JPH041406Y2 - - Google Patents

Description

[Detailed description of the invention] "Industrial application field" This invention is a metal gasket for sealing between the cylinder block and cylinder head of an internal combustion engine, and in particular, a metal plate with beads formed on the upper and lower sides of the metal core. This relates to a metal gasket with a composite structure that is joined and integrated with the metal gasket.

``Prior Art'' Conventionally, as shown in Fig. 2, a gasket is made up of two elastic metal plates (upper and lower) integrally formed of the same metal plate with a bead bulging out in an arched cross section along the periphery of the gasket hole. A metal gasket having a composite structure in which a substrate is integrally joined via an intermediate metal core material is known.

``Problems to be solved by the invention'' In the conventional metal gasket mentioned above, the upper and lower substrates are made of inexpensive metal plates such as stainless steel or iron plates, which tend to lose their elasticity relatively easily when heated at high temperatures and have poor thermal deformation resistance. When the cylinder block and cylinder head become hot and the arched bead fixed at both ends receives an excessive load due to thermal expansion, the bead, which has poor heat deformation resistance, is crushed to almost the thickness of the plate, causing permanent deformation and loss of recovery. The disadvantage is that the bead loses its elasticity and becomes almost flat, and if the bead is crushed without recovery, the engine will generally become distorted due to thermal expansion when it gets hot, and the bolts between the cylinder block and cylinder head will elongate and the bolt seats will become distorted. The tightening force between the cylinder block and the cylinder head decreases due to surface sagging, resulting in insufficient pressure contact with the gasket and poor sealing performance, especially when the engine is cooled. Gas leakage will occur at the time of startup, when the temperature is the lowest.

By the way, metal plates with excellent heat deformation resistance and high yield strength even when heated at high temperatures are known, but they are several times more expensive than metal plates commonly used in the past, resulting in a significant increase in cost. The current situation is that it cannot be adopted because of the

It is also possible to make the bead a shape that is less likely to cause permanent deformation, but if the bolt between the cylinder block and cylinder head stretches or the bolt seating surface becomes loose, as mentioned above, the contact force may be insufficient. Similarly, the problem of poor sealing performance cannot be solved.

``Means for Solving the Problems'' In order to solve the above-mentioned conventional problems, this invention has been developed to fix the metal plates to be bonded above and below the metal core material to the bead portion of the bead forming portion that follows the outer periphery of the gasket hole. The bead substrate is divided into the substrate and the remaining flat portion substrate, and this bead substrate is integrally molded with the bead using an elastic metal plate with excellent heat deformation resistance, and the flat portion substrate is made of a general elastic metal plate. The present invention proposes a metal gasket which is formed from a plate and is formed by integrally bonding a bead substrate and a flat portion substrate to the upper and lower sides of a metal core material.

"Effect" The bead substrate that receives the load is made of an elastic metal plate with excellent heat deformation resistance, so the permanent deformation of the bead due to repeated loads under heat is reduced, ensuring durable elastic pressure contact force. be done.

As a result, the elastic pressure sealing properties of the bead are maintained for a long time, gas leakage is reliably prevented, and only the flat part of the bead board is replaced with an expensive elastic metal plate with excellent heat deformation resistance. Since this uses inexpensive metal materials, it is possible to ensure appropriate surface pressure while reducing the overall material cost.

``Example'' Below, an example of this invention shown in the drawings will be described. A metal gasket 1 has a bead portion substrate 3 formed with a bead 2 having an arched cross section in the middle in the width direction, and a bead portion substrate 3 formed into a flat plate shape. Both the flat part substrate 3' and the flat part substrate 3' are joined together by overlapping each other on top and bottom of a metal core material 4 made of an inexpensive general metal plate such as an iron plate.

The bead portion substrate 3 is bonded to the bead portion of the metal gasket 1, and is made of a material that maintains elasticity when heated at high temperatures, has high heat deformation resistance, and is less likely to cause permanent deformation under deformation loads, for example, has high yield strength.
It is formed from an expensive elastic metal plate such as SUS631 into a narrow plate that follows the outer periphery of the gasket hole.

The flat part substrate 3' is to be bonded to the flat part of the metal gasket 1 other than the bead part, and is made of a common inexpensive elastic metal plate such as stainless steel or SPC iron plate, which has poor heat deformation resistance.
It is formed into a plate shaped like the flat part around the .

Therefore, by freely selecting the thickness of the bead portion substrate 3, the desired elasticity of the bead 2 can be obtained and appropriate surface pressure can be secured, and the bead portion substrate 3 is made thinner than the flat portion substrate 3'. Since the plate thickness of the bead part base plate 3 can be made thinner, when the bead 2 of the bead part base plate 3 is crushed by the cylinder block and the cylinder head, the clamping force is limited by the plate thickness of the flat part base plate 3', and the thickness of the bead part base plate 3 is reduced. It is also possible to prevent excessive deformation and further reduce permanent deformation.

When using the metal gasket 1 constructed as described above, the gasket 1 is installed between the cylinder block and the cylinder head with a predetermined tightening force.
Even if the cylinder block and cylinder head are repeatedly compressed due to thermal expansion, the bead base plate 3 is made of an elastic metal plate that is highly resistant to heat deformation and will not undergo permanent deformation under deformation loads. The bead 2 is less likely to cause permanent deformation and can maintain its restorability for a long time, and by arbitrarily selecting the thickness of the bead portion substrate 3, the desired elasticity of the bead 2 can be obtained, and the cylinder block and cylinder head can be Appropriate surface pressure can be ensured.

As a result, even when the tightening force decreases due to elongation of the cylinder block and cylinder head bolts or sagging of the bolt seating surface when hot, the gasket seals reliably, and the sealing performance of the gasket is the best, especially when the engine is cooled. It is possible to reliably prevent gas leakage at the time of starting when the engine temperature is low, and is extremely effective as a cylinder head gasket for engines that become hot under load, such as air-cooled single-cylinder high-output engines.

Note that if a soft sealant is applied to the upper and lower surfaces of the gasket 1, the sealing performance can be further improved.

``Effects of the invention'' As described above, according to this invention, the metal plates to be joined on the upper and lower sides of the metal core material are divided into a bead portion substrate made of an elastic metal plate with excellent heat deformation resistance and formed with beads. Since it is bonded to the top and bottom of the core material, it is possible to reduce permanent deformation of the bead due to repeated loads during heat, ensure durable elastic pressure welding force, and allow the thickness of the bead board to be adjusted as desired. By selecting the bead, it is possible to obtain the desired elasticity of the bead and ensure appropriate surface pressure to the cylinder block and cylinder head, thereby reliably preventing gas leakage, especially gas leakage when starting the engine. can.

Since the thickness of the bead portion substrate is made thinner than that of the flat portion substrate, when the bead of the bead portion substrate is crushed by the cylinder block and cylinder head, the clamping force is limited by the plate thickness of the flat portion substrate, and the bead Permanent deformation can also be reduced by preventing excessive deformation.

In addition, only the partial bead substrate is made of an expensive elastic metal plate with excellent heat deformation resistance, and the flat portion is made of an inexpensive metal material, which reduces the overall material cost and is economical. .

[Brief explanation of drawings]

FIG. 1 is a partial vertical cross-sectional view showing an embodiment of this invention, and FIG. 2 is a partial vertical cross-sectional view of a conventional metal gasket. 1...metal gasket, 2...bead, 3...
Bead board, 3'...Flat part board.

Claims (1)

[Scope of utility model registration request] A bead part substrate formed in a shape that follows the outer periphery of the gasket hole is made of an elastic metal plate with excellent heat deformation resistance and has a bead bulging out in an arch shape in cross section, and is bonded to a flat metal core material. A metal gasket characterized in that a flat part substrate made of a general elastic metal plate thicker than the bead part substrate is joined to the upper and lower parts of a metal core material other than the part where the bead part substrate is joined.