JP3345220B2 - Metal gasket - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal gasket for preventing leakage of fluid such as combustion gas, cooling water and lubricating oil by being interposed at a joint surface between a cylinder block and a cylinder head constituting an internal combustion engine. .

[0002]

2. Description of the Related Art In general, a joint surface between a cylinder block constituting an automobile engine or other internal combustion engine and a cylinder head mounted thereon is provided with a fluid such as combustion gas, cooling water, lubricating oil or the like from the joint surface. Various gaskets are interposed to prevent leakage, and a sealing function is provided by tightening both with a fastener such as a bolt. Conventionally, as such a gasket, a so-called soft gasket formed of an asbestos material, a chemical fiber material, a carbon sheet material, or the like has been provided. However, this soft gasket is an unavoidable problem due to the material. Due to the drawbacks of deterioration over time due to operation and difficulty in securing heat resistance, in recent years, metals with excellent heat resistance, compression resistance, and durability, and excellent resilience (spring characteristics) and thermal conductivity have been developed. It is well known that gaskets made of steel are widely used.

In recent years, engines have been developed to be smaller and lighter, have higher output, save fuel, and so on, in order to achieve higher performance. To be more specific, there is a tendency that an aluminum alloy is used for each member constituting the engine, and the interval between adjacent cylinder bores in the cylinder block is formed as narrow as possible.

On the other hand, when an engine member is formed using an aluminum alloy as described above, the overall rigidity of the engine member is significantly reduced as compared with a case where the engine member is formed using, for example, cast iron. . Another disadvantage that arises from the downsizing and weight reduction of the engine is that the amount of heat generated by the operation of the engine increases, but this is addressed by expanding the cooling water channel. This further reduces the overall stiffness of the engine. Further, in order to improve the cooling efficiency, the cooling water passage is formed near the cylinder bore, but a tightening portion such as a bolt for tightening the cylinder block and the cylinder head is formed at a position away from the cylinder bore. Become. As a matter of course, it is inevitable that the tightening force is large at a position close to the bolt and conversely is small at a position far from the bolt.

[0005] As described above, when the overall rigidity of the engine is reduced and the deviation of the tightening force by the fasteners such as bolts is increased, the metal gasket interposed between the joint surfaces becomes
At the end of the cylinder bore hole opened corresponding to the cylinder bore, a gap is generated between the cylinder block and the cylinder head. When such a phenomenon occurs, the surface pressure becomes unbalanced around the cylinder bore, so that the roundness of the cylinder bore is impaired, and heat conduction from the cylinder block to the cylinder head partially occurs during engine operation. Therefore, deformation of the cylinder is promoted. In addition, when the gap is generated, the joint surface side of the metal gasket is directly exposed to the combustion gas, so that the life of the metal gasket is shortened, and a disadvantage that the sealing property cannot be ensured for a long time may occur.

Therefore, in a metal gasket described in, for example, Japanese Patent Application Laid-Open No. 6-101761, in order to ensure a high gas sealing property, a grommet is attached to the peripheral portion of the bolt hole or a portion corresponding to the peripheral portion of the substrate. To make the peripheral portion (bolt hole seal portion) thicker than the other portions, and to attach a grommet to the peripheral portion of the cylinder bore hole or to return a portion corresponding to the peripheral portion of the substrate to the grommet or the folded portion. The restoring elastic body is sandwiched between the part and the substrate (cylinder bore seal part). Further, a rubber baked seal line portion for sealing water and oil is formed between the bolt hole seal portion and the cylinder bore hole seal portion.

However, in this case, when the bolt is tightened, the load for deforming the seal line portion of the rubber baked seal by the cylinder head and the load for deforming the restoring elastic body of the seal portion of the cylinder bore hole are provided inside the bolt hole of the substrate. However, the cylinder head made of aluminum alloy has low rigidity due to the reduction in size and weight, and a sufficient load is not applied. Therefore, the cylinder head bends in the portion between the bolt holes of the cylinder head (the upper side is curved). Occurs. In particular, a large bending occurs in a portion adjacent to the cylinder bore.

[0008] As described above, if large deflection occurs between the bolt holes adjacent to the cylinder bore of the cylinder head, it is difficult to seal high-temperature and high-pressure explosive gas generated during operation of the engine. Increasing the thickness of the restoring elastic body in the entire part,
Measures have been taken to increase the surface pressure around the cylinder bore by partially sandwiching a shim plate between adjacent cylinder bores.

[0009]

However, according to this measure, the deformation of the cylinder head (bending between the bolt holes) is further increased, so that the surface pressure near the bolt holes is high with respect to the tightening of the bolt holes. On the other hand, the surface pressure between the bolt holes, particularly the portion adjacent to the cylinder bore hole, becomes weaker. Therefore, when the surface of the cylinder inside the cylinder is pushed inward by the part with high surface pressure (near the bolt hole), and the bolt holes are located one at each of the four corners around the cylinder bore, the cross section of the cylinder inside the cylinder becomes clover-shaped. Deforms and loses roundness. When the engine is operated in this state, oil consumption increases,
Power loss, exhaust gas pollution, etc. occur.

The present invention can solve the above-mentioned problem, and an object of the present invention is to suppress deflection of a portion between bolt holes of a cylinder head due to bolt tightening while securing high gas sealability. By reducing the surface pressure difference between the vicinity of the bolt hole and the periphery of the combustion chamber (cylinder bore) hole for bolt tightening, and averaging the surface pressure around the combustion chamber hole,
An object of the present invention is to provide a metal gasket capable of ensuring roundness of a combustion chamber hole.

[0011] The metal gasket of the present invention, claim 1
The invention described in (1) is a metal gasket comprising a metal substrate provided with at least a combustion chamber hole and a bolt hole, and interposed between a cylinder block and a cylinder head to seal a joint between these joint surfaces. Folding the edge of the combustion chamber hole, embracing a soft material inside the turned-back portion, and forming a bead made of a rubber-based material on at least one joint surface of the substrate so as to be higher than the height of the turned-back portion. Further, a straight line passing through the center point of the adjacent combustion chamber hole is defined as a reference line, and a straight line passing through the center points of two bolt holes opposed to each other with the reference line therebetween is defined as a first bolt hole line. When a straight line passing through the center point of the plurality of bolt holes arranged on each side of the first bolt hole line is defined as a second bolt hole line, each straight line is within the bonding surface area of the substrate and on the first bolt hole line. Bolt hole At least one of a position on the substrate edge side and a position within the bonding surface area of the substrate and closer to the substrate edge side than each of the bolt holes at the ends on the second bolt hole line. A metal gasket provided with a metal thick portion which is thick and lower than the height of the turn-back and does not include a soft material is provided.

The thick portion may be formed by folding the edge of the substrate, or may be formed by fixing a shim plate or the like, which is a member separate from the substrate, at the position. In the case where the above member is fixed, the member to be used is not a material having low rigidity such as a rubber material, but is preferably a metal having the same rigidity as the substrate. The position at which the bead is formed is, in particular, a portion where the surface pressure needs to be stabilized during interposition (for example, around a combustion chamber hole, around a bolt hole, etc.), or between a space to be partitioned between joint surfaces. There is a site (for example, a seal position for partitioning an oil hole and a water hole).

According to a second aspect of the present invention, in the metal gasket according to the first aspect, the first bolt hole wire is
It is a straight line passing through the center point of two bolt holes that are symmetrical with respect to the reference line. According to a third aspect of the present invention, in the metal gasket according to the first and second aspects, the first and second bolt hole lines are assumed for all bolt holes formed in the substrate, and all the bolt holes are provided. The thick portion is provided at the position on the first and second bolt hole lines.

According to a fourth aspect of the present invention, in the metal gasket according to the first to third aspects, a part or all of the plurality of thick portions provided on the substrate is formed by folding an edge of the substrate. It is characterized by having been formed. In addition,
Folding the edge of the substrate means that when the substrate is formed (when the outer peripheral portion of the metal plate is cut into a predetermined shape and various holes are opened at predetermined positions of the metal plate), the outer peripheral edge and the inner peripheral edge ( The folding pieces are formed so as to protrude integrally from the edge of each hole formed in the substrate), and this means that the folding pieces are folded and overlapped on the substrate. The part that is present is referred to as a “turned-back” or “turned-back portion”.

According to a fifth aspect of the present invention, in the metal gasket according to the fourth aspect, the end of the folded portion as the thick portion is positioned outside at least one joint surface area of the cylinder block and the cylinder head. It is characterized by being located. According to a sixth aspect of the present invention, in the metal gasket according to any one of the first to fifth aspects, the height of the joint surface in the turn-up of the combustion chamber hole and the joint surface in the thick portion from the joint surface in the substrate is provided. However, a step is formed so as to be equal or substantially equal on both bonding surface sides of the substrate.

According to the metal gasket of the present invention, when the metal gasket is assembled with the metal block interposed between the cylinder block and the cylinder head, the deviation of the tightening force due to the distance from the fastener such as a bolt is reduced by combustion. The folded back of the room hole and the soft material inside the folded back are suitably deformed, and the bead made of the rubber material is elastically deformed, so that a sufficient sealing effect is ensured.

Further, it is presumed that the deformation of the cylinder head with respect to the bolt tightening in the cross section along the first and second bolt hole lines provided with the thick portions is as follows. That is, since the return of the combustion chamber hole is thicker than the thick portion by at least the thickness of the soft material, the cylinder head is pressed against the return of the combustion chamber hole, and the portion between the bolt holes of the cylinder head is raised. After the side is deformed into a convex curve, the substrate edge side portion comes into contact with the thick portion, but since the thick portion is made of, for example, a metal as rigid as the substrate and does not sandwich a soft material, The deformation of the cylinder head is supported with little deformation. When the tightening force is further increased, the thick portion serves as a counter, and a force is generated which deforms the portion between the bolt holes of the cylinder head into a convex curve on the lower side. Since the deformation occurs in a direction to offset the deformation of the cylinder head due to the contact with the head, the deformation of the cylinder head is suppressed.

Thus, on the first or second bolt hole line where the thick portion is provided at the position, the surface pressure of the bolt near the bolt hole and the adjacent portion of the combustion chamber between the bolt holes with respect to the bolt tightening is reduced. The difference becomes smaller. In particular, claim 3
When the thick portion is provided at the position on all the first and second bolt hole lines as in the invention described in (1), the surface pressure around the entire combustion chamber is averaged, and the combustion chamber is The roundness of the hole is ensured.

In addition, particularly when part or all of the plurality of thick portions provided on the substrate is formed by folding the edge of the substrate as in the invention according to claim 4, After the substrate is cut out so that the folding pieces are integrated, the thick pieces are easily formed by folding the pieces. However, when such folding is not possible due to the design of the substrate, a similar effect is exhibited even if a thick portion is formed by fixing a shim plate or the like at the position.

When a turn is formed, the end of the turn may not be completely flat. If the metal gasket is interposed between the cylinder block and the cylinder head while the folded end is not flat (that is, a rounded portion is generated) as described above, the operation / stop is easily performed. Due to the repetition of the cooling / heating cycle, the shape of the rounded portion at the folded end gradually changes, and the sealing performance at the end is reduced. In addition, an excessive load is necessary to crush the end portion to make it flat, and there is a possibility that a springback or a crack may be generated by crushing the end portion by applying the load (in the case where the plate thickness is 0 mm). If it is 0.3 mm or more, it is very difficult to flatten the end by crushing it).

Therefore, according to the fifth aspect of the present invention,
Since the end of the portion turned back as the thick portion is located outside the joint surface area of at least one of the cylinder head and the cylinder block, the sealability is not impaired, and the end is flattened. It is not necessary to apply a load of. This makes it possible to calculate an accurate gasket load during the interposition.

In particular, according to the invention, when the metal gasket is interposed, the joint surface of the metal gasket folded and the joint surface of the thick portion are formed between the joint surface side of the cylinder block and the cylinder. It will project to the same extent as the joint surface side of the head. Therefore, the joint surface in the folded portion and the joint surface in the thick portion come into uniform contact with both the cylinder block and the cylinder head, and the folded portion has its own spring characteristic due to the step. From the cylinder block due to the effect of tightening force or heat during operation.
The deformation can be suitably followed to the deformation of the cylinder head, and the uniformization of the surface pressure is promoted.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 and 2 are views showing an embodiment of the present invention. FIG. 1 is a plan view of a metal gasket 10, and FIG. 2 is a sectional view taken along line AA of FIG. As shown in these figures, the metal gasket 10 has a plurality of holes formed in a substrate 11 made of metal such as stainless steel. The substrate 11 is provided with, for example, metal plating, resin plating, or plating of a mixture of metal and resin on the inner surface of each of the holes and the joint surfaces around the holes. In addition, both surfaces that are folded back and thickened are coated with fluoro rubber, nitrile rubber (NBR), or disulfide in accordance with the roughness of the processing surfaces of the joint surfaces of the cylinder block and the cylinder head that constitute the engine. A surface treatment material 12 such as molybdenum is baked.

Further, the plurality of holes are provided with a plurality of cylinder bore holes 13 corresponding to the cylinder bores (combustion chambers) of the cylinder block, and bolts corresponding to the positions of the fastening bolts connecting the cylinder block and the cylinder head. A hole 14 (14a to 14f), an oil hole 15 corresponding to an oil gallery for supplying lubricating oil to each sliding portion such as a piston (not shown), and a cylinder block whose temperature is increased by combustion of fuel or sliding of the piston or the like. , A water hole 16 located inside the water jacket for supplying cooling water to the cylinder head. The bolt hole 14f is a dual-purpose hole that also serves as a bolt hole and an oil hole. Each of the holes 13 to 16 is formed in the metal gasket 10.
When the engine is constructed by interposing between the cylinder block and the cylinder head, it is opened so as to communicate with each part of the engine corresponding to each hole.

As shown in FIG. 2, of these holes 13 to 16, the cylinder bore hole 13 is formed by folding its edge to form a folded portion 21. Inside the folded portion 21 is, for example, an expanded graphite sheet or the like. The soft material 17 made of is embraced. The thickness of the soft material 17 depends on the rigidity of the engine. The greater the rigidity, the thinner it can be. However, the standard thickness is generally about 0.3 mm. By compressing at 600 kg / cm ² , about 30 to 50% compression deformation is performed. The material is not limited to the expanded graphite sheet, but may be a soft metal plate such as a lead plate, a zinc plate, a copper plate, a mild steel plate, a plastic sheet such as an ethylene tetrafluoride sheet and a polyimide sheet, or mica.

On the other hand, the center point of the adjacent cylinder bore 13
A straight line passing through₀Then, this reference line L₀Between
Bolt holes 14a to 14c arranged on one side
The center point is the reference line L₀A straight line L parallel to₁On top of the other
The center points of the bolt holes 14d to 14f arranged on the side
Line L₀A straight line L parallel to_TwoIt's above. Also, the reference line L ₀
Two bolt holes 14a, 1
The center point of 4d is the reference line L₀A straight line K orthogonal to₁Up
And the center point of the bolt holes 14b and 14e of the same arrangement.
Is the reference line L₀A straight line K orthogonal to_TwoAbove and similar arrangement
The center point of the bolt holes 14c and 14f is the reference line L₀Orthogonal to
Straight line K_ThreeIt's above. Here, the straight line K₁~ K_ThreeBut
The straight line L corresponds to a first bolt hole line of the present invention.₁, L
_TwoCorresponds to the second bolt hole line.

An oil hole 15 is provided on the straight line K ₁ on the edge side of the board with respect to the bolt hole 14 a, and the edge of the oil hole 15 along the straight line K ₁ is the same as the folded portion 21 of the cylinder bore hole 13. The folded portion 22a is formed by folding back to the joining surface side. Further, the substrate edge than the bolt hole 14d on the straight line K _1, by folding the outer peripheral edge of the substrate on the same joining surface side and the folded portion 21 of the cylinder bore hole 13, the folded portion 22d is formed.

The straight line K ₂ on the bolt holes 14b, the substrate edge side 14e, by folding the outer peripheral edge of the substrate on the same joining surface side and the folded portion 21 of the cylinder bore hole 13, respectively, folded portions 22b, 22e are formed Have been.
The substrate edge than the bolt hole 14c on the straight line K ₃ oil holes 15
There are, by folding the substrate edge portion along the straight line K ₃ edges of the oil holes 15 in the same joining surface side and the folded portion 21 of the cylinder bore hole 13, the folded portion 22c is formed. Further, bolt holes on the straight line K ₃ (oil hole serves hole)
The 14f, the folded portion 21 of the cylinder bore hole 13 of the substrate edge portion along the straight line K ₃ edge of the bolt hole 14f
By folding back to the same joint surface side as
f is formed.

[0029] Each bolt hole from the substrate edge (bolt hole of the bolt holes 14a and not shown right end illustrated in the left end portion of FIG. 1) end on the straight line L _1, the cylinder bore hole and the outer peripheral edge of the substrate The folded portion 22g is formed by folding back to the same joint surface side as the 13 folded portions 21. Similarly, also the substrate edge than the bolt hole end on the straight line L _2, by folding the outer peripheral edge of the substrate on the same joining surface side and the folded portion 21 of the cylinder bore hole 13, the folded portion 22h is formed I have.

The folded portions 22a to 22h correspond to the thick portions of the present invention, and in this embodiment, all the thick portions are integrally protruded from the edge of the substrate 11 (ie, the edge of the substrate when the substrate is formed). The folded back piece) is formed by folding back. And, these are in a state of being simply folded without holding anything inside. A lubricating material such as molybdenum disulfide or graphite is applied to both joint surfaces of the folded portions 21 and 22 (22a to 22h), while a slight unevenness is formed on the inner surface of the folded portion 21. (Flaw) is formed.

The portions of the substrate 11 where the folded portions 21 and 22 are formed project toward one of the bonding surfaces of the substrate 11. A step 23 is formed at a boundary position with the portion from the other portion toward the folded portions 21 and 22 from the upper joint surface side to the lower joint surface side in FIG. 2. As a result, the upper and lower joining surfaces of the folded portions 21 and 22 have the same height as the upper and lower joining surfaces of the substrate 11. Note that the step 23 is not formed in the portion adjacent to the cylinder bore 13 because the interval is small.

On the other hand, rubber beads 24 made of, for example, silicon rubber are formed on both joining surfaces of the substrate 11.
This rubber bead 24 is provided around the cylinder bore 13 and
It is formed around each bolt hole 14, and is formed so as to define each of the cylinder bore hole 13, the bolt hole 14, the oil hole 15, and the water hole 16 (FIG. 1).
Then, the locus of the rubber bead 24 is indicated by a dashed line).

Then, as shown in FIG.
The cross section of the substrate 11 perpendicular to the bonding surface is semicircular and symmetrical on both bonding surface sides. Note that the cross-sectional shape of the rubber bead 24 is not limited to a semicircular shape, but may be trapezoidal or another shape, or may be different around the bolt hole 14 and other places. Further, in order to satisfactorily apply the rubber bead 24, very small irregularities (scratches) may be formed by sandblasting or the like at the place where the rubber bead 24 is formed on the substrate 11.

The rubber beads 24 are formed so that the height from each of the joint surfaces of the folded portions 21 and 22 is the same, and the height is larger than the thickness of the folded portions 21 and 22 as a whole. It is formed to be 1.5 times or more. Incidentally, the thickness of the metal gasket 10, the height of the rubber bead 24 and T _1, the thickness of the folded portion 21 of the cylinder bore hole 13 and T _2, the thickness of the bolt holes 14 near the folded portion 22 and the T ₃ Then, it is necessary that the relationship between the plate thicknesses is larger in the order of T ₁ , T ₂ , and T ₃ . The rubber bead 24 can be formed by, for example, a one-stroke dispenser method, screen printing, or a mold type using a mold. In particular, screen printing facilitates formation of a stitch pattern. be able to. Further, a rubber bead may be formed by fixing a rubber sponge on the entire surface except for the folded portions 21 and 22.

It is also possible to form the rubber bead 24 only on one joint surface side and to form a metal bead on the substrate 11 protruding toward the joint surface side on the other joint surface side. Requires a mold for forming a metal bead. The metal gasket 10 thus formed
When the metal gasket 10 is interposed between the joining surfaces of the cylinder head and the cylinder block, the metal surface of the metal gasket 10 (actually, the surface treatment material 12) Is designed so that the area of contact with the metal gasket 10 is about 30% or less of the entire surface of the metal gasket 10. This is for the purpose of minimizing the absolute load when the metal gasket 10 is interposed between the cylinder block and the cylinder head and fastened with fasteners such as bolts.

Next, the operation of the metal gasket 10 having the above configuration will be described. The metal gasket 10
When interposed between the cylinder block constituting the engine and the cylinder head thereon, when these cylinder block and cylinder head are fastened with fasteners such as bolts,
The cylinder block and the cylinder head are deformed in a direction in which they are crushed by the surface pressure of the cylinder head and the cylinder head caused by the tightening force. More specifically, first, the rubber bead 24 having the highest height is elastically deformed in a direction in which it is crushed, and then the folded portions 21 and 22 are deformed in a direction in which it is crushed. The deformation of the folded portion 21 deforms the soft material 17.

At this time, in the folded portion 21, when the soft material 17 inside the folded portion 21 has a thickness of, for example, 0.3 mm,
In the part with high surface pressure close to the bolt, it is deformed by about 50%.
It is about 15 mm, and it is about 0.18 to 0.20 mm in a portion having a low surface pressure far from the bolt (for example, between the cylinder bore holes 13 and the bolt holes 14). As described above, the soft material 17 is deformed so as to be thin at a portion where the surface pressure is high, and conversely, is deformed so as to be thicker at a portion where the surface pressure is low as compared with the portion where the surface pressure is high, so that a sufficient sealing effect is secured. .

Further, if the width of the rubber bead 24 is reduced,
Since the load required for the deformation is small, the metal gasket 10 can cope with a further decrease in the rigidity of the cylinder head and the cylinder block. On the other hand, for the deformation of the cylinder head by tightening, for example, when viewed in cross-section according to the straight line K _2, as shown schematically in FIG. 3,
The cylinder head is pressed against the turn-back portion 21 of the cylinder bore hole 13, and the bolt holes 14b,
Portion between 14e is deformed in a curved upper convex (indicated at H ₁ in FIG. 3), then the bolt holes 14b, the folded portion 22b on the outside of the 14e, but in contact with 22e, the folded portion 22b , 22e support the deformation of the cylinder head with little deformation since no soft material is sandwiched between them.

When the tightening force is further increased, the folded portions 22b and 22e serve as a counter, and a force F is generated which deforms the portion between the bolt holes 14b and 14e of the cylinder head into a convex curve on the lower side. This force F is to produce in a direction to cancel the deformation H ₁ of the cylinder head caused by the contact between the folded portion 21 and the cylinder head of the cylinder bore hole, deformation of H ₂ actual cylinder head, as in the conventional folded portion 22b, it becomes small compared with the deformation H _P when 22e no.

[0040] Similarly, the cross-section with a linear K _1, K _3, deformation of the cylinder head is suppressed by the action of the folded portion 22 on the outside of the bolt hole 14 corresponding on the straight line K _1, K ₃ (substrate edge) Can be Similarly, the cross-section with a linear L _1, L _2, deformation of the cylinder head is suppressed by the action of the folded portion 22 on the substrate edge side of the straight line L _1, the bolt end on the L ₂ holes 14.

As described above, in this embodiment, the folded portion (thick portion) 22 is located at the position above all the first and second bolt hole lines (K _{1 to} K ₃ , L ₁ , L ₂ ). Is provided in the cylinder bore hole 13 for bolt tightening.
Are averaged over the entire periphery of the cylinder bore, and the roundness of the cylinder bore 13 is secured. Therefore, roundness of the cross section of the cylinder inner cylinder is ensured, and in the entire engine, improvement in fuel efficiency, reduction in power loss, and reduction in exhaust gas pollution are achieved.

Further, in this embodiment, the bolt hole 14f of the case and the oil holes also used there is the oil holes 15 than the bolt holes 14a in the substrate edge along the bolt hole line, such as straight lines K ₁ is oil holes 15 and The folds 22a, 22c, and 22f are formed by folding the edge of the dual-purpose bolt hole 14f on the side of the substrate. However, even in such a case, the fold may be formed by folding the outer peripheral edge of the substrate. Good. However, in such a case, it is better to open the oil hole or the like by leaving the folded piece than to secure the folded piece by expanding the outer peripheral edge of the board outward by the amount of the folded portion. Therefore, the cost can be reduced by forming the folded portion by folding the edge of the substrate edge side such as the oil hole as in this embodiment.

In this embodiment, the substrate 11 has the step 2
3 to form a bonding surface on the substrate 11 and the folded portion 2
Since the heights of the joint surfaces in the joint portions 1 and 22 are the same on both joint surface sides, the joint surfaces in the folded portions 21 and 22 uniformly contact both the cylinder block and the cylinder head. Face side rubber bead 24
The height of the rubber beads 24 can be the same, so that the contact of the rubber beads 24 with both the cylinder block and the cylinder head becomes uniform. Further, the folded portions 21 and 22 have spring characteristics themselves due to the steps. From these facts, the metal gasket 10 can be suitably deformed to follow the deformation of the cylinder block and the cylinder head due to the effect of the tightening force or the heat during operation.
Uniformity of surface pressure is promoted.

However, the present invention also includes a device without such a step 23. In the case where no step is formed on the substrate 11, for example, as shown in FIG. 4, the thickness of the rubber bead 24 is increased on the side of the folded portions 21 and 22 and the thickness of the opposite side is reduced, so that the bonding at the folded portions 21 and 22 is performed. The height from the surface to the upper and lower surfaces of the rubber bead 24 may be the same.

Also, the folded portion, particularly the folded portion 22 formed on the outer peripheral edge of the substrate 11, may not be completely flat at the end. When interposed between the cylinder block and the cylinder head without being flat as described above, it is easily estimated that the sealing performance is reduced at this end, while the end is crushed to obtain a flat state. To do so, an excessive load is required, and when the load is added and crushed, springback may occur. By the way, if the plate thickness is 0.3 mm or more, it is extremely difficult to crush and flatten the ends.

Therefore, as shown in FIGS. 5A and 5B, if the end 22A of the folded portion 22 is located outside at least one of the joining surfaces of the cylinder head and the cylinder block, the sealing property is impaired. There is no need to apply a load for flattening the end. With such a configuration, it is possible to calculate an accurate gasket load at the time of the interposition.

In this embodiment, all the thick portions provided on the substrate 11 are formed by folding the edge of the substrate 11 (that is, the folding piece that is integrally formed on the edge of the substrate when the substrate is formed). Since the folded portion 22 is formed, the thick portion can be easily formed. However, the present invention is not limited to this. If the folded portion 22 cannot be formed due to the design of the substrate, a thick portion may be formed by fixing a shim plate or the like at that position.

When a thick portion is formed by fixing a plate material such as a shim plate to the outer peripheral edge of the substrate, it is necessary to place each of the positions along the first and second bolt hole lines. Although a small plate may be fixed to each, it is easier to form a thicker portion by fixing an integral plate corresponding to the entire outer peripheral edge of the substrate and making the entire outer peripheral edge thicker. At the same time, the above-mentioned counter effect by the thick portion is enhanced.

In this embodiment, for example, a straight line K
Both the folded portion 22a along _one, as 22d, when the folded portion 22a from a reference line L _0, the distance to 22d differ, sandwiching a shim plate or the like in the distance is longer folded portion 22a of the It is preferable to increase the thickness as a thick portion so that the same counter effect can be obtained in both folded portions 22a and 22d. Further, in order to obtain the same counter effect, the ratio between the distance and the thickness of the thick portion excluding the substrate may be the same in both the thick portions.

When the oil hole 15 is provided outside the bolt holes 14a and 14c as in the folded portions 22a and 22d, the bolts are formed in addition to the folded portions 22a and 22c formed on the substrate edge side. A similar folded portion may be provided on the side of the holes 14a and 14c. Further, a thick portion may be formed by fixing a shim plate at that position. That is,
The thick portion formed along one bolt hole is not limited to two, but may be three or more.

In this embodiment, the thick portions (return portions 22) are provided at predetermined positions on all the first and second bolt hole lines, but the thick portions are part of the first and second bolt holes. The present invention also includes those provided at predetermined positions on the two bolt hole lines, and even in this case, the deformation of the cylinder head is partially suppressed. The surface pressure is averaged, and the roundness of the cylinder bore can be increased.

[0052]

As is apparent from the above description, according to the metal gasket of the present invention, the sealing effect is ensured by the return of the combustion chamber hole and the bead made of a soft material and a rubber material inside the return. You. In addition, the thick portion formed on the substrate edge side for each line indicating the arrangement of the bolt holes,
The deformation of the cylinder head at the time of tightening the bolt is suppressed, and the difference in the surface pressure between the vicinity of the bolt hole and the adjacent portion of the combustion chamber between the bolt holes is reduced when the bolt is tightened. According to this, since the thick portion is provided at the position on all the first and second bolt hole lines, the surface pressure around the combustion chamber hole of the cylinder head is averaged, and the combustion chamber hole Roundness is ensured. As a result, in the engine using the metal gasket, reduction of oil consumption, improvement of fuel consumption, reduction of power loss, and reduction of exhaust gas pollution are achieved.

In particular, according to the fourth aspect of the present invention, since the thick portion is formed by folding, the surface pressure around the cylinder bore can be easily averaged, so that the manufacturing cost can be reduced. In particular, according to the invention as set forth in claim 5, since the end of the portion folded back as the thick portion is located outside at least one of the joining surface areas of the cylinder block and the cylinder head, the sealing performance may be impaired. Therefore, it is possible to calculate an accurate gasket load at the time of interposition without adding a load for flattening the end portion.

In particular, according to the invention as set forth in claim 6, the joint surface at the turn-up of the combustion chamber hole and the joint surface at the thick portion are both on the joint surface side of the cylinder block and on the joint surface side of the cylinder head. The surface pressure can be evenly contacted, and the folded back suitably deforms following the deformation of the cylinder block and the cylinder head due to the effect of the tightening force or the heat during operation. Can be.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of a metal gasket according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

The action resulting by providing the thick portion in FIG. 3 the present invention there is provided a schematic diagram for explaining a metal gasket embodiment is the schematic diagram corresponding to the sectional view according to the straight line K ₂ .

FIG. 4 is a view corresponding to a cross-sectional view taken along line AA of FIG. 1 when no step is provided.

FIG. 5 is a cross-sectional view showing an example in which an end portion of a folded portion corresponding to a thick portion is located outside a joint surface area of a cylinder block and a cylinder head, and FIG. FIG. 4B shows a case where the cylinder block and the cylinder head are located outside the joint surface area.

DESCRIPTION OF SYMBOLS 10 Metal gasket 11 Substrate 13 Cylinder bore hole (combustion chamber hole) 14a to 14f bolt hole 15 Oil hole 16 Water hole 17 Soft material 21 Folded part 22a to 22h Folded part (thick part) 22A Folded part End 23 Step 24 Rubber bead L ₀ Reference line L ₁ , L ₂ straight line (second bolt hole line) K _{1 to} K ₃ straight line (first bolt hole line)

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-101761 (JP, A) JP-A-5-149438 (JP, A) JP-A-6-34049 (JP, A) 346169 (JP, A) Fully open 1984-188351 (JP, U) Fully open Hei 6-25666 (JP, U) Fully open 4-75270 (JP, U) Really open 4-111961 (JP, U) Hikaru 2-16859 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F16J 15/08

Claims (6)

(57) [Claims] 1. A metal gasket comprising a metal substrate having at least a combustion chamber hole and a bolt hole, and interposed between a cylinder block and a cylinder head to seal a joint between the cylinder block and the cylinder head. The edge of the combustion chamber hole is folded back, and a soft material is embraced inside the folded back, and a bead made of a rubber material is formed on at least one joint surface of the substrate so as to be higher than the height of the folded back, Further, a straight line passing through the center point of the adjacent combustion chamber hole is defined as a reference line, a straight line passing through the center points of two bolt holes opposed to each other with the reference line interposed therebetween is defined as a first bolt hole line, and the reference line is defined as a first bolt hole line. When a straight line passing through the center point of the plurality of bolt holes arranged on each side sandwiched therebetween is defined as a second bolt hole line, each bolt in the bonding surface area of the substrate and on the first bolt hole line Hole At least one of a position on the substrate edge side and a position within the bonding surface area of the substrate and closer to the substrate edge side than each of the bolt holes at the ends on the second bolt hole line. A metal gasket comprising a thick metal portion that is thick and lower than the height of the turn-back and does not include a soft material . 2. The metal gasket according to claim 1, wherein the first bolt hole line is a straight line passing through the center point of the two bolt holes that are line-symmetric with respect to the reference line. 3. Assume the first and second bolt hole lines for all bolt holes opened in the substrate, and place the meat in the positions on all the first and second bolt hole lines. The metal gasket according to claim 1, wherein a thick portion is provided. 4. The substrate according to claim 1, wherein a part or all of the plurality of thick portions provided on the substrate are formed by folding an edge of the substrate. Metal gasket. 5. The metal gasket according to claim 4, wherein an end of the portion turned back as the thick portion is located outside a joining surface area of at least one of the cylinder block and the cylinder head. 6. The height of the joint surface at the turn-back of the combustion chamber hole and the joint surface at the thick portion from the joint surface on the substrate is equal or substantially equal on both joint surface sides of the substrate. The metal gasket according to any one of claims 1 to 5, wherein a step is formed on the metal gasket.