JPH0612870U - Metal cylinder head gasket - Google Patents

Abstract

(57) [Summary] [Purpose] Even if the bottom surface of the cylinder head is scratched, the liquid-tightness of the surrounding area of the through hole 4 is ensured. A foam coating layer 12 is formed on a part of a thin metal plate 8 facing a lower surface of a cylinder head when used, around a through hole 4 for circulating cooling water or lubricating oil. The foam coating layer 12 is crushed during use, but if there is a scratch on the lower surface of the cylinder head, the foam coating layer 12 closes the inside of this scratch.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The metal cylinder head gasket according to the present invention is sandwiched between the lower surface of the cylinder head and the upper surface of the cylinder block of the internal combustion engine, and is used to maintain airtightness and liquid tightness between both surfaces.

[0002]

[Prior art]

 A cylinder head gasket is sandwiched between the lower surface of the cylinder head and the upper surface of the cylinder block of the internal combustion engine, so that high-pressure combustion gas generated in the cylinder or cooling water or lubricating oil flowing between the cylinder block and the cylinder head is retained. Prevent it from leaking to the outside. As such a cylinder head gasket, a metal cylinder head gasket in which a plurality of thin metal plates are superposed on each other has been conventionally known.

FIG. 3 shows an example of such a metal cylinder head gasket 1. The metal cylinder head gasket 1 has circular bore holes 2 and 2 matching the opening shape of the cylinder top, small circular holes 3 and 3 through which bolts for fixing the cylinder head to the cylinder block are inserted, and cooling water or Through holes 4 and 4 for passing lubricating oil are provided.

Grommets 5 are attached to the peripheral portions of the bore holes 2 and 2 as shown in FIG. 3, or metal thin plates on which ridges 6 and 6 are formed as shown in FIG. 4 described below. 7 and 7 are piled up. With this configuration, when the metal cylinder head gasket 1 is strongly sandwiched between the cylinder block upper surface and the cylinder head lower surface, the pressing force at the peripheral portions of the bore holes 2 and 2 increases, and Airtightness around the bore holes 2 and 2 is sufficiently achieved.

Conventionally, such a metal cylinder head gasket 1 is formed by stacking a plurality of metal thin plates 8 to 10 (three in the illustrated example) such as galvanized steel plates and stainless steel plates, as shown in FIG. It is composed of. Coating layers 11a and 11b of fluororubber are formed on both surfaces of some of the metal thin plates 8 and 10 among the plurality of metal thin plates 8 to 10. Among the coating layers 11a and 11b, the coating layers 11a and 11a facing the intermediate thin metal plate 9 are cooled from between the adjacent thin metal plates in a state where the plurality of thin metal plates 8 to 10 are stacked. Prevent water and lubricating oil from leaking. Further, when the metal cylinder head gasket 1 is assembled, the coating layers 11b, 11b exposed on both front and back surfaces of the metal cylinder head gasket 1 come into contact with the upper surface of the cylinder block or the lower surface of the cylinder head. Prevent cooling water and lubricating oil from leaking from the top surface of the block or the bottom surface of the cylinder head.

[0006]

[Problems to be solved by the device]

 The metal cylinder head gasket of the present invention ensures liquid-tightness around the through hole even if the cylinder head is made of an aluminum alloy, and the cooling water and lubricating oil flowing through the through hole keeps the cylinder head from flowing. It securely prevents leakage from between the lower surface and the metal cylinder head gasket.

[0007] In recent years, in order to reduce the weight of the engine, the case where the cylinder head is manufactured by aluminum alloy is increasing. However, the cylinder head made of aluminum alloy is a cylinder head made of cast iron which has been generally used conventionally. Compared to scratches. For this reason, the lower surface of the cylinder head may be damaged after the cylinder head is manufactured and before the cylinder head and the cylinder block are joined together. If the depth of the scratch is sufficiently smaller than the thickness of the coating layer 11b formed on the surface of the metal cylinder head gasket 1, no particular problem will occur.

However, while the thickness dimension of the coating layer 11b is about 20 to 25 μm, the lower surface of the cylinder head is often scratched deeper than this thickness dimension. . When a cylinder head having such a scratch is attached to the cylinder block via the conventional metal cylinder head gasket 1, cooling is performed from between the lower surface of the cylinder head and the surface of the metal cylinder head gasket 1. Water or lubricating oil may leak.

The metal cylinder head gasket of the present invention has been devised in view of the above circumstances.

[0010]

[Means for solving the problem]

 The metal cylinder head gasket of the present invention is composed of a thin metal plate like the above-mentioned conventional metal cylinder head gasket, and has a circular bore hole matching the opening shape of the cylinder top and cooling water or lubricating oil. It has a plurality of through holes for passing through and is used in a state of being sandwiched between the upper surface of the cylinder block and the lower surface of the cylinder head.

In particular, in the metal cylinder head gasket of the present invention, at least a part of the surface facing the lower surface of the cylinder head at the time of use is made by foaming an elastic material around the through hole. It is characterized by forming a foamed coating layer with many closed cells inside.

[0012]

[Action]

 The operation of the metal cylinder head gasket of the present invention configured as described above when maintaining the sealing property between the upper surface of the cylinder block and the lower surface of the cylinder head is substantially the same as that of the conventional metal cylinder head gasket described above. is there.

In particular, in the case of the metal cylinder head gasket of the present invention, the liquid-tightness between the metal cylinder head gasket and the lower surface of the cylinder head in the peripheral portion of the through hole is maintained by the foam coating layer. The foam coating layer can be formed sufficiently thicker than the conventional coating layer. When the metal cylinder head gasket is strongly sandwiched between the upper surface of the cylinder block and the lower surface of the cylinder head, the metal cylinder head gasket is compressed while following the irregularities on the lower surface of the cylinder head.

Therefore, even if the lower surface of the cylinder head is slightly scratched, it is possible to sufficiently maintain the liquid tightness around the through hole.

[0015]

【Example】

 FIG. 1 shows a first embodiment of the present invention. Of the three metal thin plates 8 to 10 constituting the metal cylinder head gasket 1a, fluorocarbon rubber coating layers 11a and 11b are formed on both sides of the metal thin plate 10 facing the upper surface of the cylinder block during use. There is. Of the two coating layers 11a and 11b, the coating layer 11a that faces the intermediate metal thin plate 9 is formed between the adjacent metal thin plates 9 and 10 in the state where the plurality of metal thin plates 8 to 10 are stacked. Prevent leakage of cooling water and lubricating oil. In addition, the coating layer 11b facing the upper surface of the cylinder block when in use contacts the upper surface of the cylinder block, preventing cooling water or lubricating oil from leaking between the metal cylinder head gasket 1 and the upper surface of the cylinder block. To prevent.

On the other hand, a coating layer 11a is formed on one surface of the metal thin plate 8 facing the lower surface of the cylinder head when in use, and the surface facing the intermediate metal thin plate 9 to form a pair of metal thin plates 8 , 9 and 9 are prevented from leaking the cooling water and lubricating oil.

Further, on the other surface of the thin metal plate 8 that faces the lower surface of the cylinder head when in use, the entire circumference of the through hole 4 for circulating cooling water or lubricating oil is surrounded and foamed. The coating layer 12 is formed. The foam coating layer 12 is formed by foaming an elastic material such as silicone rubber, urethane, fluorine rubber, nitrile butadiene rubber (NBR), and acrylic rubber, and has many closed cells inside.

When forming the foam coating layer 12 as described above, a viscous fluid formed by mixing the elastic material and the foaming agent (powder) is applied only around the through hole 4 by screen coating. Then, the viscous fluid is heated to foam. The coating thickness of the viscous fluid by the screen coating is, eg, about 30 μm. In this case, when silicon is used as the elastic material, the thickness of the foamed coating layer 12 obtained after heating is about 100 μm.

As in the case of the conventional structure, the thin metal plates 7, 7 having the protrusions 6, 6 are overlapped around the bore hole 2 surrounding the cylinder hole, and the metal cylinder head is formed. When the gasket 1a is strongly sandwiched between the upper surface of the cylinder block and the lower surface of the cylinder head, the pressing force on the peripheral portions of the bore holes 2 and 2 is increased to maintain airtightness around the bore holes 2 and 2. I am trying to make it possible.

The metal cylinder head gasket 1a of the present invention configured as described above has a space between the upper surface of the cylinder block and the lower surface of the cylinder head, similar to the conventional metal cylinder head gasket 1 (FIGS. 3 to 4) described above. It is sandwiched to maintain the sealing property between both sides.

Particularly, in the case of the metal cylinder head gasket of the present invention, the foam coating layer 12 is used to maintain the liquid tightness between the upper surface of the metal cylinder head gasket 1a and the lower surface of the cylinder head in the peripheral portion of the through hole 4. To be The foam coating layer 12 can be formed sufficiently thicker than the conventional coating layer 11b (FIG. 4). When the metal cylinder head gasket 1a is strongly sandwiched between the cylinder block upper surface and the cylinder head lower surface, the metal cylinder head gasket 1a is compressed while following the irregularities on the lower surface of the cylinder head.

For example, when the lower surface of the cylinder head is scratched and recessed, the compression amount of a part of the foam coating layer 12 facing the scratch is equal to the compression amount of the other part. Less than. Then, the inside of the scratch is filled with the foamed elastic material forming the foamed coating layer 12. Therefore, the cooling water and the lubricating oil flowing through the through holes 4 will not leak to the outside through the scratches. As a result, even if the lower surface of the cylinder head is slightly scratched, it is possible to sufficiently maintain the liquid tightness around the through hole 4.

When the foam coating layer 12 is formed around the through hole 4, the inner diameter R of the foam coating layer 12 is made slightly larger than the diameter D of the through hole 4 (R> D), It is preferable to form a portion 13 where the thin metal plate 8 is exposed between the peripheral edge of the through hole 4 and the inner peripheral edge of the foam coating layer 12. This is because when the elastic material forming the foam coating layer 12 is peeled off from the thin metal plate 8 as it is used for a long period of time, the small pieces generated by this peeling flow through the through holes 4. This is to prevent mixing in water or lubricating oil. As described above, the work of forming the foam coating layer 12 while forming the exposed portion 13 of the thin metal plate 8 is performed by applying the viscous fluid to the desired portion of the thin metal plate 8 by screen coating as described above. By doing so, it can be done easily.

Further, in recent years, in order to further reduce the weight of the engine, not only the cylinder head but also the cylinder block is increasingly made of an aluminum alloy. In such a case, the cylinder block is opposed to the lower surface of the cylinder head. The foam coating layer 12 is formed not only on the surface of the thin metal plate 8 but also on the surface of the thin metal plate 10 facing the upper surface of the cylinder block (the lower surface in FIG. 1).

Next, FIG. 2 shows a second embodiment of the present invention. In the case of this embodiment, the foam coating layers 12, 12 are formed on the both sides of the metal cylinder head gasket 1b in the peripheral portion of the through hole 4, respectively, and the peripheral portion of the bore hole 2 is made of a fluorine-based heat-resistant material. Coating layers 14, 14 are formed. Further, by folding back a part of the metal thin plate 15 at the peripheral portion of the bore hole 2, the thickness of the peripheral portion of the bore hole 2 is increased.

In the case of the present embodiment, the foam coating layers 12 and 12 are used to maintain liquid-tightness in the peripheral portion of the through hole 4, and at the same time, the coating layers 14 and 14 and the folded portion of the metal thin plate 15 allow Airtightness is maintained in the peripheral portion of the bore hole 2.

[0027]

[Effect of device]

 Since the metal cylinder head gasket of the present invention is constructed and operates as described above, even if the lower surface of the cylinder head is scratched, it is possible to securely maintain the liquid tightness between the lower surface and the lower surface of the cylinder head. It is possible to improve engine reliability by preventing leakage of cooling water and lubricating oil.

[Brief description of drawings]

FIG. 1 is a view corresponding to an enlarged AA cross section of FIG. 3, showing an embodiment of the present invention.

FIG. 2 is a view similar to FIG. 1 showing the second embodiment.

FIG. 3 is a plan view showing a metal cylinder head gasket to which the present invention is applied.

FIG. 4 is a view corresponding to an AA cross section of FIG. 3, showing an example of a conventional cross-sectional shape.

[Explanation of symbols]

 1, 1a, 1b Metal cylinder head gasket 2 Bore hole 3 Small circular hole 4 Through hole 5 Grommet 6 Protrusions 7, 8, 9, 10 Metal thin plate 11a, 11b Coating layer 12 Foam coating layer 13 Part 14 Coating layer 15 Metal thin plate

Claims (1)

[Scope of utility model registration request] 1. A cylinder block upper surface, which is formed of a plate-shaped thin metal plate, has a circular bore hole matching the opening shape of the cylinder top, and a plurality of through holes for passing cooling water or lubricating oil. In the metal cylinder head gasket used in a state of being sandwiched between the cylinder head and the lower surface of the cylinder head, at least a part of the surface facing the lower surface of the cylinder head at the time of use is provided with an elastic material around the through hole. A metal cylinder head gasket characterized by having a foam coating layer formed by foaming and having a large number of closed cells inside.