JP4864530B2 - Metal gasket - Google Patents

Description

  The present invention relates to a metal gasket that is interposed between opposed joint surfaces of a cylinder block and a cylinder head constituting an internal combustion engine, and is useful for sealing between the joint surfaces by bolt fastening. This is a useful technique for a metal gasket that can reduce the rigidity of a substrate by sealing with a synthetic elasticity of a metal bead and a rubber bead made of an elastic sealing material.

  Conventionally, as a metal gasket having a plurality of combustion chamber holes, for example, there is a gasket described in Patent Document 1. As shown in FIG. 6, this metal gasket comprises a substrate 1 made of a thin metal plate such as a stainless steel plate or a mild steel plate, and various types such as a combustion chamber hole 2, a bolt hole, an oil hole, and a water hole are formed on the substrate 1. Further, the periphery of the hole that needs to be sealed is surrounded by a metal bead made of a convex full bead or a stepped half bead. Further, an elastic sealing material 11 having heat resistance and elasticity is disposed on at least the upper and lower surfaces of the metal bead 6 surrounding the combustion chamber hole 2, and a synthetic bead composed of the metal bead 6 and a rubber bead made of the elastic sealing material 11. It is sealed with synthetic elasticity. Thus, by sealing with synthetic elasticity, the rigidity of the board | substrate 1 and the reduction | decrease of a tightening torque can be aimed at, As a result, it can respond effectively to size reduction or aluminumization of an engine.

In addition, a thickening portion 9 is disposed so as to increase the thickness by stacking plates on the substrate 1 so as to surround the outer periphery of the combustion chamber hole 2. The thickened portion 9 serves to seal the high-pressure combustion gas in the bore and limit over-compression of the bead surrounding the thickened portion 9.
International Publication WO2003 / 085294

In recent years, the evolution of engines has been accelerated, and further reductions in size and weight and performance have been made. Here, with the reduction in size and weight of the engine, the distance from the end portion of the combustion chamber hole 2 to the water hole or the like on the outside tends to be extremely narrow, and the distance between the combustion chamber hole 2 and the water hole or the like tends to be extremely small. It is necessary to provide the substrate portion with the thickened portion 9, the metal bead 6 surrounding the thickened portion outer peripheral side, and the elastic seal material 11 molded on both upper and lower surfaces of the metal bead 6. The width of the bead 6 cannot be made extremely narrow for maintaining performance. For this reason, it is conceivable to reduce the bead width of the rubber bead made of the elastic sealing material 11 that requires a larger bonding area than the width of the metal bead 6. At this time, when the bead width of the elastic sealing material 11-1 on the convex side of the metal bead 6 is reduced to a dimension that is equal to or close to the width of the metal bead 6, the elastic sealing material 11-1 is the substrate 1. On the other hand, it is almost joined only to the inclined portion of the metal bead 6, due to the compressive deformation when it is attached and fastened to the engine, and the load repeatedly input during engine operation and the difference in thermal expansion between the gasket substrate material and the engine material. As a result of the movement in the engine thrust direction, the rubber beads are easily peeled off from the metal substrate 1, resulting in a shortened life of the gasket.
The present invention has been made paying attention to the above points, and is deformed in the lateral direction due to compression deformation of the elastic sealing material formed on the inclined portion of the metal bead that has been deformed to the height of the thickened portion. It is an object to provide a metal gasket capable of absorbing the amount and suppressing the peeling of the rubber beads.

In order to solve the above-mentioned problem, the invention described in claim 1 of the present invention uses a metal plate having one or more combustion chamber holes as a substrate, and the plate thickness is thick along the periphery of the combustion chamber holes. A thickened portion is formed, and a bead is formed so as to surround the outer periphery of the thickened portion. The bead bends the substrate and protrudes toward the thickened side of the thickened portion, and at least the metal bead A metal gasket composed of a synthetic bead that is fixed to the surface of the convex portion and filled with a concave portion on the back side of the convex portion and made of an elastic sealing material that can generate a spring force together with the metal bead, the metal bead The elastic sealing material that adheres to the surface of the convex portion of the substrate is also continuously adhered to the surface of the substrate flat portion located between the thickened portion and the metal bead, and the elastic sealing material provided on the surface of the substrate flat portion At least part of A low deformation absorbers in height than KizoAtsu portion, the elastic sealing member provided on the substrate flat part surface, while contacting the outer peripheral side end face of the increased thickness portion, the deformation absorbing portion of at least the increase It is assumed that the outer peripheral side of the thickened portion is formed lower than the inner peripheral side of the thickened portion and is continuous with the deformation absorbing portion. It is a feature.

Next, according to a second aspect of the present invention, in the structure according to the first aspect, a plurality of bolt holes are formed in the substrate so as to surround the combustion chamber holes on the outer peripheral side of the metal beads. The height of the thickened portion is relatively low at the position close to the bolt hole, and the height is adjusted so as to become relatively high as the distance from the bolt hole increases. The deformation absorbing portion is characterized in that the height of the deformation absorbing portion is lower than the position where the height due to the inflection change is lowest .

  According to the present invention, the amount of deformation when the elastic sealing material formed on the convex inclined portion of the metal bead is compressed and deformed can be absorbed in the space formed above the deformation absorbing portion. This makes it difficult for at least the elastic seal material on the metal bead convex portion side to peel off.

(First embodiment)
Next, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view showing a metal gasket according to the present embodiment. 2 is a cross-sectional view taken along line AA in FIG.
(Constitution)
As a material of the substrate 1 of the metal gasket 10, for example, a metal thin plate such as a stainless steel plate, a mild steel plate, or an aluminum plate can be appropriately employed. And as a result of employ | adopting the below-mentioned synthetic bead as a bead, a mild steel plate with low rigidity can be used.

As shown in FIG. 1, a combustion chamber hole 2 is opened at a substantially central portion of the substrate 1. The entire circumference of the open end of the combustion chamber hole 2 is folded upward to form the thickest thickened portion 9, thereby providing a plate thickness difference with the other substrate 1 portion. A stopper for the bead. In the present embodiment, the thickened portion 9 is increased upward by the plate thickness.
The height of the thickened portion 9 along the circumferential direction changes so as to be inflated along the circumferential direction so that the surface pressure along the circumferential direction approaches evenly during bolt tightening. That is, height adjustment is performed by forging or the like so that the height near the bolt hole 3 is relatively low and becomes relatively high as the distance from the bolt hole 3 increases.

Here, in the present embodiment, mild steel having low rigidity can be used as the material of the substrate 1. As a result, the folding process for forming the thickened portion 9 is facilitated, and the height of the thickened portion 9 can be easily adjusted. is there. Furthermore, fatigue failure of the bending R portion can be suppressed by reducing the material hardness.
In addition, an inner peripheral seal line L1 is set on the substrate 1 so as to surround the outer periphery of each combustion chamber hole 2 on the outer side in the vicinity of the thickened portion 9, and on the outer peripheral side of the inner seal line L1. A water hole 4 and a bolt hole 3 are appropriately formed, and an outer peripheral side seal line L2 is set in a portion that needs to be sealed. Reference numeral 5 denotes an oil hole.

  Then, as shown in FIG. 2, the substrate 1 is bent in the plate thickness direction along the inner peripheral seal line L <b> 1 to form a metal bead 6 made of a step-shaped half bead on the upper side. In addition, the first elastic sealing material 12-1 is fixed to the surface of the substrate 1 on the convex side of the metal bead 6, and the same second elastic sealing material is also provided in the concave portion located on the back side of each convex side. 12-2 is filled. The elastic sealing material 12 is made of a material having heat resistance and elasticity, such as a rubber material or a resin material such as fluorine rubber, NBR, or silicon rubber.

The first elastic sealing material 12-1 fixed to the convex portion side of the metal bead 6 is joined to an inclined surface formed by the convex portion of the metal bead 6. The height of the elastic sealing material 12-1 is approximately the same as the height of the metal beads 6.
Further, an elastic sealing material (hereinafter referred to as a third elastic sealing material) continuous with the first elastic sealing material 12-1 is also formed on the upper surface of the flat substrate portion 1a located between the thickening portion 9 and the metal bead 6. 13) is attached.

The height of the third elastic sealing material 13 is set to be lower than the height of the thickening portion 9 to constitute a deformation absorbing portion. That is, when the gasket 10 is mounted on the engine, a space having a predetermined volume is formed between the third elastic seal material 13 and the joint surface of the engine.
Here, the role of the rubber beads made of the first and second elastic sealing materials 12 is that the high-pressure gas from the combustion chamber hole 2 side is fine in the tool mark on the joint surface portion facing the thickened portion 9. Even if the gas leaks through the groove, the groove is filled by the elastic deformation of the elastic sealing material 12 at the position of the inner peripheral seal line L1, so that the high pressure gas leaks to the water hole 4 side. It can be completely blocked from moving to seal. In addition, even when cooling water enters from the opposite side (outer peripheral side) of the inner peripheral side seal line L1, the flexible rubber beads can be completely blocked and sealed even to the tool mark.

Further, in this embodiment, since the upper and lower contact surfaces at the seal position are soft elastic sealing materials, the gasket coefficient can be reduced. As a result, the overall tightening load is reduced without requiring a large load, that is, the bolt tightening axial force. Can be reduced.
A synthetic bead having the same structure as described above is also formed on the outer peripheral side seal line L2.

(Action / Effect)
In the case of an engine gasket having a short distance from the end portion on the combustion chamber hole 2 side to the water hole 4 outside the combustion chamber hole 2, the bead width of the beads formed along the inner seal line L1 cannot be widened. The rubber beads molded on both surfaces of the metal bead 6 may be peeled off due to a difference in thermal expansion of the sealing surface due to repeated operation and stop when the bonding area with the substrate 1 is narrow. In particular, on the thickened side (upper surface side) of the thickened portion 9, the bead width tends to be narrowed as the thickened portion 9 and the metal bead 6 approach each other.

  On the other hand, in the present embodiment, the third elastic sealing material 13 that is continuous with the first elastic sealing material 12-1 on the convex side and does not directly contribute to the sealing is replaced by the thickened portion 9 and the metal bead 6. By joining to the substrate flat part 1a located between the two, the joining area between the substrate 1 and the elastic sealing material is increased. At this time, the bonding area can be reliably increased by bonding the third elastic sealing material 13 to the entire surface of the substrate flat portion 1 a until it comes into contact with the thickened portion 9. In particular, the portion where the third elastic sealing material 13 is in contact with the thickened portion 9 also contributes to an increase in the bonding area with the substrate 1.

Further, by reducing the height of the third elastic sealing material 13 to form a deformation absorbing portion, the amount of deformation that escapes in the lateral direction when the first elastic sealing material 12-1 is compressed and deformed is reduced to the third level. Since the elastic sealing material 13 part expands and absorbs in the upper space part, it is possible to prevent an excessive force from being generated on the joint surface between the first elastic sealing material 12-1 and the substrate 1.
As described above, even when the bead width of the rubber bead is narrowed, the first elastic sealing material 12-1 is hardly peeled off from the substrate 1, and accordingly, the performance of the gasket and the life deterioration can be suppressed.

Here, when considering the molding of the rubber bead in the production of the metal gasket 10, the substrate 1 is first processed to form the metal bead 6 and the like, and the outer edge of the combustion chamber hole 2 is folded upward to increase the thickness. Part 9 is formed. Thereafter, a rubber bead molding mold is attached to both surfaces of the substrate 1, and a sealing agent is injected into the mold to mold the rubber bead. At this time, the substrate 1 has a variation in plate thickness within a large area, and when the thickened portion 9 is formed by folding the outer edge of the combustion chamber hole 2, the width of the thickened portion 9 has a predetermined variation (dimensional error). ) Is likely to occur. In this case, when the width of the thickened portion 9 is longer than the target value, the mold may be placed on the thickened portion 9. In consideration of this, the configuration of the second embodiment described later is preferable.
Moreover, although the said embodiment illustrated the case where the combustion chamber hole 2 was one, it is applicable even if there are two or more combustion chamber holes 2. FIG.
Moreover, although the height of the said 3rd elastic sealing material 13 is formed uniformly, it does not need to be constant.

(Second Embodiment)
Next, a second embodiment will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected and demonstrated about the member similar to said each embodiment.
(Constitution)
The basic configuration of this embodiment is the same as that of the first embodiment, but the configuration of the outer peripheral side portion of the thickened portion 9 is different. That is, as shown in FIG. 3, the stepped portion 14 is formed on the outer peripheral side of the thickened portion 9, and the height of the stepped portion 14 is changed among the inflection changes formed along the circumferential direction of the thickened portion 9. It is lower than the lowest height. The height of the stepped portion 14 is the same as or substantially the same as the height of the third elastic sealing material 13.

In addition, it is not necessary to make the height of the level | step-difference part 14 and the 3rd elastic sealing material 13 correspond.
By absorbing the amount of deformation when the first elastic sealing material 12-1 is compressed and changed not only in the space above the third elastic sealing material 13 but also above the stepped portion 14, The volume for absorbing the deformation amount can be increased.
The third elastic sealing material 13 expands when the first elastic sealing material 12-1 is compressed and deformed. At that time, the third elastic sealing material 13 is placed on the joint surface of the opposing engine. There is no need to touch. When in contact, the seal pressure is low, but can contribute somewhat to sealing the gas from the bore. In particular, when the step 14 is formed as in the second embodiment, the space above the step 14 even after the third elastic sealing material 13 comes into contact with the facing joint surface of the engine. Therefore, there is a possibility that a slight sealing function by the third elastic sealing material 13 can be secured.

Further, if the stepped portion 14 that is continuous with the third elastic sealing material 13 is formed on the outer peripheral side of the thickened portion 9 as described above, the length of the thickened portion 9 is increased due to the influence of the plate thickness of the substrate 1 and the like. Even if there is an error, if the width of the thickened portion 9 is set slightly longer, a portion of the mold (see the one-dot chain line in FIG. 3) is placed on the stepped portion 14 to ensure that the thickened portion 9 It is possible to mold the third thickened portion 9 having a lower height and contacting (adhering) to the thickened portion 9.
Here, the stepped portion 14 may not be formed in advance, and the stepped portion 14 may be formed by denting the outer periphery of the thickened portion 9 with a pressure applied by a mold. Since the substrate 1 of the present embodiment can be formed of a material having low rigidity, the stepped portion 14 can be sufficiently formed by the pressure applied by the mold.

Here, in the said embodiment, although the metal bead 6 formed along the 1st seal line L1 has illustrated the case where it forms with a step-like half bead in order to narrow a bead width, As shown in FIG. 4, it may be formed from a full bead. Even in this case, the same effect as described above can be obtained.
Further, in all the above embodiments, the case where the thickened portion 9 is formed by folding the substrate 1 is illustrated, but as shown in FIG. 5, another plate 16 is joined to the substrate 1 by welding or the like to increase the thickness. The portion 9 may be formed, or the thickened portion 9 may be formed by forging or the like.

It is a top view which shows the metal gasket which concerns on embodiment based on this invention. It is AA sectional drawing in FIG. It is sectional drawing which shows the metal gasket which concerns on 2nd Embodiment based on this invention. It is sectional drawing which shows the modification of 2nd Embodiment. It is sectional drawing which shows the modification of a thickening part. It is sectional drawing which shows the structure of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Combustion chamber hole 3 Bolt hole 4 Water hole 6 Metal bead 9 Thickening part 10 Metal gasket 12-1 1st elastic sealing material 12-2 2nd elastic sealing material 13 3rd elastic sealing material 14 Step part L1 Inner circumference side seal line

Claims (2)

A metal plate having one or two or more combustion chamber holes is used as a substrate, a thickened portion is formed along the periphery of the combustion chamber holes, and a bead is formed so as to surround the outer periphery. A bead is bent on the substrate to be convex on the thickened side of the thickened part, and is fixed to at least the convex side surface of the metal bead and filled in a concave part on the back side of the convex part together with the metal bead. A metal gasket composed of a synthetic bead with a rubber bead made of an elastic sealing material capable of generating a spring force,
The elastic sealing material that adheres to the convex side surface of the metal bead is also continuously adhered to the surface of the substrate flat portion located between the thickened portion and the metal bead, and is provided on the surface of the substrate flat portion. At least a part of the elastic sealing material is a deformation absorbing portion having a height lower than that of the thickened portion , and the elastic sealing material provided on the surface of the flat substrate portion contacts the outer peripheral end surface of the thickened portion. The deformation absorbing portion is formed at least on the thickened portion side, and the outer peripheral side of the thickened portion is formed lower in height than the inner peripheral side of the thickened portion and the deformation A metal gasket characterized by being continuous to the absorption part . A plurality of bolt holes are opened on the substrate so as to surround the combustion chamber hole on the outer peripheral side of the metal bead, and the height of the thickened portion is relative to the height near the bolt hole. The height is adjusted to be relatively high as it moves away from the bolt hole, and changes so that the inflection can be applied along the circumferential direction. 2. The metal gasket according to claim 1 , wherein the height of the deformation absorbing portion is lower than the position .

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