JPH04357372A - Composite type gasket - Google Patents

Abstract

PURPOSE:To improve sealing property, cushion property and mechanical strength of a gasket, prevent a mating member from being damaged and manufacture economically the gasket. CONSTITUTION:A composite type gasket is composed of a metal support 1 having a predetermined shape and sintered metal gasket bodies 2, 6 fixed to at least one side surface of the support 1 so as to surround a bore formed in the support and containing iron or iron group alloy as its main component.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite gasket, and more particularly to a composite gasket useful as a gasket interposed between an exhaust port of an internal combustion engine or its cylinder head and a cylinder block.

0002

[Prior Art] In recent years, in order to increase the output of internal combustion engines, make them smaller, save energy, and reduce particulate emissions, the compression ratio has been increased and the distance between the bore axes has been shortened.
Research and development is underway to reduce dead space, but
Accordingly, there is a demand for the development of highly reliable and durable gaskets. Therefore, as gaskets to replace the conventionally widely used steel vests, metal gaskets made of laminated thin metal plates and metal gaskets combined with reinforcing rings made of copper or iron alloys have been developed, and some of them have been put into practical use. In addition, JP-A-62-192504 proposes a metal infiltration type sintered metal gasket in which a thin layer of a low melting point metal is formed on the surface of the sintered metal gasket body.

0003

[Problems to be Solved by the Invention] However, even though the material costs for metal gaskets are low, the molds used to process them are expensive, resulting in high costs, and moreover, the springs tend to deteriorate over time. There was a problem that the sealing performance was lowered. For example, in the case of a head gasket made of stainless steel (for example, SUS304), the springiness rapidly decreases at a temperature exceeding about 350°C, and in the case of an exhaust gasket, at a temperature exceeding about 500°C. In addition, metal gaskets that use reinforcing rings made of copper-based alloys have stronger strength than normal metal gaskets, but if you change the material of the reinforcing rings to iron-based ones in order to handle higher temperatures and pressures, the reinforcement Due to the poor cushioning properties of the ring and its circular cross-sectional shape, the part of the gasket where the reinforcing ring is inserted comes into line contact with the cylinder head and cylinder block under strong pressure. There was a problem of damaging these. This damage to the cylinder head and cylinder block is particularly severe in engines whose cylinder heads and the like are made of aluminum alloy. Moreover, since a width is required to include the reinforcing ring, there is also a problem in that the distance between the cylinder axes becomes longer in a cylinder gasket provided with the reinforcing ring.

On the other hand, infiltration type sintered metal gaskets have excellent cushioning properties, do not damage mating parts, and have good thermal conductivity just like metal gaskets, so they can be used to reduce the gap between the cylinder head and cylinder block. Although it has the advantage of reducing temperature differences, it has been extremely difficult to manufacture cylinder head gaskets for multi-cylinder engines. For example, when manufacturing a head gasket for a four-cylinder engine, a sintered plate with a large surface area of 250 x 400 mm or more is required, but even when compacted at a pressure of 1 t/cm2 per unit area, the 100
A 0-ton hydraulic press is required, and a very large furnace for sintering it is also required, requiring a large investment in equipment. In addition, such large products undergo large shrinkage and distortion during sintering, and therefore tend to crack easily, making it difficult to mass-produce them. In addition, it is difficult to handle in each process from molding to sintering, and the cost of the gasket is extremely high.In addition, sufficient force is not applied to the contact surface with the gasket due to deformation when the engine block and head block are tightened. It has become clear that it is difficult to obtain sufficient sealing performance.

[0005] Accordingly, an object of the present invention is to solve the above-mentioned problems and to improve the advantages of a sintered metal gasket, particularly its sealing performance and manufacturability without sacrificing its cushioning properties, and to enable it to be manufactured at low cost. It's about doing.

[0006]

[Means for Solving the Problems] As a means for solving the above-mentioned problems, the present invention forms a metal support body in a predetermined shape corresponding to the joining surfaces of members to be joined, and at the same time forms a The gasket body is formed only from a sintered metal whose main component is iron or an iron-based alloy, and a metal support is provided so that the gasket body can be placed at a predetermined position on the joining surface of the parts to be joined. It is designed to be placed on the body.

That is, the composite head gasket according to the present invention includes a metal support having a predetermined shape, a metal support fixed to at least one surface of the support so as to surround a bore formed in the support, and a metal support having a predetermined shape. Alternatively, it is composed of a sintered metal gasket body whose main component is an iron-based alloy.

[0008] The support usually has a thickness of 0.1 to 0.5 mm.
It is formed by punching a metal plate with a thickness of However, it is not necessarily limited to these.

[0009] For example, in the case of a head gasket, the gasket body needs to be interposed only in the portion that surrounds at least one of the bores of the contact surfaces between the cylinder block and the cylinder head, so it usually has a shape that corresponds to the bore. (For example, in the case of cylinder bores and bolt bores, it is formed in a ring shape), but if it is small, it may be formed in the form of two or more connected. In this case, in addition to connecting two adjacent cylinder bore gasket bodies,
The cylinder bore and the surrounding bolt bores may be connected. The sintered metal that forms this gasket body is mainly composed of iron or iron-based alloy, but its sintered density varies depending on the material and forming method (tapping method, pressing method, etc.). Although it cannot be determined unambiguously because it varies, usually 4
0 to 95% is preferred. For example, in the case of stainless steel,
It is preferable to process a plate-shaped sintered body having a sintered density in the range of 40 to 70%.

[0010] If sealing with a grommet is sufficient, such as in the case of an exhaust gasket, this gasket body can be put to practical use by adding natural rubber, silicone rubber, etc. during molding and subjecting it to graphitization treatment. However, if higher sealing performance is required, for example, in the case of a head gasket whose required performance is relatively low temperature and low pressure, the gasket body may be surface coated or impregnated with rubber or the like. Further, in the case of a head gasket whose required performance is high temperature and high pressure, infiltration with a low melting point metal may be performed locally or throughout the gasket. In this case, the low melting point metal depends on the material of the cylinder head and cylinder block, but
Typically, copper, lead, zinc, tin, aluminum, and alloys thereof, which have lower melting points than the sintered metal forming the gasket body, are preferred.

The gasket body may be attached to the support by bending an annular bent part provided at the edge of the bore of the support like a grommet, or by brazing, Any means such as grommets can be used. In the case of brazing, it is also possible to perform infiltration and brazing at the same time using an infiltrant in the gasket body. Also,
In the case of a grommet, it is preferable that the thickness of the gasket body be reduced by the thickness of the grommet at the portion where the bent portion of the grommet contacts the gasket body. Any known material can be used as the material for this grommet, but
When aiming at high output, it is preferable to use iron or an iron-based alloy (for example, stainless steel).

[0012] Furthermore, when a gasket body that surrounds a cylinder bore, bolt bore, etc. is attached to a support body using a grommet or the like, a ring-shaped recess is formed on the surface of the gasket body in which the bent part of the grommet is accommodated. The low melting point metal may be infiltrated only in the area surrounding the infiltrated area, and a second metal having a lower melting point than the metal infiltrated into the infiltrated area may be infiltrated in other areas other than the infiltrated area. Alternatively, the metal may be infiltrated. In this way, it is possible to improve the thermal conductivity of the gasket body, and at the same time bring its coefficient of thermal expansion close to that of the material of the cylinder head, thereby reducing stress strain. In this case, it is preferable to infiltrate the bottom of the recess or the area surrounding the bottom of the recess with copper, and infiltrate other areas with lead, zinc, tin, aluminum, or alloys thereof. be.

Furthermore, among the bores formed in the support body, the bores through which liquid flows, such as cooling water bores and lubricating oil bores, are fitted with soft grommets made of copper or copper alloy instead of being fitted with gasket bodies. It is preferable to fit a heat-resistant sealing member made of silicone rubber or other heat-resistant elastic material.

[0014]

[Operation] By constructing a gasket body made of sintered metal and a metal support that supports it in a predetermined position, it is possible to manufacture large gaskets without sacrificing the excellent properties of sintered metal gaskets. When this composite gasket is interposed between the cylinder block and cylinder head, only the gasket body comes into contact with them, reducing the contact area, so sufficient sealing performance is ensured even with a relatively low tightening force. Cushioning properties are ensured,
Contributes to preventing damage to the mating member. Furthermore, by making the gasket body into a ring shape, glasses shape, etc., its outer diameter is slightly larger than the cylinder bore, so there is no need to manufacture a large-area sintered body.
Therefore, mass production is possible.

[0015] Furthermore, the grommet fitted into the bore forming the cylinder bore, bolt bore, etc. of the gasket further improves the sealing performance and strength of the gasket, such as airtightness and watertightness against high-temperature and high-pressure gas, and forms a liquid flow path. Grommets or heat-resistant seals fitted into other bores improve watertightness.

The present invention will now be described in detail with reference to the accompanying drawings.

[0017]

[Example] Fig. 1 shows an example in which the present invention is applied to a cylinder head gasket. Sintered metal gasket body 2
As shown in FIG. 2, each gasket body 2 has a recess 2a formed along its upper inner edge, a central half of which is infiltrated with copper, and this infiltrated portion 2b. an annular projection 4 formed along the cylinder bore 3 of the support 1;
It is fixed to the support body 1 by fitting it in, bending its free end side (4a) like a grommet, and caulking it. The depth and width of the recess 2a are determined in accordance with the thickness of the annular projection 4 that is fitted into it and bent, and the length of the bent portion 4a.

The support body 1 has a plurality of bolt bores 5, and a small diameter ring-shaped gasket body 6 is attached to surround each bolt bore 5. Like the gasket body 2, this gasket body 6 also has a recess 6a formed on the inner edge side and an infiltrated portion 6b infiltrated with copper.

On the other hand, the fluid passage bore, for example, the cooling water bore 7, has a trapezoidal protrusion 8 whose height is lower than the wall thickness of the ring-shaped gasket bodies 2 and 6, as shown in FIG. A seal ring 9 made of silicone rubber is formed on the support body 1.
It is constructed by fitting.

The head gasket having the above structure according to the present invention can be manufactured, for example, as follows. First, iron powder or iron-based alloy powder is press-molded to form a ring-shaped green compact, and this is heated in an appropriate atmosphere at a temperature of 100 to 1
Fire at 300°C. For example, stainless steel powder (SU
When making a ring-shaped gasket body with an inner diameter of 60 mm, an outer diameter of 80 mm, and a thickness of 0.6 mm using S) as the material, 50
A compact with a density of ~70% has a surface pressure of 1 t/cm2 to 3 t/c
m2, so a hydraulic press of 31 to 93 tons can be used, and for powders with a density of 60%, a surface pressure of approximately 1 t/cm2 is sufficient, although this varies depending on the type of powder, so 31 tons can be used.
It is molded at a press pressure of 1,200°C and fired at 1200°C in a high vacuum.

[0021] Next, on one side surface of this fired gasket body, a width of 3 mm was formed by coining along the inner edge.
An annular recess with a depth of 0.2 mm is formed, and an inner diameter of 60 mm is formed in it.
After placing a copper ring having a diameter of 63 mm, an outer diameter of 63 mm, and a thickness of 0.2 mm, the ring-shaped gasket body 2 is obtained by heating and infiltrating the ring at 1200° C. in a high vacuum.

Next, separately, a 0.2 mm thick stainless steel plate is punched into a shape corresponding to the shape of the cylinder head and drawn to form the support 1.
The gasket body 2 may be fitted into the annular projection 4 (see FIG. 3), the annular projection 4 may be bent and caulked as shown in FIG. 2, and then flat pressed using a flat pressing press to finish. In addition, metals with a lower melting point than copper are used in other parts of the gasket body.
For example, if it is necessary to infiltrate the gasket with zinc, this can be done before attaching the gasket body to the support.

[0023] The above-mentioned calcination and firing can be carried out by any conventionally known method, and the atmosphere is a neutral atmosphere containing argon gas, nitrogen gas, etc., or hydrogen gas, ammonia decomposition gas, natural gas, etc. A high vacuum is used, as well as a reducing atmosphere containing the like. In addition, in the case of stainless steel, it is suitable to carry out in a high vacuum or a high purity hydrogen gas atmosphere. The calcination temperature and firing temperature vary depending on the material forming the sintered body, but in the case of iron, calcination is usually performed at 400°C or higher and sintering is performed at 1000 to 1300°C.

FIG. 4 shows another embodiment of the invention, in which cylinder bores 3 are formed on both sides of the support 1 made of iron or stainless steel.
A ring-shaped gasket body 2A made of sintered metal coaxially with the
, 2B are arranged, and infiltration and brazing with copper are performed at the same time, and the other configuration is the same as that in FIG. 1. In this case, it is preferable that the contact surface of the gasket support 1 with the gasket body be made uneven by sandblasting or other means, or that many minute holes be formed.

In the above embodiment, the upper end surface of the gasket body is formed flat, but in order to improve the sealing performance, the surface of the gasket body 2 has a semicircular, rectangular, or trapezoidal shape as shown in FIG. Protrusions or grooves may be formed in the protrusions.

FIG. 6 shows another embodiment of the present invention, in which a metal ring 1 having a corresponding shape is provided on the upper end surface of the gasket body 2, that is, on the surface opposite to the surface in contact with the metal support 1.
0, and the ring 10 is integrated with the gasket body 2 by caulking with the annular protrusion 4 of the support 1, and the other structure is the same as that of the embodiment shown in FIGS. 1 and 2.

FIG. 7 shows a further embodiment of the present invention, in which a support body 1 is provided with an annular projection having a shape corresponding to the shape of the cylinder head and surrounding a bore corresponding to the cylinder bore.
A gasket body 2 made of sintered metal is placed on top, and a metal protection plate 11 having a shape corresponding to the shape of the cylinder head and having no annular protrusion surrounding the cylinder bore is placed on top of the gasket body 2, and then a supporting plate is placed. The gasket body 1 and the protection plate 11 are caulked and integrated by an annular projection 4 of the body 1. Note that the protective plate may be formed of the same material as the support or a different material.

In the embodiments shown in FIGS. 6 and 7, the gasket body is surrounded by a metal support and a metal ring or a metal protection plate, so that the gasket body is not attached to the joint surface of the cylinder head, cylinder block, etc. There is no direct contact, and therefore, even if the gasket body is made of an inexpensive material, the heat resistance of the gasket can be improved. For example, if the support is made of precipitation hardening stainless steel such as SUS631, the gasket body can be made of SUS631.
Even if it is made of austenitic material such as 304, the
A gasket that can withstand use at temperatures ranging from 00 to 800°C can be obtained.

In the above embodiments, the present invention was applied to a head gasket, but it goes without saying that the present invention is not limited to this, and can be applied to exhaust gaskets and other gaskets.

[0030]

Effects of the Invention As explained above, the present invention comprises a gasket consisting of a gasket body and a metal gasket support, and only the gasket body is made of sintered metal. It can be manufactured with lower press pressure than manufactured gaskets, and can prevent cracks from occurring during heat treatment. At the same time, the amount of raw material required can be reduced, and it has excellent cushioning properties, sealing properties, durability, and heat resistance. Gaskets with excellent quality can be manufactured at low cost. Moreover, since the cushioning property is good, damage to the mating member can be prevented.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view showing an embodiment in which the present invention is applied to a head gasket.

FIG. 2 is a sectional view taken along the line II-II in FIG. 1.

3 is a cross-sectional view taken along line III-III in FIG. 1. FIG.

FIG. 4 is a partial cross-sectional view showing another embodiment of the present invention.

FIG. 5 is a sectional view showing a modification thereof.

FIG. 6 is a cross-sectional perspective view showing essential parts of another embodiment of the present invention.

FIG. 7 is a sectional view showing a main part of another embodiment of the present invention.

[Explanation of symbols]

1: Support 2: Gasket body 2a: Infiltration part 2A: Gasket body 2B: Gasket body 3: Cylinder bore 4: Annular process 5: Bolt bore 6: Gasket body 6a: Infiltration part 10: Metal ring 11: Protective plate

Claims (7)

[Claims] Claims: 1. A metal support having a predetermined shape; a sintered metal whose main component is iron or an iron-based alloy; and a metal support having a predetermined shape; A composite gasket consisting of a metal gasket body. 2. The composite gasket according to claim 1, wherein the metal support is made of iron or an iron-based alloy. 3. The composite gasket according to claim 1, wherein a plurality of said gasket bodies are integrated. 4. The gasket body according to claim 1, wherein a recess is formed along an inner edge of the gasket body, and a low melting point metal is infiltrated into at least a portion forming the recess. Composite gasket. 5. The low melting point metal is copper, lead, zinc, tin,
The composite gasket according to claim 4, characterized in that it is at least one metal selected from the group consisting of aluminum and alloys thereof. 6. The composite gasket according to claim 1, wherein the gasket body is provided with a ring-shaped metal plate on a surface opposite to the surface fixed to the metal support. 7. The composite type according to claim 1, wherein a metal protection plate having a shape corresponding to the support is disposed on the gasket body opposite to the support. gasket.