WO2013014522A2

WO2013014522A2 - Gasket

Info

Publication number: WO2013014522A2
Application number: PCT/IB2012/001434
Authority: WO
Inventors: Takahiro Harada; Takayasu Sato; Tomoaki Matsubara
Original assignee: Toyota Jidosha Kabushiki Kaisha; Nippon Gasket Co., Ltd.
Priority date: 2011-07-26
Filing date: 2012-07-25
Publication date: 2013-01-31
Also published as: JP2013029117A; WO2013014522A3

Abstract

A gasket (1) includes an inner plate (11), and a coating layer (12) formed on a surface (an upper surface and a lower surface) of the inner plate (11). Add-in material (13) (graphite) having a higher thermal conductivity than material (nitrile rubber) of the coating layer (12) is added into the coating layer (12). The add-in material (13) has a spherical shape, and a particle diameter (d) of the add-in material (13) is equal to or greater than a thickness (t) of the coating layer (12). That is, one end of the add-in material (13) protrudes from a surface of the coating layer (12), and the other end of the add-in material (13) is in contact with the surface of the inner plate (11).

Description

GASKET

BACKGROUND OF THE INVENTION

1. Field of the Invention

(0001J The invention relates to a gasket interposed between a pair of flanges arranged opposing one another.

2. Description of Related Art

[0002) Japanese Utility Model Application Publication No. 1 -60074 (JP 1 -60074 U), for example, describes a gasket. The gasket described in JP 1-60074 U is interposed between a cylinder head and a cylinder block of an internal combustion engine. A seal membrane made of resin is provided on a surface of a core plate of the gasket. The seal membrane deforms in accordance with microscopic asperities present on the mating surfaces of the cylinder head and the cylinder block. Therefore, any gaps between the gasket and these mating surfaces are able to be filled in, and as a result, a seal is maintained.

[0003] However, this kind of seal membrane is formed by material (e.g., resin such as nitrile rubber) having a low thermal conductivity than the core plate. Therefore, heat from the cylinder block is not easily transferred to the cylinder head due to the presence of this seal membrane, which is one contributing factor to an increase in the temperature of a cylinder bore in particular. As a result, the amount of oil consumed may increase and the durability of the cylinder bore wall may decrease. Also, when the temperature between cylinder bores, where there is a particular tendency for combustion heat to concentrate, increases, the cylinder bores may thermally deform, and when this happens, the friction produced as pistons move back and forth may increase.

[0004] As a countermeasure, it is possible to adhere a sheet made of graphite that has high thermal conductivity to the surface of the core plate, instead of the resin seal membrane, for example. However, in this case, the graphite tends to peel away from the gasket surface, and as a result, the seal is lost.

[0005] This issue is not limited to a gasket of an internal combustion engine, but is generally common in cases in which a gasket is interposed between a pair of flanges arranged opposing one another.

SUMMARY OF THE INVENTION

[0006] The invention thus provides a gasket capable of improving heat dissipation without losing sealability.

[0007] One aspect of the invention relates to a gasket that is interposed between a pair of flanges arranged opposing one another, that includes a core plate, and a seal membrane formed on a surface of the core plate. Add-in material having a higher thermal conductivity than material of the seal membrane is added into the seal membrane. Also, one end of the add-in material protrudes from a surface of the seal membrane, and the other end of the add-in material is in contact with the surface of the core plate.

[0008] According to this structure, when the gasket is assembled between the pair of flanges, one end of the add-in material contacts the surface of a flange and the other end of the add-in material contacts the surface of the core plate of the gasket. Therefore, heat is directly transferred between the surface of the flange and the surface of the core plate of the gasket by the add-in material that has a highemhermal conductivity than the material of the seal membrane. Accordingly, the heat dissipating ability of the gasket is able to be improved without losing sealability.

[0009] In the gasket described above, the add-in material may be generally granular, and a particle diameter of the add-in material may be equal to or greater than a thickness of the seal membrane.

[0010] When the add-in material is generally granular and the particle diameter of the add-in material is equal to or greater than the thickness of the seal membrane, as with structure described above, the first aspect of the invention in which one end of the add-in material protrudes from the surface of the seal membrane, and the other end of the add-in material is in contact with the surface of the core plate can easily be realized.

[0011] It should be noted that when the add-in material in which the particle diameter is much smaller than the seal membrane is added, the heat dissipating ability of the seal membrane as a whole is improved somewhat by the add-in material that has high thermal conductivity being added. However, when heat is transferred in the direction of the membrane thickness, the heat will alternately pass through the seal material that has low thermal conductivity and the add-in material that has high thermal conductivity, so there is a limit as to just how much more the heat dissipating ability of the gasket as a whole can be improved.

[0012] In the gasket described above, the add-in material may be made of material having a lower hardness than the pair of flanges and the core plate, and be able to deform when the gasket is in a state assembled between the pair of flanges.

(0013] According to this structure, when the gasket is assembled between the pair of flanges, the add-in material will deform upon receiving a compression load from the flanges and the core plate of the gasket. Thus, gaps can be inhibited from being created as a result of the add- in material being arranged between the flanges and the gasket. Also, the hardness of the add-in material is lower than the harnesses of the pair of flanges and the core plate, so neither the flanges nor the core plate will deform due to the add-in material. Accordingly, the seal between the gasket and the flanges is able to be well maintained.

[0014J In the gasket described above, the add-in material may be graphite. Graphite is material that has a high thermal conductivity and deforms easily under a compression load. As a result, the add-in material is able to have a lower hardness than the pair of flanges and the core plate, and to deform when the gasket is in a state assembled between the pair of flanges.

[0015] In the gasket described above, the pair of flanges may be a cylinder head and a cylinder block of an internal combustion engine.

[0016] According to this structure, the transfer of heat between the cylinder block and the cylinder head is able to be appropriately promoted via the gasket. With the gasket described above, the internal combustion engine may be a multiple cylinder internal combustion engine having a plurality of cylinders, and the add-in material may be added only at a portion of the gasket that corresponds to an area in between cylinder bores.

[0017] In a multiple cylinder internal combustion engine having a plurality of cylinders, the temperature tends to increase particularly in the area between cylinder bores. Therefore, even though adding the add-in material to the entire surface of the gasket would enable the heat dissipating ability of the entire gasket to be increased, the area in between cylinder bores would still become higher in temperature than another portion, and this temperature difference between these areas may not be able to be reduced.

(0018] Regarding this, with the structure described above, the add-in material is added only at a portion of the gasket that corresponds to an area in between cylinder bores, so the heat dissipating ability of this portion is increased, thus making it possible to suitably suppress an increase in temperature between cylinder bores. Also, the add-in material is not added at a portion other than this portion, so the temperature difference between these portions is also able to be appropriately reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019J Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIG 1 is a plan view showing the planar structure of a cylinder head gasket according to one example embodiment of the invention;

FIG 2 is a sectional view showing the sectional structure of the cylinder head gasket according to the example embodiment;

FIG 3A is a sectional view showing a frame format of the sectional structure centered around the cylinder head gasket according to the example embodiment, in a state in which a compression load is not being applied to the gasket; and FIG 3B is a sectional view showing a frame format of the sectional structure centered around the cylinder head gasket according to the example embodiment, in a state in which a compression load is being applied to the gasket.

DETAILED DESCRIPTION OF EMBODIMENTS

[0020J Hereinafter, an example embodiment in which the gasket of the invention is described as a cylinder head gasket (hereinafter simply referred to as "gasket 1") of an in-line four-cylinder gasoline engine will be described in detail with reference to FIGS. 1 to 3B.

[0021] As shown in FIG 1 , four cylinder bore holes la are formed in the gasket 1, corresponding to four cylinder bores of the engine. As shown in FIG 2, the gasket 1 includes an inner plate 11 made of stainless steel, and a coating layer 12 made of nitrile rubber that is applied to all of both surfaces of this inner plate 1 1. The thickness of the inner plate 11 is 200 μηι, while the thickness t of the coating layer 12 on one side is 25 μιτι.

[0022] Also, add-in material 13 that has a higher thermal conductivity λί than the thermal conductivity Xc of the material (nitrile rubber) of the coating layer 12 is added into the coating layer 12, as is shown in both FIGS. 3 A and 3B, at the portions indicated by hatching in FIG 1 in particular, that is, at adding portions 1 c of hole edge portions l b of the gasket 1 that correspond to the areas between cylinder bores. This add-in material 13 is spherical graphite that has a lower hardness than a cylinder block 30 and a cylinder head 40 (both of which are made of aluminum alloy).

[0023] As shown in FIG 3A, when a compression load is not acting on the gasket 1 , the particle diameter d of the add-in material 13 is equal to or greater than the thickness t of the coating layer 12 (d≥ t). More specifically, the particle diameter d of the add-in material 13 is 25 to 30 μπι, inclusive, which is approximately 1.0 to 1.2 times the thickness t (25 μτη) of the coating layer 12.

[0024] When the amount of add-in material 13 that is added to the coating layer 12 is increased, the heat dissipating ability of the overall gasket 1 consequently increases. However, through testing it has been confirmed that even if 15% or more by weight of graphite (i.e., the add-in material 13) with respect to the nitrile rubber (i.e., the coating layer 12) in a paste state is added, the heat dissipating ability of the gasket 1 will not increase any more. Therefore, with the gasket 1 according to this example embodiment, 15% by weight of the add-in material 13 with respect to the coating layer 12 in a paste state is added.

[0025J Next, the operation of this example embodiment will be described. When the gasket 1 is assembled between an upper surface 31 of the cylinder block 30 and a lower surface 41 of the cylinder head 40, a compression load from the cylinder block 30 and the cylinder head 40 is received by the gasket 1. In this case, the add-in material 13 plastic deforms upon receiving this compression load, as shown by FIG 3B. As a result, on the cylinder block 30 side of the coating layer 12, the lower end of the add-in material 13 contacts the upper surface 31 of the cylinder block 30, and the upper end of the add-in material 13 contacts the lower surface of the inner plate 11. Also, on cylinder head 40 side of the coating layer 12, the upper end of the add-in material 13 contacts the lower surface 1 of the cylinder head 40, and the lower end of the add-in material 13 contacts the upper surface of the inner plate 1 1. Therefore, heat is directly transferred between the upper surface 31 of the cylinder block 30 and the lower surface of the inner plate 11 , and between the upper surface of the inner plate 11 and the lower surface 41 of the cylinder head 40, by the add-in material 13.

[0026] With the gasket according the example embodiment described above, the operational effects described below are able to be obtained. First, a first operational effect will be described. The gasket 1 includes the inner plate 11 and the coating layer 12 that is formed on the surface (i.e., the upper surface and the lower surface) of the inner plate 1 1. The add-in material 13 that has a higher thermal conductivity than the material (nitrile rubber) of the coating layer 12 is added into the coating layer 12. The add-in materia] 13 has a spherical shape, and the particle diameter d of the add-in material 13 is equal to or greater than the thickness t of the coating layer 12. That is, one end of the add-in material 13 protrudes from the surface of the coating layer 12, and the other end of the add-in material 13 is in contact with the surface of the inner plate 1 1.

[0027] With this structure, the heat dissipating ability of the gasket 1 is able to be improved without losing sealability, so the heat of the cylinder block 30 is able to be quickly transferred to the cylinder head 40 through the gasket 1.

[0028] Next, a second operational effect will be described. The add-in material 13 is made of graphite that is material having a lower hardness than the cylinder block 30 and the cylinder head 40 (both of which are made of aluminum alloy). This kind of structure makes it possible to inhibit gaps from being created as a result of the add-in material 13 being arranged between the upper surface 31 of the cylinder block 30 and the lower surface of the gasket 1, and between the lower surface 41 of the cylinder head 40 and the upper surface of the gasket 1. Also, because the hardness of the add-in material 13 is lower than the harnesses of the cylinder block 30, the cylinder head 40, and the inner plate 11 , neither the upper surface 31 of the cylinder block 30 nor the lower surface 41 of the cylinder head 40 will deform due to the add-in material 13. Accordingly, the seal between the gasket 1 and the cylinder block 30, and the gasket 1 and the cylinder head 40 is able to be well maintained.

[0029] Next, a third operational effect will be described. The add-in material 13 is added only at the adding portions lc of the gasket 1 that correspond to the areas between cylinder bores. In a multiple cylinder internal combustion engine, the temperature between cylinder bores, where there is a particular tendency for combustion heat to concentrate, tends to become high. Therefore, even though adding the add-in material to the entire surface of the gasket would enable the heat dissipating ability of the entire gasket to be increased, the areas in between the cylinder bores would still become higher in temperature than the other areas, and this temperature difference between these areas may not be able to be reduced.

[0030] Regarding this, in the example embodiment described above, the add-in material 13 is added only at the adding portions lc of the gasket 1 that correspond to the areas in between the cylinder bores, so the heat dissipating ability of these adding portions l c is increased, which makes it possible to suitably suppress an increase in temperature between cylinder bores. Also, the add-in material 13 is not added at portions other than the adding portions lc, so the temperature difference between the portions is also able to be appropriately reduced.

[0031] The gasket according to the invention is not limited to the structure illustrated by the example embodiment described above, but may also be embodied in various other suitably modified forms such as those described below, for example.

[0032] In the example embodiment described above, the cylinder block 30 and the cylinder head 40 are described as being made of aluminum alloy, but they may also be made of cast iron.

[0033] In the example embodiment described above, 15% by weight of the add-in material 13 with respect to the coating layer 12 is added. However, the addition ratio of the add-in material according to the invention is not limited to this ratio. The preferable addition ratio of the add-in material differs depending on the material of the coating layer (i.e., the seal membrane) and the material of the add-in material, so the addition ratio of the add-in material may be set appropriately taking into account the heat dissipating ability required of the gasket.

[0034] In the example embodiment described above, the gasket 1 in which the add-in material 13 is added only at the adding portions l c corresponding to the areas between cylinder bores, i.e., the gasket 1 in which the add-in material 13 is not added at portions other than the adding portions l c, is described. Instead, the add-in material may be added to the entire surface of the gasket, and the distribution of the add-in material may be set such that the concentration of the add-in material becomes lower farther away from the portions corresponding to the areas between the cylinder bores. With this kind of gasket, the concentration of the add-in material is lower at portions where the temperature of the gasket is lower, so the temperature difference between the portions of the gasket is able to be appropriately reduced. Also, if an increase in temperature between cylinder bores is not that much of an issue, the addition concentration of the add-in material may be set evenly over the entire surface of the gasket. In this case, the seal membrane and the add-in material are able to be easily formed on the gasket.

(0035] In the example embodiment described above, the gasket 1 is formed by the inner plate 1 1 and the coating layer 12 that is formed on both surfaces (i.e., the upper surface and the lower surface) of the inner plate 1 1. However, the gasket according to the invention is not limited to the gasket 1 being used in only a single layer in this way. That is, a plurality of these kinds of gaskets may also be stacked together and used. Also, in this case, a plate member having high thermal conductivity (such as a metal plate of stainless steel, for example) may be interposed between the gaskets.

(0036] The gasket according to the invention is not limited to a cylinder head gasket of a gasoline engine. In addition, the invention may also be applied to a cylinder head gasket of a diesel engine, for example. Also, the gasket according to the invention is not limited to a cylinder head gasket. That is, the invention may be applied to any appropriate gasket as long as the gasket is interposed between a pair of flanges.

[0037] In the example embodiment described above, the coating layer 12 is made of nitrile rubber. However, the material of the seal membrane according to the invention is not limited to this. That is, resin material including other rubber material may also be employed.

[0038] In the example embodiment described above, the add-in material is made of graphite, but the material of the add-in material is not limited to this. That is, the material of the add-in material need only have a higher thermal conductivity than the material of the seal membrane. For example, if the seal membrane is made' of resin material, the material of the add-in material may be an allotrope of carbon (such as diamond), metallic material (such as copper or aluminum), or ceramic material (such as alumina), or the like.

[0039] The shape of the add-in material is not limited to being spherical (granular) as described in the foregoing example embodiment. For example, if the material is graphite, flaky graphite may be also employed. In this case as well, one end of the add-in material only needs to be protruded from the surface of the seal membrane, and the other end of the add-in material only needs to be in contact with the surface of the core plate.

[0040J In the example embodiment described above, the add-in material 13 is in contact with the surface of the inner plate 1 1 when the gasket 1 is formed (FIG 3A). However, the structure of the invention is not limited to this. That is, even if the add-in material 13 is not in contact with the surface of the inner piate 1 1 in the state shown in FIG 3 A, it is sufficient that the add-in material 13 be in contact with the surface of the inner plate 1 1 when the gasket 1 is in a state assembled between the upper surface 3 1 of the cylinder block 30 and the lower surface 41 of the cylinder head 40.

Claims

CLAIMS:

1. A gasket to be interposed between a pair of flanges arranged opposing one another, characterized by comprising:

a core plate; and

a seal membrane formed on a surface of the core plate,

wherein add-in material having a higher thermal conductivity than material of the seal membrane is added into the seal membrane; and

one end of the add-in material protrudes from a surface of the seal membrane, and the other end of the add-in material is in contact with the surface of the core plate.

2. The gasket according to claim 1 , wherein the add-in material is generally granular, and a particle diameter of the add-in material is equal to or greater than a thickness of the seal membrane.

3. The gasket according to claim 1 or 2, wherein the add-in material is made of material having a lower hardness than the pair of flanges and the core plate, and is able to deform when the gasket is in a state assembled between the pair of flanges.

4. The gasket according to claim 3, wherein the add-in material is graphite.

5. The gasket according to any one of claims 1 to 4, wherein the pair of flanges is a cylinder head and a cylinder block of an internal combustion engine.

6. The gasket according to claim 5, wherein the internal combustion engine is a multiple cylinder internal combustion engine having a plurality of cylinders; and the add-in material is added only at a portion of the gasket that corresponds to an area in between cylinder bores.

7. The gasket according to any one of claims 1 to 6, wherein the seal membrane to which the add-in material is added is formed on both surfaces of the core plate.

8. A gasket to be interposed between a pair of flanges arranged opposing one another, characterized by comprising:

a core plate; and

a seal membrane formed on a surface of the core plate,

the add-in material is generally granular, and a particle diameter of the add-in material is equal to or greater than a thickness of the seal membrane.

9. The gasket according to claim 8, wherein when the gasket is in a state assembled between the pair of flanges, one end of the add-in material contacts one of the pair of flanges and the other end of the add-in material contacts the surface of the core plate.

10. The gasket according to claim 9, wherein the add-in material is made of material having a lower hardness than the pair of flanges and the core plate, and is able to deform when the gasket is in a state assembled between the pair of flanges.

11. The gasket according to claim 10, wherein the add-in material is graphite.

12. The gasket according to any one of claims 8 to 1 1 , wherein the pair of flanges is a cylinder head and a cylinder block of an internal combustion engine.

13. The gasket according to claim 12, wherein the internal combustion engine is a multiple cylinder internal combustion engine having a plurality of cylinders; and the add-in material is added only at a portion of the gasket that corresponds to an area in between cylinder bores.

14. The gasket according to any one of claims 8 to 13, wherein the seal membrane to which the add-in material is added is formed on both surfaces of the core plate.