JP2001165321A - Metal gasket and sealing method using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal gasket and a sealing method using the gasket that suitably seals a three faces mating part as well as a gap made due to level difference of the mating part. SOLUTION: The metal gasket 20 comprises an intermediate plate 21, a lower bead plate 23 and an upper bead plate 22. The thickness of each upper and lower plate 22, 23 is 0.2 mm. Among the three plates, only the intermediate plate 21 is arranged overhung up to an internal periphery of a chain pass (opening) and a step part 21a is formed at the entire periphery thereof. Then, a cold curing silicone rubber 24 is applied to the upper and lower surfaces of the step part 21a thicker than the thickness of the bead plates 22 and 23. The bead plates 22, 23 are arranged adjacent to the step part 21a and then half bead parts 22a, 23a that are expanded to a vertical direction are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing method using a metal gasket used for a cylinder head gasket of an internal combustion engine, for example, and a metal gasket.

[0002]

2. Description of the Related Art As a metal gasket of this type, for example, a gasket described in Japanese Utility Model Laid-Open Publication No. 3-27857 is known.

The metal gasket is interposed between the upper surface of a cylinder block and a chain case attached adjacent to the cylinder block, and the lower surface of a cylinder head. The gasket has through holes at positions corresponding to a plurality of openings such as a chain passage formed in the chain case and a cylinder formed in the cylinder block. Further, in order to ensure the sealing performance of the chain passage and the inside of the cylinder, a bead is formed in the gasket at the periphery of each of the through holes.

[0004] In the three-plane mating portion composed of the cylinder block, the chain case, and the cylinder head,
Due to dimensional tolerances or thermal expansion differences between the cylinder block and the chain case, it is inevitable that a slight step will occur.

[0005] Conventionally, as one of the methods for sealing the step, a method using a FIPG (Formed-in-Place Gasket) is known. The FIPG is applied in a liquid state at the time of assembling, and then becomes an elastic body by some reaction to adhere the assembling portion.

That is, even in the gasket described in the above-mentioned publication, specifically, a room-temperature-curable silicone rubber as the FIPG is provided in a portion of the gasket facing the three-faced portion. This silicon rubber has a property of permeating moisture in the air at room temperature and gradually changing from a liquid state to a rubber state. By providing such a silicone rubber as described above, the sealing performance of the gasket can be maintained even at the step portion of the three-plane mating portion.

[0007]

As described above, by using the FIPG, even in the case of a metal gasket, it is possible to maintain the sealing performance at the step portion of the three-plane mating portion.

When the chain case is mounted adjacent to the cylinder block as described above,
Certainly, the level difference at the three-face mating portion is not negligible, but when such a level difference occurs, the matching between the upper surface of the chain case and the lower surface of the cylinder head is also performed at a portion other than the three-face mating portion. A gap is formed on the surface, and a decrease in sealing performance due to the gap cannot be ignored.

However, the conventional gasket has a structure in which the portion other than the three-face mating portion is sealed only with the bead at the periphery of the chain passage, so that the above-mentioned gap can be sufficiently sealed. Moreover, it is also difficult to ensure the sealing performance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object the purpose of not only a three-plane mating part but also a metal part capable of suitably sealing a gap caused by a step in the three-plane mating part. An object of the present invention is to provide a sealing method using a gasket and a metal gasket.

[0011]

The means for achieving the above object and the effects thereof will be described below. The invention according to claim 1 uses a metal gasket interposed between an upper surface of a cylinder block and a chain case attached adjacent to the cylinder block and a lower surface of the cylinder head, and the cylinder block and the chain are used. In a sealing method using a metal gasket for sealing between a case and a cylinder head, a first metal sheet that is laid over the upper surfaces of the cylinder head and the chain case, and a first metal sheet laminated on the first metal sheet. The first and second metal thin plates have openings formed in portions corresponding to a chain passage formed by the chain case and the cylinder block, and the first and second metal thin plates are formed in the first and second metal thin plates. By projecting only the second metal sheet of the second metal sheet to the inner periphery of the opening, the periphery of the opening is obtained. The step portion is formed, and summarized in that applying a thicker FIPG than the thickness of said first metal sheet on the stepped portion.

According to the above method, when assembling the cylinder head to the cylinder block and the chain case,
The FIPG is expanded to follow the shape of the entire upper edge of the chain path including the three-face mating portion. In this state, the FIPG changes into an elastic body, and seals the entire upper edge of the chain passage. Therefore, even if the above-mentioned steps, gaps, and the like are present, the hermeticity can be suitably maintained. . Also, by providing the first metal sheet, after the above-mentioned assembling, the FIPG has a thickness equivalent to the thickness of the first metal sheet, and contracts / restores in accordance with the expansion / contraction of the chain case. I do. That is, the above-mentioned sealing property can be maintained for a long time.

According to a second aspect of the present invention, in the sealing method using the metal gasket according to the first aspect, a bead is formed in advance on an end of the first thin metal plate facing the step. And

According to the above method, at the time of FIPG application, the FIPG enters the space formed between the bead of the first sheet metal and the second sheet metal. Will be assembled.
For this reason, the sealing property between the lamination of the first metal sheet and the second metal sheet as the metal gasket can be further improved. Further, since the entire upper edge of the chain passage is double-sealed by the FIPG and the bead, the sealing property can be maintained more suitably.

According to a third aspect of the present invention, in the sealing method using the metal gasket according to the first or second aspect, a room temperature curing type FIPG is used as the FIPG.

According to the above method, after the FIPG has been applied to a predetermined position, the gasket need only be assembled at the predetermined position. The FIPG changes into an elastic body. Therefore, it is not necessary to provide any special operation process for curing the FIPG.

According to a fourth aspect of the present invention, in the sealing method using the metal gasket according to the third aspect, the thickness of the first metal sheet is reduced by applying moisture in the atmosphere to the FIPG applied to the step. The gist of the invention is to make the thickness sufficient to allow sufficient penetration.

The room temperature-curable FIPG changes from a liquid state to a rubber state due to permeation of atmospheric moisture. Therefore, according to the method of setting the first metal sheet to the above-described thickness, a large surface area of the FIPG exposed to the air can be ensured, and the FIPG can be surely changed to the rubber state. Will be able to do it.

According to a fifth aspect of the present invention, in the sealing method using the metal gasket according to the fourth aspect, the first thin metal plate has a thickness of 0.2 mm or more.

As described above, by setting the thickness of the first metal sheet to 0.2 mm or more, the FIPG
Can permeate the moisture in the atmosphere sufficiently and in a short time. Therefore, the change of the FIPG to the rubber state can be performed reliably and in a short time.

According to a sixth aspect of the present invention, there is provided a cylinder block, a chain case mounted adjacent to the cylinder block, interposed between an upper surface of the cylinder head and a lower surface of the cylinder head. In a metal gasket for sealing between a head and a head, the gasket includes: a first metal sheet which is laid over the upper surface of the cylinder head and the chain case; and a second metal sheet laminated on the first metal sheet. , These first
And the second metal sheet has an opening at a portion corresponding to a chain passage formed by the chain case and the cylinder block, and a second metal sheet of the first and second metal sheets. Only the opening has a shape projecting to the inner periphery of the opening to form a step around the opening, and the step is coated with FIPG.

According to the above structure, since the sealing performance is enhanced by the FIPG on the entire periphery of the upper end of the chain passage, not only the above-mentioned step of the three-face mating portion but also a gap caused by the step is generated. However, the suitable sealing performance is maintained.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

First, an outline of a sealing method and a metal gasket according to the embodiment will be described with reference to FIGS. 1 is a side view schematically showing a state in which the gasket is assembled, FIG. 2 is a plan view showing a plan structure of a part of the gasket, and FIG.
FIG. 3 is a sectional view taken along line 3-3 in FIG.

As shown in FIG. 1, the metal gasket 20 is interposed between the upper surface of the cylinder block 11 and the chain case 12 attached adjacent to the cylinder block 11 and the lower surface of the cylinder head 13. .
Then, the cylinder block 11 and the chain case 12
An oil pan 14 is disposed below the oil pan. These members are fastened at a plurality of locations by bolts or the like (not shown) and are integrated.

The chain case 12 has a substantially U-shaped horizontal cross section, and the open end side of the substantially U-shaped cross section abuts against and is fixed to the side surface of the cylinder block 11 so that a cam (not shown) is formed. A chain passage in which a shaft driving chain runs is formed. When the chain runs, the lubricating oil in the oil pan 14 is sprayed on the chain.

On the other hand, as shown in FIG. 2, the metal gasket 20 has a bore hole 30 and a bolt insertion hole 31 at positions corresponding to a plurality of combustion chambers and bolt holes (not shown) formed in the cylinder block 11. Is provided. Further, the gasket 20 is provided with a chain insertion hole 32 as an opening at a position corresponding to the chain passage.

As shown in FIG. 3, the metal gasket 20 used in the sealing method of the present embodiment is a second gasket.
An intermediate plate 21 as a metal thin plate, a lower bead plate 23 as a first metal thin plate abutting on the lower surface of the intermediate plate 21, and a third bead abutting on the upper surface of the intermediate plate 21 And an upper bead plate 22 as a thin metal plate. The upper and lower bead plates 22 and 23 have a thickness of 0.2 mm.

The gasket 20 is provided so that only the intermediate plate 21 of the intermediate plate 21 and the upper and lower bead plates 22 and 23 extends to the inner periphery of the chain passage at the periphery of the chain insertion hole 32. Have been. As a result, the step 21a is formed on the entire periphery of the chain insertion hole 32. Room temperature-curable silicone rubber 24 as FIPG is applied to the upper and lower surfaces of the step portion 21a so as to be thicker than the bead plates 22 and 23. Furthermore, half bead portions 22a and 23a which are adjacent to the step portion 21a and bulge in the vertical direction are provided on the entire peripheral edge of the chain insertion hole 32 of the bead plates 22 and 23, respectively. Here, the room-temperature-curable silicone rubber 24 has a property of permeating moisture in the air at room temperature and gradually changing from a liquid state to a rubber state.

Then, as shown in FIG. 4, when such a gasket 20 is assembled to the cylinder block 11 or the like, a stepped portion A of a three-plane mating portion composed of the cylinder block 11, the chain case 12, and the cylinder head 13 is formed.
, The entire periphery of the upper end of the chain passage is sealed with the room-temperature-curable silicone rubber 24.

That is, at the time of assembling, since the silicon rubber 24 is still in a liquid state, the silicon rubber 24 is pushed and spread according to the shape of the stepped portion A, and the upper and lower bead plates 22 and 23 are separated. The silicon rubber 24 gradually changes to a rubber state while keeping the thickness of about the thickness. As described above, by sealing the entire upper edge of the chain passage including the stepped portion A with the silicone rubber 24, the sealing property in the chain passage can be suitably maintained.

Further, the gasket 20 can be assembled in a state where the silicone rubber 24 has also entered the spaces 22b and 23b formed between the intermediate plate 21 and the half bead portions 22a and 23a. Therefore, the intermediate plate 21 of the gasket 20 and each of the upper and lower bead plates 22 and 23
And the sealing property between the layers can be improved.

Further, after the gasket 20 is assembled to the cylinder block 11 or the like, the gasket 20 may be left as it is, or the moisture in the air in the chain passage may be removed during the subsequent normal working process. The permeation causes the room-temperature-curable silicone rubber 24 to change to a rubber state. For this reason,
There is no need to provide any special work process for curing the room-temperature-curable silicone rubber 24.

Next, with reference to FIG. 5, the relationship between the clearance of the fastening portion and the curing width of the room-temperature-curable silicone rubber 24 will be described.
In addition, FIG. 5 shows that the room-temperature-curable silicone rubber 24 is filled between opposing side surfaces of two flange portions having a width of 16 mm, and the silicon rubber 2 from the end after being left for 24 hours.
4 is a graph showing the results of measuring the curing width of No. 4 while changing the distance between the facing surfaces.

As shown in the graph of FIG. 5, the hardening width tends to increase as the clearance between the fastening portions increases. In other words, when the clearance between the fastening portions is large, the surface area that comes into contact with the air is large, and the moisture in the air is easily permeated. As a result, the room-temperature-curable silicone rubber 24 quickly changes from a liquid state to a rubber state. In particular, when the clearance between the fastening portions is 0.2 mm or more, the curing time of the silicone rubber 24 can be shortened. In the present embodiment, the gap between the fastening portions corresponds to the thickness of the upper and lower bead plates 22 and 23 when the metal gasket 20 is assembled to the cylinder block 11 and the like.

As described in detail above, according to the sealing method and the metal gasket 20 of this embodiment, the following excellent effects can be obtained. (1) When assembling the metal gasket 20 to the cylinder block 11 or the like, the room-temperature-curable silicone rubber 24 is spread out following the shape of the entire upper edge of the chain passage including the three-faced mating portion. The silicone rubber 2
4 changes to a rubber state and seals the chain passage.
Therefore, the cylinder block 11 and the chain case 1
Even if there is a dimensional tolerance of 2 or the like, the sealing performance of the chain passage can be suitably maintained.

(2) The upper and lower bead plates 22,
With the provision of the silicone rubber 23, the silicon rubber 24 has a thickness equivalent to the thickness of the bead plates 22, 23 after assembly. For this reason, the silicone rubber 24 contracts and restores in accordance with the expansion and contraction of the chain case 12, so that the sealing performance of the chain passage can be suitably maintained.

(3) Since the silicon rubber 24 is in a liquid state at the time of assembling, a bending stress is generated in the intermediate plate 21 even if the silicon rubber 24 is displaced up and down when the silicon rubber 24 is applied to the step portion 21a. Absent. For this reason, the intermediate plate 2
It is not necessary to increase the rigidity by increasing the plate thickness and the like of 1, and the weight of the gasket 20 can be reduced.

(4) The metal gasket 20 is
1 and the half bead portions 22a and 23a can be assembled in a state where the silicone rubber 24 enters the spaces 22b and 23b formed between the half bead portions 22a and 23a. Therefore, the intermediate plate 21 of the gasket 20 and each of the upper and lower bead plates 2
It is possible to improve the sealing property between the laminations with the layers 2 and 23. Further, the entire upper edge of the chain passage is covered with the silicone rubber 24 and the half bead portions 22a and 22a.
3a allows the seal to be double-sealed, so that the sealing property is more suitably maintained.

(5) The room-temperature-curable silicone rubber 24 is applied to a predetermined position of the gasket 20 and then the gasket 20 may be assembled at the predetermined position. While performing, the silicon rubber 24 changes to a rubber state,
There is no need to provide any special work process.

(6) By setting the thickness of the upper and lower bead plates 22 and 23 to 0.2 mm and securing a large surface area of the room-temperature-curable silicone rubber 24 in contact with air, the moisture in the air in the chain case is reduced. Can be sufficiently penetrated. For this reason, the change of the silicon rubber 24 to the rubber state can be sufficiently performed in a short time.

The above embodiment can be modified as appropriate, for example, as follows. In the above embodiment, the upper and lower bead plates 22 and 2
The thickness of each of the sheets No. 3 was set to 0.2 mm. Further, the thickness of each of the bead plates 22 and 23 does not need to be equal, and for example, the lower bead plate 23 may be provided with a greater thickness than that of the upper bead plate 22. In short, the plate thickness may be any value that allows sufficient penetration of moisture in the atmosphere into the room-temperature-curable silicone rubber 24.

In the above embodiment, the room-temperature-curable silicone rubber 24 is used, but the FIPG is not limited to this silicone rubber. Any material may be used as long as it is applied in a liquid state at the time of assembly and then becomes an elastic body by some reaction at room temperature. Alternatively, for example, a room temperature-curable resin or the like may be used.

In the above embodiment, the half bead portions 22a and 23a are provided on the periphery of the chain insertion hole 32 of the upper and lower bead plates 22 and 23.
Alternatively, the configuration may be changed to a configuration without the a and 23a. Further, a configuration in which a bead portion is provided on only one of the bead plates 22 and 23 may be changed.

In the above embodiment, the metal gasket 20 has the upper bead plate 22 (third metal thin plate). However, the gasket 20 may not have the upper bead plate 22. At this time, the FIPG is placed on the upper surface of the intermediate plate 21.
Is not applied, but an effect similar to that of the above embodiment can be obtained.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing an assembled state of an embodiment of a sealing method and a metal gasket of the present invention.

FIG. 2 is a plan view showing a partial planar structure of the gasket.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is an enlarged cross-sectional view showing a three-plane mating portion in a state where the gasket is assembled.

FIG. 5 is a graph showing a relationship between a clearance of a fastening portion and a curing width of a room-temperature-curable silicone rubber.

[Explanation of symbols]

11 ... cylinder block, 12 ... chain case, 13
... Cylinder head, 20 ... Metal gasket, 21 ... Intermediate plate, 21a ... Step portion, 23 ... Lower bead plate, 23a ... Half bead portion, 24 ... Silicon rubber cured at room temperature, 32 ...
Chain insertion hole, A: stepped portion.

Claims (6)

[Claims] The present invention relates to a cylinder block, a chain case and a cylinder head, which are provided between a top surface of a cylinder block and a chain case mounted adjacent to the cylinder block and a bottom surface of the cylinder head. A metal sheet that seals between the first metal sheet and the first metal sheet, and a second metal sheet laminated on the first metal sheet. An opening is formed in the first and second metal sheets at a position corresponding to a chain passage formed by the chain case and the cylinder block, and the first and second metal sheets are formed. Of the second metal sheet is extended to the inner periphery of the opening to form a step around the opening. A sealing method using a metal gasket, wherein FIPG is applied to the step portion so as to be thicker than the thickness of the first metal sheet. 2. A sealing method using a metal gasket according to claim 1, wherein a bead is formed in advance on an end of the first thin metal plate facing the step. Had sealing method. 3. A sealing method using a metal gasket according to claim 1 or 2, wherein a room temperature curing type FIPG is used as the FIPG. 4. A sealing method using a metal gasket according to claim 3, wherein the thickness of the first thin metal plate is applied to the step.
A sealing method using a metal gasket, wherein the PG has a thickness enough to allow atmospheric moisture to sufficiently penetrate into the PG. 5. A sealing method using a metal gasket according to claim 4, wherein the thickness of the first thin metal plate is 0.2 mm or more. 6. A cylinder block and a chain case mounted adjacent to the cylinder block, interposed between an upper surface and a lower surface of the cylinder head to seal between the cylinder block and the chain case and the cylinder head. A metal gasket, comprising: a first metal sheet that is laid over the upper surfaces of the cylinder head and the chain case; and a second metal sheet that is stacked on the first metal sheet. The metal sheet has an opening at a position corresponding to a chain passage formed by the chain case and the cylinder block, and only the second metal sheet of the first and second metal sheets has an opening. A step is formed around the opening so as to extend to the inner periphery of the opening, and FIPG is applied to the step. A metal gasket characterized by the following.