JPH0236291A - Gasket material and head gasket using said material - Google Patents

Abstract

PURPOSE:To obtain a gasket material, good in water and oil resistance and excellent in sealing properties without causing oil collapse, grommet breakage, etc., by bonding expandable graphite to both sides of a reinforcing core plate consisting of heat-resistant fibers with a resin. CONSTITUTION:The objective gasket material obtained by bonding plain expandable graphite sheets having preferably 0.05-0.07mm thickness to both sides of a reinforcing core plate, consisting of heat-resistant fibers, such as glass, carbon, phenolic resin or aramid fibers, and having preferably 0.05-0.5mm thickness with a resin consisting of a thermosetting resin, such as epoxy, phenolic, furan or polyimide resin. The above-mentioned material is punched into the form of a head gasket and the peripheral part of an opening in the resultant formed body is then coated with a heat-resistant resin to produce the head gasket.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a graphite gasket material and a head gasket using the same.

(Prior art) Graphite gaskets generally used in internal combustion engines are made of highly developed crystal structures such as natural graphite, Quiche graphite, and pyrolytic graphite, as shown in Japanese Patent Publication No. 54-33799. The resulting graphite is acid-treated with a strongly oxidizing treatment solution such as a mixture of concentrated sulfuric acid and nitric acid, or concentrated sulfuric acid and potassium permanganate to generate a graphite intercalation compound, which is then washed with water and rapidly heated to produce a graphite crystal in the C-axis direction. Expanded graphite sheets are used, which are made by cold processing graphite particles that have been expanded to have a worm-like shape and have compression recovery properties. 0.15mm thick with 9 circular protrusions to provide the strength of a conventional graphite head gasket
Expanded graphite sheets are rolled onto both sides of a ~0.25m metal reinforcing core plate using the above protrusions and fixed to obtain a gasket material, which is punched into a gasket shape, and grommets and grommets are added around the combustion chamber. A thin metal plate called...
The mainstream is a tome-like configuration. This grommet has a high density in the part surrounded by the grommet (grommet part), and when the gasket is assembled, the grommet part has a high surface pressure, which functions to seal combustion gas and prevent graphite from flowing into the combustion chamber.

(Problems to be Solved by the Invention) However, in the conventional Herad gasket described above, surface pressure is concentrated on the circular protrusion of the metal reinforcing core plate used to provide strength to the gasket.

Gasket materials are not resistant to water or oil, such as water leakage under harsh conditions, or oil penetrating into graphite parts around oil entry, which can cause the graphite parts to collapse (also called oil collapse). Sealability was not sufficient. Furthermore, in the Herad gasket mentioned above, since the grommet is in contact with the cylinder head and cylinder block, the curved portion where work hardening is large due to deformation of the grommet is susceptible to repeated loads due to explosions, shearing force due to the difference in expansion between the cylinder block and cylinder head, etc. The drawback was that problems such as grommet cracking and combustion gas leakage occurred during normal operation.

An object of the present invention is to eliminate the above-mentioned drawbacks, and to provide a gasket material and a head gasket that have good water resistance, oil resistance, excellent sealing properties, and are free from oil collapse, grommet cracking, etc.

(1! I! Rounding Means for Solving Problem) The present invention relates to a gasket material formed by bonding expanded graphite sheets with resin to both sides of a reinforcing core plate made of heat-resistant fibers, and a bed gasket using the gasket material.

The reinforcing core plate made of heat-resistant fiber used for the gasket material is cloth or mat made of glass rutted fiber, carbon fiber, phenol resin fiber, aramid fiber, or the like. As for the material, glass fiber is preferable in terms of cost.

Among cloth and mat, cloth is preferable because graphite enters the cloth grains when adhering to the expanded graphite sheet, resulting in better bonding with the expanded graphite sheet and better oil resistance and water resistance. The thickness of the reinforcing core plate is preferably 0.05 to 0.5 mm. If it is too thin, it will be difficult to handle and adhere to the expanded graphite sheet, and if it is too thick, the adhesiveness to the expanded graphite sheet will not improve and the airtightness will not improve either.

The expanded graphite sheet is not particularly limited as long as it is made from expanded graphite, but a Blaine sheet with a thickness of 0.05 to 0.7 mm is preferable. If it is too thin, it is difficult to handle; if it is too thick, it is expensive and the sheets tend to peel off.

The resins used to bond the reinforcing core plate and expanded graphite sheet are epoxy resin, phenol resin, and furan resin.

A face made of thermosetting resin such as polyimide resin is preferred.

The adhesive may be applied to the reinforcing core plate and/or the expanded graphite sheet and then crimped with a press, but the expanded graphite sheet is laminated on both sides of a prepreg in which the reinforcing core plate is pre-impregnated with the festival.

It is preferable to pass the adhesive through a hot pressure roll or to press it with a hot press because the adhesion will be sufficient and the adhesion work will be easy.

The gasket material obtained as described above is punched into a head gasket shape using a press to obtain a molded body. The opening in the head gasket is the combustion chamber.

These are oil and water holes, and expanded graphite sheets or metal foils are glued around these openings, especially around the combustion chamber. Cover with heat-resistant resin. A thin metal plate coated with a heat-resistant resin on the surface or both surfaces having a convex portion around the opening on one side of the molded body is attached with the convex portion facing outward to form a head gasket.

In order to attach an expanded graphite sheet or metal foil to the periphery of the combustion chamber or the like, for example, the above-mentioned resin face is used for adhesion. The expanded graphite sheet used for pasting is the same as that used for the gasket material.

It is preferable to impregnate the resin face in advance and bond it by thermocompression. The thickness of the expanded graphite sheet is appropriately set according to the designed surface pressure of the surrounding area such as the combustion chamber. The metal foil is not particularly limited, but aluminum foil or steel foil is preferable, and the thickness is 25~25cm.
100 μm is preferred.

Further, when covering the peripheral portion of the combustion chamber or the like with a heat-resistant resin, it is preferable to use a thermosetting resin such as a fluororesin, a silicone resin, or a polyimide resin.

As for the coating method, it is preferable to mask areas other than the peripheral areas such as the combustion chamber, apply a solution or dispersion of the resin to the molded body by air spraying, and then heat-treat the molded body. The thickness of the coating is appropriately selected depending on the design surface pressure of the surrounding areas such as the combustion chamber.

The metal thin plate attached to one side of the molded body is preferably a stainless steel plate from the viewpoint of spring properties and corrosion resistance, and the plate thickness is 0.
．． 15-0.3- is preferable. A combustion chamber, a water hole, and an oil filler are punched out from the thin metal sheet using a press, and the surrounding areas of these holes are drawn into convex portions (called beads) as shown in 6 in Figure 3. It is formed. The bead has a width of 1.
5 to 3 ann and a height of 0°1 to 0.5M are preferred. The heat-resistant resin that coats the beaded surface or both surfaces of the thin metal plate to provide good sealing properties is preferably a thermosetting resin such as fluororesin or silicone resin. Fold back part or all of the end of this thin metal plate in the direction opposite to the bead.

The folded part is fixed to the molded body to form a head gasket.

(Function) The strength of the gasket material is maintained by adhering an expanded graphite sheet to a reinforcing core plate made of heat-resistant fibers with resin instead of the circular protrusions on the conventional metal reinforcing core plate. As a result, when used as a head gasket, surface pressure is averaged and sealing performance is improved, such as eliminating water leakage.

In addition, the areas around the combustion chamber, oil fill and water holes that require high surface pressure in the head gasket, especially the areas around the combustion chamber, should be covered with expanded graphite sheets or metal foil, or heat-resistant It is coated with resin or laminated with thin metal plates with beads and attached to the cylinder block and cylinder head to increase the surface pressure when tightening the head gasket and seal out combustion gas, oil, and water.

(Example) Next, the present invention will be explained in detail.

Example 1 A phenolic resin varnish (VP231, Hitachi Chemical Co., Ltd.) was applied to a reinforcing core plate of plain-woven glass cloth (Fuji Fiberglass Co., Ltd., FECR-1311) with a thickness of 0.16 mm on both upper and lower surfaces of the prepreg. .38m, density 1
．． Expanded graphite sheets (manufactured by Hitachi Chemical Co., Ltd., trade name: CarboFit) of 0g/ai" were laminated and hot-pressed at 180°C to obtain a gasket material with a thickness of 0.8 mm. This gasket material was punched and pressed. After punching into the shape shown in FIG. 1, a 4-width punch impregnated with 2% by weight of the VP231 and having a thickness of 0.4 m was placed at a distance of 0.4 m from the periphery of the combustion chamber 3.
25 am.

Density 1g/c! A head gasket having a bonded portion 4 shown in the cross-sectional view of FIG. 2 was obtained by bonding ring-shaped carboxylates of FF3 using a hot pressure press. In FIG. 2, 1 is a reinforcing core plate, and 2 is an expanded graphite sheet.

Example 2 In place of the glass cloth in Example J, a thickness of 0.1
-Glass cloak (manufactured by Nippon Vilene, EP401
The thickness was 0.8 in the same manner as in Example 1 except that 2) was used.
[A gasket material of mI+ was obtained.

Example 3 After punching the gasket material obtained in Example 1 into the gasket shape shown in FIG. 1 using a punching press, the combustion chamber 3 was punched out.
Leave a 4-width part located 0.4 am away from the 0 periphery and mask the other parts.

Dispersion of tetrafluoroethylene resin (manufactured by Daikin Industries).

Polyflon TC-7400 (trade name) was applied by air spray, and then heat treated at 180° C. to obtain a Helad gasket with a coating layer of 40 μm thick.

Comparative Example 1 Aluminum foil with a thickness of 0.1 mm was used as a reinforcing core plate, and an acrylic ester adhesive (Hitachi Chemical FI, BT-1) was applied to both the top and bottom surfaces of this aluminum foil, and the thickness of the aluminum foil was 0.1 mm. A gasket material having a thickness of 0.8 mm was obtained by laminating carboxylates with a thickness of 0.38 mm and a density of 1.0 g/am'' and press-bonding them using hot pressure molding.

Comparative Example 2 Thickness 0, 2 with many circular protrusions at Z5ag pitch
On both sides of thin metal plate (SPCC material), thickness 0, 7
trm with a density of 1.0 g/am'' were laminated and press-bonded at a pressure of 300 kg/am'' to obtain a gasket material with a thickness of 1.2 mm. After punching this gasket material into the shape shown in Figure 5 using a punching press, a 0.2 on metal thin plate (SUS310S) with a width of 4 cabinets was placed around the periphery of the combustion chamber 3 as shown in Figure 6. A head gasket having a grommet 5 attached in the shape of an eye was obtained.

Example 4 A 0.3 am thick, 1.5 a/at? The carboxylates were laminated and molded under hot pressure at 150°C to a thickness of 0.
8 m of gasket material was obtained. After punching this gasket material into the shape shown in FIG.
A head gasket having a bonded portion 4 shown in FIG. 2 was obtained by heat-pressure bonding a number of aluminum foils having a size of 50 mm with the phenol resin VP231.

Example 5 After punching the nine gasket materials obtained in Example 1 into the shape of a head gasket using a punching press, a combustion chamber 3. The molded body had an oil filler 8 and a water hole 7. On the other hand, the combustion chamber was made by pressing a stainless steel plate (8US-301) with a thickness of 0.2 mm.

In addition to punching out oil and water holes, @
A bead of 2IIlu+ and a height of 0.3 mm was formed, and the end of the plate was folded 180° in the direction opposite to the bead.

Next, a dispersion of tetrafluoroethylene resin (Polyflon TC-7400, manufactured by Daikin Industries, Ltd.) was sprayed onto the surface having the beads, and then heat treated at 180° C. to form a coating layer with a thickness of 0.05 mm. Next, the stainless steel plate was laminated on a molded body with the surface without the coating layer facing inside, and the bent end portion was further turned inside, and a stainless steel plate was fixed to the molded body to obtain a head gasket.

Figure 3 is a plan view of this head gasket, and Figure 4 is a top view of this head gasket.
It is a BB sectional view of the figure. In the figure, 9 is a stainless steel plate, 6 is a bead thereof, 1 is a reinforcing core plate, and 2 is an expanded graphite sheet.

Example 1 above. Example 2. Example 4. Regarding the gasket materials obtained in Comparative Example 1 and Comparative Example 2.

The oil resistance, water resistance and leakage characteristics were measured and the values shown in Table 1 were obtained.

In Table 1, the oil resistance property refers to the test piece of 5oxso (W) made from gasket material.
It represents the recovery rate after immersing in oil at 150°C for 5 hours, and water resistance is a test piece of 50 x 50 (III) immersed in an ethylene glycol aqueous solution of 50% by weight.
It represents the recovery rate after immersion at ℃ for 5 hours. The recovery rate is determined by compressing the test piece impregnated with the above-mentioned 9N113 oil or ethylene glycol aqueous solution using a 2Z6mmφ penetrator, and the thickness of the compressed part when a preload of 7 kg/an'' is applied is Tl. Main load: 350kg/cr
T for the clarity when applying rP! 2nd time again 7 kg/c
The thickness when a load of m'' is applied is defined as T3, and the recovery rate R is calculated from the 9th equation.

The leakage characteristics were measured using a test piece 12 with inner diameter d=34ann and outer diameter D=50- shown in FIG. 7 for the example and comparative example.
Create 5 pieces each, hold them with jigs 13 and 13', and MI
Tighten with O's Porto 14 with a surface pressure of 80 kg/am.
A 50% by weight aqueous ethylene glycol solution was introduced into the space 16 from the liquid inlet 15, internal pressure was applied, and the presence or absence of leakage or bleeding was checked. Internal pressure is 0, s kg/am” interval is 8
The pressure was increased to kg/am2 and maintained at each pressure for 30 minutes.

Table 1 From Table 1, it can be seen that the examples are different from the comparative examples, and the koji 3
Excellent recovery rate after immersion in oil and ethylene glycol.
Also, Example 1. 2. A comparison of No. 3 shows that cloth is superior to mat as the reinforcing core plate. Furthermore, it is clear that the examples have no problems with respect to leakage characteristics.

Next, Example 1. 3. 4. The head gaskets obtained in Comparative Example 2 and Comparative Example 2 were assembled into an engine.

When a pliers durability test was conducted under full load for 200 hours continuously twice, the hemlock gasket of Comparative Example 2 had one grommet crack and one spot of antifreeze bleeding in the first test, and two grommet cracks in the second test.

One spot of oil bleeding was seen, but the example was gas,
There were no antifreeze or oil leaks or any problems.

(Effects of the Invention) According to the present invention, by using heat-resistant fibers in the reinforcing core plate,
The surface pressure becomes even and the sealing effect against water is enhanced. Furthermore, by using a resin to bond the reinforcing core plate and the expanded graphite sheet, the bondability between the reinforcing core plate and the expanded graphite sheet is maintained, and oil and water resistance can also be improved. Furthermore, by bonding an expanded graphite sheet or metal foil to the surrounding area of the gasket, such as the combustion chamber, coating it with a heat-resistant resin, or pasting a metal thin plate with beads,
Improved sealing against combustion gases, water and oil.

[Brief explanation of the drawing]

1 and 3 are plan views of a head gasket according to an embodiment of the present invention, and FIGS. 2 and 4 are A of FIG. 1, respectively.
-A sectional view, BB sectional view in FIG. 3, and FIG. 5 is a plan view of a conventional head gasket. FIG. 6 is a sectional view taken along the line C--C in FIG. 5, and FIG. 7 is a schematic diagram showing a test method for leakage characteristics. Explanation of symbols 1...Reinforcement core plate 3...Combustion chamber 5...Grommet 7...Water hole 9...Stainless steel plate 13...Jig 15...Liquid inlet 2... Expanded graphite sheet 4...Adhesive part 6...Pead 8...Oil filler 12...Test piece 14...Bolt 16...Space No./prisoner/3rd eye 70 g44 圀

Claims (1)

[Claims] 1. A gasket material made by bonding expanded graphite sheets with resin to both sides of a reinforcing core plate made of heat-resistant fibers. 2. Glue an expanded graphite sheet or metal foil with resin around the opening of a molded body made by punching out a gasket material in the shape of a head gasket, with expanded graphite sheets adhered with resin to both sides of a reinforcing core plate made of heat-resistant fibers. head gasket. 3. A head gasket made by punching out a gasket material into the shape of a head gasket from a gasket material in which expanded graphite sheets are bonded with resin to both sides of a reinforcing core plate made of heat-resistant fibers, and covering the periphery of the opening with a heat-resistant resin. 4. A convex part is provided around the opening on one side of a molded body made by punching out a gasket material in the shape of a head gasket, in which expanded graphite sheets are bonded with resin to both sides of a reinforcing core plate made of heat-resistant fibers, and the convex part is formed around the opening. A head gasket consisting of a thin metal plate coated with heat-resistant resin on the surface or both sides of the head gasket, with the convex portion facing outward.