated from the bolt fastening portion is large. By the way, the spring constant of the stepped bead 12 is determined by the elastic restoring force of the substrate 4 and the bolt fastening force acting on the joint portion 18 described later. In this case, it goes without saying that the sealing pressure of the stepped bead 12 surrounding the combustion chamber hole 6 is taken into consideration so as to generate the pressure necessary to prevent the occurrence of leakage.

Further, as is apparent from FIG. 1, the first step-shaped bead 12a between the combustion chamber hole 6 and the bolt hole 8 is located approximately at the center between the inner peripheral surface 10 of the combustion chamber hole 6 and the inner peripheral surface 8a of the bolt hole 8. It is formed in the part.

In FIG. 4, reference numerals 14 and 16 denote a cylinder head and a cylinder block constituting an internal combustion engine, and the veneer metal gasket 2 is interposed at a joint portion 18 between the cylinder head 14 and the cylinder block 16. Reference numeral 20 is a combustion chamber and 22 is a piston.

Next, the operation of this embodiment will be described.

The single plate metal gasket 2 interposed in the joint portion 18 between the cylinder head 14 and the cylinder block 16 has a bolt hole 8
It is compressed and deformed by the fastening force of the fastening means inserted through. Then, the step-shaped bead 12 is brought into close contact with the surface of the crack which is the joining surface between the cylinder head 14 and the cylinder block 16 to form a seal line. At this time, conventionally, the surface pressure due to the bolt fastening force is large in the vicinity of the bolt hole 8 and
It became lower as it was separated from.

However, according to this embodiment, since the spring constant of the step-shaped bead 12 becomes larger as it is separated from the bolt hole 8 side, the elastic restoring force of the step-shaped bead 12 becomes larger than the conventional one. Become. As a result, it is possible to sufficiently compensate for the shortage of the surface pressure due to the bolt fastening force, reduce the ratio of the surface pressures, and evenly apply the sealing pressure required to prevent the occurrence of leakage.

Further, by forming the step-like beads 12 on the substrate 4, the spring constant is made small as a whole to improve the adhesion, and the fastening force is made small to prevent the bead from damaging the joint surface, and further, the horizontal direction. Of the stepped bead 12 due to the explosive force can be avoided and the service life can be extended.

Furthermore, since it is a single metal gasket and has good adhesion,
The gap of the joint portion 18 can be narrowed to prevent the gas from passing through, and the thermal conductivity can be improved to make the heat even and the heat satisfactorily dissipated.

Furthermore, since no step is formed on the stepped bead 12, damage to the joint surface can be prevented.

In addition, the stepped bead can have a bead width smaller than that of the convex bead, and the gasket of the small internal combustion engine can be easily configured.

Further, since the first step-shaped bead 12a between the combustion chamber hole 6 and the bolt hole 8 is formed in the substantially central portion between the inner peripheral surface 10 of the combustion chamber hole 6 and the inner peripheral surface 8a of the bolt hole 8, the fastening is performed. The force does not significantly affect the first step-shaped bead 12a having a small spring constant, which prevents the step-shaped bead 12 from deteriorating in function, and has a predetermined surface on the joint surface between the cylinder head 14 and the cylinder block 16. It is possible to secure pressure and improve the sealing property.

[Effects of the Invention] As is apparent from the above detailed description, according to the present invention,
A combustion chamber hole and a plurality of bolt holes are formed in the substrate made of an elastic metal plate around the combustion chamber hole. The combustion chamber hole is surrounded by the substrate and the bolt hole is separated from the bolt hole without surrounding the bolt hole. A stepped bead is provided on the stepped bead, and the height of the stepped bead is higher than the height of the stepped bead at the bolted portion as the distance from the bolted portion is increased to increase the spring constant as the bolted portion is separated from the bolt hole side. The width of the step-shaped bead is formed to be smaller than the width of the step-shaped bead at the bolt-fastened portion with increasing distance from the bolt-fastened portion, and the step-shaped bead between the combustion chamber hole and the bolt hole is formed as a combustion chamber hole. By arranging them at approximately the center of the inner peripheral surface of the bolt and the inner peripheral surface of the bolt hole, the bolt tightening force is reduced and the surface pressure of the separated portion of the bolt tightened portion is increased. Evenly by applying a sealing pressure of Lumpur site to improve the sealing property.

Also, by providing a stepped bead on the substrate, the spring constant is generally small to improve the degree of adhesion, and the fastening force is also small to prevent the joint surface from being damaged by the bead, and it is horizontal. It is possible to allow the sliding in the direction to ensure good sealing property.

Further, the single plate metal gasket of the present invention has a simple structure, is easy to manufacture, and can be used in a small internal combustion engine because the bead width can be made small, and the material cost and the manufacturing cost are low. It will be cheaper.

Furthermore, it is possible to avoid the occurrence of hitting of the step-like beads due to the explosive force, and to prolong the service life.

Furthermore, since it is a single metal gasket and has good adhesion,
It is possible to narrow the gap at the joint portion to prevent blow-through of gas generation, and to enhance the thermal conductivity, so that the heat can be leveled and the heat can be satisfactorily dissipated.

Furthermore, since the top of the stepped bead is not formed, damage to the joint surface can be prevented.

Further, since the stepped bead between the combustion chamber hole and the bolt hole is formed in the substantially central portion between the inner peripheral surface of the combustion chamber hole and the inner peripheral surface of the bolt hole, the fastening force is a stepped bead with a small spring constant. It is possible to prevent the functional deterioration of the step-like bead and to ensure a predetermined surface pressure at the joint surfaces of the cylinder head and the cylinder block, thereby improving the sealing performance.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention, FIG. 1 is a plan view of a veneer metal gasket, FIG. 2 is an enlarged sectional view of the veneer metal gasket taken along line II-II of FIG. 1, and FIG. Fig. 1
FIG. 4 is an enlarged cross-sectional view of the single plate metal gasket taken along the line III-III, and FIG. 4 is a cross-sectional view of a main part with a part of the single plate metal gasket interposed between the cylinder head and the cylinder block. In the figure, 2 is a single plate metal gasket, 4 is a substrate, 6 is a combustion chamber hole, 8 is a bolt hole, 12 is a stepped bead, 1
2a is a first step bead, 12b is a second step bead, and 18 is a joint.

Claims (1)

[Claims] 1. A combustion chamber hole and a plurality of bolt holes around the combustion chamber hole are formed in a substrate made of an elastic metal plate. The substrate surrounds the combustion chamber hole and is separated from the bolt hole. The stepped bead is provided without surrounding the bolt hole, and the height of the stepped bead is increased as it is separated from the bolt fastening portion so as to increase the spring constant as it is separated from the bolt hole side of the bolt fastening portion. The width of the step-shaped bead is formed to be smaller than the height of the step-shaped bead of the bolt-fastened portion and the width of the step-shaped bead is made smaller than the width of the step-shaped bead of the bolt-fastened portion as it is separated from the bolt-fastened portion. The stepped bead between the combustion chamber hole and the bolt hole is arranged substantially at the center of the inner peripheral surface of the combustion chamber hole and the inner peripheral surface of the bolt hole. Plate metal gasket.