JP2009275808A - Metal gasket - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal gasket partially exposed to high temperature combustion gas with both an initial affinity property in a sealing surface and a corrosion resistance against the high temperature combustion gas. <P>SOLUTION: The metal gasket 20 consists of a metal base material 21 and a coating layer 22 formed on a surface of the metal base material 21. The coating layer 22 is provided with a corrosion resistance layer 221 containing corrosion resistant metal as a main material which is unlikely to be corroded by the combustion gas compared to the metal base material 21 and a sealing layer 222 containing a soft metal as a main material which is softer than the corrosion resistant metal. The corrosion resistant layer 221 is formed at a portion (a gas contact surface 20a) of the metal base material 21 where the metal gasket 20 is exposed to the combustion gas. The sealing layer 222 is formed at sealing portions (sealing surfaces 20b, 20c) of the metal base material 21 where the metal gasket 20 and a counter part member contact. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a metal gasket, and more particularly to a metal gasket that is partially exposed to combustion gas of an internal combustion engine and that is interposed between counterpart members to prevent the combustion gas from leaking from between the counterpart members.

  A metal gasket for preventing the combustion gas from leaking is interposed between the members that can come into contact with the combustion gas in the combustion chamber of the internal combustion engine.

  For example, in a direct injection engine, a combustion chamber is defined and formed by a cylinder block, a piston top surface that is reciprocally disposed in the cylinder block, and a cylinder head that faces the piston top surface. . The cylinder head is provided with a fuel injection nozzle for injecting fuel toward the recess formed in the piston top surface. For this reason, an annular metal gasket is interposed between the cylinder head and the fuel injection nozzle in order to prevent the combustion gas from leaking from between the cylinder head and the fuel injection nozzle to the cam chamber side or the like. In this metal gasket, the inner peripheral surface of the gasket is exposed to combustion gas, and both end surfaces (both end surfaces in the axial direction) of the gasket serve as seal surfaces for the fuel injection nozzle and the cylinder head.

  Conventionally, a copper gasket made of copper or a copper alloy is known as such a metal gasket. However, the conventional copper gasket has a problem that the inner peripheral surface of the gasket exposed to the high-temperature combustion gas is damaged by corrosion, thereby reducing the sealing surface of the gasket and deteriorating the sealing performance. The cause of corrosion on the inner peripheral surface of the gasket is not clear, but copper oxide or copper sulfide is formed on the inner peripheral surface of the gasket in contact with high-temperature combustion gas by oxidation or sulfidization, and brittle copper oxide or copper sulfide is not formed. It is considered that the inner peripheral surface of the gasket is damaged due to the dropping and the repeated oxidation or sulfurization and the copper oxide or copper sulfide dropping.

  A tin-plated copper gasket in which a tin-plated layer is formed on the entire surface of the copper gasket is also known (see, for example, Patent Document 1). The tin-plated copper gasket described in Patent Document 1 is used in a combustion chamber of an alcohol engine. Moreover, in the tin plating copper gasket described in patent document 1, in order to prevent the corrosion by alcohol, the tin plating layer is formed in the whole surface of a gasket.

  In the tin-plated copper gasket described in Patent Document 1, corrosion of the gasket inner peripheral surface can be prevented by the tin-plated layer in the initial stage. However, when exposed to a high-temperature combustion gas for a long period of time, tin in the tin plating layer diffuses to the copper substrate side and the tin plating layer is damaged, and eventually the copper substrate is corroded.

  Therefore, in order to prevent corrosion of the metal gasket due to contact with the combustion gas, a means for applying corrosion-resistant nickel plating or chromium plating to the gasket surface can be considered. However, when nickel plating or chrome plating is applied to the gasket surface, the nickel plating or chrome plating is hard, so that there is a problem that the initial conformability of the seal surface required for the gasket cannot be obtained.

It is a laminated type gasket composed of an iron plate and stainless steel seal plates disposed on both sides of the iron plate, and is exposed to combustion gas in the cylinder head gasket interposed between the cylinder head and the cylinder block. A laminated cylinder head gasket is also known in which the edge of an iron plate is subjected to corrosion-resistant chrome plating (see, for example, Patent Document 2).
Japanese Utility Model Publication No. 62-162367 Japanese Utility Model Publication No. 63-59262

  The present invention has been made in view of the above circumstances, and solves the problem of achieving both the initial conformability on the sealing surface and the corrosion resistance against the high-temperature combustion gas in the metal gasket partially exposed to the high-temperature combustion gas. It is a technical issue to be solved.

  (1) The metal gasket of the present invention that solves the above problems comprises a metal substrate and a coating layer formed on the surface of the metal substrate, and is a counterpart member that is partially exposed to the combustion gas of the internal combustion engine. A metal gasket for preventing the combustion gas from leaking between the mating members interposed therebetween, wherein the coating layer is mainly made of a corrosion-resistant metal that is less corroded by the combustion gas than the metal base material. A corrosion-resistant layer formed on a portion of the metal base material where the metal gasket is exposed to the combustion gas; a soft metal softer than the corrosion-resistant metal as a main material; and the metal gasket of the metal base material. And a seal layer that is formed at a seal portion that comes into contact with the counterpart member and that comes into contact with the counterpart member.

  In the metal gasket of the present invention, a corrosion-resistant layer mainly composed of a corrosion-resistant metal that is less likely to be corroded by the combustion gas than the metal substrate is formed at a portion exposed to the combustion gas. For this reason, corrosion of the metal substrate due to high-temperature combustion gas can be effectively prevented by the corrosion-resistant layer. On the other hand, a seal layer mainly composed of a soft metal is formed at the seal portion, and this seal layer comes into contact with the mating member. For this reason, initial conformability can be easily ensured between the soft seal layer and the mating member.

  The metal gasket of the present invention preferably has at least one of the structures shown in the following (2) to (4). The metal gasket of the present invention may have each of the configurations shown in the following items (2) to (4), or the configurations shown in the following items (2) to (4). You may have in combination of two or more.

  (2) It is preferable that the said corrosion-resistant metal is nickel or chromium.

  (3) The soft metal is preferably tin.

  (4) The metal substrate is preferably copper or a copper alloy.

  Therefore, according to the metal gasket of the present invention, it is possible to achieve both initial conformability on the seal surface and corrosion resistance against high-temperature combustion gas.

  Hereinafter, embodiments of the metal gasket of the present invention will be described in detail. The embodiment to be described is only one embodiment, and the metal gasket of the present invention is not limited to the following embodiment. The metal gasket of the present invention can be implemented in various forms with modifications and improvements that can be made by those skilled in the art without departing from the scope of the present invention.

  In the present embodiment, the metal gasket of the present invention is applied to a gasket interposed between a fuel injection nozzle and a cylinder head in a direct injection engine.

  As shown in FIG. 1, in a direct injection engine, a cylinder block 10 having a bore 10a, a piston 11 reciprocally disposed in the bore 10a of the cylinder block 10, and a piston top surface of the piston 11 are provided. A combustion chamber 13 is defined by the opposing cylinder head 12. A recess 111 for securing the volume of the combustion chamber 13 between the piston 11 and the cylinder head 12 is formed on the piston top surface.

  The cylinder head 12 is provided with a fuel injection nozzle 14 for injecting fuel toward a recess 111 formed on the top surface of the piston. Specifically, the cylinder head 12 is provided with a hollow portion 12 a at a position facing the substantially central portion of the concave portion 111 of the piston 11, and an insertion hole 12 b that communicates the hollow portion 12 a and the combustion chamber 13. Yes. The nozzle body 141 of the fuel injection nozzle 14 is disposed in the cavity 12a, and the nozzle tip 142 of the fuel injection nozzle 14 is inserted through the insertion hole 12b.

  The metal gasket 20 of this embodiment is disposed between the annular belt-shaped bottom surface of the cavity 12 a of the cylinder head 12 and the lower end surface of the nozzle body 141 of the fuel injection nozzle 14. The metal gasket 20 prevents the combustion gas in the combustion chamber 13 from leaking between the mating members, that is, between the cylinder head 12 and the fuel injection nozzle 14 to the cam chamber side or the like.

  In this metal gasket 20, the inner peripheral surface of the metal gasket 20 is a gas contact surface 20a exposed to the combustion gas, and the upper and lower end surfaces (both end surfaces in the axial direction) of the metal gasket 20 are the cylinder head 12 as a mating member and The seal surfaces 20b and 20c are in contact with the fuel injection nozzle 14. The upper end surface of the metal gasket 20 serves as a nozzle-side seal surface 20b that contacts the fuel injection nozzle 14, and the lower end surface of the metal gasket 20 serves as a cylinder head-side seal surface 20c that contacts the cylinder head 12.

  As shown in FIG. 2, the metal gasket 20 includes an annular metal base 21 and a coating layer 22 formed on the surface of the metal base 21.

  The type of metal material constituting the metal substrate 21 is not particularly limited as long as it has the elasticity, flexibility, heat resistance, etc. required as a gasket. For example, copper, a copper alloy, aluminum, or an aluminum alloy can be employed as a suitable metal material for the metal substrate 21. In the present embodiment, copper (pure copper) is used as the metal material of the metal substrate 21.

  The covering layer 22 includes a corrosion resistant layer 221 and a seal layer 222. The corrosion resistant layer 221 is formed on a portion of the metal base 21 where the metal gasket 20 is exposed to the combustion gas, that is, on the gas contact surface 20 a on the inner peripheral surface of the metal gasket 20. The seal layer 222 is formed on the seal portion where the metal gasket 20 and the fuel injection nozzle 14 and the cylinder head 12 are in contact with each other, that is, the seal surfaces 20b and 20c on the nozzle side and the cylinder head side of the metal gasket 20, respectively. Has been.

  The corrosion-resistant layer 221 as the coating layer 22 is mainly made of a hard corrosion-resistant metal that is harder than the metal substrate 21 and harder to be corroded by the combustion gas than the metal substrate 21. The type of the corrosion-resistant metal constituting the corrosion-resistant layer 221 is not particularly limited as long as it is less corroded by the combustion gas than the metal substrate 21. For example, nickel or a nickel alloy, or chromium or a chromium alloy can be employed as a suitable corrosion resistant metal for the corrosion resistant layer 221. In the present embodiment, nickel is used as the corrosion resistant metal of the corrosion resistant layer 221.

  The seal layer 222 as the coating layer 22 is mainly composed of a soft metal that is softer than the corrosion-resistant metal that forms the corrosion-resistant layer 221. The kind of the soft metal constituting the seal layer 222 is not particularly limited as long as it is softer than the corrosion-resistant metal constituting the corrosion-resistant layer 221, but it is preferable that the metal is not easily corroded by the combustion gas. It is preferably softer than or equivalent to the base material 21. For example, tin or a tin alloy can be employed as a suitable soft metal for the seal layer 222. In the present embodiment, tin is used as the soft metal for the seal layer 222.

  The hardness of the soft metal constituting the seal layer 222 is Vickers hardness (JIS Z 2244), and is preferably about HV 10-40. In addition, the hardness of the corrosion-resistant metal which comprises the corrosion-resistant layer 221 is Vickers hardness (JIS Z 2244), and can be about HV200-700.

  The thicknesses of the corrosion-resistant layer 221 and the seal layer 222 may be set as appropriate so that the respective functions can be effectively exhibited, and can be about 5 to 20 μm, respectively.

  Here, only the sealing layer 222 mainly composed of a soft metal is formed as the coating layer 22 on the sealing surface 20 b of the metal gasket 20. Similarly, only the sealing layer 222 mainly composed of a soft metal is formed as the coating layer 22 on the sealing surface 20 c of the metal gasket 20. That is, the seal surface 20b, 20c of the metal gasket 20 is not formed with the corrosion resistant layer 221 mainly composed of a corrosion resistant metal as the covering layer 22.

  In addition, the gas contact surface 20a of the metal gasket 20 may be formed with a layer mainly composed of a soft metal together with the corrosion resistant layer 221 mainly composed of a corrosion resistant metal as the covering layer 22. When both the corrosion-resistant layer 221 mainly made of corrosion-resistant metal and the layer mainly made of soft metal are formed on the gas contact surface 20a of the metal gasket 20, either of them may be the outermost layer.

  The method for forming the corrosion-resistant layer 221 and the seal layer 222 on the surface of the metal substrate 21 is not particularly limited, but preferably a plating process can be employed.

  Further, when the corrosion resistant layer 221 and the seal layer 222 are formed on the surface of the metal base material 21 by plating, a portion or a part of the surface of the metal base material 21 that does not need to form the coating layer 22 is formed. What is necessary is just to perform a plating process while masking the part which should not be.

  When the corrosion resistant layer 221 and the seal layer 222 in the metal gasket 20 of the present embodiment shown in FIG. 2 are formed by plating, for example, the following may be performed. First, the surface of the metal substrate 21 other than the inner peripheral surface of the metal substrate 21 corresponding to the gas contact surface 20a of the metal gasket 20 is covered with a predetermined mask member for masking. Then, the metal base material 21 whose predetermined portion is masked with a mask member is subjected to corrosion-resistant metal plating, and a corrosion-resistant layer having a predetermined thickness is formed on the inner peripheral surface of the metal base material 21 corresponding to the gas contact surface 20a of the metal gasket 20. 221 is formed. Thereafter, the mask members on the upper and lower end surfaces of the metal base 21 corresponding to the sealing surfaces 20b and 20c of the metal gasket 20 are removed, and the corrosion-resistant layer 221 is covered with a predetermined mask member for masking. Then, soft metal plating is performed on the metal base material 21 in which the predetermined portion is masked with a mask member, and seal layers 222 are respectively provided on both upper and lower end surfaces of the metal base material 21 corresponding to the seal surfaces 20b and 20c of the metal gasket 20. Form. Finally, by removing all the mask members, the corrosion-resistant layer 221 and the seal layer 222 in the metal gasket 20 of the present embodiment shown in FIG. 2 can be formed.

  In order to reduce the manufacturing cost by simplifying the masking process, the coating layer 22 is formed on the gas contact surface 20 a of the metal gasket 20, that is, on the inner peripheral surface of the metal substrate 21, as described in Example 1 described later. A layer mainly composed of a soft metal may be formed together with the corrosion resistant layer 221 composed mainly of a corrosion resistant metal. For the same reason, as described in Examples 1 and 2 described later, a layer mainly composed of a corrosion-resistant metal and a layer mainly composed of a soft metal may be formed on the outer peripheral surface of the metal substrate 21. .

  In the metal gasket 20 of the present embodiment having the above-described configuration, a corrosion-resistant layer 221 mainly composed of a hard corrosion-resistant metal is formed on a portion exposed to the combustion gas, that is, the gas contact surface 20a. For this reason, corrosion of the metal substrate 21 due to high-temperature combustion gas can be effectively prevented by the corrosion-resistant layer 221. On the other hand, seal layers 222 and 222 made mainly of soft metal are formed on the seal portions, that is, the seal surfaces 20b and 20c, respectively. The seal layers 222 and 222 are connected to the fuel injection nozzle 14 and the cylinder head 12, respectively. Abut. For this reason, initial conformability can be easily ensured between the soft seal layer 222 and the fuel injection nozzle 14 and the cylinder head 12.

  Therefore, according to the metal gasket 20 of the present embodiment, it is possible to achieve both initial conformability on the seal surfaces 20b and 20c and corrosion resistance against high-temperature combustion gas on the gas contact surface 20a.

Example 1
As shown in FIGS. 3A to 3D, the metal base material 21 was subjected to predetermined masking treatment and plating treatment, and the metal gasket 20 of Example 1 was manufactured.

  First, an annular metal substrate 21 made of pure copper was manufactured by cold forging and cutting. The size of the metal substrate 21 was set to an outer diameter: 18 mm, an inner diameter: 8 mm, and a thickness (a height in the axial direction): 4 mm.

  The upper end surface 21b and the lower end surface 21c of the metal base 21 were covered and masked with a mask member 30 made of a fluorine-based resin (see FIG. 3A). This masking was performed by applying a fluorine-based paint.

  Nickel plating was performed on the metal base material 21 whose upper end surface 21b and lower end surface 21c were masked under the following conditions. As a result, a corrosion-resistant layer 221 made of a nickel plating layer was formed on the inner peripheral surface 21a of the metal substrate 21 (see FIG. 3B). A nickel plating layer 223 was also formed on the outer peripheral surface 21d of the metal substrate 21. The thickness of the corrosion-resistant layer 221 and the nickel plating layer 223 was 5 μm.

Kind of plating bath: Watt bath mainly composed of nickel sulfate (300 g / L), nickel hydrochloride (50 g / L) and boric acid (40 g / L) pH of plating bath: 4.5
Plating bath temperature: 60 ° C
Current density: 6 A / dm ²
Next, the mask member 30 was peeled off from the upper end surface 21b and the lower end surface 21c of the metal base material 21 (see FIG. 3C).

  And it tin-plated on the conditions shown below. As a result, seal layers 222 and 222 made of a tin plating layer were formed on the upper end surface 21b and the lower end surface 21c of the metal substrate 21, respectively (see FIG. 3D). In addition, the tin plating layer 224 was also formed on the corrosion-resistant layer 221 formed on the inner peripheral surface 21a of the metal substrate 21 and the nickel plating layer 223 formed on the outer peripheral surface 21d of the metal substrate 21. The thickness of the seal layer 222 and the tin plating layer 224 was 10 μm.

Type of plating bath: alkaline bath mainly composed of potassium stannate (120 g / L), potassium hydroxide (15 g / L) and acetic acid (5 g / L) Temperature of plating bath: 70 ° C.
Current density: 4 A / dm ²
Thus, the corrosion-resistant layer 221 and the tin-plated layer 224 made of a nickel plating layer are formed on the gas contact surface 20a of the metal gasket 20, that is, the inner peripheral surface 21a of the metal base 21, and the metal gaskets 20 are sealed on the seal surfaces 20b and 20c. The metal gasket 20 in which the sealing layers 222 and 222 made of a tin plating layer were formed was manufactured.

  In the metal gasket 20 of Example 1, a corrosion-resistant layer 221 made of a nickel-plated layer having high corrosion resistance and a tin-plated layer 224 having higher corrosion resistance than copper are formed on the gas contact surface 20a. Further, seal layers 222 and 222 made of a tin plating layer having initial conformability equal to or higher than that of the copper constituting the metal base 21 are formed on the seal surfaces 20b and 20c. For this reason, according to the metal gasket 20 of Example 1, it is possible to achieve both the initial conformability on the seal surfaces 20b and 20c and the corrosion resistance against high-temperature combustion gas on the gas contact surface 20a.

  In the metal gasket 20, from the viewpoint of simplifying the masking process, the gas contact surface 20 a of the metal gasket 20, that is, the inner peripheral surface 21 a of the metal substrate 21, and the corrosion resistant layer 221 made of a nickel plating layer and tin While the plating layer 224 is formed and the nickel plating layer 223 and the tin plating layer 224 are also formed on the outer peripheral surface 21d of the metal base material 21, this is disadvantageous in terms of the function of the metal gasket 20. There is no.

(Example 2)
As shown in FIGS. 4A to 4F, the metal base material 21 was subjected to predetermined masking treatment and plating treatment, and the metal gasket 20 of Example 2 was manufactured.

  First, in the same manner as in Example 1, an annular metal substrate 21 made of pure copper was manufactured. And the inner peripheral surface 21a of the metal base material 21 was covered with the mask member 31 and masked in the same manner as in Example 1 (see FIG. 4A).

  The metal substrate 21 with the inner peripheral surface 21a masked was subjected to tin plating under the same conditions as in Example 1. Thus, seal layers 222 and 222 made of a tin plating layer were formed on the upper end surface 21b and the lower end surface 21c of the metal substrate 21, respectively (see FIG. 4B). A tin plating layer 224 was also formed on the outer peripheral surface 21d of the metal base material 21. The thickness of the seal layer 222 and the tin plating layer 224 was 10 μm.

  Next, after peeling the mask member 31 from the inner peripheral surface 21a of the metal base material 21 (see FIG. 4C), the sealing layer 222 formed on the upper end surface 21b of the metal base material 21, and the metal base material The sealing layer 222 formed on the lower end surface 21c of 21 was covered with the mask member 32 and masked in the same manner as in Example 1 (see FIG. 4D).

  Then, nickel plating was performed on the metal base material 21 on which the seal layers 222 and 222 and the tin plating layer 224 were formed and the upper end surface 21b and the lower end surface 21c were masked under the same conditions as in Example 1. . Thus, a corrosion-resistant layer 221 made of a nickel plating layer was formed on the inner peripheral surface 21a of the metal base 21 (see FIG. 4 (e)). A nickel plating layer 223 was also formed on the tin plating layer 224 formed on the outer peripheral surface 21d of the metal substrate 21. The thickness of the corrosion resistant layer 221 and the nickel plating layer 223 was 10 μm.

  Finally, the mask portion 32 was peeled off from the seal layers 222 and 222 (see FIG. 4F).

  Thus, the corrosion-resistant layer 221 made of a nickel plating layer is formed on the gas contact surface 20a of the metal gasket 20, that is, the inner peripheral surface 21a of the metal substrate 21, and the tin plating layers are made on the sealing surfaces 20b and 20c of the metal gasket. The metal gasket 20 in which the sealing layers 222 and 222 were formed was manufactured.

  In the metal gasket 20 of Example 2, a corrosion-resistant layer 221 made of a nickel plating layer having high corrosion resistance is formed on the gas contact surface 20a. Further, seal layers 222 and 222 made of a tin plating layer having initial conformability equal to or higher than that of the copper constituting the metal base 21 are formed on the seal surfaces 20b and 20c. For this reason, according to the metal gasket 20 of Example 2, it becomes possible to make compatible the initial conformability in the sealing surfaces 20b and 20c, and the corrosion resistance with respect to the high temperature combustion gas in the gas contact surface 20a.

  In the metal gasket 20, a tin plating layer 224 and a nickel plating layer 223 are formed on the outer peripheral surface 21d of the metal base 21 from the viewpoint of simplifying the masking process. There is no penalty for the 20 functions.

It is sectional drawing which shows the usage pattern of the metal gasket of Embodiment 1 typically. It is sectional drawing which shows the structure of the metal gasket of Embodiment 1 typically. It is sectional drawing which illustrates typically the manufacturing process of the metal gasket of Example 1. FIG. It is sectional drawing which illustrates typically the manufacturing process of the metal gasket of Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 ... Metal gasket 20a ... Gas contact surface 20b, 20c ... Sealing surface 21 ... Metal base material 22 ... Coating layer 221 ... Corrosion-resistant layer 222 ... Sealing layer

Claims (4)

Composed of a metal base and a coating layer formed on the surface of the metal base, the combustion gas leaks from between the counterpart members while being partially exposed to the combustion gas of the internal combustion engine and interposed between the counterpart members A metal gasket that prevents
The coating layer is
Corrosion resistant layer formed mainly on a corrosion resistant metal that is less likely to be corroded by the combustion gas than the metal base, and the metal gasket of the metal base is exposed to the combustion gas;
The main layer is a soft metal that is softer than the corrosion-resistant metal, and a seal layer that is formed in a seal portion where the metal gasket and the mating member are in contact with each other and is in contact with the mating member;
A metal gasket characterized by comprising:   The metal gasket according to claim 1, wherein the corrosion-resistant metal is nickel or chromium.   The metal gasket according to claim 1 or 2, wherein the soft metal is tin.   The metal gasket according to any one of claims 1 to 3, wherein the metal substrate is copper or a copper alloy.

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