U.S. patent application number 09/897508 was filed with the patent office on 2002-01-03 for tube pump.
Invention is credited to Doi, Yutaka, Morita, Katsuhiko, Nakamura, Fumio, Tamagawa, Nagao.
Application Number | 20020001530 09/897508 |
Document ID | / |
Family ID | 18698303 |
Filed Date | 2002-01-03 |
United States Patent
Application |
20020001530 |
Kind Code |
A1 |
Doi, Yutaka ; et
al. |
January 3, 2002 |
Tube pump
Abstract
A tube pump comprising a tube formed beforehand into a shape
adapted for the inner circumferential face of the housing. With
this configuration, the tube can be used without problems even when
the inner circumferential face of the housing is small and when the
curvature of the inner circumferential face is large, and squeezing
can be carried out by applying a small pressure force to the tube.
Hence, the size of the pump is prevented from being made larger,
and breakage of the tube owing to repeated deformations does not
occur because the amount of deformation of the tube is reduced.
Furthermore, synthetic resins having high chemical resistance can
be used as materials of the tube. Hence, unlike a rubber tube, the
tube of the present invention is suited for a wide range of
applications.
Inventors: |
Doi, Yutaka; (Neyagawa,
JP) ; Nakamura, Fumio; (Higashi-Osaka, JP) ;
Morita, Katsuhiko; (Yawata, JP) ; Tamagawa,
Nagao; (Minoo, JP) |
Correspondence
Address: |
KODA & ANDROLIA
SUITE 3850
2029 CENTURY PARK EAST
LOS ANGELES
CA
90067-3024
US
|
Family ID: |
18698303 |
Appl. No.: |
09/897508 |
Filed: |
June 29, 2001 |
Current U.S.
Class: |
417/477.12 |
Current CPC
Class: |
F04B 43/123 20130101;
F04B 43/0072 20130101 |
Class at
Publication: |
417/477.12 |
International
Class: |
F04B 043/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 3, 2000 |
JP |
2000-200424 |
Claims
What is claimed is:
1. A tube pump comprising a tube disposed in a ring shape along a
circular inner circumferential face formed in a housing, said tube
being squeezed sequentially in the longitudinal direction thereof
by a pressure application member disposed inward so as to feed
fluid from the inside of said tube, wherein said tube is formed
beforehand into a shape adapted for said inner circumferential face
of said housing.
2. A tube pump in accordance with claim 1, wherein said tube is
made of a synthetic resin, and the squeezed portion thereof is flat
in cross section such that the outer side of said tube on the side
of said housing and the inner side of said tube on the side of said
pressure application member are joined to each other at acute
angles.
3. A tube pump in accordance with claim 2, wherein the outer side
and the inner side of said tube have circular arc shapes in cross
section.
4. A tube pump in accordance with claim 2, wherein the outer side
and the inner side of said tube have broken line shapes in cross
section.
5. A tube pump in accordance with claim 3, wherein one of the
pressure application face of said inner circumferential face of
said housing and the pressure application face of said pressure
application member has a convex circular arc shape and the other
has a concave circular arc shape in cross section.
6. A tube pump in accordance with claim 5, wherein the wall
thickness of one of the outer side and the inner side of said tube,
making contact with said concave pressure application face, is made
larger, and the wall thickness of the other, making contact with
said convex pressure application face, is made smaller.
7. A tube pump in accordance with any one of claims 1 to 6, wherein
the outside of said tube is covered with a rubber tube.
8. A tube pump in accordance with any one of claims 1 to 7, wherein
a connection portion is formed at each end of said tube so as to be
integrated therewith.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a tube pump, more
particularly to an improvement of a tube for use in the tube
pump.
[0003] 2. Description of the Prior Art
[0004] A tube pump is configured such that a tube is disposed in a
ring shape along a circular inner circumferential face formed in a
housing and such that the tube is squeezed sequentially in the
longitudinal direction thereof by a pressure application member
disposed inward, such as a roller or a ring, so as to feed fluid
from the inside of the tube. A straight tube, which is made of a
rubber elastic material, circular or nearly circular in cross
section and stretchable and compressible in both the radial and
longitudinal directions, is generally used as a tube for this pump.
This tube is bent in a ring shape and disposed along the inner
circumferential face of the housing.
[0005] When the straight tube is bent during use as described
above, the outer side of the bent tube is stretched, and the inner
side thereof is compressed. Hence, if the curvature of the bent
tube exceeds a certain limit, the tube results in buckling, and the
buckling portion becomes flat, whereby the effective
cross-sectional area of the tube becomes small and the pump cannot
deliver its intended capacity. To prevent this problem, it is
necessary to take countermeasures. For example, the diameter of the
inner circumferential face of the housing is made larger to
decrease the curvature thereof, or the wall thickness of the tube
is made larger to make the tube resistant to flattening. However,
these countermeasures become great factors making the size of the
pump larger.
[0006] In addition, in order to operate the pump efficiently, the
tube is required to be flattened completely so as not to cause any
clearance inside when the tube is squeezed, and also required to
return to its original shape promptly after squeezing. However, in
the case of a tube being circular in cross section, in order to
completely flatten this tube, it is necessary to apply a pressure
force that is large enough to fold back the wall of the tube 180
degrees at both ends thereof in cross section. Furthermore, in
order to allow the tube to return to its original shape promptly
after squeezing, it is preferable that the elastic force of the
tube is larger. Hence, it is necessary that the pressure force is
large enough to cope with this large elastic force. Therefore,
these also become great factors making the size of the pump larger.
Moreover, these require extra energy significantly exceeding energy
required for fluid transfer. As a result, the efficiency of the
pump is lowered, and the tube is apt to break at portions wherein
folding back is repeated, thereby increasing maintenance cost.
[0007] Still further, since a freely stretchable and compressible
tube having rubber-like elasticity is required, the material of the
tube that can be used for the pump is limited. Hence, it is
impossible to use tubes made of synthetic resins having high
chemical resistance, such as polypropylene, polyethylene and
fluorocarbon resin, thereby causing a problem of limiting the
application range of the pump.
SUMMARY OF THE INVENTION
[0008] In view of these problems, a first object of the present
invention is to provide a compact tube pump. A second object of the
present invention is to reduce energy required for pump operation.
A third object of the present invention is to provide a tube pump
comprising a tube being resistant to breakage. Furthermore, a
fourth object of the present invention is to provide a tube pump
having very few limitations on the material of the tube so as to be
usable for wide applications.
[0009] In order to attain the above-mentioned objects, the tube
pump of the present invention uses a tube formed beforehand into a
shape adapted for the inner circumferential face of the
housing.
[0010] The specific configuration of the tube pump of the present
invention, more particularly the specific configuration of its
tube, will become apparent from the following descriptions of
embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic front view showing an embodiment of a
tube pump in accordance of the present invention;
[0012] FIG. 2A is a perspective view showing a tube for use in the
pump;
[0013] FIG. 2B is a sectional view showing a shape of the squeezed
portion of the tube;
[0014] FIG. 3A is a sectional view showing another shape of the
squeezed portion of the tube;
[0015] FIG. 3B is a sectional view showing still another shape of
the squeezed portion of the tube;
[0016] FIG. 4 is a sectional view showing shapes of the pressure
application faces of the pump and a further shape of the squeezed
portion of the tube;
[0017] FIG. 5A is a sectional view showing a still further shape of
the squeezed portion of the tube for use in the pump; and
[0018] FIG. 5B is a sectional view showing a squeezed condition of
the still further shape of the squeezed portion of the tube.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] Referring to FIG. 1, numeral 1 designates a housing having
an inner circumferential face 2. On the inner circumferential face
2, a circular pressure application face 2a is formed in a range
larger than the half and smaller than the whole of the
circumference of the inner circumferential face 2. An opening
portion 2b is provided at a portion wherein the pressure
application face 2a is not formed. Numeral 3 designates a tube. The
tube 3 is disposed along the inner circumferential face 2. The
straight extension portions 3a at both ends of the tube 3 are
extended outside the housing 1 from the opening portion 2b.
[0020] Numeral 4 designates a ring-shaped pressure application
member disposed on the inner side of the tube 3. The pressure
application member 4 has a double structure comprising an inner
ring 41 and an outer ring 42. The inner ring 41 is made of a rigid
material having a low friction coefficient, such as a
fluorocarbon-resin-based synthetic resin mold. The outer ring 42 is
formed of a mold made of an elastic material having a high friction
coefficient, such as rubber. The outer circumference of the outer
ring 42 is used as a pressure application face 4b.
[0021] Numeral 5 designates an eccentric driving member disposed on
the inner side of the pressure application member 4. Numeral 6
designates a rotation shaft on which the eccentric driving member 5
is installed. The eccentric driving member 5 rotates for example
clockwise as seen in FIG. 1 while its circular outer
circumferential face 5a makes sliding contact with the inner
circumferential face 4a of the pressure application member 4.
Hence, the pressure application member 4 carries out circular
motion along the inner circumferential face 2 of the housing 1,
whereby the pressure application faces 2a and 4b hold the tube 3
therebetween and squeeze the tube 3 sequentially toward the left
extension portion 3a as seen in FIG. 1. A drive motor (not shown)
is disposed on the rear face of the housing 1, and the output shaft
of the motor is directly used as the rotation shaft 6 or connected
to the rotation shaft 6 via an appropriate reduction gear.
[0022] The tube 3 is formed of a synthetic resin mold having a high
chemical resistance, such as polypropylene, polyethylene and
fluorocarbon resin. As a whole, the tube 3 has a shape shown in
FIG. 2A. The straight extension portion 3a adapted for the opening
2b is formed at each end of the ring-shaped squeezed portion 3c
adapted for the pressure application face 2a of the housing 1 so as
to be integrated with the squeezed portion 3c. In addition, a
connection portion 3b for connection to another apparatus via a
tube is formed at the end of the extension portions 3a. The
connection portion 3b is provided with appropriate annular
projections to prevent disconnection. This tube 3 is not so
flexible as rubber because it is a mold made of the above-mentioned
material. Furthermore, the tube 3 has some hardness and rigidity,
and also has elasticity so as to be deformable and so as to return
to its original shape after deformation. The shape of the tube 3
shown in FIG. 2A is just an example, and it is needless to say that
the tube 3 can be formed into a shape adapted for the inner
circumferential face 2 of the housing 1 in which the tube 3 is
used.
[0023] FIG. 2B is a sectional view taken along a plane in a
direction perpendicular to the length of the squeezed portion 3c.
In other words, its cross section has a flat shape wherein an outer
side 3d making contact with the housing 1 is joined to an inner
side 3e making contact with the pressure application member 4 at
joint portions 3f. An angle A at which the outer side 3d intersects
the inner side 3e is an acute angle. Both the outer side 3d and the
inner side 3e have circular arc shapes slightly inflated outward.
Since the squeezed portion 3c is extended in the direction of
flatness of the tube 3, the thickness of the outer side 3d and the
thickness of the inner side 3e are far smaller than that of the
extension portion 3a. In FIG. 2B, it is assumed that the cross
sections of the outer side 3d and the inner side 3e have ordinary
circular arc shapes. However, the cross sections may have circular
arc shapes partially taken from ellipses.
[0024] Since the tube pump 11 of this embodiment comprises the tube
3 having the above-mentioned shape, the outer side 3d and the inner
side 3e having small wall thicknesses and slightly inflated shapes
should only be flattened at the time of squeezing. Since the angle
at the joint portion 3f is an acute angle, the amount of its
deformation is small at the time of squeezing. Furthermore, in the
case of this deformation, both the ends are not folded back 180
degrees when flattened. Hence, the outer side 3d and the inner side
3e should only have elasticity to the extent that they can return
to their inflated shapes. For this reason, the wall thicknesses of
the outer side 3d and the inner side 3e can be made smaller.
Therefore, the tube can be squeezed completely by applying a
smaller pressure force in comparison with a case wherein a circular
rubber tube is squeezed, and breakage at the joint portions 3f
owing to repeated deformations is less likely to occur. Still
further, since the deformations at the outer side 3d and the inner
side 3e are small, they can return promptly to their original
shapes after squeezing by virtue of the recovery forces of the
outer side 3d, the inner side 3e and the joint portions 3f.
[0025] FIGS. 3A and 3B show examples of other sectional shapes of
the squeezed portion 3c. The shapes of the outer side 3d and the
inner side 3e shown in FIG. 3A are formed of broken lines wherein
the outer side 3d and the inner side 3e are inflated and bent
outward thereby forming a rhombus. In addition to this rhombus, it
is possible to have a flat hexagon or the like. Furthermore, the
shape shown in FIG. 3B is similar to that shown in FIG. 2B, but the
joint portions 3f have fin shapes extending in the direction of
flatness of the tube 3. The outer side 3d and the inner side 3e
have shapes smoothly inflated in parallel with the fin-shaped joint
portions 3f. Hence, deformations at the joint portions 3f are
almost negligible, whereby the tube 3 can be squeezed easily to a
flat shape. In this case, when the sum of the wall thickness of the
outer side 3d and the wall thickness of the inner side 3e is made
equal to the wall thickness of the joint portion 3f, and when the
tube 3 is squeezed and flattened, the thickness of the tube 3
becomes constant on the whole.
[0026] Since the tube 3 is formed into the shape adapted for the
inner circumferential face 2 of the housing 1 beforehand as
described above, even when the housing 1 is small and when the
curvature of the inner circumferential face 2 is large, no
extension force applies to the outer side of the curved shape of
the tube 3, and no compression force applies to the inner side of
the curved shape of the tube 3 during pump operation. Furthermore,
the sectional shape of the squeezed portion 3c of the tube 3 that
is squeezed during pump operation is a flat shape wherein the outer
side 3d on the side of the housing 1 and the inner side 3e on the
side of the pressure application member 4 are joined to each other
at acute angles. Hence, the wall thickness of the squeezed portion
3c can be decreased, and the amount of its deformation at the time
of squeezing can be reduced, whereby squeezing can be carried out
securely by applying a relatively small pressure force.
[0027] With these overall effects, the size of the pump is
prevented from being made larger, and breakage of the tube owing to
repeated deformations does not occur because the amount of
deformation of the tube is reduced. Furthermore, a variety of
synthetic resins can be used as materials of the tube, whereby it
is possible to obtain a tube pump applicable to a variety of
medicines and chemical products.
[0028] Still further, this kind of pump is not used independently,
but is required to be connected between external apparatuses via
connection tubes in order to receive and deliver fluid to be
transferred. In this embodiment, the connection to the external
apparatuses is easy, since the connection portion 3b is formed at
each end of the tube 3 so as to be integrated therewith as
described above.
[0029] In the embodiment, it is assumed that the pressure
application face 2a of the housing 1 and the pressure application
face 4b of the pressure application member 4 are cylindrical and
that their sectional shapes are straight in the axial direction.
The squeezed portion 3c of the tube 3 is symmetrical with respect
to its centerline in the direction of flatness of the tube 3.
[0030] On the other hand, as shown in FIG. 4, one of the pressure
application face 2a of the housing 1 and the pressure application
face 4b of the pressure application member 4 can have a convex
circular arc shape in cross section, and the other can have a
concave circular arc shape in cross section adapted for the convex
circular shape. In this case, it is preferable that the wall
thickness of one of the outer side 3d and the inner side 3e of the
tube 3, making contact with the concave pressure application face,
is made larger, and that the wall thickness of the other, making
contact with the convex pressure application face, is made smaller.
In FIG. 4, the pressure application face 4b is made convex, the
pressure application face 2a is made concave, the wall thickness of
the outer side 3d of the tube 3 is made larger, and the wall
thickness of the inner side 3e is made smaller. In the case of this
shape, the side that is thin and deformable easily at the time of
squeezing, that is, the inner side 3e in the example shown in FIG.
4, can be deformed and pressed easily against the outer side 3d
with no clearance therebetween as indicated in a chain line. Hence,
no large pressure force is required for squeezing. Furthermore,
after squeezing, the inner side 3e returns to its original shape by
virtue of its elasticity.
[0031] Generally speaking, a thin object having a slightly inflated
shape has the property of being deflated abruptly because of a kind
of buckling phenomenon when an external pressure larger than the
deflation pressure of the object is applied to the object and
returning to its original shape abruptly when the external pressure
becomes extinct. In the case of this tube 3, by properly selecting
the wall thickness and the inflated shape of the inner side 3e, the
inner side 3e can be deflated easily by slight pressure application
and can immediately return to its original shape when the pressure
application ceases. By using this property, it is possible to
obtain a tube wherein the inner side 3e can make completely close
contact with the outer side 3d by applying a small pressure force
and the inner side 3e returns promptly to its original shape after
squeezing. This so-called can-deflating effect can be obtained by
properly selecting the wall thickness and inflated shape. Hence, an
effect similar to this effect can also be obtained even when the
wall thickness of the outer side 3d is equal to that of the inner
side 3e.
[0032] FIGS. 5A and 5B show an example wherein the shape returning
force of the tube 3 is improved by using a structure different from
the above-mentioned structures. In this example, at least the
squeezed portion 3c of the tube 3, a synthetic resin mold, is
covered with a rubber tube 8. It is preferable that this rubber
tube 8 has a size that achieves a slightly stretched condition when
the tube 3 is covered with the rubber tube 8. In this
configuration, in a condition wherein the tube 3 is squeezed and
flattened as shown in FIG. 5B, an inward contracting stress is
produced in the stretched rubber tube 8 as indicated by the arrows.
Hence, the returning force of the rubber tube 8 is superimposed on
the returning force of the tube 3 itself, whereby the tube 3 can
promptly return to its original shape after squeezing.
[0033] Unlike the structure wherein the tube 3 is covered with the
rubber tube 8 shown in FIGS. 5A and 5B, for example, a structure,
in which cushion members made of sponge or the like are disposed at
positions making contact with the connection portions 3f at both
ends of the tube 3 when squeezed and flattened, may be used. In
other words, the forces for returning the connection portions 3f
are generated by the cushion members. Even when this configuration
is used, the tube 3 can return promptly to its original shape after
squeezing.
[0034] As a result, with the above-mentioned configurations, the
tube can return promptly to its original shape after the squeezing
of the tube is completed, whereby it is possible to obtain an
efficient tube pump.
* * * * *