JP2010029759A - Piezoelectric fan device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric fan device which is superior in cooling performance capable of locally cooling the periphery of an IC chip in various kinds of electronic equipment. <P>SOLUTION: In the piezoelectric fan device 100A, one end side or a middle of a piezoelectric fan part 110 consisting of a plate-like piezoelectric element 111 and a plate-like elastic vibration plate 112 on which the plate-like piezoelectric element 111 is fixed and having a length longer than the plate-like piezoelectric element 111, is cantileveredly supported and fixed on a support part 130, an alternate circuit 120 applying an alternate voltage to electrodes of the plate-like piezoelectric element 111 is provided, and a weight member 140 is provided at an end side of the vibrating elastic vibration plate 112. This configuration improves the amplitude and reduces vibration frequency. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

    The present invention relates to a piezoelectric fan device including a piezoelectric element that locally cools the periphery of a chip such as an LSI or a CPU in various electronic devices.

Since chips such as LSIs and CPUs incorporated in various electronic devices are local heat sources, depending on the product, it is necessary to cool them appropriately.
As a response to such a demand, a simple heat radiating body (plate) having a large number of heat radiating pieces is also used, but a small piezoelectric element (ceramic element) that can be cooled more efficiently is used. A piezoelectric fan device is provided (for example, cited document 1).
JP 2000-323882 A

The schematic structure of the piezoelectric fan device is as shown in FIGS. In these apparatuses, one or two plate-like piezoelectric elements (usually ceramic elements made of PZT or the like) 11 are placed on one side or both sides of a longer elastic diaphragm (blade) 12 via an adhesive layer 13. Pasted. The plate-like piezoelectric element 11 is usually formed with electrodes 14 and 14 on both surfaces thereof, and is integrated with the elastic diaphragm 12 as a piezoelectric fan unit 10.
An AC circuit 20 for applying an AC voltage to the piezoelectric fan unit 10 is connected to the piezoelectric fan unit 10 so as to be energized between the electrodes 14 and 14 of the plate-like piezoelectric element 11, while one end (center, etc.) of the piezoelectric fan unit 10 is connected. Is also supported and fixed as a cantilever type by a support part 30 which is a fixed part. In addition, a single plate-like piezoelectric element 11 is called a monomorph type (unimorph type), and a two-sheet piezoelectric element 11 is called a bimorph type.

  In the case of such a piezoelectric fan device, when an AC voltage is applied, the plate-like piezoelectric element 11 expands or contracts, so that the piezoelectric fan unit 10 is bent alternately in the forward and reverse directions as a whole. Accordingly, when the piezoelectric fan device is assembled around a chip such as an LSI or CPU in an electronic device and a sine wave having a resonance frequency is applied as an AC voltage, the free end (free end) side of the elastic diaphragm 12 is a fan shape. Cooling air is generated. That is, a desired fan function can be obtained.

  In addition, when there are two plate-like piezoelectric elements 11, when one plate-like piezoelectric element 11 extends, the other plate-like piezoelectric element 11 shrinks. Conversely, when one plate-like piezoelectric element 11 shrinks, the other Since the plate-like piezoelectric element 11 is extended, the bending motion in the forward and reverse directions is amplified. For this reason, larger cooling air is generated. That is, a better fan function can be obtained.

  In the piezoelectric fan device having such a structure, in order to increase the cooling performance, in order to obtain larger high vibration of the elastic diaphragm 12, the length of the elastic diaphragm 12 is increased or the voltage to be energized is increased. It will be necessary.

  However, in recent years, with the downsizing of electronic equipment, the space for installing a piezoelectric fan device, which is a cooling component, has also been limited, and it has become difficult to increase the size of the device. On the other hand, the power consumption of electronic devices has increased due to the progress of multi-functionalization, and it has become difficult to drive the piezoelectric fan device at a high voltage.

  That is, there is a need for a piezoelectric fan device having a size equivalent to that of the conventional structure and higher cooling performance. Furthermore, there is a need for a piezoelectric fan device that has the same cooling performance even if it is smaller than the conventional structure.

  Accordingly, the present inventors have focused on the vibration state at the time of vibration of the elastic diaphragm 12, and found that when a weight member is provided on the distal end side of the elastic diaphragm 12 to vibrate, a large amplitude can be obtained. . This is presumed that the amplitude increases due to the generation of the inertia moment (inertia) by the weight member. In addition, since the center of gravity of the elastic diaphragm moves to the tip side, it was found that the cantilevered support type has lower frequency vibration as the weight on the tip side increases, and noise can be reduced.

  The present invention has been made in view of these points, and by providing a weight member on the vibrating front end side (free end side) of the non-fixed end of the elastic diaphragm (blade), a larger amplitude characteristic, that is, It is an object of the present invention to provide an excellent piezoelectric fan device capable of obtaining high cooling performance and at the same time reducing noise by low frequency vibration.

  According to a first aspect of the present invention, there is provided a piezoelectric fan comprising a single plate-like piezoelectric element and a plate-like elastic vibration plate having a length longer than that of the plate-like piezoelectric element. A piezoelectric fan device comprising an AC circuit that supports and fixes one end side or a middle of the unit in a cantilevered manner with a support unit and applies an AC voltage to the electrode on the outer surface of the plate-like piezoelectric element and the elastic diaphragm In the piezoelectric fan device, a weight member is provided on a front end side of the elastic diaphragm that vibrates.

  According to a second aspect of the present invention, there is provided the piezoelectric fan device according to the first aspect, wherein a weight member is provided on one side or both sides of the front end side of the elastic diaphragm.

  According to a third aspect of the present invention, there are provided two plate-like piezoelectric elements and a plate-like elastic diaphragm having a length longer than the two plate-like piezoelectric elements and sandwiched between these plate-like piezoelectric elements. A piezoelectric fan device comprising an AC circuit that supports and fixes one end side or a middle of the piezoelectric fan unit to be cantilevered by a support unit and applies an AC voltage between the electrodes on the outer surfaces of the two plate-like piezoelectric elements. In the piezoelectric fan device, a weight member is provided on a front end side of the elastic diaphragm that vibrates.

  According to a fourth aspect of the present invention, there is provided the piezoelectric fan device according to the third aspect, wherein a weight member is provided on one side or both sides of the front end side of the elastic diaphragm.

According to the piezoelectric fan device of the present invention, in the monomorph type or bimorph type, the weight member is provided on the vibrating vibration tip (blade), so that a large amplitude can be obtained. As a result, high cooling performance can be obtained. Further, noise can be reduced by low-frequency vibration.
Furthermore, when the cooling performance is improved, it is not necessary to increase the length of the elastic diaphragm or increase the energization voltage as in the prior art, so that the size of the apparatus can be reduced, and high voltage driving is possible. It is no longer needed.

FIG. 1 shows an example of a piezoelectric fan device according to the present invention, and FIG. 2 shows a piezoelectric fan device from a perspective direction with a part thereof omitted.
In the figure, reference numeral 100A denotes a monomorph type piezoelectric fan device, and 110 denotes the piezoelectric fan unit. The piezoelectric fan unit 110 is formed by attaching a single plate-like piezoelectric element 111 (an element such as PZT) to one side (upper surface in the drawing) of the elastic diaphragm 112 having a longer length via an adhesive layer 113. In addition, electrodes 114 and 114 are provided on both surfaces of the plate-like piezoelectric element 111. Reference numeral 120 denotes an AC circuit for applying an AC voltage to both electrodes 114 and 114 of the plate-like piezoelectric element 111, and reference numeral 130 denotes a fixed portion that supports one end side of the piezoelectric fan unit 110 (in the middle or the like) in a cantilever manner. A support portion 140 made of a component is a weight member provided on the tip side of the elastic diaphragm 112 that vibrates (the free end side opposite to the support portion 130 of the fixed component).

  The elastic diaphragm 112 is not particularly limited as long as it can vibrate, but is usually a flat metal plate such as brass or SUS, a resin plate such as PET, or CFRP (carbon fiber is impregnated with resin and post-cured. A composite plate made of a composite material such as a molded product) can be used. The weight member 140 provided on the distal end side of the elastic diaphragm 112 may be attached to one or both surfaces of the diaphragm with an adhesive or the like, for example, as illustrated.

Since the weight member 140 is for increasing the moment of inertia on the elastic diaphragm 112 side and obtaining a large vibration (high amplitude), the attachment mode is not particularly limited.
For example, the weight member 140 may be fixed to the tip of the diaphragm so as to extend its length. Further, the weight member 140 may be provided on the inner side from the tip of the diaphragm as long as the function is not lost. Further, in the illustrated example, the weight member 140 is a plate-shaped piece, but is not particularly limited thereto. For example, a disk-shaped piece or a square-shaped piece may be used. Further, a clip-like weight fixed to the tip of the diaphragm may be used. Furthermore, the material of the weight member 140 is not particularly limited as long as it has an appropriate amount of weight.

The energization to the plate-like piezoelectric element 111, particularly the energization to the inner electrode 114 on the elastic diaphragm 112 side may be performed by a normal method. For example, when the elastic diaphragm 112 is a metal plate, one lead wire of the AC circuit 120 is connected to the elastic diaphragm 112.
Although there is an adhesive layer 113 between the elastic diaphragm 112 and the electrode 114, since this layer is thin, it can be energized with no problem even with a normal adhesive material. The adhesive layer 113 may be a conductive adhesive layer. When the conductive adhesive layer is used, the electrode 114 inside the plate-like piezoelectric element 111 can be omitted in the present invention. Thereby, thickness reduction of an apparatus is obtained. Further, a lead wire or the like on the AC circuit 120 side may be directly connected to the inner electrode 114 side of the plate-like piezoelectric element 111. When the elastic diaphragm 112 is made of a non-metallic material plate, electrode connection using this lead wire or the like is required.

Thus, in the case of this monomorph type piezoelectric fan device 100A, since the weight member 140 is provided on the distal end side of the elastic diaphragm 112, the inertia moment on the distal end side is increased during vibration, so that a large vibration is obtained. It is done. That is, a large amplitude can be obtained.
As a result, the plate-like piezoelectric element 111 having the same performance can obtain a larger vibration.
Therefore, for the improvement of the cooling performance, it is not necessary to make the length of the elastic diaphragm particularly long as in the prior art, and it is not necessary to make the energized voltage particularly high.

FIG. 3 shows another example of the piezoelectric fan device according to the present invention, and FIG. 4 shows the piezoelectric fan device from a perspective direction with a part omitted.
In the figure, this piezoelectric fan device 100B is a bimorph type piezoelectric fan device, and a piezoelectric fan unit 110 is attached to two plate-like piezoelectric elements 111, 111 and an elastic diaphragm 112, which is bonded via adhesive layers 113, 113. Basically, it has the same structure as the piezoelectric fan device 100A. Of course, the weight member 140 is provided on the leading end side (free end side) of the elastic diaphragm 112 in the same manner as described above. The same components as those of the piezoelectric fan device 100A are denoted by the same reference numerals.

  In the case of this piezoelectric fan device 100B, since there are two plate-like piezoelectric elements 111, a larger amplitude can be obtained by the effect of adding piezoelectric elements and the effect of attaching the weight member 140 as compared to the piezoelectric fan device 100A.

<Examples and comparative examples>
In order to confirm the effect of the piezoelectric fan device according to the present invention, the same structure as that of the monomorph type piezoelectric fan device 100A of the present invention shown in FIG. 1 having the dimensions shown in FIG. Each sample having the same structure as that of the conventional monomorph type shown in FIG. 8 and having the dimensions shown in FIG. 6 (comparative example) was manufactured, and an AC voltage of ± 12 V was applied to the elastic diaphragm. The amplitude test was performed. The results were as shown in Table 1.

In the piezoelectric fan device of each sample described above, the elastic diaphragms 112 and 12 have a length of 20 mm and a width of 4.0 mm. The plate-like piezoelectric elements 111 and 11 have a length of 10 mm, a thickness of 0.2 mm, and the elastic diaphragms 112 and 12 have a thickness of 0.05 mm.
The plate-like piezoelectric elements 111 and 11 used are PZT. Three types of elastic diaphragms 112 and 12 were used: SUS301 (steel material), PET (resin plate), and CFRP (carbon fiber impregnated with resin and then cured). Furthermore, as the weight member 140 in the embodiment of the present invention, a small plate of SUS301 was used, and this was affixed to both surfaces on the tip side of the elastic diaphragm 112. And about the weight, the thing of 3.2 mg, 6.3 mg, 12.7 mg, and 25.4 mg was used.

  According to the characteristic data (amplitude evaluation result) in Table 1, when a weight member is provided on the tip side of the elastic diaphragm (an embodiment of the present invention), the weight member is not provided on the tip side of the elastic diaphragm (comparative example). It can be seen that the amplitude increases about 10% compared to

Moreover, when the vibration frequency (resonance frequency) in the piezoelectric fan device (the embodiment of the present invention and the comparative example) of each sample was measured, it was as shown in the graph of FIG.
That is, regardless of the material of the elastic diaphragm, when a weight member is provided (an embodiment of the present invention), particularly when the weight is increased, the vibration is less than that without a weight member (comparative example). It can be seen that the frequency decreases. It can be seen that noise (noise) can be reduced.

  In addition, it was confirmed that the same result was obtained when the same test as described above was performed even when the piezoelectric fan device was a bimorph type.

It is the general | schematic longitudinal section side view which showed an example of the piezoelectric fan apparatus which concerns on this invention. FIG. 2 is a partially omitted perspective view of the piezoelectric fan device of FIG. 1. It is the general | schematic longitudinal section side view which showed the other example of the piezoelectric fan apparatus which concerns on this invention. FIG. 4 is a partially omitted perspective view of the piezoelectric fan device of FIG. 3. It is a partially exploded perspective view of the sample corresponding to the piezoelectric fan apparatus of FIG. It is a perspective view of the sample corresponding to the piezoelectric fan apparatus of the following FIG. It is the graph which showed the relationship of the frequency of the vibration which concerns on the piezoelectric fan apparatus which concerns on this invention, and the conventional piezoelectric fan apparatus, the presence or absence of a weight member, and the weight of a weight member. It is the general | schematic longitudinal side view which showed the conventional piezoelectric fan apparatus. It is the general | schematic longitudinal side view which showed the other conventional piezoelectric fan apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100A-100B ... Piezoelectric fan apparatus, 110 ... Piezoelectric fan part, 111 ... Plate-shaped piezoelectric element, 112 ... Elastic vibration board, 113 ... Adhesive layer, 114 ... Electrode, 120 * ..AC circuit, 130 ... support part, 140 ... weight member

Claims (4)

One plate-like piezoelectric element and the plate-like piezoelectric element are fixed, and supports one end side or the middle of a piezoelectric fan unit comprising a plate-like elastic diaphragm having a longer length than the plate-like piezoelectric element. In a piezoelectric fan device comprising an AC circuit for applying an AC voltage to the electrode on the outer surface of the plate-like piezoelectric element and the elastic diaphragm, while being supported and fixed to a cantilever at the part,
A piezoelectric fan device characterized in that a weight member is provided on a vibrating tip side of the elastic diaphragm. 2. The piezoelectric fan device according to claim 1, wherein a weight member is provided on one side or both sides of the elastic diaphragm. One end side or halfway of a piezoelectric fan unit comprising two plate-like piezoelectric elements and a plate-like elastic diaphragm having a longer length than the two plate-like piezoelectric elements and sandwiched between these plate-like piezoelectric elements Is supported and fixed in a cantilevered manner by a support portion, and in the piezoelectric fan device including an AC circuit that applies an AC voltage between the electrodes on the outer surfaces of the two plate-like piezoelectric elements,
A piezoelectric fan device characterized in that a weight member is provided on a vibrating tip side of the elastic diaphragm. 4. The piezoelectric fan device according to claim 3, wherein a weight member is provided on one or both surfaces of the front end side of the elastic diaphragm.

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