WO2009145064A1 - Piezoelectric microblower - Google Patents

Piezoelectric microblower Download PDF

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Publication number
WO2009145064A1
WO2009145064A1 PCT/JP2009/058968 JP2009058968W WO2009145064A1 WO 2009145064 A1 WO2009145064 A1 WO 2009145064A1 JP 2009058968 W JP2009058968 W JP 2009058968W WO 2009145064 A1 WO2009145064 A1 WO 2009145064A1
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WIPO (PCT)
Prior art keywords
opening
portion
blower
wall
central space
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PCT/JP2009/058968
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French (fr)
Japanese (ja)
Inventor
平田 篤彦
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株式会社村田製作所
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Priority to JP2008-142250 priority Critical
Priority to JP2008142250 priority
Application filed by 株式会社村田製作所 filed Critical 株式会社村田製作所
Publication of WO2009145064A1 publication Critical patent/WO2009145064A1/en

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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04BPOSITIVE DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B43/00Machines, pumps, or pumping installations having flexible working members
    • F04B43/02Machines, pumps, or pumping installations having flexible working members having plate-like flexible members, e.g. diaphragms
    • F04B43/04Pumps having electric drive
    • F04B43/043Micropumps

Abstract

A piezoelectric microblower which can efficiently transport a compressible fluid without using a check valve, thereby realizing increase in a flow rate. A blower body (1) is provided with a first wall portion (30) and a second wall portion (10), and opening portions (31, 11) are formed at the positions of the wall portions opposite the center portion of a driving body (50).  Between both of the wall portions, a center space (21) which communicates with the opening portions (31, 11) and flow-in paths (22) which causes the center space (21) to communicate with outside are formed.  At connecting portions of the flow-in paths (22) and the center space (21), restrictions (23) are formed.  When the driving body (50) is vibrated by applying voltage to a piezoelectric element (52), the wall portion (30) resonates to generate a large pressure wave upward from the opening portion (31), and the pressure wave discharges the air within the center space (21) to the outside through the second opening portion (11).  Providing the restrictions (23) reduces the loss of pressure energy, thereby allowing the increase in the flow rate.

Description

Piezoelectric micro blower

The present invention relates to a piezoelectric microblower suitable for transporting a compressible fluid such as air.

Piezoelectric micropumps are used as cooling water transportation pumps for small electronic devices such as notebook computers and fuel transportation pumps for fuel cells. On the other hand, a piezoelectric micro blower can be used as a blower for replacing a cooling fan such as a CPU, or as a blower for supplying oxygen necessary for power generation by a fuel cell. Both the piezoelectric micropump and the piezoelectric microblower are pumps (blowers) that use a diaphragm that bends and deforms when a voltage is applied to the piezoelectric element, and have the advantage of being simple in structure, thin, and having low power consumption. is there.

When transporting incompressible fluids such as liquids, check valves using soft materials such as rubber and resin are provided at the inlet and outlet, respectively, and piezoelectric elements are installed at a low frequency of about several tens of Hz. It is common to drive. When the piezoelectric element is driven in the vicinity of the resonance frequency (primary resonance frequency or tertiary resonance frequency) of the diaphragm, the maximum displacement is obtained, but the check valve cannot follow up because the resonance frequency is a high frequency on the order of kHz. Therefore, a piezoelectric microblower that does not have a check valve is desirable for transporting a compressive fluid.

In Patent Document 1, a base body having a pressurizing chamber filled with a fluid, a nozzle plate having a nozzle provided so as to face the pressurizing chamber, and an opening are provided, and the nozzle is located substantially at the center of the opening. The electrical vibrator is mounted on the nozzle plate, and the nozzle plate and the electrical vibrator are mounted on the substrate, and an AC signal having a frequency near the resonance frequency of the electrical vibrator is applied to the electrical vibrator. There has been proposed a flow generating device adapted to be supplied to the vehicle. In this case, the check valve can be omitted, and the flow rate can be increased by driving the vibrator at a high frequency. In the structure of FIG. 5 of Patent Document 1, an inflow air chamber is provided in front of the nozzle plate, and an air flow ejected from the nozzle is discharged from the discharge port while entraining air in the surrounding air chamber. However, since the opening area of the inflow air chamber is large, the pressure energy of the fluid ejected from the nozzle escapes to the periphery of the inflow air chamber, and there is a drawback that the flow rate from the discharge port does not increase.

Patent Document 2 discloses a micro that includes an injection unit that sucks and injects external air, a cover part in which a discharge port that discharges air injected from the injection unit is formed, and a base unit that is coupled to the injection unit. A blower is disclosed. In FIG. 4 of Patent Document 2, an injection plate having a suction hole and an injection hole is provided, and a diaphragm including a magnetic sheet is attached to the back of the injection plate via a pressurizing chamber. A structure is disclosed in which a jet air current is generated from a cavity by being vibrated by a coil, and air in a cover cavity located in front of the jet plate is entrained and discharged from a discharge port. Also in this structure, since the opening area of the cover cavity is larger than the opening area of the pressurizing chamber, the pressure energy ejected from the injection hole is diffused into the cover cavity as in Patent Document 1, and the flow rate from the discharge port is increased. There is a disadvantage of not.
Japanese Patent Publication No. 64-2793 JP 2005-113918 A

Therefore, an object of the present invention is to provide a piezoelectric micro blower that can efficiently transport a compressive fluid without using a check valve and can realize an increase in flow rate.

In order to achieve the above object, the present invention includes a blower body, a drive body having an outer peripheral portion fixed to the blower body and having a piezoelectric element, and a blower chamber formed between the blower body and the drive body. A piezoelectric micro blower for transporting a compressive fluid by applying a voltage to the piezoelectric element and bending the drive body to form a blower chamber with the drive body. A first opening that is formed in the first wall and communicates the inside and outside of the blower chamber, and the first wall is on the opposite side of the blower chamber with the first wall in between. A second wall portion provided open, a second opening portion formed in the second wall portion, and formed between the first wall portion and the second wall portion; Having an opening area larger than two openings and smaller than the blower chamber, and the first opening and A central space that communicates with the second opening, and an inflow passage having an outer end connected to the outside and an inner end connected to the central space. The inflow passage has a smaller passage area than the inflow passage. Provided is a piezoelectric microblower characterized in that a diaphragm is provided.

When a voltage is applied to the piezoelectric element to cause the driver to bend and vibrate, the fluid is drawn from the inflow passage into the central space by the fluid flowing at high speed from the first opening toward the second opening as the driver is displaced. be able to. That is, the fluid can be drawn into the central space from the inflow passage not only when the driving body is displaced convexly downward but also when it is displaced convexly upward. Since the fluid drawn from the inflow passage and the fluid pushed out from the blower chamber merge and are discharged from the second opening, a discharge flow rate that is equal to or greater than the displacement volume of the driver can be obtained. Since the inflow passage is connected to the central space between the first and second openings and is not directly connected to the blower chamber, the inflow passage is hardly affected by the pressure change in the blower chamber. Therefore, the high flow rate that flows through the first and second openings does not flow back into the inflow passage without providing a check valve, and the flow rate can be effectively increased. The opening area of the central space is larger than the first opening and the second opening and smaller than the blower chamber. The fluid that has entered from the inflow passage is once collected in the central space and discharged together from the second opening by the flow of the fluid blown out from the first opening.

When the drive body bends and vibrates up and down as described above, the fluid is drawn into the central space from the inflow passage using the pressure energy generated by the fluid pushed out from the blower chamber, and is pushed out from the drawn fluid and the blower chamber. The fluid merges and is discharged from the second opening. If the inflow passage is connected to the central space as it is, pressure energy in the central space escapes to the inflow passage. Therefore, in the present invention, a throttle having a small passage area is provided in the inflow passage. This restriction makes it difficult for the pressure energy in the central space to escape to the inflow passage, so that the pressure energy can act directly on the second opening, and the flow rate of the fluid delivered from the second opening can be increased.

It is preferable that the first opening is formed in a portion of the first wall that faces the center of the driving body. The maximum flow rate can be obtained by forming the first opening at a position facing the central portion where the displacement of the driving body is the largest. Furthermore, it is preferable that the second opening is formed at a portion of the second wall that faces the first opening. The high-speed fluid ejected from the first opening can pass through the central space and be discharged to the outside from the second opening without any resistance.

The restrictor is preferably provided at a connection portion between the inflow passage and the central space. The position of the throttle may be anywhere in the inflow passage, but if it is provided in a position close to the central space, the pressure energy in the central space becomes difficult to escape to the inflow passage, and the pressure energy in the central space is effectively applied to the second opening. be able to.

The shape of the restriction is preferably a shape in which the passage area gradually decreases along the direction of flow from the inflow passage toward the central space. The average pressure in the central space is lower than the average pressure in the inflow passage, and a pressure gradient is generated. In the flow path, pressure loss occurs due to friction between the fluid and the wall surface. However, since the pressure in the central space is lower than the pressure drop due to the pressure loss, a contraction occurs near the inlet of the central space. Since the vortex is generated around the contracted flow and the loss is generated, the flow rate is lowered. Therefore, by providing a throttle having a shape in which the passage area gradually decreases from the inflow passage toward the central space, the generation of vortex of the fluid entering the central space from the inflow passage is suppressed, and the average pressure in the central space can be further reduced. it can. Therefore, the flow rate drawn into the central space is increased, and the flow rate of the fluid sent out from the second opening can be further increased.

If the inflow passage is composed of a plurality of passages extending in the radial direction from the central space, and the inlet is formed at the outer end of each inflow passage, the passage area of the inflow passage can be secured, so the flow resistance can be reduced, The flow rate can be further increased.

It is preferable to set the opening area of the central space so that the portion of the first wall portion facing the central space vibrates with the vibration of the driving body. When the first wall portion vibrates, there is a function of increasing the flow rate of the fluid generated by the driving body by the displacement of the first wall portion, and a further increase in the flow rate can be realized. In particular, it is desirable that the portion of the first wall portion facing the central space resonates with the vibration of the driving body. That is, the first wall portion can resonate following the displacement of the drive body by bringing the natural frequency of the portion of the first wall portion facing the central space close to the vibration frequency of the drive body. In addition, when resonating, it is not necessary for the first wall portion and the driving body to vibrate in the same resonance mode. For example, both the driving body and the first wall portion may resonate in a primary mode or a higher order mode (eg, a third order mode), or one may resonate in a first order mode and the other in a higher order mode. Good.

The driving body in the present invention is a unimorph type in which a piezoelectric element that expands and contracts in a planar direction is attached to one side of a diaphragm (resin plate or metal plate), and a bimorph in which piezoelectric elements that extend in opposite directions are attached to both sides of the diaphragm. A bimorph type in which a laminated piezoelectric element that itself bends and deforms on one side of a mold or a diaphragm, or a structure in which the entire driving body is constituted by a laminated piezoelectric element may be used. The shape of the piezoelectric element may be a disk shape, a rectangular shape, or an annular shape. A structure in which an intermediate plate is sandwiched between the piezoelectric element and the diaphragm may be employed. In any case, it is only necessary to apply an alternating voltage (sine wave voltage or rectangular wave voltage) to the piezoelectric element so as to bend and vibrate in the thickness direction.

Driving the drive body including the piezoelectric element in the primary resonance mode (primary resonance frequency) is desirable because the largest amount of displacement can be obtained. However, since the primary resonance frequency is in the audible range, noise increases. There is. In contrast, when the third-order resonance mode (third-order resonance frequency) is used, the amount of displacement is smaller than that of the first-order resonance mode, but a larger amount of displacement is obtained than when the resonance mode is not used, and the audible region is reduced. Since it can be driven at a frequency exceeding, noise can be prevented. The primary resonance mode is a mode in which the central portion and the peripheral portion of the driving body are displaced in the same direction. The tertiary resonance mode is a direction in which the central portion and the peripheral portion of the driving body are in the opposite directions. It is a mode to be displaced.

Effects of preferred embodiments of the invention

As described above, according to the piezoelectric micro blower of the present invention, the fluid in the central space is sucked into the blower chamber through the first opening by bending and vibrating the driving body, and the outside of the blower chamber is discharged from the second opening. The fluid existing in the central space can be entrained and pushed out together with the high-speed flow pushed out to the outside. Therefore, a discharge flow rate that is equal to or greater than the displacement volume of the driving body can be obtained without using a check valve, and a large flow rate blower can be realized. In addition, since the throttle is provided in the inflow passage, it is possible to suppress the pressure fluctuation in the central space from spreading to the inflow passage, and the pressure energy in the central space can be effectively transmitted to the second opening. As a result, a further increase in flow rate can be achieved.

1 is an overall perspective view of a first embodiment of a piezoelectric microblower according to the present invention. FIG. 3 is an exploded perspective view of the piezoelectric microblower shown in FIG. 2. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. It is operation | movement explanatory drawing of the piezoelectric micro blower shown in FIG. It is sectional drawing of the modification of a piezoelectric micro blower. The flow rate characteristic with respect to the applied voltage and the flow rate characteristic with respect to the power consumption in the sample in which the material and thickness of the separator are changed are shown. It is sectional drawing of the micro blower which shows the other example of an aperture_diaphragm | restriction.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
1 to 4 show a first embodiment of a piezoelectric microblower according to the present invention. The piezoelectric micro blower A of this embodiment is an example used as an air cooling blower of an electronic device, and includes a top plate (second wall portion) 10, a flow path forming plate 20, a separator (first wall portion) 30, and a blower frame. The body 40, the driving body 50, and the bottom plate 60 are laminated and fixed in order from above. The outer peripheral portion of the driving body 50 is bonded and fixed between the blower frame body 40 and the bottom plate 60. The parts 10, 20, 30, 40, 60 excluding the driving body 50 constitute the blower body 1, and are formed of a rigid flat plate material such as a metal plate or a hard resin plate.

The top plate 10 is formed of a rectangular flat plate, and a discharge port (second opening) 11 penetrating the front and back is formed at the center thereof.

The flow path forming plate 20 is also a flat plate having the same outer shape as the top plate 10, and as shown in FIG. 4, a central hole (central space) 21 having a diameter larger than that of the discharge port 11 is formed in the central portion thereof. A plurality of (in this case, four) inflow passages 22 extending in the radial direction from the central hole 21 toward the four corner portions are formed, and the outer peripheral end of the inflow passage 22 is connected to an inflow port 8 described later. . In the case of this embodiment, since the inflow passage 22 communicates with the central hole 21 from four directions, the fluid is attracted to the central hole 21 without resistance along with the pumping operation of the driver 50, and the flow rate is further increased. Can be planned. The inflow passage 22 is formed with a tapered throttle 23 whose flow path width gradually decreases toward the central hole 21. In this embodiment, the throttle 23 is formed at the connecting portion between the inflow passage 22 and the central hole 21, but may be formed at any location in the inflow passage 22.

The separator 30 is also a flat plate having the same outer shape as the top plate 10, and a communication hole 31 (first opening) having substantially the same diameter as the discharge port 11 is formed at the center of the separator 30 at a position facing the discharge port 11. Yes. The discharge port 11 and the communication hole 31 may have the same diameter or different diameters, but have at least a diameter smaller than the central hole 21. In the vicinity of the four corner portions, inflow holes 32 are formed at positions corresponding to the outer end portions of the inflow passage 22. By bonding the top plate 10, the flow path forming plate 20, and the separator 30, the discharge port 11, the central hole 21, and the communication hole 31 are aligned on the same axis, and correspond to the center portion of the driving body 50 described later. Yes. As will be described later, in order to resonate the portion of the separator 30 corresponding to the central hole 21, it is desirable to form the separator 30 with a thin metal plate.

The blower frame 40 is also a flat plate having the same outer shape as the top plate 10, and a large-diameter cavity 41 is formed at the center thereof. In the vicinity of the four corner portions, inflow holes 42 are formed at positions corresponding to the inflow holes 32. By bonding the separator 30 and the drive body 50 with the blower frame 40 therebetween, a blower chamber is formed by the cavity 41 of the blower frame 40. The blower chamber 41 does not have to be a closed space and may be partially opened.

The bottom plate 60 is also a flat plate having the same outer shape as the top plate 10, and a hollow portion 61 having substantially the same shape as the blower chamber 41 is formed at the center thereof. The bottom plate 60 is formed thicker than the sum of the thickness of the piezoelectric element 52 and the displacement amount of the diaphragm 51, and even when the micro blower A is mounted on a substrate or the like, the piezoelectric element 52 can be prevented from coming into contact with the substrate. . The cavity 61 surrounds a piezoelectric element 52 of the driving body 50 described later. In the vicinity of the four corners of the bottom plate 60, inflow holes 62 are formed at positions corresponding to the inflow holes 32 and 42.

The driving body 50 has a structure in which a circular piezoelectric element 52 is attached to the lower surface of the central portion of the diaphragm 51. As the diaphragm 51, various metal materials such as stainless steel and brass can be used, and a resin plate made of a resin material such as a glass epoxy resin may be used. The piezoelectric element 52 is a disk having a smaller diameter than the hollow portion 41 of the blower frame body 40. In this embodiment, a single-plate piezoelectric ceramic having electrodes on the front and rear surfaces is used as the piezoelectric element 52, and this is attached to the rear surface (surface opposite to the blower chamber 41) of the diaphragm 51 to form a unimorph type driving body. did. By applying an alternating voltage (sine wave or rectangular wave) to the piezoelectric element 52, the piezoelectric element 52 expands and contracts in the plane direction, so that the entire driving body 50 is bent and deformed in the plate thickness direction. By applying an alternating voltage that causes the piezoelectric element 52 to bend and displace the driving body 50 in the primary resonance mode or the tertiary resonance mode, the displacement volume of the driving body 50 can be greatly reduced as compared with the case where voltages having other frequencies are applied. The flow rate can be greatly increased.

In the vicinity of the four corners of the diaphragm 51, inflow holes 51 a are formed at positions corresponding to the inflow holes 32, 42, and 62. The inflow holes 32, 42, 62, 51 a form an inflow port 8 having one end opened downward and the other end communicating with the inflow passage 22.

As shown in FIG. 3, the inflow port 8 of the piezoelectric micro blower A opens toward the lower side of the blower body 1, and the discharge port 11 opens to the upper surface side. Since the compressive fluid can be sucked in from the inlet 8 on the back side of the piezoelectric micro blower A and discharged from the outlet 11 on the front side, the structure is suitable as an air supply blower for a fuel cell or an air cooling blower for a CPU. In addition, the inflow port 8 does not need to open below, and may open to the outer periphery.

In FIG. 3, the driving body 50 including the diaphragm 51 and the piezoelectric element 52 is used. However, as illustrated in FIG. 6, the driving body 50 in which the intermediate plate 53 is provided between the diaphragm 51 and the piezoelectric element 52 is used. May be. As the intermediate plate 53, a metal plate such as SUS can be used. By providing such an intermediate plate 53 between the diaphragm 51 and the piezoelectric element 52, the neutral surface when the driving body 50 is bent and displaced can be positioned in the intermediate plate 53. As a result, the displacement efficiency is increased. Can be further improved, and a piezoelectric micro blower with a low voltage and a large flow rate can be obtained.

FIG. 5 is a schematic view for explaining the operation of the piezoelectric micro blower A, and the displacement is shown greatly for easy understanding. 5A shows the initial state (when no voltage is applied), and FIGS. 5B to 5E show the driving body 50 and the separator every 1/4 period of the voltage applied to the piezoelectric element 52 (for example, sin wave). 30 displacements are illustrated. By applying an alternating voltage to the piezoelectric element 52, the operations (b) to (e) are periodically repeated. As shown in the figure, the separator 30 resonates with the vibration of the driving body 50, and the separator 30 vibrates in a form delayed by a predetermined phase (about 90 ° here) with respect to the driving body 50. When the separator 30 resonates, a large pressure wave is generated upward from the first opening 31, and the air in the central space 21 is discharged from the second opening 11 to the outside by the pressure wave. Therefore, an increase in flow rate can be achieved as compared with the case where the separator 30 does not resonate. By discharging the air in the central space 21 to the outside, the air in the inflow passage 22 is drawn toward the central space 21, and an air flow can be continuously generated from the second opening 11.

Although FIG. 5 illustrates an example in which the driving body 50 is displaced in the primary resonance mode, the same applies to the case where the drive body 50 is displaced in the tertiary resonance mode. Moreover, although the displacement amount of the separator 30 is larger than the displacement amount of the driving body 50, the displacement amount of the separator 30 is smaller than that of the driving body 50 depending on the size of the central space 21, the Young's modulus and the thickness of the separator 30, and the like. There may be cases. Further, the phase delay of the separator 30 with respect to the driving body 50 is not limited to 90 °. In short, the separator 30 vibrates together with a certain phase lag with respect to the driving body 50, and thereby the distance between the driving body 50 and the separator 30 changes more greatly than when the separator 30 does not vibrate. I just need it.

The micro blower A under the following conditions was used and the flow rate was measured.
Driver: Piezoceramic element single plate with a thickness of 0.2mm and a diameter of 11mm was pasted on a diaphragm made of 42Ni plate with a thickness of 0.08mm, with an intermediate plate of SUS430 having a thickness of 0.15mm and a diameter of 11mm. Unimorph element blower chamber: height 0.15mm, diameter 16mm
Blower body: 20mm long x 20mm wide x 2.4mm high
Separator: SUS430 with a thickness of 0.05mm
First opening: Diameter 0.6mm
Second opening: 0.8mm in diameter
Central space: Diameter 6mm, Height 0.5mm
Inflow passage: width 2.5mm, height 0.5mm, 4 throttles: width 1mm

When the micro blower A having the above-described configuration was driven by applying a sin waveform voltage having a frequency of 24 kHz and 20 Vp-p, a flow rate of 0.9 L / min was obtained at 100 Pa. This is an example of driving in the tertiary mode, but it can also be driven in the primary mode. On the other hand, when an experiment was performed using a microblower having the same structure except that the throttle was not provided, a flow rate of 0.77 L / min was obtained at 100 Pa. From this result, it was confirmed that the flow rate increased by providing a throttle.

The reason why the flow rate is increased by providing the throttle in the inflow passage in this way is considered to be the following (1) to (3).

(1) First, with the vibration of the driving body 50, a high-energy pressure wave is generated from the first opening 31, and the air in the central space 21 is discharged from the second opening 11. At this time, since the portion of the separator 30 which is the bottom wall of the central space 21 vibrates (see FIG. 5), a high pressure fluctuation occurs in the central space 21, and this pressure energy flows into not only the second opening 11 but also the second opening 11. It also tries to diffuse into the passage 22. In particular, when the passage area of the inflow passage 22 is set large in order to reduce the air resistance, the loss of pressure energy is large. However, providing the throttle 23 in the inflow passage 22 makes it difficult for the pressure energy in the central space 21 to diffuse into the inflow passage 22, so that the pressure energy in the central space 21 can be efficiently directed to the second opening 11. An increase in flow rate can be achieved.

(2) Moreover, since the inside of the central space 21 is a high-speed air flow, the average pressure is lower than the pressure on the inflow passage 22 side. Therefore, a pressure gradient is generated in the flow path, and a flow from the inflow passage 22 side toward the central space 21 is generated. In the inflow passage 22, pressure loss occurs due to friction with the wall surface of the air. However, since the pressure in the central space 21 is lower than the pressure drop due to the pressure loss, the central space 21 is used in the case of a flow path without a throttle. A constricted part is formed near the entrance to the, and loss due to the generation of vortices occurs around the constricted part. As a result, the flow rate of the blower decreases. Therefore, by providing the throttle 23 in the vicinity of the entrance to the central space 21, the compatibility between the flow path shape and the flow shape is enhanced, so that the generation of vortices and the like can be suppressed, and the flow loss is reduced. . As a result, the flow rate of the blower increases.

(3) Furthermore, the separator 30 is bonded to the flow path forming plate 20, and the central region of the separator 30 corresponding to the central space 21 is configured to be able to vibrate. The vibration in the central region of the separator 30 greatly affects the flow rate as shown in FIG. Therefore, although the size (opening area) of the central space 21 is designed to have an appropriate diameter so that the central region of the separator 30 can easily vibrate, the connection portion between the central space 21 and the inflow passage 22 is separated. Can not be restrained. In the case of the flow path forming plate 20 having the restriction 23, since the tip end portion of the restriction 23 is narrow, the area where the side wall of the central space 21 exists increases. That is, the area supporting the separator 30 is increased as compared with the case where there is no diaphragm, and the support area of the separator 30 becomes closer to a circle. As a result, the one with the throttle 23 can more appropriately support the central region of the separator 30 and contribute to an increase in the flow rate.

Table 1 shows the difference in flow rate when the driving frequency of the driving body 50 and the diameter of the central space 21 are changed. The unit of flow rate is L / min. The thickness of the diaphragm (42Ni collar plate) at a driving frequency of 24.4 kHz was 0.08 mm, and the thickness of the diaphragm (42Ni collar) at a driving frequency of 25.5 kHz was 0.1 mm.

Figure JPOXMLDOC01-appb-T000001

As is clear from Table 1, when the diameter of the central space 21 is 5 mm, the flow rate increases when the frequency is increased. However, when the diameter of the central space 21 is 6 mm, the frequency is decreased. It can be seen that the flow rate increases. Thus, it can be seen that the vibration of the separator 30 corresponding to the central space 21 affects the flow rate. Although the natural frequency of the driving body 50 varies depending on the material and thickness of the diaphragm 51, the natural frequency of the separator 30 corresponding to the central space 21 can be adjusted by adjusting the diameter of the central space 21. It seems that the resonance can be made close to the natural frequency, and the flow rate is increased thereby.

FIG. 7 shows an experimental result of the micro blower B using the driving body 50 in which the intermediate plate 53 is provided between the diaphragm 51 and the piezoelectric element 52. In this experiment, as shown in Table 2, the flow rates when the material and thickness of the separator 30 are changed are compared. Sample 1 used phosphor bronze having a thickness of 0.05 mm as a separator, and sample 2 used SUS304 having a thickness of 0.1 mm as a separator. Other configurations are the same as those of the micro blower A. The configuration other than the separator is common to Sample 1 and Sample 2, and the drive frequency is both 24.4 kHz.

Figure JPOXMLDOC01-appb-T000002

When phosphor bronze and SUS304 are compared at the same thickness, SUS304 is about 1.5 times more rigid than phosphor bronze, but the difference in thickness is twice, so sample 2 is better than sample 1 The separator has a much higher rigidity. In other words, in sample 1, the separator part facing the central space vibrates, but in sample 2, it is considered that the separator part hardly vibrates. This experiment was to measure the influence of the vibration of the separator portion facing the central space on the flow rate.

As shown in FIG. 7A, for example, when compared at an applied voltage of 20 Vpp, the sample 2 is about 0.42 L / min, whereas the sample 1 is about 0.78 L / min. Is approximately twice that of sample 2. That is, it can be seen that the vibration of the separator part greatly contributes to the increase in the flow rate. FIG. 7B compares the flow rates based on the power consumption. Since the impedance changes, the power consumption also changes, but it can be seen that the sample 1 is more advantageous when compared with the same power consumption.

[Second Embodiment]
FIG. 8 shows another embodiment of the aperture shape. In addition, since it is the same as that of 1st Embodiment (FIG. 4) except an aperture_diaphragm | restriction, the same code | symbol is attached | subjected and duplication description is abbreviate | omitted. In this embodiment, a non-tapered diaphragm 24 is formed at the connecting portion between the inflow passage 22 and the central space 21. Also in this case, the flow rate can be increased because the throttle 24 has a function to suppress the pressure fluctuation in the central space 21 from spreading to the inflow passage 22 side.

In the embodiment, the example in which the separator (first wall portion) corresponding to the central space is resonated with the vibration of the driving body has been described. If the vibration is excited and the separator vibrates following the driving body, an increase in the flow rate can be achieved. The shape of the inflow passage is not limited to the shape linearly extending in the radial direction as shown in FIG. 4, and can be arbitrarily selected. Also, the number of inflow passages is arbitrary and can be selected according to the flow rate and the degree of noise.

In the above embodiment, the blower body is formed by laminating and bonding a plurality of plate-like members. However, the present invention is not limited to this. For example, the top plate 10 and the flow path forming plate 20, the separator 30 and the blower frame 40, and the flow path forming plate 20 and the separator 30 can be integrally formed of resin or metal.

A Piezoelectric micro blower 8 Inlet 10 Top plate (second wall)
11 Discharge port (second opening)
20 Channel formation plate 21 Center hole (central space)
22 Inflow passage 23 Restriction 30 Separator (first wall)
31 communication hole (first opening)
40 Blower frame 41 Blower chamber 50 Driver 51 Diaphragm 52 Piezoelectric element 60 Bottom plate

Claims (7)

  1. A blower body, a drive body having a piezoelectric element having an outer peripheral portion fixed to the blower body, and a blower chamber formed between the blower body and the drive body, and applying a voltage to the piezoelectric element. In a piezoelectric micro blower that transports a compressive fluid by bending and vibrating a driver,
    A first wall portion of a blower body forming a blower chamber with the driver,
    A first opening formed in the first wall for communicating the interior and exterior of the blower chamber;
    A second wall provided on the opposite side of the blower chamber with the first wall in between, and spaced from the first wall;
    A second opening formed in the second wall;
    An opening area formed between the first wall portion and the second wall portion, having an opening area larger than the first opening portion and the second opening portion and smaller than the blower chamber, and the first opening portion and the second opening portion. The central space leading to the club,
    An inflow passage having an outer end connected to the outside and an inner end connected to the central space,
    A piezoelectric microblower characterized in that a throttle having a smaller passage area than the inflow passage is provided in the inflow passage.
  2. 2. The piezoelectric micro blower according to claim 1, wherein the first opening is formed in a portion of the first wall that faces a central portion of the driving body.
  3. 3. The piezoelectric micro blower according to claim 1, wherein the second opening is formed at a portion of the second wall that faces the first opening. 4.
  4. 4. The piezoelectric micro blower according to claim 1, wherein the throttle is provided at a connection portion between the inflow passage and the central space. 5.
  5. 5. The piezoelectric micro blower according to claim 1, wherein the throttle is formed so that a passage area gradually decreases along a flow direction from the inflow passage toward the central space. 6.
  6. 6. The piezoelectric micro blower according to claim 1, wherein an opening area of the central space is set such that a portion facing the first wall portion vibrates with vibration of the driving body.
  7. The piezoelectric micro blower according to claim 1, wherein the inflow passage includes a plurality of passages extending in a radial direction from the central space.
PCT/JP2009/058968 2008-05-30 2009-05-14 Piezoelectric microblower WO2009145064A1 (en)

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EP09754572.7A EP2306019A4 (en) 2008-05-30 2009-05-14 Piezoelectric microblower
JP2010514432A JP5287854B2 (en) 2008-05-30 2009-05-14 Piezoelectric micro blower
US12/953,555 US20110070110A1 (en) 2008-05-30 2010-11-24 Piezoelectric micro blower

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JPWO2009145064A1 (en) 2011-10-06
US20110070110A1 (en) 2011-03-24
EP2306019A4 (en) 2014-10-15
EP2306019A1 (en) 2011-04-06

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