JP3898791B2 - Cylinder head gasket - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine cylinder head gasket, and more particularly to a cylinder head gasket having a convex bead having a stopper portion built around a combustion chamber hole.
[0002]
[Prior art]
In a metal gasket comprising a single or a plurality of metal plates having a combustion chamber hole and a bolt hole, a bead for surrounding and sealing the combustion chamber hole is provided in at least one layer of the metal plate, and the combustion chamber is used more than the bead. It is already well known that a stopper portion that restricts compression of the bead is formed by a folded portion of a metal plate or a shim plate at a hole side position. In such a cylinder head metal gasket, when the gasket is mounted and tightened between the cylinder head and the cylinder block, the stopper portion is prevented from being completely compressed until the bead is flattened, that is, until the bead becomes flat. In addition, since the size of the deformation of the bead repeatedly compressed and restored based on the gas pressure in the combustion chamber is limited, it is possible to prevent the bead from being damaged or damaged during the long-term use of the gasket.
[0003]
The applicant of the present application is a metal gasket having a stopper portion that operates as described above, and a metal in which a portion of the concave portion of the convex bead that surrounds and seals the combustion chamber hole is filled with a hard synthetic resin, for example, an epoxy resin. Japanese Patent Application No. 8-38787 is a metal gasket in which the filling height of the gasket, particularly the hard synthetic resin layer filled in the concave portion of the bead, is lowered at a portion close to the bolt hole and increased at a portion separated from the bolt hole. Proposed in
[0004]
In the metal gasket according to the above application, when the gasket is mounted between the cylinder head and the cylinder block and tightened, the compressed bead is supported by the hard synthetic resin layer filled in the recess, so that the height of the bead is increased. However, the bead is not compressed so as to be lower than the filling height of the resin layer. That is, the hard synthetic resin layer filled in the concave portion of the bead functions as a stopper portion that restricts compression of the bead, and the metal gasket has a stopper portion inside the convex bead itself, and is a stopper that is arranged in parallel with the bead separately from the bead. It is not necessary to provide a part.
[0005]
Therefore, a stopper portion formed by a folded portion, shim plate, or the like is provided on the combustion chamber hole side from the bead, and the stopper portion and the bead are arranged in parallel around the combustion chamber hole. Compared with the conventional cylinder head gasket that causes the above-mentioned, in the metal gasket according to the application, the effect of increasing the thickness of the gasket by the hard synthetic resin layer filled in the concave portion of the bead and the elastic force of the bead are concentrated on the bead portion. Therefore, there is an advantage that the surface pressure of the seal line around the combustion chamber hole is high, and the high surface pressure by the stopper portion is not applied to the immediate periphery of the combustion chamber of the engine, so that there is little possibility of deforming the combustion chamber.
[0006]
Further, since the gasket does not require a dedicated place for providing the stopper portion, there is an advantage that it can advantageously cope with the tendency of the engine to be made compact. Furthermore, the gasket is easy to change the height of the stopper portion, that is, the filling height of the hard synthetic resin layer according to the distance from the bolt hole, and when the height of the stopper portion is changed as described above, There is an advantage that the surface pressure of the seal wire by the bead can be equalized around the hole for the combustion chamber.
[0007]
[Problems to be solved by the invention]
However, the metal gasket of the above-mentioned application provided with a stopper portion made of a hard synthetic resin layer such as an epoxy resin filled in the concave portion of the convex bead surrounding the combustion chamber hole is mounted between the cylinder head and the cylinder block. When the hard synthetic resin layer is in contact with the joint surface of the cylinder head or cylinder block when tightened, vibration of the cylinder head and cylinder block during operation of the engine and cylinder head associated with operation and stop of the engine and Based on the thermal expansion and contraction of the cylinder block, the hard synthetic resin layer is rubbed and worn by the abutting contact surface, and the function of the stopper is impaired during long-term use. The effect of increasing the thickness may be reduced, and the seal surface pressure may be reduced. Further, in the metal gasket of the above-mentioned application, since the spring force of the bead surrounding the combustion chamber hole is decreased due to the filled hard synthetic resin, it is desired to make a structure that compensates for this and improves the spring force. Sometimes.
[0008]
The present invention has been made in view of the above points, and an object of the present invention is a cylinder provided with a stopper portion made of a hard synthetic resin layer filled in a concave portion of a convex bead that surrounds and seals around a hole for a combustion chamber. In the head gasket, there is a risk that the hard synthetic resin layer is rubbed and worn by the joint surface of the cylinder head or the cylinder block, and the spring force of the bead sealing the combustion chamber hole is improved.
[0009]
[Means for Solving the Problems]
The metal gasket of the present invention that achieves the above object is formed by laminating at least two layers of an elastic metal plate having at least a combustion chamber hole and a bolt hole, the first metal plate surrounds the combustion chamber hole, and the gasket. A convex bead that protrudes to the outside of the bead, and a stopper portion that restricts compression of the bead, comprising a hard synthetic resin layer that fills a portion of the depth of the recess in the recess of the bead, and a second metal The plate includes a convex bead that surrounds the combustion chamber hole at a position corresponding to the bead of the first metal plate and protrudes in the same direction as the protruding direction of the bead.
[0010]
In the cylinder head gasket of the present invention, as described above, the hard synthetic resin layer constituting the stopper portion is filled in the concave portion of the convex bead around the combustion chamber hole of the first metal plate. The portion located is thicker than the other portions. Therefore, a high seal surface pressure due to the thickness increasing effect and a high seal surface pressure due to the elastic force of the bead are superimposed and concentrated on the bead portion. In addition, since the convex bead of the second metal plate is disposed at a position corresponding to the bead of the first metal plate and protrudes in the same direction as the protruding direction of the bead of the first metal plate. The spring force of the bead of the first metal plate and the spring force of the bead of the second metal plate are superimposed. Therefore, when the gasket of the present invention is mounted and tightened between the cylinder head and the cylinder block, a seal line having a very high surface pressure is formed around the combustion chamber hole.
[0011]
In the present invention, since the second metal plate is laminated on the concave portion of the bead of the first metal plate, the stopper portion made of the hard synthetic resin layer filled in the concave portion of the bead is the first metal plate. And is not covered with the joint surface of the cylinder head or the cylinder block. Therefore, there is no danger of the hard synthetic resin layer constituting the stopper portion being rubbed and worn by the joint surface.
[0012]
It is relatively easy to adjust the filling height of the hard synthetic resin layer constituting the stopper portion into the bead recess as will be described later. Therefore, in the gasket of the present invention, the height of the stopper, that is, the filling height of the hard synthetic resin layer is adjusted depending on the position, and the height of the stopper portion at the position separated from the bolt hole is set to the height of the stopper portion at the position close to the bolt hole. Adjustment to be higher than the above can be realized relatively easily. Then, the seal surface pressure around the combustion chamber hole can be equalized by adjusting the height of the stopper portion according to the distance from the bolt hole in this way.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The details of the present invention will be described below with reference to the drawings of the embodiments. 1 is a plan view of a cylinder head gasket according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view taken along line AA in FIG. 1, and FIG. 3 is an enlarged sectional view taken along line BB in FIG. is there. However, FIG. 1 omits illustration of a cooling water passage hole, an oil passage hole, a bead for sealing these, and the like in order to simplify the drawing. FIG. 1 shows a state in which the surface of the metal plate 1 is not covered with a sealing material layer. In each figure, the same code | symbol has shown the same part.
[0014]
The cylinder head gasket G according to the present invention includes a combustion chamber hole 3 provided at a position and shape aligned with the combustion chamber of the engine, a bolt hole 4 through which a bolt for fastening the cylinder head to the cylinder block, and cooling water not shown. A passage hole, an oil passage hole and a bead for sealing them are provided, and a first and second metal plates 1 and 2 made of an elastic metal plate such as a stainless steel plate and having a thickness of 0.2 to 0.3 mm, for example, are laminated. Configured.
[0015]
The first metal plate 1 includes a convex bead 5 having a cross-sectional shape that surrounds and seals around the combustion chamber hole 3, and the bead 5 extends to the outside of the gasket, that is, the cylinder head (upper side in the figure). Projecting toward. The height of the bead is, for example, 80 to 200 μm. The concave portion 51 of the bead 5 has a hard synthetic resin layer, that is, a synthetic resin layer that is hardly compressed and deformed even when subjected to stress, or that is slightly compressed and slightly deformed, for example, an epoxy resin layer. The stopper part 6 which is filled so as to fill a part of and restricts the compression of the convex bead 5 is configured.
[0016]
Filling the recess 51 with the hard synthetic resin layer can be easily performed by applying or injecting a liquid coating material such as an epoxy resin into the recess 51 and curing it. The filling height of the hard synthetic resin layer, that is, the height of the stopper portion 6 may be substantially constant over the entire length of the bead 5, but the height of the stopper portion 6 is changed according to the distance from the bolt hole 4, and FIG. As shown in FIG. 3, the height h ₁ of the stopper portion 6 at a position separated from the bolt hole 4 (for example, a position intersecting with the AA line) intersects with a position (for example, the BB line) close to the bolt hole 4. It is desirable to make it higher than the height h ₂ of the stopper portion 6 at the position). Thus, by adjusting the height of the stopper portion 6 according to the distance from the bolt hole 4, the seal surface pressure can be equalized around the combustion chamber hole.
[0017]
Specifically, the height of the stopper portion 6 is adjusted, for example, to a bead height of 80 to 200 μm, and the height of the stopper portion 6 is within a range of 30 to 60 μm at a position close to the bolt hole. The height of the stopper portion 6 at a position separated from the bolt hole is selected in the range of 70 to 190 μm within a range not exceeding the depth of the recess 51. However, it is preferable that the height of the stopper portion 6 is at least 10 μm lower than the depth of the concave portion 51, that is, the height of the bead 5 so that the convex bead 5 can ensure elastic deformation all around the combustion chamber hole 3. .
[0018]
Adjustment of the filling height of the hard synthetic resin layer for adjusting the height of the stopper portion 6 in this way is performed by, for example, screen coating of a liquid coating material such as an epoxy resin a plurality of times, and only the portion having a high filling height. It can be carried out relatively easily by additional coating, or by adjusting the coating amount with a dispenser, partial multiple coatings, and the like.
[0019]
The second metal plate 2 is laminated on the first metal plate 1 on the concave 51 side of the bead 5 so as to cover the concave portion 51. The second metal plate 2 includes a convex bead 7 that surrounds and seals the combustion chamber hole 3 at a position corresponding to the bead 5 of the first metal plate 1. The protruding direction of the bead 7 is the same as the protruding direction of the bead 5 of the first metal plate, and protrudes upward in the figure, that is, toward the cylinder head. Therefore, the spring force of the bead 7 and the spring force of the bead 5 overlap, and the spring force of the bead increases. The cross-sectional shape of the bead 7 may be substantially the same as the cross-sectional shape of the bead 5 of the metal plate 1 or may be a convex bead having a cross-sectional shape different from that of the bead 5.
[0020]
8 in the figure is a sealing material layer coated on the outer surface 11 of the metal plate 1 and the outer surface 21 and the inner surface 22 of the metal plate 2, and is a heat-resistant and relatively flexible rubber and synthetic resin such as fluorine rubber and silicone resin. It functions as a so-called micro seal that compensates for irregularities such as scratches, surface roughness, distortion, etc. on the joint surfaces of the cylinder head and the cylinder block and the surfaces of the metal plates 1 and 2. In the figure, only the beads 5 and 7 and both side portions thereof are covered with the sealing material layer, but there is no problem even if they are covered over a wider range.
[0021]
In the cylinder head gasket G according to the present invention described above, the concave portion 51 of the convex bead 5 of the metal plate 1 is filled with the hard synthetic resin layer constituting the stopper portion 6, so that the portion where the bead 5 is located is other than The thickness of the gasket is thicker than that of the portion, and the convex bead 7 of the metal plate 2 protrudes in the same direction at the same position as the bead 5 so that the spring force of the bead 5 and the spring force of the bead 7 are superimposed. Therefore, if the gasket G is mounted between the cylinder head and the cylinder block and tightened, as described above, an extremely high surface pressure seal line is formed around the combustion chamber hole 3, The sealing ability is great. And in the gasket G, since the hard synthetic resin layer which comprises the stopper part 6 incorporated in the convex bead 5 of the metal plate 1 is covered with the metal plates 1 and 2, it is formed with the joint surface of a cylinder head or a cylinder block. There is no risk of rubbing and wearing.
[0022]
In the above description, the convex bead 5 incorporating the stopper portion 6 of the metal plate 1 and the convex bead 7 of the metal plate 2 protrude toward the cylinder head side (the upper side in the figure). Although the description has been made on the assumption that they are stacked on the cylinder block side (lower side in the figure) which is the concave side, conversely, the convex beads 5 and 7 of the metal plates 1 and 2 protrude toward the cylinder block side, and the metal plate 2 is the cylinder. It may be laminated so as to cover the concave portion 51 that is disposed on the head side and is filled with a hard synthetic resin layer that constitutes the stopper portion 6 of the convex bead 5 of the metal plate 1. It is desirable to determine which side of the cylinder head and the cylinder block the convex beads 5 and 7 protrude depending on the structure and operating characteristics of the engine.
[0023]
【The invention's effect】
As described above, the cylinder head gasket of the present invention has the following remarkable effects. That is, in the gasket of the present invention, the effect of increasing the thickness of the gasket and the elastic force of the beads are concentrated and accumulated in the convex bead portion surrounding the combustion chamber hole, so that the surface pressure around the combustion chamber hole is extremely high. A seal wire is formed, and the sealing ability is large. In addition, since the hard synthetic resin filling layer that constitutes the stopper and gives the effect of increasing the thickness is covered with the first and second metal plates, there is a risk of being rubbed and worn by the joint surfaces of the cylinder head and the cylinder block. Absent. Further, when the height of the stopper portion is adjusted according to the distance from the bolt hole, there is an advantage that the seal surface pressure can be equalized around the hole for the combustion chamber.
[Brief description of the drawings]
FIG. 1 is a plan view of a gasket according to an embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view taken along line AA in FIG.
3 is an enlarged cross-sectional view taken along line BB in FIG.
[Explanation of symbols]
3 Combustion chamber holes 5, 7 Convex bead 51 Recess 6 Stopper

Claims (3)

A first metal plate comprising a first bead made of an elastic metal plate and surrounding the combustion chamber hole;
A second metal plate made of an elastic metal plate and provided with a second bead at a position corresponding to the first bead ;
A metal gasket having at least a combustion chamber hole and a bolt hole ,
The first bead is provided with a stopper portion made of a hard synthetic resin that fills a part of the depth of the concave portion on the bead bottom side, so that the deformability is reduced compared to the second bead,
A cylinder head gasket, wherein a first bead and a second bead are laminated so that a top portion of a second bead is positioned in an unfilled portion of a concave portion of the first bead. The height of the stopper portion is adjusted according to the distance from the bolt hole, and the height of the stopper portion at a position away from the bolt hole is higher than the height of the stopper portion at a position close to the bolt hole. The cylinder head gasket according to 1. The cylinder head gasket according to claim 1 or 2, wherein the hard synthetic resin layer is made of an epoxy resin.

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