JPS5891352A - Head gasket for engine - Google Patents

Abstract

PURPOSE:To concentrate a clamping force for the head into annular protrusions and prevent the leakage of a pressure in a combustion chamber by a method wherein each one annular protrusions surrounding the combustion chamber are formed on both surfaces of the head gasket for the engine. CONSTITUTION:The both surfaces of the head gasket 24 for the engine, which is pinched between the cylinder head and the cylinder body of the engine are formed with the annular protrusions 34, 36 surrounding the combustion chamber. The gasket 24 is formed by a metallic plate 38 while the annular protrusions 34, 36 are formed by two beads being connected by substantially a wave form in the section thereof. When the cylinder head and the cylinder body are clamped by a predetermined clamping force, the top faces of each annular protrusions 34, 36 are pressed strongly against the cylinder body and the cylinder head respectively and the clamping force is applied to these annular protrusions 34, 36 concentrically, whereby, the adhesion properties of the gakset may be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a head gasket for an engine that is held between a cylinder head and a cylinder body and prevents pressure leakage in a combustion chamber.

A head gasket is sandwiched between the cylinder body and cylinder head to prevent combustion chamber pressure from leaking. This head gasket has been known to have a variety of structures, such as those using a flat metal plate (metal type), those using an asbestos plate wrapped in metal (coated type), or those using metal and non-metal. There are some types that mainly use composite materials (composite type). However, these flat gaskets generally have poor adhesion to the mounting surface on the cylinder body and cylinder head side, and because the tightening force is distributed over the entire surface of the gasket, there is a problem that the sealing performance may deteriorate depending on the material of the surface. Ta.

FIG. 1 is a sectional view of the combustion chamber side of a conventionally used corrugated gasket. This gasket has an annular convex portion 2, that is, a bead, formed on one side of a metal plate 1 such as a copper plate, an aluminum plate, or a mild steel plate, so as to surround a combustion chamber.
The sealing performance of the flat gasket is improved. In this corrugated gasket, the top 3 of the annular convex portion 2
Since the tightening force is intensively applied to the top part 3, the adhesion and sealing properties between the top part 3 and the mounting surface are improved. However, this top 3
The sewing tightening force that is intensively applied to the top part 3 is distributed to the two hem parts 4 and 5 on the side opposite to this top part 3, so this hem part 4
．． The tightening force between 5 and the mounting surface becomes weaker. For this reason, the adhesion and sealing properties of the hem portions 4 and 5 are not sufficiently improved.

On the other hand, in order to reduce the weight of the engine, it is desired to reduce the number of head bolts that tighten the cylinder head and cylinder body, increase the spacing between the head bolts, and increase the maximum explosion pressure in the direction of exit. However, with conventional flat gaskets, pressure leaks in the combustion chamber are likely to occur when such methods are used to reduce weight and improve output, and even with the use of corrugated gaskets, pressure leaks cannot be completely prevented in some cases.

The purpose is to provide sketches.

In order to achieve this object, the present invention forms an annular protrusion surrounding the combustion chamber, one on each side, and concentrates the tightening force of the cylinder body and cylinder head on the annular protrusion to prevent pressure leakage in the combustion chamber. This is to prevent The present invention will be described in detail below based on the illustrated embodiments.

Fig. 2 is a sectional view of a two-stroke engine to which an embodiment of the present invention is applied, Fig. 3 is a plan view of its head gasket, and Figs. 4 and 5 are sectional views taken along the tV-■ line in Fig. 3. v-v
It is a line enlarged end view.

In FIG. 2, reference numeral 10 denotes a cylinder body, 12 a cylinder sleeve integrally cast into this cylinder body 1O, and 1
4 is a crankcase, 16 is a screw-ton, 18 is a crankshaft, and 20 is a connecting rod that connects the piston 16 and the crankshaft 18.

Six head bolts 22 (only two are visible in FIG. 2) project upward from the cylinder body 10. This head bolt 22 has a gasket 2 shown in FIG.
4 and cylinder head 26 are installed one after another and these are tightened by nuts 28. As a result, cylinder sleeve 12, cylinder head 26 and piston 16
(A combustion chamber 30 is formed from the two. Note that 32 is a spark plug.

The gasket 24 is formed with one annular convex portion 34 and one annular convex portion 36 on each side C so as to surround the combustion chamber 32.

That is, as is clear from FIGS. 4 and 5, the gasket 24 is formed of a metal plate 38, and the annular convex portions 34 and 36 are formed of two connected beads having a substantially wavy cross section. Furthermore, the third
In the figure, 40 is a hole through which the head bolt 22 is inserted.

Therefore, according to this embodiment, when the gasket 24 is tightened between the cylinder body 10 and the cylinder head 26 with a predetermined tightening force, the tops of the respective annular protrusions 34 and 36 are attached to the cylinder body 10 and the cylinder head, respectively. 26 is strongly pressed. In other words, the tightening force is applied to these annular protrusions 34.
．． It will be intensively added to 36. Therefore, the gasket 24, the cylinder body 10 and the cylinder head 26
Although the metals are in contact with each other, the tightening force acts strongly on the annular convex portions 34 and 36, resulting in good adhesion and improved sealing performance.

Furthermore, even if the tightening gap of the gasket 24 increases slightly due to explosive force or thermal deformation within the combustion chamber 30, the annular convex portion 34.
Due to the elasticity of the cylinder 36, the pressing force between the annular projection 34 and the cylinder body 10 and the cylinder head 26 can be maintained sufficiently large. Therefore, it is possible to increase the interval between the head bolts 22 and reduce the weight of the engine, while at the same time increasing the maximum explosion pressure, it is also possible to increase the output.

Since the above embodiment is applied to a metal type gasket made of a single metal plate, the annular convex portions 34 and 36 can be formed extremely easily by press working, etc., and manufacturing is easy. However, the present invention can of course be applied to gaskets of other structures.

FIG. 6 is a sectional view of the combustion chamber side of the second embodiment. The gasket 24A of this embodiment is a covered type in which an asbestos plate 42 is wrapped with a metal plate 44. is bent into a wavy cross section and has an annular convex portion 34A on both sides,
34B is formed. According to this embodiment, asbestos board 4
Since the elasticity of the gasket 2 itself also acts, the sealing performance is even better than that of the metal type gaskets shown in FIGS.

In each of the above embodiments, the annular convex portion 34.34A,
- Although 36.36A is formed to have a wave-like cross section, it is preferable that the adjacent annular convex portions 34.36, 34A, and 36A are close to each other. That is, in this case, the pressure of the clamping force acting on one of the annular protrusions 34, 34A immediately acts on the other annular protrusion 36, 36A, improving the degree of concentration of the tightening force.

FIG. 7 is a sectional view of the combustion chamber side of the third embodiment, in which the gasket 24B of this embodiment is an asbestos plate 46, and an annular convex portion 34B is provided on both sides of the plate 46 back to back.

36B.

Further, FIG. 8 is a sectional view of the combustion chamber side of the fourth embodiment.
It is of a covering type, and annular convex portions 34C and 36C are formed back to back on both surfaces, similar to the embodiment shown in FIG.

According to the embodiments shown in FIGS. 7 and 8, the annular convex portion 34B
, 34C and 36B. Since 36C are formed back to back, one annular convex portion 34B.

The pressure on 34C is -jt on the other annular convex portion 36B.
, 36C, and the sealing performance is further improved.

As described above, in this invention, one annular convex portion is formed on each side of the gasket so as to surround the combustion chamber.
The tightening force of the gasket is concentrated on these annular protrusions. Therefore, the contact pressure between these annular protrusions and the dowel body and cylinder head is significantly increased, improving the adhesion and sealing performance between the two. Therefore, pressure leakage in the combustion chamber can be reliably prevented.

[Brief explanation of drawings]

Figure 9J1 is a sectional view of the combustion chamber side of a conventional gasket, Figure 2 is a sectional view of an engine to which an embodiment of the present invention is applied, and Figure 3 is a sectional view of the combustion chamber side of a conventional gasket.
The figure is a plan view of the gasket, and Figures 184 and 5 are the 3rd
The cross-sectional view taken along the line W-1r and the enlarged end view taken along the line ■-V in Figures 6.7.8 are side cross-sectional views of the combustion chamber of another embodiment. lO...Cylinder body, 24.24A~24C-...Gasket, 26...
Cylinder head, 30... Combustion chamber, 34.34A~3
4C, 36, 36mm to 36C... annular convex portion. Patent applicant Yamaha Motor Co., Ltd.

Claims (1)

[Claims] In a gasket for an engine that is held between a cylinder body and a cylinder head, one annular protrusion surrounding the combustion chamber is formed on each side, and the tightening force of the cylinder body and cylinder head is applied to the annular protrusion. A gasket for engines that concentrates pressure to prevent pressure leaks in the combustion chamber.