JP2014013019A - Piezo fan - Google Patents

Abstract

A flow rate and a flow rate of an air flow generated by a blade that vibrates due to a piezoelectric effect are sufficiently increased.
A pair of blades 2 and 3 whose phases of membrane vibration are shifted from each other are opposed to each other with a predetermined interval and their peripheral portions are connected and held. Sealing materials 6a, 6b, 6c are interposed so that an opening 7 is formed at a predetermined position between the peripheral portions, and the pair of blades 2, 3 are further connected to the outer surfaces of the blades 2, 3. Between the upper plate portion 8 and the outer surface of one blade 2 facing the upper plate portion 8 and the lower plate portion 9. In addition, each of the space between the lower plate portion 9 and the outer surface of the other blade 3 facing the lower plate portion 9 is a space portion in which an opening portion 7A is formed at a predetermined position.
[Selection] Figure 1

Description

  The present invention relates to a piezo fan in which an air flow is generated by vibrating a blower blade by a piezo element that is deformed by applying a voltage.

  The piezoelectric element generates an electromotive force according to a stress caused by an external force, and deforms when a voltage is applied on the contrary. 2. Description of the Related Art Conventionally, a fan configured to drive a diaphragm using such a piezoelectric effect (piezo effect) to blow air is known. Examples thereof are described in Patent Documents 1 to 4, and among these documents, the piezoelectric fan described in Patent Documents 1 to 3 includes an elastic body having one end sandwiched between a pair of piezoelectric elements, The diaphragm is connected to the other end of the elastic body, and a case that accommodates the piezoelectric element, the elastic body, and the diaphragm and is formed with an air inlet and outlet. In the piezoelectric fan configured as described above, when an alternating current with a phase shift is applied to each piezoelectric element, the elastic body vibrates and the vibration of the elastic body is transmitted to the vibration plate. It can be moved to generate an air flow by the so-called fan principle. Therefore, the cooling devices described in Patent Documents 1 to 3 can have a thickness that allows the diaphragm to vibrate.

  In addition, the fan described in Patent Document 4 has a piezoelectric ceramic bonded to the upper surface of the diaphragm, accommodates the blades to which vibrations of the diaphragm are transmitted, the diaphragm and the blades, and an air suction port. And a case in which a discharge port is formed. In the fan configured in this manner, when an alternating current is applied to the piezoelectric element, the piezoelectric ceramic repeatedly contracts and expands, and the diaphragm and blades to which the piezoelectric ceramic is bonded vibrate. An air flow can be generated. Therefore, similarly to the piezoelectric fan described in Patent Documents 1 to 3, the fan described in Patent Document 4 can also have a thickness that allows the diaphragm to vibrate.

JP 2002-130198 A JP 2002-130199 A JP 2002-339900 A JP 2002-364599 A

  Conventionally, a fan using a piezoelectric element reciprocates a single vibration plate in the air and stirs the air around the vibration plate as described in each of Patent Documents 1 to 4 above. At the same time, a pushing force in a predetermined direction is applied to the air during stirring. It is comprised so that it may blow on the principle of what is called a fan. When the behavior of the diaphragm (or blade) and the surrounding air is further examined, the density and weight of air is much smaller than that of the diaphragm, so that the surrounding air is displaced by the movement of the diaphragm. Move. If the diaphragm is reciprocated at its free end with its one end as a fulcrum and the other end as a free end, air is pushed in a certain direction by bending around the fulcrum of the diaphragm. As a result, the air can be made an air flow rather than simply stirring.

  However, the air flow generated in this way is generated by the air in the open space being pushed away by the diaphragm, and the action of pressurizing the air hardly occurs. Such a situation is the same even when the diaphragm or blade is arranged inside the case as described in Patent Documents 1 to 4, and those cases are released in a plurality of directions. Therefore, there is no function to restrict or confine air movement. Since the conventional fan using the piezoelectric effect does not pressurize air for blowing air, the air flow velocity and the air flow reach distance are not always sufficiently large. It has been difficult to sufficiently air-cool electronic components mounted inside.

  The present invention has been made paying attention to the above technical problem, and aims to sufficiently increase the flow velocity and flow rate of an air flow by a piezo fan that uses a piezoelectric effect to generate an air amount by vibrating a blade. It is what.

  In order to achieve the above object, the invention of claim 1 is directed to a piezo fan in which an air flow is generated by a blade that vibrates due to a piezoelectric effect. A sealant is interposed between the peripheral portions of these blades so as to be opposed to each other with a space therebetween and to be held at a predetermined position between the peripheral portions of these blades. The pair of blades are accommodated inside a cover member having an upper plate portion and a lower plate portion facing the outer surface of the blades at a predetermined interval, and the upper plate portion and one of the blades facing the upper plate portion Each space between the outer surface of the blade and between the lower plate portion and the outer surface of the other blade opposite to the lower plate portion is a space portion in which an opening is formed at a predetermined position. It is an feature.

  According to a second aspect of the present invention, in the first aspect of the invention, the pair of blades are disposed inside a frame member having a shape surrounding an outer peripheral side excluding an opening between the blades, and a plurality of outer peripheral portions are arranged. The piezo fan is characterized in that it is connected to the frame member at a location, and the cover member is attached to the frame member.

  Furthermore, a third aspect of the present invention is the piezoelectric fan according to the first or second aspect, wherein each of the blades is configured by attaching a piezoelectric element to a metal plate.

  According to the present invention, the pair of blades vibrate in a film due to the piezoelectric effect, the vibrations are out of phase, and vibrate so as to approach and separate from each other. That is, since the space | interval of blades changes repeatedly widely, the volume of the space part between blades increases / decreases repeatedly. The blades are connected to each other at the periphery thereof, and a sealing material is interposed between the blades so that an opening is formed at a predetermined position, and other than the opening is closed in an airtight state. ing. That is, the space between the blades is not an open space, but has a closed structure. Therefore, in the space between the blades, there is an effect of pressurizing and depressurizing the air in the interior due to the change in volume accompanying the membrane vibration of the blade. Since the pressurized air is blown out from the opening, the pressure is high, and a large amount of air is sent out from the opening, so that air flow with a sufficiently high flow rate and flow rate can be performed.

  Further, when the blades approach each other and the volume of the inner space portion decreases, the volume of the space portion between the outer surface of each blade and the upper plate portion and the lower plate portion of the cover member increases, and On the contrary, when the blades are separated from each other and the volume of the space portion inside thereof is increased, the volume of the space portion between the outer surface of each blade and the upper plate portion and the lower plate portion of the cover member is decreased. That is, between each blade and the upper plate portion or the lower plate portion, a change in volume between the blades and accompanying air pressurization and suction occur. Thus, in the present invention, air can be pressurized and sucked at a total of three locations between the blades and on the upper and lower sides of the pair of blades, so that the amount of air blow can be increased.

It is a figure for demonstrating an example of the cooling device which concerns on this invention, (a) is a top view, (b) is sectional drawing which follows the bb line in (a). It is a figure for demonstrating an example of a structure of the fan in FIG. 1, (a) is a perspective view, (b) is a top view, (c) is sectional drawing which follows the cc line in (b). It is sectional drawing for demonstrating the effect | action of the fan, and is a figure which shows the state which is discharging | emitting air from a fan. It is sectional drawing for demonstrating the effect | action of the fan, and is a figure which shows the state which is inhaling air to the fan. It is a figure for demonstrating the structure which connects the fan and frame member in FIG. It is a figure which shows the state which the cooling device is discharging | emitting air toward the cooling object, (a) is a top view, (b) is sectional drawing which follows the bb line of (a). It is sectional drawing for demonstrating the other structural example which connects a fan and a cover member. It is sectional drawing for demonstrating the other structural example which connects a cover member and a frame member. It is a figure for demonstrating the example which a cooling device produces a forced convection in the position different from a heat-emitting part, (a) is a side view, (b) is a top view.

  Next, the piezofan according to the present invention will be specifically described. The piezo fan according to the present invention includes a drive unit composed of a pair of blades that are deformed according to a voltage applied to the piezoelectric element, and a cover member that houses the drive unit. First, the configuration of the drive unit will be described. The drive unit 1 shown in FIG. 2 includes a pair of blades 2 and 3 disposed opposite to each other, piezoelectric elements 4 and 5 provided on the outer surfaces of the blades 2 and 3, and peripheral edges of the blades 2 and 3. It is comprised by the sealing members 6a, 6b, 6c formed by resin materials, such as a silicon | silicone provided in part 2a, 2b, 2c (3a, 3b, 3c). In the drive unit 1 configured as described above, when the voltage is applied and the piezoelectric elements 4 and 5 are deformed, the blade 2 (3) to which the piezoelectric element 4 (5) is closely attached expands and contracts.

  That is, each of the piezoelectric elements 4 and 5 has a deformation in which the surface in close contact with the blades 2 and 3 extends and a deformation in which the surface in close contact with the blades 2 and 3 contracts depending on the polarity of the applied voltage. Is configured to occur. A voltage is applied to each of the piezoelectric elements 4 and 5 such that the close contact surfaces with respect to the blades 2 and 3 extend together and the close contact surfaces contract together. Since these blades 2 and 3 are connected at their peripheral portions and are constrained at the peripheral portions, and the piezoelectric elements 4 and 5 are attached to the central portion, the deformation of the piezoelectric elements 4 and 5 as described above. As a result, the blades 2 and 3 are deformed to approach each other and to be separated from each other. That is, by applying a high-frequency voltage, each blade 2, 3 vibrates and the phase of the vibration is shifted, so that each blade 2, 3 approaches each other and the space volume between them decreases, Further, the space volume between the two is increased while being separated from each other.

  Each of the blades 2 and 3 may be a thin metal plate such as stainless steel or aluminum, and the piezoelectric elements 4 and 5 may be formed by sandwiching a member such as crystal or ceramic as in the conventional art. It is configured to contract and expand when it is provided and the electrode is energized.

  Further, the blades 2 and 3 are connected by seal members 6a, 6b, and 6c so that a predetermined gap is provided between the blades 2 and 3. In the example shown in FIG. 2, seal members 6a, 6b, 6c having a circular cross-sectional shape are sandwiched between three peripheral portions 2a, 2b, 2c (3a, 3b, 3c) of the blades 2, 3. Yes. This is to prevent the sealing members 6a, 6b and 6c from inhibiting the expansion and contraction of the blades 2 and 3, and to make the space between the blades 2 and 3 airtight. The sealing members 6a, 6b and 6c are preferably formed of a resin material such as rubber having a small elastic coefficient so as not to inhibit the blades 2 and 3 from expanding and contracting. By providing the seal members 6a, 6b, and 6c as described above, the blades 2 and 3 and the seal members 6a, 6b, and 6c facing each other form a space S that is opened only on one side. By expanding and contracting, air is sucked into and discharged from the space S through the opening 7 opened only on one side.

  A power source (not shown) is electrically connected to each of the piezoelectric elements 4 and 5 described above, and an electronic control unit (not shown) for controlling the intensity and frequency of the electric field applied to the piezoelectric elements 4 and 5 from the power source is provided. ing. Specifically, one electrode is connected to each of the piezoelectric elements 4 and 5, and the other electrode is connected to each blade 2 and 3 to which the piezoelectric elements 4 and 5 are attached. By changing the voltage and frequency applied to the piezoelectric elements 4 and 5 by this electronic control device, the displacement amount of the contraction / expansion of each piezoelectric element 4 or 5 is controlled, or the displacement frequency, that is, the piezoelectric element 4 or 5 is controlled. The frequency at which 5 vibrates can be controlled. In addition, since the same electrode is connected to each of the piezoelectric elements 4 and 5, the piezoelectric elements 4 and 5 and the piezoelectric elements 4 and 5 are controlled without controlling the phase of the frequency applied to the piezoelectric elements 4 and 5. The blades 2 and 3 to which 5 is attached can be contracted and expanded simultaneously.

  Here, the effect | action of the drive part 1 mentioned above is demonstrated. First, an alternating current is supplied from a power source electrically connected to each of the piezoelectric elements 4 and 5. The voltage and frequency of the alternating current can be arbitrarily determined based on the flow rate or flow velocity of the air flow to be generated. Next, the piezoelectric elements 4 and 5 contract and expand according to the energized power. In other words, the piezoelectric elements 4 and 5 vibrate according to the frequency of the alternating current supplied to the piezoelectric elements 4 and 5. Further, since the piezoelectric elements 4 and 5 are attached to the outer surfaces of the blades 2 and 3 as described above, the blades 2 and 3 vibrate integrally with the piezoelectric elements 4 and 5.

  The drive unit 1 shown in FIG. 1 generates an air flow by compressing and expanding the air intervening in the space S by the expansion and contraction of the blades 2 and 3. For this reason, each of the piezoelectric elements 4 and 5 described above. The phase of the vibration frequency between the blades 2 and 3 is controlled so that the blades 2 and 3 are separated from each other or approach each other. That is, in the example shown in FIG. 1, by connecting the same electrode to each piezoelectric element 4, 5, both piezoelectric elements 4, 5 contract simultaneously, or both piezoelectric elements 4, 5 expand simultaneously. As described above, the electrodes connected to the piezoelectric elements 4 and 5 are controlled so as to pass a current in the same direction.

  3 and 4 show a state in which the blades 2 and 3 are vibrating. FIG. 3 shows that the blades 2 and 3 are deformed in the direction in which the blades 2 and 3 approach each other, so that air is discharged from the space S. FIG. 4 shows a state in which air is sucked into the space S by deformation in a direction in which the blades 2 and 3 are separated from each other. 3 and 4 show the cross section of the seal member 6b in a straight line for convenience. Further, instead of using a plurality of linear seal members, a single seal member may be bent according to the shape of the peripheral portion of the blade.

  The piezoelectric elements 4 and 5 and the electrodes connected to the blades 2 and 3, that is, the cover members 8 and 9 for protecting the drive unit 1 from external force or holding the blades 2 and 3 are shown in FIG. It is provided as shown. These cover members 8 and 9 are members corresponding to the upper plate portion and the lower plate portion in the present invention, and are attached to the frame member 10 holding the drive unit 1 described above. The drive unit 1 in the example described here is formed in a rectangular shape, and the opening 7 described above is formed in one side edge portion thereof. The frame member 10 is a frame body that covers the outer peripheral side of the drive unit 1 excluding the opening 7. In the example shown in the figure, the frame member 10 is configured to have a “U” shape in plan view. The drive unit 1 or the pair of blades 2 and 3 described above is inserted into the frame member 10 and the frame 3 is connected to the frame by the connecting member 11 such as a tab in a state where the three outer sides are slightly separated from the frame member 10. The member 10 is connected and held.

  As shown in FIG. 1A, the upper and lower portions of the blades 2 and 3 are surrounded by cover members 8 and 9 disposed on both sides of the front and back of the peripheral portion of the frame member 10. That is, the cover members 8 and 9 are arranged on both the front and back sides of the drive unit 1, and the three peripheral portions of the cover members 8 and 9 are connected by rivets 12 or the like as shown in FIG. . Therefore, an opening 7 </ b> A is formed by the cover members 8, 9 at locations around the cover members 8, 9 that coincide with the opening 7 described above. In addition, although the hole 13 for taking out the lead wire connected to the electrode to the exterior of the cover members 8 and 9 is formed, the cooling device shown in FIG. The space 13 is also configured to discharge air, and in order to suppress or prevent air from leaking from a portion other than the portion opened to the outside, the hole 13 has the cover members 8 and 9 formed by the frame member 10. The part which overlaps with is preferable.

  Thus, the cover members 8 and 9 protect the drive unit 1, and a predetermined gap is provided between the front and back both sides of the drive unit 1, that is, between the blades 2 and 3 and the inner wall surfaces of the cover members 8 and 9. Therefore, when the blades 2 and 3 are deformed in a direction approaching each other, the air interposed between the blades 2 and 3 is pressurized and discharged, and at the same time, the outer surface of the blades 2 and 3 and the cover members The volume of the space between 8 and 9 increases, and air is sucked into the space portion from the opening 7A. Further, when the blades 2 and 3 are deformed in the direction away from each other, the space volume between the blades 2 and 3 is increased and the pressure is reduced. The air interposed between the cover members 8 and 9 is pressurized and discharged from the opening 7A.

  Thus, in the piezo fan according to the present invention, the blowing of air from the space between the blades 2 and 3 and the suction of air between the blades 2 and 3 and the cover members 8 and 9 are simultaneously performed. In addition, the suction of air into the space between the blades 2 and 3 and the blowing of air from the space between the blades 2 and 3 and the cover members 8 and 9 occur simultaneously. Therefore, there are air blowing or suction from the space between the blades 2 and 3 and air suction or air blowing into the space between the blades 2 and 3 and the cover members 8 and 9. By preventing the interference, the air flow can be continuously blown out. When used as a fan for forced air cooling, the cooling air volume can be increased to improve the cooling capacity or the cooling efficiency.

  FIG. 6 shows a state in which air is blown from the piezo fan toward the upper surface of the heat spreader 15 integrated on the upper surface of the chip set 14 with the chip set 14 as an object to be cooled. Further, the above-described piezofan can cause forced convection by contraction and expansion of the piezoelectric elements 4 and 5, and the displacement amount of the thickness of the piezofan expands the piezoelectric elements 4 and 5 to the maximum. It is a range. That is, the thickness of the piezo fan is the thickness of the cover members 8 and 9 disposed so as not to come into contact with the piezoelectric elements 4 and 5 when the piezoelectric elements 4 and 5 are expanded to the maximum. As a result, since the thickness of the entire piezo fan can be reduced, it can be used as a device for cooling thin electronic devices such as portable electronic devices.

  In the cooling device according to the present invention, the air that was interposed between the cover members 8 and 9 and the blades 2 and 3 is separated by separating the blades 2 and 3 to which the piezoelectric elements 4 and 5 are attached. Therefore, the blades 2 and 3 do not have to be connected to the frame member 10 via the tabs 11. That is, as shown in FIG. 7, a seal member 16 made of a silicon material is provided on the inner wall surface of the cover members 8 and 9 so that the cover members 8 and 9 and the blades 2 and 3 are connected by the seal member 16. It may be configured. Further, the cover members 8 and 9 may not be connected by the rivet 12. For example, the blades 2 and 3 and the frame member 10 are connected by the tab 12 as shown in FIG. The cover members 8 and 9 may be connected to each other via a seal member 17 formed of a silicon material.

  Note that the cooling device according to the present invention may not be configured to generate forced convection directly in a heat generating part such as the chipset 14 as described above. FIG. 9 shows an example of the configuration. One end of a conventionally known flat plate-type heat pipe 18 is disposed on the upper surface of the heat spreader 15, and a heat sink 19 is provided on the other end of the flat plate-type heat pipe 18. The piezo fan according to the present invention is provided so as to blow air toward the heat sink 19.

  As conventionally known, the flat plate-type heat pipe 18 heats and transfers heat transferred from the heat generating portion to the heat radiating portion as latent heat. Therefore, by constructing as shown in the figure, by generating forced convection by blowing air from the piezo fan according to the present invention toward the heat sink 19 integrally formed in the heat radiating portion, a flat plate type heat The heat radiation performance of the heat radiating part of the pipe 18 can be improved, and as a result, the heat transport efficiency of the flat plate type heat pipe 18 and the cooling efficiency of the heat generating part can be improved. That is, the cooling target of the piezo fan according to the present invention may be a member that generates heat, such as the chip set 14, or may be a member that transfers heat from the heat generating portion, such as the heat sink 19.

  Furthermore, the piezo fan according to the present invention generates forced convection by pressurizing and blowing in or inhaling air existing in the drive unit 1 when the piezoelectric elements 4 and 5 contract and expand. In addition, it is only necessary to blow air between the drive unit 1 and the cover members 8 and 9 while the drive unit 1 sucks air, so that the cover member 8 opened to only one of the objects to be cooled as described above. 9, for example, a configuration in which a supply port and a discharge port are provided in the side wall portions facing each other may be used. That is, a valve that opens when the blades 2 and 3 move away from each other is provided at the air discharge port that opens toward the object to be cooled, and opens when the blades 2 and 3 move toward each other. It is good also as a structure which provided the valve in the air inlet opening opened in the peripheral part on the opposite side to the air exhaust port.

  That is, a valve that opens when the air is discharged from between the drive unit 1 and the cover members 8 and 9 is provided in the air discharge port, and the valve that opens when the air is discharged from the inside of the drive unit 1 is air. You may provide in an inlet. With such a configuration, the air near the object to be cooled is not sucked, that is, high-temperature air is not sucked, and the convection discharged from the inside of the driving unit 1 is covered with the driving unit 1 and the cover. The convection of the air sucked between the members 8 and 9 is not hindered, and as a result, the cooling efficiency can be improved by improving the flow velocity and flow rate of the air discharged toward the cooling target portion. .

  Further, the shapes of the piezoelectric elements 4 and 5 and the blades 2 and 3 or the seal members 6a, 6b and 6c are not limited to the above-described shapes. For example, the piezoelectric elements 4 and 5 may be rectangular. May be circular. Further, in the above-described example, the example in which the piezoelectric elements 4 and 5 are provided on the upper and lower blades 2 and 3 has been described. However, one of the blades 2 (3) is provided with the piezoelectric element 4 (5). It only has to be.

  DESCRIPTION OF SYMBOLS 1 ... Drive part, 2, 3 ... Blade, 2a, 2b, 2c (3a, 3b, 3c) ... Peripheral part, 4, 5, ... Piezoelectric element, 6a, 6b, 6c ... Seal member, 7, 7A ... Opening, 8, 9 ... cover member.

Claims (3)

In a piezo fan that generates an air flow with a blade that vibrates due to the piezoelectric effect,
A pair of the blades whose phases of the membrane vibration are shifted from each other are opposed to each other with a predetermined interval and their peripheral portions are connected and held,
Between the peripheral parts of these blades, a sealing material is interposed so that an opening is generated at a predetermined place,
Further, the pair of blades are accommodated inside a cover member having an upper plate portion and a lower plate portion facing each other with a predetermined interval on the outer surface of the blades,
An opening is provided at a predetermined position between the upper plate and the outer surface of one blade facing the upper plate, and between the lower plate and the outer surface of the other blade facing the blade. A piezo fan characterized by a formed space. The pair of blades are disposed inside a frame member having a shape surrounding an outer peripheral side excluding an opening between the blades, and are connected to the frame member at a plurality of locations on the outer peripheral portion.
The piezo fan according to claim 1, wherein the cover member is attached to the frame member.   3. The piezo fan according to claim 1, wherein each of the blades is configured by attaching a piezoelectric element to a metal plate.

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