JPS61118548A - Head gasket - Google Patents

Abstract

PURPOSE:To prevent collapse of graphite into combustion chamber by laminating expansion graphite sheets to the opposite sides of reinforcing board while pressing an expansion graphite sheet around the combustion chamber of punched head gasket and impregnating the pressing section with heat-resistant resin. CONSTITUTION:Expansion graphite sheets 4 are laminated to the opposite sides of thin metal reinforcing board 3 then punched through press thereafter an expansion graphite sheet is pressed around the combustion chamber 1 to provide a press section 2. Then heat-resistant resin is impregnated at the press section 2 with impregnation rate of 5% and thermally set. Consequently, collapse of graphite into the combustion chamber (bore) 1 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvements in graphite head gaskets used in internal combustion engines.

(Prior Art) A conventional Herad gasket has a thin metal plate called a grommet attached around the combustion chamber. This grommet has a high-density part surrounded by the grommet (grommet part), and when the gasket is assembled, the grommet part creates high surface pressure and acts to seal the combustion gas, and also prevents the base material from flowing into the combustion chamber. There is a function to do that.

However, with conventional grommets, the grommet is in contact with the cylinder head and cylinder block.

Grommet deformation force In curved parts where Loe hardening is large, grommet cracking occurs during operation due to repeated loads due to leakage, shearing force due to differential expansion of the cylinder block and cylinder head, etc.
There were cases where gas leakage problems occurred. In order to prevent grommet cracking, there is a method of attaching an expanded graphite sheet around the combustion chamber without using a grommet to make the area around the combustion chamber denser and seal the gas, but this method causes the graphite to collapse during operation. There was a problem with graphite flowing into the combustion chamber.

(Object of the Invention) An object of the present invention is to provide a head gasket that prevents graphite from collapsing into the combustion chamber without using a grommet.

(Structure of the Invention) The present invention provides a head gasket in which expanded graphite sheets are laminated on both sides of a reinforcing plate and punched out.

The present invention relates to a head gasket in which an expanded graphite sheet is crimped around the combustion chamber of the head gasket to form a crimped portion, and the crimped portion is impregnated with a heat-resistant resin.

The expanded graphite used in the present invention is obtained by acid-treating natural graphite with a highly developed crystal structure with a strong oxidizing treatment solution such as a mixed acid of concentrated sulfuric acid and nitric acid or a mixed acid of concentrated sulfuric acid and potassium permanganate. It is obtained by generating an intercalation compound, washing it with water, rapidly heating it, and expanding it in the C-axis direction of graphite crystal.

In addition, the graphite herad gasket is made by cold processing the expanded graphite to create a graphite sheet, and then shaped into a nine-circular or
Expanded graphite sheets are laminated on both sides of a thin metal reinforcing plate having rectangular protrusions, and then punched into a predetermined shape using a punching press.

In the present invention, in order to increase the density around the combustion chamber without using a grommet, an expanded graphite sheet is pasted around the combustion chamber with adhesive and crimped, or by pressing! 1. After pressing an expanded graphite sheet around the combustion chamber, it is impregnated with a heat-resistant resin.

As the heat-resistant resin to be impregnated into the crimp portion, thermosetting resins such as phenol resin, furan resin, epoxy resin, and polyimide resin are preferable.

Further, it is preferable that the impregnation width be applied to the entire surface of the crimped part.

The amount of impregnation is preferably 2 to 10 inches in weight percent. If the amount of impregnation is too small, there will be no effect of increasing the strength, and if it is too large, the expanded graphite sheet will lose flexibility and the sealing performance of the gasket will deteriorate.

(Example) Next, the present invention will be explained with reference to examples.

Example 1 Expanded graphite sheets with a thickness of 0.75 m and a density of 1 g/an'' (Hitachi Chemical The combustion chamber (made by Kogyo Co., Ltd., trade name: Carboit) 4 was laminated and further punched into the shape shown in Fig. 1 using a punching press.
4 aa width and 0.4 am thick at the periphery of bore hole 1, that is, at a position 0.4 mm from the bore hole.

An expanded graphite sheet (Carboit) with a density of 1 g/am" was crimped with a press to provide a crimped portion 2 (see also Figure 2). Next, a phenol resin (manufactured by Hitachi Chemical Co., Ltd.) was formed.

A solution of 20 parts by weight of product name PR1140) dissolved in 80 parts by weight of acetone was impregnated into the 45-an area 5 including the crimp part 2 through the bore hole around the combustion chamber so that the impregnation rate was 5 cm. Allowed to harden.

(Comparative Example 1) In Example 1 and 2, a head gasket was created in which the periphery of the combustion chamber was not impregnated with resin and hardened.

(Comparative example 2) In Example 1, after punching with a punching press.

A head gasket was made by attaching a 0.2 nun thin metal plate of 41 m [1 width in a grommet shape] around the combustion chamber as shown in Fig. 3.

When the Herad gaskets of Examples and Comparative Examples were compared twice in 50-day general driving monitor tests, the first
The results in the table were obtained.

Table 1 As is clear from Table 1, the resin-impregnated portion 5 around the combustion chamber is
Graphite outflow into the bore hole can be significantly prevented. Also, comparative example 2
Grommet cracks occur in the head gasket.

(Effects of the Invention) According to the present invention, since an expanded graphite sheet is crimped around the combustion chamber and further impregnated with heat-resistant resin, it is possible to prevent graphite from collapsing into the combustion chamber, which is a drawback of conventional head gaskets that do not use grommets. .

[Brief explanation of the drawing]

FIG. 1 is a plan view of a head gasket according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line A-A in FIG. FIG. 3 is a sectional view of a head gasket of a comparative example. Explanation of symbols 1... Combustion chamber 2... Crimping part 3... Reinforcement plate 4... Expanded graphite sheet 5... Resin impregnated part 6... Grommet No. 1 Comment 3 Figure

Claims (1)

[Claims] 1. In a head gasket in which expanded graphite sheets are laminated on both sides of a reinforcing plate and punched out, the expanded graphite sheet is crimped around the combustion chamber of the head gasket to form a crimped part, and the crimped part is impregnated with a heat-resistant resin. head gasket.