U.S. patent application number 15/039506 was filed with the patent office on 2016-12-29 for fluid apparatus.
The applicant listed for this patent is NIPPON PILLAR PACKING CO., LTD.. Invention is credited to Tomohiro Adachi, Makoto Fujii, Tatsuya Fujii, Shintaro Makihata, Masaki Miyamoto, Masaya Shiomi, Masateru Yamada, Kenji Yamazaki.
Application Number | 20160377071 15/039506 |
Document ID | / |
Family ID | 53273320 |
Filed Date | 2016-12-29 |
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United States Patent
Application |
20160377071 |
Kind Code |
A1 |
Fujii; Tatsuya ; et
al. |
December 29, 2016 |
FLUID APPARATUS
Abstract
A fluid apparatus includes a bellows that is configured to be
extendable and contractible in an axial direction in order to suck
a fluid from a suction flow passage and eject the fluid to an
ejection flow passage. The bellows has peak portions and valley
portions, which are alternately formed in the axial direction, and
annular side surface portions, which are located between the peak
portions and the valley portions and connect the peak and valley
portions to each other. A ratio B/A of the thickness B of the axial
middle part of each of the peak portions in a direction which is
perpendicular to the axial direction, to the thickness A of each of
the side surface portions in the axial direction is set within a
range of 1.3 to 1.8.
Inventors: |
Fujii; Tatsuya; (Osaka-shi,
JP) ; Fujii; Makoto; (Osaka-shi, JP) ;
Miyamoto; Masaki; (Osaka-shi, JP) ; Yamada;
Masateru; (Osaka-shi, JP) ; Makihata; Shintaro;
(Osaka-shi, JP) ; Adachi; Tomohiro; (Osaka-shi,
JP) ; Shiomi; Masaya; (Osaka-shi, JP) ;
Yamazaki; Kenji; (Osaka-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NIPPON PILLAR PACKING CO., LTD. |
Osaka-shi, Osaka |
|
JP |
|
|
Family ID: |
53273320 |
Appl. No.: |
15/039506 |
Filed: |
November 20, 2014 |
PCT Filed: |
November 20, 2014 |
PCT NO: |
PCT/JP2014/080761 |
371 Date: |
May 26, 2016 |
Current U.S.
Class: |
417/472 |
Current CPC
Class: |
F04B 43/0072 20130101;
F04B 43/0081 20130101; F04B 43/113 20130101; F04B 45/02 20130101;
F04B 53/16 20130101; F04B 43/10 20130101; F16J 3/043 20130101; F16J
3/06 20130101 |
International
Class: |
F04B 43/00 20060101
F04B043/00; F04B 53/16 20060101 F04B053/16; F04B 43/10 20060101
F04B043/10 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 5, 2013 |
JP |
2013-252114 |
Claims
1. A fluid apparatus including a bellows which is configured to be
extendable and contractible in an axial direction in order to suck
a fluid from a suction flow passage and eject the fluid to an
ejection flow passage, wherein the bellows comprises: peak portions
and valley portions which are alternately formed in the axial
direction; and annular side surface portions which are located
between the peak portions and the valley portions, and which
connect the both portions to each other, and a ratio B/A of a
thickness B of the axial middle part of each of the peak portions
in a direction which is perpendicular to the axial direction, to a
thickness A of each of the side surface portions in the axial
direction is set within a range of 1.3 to 1.8.
2. The fluid apparatus according to claim 1, wherein the ratio B/A
of the thickness B of the axial middle part of each of the peak
portions in the direction which is perpendicular to the axial
direction, to the thickness A of each of the side surface portions
in the axial direction is set within a range of 1.3 to 1.5.
3. The fluid apparatus according to claim 1, wherein, when the
bellows is maximally contracted in the axial direction, each of
side surface portions is located in a plane which is substantially
perpendicular to the axial direction of the bellows.
4. The fluid apparatus according to claim 2, wherein, when the
bellows is maximally contracted in the axial direction, each of
side surface portions is located in a plane which is substantially
perpendicular to the axial direction of the bellows.
Description
TECHNICAL FIELD
[0001] The present invention relates to a fluid apparatus including
a bellows.
BACKGROUND ART
[0002] As a fluid apparatus including a bellows which is configured
to be extendable and contractible in the axial direction in order
to allow a fluid to flow, a bellows pump, a pulsation damping
device, and the like are known (for example, see Patent Literature
1).
[0003] In a fluid apparatus of this kind, as shown in FIG. 11(a), a
bellows has peak portions 157 and valley portions 158 which are
alternately formed in the axial direction, and annular side surface
portions 159 which are located between the peak portions 157 and
the valley portions 158, and which connect the both portions to
each other. The bellows is configured so as to, when the fluid
apparatus operates, extendable and contractible in the axial
direction.
[0004] When the thickness of each of the side surface portions 159
in the axial direction is indicated by A, and that of each of the
axial middle parts (apex portions) of the peak portions 157 in a
direction which is perpendicular to the axial direction is
indicated by B, the bellows are set so that a ratio B/A is 1. That
is, the thickness A of the side surface portions and the thickness
B of the peak portions are equal to each other.
[0005] When the bellows is extended, therefore, the peak portion
157 is preferentially deformed to be stretched in the axial
direction as shown in FIG. 11(b), and large stress is
concentrically generated in a specific narrow place 160 which is in
the inner side of the axial middle part of the peak portion 157,
and the axial middle part of the peak portion 157 easily fatigues.
As a result, there arises a possibility that a crack 161 which
extends in a direction perpendicular to the axial direction occurs
in the axial middle part of the peak portion 157 where stress
concentration occurs.
PRIOR ART LITERATURE
Patent Literature
Patent Literature 1: Japanese Patent Application Laid-Open No.
6-50265
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
[0006] The inventors have thought that, the larger the thickness B
of the middle part with respect to the thickness A of the side
surface portion in order to prevent the crack 161 from occurring,
the higher the rigidity of the middle part, and the crack 161 can
be prevented from occurring. Even when the rigidity is enhanced,
however, the stress concentration in the middle does not disappear.
Therefore, there is a fear that, when the bellows is used for a
long term, a crack may occur in the middle part because of
fatigue.
[0007] When the inventors have repeated a process of trial and
error in order to prevent a crack due to fatigue from occurring,
the inventors have found that, when the ratio B/A of the thickness
B of the peak portion in a direction which is perpendicular to the
axial direction, to the thickness A of the side surface portion in
the axial direction is limitedly set within a certain range, stress
concentration in the middle part is remarkably reduced, and
occurrence of a crack such as above described can be suppressed.
The invention has been accomplished based on this finding.
[0008] The invention has bee conducted in view of the above
circumstances. It is an object of the invention to provide a fluid
apparatus in which a crack due to extension and contraction of a
bellows can be suppressed from occurring in an axial middle part of
a peak portion of the bellows.
Means for Solving the Problem
[0009] The invention of claim 1 is a fluid apparatus including a
bellows which is configured to be extendable and contractible in an
axial direction in order to suck a fluid from a suction flow
passage and eject the fluid to an ejection flow passage, wherein
the bellows has: peak portions and valley portions which are
alternately formed in the axial direction; and annular side surface
portions which are located between the peak portions and the valley
portions, and which connect the both portions to each other, and a
ratio B/A of a thickness B of the axial middle part of each of the
peak portions in a direction which is perpendicular to the axial
direction, to a thickness A of each of the side surface portions in
the axial direction is set within a range of 1.3 to 1.8.
[0010] According to the configuration, when the bellows is
extended, large stress dispersedly occurs on the side of the inner
circumferential surface of each of the peak portions which are
stretched in the axial direction. Namely, large stress which is
caused in the peak portion in this case is not concentrated in a
specific narrow place. Therefore, the axial middle part of the peak
portion which is deformable in accordance with extension and
contraction of the bellows can be made not easily fatigued.
Consequently, a crack which is due to extension and contraction of
the bellows, and which extends in a direction perpendicular to the
axial direction can be suppressed from occurring in the axial
middle part of the peak portion. As a result, the bellows is hardly
broken, and a prolonged life period of the bellows can be
realized.
[0011] The invention of claim 2 has a configuration where, in the
fluid apparatus set forth in claim 1, the ratio B/A of the
thickness B of the axial middle part of each of the peak portions
in the direction which is perpendicular to the axial direction, to
the thickness A of each of the side surface portions in the axial
direction is set within a range of 1.3 to 1.5.
[0012] According to the configuration, even in the case of severe
use conditions such as those where the temperature of the fluid is
higher than the ordinary temperature (room temperature), when the
bellows is extended in the axial direction, large stress which is
caused in the peak portion is not concentrated in a specific narrow
place. Even in such a case, therefore, a crack which is due to
extension and contraction of the bellows can be suppressed from
occurring in the axial middle part of the peak portion of the
bellows. A prolonged life period of the bellows can be
realized.
[0013] The invention of claim 3 has a configuration where, in the
fluid apparatus set forth in claim 1 or 2, when the bellows is
maximally contracted in the axial direction, each of side surface
portions is located in a plane which is substantially perpendicular
to the axial direction of the bellows.
Effects of the Invention
[0014] According to the invention, it is possible to provide a
fluid apparatus in which a crack due to extension and contraction
of a bellows can be suppressed from occurring in an axial middle
part of a peak portion of the bellows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a side sectional view of a pump device which is a
fluid apparatus of an embodiment of the invention.
[0016] FIG. 2 is a partial enlarged sectional view of a bellows in
the pump device.
[0017] FIG. 3 is a partial enlarged sectional view of a bellows
portion of the bellows.
[0018] FIG. 4 is a comparison view of the maximum value of stress
which, in the case where the temperature of a fluid is 20.degree.
C., occurs in a peak portion when the bellows is extended.
[0019] FIG. 5 is a comparison view of the maximum value of stress
which, in the case where the temperature of the fluid is 70.degree.
C., occurs in a peak portion when the bellows is extended.
[0020] FIG. 6 is a partial enlarged sectional view of a
modification of the bellows portion of the bellows.
[0021] FIG. 7 is another partial enlarged sectional view of the
bellows in the pump device.
[0022] FIG. 8 is a partial enlarged sectional view of a bellows in
another example.
[0023] FIG. 9 is a side sectional view of a pulsation damping
device which is a fluid apparatus of another embodiment of the
invention.
[0024] FIG. 10 is a side sectional view of a bellows pump which is
a fluid apparatus of a further embodiment of the invention.
[0025] FIG. 11 is a partial enlarged sectional view of a bellows in
a fluid apparatus of a conventional example.
BEST MODE FOR CARRYING OUT THE INVENTION
[0026] Preferred embodiments of the invention will be described
with reference to the drawings.
[0027] The fluid apparatus of the invention is a bellows pump, a
pulsation damping device, or the like, and, for example, used for
transporting a fluid such as ultrapure water or chemical liquid in
a facility for producing a semiconductor or liquid crystal.
[0028] FIG. 1 is a side sectional view of a pump device 1 which is
a fluid apparatus of an embodiment of the invention.
[0029] As shown in FIG. 1, the pump device 1 includes a bellows
pump 2, and a pulsation damping device 3 which is juxtaposed to the
bellows pump 2. The bellows pump 2 and the pulsation damping device
3 have a common partition wall 5, and are placed coaxially with
each other. In the partition wall 5, a suction flow passage 6,
intermediate flow passage 7, and ejection flow passage 8 for a
fluid are formed.
[0030] The bellows pump 2 includes the bellows 10. The bellows 10
is configured so as to be extendable and contractible in the axial
direction (the lateral direction in FIG. 1) in order to suck the
fluid from the suction flow passage 6 and eject the fluid to the
intermediate flow passage 7 which functions as an ejection flow
passage. In the embodiment, a bottomed cylinder-like pump casing 11
is attached to a side wall portion of the partition wall 5 on one
axial end side (the right side in FIG. 1), and the bellows 10 is
placed in the pump casing 11.
[0031] The bellows 10 is configured by a fluorine resin (in the
embodiment, polytetrafluoroethylene (PTFE)). The bellows 10 is
formed by cutting a cylindrical member made of
polytetrafluoroethylene on a lathe by using a stick bite or a
knife.
[0032] The bellows 10 has an opening peripheral edge portion 12 on
the other axial end side (the left side in FIG. 1). The opening
peripheral edge portion 12 is fixed in an airtight state to a side
wall portion of the partition wall 5 on the one axial end side by a
first annular fixing plate 13. In this way, the internal space of
the pump casing 11 is hermetically partitioned by using the bellows
into a pump working chamber 14 which is located inside the bellows
10, and a pump operating chamber 15 which is located outside the
bellows 10.
[0033] The bellows 10 further has a closed end portion 21 on the
one axial end side (the right side in FIG. 1). The bellows 10 has a
cylindrical bellows portion 22 between the closed end portion 21
and the opening peripheral edge portion 12 so as to be extendable
and contractible in the axial direction. In the bellows portion 22,
peak portions 17, valley portions 18, and side surface portions 19,
which will be described later, are provided (see FIG. 2).
[0034] In the bellows pump 2, moreover, a suction port 41 and
discharge port 42 for a fluid communicate with the interior of the
pump working chamber 14. The suction port 41 communicates with the
suction flow passage 6, and the discharge port 42 communicates with
the intermediate flow passage 7. A first check valve 43 and second
check valve 44 which can be alternately opened and closed in
accordance with extending and contracting operations of the bellows
10, and which are of the resin-made spring type are disposed in the
middles of the suction flow passage 6 and the intermediate flow
passage 7.
[0035] A coupling member 46 is disposed in the pump operating
chamber 15. The coupling member 46 is fixed to the closed end
portion 21 of the bellows 10 by using a second annular fixing plate
206 and bolts 207. A shaft member 47 is coupled to the coupling
member 46. The shaft member 47 is disposed so as to be passed from
the interior of the pump operating chamber 15 through a
substantially middle of a bottom wall portion of the pump casing 11
to be projected to the outside. A piston 48 is fixed to a projected
portion of the shaft member 47.
[0036] The piston 48 is fitted into a cylinder 49 fixed to the
bottom wall portion of the pump casing 11, in an axially slidable
manner. An air cylinder 53 which is driving means for extending and
contracting the bellows 10 is configured so as to be able to
alternately supply pressurized air from an air compressor or the
like which is not shown, to the pump operating chamber 15 and the
internal space surrounded by the cylinder 49 and the piston 48
through air holes 51, 52 that are formed in the bottom wall portion
of the pump casing 11, and the cylinder 49, respectively.
[0037] Proximity sensors 55, 56 are attached to the air cylinder
53, and a sensor sensing plate 57 is attached to the piston 48. In
accordance with the axial reciprocal motion of the piston 48, the
sensor sensing plate 57 alternately approaches the proximity
sensors 55, 56, whereby the supply of the pressurized air which is
fed from the air compressor or the like, into the internal space of
the cylinder 49, and that into the pump operating chamber 15 are
automatically switched over.
[0038] As shown in FIG. 1, the pulsation damping device 3 further
includes a bellows 60. The bellows 60 is configured so as to be
extendable and contractible in the axial direction (the lateral
direction in FIG. 1) in order to suck a fluid from the intermediate
flow passage 7 which functions as a suction flow passage, and eject
the fluid to the ejection flow passage 8. In the embodiment, a
bottomed cylinder-like casing 61 is attached to a side wall portion
of the partition wall 5 on the other axial end side (the left side
in FIG. 1), and the bellows 60 is placed in the casing 61.
[0039] The bellows 60 has an opening peripheral edge portion 62 on
the one axial end side (the right side in FIG. 1). The opening
peripheral edge portion 62 is fixed in an airtight state to a side
wall portion of the partition wall 5 on the other axial end side by
an annular fixing plate 63. In this way, the internal space of the
casing 61 is hermetically partitioned by using the bellows 60 into
a liquid chamber 64 which is located inside the bellows 60, and an
air chamber 65 which is located outside the bellows 60.
[0040] The bellows 60 further has a closed end portion 71 on the
other axial end side. The bellows 60 has a cylindrical bellows
portion 72 between the closed end portion 71 and the opening
peripheral edge portion 62 so as to be extendable and contractible
in the axial direction. In the bellows portion 72, peak portions
67, valley portions 68, and side surface portions 69 are provided
(see FIG. 2).
[0041] In the pulsation damping device 3, moreover, the
intermediate flow passage 7 and the ejection flow passage 8
communicate with the interior of the liquid chamber 64. A stopper
wall 74 for restricting excessive extension of the bellows 60 which
may be possibly caused by an unexpected situation is disposed at a
position opposed to the closed end portion 71 of the bellows 60,
with forming a predetermined gap with respect to the closed end
portion 71.
[0042] A bottom wall portion 75 is disposed on the other axial end
side with respect to the stopper wall 74 of the casing 61. In the
bottom wall portion 75, an opening 76 is formed, and automatic
ventilation adjusting means 77 for adjusting the filling pressure
of the interior of the air chamber 65 is detachably attached by
bolts or the like to the bottom wall portion in a state where the
means is inserted into the opening 76.
[0043] The automatic ventilation adjusting means 77 is configured
so as to balance the liquid pressure in the liquid chamber 64 with
the air pressure in the air chamber 65 in order to prevent
excessive extending and contracting deformation from occurring in
the bellows 60. Specifically, when the capacity of the liquid
chamber 64 is increased to exceed a predetermined range, the
automatic ventilation adjusting means 77 causes the air to be
sucked into the air chamber 65 to raise the filling pressure, and,
when the capacity of the liquid chamber 64 is decreased to exceed a
predetermined range, the means discharges the air from the air
chamber 65 to lower the filling pressure.
[0044] A valve push rod 78 for opening and closing a suction valve
(not shown) disposed in the automatic ventilation adjusting means
77, and a slider 81 attached to a tip end of a valve pull rod 79
for opening and closing a discharge valve (not shown) are disposed
so as to face the interior of the air chamber 65 through a through
hole 82 which is formed in the stopper wall 74. The slider 81 is
always urged by a spring 83 toward the bellows 60.
[0045] Next, the operation of the pump device 1 (the bellows pump 2
and the pulsation damping device 3) will be described.
[0046] In actuation of the pump device 1, in the bellows pump 2,
when the pressurized air from the air compressor or the like is
supplied through the air hole 52 to the internal space surrounded
by the cylinder 49 and the piston 48, the bellows 10 is extended in
the rightward direction in FIG. 1 to cause the pump working chamber
14 to have a negative pressure. In accordance with the extension of
the bellows 10, the first check valve 43 on the side of the suction
port 41 is opened, and the fluid fed from the suction flow passage
6 is sucked into the pump working chamber 14 through the first
check valve 43.
[0047] By contrast, when the pressurized air which is fed from the
air compressor or the like is supplied through the air hole 51 into
the pump operating chamber 15, the bellows 10 is contracted in the
leftward direction in FIG. 1. In accordance with the contraction of
the bellows 10, the second check valve 44 on the side of the
discharge port 42 is opened, and the fluid which is sucked into the
pump working chamber 14 is ejected toward the intermediate flow
passage 7 from the second check valve 44.
[0048] As described above, when the bellows 10 is extended and
contracted by the operation of the air cylinder 53, the first check
valve 43 and second check valve 44 in the pump working chamber 14
are alternately opened and closed, and the operation of sucking the
fluid from the suction flow passage 6 into the pump working chamber
14, and that of discharging the fluid from the pump working chamber
14 into the intermediate flow passage 7 are repeated. In this way,
the pumping operation of the bellows pump 2 is executed.
[0049] During execution of the pumping operation, the pressurized
air is adequately controlled so that the pressure (external
pressure) of the pressurized air of the pump operating chamber 15
which acts on the bellows portion 22 of the bellows 10 is always
maintained to be higher than the pressure (internal pressure) of
the fluid of the pump working chamber 14 which acts on the bellows
portion 22.
[0050] The fluid ejected from the discharge port 42 of the bellows
pump 2 is formed into a pulsating flow by the extending and
contracting operations of the bellows pump 2, and then fed through
the intermediate flow passage 7 into the liquid chamber 64 which is
formed in the bellows 60 of the pulsation damping device 3. After
the fluid is temporarily stored in the liquid chamber 64, the fluid
is ejected to the outside from the ejection flow passage 8.
[0051] In this case, when the ejection pressure of the fluid has an
increasing tendency, the bellows 60 of the pulsation damping device
3 is extended, and the capacity of the liquid chamber 64 is
increased to absorb the ejection pressure. At this time, the liquid
amount of the fluid which is flown out from the liquid chamber 64
is smaller than that elected from the bellows pump 2.
[0052] When, in this state, the ejection pressure of the fluid is
changed to a decreasing tendency, the pressure of the fluid is
lower than the filling pressure of the interior of the air chamber
65 which is compressed by the extension of the bellows 60, and
therefore the bellows 60 is contracted to decrease the capacity of
the liquid chamber 64. At this time, the liquid amount of the fluid
which is flown out from the liquid chamber 64 is larger than that
elected from the bellows pump 2.
[0053] By the above-described repeated operation of changing the
capacity of the liquid chamber 64 which is caused by the extending
and contracting operations of the bellows 60, the fluid is caused
to be continuously and smoothly flown out from the pulsation
damping device 3 while the pulsation is damped.
[0054] When the capacity of the liquid chamber 64 of the pulsation
damping device 3 is increased to exceed a predetermined range by
the extending and contracting operations of the bellows 60,
specifically, by the variation of the ejection pressure in the
bellows pump 2, the closed end portion 71 of the bellows 60 butts
against the valve push rod 78 of the automatic ventilation
adjusting means 77, and then pushes the valve push rod 78 in the
leftward direction in FIG. 1. Therefore, the suction valve is
opened, the air is sucked into the air chamber 65, the filling
pressure is raised, and excessive extending deformation of the
bellows 60 is suppressed. Consequently, the capacity of the liquid
chamber 64 is prevented from being excessively increased.
[0055] By contrast, when the capacity of the liquid chamber 20a is
decreased to exceed a predetermined range, the slider 81 is engaged
with the tip end of the valve pull rod 79, and the valve pull rod
79 is rightwardly pushed by the spring 83. Therefore, the discharge
valve is opened, the air is discharged from the interior of the air
chamber 65, the filling pressure is lowered, and excessive
contracting deformation of the bellows 60 is suppressed.
Consequently, the capacity of the liquid chamber 64 is prevented
from being excessively decreased.
[0056] In this way, the amounts of extending and contracting
deformations of the bellows 60 can be restricted within a constant
range irrespective of variation of the ejection pressure of the
bellows pump 2, and pulsation can be reduced.
[0057] Next, the bellows 10 of the bellows pump 2 will be described
in more detail. The bellows 60 of the pulsation damping device 3 is
configured in a substantially same manner as the bellows 10, and
hence its description is omitted.
[0058] FIG. 2 is a partial enlarged sectional view of the bellows
10(60) in the pump device 1. FIG. 3(a) is a partial enlarged
sectional view of the bellows portion 22 when the bellows 10 is
contracted. FIG. 3(b) is a partial enlarged sectional view of the
bellows portion 22 when the bellows 10 is maximally extended.
[0059] As shown in FIG. 2, the bellows 10 has the peak portions 17
and valley portions 18 which are alternately formed in the
direction of the axis 16 (the lateral direction in FIG. 1), and the
annular side surface portions 19 which are located between the peak
portions 17 and the valley portions 18, and which connect the both
portions to each other. Each of the peak portions 17 is provided in
an outer circumferential surface portion of the bellows 10 (the
bellows portion 22), and each of the valley portions 18 is placed
at a position which is closer to the axis 16 than the peak portion
17. The side surface portions 19 which are adjacent to each other
in the direction of the axis 16 are placed to be opposed to each
other.
[0060] In the bellows 10, as shown in FIG. 3(a), when the thickness
of the side surface portions 19 in the direction of the axis 16
(the lateral direction in FIG. 1) is indicated by A, and that of
the axial middle parts (an apex portion, the position of a path 0
which will be described later) of the peak portions 17 in a
direction (radial direction) which is perpendicular to the
direction of the axis 16 is indicated by B, a ratio B/A of the
thicknesses is set within a range of 1.3 to 1.8. In the embodiment,
the thickness A of the side surface portions 19 is set to be
uniform in a direction which is perpendicular to the direction of
the axis 16.
[0061] According to the configuration, during extension of the
bellows 10 due to the operation the pump device 1, in the inner
circumferential surface side 17a of the peak portion 17 which is
extended in the direction of the axis 16 as shown in FIG. 3(b),
large stress (maximum value) dispersedly occurs in a range 30 which
extends along the inner circumferential surface across the middle
portion in the direction of the axis 16. Namely, large stress which
is caused in the peak portion 17 is not concentrated in a specific
narrow place. This function effect will be described in Paragraphs
Nos. [0054] to [0059]. In the case where the thickness ratio B/A is
1, stress is concentrated in a focused manner in the inner
circumferential surface side of the axial middle portion of the
peak portion which is extended in the axial direction (see the
reference numeral 160 in FIG. 11).
[0062] Therefore, the middle part in the direction of the axis 16
of the peak portion 17 which is deformable in accordance with
extension and contraction of the bellows 10 can be made not easily
fatigued. Consequently, a crack which is due to extension and
contraction of the bellows 10, and which extends in a direction
perpendicular to the direction of the axis 16 can be suppressed
from occurring in the middle part in the direction of the axis 16
of the peak portion 17. As a result, the bellows 10 is hardly
broken, and a prolonged life period of the bellows can be
realized.
[0063] More preferably, the ratio B/A of the thickness B of the
middle part in the direction of the axis 16 of each of peak
portions 17 in the direction which is perpendicular to the
direction of the axis 16, to the thickness A of each of side
surface portions 19 in the direction of the axis 16 is set within a
range of 1.3 to 1.5, and, further preferably, the ratio is set to
1.5.
[0064] According to the configuration, even in the case of severe
use conditions such as those where the temperature of the fluid is
higher (for example, 70.degree. C.) than the ordinary temperature
(room temperature), when the bellows 10 is extended in the
direction of the axis 16, large stress which is caused in the peak
portion 17 is not concentrated in a specific narrow place. Even in
such a case, therefore, a crack which is due to extension and
contraction of the bellows 10 can be suppressed from occurring in
the middle part in the direction of the axis 16 of the peak portion
17 of the bellows 10.
[0065] Next, the phenomenon in which the embodiment achieves the
function effect that large stress occurring in the peak portion 17
is not concentrated in a specific narrow place will be described.
The stress occurring in the peak portion 17 of the bellows 10 was
analyzed by calculating the Von Mises stress. FIG. 4 is a
comparison view of the maximum value (maximum of Von Mises stress)
of stress which, in the case where the temperature of the fluid is
20.degree. C., occurs in the peak portion 17 when the bellows 10 is
extended. FIG. 5 is a comparison view of the maximum value (maximum
Von Mises stress) of stress which, in the case where the
temperature of the fluid is 70.degree. C., occurs in the peak
portion 17 when the bellows 10 is extended.
[0066] In the case where, among paths which extend from one end in
the direction of the axis 16 of the inner circumferential surface
side 17a of the peak portion 17 to the other end, the middle
portion (apex portion) in the direction of the axis 16 of the peak
portion 17 is indicated by a path 0, the maximum value (maximum Von
Mises stress) of stress occurring in the peak portion 17 which is
stretched in the direction of the axis 16 when the bellows 10 is
extended is distributed in the arcuate range 30 that includes the
position of the path 0 in the inner circumferential surface side of
the peak portion 17.
[0067] From FIG. 4, it can be confirmed that, when the largest
maximum Von Mises stress at the thickness ratio B/A=1 is set to 1,
the maximum Von Mises stress has the largest value (i.e., 1) in a
specific place which is the position of the path 0, while being is
steeply changed, but, in the embodiment, the maximum Von Mises
stress is reduced to about 0.9 in a predetermined range in the
direction of the axis 16 and across the position of the path 0, and
the value of about 0.9 is substantially maintained.
[0068] From this, it is seen that, in the embodiment, the maximum
Von Mises stress has an approximately same value in a relatively
wide predetermined range (the flat-like portions in FIG. 4) across
the position of the path 0 with respect to the path, at each of
thickness ratios B/A=1.3, 1.5, and 1.8. Namely, it is seen that
large stress (maximum value) occurring in the peak portion 17 when
the bellows 10 is extended has a relatively small value, and is
distributed in the periphery of the position of the path 0 without
being concentrated to the position thereof.
[0069] From FIG. 5, moreover, it can be confirmed that, when the
largest maximum Von Mises stress at the thickness ratio B/A=1 is
set to 1, in the embodiment, the maximum Von Mises stress is
reduced to about 0.85 in a predetermined range in the direction of
the axis 16 and across the position of the path 0, and the value of
about 0.85 is substantially maintained.
[0070] From this, it is seen that, even in the case where the
temperature of the fluid is high (specifically, 70.degree. C.), the
maximum Von Mises stress has an approximately same value in a
relatively wide predetermined range (the flat-like portions in FIG.
5) across the position of the path 0 with respect to the path, at
each of thickness ratios B/A=1.3 and 1.5. Namely, it is seen that
large stress (maximum value) occurring in the peak portion 17 when
the bellows 10 is extended has a relatively small value, and is
distributed in the periphery of the position of the path 0 without
being concentrated to the position thereof.
[0071] In the embodiment, as shown in FIG. 3(a), the sectional
shape of the inner circumferential surface side 17a of the peak
portion 17 in the direction of the axis 16 is formed into an
arcuate shape having a first radius of curvature. The sectional
shape of the outer circumferential surface side 17b of the peak
portion 17 in the direction of the axis 16 is formed into an
arcuate shape having a second radius of curvature which is larger
than the first radius of curvature. Here, the center 24 of the arc
having the second radius of curvature which is placed on the same
axis as the center 23 of the arc having the first radius of
curvature is deviated toward the radially outer side with respect
to the center 23.
[0072] In the embodiment, as shown in FIGS. 2 and 3, the sectional
shape of an outer circumferential surface side 18b of the valley
portion 18 in the direction of the axis 16 is formed into a shape
(arcuate shape) corresponding to the sectional shape of the inner
circumferential surface side 17a of the peak portion 17 in the
direction of the axis 16. The sectional shape of an inner
circumferential surface side 18a of the valley portion 18 in the
direction of the axis 16 is formed into a shape (arcuate shape)
corresponding to the sectional shape of the outer circumferential
surface side 17b of the peak portion 17 in the direction of the
axis 16.
[0073] Although, in the embodiment, the peak portion of the bellows
in the invention is the peak portion 17 in which a ridge portion of
the outer circumferential surface side 17b is formed into an
arcuate shape in sectional, the peak portion is not limited to
this. As shown in FIG. 6(a), the peak portion may be formed as a
peak portion 33 having, in a sectional view, an angular shape in
which ridge portions of an outer circumferential surface side 33b
are formed into edge portions 33c in the both end sides in the
direction of the axis 16, or, as shown in FIG. 6(b), a peak portion
35 in which the edge portions 33c of the peak portion 33 are
chamfered. From the viewpoint of relaxation of stress
concentration, however, the peak portion of the bellows in the
invention is preferably the peak portion 17 shown in FIG. 3 as
compared with the peak portions 33, 35 shown in FIGS. 6(a) and
(b).
[0074] In the embodiment, as shown in FIG. 3, a space portion 201
is formed between the side surface portions 19 which are adjacent
to each other in the direction of the axis 16. Also when the
bellows 10 is contracted, the space portion 201 is held. The width
(the width of the space portion in the direction of the axis 16) C
between the side surface portions 19 which are adjacent to each
other in the direction of the axis 16 is set to be substantially
equal to the thickness A of the side surface portions 19 when the
bellows 10 is contracted (maximally contracted).
[0075] In the embodiment, the side surface portions 19 are
configured so as to, when the bellows 10 is maximally contracted in
the axial direction, be located on a plane which is substantially
perpendicular to the axial direction of the bellows 10 as shown in
FIG. 3(a). The state of the bellows 10 is adequately controlled by
the air cylinder 53 so that the space portion 201 having the width
C of a predetermined dimension is formed between the side surface
portions 19 which are opposed to each other on the side of the pump
working chamber 14.
[0076] Specifically, the side surface portions 19 of the bellows 10
has an inner circumferential surface 202 which faces toward the
pump working chamber 14, and an outer circumferential surface 203
which faces toward the pump operating chamber 15. Each of the inner
circumferential surface 202 and the outer circumferential surface
203 is formed into a planar shape. The inner circumferential
surface 202 and the outer circumferential surface 203 are placed in
parallel to each other so that the thickness A of the side surface
portions 19 is substantially constant in a radial direction of the
bellows 10.
[0077] When the bellows 10 is maximally contracted in the axial
direction, then, the inner circumferential surface 202 and the
outer circumferential surface 203 are configured to constitute
planes which are substantially perpendicular to the axial direction
of the bellows 10. When the bellows 10 is maximally contracted,
therefore, the space portion 201 has the width C which is
approximately equal to the peak portion 17 on the side of the
valley portion 18, and namely has the width C which is
substantially constant in a radial direction of the bellows 10.
[0078] The maximally contracted state of the bellows 10 can be
realized by, in the air cylinder 53, contacting the piston 48 which
is moved for contracting the bellows 10, to the cylinder 49 (the
bottom wall portion of the pump casing 11), thereby restricting the
position of the piston 48, or controlling the pressurized air by
using the proximity sensors 55, 56 and the sensor sensing plate
57.
[0079] In the bellows 10 in the maximally contracted state,
therefore, it is possible to, in the pump working chamber 14,
ensure the width C which does not impede ingress of the fluid into
the space portion 201, and the pump working chamber 14 is easily
filled with the fluid. Consequently, the operation of switching the
contracted state of the bellows 10 to the extended state in
accordance with the inflow of the fluid into the pump working
chamber 14 can be smoothly performed.
[0080] FIG. 7(a) is an enlarged sectional view of a vicinity of the
opening peripheral edge portion 12 when the bellows 10 is maximally
contracted. FIG. 7(b) is an enlarged sectional view of a vicinity
of the closed end portion 21 when the bellows 10 is maximally
contracted.
[0081] In the embodiment, as shown in FIG. 7(a), the bellows 10 is
disposed so that, when the bellows 10 is maximally contracted, the
side surface portion 19(19A) which is closest to the opening
peripheral edge portion 12 is not contacted with the first annular
fixing plate 13. The side surface portion 19(19A) is placed so
that, when the bellows 10 is maximally contracted, a first gap 205
is formed between the side surface portion and the first annular
fixing plate 13.
[0082] In the embodiment, as shown in FIG. 7(b), the bellows 10 is
disposed so that, when the bellows 10 is maximally contracted, the
side surface portion 19(19B) which is closest to the closed end
portion 21 is not contacted with the second annular fixing plate
206. The side surface portion 19(19B) is placed so that, when the
bellows 10 is maximally contracted, a second gap 208 is formed
between the side surface portion and the second annular fixing
plate 206.
[0083] According to the configuration, when the bellows 10 is
extension-driven, it is possible to block the side surface portion
19(19A) from repeatedly contacting with the first annular fixing
plate 13. In this case, furthermore, it is possible to block the
side surface portion 19(19B) from repeatedly contacting with the
second annular fixing plate 206. Therefore, deterioration of the
bellows 10 (the side surface portions 19(19A), (19B)) caused by
contact with the first annular fixing plate 13 and the second
annular fixing plate 206 can be prevented from occurring.
[0084] In the fluid apparatus of the invention, a bellows 210
which, as shown in FIG. 8, is directly fixed in an opening
peripheral edge portion 213 to a partition wall 211 and a pump
casing 12 may be used in place of the bellows 10. In this case, it
is preferable that, when the bellows 210 is maximally contracted, a
gap 217 is formed between a side surface portion 215(215A) which is
included in the bellows 210, and which is closest to the opening
peripheral edge portion 213, and the opening peripheral edge
portion 213, thereby preventing the both portions from contacting
with each other.
[0085] FIG. 9 is a side sectional view showing the whole of a
pulsation damping device 93 which is a fluid apparatus of another
embodiment of the invention. The portions corresponding to the
places shown in FIG. 1 are denoted by the same reference
numerals.
[0086] As shown in FIG. 9, the pulsation damping device 93 is
substantially identical with the pulsation damping device 3 of the
above-described embodiment. The pulsation damping device 93
includes a cylindrical peripheral wall member 102, and a casing 101
having an upper wall member 103 and lower wall member 104 which are
fixed to the upper and lower ends of the peripheral wall member,
respectively. The bellows 60 which is configured so as to be
extendable and contractible in the axial direction (the vertical
direction) is placed in the casing 101.
[0087] Then, the opening peripheral edge portion 62 of the bellows
60 is fixed in an airtight state to a side wall portion of the
lower wall member 104 by the annular fixing plate 63. Therefore,
the internal space of the casing 101 is hermetically partitioned
into the liquid chamber 64 which is located inside the bellows 60,
and the air chamber 65 which is located outside the bellows 60. In
the lower wall member 104, the suction flow passage 6 and ejection
flow passage 8 for a fluid are formed, and the both passages 7, 8
communicate with the liquid chamber 64. The automatic ventilation
adjusting means 77 is disposed in the upper wall member 103.
[0088] The bellows 60 has a configuration which is substantially
identical with that used in the pulsation damping device 3 shown in
FIG. 1, and the configuration of the automatic ventilation
adjusting means 77 is identical with that used in the pulsation
damping device 3. Therefore, detailed description of their function
operations is omitted.
[0089] FIG. 10 is a longitudinal sectional view showing the whole
of a bellows pump 112 which is a fluid apparatus of a further
embodiment of the invention.
[0090] In the bellows pump 112, as shown in FIG. 10, a pair of
right and left pump portions are symmetrically placed. The pump
portions complementarily operate, and therefore a large
transportation amount can be obtained.
[0091] Namely, the bellows pump 112 includes a cylindrical
peripheral wall member 121, and a pump casing 120 having sidewall
members 122, 123 which are fixed to the left and right ends of the
peripheral wall member 121, respectively. In the pump casing 120, a
pair of bellows 125, 126 are placed in a bilaterally symmetrical
manner across a partition wall 124.
[0092] The bellows 125, 126 have a configuration which is
substantially identical with the bellows 10 used in the bellows
pump 2 shown in FIG. 1. In the bellows 125, 126, their opening
peripheral edge portions are fixed in an airtight state to side
wall portions of the partition wall 124 by annular fixing plates
128, 129, and their closed end portions are coupled to pressure
receiving plates 131, 132. The pressure receiving plates 131, 132
are coupled to each other by a plurality of coupling rods 133 which
are passed through the partition wall 124.
[0093] In the partition wall 124, a suction flow passage 134 and
ejection flow passage 135 for a fluid are formed. Between the
suction flow passage 134 and the ejection flow passage 135, check
valves 136, 137 which can be alternately opened and closed in
accordance with extending and contracting operations of the bellows
125 are disposed, and check valves 138, 139 which can be
alternately opened and closed in accordance with extending and
contracting operations of the bellows 126 are disposed.
[0094] Furthermore, air holes 141, 142 for supplying pressurized
air from a compressor or the like which is not shown, to the pump
casing 120, and air holes 143, 144 for discharging the air in the
pump casing 120 are formed in the sidewall members 122, 123 of the
pump casing 120, respectively.
[0095] In the bellows pump 112, therefore, the pressurized air from
the compressor or the like is alternately supplied from the air
holes 141, 142 to cause the left and right bellows 125, 126 to
alternately perform extending and contracting operations. When the
fluid is sucked from the suction flow passage 134 through the check
valve 139 by the right bellows 126, for example, the fluid stored
in the left bellows 125 is ejected from the ejection flow passage
135 through the check valve 136 by the left bellows 125. When the
fluid is sucked from the suction flow passage 134 through the check
valve 137 by the left bellows 125, the fluid stored in the right
bellows 126 is ejected from the ejection flow passage 135 through
the check valve 138 by the right bellows 126.
[0096] When the left and right bellows 125, 126 are caused to
alternately perform extending and contracting operations in this
way, the suction of the fluid from the suction flow passage 134,
and the ejection to the ejection flow passage 135 are repeated,
whereby the predetermined pumping operation is executed.
DESCRIPTION OF REFERENCE NUMERALS
[0097] 1 pump device (fluid apparatus) [0098] 6 suction flow
passage [0099] 7 intermediate flow passage (ejection flow passage
or suction flow passage) [0100] 8 ejection flow passage [0101] 10
bellows [0102] 16 axis [0103] 17 peak portion [0104] 18 valley
portion [0105] 19 side surface portion [0106] 33 peak portion
[0107] 35 peak portion [0108] 60 bellows [0109] 67 peak portion
[0110] 68 valley portion [0111] 69 side surface portion [0112] 93
pulsation damping device (fluid apparatus) [0113] 112 bellows pump
(fluid apparatus) [0114] 125 bellows [0115] 126 bellows
* * * * *