U.S. patent application number 10/598881 was filed with the patent office on 2007-08-09 for fuel sealing structure.
This patent application is currently assigned to SAKAMOTO INDUSTRY CO., LTD.. Invention is credited to Mamoru Fukushima, Kazuhiko Kimura, Satoshi Komada, Toru Mashimo, Noriyuki Ohsawa.
Application Number | 20070181580 10/598881 |
Document ID | / |
Family ID | 34975458 |
Filed Date | 2007-08-09 |
United States Patent
Application |
20070181580 |
Kind Code |
A1 |
Kimura; Kazuhiko ; et
al. |
August 9, 2007 |
Fuel sealing structure
Abstract
To provide a fuel sealing structure capable of preventing the
leakage of not only liquid fuel but also gasified fuel, an annular
packing 30 is interposed between an annular sealing surface 15 on
an opening part 11 of a container 20 and an annular sealing surface
25 of a closure 20. The distance between the second regions 15b,
25b of the sealing surfaces 15, 25 is shorter than that between the
first regions 15a, 25a. The packing 30 includes a first sealing
part 31 sandwiched between the first regions 15a,25a and a second
sealing part 32 sandwiched between the 15b, 25b. The second sealing
part 32 is smaller in thickness than the first sealing part 31 and
the difference of the thicknesses is larger than the difference of
distances between the above-mentioned regions. With the closure 20
attached, the compression ratio of the second sealing part 32 is
smaller than that of the first sealing part 31.
Inventors: |
Kimura; Kazuhiko; (Gunma,
JP) ; Mashimo; Toru; (Gunma, JP) ; Fukushima;
Mamoru; (Gunma, JP) ; Ohsawa; Noriyuki;
(Gunma, JP) ; Komada; Satoshi; (Gunma,
JP) |
Correspondence
Address: |
Stephen B. Salai, Esq.;Harter, Secrest & Emery LLP
1600 Bausch & Lomb Place
Rochester
NY
14604-2711
US
|
Assignee: |
SAKAMOTO INDUSTRY CO., LTD.
292 Bessho-cho
Ohta-city, Gunma
JP
|
Family ID: |
34975458 |
Appl. No.: |
10/598881 |
Filed: |
March 14, 2005 |
PCT Filed: |
March 14, 2005 |
PCT NO: |
PCT/JP05/04418 |
371 Date: |
October 5, 2006 |
Current U.S.
Class: |
220/304 |
Current CPC
Class: |
B65D 41/045
20130101 |
Class at
Publication: |
220/304 |
International
Class: |
B65D 53/00 20060101
B65D053/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 15, 2004 |
JP |
2004-072794 |
Claims
1. A fuel sealing structure comprising a container for storing fuel
and having an opening part, a closure attached to the opening part
of said container, and an annular packing interposed in a
compressed condition between an annular sealing surface of said
opening part of said container and an annular sealing surface of
said closure, wherein said sealing surfaces of said container and
closure each include an annular first region and an annular second
region, and a distance between said second regions of said two
sealing surfaces is shorter than that between said first regions,
said packing includes a first sealing part sandwiched between said
first regions of said two sealing surfaces and a second sealing
part sandwiched between said second regions of said two sealing
surfaces, said first and second sealing parts are, in their
compressed condition, interposed between said sealing surfaces,
said second sealing part is smaller in thickness than said first
sealing part in a natural condition, and this difference in
thickness is larger than the difference between said distance
between said first regions and said distance between said second
regions.
2. A fuel sealing structure according to claim 1, wherein a
compression ratio of said second sealing part is smaller than that
of said first sealing part when said closure is in an attached
condition.
3. A fuel sealing structure according to claim 1 or 2, wherein said
first sealing part is located radially inside of said second
sealing part.
4. A fuel sealing structure according to claim 1 or 2, wherein one
of said sealing surfaces of said container and closure is a plane
with said first and second regions made flush with each other, and
the other sealing surface includes a step at a boundary between
said first and second regions, one surface of said packing is a
plane corresponding to said one sealing surface, and the other
surface includes a step corresponding to the other sealing
surface.
5. A fuel sealing structure according to claim 1 or 2, wherein an
annular projection is formed on one of said sealing surface of said
container and said sealing surface of said closure, a top surface
of said projection is provided as said second region, a radial
inside and a radial outside of said projection in said one sealing
surface are provided as said first regions, the other sealing
surface includes said second region and said first regions disposed
radially inside and outside of said second region on a same plane
in correspondence to one sealing surface, and said packing includes
said thin second sealing part corresponding to said projection and
said thick first sealing parts located radially inside and outside
of said second sealing part.
Description
TECHNICAL FIELD
[0001] This invention relates to a fuel sealing structure.
BACKGROUND ART
[0002] It is known to interpose an annular packing between an
opening part of a container such as a fuel tank and a closure in
order to prevent the leakage. FIG. 10 of Japanese Patent
Application Laid-Open No. 2002-337916 discloses a packing having a
uniform thickness. This packing is interposed between an annular
sealing surface on an opening part of a container and an annular
sealing surface of a closure. The two sealing surfaces are planar
surfaces (planes) which are parallel to each other. At the time of
attaching the closure, the packing is uniformly compressed by the
two sealing surfaces. The two surfaces of the compressed packing
are adhered to the seating surface on the container and the sealing
surface on the closure with a predetermined pressure, respectively,
thereby preventing the leakage of fuel.
DISCLOSURE OF THE INVENTION
Problem to be Solved by the Invention
[0003] In the fuel sealing structure of the Japanese Patent
Application Laid-Open No. 2002-337916, in case the packing is
thick, the amount of the gasified fuel permeated through the rubber
material of the packing is increased. In order to restrain the
amount of permeating fuel, it is necessary to reduce the permeating
sectional area by making the packing thinner. In case the packing
is made thinner, however, there arises another inconvenience. This
inconvenience will be described with reference to FIG. 7.
[0004] FIG. 7 shows the changes of compression ratio of the packing
in accordance with movement of the closure in the axial direction.
In FIG. 7, the axial movement of the closure from the time the
attachment of the closure is started until the time the compression
of the packing is started is omitted. In other words, the amount of
movement of the closure is set to zero at the time of starting of
the compression. As the closure is moved in the axial direction,
the compression ratio of the packing is increased. This change, in
case the packing is thin, is great compared with the packing that
is thick.
[0005] At the time the closure is pushed in for a predetermined
amount, the attachment of the closure is completed. There can be
found some error in amount of axial movement of the closure until
the closure reaches the attachment completing position. As
mentioned above, in case the packing is thin, the change of
compression ratio of the packing is large per unit of movement of
the closure. Accordingly, the error of compression ratio becomes
large corresponding to the error of the amount of axial movement of
the closure, and there is a possibility that the error of
compression ratio is out of the allowable range of error. When the
actual compression ratio of the packing exceeds the upper limit of
the allowable range of error, breakage of the packing occurs, and
when the ratio becomes lower than the lower limit of the allowable
range of error, the adhering force between the packing and sealing
surfaces of the container and closure is lowered and thus, the
sealability of the liquid fuel is lowered.
Means for Solving the Problem
[0006] To solve the above problem, the present invention provides a
fuel sealing structure comprising a container for storing fuel and
having an opening part, a closure attached to the opening part of
the container, and an annular packing interposed in a compressed
condition between an annular sealing surface of the container and
an annular sealing surface of the closure, wherein the sealing
surfaces of the container and closure each include an annular first
region and an annular second region disposed radially inside or
outside of the first region, and a distance between the second
regions of the two sealing surfaces is shorter than that between
the first regions, the packing includes a first sealing part
sandwiched between the first regions of the two sealing surfaces
and a second sealing part sandwiched between the second regions of
the two sealing surfaces, the first and second sealing parts are,
in their compressed condition, interposed between the sealing
surfaces, the second sealing part is smaller in thickness than the
first sealing part in a natural condition, and this difference in
thickness is larger than the difference between the distance
between the first regions and the distance between the second
regions.
[0007] Owing to the above construction, in the first sealing part,
the change of compression ratio with respect to the amount of axial
movement of the closure is gentle, the compression ratio can be
managed with a comparatively high precision, and the change of
compression ratio can be set within an allowable range. As a
result, the packing can be adhered to the sealing surface of the
container and the sealing surface of the closure with a sufficient
pressure without the occurrence of breakage of the packing, and the
leakage of liquid fuel can reliably be prevented. In the second
sealing part, since the packing is smaller in thickness than in the
first sealing part and the permeating sectional area is small, the
permeation of the gasified fuel can be restrained. Moreover, since
the difference of thickness between the first and second sealing
parts is larger than the difference between the distance between
the first regions and the distance between the second regions, the
amount of compression of the second sealing part is smaller than
that of the first sealing part, the overly compression of the
second sealing part can be avoided, and the breakage of the packing
at its second sealing part can be prevented.
[0008] Preferably, a compression ratio of the second sealing part
is smaller than that of the first sealing part when the closure is
in an attached condition. Owing to this arrangement, even if some
error occurs at the attaching position of the closure, the overly
compression of the second sealing part can reliably be
prevented.
[0009] Preferably, the first sealing part is located radially
inside of the second sealing part. Owing to this arrangement, the
liquid fuel is prohibited in the first sealing part and does not
reach the second sealing part. Thus, the second sealing part can
limit its task only to prevention of permeation of a small amount
of gasified fuel, the amount of compression can be reduced
extensively, and breakage of the packing at the second sealing part
can more reliably be prevented.
[0010] In one embodiment, one of the sealing surfaces of the
container and closure is a plane with the first and second regions
made flush with each other, and the other sealing surface includes
a step at a boundary between the first and second regions, one
surface of the packing is a plane corresponding to the one sealing
surface, and the other surface includes a step corresponding to the
other sealing surface. Owing to this arrangement, the effect of the
present invention can be obtained with a comparatively simple
packing structure and sealing surface configuration.
[0011] In another embodiment, an annular projection is formed on
one of the sealing surface of the container and the sealing surface
of the closure, a top surface of the projection is provided as the
second region, a radial inside and a radial outside of the
projection in the one sealing surface are provided as the first
regions, the other sealing surface includes the second region and
the first regions disposed radially inside and outside of the
second region on a same plane in correspondence to one sealing
surface, and the packing includes the thin second sealing part
corresponding to the projection and the thick first sealing parts
located radially inside and outside of the second sealing part.
Owing to this arrangement, two sealing parts are employed and thus,
liquid tightness can be enhanced.
[0012] According to another aspect of the present invention, there
is provided a fuel sealing structure comprising a container for
storing fuel and having an opening part, a closure attached to the
opening part of the container, and an annular packing interposed in
a compressed condition between an annular sealing surface of the
container and an annular sealing surface of the closure, wherein an
annular elastically deformable permeation restraining plate having
a lower fuel permeability than material of the packing is embedded
in the packing, the permeation restraining plate extends radially
of the packing, a distance between the permeation restraining plate
and one surface of the packing is shorter than that between the
permeation restraining plate and the other surface of the packing
at a certain annular part but a distance between the permeation
restraining plate and the other surface of the packing is shorter
than that between the permeation restraining plate and the one
surface of the packing at other annular part.
[0013] Owing to the above construction, the gasified fuel is
divided into two groups and permeates the packing material through
one and the other sides of the permeation restraining plate. The
first group of gasified fuel passing through one side of the
permeation restraining plate is restrained in permeation at a place
having a small permeating sectional area between a certain annular
part of the permeation restraining plate and one surface of the
packing, and the second group of gasified fuel passing through the
other side of the permeation restraining plate is restrained in
permeation at a place having a small permeating sectional area
between the other annular part of the permeation restraining plate
and the other surface of the packing. As a result, the total amount
of the permeating gasified fuel can be restrained. Moreover, the
packing is not required to be made thin in order to restrain the
permeation of gasified fuel and the change of compression ratio can
be made gentle with respect to the amount of axial movement of the
closure. Thus, the compression ratio can be managed with a
comparatively high precision and set within an allowable range. As
a result, the packing can be adhered to the sealing surface of the
container and the sealing surface of the closure with a sufficient
pressure without the occurrence of breakage of the packing, and the
leakage of liquid fuel can reliably be prevented.
[0014] Preferably, both surfaces of the packing are planes and have
a uniform thickness, and the permeation restraining plate is
inclined at a surface connecting the certain annular part and the
other annular part together. Owing to this arrangement, the packing
can be made simple in structure.
Effect of the Invention
[0015] According to the present invention, a liquid fuel can
satisfactorily be sealed. Also, a gasified fuel can satisfactorily
be restrained in permeation. Moreover, breakage of the packing can
be avoided.
BRIEF DESCRIPTION OF DRAWINGS
[0016] FIG. 1 is a vertical sectional view of a fuel sealing
structure according to a first embodiment of the present
invention.
[0017] FIG. 2 is an enlarged vertical sectional view of the sealing
structure, showing a state of a packing immediately before its
first sealing part is compressed.
[0018] FIG. 3 is an enlarged vertical sectional view of the sealing
structure, showing a state of the packing wherein its first and
second sealing parts are compressed and attachment of a closure is
completed.
[0019] FIG. 4 is a graph showing the change of the compression
ratios of the first and second sealing parts of the packing.
[0020] FIG. 5 is an enlarged vertical sectional view of a fuel
sealing structure according to a second embodiment of the present
invention.
[0021] FIG. 6 is an enlarged vertical sectional view of a fuel
sealing structure according to a third embodiment of the present
invention.
[0022] FIG. 7 is a graph showing the change of the compression
ratios when a thin packing is used in the conventional fuel sealing
structure.
DESCRIPTION OF REFERENCE NUMERALS
[0023] 10 . . . fuel tank (container) [0024] 11 . . . opening part
[0025] 15 . . . sealing surface [0026] 15a . . . first region
[0027] 15b . . . second region [0028] 20 . . . pump (closure)
[0029] 25 . . . sealing surface [0030] 25a . . . first region
[0031] 25b . . . second region [0032] 29 . . . projection [0033] 30
. . . packing [0034] 31 . . . first sealing part [0035] 32 . . .
second sealing part [0036] 50 . . . permeation restraining
plate
BEST MODE FOR CARRYING OUT THE INVENTION
[0037] A fuel sealing structure according to a first embodiment of
the present invention will be described hereinafter with reference
to FIGS. 1 through 4. In FIG. 1, reference numeral 10 denotes a
fuel tank (container). The fuel tank includes a cylindrically
projecting opening part 11. A screw 12 is formed on the outer
periphery of this opening part 11.
[0038] A pump 20 (closure) can be attached to the opening part 11.
An annular flange 21 projects from the outer periphery of the pump
20. An annular packing 30 is interposed in its compressed condition
between a lower surface of the flange 21 and an upper end surface
of the opening part 11 of the fuel tank 10.
[0039] The sealing structure further includes a cylindrical lock
nut 40. A radially inwardly projecting annular hook part 41 is
formed on an upper end of this lock nut 40 and a screw 42 is formed
on an inner periphery of the lock nut 40. By bringing the lock nut
40 into threading engagement with the opening part 11 and
tightening the lock nut 40, the hook part 41 is abutted with the
flange 21 of the pump 20 such that the flange 21 is pushed
downward. By this, the packing 30 is compressed to exhibit the
sealing performance.
[0040] The details of the sealing structure will now be described
with reference to FIGS. 2 and 3. FIG. 2 shows the packing 30
immediately before it is compressed during the threading engagement
process of the lock nut 40, and FIG. 3 shows the compressed packing
30 when the tightening of the lock nut 40 is completed (the
attachment of the pump 20 is completed).
[0041] The upper end surface of the opening part 11 is provided as
an annular sealing surface 15. This sealing surface 15 is stepped
and includes a lower annular first region 15a and a higher annular
second region 15b. In this embodiment, the second region 15b is
located radially outside of the first region 15a. The lower surface
of the flange 21 of the pump 20 is also provided as an annular
sealing surface 25. This sealing surface 25 includes an annular
first region 25a faced with the first region 15a of the sealing
surface 15 and an annular second region 25b faced with the second
region 15b. Those regions 15a, 15b, 25a, 25b constitute planes
orthogonal to the axes of the opening part 11 and the pump 20. The
regions 25a, 25b are flush with each other, and the sealing surface
25 is a continuous planar surface.
[0042] The packing 30 integrally includes a first sealing part 31
disposed between the first regions 15a, 25a and a second sealing
part 32 disposed between the second regions 15b, 25b. An upper
surface of the packing 30 is a planar surface and provided as an
adhesion surface with the sealing surface 25 of the flange 21. A
lower surface of the packing 30 is stepped. This step of the lower
surface of the packing 30 corresponds to that of the sealing
surface 15. The lower surface includes the two annular planar
surfaces, which are provided as adhesion surfaces to be adhered to
the regions 15a, 15b of the sealing surface 15.
[0043] As shown in FIG. 2, a thickness THb of the second sealing
part 32 in a natural condition (non-compressed condition) is
smaller than a thickness THa of the first sealing part 31 in a
natural condition. This thickness difference .DELTA.TH
(.DELTA.TH=THa-THb) is larger than a height of the step S between
the regions 15a, 15b in the sealing surface 15. Because of this
reason, with the flange 21 of the pump 20 merely placed on the
packing 30, the upper and lower surfaces of the first sealing part
31 is in contact with the first regions 15a, 25a of the sealing
surfaces 15, 25 and the upper surface of the second sealing part 32
is in contact with the second region 25b of the sealing surface 25.
However, the lower surface of the second sealing part 32 is spaced
away by a distance y (y=.DELTA.TH-S) from the second region 15b of
the sealing surface 15.
[0044] The above-mentioned step S refers to a difference between
the distance between the first regions 15a, 25a and the distance
between the second regions 15b, 25b at the time of beginning of the
attachment of the pump 20 or completion of the attachment.
[0045] As previously mentioned, when the lock nut 40 is threadingly
engaged with the opening part 11, first, the first sealing part 31
begins to be compressed. When the threading engagement of the lock
nut 40 is further progressed to push down the flange 21 of the pump
20 in the axial direction by y (y=.DELTA.TH-S), the second sealing
part 32 begins to be compressed. As shown in FIG. 3, by further
progressing the threading engagement of the lock nut 40 to push
down the flange 21 in the axial direction by .DELTA. y, attachment
of the pump 20 is completed.
[0046] The compression ratio R1 of the first sealing part 31 at the
time of completion of the attachment can be expressed by the
following equation. R1=(y+.DELTA.y)/THa (1)
[0047] Likewise, the compression ratio R2 of the second sealing
part 32 can be expressed by the following equation. R2=.DELTA.y/THb
(2)
[0048] The compression ratio R2 of the second sealing part 32 is
smaller than the compression ratio R1 of the first sealing part
31.
[0049] Changes of the compression ratios of the first and second
sealing parts 31, 32 in accordance with the axial movement of the
pump 20 are shown in FIG. 4.
[0050] As mentioned above, the compression ratio of the first
sealing part 31 at the time of completion of the attachment of the
pump 20 is such high as, for example, 10%, and its upper and lower
surfaces are adhered to the first regions 15a, 25a of the sealing
surfaces 15, 25 with a strong adhering force. Accordingly, the
leakage of the liquid fuel can reliably be prevented. Since the
thickness THa of the first sealing part 31 is large, the sectional
area through which the gasified fuel permeates the rubber material
is large and the function for restraining the permeation of the
gasified fuel is lower than the second sealing part 32 as later
described.
[0051] The compression ratio of the second sealing part 32 at the
time of completion of the attachment of the pump 20 is such low as,
for example, 3%, and its upper and lower surfaces are adhered to
the second regions 15b, 25b of the sealing surfaces 15, 25 with a
weak adhering force. Accordingly, the function for preventing the
leakage of the liquid fuel is weaker than the first closure 31.
However, since the thickness THb of the second sealing part 32 is
small and the permeating sectional area is small, the function for
restraining the permeation of the gasified fuel is high.
[0052] As mentioned above, by preventing the leakage of liquid fuel
mainly at the first sealing part 31 and restraining the permeation
of gasified fuel mainly at the second sealing part 32, a
satisfactory fuel-sealing characteristic can be obtained.
[0053] Some error of the compression ratio may occur due to error
of the axial position of the flange 21 at the time of completion of
the attachment of the pump 20. However, since the thickness THa of
the first sealing part 31 is large and the change of the
compression ratio with respect to the amount of axial movement of
the flange 21 is comparatively small, this compression ratio can be
set within an allowable range of error. As a result, breakage due
to overly high compression ratio does not occur and leakage of
liquid fuel due to overly low compression ratio does not occur,
either.
[0054] Since the thickness THa of the second sealing part 32 is
small and the change of the compression ratio with respect to the
amount of axial movement of the flange 21 is comparatively large,
the error of compression ratio becomes large. However, since the
compression ratio R2 is set to be lower than that of the first
sealing part 31, the error is lower than the upper limit of the
allowable range of error and the breakage can reliably be
prevented. Since the lower limit of the range of error of the
compression ratio of the second sealing part 32 is set to be equal
to or higher than 1%, the gasified fuel never leaks between the
second sealing part 32 and the second regions 15b, 25b of the
sealing surfaces 15, 25.
[0055] Other embodiments of the present invention will be described
next. In those embodiments, the component parts corresponding to
the preceding embodiment are denoted by identical reference numeral
and detailed description thereof will be omitted. FIG. 5 shows a
second embodiment of the present invention. An annular projection
29 is formed on a sealing surface 25 of a flange 21. A flat surface
of this projection 29 is provided as a second region 25b of the
sealing surface 25, and the radially inside and outside of a
projection 29 are provided as a first region 25a. On the other
hand, a sealing surface 15 on an opening part 11 includes, on a
same plane, an annular second region 15b corresponding to the
second region 25b and a first region 15 located radially inside and
outside of the second region 25b. A packing 30 includes an annular
groove corresponding to the projection 29 and a bottom part of this
groove is provided a second sealing part 32, and the radially
inside and outside parts of the second sealing part 32 is provided
as a first sealing part 31 having a large thickness. The dimensions
and compression ratios of the various component parts in this
embodiment are same as in the first embodiment. In this embodiment,
by using the first sealing parts 31 at two places, the liquid tight
characteristic can further be enhanced.
[0056] FIG. 6 shows a third embodiment of the present invention. In
this embodiment, an annular permeation restraining plate 50, which
is made of material having a lower permeation ratio than the rubber
material of the packing 30 such as, for example, metal and resin,
is embedded in a packing 30 whose upper and lower surfaces are
planar surfaces and having a uniform thickness. This permeation
restraining plate 50 has a same sectional configuration over the
entire periphery. The plate 50 is thin and elastically deformable
and extends in the radial direction of the packing 30. At certain
annular parts 51, 52 of the permeation restraining plate 50, a
distance between an upper surface (one surface) of the packing 30
and the permeation restraining plate 50 is smaller than a distance
between a lower surface (the other surface) and the permeation
restraining plate 50, thereby providing annular regions each having
a smaller permeating sectional area in the packing 30. At another
annular part 53, a distance between the lower surface of the
packing 30 and permeation restraining plate 50 is smaller than a
distance between the upper surface and the permeation restraining
plate 50, thereby providing an annular region having a small
permeating sectional area in the packing 30. The sealing surfaces
15, 25 form planar surfaces respectively corresponding to the upper
and lower surfaces of the packing 30.
[0057] In the third embodiment, the packing 30 has a comparatively
large thickness like the first sealing part 31 of the first
embodiment. Accordingly, the packing 30 exhibits a performance on a
satisfactory level with respect to the prevention of leakage of the
liquid fuel caused by compression thereof. The permeation
restraining plate 50 undertakes the permeation preventing function
of the gasified fuel. That is, the gasified gas tries to permeate
the packing 50 in two groups owing to a provision of the permeation
restraining plate 50. The gasified fuel permeating through the
upper side of the permeation restraining plate 50 is restrained in
permeation here because the distance between the annular parts 51,
52 and the upper surface of the packing 30 is short and the
permeating sectional area is small. On the other hand, the gasified
fuel permeating through the lower side of the permeation
restraining plate 50 is restrained in permeation here because the
distance between the annular part 53 and the lower surface of the
packing 30 is short and the permeating sectional area is small. In
this manner, the total amount of permeation of the gasified fuel
can be restrained.
[0058] The present invention is not limited to the above-mentioned
embodiments but many other embodiments may also be employed. For
example, a step may be formed on the sealing surface 25 in the
first embodiment. The projection 29 may be formed on the sealing
surface 15 in the second embodiment. It is also accepted that the
closure is a normal cover instead of the pump.
INDUSTRIAL APPLICABILITY
[0059] The present invention is applicable to a sealing structure
for a fuel tank of automotive vehicles or the like.
* * * * *