JPH11201285A - Gasket board of cylinder head gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the excessive reduction of the surface pressure at the part separated from a fastening bolt, and to prevent the blowby of a combustion gas, by making a part close to the fastening bolt in a thin wall, while a part separated from the fastening bolt in a thick wall, even though the surface pressure at the part close to the fastening bolt is high, and that at the part far from the fastening bolt is low. SOLUTION: A gasket board 2 furnishes combustion chamber holes 2A and bolt holes 2B, and a cylinder head and a cylinder block are fastened by fastening bolts inserted to the bolt holes, so as to hold the gasket board 2 between both members. To the gasket board 2, thin wall parts 2a at the positions close to the bolt holes 2B, thick wall parts 2b at the positions separated from the bolt holes, and thickness changing parts 2c which continue the thickness of the thin wall parts and the thickness of the thickness wall parts smoothly, are formed by surrounding the combustion chamber holes 2A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gasket substrate for a cylinder head gasket used in an engine.

[0002]

2. Description of the Related Art Conventionally, a cylinder head gasket generally has a gasket substrate having a plurality of combustion chamber holes formed in accordance with cylinder bores and bolt holes through which fastening bolts are passed. By fastening them with the above-mentioned fastening bolts while being interposed between the head and the cylinder block, the space between the cylinder head and the cylinder block is sealed. Conventionally, a plate having a combustion chamber hole drilled in accordance with the cylinder bore and a bolt hole through which the fastening bolt passes is superimposed on a gasket substrate, and a portion of the plate surrounding the combustion chamber hole is adjacent to the gasket substrate. It is also known that a portion close to the combustion chamber is formed to be thick so as to particularly improve the sealing property and durability between the combustion chambers (Japanese Patent Laid-Open No. 6-174).
No. 100)

[0003]

However, when the cylinder head and the cylinder block are fastened by the fastening bolt, the surface pressure at a portion close to the fastening bolt is high and the surface pressure at a portion far from the fastening bolt is low. Depending on the engine, the sealing performance may be reduced at a portion far from the fastening bolt, and the gas in the combustion chamber may blow out from that portion. The present invention has been made in view of such circumstances, and when a cylinder head and a cylinder block are fastened by fastening bolts, it is intended to prevent an excessive decrease in surface pressure in a portion far from the fastening bolts, thereby preventing combustion gas from flowing through. And a gasket substrate for a cylinder head gasket.

[0004]

That is, the present invention provides a combustion chamber hole which is sandwiched between a cylinder head and a cylinder block and is drilled in accordance with a cylinder bore, and a fastening bolt for fastening the cylinder head and the cylinder block. In the gasket substrate of a cylinder head gasket having a bolt hole through which the gasket substrate surrounds the combustion chamber hole, a thin portion at a position close to the bolt hole, and a thin portion at a position away from the bolt hole A thick portion and a thickness changing portion that smoothly continues the thickness of the thin portion and the thickness of the thick portion are formed.

[0005]

According to the above construction, when the cylinder head and the cylinder block are fastened by the fastening bolt,
Generally, the surface pressure of the part close to the fastening bolt is high and the surface pressure of the part far away is low, but the part close to the fastening bolt is a thin part and the part away from the fastening bolt is a thick part. Therefore, it is possible to prevent the occurrence of blow-through due to excessive decrease in surface pressure particularly at a portion away from the fastening bolt. Since the thickness of the thin portion and the thickness of the thick portion are smoothly continued by the thickness change portion, there is room for occurrence of blow-through from a step portion between the thin portion and the thick portion. There is no.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a cylinder head gasket for an in-line four-cylinder engine will be described below. In FIG. 2, a cylinder head gasket 1 has a relatively thick gasket substrate 2 and a gasket substrate 2.
The gasket substrate 2 and the two plates 3 and 4 are provided on the upper and lower surfaces of the gasket substrate 2 and the two plates 3 and 4 so as to match the cylinder bores of an engine (not shown). Four provided combustion chamber holes 2A (see FIG. 1), 3A and 4A are formed. Further, the gasket substrate 2 and the two plates 3 and 4 are formed with bolt holes 2B (only the bolt holes 2B of the gasket substrate 2 are shown in FIG. 1) through which fastening bolts (not shown) are passed. ing. The cylinder head gasket 1 is
Although not shown, as is well known in the art, the cylinder head and the cylinder block are interposed between the cylinder head and the cylinder block of the engine. Is to be sealed.

The plates 3 and 4 are formed with full bead portions 3a and 4a surrounding the combustion chamber holes 2A. In the illustrated embodiment, the full bead portions 3a and 4a project toward the gasket substrate 2, respectively. It is formed in. Half beads 3b and 4b are formed on the outer peripheral side of the plates 3 and 4 and are formed along the outer periphery of the gasket substrate 2 and surround all the bolt holes 2B so that they are inside. Further, a shim 5 surrounding each combustion chamber hole 3A of the plate 3 is provided on the lower surface of the plate 3 on the upper side (cylinder head side), that is, the surface on the gasket substrate 2 side.
Are integrally attached by welding.

As shown in FIGS. 2 and 3, a portion of the gasket substrate 2 that overlaps with the shim 5 in each combustion chamber hole 2A is on the opposite side of the shim 5 in order to release the thickness of the shim 5. The amount of protrusion is set to approximately half the thickness of the shim 5. The thickness of the protruding portion surrounding each combustion chamber hole 2A is made different in the circumferential direction of each combustion chamber hole 2A. That is, as shown in FIGS. 1 and 4, a thin portion 2a is formed at a position close to the bolt hole 2B, and a thick portion 2b is formed at a position distant from the bolt hole 2B. Thin part 2a and thick part 2b
A thickness change portion 2c is formed between the thin portion 2a and the thick portion 2b to smoothly and continuously connect the thickness of the thin portion 2a and the thickness of the thick portion 2b. In the illustrated embodiment, the thin portion 2a, the thick portion 2b, and the thickness change portion 2c are formed such that the lower surface is flat and the upper surface is uneven. The thin portion 2a is provided on each side of a line L connecting the center of the combustion chamber hole 2A and the center of each bolt hole 2B by 10 degrees, that is, over a range of 20 degrees around the combustion chamber hole 2A. The thickness change portions 2c arranged on both sides of the thin portion 2a also have a thickness of 20 mm around the combustion chamber hole 2A.
The other portion is the thick portion 2b. In FIG. 1, the above-mentioned thickness change portion 2c is indicated by oblique lines. Further, the thickness of the shim 5 is 1
The protrusion amount for releasing the thickness of the shim 5 is set to 60 μm, the thickness of the gasket substrate 2 is set to 600 μm, and the thickness of the thin portion 2a is reduced to the thickness of the thick portion 2b. In comparison, the thickness is reduced by 20 μm.
These numerical values are merely examples, and it is a matter of course that the present invention is not limited to these numerical values. In FIG. 1, the upper right bolt hole 2B also serves as an oil hole, and thus has a long hole shape. 6 is a water hole and 7 is a blow-by hole.

In the above construction, the cylinder head gasket 1 is interposed between the cylinder head and the cylinder block of the engine, and in this state, the cylinder head and the cylinder block are integrally connected by fastening bolts so as to be connected to each other. Seal the gap. At this time, a thin portion 2a is formed at a position close to the bolt hole 2B, and a thick portion 2b is formed at a position distant from the bolt hole 2B, and a thin portion 2a and a thick portion 2b are formed between the thin portion 2a and the thick portion 2b. Since the wall thickness change portion 2c for making the wall thickness smoothly continuous is formed, the surface pressure due to the fastening can be made as uniform as possible at a position close to the fastening bolt and a position away from the fastening bolt. Therefore, it is possible to prevent the surface pressure at a position distant from the fastening bolt from being excessively reduced and the gas in the combustion chamber from flowing therethrough as in the related art. In particular, the thickness change portion 2c between the thin portion 2a and the thick portion 2b smoothly connects the thickness of the thin portion 2a and the thickness of the thick portion 2b. As described above, the contact pressure does not suddenly change, and thus blow-through caused by the contact pressure suddenly changing can be prevented.

In the above-described embodiment, the protrusion for releasing the thickness of the shim 5 is provided. However, the protrusion may be omitted.
Simultaneously, the shim 5 may be omitted. Further, in the above embodiment, the surface pressure is made as uniform as possible in the circumferential direction. However, the surface pressure may be set to be slightly higher only in the adjacent combustion chamber hole 2A. If necessary, one or both of the plates 3 and 4 may be omitted.

[0011]

As described above, according to the present invention, it is possible to prevent the surface pressure at a portion away from the fastening bolt from being excessively reduced, thereby preventing gas from flowing out from that portion. The effect that it can be obtained is obtained.

[Brief description of the drawings]

FIG. 1 is a plan view of a gasket substrate 2 showing one embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the cylinder head gasket 1 including the gasket substrate 2 of FIG. 1 along the line II-II of FIG.

FIG. 3 is an enlarged sectional view taken along line III-III of FIG. 1;

FIG. 4 is an enlarged sectional view taken along the line IV-IV in FIG. 1;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cylinder head gasket 2 ... Gasket board 2A ... Combustion chamber hole 2B ... Bolt hole 2a ... Thin part 2b ... Thick part 2c ... Thickness change part 3, 4 ... Plates 3a, 3b, 4a, 4b ... Bead part 5 ... Sim

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[Procedure amendment]

[Submission date] February 20, 1998

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG. 2

[Fig. 3]

[Fig. 4]

[Fig. 1]

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Eisaburo Goto 3-65 Midorigaoka, Toyota-shi, Aichi Prefecture Inside Daitoyo Kogyo Co., Ltd. (72) Inventor Kenji Uchida 3-65 Midorigaoka, Toyota-shi, Aichi Prefecture Otoyo Kogyo Co., Ltd. (72) Inventor Hideo Fukaya 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Seiichi Ohashi 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Kawai Shiro 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Seiji Omura 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation

Claims (5)

[Claims] 1. A combustion chamber hole sandwiched between a cylinder head and a cylinder block and drilled in accordance with a cylinder bore, and a bolt hole through which a fastening bolt for fastening the cylinder head and the cylinder block is inserted. In the gasket substrate of the cylinder head gasket, the gasket substrate surrounds the combustion chamber hole and has a thin portion at a position close to the bolt hole, a thick portion at a position away from the bolt hole, and A gasket substrate for a cylinder head gasket, wherein a gasket substrate is formed with a wall thickness changing portion for smoothly connecting the wall thickness and the wall thickness of the thick wall portion. 2. The gasket substrate for a cylinder head gasket according to claim 1, wherein said thin portion is provided over a range of about 20 degrees around said combustion chamber hole. 3. The gasket substrate for a cylinder head gasket according to claim 1, wherein the thick wall portion is provided over a range of about 20 degrees around the combustion chamber hole. . 4. A combustion chamber hole formed in each of the front and back surfaces of the gasket substrate in accordance with the cylinder bore,
A plate having a bolt hole through which a fastening bolt for fastening the cylinder head and the cylinder block is provided is provided, and a shim surrounding a combustion chamber hole of the plate is provided on a surface of one of the plates on the gasket substrate side. The gasket substrate for a cylinder head gasket according to any one of claims 1 to 3, wherein: 5. The gasket substrate according to claim 1, wherein a thin portion, a thick portion, and a thickness-varying portion surrounding the combustion chamber hole are entirely protruded along the shim on a side opposite to the shim. A gasket substrate for the cylinder head gasket according to claim 4.