JP2000161493A - Cylinder head gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture inner and outer plates, and prevent gas from escaping from one side in a cylinder head gasket while obtaining substantially same surface pressure on both sides of the cylinder head gasket. SOLUTION: This cylinder head gasket 1 has a first inner plate 2, a second inner plate 3, a first outer plate 4 and a second outer plate 5 which are superposed on each other. Inner full bead portions 4a, 5a and outer full bead portions 4b, 5b are formed on the outer plates, which are projected in separating direction from each other so as to surround a combustion hole 6. Inner full bead portions 2a, 3a are formed on the inner plates and inside the inner full bead portions 4a, 5a. The inner full bead portions 2a, 3a are separated from the inner full bead portions 4a, 5a of the outer plates, before assembling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder head gasket sandwiched between a cylinder head and a cylinder block of an engine to seal the portion.

[0002]

2. Description of the Related Art Conventionally, as a cylinder head gasket, at least two gasket substrates are superimposed, a combustion chamber hole is formed in each of them in accordance with a cylinder bore, and a full bead portion protruding in the same direction on both gasket substrates. Are known (Japanese Patent Laid-Open No. 5-39867). Further, when forming the full bead portion, the second full bead portion of the other gasket substrate protruding into the first full bead portion formed on one gasket substrate, in a state before assembly,
It is also known that the first full bead portion is formed apart from the first full bead portion (Japanese Patent Laid-Open No. 1-168059).

[0003]

However, in the former configuration, since the two gasket substrates are generally manufactured separately, high-precision manufacturing is required in order to accurately overlap the full bead portions. If the two are displaced from each other, they may cause cracks in the bead portion. In the latter configuration, since the two full bead portions are separated from each other, it is not necessary to perform high-precision manufacturing, and the manufacturing is easy.However, together with the former configuration, a full bead portion projecting in only one direction is formed. Therefore, the contact surface pressure is different between the front surface side and the rear surface side, and there is a high danger that the combustion gas will blow out particularly on the surface opposite to the direction in which the full bead portion protrudes. The present invention has been made in view of such circumstances, and provides a cylinder head gasket that is easy to manufacture and that can reduce the risk of combustion gas blowing through.

[0004]

That is, the present invention comprises a first inner plate and a second inner plate which are superimposed on each other, and a first outer plate and a second outer plate which are superposed on the outside of each inner plate. A combustion chamber hole is formed in each of the inner plate and the outer plate in accordance with the cylinder bore; and the first and second outer plates are protruded in a direction away from each other to form the combustion chamber holes. And an outer full bead portion projecting in the direction away from the inner full bead portion is formed outside the inner full bead portion, and further, the first inner plate and the second inner plate are separated from each other in a direction separating from each other. To form inner full bead portions located inside the inner full bead portions of the outer plates, respectively, and Bead portion is characterized in that which is remote from the inner full bead portion of the outer plate in the state before assembly.

[0005]

According to the above construction, since each inner full bead portion of the inner plate is separated from the inner full bead portion of each outer plate, the inner full bead portions can be manufactured with higher precision than when they are superimposed on each other. Therefore, the inner plate and the outer plate can be easily manufactured. Further, according to the above configuration, a double high surface pressure is obtained at the inner full bead portion and the outer full bead portion of the outer plate, so that double sealing can be performed at those portions, and the cylinder of the cylinder head gasket is further improved. Since substantially the same surface pressure is obtained on the head side and the cylinder block side, there is no case where the combustion gas easily blows from one side.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a cylinder head gasket according to the present invention; FIG.
Is provided with a first inner plate 2 and a second inner plate 3 which are superposed on each other, and a first outer plate 4 and a second outer plate 5 are superposed on the outer sides of the inner plates 2 and 3, that is, on the upper and lower surfaces. ing. A combustion chamber hole 6 is formed in each of the inner plates 2 and 3 and the outer plates 4 and 5 in accordance with a cylinder bore of an engine (not shown). The inner plates 2 and 3 and the outer plates 4 and 5 are respectively formed with bolt holes 7 through which fastening bolts (not shown) are passed, and water holes 8 through which cooling water flows and lubricating oil are supplied. And an oil return hole 10 for returning lubricating oil are also formed. The cylinder head gasket 1 is interposed between a cylinder head and a cylinder block of an engine (not shown), and is interposed between the cylinder head and the cylinder block by integrally connecting the cylinder head and the cylinder block by the above-described fastening bolts. Is to be sealed.

Each of the outer plates 4 and 5 has inner full bead portions 4a and 5a projecting vertically and spaced apart from each other and surrounding the combustion chamber hole 6, and is formed outside the inner full bead portions 4a and 5a. The outer full bead portions 4b and 5b protruding in the vertical direction and separated from each other are formed. On the other hand, the inner plates 2 and 3 are respectively formed with inner full bead portions 2a and 3a that protrude in the vertical direction and are separated from each other and are located in the inner full bead portions 4a and 5a of the outer plates 4 and 5 respectively. The inner full bead portions 2 of the inner plates 2 and 3
a and 3a are separated from the inner surfaces of the inner full bead portions 4a and 5a of the outer plates 4 and 5 in a state before the cylinder head gasket 1 is clamped between the cylinder head and the cylinder block.

According to the above construction, the inner full bead portions 2a, 3a of the inner plates 2, 3 are separated from the inner surfaces of the inner full bead portions 4a, 5a of the outer plates 4, 5, so that the inner full bead portions are formed. It is not necessary to manufacture the inner plates 2 and 3 and the outer plates 4 and 5 easily, as compared with the case where they are polymerized with each other. 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 a fastening bolt to seal therebetween. . At this time, since the inner full bead portions 4a and 5a of the outer plates 4 and 5 and the outer full bead portions 4b and 5b can obtain a double high surface pressure, the portions are double sealed. In addition, since substantially the same surface pressure is obtained on the cylinder head side and the cylinder block side of the cylinder head gasket 1, the combustion gas is not easily blown from one side.

The inner full bead portions 2a, 3a of the inner plates 2, 3 provided on the inner surface side of the inner full bead portions 4a, 5a of the outer plates 4, 5 serve as stoppers for the inner full bead portions 4a, 5a during assembly. Function. Thus, since the stress amplitude of the inner full bead portions 4a and 5a at the time of combustion load fluctuation can be reduced, damage of the inner full bead portions 4a and 5a can be prevented. Further, the inner full bead portions 4a, 5a of the outer plates 4, 5 are manufactured relatively large in view of accommodating the inner full bead portions 2a, 3a of the inner plates 2, 3 on the inner surface side, As a result, the sealing area is enlarged, so that the sealing performance against scratches or the like on the cylinder head or cylinder block side can be improved. Furthermore, when the cylinder head gasket 1 is sandwiched between the cylinder head and the cylinder block, the contact portions adjacent to the combustion chamber holes 6 of the inner plates 2 and 3 are crushed by crushing the inner full bead portions 2a, 3a and 4a and 5a. Become open. Then
The combustion gas leaking into the inner full bead portions 2a and 3a of the inner plates 2 and 3 from the gap between the inner plates 2 and 3 flows through the inner full bead portions 2a and 3a to the inside of the outer plates 4 and 5 by the pressure. Since the full bead portions 4a and 5a are pressed against the cylinder head and the cylinder block, the sealing performance at those portions can be further improved.

FIG. 3 shows a second embodiment of the present invention. While the inner plates 2 and 3 of the above embodiment have only the inner full bead portions 2a and 3a, in the present embodiment, each of the full plates Outside full bead portions 2b and 3b are formed outside the bead portions 2a and 3a. The outer full bead portions 2b, 3b protrude in the vertical direction and are spaced apart from each other.
b, 5b, and the outer full bead portions 2b, 3b of the inner plates 2, 3 are provided with the respective outer plates in a state before the cylinder head gasket 1 is clamped by the cylinder head and the cylinder block. 4,
5 is separated from the inner surfaces of the outer full bead portions 4b, 5b. Further, in the above embodiment, all the full beads are constituted by full bead portions having a semicircular cross section. However, the full bead portions 4a, 5a and 4b, 5b of the outer plates 4, 5 in this embodiment are mutually connected. It is composed of a pair of half bead portions arranged adjacent to each other, whereby the cross-sectional shape of the full bead portions is trapezoidal.
With such a configuration, the same operation and effect as those of the first embodiment can be obtained.

Note that, unlike the above embodiment, any or all of the full bead portions may be constituted by a pair of half bead portions arranged adjacent to each other.

[0012]

As described above, according to the present invention, the inner plate and the outer plate can be easily manufactured, and the cylinder head gasket has substantially the same surface on the cylinder head side and the cylinder block side. Since the pressure is obtained, it is possible to prevent the combustion gas from being easily blown from one side.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view showing a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cylinder head gasket 2, 3 ... Inner plate 4, 5 ... Outer plate 6 ... Combustion chamber hole 2a, 3a, 4a, 5a ... Inner full bead part 2b, 3b, 4b, 5b ... Outer full bead part

Claims (3)

[Claims] A first inner plate and a second inner plate which are superposed on each other;
An inner plate, a first outer plate and a second outer plate superposed on the outer side of each inner plate, and a combustion chamber hole is formed in each of the inner plate and the outer plate in accordance with a cylinder bore; The first outer plate and the second outer plate protrude in a direction away from each other to form inner full bead portions surrounding the combustion chamber holes, and protrude outside the inner full bead portions in a direction away from each other. Forming an outer full bead portion, and further forming, on the first inner plate and the second inner plate, inner full bead portions protruding in a direction away from each other and positioned inside the inner full bead portions of the respective outer plates; Each inner full bead portion of the inner plate is separated from the inner full bead portion of each outer plate in a state before assembly. Cylinder head gasket, characterized in that. 2. The first inner plate and the second inner plate each have an outer full bead portion protruding in a direction away from each other and located in an outer full bead portion of each of the outer plates, respectively, and each outer plate of the inner plates has an outer full bead portion. The cylinder head gasket according to claim 1, wherein the full bead portion is separated from an outer full bead portion of each outer plate before assembly. 3. The cylinder head gasket according to claim 1, wherein at least one of the full bead portions is constituted by a pair of half bead portions.