U.S. patent application number 11/709744 was filed with the patent office on 2007-07-26 for metal gasket.
This patent application is currently assigned to Koichi Hatamura. Invention is credited to Koichi Hatamura, Masahisa Kumashiro, Reiji Mahigashi, Hiroyuki Ogino, Yasuyuki Okudaira, Takahiko Sugiura, Takashi Suzuki, Keisuke Umehara, Takeshi Wakuda.
Application Number | 20070170659 11/709744 |
Document ID | / |
Family ID | 34752138 |
Filed Date | 2007-07-26 |
United States Patent
Application |
20070170659 |
Kind Code |
A1 |
Hatamura; Koichi ; et
al. |
July 26, 2007 |
Metal gasket
Abstract
A metal gasket capable of preventing the occurrence of cracks in
a stopper while employing a wave-shaped stopper, improving the
contact pressure balance around the bead to enhance the engine
performance, and improving the durability of the stopper. The metal
gasket is constituted by a gasket component sheet having an opening
formed to face a combustion chamber, and the gasket component sheet
is provided with a combustion chamber bead surrounding the opening.
An inner circumference side stopper lower than the height of the
combustion chamber bead is formed along the combustion chamber bead
in a portion between the combustion chamber bead and the opening
such that at least a section of each wave where stress amplitude is
large becomes thin, a thin portion and a thick portion are arranged
alternately in each wave, and the hardness of the thin portion is
higher than that of the thick portion.
Inventors: |
Hatamura; Koichi;
(Hiroshima, JP) ; Suzuki; Takashi; (Ayabe-shi,
JP) ; Ogino; Hiroyuki; (Ayabe-shi, JP) ;
Sugiura; Takahiko; (Kyoto-shi, JP) ; Okudaira;
Yasuyuki; (Ayabe-shi, JP) ; Wakuda; Takeshi;
(Osaka, JP) ; Mahigashi; Reiji; (Fukuchiyama-shi,
JP) ; Umehara; Keisuke; (Ayabe-shi, JP) ;
Kumashiro; Masahisa; (Okayama-shi, JP) |
Correspondence
Address: |
ARMSTRONG, KRATZ, QUINTOS, HANSON & BROOKS, LLP
1725 K STREET, NW
SUITE 1000
WASHINGTON
DC
20006
US
|
Assignee: |
Koichi Hatamura
Hiroshima-shi
JP
KOKUSAN PARTS INDUSTRY CO., LTD.
Toyonaka-shi
JP
|
Family ID: |
34752138 |
Appl. No.: |
11/709744 |
Filed: |
February 23, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11038492 |
Jan 21, 2005 |
7204491 |
|
|
11709744 |
Feb 23, 2007 |
|
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|
Current U.S.
Class: |
277/595 |
Current CPC
Class: |
F16J 2015/0862 20130101;
F16J 2015/0875 20130101; F16J 15/0825 20130101; F16J 2015/085
20130101; F16J 15/0818 20130101; F16J 2015/0856 20130101 |
Class at
Publication: |
277/595 |
International
Class: |
F02F 11/00 20060101
F02F011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 23, 2004 |
JP |
2004-016343 |
Nov 19, 2004 |
JP |
2004-335349 |
Claims
1. A single-layer or multiple-layer metal gasket composed of a
single or a plurality of gasket component sheet(s) having an
opening formed to face a combustion chamber of an engine, at least
one of the gasket component sheets being provided with a bead
surrounding the opening, wherein an inner circumference side
stopper for preventing the bead from collapsing is formed at least
either in a portion between the bead and the opening of the gasket
component sheet formed with the bead or in a portion of another
gasket component sheet opposing the same; an outer circumference
side stopper for preventing the bead from collapsing is formed at
least either in a portion on the outer side from and close to the
bead in the gasket component sheet formed with the bead or in a
portion of another gasket component sheet opposing the same; and
the inner circumference side stopper is constituted by a plurality
of auxiliary beads which are formed along the bead in the
peripheral edge of the opening in the gasket component sheet such
that the inner circumference side stopper is formed by these
auxiliary beads into a wave-shaped cross section lower than the
height of the bead.
2. The metal gasket according to claim 1, wherein the outer
circumference side stopper is provided by dividing the gasket
component sheet to be provided with the outer circumference side
stopper into an inner circumference side component sheet located
close to the opening and an outer circumference side component
sheet corresponding to the other part of the gasket component sheet
and partially overlapping the inner circumference side component
sheet and the outer circumference side component sheet to form the
outer circumference side stopper.
3. The metal gasket according to claim 1, wherein the outer
circumference side stopper is provided by forming a build-up
portion from a material having thermal resistance and compressive
resistance.
4. The metal gasket according to claim 1, wherein the outer
circumference side stopper is provided by welding a ring-shaped
stopper plate.
5. The metal gasket according to claim 1, wherein the outer
circumference side stopper is provided by forming a plurality of
auxiliary beads along the bead such that the outer circumference
side stopper is formed by these auxiliary beads into a wave-shaped
cross section lower than the height of the bead.
6. The metal gasket according to claim 1, wherein the stoppers
formed by the plurality of auxiliary beads into a wave-shaped cross
section are formed along the bead such that a section of each wave
where stress amplitude is large becomes thin, a thin portion and a
thick portion are arranged alternately in each wave, and the
hardness of the thin portion is higher than that of the thick
portion.
7. The metal gasket according to claim 2, wherein the stoppers
formed by the plurality of auxiliary beads into a wave-shaped cross
section are formed along the bead such that a section of each wave
where stress amplitude is large becomes thin, a thin portion and a
thick portion are arranged alternately in each wave, and the
hardness of the thin portion is higher than that of the thick
portion.
8. The metal gasket according to claim 3, wherein the stoppers
formed by the plurality of auxiliary beads into a wave-shaped cross
section are formed along the bead such that a section of each wave
where stress amplitude is large becomes thin, a thin portion and a
thick portion are arranged alternately in each wave, and the
hardness of the thin portion is higher than that of the thick
portion.
9. The metal gasket according to claim 4, wherein the stoppers
formed by the plurality of auxiliary beads into a wave-shaped cross
section are formed along the bead such that a section of each wave
where stress amplitude is large becomes thin, a thin portion and a
thick portion are arranged alternately in each wave, and the
hardness of the thin portion is higher than that of the thick
portion.
10. The metal gasket according to claim 5, wherein the stoppers
formed by the plurality of auxiliary beads into a wave-shaped cross
section are formed along the bead such that a section of each wave
where stress amplitude is large becomes thin, a thin portion and a
thick portion are arranged alternately in each wave, and the
hardness of the thin portion is higher than that of the thick
portion.
Description
RELATED APPLICATIONS
[0001] This application is a division of U.S. patent application
Ser. No. 11/038,492, filed Jan. 21, 2005, which application claims
priority under 35 U.S.C. .sctn. 119 of Japanese Application No.
2004-016343, filed Jan. 23, 2004 and Japanese Application No.
2004-335349, filed Nov. 19, 2004, all of which are incorporated by
reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a metal gasket that can be
suitably used for automobile engines.
[0004] 2. Description of the Related Art
[0005] A metal gasket widely employed for automobile engines is one
which is composed of a single or a plurality of gasket component
sheet(s). The gasket component sheet has an opening formed to face
a combustion chamber, a bead formed to surround the opening, and a
stopper formed on the inner circumference side of the bead to
prevent the flattening of the bead.
[0006] An example of widely used stoppers is formed by folding back
the peripheral edge of a gasket component sheet opening so that
this folded part is used as a stopper. Meanwhile, it has recently
been proposed, as disclosed in Japanese Patent Kokai Publication
No. 2004-144119, to form a stopper with a wave-shaped cross
section, by means of press molding, on the inner side of a bead on
a gasket component sheet and concentrically with the opening. This
Japanese patent publication also discloses a stopper which is
formed by pressing a part of a gasket component sheet on the inner
circumference side of a bead into a sine wave shape, then smoothing
the top and bottom of each wave so that the slopes of the wave
become thicker than the top and bottom.
[0007] Japanese Patent Kohyo Publication No. 2004-503731 discloses
a metal gasket in which a stopper with a sine wave shape is formed
by press molding on the inner side of a bead on a gasket component
sheet so that the slopes of each wave become thinner than the top
and the bottom of the wave.
[0008] Formation of a stopper only on the inner circumference side
of a bead will lead to a problem of poor balance of contact
pressure around a combustion chamber. Therefore, it has also been
proposed to form a stopper both on the inner and outer
circumference sides of a bead to make the contact pressure balance
uniform (see Japanese Patent Kokai Publication No. H11-2324, for
example).
[0009] It is known that stress amplitude occurs in a metal gasket
bead, repeating compression and decompression, due to pressure
fluctuation in cylinders of an engine during engine operation, and
such stress amplitude constitutes a factor that causes cracks in
the bead. When a plurality of waves with a narrow width (with a
short wavelength) are arranged to function as a stopper as
described in the Japanese Patent Kokai Publication No. 2004-144119
and Kohyo Publication No. 2004-503731, in particular, the ratio of
height to width of each wave is so large that fatigue fracture will
possibly occur in the stopper if the waves are formed by a same
method as the bead. More specifically, according to conventional
techniques, a bead is formed using a mold having a molding surface
substantially conforming to the final shape of the bead, and this
fact raises a problem that a large frictional force is generated
between the top of a male punch and a blank metal sheet. The
frictional resistance thus generated restricts the lateral
extension of the part of the blank metal sheet contacted with the
top of the punch. When waves are formed into a required shape, only
the opposite slopes of the waves are extended but the top and
bottom thereof are not extended significantly. As the result, the
thickness at the top and bottom of each wave becomes larger than
the thickness of the slopes. This tendency becomes more severe as
the ratio of height to width of a bead becomes larger. Therefore,
if waves are formed with a large ratio of height to width as
described in Japanese Patent Kokai Publication No. 2004-144119 and
Kohyo Publication No. 2004-503731, there is a risk that fatigue
fracture occurs at the top of the waves in the stopper.
[0010] In addition, although Japanese Patent Kokai Publication No.
2004-144119 discloses a stopper having waves the top of which is
thin, these waves are formed by press molding a blank metal sheet
into a sine wave form and then smoothing the top of each wave. The
resistance to compression of the stopper may be enhanced by making
the slopes of the wave thicker in this manner. However, cracks are
liable to occur at the tops of waves which are subject to maximum
stress amplitude. Moreover, it is required to smooth the tops of
waves, after the press molding process, with the opening edge fixed
to prevent the wave width being enlarged. This makes the
manufacturing process complicated and requires a special mold for
the smoothing process.
[0011] Whereas, according to Japanese Patent Kokai Publication No.
H11-2324, a stopper is formed into a thin ring shape from a rigid
coating material or sintered material, on the inner and outer
circumference sides of a bead, by means of coating, flame spray
coating, screen printing, stencil spraying or the like. However,
the thermal resistance requirement is particularly stringent to the
stopper on the inner circumference side, that is arranged on the
side of combustion chamber, and such stopper is subjected to load
exerted in the shearing direction due to difference in coefficient
of thermal expansion between a cylinder head and a cylinder block.
Therefore, there is a risk that the sealing performance is
deteriorated as the result of the stopper coming off.
SUMMARY OF THE INVENTION
[0012] An object of the present invention is to provide a metal
gasket that is capable of effectively preventing the occurrence of
cracks in the stopper while using a wave-shaped stopper, and a
metal gasket that is capable of enhancing the engine performance by
improving the contact pressure balance around a bead and is still
capable of improving the durability of the stopper.
[0013] The present inventor has made a keen study on configuration
of a stopper capable of preventing the occurrence of cracks
effectively, and has accomplished the present invention,
discovering that cracks can be prevented effectively by increasing
the amount of plastic deformation at a part of a stopper where
fatigue fracture is liable to occur during press molding of a
gasket component sheet, that is, at a part where stress amplitude
is large, so that the hardness of such part is increased by work
hardening and thus the fatigue limit is increased.
[0014] A metal gasket according to a first aspect of the present
invention is a single-layer or multiple-layer metal gasket composed
of a single or a plurality of gasket component sheet(s) having an
opening formed to face a combustion chamber of an engine, at least
one of the gasket component sheets being provided with a bead
surrounding the opening, wherein an inner circumference side
stopper with a wave-shaped cross section lower than the height of
the beam is formed along the bead at least either in a portion
between the bead and the opening of the gasket component sheet
formed with the bead or in a portion of another gasket component
sheet opposing the same, such that at least a section of each wave
where stress amplitude is large becomes thin, a thin portion and a
thick portion are arranged alternately in each wave, and the
hardness of the thin portion is higher than that of the thick
portion.
[0015] When this metal gasket of the first aspect of the invention
is implemented as a single layer metal gasket, an opening is formed
in a single gasket component sheet, a bead is formed to surround
the opening, and an inner circumference side stopper with a
wave-shaped cross section is formed in a region between the bead
and the opening in the gasket component sheet. When it is
implemented as a multiple layer metal gasket, a bead and inner
circumferential stopper are formed on any one of the gasket
component sheets. The bead and the inner circumferential stopper
may be formed either on a same gasket component sheet or on
separate gasket component sheets. Also, the bead and the inner
circumferential stopper may be formed either in singularity or in
plurality.
[0016] When the metal gasket of the first aspect is mounted between
a cylinder block and a cylinder head and head bolts are tightened,
a certain gap is formed around the inner circumference side stopper
between the cylinder block and the cylinder head. The deformation
of the bead, which is arranged close to the inner circumference
side stopper, is reduced by the gap formed by the inner
circumference side stopper and the bead will not be compressively
deformed to a completely flattened state but only will be collapsed
by compression to a certain degree. This means that, in this metal
gasket, excessive compressive deformation of the bead is prevented
by the inner circumference side stopper, and it is thus possible to
prevent deterioration of the sealing performance due to flattening
of the bead.
[0017] Further, in the metal gasket of the first aspect, the inner
circumference side stopper with a wave-shaped cross section is
formed, by press molding for example, such that at least a section
of each wave where stress amplitude is large becomes thin, a thin
portion and a thick portion are arranged alternately in each wave,
and the hardness of the thin portion is higher than that of the
thick portion. In this manner, a thin portion the hardness and
fatigue limit of which is increased in comparison with a thick
portion by work hardening is provided at a portion where stress
amplitude is large, whereby it is made possible to prevent
effectively the fatigue fracture in the portion where stress
amplitude is large and to prevent the occurrence of cracks in the
stopper. Moreover, the inner circumference side stopper can be
formed by press molding only, not requiring the smoothing
processing like Japanese Patent Laid-Open Application No.
2004-144119. Therefore, it is possible to prevent the increase of
manufacturing processes, and to eliminate the need of using
equipment such as a special mold to be used for the smoothing. The
thick and thin portions are desirably provided in all the waves,
but it is also possible to provide them only in some specific
waves.
[0018] In this metal gasket, an outer circumference side stopper
with a wave-shaped cross section lower than the height of the
abovementioned bead may be formed along the bead, at least either
in a part of the gasket component sheet having the bead that is
located on the outer side of and close to the bead, or in a portion
of another gasket component sheet opposing the same, such that at
least a section of each wave where stress amplitude is large
becomes thin, a thick portion and a thin portion are arranged
alternately in each wave, and the hardness of the thin portion is
higher than that of the thick portion. In this case, a stopper is
formed on each of the inner circumference side and the outer
circumference side of the bead. Therefore, well-balanced contact
pressure can be obtained around the bead, and thus the circularity
of the cylinder holes can be increased to enhance the engine
performance while ensuring a high sealing performance. Further, the
waves of the outer circumference side stopper are formed similarly
to those of the inner circumference side stopper. Therefore, it is
possible not only to prevent the occurrence of cracks in the
stopper but also to prevent the increase of manufacturing
processes, eliminating the need of using equipment such as a
special mold for smoothing. The inner circumference side stopper
and the outer circumference side stopper may have a same height or
may have a different height to optimize the contact pressure
balance.
[0019] A groove may be formed along a portion where stress
amplitude is large so that such portion becomes thin. When such
groove is formed at the same time as the press molding of the
stopper, the portion where the groove is formed can be formed thin,
so that the hardness and fatigue limit of such portion is increased
by work hardening, and the occurrence of cracks due to stress
amplitude can be prevented effectively. When such groove is formed,
it is preferable that the groove is not formed at the bead-side
edge of a wave located adjacent to the bead for avoiding
complicating the construction of the mold.
[0020] Arrangement of thin and thick portions in a wave may be, for
example, such that a thin portion is provided at the top and bottom
of the wave while a thick portion is provided at an intermediate
portion in the height direction of the opposite slopes of the wave.
The arrangement may also be such that a thin portion is provided at
the top side and bottom side in the opposite slopes of the wave
while a thick portion is provided at the top and bottom of the wave
and at an intermediate portion in the height direction of the
opposite slopes of the wave. Further, the arrangement may also be
such that a thin portion is provided is provided at the top and at
a bottom side in the opposite slopes of the wave while a thick
portion is provided at the bottom and at an intermediate portion in
the height direction of the opposite slopes of the wave. This means
that stress amplitude acting on the stopper is larger around the
top and bottom of each wave. Therefore, by providing a thin portion
at the top or bottom of the wave, or at the top side or bottom side
in the opposite slopes of the wave, the hardness and fatigue limit
of such portion can be increased and the occurrence of cracks due
to stress amplitude can be prevented effectively.
[0021] The stopper may be formed to have a sine wave-shaped cross
section, or to have a flattened wave-shaped cross section in which
a flat surface is formed on the upper or lower face of the top or
bottom of each wave. Further, the cross sectional shape of the
stopper may be varied from the sine waveshape to the flattened
shape stepwise or continuously in the circumferential direction, so
as to equalize the contact pressure. It is also possible that, when
used for an in-line multiple-cylinder engine, the stoppers
surrounding the cylinders arranged on the opposite side are formed
to have a different cross sectional shape from that of the stopper
surrounding the cylinder arranged at the center. For example, the
stoppers surrounding the side cylinders may be formed to have a
sine wave-shaped cross section and the stopper surrounding the
center cylinder may be formed to have a flattened wave-shaped cross
section.
[0022] The stopper may be formed either continuously or
intermittently in the circumferential direction. When formed
intermittently, the stopper is preferably omitted in the vicinity
of an area where a head bolt is tightened for fastening the
cylinder head to the cylinder block. More specifically, the contact
pressure acting on the bead and the stopper becomes lower as the
part of the bead or stopper subjected to such contact pressure
recedes from the head bolt tightening portion. Therefore, the
stopper can be omitted in an area close to the head bolt tightening
portion so that the contact pressure acting on a portion of the
bead away from the head bolt tightening portion is increased to
adjust the contact pressure acting on the bead to become uniform in
the entire circumference. This arrangement is preferable since the
sealing performance can be improved in this manner.
[0023] It is also preferable to vary the height of waves of the
stopper in the circumferential direction, or to vary the number of
waves in the circumferential direction of the stopper. Similarly to
the case where the stopper is formed intermittently as described
above, the sealing performance can be improved by varying the
height or number of waves in the circumferential direction to
adjust the contact pressure acting on the bead. Specifically, the
height of the waves may be made lower, or the number of the waves
may be made smaller as closer to the head bolt tightening portion,
so that the contact pressure acting on the bead can be adjusted
uniformly. It is further possible to adjust the contact pressure
acting on the bead by combining a stopper formation portion, a wave
height, and a number of waves as required.
[0024] It is also preferable that the waves of the stopper be
projected to the same side as the bead is projected. When a metal
gasket having this arrangement is mounted between a cylinder head
and a cylinder block, the gasket component sheet can be prevented
from being elastically deformed between the stopper and bead. When
a metal gasket formed by overlapping a gasket component sheet
provided with a bead and another gasket component sheet provided
with a stopper, the term "the bead projecting side" means the side
of the surface facing the bead.
[0025] The wave of the stopper may be formed into a complete circle
or into a wave shape oscillating in a radial direction of the
opening. In case of the stopper having a wave shape oscillating in
a radial direction of the opening, the wavelength and amplitude of
such oscillation may be set uniformly for the entire circumference,
whereas the wavelength and/or amplitude of such oscillation may be
adjusted to adjust the contact pressure acting on the bead.
[0026] A metal gasket according to a second aspect of the present
invention is a single-layer or multiple-layer metal gasket composed
of a single or a plurality of gasket component sheet(s) having an
opening to face a combustion chamber of an engine, at least one of
the gasket component sheets being provided with a bead surrounding
the opening, wherein an inner circumference side stopper for
preventing the bead from collapsing is formed at least either in a
portion between the bead and the opening of the gasket component
sheet formed with the bead or in a portion of another gasket
component sheet opposing the same; an outer circumference side
stopper for preventing the bead from collapsing is formed at least
either in a portion close to and on the outer side than the bead in
the gasket component sheet formed with the bead or in a portion of
another gasket component sheet opposing the same; and the inner
circumference side stopper is constituted by a plurality of
auxiliary beads which are formed along the bead in the peripheral
edge of the opening in the gasket component sheet, the inner
circumference side stopper being formed in a wave-shaped cross
section lower than the height of the bead.
[0027] In this metal gasket of the second aspect, the inner and
outer circumference side stoppers are formed on the inner and outer
circumference sides of the bead, respectively. Therefore, it is
possible to obtain a well-balanced contact pressure around the
bead, and to increase the circularity of cylinder holes to improve
the engine performance while ensuring sufficient sealing
performance. Moreover, the inner circumference side stopper is
constituted by a plurality of auxiliary beads formed along the bead
at the peripheral edge of the opening of the gasket component
sheet, which makes it possible to effectively prevent the inner
circumference side stopper from coming off from the gasket
component sheet, and hence to prevent deterioration of sealing
performance caused by the coming off of the inner circumference
side stopper. Further, the outer circumference side stopper, which
can be formed arbitrarily, may possibly come off as a result of
aging or the like. Even if it comes off, however, it will not lead
to a serious problem since the sealing performance will be ensured
sufficiently by the inner circumference side stopper.
[0028] Preferred embodiments of this metal gasket of the second
aspect include an arrangement in which the outer circumference side
stopper is provided by dividing the gasket component sheet to be
provided with the outer circumference side stopper into an inner
circumference side component sheet located close to the opening and
an outer circumference side component sheet corresponding to the
other part of the gasket component sheet and partially overlapping
the inner circumference side component sheet and the outer
circumference side component sheet to form the outer circumference
side stopper; an arrangement in which the outer circumference side
stopper is provided by forming a build-up portion from a material
having thermal resistance and compressive resistance; an
arrangement in which the outer circumference side stopper is
provided by welding a ring-shaped stopper plate; an arrangement in
which the outer circumference side stopper is provided by forming a
plurality of auxiliary beads along the bead so that the outer
circumference side stopper is formed by the plurality of auxiliary
beads to have a wave-shaped cross section lower than the height of
the bead; and an arrangement in which the stopper formed by the
plurality of auxiliary beads to have a wave-shaped cross section is
formed along the bead such that a section of each wave where stress
amplitude is large becomes thin, a thin portion and a thick portion
are arranged alternately in each wave, and the hardness of the thin
portion is higher than that of the thick portion. The stopper with
a wave-shaped cross section of the metal gasket of the second
aspect can be constructed similarly to the stopper of the metal
gasket of the first aspect.
[0029] According to the first aspect of the present invention, the
metal gasket is capable of preventing excessive compressive
deformation of the bead by the presence of the inner circumference
side stopper and thus capable of preventing deterioration of the
sealing performance caused by flattening of the bead. In addition,
since the inner circumference side stopper with a wave-shaped cross
section is formed, for example by press molding, such that at least
a section of each wave where stress amplitude is large becomes
thin, a thin portion and a thick portion are arranged alternately
in each wave, and the hardness of the thin portion is higher than
that of the thick portion, the thin portion whose hardness and
fatigue limit have been increased by work hardening in comparison
with those of the thick portion is arranged in a portion where
stress amplitude is large. Therefore, it is possible to effectively
prevent fatigue fracture at the section where stress amplitude is
large, and hence to prevent occurrence of cracks in the stopper.
Moreover, since the inner circumference side stopper can be formed
by press molding only, the increase of manufacturing processes can
be prevented and the need of using equipment such as a special mold
for smoothing can be avoided.
[0030] If an outer circumference side stopper with a wave-shaped
cross section lower than the height of the bead is further provided
along the bead in at least either in a part close to and on the
outer side of the bead in the gasket component sheet where the bead
is formed or in a part of another gasket component sheet facing the
same, such that a section of each wave where stress amplitude is
large becomes thin, a thick portion and a thin portion wave are
alternately arranged in each wave, and the hardness of the thin
portion is higher than that of the thick portion, a well-balanced
contact pressure can be obtained around the bead, and the
circularity of the cylinder hole can be increased to enhance the
engine performance while ensuring sufficient sealing performance.
Further, since the waves of the outer circumference side stopper
are formed similarly to those of the inner circumference side
stopper, the occurrence of cracks in the stopper can be prevented.
Moreover, the increase of manufacturing processes can be prevented
while eliminating the need of equipment such as a special mold for
smoothing.
[0031] When a groove is formed along a portion where stress
amplitude is large t to make such portion thin, this portion where
the groove is formed can be made thinner, and the hardness and
fatigue limit of this portion can be enhanced by work hardening to
prevent effectively the occurrence of cracks due to stress
amplitude.
[0032] The hardness and fatigue limit of portions of each wave such
as the top or bottom, or the top side or bottom side in the
opposite slopes of the wave where stress amplitude is large can be
increased to effectively prevent the occurrence of cracks in such
portions, by implementing any of the followings: a thin portion is
provided at the top and bottom of each wave while a thick portion
is provided at an intermediate portion in the height direction of
the opposite slopes of the wave; a thin portion is provided at the
top side and bottom side in the opposite slopes of each wave while
the thick portion is provided at the top and bottom and at an
intermediate portion in the height direction of the opposite slopes
of the wave; a thin portion is provided at the top and at the
bottom side in the opposite slopes of each wave while a thick
portion is provided at the bottom and at an intermediate portion in
the height direction of the opposite slopes of the wave.
[0033] When the stopper is formed to have a flattened wave-shaped
cross section having a flat surface on the upper or lower face of
the top or bottom of each wave, the rigidity of the stopper can be
enhanced.
[0034] When the stopper is provided in appropriate portion, or the
height or number of waves is set appropriate, by forming the
stopper intermittently, or varying the height of the waves in the
circumferential direction of the stopper, or varying the number of
waves in the circumferential direction of the topper, the contact
pressure acting on the bead can be adjusted to enhance the sealing
performance.
[0035] By projecting the waves of the stopper to the same side as
the bead is projected, the gasket component sheet can be prevented
from being elastically deformed between the stopper and the bead
when the metal gasket is mounted between a cylinder head and a
cylinder block.
[0036] The formability of the stopper can be improved by forming
the waves of the stopper into a complete circle shape. When the
stopper is formed into waves oscillating in a radial direction of
the opening, the contact pressure acting on the bead can be
adjusted appropriately by adjusting the wavelength and/or amplitude
of the waves.
[0037] In the metal gasket according the second aspect of the
present invention, the contact pressure on the inner circumference
side and the contact pressure on the outer circumference side can
be well balanced in the vicinity of the bead by providing the inner
circumference side stopper on the inner circumference side and the
outer circumference side stopper on the outer circumference side.
Therefore, the circularity of the cylinder hole can be increased to
enhance the engine performance while ensuring sufficient sealing
performance. Moreover, the inner circumference side stopper can be
reliably prevented from coming off from the gasket component sheet,
and thus the deterioration of sealing performance due to coming off
of the inner circumference side stopper can be prevented
reliably.
[0038] The outer circumference side stopper also can be prevented
from coming off reliably when the outer circumference side stopper
is provided by dividing the gasket component sheet on which the
outer circumference side stopper is to be provided into an inner
circumference side component sheet located close to the opening and
an outer circumference side component sheet corresponding to the
other part of the gasket component sheet and overlapping the inner
circumference side component sheet and the outer circumference side
component sheet, or when the outer circumference side stopper is
provided by forming a plurality of auxiliary beads along the bead
so that the outer circumference side stopper is formed by the
plurality of auxiliary beads into a wave-shaped cross section lower
than the height of the bead. Additionally, if the outer
circumference side stopper is provided by forming the auxiliary
beads, it is possible to form the inner and outer circumference
side stoppers at the same time by press molding or the like, and
thus the formability of the gasket component sheet can be
improved.
[0039] If the stopper formed by the plurality of auxiliary beads
into a wave-shaped cross section as described above is provided
along the bead such that a section of each wave where stress
amplitude is large becomes thin, a thin portion and a thick portion
are arranged alternately in the wave, and the hardness of the thin
portion is higher than that of the thick portion, the same effect
as the metal gasket according to the first aspect can be
obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] FIG. 1 is a plan view showing principal parts of a metal
gasket;
[0041] FIG. 2 is a longitudinal sectional view taken along the line
II-II in FIG. 1, showing the state of an engine immediately before
the metal gasket is mounted between a cylinder block and a cylinder
head;
[0042] FIGS. 3A, 3B and 3C are sectional views showing various
types of waves;
[0043] FIG. 4 is a plan view showing principal parts of a metal
gasket having another configuration;
[0044] FIG. 5 is a longitudinal sectional view taken along the line
V-V in FIG. 4, showing the state of an engine immediately before
the metal gasket is mounted between a cylinder block and a cylinder
head;
[0045] FIG. 6 is a longitudinal sectional view showing the vicinity
of a stopper of a metal gasket having another configuration;
[0046] FIGS. 7A through 7C are longitudinal sectional views showing
the vicinity of a stopper of various types of multiple-layer metal
gaskets;
[0047] FIGS. 8A through 8D are longitudinal sectional views showing
the vicinity of a stopper of various types of multiple-layer metal
gaskets with other configurations;
[0048] FIG. 9 is a plan view showing principal parts of a metal
gasket having another configuration;
[0049] FIG. 10 is a plan view showing a metal gasket having another
configuration;
[0050] FIG. 11 is a plan view showing the vicinity of a stopper of
a gasket component sheet with another configuration;
[0051] FIG. 12 is a plan view showing principal parts of a metal
gasket;
[0052] FIG. 13 is a longitudinal sectional view of an engine
showing the vicinity of a stopper in the state immediately before a
cylinder head is attached to a cylinder block;
[0053] FIG. 14 is a longitudinal sectional view of the engine
showing the vicinity of the stopper in the state after the cylinder
head has been attached to the cylinder block;
[0054] FIG. 15 is a sectional view taken along the line XV-XV in
FIG. 1;
[0055] FIGS. 16A and 16B are views corresponding to FIG. 15 but
showing metal gaskets with different configurations therefrom;
and
[0056] FIGS. 17A through 17D are views corresponding to FIG. 15 but
showing metal gaskets with different configurations therefrom.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0057] Preferred embodiments of the present invention will now be
described with reference to the drawings.
First Embodiment
[0058] A metal gasket 1 shown in FIGS. 1 and 2 is a metal gasket
for in-line multiple-cylinder engines. This metal gasket 1 is
designed to be interposed between joint surfaces 4 and 5 of a
cylinder block 2 and a cylinder head 3 to seal the joint surfaces 4
and 5 which face a combustion chamber 6, a water jacket 7, a
lubricating oil passage (not shown) and so on. The metal gasket 1
according to the present invention is applicable to engines having
a cylinder block of cast iron, and engines having a cylinder block
and a cylinder head principally made from a light alloy such as
aluminum alloy or magnesium alloy. In this embodiment, the metal
gasket 1 according to the present invention is applied to an engine
which has an open deck type cylinder block 2 in which the top face
of a water jacket 7 is open, and the cylinder block 2 and a
cylinder head 3 of which are made from an aluminum alloy.
[0059] The metal gasket 1 is composed of a single gasket component
sheet 10 which is interposed between the joint surfaces 4 and 5 of
the cylinder block 2 and cylinder head 3 to cover substantially all
over the joint surfaces 4 and 5.
[0060] The gasket component sheet 10 is formed of a stainless steel
sheet such as SUS301 stainless steel sheet according to JIS
standard. The outline of the gasket component sheet 10 is formed
into a substantially identical shape with that of the joint surface
4 of the cylinder block 2. If the thickness of the gasket component
sheet 10 is less than 0.15 mm, the rigidity of the beads 15, 20-22
will become too low to provide a sufficient contact pressure,
whereas if the thickness exceeds 0.4 mm, cracks may occur in the
beads 15, 20-22 due to deterioration of the material after
processing or excessive tightening of a head bolt. Therefore, the
thickness of the gasket component sheet 10 is set preferably to
0.15 to 0.4 mm, more preferably to a range from 0.15 to 0.35 mm,
and particularly preferably to a range from 0.2 to 0.25 mm. The
gasket component sheet 10 can be formed of a metal sheet only, but
also can be formed of a coated metal sheet having at least one of
the surfaces coated with a rubber layer or the like for improving
the sealing performance of the metal gasket 1.
[0061] A plurality of openings 11 are formed in a substantially
central portion in the transverse direction of the gasket component
sheet 10, at intervals in the longitudinal direction so as to face
a combustion chamber 6. A plurality of cooling water holes (not
shown) are formed in a specific arrangement on the outside of the
openings 11 in association with a water jacket 7 of the cylinder
block 2. A plurality of bolt insertion holes 12, through which head
bolts (not sown) are inserted for fastening the cylinder head 3 to
the cylinder block 2, are formed on the outside of the cooling
water holes at substantially regular intervals so as to surround
the openings 11, so that the cylinder head 3 can be fastened to the
cylinder block 2 by means of the bolts in a well-balanced manner.
An oil hole 13 through which lubricating oil flows is formed on the
outside of specific bolt insertion holes 12 so that the lubricating
oil is supplied from the cylinder block 2 side to the cylinder head
3 side for lubricating a valve mechanism or the like.
[0062] The gasket component sheet 10 has a combustion chamber bead
15 surrounding the combustion chamber 6, an inner circumference
side stopper 17 composed of a plurality of waves 16 an arranged at
an inner side from the combustion chamber bead 15, a bolt hole bead
20 surrounding the bolt insertion hole 12, a bolt/oil hole bead 21
surrounding the combination of the bolt insertion hole 12 and the
oil hole 13, and an outer circumferential bead 22 surrounding the
whole of the plurality of bolt hole beads 20 and bolt/oil hole
beads 21. The outer circumferential bead 22 may be arranged not to
surround the bolt hole beads 20 or bolt/oil hole beads 21, as long
as it is arranged to surround the cooling water holes. Further, the
bolt hole beads 20, the bolt/oil hole beads 21 and the outer
circumferential bead 22 may be constituted either by a round bead
having a circular arc section or by a stepped bead with a stepped
shape.
[0063] The shapes, numbers and arrangement of the openings 11,
cooling water holes, bolt insertion holes 12, and oil holes 13, as
well as the shapes, numbers and arrangement of the combustion
chamber beads 15, bolt hole beads 20, bolt/oil hole beads 21, and
outer circumferential bead 22 in the gasket component sheet 10 are
determined as required according to the configuration of the engine
or the like.
[0064] The inner circumference side stopper 17 and the combustion
chamber bead 15 are arranged on the side closer to the combustion
chamber 6 than the water jacket 7 and so as to face the top face of
a cylindrical cylinder inner peripheral wall 2a of in the cylinder
block 2. The combustion chamber bead 15 is arranged in a
substantially central part in the thickness direction of the
cylinder inner peripheral wall 2a.
[0065] The inner circumference side stopper 17 is formed by press
molding only, and is formed to have a cross sectional shape
consisting of four annular waves 16 substantially concentrical with
the combustion chamber bead 15. The center line in the thickness
direction of the inner circumference side stopper 17 is formed in a
substantially sine wave shape. The number of waves 16 can be set
arbitrarily, but it is preferable to provide at least two waves 16
for ensuring the function as the inner circumference side stopper
17. While the inner circumference side stopper 17 may be formed by
a single press molding process, it may also be formed by a
plurality of press molding processes such that a desired shaped is
obtained step-by-step.
[0066] The width of each wave 16 is set to be smaller than the
width of the combustion chamber bead 15, and the height of the
waves 16 is set to be smaller than the height of the combustion
chamber bead 15 in its natural state. While the waves 16 can be
projected to the opposite side from the side where the combustion
chamber bead 15 is projected, it is preferable that the waves 16 be
projected to the same side as the combustion chamber bead 15 is
projected while placing the bottom face of each wave 16
substantially in the same plane as the bottom face of a flat
general portion of the gasket component sheet 10 in order to
minimize the deformation of the gasket component sheet 10 between
the waves 16 and the combustion chamber bead 15.
[0067] The inner circumference side stopper 17 is press molded such
that at least a section of the waves 16 constituting the same where
stress amplitude is large during engine operation becomes thin and
a thin portion and a thick portion are arranged alternately in each
wave 16. Work hardening is induced during pressing molding of the
inner circumference side stopper 17 and the portions where stress
amplitude is large are made thin. This work hardening increases the
hardness and fatigue limit of the thin portions to make these
portions more resistible against fatigue fracture. Therefore, the
durability against stress amplitude of the thin portions can be
enhanced and the occurrence of cracks in these portions can be
prevented. While the portions where stress amplitude becomes large
are determined partially according to the shape of the inner
circumference side stopper 17, they are basically located at least
at the top 16a and bottom 16c of each wave 16, and at a top 16a
side and bottom 16c side in the slopes 16b. As particular methods
for forming the thin portion by press molding, preferable are a
method of designing a mold such that the mold part for forming the
thin portion has a smaller radius, and a method of providing the
mold part corresponding to the thin portion with a ridge such that
a groove with a circular-arc cross section is formed along the
portion where a stress amplitude becomes large, but other methods
also can be employed.
[0068] Specific arrangement of thin and thick portions will now be
described. It should be noted that, however, as long as a thin
portion is disposed at the top 16a and bottom 16c of each wave 16
and at the top 16a side and bottom 16c side in the slopes 16b,
other configurations than those described below also can be
employed.
[0069] As shown in FIG. 3A, the tops 16a and bottoms 16c, and upper
and lower faces in their vicinity of the inner circumference side
stopper 17 are formed by curved surfaces having a uniform radius,
so that the inner circumference side stopper 17 is formed into a
substantially sine wave shape. In this case, thin portions and
thick portions are formed within one cycle S of each wave 16 such
that the top 16a and the bottom 16c corresponding to grooves 18
have a smallest thickness t1 and the thickness gradually increases
towards the slopes 16b up to a largest thickness t2 at a
substantially central portion in the height direction of the slopes
16b.
[0070] As shown in FIG. 3B, a flat surface 16d is formed at the
bottom of the upper face and at the top of the lower face of the
inner circumference side stopper 17, while the other portions are
formed by generally curved surfaces, so that the inner
circumference side stopper 17 is formed into a flattened sine wave
shape. In this case, thin portions and thick portions are formed
within one cycle S of each wave 16 by varying the thickness
gradually such that the top 16a and the bottom 16c, and
intermediate portions in the height direction of the slopes 16b
have a largest thickness t2 and the portions of the slopes 16b
located on the top 16a side and bottom 16c side and associated with
respective grooves 18 have a smallest thickness t1. It should be
noted that, however, the thickness t1 of the portion at the top 16a
side in the slopes 16b of each wave 16 may be set equal to or
different from the thickness t1 of the portion at the bottom 16c
side in he slopes 16b. Also, the thickness t2 of the top 16a and
bottom 16c of each wave 16 may be set equal to or different from
the thickness t2 in the height direction of the slopes 16b.
[0071] As shown in FIG. 3C, a flat surface 16d is formed at the
bottom of the upper face while the other portions are formed by
generally curved surfaces, so that the inner circumference side
stopper 17 is formed in a flattened substantially sine wave shape.
In this case, thin portions and thick portions are formed within a
cycle S of each wave 16 by gradually varying the thickness such
that the top 16a and the bottom 16c side portions of the slopes 16b
opposing respective grooves 18 have a smallest thickness t1 and the
bottom 16 and substantially central portion in the height direction
of the slopes 16b have a largest thickness t2. It should be noted
that, however, the thickness t1 at the top 16a of each wave 16 may
be set equal to or different from the thickness t1 at the bottom
16c side portion of the slopes 16b. Also, the thickness t2 at the
bottom 16c of each wave 16 may be set equal to or different from
the thickness t2 in the height direction of the slopes 16b.
[0072] The waves 16 as shown in FIGS. 3A through 3C may be formed
upside down. Further, as for the waves 16 disposed adjacent to the
combustion chamber bead 15, the grooves to be formed on the side of
the combustion chamber bead 15 may be omitted to avoid the
complication of mold configuration.
[0073] In the gasket component sheet 10, a thickness t0 of the flat
general portion other than the inner circumference side stopper 17
(see FIG. 2), a thickness t1 of the thin portion and a thickness t2
of the thick portion of each wave 16 are set to satisfy the
following relationships (1) to (3), where a and b are constants:
t1=a.times.t0(0.05=a=0.95) (1) t2=b.times.t0(0.5=b=0.95) (2) a<b
(3)
[0074] More specifically, if the constants a and b are less than
0.5, the thicknesses of the thin portion and thick portion become
both so thin that the inner circumference side stopper 17 becomes
more liable to be broken. Whereas, if the constants a and be are
larger than 0.95, the effect of work hardening, which would be
obtained by making the sheet thinner, can hardly be expected.
Therefore, it is preferable that the costants a and b be set as
0.5=a=0.95 and 0.5=b=0.95, respectively. Thus, when the press
molding is conducted such that the thin portion has a thickness
smaller than that of the general portion, the hardness and fatigue
limit of the thin portion can be increased by the work hardening
caused by the press molding, and the fatigue resistance of the thin
portion can be enhanced. Additionally, when the thickness of the
thick portion is made thicker than the thin portion but slightly
thinner than the flat general portion, the hardness and fatigue
limit of the thick portion can be increased by the work hardening
caused by the press molding, and thus the fatigue fracture of the
inner circumference side stopper 17 as a whole can be prevented
effectively.
[0075] This metal gasket 1 is mounted to the engine by fastening
the cylinder head 3 to the cylinder block 2 by means of head bolts
with the metal gasket 1 interposed between the cylinder block 2 and
the cylinder head 3. When the metal gasket 1 is mounted in this
manner, the combustion chamber bead 15 is compressively deformed by
a difference in height between the combustion chamber bead 15 and
the inner circumference side stopper 17 to seal the combustion
chamber 6. Additionally, a gap is formed in the vicinity of the
combustion chamber bead 15 by the inner circumference side stopper
17, whereby excessive compressive deformation of the combustion
chamber bead 15 can be prevented and thus the combustion chamber
bead 15 can be prevented from being flattened. Moreover, the thin
portions, the hardness and fatigue limit of which have been
increased by the work hardening, are disposed at portions of the
inner circumference side stopper 17, where stress amplitude is
large, namely at the tops 16a and bottoms 16c of the waves 16 and
at the top 16a side and bottom 16c side portions of the slopes 16b
of the waves 16. Therefore, the fatigue fracture of the waves 16
can be prevented effectively. Further, since the inner
circumference side stopper 17 can be formed by the press molding
only, the metal gasket 1 can be manufactured by utilizing existing
equipment effectively.
[0076] It should be noted that the cross-sectional shape of the
inner circumference side stopper 17 is not limited to a sine wave
shape, and may assume an arbitrary wave shape such as a rectangular
or trapezoidal wave shape. In addition, the height (amplitude) and
the width (wavelength) of waves 16 may differ in the inner
circumference side stopper 17 between the center side and the
outside in the radial direction. Specifically, if the height of the
waves 16 on the center side is made higher or the width thereof is
made smaller, the air tightness of the combustion chamber 6 can be
enhanced.
[0077] Further, it is also possible to vary the number of the waves
16 in the circumferential direction of the inner circumference side
stopper 17, to vary the height of the wave 16, or to vary the width
of the waves 16 in the circumferential direction of the inner
circumference side stopper 17. By varying the number, the height or
the width of the waves 16 in the circumferential direction, the
contact pressure acting on the bead can be adjusted to improve the
sealing performance. Specifically, the setting can be made such
that the number of the waves 16 becomes smaller, the height of the
waves 16 becomes lower, or the width of the waves 16 becomes larger
towards the bolt insertion holes 12 through which the head bolts
are inserted, and thus the contact pressure acting on the
combustion chamber bead 15 can be adjusted uniformly. Further, it
is also possible to adjust the contact pressure acting on the
combustion chamber bead 15 by combining the number, the height and
the width of the waves 16 as required.
[0078] It is also possible that a synthetic resin material or
metallic material having thermal resistance and compressive
resistance is built up or deposited in between the adjacent waves
16 in the inner circumference side stopper 17 by means of pattern
printing, metal press fitting, metal flame spray coating, or
material application with a dispenser so as to fill the valleys
between the waves 16 with such material. When this is done, the
inner circumference side stopper 17 is allowed to exhibit its
function at full. Such metallic material or synthetic resin
material may be built up or deposited between all of the waves 16
or between specific adjacent waves 16 only. Also, the material may
be built up continuously in the circumferential direction, or may
be built up partially such that a uniform contact pressure is
acting on the combustion chamber bead 15. The synthetic resin
material or metallic material thus built up or deposited has its
external surface placed at the same level as the top 16a or bottom
16c of the waves 16. The external surface of the material may
either cover the top 16a or bottom 16c, or expose the top 16a or
bottom 16c to the outside.
Second Embodiment
[0079] As shown in FIGS. 4 and 5, a metal gasket 1A according to
this second embodiment is a single layer metal gasket composed of a
gasket component sheet 10A, and is constituted by partially
modifying the gasket component sheet 10 of the metal gasket 1 of
the first embodiment described above. In FIGS. 4 and 5, like
components to those of the first embodiment are designated with
like reference numerals and description thereof is omitted.
[0080] The gasket component sheet 10A of the metal gasket 1A is
provided with an inner circumference side stopper 17A with a
wave-shaped cross section having two waves 16, instead of the inner
circumference side stopper 17 of the gasket component sheet 10
according to the first embodiment, and is further provided with an
outer circumference side stopper 30 with a wave-shaped cross
section having two waves 16. The outer circumference side stopper
30 is provided on the outside of and close to the combustion
chamber bead 15 so as to surround the entire of the combustion
chamber bead 15. While the metal gasket 1A is applicable to engines
having a cylinder block of cast iron, it is suitably applicable for
engines having a cylinder block and a cylinder head principally
made from a light alloy such as aluminum alloy or magnesium alloy.
The metal gasket 1A is particularly suitably applicable to an open
deck type engine having a water jacket 7 the top of which is open,
because the metal gasket 1A is helpful to prevent the deterioration
of circularity of a cylinder inner peripheral wall 2a of a cylinder
block 2 constituting a combustion chamber 6, which is otherwise
liable to occur in this type of engines.
[0081] Like the waves 16 of the inner circumference side stopper 17
of the first embodiment, the waves 16 of the toppers 17A and 30 are
also designed such that a thin portion, whose hardness and fatigue
limit have been increased by the work hardening, is disposed at the
top 16a and bottom 16c of each wave 16, and at top 16a side and
bottom 16c side portions in the opposite slopes 16b, where stress
amplitude is large.
[0082] While the number of the waves 16 in the stoppers 17A and 30
may be set arbitrarily, it is preferable to provide at least two
waves 16 for ensuring the function as the stoppers. It is also
possible to differentiate the number, height or width of the waves
16 between the inner circumference side stopper 17A and the outer
circumference side stopper 30. For example, the number of waves 16
in the inner circumference side stopper 17A can be set larger than
the number of waves 16 in the outer circumference side stopper 30,
or the height of the wave 16 in the inner circumference side
stopper 17A can be set greater than that of the waves 16 in the
outer circumference side stopper 30, or the width of the waves 16
in the inner circumference side stopper 17A can be set greater than
that of the waves 16 in the outer circumference side stopper 30, so
that the air tightness of the combustion chamber 6 can be improved.
Further, the waves 16 of the stoppers 17A and 30 may be projected
to the opposite direction from the direction the combustion chamber
bead 15 is projected, but it is preferable that the waves 16 be
protruded to the same direction as the combustion chamber bead 15
in order to ensure that these stoppers function sufficiently as the
stopper 17 for the combustion chamber bead 15.
[0083] When using this metal gasket 1A, the metal gasket 1A is
incorporated in the engine by fastening the cylinder head 3 to the
cylinder block 2 by the use of head bolts with the metal gasket 1A
interposed between the cylinder block 2 and the cylinder head 3.
When the metal gasket 1A is mounted in this manner, the combustion
chamber bead 15 is compressively deformed by the difference in
height between the combustion chamber bead 15 and the stoppers 17A
and 30 to seal the combustion chamber 6. Further, a gap is formed
by the stoppers 17A and 30 in the vicinity of the combustion
chamber bead 15, whereby excessive compressive deformation of the
combustion chamber bead 15 is prevented, and thus the combustion
chamber bead 15 is prevented from being flattened. Moreover, the
tightening load from the head bolt is distributed over and exerted
in a well-balanced manner to the top face of the cylinder inner
peripheral wall 2a by the combustion chamber bead 15 and stoppers
17A and 30. Therefore, the deformation in a radial direction of the
cylinder inner peripheral wall 2a can be minimized to improve the
circularity of the cylinder hole and hence to improve the engine
performance. Further, similarly to the stopper 17 according to the
first embodiment described above, a synthetic resin material or
metallic material having thermal resistance and compressive
resistance may be built up or deposited in between the adjacent
waves 16 in at least one of the stoppers 17A and 30 by means of
pattern printing, metal press fitting, metal flame spray coating,
or material application with a dispenser so as to enhance the
functions as the stopper 17.
[0084] Further, the fatigue fracture of the wave 16 can be
prevented effectively, since a thin portion, whose hardness and
fatigue limit have been enhanced by the work hardening, is provided
at the top 16a and bottom 16c of each waves 16 of the stoppers 17A
and 30 and at the top 16a side and bottom 16c side portions of the
slopes 16b. Still further, since the stoppers 17A and 30 can be
formed by press molding only, metal gasket 1A can be manufactured
by utilizing existing equipment effectively.
[0085] It should be noted that the thermal resistance and other
properties required for the outer circumference side stopper 30 are
not as high as those for the inner circumference side stopper 17A.
Therefore, as shown in FIG. 6, a metal gasket 1B may be formed by a
gasket component sheet 10B having no outer circumference side
stopper 30 and this gasket component sheet 10B may be provided with
an outer circumference side stopper 31 formed by depositing a
synthetic resin material or metallic material having thermal
resistance and compressive resistance by means of pattern printing,
metal flame spray coating, or material application with a
dispenser, or by welding a ring-shaped stopper plate.
Third Embodiment
[0086] Description so far has been made on the first and second
embodiments in which the metal gaskets 1, 1A and 1B is constituted
by a single gasket component sheet 10, 10A and 10B, respectively.
However, the present invention is also applicable to a
multiple-layer metal gasket composed of a plurality of gasket
component sheets.
[0087] Specifically, FIG. 7A shows a metal gasket 1C, for example,
in which a substantially flat gasket component sheet 35 is laid
over the surface of the gasket component sheet 10A according to the
second embodiment which includes the projecting side of the
combustion chamber bead 15. Alternatively, FIG. 7B shows a metal
gasket 1D, in which a flat gasket component sheet 35 is laid over
the opposite surfaces of the gasket component sheet 10A according
to the second embodiment. Yet further alternatively, FIG. 7C shows
a metal gasket 1E, in which a gasket component sheet 36 having a
combustion chamber bead 15 is laid over the surface of the gasket
component sheet 10A according to the second embodiment which
includes the projecting side of the combustion chamber bead 15,
such that the both combustion chamber beads 15 abut against each
other. Further, a metal gasket may be constructed by superposing
the gasket constituent sheet 35 or 36 on the gasket component sheet
10 or 10B instead of the gasket component sheet 10A.
[0088] Further, FIG. 8A shows a metal gasket 1F, for example, in
which a gasket component sheet 37 obtained by omitting the outer
circumference side stopper 30 from the gasket component sheet 10A
according to the second embodiment is laid over a gasket component
sheet 38 obtained by omitting the combustion chamber bead 15 and
inner circumference side stopper 17A from the gasket component
sheet 10A according to the second embodiment. Alternatively, FIG.
8B shows a metal gasket 1G, in which a gasket component sheet 39
obtained by omitting the inner circumference side stopper 17A from
the gasket component sheet 10A of the second embodiment is laid
over a gasket component sheet 40 obtained by omitting the
combustion chamber bead 15 and outer circumference side stopper 30
from the gasket component sheet 10A of the second embodiment.
Further alternatively, FIG. 8C shows a metal gasket 1H, in which a
first gasket component sheet 41 obtained by omitting the inner
circumference side stopper 17 and outer circumference side stopper
30 from the gasket component sheet 10A of the second embodiment is
laid over a gasket component sheet 42 obtained by omitting the
combustion chamber bead 15 from the gasket component sheet 10A of
the second embodiment. Yet further alternatively, FIG. 8D shows a
metal gasket 1I, in which the gasket component sheet 41 is laid
over a second gasket component sheet 46 that is formed by dividing
the gasket component sheet 42 as used in the metal gasket 1H into
an inner circumference side component sheet 43 surrounding the
opening 11 and an outer circumference side component sheet 44
corresponding to the other part, and providing, in place of the
outer circumference side stopper 30, an overlapped portion 45 of
these component sheets 43 and 44. When a plurality of gasket
component sheets are superposed in this manner, the outer
circumference side stopper 30 may be substituted with a build-up
portion that is formed by depositing a synthetic resin material or
metallic material having thermal resistance and compressive
resistance by means of pattern printing, material application with
a dispenser, or metal flame spray coating, or by welding a
ring-shaped plate serving as the stopper 17.
[0089] In the second embodiment described above, the inner
circumference side stopper 17A is formed into a complete circle
shape centered on the opening 11 while the outer circumference side
stopper 30 is formed into a continuous ring shape defined by a
combination of complete circle shape portions centered on the
opening 11. Alternatively, as a gasket component sheet 10J for a
metal gasket 1J shown in FIG. 9, the outer circumference side
stopper 30 may be omitted in the vicinity of a merging portion 15a
where the combustion chamber beads 15 surrounding the adjacent
openings 11 merge with each other so that the outer circumference
side stopper 30 is formed intermittently. Further alternatively, as
a gasket component sheet 10K for a metal gasket 1K shown in FIG.
10, the outer circumference side stopper 30 and inner circumference
side stopper 17A may be omitted in the vicinity of the bolt
insertion holes 12 so that the these stoppers 17A and 30 are formed
intermittently. Further, it is also possible in the gasket
component sheet 10 of the first embodiment which is provided with
the inner circumference side stopper 17 only and not with the outer
circumference side stopper 30, to adjust the contact pressure by
omitting the inner circumference side stopper 17 in the vicinity of
the portion where a head bolt is tightened.
[0090] Still further, as a gasket component sheet 10L shown in FIG.
11, an inner circumference side stopper 1 7B may be formed into a
wave shape that oscillates in a radial direction in place of the
inner circumference side stopper 17 or 17A formed into a complete
circle shape. Although not shown in the drawings, the outer
circumference side stopper 30 also may be formed in a wave shape
oscillating in a radial direction. In this case, the contact
pressure can be adjusted by adjusting the width or height of the
waves.
[0091] It should be noted that, although the description so far has
been made on a metal gasket composed of one to three gasket
component sheet(s), the present invention is also applicable to a
metal gasket constituted by layering four or more gasket component
sheets. In a metal gasket constituted by a plurality of gasket
component sheets in this manner, these gasket component sheets
layered on top of another are joined integrally by means of an
eyelet or mechanical clinch at a portion not including the joint
surfaces 4 and 5 of the cylinder block 2 and cylinder head 3, for
example at a portion outside of the joint surfaces 4 and 5 of the
cylinder block 2 and cylinder head 3, or at a portion where the
water jacket 7 is arranged.
[0092] In the present embodiment, the present invention is applied
to a metal gasket that is mounted between a cylinder block 2 and
the cylinder head 3 of an in-line multiple-cylinder engine.
However, the present invention is also applicable to a
single-cylinder engine or V-engine. The present invention is also
well applicable to an air pump or the like, in addition to such
various types of engines.
Fourth Embodiment
[0093] FIG. 12 shows a metal gasket 51 used for in-line
multiple-cylinder engines. This metal gasket 51 is designed, as
shown in FIGS. 13 and 14, such that the metal gasket 51 is
interposed between joint surfaces 54 and 55 of a cylinder block 52
and a cylinder head 53 to seal the joint surfaces 54 and 55 facing
a combustion chamber 56, a water jacket (not shown), and a
lubricating oil passage (not shown). While the metal gasket 51
according to the present invention is applicable to engines having
a cylinder block 52 made from cast iron, it is more suitably
applicable to engines having a cylinder block 52 and a cylinder
head 53 which are principally made from a light alloy such as an
aluminum alloy or magnesium alloy. Particularly, the metal gasket
of the present invention is suitably applicable to open deck type
engines having a water jacket 57 the top face of which is open.
This is because the metal gasket of the present invention is
capable of effectively preventing the reduction of circularity of
the inner peripheral wall 52a of the cylinder block 52 constituting
a combustion chamber 56, which is liable to occur in this type of
engines.
[0094] The metal gasket 51 is, as shown in FIGS. 12 through 15,
constituted by a single gasket component sheet 60 that is
interposed between the joint surfaces 54 and 55 of the cylinder
block 52 and the cylinder head 53 so as to cover substantially all
over these joint surfaces.
[0095] The gasket component sheet 60 is made of a sheet of SUS301
stainless steel or the like, and the outline of gasket component
sheet 60 is shaped into a substantially identical shape to that of
the joint surface 54 of the cylinder block 52. If the thickness of
the gasket component sheet 60 is less than 0.15 mm, the rigidity of
the bead is too low to provide a sufficient contact pressure,
whereas if it is more than 0.4 mm, cracks may occur as a result of
deterioration of the material caused by processing or excessive
tightening of head bolts. Therefore, the thickness of the gasket
component sheet 60 is preferably set to a range from 0.15 to 0.4
mm, more preferably to a range from 0.15 to 0.35 mm, and
particularly preferably to a range from 0.2 to 0.25 mm. While the
gasket component sheet 60 may be constituted by a metal sheet only,
it also can be constituted by a coated metal sheet obtained by
coating at least one of the surfaces of the gasket component sheet
60 with a rubber coating layer or the like for improving the
sealing performance of the metal gasket 51.
[0096] A plurality of openings 61 are formed in a substantially
central portion in the width direction of the gasket component
sheet 60, while being spaced from each other to face a combustion
chamber 56. On the outside of each of the opening 61, a plurality
of cooling water holes (not shown) are formed in a predetermined
arrangement so as to face a water jacket 57 of the cylinder block
52. On the outside of the cooling water holes, a plurality of bolt
insertion holes 62, through which head bolts (not shown) are
inserted for fastening the cylinder head 53 to the cylinder block
52, are formed at substantially equal intervals so as to surround
the openings 61, whereby the cylinder head 53 can be fastened to
the cylinder block 52 in a well-balanced manner. An oil hole 63 for
passing lubricating oil is formed on the outside of a specific bolt
insertion hole 62 so that a valve mechanism and the like can be
lubricated by supplying lubricating oil from the cylinder block 52
to the cylinder head 53.
[0097] The gasket component sheet 60 has a combustion chamber bead
65 surrounding the combustion chamber 56, an inner circumference
side stopper 67 composed of a plurality of inner auxiliary beads 66
arranged on the inner side the combustion chamber bead 65, an outer
circumference side stopper 69 composed of a plurality of outer
auxiliary beads 68 arranged on the outer side from the combustion
chamber bead 65, a bolt hole bead 70 surrounding the bolt insertion
hole 62, a bolt/oil hole bead 71 surrounding of the bolt insertion
hole 62 and oil hole 63 together, and an outer circumferential bead
72 surrounding the whole of the bolt hole beads 70 and bolt/oil
hole beads 71. It should be noted that the outer circumferential
bead 72 may be formed not to surround the bolt hole beads 70 or
bolt/oil hole beads 71 as long as it surrounds the cooling water
holes. Additionally, the bolt hole bead 70, the bolt/oil hole bead
71, and the outer circumferential bead 72 may be constituted either
by a round bead having a circular arc section or by a stepped bead
with a stepped shape.
[0098] In the gasket component sheet 60, the shapes, numbers and
arrangements of the openings 61, cooling water holes, bolt
insertion holes 62, and oil holes 63, as well as the shapes,
numbers and arrangements of the combustion chamber beads 65, bolt
hole beads 70, bolt/oil hole beads 71 and outer circumferential
beads 72 may be set arbitrarily in accordance with the
configuration of the engine or the like.
[0099] The inner circumference side stopper 67 and the outer
circumference side stopper 69 are formed into a triangular
wave-shaped cross section by three auxiliary beads 66 and 68,
respectively, which are formed substantially concentrically with
the combustion chamber bead 65. The amplitude of the waves of the
auxiliary beads 66 and 68 is set to a value smaller than the width
of the combustion chamber bead 65, and the height of the waves is
set lower than the height of the combustion chamber bead 65 in its
natural state. The auxiliary beads 66 and 68 are thus designed so
that they are hardly compressively deformed under a load exerted
when the cylinder head 53 is fastened to the cylinder block 52 with
head bolts.
[0100] The stoppers 67 and 69 and the combustion chamber bead 65
are arranged to face the top face of a cylindrical cylinder inner
peripheral wall 52a of the cylinder block 52 that is arranged
closer to the combustion chamber 56 than the water jacket 57. The
combustion chamber bead 65 is arranged in a substantially central
portion in the thickness direction of the cylinder inner peripheral
wall 52a, and the inner circumference side stopper 67 and outer
circumference side stopper 69 are spaced from the combustion
chamber bead 65 by a substantially same distance.
[0101] In addition to the triangular-wave shape, the
cross-sectional shape of the stoppers 67 and 69 may be any shape
such as a sine-wave or rectangular-wave shape. However, it is
preferable that the stoppers 67 and 69 be formed similarly to the
inner circumference side stopper 17 of the first embodiment
described above. While the number of the inner and outer auxiliary
beads 66 and 68 may be set to any value, it is preferable to set
the number to at least two or more for ensuring the functions as
stoppers. While the height of the auxiliary beads 66 and 68 may be
set to an identical value, it is preferable to set the height of
the inner auxiliary beads 66 to be slightly higher than the height
of the outer auxiliary beads 68 in order to enhance the air
tightness of the combustion chamber 56. While the inner and outer
auxiliary beads 66 and 68 may be projected to the opposite
direction from the direction the combustion chamber bead 65 is
projected, it is preferable that the auxiliary beads 66 and 68 be
projected to the same direction as the combustion chamber bead 65
is projected in order to allow the auxiliary beads 66 and 68 to
exhibit their function as stoppers for the combustion chamber bead
65 fully.
[0102] This metal gasket 51 is incorporated into an engine by
fastening the cylinder head 53 to the cylinder block 52 by means of
head bolts with the metal gasket 51 interposed between the cylinder
block 52 and the cylinder head 53. In this case, a gap is formed by
the stoppers 67 and 69 in the vicinity of the combustion chamber
bead 65 such that the height of the gap substantially corresponds
to the height of the auxiliary beads 66 and 68. As a result, the
metal gasket 51 is not compressed until the combustion chamber bead
65 comes into close contact with the top face of the cylinder inner
peripheral wall 52a. Therefore, the stress amplitude of the
combustion chamber bead 65 during operation of the engine is
reduced, and hence it is possible to prevent the deterioration of
sealing performance caused by flattening or cracks of the
combustion chamber bead 15. Additionally, the tightening load from
the head bolt is distributed over and exerted in a well-balanced
manner to the top face of the cylinder inner peripheral wall 52a by
the combustion chamber bead 65 and stoppers 67 and 69. Therefore,
the deformation in a radial direction of the cylinder inner
peripheral wall 52a can be reduced to improve the circularity of
the cylinder hole and hence to improve the engine performance.
Further, these stoppers 67 and 69 are by the stoppers 67 and 69
since they can be formed integrally with the gasket component sheet
60 by press molding or the like. Moreover, since this type of metal
gasket is free from problems such as sheet exfoliation, the
durability of the engine can be improved.
[0103] It should be noted that, as a metal gasket 51A shown in FIG.
16A, an inner circumference side stopper 67A and an outer
circumference side stopper 69A may be provided in place of the
stoppers 67 and 69, the inner and outer circumference side stoppers
67A and 69A being formed to have a flat surface on one side and
wave-shaped surface on the other side by adjusting the thickness of
the gasket component sheet 60A. Additionally, since the thermal
resistance and other properties required for the outer
circumference side stopper 69 are not as high as those for the
inner circumference side stopper 67, a metal gasket 51B may be
formed, as shown in FIG. 16B, by a gasket component sheet 60B
having no outer circumference side stopper 69 and this gasket
component sheet 60B may be provided with an outer circumference
side stopper 69B formed by depositing a synthetic resin material or
metallic material having thermal resistance and compressive
resistance by means of pattern printing, metal flame spray coating,
or material application with a dispenser, or by welding a
ring-shaped stopper plate.
[0104] Further, the metal gasket 51 may be constituted by a
plurality of gasket component sheets 60. When the metal gasket 51
is constituted by two gasket component sheets, for example, the
gasket component sheet 60 as described above may be laid directly
over another gasket component sheet. Alternatively, as a metal
gasket 80 shown in FIG. 17A, a first gasket component sheet 60C
having a combustion chamber bead 65 and an inner circumference side
stopper 67 but no outer circumference side stopper 69 may be laid
over a second gasket component sheet 81 having an outer
circumference side stopper 69. Further alternatively, as a metal
gasket 82 shown in FIG. 17B, a first gasket component sheet 60D
having a combustion chamber bead 65 and outer circumference side
stopper 69 but no inner circumference side stopper 67 may be laid
over a second gasket component sheet 83 having an inner
circumference side stopper 67. Yet further alternatively, as a
metal gasket 84 shown in FIG. 17C, a first gasket component sheet
60E having a combustion chamber bead 65 but no inner circumference
side stopper 67 or outer circumference side stopper 69 may be laid
over a second gasket component sheet 85 having an inner
circumference side stopper 67 and an outer circumference side
stopper 69.
[0105] Further, when two gasket component sheets are overlapped in
this manner, similarly to the embodiments described above, the
outer circumference side stopper 69 may be provided with an outer
circumference side stopper 69A having a flat surface on one side
and a wave-shaped surface on the other side, or with an outer
circumference side stopper 69B formed by depositing a synthetic
resin material or metallic material having thermal resistance and
compressive resistance by means of pattern printing, metal flame
spray coating, or material application with a dispenser, or by
welding a ring-shaped stopper plate. Still further, when the second
gasket component sheet 60 is provided with an outer circumference
side stopper 69, as a metal gasket 86 shown in FIG. 17D, the first
gasket component sheet 60E or 10C may be laid over a second gasket
component sheet 90 that is divided into an inner circumference side
component sheet 87 surrounding the combustion chamber 56 and an
outer circumference side component sheet 88 corresponding to the
other part, and providing, in place of the outer circumference side
stopper 69, an overlapped portion 89 of these component sheets 87
and 88.
[0106] The description of the fourth embodiment has been made so
far on metal gaskets of single-layer and two-layer configurations.
However, the present invention is also applicable to a metal gasket
having three or more gasket component sheets layered on top of
another. In such metal gasket having a plurality of gasket
component sheets, these plurality of gasket component sheets
layered on top of another are joined integrally by means of an
eyelet or mechanical clinch at a portion not including the joint
surfaces 54 and 55 of the cylinder block 52 and cylinder head 53,
for example at a portion outside of the joint surfaces 54 and 55 of
the cylinder block 52 and cylinder head 53, or at a portion where
the water jacket 57 is arranged.
[0107] Further, in the fourth embodiment, the present invention is
applied to the metal gasket 51 that is mounted between the cylinder
block 52 and the cylinder head 53 of an in-line multiple-cylinder
engine. However, the present invention is also applicable to a
single-cylinder engine or V-engine. Further, the present invention
is also well applicable to air pumps or the like in addition to
engines.
* * * * *