JP2508802B2 - Head gasket - Google Patents

Description

TECHNICAL FIELD The present invention relates to a head gasket.

(Prior Art) Generally, a graphite gasket used in an internal combustion engine or the like is used as a material as disclosed in Japanese Patent Publication No. 54-33799.
The graphite intercalation compound is obtained by acid-treating graphite with a highly developed crystal structure such as natural graphite, Kishyu graphite, and pyrolytic graphite with a strong oxidizing treatment liquid such as concentrated sulfuric acid and nitric acid, or a mixture of concentrated sulfuric acid and potassium permanganate. There is used an expanded graphite sheet obtained by cold-working worm-shaped graphite particles having a compression-restoring property that are produced, washed with water, and then rapidly heated to expand in the C-axis direction of graphite crystals. A circular projection with a thickness of 0.15 to 0.25 mm in order to provide the strength of a conventional graphite head gasket.
The expanded graphite sheets are fixed on both sides of the metal reinforcing core plate by using the above-mentioned projections by roll processing to obtain a gasket material, which is punched into a gasket shape, and further, a thin metal plate called a grommet around the combustion chamber. The mainstream configuration is to attach eyelets. The grommet has a high density in the part surrounded by the grommet (grommet part), and the grommet part has a high surface pressure when the gasket is assembled, which serves to seal the combustion gas and also to prevent the inflow of graphite into the combustion chamber.

(Problems to be Solved by the Invention) However, the above-mentioned conventional head gasket is
The surface pressure is concentrated on the circular protrusions of the metal core plate used to increase the strength of the gasket, causing water leakage under harsh conditions, and oil permeating into the graphite part around the oil hole to cause graphite The quality of the gasket may not be enough (such as oil slump), and the sealability against water and oil as a gasket material was insufficient. Further, in the above-mentioned head gasket, since the grommet is in contact with the cylinder head and the cylinder block, the curved part that has a large work hardening due to the deformation of the grommet is in operation due to the repeated load due to the explosion, the shearing force due to the difference in expansion of the cylinder head and the cylinder head, etc. However, there were defects such as grommets cracking and leakage of combustion gas.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned drawbacks and to provide a head gasket having excellent water resistance and oil resistance, excellent sealing property, and free from oil slump and grommet cracking.

(Means for Solving the Problem) The present invention, in the peripheral portion of the opening of a molded body punched into a head gasket shape, a gasket material in which expanded graphite sheets are bonded with resin on both sides of a reinforcing core plate made of heat resistant fiber, A head gasket made by adhering expanded graphite sheet or metal foil with resin, a core material made of heat-resistant fiber, and a gasket material made by adhering expanded graphite sheets with resin on both sides. The head gasket made of heat-resistant resin and the reinforcing core plate made of heat-resistant fiber are bonded to both sides of the expanded graphite sheet with resin, and the gasket material is punched into the shape of the head gasket. A head formed by providing a convex portion on the peripheral portion of the portion and attaching a thin metal plate coated with heat-resistant resin on the surface or both surfaces on which the convex portion is provided, with the convex portion on the outside. Regarding gaskets.

As the reinforcing core plate made of heat-resistant fiber used for the gasket material, cloth or mat of glass fiber, carbon fiber, phenol resin fiber, aramid fiber or the like is used. The material is preferably glass fiber in terms of cost. In the case of cloth and mat, cloth is preferable because graphite penetrates into the cloth when adhering to the expanded graphite sheet, so that the bond with the expanded graphite sheet is improved and the heat resistance and water resistance are also improved. The thickness of the reinforcing core plate is 0.05-0.
5 mm is preferable. If it is too thin, it will be difficult to handle and bond it to the expanded graphite sheet, and if it is too thick, the adhesion to the expanded graphite sheet will not improve and the airtightness will not improve.

The expanded graphite sheet is not particularly limited as long as it is made of expanded graphite as a raw material, but a plain sheet having a thickness of 0.05 to 0.7 mm is preferable. If it is too thin, it will be difficult to handle, and if it is too thick, it will be expensive and peeling will easily occur between the sheets.

The resin used for bonding the reinforcing core plate and the expanded graphite sheet is preferably a varnish of a thermosetting resin such as an epoxy resin, a phenol resin, a furan resin or a polyimide resin. For the adhesion, the varnish may be applied to the reinforcing core plate and / or the expanded graphite sheet and then pressure-bonded by pressing. Passing through a roll or press-bonding with a hot press is preferable because the adhesion is sufficient and the adhesion work is easy.

The gasket material obtained as described above is punched into a head gasket shape by a press to obtain a molded body. The openings in the head gasket are the combustion chamber, oil holes, and water holes. The expanded graphite sheet or metal foil is adhered to the periphery of these openings, especially the periphery of the combustion chamber with resin, or heat resistant resin is coated. Alternatively, a metal thin plate having a convex portion on the periphery of the opening or the like on one side surface of the molded body or a metal thin plate coated with a heat-resistant resin on both sides is attached with the convex portion on the outside to form a head gasket.

To attach the expanded graphite sheet or the metal foil to the periphery of the combustion chamber or the like, for example, the resin varnish described above is used.
The expanded graphite sheet used for sticking may be the same as that used for the gasket material, and it is preferable to thermocompress the one that has been impregnated with the resin varnish in advance. The thickness of the expanded graphite sheet is appropriately set according to the design surface pressure of the peripheral portion such as the combustion chamber. The metal foil is not particularly limited, but aluminum foil or copper foil is preferable, and the thickness is preferably 25 to 100 μm.

When the heat-resistant resin is coated on the periphery of the combustion chamber, it is preferable to use a thermosetting resin such as fluorine resin, silicon resin, or polyimide resin. It is preferable to heat-treat after coating the resin solution or dispersion with an air spray on the molded body masked with. The thickness to be coated is appropriately selected according to the design surface pressure of the peripheral part such as the combustion chamber.

The thin metal plate attached to one side of the molded body is preferably a stainless steel plate in terms of springiness and corrosion resistance, and the plate thickness is
0.15-0.3 mm is preferable. The thin metal plate has punched out the combustion chamber, water holes, and oil holes by pressing, and the peripheral portions of these holes are formed into convex portions (called beads) as shown in FIG. 3 by drawing. It Bead width is 1.5 to 3 mm
And a height of 0.1 to 0.5 mm is preferable. The heat-resistant resin that covers the beaded surface or both surfaces of the thin metal plate to improve the sealing property is preferably a thermosetting resin such as fluorine resin or silicon resin. A part or all of the end of this thin metal plate is folded back in the direction opposite to the bead, and the folded part is fixed to the molded body to form a head gasket.

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

In addition, instead of installing grommet around each of the combustion chamber, oil hole and water hole that require high surface pressure in the head gasket, especially around the combustion chamber, an expanded graphite sheet or metal foil is bonded or a heat resistant resin is used. Cover or attach a thin metal plate with a bead and attach it to the cylinder block and cylinder head to increase the surface pressure when tightening the head gasket and seal combustion gas, oil and water.

(Example) Next, the Example of this invention is described.

Example 1 A 0.16 mm thick plain woven glass cloth (Fuji Fiber Glass, FECR-1311) reinforcing core plate coated with a phenol resin varnish (Hitachi Chemical Co., Ltd., VP231) was applied on both upper and lower surfaces of the prepreg to give a thickness of 0.38 mm. Then, expand graphite sheets with a density of 1.0 g / cm ³ (Hitachi Chemical Co., Ltd., product name Carbofit) are laminated, 1
Hot pressing was performed at 80 ° C to obtain a 0.8 mm thick gasket material. After punching this gasket material into the shape shown in Fig. 1 by a punching press, it is impregnated with 2% by weight of VP231 in a width of 4 mm at a position 0.4 mm away from the periphery of the combustion chamber 3 and a thickness of 0.
A ring-shaped carbofit having a density of 25 mm and a density of 1 g / cm ³ was bonded by a hot press to obtain a head gasket having a bonding portion 4 shown in the sectional view of FIG. In FIG. 2, 1 is a reinforcing core plate and 2 is an expanded graphite sheet.

Example 2 Instead of the glass clock in Example 1, the thickness is 0.1 m.
A gasket material having a thickness of 0.8 mm was obtained in the same manner as in Example 1 except that m glass kettle (manufactured by Japan Vilene, EP4012) was used.

Example 3 The gasket material obtained in Example 1 was punched into a gasket shape shown in FIG. 1 by a punching press, and then a 4 mm wide portion 0.4 mm apart from the periphery of the combustion chamber 3 was left. Is masked, and a dispersion of tetrafluoroethylene resin (manufactured by Daikin Industries, trade name Polyflon TC-7400) is applied by air spraying, and then heat treated at 180 ° C to form a coating layer with a thickness of 40 µm. A head gasket is obtained.

Comparative Example 1 A 0.1 mm thick aluminum foil was used as a reinforcing core plate, and an acrylic ester adhesive (manufactured by Hitachi Chemical Co., Ltd., BT-1) was applied to both upper and lower surfaces of this aluminum foil, and then a thickness of 0.38 mm, Density 1.0g / cm ³
Carbofits of No. 1 are laminated and thermocompression-bonded to obtain a thickness of 0.
8mm gasket material was obtained.

Comparative Example 2 Carbofit with a thickness of 0.7 mm and a density of 1.0 g / cm ³ was laminated on both sides of a 0.2 mm thick thin metal plate (SPCC material) with 2.5 mm pitches and a large number of circular protrusions, and 300 kg / cm ² Press-pressing was applied under pressure to obtain a 1.2 mm thick gasket material. After punching this gasket material into the shape shown in Fig. 5 with a punching press, a 0.2 mm thin metal plate (SUS310S) is formed in a 4 mm width around the periphery of the combustion chamber 3 as shown in Fig. 6. A head gasket having the attached grommet 5 was obtained.

Example 4 A 0.2 mm thick glass cloth-epoxy resin prepreg (GE-61NS manufactured by Hitachi Chemical Mold Co., Ltd.) was laminated with a carbofit having a thickness of 0.3 mm and a density of 1.5 g / cm ³ at 150 ° C.
Then, it was hot pressed to obtain a gasket material having a thickness of 0.8 mm. After punching this gasket material into the shape shown in FIG. 1 by a punching press, an aluminum foil with a width of 5 mm and a thickness of 50 μm is placed at a position 1 mm away from the periphery of the combustion chamber 3 by using the phenol resin V.
Heat-adhesion bonding was performed with P231 to obtain a head gasket having the bonding portion 4 shown in FIG.

Example 5 The gasket material obtained in Example 1 was punched into a head gasket shape by a punching press, and then a molded body having a combustion chamber 3, oil holes 8 and water holes 7 was formed as shown in FIG. On the other hand, a 0.2 mm thick stainless steel plate (SU-301) is pressed to punch out the combustion chamber, oil hole, and water hole, and a bead with a width of 2 mm and a height of 0.3 mm is formed around these holes. Then, the end of the board was folded back 180 ° in the direction opposite to the bead. Then, a dispersion of tetrafluoroethylene resin (Polyflon TC-7400 manufactured by Daikin Industries, Ltd.) was sprayed on the beaded surface, and then 1
Heat treatment was performed at 80 ° C. to form a coating layer having a thickness of 0.05 mm. Then, the surface without the coating layer was laminated on the molded body, and the bent end portion was folded further inward to fix the stainless steel plate to the molded body to obtain a head gasket. FIG. 3 is a plan view of this head gasket, and FIG. 4 is a sectional view taken along line BB of FIG. In the figure, 9 is a stainless steel plate, 6 is its bead, 1 is a reinforcing core plate, and 2 is an expanded graphite sheet.

Example 1, Example 2, Example 4, Comparative Example 1 and Comparative Example 2
The oil resistance property, water resistance property, and leak property of the gasket material obtained in Step 1 were measured, and the values shown in Table 1 were obtained.

In Table 1, oil resistance is the recovery rate of a 50 x 50 (mm) test piece made from a gasket material after being immersed in ASTM No. 3 oil for 5 hours at 150 ° C. The recovery rate after immersing a test piece of × 50 (mm) in a 50% by weight aqueous solution of ethylene glycol at 100 ° C for a period of time is shown. The recovery rate is obtained by compressing the test piece after impregnation with the above No. 3 oil or ethylene glycol aqueous solution with a penetrator of 22.6 mmφ, and the thickness of the compressed part when a preload of 7 kg / cm ² is applied. Let T _{1 be} the thickness when a main load of 350 kg / cm ² is applied, T ₂ and the thickness when a load of 7 kg / cm ² is applied again be T _3, and calculate the restoration ratio R from the following formula. .

Regarding the leak characteristics, five test pieces 12 each having an inner diameter d = 34 mm and an outer diameter D = 50 mm shown in FIG. 7 were prepared for each of the Examples and Comparative Examples. 14 in 80
After tightening with a surface pressure of kg / cm ² , 50 wt% ethylene glycol aqueous solution was fed into the space 16 from the liquid inlet 15 and internal pressure was applied to check for leaks and bleeding. Internal pressure is 0.5 kg / cm ²
The pressure was raised to 8 kg / cm ^{2 at} intervals and held for 30 minutes at each pressure.

From Table 1, it can be seen that the samples of the examples have NO.
3 The recovery rate after immersion in oil and ethylene glycol is excellent, and the comparison between Examples 1, 2 and 3 shows that the reinforcing core plate is superior to mat in cloth. Further, it is clear that the leak characteristics of the examples have no problem.

Next, the head gaskets obtained in Examples 1, 3, 4, 5 and Comparative Example 2 were incorporated into an engine, and a 200-hour continuous bench durability test was performed twice under full load.
As for the head gasket of 1st time, 1 spot of grommet crack, 1 spot of antifreeze liquid, 2 spots of grommet crack and 1 spot of oil were seen at the 2nd time. In the example, gas, antifreeze liquid, oil leak There was no trouble.

(Effect of the Invention) According to the present invention, by using heat-resistant fiber for the reinforcing core plate, the contact of the surface pressure becomes uniform, and the sealing effect against water is enhanced. Further, by using a resin for bonding 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 resistance and water resistance can be improved. In addition, the expanded graphite sheet or metal foil is adhered to the periphery of the combustion chamber in the gasket, the heat-resistant resin is coated,
Alternatively, by sticking a thin metal plate provided with a bead, the sealing property against combustion gas, water and oil is improved.

[Brief description of drawings]

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 and BB sectional view of FIG. 3, FIG. 5 is a plan view of a conventional head gasket, FIG. 6 is a CC sectional view of FIG. 5, and FIG. 7 is a leak characteristic test method. It is a schematic diagram showing. Explanation of symbols 1 ... Reinforcing core plate, 2 ... Expanded graphite sheet 3 ... Combustion chamber, 4 ... Adhesive part 5 ... Grommet, 6 ... Bead 7 ... Water hole, 8 ... Oil hole 9 ... Stainless steel plate, 12 …… Test piece 13 …… Jig, 14 …… Bolt 15 …… Liquid inlet, 16 …… Space

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Tatsuya Nishida, Inventor Tatsuya Nishida 3-3-1 Ayukawa-cho, Hitachi City, Ibaraki Prefecture Sakuragawa Plant, Nitrate Kasei Co., Ltd. (72) Inventor Koichi Kuboki 3 Ayukawa-cho, Hitachi City, Ibaraki Prefecture 3-3-1 Nitta Rikasei Co., Ltd. Sakuragawa Factory (56) References Japanese Patent Laid-Open No. 52-92216 (JP, A) Japanese Utility Model Sho 53-81769 (JP, U) Japanese Utility Model Sho 59-22276 (JP, Y2)

Claims (3)

(57) [Claims] 1. An expanded graphite sheet or a metal foil is attached to the periphery of an opening of a molded body obtained by punching a gasket material in which expanded graphite sheets are adhered with resin on both sides of a reinforcing core plate made of heat-resistant fiber and punched into a head gasket shape. Head gasket that is adhered with. 2. A heat-resistant resin is applied to the periphery of the opening of a molded body obtained by punching a gasket material in which expanded graphite sheets are bonded with resin on both sides of a reinforcing core plate made of heat-resistant fiber and punched into a head gasket shape. Head gasket. 3. A convex portion is provided in the peripheral portion of the opening on a surface on one side of a molded body obtained by stamping a gasket material in which expanded graphite sheets are adhered with a resin on both sides of a reinforcing core plate made of heat resistant fiber and punched into a head gasket shape. A head gasket in which a thin metal plate coated with a heat-resistant resin is attached to the surface provided with the convex portion or both surfaces with the convex portion facing outward.