JPH041232B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a gasket assembly with excellent sealing properties and a method of manufacturing the same.

BACKGROUND OF THE INVENTION Gaskets comprising elastomeric sealing beads on the surface of a base plate are well known (see, eg, US Pat. No. 3,794,333).

However, laminated head gaskets having a central metal core and one or two topsheets with sealing beads are gaining importance in sealing internal combustion engines. The sealing beads are arranged in a general pattern and are often applied by silk-screening.

In addition to the sealing beads, the topsheet typically includes
It is necessary to apply a coating or surface treatment,
This prevents fretting, abrasion, misalignment, or breakage of the sealing bead. However, the above surface treatments for protecting the topsheet have the disadvantage of making it difficult to adhere the sealing bead to the topsheet. Therefore, a method is often adopted in which a sealing bead is provided on the top sheet of the gasket and then surface treatment is performed. At this time,
In some cases, the sealing bead may not be surface treated. This approach is much more cumbersome, expensive, and sometimes less effective than applying a sealing bead to the topsheet after surface treatment.

In this sense, gaskets such as those described in U.S. Pat. No. 3,794,333 without any surface treatment on the gasket surface are economically advantageous, but sealing beads applied to the outer surface of the gasket are advantageous. is exposed to harsh external environments and its durability is impaired.

The present invention has been devised in this technical background, and in use, the sealing bead is protected from direct contact with the surface to be sealed, and compared to the prior art, The objective is to obtain a gasket assembly with excellent sealing properties.

Means for Solving the Problem The object is to provide a gasket assembly which is disposed between and compressed between the surfaces of a pair of members to be sealed, one of which is made of compressible material. a pair of gasket layers laminated to each other, the other being a metal layer, and a sealing bead disposed between and wrapped between the gasket layers, the sealing bead being disposed between the gasket layers, the other being a metal layer; By providing a gasket assembly including a sealing bead formed of a deformable non-compressible elastomer and at least one opening in the gasket assembly around which the sealing bead is disposed. It will be achieved. Note that in this specification, incompressibility refers to the property of deforming without changing volume when applying pressure (or squeezing force), and for example, rubber is an incompressible material. Conversely, compressible materials are typically materials that have a large number of voids within them. Furthermore, the term "incompressible elastomer" as used herein also includes "virtually incompressible" elastomers.

The gasket assembly of the present invention includes a head gasket assembly for an internal combustion engine. In this case, the gasket assembly is arranged between the head and the engine block. The gasket assembly has at least one combustion opening and defines a plurality of holes for oil, water, etc.
be done.

A sealing bead of elastomeric material provided in a pattern between a pair of gasket layers surrounds at least one opening to improve the sealing effect of the gasket assembly in the sealing bead zone. Increase. The gasket layer serves to provide a cavity within which the elastomeric sealing bead is constrained, thus acting as if the sealing bead were an attached "O-ring."

When such a head assembly is placed in compression between the head and block, the sealing bead is protected from direct contact with the head and block, thereby protecting it from friction, heat and extrusion.

Most preferably, the sealing bead is adhered to the metal layer and the surface layer as one gasket layer is adhesively adhered to the metal layer by pressure in a zone closely surrounding the sealing bead. This processing operation limits lateral movement of the sealing bead and hardens the sealing bead when the gasket assembly is placed in compression. Furthermore, it compresses and densifies the surface layer, one of which is the gasket layer.

According to a second feature of the invention, there is provided a method of fabricating a gasket assembly disposed between the surfaces of a pair of members to be sealed, comprising: forming a sealing bead of incompressible elastomeric material into a gasket assembly; disposing and curing a first gasket layer of metal, and placing a surface layer of compressible material as a second gasket layer over the first gasket layer and the sealing bead, thereby forming a gasket assembly. wrapping a sealing bead positioned around at least one aperture between a first gasket layer and the surface layer; and adhering the surface layer as a second gasket layer to the first gasket layer under compression. and compressing the surface layer to densify it in the region of the sealing bead.

EXAMPLE Referring now to the drawings, a diesel engine 1 having a head 2 and a block 3 is illustrated as using a gasket assembly 10 specifically formed and configured for use therein. There is. Block 3 is shown as having a cylinder opening 4, a cylinder sleeve 5 and a piston 6. The engine 1 has a plurality of combustion cylinders 4, one of which is shown in FIG.

Gasket assembly 10 is a laminate including a generally flat, solid and wide metal core (metal layer) 14;
A pair of generally flat wide surface sheets (surface layers)
16. metal core 14
has upper and lower planes, such as surface 18, to which topsheet 16 is laminated. Other surface treatments such as stamping, embossing or etching may also be applied to the metal core at desired locations.

The topsheet 16 may be made of a compressible gasket surface synthetic material and reinforced with fibers. The topsheet is laminated to surface 18 with an adhesive, such as a suitable heat-reactive adhesive, or mechanically. Suitable heat-responsive adhesives include phenolic nitrile rubber and polybutyral rubber, which are suitable for initial use on the surface of the topsheet. The topsheet may incorporate asbestos glass fibers or other suitable fibrous materials and may utilize elastomers such as nitrile, neoprene or polyacrylic as a binder. Often, the binder comprises about 15% to about 25% of the top sheet, depending on whether asbestos fibers or other organic or inorganic fiber fillers are used. In the illustrated embodiment, topsheet 16 is approximately 0.64 mm (approximately 0.025 inch).
However, this dimension can of course be changed depending on the location of use. The topsheet generally resists oil and coolant degradation, maintains torque, minimizes extrusion, and has thermal resistance.

Gasket assembly 10 is perforated with a combustion opening 20 and holes such as bottle holes 22 and a plurality of oil and water passageways 24. The metal core may be made of cold rolled steel and its thickness may vary depending on the application. Approximately 0.15mm (0.006 inch) to 1.3mm (approximately
Thicknesses up to 0.050 inch are typical. The surface 18 of the metal core may be phosphated to improve adhesion.

In the illustrated embodiment, the metal core 14 has an embossing 21 surrounding the combustion aperture 20 . The gasket assembly 10 is then provided with an annular sheath 25 secured around the embossing portion 21 in a known manner to supplement the sealing of the combustion opening.

In this embodiment, the desired sealing beads 26 are provided and fixed on one or both surfaces of the metal core. The patterned sealing bead 26 has a series of sealing beads 28, 30 formed in zones requiring increased sealing force at the point of application in which the gasket assembly 10 is used. Typically, sealing bead 28 is formed to substantially surround the combustion opening and sealing bead 30 is formed to substantially surround the water and oil passageway between the associated head and block. Sometimes, because of the shape of the head and block, and because of the placement of the bolt holes, or for other design reasons, the bead shape is truncated or fully circular, as shown in Figures 1 and 3. is desired.

In the illustrated embodiment, the sealing bead 26 forming the sealing beads 28 and 30 is typically formed of a sealing bead by a silk screen process, preferably as described in U.S. Pat. No. 3,477,867. This can be made with silicone encapsulant deposited at a height ranging from about 0.15 mm (about 0.006 inch) to about 0.2 mm (about 0.008 inch). The silicone sealant may be a two-component thermosetting liquid silicone. When the sealing bead is placed and bonded to a dimensionally stable and highly adhesive metal core, the sealing bead can be placed in precise and precise alignment from gasket assembly to gasket assembly.

A sealing bead is placed on the surface 18 of the metal core 14.
After being cured by methods known above, the compressible topsheet 16 is placed over the metal core and the sealing beads are laminated to the metal core with a conventional intervening adhesive layer. The adhesive bonds the topsheet to the metal core, and when the metal core and topsheet are laminated by pressure, the topsheet is compressed and densified in the zones of the sealing beads. Phosphate treatment of metal core,
Or, if other suitable treatments are applied to increase the adhesion, the top sheet 16 will be immediately and firmly adhered to the surface of the metal core, and depending on the sealing material constituting the sealing bead 26, the top sheet 16 may or may not adhere to sealing beads 28, 30. In either case, the topsheet and metal core wrap and surround the sealing bead.

Preferably, the face sheet is secured to the surface 18 of the metal core with a zone Z closely surrounding the sealing bead, thereby confining the sealing bead and compressing the sealing bead when the gasket assembly is placed in compression. prevent lateral movement of the top. Wrapping the sealing bead has many advantages. Particularly when the bead is formed of an elastomer, it prevents migration or extrusion of the sealing bead and increases the load carrying capacity of the sealing bead. When the top sheet and the metal core surround the sealing bead very closely, it not only prevents extrusion, but also prevents the same sealing bead from showing if exposed to the surface as in conventional a somewhat stiffer load-deflection curve (i.e., deflection characteristics) than would be
It has a tendency to show. Therefore, under compression,
The sealing bead and its overlying surface are now more compact than previously possible, since the compression of the sealing bead is to be limited to a slight embedding in the lower (inner surface) surface of the top sheet without causing extrusion. As a seal under larger compressive loads,
It can work more effectively.

When using a gasket with a sealing bead on the surface, it is first necessary to embed the sealing bead almost completely into the face sheet before applying the load to other parts of the gasket. However, with the gasket assembly of the present invention that relies on precompression in the wrapped bead zone, loading in areas other than the bead zone may occur almost immediately. Sealing occurs when the sealing bead material is substantially incompressible, such as elastomers such as silicone and other rubbers, and when the gasket assembly is compressed in the sealing bead zone during use or during manufacturing. The surface material overlapping the bead becomes denser,
Moreover, it becomes a porous body that is less porous than the original porous body (that is, the pores are submerged due to compression) and becomes impermeable to fluid. The surface material of this zone therefore has enhanced sealing and physical properties unlike the area adjacent to the sealing bead zone.

In FIG. 5, the gasket assembly is illustrated prior to compression at the sealing bead and bead zone. However, during fabrication, the gasket assembly is preferably compressed in the indicated zone;
The topsheet is densified as shown in FIG.
Here, a silicone sealing bead 28 is shown embedded in the topsheet 16, and the topsheet in the bead zone is compressed. In FIG. 5, the amount of protrusion of the topsheet in the bead zone is approximately equal to the height Y of the sealing bead, but
In the figure, the amount of protrusion of the top sheet is approximately reduced as indicated by the height X. Preferably, the ratio of heights 1/
(Although it is set to 2 or less, this value is not strict, and in fact, it only needs to be about 1/2 or less).
In this way, the surface of the gasket assembly is more planar than one having a sealing bead on the surface.
Enhances the sealing properties of the gasket assembly over its entire surface.

Another advantage derived from the gasket assembly of the present invention is that it protects the sealing bead not only from extrusion but also from surface phenomena. This surface phenomenon includes the tendency of sealing beads to burst and disturb during use in engines, as well as during shipping, handling, and installation operations.
Such rupture may be due to the roughness of the surface to be sealed, where there is a high tendency for the sealing bead to split or crack due to the rough finish. Furthermore,
It is known that excessive heat tends to have an adverse effect on elastomeric sealing beads. As discussed, wrapping the sealing bead insulates it from thermal effects to a greater extent than when the sealing bead is on the surface of the gasket assembly. Additionally, scuff erosion of the sealing bead occurs in some circumstances. Surfaces can be treated to resist abrasion, but sealing beads such as silicone beads with erosion-resistant materials may be difficult to bond to the sealing beads with a suitable protective layer. Conventionally, it has been very difficult to treat.

Also related to the advantages of the method invention, when there are no sealing beads on the surface, without supplementing the treatment,
Thus, it is possible to easily and inexpensively apply anti-erosion coatings and other surface treatments to the entire surface without adding additional steps during the fabrication of the gasket assembly. By providing a sealing bead on the metal core, a special barrier coating on the top sheet is used to accelerate the curing of the bead material, such as silicone. This eliminates the need for pre-application (which is often presently required since the surface material itself tends to inhibit hardening of the bead material). In addition, the gasket assembly according to the present invention, which has a structure in which the sealing bead is wrapped in a top sheet, has a high load-bearing capacity of the sealing bead as described above.
It is possible to improve suppression of distortion of the cylinder head.

Although the sealing bead has been described as being made from a silicone elastomer, other elastomers and elastic materials can also be used, such as nitrile (polybutadiene nitruluri rubber) or neoprene rubber, flexible and rubber-modified epoxies. epoxies, or their compounds. Furthermore, since the sealing bead and face sheet cooperate in transmitting the sealing force in the bead zone, it is not necessary to use an elastic material such as an elastomer to effect the sealing at the point where the sealing occurs through the sealing bead. It is possible to consider the use of slightly harder materials that are less durable. Furthermore, according to the characteristic of the present invention in which the sealing bead is buried in the topsheet, the sealing compatibility of the topsheet surface to the head and block can be improved by a method that does not expose the sealing bead to the external surface as in the conventional method. It is possible to plan to improve the

In the embodiments described above, the sealing bead is bonded to the metal core and the topsheet is bonded to the metal core.
Depending on the materials used, it may be desirable to adhere the sealing bead to the topsheet during lamination.

[Brief explanation of drawings]

FIG. 1 is a top view of a gasket assembly embodying the principles of the present invention, FIG. 2 is a cutaway sectional view of a diesel engine using the gasket assembly shown in FIG. 1, and FIG. 4 is a cut away plan view of the metal core of the gasket assembly of FIG. 1 with a sealing bead added; FIG.
FIG. 5 is an enlarged sectional view taken along the line 5--5 of FIG. 4, and FIG. 6 is an enlarged sectional view of the portion of FIG. 5 which has been pre-compressed according to the present invention. be. 10...Gasket assembly, 14...Metal core, 1
6... Surface sheet, 18... Surface, 20... Combustion opening, 22... Bolt hole, 26, 28, 30...
...Sealing bead.

Claims (1)

[Claims] 1. A gasket assembly disposed between and compressed between the surfaces of a pair of members to be sealed, one of which is a layer of compressible material and the other of which is compressed. a pair of gasket layers laminated to each other, each of which is a metal layer, and a sealing bead disposed between the two gasket layers and wrapped between the two gasket layers, the sealing bead being deformable under compression. a sealing bead formed of a compressible elastomer, the sealing bead being disposed around the sealing bead;
and at least one opening in the gasket assembly. 2. both gasket layers are secured to each other in a region proximate and surrounding the sealing bead so as to prevent lateral shearing of the sealing bead when the gasket assembly is placed in compression; A gasket assembly as claimed in claim 1, which has a structure that prevents the gas from overflowing. 3. The gasket assembly of claim 1, wherein the gasket assembly has at least one opening completely surrounded by the sealing bead. 4. A third gasket layer formed of a compressible material and laminated to the metal layer; and a third gasket layer disposed between the third gasket layer and the metal layer and wrapped between the two gasket layers. and a second sealing bead of non-compressible material. 5 The surface layer is compressed in the sealing bead zone,
2. The gasket assembly according to claim 1, wherein the protrusion height of the surface layer on the sealing bead is less than 1/2 of the height of the sealing bead. 6. A method of fabricating a gasket assembly disposed between the surfaces of a pair of members to be sealed, the method comprising placing a sealing bead of non-compressible elastomeric material deformable under compression into a metal first disposing and curing a surface layer of a compressible material as a second gasket layer over the first gasket layer and the sealing bead; wrapping said sealing bead positioned around at least one aperture between a first gasket layer and said surface layer; and adhering said surface layer as a second gasket layer to a first gasket layer under compression. and then compressing the surface layer to densify it in the area of the sealing bead. 7. The surface layer as a second gasket layer is affixed to the first metal gasket layer in an area proximate and surrounding the sealing bead so that when the gasket assembly is placed in compression, 7. A method of making a gasket assembly as claimed in claim 6, including limiting lateral drift of said sealing bead.