U.S. patent application number 11/176102 was filed with the patent office on 2006-01-12 for actuator and pump device.
Invention is credited to Hiroshi Sugihara, Kiyotsugu Takasawa, Mitsuo Yokozawa.
Application Number | 20060008367 11/176102 |
Document ID | / |
Family ID | 35541562 |
Filed Date | 2006-01-12 |
United States Patent
Application |
20060008367 |
Kind Code |
A1 |
Yokozawa; Mitsuo ; et
al. |
January 12, 2006 |
Actuator and pump device
Abstract
An actuator includes a fixed body and a movable body. The fixed
body includes a first yoke, a pair of drive magnets overlapped so
as to interpose the first yoke therebetween with their same
polarities being directed to the first yoke, and a second yoke
which faces an outer peripheral end face of the first yoke and is
superposed on respective end faces positioned on the outer sides of
the pair of drive magnets. The movable body includes a coil
disposed so as to surround around the outer peripheral end face of
the first yoke between the first yoke and the second yoke and the
coil is displaced in an axial direction by energization of the
coil. The actuator may be preferably applied to a pump device.
Inventors: |
Yokozawa; Mitsuo; (Nagano,
JP) ; Sugihara; Hiroshi; (Nagano, JP) ;
Takasawa; Kiyotsugu; (Nagano, JP) |
Correspondence
Address: |
CANTOR COLBURN, LLP
55 GRIFFIN ROAD SOUTH
BLOOMFIELD
CT
06002
US
|
Family ID: |
35541562 |
Appl. No.: |
11/176102 |
Filed: |
July 7, 2005 |
Current U.S.
Class: |
417/418 ;
417/415; 417/416; 417/417 |
Current CPC
Class: |
F04B 35/04 20130101 |
Class at
Publication: |
417/418 ;
417/415; 417/416; 417/417 |
International
Class: |
F04B 35/04 20060101
F04B035/04; F04B 17/04 20060101 F04B017/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 8, 2004 |
JP |
2004-201966 |
Claims
1. An actuator comprising: a fixed body including; a first yoke; a
pair of drive magnets which are overlapped so as to interpose the
first yoke therebetween with their same polarities being directed
to the first yoke; and a second yoke which faces an outer
peripheral end face of the first yoke and is superposed on
respective end faces positioned on outer sides of the pair of drive
magnets; and a movable body including, a coil which is disposed so
as to surround around the outer peripheral end face of the first
yoke between the first yoke and the second yoke, the coil being
displaced in an axial direction by energization of the coil.
2. The actuator according to claim 1, wherein the second yoke is
provided with a ring-shaped protruding part which protrudes so as
to face the outer peripheral end face of the first yoke.
3. The actuator according to claim 1, further comprising: a pair of
yoke members included in the second yoke which are formed in a
bottomed cylinder shape and capable of being divided in the axial
direction, the pair of yoke members being disposed such that
respective cylindrical body parts of the pair of yoke members are
butted with each other and bottom plate portions of the pair of
yoke members being overlapped on the respective end faces of the
pair of drive magnets, and a space which is formed by the second
yoke and the first yoke and the pair of the drive magnets for
allowing the movable body to move in the axial direction.
4. The actuator according to claim 1, further comprising: a coil
bobbin around which the coil is wound; and a guide member which is
disposed in a space which is formed by the second yoke and the
first yoke and the pair of drive magnets; wherein the coil bobbin
is provided with a guide part which engages with the guide member
for performing a guide operation to the movement of the movable
body.
5. The actuator according to claim 1, further comprising a
sheet-shaped elastic member which supports the coil disposed
between the first yoke and the second yoke such that the coil is
capable of moving in the axial direction.
6. A pump device comprising: an actuator comprising; a fixed body
including; a first yoke; a pair of drive magnets which are
overlapped so as to interpose the first yoke therebetween with
their same polarities being directed to the first yoke; and a
second yoke which faces an outer peripheral end face of the first
yoke and is superposed on respective end faces positioned on outer
sides of the pair of the drive magnets; and a movable body
including; a coil which is disposed so as to surround around the
outer peripheral end face of the first yoke between the first yoke
and the second yoke, the coil being displaced in an axial direction
by energization of the coil; and a pump chamber in which suction of
fluid and discharge of the fluid are performed by movement of the
movable body.
7. The pump device according to claim 6, further comprising: a
first pump chamber disposed on one side of the movable body in the
axial direction in a space which is formed by the second yoke; a
second pump chamber disposed on the other side of the movable body
in the axial direction in the space which is formed by the second
yoke; and a piston which is formed by the movable body.
8. The pump device according to claim 7, wherein the first pump
chamber and the second pump chamber are in communication with a
common fluid inlet port and a common fluid outlet port.
9. The pump device according to claim 7, further comprising: a
first fluid inlet port which is in communication with the first
pump chamber; a second fluid inlet port which is in communication
with the second pump chamber; a first fluid outlet port which is in
communication with the first pump chamber; and a second fluid
outlet port which is in communication with the second pump
chamber.
10. The pump device according to claim 6, further comprising: a
first pump chamber disposed on one side of the movable body in the
axial direction in a space which is formed by the second yoke; a
second pump chamber disposed on the other side of the movable body
in the axial direction in the space which is formed with the second
yoke; and a diaphragm which is formed by the movable body.
11. The pump device according to claim 10, wherein the first pump
chamber and the second pump chamber are in communication with a
common fluid inlet port and a common fluid outlet port.
12. The pump device according to claim 10, further comprising: a
first fluid inlet port which is in communication with the first
pump chamber; a second fluid inlet port which is in communication
with the second pump chamber; a first fluid outlet port which is in
communication with the first pump chamber; and a second fluid
outlet port which is in communication with the second pump
chamber.
13. The pump device according to claim 10, wherein the diaphragm
includes the coil and a sheet-shaped elastic member which supports
the coil disposed between the first yoke and the second yoke such
that the coil is capable of moving in the axial direction.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present invention claims priority under 35 U.S.C.
.sctn.119 to Japanese Application No. 2004-201966 filed Jul. 8,
2004, which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to an electromagnetic actuator
and to a pump device which is structured to perform a pumping
operation by utilizing the reciprocating movement of a movable body
in the actuator.
BACKGROUND OF THE INVENTION
[0003] A pump device provided with an electromagnetic actuator has
been proposed in which a pumping operation is performed by means of
a movable body disposed in a cylinder that is reciprocated by
electromagnetic force (see, for example, Japanese Patent Laid-open
No. Hei 5-240163, Japanese Patent Laid-open No. 2004-124724, and
Japanese Patent Laid-Open No. 2004-60641).
[0004] In a pump device as described in Japanese Patent Laid-Open
No. Hei 5-240163, a movable body provided with a drive coil is
disposed in a cylinder and a ring-shaped magnet is disposed outside
the cylinder. Further, a cylindrical yoke is extended to an inner
side of the drive coil from the magnet and a ferrite core is
disposed on the outer side of the coil such that the coil is
interposed between the cylindrical portion of the yoke and the
ferrite core. In a pump device described in Japanese Patent
Laid-open No. 2004-124724, a movable body provided with a drive
magnet is slidably disposed in the axial direction of a cylinder
and a drive coil is disposed on the outer peripheral side of the
cylinder. In a pump device in Japanese Patent Laid-open No.
2004-60641, a movable body provided with a drive magnet is
supported in the axial direction of a cylinder by an elastic member
in a movable manner and a drive coil is disposed on the outer side
of the cylinder.
[0005] However, in the pump device described in Japanese Patent
Laid-Open No. 2004-124724 or Japanese Patent Laid-open No.
2004-60641, since the drive magnet is disposed on the movable body,
a space is required between the drive magnet and its peripheral
magnetic member in consideration of the moving range of the drive
magnet so that the drive magnet is not attracted by the peripheral
magnetic member. Further, when the magnetic field is shielded so
that surrounding objects are not attracted by the drive magnet or
malfunctions are not induced in peripheral devices, it is necessary
to provide clearance for the full range of motion of the drive
magnet. Thus, the outer dimension of the actuator is quite
large.
[0006] Further, in the pump device described in Japanese Patent
Laid-Open No. Hei 5-240163, only one magnet can be disposed due to
the restriction on a layout, for example, that the yoke cannot be
disposed on the movable body. Therefore, since the magnetic flux
density interlining with the coil is lower, thrust acting on the
movable body becomes smaller.
SUMMARY OF THE INVENTION
[0007] In view of the problems described above, the present
invention may advantageously provide a small-sized actuator capable
of applying a large thrust to a movable body, and provide a pump
device with the actuator.
[0008] Thus, according to the present invention, there may be
provided an actuator including a fixed body having a first yoke, a
pair of drive magnets which are overlapped so as to interpose the
first yoke therebetween with their same polarities being directed
to the first yoke, and a second yoke which faces an outer
peripheral end face of the first yoke and is superposed on the
respective end faces positioned on outer sides of the pair of drive
magnets, and a movable body having a coil which is disposed so as
to surround around the outer peripheral end face of the first yoke
between the first yoke and the second yoke and the coil is
displaced in an axial direction by energization of the coil.
[0009] In an actuator in accordance with an embodiment of the
present invention, a pair of drive magnets are overlapped so as to
interpose the first yoke therebetween with their same polarities
being directed to the first yoke and a second yoke is disposed so
as to face the outer peripheral end face of the first yoke in a
fixed body. Therefore, the magnetic flux from the pair of the drive
magnets can be efficiently guided from the outer peripheral end
face of the first yoke in the direction perpendicular to the axial
direction. Accordingly, the density of magnetic flux interliking
with the coil is high which is disposed to surround around the
outer peripheral end face of the first yoke, and thus a large
thrust can be applied to the movable body. Further, the same
polarities of the two drive magnets are directed so as to face each
other but, since the first yoke is sandwiched between the two drive
magnets, assembling operations can easily be performed without
being affected by the repulsion of the two drive magnets. In
addition, since the drive magnets are disposed on the fixed body,
the drive magnets are not attracted to peripheral members even when
the drive magnets and the peripheral members are placed in a close
relation. Moreover, even when a shield is applied to the magnetic
field such that the peripheral members are not attracted to the
drive magnets or such that malfunctions are not induced in the
peripheral devices, the periphery of the drive magnets can be
covered in a compact manner because the drive magnets are fixed.
Consequently, the outer dimension of the actuator can be made
smaller. In addition, since the second yoke is disposed to cover
the drive magnets and the coil, the shield is efficiently attained
with the second yoke. Accordingly, since another shield member is
not required, the outer dimension of the actuator is not required
to be made larger.
[0010] In accordance with an embodiment of the present invention,
the second yoke is preferably provided with a ring-shaped
protruding part which protrudes toward and faces the outer
peripheral end face of the first yoke. According to the
construction described above, the magnetic flux density to the coil
can be enhanced which is disposed between the first yoke and the
second yoke. Therefore, since thrust acting on the movable body can
be increased, the response speed and the output characteristics of
the movable body can be improved. Further, the second yoke may
include a pair of yoke members which are formed in a bottomed
cylinder shape and capable of being divided in the axial direction.
The pair of the yoke members may be disposed such that the
respective end faces of respective cylindrical body parts of the
pair of the yoke members are butted with each other and that the
bottom plate portions of the pair of the yoke members are
overlapped on the respective end faces of the pair of drive
magnets. According to the construction described above, a space
that is formed by the second yoke and the first yoke and the pair
of the drive magnets can be utilized as the space within which the
movable body is moved in the axial direction. Further, since the
coil may be wound around the coil bobbin, the coil bobbin may be
preferably provided with a guide part which engages with a guide
member, which is disposed in a space formed by the second yoke and
the first yoke and the pair of drive magnets, for performing a
guide operation to the movement of the movable body. Further, the
coil may be supported by a sheet-shaped elastic member such that
the coil is capable of moving in the axial direction between the
first yoke and the second yoke.
[0011] The actuator in accordance with the present invention may be
applied to a pump device. In the pump device, the actuator may be
used to perform the suction of fluid to a pump chamber and the
discharge of the fluid from the pump chamber by the movement of the
movable body.
[0012] In this case, the movable body may be structured as a
piston, which serves to form a first pump chamber disposed on one
side of the piston in the axial direction in a space which is
formed with the second yoke and form a second pump chamber disposed
on the other side of the piston in the axial direction in the
space.
[0013] Further, the movable body may be structured as a diaphragm,
which serves to form a first pump chamber disposed on one side of
the diaphragm in the axial direction in a space which is formed
with the second yoke and form a second pump chamber disposed on the
other side of the diaphragm in the axial direction in the space.
The diaphragm may include the coil and a sheet-shaped elastic
member which supports the coil between the first yoke and the
second yoke such that the coil is capable of moving in the axial
direction.
[0014] In accordance with an embodiment of the present invention,
the pump device may be structured such that the first pump chamber
and the second pump chamber are in communication with a common
fluid inlet port and a common fluid outlet port. According to the
construction described above, fluid can be sent out alternately
from the first pump chamber and die second pump chamber, and thus
the flow rate of the fluid becomes large and the occurrence of
pulsating flow can be restrained.
[0015] Further, in accordance with an embodiment of the present
invention, the pump device may be provided with a first fluid inlet
port which is in communication with the first pump chamber, a
second fluid inlet port which is in communication with the second
pump chamber, a first fluid outlet port which is in communication
with the first pump chamber, and a second fluid outlet port which
is in communication with the second pump chamber. According to the
construction described above, different fluids can be respectively
sent out from the first pump chamber and the second pump chamber in
one pump device.
[0016] As described above, in the actuator of the present
invention, a pair of drive magnets are overlapped so as to
interpose the first yoke therebetween with their same polarities
being directed to the first yoke and a second yoke is disposed so
as to face the outer peripheral end face of the first yoke in the
fixed body. Therefore, the magnetic flux from the pair of the drive
magnets can be efficiently guided from the outer peripheral end
face of the first yoke in the direction perpendicular to the axial
direction. Accordingly, since the density of magnetic flux
interliking with the coil is high which is disposed to surround
around the outer peripheral end face of the first yoke, a large
thrust can be applied to the movable body. Further, the same
polarities of the two drive magnets face each other but, since the
first yoke is sandwiched between the two drive magnets, assembling
operations can easily be performed without being affected by the
repulsion of the two drive magnets. In addition, since the drive
magnets are disposed on the fixed body, the drive magnets are not
attracted by peripheral members even when the drive magnets and the
peripheral members are placed in a close relation. Moreover, even
when a shield is applied to the magnetic field such that the
peripheral members are not attracted to the drive magnets or such
that malfunctions are not induced in the peripheral devices, the
periphery of the drive magnets can be covered in a compact manner
because the drive magnets are fixed. Consequently, the outer
dimension of the actuator can be made smaller. In addition, since
the second yoke is disposed to cover the drive magnets and the
coil, the shield is efficiently attained by the second yoke.
Accordingly, since another shield member is not required, the outer
dimension of the actuator is not required to be larger.
[0017] Other features and advantages of the invention will be
apparent from the following detailed description, taken in
conjunction with the accompanying drawings that illustrate, by way
of example, various features of embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Embodiments will now be described, by way of example only,
with reference to the accompanying drawings which are meant to be
exemplary, not limiting, and wherein like elements are numbered
alike in several Figures, in which:
[0019] FIG. 1(a) is a schematic cross-sectional view showing an
entire structure of an actuator in accordance with an embodiment of
the present invention, and FIG. 1(b) is an explanatory view showing
the lines of magnetic force in the actuator.
[0020] FIG. 2 is a plan view showing a pump device in accordance
with an embodiment of the present invention.
[0021] FIG. 3(a) is a cross-sectional view showing the pump device
which is cut by the line of "A-A" in FIG. 2 and FIG. 3(b) is a
cross-sectional view showing the pump device which is cut by the
line of "B-B" in FIG. 2.
[0022] FIG. 4 is an exploded perspective view showing the pump
device shown in FIGS. 2 and FIGS. 3(a) and 3(b).
[0023] FIGS. 5(a) through 5(c) are cross-sectional views showing
another pump device in accordance with an embodiment of the present
invention. FIG. 5(a) is a cross-sectional view showing the pump
device that is cut at a position corresponding to the line of "A-A"
in FIG. 2, FIG. 5(b) is a cross-sectional view showing the pump
device which is cut at a position corresponding to the line of
"B-B" in FIG. 2, and FIG. 5(c) is an enlarged view showing a
portion of the pump device encircled by the line "C" in FIG.
5(a).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] An actuator and a pump device in accordance with embodiments
of the present invention are described below with reference to the
accompanying drawings.
Embodiment of Actuator
[0025] FIG. 1(a) is a schematic cross-sectional view showing the
entire structure of an actuator in accordance with an embodiment of
the present invention and FIG. 1(b) is an explanatory view showing
the lines of magnetic force in the actuator.
[0026] As shown in FIG. 1(a), an actuator 1 in accordance with the
embodiment of the present invention includes a fixed body 3 and a
movable body 2 provided with a coil 8 for constructing a
magnetic-drive circuit between the fixed body 3 and the movable
body 2.
[0027] The fixed body 3 includes a first yoke 4, a pair of drive
magnets 5, 6 disposed in an axial direction "L" so as to sandwich
the first yoke 4, and a second yoke 7.
[0028] The first yoke 4 and the pair of drive magnets 5, 6 are
respectively formed in a disk-like shape with the same diameter.
Each of the drive magnets 5, 6 is a permanent magnet which is
magnetized in a thickness direction such that one of its faces is
magnetized at an N-pole and the other at an S-pole. The respective
drive magnets 5, 6 are disposed such that their same polarities
(N-pole in this embodiment) are directed to the first yoke 4.
[0029] The second yoke 7 includes a pair of yoke members 71, 72
shaped in a bottomed cylinder which are capable of being divided in
the axial direction "L". The yoke members 71, 72 are disposed in
the state where respective annular end faces 71a, 72a of respective
cylindrical body parts 711, 721 of the yoke members 71, 72 are
butted with each other. In this state, the cylindrical body parts
711, 721 of the second yoke 7 are disposed so as to face the outer
peripheral end face 40 of the first yoke 4 and the outer peripheral
end faces of the pair of drive magnets 5, 6. The bottom plate
portions 712, 722 of the second yoke 7 are overlapped on the
respective end faces 51, 61 which are located on the outer side of
the drive magnets 5, 6 in the axial direction "L".
[0030] Further, annular protruding parts 715, 725 which are
protruded toward the outer peripheral end face 40 of the first yoke
4 are formed near the butting portion of the yoke members 71, 72 of
the second yoke 7. Therefore, as shown in FIG. 1(b), the magnetic
flux which is to be guided to the first yoke 4 from the pair of
drive magnets 5, 6 can be efficiently guided to the protruding
parts 715, 725 of the second yoke 7 and the magnetic flux is
radially radiated from the outer peripheral end face 40 of the
first yoke 4 in the direction perpendicular to the axial direction
"L". The magnetic flux guided to the protruding parts 715, 725
forms a loop where the flux is guided to the cylindrical body part
711, 721 through the bottom plate portions 712, 722 and reaches the
S-poles of the magnets 5, 6.
[0031] The movable body 2 is provided with the coil 8 which is
disposed to surround around the outer peripheral end face 40 of the
first yoke 4 between the first yoke 4 and the protruding parts 715,
725 of the second yoke 7. The coil 8 is wound around a coil bobbin
9 which is made of an electrically insulative resin and formed in a
U-shape in cross-section. The coil 8 is supported by an elastic
support member or the like (not shown).
[0032] In the actuator 1 as structured above, the movable body 2 is
located at a stand-by position shown in FIGS. 1(a) and 1(b) when
the coil 8 is not energized. In this state as shown in Fig. 1(b),
when an electric current directed up from the paper surface is
applied to the coil 8, the movable body 2 is displaced or moved in
the direction shown by the arrow "F1". On the other hand, when an
electric current directed down into the paper surface is applied to
the coil 8, the movable body 2 is displaced or moved in the
direction shown by the arrow "F2". Therefore, when an alternating
current is applied to the coil 8, the movable body 2 is alternately
displaced or moved in the direction shown by the arrow "F1" and in
the direction shown by the arrow "F2". Consequently, the movement
of the movable body 2 can be utilized in the driving of various
types of members.
[0033] As described above, in the fixed body 3 of the actuator 1 in
accordance with an embodiment of the present invention, a pair of
the drive magnets 5, 6 are superposed in the axial direction "L"
such that the respective N-poles of the drive magnets 5, 6 face the
first yoke 4. Further, the second yoke 7 is disposed so as to face
the outer peripheral end face 40 of the first yoke 4. Therefore,
the magnetic flux from the pair of the drive magnets 5, 6 can be
efficiently guided to the direction perpendicular to the axial
direction "L" from the outer peripheral end face 40 of the first
yoke 4. Accordingly, the density of the magnetic flux is high,
which interlinks with the coil 8 disposed so as to surround the
outer peripheral end face 40 of the first yoke 4, and thus a large
thrust can be acted on the movable body 2.
[0034] The first yoke 4 is sandwiched between common poles of the
drive magnets 5, 6. Therefore, the drive magnets 5, 6 are not
attracted to each other simplifying the assembly operation.
[0035] In addition, since the drive magnets 5, 6 are disposed in
the fixed body 3, the moving range of the drive magnets 5, 6 is not
required to be considered which is different from the case in which
the drive magnets 5, 6 are disposed in the movable body.
Accordingly, even when the drive magnets 5, 6 are disposed close to
peripheral members, the movement of the movable body is not
disturbed because the drive magnets 5, 6 are not magnetically
attracted by the peripheral members. In addition, even when a
shield is applied to the magnetic field such that the peripheral
members are not attracted by the drive magnet 5, 6, or such that
malfunction is not induced in peripheral devices, the drive magnets
5, 6 can be compactly covered because the drive magnets 5, 6 are
fixed. In addition, in an embodiment of the present invention,
since the second yoke 7 is disposed to cover the drive magnets 5, 6
and the coil 8, the shield is efficiently performed by the second
yoke 7. Accordingly, since another shield member is not required,
the outer dimension of the actuator 1 can be made small. As a
result, the actuator 1 in the embodiment of the present invention
is suitable for mounting on a small-sized device such as a lens
drive device, which is mounted on a portable telephone with a
camera, and a pump device described later.
Embodiment of Pump Device
[0036] The actuator 1 described with reference to FIGS. 1(a) and
1(b) can be used in a pump device that is constructed so that the
reciprocating movement of the movable body 2 performs a pumping
operation FIG. 2 is a plan view showing a pump device to which the
present invention is applied. FIG. 3(a) is a cross-sectional view
showing the pump device that is cut by the line of "3-3A-A" in FIG.
2 and FIG. 3(b) is a cross-sectional view showing the pump device
that is cut by the line of "B-B" in FIG. 2. FIG. 4 is an exploded
perspective view showing the pump device shown in FIGS. 2 and FIGS.
3(a) and 3(b). Respective component members shown in FIG. 4 are
vertically symmetrically disposed with the movable body as a center
and the respective corresponding component parts structured in a
vertically symmetrical manner.
[0037] As shown in FIG. 2, FIGS. 3(a) and 3(b) and FIG. 4, a pump
device 10 in accordance with an embodiment of the present invention
is provided with an electromagnetic actuator on the inside of a
sealing case 50. The structure of the actuator is basically the
same as that of the above-mentioned actuator 1 and thus the same
notational symbol is used for the corresponding structural
element
[0038] In the pump device 10 in accordance with the embodiment of
the present invention, the movable body 2 is disposed in the space
formed by the second yoke 7 such that a first pump chamber 11 is
formed on one side of the movable body 2 in the axial direction "L"
and a second pump chamber 12 is formed on the other side of the
movable body 2 in the axial direction "L". In this embodiment, the
movable body 2 is used as a piston which is reciprocated in the
axial direction "L".
[0039] More concretely, the fixed body 3 includes two plates of the
first yoke 4, a pair of drive magnets 5, 6 overlapped so as to
interpose the first yoke 4 therebetween, and the second yoke 7. The
two plates of the first yoke 4 are superposed in the axial
direction "L" and formed with the same diameter as that of the
drive magnets 5, 6. Each of the drive magnets 5, 6 is a permanent
magnet that is magnetized in a thickness direction such that one of
its faces is magnetized at an N-pole and the other at an S-pole.
The respective drive magnets 5, 6 are disposed such that their same
polarities (N-pole in this embodiment) are directed to the first
yoke 4.
[0040] In this embodiment of the present invention, the second yoke
7 includes a pair of yoke members 15, 16 shaped in a bottomed
cylinder and a pair of ring-shaped yoke members 17, 18. In the
state that these yoke members are superposed each other, the bottom
plate portions 712, 722 of the yoke members 15, 16 are overlapped
on the respective end faces 51, 61 of the drive magnets 5, 6 in the
axial direction "L". The inner peripheral edge portions of the
ring-shaped yoke members 17, 18 are protruded in the inside of the
space that is formed by the second yoke 7. Annular protruding parts
715, 725 protruded toward the outer peripheral end face 40 of the
first yoke 4 are formed by the inner peripheral edge portions of
the ring-shaped yoke members 17, 18. Flange portions are formed in
the yoke members 15, 16 at the butting portions with the yoke
members 17, 18. Sealing is applied between the flange portions of
the yoke members 15, 16 and the outer peripheral edge portions of
the yoke members 17, 18. The inner peripheral edge portions of the
sealing members 19, 20 are pinched between the yoke members 17,
18.
[0041] The movable body 2 is provided with the coil 8 which is
disposed to surround around the outer peripheral end face 40 of the
first yoke 4 between the first yoke 4 and the second yoke 7. The
coil 8 is wound around a coil bobbin 9 which is made of an
electrically insulative resin and formed in a U-shape in
cross-section. Ring-shaped guide members 22, 23 are disposed within
the space which is formed by the second yoke 7 for performing the
guide operation at the time of the movement of the movable body 2.
The movable body 2 can be moved in the axial direction "L" while
sliding on the inner peripheral face of the guide members 22, 23,
the outer peripheral end face 40 of the first yoke 4, and the outer
peripheral end faces of a pair of the drive magnets 5, 6.
Therefore, the movable body 2 serves as a piston of the first pump
chamber 11 and the second pump chamber 12.
[0042] A small projecting part 91 in a pillar shape is formed on
each of the end faces of the coil bobbin 9 and small holes 221, 231
are formed in the guide members 22, 23 into which the small
projecting parts 91 in the pillar shape are slidably fitted. The
small projecting parts 91 are sidably guided by the small holes
221, 231. Therefore, the movable body 2 does not incline because
the small pillar shaped projecting parts 91 are fitted into and
guided by the small holes 221, 231 when the movable body 2 is moved
in the axial direction "L". Further, thin plate-like projecting
parts 92 are protruded from the respective outer peripheral edge
portions of both the end faces of the coil bobbin 9. On the other
hand, grooves 222, 232 to which the plate-like projecting parts 92
are fitted are formed in the guide members 22, 23. Therefore, since
the projecting parts 92 of the coil bobbin 9 are guided by the
grooves 222, 232 of the guide members 22, 23, the movable body 2
does not move around the axial direction "L". Further, the
plate-like projecting parts 92 of the coil bobbin 9 are guided by
the inner peripheral faces of the guide members 22, 23, and thus
the movable body 2 does not incline. In addition, thin plate-like
projecting parts 93 are protruded from the inner peripheral edge
portions of both the end faces of the coil bobbin 9 and the
plate-like projecting parts 93 slide on the outer peripheral end
face 40 of the first yoke 4 and on the outer peripheral end faces
of a pair of the drive magnets 5, 6. Therefore, the movable body 2
does not incline.
[0043] The actuator 1 is housed in the sealing case 50 and a common
fluid inlet port 28 and a common fluid outlet port 29 are formed in
the sealing case 50, which are in communication with both the first
pump chamber 11 and the second pump chamber 12. The sealing case 50
includes rectangular and tubular main case bodies 58, 59, which are
formed with circular aperture parts 58a, 59a for accommodating the
actuator 1 and rectangular case covers 53, 54 for closing the
circular aperture parts 58a, 59a of the main case bodies 58, 59
from the outside. A discharge pipe 31 in communication with the
common fluid outlet port 29 is connected with the main case body 58
and a suction pipe 30 in communication with the common fluid inlet
port 28 is connected with the main case body 59. The case covers
53, 54 are fixed to the main case bodies 58, 59 with screws 55 or
the like. When the sealing case 50 is assembled, the outer
peripheral edge portions of the sealing members 19, 20 are pinched
by the main case bodies 58, 59.
[0044] In the state when the pump device is disassembled, in other
words, the assembling is on the way as shown in FIG. 4, the common
fluid inlet port 28 and the common fluid outlet port 29 are exposed
to the outside, and thus the valves 111, 121 for suction and the
valves 112, 122 for discharge can be mounted. The valve 111 for
suction prevents fluid from flowing backward from the first pump
chamber 11 to the suction pipe 30. The valve 112 for suction
prevents the fluid from flowing backward from the second pump
chamber 12 to the suction pipe 30. The valve 112 for discharge
prevents the fluid from flowing backward from the discharge pipe 31
to the first pump chamber 11. The valve 122 for discharge prevents
the fluid from flowing backward from the discharge pipe 31 to the
second pump chamber 12.
[0045] In the actuator 1 for the pump device 10 structure described
above, when an alternating current is applied to the coil 8, the
movable body 2 is alternately moved with a stroke length of about 1
mm in the direction shown by the arrow "F1" and the direction shown
by the arrow "F2". At this time, when the movable body 2 moves to
the upper side as shown by the arrow "F1" in FIG. 1(b), the fluid
is sent out from the first pump chamber 11 through the common fluid
outlet port 29 and the discharge pipe 31. On the other hand, the
fluid is introduced into the second pump chamber 12 through the
suction pipe 30 and the common fluid inlet port 28. On the
contrary, when the movable body 2 moves to the under side as shown
by the arrow "F2", the fluid is introduced into the first pump
chamber 11 through the suction pipe 30 and the common fluid inlet
port 28, and the fluid is sent out from the second pump chamber 12
through the common fluid outlet port 29 and the discharge pipe
31.
[0046] As described above, the pump device 10 in accordance with
this embodiment of the present invention includes the actuator 1
provided with the fixed body 3 in which a pair of the drive magnets
5, 6 are overlapped on the first yoke 4 in the axial direction "L"
with the N-poles of the drive magnets 5, 6 directing to the first
yoke 4. In this actuator 1, the second yoke 7 is disposed so as to
face the outer peripheral end face 40 of the first yoke 4.
Moreover, the second yoke 7 is provided with the protruding parts
715, 725 that are protruded toward the outer peripheral end faces
40 of the first yoke 4. Therefore, the magnetic flux from the pair
of the drive magnets 5, 6 can be effectively guided from the outer
peripheral end face 40 of the first yoke 4 to the direction
perpendicular to the axial direction "L". Accordingly, since the
density of the magnetic flux is high which interlinks with the coil
8 disposed so as to surround around the outer peripheral end face
40 of the first yoke 4, a large thrust can be acted on the movable
body 2. As a result, the movable body 2 can effectively perform as
a piston the suction of fluid to the first pump chamber 11 and the
second pump chamber 12 and the discharge of the fluid from the pump
chambers 11, 12.
[0047] In addition, since the coil 8 is constructed as the movable
body 2, the weight of the movable body 2 can be reduced. Therefore,
when the movable body 2 is used as a piston, a large thrust is
capable of acting on the movable body 2. Further, since the movable
body 2 can be light-weight, the pump device 10 in accordance with
the embodiment of the present invention can feed liquid as well as
gas.
[0048] The first pump chamber 11 and the second pump chamber 12 are
in communication with the common fluid inlet port 28 and in
communication with the common fluid outlet port 29. Therefore,
fluid can be alternately sent out from the first pump chamber 11
and the second pump chamber 12. Accordingly, the Flow rate can be
large in comparison with the size of the pump device 10 and the
occurrence of pulsating flow can be restrained.
[0049] In this embodiment of the present invention, two drive
magnets 5, 6 are disposed such that the same polarities are
directed to each other. However, since two plates of the first yoke
4 are sandwiched between the drive magnets 5, 6, assembly against
the repulsive forces of the drive magnets 5, 6 is simplified.
[0050] In addition, since the drive magnets 5, 6 are disposed in
the fixed body 3, the drive magnets 5, 6 are not attracted to
peripheral magnetic members even when the drive magnets 5, 6 and
the peripheral members are positioned in a close relation.
Moreover, even when a shield is applied to the magnetic field such
that the peripheral members are not attracted to the drive magnets
5, 6 or such that malfunctions are not induced in the peripheral
devices, the periphery of the drive magnets 5, 6 can be covered in
a compact manner because the drive magnets 5, 6 are fixed.
[0051] In addition, since the second yoke 7 is disposed so as to
cover the drive magnets 5, 6 and the coil 8, a shield is
efficiently executed by the second yoke 7. Therefore, since another
shield member is not required, the outer dimension of the actuator
1 can be made smaller. As a result, the pump device 10 in this
embodiment of the present invention can be made thinner to the
extent of the thickness of 10 mm or less, and thus the pump device
10 can be used as a cooling pump for a CPU and the like in a
notebook type personal computer.
Another Embodiment of Pump Device
[0052] FIGS. 5(a) through 5(c) are cross-sectional views showing
another pump device in accordance with an embodiment of the present
invention FIG. 5(a) is a cross-sectional view showing the pump
device that is cut at a position corresponding to the line of "A-A"
in FIG. 2, FIG. 5(b) is a cross-sectional view showing the pump
device which is cut at a position corresponding to the line of
"B-B" in FIG. 2, and FIG. 5(c) is an enlarged view showing a
portion of the pump device encircled by the line "C" in FIG. 5(a).
The structure of the pump device in this embodiment is basically
the same as that of the above-mentioned pump device 10 and thus the
same notational symbol is used for the corresponding structural
element.
[0053] In the pump device 10 of this embodiment shown in FIGS. 5(a)
through 5(c), similarly to the pump device described with reference
to FIG. 2, FIGS. 3(a) and 3(b) and FIG. 4, the actuator 1 described
with reference to FIGS. 1(a) and 1(b) is provided on the inside of
the sealing case 50. In other words, in the actuator 1, the fixed
body 3 includes two plates of the first yoke 4, a pair of the drive
magnets 5, 6 overlapped so as to interpose the first yoke 4
therebetween, and the second yoke 7. The respective drive magnets
5, 6 are disposed such that their same polarities are directed to
the first yoke 4. The second yoke 7 is superposed on the respective
end faces 51, 61 of the drive magnets 5, 6 positioned on the outer
side in the axial direction "L". The second yoke 7 is provided with
ring-shaped protruding parts 715, 725 which are protruded to the
outer peripheral end face 40 of the first yoke 4.
[0054] The movable body 2 is provided with the coil 8 which is
disposed to surround around the outer peripheral end face of the
first yoke 4 between the first yoke 4 and the ring-shaped plate
members 17, 18 of the second yoke 7.
[0055] In this embodiment the movable body 2 is supported in the
state that the coil 8 is wrapped with two sheet-shaped elastic
members 60 from both sides in the axial direction "L". The two
overlapped inner peripheral edge parts of the elastic members 60
are held between the two plates of the first yoke 4 and the two
overlapped outer peripheral edge parts are held between the
protruding parts 715, 725. Therefore, the first pump chamber 11 is
formed by the movable body 2 on one side of the movable body 2 in
the axial direction "L" in the space which is formed by the second
yoke 7, and the second pump chamber 12 is formed in the other side
of the movable body 2 in the axial direction "L". In other words,
the movable body 2 serves as a diaphragm for the first pump chamber
11 and the second pump chamber 12. The elastic member 60 may be
formed of a film-like member basically made of rubber and fiber, or
a film-like member that is formed of resin in a film-like
shape.
[0056] Annular recessed parts 401, 750 in a rectangular cross
section are resctively formed on the outer peripheral end faces 40
of two plates of yokes 4 and the inner peripheral end faces of the
protruding parts 715, 725 to accommodate elastic deforming parts
601, 602 which permit the elastic member 60 to elastically deform
in the axial direction "L".
[0057] Also in this embodiment of the present invention, the first
pump chamber 11 and the second pump chamber 12 are connected to the
discharge pipe 31 through the common fluid outlet port 29 and
connected to the suction pipe 30 through the common fluid inlet
port 28. Further, the valves 112, 122 for discharge are disposed
between the first pump chamber 11 and the common fluid outlet port
29, and the valves 111, 121 for suction are disposed between the
second pump chamber 12 and the common fluid inlet port 28.
[0058] The pump device 10 structured as described above includes
the actuator 1 provided with the fixed body 3 in which a pair of
the drive magnets 5, 6 are overlapped on the first yoke 4 in the
axial direction "L" with the N-poles of the drive magnets 5, 6
directing to the first yoke 4 similarly to the pump device
described with reference to FIG. 2, FIGS. 3(a) and 3(b) and FIG. 4.
In this actuator 1, the second yoke 7 is disposed so as to face the
outer peripheral end face 40 of the first yoke 4. Moreover, the
second yoke 7 is provided with the protruding parts 715, 725 which
are protruded toward the outer peripheral end faces 40 of the first
yoke 4. Therefore, the magnetic flux from the pair of the drive
magnets 5, 6 can be effectively guided from the outer peripheral
end face 40 of the first yoke 4 to the direction perpendicular to
the axial line direction "L". Accordingly, since the density of the
magnetic flux is high which interlinks with the coil 8 disposed so
as to surround the outer peripheral end face 40 of the first yoke
4, a large thrust can be acted on the movable body 2. As a result,
the movable body 2 can effectively perform as a diaphragm the
suction of fluid to the first pump chamber 11 and the second pump
chamber 12 and the discharge of the fluid from the pump chambers
11, 12, and thus has similar effects as the pump device described
with reference to FIG. 2, FIGS. 3(a) and 3(b) and FIG. 4 can be
obtained.
Other Embodiments
[0059] In the embodiments of the present invention, the first pump
chamber 11 and the second pump chamber 12 are connected to the
common fluid outlet port 29 and the common fluid inlet port 28.
However, when the pump device is provided with a first fluid inlet
port which is in communication with the first pump chamber 11, a
second fluid inlet port which is in communication with the second
pump chamber 12, a first fluid outlet port which is in
communication with the first pump chamber 11, and a second fluid
outlet port which is in communication with the second pump chamber
12, different fluids can be respectively sent out from the first
pump chamber 11 and the second pump chamber 12 by using only one
pump device. Therefore, for example, the feeding of water and
alcohol can be performed by using one pump device in a fuel cell
system.
[0060] When the number of turns of the coil 8 is small, a flexible
printed circuit board (FPC) may be used as the movable body 2
instead of the coil 8.
[0061] While the description above refers to particular embodiments
of the present invention, it will be understood that many
modifications may be made without departing from the spirit
thereof. The accompanying claims are intended to cover such
modifications as would fall within the true scope and spirit of the
present invention.
[0062] The presently disclosed embodiments are therefore to be
considered in all respects as illustrative and not restrictive, the
scope of the invention being indicated by the appended claims,
rather than the foregoing description, and all changes which come
within the meaning and range of equivalency of the claims are
therefore intended to be embraced therein.
* * * * *