Steel laminate gasket with wide sealing area

A steel laminate gasket of the invention is installed in an internal combustion engine having at least one hole therein. The gasket comprises a first plate having at least one first hole therein corresponding to the hole of the engine, and a second plate having at least one second hole. The first plate is provided with a base portion, at least one curved portion adjacent the first hole, and at least one flange situated parallel to the base portion. The base portion, curved portion and flange are integrally formed together. At least one side wall is formed on one of the base portion and the flange adjacent the curved portion to surround the first hole. The thickness between the flange and base portion inside the side wall is greater than the thickness between the flange and base portion outside the side wall so that an embossed portion is formed around the first hole. The second plate is situated adjacent the first plate so that the second plate does not pile the flange of the first plate.

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT 
The present invention relates to a steel laminate gasket for an internal 
combustion engine, which can provide wide and high sealing pressure to 
securely seal around a hole. 
The steel laminate gasket of the present invention may be used widely, such 
as a regular gasket situated between two engine blocks, cylinder head 
gasket and manifold gasket. When the gasket of the present invention is 
used as a cylinder head gasket, the gasket may seal around cylinder holes 
Hc, water holes Hw, oil holes Ho, bolt holes Hb and the like, as shown in 
FIG. 1. However, it is preferably to seal around a relatively large hole, 
such as a cylinder hole Hc. 
In a gasket, a main subject of a gasket is to securely seal around a hole. 
Therefore, when a gasket is designed, attention has been paid how a 
portion around a hole is securely sealed. In this respect, there have been 
proposed many methods. 
One of conventional methods to seal around a hole is to form a bead around 
a hole. As shown in FIG. 2, for example, a gasket 20 comprises an upper 
plate 21, a lower plate 23, and a middle plate 22 having a bead 22a around 
a cylinder hole Hc. In the gasket 20, the bead 22a only provides a sealing 
pressure around the cylinder hole Hc. Therefore, fluid passing through the 
hole Hc may permeate through the plates. The sealing ability of the gasket 
20 is not good. 
In view of the prior art, a gasket 25 as shown in FIG. 3 has been proposed 
in Ser. No. 193,215 filed on May 11, 1988. The gasket 25 comprises an 
upper plate 26 with a curved portion 26a and a flange 26b, and a lower 
plate 27. The gasket 25 can securely seal around the hole Hc. However, 
since an area around the hole Hc is only sealed by the curved portion 26a, 
the sealing area that forms sealing pressure is relatively narrow. 
Further, since the curved portion may strongly abut against the engine 
blocks, in case the engine blocks are formed of aluminum alloy, the engine 
blocks may deform at the curved portion. Therefore, a gasket with 
relatively wide sealing area without affecting the engine blocks has been 
desired. 
Accordingly, one object of the present invention is to provide a steel 
laminate gasket, which can provide wide and high sealing pressure around a 
hole to be sealed. 
Another object of the present invention is to provide a steel laminate 
gasket as stated above, which does not cause any damage to portions 
abutting against the gasket. 
A further object of the present invention is to provide a steel laminate 
gasket as stated above, which can be easily and economically manufactured. 
Further objects and advantages of the invention will be apparent from the 
following description of the invention. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a steel laminate gasket is 
designed to be installed in an internal combustion engine having at least 
one hole therein. The gasket comprises a first plate having at least one 
first hole corresponding to the hole of the engine, and a second plate 
situated adjacent to the first plate. 
The first plate is provided with a base portion, at least one curved 
portion for defining the first hole, and a flange located above the base 
portion. The curved portion and flange are integrally formed with the base 
portion. The first plate is further provided with at least one side wall 
formed on either the base portion or the flange adjacent the curved 
portion to surround the first hole. The side wall may be formed diagonally 
or perpendicularly relative to the base portion or the flange that the 
side wall is not formed. 
The thickness between the flange and base portion inside the side wall is 
greater than the thickness between the flange and base portion outside the 
side wall. Therefore, an area around the first hole surrounded by the side 
wall and the curved portion forms an embossed portion. 
The embossed portion is substantially flat and parallel to the base portion 
or the flange facing against the embossed portion. When the gasket is 
tightened, the embossed portion forms a plurality of corrugated beads 
thereat to thereby securely seal around the first hole. 
The second plate is situated at a flange side of the first plate and is 
provided with at least one second hole therein. The diameter of the second 
hole is larger than the outer diameter of the flange. Therefore, when the 
first and second plates are assembled, the flange is located inside the 
second hole. 
In the gasket of the invention, outer plates may be formed to protect the 
first and second plates. Further, a plate having a bead may be installed 
between the first and second plates, wherein the bead is located under the 
embossed portion.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring to FIGS. 4 and 5, a first embodiment A of a steel laminate gasket 
of the present invention is shown. The gasket A as shown in FIGS. 4 and 5 
is a cylinder head gasket, similar to FIG. 1, and is provided with a 
plurality of holes, i.e. cylinder holes Hc, water holes Hw, oil holes Ho 
and bolt holes Hb. Areas around the cylinder holes Hc are sealed in 
accordance with the present invention. However, if required, areas around 
the water holes Hw, oil holes Ho and bolt holes Hb may be sealed as well. 
The gasket A comprises an upper plate A30, and a lower plate A31 situated 
under the upper plate A30. The upper plate A30 is provided with a base 
portion A30a extending substantially throughout the entire area of the 
gasket, a diagonal side wall A30b extending diagonally and upwardly from 
the base portion A30a around the cylinder hole Hc, and an embossed portion 
A30c. The upper plate A30 also includes a curved portion A30d around the 
cylinder hole Hc to define the same, and a flange A30e situated under the 
embossed portion A30c. 
The flange A30e is spaced apart from the embossed portion A30c and is 
situated parallel thereto, so that a space is formed between the flange 
A30e and the embossed portion A30c. An end portion of the flange A30e is 
located under the base portion A30a. 
When the upper plate A30 is formed, the embossed portion A30c is treated at 
first. Namely, the diagonal side wall A30b is formed, and then an upper 
edge of the curved portion A30d is bent. The upper edge of the curved 
portion may be bent before the diagonal side wall A30b is formed. Then, 
the flange A30e is turned to be located under the embossed portion A30c, 
whereby the curved portion A30d is formed. 
The lower plate A31 is a flat plate situated under the base portion A30a of 
the upper plate A30. The lower plate A31 is provided with a hole A32. The 
diameter of the hole A32 is larger than the outer diameter of the flange 
A30e. 
When the gasket A is assembled, the lower plate A31 is situated under the 
upper plate A30 so that the flange A30e is located in the hole A32. The 
lower plate A31 does not pile on the flange A30e. 
When the gasket A thus assembled is situated between a cylinder head X and 
a cylinder block Y and is tightened therebetween as shown in FIG. 5, the 
embossed portion A30c is compressed. Since the embossed portion A30c is 
surrounded by the diagonal side wall A30b and the curved portion A30d, the 
tightening pressure is concentrated at the embossed portion A30c. As a 
result, a plurality of corrugated beads are formed on the embossed portion 
A30c. 
In the gasket A, since the embossed portion A30c surrounded by the diagonal 
side wall A30b and the curved portion A30d is relatively wide, relatively 
wide sealing pressure is formed around the cylinder hole Hc. Namely, the 
sealing pressure is not concentrated at a narrow area and is evenly spread 
around the embossed portion A30c. As a result, the sealing characteristics 
are sufficiently improved. Also, the cylinder head is not damaged by the 
corrugated beads. 
FIG. 6 shows a second embodiment B of a steel laminate gasket of the 
present invention. The gasket B comprises a plate B30 with an embossed 
portion B30c and a flange B30e, and a plate B31, similar to the gasket A. 
However, a diagonal side wall B30b is formed to bend gently relative to a 
base portion B30a and the embossed portion B30c. Since the diagonal side 
wall B30b is curved gently, it is possible to reduce metal fatigue formed 
at the plate B30 when the diagonal side wall B30b is formed. As a result, 
durability at the diagonal side wall B30b is improved. Moreover, the 
gasket B is provided with an upper outer plate B33, and a lower outer 
plate B34. 
The upper outer plate B33 is provided with an opening corresponding to the 
cylinder hole Hc and is situated above the plate B30. The lower outer 
plate B34 is provided with an opening corresponding to the cylinder hole 
Hc and is situated under the plate B31. In the gasket B, durability is 
improved. Also, the gasket B is useful when a thick gasket is required. 
FIG. 7 shows a third embodiment C of a steel laminate gasket of the present 
invention. The gasket C comprises an upper plate C30 with an embossed 
portion C30c and a flange C30e, and a lower plate C31, similar to the 
gasket A. In the gasket C, the thickness of the upper plate C30 is thicker 
than that of the lower plate C31. As a result, high sealing pressure is 
obtained around the cylinder hole Hc. The gasket C is useful where high 
sealing pressure is required. 
FIG. 8 shows a fourth embodiment D of a steel laminate gasket of the 
present invention. The gasket D comprises an upper plate D30 with a hole 
D32, and a lower plate D31 situated under the upper plate D30. The lower 
plate D31 is provided with a curved portion D31d, and a flange D31e 
wherein a diagonal side wall D31b and an embossed portion D31c are formed. 
Namely, while the gasket A is provided with the embossed portion A30c on 
the base portion A30a, in the gasket D, the embossed portion D31c is 
formed on the flange D31e. 
When the gasket D is assembled, the flange D31e is located in the hole D32 
of the upper plate D30. The embossed portion D31c slightly projects 
outwardly from the upper surface of the upper plate D30. The gasket D 
operates as in the gasket A. 
FIG. 9 shows a fifth embodiment E of a steel laminate gasket of the present 
invention. The gasket E comprises a plate E30 with an embossed portion 
E30c and a flange E30e, and a plate E31, similar to the gasket A. However, 
the gasket E further includes an upper outer plate E33, a lower outer 
plate E34, and a plate E35 situated between the lower outer plate E34 and 
the plate E31. 
The upper outer plate E33 is provided with a curved portion E33a to define 
the cylinder hole Hc, and a flange E33b situated under a part of the lower 
outer plate E34. Namely, the plates E30, E31 are completely covered by the 
outer plates E33, E34. The gasket E is useful in case a thick gasket is 
required. 
FIG. 10 shows a sixth embodiment F of a steel laminate gasket of the 
present invention. The gasket F comprises an upper plate F30 with an 
embossed portion F30c and a flange F30e, and a lower plate F31, similar to 
the gasket A. However, the gasket F further includes a middle plate F36 
situated between the upper plate F30 and the lower plate F31. 
The middle plate F36 is provided with a bead F36a around the cylinder hole 
Hc under the embossed portion F30c to support the same. Therefore, when 
the gasket F is tightened, the embossed portion F30c, especially the 
center of the embossed portion F30c, is supported by the bead F36a to 
thereby provide a high sealing pressure. The gasket F is useful in case 
high sealing pressure is required. 
FIG. 11 shows a seventh embodiment G of a steel laminate gasket of the 
present invention. The gasket G comprises a plate G30 with an embossed 
portion G30c and a flange G30e, a plate G31, and a plate G36 with a bead 
G36a, similar to the gasket F. However, the gasket G further includes an 
upper outer plate G33 situated above the plate G30, a lower outer plate 
G34 situated under the plate G31, and a plate G37 situated between the 
plate G33 and the plate G30. The plate G37 operates as a surface pressure 
regulation plate for the embossed portion G30c and the bead G36a. 
The upper outer plate G33 is provided with a curved portion G33a to define 
the cylinder hole Hc, and a flange G33b situated under a part of the lower 
outer plate G34. Namely, the plates G30, G31 are completely covered by the 
plates G33, G34. The gasket G is useful in case a thick gasket with high 
sealing pressure is required. 
FIG. 12 shows an eighth embodiment H of a steel laminate gasket of the 
present invention. The gasket H comprises an upper plate H30 with an 
embossed portion H30c and a flange H30e, and a lower plate H31, similar to 
the gasket A. In the gasket H, however, the upper plate H30 is provided 
with a vertical side wall H30b. Since the vertical side wall H30b is 
stronger than a diagonal side wall, e.g. A30b, against a vertical pressure 
applied thereto, the embossed portion H30c can provide a strong sealing 
pressure when the gasket H is tightened. The gasket H is useful when high 
sealing pressure is required. 
In the present invention, the gasket is basically provided with a first 
plate having a relatively wide embossed portion around a hole to be 
sealed, and a second plate situated at a flange side of the first plate. 
Since the embossed portion, when compressed, forms a plurality of 
corrugated beads, a relatively wide and strong sealing pressure is 
obtained. Therefore, an area around the hole is securely sealed by the 
embossed portion. 
When a bead is situated under the embossed portion, the embossed portion is 
supported by the bead. As a result, a part of the embossed portion 
supported by the bead provides a strong sealing pressure thereat. In the 
present invention, it is possible to regulate the sealing pressure by the 
combination of the embossed portion and the supporting bead. 
While the invention has been explained with reference to the specific 
embodiments of the invention, the explanation is illustrative and the 
invention is limited only by the appended claims.