U.S. patent application number 11/511683 was filed with the patent office on 2007-03-22 for diaphragm pump.
This patent application is currently assigned to ALPS ELECTRIC CO., LTD.. Invention is credited to Jiro Nakajima, Hitoshi Onishi.
Application Number | 20070065309 11/511683 |
Document ID | / |
Family ID | 37884348 |
Filed Date | 2007-03-22 |
United States Patent
Application |
20070065309 |
Kind Code |
A1 |
Nakajima; Jiro ; et
al. |
March 22, 2007 |
Diaphragm pump
Abstract
A diaphragm pump is provided. The diaphragm pump comprises an
upper and lower housing, a pump chamber plate, a pair of pump
chambers, and a diaphragm that separates the pair of pump chambers.
First and second suction-side check valves are disposed between the
pair of pump chambers and a suction port. First and second
discharge-side check valves are disposed between the pair of pump
chambers and a discharge port. The lower housing comprises a first
pump chamber concave portion. The pump chamber plate comprises a
second pump chamber concave portion, the second suction-side check
valve, and the second discharge-side check valve. An interplate
suction-side channel and an interplate discharge-side channel are
provided between the upper housing and the pump chamber plate.
Inventors: |
Nakajima; Jiro;
(Niigata-ken, JP) ; Onishi; Hitoshi; (Niigata-ken,
JP) |
Correspondence
Address: |
BRINKS HOFER GILSON & LIONE
P.O. BOX 10395
CHICAGO
IL
60610
US
|
Assignee: |
ALPS ELECTRIC CO., LTD.
|
Family ID: |
37884348 |
Appl. No.: |
11/511683 |
Filed: |
August 28, 2006 |
Current U.S.
Class: |
417/413.1 |
Current CPC
Class: |
F04B 43/046 20130101;
F04B 43/023 20130101 |
Class at
Publication: |
417/413.1 |
International
Class: |
F04B 17/00 20060101
F04B017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 6, 2005 |
JP |
2005-257376 |
Claims
1. A diaphragm pump comprising: an upper and lower housing; a pump
chamber plate; a pair of pump chambers; a diaphragm that separates
the pair of pump chambers; first and second suction-side check
valves between the pair of pump chambers and a suction port; and
first and second discharge-side check valves between the pair of
pump chambers and a discharge port, wherein the lower housing
comprises a first pump chamber concave portion, wherein the pump
chamber plate comprises a second pump chamber concave portion, the
second suction-side check valve, and the second discharge-side
check valve, and wherein an interplate suction-side channel and an
interplate discharge-side channel are provided between the upper
housing and the pump chamber plate.
2. The diaphragm pump according to claim 1, wherein the suction
port includes the first suction-side check valve in communication
with the first pump chamber forming concave portion, and the
discharge port includes the first discharge-side check valve in
communication with the first pump chamber forming concave
portion.
3. The diaphragm pump according to claim 2, wherein the interplate
suction-side channel is bifurcated from the suction port of the
lower housing and connected to the second suction-side check valve
and the interplate discharge-side channel is bifurcated from the
discharge port of the lower housing and connected to the second
discharge-side check valve.
4. The diaphragm pump according to claim 3, wherein the interplate
suction-side channel and the interplate discharge-side channel are
sealed with a seal ring inserted between the pump chamber plate and
the upper housing.
5. The diaphragm pump according to claim 4, wherein one end of the
interplate suction-side channel and one end of the interplate
discharge-side channel communicate with the second suction-side
check valve and the second discharge-side check valve, and the
other ends of the interplate suction-side channel and the
interplate discharge-side channel communicate with the channels
bifurcated from the suction and discharge ports that open to the
lower housing.
6. The diaphragm pump according to claim 4, wherein the seal ring
has an oval shape.
7. The diaphragm pump according to claim 1, wherein the first
suction-side check valve and the first discharge-side check valve
are formed as a first suction-side check valve unit and a first
discharge-side check valve unit that are separate from the lower
housing, and the first suction-side check valve unit and the first
discharge-side check valve unit are attached to pump chamber-side
opening ends of the suction and discharge ports.
8. The diaphragm pump according to claim 7, wherein the first
suction-side check valve unit and the first discharge-side check
valve unit are provided on the same substrate.
9. The diaphragm pump according to claim 1, wherein the suction and
discharge ports of the lower housing are protruded in parallel with
each other in the plane direction of the diaphragm in a free
state.
10. The diaphragm pump according to claim 1, wherein the check
valve has an umbrella shape.
11. The diaphragm pump according to claim 1, wherein the diaphragm
is a piezoelectric oscillator or an electrostriction
oscillator.
12. The diaphragm pump according to claim 1, wherein the diaphragm
is a bimorph type piezoelectric oscillator.
Description
[0001] This application claims the benefit of Japanese Patent App.
No. 2005-257376 filed Sep. 6, 2005, which is hereby incorporated by
reference.
BACKGROUND
[0002] 1. Field A diaphragm pump is provided.
[0003] 2. Related Art
[0004] Generally, a diaphragm pump is constructed with pump
chambers (variable volume chamber) that are defined by a diaphragm
and a pair of check valves having different flow directions that
are provided in a pair of channels connected to the pump chamber (a
suction-side check valve allowing a flow toward the pump chamber
and a discharge-side check valve allowing a flow from the pump
chamber are provided in the two channels). To operate the pump, the
suction-side check valve opens at a stroke for increasing the
volume of the pump chamber by oscillating the diaphragm and the
discharge-side check valve opens at a stroke for decreasing the
volume of the pump chamber. The diaphragm is made of an elastic
(oscillatable) material, for example, a rubber, or a piezoelectric
oscillator.
[0005] An example of the conventional diaphragm pump is disclosed
in Japanese Unexamined Patent Application Publication No.
2001-193656. As described above, the operation of a diaphragm pump
is accompanied by pulsation at the discharge port caused by
repeating the opening of the suction-side check valve at a stroke
that increases the volume of the pump chamber and the opening of
the discharge-side check valve at a stroke that decreases the
volume of the pump chamber.
[0006] A diaphragm pump with a pulsation period at the discharge
port is reduced to a half of the pulsation period at the discharge
port of the conventional diaphragm pump is disclosed in Japanese
Unexamined Patent Application Publication No. 2005-337068. In the
diaphragm pump, pump chambers are formed above and under the
diaphragm. A single suction port and a single discharge port are
installed. First and second suction-side check valves allow fluid
to flow from a suction port toward the pair of pump chambers and do
not allow fluid to flow in the reverse directions are provided
between the pair of pump chambers and the suction port. First and
second discharge-side check valves allow fluid to flow from the
pair of pump chambers toward the discharge port and does not allow
fluid to flow in the reverse directions are provided between the
pair of pump chambers and the discharge port (four-valve diaphragm
pump).
[0007] In addition, a pump structure that enables a slim sized
four-valve diaphragm pump is disclosed in Japanese Unexamined
Patent Application Publication No. 2005-337068. Umbrellas are
attached in the suction and discharge ports formed in the upper and
lower housings, respectively, and separate covers are adhered
thereto for forming channels. For example, the covers may be
adhered by using a highly reliable laser welding. However, over the
lifetime of the pump a leak may be caused in a pump by
deterioration. It is difficult to obtain perfect reliability.
SUMMARY
[0008] In a preferred embodiment, a diaphragm pump includes a pair
of pump chambers that are formed by an oscillatable diaphragm above
and under the diaphragm. First and second suction-side check valves
allow fluid to flow from a suction port toward the pair of pump
chambers and do not allow fluid to flow in the reverse directions
are provided between the pair of pump chambers and the suction
port. First and second discharge-side check valves that allow fluid
to flow from the pair of pump chambers toward a discharge port and
do not allow fluid to flow in the reverse directions are provided
between the pair of pump chambers and the discharge port. The
diaphragm pump comprises an upper housing, a pump chamber plate, a
diaphragm, and a lower housing, in a sequentially stacked form. The
lower housing comprises a first pump chamber that including a
concave portion that forms one pump chamber and faces the
diaphragm. The suction port includes the first suction-side check
valve communicating with the pump chamber forming the concave
portion. The discharge port includes the first discharge-side check
valve that communicates with the pump chamber concave portion. The
pump chamber plate includes a second pump chamber concave portion
that forms the other pump chamber and faces the diaphragm, the
second suction-side check valve, and the second discharge-side
check valve are provided. An interplate suction-side channel that
is bifurcated from the second suction-side check valve and
connected to the second suction-side check valve and an interplate
discharge-side channel that is bifurcated from the second
discharge-side check valve and connected to the second
discharge-side check valve are provided between the upper housing
and the pump chamber plate.
[0009] It is desirable that the interplate suction-side channel and
the interplate discharge-side channel are sealed by a seal ring
inserted between the pump chamber plate and the upper housing.
[0010] It is desirable that one end of the interplate suction-side
channel and the interplate discharge-side channel communicate with
the second suction-side check valve and the second discharge-side
check valve, and the other end of the interplate suction-side
channel and the discharge-side channel communicate with the
channels bifurcated from the suction and discharge ports that open
to the lower housing.
[0011] When the seal ring has an oval shape, it is easy to form the
channel.
[0012] It is desirable the first suction-side check valve and the
first discharge-side check valve that are provided in the lower
housing are formed as a first suction-side check valve unit and a
first discharge-side check valve unit that are separate from the
lower housing. The first suction-side check valve unit and the
first discharge-side check valve unit are attached to pump
chamber-side opening ends of the suction and discharge ports. In an
alternate embodiment, the first suction-side check valve unit and
the first discharge-side check valve unit are provided on the same
substrate.
[0013] When the suction and discharge ports of the lower housing
protrude in parallel with each other in the plane direction of the
diaphragm in a free state, it is desirable to obtain a slim
diaphragm pump.
[0014] According to any embodiments of the present invention, it is
desirable that the check valve has an umbrella shape. In addition,
it is preferred that the diaphragm is a piezoelectric oscillator or
an electrostriction oscillator. Specifically, it is desirable that
the diaphragm is a bimorph type piezoelectric oscillator.
BRIEF DESCRIPTION OF THE DRAWING
[0015] FIG. 1 is an exploded perspective view of an exemplary
diaphragm pump according to a preferred embodiment.
[0016] FIG. 2 is an exploded cross sectional view of the diaphragm
pump shown FIG. 1.
[0017] FIG. 3 is a top plan view of an exemplary lower housing.
[0018] FIG. 4 is a cross sectional view taken along the line IV-IV
of FIG. 3.
[0019] FIG. 5 is a cross sectional view taken along the line V-V of
FIG. 3.
[0020] FIG. 6 is a top plan view of an exemplary pump chamber plate
side of an upper housing.
[0021] FIG. 7 is a top plan view of an exemplary pump chamber that
forms a concave portion of a pump chamber plate.
[0022] FIG. 8 is an exploded perspective view of an exemplary
bimorph type piezoelectric oscillator.
[0023] FIG. 9 is a perspective view that illustrates an exemplary
relation between the bimorph type piezoelectric oscillator and a
deformed D shape seal ring.
[0024] FIG. 10 is a top plan view of the same substantial part of
FIG. 9.
[0025] FIG. 11 is a conceptual view of an exemplary four-valve
diaphragm pump according to a preferred embodiment.
DESCRIPTION OF THE PREFERED EMBODIMENTS
[0026] The operating mechanism of a four-valve diaphragm pump will
be described with reference to FIG. 11. The diaphragm pump includes
an upper housing 10, a lower housing 20, a piezoelectric oscillator
(diaphragm) 30, and four umbrellas (check valves) 11, 12, 21, and
22. A pump chamber (variable volume chamber) 13 is located between
the upper housing 10 and the piezoelectric oscillator 30. A pump
chamber (variable volume chamber) 23 is located between the low
housing 20 and the piezoelectric oscillator 30.
[0027] A single port 31 communicates with the suction-side channels
14H and 24H. The suction-side channel 14H communicates with the
pump chamber 13 through the suction-side umbrella 11. The
suction-side channel 24H communicates with the pump chamber 23
through the suction-side umbrella 22. In addition, a single
discharge port 32 communicates with discharge-side channels 15D and
25D. The discharge-side channel 15D communicates with the pump
chamber 13 through a discharge-side umbrella 12. The discharge-side
channel 25D communicates with the pump chamber 23 through a
discharge-side umbrella 22.
[0028] In the four-valve diaphragm pump, when the piezoelectric
oscillator 30 is elastically deformed (oscillates) in the forward
and backward directions, a volume of one pump chamber 13 or 23
increases and a volume of the other pump chamber 23 or 13
decreases. A stroke for increasing the volume of the pump chamber
13 is a stroke for decreasing the volume of the pump chamber 23.
When the volume of the pump chamber 13 increases, the suction-side
umbrella (suction-side check valve) 11 opens to introduce a fluid
into the pump chamber 13 from the pump port 31, and since the
volume of the pump chamber 23 decreases, a fluid in the pump
chamber 23 opens the discharge-side umbrella (discharge-side check
valve) 22 to discharge the fluid to the discharge port 32.
[0029] A stroke that decreases the volume of the pump chamber 13 is
a stroke that increases the volume of the pump chamber 23. Since
the volume of the pump chamber 23 increases, the suction-side
umbrella (suction-side check valve) 21 opens to introduce a fluid
into the pump chamber 23 from the suction port 31, and since the
volume of the pump chamber 13 decreases, a fluid in the pump
chamber 13 opens the discharge-side umbrella (discharge-side check
valve) 12 to discharge the fluid to the discharge port 32.
Accordingly, the pulsation period at the discharge port 32 can be
shortened (the pulsation period is a half of the period in the case
where the pump chamber is formed on only one side that is an upper
or lower side of the piezoelectric oscillator 30).
[0030] According to a preferred embodiment, the four-valve
diaphragm pump that operates according to the aforementioned
mechanism is embodied as a structure that prevents a leak. An
embodiment of the four-valve diaphragm pump will be described with
reference to FIGS. 1 to 7.
[0031] The diaphragm pump includes the upper housing 10, the lower
housing 20, the piezoelectric oscillator 30, and a pump chamber
plate 40 attached between the upper housing 10 and the
piezoelectric oscillator 30 and has an entirely flattened
rectangular shape. The upper housing 10, the lower housing 20, and
the pump chamber plate 40 include moldings of resin materials.
[0032] The lower housing 20 is the largest molding of the
aforementioned moldings. The lower housing 20 is a complex
flattened rectangular shape. In the lower housing 20, an opened
pump chamber forming concave portion 20a is formed in the opposing
surface of the piezoelectric oscillator 30. The suction port 31 and
the discharge port 32 are protruded in parallel with each other and
integrated with one of the four side faces of the lower housing 20
(refer to FIGS. 1 to 5). In the lower housing 20, the suction-side
channel 24H that communicates with the suction port 31 and the
discharge-side channel 25D that communicate with the discharge port
32 are formed. Channel expanding portions 24Ha and 25Da
communicating with the pump chamber forming concave portion 20a are
formed at the inner ends of the suction-side and discharge-side
channels 24H and 25D. Valve retainer concave portions 24Hb and 25Db
are formed at ends of the channel expanding portions 24Ha and 25Da
close to the pump chamber forming concave portion 20a.
[0033] A suction-side umbrella unit (suction-side check valve unit)
21U and a discharge-side umbrella unit (discharge-side check valve
unit) 22U are adhered and fixed to the valve retainer concave
portions 24Hb and 25Db. The suction-side umbrella unit 21U and the
discharge-side umbrella unit 22U are the same in the structure,
except the attachment direction. An umbrella attaching hole 21c
(umbrella attaching hole 22c) is formed on the center portion of
the unit plate 21a (unit plate 22a) of which circumference is used
as an adhesion portion 21b (adhesion portion 22b) with the valve
retainer concave portion 24Hb (valve retainer concave portion
25Db). A plurality of channel holes 21d (channel holes 22d) are
formed on the circumference of the umbrella attaching hole 21c
(umbrella attaching hole 22c). An umbrella portion 21g (umbrella
portion 22g) of an umbrella 21f (umbrella 22f) in which a central
axis 21e (central axis 22e) is inserted into the umbrella attaching
hole 21c (umbrella attaching hole 22c) covers the channel holes 21d
(channel holes 22d).
[0034] When pressure greater than a predetermined value is applied
to the umbrella portion 21g (umbrella portion 22g) from the channel
hole 21d (channel hole 22d), the umbrella portion 21g (umbrella
portion 22g) is elastically deformed to open the channel holes 21d
(channel holes 22d). The adhesion portion 21b of the suction-side
umbrella unit 21U is adhered to the valve retainer concave portion
24Hb. Conversely, the adhesion portion 22b of the discharge-side
umbrella unit 22U is adhered to the valve retainer concave portion
25Db. The suction-side umbrella unit 21U allows a flow from the
suction port 31 toward the pump chamber forming concave channel
portion 20a (pump chamber 23) and does not allow a reverse flow.
The discharge-side umbrella unit 22U allows a flow from the pump
chamber forming concave portion 20a (pump chamber 23) toward the
discharge port 32 and does not allow a reverse flow. The unit
plates 21a and 22a of the umbrella units 21U and 22U of the suction
and discharge sides may be formed of one substrate.
[0035] An additional cover is not needed for the aforementioned
lower housing 20. In a body of the lower housing 20, the closed
suction-side channel 24H is formed between the suction port 31 and
the pump chamber forming concave portion 20a, and the closed
discharge-side channel 25D is formed between the discharge port 32
and the pump chamber forming concave portion 20a. In the lower
housing 20, a seal ring groove 20b is also formed at the
circumference of the pump chamber forming concave portion 20a. The
seal ring groove 20b has a deformed D shape that includes a large
circular portion 20b1 that exceeds a semicircle and a linear
portion 20b2 that connects the both ends of the large circular
portion 20b1.
[0036] The suction-side umbrella unit 21U and the discharge-side
umbrella unit 22U, for example, the valve retainer concave portions
24Hb and 25Db (umbrella portions 21g and 22g) are slanted with
respect to the plane of the piezoelectric oscillator 30
(non-parallel). Considering a plane that is perpendicular to the
piezoelectric oscillator 30 and contains an axis line of the
suction port 31 (discharge port 32), in the plane, the
aforementioned slant direction is a direction in which the valve
retainer concave portions 24Hb and 25Db and the piezoelectric
oscillator 30 become more distant in the rear direction of the
suction port 31 (discharge port 32) and become closer in the front
direction of the suction port 31 (discharge port 32) to each
other.
[0037] As described above, when the suction-side and discharge-side
umbrella units 21U and 22U are slanted with respect to the
piezoelectric oscillator 30, the slim lower housing 20 can be
achieved without reducing the cross sections of the channels of the
suction and discharge ports 31 and 32.
[0038] As shown in FIG. 4, the surface (unit plate 21a of the
suction-side umbrella unit 21U (umbrella portion 21g)) of the valve
retainer concave portion 24Hb is not in parallel with the surface
of the piezoelectric oscillator 30 in a free state and is slanted
by an angle of .alpha. with respect to the surface of the
piezoelectric oscillator 30 in the free state. For example, the
channel at the suction-side check valve 21 is not perpendicular to
the piezoelectric oscillator 30. On the other hand, the axis line
of the suction port 31 (suction-side channel 24H) is in parallel
with the surface of the piezoelectric oscillator 30. The direction
of the angle of .alpha. is a direction in which the unit plate 21a
(umbrella portion 21g) of the suction-side umbrella unit 21U
becomes spaced apart from the piezoelectric oscillator 30 in the
rear direction of the suction port 31 (suction-side channel 24H)
and becomes closer to the piezoelectric oscillator 30 in the front
direction of the suction port 31 (suction-side channel 24H).
[0039] Similarly, as shown in FIG. 5, the surface (unit plate 22a
of the discharge-side umbrella unit 22U (umbrella portion 22g)) of
the valve retainer concave portion 25Db is not in parallel with the
surface of the piezoelectric oscillator 30 and is slanted by an
angle of .alpha. with respect to the surface of the piezoelectric
oscillator 30 in a free state. For example, the channel at the
discharge-side check valve 22 is not perpendicular to the
piezoelectric oscillator 30. Alternatively, the axis line of the
discharge port 32 (discharge-side channel 25D) is parallel with the
surface of the piezoelectric oscillator 30. The direction of the
angle of .alpha. is a direction in which the unit plate 22a
(umbrella portion 22g) of the discharge-side umbrella unit 22U
becomes apart from the piezoelectric oscillator 30 in the rear
direction of the discharge port 32 and becomes closer to the
piezoelectric oscillator 30 in the front direction of the discharge
port 32 (discharge-side channel 25D).
[0040] In the lower housing 20, bifurcated channels 24Hd and 25Dd
that are bifurcated from the suction-side channel 24H and the
discharge-side channel 25D, respectively, are formed to be opened
to the pump chamber plate 40 side. In the pump chamber plate 40,
communication holes 41 and 42 communicate with the bifurcated
channels 24Hd and 25Dd. An interplate suction-side channel 14H that
communicates with the communication hole 41 and an interplate
discharge-side channel 15D that communicates with the communication
hole 42 are formed between the upper housing 10 and the pump
chamber plate 40. For example, in the pump chamber plate 40, convex
portions 41a and 42a that are fit into the bifurcated channels 24Hd
and 25Dd are formed. The communication holes 41 and 42 are formed
at the center of the convex portions 41a and 42a. The reference
numerals 41b and 42b indicate o-rings for sealing the bifurcated
channels 24Hd and 25Dd with the convex portions 41a and 42a
(communication holes 41 and 42).
[0041] In the pump chamber plate 40, the pump chamber forming
concave portion 40a (FIGS. 2, 4, and 5) faces the piezoelectric
oscillator 30. The suction-side umbrella 11 corresponds to the
suction-side umbrella unit 21U and the discharge-side umbrella 12
corresponds to the discharge-side umbrella unit 22U that are
attached to the approximate center of the pump chamber forming
concave portion 40a. The suction-side umbrella 11 and the
discharge-side umbrella 12 are not shown in FIG. 2. For example, on
the pump chamber plate 40, umbrella attaching holes 11a and 12a are
formed under the suction-side umbrella unit 21U and the
discharge-side umbrella unit 22U.
[0042] A plurality of channel holes 11b and 12b are formed on the
circumferences of the umbrella attaching holes 11a and 12a. The
suction-side and discharge-side umbrellas 11 and 12 include a
central axis 11c (central axis 12c) inserted into the umbrella
attaching hole 11a (umbrella attaching hole 12a) and an umbrella
portion 11d (umbrella portion 12d) that covers the channel holes
11b (channel holes 12b) in normal times. When pressure greater than
a predetermined value is applied to the umbrella portion 11d
(umbrella portion 12d) from the channel hole 11b (channel hole 12b)
side, the umbrella portion 11d (umbrella portion 12d) is
elastically deformed to open the channel holes 11b (channel holes
12b).
[0043] The suction-side umbrella 11 allows a flow from the upper
housing 10 side toward the pump chamber that forms concave portion
40a (pump chamber 13) and does not allow a reverse flow. The
discharge-side umbrella 12 allows a flow from the pump chamber that
forms concave portion 40a (pump chamber 13) toward the upper
housing 10 side and does not allow a reverse flow.
[0044] The upper housing 10 has the same shape as the lower housing
20 so that the upper housing 10 overlaps the lower housing 20. In
the upper housing 10, a concave portion 14Ha that forms the
interplate suction-side channel 14H that communicates the
communication hole 41 with the suction-side umbrella 11 and a
concave portion 15Da that forms the interplate discharge-side
channel 15D that connects the communication hole 42 to the
discharge-side umbrella 12 are formed between the upper housing 10
and the pump chamber plate 40 (refer to FIGS. 2 and 4 to 6).
[0045] The seal ring grooves 14Hc and 15Dc that insert oval o-rings
(seal rings) 14Hb and 15Db are formed at the circumference of the
concave portions 14Ha and 15Da. A concave portion 10a (FIGS. 2 and
6) that inserts the pump chamber plate 40 into the upper housing 10
are formed in the upper housing 10.
[0046] A fitting hole 10c and a positioning protrusion 40c (FIG. 1)
that fits into the fitting hole 10c while the oval o-rings 14Hb and
15Db are inserted into the concave portions 14Ha and 15Da are
formed in the pump chamber plate 40 and the upper housing 10. The
positioning protrusion 40c is fitted into the fitting hole 10c and
adhered to the fitting hole 10c to form the sealed interplate
suction-side channel 14H from the communication hole 41 toward the
suction-side umbrella 11 and the sealed interplate discharge-side
channel 15D from the communication hole 42 toward the
discharge-side umbrella 12. For example, the upper housing 10 and
the pump chamber plate 40 are previously integrated with each other
by inserting the pump chamber plate 40 into the concave portion 10a
to form the interplate suction-side channel 14H and the interplate
discharge-side channel 15D that are closed therebetween. An
additional cover except the upper housing 10 and the pump chamber
plate 40 is not needed for forming the interplate suction-side
channel 14H and the interplate discharge-side channel 15D.
[0047] As shown in FIG. 7, in the pump chamber plate 40, a seal
ring groove 40b (that is the same shape as the seal ring groove of
the lower housing 20 on the plane) corresponding to the seal ring
groove of the lower housing 20 is formed at the circumference of
the pump chamber forming concave portion 40a that faces the
piezoelectric oscillator 30. The seal ring groove 40b has a
deformed D shape that includes a large circular portion 40b1 that
exceeds a semicircle and a linear portion 40b2 that connects both
ends of the large circular portion 40b1.
[0048] The piezoelectric oscillator 30 may be a unimorph or bimorph
type. FIGS. 8 to 10 are pattern diagrams of an embodiment of the
bimorph type piezoelectric oscillator disclosed in Japanese
Unexamined Patent Application Publication No. 2005-201235.
According to the embodiment, the bimorph type piezoelectric
oscillator includes a circular shim 111 at the center and
piezoelectric members 112 formed over and under the shim 111 by
deposition. The shim 111 includes a conductive metal sheet, for
example, a stainless steel sheet having a thickness of about 0.2
mm. The piezoelectric member 112 is made of Lead Zirconate Titanate
(PZT, Pb(Zr, Ti) O.sub.3). The piezoelectric member 112 is
polarized in the front-to-back direction of the piezoelectric
members 112. The polarization directions of the pair of
piezoelectric members located over the front and back surfaces of
the shim 111 are the same.
[0049] As shown in FIG. 8, when the polarization direction of the
pair of piezoelectric members 112 is represented by the arrow a or
b, the piezoelectric members 112 are polarized in the same
direction which is the thickness direction of the shim 111. In
other words, a pair of the piezoelectric members 112 that are in
contact with the front and back surfaces of the shim 111 are
polarized to have different poles from each other, at exposed
surfaces thereof. The exposed surfaces of the pair of the
piezoelectric members 112 are polarized to have different poles
from each other. As described above, when the piezoelectric members
112 are polarized in the same direction, the displacement of the
shim 111 can be increased when positive and negative voltages are
alternately applied between the shim 111 and the surfaces of the
pair of the piezoelectric members 112 that face the shim 111.
[0050] The surfaces of the pair of the piezoelectric members 112
that face the shim 111 are attached to the shim 111 so as to be
entirely electrically conductive to the shim 111. Film shaped
electrodes 113 are formed on the surfaces that do not face the shim
111. The film shaped electrodes 113 are formed by printing (screen
baking) a conducting paste (silver paste or gold paste).
[0051] A supply terminal 180 includes a pair of contacts 1811, a
connection edge 1812 for connecting the contacts 1811 with each
other, and a wiring connection portion 1813. The pair of contacts
1811 and the connection edge 1812 constitute a U-shaped cross
section. The pair of contacts 1811 have a wider width at the wiring
connection portion 1813 and have a gradually narrower width toward
the center of the piezoelectric oscillator 30 to form the same
approximate triangular shapes. For example, the contact 1811 has
the narrowest width at the soldering portion 1131 and has a wider
width toward the outside of the piezoelectric oscillator 30.
[0052] A wiring connection protrusion 114 that is protruded in the
diameter direction of the shim 111 of the piezoelectric oscillator
30 is extended between the pair of contacts 1181. In the wiring
connection protrusion 114, a concave portion 1141 for insulation
for securing a gap between the wiring connection protrusion 114 and
the connection edge that connects the pair of contacts 1181 with
the wiring connection protrusion 114 is formed.
[0053] Annular spacer insulation rings 115 are located over and
under the circular shim 111. Strip insulation sheets 1151 are
extended from the pair of spacer insulation rings 115 toward
between the pair of contacts 1181 and the wiring connection
protrusion 114 to prevent a short circuit between the shim 111 and
the supply terminal 180. At the same time, the strip insulation
sheets 1151 prevent the connection edge 1812 of the supply terminal
180 from moving to the concave portion 1141 of the shim 111 for
insulation to secure insulation.
[0054] A pair of lead wire holding concave portions 1143 and 1144
are symmetrically formed in the both sides of the wiring connection
protrusion 114 in the width direction and located at the outer side
of the piezoelectric oscillator 30 as compared with the concave
portion 1141 for insulation. A through hole 1145 for soldering is
formed at the inner side of the piezoelectric oscillator 30 as
compared with the one lead wire holding concave portion 1143.
[0055] A through hole 1814 for soldering is formed in
correspondence with the through hole 1145 for soldering of the
wiring connection protrusion 114 in the wiring connection portion
1813 of the supply terminal 180. The locations of the through holes
1145 and 1814 for soldering are different on the plane, and the
lead wires 211 and 221 are soldered into the through holes 1145 and
1814 for soldering. The through holes 1145 and 1814 for soldering
are located at different locations on the plane to enable the slim
sized diaphragm pump. In addition, the lead wires 211 and 221 are
held by the lead wire holding concave portions 1143 and 1144 to
increase coming-out stopping resistances of the lead wires 211 and
221.
[0056] A PPS film (insulation film) 241 (FIG. 8) is adhered to the
surface of the piezoelectric oscillator 30. The PPS film 241
includes a piece 241a in the diameter direction which is extended
over the supply terminal 180 to prevent separation between the
contacts 1811 and the film shaped electrodes 113 of the
piezoelectric oscillator 30.
[0057] The shim 111 and the film shaped electrode 113 can be
securely wired without disturbing the movement of the piezoelectric
oscillator 30 by using the aforementioned connection protrusion 114
of the shim 111 and the wiring structures around the supply
terminal 180.
[0058] The aforementioned circular piezoelectric oscillator 30 is
attached between the pump chamber forming concave portion 20a of
the lower housing 20 and the pump chamber forming concave portion
40a of the pump chamber plate 40, and the surroundings are sealed
by the seal rings 16 and 26 to form the pump chambers 13 and 23.
The seal rings 16 and 26 have the same shape as the seal ring
groove 20b of the lower housing 20 and the seal ring groove 40b of
the pump chamber plate 40 and include a large circular portion 16a
(large circular portion 26a) and a linear portion 16b (linear
portion 26b). In addition, the supply terminal 180 of the
piezoelectric oscillator 30 is located outside of the seal rings 16
and 26, and more specifically, outside of the linear portion 16b
(linear portion 26b). According to the aforementioned layout, the
supply terminal 180 for the piezoelectric members 112 of the
piezoelectric oscillator 30 need not to cross over the seal rings
16 and 26, and the seal rings 16 and 26 are not deformed, which in
turn improves the durability of the piezoelectric oscillator
30.
[0059] In addition, the lower housing 20 and the upper housing 10
previously integrated into the pump chamber plate 40 are combined
by a fastener (for example, bolts and nuts) to form one body while
the piezoelectric oscillator 30 is attached therebetween.
Alternatively, an additional adhesive may be used.
[0060] The basic operation of the present diaphragm pump having the
aforementioned structure is the same as the operation illustrated
in FIG. 11. When an alternating electric field is applied between
the supply terminal 180 of the piezoelectric oscillator 30 and the
shim 111 (wiring connection protrusion 114) to elastically deform
(oscillate) the piezoelectric oscillator 30 in forward and backward
directions, a volume of one pump chamber 13 or 23 increases and a
volume of the other pump chamber 23 or 13 decreases.
[0061] In a stroke that increases the volume of the pump chamber
13, since the suction-side umbrella 11 opens to introduce a fluid
into the pump chamber 13 from the pump port 31 and the volume of
the pump chamber 23 simultaneously decreases, a fluid in the pump
chamber 23 opens the discharge-side umbrella (unit) 22 to discharge
the fluid to the discharge port 32. In contrast, in a stroke that
decreases the volume of the pump chamber 13, since the suction-side
umbrella (unit) 21 opens to introduce a fluid into the pump chamber
23 from the suction port 31 and the volume of the pump chamber 13
decreases, a fluid in the pump chamber 13 opens the discharge-side
umbrella 12 to discharge the fluid to the discharge port 32.
[0062] The seal rings 16 and 26 have a non-circular shape, and
alternatively, circular seal rings (o-rings) may be used. In
addition, although the umbrella is used as an example of the check
valve in the embodiment, it is possible to use another check valve
except the umbrella. Although the piezoelectric oscillator is used
as the diaphragm in the aforementioned embodiment, it is possible
to use an electrostriction oscillator instead of the piezoelectric
oscillator.
* * * * *