JPS61241446A - Setting method of head gasket - Google Patents

Abstract

PURPOSE:To maintain sealability for gasfor a long time, by setting up a metallic ring in a bore hole part in a head gasket made up of punching layered graphite sheets on both surfaces of a reinforced plate and also setting up a gasket on this outer circumference, while attaching them to an engine. CONSTITUTION:Graphite sheets 1 are layered on both sides of a metallic thin reinforced plate 4 having a lot of circular projections on both surfaces and, after these sheets are rolled smoothly, are punched in a illustrated form with a punching press. Next, an annular body 2 made up of punching a carbo-fit is stuck up by a press so as to cause the inner diameter to be sityated at the outside of about 0.5mm from a bore hole 8, thus a head gasket is secured. An inner diameter of a soft steel metal ring 3 is polished to be larger as much as 0.2-0.5mm than a diameter of a combustion chamber. And, as for setting to an engine, the head gasket is mounted on a cylinder block 5 and after the metal ring 3 is charged and positioned to the bore hole part, a cylinder head 6 is locked to the cylinder block 5 with a screw via the head gasket and the metal ring 3. With this constitution, sealability for gas is maintained for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of attaching a graphite head gasket for use in an internal combustion engine.

(Prior Art) Conventionally, a bed gasket attached to an internal combustion engine has a thin metal plate called a grommet attached to the bore hole in contact with the combustion chamber in a 7% mesh pattern.

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.

(Problem to be solved by the invention) However, with conventional grommets, the grommet is in contact with the cylinder head and cylinder block.

Curved parts where the grommet is highly deformed and hardened may cause problems such as grommet cracking and gas leakage during operation due to repeated loads due to explosions, shearing force due to differential expansion of the cylinder block and cylinder head, etc. In order to prevent grommet cracking, some methods have been used to attach an expanded graphite sheet around the bore hole without using a grommet, making the area around the bore hole denser and sealing the gas, but this method causes the graphite to collapse during operation. There was a problem with graphite flowing into the combustion chamber.

SUMMARY OF THE INVENTION An object of the present invention is to provide a head gasket mounting method that solves the above-mentioned problems.

(Means for solving the problem) The present invention is a head gasket made by laminating graphite sheets on both sides of a reinforcing plate and punching them out.A ring-shaped graphite sheet is attached near the bore hole in K, and a metal ring and a metal ring are attached to the bore hole. The present invention relates to a method for attaching a head gasket, characterized in that the head gasket is disposed around the outer periphery of the metal ring and is attached to an internal combustion engine.

In the present invention, the graphite sheet is produced by immersing scale-like graphite in a strongly oxidizing liquid such as a mixed acid of concentrated sulfuric acid and nitric acid or a mixed acid of concentrated sulfuric acid and potassium permanganate to form an interlayer compound, followed by rapid heating after washing with water. Expanded graphite obtained by expanding graphite crystals in the C-axis direction is formed into a sheet by cold working or the like. After laminating this graphite sheet on the inner surface of a thin metal reinforcing plate having circular or square protrusions on both sides, it was crimped with a roll, etc., and then pressed and punched into the shape shown in Figure 1. , a ring-shaped graphite sheet is attached near the bore hole and is used as a head gasket. The annular graphite sheet is attached by adhesive bonding or press bonding. There is no particular limit to the thickness of the annular graphite sheet.The metal ring may be made of any material as long as it prevents graphite streaks during operation and can withstand operating temperatures, but mild steel is usually used. The inner diameter of the metal ring is made slightly larger than the diameter of the combustion chamber in consideration of thermal expansion, and there are no restrictions on the dimensions of other parts.

For installation on the engine, 1. For example, place the metal ring on the cylinder block and the cylinder head on the outer periphery of the metal ring.
After aligning the metal ring with the combustion chamber, fix the cylinder head with screws, etc.

(Function) With the above configuration, the part of the head gasket where the annular graphite sheet is attached is compressed and seals the high-density gas, and the metal ring interposed between the combustion chamber and the head gasket seals the graphite sheet. Prevents the flow of water into the combustion chamber.

(Example) Next, an example will be described.

Example 1 A reinforcing plate 40 made of a thin metal plate shown in FIG. 2 and having a large number of circular protrusions of 0.2 m on both sides has a thickness of 0.75 mm on both sides.

Graphite sheets (manufactured by Hitachi Chemical Co., Ltd., trade name: Carpofit) 1 having a density of 1 g/am" were laminated and rolled, and then punched into the shape shown in FIG. 1 using a punching press.

At this time, the diameter of the bore hole 8 is +0.5 of the outer diameter of the metal ring.
It was punched out with a dimensional accuracy of ~0011 m. Next, the thickness is 0.4-
An annular body 2, which is made by punching a carbo- A gasket was obtained. The inner diameter of the metal ring 3 was polished 0.2 to 0.5 wn larger than the combustion chamber diameter, and the thickness was 1.2 mm and the dimensional difference between the outer diameter and the inner diameter was 6 tm (
A mild steel one with a width of 3 am was used.

To install the engine, as shown in Figure 2, place the head gasket on the cylinder block 5, load the metal ring 3 into the bore hole, position it, and then attach the cylinder head 6 to the head gasket and the metal ring. 3 and screwed to the cylinder block 5. At this time, the annular body 2 attached to the graphite sheet 1 is compressed, and the upper surfaces of the graphite sheet 1, the annular body 2, and the metal ring 3 become the same plane.

Comparative Example 1 A reinforcing plate 4 was laminated with graphite sheets 1 on both sides as shown in FIG. 4 in the same manner as in Example 1.

Punch 2 so that the bore hole is O~0.5-in apart from the diameter of the combustion chamber 2 Then press the annular body 2 which is the same as in Example 1 so that the inner diameter is at a position 0.5 wn from the combustion chamber. I crimped it and got a head gasket. Next, this head gasket was attached to an engine in the same manner as in Example 1.

Comparative Example 2 A third hole was inserted into the bore hole of a plate punched using the same method as Comparative Example 1.
Grommet 7 was installed as shown in the figure (thickness 0.2a
A head gasket (in which SPC plates of 4111 m in width were attached in a grommet shape) was obtained and then attached to an engine in the same manner as in Example 1.

Using the engines of the example and comparative example, a 50,000-mile monitor test was conducted to compare the conditions of the head gaskets. As a result, in the head gasket of Comparative Example 1, a maximum of 1.1 ann of graphite protruded into the cylinder, and in the head gasket of Example 3, cracks were observed in three places in the grommet, whereas in the head gasket of Example 1 and No abnormality was observed in the metal ring.

(Effects of the Invention) According to the present invention, there is no grommet cracking or graphite flowing into the combustion chamber as in the conventional case, and therefore gas sealing performance can be maintained for a long period of time.

[Brief explanation of drawings]

FIG. 1 is a plan view of a head gasket and a metal ring in a head gasket installation method according to an embodiment of the present invention, and FIG. 2 is a sectional view showing a state in which the head gasket and metal ring of FIG. 1 are attached to an engine. FIG. 3 and FIG. 4 are cross-sectional views showing a state in which a gasket of a comparative example is attached to an engine. Explanation of symbols

Claims (1)

[Claims] 1. A ring-shaped graphite sheet is attached near the bore hole in a head gasket made by laminating graphite sheets on both sides of a reinforcing plate and punched out, and a metal ring is arranged in the bore hole and the head gasket is arranged around the outer periphery of the metal ring, A method for installing a head gasket, which is characterized in that it is installed on an internal combustion engine.