U.S. patent application number 11/192024 was filed with the patent office on 2006-07-20 for hand-held vacuum pump and automated urinary drainage system using pump thereof.
Invention is credited to Kiyoshi Azuhata, Yoshikazu Ishitsuka, Isao Koromegawa, Ryosuke Miyagawa, Tetsuya Tanaka, Wataru Tazoe.
Application Number | 20060159567 11/192024 |
Document ID | / |
Family ID | 36202541 |
Filed Date | 2006-07-20 |
United States Patent
Application |
20060159567 |
Kind Code |
A1 |
Tazoe; Wataru ; et
al. |
July 20, 2006 |
Hand-held vacuum pump and automated urinary drainage system using
pump thereof
Abstract
In the hand-held vacuum pump 1, the main body 1a of the vacuum
pump in which the pump room 4a is formed and the electric motor 2
are connected via the shaft coupling 21. The main body of the
vacuum pump has the driving shaft 10. One ball bearing 15b
supporting the driving shaft is supported by the cylinder. The
other ball bearing 15a is sup ported by the flange 5 mounted
hermetically at the cylinder. The end part of the cylinder at the
side of the electric motor accommodates the shaft coupling, and is
engaged with the end part of the electric motor so that the
electric motor may support the cylinder.
Inventors: |
Tazoe; Wataru; (Tsuchiura,
JP) ; Miyagawa; Ryosuke; (Kasukabe, JP) ;
Ishitsuka; Yoshikazu; (Minori, JP) ; Tanaka;
Tetsuya; (Tokyo, JP) ; Azuhata; Kiyoshi;
(Ishioka, JP) ; Koromegawa; Isao; (Tsuchiura,
JP) |
Correspondence
Address: |
ANTONELLI, TERRY, STOUT & KRAUS, LLP
1300 NORTH SEVENTEENTH STREET
SUITE 1800
ARLINGTON
VA
22209-3873
US
|
Family ID: |
36202541 |
Appl. No.: |
11/192024 |
Filed: |
July 29, 2005 |
Current U.S.
Class: |
417/410.3 |
Current CPC
Class: |
F04C 2240/60 20130101;
F04C 23/02 20130101; F04C 29/0057 20130101; F04C 18/356 20130101;
F04C 29/0071 20130101; F04C 2240/52 20130101; F04B 35/04 20130101;
A61F 5/44 20130101; F04C 25/02 20130101; F04C 29/0078 20130101;
F04C 2240/30 20130101 |
Class at
Publication: |
417/410.3 |
International
Class: |
F04B 35/04 20060101
F04B035/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 20, 2005 |
JP |
2005-012223 |
Feb 14, 2005 |
JP |
2005-035371 |
Claims
1. A hand-held vacuum pump formed by connecting an electric motor
and a main body of vacuum pump formed with a pump room via a shaft
coupling, wherein one bearing supporting a driving shaft of said
main body of vacuum pump is supported by a cylinder, and the other
bearing is supported by a flange mounted hermetically at said
cylinder; an end part of said cylinder at a side of an electric
motor accommodates said shaft coupling and is engaged with an end
part of said electric motor; and said electric motor supports said
cylinder.
2. A hand-held vacuum pump of claim 1, wherein a round hole engaged
with a rotating shaft of said electric motor is formed at one side
of said shaft coupling; a quasi-square hole engaged with a drive
shaft penetrating inside said cylinder is formed at the other side
of said shaft coupling; and a hole engaged with a rotating shaft of
said electric motor is formed at said driving shaft so that a
locking screw for said shaft coupling and said rotating shaft of
said electric motor may not required.
3. A hand-held vacuum pump of claim 2, wherein an eccentric shaft
made of resin material aligned with an eccentric axis to said
driving shaft and having an outline cylindrical part is provided; a
piston having an extension part configured as a plate structure at
a part of periphery is mounted at an outer side of said eccentric
shaft; and plural protruding parts extending in an axial direction
of an inner face of said eccentric shaft are formed at an engaged
part between said driving shaft and said eccentric shaft.
4. A hand-held vacuum pump of claim 2, wherein a material to be
used for said shaft coupling is selected to be a resin material;
and plural protruding parts extending in an axial direction at an
inner face of a round hole formed said shaft coupling, or plural
protruding parts extending in a radial direction and connecting to
said round hole.
5. A hand-held vacuum pump wherein a couple of sliding cylinders
clamping both sides of an intermediate part of an extension part of
said plate structure and having a circular arc part is provided;
said sliding cylinder is supported by a cylinder and said siding
cylinder is made oscillating inside said cylinder; said cylinder
and said piston are formed as double cylinders; and a pump room is
formed so that a shape of said pump room may change between said
double cylinders.
6. An automated urinary drainage system having a hand-held vacuum
pump of one of claims 1 to 5, wherein an exhaust speed of said
vacuum pump is 70 mL/sec or larger, and a weight of said vacuum
pump is 250 g or lighter.
7. A hand-held vacuum pump of claim 1, wherein a piston is mounted
at said driving shaft through an eccentric shaft; said piston has a
blade part configured as a plate structure extending towards an
outer side at a part of periphery; said sliding cylinder having a
circular arc part supports said blade part so as to freely
oscillate; a material of said driving shaft is made to be stainless
steel, a material of said shaft coupling is made to be PC resin or
POM resin, a material of said piston is made to be PS resin or PC
resin, a material of the cylinder is made to be PBT resin, and a
material of said sliding cylinder is made to be PPS resin or PBT
resin, in which PC stands for Polycarbonade, POM stands for
Polyacetal, PS stands for Polystyrene, PPS stands for Polyphenylene
Sulfide, and PBT stands for Polybutylene Terphthalate.
8. A hand-held vacuum pump of claim 7, wherein a balance weight is
mounted at an end part of said driving shaft for compensating an
eccentricity between said piston and said eccentric shaft; a cover
for covering said balance weight is mounted at said flange; and a
material of said flange is selected to be POM resin.
9. A hand-held vacuum pump of claim 7, wherein said cylinder and
said piston are formed as double cylinders; and a gas inside a pump
room is compressed by changing a volume of said pump room formed
between double cylinders by oscillating said blade part.
10. A hand-held vacuum pump of claim 7, wherein a beveled cut part
having a cross-sectional shape of shaft shaped in D-sigmoid is
formed at said driving shaft; a hole corresponding to said
D-sigmoid shape is formed at said eccentric shaft; and plural
protruding parts extending in an axial direction inside said hole
shaped in D-sigmoid formed at an eccentric shaft.
11. A hand-held vacuum pump of claim 7, wherein a support part
supporting said sliding cylinder is formed at said cylinder; a
suction passage for sucking a gas into said cylinder and a
discharge passage for discharging a gas are mounted near said
support part and a double cylinder part so as to be almost vertical
to a vibrating blade part; a valve configured in a sheet structure
for opening and closing said discharge passage and a discharge
valve presser for pressing down said valve are provided at said
discharge passage.
12. A hand-held vacuum pump of one of claims 7 to 11, wherein a
diameter of said hand-held vacuum pump is 30 mm or shorter, its
length is 70 mm or shorter, and its weight is 250 g or lighter;
said electric motor is driven by a dry cell or a secondary battery
providing an output voltage between 4V and 9V; and an overall
exhaust velocity when driven by said vacuum pump at 4000 to 6000
rpm is about 80 mL/sec.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a hand-held vacuum pump,
and specifically to a hand-held vacuum pump preferable for an
automated urinary drainage system.
[0002] An example of the urine suction apparatus for urinary
drainage for the people finding difficulty in moving on his or her
own ability to the place where he or she relieve himself or herself
is described in the Japanese Patent Application Laid-Open No.
2003-126242. In the urine suction apparatus sited in this Patent
Gazette, a urine storage container is located between the urine
receiver and the suction pump operated as the suction engine. When
the urine is discharged into the urine receiver, the urine
discharge is detected and the discharged urine is sucked from the
suction pipeline into the urine storage container. In this
operation, the suction operation of the suction pump is controlled
by referring to the signal from the pressure sensor for detecting
the changes in the pressure inside the urine storage container.
[0003] A lightweight vacuum pump is used generally for the suction
pump. An example of this type of vacuum pump is described in the
Japanese Patent Application Laid-Open No. 2002-195180 and the
Japanese Patent Application Laid-Open No. 8-296575. In the
compressor described in the Japanese Patent Application Laid-Open
No. 2002-195180, in order to improve the sliding characteristic and
ultimately the efficiency, such a sliding member as providing a
continuous lubrication function by means of self-lubricating
operation is provided at the rotary compressor. In contrast, in the
movable vane compressor and vacuum pump described in the Japanese
Patent Application Laid-Open No. 8-296575, the compressor room and
the pump room for the sealing fluid are partitioned separately and
hermetically, and the sealing fluid discharged out from the pump
room is supplied to the sealing part and the lubricating part.
[0004] In the conventional urine suction apparatus sited in the
Japanese Patent Application Laid-Open No. 2003-126242, what is
disclosed is that the operation state of the suction pump operated
as suction engine is changed in response to the pressure inside the
urine storage container. However, in the Japanese Patent
Application Laid-Open No. 2003-126242, there is not sufficient
consideration for downsizing the suction pump and reducing its
operation noise. In case of downsizing the overall system in order
to increase the portability of the urine suction apparatus, it is
required to downsize the suction pump itself. Although one of the
most effective methods for downsizing the pump is to increase the
rotating speed of the pump, in case of attempting to increase the
rotating speed of the pump, especially the positive displacement
pump generally used as the small-sized pump, the relative gap
between the rotating member and the stationary member increases
which leads to reducing the efficiency. In addition, increasing the
rotating speed simply may result in the increase in the noise
generated from the pump. As for the urine suction apparatus, the
usage out of doors as well as the usage bedside especially in the
night should be considered, which requires inevitably the reduction
of the noise.
[0005] In contrast, in the compressor sited in the Japanese Patent
Application Laid-Open No. 2003-126242 and Japanese Patent
Application Laid-Open No. 8-296575, the reliability of the sealing
part and the lubricating part is increased in order to prevent the
reduction in efficiency due to the downsizing of the overall
system. However, as this compressor is not intended to be used for
the hand-held medical device such as urinary drainage system, the
downsizing of the compressor may experience a complexity in the
structure of the compressor itself that is the result of the design
respecting the performance primarily. In addition, the intended use
of the compressor does not assume the usage in the night, and thus,
there is not sufficient consideration of the reduction of the noise
generated in the intermittent operation of the compressor.
BRIEF SUMMARY OF THE INVENTION
[0006] In order to solve the problems in the prior art, an object
of the present invention is to downsize the vacuum pump and
increase its portability. Another object of the present invention
is to increase the reliability of the vacuum pump having
portability. Further another object of the present invention is to
enable the urinary drainage system having a vacuum pump to be used
in the night and out of doors.
[0007] The characterized feature of the present invention to
achieve the above object is that, in the hand-held vacuum pump in
which the electric motor and the main body of the vacuum pump are
connected through the shaft coupling, one bearing supporting the
driving shaft included in the main body of the vacuum pump is
supported by the cylinder and the other bearing is supported by the
flange mounted hermetically at the cylinder, and the end part of
the cylinder near the electric motor accommodates the shaft
coupling and is engaged with the end part of the electric motor,
and the electric motor supports the cylinder.
[0008] In the characterized feature described above, the round hole
to be engaged with the rotating shaft of the electric motor is
formed at one side of the shaft coupling and the quasi-square hole
to be engaged with the driving shaft passing through inside the
cylinder is formed at the other side of the shaft coupling, and the
hole to be engaged with the rotating shaft of the electric motor is
formed at the driving shaft, which may eliminates preferably the
locking screw for fixing the shaft coupling and the rotating shaft
of the electric motor. In addition, it is preferable that the
material of the shaft coupling is made to be resin, and plural
protruding parts extending in the axial direction on the inside
face of the round hole formed at the shaft coupling are formed, or
that plural holes extending in the radial direction communicating
with this round hole are formed.
[0009] In the characterized feature described above, it is
preferable that a couple of sliding cylinders having a circular arc
part and clamping both sides of the intermediate part of the
extension part configured as a plate structure is provided, and
this sliding cylinder is supported by the cylinder and the sliding
cylinder is made oscillating inside the cylinder, and the cylinder
and the piston are formed as double cylinders, and that the pump
room is formed so that the shape of the pump room may change
between the double cylinders.
[0010] In the characterized feature described above, it is
preferable that the piston is mounted at the driving shaft through
the eccentric shaft, this piston has a blade part configured as a
plate structure extending towards the outer side at a part of its
periphery, the sliding cylinder having a circular arc part supports
this blade part so as to freely oscillate, and that the material of
the driving shaft is made to be stainless steel, the material of
the shaft coupling is made to be PC resin or POM resin, the
material of the piston is made to be PS resin or PC resin, the
material of the cylinder is made to be PBT resin, and the material
of the sliding cylinder is made to be PPS resin or PBT resin. Note
that PC stands for Polycarbonade, POM stands for Polyacetal, PS
stands for Polystyrene, PPS stands for Polyphenylene Sulfide, and
PBT stands for Polybutylene Terphthalate.
[0011] In addition, in the characterized feature described above,
it is preferable that the balance weight is mounted at the end part
of the driving shaft for compensating the eccentricity between the
piston and the eccentric shaft, and the cover for covering the
balance weight is mounted at the flange, and the material of the
flange is made to be POM resin, and the cylinder and the piston are
formed as double cylinders, and that the gas inside the pump room
is compressed by changing the volume of the pump room formed
between the double cylinders by oscillating the blade part.
[0012] In addition, in the characterized feature described above,
it is preferable that the beveled cut part having a cross-sectional
shape of shaft shaped in D-sigmoid is formed at the driving shaft,
and the hole corresponding to this D-sigmoid shape is formed at the
eccentric shaft, and plural protruding parts extending in the axial
direction are formed inside the hole shaped in D-sigmoid formed at
the eccentric shaft, and that the support part supporting the
sliding cylinder is formed at the cylinder, and the suction passage
for sucking the gas into the cylinder and the discharge passage for
discharging the gas are mounted near this support part and the
double cylinder part so as to be almost vertical to the vibrating
blade part, and a valve configured in a sheet structure for opening
and closing the discharge passage and a discharge valve presser for
pressing down this valve are provided at the discharge passage. In
addition, it is preferable that the diameter of the hand -held
vacuum pump is 30 mm or shorter, its length is 70 mm or shorter,
and its weight is 250 g or lighter, and the electric motor is
driven by the dry cell or the secondary battery providing an output
voltage between 4V and 9V, and that the overall exhaust velocity
when driven by this vacuum pump at 4000 to 6000 rpm is about 80
mL/sec.
[0013] In another characterized feature of the present invention,
the automated urinary drainage system includes the hand-held vacuum
pump having either one of the characterized aspects described above
which provides the exhaust speed around 80 mL/sec and the weight of
250 g or lighter.
[0014] According to the present invention, as the structure of the
vacuum pump is simplified, it will be appreciated that the
downsizing of the vacuum can be attained and the portability can be
increased. As the positioning accuracy at the individual parts is
increased by using a simplified structure and the lubrication
between the stationary parts and the moving parts are sufficiently
provided, it will be appreciated that the reliability of the vacuum
pump having portability can be increased. As the positioning
accuracy is increased, it will be appreciated that the number of
noise generation sources and their noise intensity can be reduced,
and the urinary drainage system to which this vacuum pump is
applied can be used in the night and/or out of doors.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0015] FIG. 1 is a side cross-section view of one embodiment of the
hand-held vacuum pump of the present invention.
[0016] FIG. 2 is an A-A cross-section view of FIG. 1.
[0017] FIG. 3 is a perspective exploded view of the rotor part of
the vacuum pump shown in FIG. 1.
[0018] FIG. 4 is a perspective exploded view of the shaft coupling
of the vacuum pump shown in FIG. 1.
[0019] FIG. 5 is a perspective exploded view of the driving shaft
part used for the vacuum pump shown in FIG. 1.
[0020] FIG. 6 is a side view of the shaft coupling used for the
vacuum pump shown in FIG. 1.
[0021] FIG. 7 is a perspective exploded view of another embodiment
of the shaft coupling used for the vacuum pump shown in FIG. 1.
[0022] FIG. 8 is a side view of the end part of the driving shaft
used for the vacuum pump shown in FIG. 1.
[0023] FIG. 9 is a front view and a side view of the discharge
valve stopper 19 used for the vacuum pump shown in FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0024] Now referring to the attached figures, one embodiment of the
hand-held vacuum pump according to the present invention will be
described. The vacuum pump in this embodiment is mainly used for
the urinary drainage system. FIG. 1 is a vertical cross section
view of the vacuum pump, and FIG. 2 is an A-A cross-section view of
FIG. 1. FIG. 3 is an exploded and perspective view of the main part
of the vacuum pump shown in FIG. 1 and its B-B cross-section view,
and FIG. 4 is an exploded and perspective view of the end part of
the shaft of the vacuum pump shown in FIG. 1, and FIG. 5 is an
exploded and perspective view of the shaft of the vacuum pump shown
in FIG. 1.
[0025] In the hand-held vacuum pump 1, the main body 1a of the
vacuum pump is connected to one side of the driving motor 2 through
the shaft coupling 21. The motor 2 drives the vacuum pump 1 at the
rotating speed between 4000 rpm and 7000 rmp. The diameter of the
motor 2 is about 30 mm, and its axial length is about 35 mm. The
motor 2 is driven by the dry cell or the secondary battery
providing the voltage between 4V and 9V.
[0026] The intermediate part in the axial direction of the driving
shaft 10 connected to the motor shaft 2a through the shaft coupling
21 is engaged to the hole formed at the eccentric position inside
the cylindrical eccentric shaft 11, and the eccentric shaft 11 is
driven around the eccentric axis around the motor shaft 2a. The
needle bearing 12 is engaged at the periphery of the eccentric
shaft 11. Both right and left ends in the axial direction of the
eccentric shaft 11 are supported by the ball bearings 15a and 15b
so as to rotate freely. The balance weight 13 is mounted at the
contact face 10f of the eccentric shaft 11 at the opposite side of
the motor, that is, the left end part shown i n FIG. 1, on the
basis of the contact face of the balance weight. The balance weight
13 is supported at the eccentric shaft 11 by the stopper 14.
[0027] In order to prevent the lubricant which is coated at the
ball bearing 15a supported at the ball bearing supporting part 5a
shaped in a cylinder, but is not shown in the figure, from flying
in all directions, the lubricant reservoir dish 5b shaped in a cone
is mounted around the ball bearing supporting part 5a. In case of
installing the needle bearing 12 between the piston 3 and the
eccentric shaft 11, the needle bearing fixing part 11d for
supporting the needle bearing 12 is formed by pressing the inner
ring of the needle bearing 12 in the axial direction.
[0028] The part of the driving shaft 10 on the side of the balance
weight 13 is covered by the cover 6 engaged with the flange 5. The
fixing plate 4d for fixing the vacuum pump 1 at the urinary
drainage system is provided on one side 4c of the cylinder 4. In
addition, the end part of the cylinder 4 on the side of the motor 2
is shaped in a cylinder, and accommodates the shaft coupling 21 and
is engaged with the engage part formed at the electric motor 2.
Owing to this structure, the cylinder 4 can be directly supported
by the motor 2. The outer part of the cylinder corresponding to the
pump room 4a is formed as a double structure, and the motor base 20
for supporting the periphery of the motor 2 is mounted at the end
part of this double structure on the side of motor 2. Thus, the
cylinder 4 is supported by the motor 2 also with the motor base
20.
[0029] The ball bearing 15b is supported at the cylinder 4
integrated with the casing which is a container shaped like a
"Snowman" and has an open structure at the left side shown in FIG.
1. On the other hand, the left side ball bearing 15a is supported
by the ball bearing supporting part 5a formed at the flange 5. The
flange 5 is a member configured at the in a plate structure
covering the open face of the cylinder 4, and the dedicated sheet
17 is arranged between the flange and the cylinder so as to be
engaged hermetically with the cylinder 4. The dedicated sheet 17 is
a sheet composed of PTFE, and used for compensating the molding
error and the assembling error of the cylinder 4 composed of a
resin material, the eccentric shaft 11, the piston 3 and the
sliding cylinders 7a and 7b, which will be described in detail
below.
[0030] As the cylinder 4 slides on the dedicated sheet 17, the
dedicated sheet is composed of easy-to-slide material. The
dedicated sheet 17 can change its shape when sliding with the
cylinder 4. The piston 3 is mounted at the periphery of the needle
bearing 12, and this piston 3 have a ring and a blade 3a formed by
extending one part on the circumferential direction of this ring
toward the outer side. The eccentric shaft 11, the needle bearing
12 and the piston 3 are accommodated inside the cylinder 4.
[0031] The intermediate part of the blade 3a is clamped at the left
and right sides by the sliding cylinders 7a and 7b forming a part
of the cylinder. The sliding cylinders 7a and 7b are supported by
the protruding part of the cylinder 4 with its inner surface shaped
so as to be fit to the external shape of the sliding cylinders 7a
and 7b. The head part of the blade 3a extends towards the space
shaped in a elliptic cylinder formed at the inner face of the
protruding part of the cylinder 4. The lower part of the piston 3
is shaped in a cylinder, and its peripheral surface 3b faces to the
inner surface 4a of the lower part of the cylinder 4 shaped in a
cylinder. The gap between the piston 3 and the cylinder 4
establishes a very little clearance in order to keep the sealing
performance even at the narrowest gap. The piston 3 has a swirling
motion inside the cylinder 4. When the piston 3 swirls with a
constant radius, the bicephalic space 4b formed between the inner
surface 4a of the cylinder 4 and the piston 3 moves by following to
this swirling motion. Then, the gaseous component is taken in from
the intake passage 8 and discharged to the discharge passage 9.
[0032] The intake passage 8 and the discharge passage 9 are formed
in the vertical direction orthogonal to the driving shaft 4 near
the supporting part of the cylinder 4 for supporting the sliding
cylinders 7a and 7b. The intake passage 8 and the discharge passage
9 are open to the pump room 4b. The valve seat 9b is formed at the
discharge passage 9, and the discharge valve 9a contacts to this
valve seat 9b. The discharge valve 9a is a silicon sheet having a
thickness of 0.5 mm. The discharge valve stopper 19 presses down
the discharge valve 9a towards the opposite direction of the
discharge flow. The discharge valve 9a to be mounted at the
discharge passage 9 is mounted at the location that is possibly
located on the internal surface 4a of the cylinder and near the
blade 3a in order to reduce the dead volume. In this embodiment,
the valve seat 9b is formed by forming a hole larger than the
diameter of the discharge passage 9 on the side of cylinder side
face at the discharge passage.
[0033] The detail structure of the discharge valve stopper 19 is
shown in FIG. 9. FIG. 9(a) shows the front view, and FIG. 9(b)
shows the side view. The discharge valve stopper 19 is formed by
processing and forming a round-bar material. A through-hole 19y is
formed at the center part of the round bar, and a stepped shape
having the step size 19d equivalent to the discharge valve stroke
in the axial direction is formed at its back face. As shown in FIG.
9, a part of the step has a canted part. The slotted part 19j,
which is a groove developed in the radial direction, is formed at
the front side of the round bar, and the round hole 19x larger than
the diameter of the through hole 19y is formed up to the
intermediate part in the axial direction. The hexagon hole 19i is
formed at the backside of the round hole 19x, which is used for
mounting the discharge vale stopper 19 by using the hexagonal
wrench. The diameter 19a of the discharge valve stopper 19 is 5.0
mm.
[0034] The discharge valve 9a having the diameter almost identical
to the diameter of the discharge valve stopper 19 is arranged at
the backside of the discharge valve stopper 19. The discharge valve
9a is a circular plate made of PTFE with 0.1 mm thickness, and its
top part to the stepped part are pressed down by the discharge
valve stopper 19 in accordance with the shape of the discharge
valve stopper 19. Thus, the discharge valve can bend right and left
at its stepped part to its lower part due to the pressure inside
the discharge passage 9. The valve stopper length 19b, measured
from the top part to the stepped part, is 1.15 mm. The valve
aperture angle 19c, which is the canted angle of the stepped part,
is 45 degrees. The discharge valve 9a bends with the supporting
points at the valve aperture supporting parts 19e and 19f, which
are located at the both ends of the canted parts. As the lower end
part of the discharge valve 9a can bend with the supporting point
at the valve aperture supporting part 19f, the communication
channel between the front side of the discharge valve stopper 19
and the backside of the discharge valve 9a can be established when
the discharge valve 9a bends.
[0035] As the height of the air discharge port 19h is established
the inner side of the thick part 19g of the ring formed by the
penetration hole 19y formed at the discharge valve stopper 19, the
channel communicating from the penetration hole 19y to the slotted
part 19j of the groove width 19K is formed. Owing to this
structure, the discharge valve can be operated definitely
independently of the installation state of the vacuum pump. Note
that the noise generated by opening and closing the discharge valve
9a can be reduced because the stepped part is formed as a canted
shape.
[0036] As shown in detail in FIG. 4, the driving shaft 10 and the
rotating shaft 2a of the motor 2 are linked together with the shaft
coupling 21. The shaft coupling 21 is shaped in a cylinder, and has
a round hole 21 a formed at the side where the rotating shaft 2a of
the motor 2 is engaged with the shaft coupling. On the other hand,
a quasi-rectangular hole (square hole) 21b which is formed by
cutting a circle with a couple of lines is formed at the side where
the driving shaft 10 is engaged with the shaft coupling. A fillet
having a couple of planes 10b and 10c parallel to each other is
formed at the driving shaft 10 corresponding to this square hole. A
round hole 10a with which the rotating shaft of the motor can be
engaged is formed at the center part of the driving shaft 10.
[0037] In the vacuum pump 1 so configured as described above, the
flange 5 and the dedicated sheet 17 are hermetically mounted at the
cylinder 4, and then the pump room 4b is formed. The protruding
part 4e is formed on the surface of the cylinder facing to the
flange 5, and this protruding part is transformed when installing
the flange 5 at the cylinder 4, and thus, the protruding part 4e
and the dedicated sheet 17 firmly contact to the flange 5. Owing to
this structure, the sealing performance of the pump room 4b is
established.
[0038] When the motor shaft 2a rotates, the eccentric shaft 11
rotates in an eccentric motion, and then the piston 3 mounted at
the peripheral side of the eccentric shaft also rotates in an
eccentric motion. In this operation, the movement of the blade 3a
of the piston 3 is limited by the sliding cylinders 7a and 7b, and
then the rotation of the piston 3 on its own axis is blocked. The
material and shape (as a part of the cylinder) of the sliding
cylinders 7a and 7b blocking the rotation of the blade 3a on its
own axis is selected to be appropriate for sliding performance in
order to make the movement of the blade 3a smooth.
[0039] In this embodiment, the rotation driving power of the motor
2 is transmitted to the driving shaft 10 by using the static
friction generated between the rotating shaft 2a of the motor and
the round hole 21a. When the shaft coupling 21 rotates, the turning
force is transmitted from the square hole 21b formed at the shaft
coupling 21 to the flat surfaces 10b and 10c of the fillet of the
driving shaft 10, and thus the driving shaft 10 rotates. Though the
shaft coupling 21 was fixed at the shaft 10 by using the clamp
screw in the prior art, this embodiment does not use the clam
screw. The reason is that the application of the clamp screw makes
the weight of the clamp screw itself operate as unbalanced load
that may result in an occurrence of vibration. As this embodiment
does not use the clamp screw, it will be appreciated that the
driving shaft 10 and the shaft coupling 21 can be engaged firmly.
In addition, in view of the disassembly operation for the driving
shaft 10 and the shaft coupling 21, PC (Polycarbonate) resin is
used for the material of the shaft coupling 21, which is aimed for
weight saving and abrasion resistance.
[0040] Though this embodiment uses the shaft coupling 21 made of
Polycarbonate for the reason described above, it is difficult for
the shaft coupling 21 made of the resin material to establish the
same level of molding accuracy as the metallic shaft coupling. In
order to prevent the axial alignment deviation between the rotating
shaft 2a of the motor 2 and the driving shaft 10 due to the molding
error, this embodiment uses such a structure that the rotating
shaft 2a of the motor 2 can be inserted into the round hole 10a.
Owing to this structure, the vibration at the high-speed rotation
which may result from the slight deviation in the axial alignment
between the rotating shaft 2a of the motor 2 and the driving shaft
10 can be reduced as well as the mechanical loss can be prevented.
In addition, the axial length of the vacuum pump 1 can be reduced,
which contributes to the downsizing of the vacuum pump 1.
[0041] This embodiment uses such a structure that the shaft
coupling 21 is not fixed at the rotating shaft 2a of the motor 2 by
using the clamp screw and can be dismounted from the motor 2
without using the clamp screw. In the structure of this embodiment,
the protruding part 21c extending in the axial direction shown in
detail in FIG. 6 is formed on the inner surface of the round hole
21a of the shaft coupling 21. Plural protruding parts 21c are
formed with an interval in the circumferential direction on the
inner surface of the shaft coupling 21c. FIG. 6(a) shows the side
view of the shaft coupling 21c alone, and FIG. 6(b) is a
cross-section view of the structure in which the shaft coupling 21
is mounted at the rotating shaft 2a of the motor 2. As the rotating
shaft 2a is inserted into the shaft coupling 21, the protruding
parts 21c of the shaft coupling 21 made of the resin material are
deformed elastically.
[0042] As plural protruding parts 21c are formed on the inner
surface of the shaft coupling 21, the rotation torque generated by
the rotating shaft 2a of the motor 2 can be transmitted definitely
to the shaft coupling 21 owing to the friction force. In addition,
owing to the deformation of the protruding parts 21c, the accuracy
of positioning, that is, axial alignment of the rotating shaft 2a
of the motor 2 can be established. Owing to the deformation of the
protruding parts 21c, the touch area between the rotating shaft 2a
of the motor 2 and the shaft coupling required for transmitting the
torque can be ensured. The height of the individual protruding part
21c is determined so that the gap between the protruding part 21c
and the rotating shaft 2a engaged to each other may not be
developed when inserting the rotating shaft 2a of the motor 2.
Thus, even if the finished size of the round hole 21a is a little
consistently different from the designed value or its finishing
accuracy has a little deviation, and even if the difference between
the material of the rotating shaft 2a and the material of the shaft
coupling 21 may result in the difference in their heat deformation,
there is no gap between the protruding parts 21c and the rotating
shaft 2a, and hence, the rotation torque can be definitely
transmitted.
[0043] The rotation torque is transmitted from the side surface of
the square hole 21b of the shaft coupling 21 and the flat surfaces
10b and 10c of the fillet of the driving shaft 10 to the driving
shaft 10. The square hole 21b and the fillet are used not only for
transmitting the torque but also for positioning the parts when
assembling the parts. By aligning the flat surfaces 10b and 10c of
the fillet onto the two side surfaces of the square hole 21b, the
shaft coupling 21 can be positioned to the driving shaft 10 in the
vertical and horizontal directions, respectively. In addition, the
rotating shaft 2a of the motor 2 can be positioned to the round
hole 10a of the driving shaft 10 only by inserting the fillet into
the square hole 21b of the shaft coupling 21.
[0044] FIG. 7 shows another embodiment of the shaft coupling. In
the above embodiment, the shaft coupling 21 is fixed at the
rotating shaft 2a and the driving shaft 10a by the protruding part
21c extending in the axial direction and the fillet. In this
embodiment, plural rigidity reducing holes 22c extending in the
radial direction of the shaft coupling 22 are formed approximately
at the axially symmetrical positions. As the shaft coupling 22 is
composed of resin material, the inner surface of the rigidity
reducing hole 22c is deformed plastically to the inward side when
processing the rigidity reducing hole 22c. Due to this deformation,
when inserting the rotating shaft 2a into the round hole 22a, the
inner surface of the round hole 22a is flared by the rotating shaft
2a and the firm engagement between the rotating shaft 2a and the
shaft coupling 22 is established in the circumferential direction
without gap. On the side of the driving shaft 10, the groove 22b is
formed so as to extend to the periphery corresponding to the shape
of the end part of the driving shaft 10. According to this way of
forming the shaft coupling 22, the positioning between the motor
shaft 2a and the driving shaft 10 can be easily established and the
thermal deformation is treated in the similar way to the above
embodiment.
[0045] Now, referring to FIG. 3 and FIG. 5, the operation of the
pump is described. At the one position on the periphery of the
driving shaft 10, the slotted surface 10d is formed and the
cross-section of the driving shaft is shaped in a circle truncated
with a straight line. As the hole (hole for the driving shaft) 11a
having the same cross-sectional shape as the cross-section of the
driving shaft at the slotted surface 10d is formed at the eccentric
shaft 11, the position of the eccentric shaft 11 in the peripheral
direction can be determined only by inserting the driving shaft 10
into the hole 11a for the driving shaft. When the driving shaft 10
rotates, the rotation torque is transmitted from the slotted
surface 10d to the flat face 11b of the hole 11a for the driving
shaft, and then the eccentric shaft 11 rotates. In this operation,
the axle center of the eccentric shaft 11 and the axle center of
the driving shaft 10 are not aligned to each other, the eccentric
shaft 11 rotates in an eccentric motion.
[0046] In the above operation, due to the assembly error and gap
between the eccentric shaft 11 and the driving shaft 10, the
vibration gives rise to the eccentric shaft 11 and the vibration
amplitude may increase due to the eccentric rotating motion of the
eccentric shaft 11. As a result, the mechanical efficiency is
reduced and the friction loss and abrasion at the sliding surface
between the cylinder 4 and the piston 3 occur. Consequently, the
abrasion and the thermal deformation cause the decrease in the
lifetime of the vacuum pump 1. In order to prevent those
disadvantages, this embodiment uses the eccentric shaft 11 made of
PPS (Polyphenylene Sulfide). By means of using the eccentric shaft
11 made of PPS, as this material is lightweight and advantageous
for abrasion resistance and heat resistance as well as relatively
low abrasion resistance among other resin materials, the vacuum
pump 1 can be operated over the long term.
[0047] As the eccentric shaft 11 is lightweight, the unbalanced
force distribution (centrifugal force) due to the eccentric
rotating motion can be reduced and thus the required mass of the
balance weight 13 can be reduced. Owing to this configuration, the
downsizing of the vacuum pump can be achieved. Though this
embodiment uses such a structure that the driving shaft 10 and the
eccentric shaft 11 are engaged to each other, it is allowed to
apply the insert molding process to integrate both parts. In case
of insert molding, the driving shaft is positioned inside the die
assembly and then the resin material for forming the eccentric
shaft is filled in this die assembly. By means of forming the
eccentric shaft 11 by the insert molding process, the alignment
between the eccentric shaft and the driving shaft 10 can be
established, which leads to increasing the performance of the
compressor and reducing the man-hour cost for fabrication.
[0048] In contrast to the resin material used for the eccentric
shaft, metallic material which has an advantageous property in
mechanical strength is used for the driving shaft 10. As the
driving shaft 10 is made of metallic material, the coefficient of
thermal expansion of the driving shaft is different from the
coefficient of the thermal expansion of the resin-made eccentric
shaft 11. Due to the difference in their coefficients of the
thermal expansion, the eccentric shaft 11 tends to transform its
shape in the peripheral direction to the driving shaft 10. In order
to this problem, plural protruding parts 11c is formed so as to
extend in the axial direction on the flat face 11b of the eccentric
shaft 11. FIG. 8 shows the outline of the hole 11a for the driving
shaft formed at the eccentric s haft 11. FIG. 8(a) is an outline of
the hole 11a for the driving shaft alone, and FIG. 8(b) is a
cross-section view when inserting the driving shaft 10 into the
hole 11a.
[0049] In the similar manner to the case of the relation between
the rotating shaft 2a of the motor 2 and the shaft coupling 21,
when the driving shaft 10 is inserted into the hole 11a for the
driving shaft, the protruding part 11c extending in the axial
direction is deformed elastically or plastically, and then, the gap
between the driving shaft 10 and the eccentric shaft 11 goes out of
existence. Then, even if the driving shaft 10 and the eccentric
shaft 11 yield to the heat deformation due to the heat generated by
the rotational movement of the driving shaft 10, the steady state
that the gap between he driving shaft 10 and the eccentric shaft 11
does not exist can be maintained owing to the deformation of the
protruding part 11b. Thus, the relative displacement of the
eccentric shaft 11 in the circumferential direction relative to the
driving shaft 10 can be prevented.
[0050] In this embodiment, three protruding parts 11c extending in
the axial direction are formed on the flat face 11b with its
cross-section shaped in D-sigmoid. In addition, as the length
measured in the axial direction of the flat face 10d of the driving
shaft 10 ad the flat face 11b of the eccentric shaft 10 is long,
the flat faces 10d and 11b are made slanted in the axial direction
in view of easiness for assembly and disassembly. The inclination
angle in this slanted structure is about 1 degree. As the vibration
due to the existence of the gap between the driving shaft 10 and
the eccentric shaft 11 is reduced as in the above-described way,
the required mass for the balance weight 13 can be reduced.
[0051] A case study of applying the above-described small-sized
vacuum pump 1 to the automated urinary drainage system will be
described below. The entire component including the vacuum pump 1
is required to be replaced periodically in view of sanitary
supervision for the automated urinary drainage system. In order to
make the replacement parts recyclable, the component of the vacuum
pump 1 is so configured as to be enabled to be disassembled
material by material. Table 1 summarizes the analysis of easiness
of assembly and disassembly and the preferable materials to be
selected. TABLE-US-00001 TABLE 1 Performance Requirement (required
feature marked with .largecircle.) Coefficient of Heat Expansion
Material (marked Friction Coefficient selected in Light Heat with
.largecircle. for Abrasion (marked with .largecircle. for Urinary
Easiness for the Part Symbol Weight Strength Resistance smaller
values) Resistance larger values) Resistance Molding Process
embodiment Driving 10 .largecircle. .largecircle. Metal Shaft
(Stainless) Shaft 21 .largecircle. .largecircle. PC/PCM Coupling
Piston 3 .largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. PS/PC Eccentri 11 .largecircle.
(Equivalent to .largecircle. .largecircle. PBT/PPS Shaft Piston)
.largecircle. Cylinder 4 .largecircle. (Equivalent to .largecircle.
.largecircle. .largecircle. PBT Integrate Piston) .largecircle.
with Casing Sliding 7a, 7b .largecircle. (Larger than .largecircle.
.largecircle. PPS/PBT Cylinder Piston) .largecircle. Flange 5
(Equivalent to .largecircle. .largecircle. POM Piston)
.largecircle. Cover 6 .largecircle. POM Motor 20 .largecircle. POM
Base
[0052] As determined from the above reason, the materials used for
the driving shaft 10 and the eccentric shaft 11 are selected to be
stainless steel and PBT/PPS, respectively. The material used for
the piston 3 is selected to be PC/PC which has such advantageous
chemical-resistant properties as weak-acid resistance and
weak-alkali resistance. Those materials have an advantageous
mechanical deformation property.
[0053] The individual parts of the vacuum pump 1 expand due to heat
in the operation of the vacuum pump 1. The materials used for the
cylinder 4, the eccentric shaft 11 and the sliding cylinders 7a and
7b for guiding the blade part 3a of the piston 3 are made
approximately identical to one another in order to reduce the
stress generated due to the thermal expansion. In this embodiment,
the material used for those parts is determined to PS
(Polystyrene). In case of increasing the sliding performance by
installing the needle bearing 12 between the eccentric shaft 11 and
the driving shaft 10, the needle bearing supporting part 3c for
supporting the end face of the needle bearing 12 is formed at the
eccentric shaft 11.
[0054] Corresponding to the position where the ball bearing 15a and
15b are supported by the cylinder 4, the ball bearing positioning
seats 11g and 11h for pressing down in the axial direction to the
inner face of the ball bearing 15a and 15b are formed at the
eccentric shaft 11. Those ball bearing positioning seats 11g and
11h are shaped in a cylinder, and their length in the axial
direction is about 0.5 mm. The size of the eccentric shaft 11 in
the axial direction is almost the same as the width of the piston 3
and the pump room 4b.
[0055] As for the material to be used for the cylinder, such a
material that has an advantageous property in abrasion resistance
and heat resistance and has weak-acid resistance and weak-alkali
resistance and has a mechanical property of easiness for molding
should be selected. As the cylinder 4 slides with the piston 3, the
material to be used for the cylinder 4 is selected to be PPS
(Polyphenylene Sulfide) or PBT (Polybutylene Terphthalate) having
approximately the same coefficient of thermal expansion as the
material of the piston 3. The material to be used for sliding
cylinders 7a and 7b guiding the blade part 3a of the piston 3 is
selected to be the material having an advantageous property in
abrasion resistance and heat resistance and having approximately
the same coefficient of thermal expansion as the material of the
piston 3. In this embodiment, also in view of easiness for molding
process, PPS or PBT is used for the material of the sliding
cylinders 7a and 7b.
[0056] The material to be used for the flange 5 is selected to be
the material having easiness for molding process, and having
approximately the same coefficient of thermal expansion as the
material of the piston 3 and the cylinder 4. The material to be
used for the flange requires a certain level of abrasion resistance
which might not be less than the material to be used for the other
sliding parts. In this embodiment, the material to be used for the
flange is Homopolymer of POM (Polyacetal). In view of easiness for
molding process, the material to be used for the motor base 2 and
cover 6 is selected to be Copolymer of POM.
[0057] The size of the vacuum pump is determined on the basis of
the drained urinary volume. By referring to the article in Acta
Urologica Japonica, Vol. 33, No. 4, pp. 521-526, (April, 1987),
which describes the investigation results of the urinary volumes
for the individual generations (urinary volume per unit time), the
drained urinary volume of the adult people is estimated. According
to this paper, the maximum drained urinary volume of the young
adult people between 19 to 39 years old is 28.2.+-.4.6 mL per
second, which is larger than the volume of any other generation.
The maximum drained urinary volume is determined to be 40 mL per
second on the safer side. By considering the involvement of air and
the other fluid dynamics loss, the overall drainage speed of the
vacuum pump is determined to be 70 mL per second. Thus, assuming
that the diameter of the cylinder is 17.2 mm, its length is 16.3 mm
and the diameter of the piston is 14.0 mm, the drained volume per
single revolution of the piston is approximately 1.066 mL, and the
urine can be drained by 76.4 mL per second by the vacuum pump 1
driven at 4300 rpm. Assuming that there exists approximately 10%
loss, the urine can be drained approximately by 70 mL per
minute.
[0058] Though the sizes of the individual parts of the vacuum pump
and its rotating speed are determined as described above in this
embodiment, it is allowed to select another sizes and rotating
speed alternatively if the overall drain speed of 70 mL per second
is attained. As the downsizing and weight saving of the vacuum pump
can be established so far, the outline of the vacuum pump system
integrated with the motor can be determined so that the diameter
may be 30 mm or shorter and its length may be 70 mm or shorter.
Owing to this configuration, it will be appreciated that the dry
cell and the secondary battery, including solar cell and fuel cell,
having the output voltage approximately from 4V to 9V can be
supplied as the electric power unit.
[0059] Although the present invention has been illustrated and
described with respect to exemplary embodiment thereof, it should
be understood by those skilled in the art that the foregoing and
various other changes, omission and additions may be made therein
and thereto, without departing from the spirit and scope of the
present invention. Therefore, the present invention should not be
understood as limited to the specific embodiment set out above but
to include all possible embodiments which can be embodied within a
scope encompassed and equivalent thereof with respect to the
feature set out in the appended claims.
* * * * *