U.S. patent application number 09/795495 was filed with the patent office on 2001-10-04 for laminated gasket.
This patent application is currently assigned to NIPPON GASKET COMPANY LTD.. Invention is credited to Sugimoto, Kiyoshi, Uemura, Hiroshi, Yoshijima, Kazuya.
Application Number | 20010026047 09/795495 |
Document ID | / |
Family ID | 18614392 |
Filed Date | 2001-10-04 |
United States Patent
Application |
20010026047 |
Kind Code |
A1 |
Uemura, Hiroshi ; et
al. |
October 4, 2001 |
Laminated gasket
Abstract
A laminated gasket is provided, which ensures desired bore
sealing surface pressures on the side of a cylinder head and on the
side of a cylinder block, which is excellent in sealing ability and
durability preferably by virtue of its double sealing function and
which has a comparatively simple structure. This gasket has a core
plate and elastic plates laminated to both surfaces of the core
plate. The core plate has thin-walled portions each surrounding a
bore opening and a thick-walled portion extending outwardly from
each thin-walled portion. The elastic plates respectively have
folded-back portions each of which is formed so as to create,
together with a base portion, a clearance around its associated
bore opening.
Inventors: |
Uemura, Hiroshi; (Osaka,
JP) ; Sugimoto, Kiyoshi; (Osaka, JP) ;
Yoshijima, Kazuya; (Okazaki-shi, JP) |
Correspondence
Address: |
ARENT FOX KINTNER OLOTKIN & KAHN, PLLC
1050 Connecticut Avenue, N.W., Suite 600
Washington
DC
20036-5339
US
|
Assignee: |
NIPPON GASKET COMPANY LTD.
|
Family ID: |
18614392 |
Appl. No.: |
09/795495 |
Filed: |
March 1, 2001 |
Current U.S.
Class: |
277/594 |
Current CPC
Class: |
F16J 2015/0862 20130101;
F16J 2015/0856 20130101; F16J 15/0825 20130101; F16J 2015/0843
20130101 |
Class at
Publication: |
277/594 |
International
Class: |
F02F 011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 3, 2000 |
JP |
2000-100148 |
Claims
What is claimed is:
1. A laminated gasket which has a core plate and elastic plates
laminated to both surfaces of the core plate, wherein the core
plate has thin-walled portions each of which surrounds a bore
opening and a thick-walled portion extending outwardly from the
thin-walled portions, and wherein each of the elastic plates has
(a) folded-back portions each of which is formed so as to create,
together with a base portion, a clearance around its associated
bore opening and (b) beads each of which is formed outside its
associated folded-back portion.
2. A laminated gasket according to claim 1, in which each of the
thin-walled portions is an inclined thin-walled portion which
gradually becomes thinner toward its associated bore opening and in
which the folded-back portions and beads of the elastic plates are
in contact with their associated inclined thin-walled portion.
3. A laminated gasket according to claim 1, in which each of the
thin-walled portions is a step-like thin-walled portion formed by
thinning a part on the side of each bore opening and in which the
folded-back portions of the elastic plates are in contact with
their associated step-like thin-walled portion whereas the beads of
the elastic plates are in contact with the thick-walled
portion.
4. A laminated gasket which has a core plate and elastic plates
laminated to both surfaces of the core plate, wherein the core
plate has thin-walled portions each of which surrounds a bore
opening and a thick-walled portion extending outwardly from the
thin-walled portions, and wherein each of the elastic plates has
(a) folded-back portions each of which is formed so as to create,
together with a base portion, a clearance around its associated
bore opening and (b) seal portions each of which is made of a soft
sealing material and positioned outside its associated folded-back
portion.
5. A laminated gasket according to claim 4, in which each of the
thin-walled portions is an inclined thin-walled portion which
gradually becomes thinner toward its associated bore opening and in
which the folded-back portions of the elastic plates are in contact
with their associated inclined thin-walled portion.
6. A laminated gasket according to claim 4, in which each of the
thin-walled portions is a step-like thin-walled portion which is
formed by thinning a part on the side of each bore opening and in
which the folded-back portions of the elastic plates are in contact
with their associated step-like thin-walled portion.
7. A laminated gasket which has a core plate and elastic plates
laminated to both surfaces of the core plate, wherein the core
plate has (a) thin-walled portions each of which surrounds a bore
opening, (b) a thick-walled portion extending outwardly from the
thin-walled portions and (c) seal portions made of a soft sealing
material and formed on the thin-walled portions and/or the
thick-walled portion, and wherein each of the elastic plates has
folded-back portions each of which is formed so as to create,
together with a base portion, a clearance around its associated
bore opening.
8. A laminated gasket according to claim 7, in which each of the
thin-walled portions is an inclined thin-walled portion which
gradually becomes thinner toward its associated bore opening and in
which the folded-back portions of the elastic plates are in contact
with their associated inclined thin-walled portion.
9. A laminated gasket according to claim 7, in which each of the
thin-walled portions is a step-like thin-walled portion which is
formed by thinning a part on the side of each bore opening, in
which the folded-back portions of the elastic plates are in contact
with their associated step-like thin-walled portion, and in which
the radial length of the base portions of the elastic plates is
within the range equal to the radial length of the step-like
thin-walled portions and the elastic plates are not in contact with
the thick-walled portion of the core plate.
10. A laminated gasket according to claim 7, in which each of the
thin-walled portions is a step-like thin-walled portion which is
formed by thinning a part on the side of each bore opening, in
which the folded-back portions of each elastic plate are in contact
with their associated step-like thin-walled portion, and in which
the base portion of each elastic plate holds an end of the
step-like thin-walled portion and the elastic plates are not in
contact with the thick-walled portion of the core plate.
Description
TECHNICAL FIELD
[0001] The present invention relates to laminated gaskets used for
providing seals, for example, between the opposed surfaces of the
cylinder block and cylinder head of an engine.
BACKGROUND ART
[0002] For sealing the joint between the opposed surfaces of the
cylinder block and cylinder head of an engine, there have been
widely used gaskets composed of elastic metal plates. Such
laminated gaskets are often designed such that elastic metal plates
having beads or folded-back portions are laminated to another
structural plate in order to enhance a sealing effect particularly
in the areas around the peripheries of bore openings.
[0003] For producing lightweight and small-sized engines, there are
two concurrent noticeable tendencies in the recent development of
engines. One is a trend toward making all of the structural members
of an engine from aluminum alloys and the other is a trend toward
higher combustion pressure for seeking higher output, higher
performance engines. Although more lightweight cylinder heads and
cylinder blocks etc. can be produced from aluminum alloys, compared
to cases where iron materials are used, the use of aluminum alloys
disadvantageously provides poor rigidity which causes considerable
deformation in the cylinder head and the cylinder block when
clamping the cylinder head gasket, so that it becomes difficult to
obtain uniform static sealing surface pressure around the
peripheries of the bore openings. In addition, during an operation
of the engine, the relative displacement of the cylinder head and
the cylinder block is increased by high pressure within the
cylinders and heat, which leads to difficulty in achieving uniform
dynamic sealing surface pressure.
[0004] To solve this problem, the following cylinder head gaskets
have been proposed and put to practical use, which have structures
of high freedom to conform to slips and deformation occurring
around the peripheries of the bore openings.
[0005] (1) Japanese Patent Publication (KOKAI) No. 63-101575
(1988)
[0006] This publication discloses a gasket having a structure in
which a plate, which has beads and folded-back portions including
comparatively large clearances, is overlaid on another structural
plate.
[0007] (2) Japanese Utility Model Publication (KOKAI) No. 1-118147
(1989)
[0008] This publication discloses a gasket having a structure in
which a plate has folded-back portions having .alpha.-shaped
clearances around a bore opening and a bead, and another plate is
placed so as not to overlap with the folded-back portions.
[0009] (3) Japanese Utility Model Publication (KOKAI) No. 4-66457
(1992), Japanese Patent Publication (KOKAI) No. 5-52268 (1993)
[0010] These publications disclose a gasket having a
four-plate-structure in which a first intermediate plate having
folded-back stoppers and a second intermediate plate having
step-like stoppers are sandwiched between two bead plates. The
folded-back stoppers for preventing entire bead compression are
formed only on a side of either of the bead plates.
[0011] (4) Japanese Patent Publication (KOKAI) No. 10-61773
(1998)
[0012] This publication discloses a structure in which bead plates
are laminated to both sides of an intermediate plate and thickness
increasing stopper portions made from a sintered material are
formed on the bead plates.
[0013] These conventional gaskets have, however, revealed the
following disadvantages. The gasket of column (1) has a problem in
its conformability to the deformation of the cylinder head and
cylinder block since the comparatively large clearance formed in
the folded-back portion is a grommet-like folded portion. Neither
of the gaskets described in columns (1) and (2) have an outer
laminated plate which directly contacts the folded-back portions
and they are in the form of a single layer at the parts around the
bore openings so that it is difficult to keep springiness and
therefore a surface pressure adjustment for bore sealing cannot be
easily performed.
[0014] In the gasket of the four-plate-structure described in
column (3), the distortion of the second intermediate plate having
the step-like stopper is virtually unexpected and the absence of
the distortion causes no problem in the performance of the gasket.
Therefore, virtually no effect of the folded-back stopper formed on
one side is transmitted through the thick, second intermediate
plate to the cylinder head surface or the cylinder block surface on
the opposite side. In case where the folded-back stopper is
positioned toward the cylinder block side, as a whole the gasket
when tightening and in use cannot follow the deformation occurring
on the cylinder head, or vice versa. It becomes therefore difficult
to simultaneously maintain desired sealing surface pressures on the
cylinder head side and on the cylinder block side. It should be
noted herein that where the cylinder block is made of cast iron
whereas the cylinder head is made of an aluminum alloy, deformation
can be dealt with in some degree which may be somehow insufficient
though, by appropriately adjusting the orientation of the gasket of
the four-plate-structure. However, the problems described above are
dominant in the case of engines entirely made of aluminum alloys
such as the latest open deck type engines.
[0015] In the gasket described in column (4), since the thickness
increasing stopper is made of a sintered material, increased costs
due to the material and the sintering process are unavoidable.
[0016] The invention has been directed to overcoming the foregoing
problems and it is therefore a prime object of the invention to
provide a laminated gasket of a comparatively simple structure, in
which desired bore sealing surface pressures on both of the
cylinder head side and the cylinder block side can be ensured by
use of elastic plates having at least folded-back portions formed
so as to follow the deformations of the cylinder head and the
cylinder block and in which excellent sealing ability and
durability can be achieved preferably by a double sealing
function.
DISCLOSURE OF THE INVENTION
[0017] The above object can be achieved by a laminated gasket
constructed according to a first aspect of the invention, which has
a core plate and elastic plates laminated to both surfaces of the
core plate,
[0018] wherein the core plate has thin-walled portions each of
which surrounds a bore opening and a thick-walled portion extending
outwardly from the thin-walled portions, and
[0019] wherein each of the elastic plates has (a) folded-back
portions each of which is formed so as to create, together with a
base portion, a clearance around its associated bore opening and
(b) beads each of which is formed outside its associated
folded-back portion.
[0020] According to the invention, since the folded-back portions
formed on the elastic plates are each formed so as to create a
clearance together with a base portion, the clearances can remain
as much as possible when the elastic plates are tightened between
the opposed surfaces of the cylinder head and the cylinder block,
so that bore seal lines can be formed by these folded-back
portions. In addition, a double seal structure composed of a first
seal provided by the folded-back portions formed on the elastic
plates and a second seal provided by the beads can be achieved and
thus, good sealing effects can be achieved with a relatively simple
structure. Since the thin-walled portions of the core plate allow
the folded-back portions having a clearance and formed on the
elastic plates to maintain springiness, the gasket can conform to
the deformation of the cylinder head or cylinder block when the
gasket is tightened or when the engine is operated. Additionally,
since the elastic plate is provided for both surfaces of the core
plate, even if deformation occurs from both of the cylinder head
side and the cylinder block side when the gasket is tightened, the
elastic plates flexibly receive the stresses so that surface
pressures on both sides can be distributed as desired. Further, the
gasket can easily follow the deformation of the cylinder head or
the cylinder block, exerting good sealing effects, during an
operation of the engine. Accordingly, a gasket having excellent
sealing ability and durability can be achieved.
[0021] The gasket of the invention may be structured such that each
of the thin-walled portions is an inclined thin-walled portion
which gradually becomes thinner toward its associated bore opening
and such that the folded-back portions and beads of the elastic
plates are in contact with their associated inclined thin-walled
portion. In such a structure, the folded-back portions of the
elastic plates can be allowed to maintain springiness by the
inclined thin-walled portions of the core plate when the gasket is
tightened or the engine is operated.
[0022] Alternatively, the gasket of the invention may be structured
such that each of the thin-walled portions is a step-like
thin-walled portion which is formed by thinning a part on the side
of each bore opening and such that the folded-back portions of the
elastic plates are in contact with their associated step-like
thin-walled portion whereas the beads of the elastic plates are in
contact with the thick-walled portion.
[0023] According to a second aspect of the invention, there is
provided a laminated gasket which has a core plate and elastic
plates laminated to both surfaces of the core plate,
[0024] wherein the core plate has thin-walled portions each of
which surrounds a bore opening and a thick-walled portion extending
outwardly from the thin-walled portions, and
[0025] wherein each of the elastic plates has (a) folded-back
portions each of which is formed so as to create, together with a
base portion, a clearance around its associated bore opening and
(b) seal portions each of which is made of a soft sealing material
and positioned outside its associated folded-back portion.
[0026] According to the invention, a double seal structure can be
achieved, which is composed of a first seal provided by the
folded-back portions formed on the elastic plates and a second seal
provided by the seal portions formed outside the folded-back
portions. With this arrangement, the same effect as obtained by the
first aspect can be achieved.
[0027] The invention may be arranged such that each of the
thin-walled portions is an inclined thin-walled portion which
gradually becomes thinner toward its associated bore opening and
such that the folded-back portions of the elastic plates are in
contact with their associated inclined thin-walled portion.
[0028] The invention may be alternatively arranged such that each
of the thin-walled portions is a step-like thin-walled portion
which is formed by thinning a part on the side of each bore opening
and such that the folded-back portions of the elastic plates are in
contact with their associated step-like thin-walled portion.
[0029] According to a third aspect of the invention, there is
provided a laminated gasket which has a core plate and elastic
plates laminated to both surfaces of the core plate,
[0030] wherein the core plate has (a) thin-walled portions each of
which surrounds a bore opening, (b) a thick-walled portion
extending outwardly from the thin-walled portions and (c) seal
portions made of a soft sealing material and formed on the
thin-walled portions and/or the thick-walled portion,
[0031] wherein each of the elastic plates has folded-back portions
each of which is formed so as to create, together with a base
portion, a clearance around its associated bore opening.
[0032] According to the invention, a double seal structure can be
achieved, which is composed of a first seal provided by the
folded-back portions formed on the elastic plates and a second seal
provided by the seal portions formed on the thin and/or
thick-walled portion of the core plate. With this arrangement, the
same effect as obtained by the first aspect can be achieved.
[0033] The invention may be arranged such that each of the
thin-walled portions is an inclined thin-walled portion which
gradually becomes thinner toward its associated bore opening and
such that the folded-back portions of the elastic plates are in
contact with their associated inclined thin-walled portion.
[0034] The invention may be alternatively arranged such that each
of the thin-walled portions is a step-like thin-walled portion
which is formed by thinning a part on the side of each bore
opening, such that the folded-back portions of the elastic plate
are in contact with their associated step-like thin-walled portion,
and such that the radial length of the base portions of the elastic
plates is within the range equal to the radial length of the
step-like thin-walled portions and the elastic plates are not in
contact with the thick-walled portion of the core plate. This
arrangement provides a much simpler structure in which no elastic
plates are laminated to the thick-walled portion of the core
plate.
[0035] Another alternative arrangement is such that each of the
thin-walled portions is a step-like thin-walled portion which is
formed by thinning a part on the side of each bore opening, such
that the folded-back portions of each elastic plate are in contact
with their associated step-like thin-walled portion, and such that
the base portion of each elastic plate holds an end of the
step-like thin-walled portion and the elastic plates are not in
contact with the thick-walled portion of the core plate. Similarly
to the above arrangements, this arrangement provides a much simpler
structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1 is a partial plan view of a laminated gasket
constructed according to a first embodiment of the invention.
[0037] FIG. 2 is a sectional view taken along line A-A of FIG.
1.
[0038] FIG. 3 is a sectional view of a laminated gasket constructed
according to a second embodiment of the invention.
[0039] FIG. 4 is a sectional view of a laminated gasket constructed
according to a third embodiment of the invention.
[0040] FIG. 5 is a sectional view of a laminated gasket constructed
according to a fourth embodiment of the invention.
[0041] FIG. 6 is a sectional view of a laminated gasket constructed
according to a fifth embodiment of the invention.
[0042] FIG. 7 is a sectional view of a laminated gasket constructed
according to a sixth embodiment of the invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0043] Referring now to the accompanying drawings, laminated
gaskets will be hereinafter described according to preferred
embodiments of the invention.
[0044] FIG. 1 shows a partial plan view of a laminated gasket
constructed according to a first embodiment of the invention and
FIG. 2 shows a sectional view taken along line A-A of FIG. 1.
[0045] A laminated gasket 1 according to the first embodiment is
used for sealing the joint between the opposed surfaces of the
cylinder head and cylinder block of a multi-cylinder engine. The
laminated gasket 1 is comprised of a core plate 2 and elastic
plates 3, 4 laminated to both sides of the core plate 2,
respectively.
[0046] The core plate 2 is formed to be relatively thick from a
steel plate such as SECC and has inclined thin-walled portions 2a
each positioned around each bore opening 5, whereas elastic plates
3, 4 are formed from a metal plate such as SUS 301, having base
portions 3a, 4a and folded-back portions 3b, 4b. Each folded-back
portion 3b (4b) is formed so as to create a clearance 6(7) around
each bore opening 5, together with a base portion 3a (4a). The
elastic plates 3, 4 have annular beads 3c and 4c respectively, such
that the annular beads 3c, 4c are positioned outside the fold-back
portions 3b, 4b, encircling them, respectively.
[0047] Each elastic plate 3(4) is laminated to the core plate 2
such that the folded-back portion 3b(4b) and the bead 3c(4c) are
brought into contact with the inclined thin-walled portion 2a of
the core plate 2. In other words, the folded-back portions 3b, 4b
and beads 3c, 4c of the elastic plates 3, 4 are located closer to
their associated bore opening 5 than a thin-walled portion boundary
line L on the elastic plates 3, 4. In the laminated condition, the
assembly of the core plate 2 and the elastic plates 3, 4 is
perfectly symmetrical with respect to a center line C of the cross
section of the core plate 2, the center line C extending in the
same direction as the extending direction of the core plate 2.
[0048] The core plate 2 and the elastic plates 3, 4 respectively
have bolt holes 8, water holes 9, oil holes 10, knock and bolt
holes 11 and others which are so formed as to pierce through these
plates.
[0049] In the laminated gasket 1 of the present embodiment, the
folded-back portions 3b, 4b in contact with the core plate 2
provide a first seal around each bore opening 5 while the beads 3c,
4c in contact with the core plate 2 provide a second seal, whereby
the gasket 1 has a double sealing function. The inclined
thin-walled portion 2a formed on the core plate 2 and the beads 3c,
4c allow the folded-back portions 3b, 4b of the elastic plates 3, 4
having clearances 6, 7 to maintain their springiness, so that when
the laminated gasket 1 is tightened between the opposed surfaces of
the cylinder head and the cylinder block, the clearances 6, 7 can
remain as much as possible. In addition, by virtue of the structure
in which the elastic plates 3, 4, which are provided with the
folded-back portions 3b, 4b including the clearances 6, 7 and with
the beads 3c, 4c, are positioned on both sides of the core plate 2
respectively, the laminated gasket 1 can flexibly receive the
stress of deformations which occur from the cylinder head side and
the cylinder block side when the laminated gasket 1 is tightened.
Consequently, surface pressures on both of the cylinder head side
and the cylinder block side can be distributed as desired. Further,
the laminated gasket 1 can easily conform to the deformation of the
cylinder head or the cylinder block when the engine is
operated.
[0050] FIG. 3 shows a sectional view of a laminated gasket
constructed according a second embodiment of the invention.
[0051] In a laminated gasket 11 of the second embodiment, a core
plate has inclined thin-walled portions 12a whereas elastic plates
13, 14 have folded-back portions 13b, 14b around each bore opening
5, respectively, but beads like those in the first embodiment are
not formed. Instead of beads, seal portions 15 made of a soft
sealing material such as graphite or urethane type high polymer
materials are formed on the core plate 12, being positioned outside
the thin-walled portion boundary line L. The seal portions 15
provide a second seal. It should be noted that the seal portions of
the example shown in FIG. 3 are annular bead-like seal portions
encircling the inclined thin-walled portion. With this arrangement,
the same function and effect as those of the first embodiment can
be achieved.
[0052] While the seal portions 15 are formed on the core plate 12,
being positioned outside the thin-walled portion boundary line L in
the present embodiment, the seal portions 15 may be formed on the
elastic plates 13, 14 and positioned inside the thin-walled portion
boundary line L, as far as they are positioned outside the
folded-back portions 13b, 14b.
[0053] FIG. 4 shows a sectional view of a laminated gasket
constructed according to a third embodiment of the invention. A
laminated gasket 21 according to the third embodiment has the same
structure as that of the second embodiment except that the inclined
thin-walled portion of the second embodiment is replaced by a
step-like thin-walled portion 22a formed on a core plate 22 and
that folded-back portions 23b, 24b formed on elastic plates 23, 24
are in contact with the step-like thin-walled portion 22a. In this
example, the elastic plates 23, 24 are respectively provided with a
seal portion 25 made of a soft sealing member.
[0054] FIG. 5 shows a sectional view of a laminated gasket
constructed according a fourth embodiment of the invention.
[0055] A laminated gasket 31 according to the fourth embodiment is
the same as the third embodiment in terms of the structure of a
step-like thin-walled portion 32a formed on a core plate 32, but
differs from the third embodiment in that the seal portions 25 of
the third embodiment are replaced by beads 33c, 34c formed on
elastic plates 33, 34 and in that these beads 33c, 34c are in
contact with a thick-walled portion 32b of the core plate 32 while
folded-back portions 33b, 34b being in contact with the step-like
thin-walled portion 32a.
[0056] FIG. 6 shows a sectional view of a laminated gasket
constructed according a fifth embodiment of the invention.
[0057] In a laminated gasket 41 according to the fifth embodiment,
a core plate 42 has a step-like thin-walled portion 42a, similarly
to the third and fourth embodiments. A thick-walled portion 42b of
the core plate 42 has projecting portions 45 on its lead end. Base
portions 43a, 44a of elastic plates 43, 44 are pinched by the
projecting portions 45 and secured to the core plate 42 by means of
caulking or the like. The width of the base portions 43a, 44a is
within the range equal to the width of the step-like thin-walled
portion 42a. In order to achieve a double sealing structure, seal
portions 46 made of a soft sealing material are formed on the
thick-walled portion 42b of the core plate 42. Thus, the elastic
plates 43, 44 are not in contact with the thick-walled portion 42b
of the core plate 42.
[0058] According to the structure of the present embodiment, since
the elastic plates 43, 44 are not laminated to the thick-walled
portion 42b of the core plate 42, the resultant laminated gasket
can be formed in a much simpler structure as a whole.
[0059] In cases where a high heat conductive material such as
aluminum and aluminum alloys is used as the material of the core
plate 42 in the structure of the present embodiment, not only can
good heat transfer between the combustion chamber--the cylinder
head--the cylinder block be achieved, but also it is effective in
improving the durability of the gasket and, in consequence, the
performance of the engine.
[0060] FIG. 7 shows a sectional view of a laminated gasket
constructed according a sixth embodiment of the invention.
[0061] In a laminated gasket 51 of the sixth embodiment, a
step-like thin-walled portion 52a is formed on a core plate 52 like
the foregoing embodiments. An elastic plate 53 holds, at its base
portion 53a, an end of the step-like thin-walled portion 52a of the
core plate 52 in a manner similar to a grommet. Folded-back
portions 53b, 53c formed on both ends of the base portion 53a are
in contact with the step-like thin-walled portion 52a, and the
elastic plate 53 is not in contact with a thick-walled portion 52b
formed in the core plate 52. Like the foregoing embodiment, seal
portions 56 made of a soft sealing material are formed on the
thick-walled portion 52b of the core plate 52 to achieve a double
sealing structure. By forming chamfered portions 57 on the corners
of the end of the core plate 52, the rounded parts of the
grommet-like portions can be prevented from cracking. With this
arrangement, a laminated gasket of a simple structure can be
achieved like the fifth embodiment.
[0062] In each of the foregoing embodiments, the materials of the
core plate and the elastic plates may be selected from any of
metallic materials and resinous materials. In the case of metal
plates, aluminum, aluminum alloys, and titanium--aluminum alloys
may be used.
[0063] The elastic plates laminated to both surfaces of the core
plate may be different from each other in material, the shape of
the folded-back portion and the shape of the bead, but it is
preferable that they be symmetrical with respect to the center line
of the cross section of the core plate, the center line extending
in the same direction as the extending direction of the core
plate.
[0064] The folded-back portions may be partly varied in width or in
the height of the clearance, around their respectively associated
bore openings.
[0065] The beads may be formed as half beads. Alternatively, either
of the beads may be formed as a half bead while the other being
formed as a full bead. In addition, the beads may be allowed to
meat each other by a known means in the area between the bore
openings.
[0066] The surfaces of the core plate and the elastic plates may be
partly or entirely treated by known coating. Additionally, seals
made of a soft sealing material such as graphite, rubber and
urethane high polymer materials may be locally employed. Further,
if necessary, a bead plate or shim plate may be laminated to the
outer surfaces of the elastic plates having the folded-back
portions.
* * * * *