U.S. patent application number 10/127535 was filed with the patent office on 2003-01-02 for pump and method of manufacturing same.
This patent application is currently assigned to MATSUSHITA ELECTRIC WORKS, LTD.. Invention is credited to Kawaguchi, Tatsuji, Kitahara, Harunori, Urano, Youji.
Application Number | 20030002995 10/127535 |
Document ID | / |
Family ID | 18975035 |
Filed Date | 2003-01-02 |
United States Patent
Application |
20030002995 |
Kind Code |
A1 |
Urano, Youji ; et
al. |
January 2, 2003 |
Pump and method of manufacturing same
Abstract
A compact pump has a pump chamber, inlet and outlet channels
communicating with the pump chamber, and a pair of check valve
units between the pump chamber and the inlet and outlet channels.
Each check valve unit has a thin film check valve membrane, and a
check valve body with a channel opened and closed by the check
valve membrane due to a pressure difference.
Inventors: |
Urano, Youji; (Osaka,
JP) ; Kawaguchi, Tatsuji; (Osaka, JP) ;
Kitahara, Harunori; (Osaka, JP) |
Correspondence
Address: |
OBLON SPIVAK MCCLELLAND MAIER & NEUSTADT PC
FOURTH FLOOR
1755 JEFFERSON DAVIS HIGHWAY
ARLINGTON
VA
22202
US
|
Assignee: |
MATSUSHITA ELECTRIC WORKS,
LTD.
Kadoma-shi
JP
|
Family ID: |
18975035 |
Appl. No.: |
10/127535 |
Filed: |
April 23, 2002 |
Current U.S.
Class: |
417/322 ;
417/413.2; 417/559; 417/569 |
Current CPC
Class: |
F04B 43/046 20130101;
F04B 53/1062 20130101 |
Class at
Publication: |
417/322 ;
417/559; 417/569; 417/413.2 |
International
Class: |
F04B 017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 24, 2001 |
JP |
2001-125904 |
Claims
What is claimed is:
1. A piezoelectric pump for sucking fluid to a pump chamber and
discharging fluid from the pump chamber by changing a volume of the
pump chamber by action of a piezoelectric actuator, said
piezoelectric pump comprising: a casing having inlet and outlet
flow channels both communicating with the pump chamber; first and
second check valve units each having a thin-film check valve
membrane and a check valve body having a channel opened and closed
by the check valve membrane; and the first and second check valve
units being disposed between the pump chamber and the inlet and
outlet flow channels, respectively.
2. The piezoelectric pump according to claim 1, further comprising
a diaphragm comprising a piezoelectric actuator and a thin metal
plate joined together, wherein the diaphragm is mounted to the
casing to form the pump chamber between the diaphragm and the
casing.
3. The piezoelectric pump according to claim 1, wherein the first
and second check valve units are identically configured and
installed to the casing in inverse positions.
4. The piezoelectric pump according to claim 1, wherein the first
and second check valve units are installed to the casing from a
side opposite the diaphragm side.
5. The piezoelectric pump according to claim 1, wherein the casing
comprises a first casing part to which the diaphragm is disposed
and a second casing part that is separate from the first casing
part and to which the first and second check valve units are
installed.
6. The piezoelectric pump according to claim 5, wherein a fitting
structure is used at least between the casing and the first and
second check valve units or between the first and second casing
parts, and the fitting structure is an interference fitting
assembled by press fitting.
7. The piezoelectric pump according to claim 5, wherein a fitting
structure is used at least between the casing and the first and
second check valve units or between the first and second casing
parts, and the fitting structure is a transition fitting or
clearance fitting completed with adhesion or welding.
8. The piezoelectric pump according to claim 5, wherein a fitting
structure is used at least between the casing and the first and
second check valve units or between the first and second casing
parts, and the fitting structure has screw threads formed therein
for screw fitting.
9. The piezoelectric pump according to claim 1, wherein the check
valve membrane is positioned to cover the channel in the check
valve body, and the check valve membrane is joined to the check
valve body.
10. The piezoelectric pump according to claim 9, wherein the check
valve membrane has at least one vent formed therein and is disposed
so as to cover the channel in the check valve body, and the check
valve membrane around the vent is joined to the check valve
body.
11. The piezoelectric pump according to claim 10, wherein the check
valve membrane has two vents formed at positions on opposite sides
of the channel.
12. The piezoelectric pump according to claim 10, wherein the check
valve membrane has a single vent parallel to a tangent to the
outside circumference of the channel, the single vent being formed
at a position removed from the channel.
13. The piezoelectric pump according to claim 10, wherein the check
valve membrane has a plurality of vents each parallel to a tangent
to an outside circumference of the channel, the plurality of vents
being formed circumferentially to the channel at positions removed
therefrom.
14. The piezoelectric pump according to claim 10, wherein the vent
in the check valve membrane is shaped into a continuous curve.
15. The piezoelectric pump according to claim 9, wherein the check
valve membrane is disposed so as to cover the channel, and two
sides thereof on opposite sides of the channel are joined to the
check valve body.
16. The piezoelectric pump according to claim 9, wherein the check
valve membrane has one openable side and is disposed so as to cover
the channel, the check valve membrane being joined to the check
valve body surrounding the channel except on the one openable
side.
17. The piezoelectric pump according to claim 9, wherein the check
valve membrane is disposed so as to cover the channel and joined in
spots around the circumference of the channel to the check valve
body, and intervals between the joined spots are vents.
18. The piezoelectric pump according to claim 17, wherein the check
valve membrane is shaped into a polygon and placed so as to cover
the channel, and each corner of the polygon is joined to the check
valve body.
19. The piezoelectric pump according to claim 9, wherein the check
valve membrane has a flap formed by removing a part of a thin film,
and the check valve membrane is joined to the check valve body
around the perimeter of the flap.
20. The piezoelectric pump according to claim 19, wherein the
channel opened and closed by the flap is formed from a plurality of
openings separated a specific interval, and a support part for
supporting the flap is formed in a center of the plurality of
openings.
21. The piezoelectric pump according to claim 9, wherein the check
valve membrane is formed into a rectangular strip and is joined on
only one side thereof perpendicular to a long side thereof to the
check valve body.
22. The piezoelectric pump according to claim 9, wherein the check
valve body is formed with first and second spacers having a fitting
structure, and the check valve membrane is inserted between and
joined to the first and second spacers.
23. The piezoelectric pump according to claim 22, wherein the first
and second spacers are bonded.
24. The piezoelectric pump according to claim 9, wherein the check
valve membrane and the check valve body are welded together.
25. The piezoelectric pump according to claim 9, wherein the check
valve body is formed with first and second spacers, the check valve
membrane is disposed between the first and second spacers, and the
first and second spacers and the check valve membrane are welded
together.
26. A method of manufacturing a pump, comprising: forming a vent in
a check valve membrane made of a thin film; forming a channel in a
check valve body; placing the check valve membrane so as to cover
the channel; joining the check valve membrane around the vent to
the check valve body to form a check valve unit in which the
channel is opened and closed by the check valve membrane due to a
pressure differential; and installing the check valve unit in a
casing.
27. The method according to claim 26, wherein the vent in the thin
film is formed with an excimer laser.
28. A method of manufacturing a pump, comprising: forming a channel
in a check valve body; placing a check valve membrane so as to
cover the channel; joining the check valve membrane to the check
valve body around the channel; forming a vent in the check valve
membrane at a position between a joint and the channel to form a
check valve unit in which the channel is opened and closed by the
check valve membrane due to a pressure differential; and installing
the check valve unit in a casing.
29. The method according to claim 28, wherein the vent in the thin
film is formed with an excimer laser.
30. A method of manufacturing a pump, comprising: forming a channel
in a check valve body; placing a check valve membrane so as to
cover the channel; pressing the check valve membrane to the check
valve body with a glass plate while a laser beam is emitted to weld
the check valve membrane to the check valve body to form a check
valve unit in which the channel is opened and closed by the check
valve membrane due to a pressure differential; and installing the
check valve unit in a casing.
31. The method according to claim 30, wherein an iris having an
aperture is used for laser welding to simultaneously weld specific
parts of the check valve membrane to the check valve body.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to a small pump used
in a sphygmomanometer, for example, and, in particular but not
exclusively, to the structure of a piezoelectric pump that operates
with the action of a piezoelectric actuator.
[0003] 2. Description of the Related Art
[0004] A pump of this type is taught in Japanese Laid-Open Patent
Publication (unexamined) No. 59-200081, U.S. Pat. No. 6,033,191 and
the like.
[0005] As shown in FIG. 46, the pump taught in U.S. Pat. No.
6,033,191 is of a lamellar construction having a valve membrane 52
disposed between an upper housing 50 and a lower housing 51 with
inlet and outlet flow channels 53 formed on the upper surface of
the lower housing 51. A diaphragm 54 vibrated by a piezoelectric
actuator is disposed on the upper housing 50, forming a pump
chamber between the diaphragm 54 and top of the upper housing 50.
The pump chamber and inlet and outlet side flow channels 53
communicate through respective holes 55 in the upper housing 50,
and inlet and outlet check valves are formed by the valve membrane
52 at portions where holes 55 and flow channels 53 communicate.
When the diaphragm 54 vibrates, air is sucked to the pump chamber
from the suction side flow channel 53 and air is discharged from
the pump chamber to the discharge side flow channel 53.
[0006] A problem with a compact pump thus comprised is that in
order to assure airtightness it is necessary to assure sufficient
flatness and parallelism on the mating surfaces of the upper and
lower housings 50, 51. It is also difficult to simultaneously
position the three layers, upper housing 50, lower housing 51, and
valve membrane 52.
[0007] In addition, if positioning precision drops when the check
valve is formed by disposing the valve membrane 52 between the
upper housing 50 and lower housing 51, production yield of the pump
body also drops.
[0008] Furthermore, the mating faces of the upper and lower
housings 50, 51 are laser welded along the flow channels 53 as
indicated by the welding beads 56 shown in FIG. 47 for
airtightness, but air leaks between the valve membrane 52 and upper
housing 50 are unavoidable in the flow channels 53. This creates a
problem of degraded compression efficiency. Forming the flow
channels 53 is not simple, in addition.
[0009] A problem with the pump taught in Japanese Laid-Open Patent
Publication No. 59-200081 is that because it uses a check valve the
upper housing must be thick enough to dispose the check valve
therein, and the upper housing cannot be made extremely thin.
SUMMARY OF THE INVENTION
[0010] The present invention is therefore directed to solving the
problems described above by providing a compact pump that is easy
to manufacture and offers high efficiency and reliability, and by
providing a manufacturing method for this pump.
[0011] In accomplishing the above and other objectives, a pump
according to the present invention is a piezoelectric pump for
sucking fluid to a pump chamber and discharging fluid from the pump
chamber by changing a volume of the pump chamber by action of a
piezoelectric actuator. The piezoelectric pump includes a casing
having inlet and outlet flow channels both communicating with the
pump chamber, and first and second check valve units each having a
thin-film check valve membrane and a check valve body having a
channel opened and closed by the check valve membrane. The first
and second check valve units are disposed between the pump chamber
and the inlet and outlet flow channels, respectively.
[0012] This configuration makes it possible to easily manufacture a
compact pump and improve the pump efficiency.
[0013] The check valve function of the check valve units can also
be confirmed before installation to the casing, thereby improving
pump reliability and improving pump manufacturing yield.
Furthermore, if a check valve becomes damaged from extended use,
this configuration enables replacing only the damaged check valve
unit.
[0014] The diaphragm is preferably made up of a piezoelectric
actuator and a thin metal plate joined together and is mounted to
the casing, forming a pump chamber between the diaphragm and
casing. This makes it possible to reduce the volume of fluid from
the pump chamber to the check valve membrane, and increases the
pressure inside the pump chamber during discharge, as compared with
conventional pumps. High pressure fluid discharge is thus possible,
and pump efficiency improves.
[0015] Further preferably, the first and second check valve units
are identically configured and installed to the casing in inverse
positions. Identical check valve units can therefore be used on
both suction and discharge sides, and production cost can therefore
be reduced.
[0016] Further preferably, the check valve units are installed to
the casing from the side opposite the diaphragm side, making it
possible to replace the check valve unit without removing the
diaphragm.
[0017] The diaphragm is easily damaged by external force. However,
if the casing part to which the diaphragm is disposed and the
casing part to which the check valve units are installed are
separate parts, the part to which the diaphragm is joined and the
part to which the check valve units are fit can be separated,
making it easier to replace the diaphragm and easier to replace the
check valve units. Furthermore, because the same check valve unit
can be used with different diaphragms, it is easy to determine how
pump characteristics change when the diaphragm is changed.
[0018] Further preferably, a fitting structure is used at least
between the casing and check valve units or between the discrete
casing parts, and this fitting structure is preferably an
interference fitting assembled by press fitting. This makes it
simple to separate the casing and check valve unit (or the casing
parts) when replacing a check valve unit (or a diaphragm). An
interference fitting also makes it easy to secure the check valve
unit (or casing part) in the casing (or other casing part),
airtightness is assured by interference fitting, and pump
reliability can be improved.
[0019] The same benefits can be achieved using a transition fitting
or clearance fitting completed with adhesion or welding.
[0020] It is also possible to form screw threads on the fitting
surfaces so that the casing and check valve units, or the casing
parts, are screwed together. The parts can thus be easily fastened
together or separated.
[0021] If the check valve membrane is disposed covering the channel
in the check valve body and the check valve membrane is joined to
the check valve body, a check valve membrane of the smallest
necessary size can be used and the yield of the thin film material
used for the check valve membrane can be improved.
[0022] If the check valve membrane having one or more vents formed
therein is disposed covering the channel in the check valve body,
and the check valve membrane around the vent containing the channel
is joined to the check valve body, the size of the thin film can be
freely set, handling is easier during assembly, and welding is also
easier.
[0023] If the vents are formed at positions on opposite sides of
the channel, a check valve that operates reliably and has an
extremely simple configuration can be provided, and high precision
positioning is not needed for the check valve membrane.
[0024] If a single vent parallel to a tangent to the outside
circumference of the channel is formed at a position removed from
the channel, leaks cannot easily occur. If a plurality of vents
each parallel to a tangent to the outside circumference of the
channel are formed circumferentially to the channel at positions
removed therefrom, the check valve membrane is prevented from
wrinkling.
[0025] Furthermore, if the shape of a vent formed in the check
valve membrane is a continuous curve, damage to the check valve
membrane due to tension is prevented.
[0026] Yet further, if the check valve membrane is disposed
covering the channel and two sides on opposite sides of the channel
are joined to the check valve body, a check valve can be formed
with a simple configuration and high precision positioning is not
needed for the check valve membrane.
[0027] If a check valve membrane having one openable side is
disposed covering the channel and is joined to the check valve body
surrounding the channel except on the one openable side, a check
valve function can be achieved with a simple configuration and
leaks cannot occur easily.
[0028] If the check valve membrane is disposed covering the
channel, the check valve membrane is joined in spots around the
circumference of the channel to the check valve body, and intervals
between the joined spots function as vents, and therefore the spots
where the check valve membrane is joined to the check valve body
will be concentric to the channel and wrinkles will not easily
occur in the check valve membrane.
[0029] If a polygonally shaped check valve membrane is placed
covering the channel and each corner of the polygon is joined to
the check valve body, the spots where the check valve membrane is
joined to the check valve body will be concentric to the channel.
Wrinkles will therefore not easily occur in the check valve
membrane, and the edges of the check valve membrane will not curl
because the sides that open are straight.
[0030] Furthermore, if the check valve membrane has a flap formed
by removing a part of a thin film, and the check valve membrane is
joined to the check valve body around the flap, a check valve unit
with a simple configuration not requiring high precision
positioning of the check valve membrane can be provided.
Furthermore, because the channel is opened and closed by the
flexural modulus of the thin film, pressure loss due to the tension
of the thin film can be reduced.
[0031] Furthermore, if the channel opened and closed by the flap is
formed from a plurality of openings separated a specific interval
and a support part for supporting the flap is formed in a center of
the plurality of openings, fluid leaks resulting from the thin film
being pulled into the channel can be prevented, and the pressure
inside the pump can be further increased.
[0032] If the check valve membrane is formed into a rectangular
strip and is joined on only one side perpendicular to a long side
to the check valve body, a check valve unit with a simple
configuration not requiring high precision positioning of the check
valve membrane can be provided. In addition, the channel can be
opened and closed by the flexural modulus of the thin film, and
pressure loss due to the tension of the thin film can be
reduced.
[0033] If the check valve body is formed with first and second
spacers, the first and second spacers have a fitting structure, and
the check valve membrane is inserted between and joined to the
first and second spacers when they are fit together, the check
valve membrane can be easily fixed in place by an interference
fitting, for example.
[0034] If the first and second spacers are adhesively bonded, air
leaks can be eliminated.
[0035] Furthermore, if the check valve membrane and check valve
body are welded together, the check valve membrane can be reliably
joined to the check valve body by welding.
[0036] If the check valve body is formed with first and second
spacers, the check valve membrane is disposed between the first and
second spacers, and the first and second spacers and check valve
membrane are welded together, welding damage to the check valve
membrane is prevented because three layers are welded.
[0037] A manufacturing method for a pump according to another
aspect of the invention includes: forming a vent in a check valve
membrane made of a thin film; forming a channel in a check valve
body; placing the check valve membrane so as to cover the channel;
joining the check valve membrane around the vent to the check valve
body to form a check valve unit in which the channel is opened and
closed by the check valve membrane due to a pressure differential;
and installing the check valve unit in a casing.
[0038] Vents can thus be easily formed in the thin film, and high
precision positioning is not needed when welding.
[0039] The vents can be formed in the check valve membrane after
check valve unit is assembled. This completely eliminates any need
for positioning the check valve membrane for joining to the check
valve body. The vents can also be formed at appropriate positions
after the check valve membrane is fixed.
[0040] If the vents in the thin film are formed with an excimer
laser, wrinkles are not formed by process heat, the thin film can
be precision processed, and there is little likelihood of damage
(laser marks) being left on the check valve body from
post-processing.
[0041] Another manufacturing method for a pump according to the
present invention includes: forming a channel in a check valve
body; placing a check valve membrane so as to cover the channel;
joining the check valve membrane to the check valve body around the
channel; forming a vent in the check valve membrane at a position
between a joint and the channel to form a check valve unit in which
the channel is opened and closed by the check valve membrane due to
a pressure differential; and installing the check valve unit in a
casing.
[0042] This method holds the check valve membrane and the check
valve body tight together while welding them together, and thus
improves airtightness.
[0043] Furthermore, if an iris having an aperture is used for laser
welding to simultaneously weld specific parts of the check valve
membrane to the check valve body, the effects of welding heat can
be further lessened.
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] The above and other objectives and features of the present
invention will become more apparent from the following description
of preferred embodiments thereof with reference to the accompanying
drawings, throughout which like parts are designated by like
reference numerals, and wherein:
[0045] FIG. 1 is a perspective view of a diaphragm pump according
to a first embodiment of the present invention;
[0046] FIG. 2 is an exploded perspective view of the pump shown in
FIG. 1;
[0047] FIG. 3 is an exploded perspective view of a check valve unit
disposed in the pump shown in FIG. 1;
[0048] FIG. 4A is a sectional view showing the suction operation of
the check valve unit shown in FIG. 3;
[0049] FIG. 4B is a sectional view showing the discharge operation
of the check valve unit shown in FIG. 3;
[0050] FIG. 5A is a perspective view of a check valve unit in a
diaphragm pump according to a second preferred embodiment of the
present invention;
[0051] FIG. 5B is a sectional view of the diaphragm pump having the
check valve unit shown in FIG. 5A;
[0052] FIG. 6A is a perspective view of a check valve unit in a
diaphragm pump according to a third preferred embodiment of the
present invention;
[0053] FIG. 6B is a sectional view of the diaphragm pump having the
check valve unit shown in FIG. 6A;
[0054] FIG. 7A is an exploded perspective view of a diaphragm pump
according to a fourth preferred embodiment of the present
invention;
[0055] FIG. 7B is a sectional view of the diaphragm pump shown in
FIG. 7A;
[0056] FIG. 8 is a perspective view as viewed from the back of an
assembled diaphragm pump according to a modification of the pump
shown in FIG. 7A;
[0057] FIG. 9 is a perspective view of a check valve membrane
disposed in a check valve unit according to the present
invention;
[0058] FIG. 10A is a perspective view of the check valve membrane
shown in FIG. 9 when open;
[0059] FIG. 10B is a sectional view of the check valve membrane
shown in FIG. 9 when open;
[0060] FIG. 11A is a perspective view of the check valve membrane
shown in FIG. 9 when closed;
[0061] FIG. 11B is a sectional view of the check valve membrane
shown in FIG. 9 when closed;
[0062] FIG. 12 is a perspective view of an alternative check valve
membrane;
[0063] FIG. 13A is a perspective view of the check valve membrane
shown in FIG. 12 when open;
[0064] FIG. 13B is a sectional view of the check valve membrane
shown in FIG. 12 when open;
[0065] FIG. 14A is a perspective view of the check valve membrane
shown in FIG. 12 when closed;
[0066] FIG. 14B is a sectional view of the check valve membrane
shown in FIG. 12 when closed;
[0067] FIG. 15A is a perspective view of another alternative check
valve membrane;
[0068] FIG. 15B is a perspective view of the check valve membrane
shown in FIG. 15A when open;
[0069] FIG. 16A is a perspective view of another alternative check
valve membrane;
[0070] FIG. 16B is a perspective view of the check valve membrane
shown in FIG. 16A when open;
[0071] FIG. 17A is a perspective view of another alternative check
valve membrane;
[0072] FIG. 17B is a perspective view of the check valve membrane
shown in FIG. 17A when open;
[0073] FIG. 18 is a perspective view of another alternative check
valve membrane;
[0074] FIG. 19A is a perspective view of the check valve membrane
shown in FIG. 18 when open;
[0075] FIG. 19B is a sectional view of the check valve membrane
shown in FIG. 18 when open;
[0076] FIG. 20A is a perspective view of the check valve membrane
shown in FIG. 18 when closed;
[0077] FIG. 20B is a sectional view of the check valve membrane
shown in FIG. 18 when closed;
[0078] FIG. 21 is a perspective view of another alternative check
valve membrane;
[0079] FIG. 22A is a perspective view of the check valve membrane
shown in FIG. 21 when open;
[0080] FIG. 22B is a sectional view of the check valve membrane
shown in FIG. 21 when open;
[0081] FIG. 23A is a perspective view of the check valve membrane
shown in FIG. 21 when closed;
[0082] FIG. 23B is a sectional view of the check valve membrane
shown in FIG. 21 when closed;
[0083] FIG. 24 is a perspective view of another alternative check
valve membrane;
[0084] FIG. 25A is a perspective view of the check valve membrane
shown in FIG. 24 when open;
[0085] FIG. 25B is a sectional view of the check valve membrane
shown in FIG. 24 when open;
[0086] FIG. 26A is a perspective view of the check valve membrane
shown in FIG. 24 when closed;
[0087] FIG. 26B is a sectional view of the check valve membrane
shown in FIG. 24 when closed;
[0088] FIG. 27A is a perspective view of another alternative check
valve membrane;
[0089] FIG. 27B is a perspective view of the check valve membrane
shown in FIG. 27A when open;
[0090] FIG. 28A is a perspective view of a channel with a
configuration different from that shown in FIG. 27A;
[0091] FIG. 28B is a perspective view of the check valve membrane
shown in FIG. 28A when open;
[0092] FIG. 29A is a perspective view of another alternative check
valve membrane;
[0093] FIG. 29B is a perspective view of the check valve membrane
shown in FIG. 29A when open;
[0094] FIG. 30 is an exploded perspective view of a check valve
unit;
[0095] FIG. 31 is a perspective view of the check valve unit shown
in FIG. 30;
[0096] FIG. 32 is a sectional view of the check valve unit shown in
FIG. 30;
[0097] FIG. 33 is an exploded perspective view of another check
valve unit;
[0098] FIG. 34 is a perspective view of the check valve unit shown
in FIG. 33;
[0099] FIG. 35 is a sectional view of the check valve unit shown in
FIG. 33;
[0100] FIG. 36 is an exploded perspective view of another check
valve unit;
[0101] FIG. 37 is a perspective view of the check valve unit shown
in FIG. 36;
[0102] FIG. 38 is a sectional view of the check valve unit shown in
FIG. 36;
[0103] FIG. 39 is a perspective view showing the formation of vents
in the check valve membrane after the check valve unit is
assembled;
[0104] FIG. 40 is a perspective view of the check valve unit before
the check valve membrane is welded;
[0105] FIG. 41 is a perspective view of the check valve unit when
the check valve membrane is welded;
[0106] FIG. 42 is a perspective view showing welding of the check
valve membrane using a laser device;
[0107] FIG. 43A is a perspective view showing a preferred
embodiment of a diaphragm pump according t o the pre sent
invention;
[0108] FIG. 43B is an exploded perspective view of the diaphragm
pump shown in FIG. 42A;
[0109] FIG. 43C is an exploded perspective view of a check valve
unit disposed in the diaphragm pump shown in FIG. 43A;
[0110] FIG. 44A is a perspective view showing an example of the
check valve unit shown in FIG. 43C;
[0111] FIG. 44B is a partial perspective view of the check valve
unit shown in FIG. 44A;
[0112] FIG. 44C is a perspective view showing the check valve
membrane in the check valve unit shown in FIG. 43C when open;
[0113] FIG. 45A is a perspective view showing welding of the check
valve membrane to the check valve unit using a YAG laser;
[0114] FIG. 45B is a perspective view showing the formation of
vents in the check valve membrane using an excimer laser;
[0115] FIG. 46 is an exploded perspective view of a prior art
diaphragm pump; and
[0116] FIG. 47 is a partial sectional view of the prior art
diaphragm pump shown in FIG. 46.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0117] This application is based on an application No. 2001-125904
filed Apr. 24, 2001 in Japan, the content of which is herein
expressly incorporated by reference in its entirety.
[0118] Preferred embodiments of the present invention are described
below with reference to the accompanying drawings.
[0119] Embodiment 1
[0120] FIGS. 1 to 3 and FIGS. 4A and 4B show a diaphragm pump
having a disc-shaped diaphragm 12, a disc-shaped casing 9, and a
pair of check valve units 8. The diaphragm 12 is disposed on top of
the casing 9 with the edges of the diaphragm 12 welded or
adhesively bonded to the top of the casing 9, thereby forming a
pump chamber 1 between the diaphragm 12 and casing 9.
[0121] The outside diameter A of the diaphragm 12 in this exemplary
pump is 20 mm, the outside diameter B of the casing 9 is 22 mm, and
the height C is 3 mm.
[0122] An inlet channel 2 for suction into the pump chamber 1 and
an outlet channel 3 for discharge from the pump chamber 1 are
formed in the casing 9 through the thickness direction of the
casing 9. Check valve housings 18 are formed between the pump
chamber 1 and the inlet and outlet channels 2, 3. The check valve
units 8 are housed in these check valve housings 18. Each check
valve unit 8 has a check valve membrane 5, which is a thin film
with elasticity, and a check valve body 7, which has a channel 6
opened and closed by the check valve membrane 5 according to the
pressure differential between respective sides thereof. Channel 6
passes completely through the check valve body 7, and channels 2, 3
communicate with the pump chamber 1 through channels 6.
[0123] The check valve body 7 has a first spacer 7a and a second
spacer 7b. The check valve membrane 5 is located between the first
spacer 7a and second spacer 7b so as to block the channel 6, and
the check valve membrane 5 is disposed in the check valve body 7 by
integrating the check valve membrane 5 with the first spacer 7a and
second spacer 7b.
[0124] The check valve unit 8 on the inlet channel 2 side displaces
upward and opens when pressure is applied from the inlet channel 2
to the pump chamber 1, and a space 19 large enough for the check
valve membrane 5 to so displace is disposed in the first spacer 7a
on the pump chamber 1 side.
[0125] The check valve unit 8 on the outlet channel 3 side
displaces downward and opens when pressure is applied from the pump
chamber 1 to the outlet channel 3 side, and a space 19 large enough
for the check valve membrane 5 to so displace is disposed in the
second spacer 7b on the side away from the pump chamber 1.
[0126] When the diaphragm 12 is vibrated by the piezoelectric
actuator or other drive means, vibration of diaphragm 12 causes
suction of fluid from the inlet channel 2 to the pump chamber 1,
and causes the fluid compressed inside the pump chamber 1 to then
be discharged from the outlet channel 3. During suction phase the
diaphragm 12 is driven to separate from the casing 9 as shown in
FIG. 4A and fluid can be suctioned from the inlet channel 2 into
the pump chamber 1 because the check valve membrane 5 communicating
with the inlet channel 2 opens while the check valve membrane 5
communicating with the outlet channel 3 closes. Similarly during
the discharge phase, the diaphragm 12 is driven in the direction
closing to the casing 9 as shown in FIG. 4B, but this time the
check valve membrane 5 communicating with the inlet channel 2
closes and the check valve membrane 5 communicating with the outlet
channel 3 opens so that fluid can be discharged from the pump
chamber 1 to the outlet channel 3.
[0127] By constructing the check valve unit 8 separately from the
casing 9 as described above, the check valve unit 8 can be
installed to the casing 9 after first confirming that the check
valve unit 8 functions properly, and pump production yield can
therefore be improved. Furthermore, if a check valve becomes
damaged with extended use, for example, it is possible to replace
just the damaged check valve unit 8.
[0128] The diaphragm 12 is made up of a piezoelectric actuator 10
and a brass or other thin metal plate 11. The piezoelectric
actuator 10 is a PZT element or other piezoelectric element with
silver or other metallic conductor electrodes. When a voltage such
as a commercial AC voltage is applied to the piezoelectric actuator
10, the diaphragm 12 is reciprocally driven by the piezoelectric
actuator 10 and a pumping action is achieved.
[0129] The first and second spacers 7a, 7b and the check valve
membrane 5 of the check valve body 7 are made, for example, from
polycarbonate (PC) resin, and the casing 9 is made of
polyphthalamide (PPA), for example.
[0130] The distance from the top of the casing 9, which is the
bottom of the pump chamber 1, to the check valve membrane 5 is
shorter, and the volume of the channels from the pump chamber 1 to
both check valve membranes 5 when fluid is ingested to the pump
chamber 1 is less in this embodiment than in the related art
described above. If V is the volume of the channels from the pump
chamber 1 to both check valve membranes 5 when fluid is ingested to
the pump chamber 1, .DELTA.V is the discharge volume, that is, the
volume discharged for this V, and .DELTA.P is the internal pressure
rise from the initial pressure P,
.DELTA.P=.DELTA.V/(V-.DELTA.V).times.P, and .DELTA.P is increased
by reducing V.
[0131] Embodiment 2
[0132] FIG. 5A and FIG. 5B show a different embodiment in which the
fluid suction side check valve unit 8 and fluid discharge side
check valve unit 8 are identically constructed, and are simply
installed to the casing 9 in different directions on the suction
and discharge sides.
[0133] As in the first embodiment the check valve body 7 has a
first spacer 7a and second spacer 7b, but in this embodiment the
first spacer 7a and second spacer 7b have the same thickness and
outside diameter. A check valve membrane 5 is disposed between the
first spacer 7a and second spacer 7b, and a space 19 of a diameter
large enough for the check valve membrane 5 to displace is disposed
in the first spacer 7a. The suction-side check valve unit 8 is
installed so that the first spacer 7a is on the pump chamber 1
side, and the discharge-side check valve unit 8 is installed so
that the second spacer 7b is on the pump chamber 1 side.
[0134] Production cost is reduced with this embodiment because the
same check valve unit 8 can be used on both the suction and
discharge sides.
[0135] Embodiment 3
[0136] FIG. 6A and FIG. 6B show a different embodiment in which the
check valve units 8 are housed to the casing 9 from the side
opposite the diaphragm 12 side.
[0137] As shown in FIG. 6A and FIG. 6B, the check valve body 7 has
a first spacer 7a, second spacer 7b, and third spacer 7c. Similarly
to the first spacer 7a and second spacer 7b, this third spacer 7c
is made of polycarbonate resin.
[0138] A check valve membrane 5 is again disposed between the first
spacer 7a and second spacer 7b, but the space 19 for check valve
membrane 5 displacement is disposed to the first spacer 7a in the
suction-side check valve unit 8 and is disposed to the second
spacer 7b in the discharge-side check valve unit 8.
[0139] By thus inserting the check valve units 8 to the check valve
housings 18 in the casing 9 from the side of the casing 9 opposite
the diaphragm 12, this embodiment enables the check valve units 8
to be replaced without removing the diaphragm 12.
[0140] Embodiment 4
[0141] FIG. 7A and FIG. 7B show an embodiment in which the casing
part 9a to which the diaphragm 12 is disposed and the casing part
9b to which the check valve units 8 are disposed are separate
components.
[0142] As shown in FIG. 7A and FIG. 7B, the disc-shaped casing 9 is
formed from a casing part 9a and a separate casing part 9b. The one
casing part 9a is annularly shaped with a hole 20 in the center.
The other casing part 9b is disc-shaped with a protrusion 21 on
top. The protrusion 21 of this casing part 9b is fit to the hole 20
in casing part 9a to integrate casing part 9a and casing part 9b.
The diaphragm 12 is disposed on top of casing part 9a and
integrated with the casing part 9a by bonding the edge of the
diaphragm 12 to the top of the casing part 9a. The check valve
units 8 are installed to casing part 9b.
[0143] While the diaphragm 12 is susceptible to damage from
external forces with this configuration, the part to which the
diaphragm 12 is disposed can be separated from the part to which
the check valve units 8 are disposed, and the diaphragm 12 and
check valve units 8 can therefore be easily replaced. Furthermore,
because the same set of check valve units 8 can be used when the
diaphragm 12 is replaced, pump characteristics can be easily
evaluated after the diaphragm 12 is exchanged.
[0144] Installing the check valve units 8 to the casing 9, and
assembling the two casing parts 9a, 9b, are described next.
[0145] An integrated casing 9 is assembled by interference fitting
the protrusion 21 of casing part 9b into the hole 20 in casing part
9a. The check valve units 8 can also be installed by interference
fitting them into the check valve housings 18 in the casing part
9b. If the inside diameter of the hole 20 and the outside diameter
of the protrusion 21 are both nominally 16 mm, the protrusion 21
can be interference fit in the hole 20 by forming the hole 20 with
a tolerance of +0.018 mm to 0 mm and the protrusion 21 with a
tolerance of +0.029 mm to +0.018 mm.
[0146] By interference fitting components together as described
above, the check valve unit 8 and casing 9 (or casing part 9a and
casing part 9b) can be easily separated in order to replace a check
valve unit 8 (or diaphragm 12 ). Furthermore, the tolerances of the
interference fitting makes it easy to secure the check valve units
8 (or casing part 9b) in the casing 9 (or casing part 9a), and
airtightness can be assured by press fitting.
[0147] The process tolerances between the casing 9 and check valve
units 8, or between the separate casing parts 9a and 9b can be set
for transition fitting or clearance fitting with the fitting then
secured by adhesive bonding or welding.
[0148] For example, if the inside diameter of the hole 20 and the
outside diameter of the protrusion 21 are both nominally 16 mm and
the tolerance of the hole 20 is +0.018 mm to 0 mm and the tolerance
of protrusion 21 is 0 mm to -0.018 mm, the casing part 9a and
casing part 9b can be fastened by bonding or welding after they are
fit together. FIG. 8 shows an example in which the casing part 9a
and casing part 9b are bonded together with adhesive. Reference
numeral 22 in FIG. 8 shows where the adhesive is applied.
[0149] It is therefore possible as described above to reliably
assure airtightness between the casing 9 and check valve units 8
(or between casing part 9a and casing part 9b) by thus adhesively
bonding or welding them.
[0150] It is also possible to form female threads and male threads
on the inside circumference of the hole 20 in casing part 9a and
the outside circumference of the protrusion 21 on casing part 9b so
that one can be screwed into the other for fastening. Female
threads and male threads can likewise be formed on the inside
circumference of the check valve housings 18 in casing part 9b and
the outside circumference of the check valve units 8 so that these
can be similarly screwed together and fastened.
[0151] It will also be noted that by threading the check valve
units 8 to the casing 9 or casing part 9b to casing part 9a, the
parts can be easily connected and disconnected.
[0152] (Various Embodiments of the Check Valve Membrane)
[0153] A check valve membrane 5 is used as the member achieving the
check valve function in the first to fourth embodiments described
above, and various embodiments of the check valve membrane 5 are
described next below.
[0154] FIG. 9 shows the part where the check valve membrane 5 is
installed to the check valve unit 8 shown in FIG. 5A. The thin-film
check valve membrane 5 is formed as a rectangular band and is
disposed across so as to cover the channel 6. With the check valve
membrane 5 thus covering the channel 6, the check valve membrane 5
is bonded with adhesive 14 on opposite sides of the channel 6
perpendicular to the longitudinal direction of the check valve
membrane 5.
[0155] When the check valve unit 8 is open, the long sides of the
check valve membrane 5 are lifted as shown in FIG. 10A and FIG.
10B. When the check valve unit 8 is closed, the channel 6 is closed
by the check valve membrane 5 as shown in FIG. 11A and FIG.
11B.
[0156] By thus using a band-shaped check valve membrane 5 the check
valve membrane 5 can be made of the smallest piece of thin film
necessary as a check valve, and less thin film material is
therefore required.
[0157] FIG. 12 shows a variation in which two parallel slitted
vents 13 are formed in the check valve membrane 5 disposed so as to
cover the channel 6. The check valve membrane 5 is then bonded with
adhesive 14 around the vents 13 containing channel 6.
[0158] FIG. 13A and FIG. 13B show the vents 13 in the check valve
membrane 5 shown in FIG. 12 when open, and FIG. 14A and FIG. 14B
show the channel 6 closed by the check valve membrane 5.
[0159] The size of the check valve membrane 5 can be freely
determined with this embodiment so that handling during assembly is
easier and welding is also easier.
[0160] FIG. 15A and FIG. 15B show a rectangular thin film check
valve membrane 5 placed covering the channel 6. A pair of parallel
slitted vents 13 is formed in the check valve membrane 5 on
opposite sides of the channel 6, and the check valve membrane 5 is
bonded with adhesive 14 completely encircling the vents 13.
[0161] As shown in FIG. 15B, the check valve membrane 5 lifts up so
that a horizontal semi-cylinder is formed between the two vents 13
when the vents 13 of the check valve membrane 5 open.
[0162] This embodiment assures that the check valve operates
reliably with a simple configuration, and does not require high
precision positioning of the check valve membrane 5.
[0163] It is also possible as shown in FIG. 16A to form a single
slitted vent 13 in the check valve membrane 5 at a point separated
from the channel 6. This vent 13 extends parallel to a tangent to
the outside circumference of the channel 6, and the check valve
membrane 5 is fixed to the check valve body 7 with adhesive 14
completely encircling the vent 13.
[0164] When the vent 13 of this check valve membrane 5 opens, the
check valve membrane 5 is displaced upward from the vent 13 in the
check valve membrane 5 across the channel 6 as shown in FIG.
16B.
[0165] This configuration is resistant to leaks even when the
distance from the channel 6 to the opening of the vent 13 is
short.
[0166] Multiple vents 13 can also be formed in the check valve
membrane 5 as shown in FIG. 17A. More specifically, the rectangular
thin film check valve membrane 5 is placed so as to cover the
channel 6, and multiple (three in this example) slitted vents 13
parallel to tangents to the outside circumference of the channel 6
are formed at positions apart from the outside circumference of the
channel 6 and circumferentially to the channel 6. The check valve
membrane 5 is fixed with adhesive 14 completely encircling the
vents 13.
[0167] FIG. 17B shows the vents 13 of this check valve membrane 5
when open.
[0168] Wrinkles do not easily form in the check valve membrane 5
because the vents 13 are formed equidistantly in the
circumferential direction to the channel 6 and the adhesive 14 is
located on a circle centered on the channel 6.
[0169] The corners of the vents 13 in the check valve membrane 5
must be curved. If the vents 13 have sharp corners such as in a
square, the corners can tear easily when tension is applied to the
check valve membrane 5. If the corners of the vents 13 are round or
nearly round, however, tension tears in the check valve membrane 5
care be prevented. More specifically, the vents formed in the check
valve membrane are preferably continuous curves.
[0170] FIG. 18 shows an embodiment in which the rectangular thin
film check valve membrane 5 is placed so as to cover the channel 6
with an openable side of the check valve membrane 5 proximal to the
channel 6. The check valve membrane 5 is then fixed with a U-shaped
adhesive bead 14 encircling the channel 6 except on this one
openable side.
[0171] This check valve membrane 5 opens on only one side as shown
in FIG. 19A and FIG. 19B, and the channel 6 is closed by the check
valve membrane 5 as shown in FIG. 20A and FIG. 20B.
[0172] This embodiment provides a check valve with a very simple
configuration, and leaks cannot occur easily.
[0173] As shown in FIG. 21 it is also possible to place the check
valve membrane 5 covering the channel 6 and spot bond the check
valve membrane 5 around the channel 6 with adhesive bead 14 so that
the spaces between the adhesive beads 14 function as vents. In the
example shown in FIG. 21 note that the three adhesive spots are
spaced at equal intervals in the circumferential direction around
the check valve membrane 5.
[0174] This check valve membrane 5 opens on three sides except the
adhesive spots as shown in FIG. 22A and FIG. 22B, and the channel 6
is closed by the check valve membrane 5 as shown in FIG. 23A and
FIG. 23B.
[0175] Wrinkles do not occur easily with this check valve membrane
5 because the adhesive bead 14 is in a circumference around the
channel 6.
[0176] As shown in FIG. 24, the check valve membrane 5 could yet
further alternatively be substantially polygonal in shape, covering
the channel 6 with adhesive bead 14 placed at each corner of the
membrane. The spaces between the adhesive beads 14 become vents in
this case.
[0177] In the example shown in FIG. 24 the thin film check valve
membrane 5 is shaped as a triangle as an example of one polygon. As
shown in FIG. 25A and FIG. 25B, the check valve opens when the
three straight sides of the check valve membrane 5 balloon up, and
the channel 6 is closed when the check valve membrane 5 settles
down as shown in FIG. 26A and FIG. 26B.
[0178] The adhesive beads 14 of this check valve membrane 5 are
also located concentrically to the channel 6, thus preventing
wrinkles in the check valve membrane 5. Because they are straight,
the opening edges of the check valve membrane 5 also do not curl
up.
[0179] As shown in FIG. 27A, a flap 5b can be formed in the check
valve membrane 5 by arcuatedly cutting the thin film. The check
valve membrane 5 is then placed with the flap 5b covering the
channel 6, and is bonded with adhesive 14 encircling the channel 6
and the cut-out part 5a. The substantially semicircular flap 5b
inside the cut-out part 5a thus functions as a valve membrane.
[0180] With this check valve membrane 5 the flap 5b functions as
the valving element and flaps up and down to open and close the
channel 6 as shown in FIG. 27B.
[0181] This variation of the check valve membrane 5 is extremely
simple, does not require high precision positioning, and reduces
pressure loss due to the tension of the valve membrane because it
opens and closes the channel 6 using the flexural modulus of the
valve membrane.
[0182] As shown in FIG. 28A and FIG. 28B, the channel 6 in this
case preferably has plural (three in this example) equidistantly
spaced arc-shaped openings 6a with a support 6b for supporting the
flap 5b in the center of the plural openings 6a .
[0183] When the channel 6 is shaped as shown in FIG. 27 and the
flap 5b (valving element) closes, the center of the flap 5b
occluding the channel 6 is pulled down into the channel 6. When a
support 6b positioned at the center of the flap 5b is provided as
shown in FIG. 28A and FIG. 28B, however, the center of the flap 5b
is not pulled into the channel 6 when the flap 5b closes. This
check valve membrane 5 configuration is therefore more resistant to
fluid leaks and enables an even higher pressure to be used.
[0184] It will also be obvious that the shape of the openings 6a
shall not be limited to an arc, and could be circular, elliptical,
or other shape.
[0185] It will also be noted that the configuration of the channel
6 shown in FIG. 28A and FIG. 28B can also be applied to the other
check valve membranes 5 described above.
[0186] As shown in FIG. 29A, the thin film check valve membrane 5
could also have a band (rectangular) shape placed covering the
channel 6 and then bonded with adhesive 14 perpendicular to the
long side at only one end of the check valve membrane 5.
[0187] The rectangular flap 5b thus disposed over the channel 6
operates as the valving element in this configuration, and the
channel 6 opens and closes as the flap 5b moves up and down as
shown in FIG. 29B.
[0188] This variation of the check valve membrane 5 is also
extremely simple, does not require high precision positioning, and
reduces pressure loss due to valve membrane tension because it
opens and closes the channel 6 using the flexural modulus of the
valve membrane.
[0189] (Various Embodiments of the Check Valve Unit)
[0190] The check valve body 7 shown in FIG. 30 to FIG. 32 is formed
by first and second spacers 7a, 7b. The check valve membrane 5 is
inserted between the first and second spacers 7a, 7b, which are fit
together to fix the check valve membrane 5. The vents of the check
valve membrane 5 can be as in any of the variations described
above, and further description thereof is thus omitted here.
[0191] If the nominal inside diameter of the fitting recess in the
first spacer 7a and the outside diameter of the fitting protrusion
of the second spacer 7b is 4 mm and the thickness of the check
valve membrane 5 is 0.002 mm, the inside diameter tolerance of the
recess in the first spacer 7a is +0.02 mm to +0.01 mm, and the
outside diameter tolerance of the second spacer 7b protrusion is
-0.01 mm to -0.02 mm, the first and second spacers 7a, 7b can be
easily joined by interference fitting.
[0192] It will also be obvious that instead of interference fitting
the check valve membrane 5 could be disposed between the first
spacer 7a and second spacer 7b and the entire perimeters of the
first spacer 7a and second spacer 7b are then bonded.
[0193] As shown in FIG. 33 to FIG. 35, the check valve membrane 5
can alternatively be reliably joined to the check valve body 7 by
placing the thin film check valve membrane 5 on top of the check
valve body 7 and then welding the check valve membrane 5 around the
outside edge of the check valve body 7 with a welding bead as shown
in FIG. 34 and FIG. 35.
[0194] It is yet further possible, as shown in FIG. 36 to FIG. 38,
to form the check valve body 7 with a first spacer 7a and second
spacer 7b, dispose the thin film check valve membrane 5 between the
first spacer 7a and second spacer 7b, and weld the first spacer 7a,
second spacer 7b, and check valve membrane 5 around the entire
outside perimeter. Welding damage to the check valve membrane 5 is
less likely with this method because the three layers are welded at
a time.
[0195] (Manufacture of Piezoelectric Pump)
[0196] A piezoelectric pump according to the present invention can
be easily manufactured as follows. One or more vents 13 are first
formed in the thin film, or the check valve membrane 5 is formed by
processing a thin film to the desired configuration. The channel 6
that will be opened and closed by the check valve membrane 5 is
also formed in the check valve body 7. The check valve membrane 5
is then placed covering the channel 6 and joined to the check valve
body 7 by various methods such as described above to form the check
valve unit 8. The check valve unit 8 is then installed to the
casing 9 between the pump chamber 1 and inlet and outlet channels
2, 3. The one or more vents 13 can thus be easily formed in a thin
film.
[0197] The vents 13 can also be formed in the check valve membrane
5 after joining the check valve membrane 5 and check valve body 7
to form the check valve unit 8. This method completely eliminates
the need to position the check valve membrane 5 for installation,
and enables the vents 13 to be formed appropriately to the desired
locations.
[0198] The vents 13 can be formed in a thin film 4 (blank of the
check valve membrane 5) using an excimer laser as shown in FIG.
39.
[0199] When the check valve body 7 is formed with a first spacer 7a
and second spacer 7b as shown in FIG. 39 and an excimer laser or
other laser is used, the first spacer 7a is preferably made of a
transparent polycarbonate resin and the second spacer 7b is made of
a black polycarbonate resin, for example. Before the vent 13 is
formed in this example the thin film 4 is disposed between the
first spacer 7a and second spacer 7b, joined with adhesive 14, and
the check valve unit 8 is assembled. A laser beam 27 is then
emitted from the laser device 28 to form a vent 13.
[0200] Wrinkles caused by process heat do not occur and the thin
film 4 can be precision processed by thus using an excimer laser or
other type of laser to form the vents 13. Damage (laser marks) from
post-processing to the check valve body 7 is also less likely to
occur.
[0201] Alternatively, a check valve membrane made of a flexible
thin film 4 is placed on the check valve body 7 covering the
channel 6 as shown in FIG. 40. A glass plate 16 is then placed over
the thin film 4 as shown in FIG. 41 to press the thin film 4 to the
check valve body 7 while emitting a laser to form a weld 25.
[0202] By thus holding the thin film 4 tight to the check valve
body 7 while welding the thin film 4 to the check valve body 7, the
thin film 4 can be reliably welded without producing any wrinkles,
and airtightness can be improved.
[0203] When welding with a laser, an iris 17 with a specific
aperture or other opening can be used as shown in FIG. 42 to
simultaneously emit the laser beam 27 to a specific place and
thereby integrally bond the first spacer 7a, thin film 4, and
second spacer 7b. In the example shown in FIG. 42 two irises 17
each with a specific aperture are installed stacked together in the
laser device 28, and the laser beam 27 is emitted simultaneously to
a specific circle around the first spacer 7a, thin film 4, and
second spacer 7b, thus a weld 25 is formed. A YAG laser is used for
the laser device 28 in this example, and sample laser emission
conditions are shown in Table 1.
1 TABLE 1 Acrylic Polycarbonate Power 0.56 J/shot 0.24 J/shot
Number of shots 5 5
[0204] When the entire perimeter is welded simultaneously, the
effects of the welding heat can be lessened.
(EXAMPLE)
[0205] A diaphragm pump according to the present invention can be
manufactured as described below. FIG. 43A shows the assembled
diaphragm pump, and FIG. 43B is an exploded perspective view of the
diaphragm pump.
[0206] The drive voltage, drive frequency, maximum pressure, and
flow of this diaphragm pump are as follow.
2 Drive voltage: -100, 400 V Drive frequency: 100 Hz (square wave)
Maximum pressure: 450 hPa Flow: 85 ml/min
[0207] This diaphragm pump is made up of a disc-shaped diaphragm
12, disc-shaped casing 9, and check valve units 8. The diaphragm 12
is placed on top of the casing 9 and the edge of the diaphragm 12
is bonded to the top of the casing 9 to form a pump chamber.
[0208] The casing 9 is formed from a casing part 9a and a separate
casing part 9b. The one casing part 9a is annularly shaped with a
hole 20 in the center. The other casing part 9b is disc-shaped with
a protrusion 21 on top. The protrusion 21 of this casing part 9b is
fit to the hole 20 in casing part 9a to integrate casing part 9a
and casing part 9b. The diaphragm 12 is disposed on top of casing
part 9a and integrated with the casing part 9a by bonding the edge
of the diaphragm 12 to the top of the casing part 9a. Check valve
housings 18 are formed in casing part 9b, and the check valve units
8 are installed to these check valve housings 18.
[0209] The check valve body 7 is made up of a first spacer 7a and
second spacer 7b, which are disc shaped members identical in
thickness and outside diameter. The first spacer 7a is made of a
transparent polycarbonate resin, the second spacer 7b is made of a
black polycarbonate resin, and the check valve membrane 5 is made
of a transparent polycarbonate resin. The check valve unit 8 is
assembled by placing the check valve membrane 5 between the first
spacer 7a and second spacer 7b and then joining the first spacer 7a
and second spacer 7b.
[0210] The diaphragm 12 is made of a thin metal plate 11 and
piezoelectric actuator 10. The piezoelectric actuator 10 is a PZT
element 20 mm in diameter and 0.25 mm thick. The thin metal plate
11 is preferably brass, 20.2 mm in diameter and 0.05 mm thick.
Electrodes of the PZT element are silver and 18 mm in diameter.
[0211] The check valve membrane 5 is made of a polycarbonate film
0.002 mm thick. This check valve membrane 5 is disposed between the
first spacer 7a and second spacer 7b of the check valve body 7, and
the check valve unit 8 is assembled by integrally welding the check
valve membrane 5, first spacer 7a, and second spacer 7b with a weld
25.
[0212] As shown in FIG. 44A, the height of the check valve unit 8
is 1.6 mm, the outside diameter of the check valve unit 8 is 5.5
mm, and the fitting tolerance is -0.004 mm to -0.012 mm, for
example.
[0213] The diameter of the space 19 into which the check valve
membrane 5 displaces is 2.8 mm as shown in FIG. 44B, and the
diameter of the channel 6 is 1 mm. The suction side and discharge
side of this check valve unit 8 are identically configured, and the
orientation of the check valve unit 8 is simply inverted on the
suction and discharge sides.
[0214] FIG. 44C shows the operation of this check valve. The vents
13 are 1 mm long, the gap between the pair of vents 13 is 2 mm, and
the vents 13 are 0.3 mm wide.
[0215] Casing part 9a of this casing 9 is made of PPA resin, and
casing part 9b is made of transparent acrylic resin. The outside
diameter of casing part 9a of casing 9 is 22 mm, the inside
diameter is 13 mm, the fitting tolerance is +0.018 mm to 0 mm, for
example, and the thickness is 1 mm. The outside diameter of casing
part 9b of casing 9 is 15 mm and the thickness is 2 mm. The outside
diameter of the protrusion 21 of casing part 9b is 13 mm, and the
fitting tolerance is -0.006 mm to -0.017 mm, for example. The
inside diameter of the check valve housing 18 is 5.5 mm, the
fitting tolerance is +0.012 mm to 0 mm, for example, and the depth
is 1.6 mm.
[0216] A YAG laser is used to integrally weld the first spacer 7a,
second spacer 7b, and check valve membrane 5 with a weld 25, which
as shown in FIG. 45A completely encircles the space 19. The vents
13 are formed using an excimer laser as shown in FIG. 45B.
[0217] Although the present invention has been fully described by
way of examples with reference to the accompanying drawings, it is
to be noted here that various changes and modifications will be
apparent to those skilled in the art. Therefore, unless such
changes and modifications otherwise depart from the spirit and
scope of the present invention, they should be construed as being
included therein.
* * * * *