U.S. patent application number 14/506721 was filed with the patent office on 2015-01-22 for piezoelectric fan.
The applicant listed for this patent is Murata Manufacturing Co., Ltd.. Invention is credited to Nobuhira TANAKA.
Application Number | 20150023819 14/506721 |
Document ID | / |
Family ID | 49383313 |
Filed Date | 2015-01-22 |
United States Patent
Application |
20150023819 |
Kind Code |
A1 |
TANAKA; Nobuhira |
January 22, 2015 |
PIEZOELECTRIC FAN
Abstract
A piezoelectric fan in which vibration of blades is unaffected
by external noise includes a vibrating plate including blades and a
base. First piezoelectric elements are attached to a side of a
first blade adjacent to the base. Second piezoelectric elements are
attached to a side of a second blade adjacent to the base. Third
piezoelectric elements are attached to a side of a third blade
adjacent to the base. A holder includes a supporting body and a
holding member that sandwich the base therebetween. The holding
member has a supporting portion and main-body fixing portions
including respective main-body fixing holes. The main-body fixing
portions extend from the supporting portion.
Inventors: |
TANAKA; Nobuhira;
(Nagaokakyo-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Murata Manufacturing Co., Ltd. |
Nagaokakyo-shi |
|
JP |
|
|
Family ID: |
49383313 |
Appl. No.: |
14/506721 |
Filed: |
October 6, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2013/057998 |
Mar 21, 2013 |
|
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14506721 |
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Current U.S.
Class: |
417/410.2 |
Current CPC
Class: |
F04D 23/006 20130101;
H01L 41/094 20130101; H01L 2924/0002 20130101; F04D 33/00 20130101;
F04D 25/0606 20130101; H01L 2924/00 20130101; H01L 2924/0002
20130101; H01L 23/467 20130101 |
Class at
Publication: |
417/410.2 |
International
Class: |
F04D 25/06 20060101
F04D025/06; F04D 33/00 20060101 F04D033/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 17, 2012 |
JP |
2012-093524 |
Claims
1. (canceled)
2. A piezoelectric fan comprising: a vibrating plate including a
base having a flat plate shape and a plurality of blades arranged
along the base at predetermined intervals in the longitudinal
direction of the base; a piezoelectric element attached to the
blade; and a holding member having a flat plate shape and including
a supporting portion and a main-body fixing portion, the supporting
portion being configured to support the base; wherein adjacent ones
of the plurality of blades are driven to vibrate in opposite
phases; and the main-body fixing portion of the holding member
extends from the supporting portion and is arranged in a region
which is not overlapped with the base in a plan view.
3. The piezoelectric fan according to claim 2, wherein the
main-body fixing portion is positioned to a blade side compared
with the base in the plan view of the vibrating plate.
4. The piezoelectric fan according to claim 2, wherein the holding
member is made of an insulating material.
5. The piezoelectric fan according to claim 2, wherein the
supporting portion has a shape that is identical or substantially
identical to the base; and the main-body fixing portion is
positioned between the plurality of blades.
6. The piezoelectric fan according to claim 2, wherein the base and
the plurality of blades are integrally configured and defined by a
single unitary member.
7. The piezoelectric fan according to claim 2, wherein a width of
each of plurality of blades varies along a length thereof.
8. The piezoelectric fan according to claim 2, wherein at least two
piezoelectric elements are attached to opposite sides of each of
the plurality of blades.
9. The piezoelectric fan according to claim 2, wherein the base and
the plurality of blades are integrally configured and defined by a
single unitary member.
10. The piezoelectric fan according to claim 2, wherein at least
one piezoelectric element is attached to one side of each of the
plurality of blades.
11. A piezoelectric fan comprising: a vibrating plate including a
base having a flat plate shape and including a plurality of blades
connected to the base at predetermined intervals in the
longitudinal direction of the base; a piezoelectric element
attached to the blade; and a holding member having a flat plate
shape and including a supporting portion having a shape that is
identical or substantially identical to the base and a main-body
fixing portion, the supporting portion being configured to support
the base; wherein adjacent ones of the plurality of blades are
driven to vibrate in opposite phases; and the main-body fixing
portion of the holding member extends from an end surface
positioned between the plurality of blades and in parallel or
substantially in parallel to the longitudinal direction of the
supporting portion.
12. The piezoelectric fan according to claim 11, wherein the
main-body fixing portion is positioned to a blade side compared
with the base in the plan view of the vibrating plate.
13. The piezoelectric fan according to claim 11, wherein the
holding member is made of an insulating material.
14. The piezoelectric fan according to claim 11, wherein the
supporting portion has a shape that is identical or substantially
identical to the base; and the main-body fixing portion is
positioned between the plurality of blades.
15. The piezoelectric fan according to claim 11, wherein the base
and the plurality of blades are integrally configured and defined
by a single unitary member.
16. The piezoelectric fan according to claim 11, wherein a width of
each of plurality of blades varies along a length thereof.
17. The piezoelectric fan according to claim 11, wherein at least
two piezoelectric elements are attached to opposite sides of each
of the plurality of blades.
18. The piezoelectric fan according to claim 11, wherein the base
and the plurality of blades are integrally configured and defined
by a single unitary member.
19. The piezoelectric fan according to claim 11, wherein at least
one piezoelectric element is attached to one side of each of the
plurality of blades.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a piezoelectric fan that
blows air by using a piezoelectric element as a drive source to a
vibrate blade.
[0003] 2. Description of the Related Art
[0004] Conventional piezoelectric fans that use a piezoelectric
element as a drive source are described, for example, in Japanese
Unexamined Patent Application Publication No. 2-33500 and
International Publication No. 2009/119431.
[0005] The piezoelectric fan described in Japanese Unexamined
Patent Application Publication No. 2-33500 includes a vibrating
plate and piezoelectric elements. One end of the vibrating plate is
divided into three blades, whereas the other end of the vibrating
plate is provided with main-body fixing holes. The piezoelectric
elements are attached to the respective blades. The piezoelectric
element on the central blade and the piezoelectric elements on the
right and left blades are polarized in opposite directions. When an
alternating voltage of the same phase is applied to each of the
piezoelectric elements, the central blade and the right and left
blades vibrate in opposite phases. Vibration is suppressed at the
fixed end of the vibrating plate, because vibration of the central
blade and vibration of the right and left blades cancel each other
out. The piezoelectric fan blows air by performing this
operation.
[0006] The piezoelectric fan described in International Publication
No. 2009/119431 includes a vibrating plate, piezoelectric elements,
and a supporting body. The vibrating plate is composed of two
separate blades. The piezoelectric elements are attached to the two
blades in the same manner. The two blades are supported and coupled
to each other in parallel by the supporting body. When alternating
voltages of opposite phases are applied to the two piezoelectric
elements, the piezoelectric fan operates in the same manner as that
described above.
[0007] A piezoelectric fan illustrated in FIG. 6 was devised by the
inventor of the present application using the prior art disclosed
in Japanese Unexamined Patent Application Publication No. 2-33500
and International Publication No. 2009/119431. FIG. 6A is an
external perspective view of a piezoelectric fan 10P, FIG. 6B is a
plan view of the piezoelectric fan 10P, and FIG. 6C is a lateral
view of the piezoelectric fan 10P.
[0008] The piezoelectric fan 10P includes a vibrating plate 11,
piezoelectric elements 121, 122, 123, 131, 132, and 133 and
supporting bodies 141P and 142P. Main-body fixing holes 151 and 152
are provided to secure the main body of the piezoelectric fan 10P,
for example, to a destination housing to which air is supplied.
Note that the piezoelectric elements 131 and 132 are not shown in
FIGS. 6A-6C.
[0009] The vibrating plate 11 is integrally formed by three blades
111, 112, and 113 and a base 110P. The blades 111, 112, and 113 are
arranged in the longitudinal direction of the base 110P in the
following order: the blade 112, the blade 111, and the blade
113.
[0010] The piezoelectric element 121 is attached to one flat
surface of the blade 111, the piezoelectric element 131 is attached
to the other flat surface of the blade 111, the piezoelectric
element 122 is attached to one flat surface of the blade 112, and
the piezoelectric element 132 is attached to the other flat surface
of the blade 112. The piezoelectric element 123 is attached to one
flat surface of the blade 113, and the piezoelectric element 133 is
attached to the other flat surface of the blade 113. The
polarization direction of each piezoelectric element and the
direction of voltage applied to the piezoelectric element are set
such that the central blade 111 and the left and right blades 112
and 113 vibrate in opposite phases. When an alternating voltage is
applied to each piezoelectric element, the piezoelectric fan 10P
operates in the manner described above.
[0011] The supporting bodies 141P and 142P support the vibrating
plate 11 by sandwiching the vibrating plate 11 from both flat sides
of the base 110P.
[0012] The main-body fixing holes 151 and 152 pass through the base
110P and the supporting bodies 141P and 142P. For example, with
screws inserted in the main-body fixing holes 151 and 152, the
piezoelectric fan 10P is attached to a destination housing to which
air is supplied.
[0013] In the piezoelectric fan 10P, the base 110P and the
supporting bodies 141P and 142P are often bonded together by an
adhesive.
[0014] The conventional piezoelectric fan illustrated in FIGS.
6A-6C is secured to an external housing (i.e., a housing to which
the piezoelectric fan is to be attached) by inserting screws into
the main-body fixing holes 151 and 152 as described above. This
causes electrical conduction between the vibrating plate 11 and the
external housing. As a result, noise may propagate through the
external housing to the vibrating plate 11. If noise propagates to
the vibrating plate 11, drive signals for driving the piezoelectric
elements are disturbed by the noise and desired vibration cannot be
obtained.
SUMMARY OF THE INVENTION
[0015] Preferred embodiments of the present invention provide a
piezoelectric fan that prevents electrical conduction between a
vibrating plate and an external housing, and reliably obtains
desired vibration.
[0016] A piezoelectric fan according to a preferred embodiment of
the present invention includes a vibrating plate including a base
and a blade; a piezoelectric element attached to the blade; and a
holding member including a supporting portion and a main-body
fixing portion, the supporting portion being configured to support
the base. The main-body fixing portion of the holding member
extends from the supporting portion.
[0017] In this configuration, a main-body fixing hole of the
main-body fixing portion is located in an area where the vibrating
plate is not in contact with a supporting body. Therefore, even
when the piezoelectric fan is secured to an external housing with
conductive screws, the vibrating plate and the external housing are
not electrically conducted to each other. It is thus possible to
prevent external noise from propagating to the vibrating plate.
[0018] In a piezoelectric fan according to a preferred embodiment
of the present invention, it is preferable that the blade be
provided in a plurality, and that the main-body fixing portion be
positioned between the plurality of blades.
[0019] In a piezoelectric fan according to a preferred embodiment
of the present invention, the main-body fixing portion is
preferably positioned to a blade side compared with the base in a
plan view of the vibrating plate.
[0020] With this configuration, it is possible to provide a compact
piezoelectric fan while providing the operation and effect
described above. In particular, when the main-body fixing portion
is positioned to the blade side compared with the supporting
portion, it is possible to further reduce the size of the
piezoelectric fan.
[0021] A piezoelectric fan according to a preferred embodiment of
the present invention preferably has the following configuration.
That is, the number of the plurality of blades is preferably three,
for example, and the blades are arranged in a longitudinal
direction of the supporting portion; and the blades at both ends in
the direction of arrangement and the blade at the center in the
direction of arrangement are driven to vibrate in opposite
phases.
[0022] This shows a more concrete configuration of the
piezoelectric fan. With this configuration, vibrations of the
blades cancel each other out at the base and do not propagate to
the outside. In the piezoelectric fan with this configuration,
where a desired drive signal is reliably applied to each blade, the
vibrations reliably cancel each other out.
[0023] In a piezoelectric fan according to a preferred embodiment
of the present invention, the holding member is preferably made of
an insulating material.
[0024] With this configuration, where the holding member is
electrically insulated from the outside, it is possible to prevent
noise from being superimposed on drive signals through the holding
member.
[0025] Various preferred embodiments of the present invention
ensure insulation between the vibrating plate and the external
housing, and to stably obtain desired vibration.
[0026] The above and other elements, features, steps,
characteristics and advantages of the present invention will become
more apparent from the following detailed description of the
preferred embodiments with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIGS. 1A-1D provide an external perspective view, a plan
view, a lateral view, and a cross-sectional view of a piezoelectric
fan 10 according to a first preferred embodiment of the present
invention.
[0028] FIG. 2 illustrates a driving concept of the piezoelectric
fan 10 according to the first preferred embodiment of the present
invention.
[0029] FIG. 3 is a plan view of a holding member 142 according to
the first preferred embodiment of the present invention.
[0030] FIGS. 4A-4C provide an external perspective view, a plan
view, and a lateral view of a piezoelectric fan 10A according to a
second preferred embodiment of the present invention.
[0031] FIGS. 5A-5C provide an external perspective view, a plan
view, and a lateral view of a piezoelectric fan 10B according to a
third preferred embodiment of the present invention.
[0032] FIGS. 6A-6C provide an external perspective view, a plan
view, and a lateral view of a piezoelectric fan 10P according to a
comparative example of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] A piezoelectric fan according to a first preferred
embodiment of the present invention will be described with
reference to the drawings. FIG. 1A is an external perspective view
of a piezoelectric fan 10 according to the first preferred
embodiment of the present invention. FIG. 1B is a plan view of the
piezoelectric fan 10 according to the first preferred embodiment of
the present invention. FIG. 1C is a lateral view of the
piezoelectric fan 10 according to the first preferred embodiment of
the present invention. FIG. 1D is a cross-sectional view taken
along line A-A' of the piezoelectric fan 10 according to the first
preferred embodiment of the present invention. FIG. 2 illustrates a
driving concept of the piezoelectric fan 10 according to the first
preferred embodiment of the present invention. FIG. 3 is a plan
view of a holding member 142 according to the first preferred
embodiment of the present invention.
[0034] The piezoelectric fan 10 includes a vibrating plate 11,
piezoelectric elements 121, 122, 123, 131, 132, and 133, and a
holder 14.
[0035] The vibrating plate 11 is a flat plate including a first
flat surface and a second flat surface opposite each other, and
having a predetermined degree of stiffness. The vibrating plate 11
preferably is, for example, a 0.1-mm-thick stainless steel (SUS)
plate, for example.
[0036] The vibrating plate 11 is integrally configured and defined
by three blades 111, 112, and 113 and a base 110 that are
preferably defined by a single unitary member, for example. The
blades 111, 112, and 113 and the base 110 are long flat plates. The
blades 111, 112, and 113 are arranged along the base 110 at
predetermined intervals in the longitudinal direction of the base
110. The blades 111, 112, and 113 are arranged and connected in the
longitudinal direction of the base 110 in the following order: the
blade 112, the blade 111, and the blade 113. The longitudinal
direction of the blades 111, 112, and 113 is perpendicular or
substantially perpendicular to the longitudinal direction of the
base 110, that is, perpendicular or substantially perpendicular to
the direction of arrangement of the blades 111, 112, and 113.
[0037] End portions of the blades 111, 112, and 113, the end
portions being connected to the base 110, are fixed ends of the
blades 111, 112, and 113. The other end portions of the blades 111,
112, and 113, the other end portions being opposite the fixed ends,
are free ends.
[0038] Widths (i.e., lengths in the short side direction) of the
blades 111, 112, and 113 vary along their longitudinal direction.
Specifically, the widths of the blades 111, 112, and 113 are
shorter at the fixed ends than at the free ends. Thus, in plan view
of the vibrating plate 11 (i.e., as viewed in the direction
perpendicular or substantially perpendicular to the first flat
surface and the second flat surface), a gap having a predetermined
length is provided between the blade 111 and the blade 112, and a
gap having a predetermined length is provided between the blade 111
and the blade 113.
[0039] The blades 112 and 113 at both ends are identical in shape.
The width of the blade 111 at the center in the direction of
arrangement preferably is about twice the width of the blades 112
and 113 at both ends in the direction of arrangement, for
example.
[0040] The piezoelectric element 121 is attached to the first flat
surface of the blade 111. The piezoelectric element 131 is attached
to the second flat surface (i.e., a surface on the opposite side of
the first flat surface) of the blade 111. The piezoelectric element
122 is attached to the first flat surface of the blade 112. The
piezoelectric element 132 is attached to the second flat surface of
the blade 112. The piezoelectric element 123 is attached to the
first flat surface of the blade 113. The piezoelectric element 133
is attached to the second flat surface of the blade 113.
[0041] The piezoelectric elements 121, 122, 123, 131, 132, and 133
are long flat plates. Each piezoelectric element is polarized in
the direction perpendicular or substantially perpendicular to its
flat surfaces. The flat surfaces of each piezoelectric element are
provided with electrodes configured to apply drive signals (not
shown).
[0042] Each piezoelectric element is preferably defined by, for
example, by a piezoelectric body made of PZT ceramics and
electrodes on both principal surfaces of the piezoelectric body.
When the vibrating plate 11 is an electrical conductor, the
electrode on the side of the vibrating plate 11 can be omitted.
[0043] As illustrated in FIG. 2, the polarization direction of the
piezoelectric element 121 is opposite that of the piezoelectric
elements 122 and 123. Also, the polarization direction of the
piezoelectric element 131 is opposite that of the piezoelectric
elements 132 and 133. The polarization direction of the
piezoelectric element 121 is the same as that of the piezoelectric
element 131.
[0044] When an alternating voltage of the same phase is applied to
the piezoelectric elements 121, 122, 123, 131, 132, and 133
polarized as described above, the blade 111 and the blades 112 and
113 vibrate in opposite phases. Vibration is suppressed or
prevented at the fixed end of the vibrating plate, because
vibrations of the blade 111 and the blades 112 and 113 cancel each
other out.
[0045] The holder 14 includes a supporting body 141 and a holding
member 142.
[0046] The supporting body 141 is preferably defined by a long flat
plate substantially identical to the base 110. The supporting body
141 is preferably made of, for example, an insulating material such
as glass epoxy resin. The supporting body 141 is attached to the
first flat surface of the base 110 such that the longitudinal
direction thereof coincides with that of the base 110.
[0047] The holding member 142 is preferably integrally defined by a
supporting portion 160 and main-body fixing portions 161 and 162.
The holding member 142 preferably is made of, for example, an
insulating material such as glass epoxy resin. When the supporting
body 141 and the holding member 142 are each made of an insulating
material, noise from the outside is prevented from being
superimposed on drive signals through the holding member 142. This
significantly reduces or prevents negative effects of noise on
vibration. The operation and effects described above are achieved
as long as at least the main-body fixing portions 161 and 162 of
the holding member 142 are made of an insulating material.
[0048] The supporting portion 160 is preferably defined by a long
flat plate substantially identical to the base 110. The main-body
fixing portions 161 and 162 protrude from an end surface of the
supporting portion 160, the end surface being parallel or
substantially parallel to the longitudinal direction in the flat
surface of the supporting portion 160. The main-body fixing
portions 161 and 162 are spaced apart by substantially the width of
the blade 111. The main-body fixing portions 161 and 162 are
provided with main-body fixing holes 151 and 152, respectively. For
example, with metal screws inserted in the main-body fixing holes
151 and 152, the piezoelectric fan 10 is attached to an external
housing, such as a destination housing to which air is
supplied.
[0049] The holding member 142 is attached to the second flat
surface of the base 110 such that the longitudinal direction of the
supporting portion 160 coincides with that of the base 110. The
main-body fixing portion 161 is positioned in the gap between the
blade 111 and the blade 112, and the main-body fixing portion 162
is positioned in the gap between the blade 111 and the blade
113.
[0050] With this configuration, even when the piezoelectric fan 10
is attached to an external housing by inserting conductive fixing
members, such as screws, into the main-body fixing holes 151 and
152, the vibrating plate 11 and the external housing are not
electrically conducted (short-circuit) through the screws.
Therefore, noise generated in another circuit board included in the
external housing, or noise propagating from outside the housing, is
prevented from propagating to the vibrating plate 11. It is thus
possible to prevent noise from being superimposed on drive signals
to drive the piezoelectric elements 121, 122, 123, 131, 132, and
133, and to stably vibrate the blades 111, 112, and 113 as
desired.
[0051] The holding member 142 is attached to the vibrating plate 11
by bonding the supporting portion 160 and the base 110 together
with an adhesive. Since the main-body fixing holes 151 and 152 are
not provided in the supporting portion 160, there is no possibility
that the main-body fixing holes 151 and 152 will be blocked by the
adhesive. It is thus possible to improve the adhesion between the
supporting portion and the vibrating plate without affecting the
main-body fixing holes.
[0052] In the present preferred embodiment, the main-body fixing
portions 161 and 162 are each positioned in the gap between
adjacent blades. This configuration is preferable because the outer
shape of the piezoelectric fan 10 is kept compact.
[0053] The main-body fixing portions 161 and 162 are preferably
made of, for example, an insulating material such as glass epoxy
resin. Thus, even when the piezoelectric fan 10 is secured with
electrical conductors, such as metal screws, the electrical
conductors and the vibrating plate 11 are electrically insulated by
the main-body fixing portions 161 and 162. This makes it possible
to easily realize a structure in which a desired voltage is
externally applied to the vibrating plate.
[0054] A piezoelectric fan according to a second preferred
embodiment of the present invention will be described with
reference to FIGS. 4A-4C. FIG. 4A is an external perspective view
of a piezoelectric fan 10A according to the second preferred
embodiment of the present invention. FIG. 4B is a plan view of the
piezoelectric fan 10A according to the second preferred embodiment
of the present invention. FIG. 4C is a lateral view of the
piezoelectric fan 10A according to the second preferred embodiment
of the present invention.
[0055] The piezoelectric fan 10A of the second preferred embodiment
preferably has the same configuration as that of the piezoelectric
fan 10 of the first preferred embodiment, except that the
piezoelectric fan 10A does not have the supporting body 141. The
same effects as those in the first preferred embodiment are
achieved in the second preferred embodiment.
[0056] A piezoelectric fan according to a third preferred
embodiment of the present invention will be described with
reference to FIGS. 5A-5C. FIG. 5A is an external perspective view
of a piezoelectric fan 10B according to the third preferred
embodiment of the present invention. FIG. 5B is a plan view of the
piezoelectric fan 10B according to the third preferred embodiment
of the present invention. FIG. 5C is a lateral view of the
piezoelectric fan 10B according to the third preferred embodiment
of the present invention.
[0057] The piezoelectric fan 10B of the third preferred embodiment
includes a holder 14B, instead of the holder 14 of the first
preferred embodiment. The other configuration is preferably the
same as that of the first preferred embodiment. The following
describes differences from the first preferred embodiment. The
holder 14B includes a holding member 142B including main-body
fixing portions 161B and 162B. The main-body fixing portions 161B
and 162B are positioned on the side where the blades 111, 112, and
113 do not protrude from the base 110.
[0058] The shape and the arrangement of the main-body fixing
portions are not limited to those in the preferred embodiments
described above.
[0059] The number of blades included in the vibrating plate is not
limited to that in the preferred embodiments described above.
[0060] Although the piezoelectric elements are preferably made of
PZT ceramics in the preferred embodiments described above, the
material of the piezoelectric elements is not limited to this. For
example, the piezoelectric elements may be made of a piezoelectric
material of lead-free piezoelectric ceramics, such as
potassium-sodium niobate ceramics or alkali niobate ceramics.
[0061] Although the piezoelectric elements are preferably attached
to both flat surfaces of the vibrating plate (bimorph type) in the
preferred embodiments described above, the piezoelectric elements
may be attached to one flat surface of the vibrating plate
(unimorph type).
[0062] While preferred embodiments of the present invention have
been described above, it is to be understood that variations and
modifications will be apparent to those skilled in the art without
departing from the scope and spirit of the present invention. The
scope of the present invention, therefore, is to be determined
solely by the following claims.
* * * * *