JPH04248070A - Metal gasket - Google Patents

Abstract

PURPOSE:To provide a metal gasket which secures the sealing force of the bead according to the area between combustion chambers which are subject to deform due to heat because the rigidity of a cylinder head is lowered most by making the rigidity of the bead section positioned in the area between cylinder bores out of the beads formed along the peripheral edges of the cylinder bores of a bead plate higher than the rigidity of a bead section positioned in an area other than the area between the cylinder bores. CONSTITUTION:In this metal gasket 10, since the rigidity of a bead section 13Z positioned in an area Z other than the area between the cylinder bores 14 and 14 of a bead plate 11 is made lower than that of the bead section 13Y positioned in the area Y between the cylinder bores 14 and 14, the rigidity of the bead section 13Y positioned in the area Y is relatively higher than that of the bead section 13Z. The area X between the areas Y and Z is the one in which the rigidity of a bead section 13X varies smoothly.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a metal gasket that is placed between opposing surfaces of a cylinder head and a cylinder block in a multi-cylinder engine, and seals the opposing surfaces while the cylinder head is tightened and fixed to the cylinder block. Regarding.

0002

[Prior Art] Conventionally, a metal gasket that is disposed between a cylinder head and a cylinder block and seals between opposing surfaces of the cylinder head and cylinder block when the cylinder head is tightened relative to the cylinder block has been used for cylinder bores. A metal gasket is used that has a bead substrate made of an elastic metal plate with beads formed around the periphery of the hole. By tightening the cylinder head to the cylinder block with a tightening means such as a bolt, the bead of the bead base plate comes into contact with the cylinder head or cylinder block and deforms, and the contact part is the surface facing the cylinder head or cylinder block. becomes the sealing surface. On the sealing surface, the bead is in strong elastic contact with one opposing surface, and even on the side where no bead is formed, the reaction force causes the metal gasket to contact the other opposing surface, and the elastic deformation force This provides good sealing between opposing surfaces.

[0003] Such a metal gasket is disclosed in, for example, Japanese Patent Laid-Open No. 155376/1983. 9 and 10 are drawings showing a part of the metal gasket, and FIG. 9 is a plan view of the metal gasket,
Figure 10 shows a line E that crosses between the cylinder bore holes in Figure 9.
-E is a sectional view. The metal gasket 50 shown in these figures consists of two metal plates: an elastic metal plate on which beads 53 are formed, that is, a bead substrate 51 and a sub-plate 52 laminated on the bead substrate 51. The sub-plate 52 is laminated on the bead substrate 51 on the side opposite to the side on which the beads 53 are formed. The bead 53 is connected to the cylinder bore hole 54
It is formed to surround the The peripheral edge of the punched hole for the combustion chamber in the sub-plate 52 is folded back to sandwich the peripheral edge of the punched hole in the bead base plate 51 to form a grommet portion 55 . The edge of the sub-plate 52 that is folded back forms a cylinder bore hole 54 . The grommet portion 55 has a bead 5
3 functions as a compensating portion having a predetermined thickness on the cylinder bore hole 54 side.

The metal gasket 50 prevents the gap between the facing surfaces of the cylinder head and cylinder block from expanding or contracting due to the influence of combustion gas pressure or engine heat. Further, since the surface pressure applied to the metal gasket 50 is distributed to the grommet portion 55, the alternating load acting on the bead 53 is reduced, and the stress generated on the bead 53 is reduced, so that the occurrence of sagging of the bead 53 is prevented. Ru. The grommet portion 55 also functions as a stopper against deformation of the bead 53, which is a secondary seal. Furthermore, since the circumference of the cylinder bore hole 54 is sealed by both the grommet portion 55 and the bead 53, leakage of combustion gas is further prevented.

In addition, recent internal combustion engines are required to be lighter in weight as well as higher output, and as part of this effort, the cylinder head and cylinder block are made of aluminum alloy material with low specific gravity instead of the conventional cast iron material with high specific gravity. There is a tendency to In addition, the spacing between these cylinders, or the wall thickness between the cylinder boreholes, is becoming increasingly thinner. As the spacing between cylinder bore holes narrows, it becomes difficult to secure an independent bead for each cylinder bore hole on the bead substrate due to space constraints even in metal gaskets, and adjacent beads overlap each other between cylinder bore holes to form a single compound. It has to be the bead part. Further, the area where the sealing performance of the metal gasket is expected to be the best is between the cylinder bore holes. Due to these narrow dimensions, the rigidity of the cylinder head is low and deformation is likely to occur in areas where the cylinder head is easily deformed due to the conflicting demands of applying higher bead stress than other areas to ensure sealing pressure. It is necessary to respond. However, if the stress generated in the bead is too high, the bead is likely to suffer from sagging, cracking, etc., which shortens the life of the metal gasket.

[0006] As for how to treat such a composite bead part, for example, there are metal gaskets shown in FIGS. 11 to 15. FIG. 11 is a plan view of the bead substrate 61 between the cylinder bore holes 64 of the metal gasket 60. At the meeting part 66 where the beads 63, 63 provided around the adjacent cylinder bore holes 64, 64 meet, the bead line 63a is connected with a slight curve, and the meeting parts 66, 66 on both sides (upper and lower in the figure) are connected. Now, the straight bead 67
It becomes. Regarding beads 63, 63, bead line 6
Dotted lines 63b, 63b on both sides of 3a, 63a indicate the bead outline.

FIG. 12 shows adjacent cylinder bore holes 74,
Metal gasket 7 showing bead substrate 71 between 74
0 is a partial plan view of the same type of metal gasket as in FIGS. 9 and 10 shown earlier. A sub-plate 72 is located on the front side of the drawing with respect to the bead substrate 71 located on the back side of the drawing, and the cylinder bore hole 74 side of the sub-plate 72 is folded back to the bead substrate 71 side to form a grommet portion 75. The bead lines 73a of the beads 73, 73 provided around the adjacent cylinder bore holes 74, 74 merge as they are to form a meeting part 76, and the two meeting parts 76, 7
Between 6 and 6, there is a straight bead 77. bead 73
, 77, dotted lines 73b and 77b on both sides of the bead line 73a and bead line 77a indicate the bead outline.

[0008] Furthermore, regarding how to construct the composite bead portion, there is a metal gasket disclosed in Japanese Patent Laid-Open No. 63-210465. Regarding the metal gasket 80 disclosed in this publication, as a part of it is shown in FIG. It becomes. As shown by the intervals L1, L2, and L3 in the figure, the bead width L1 of the meeting portion 86 is
Width L of bead 83 located at a location other than the cylinder bore hole
3 and the bead width L2 of the bead 87 between the meeting parts. A metal gasket in which the bead width is widened at the meeting part and the bead width is reduced at the center of the bead between the meeting parts until it becomes the same width as the bead width other than the meeting part, has a decrease in the spring constant of the meeting part, that is, a decrease in the spring constant of the meeting part. However, the metal gasket 80 disclosed in the above publication
The company claims that it is possible to prevent such a decline.

[0009] Regarding another configuration of the composite bead part,
As shown in Figures 14 and 15, the actual equity 1-8
There is a metal gasket disclosed in Japanese Patent No. 678. In the metal gasket 90, the beads 93, 93 formed on the bead substrate 91 along the periphery of adjacent cylinder bore holes form a meeting portion 96 in a region where the cylinder bore holes 94, 94 approach each other.
However, this meeting part 96 is connected to the nearest fastening bolt hole 9
It is close to part 8. That is, the bead lines 93a, 93a of the beads 93, 93 are located around the fastening bolt hole 98 at approximately the same distance from the center of the bolt hole 98. The bead wires 93a, 93a are connected to a bead wire 97a of one bead 97 at a meeting portion 96. It is expected that the surface pressure at the time of fastening flattens the bead shape of the meeting portion 96 and its vicinity, thereby improving the sealing performance of the meeting portion 96. Regarding beads 93, 97, bead lines 93a, 97
Lines 93b and 97b on both sides of a represent the bead outline.

Furthermore, as a means for changing the height of the bead of a bead substrate, there is a metal gasket provided with a spacer as disclosed in Japanese Utility Model Application Publication No. 16459/1983. Figure 1
6 shows the bead line 103a portion of the bead 103 formed on the bead substrate 101 and the bead outline line 103b on both sides thereof.
An example is shown in which a spacer 104 is provided in a portion, and FIG. 17 shows an example in which a spacer 104 is provided only in a bead line 103a portion. The spacer 104 can be formed by building up the bead substrate 101 or applying thick plating. By providing the spacer 104, the height of the bead 103 becomes higher, and even if the cylinder head 1 and the cylinder block 2 are deformed with the operation of the internal combustion engine and the distance between the opposing surfaces becomes larger, the metal gasket 103
is expected to be able to follow such thermal distortion and ensure a seal between the facing surfaces of the cylinder head 1 and cylinder block 2.

Furthermore, since the arrangement of bolt tightening positions around the cylinder bore hole is limited, the conditions for pressing the bead of the bead substrate differ depending on the location. Although not shown in the drawings, Japanese Patent Laid-Open No. 62-224772 discloses a metal gasket in which a spacer is made of a material that becomes progressively more difficult to deform under pressure as the distance from the bolt tightening area increases. Furthermore, although not shown in the drawings, a metal gasket in which a thin metal plate is interposed in the gap between the facing surfaces formed by the bead in the portion between the cylinder bore holes of the bead substrate is disclosed in Japanese Patent Laid-Open No. 186950/1982 and Japanese Utility Model Laid-Open No. 63-1989. 1667
It is disclosed in Publication No. 59.

0012

[Problems to be Solved by the Invention] However, when the metal gasket 50 shown in FIGS. 9 and 10 is placed between the facing surfaces of the cylinder head and the cylinder block and is tightened with tightening means such as bolts, Although the extent varies depending on the arrangement and the shape of the cylinder head and cylinder block, deformation may occur in the cylinder head on the less rigid side, or the distance from the tightening position to the bead 53 in the vicinity is not constant, so the tightening force is applied to the bead substrate. cannot be evenly distributed over the beads. Particularly in the area where the combustion chamber holes are adjacent, deformation near the opposing surface of the cylinder head increases, and the degree of deformation becomes more significant as the wall thickness between the combustion chamber holes becomes thinner. Therefore, sufficient tightening pressure, that is, surface pressure, cannot be obtained on the bead corresponding to the area adjacent to the combustion chamber hole of the metal gasket, and there is a risk that the sealing effect will be reduced. Further, the gap between the cylinder head and the cylinder block increases and decreases repeatedly according to the combustion cycle of the internal combustion engine, and accordingly, the bead of the metal gasket is subjected to repeated loads and deformations. Such fluctuations in stress and strain are also greatest at the portions of the cylinder head where the rigidity is lowest, which poses the problem of deterioration of sealing performance, particularly in the form of sagging or cracking in the bead between the combustion chambers.

Furthermore, in the metal gasket 50 shown in FIGS. 9 and 10 and the metal gasket 70 shown in FIG. Bead 5
The portion where 3 and 73 are located consists of two layers with a space inside. In addition, the grommet portions 55, 75 and the bead 53,
The area between the plate 73 and the plate 73 consists of two layers in which the plates 51, 71 and the sub plates 52, 72 are in contact with each other. Therefore, the grommet parts 55 and 75 are directly exposed to load fluctuations and vibrations between the cylinder head and the cylinder block.
When the thickness of the sub-plates 52, 72 is made thinner, there is a problem in that the grommet portions 55, 75 are more likely to crack when used for a long period of time. On the other hand, if the plate thickness of the sub-plates 52 and 72 is increased, when the cylinder head is tightened to the cylinder block, the tightening load is relatively likely to be concentrated on the compensating section consisting of three layers, so that the cylinder bore hole including the bead is There is a problem in that an average surface pressure distribution state cannot be ensured in the surrounding area, and as a result, a good sealing state cannot be maintained for a long period of time. Considering that the grommet parts 55, 75 function as a stopper against lateral deformation of the secondary plates 52, 72, cracks occur in the grommet parts 55, 75 in response to large deformation of the secondary plates 52, 72. I have concerns. As described above, forming the grommets 55 and 75 itself increases the manufacturing cost of the metal gasket, and it is difficult to improve the precision of the grommets, and they have various drawbacks as described above. It is.

In the metal gaskets 60, 70 shown in FIGS. 11 and 12, or the metal gasket 80 shown in FIG. 13, the cylinder bore holes 64, 74,
Two meeting parts of beads 63, 73, 83 between 84, 66 and 66, 76 and 76, and bead 6 between 86 and 86
Since 7, 77, and 87 are straight beads having a substantially constant width, they are not a perfect solution to ensuring long-term sealing properties. In other words, since the width of each part of the bead other than the meeting part is approximately constant, even though their spring constants appear to remain the same, the spring characteristics change significantly discontinuously at the meeting part, and the cylinder When the head is tightened to the cylinder block, the stress acting on the metal gasket between the cylinder bore holes changes discontinuously, making it impossible to ensure a balance in surface pressure. Therefore, when used for a long time, cracks and deformation of the beads occur.

The metal gasket 90 shown in FIGS. 14 and 15 can improve the sealing performance at the meeting portion 96 and its vicinity, but the bead 98 between the meeting portions 96 and 96 can be improved.
Since the distance becomes long, when used for a long time, the sealing performance due to the settling of the bead 98 and the balance between the characteristics of the bead 98 and the rigidity of the cylinder head cannot necessarily be maintained well over the entire region of this distance.

Furthermore, regarding the metal gasket 100 shown in FIGS. 16 and 17, there is an idea to partially change the height of the bead 103 around the cylinder bore hole, but only the bead located between the cylinder bore holes. However, the idea of changing the height of the bead in order to increase the rigidity of the bead is not disclosed. Furthermore, it is not possible to accurately follow changes in the temperature of the cylinder head, etc., and there is no substantial improvement in terms of improving bead characteristics. When the spacer 104 is formed by welding, defects are likely to occur in the welded portion, which poses a problem in the durability of the metal gasket. Furthermore, since it is necessary to ensure accuracy in the position and thickness of the spacer 104, the manufacturing cost increases significantly. Because it is extremely difficult to achieve high machining accuracy,
There is a problem in that it is difficult to optimize the surface pressure distribution between the cylinder bore holes, which is most important for sealing performance.

An object of the present invention is to solve the above-mentioned problem, and by only slightly changing the cross-sectional shape of the bead located between the cylinder bore holes of the bead plate, the cross-sectional shape of the bead other than between the cylinder bore holes, It compensates for the reduction in sealing performance due to deformation of parts with low rigidity, such as the port of the cylinder head or between the combustion chambers, and improves the sealing performance between cylinder bore holes compared to other parts without forming a grommet part on the metal plate. It also avoids sudden changes in the spring properties of the bead as seen in the composite bead, and allows for the best seal on the combustion chamber without adding a spacer to the bead to adjust the bead height. Ensures seals between the cylinder bore holes, which need to be securely sealed due to the possibility of combustion gas leakage, and prevents bead deformation or cracks even after long-term use in an environment where the tightening load based on the combustion cycle fluctuates. It is an object of the present invention to provide a metal gasket which can avoid the occurrence of this problem and reduce costs.

A further object of the present invention is to reduce the surface pressure itself acting on the metal gasket between the cylinder bore holes when the cylinder head is tightened against the cylinder block, regardless of whether or not the beads meet between the cylinder bore holes. It is an object of the present invention to provide a metal gasket which has excellent sealing properties, maintains the balance of the surface pressure, and also prevents cracks in the grommet part when a grommet part is formed.

[0019]

[Means for Solving the Problems] In order to achieve the above object, the present invention is constructed as follows. That is, the present invention provides a metal gasket having an elastic metal bead plate arranged between opposing surfaces of a cylinder head and a cylinder block and having beads formed along the circumferences of parallel cylinder bore holes for sealing between the opposing surfaces. The spring characteristics of the bead formed on the bead plate are determined by changing the spring stiffness of the bead located between the cylinder bore holes to a bead part with high spring stiffness located between the cylinder bore holes through a bead part where the spring stiffness smoothly decreases. This invention relates to a metal gasket characterized by a continuous transition to a low bead.

Further, in this metal gasket, each of the bead portions located other than between the adjacent cylinder bore holes meets one of the bead portions located between the cylinder bore holes in a smoothly curved shape, and the cylinder bore The width of the bead portion located other than between the holes is formed to be wider than the width of the bead portion located between the cylinder bore holes.

Furthermore, in this fuel injection nozzle, a metal sub-plate is laminated on the bead plate, and a peripheral edge of the cylinder bore hole of the sub-plate is folded back toward the bead plate to form a grommet portion. .

[0022]

[Operation] The metal gasket according to the present invention is constructed as described above and functions as follows. That is, in the metal gasket according to the present invention, the spring characteristics of the bead are changed from the bead portion with high spring stiffness located between the cylinder bore holes to the bead portion where the spring stiffness smoothly decreases, and the spring stiffness located outside the cylinder bore holes is reduced. Since the bead part is continuously changed to a low bead, when the cylinder head is tightened to the cylinder block, the cylinder bore hole, that is, the area around the combustion chamber hole is the most important part for sealing combustion gas, but the rigidity of the cylinder head is The tightening force is largely distributed between the cylinder bore holes, where the spring stiffness is likely to decrease, and the bead portion has a higher spring rigidity than the other portions, which provides a strong seal.

[0023] In this metal gasket, each bead portion located outside of the area between adjacent cylinder bore holes meets one bead portion located between the cylinder bore holes in a smoothly curved shape; Since the width of the bead portion is formed to be wider than the width of the bead portion located between the cylinder bore holes, a flat portion is added by meeting in a smooth curved shape, and the bead portion is expanded by the amount of the flat portion. It becomes easier to bend. That is, when the cylinder head is tightened to the cylinder block, the bead deforms as if it were crushed, but the magnitude of the resistance, that is, the rigidity, is lowered if the chevron-shaped top of the bead portion is flat. Therefore, when viewed from the bead side between the cylinder bore holes,
Its rigidity is higher than the spring characteristics of the bead portions other than between the cylinder bore holes.

Furthermore, in this metal gasket, the bead portions other than those between adjacent cylinder bore holes are composed of curved portions whose cross-sectional shape has a gentler bend than the bead portion located between the cylinder bore holes, and the bead width is If the bead is wider than the bead between the cylinder bore holes, the bead height is the same, so the larger the radius of curvature, the gentler the bending becomes, and the easier it is to bend. Therefore, the bead located between the cylinder bore holes has a smaller radius of curvature and is bent more steeply than the bead located between the cylinder bore holes, so a large bending stress is required for deformation, and the rigidity of the cylinder bore is The spring characteristics are higher than those of the bead portions other than between the holes.

In addition, in this metal gasket, the bead formed along the periphery of the cylinder bore hole is formed between adjacent cylinder bore holes regardless of whether or not the bead portions along the periphery of the cylinder bore hole meet. The rigidity can be made higher than that of the bead portion located at a portion other than the gap. When they do not meet, each bead portion performs a sealing function around each cylinder bore hole. If the bead parts meet on both sides of the line connecting the centers of the cylinder bore holes, and one bead part is formed between the two meeting parts, such a common bead part will have a sealing function for the adjacent cylinder bore holes. Fulfill. When a sub-plate is laminated on the bead plate, the peripheral edge of the cylinder bore hole of the sub-plate can be folded back toward the bead plate to form a grommet part. In this case, the thickness of the metal gasket of the grommet part is It can also have a compensation function, a function to reduce excessive load on the bead, and a stopper function against crushing deformation of the bead.

[0026]

Embodiments Hereinafter, embodiments of the metal gasket according to the present invention will be described with reference to the drawings. 1 to 3 are diagrams showing one embodiment of a metal gasket according to the present invention. FIG. 1 is a plan view showing a relatively wide area of a metal gasket. FIG. 2 is a sectional view showing a cross section of the bead along line A-A on the line connecting the centers of adjacent cylinder bore holes in FIG. FIG. 3 is a sectional view showing a cross section of the bead along the radial line B-B in a region other than between the cylinder bore holes.

As shown in FIG. 1, a metal gasket 10 is disposed between opposing surfaces between a cylinder head and a cylinder block in a multi-cylinder engine and is used to seal the periphery of a combustion chamber. . The metal gasket 10 is mainly composed of a bead plate 11. For example, the upper plate and the lower plate are each constituted by a bead plate 11, and the secondary plate 12, which is a flat middle plate, is interposed between the upper plate and the lower plate, and the bead 13 of the bead plate 11 is brought into contact with the middle plate. Configure it into a specific structure. The thickness of the bead plate 11 is about 0.20 mm, and the bead plate 11 is made of a stainless steel spring plate made of SUS301 or the like. The metal gasket 10 is formed with a cylinder bore hole 14, which corresponds to a cylinder bore formed in a cylinder block. Furthermore, in order to insert the bolts that connect and tighten the cylinder block and cylinder head,
A plurality of bolt holes 3 are drilled. Furthermore, this metal gasket 10 is provided with a plurality of water holes 4 through which cooling water passes, riveting holes 5, etc., but these holes such as bolt holes are similar to those formed in conventional metal gaskets. It is.

In FIG. 1, a bead 13 is formed on the bead plate 11 around the cylinder bore hole 14. As shown in FIG. The height h of the bead 13 (see FIGS. 2 and 3) is, for example, about 0.2 mm. The sub-plate 12 is made of, for example, a stainless steel plate such as SUS304.The outline of the cylinder bore hole 14 is as follows.
The curvature is made small in the area between 14 and 14. The beads 13, 13 on both sides meet between the cylinder bore holes 14, 14 to form a meeting portion 16. The meeting portions 16, 16 on both sides (upper and lower in the figure) are connected to one bead portion 13Y, and the bead portion 13Y is common to the adjacent cylinder bore holes 14, 14.

Regarding the bead 13, an example of a configuration for increasing the rigidity of the bead portion 13Y located in the region Y between the cylinder bore holes compared to the rigidity of the bead portion 13Z located in the region Z other than between the cylinder bore holes is shown in FIG. 2 and 3. That is, the area Y between the cylinder bore holes 14, 14
As shown in FIG. 2, the cross-sectional contour of the bead 13 is a bead portion 13Y whose cross section is a smooth curve with no flat portion in the free state of the metal gasket.
The width La of Y is 2.1 mm. On the contrary,
In the region Z other than between the cylinder bore holes 14, 14, as shown in FIG. 3, when the metal gasket is in a free state, the cross-sectional outline of the bead 13 is such that the flat center portion 13c cuts into the chevron-shaped top and is connected. It has a shape. The contours on both sides of the flat central portion 13c are the same as the contour of the bead portion 13Y in the region Y between the cylinder bore holes 14, 14 shown in FIG. Therefore, the width Lb of the bead portion 13Z in the region Z is 2.6 mm, which is wider than the width La. Therefore, the rigidity of the bead portion 13Y in region Y, that is, the resistance to crushing when the cylinder head is tightened against the cylinder block, is
It becomes higher than the rigidity of Z. As an example, when the cylinder bore diameter is 95 mm, the length of region Y is 30 mm, and the length of region X is 5 mm.

FIG. 4 is a plan view of another embodiment of the metal gasket according to the present invention in the area between the cylinder bore holes. The basic configuration of the metal gasket 20 is almost the same as that of the conventional example shown in FIGS. 14 and 15, and the definitions of the bead lines 23a, 27a of the bead plate 21 and the bead outline lines 23b, 27b are also the same. . Also in this embodiment, regarding the bead 23 formed on the bead plate 21, the width of the bead portion 23Z in the region Z beyond the joining portion 26 is 2.6 mm, and regarding the bead 27 that has joined into one, the width of the bead portion 23Z in the region Z beyond the joining portion 26 is 2.6 mm. , 26 is wider than the width of the bead portion 23Y in the region Y between the regions Y. Therefore, the rigidity of the bead portion 23Y is higher than that of the other bead portions 23Z. The bead portion 23X of the bead region X is a portion of the bead 23 where the rigidity changes, as in the case of FIG. The cross-sectional shapes of the bead portions 23Y and 23Z are similar to those in the previous embodiment.

FIG. 5 is a plan view of another embodiment of the metal gasket according to the present invention in the area between the cylinder bore holes. The illustrated metal gasket 30 consists of a bead plate 31. The line indicated by a dashed line around the cylinder bore hole 34 is a bead line 33a that traces the top of the bead 33 formed on the bead plate 31.
Dotted lines 33b on both sides of a represent the bead outline. Regarding the bead 37, the dashed line 37a at the center represents the bead line, and the dotted lines on both sides thereof are the bead outline line 37b. In the bead plate 31, adjacent cylinder bore holes 34,
Beads 33, 33 formed around 34 are brought as close to each other as possible to form meeting parts 36, 36. Mainly, the bead portion 33Y between the meeting portions 36, 36 has higher rigidity than the bead portion 33Z in the portion other than between the cylinder bore holes. That is, the bead portion 33Y in region Y in FIG. 4 is formed to have higher rigidity than the bead portion 33Z in region Z. The bead portion 33X in the region X is a portion where the rigidity changes smoothly. Both ends of the region Y forming high rigidity are meeting parts 3
The area is not limited to 6 or 36, and the area may be slightly enlarged or reduced.

FIGS. 6, 7 and 8 are diagrams showing still another embodiment of the metal gasket according to the present invention. FIG. 6 is a partial plan view of the bead plate 41 of only the portion between the adjacent cylinder bore holes 44 of the metal gasket 40. As shown in FIG. FIG. 7 shows both cylinder bore holes 44 crossing the boundary between adjacent cylinder bore holes 44, 44.
, 44, as viewed in the direction of the arrow. FIG. 8 shows the cylinder bore hole 4 passing through the center of the cylinder bore hole 44.
4 is a partial cross-sectional view of the metal gasket 40 viewed in the direction of the arrow on the line DD on the line that crosses the portion other than between 4 and 44. FIG.

In the metal gasket 40 shown in FIGS. 6, 7, and 8, a bead 43 is formed on a bead plate 41 around a cylinder bore hole 44. As shown in FIG. Regarding the bead 43, a dashed line represents a bead line 43a, and a dotted line represents a bead outline 43b. Adjacent beads 43,4
3 is one point on the line B-B, and the bead outline lines 43b, 43b are in contact only at one point. As shown in the cross-sectional views of FIGS. 5 and 6, the height h of the bead 43 is
The width Lc of the bead portion 43Y in the area Y between the cylinder bore holes 44 and 44 is 2.1 mm, as shown by the bead outline lines 43b and 43b. The width Ld of the bead portion 43Z in the region Z other than between the cylinder bore holes 44 is 2.
6 mm, and the width Lc is narrower than the width Ld. Specifically, the radius of curvature of the arc defining the cross-sectional shape of bead portion 43Y in region Y is smaller than the radius of curvature of the arc defining the cross-sectional shape of bead portion Z in region Z. In the bead portion X of the region X transitioning from the region Y to the region Z, the bead width changes smoothly, and the rigidity of the bead portion X gradually changes. Therefore, the rigidity of the bead portion 43Y located in the region Y is high, and the rigidity of the bead portion 43Z located in the region Z is low.

[0034] In the embodiments of the metal gasket described above based on the drawings, if a secondary plate such as a middle plate is laminated in addition to the bead plate, the thickness of the secondary plate itself can be set arbitrarily, so shims can be used. In other words, the metal gasket also functions to fit the metal gasket into the gap between the cylinder head and the cylinder block, and improves the function of sealing between the opposing surfaces of the cylinder head and cylinder block. In addition, vibrations and tensile forces due to explosions occur between the cylinder head and cylinder block as the engine operates, but the secondary plate prevents lateral vibrations from acting only on the bead plate. Damage to the bead plate due to rubbing against the cylinder head or cylinder block is thereby avoided. Furthermore, vibrations or shocks in the vertical direction, that is, in the direction perpendicular to the surface of the bead plate, do not directly hit both sides of the bead plate from the cylinder head or cylinder block, so the sub plate has a kind of buffering effect on the bead plate. be.

In some cases, a grommet portion may be formed on the edge of the sub-plate on the side of the cylinder bore hole, but in that case, the grommet portion is folded back so as not to overlap the bead plate. The folding width of the grommet part can be set arbitrarily, and the distribution of surface pressure with respect to the bead can be adjusted. In this case, compared to the case where the bead plate is folded back to hold it, the grommet part does not act as a stopper to restrain the above deformation of the bead of the bead plate, but allows the above deformation of the bead, and the grommet part part is not affected by bead deformation during tightening. Furthermore, when forming the grommet portion of the sub-plate, it can be folded back with a soft member serving as a shim in between. The shims may be one continuous piece at the cylinder bore hole, or may be provided independently around each cylinder bore hole. Since the thickness at the grommet portion is increased by the soft member, the surface pressure distribution in the metal gasket can be appropriately corrected and the balance can be finely adjusted. The shim can also be expected to absorb vibrations generated between the cylinder head and cylinder block. In addition to the soft metal plate, the shim may also be made of a material having properties similar to those of a soft material such as a heat insulating graphite sheet, an aramid heater sheet, resin, or rubber.

[0036] In the metal gasket, the surface of the bead plate or other metal plate to be laminated is coated with a heat-resistant and oil-resistant material such as rubber or resin, for example, from 10μ to 50μ.
The coating may be applied to a thickness of , preferably 25μ. The coating may be applied to both sides of the bead substrate, or in some cases, it may be applied only to the contact surface between the cylinder head and the cylinder block. By applying such surface treatment, direct metal-to-metal contact with the cylinder head and cylinder block can be avoided, and the corrosion resistance and durability of the gasket can be improved, ensuring strength and sufficient strength. Can perform sealing function.

Although each embodiment of the present invention has been described with respect to a multi-cylinder internal combustion engine, the present invention is not limited to this type of internal combustion engine; for example, it is not limited to a four-cylinder engine,
It can also be applied to a six-cylinder engine, a V-type six-cylinder engine, etc.

[0038]

[Effects of the Invention] Since the metal gasket according to the present invention is constructed as described above, it has the following effects. That is, regarding the spring characteristics of the bead formed on the bead plate, this metal gasket has a bead portion located between the cylinder bore holes that has a high spring rigidity, and a bead portion where the spring rigidity smoothly decreases, and is located at a place other than between the cylinder bore holes. Since the spring rigidity changes continuously to the bead part, when the cylinder head is tightened to the cylinder block, the rigidity of the cylinder head is the most important part for sealing the combustion gas around the combustion chamber hole. The tightening force is largely distributed between the cylinder bore holes, where the spring stiffness is likely to decrease, and the spring stiffness is strongly sealed by the bead, which is higher than other parts. In this way, by simply changing the rigidity of the bead located between the cylinder bore holes of the bead plate continuously with the rigidity of the bead other than between the cylinder bore holes, low rigidity parts such as between the combustion chambers of the cylinder head can be deformed. This compensates for the reduction in sealing performance due to this, and also ensures the same sealing performance between the cylinder bore holes as with beads at other locations, without relying on the grommet portion of the metal gasket. Furthermore, it avoids the sudden change in the spring characteristics of the bead as seen in the composite bead, and eliminates the leakage of combustion gas on the seal of the combustion chamber without adding a spacer to the bead to adjust the bead height. It is necessary to securely seal the area between the cylinder bore holes because of the possibility of can be avoided.

[0039] In this metal gasket, the bead portion located outside of the area between adjacent cylinder bore holes is connected by inserting a flat central portion into the center apex of the bead portion located between the cylinder bore holes in its chevron-shaped cross section. By making the bead shape wider than the bead portion located between the cylinder bore holes, the bead portion becomes easier to bend due to the addition of the flat portion. Therefore, when viewed from the side of the bead between the cylinder bore holes, its rigidity is higher than the spring characteristics of the bead portion other than between the cylinder bore holes. Furthermore, in this metal gasket, the bead portions other than between the adjacent cylinder bore holes are composed of curved portions whose cross-sectional shape has a gentler bend than the bead portion located between the cylinder bore holes, and the bead width is formed between the cylinder bore holes. If the width is wider than the bead portion, the bead height is the same, so the larger the radius of curvature, the gentler the bending becomes, and the easier it is to bend. therefore,
The bead portion located between the cylinder bore holes has stronger resistance to bending, that is, has higher rigidity, than the bead portion located other than between the cylinder bore holes. In either case, the rigidity of the bead can be changed by simply changing the cross-sectional shape of the bead at the time of formation, and the bead can be manufactured at low cost.

Furthermore, this metal gasket can be applied regardless of whether or not the beads along the periphery of the cylinder borehole meet between adjacent cylinder boreholes of the bead plate, and is highly versatile. In addition, this metal gasket can be applied not only to bead plates but also to those that have a sub-plate laminated to the bead plate, ensuring the surface pressure itself acting on the metal gasket between the cylinder bore holes and maintaining the balance of the surface pressure. be able to. In some cases, when a grommet portion is formed on the sub-plate, it is possible to provide a metal gasket with excellent sealing properties while still performing the function of the grommet portion.

[Brief explanation of the drawing]

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

FIG. 2 is a partial sectional view taken along line A-A, which is a line connecting the centers of adjacent cylinder bore holes of the metal gasket shown in FIG. 1;

FIG. 3 is a partial cross-sectional view of the metal gasket shown in FIG. 1 along line BB in a region other than between the cylinder bore holes.

FIG. 4 is a partial plan view showing a portion between cylinder bore holes of another embodiment of the metal gasket according to the present invention.

FIG. 5 is a partial plan view showing a portion between cylinder bore holes of still another embodiment of the metal gasket according to the present invention.

FIG. 6 is a partial plan view showing a portion between cylinder bore holes of another embodiment of the metal gasket according to the present invention.

7 is a partial cross-sectional view taken along line CC on a line connecting the centers of adjacent cylinder bore holes of the embodiment of the metal gasket shown in FIG. 6; FIG.

8 is a partial cross-sectional view of the embodiment of the metal gasket shown in FIG. 6 along line DD in a region other than between the cylinder bore holes.

FIG. 9 is a partial plan view showing an example of a conventional metal gasket.

10 is a cross-sectional view of the metal gasket shown in FIG. 9 along line EE.

FIG. 11 is a partial plan view showing another example of a conventional metal gasket.

FIG. 12 is a partial plan view showing yet another example of a conventional metal gasket.

FIG. 13 is a partial plan view showing another example of a conventional metal gasket.

FIG. 14 is a partial plan view showing still another example of a conventional metal gasket.

FIG. 15 is an enlarged view of a part of the metal gasket shown in FIG. 14;

FIG. 16 is a partial cross-sectional view showing another example of a conventional metal gasket.

FIG. 17 is a partial cross-sectional view showing an example of a conventional metal gasket similar to FIG. 16;

[Explanation of symbols]

10 Metal gasket 11 Bead plate 13 Bead 14 Cylinder bore hole 16 Meeting Department 17 Bead between meeting parts 20 Metal gasket 21 Bead plate 23 Bead 24 Cylinder bore hole 26 Meeting Department 27 Bead between meeting parts 30 Metal gasket 31 Bead plate 33 Bead 36 Meeting Department 37 Bead between meeting parts 40 Metal gasket 41 Bead plate 43 Bead 44 Cylinder bore hole 46 Meeting Department

Claims (3)

[Claims] 1. A metal gasket having an elastic metal bead plate disposed between opposing surfaces of a cylinder head and a cylinder block and having beads formed along the periphery of parallel cylinder bore holes for sealing between the opposing surfaces, The spring characteristics of the bead formed on the bead plate are determined by changing the spring stiffness of the bead located between the cylinder bore holes to a bead part with high spring stiffness located between the cylinder bore holes through a bead part where the spring stiffness smoothly decreases. A metal gasket characterized by a continuous transition to a low bead. 2. Each of the bead portions located at a position other than between the adjacent cylinder bore holes meets one of the bead portions located between the cylinder bore holes in a smoothly curved shape, 2. The metal gasket according to claim 1, wherein the width of the bead portion is wider than the width of the bead portion located between the cylinder bore holes. 3. A metal sub-plate is laminated on the bead plate, and a peripheral edge of the cylinder bore hole of the sub-plate is folded back toward the bead plate to form a grommet portion. Metal gasket as described.