JP2009146916A - Piezoelectric fan device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooing device for electronic equipment having improved cooling performance for locally cooling the periphery, or the like, of an IC chip in each kind of electronic equipment. <P>SOLUTION: In a piezoelectric fan device 100A, one edge side or the middle of a piezoelectric fan section 110, comprising one flat piezoelectric element 111 and a flat elastic metal plate 112, to which the flat piezoelectric element 111 is fixed while having length longer than that of the flat piezoelectric element 111 is supported and fixed in a cantilever manner by a support section 130. Also, the piezoelectric fan device 100A has an AC circuit 120 for applying an AC voltage to an electrode on the outer surface of the flat piezoelectric element 111 and the elastic metal plate 112. The piezoelectric fan device 100A also has a non-adhesive region A, such as, a rectangular opening 112a, at the adhesion section between the elastic metal plate 112 and the flat piezoelectric element 111, thus obtaining an amplitude-increasing effect. <P>COPYRIGHT: (C)2009,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 or both sides of a longer elastic metal plate (blade) 12 via an adhesive layer 13. Pasted. The plate-like piezoelectric element 11 is usually provided with electrodes 14 and 14 on both sides thereof, and is integrated with the elastic metal plate 12 as the 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. Therefore, if 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 metal plate 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 metal plate 12, the length of the elastic metal plate 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.

  Therefore, the present inventors pay attention to the bonding portion between the elastic metal plate 12 and the plate-like piezoelectric element 11, and do not bond them to the entire bonding portion, but are not bonded to a part of the bonding surface. When the non-adhesive region was provided, it was found that a higher amplitude can be obtained as apparent from the test results described later.

  The present invention has been invented by paying attention to this point, and by providing a part of the non-adhesive region at the adhesive portion between the elastic metal plate (blade) and the plate-like piezoelectric element, high amplitude, that is, high cooling performance. An excellent piezoelectric fan device having the above is provided.

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 metal plate to which the plate-like piezoelectric element is fixed and having a longer length than the plate-like piezoelectric element. A piezoelectric fan device comprising an AC circuit for supporting and fixing one end side or a halfway of the unit in a cantilevered manner with a support unit and applying an AC voltage to the electrode on the outer surface of the plate-like piezoelectric element and the elastic metal plate In
The piezoelectric fan device is characterized in that a non-bonding region is provided in a bonding portion between the elastic metal plate and the plate-like piezoelectric element.

According to a second aspect of the present invention, there are provided two plate-like piezoelectric elements and a flat elastic metal plate having a longer length 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
In the piezoelectric fan device, a non-bonding region is provided in a bonding portion between the elastic metal plate and the two plate-like piezoelectric elements.

  According to a third aspect of the present invention, there is provided the piezoelectric fan device according to the first or second aspect, wherein the non-bonding region is an opening opened in an elastic metal plate.

  A fourth aspect of the present invention is the piezoelectric fan device according to the third aspect, wherein the opening is rectangular.

  The present invention according to claim 4 is characterized in that the opening is rectangular and the bonding margin width of the bonding portion in the width direction of the elastic metal plate around the opening is 1.0 mm or more. Item 4. The piezoelectric fan device according to Item 4.

According to the piezoelectric fan device of the present invention, in a monomorph type or bimorph type, at the bonding portion between the elastic metal plate (blade) and the plate-like piezoelectric element, the two are not bonded to the entire surface but bonded to a part thereof. It is inferred that, as a result, the plate-like piezoelectric element easily vibrates because the non-bonded region is not provided. That is, since the degree of freedom of vibration of the plate-like piezoelectric element is increased, a higher amplitude can be obtained. Thereby, a large vibration of the elastic metal plate is obtained, and as a result, a high cooling performance is obtained.
Further, when improving the cooling performance, it is not necessary to increase the length of the elastic metal plate or increase the energization voltage, so that the size of the apparatus can be reduced and high voltage driving is required. Nothing will happen.

    FIG. 1 shows an example of a piezoelectric fan device according to the present invention, and FIG. 2 shows a schematic manufacturing process thereof. 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 includes a single plate-like piezoelectric element (PZT, etc.) 111 and an elastic metal plate (steel material such as SUS, brass material, etc.) 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 between the electrode 114 on the outer surface of the plate-like piezoelectric element 111 and the elastic metal plate 112, and 130 denotes one end side of the piezoelectric fan unit 110 (possibly in the middle or the like). It is a support part which consists of a fixed component supported by a holding type.

  When the plate-like piezoelectric element 111 is attached to one side of the elastic metal plate 112, the two are not bonded to the entire surface of the bonding portion, but as shown in FIG. 2, a rectangular opening 112a is formed on the elastic metal plate 112 side. Is opened and a non-bonding area A is provided and bonded.

  In other words, the rectangular peripheral edge of the opening 112a is used as a bonding margin. As a result, since the adhesive surface of the plate-like piezoelectric element 111 is not firmly and integrally bonded to the elastic metal plate 112 side, the structure easily vibrates. Thereby, as will be described later, a higher amplitude of the plate-like piezoelectric element 111 is obtained. Of course, corresponding to this, a large vibration is obtained on the elastic metal plate 112 side. As a result, high cooling performance can be obtained.

In addition, although the bonding margin width of the bonded portion in the width direction of the elastic metal plate in the non-bonded region A such as the rectangular opening can be set as appropriate, as is clear from the test examples described later, it is 1.0 mm or more. There is a need to. This is because if it is less than 1.0 mm, it is too narrow to obtain sufficient adhesive strength, and the adhesive layer is peeled off during driving.
Further, the bonding margin width of the bonded portion in the longitudinal direction of the elastic metal plate in the non-bonded region A such as a rectangular opening is not particularly limited, but may be set to about 1.0 to 1.5 mm. In the case of the opening, the plate itself is cut out, and if it is less than 1.0 mm, it is too narrow to obtain a sufficient holding force (strength) of the elastic metal plate itself.

Energization of the electrode 114 inside the plate-like piezoelectric element 111 is performed by a normal method. As described above, when energizing from the elastic metal plate 112 side, since the thickness of the adhesive layer 113 is thin, it is possible to energize even with a layer made of a normal adhesive material, but it can also be made conductive.
In the case of the conductive adhesive layer, in the present invention, the electrode 114 inside the plate-like piezoelectric element 111 can be omitted. Thereby, thickness reduction of an apparatus is obtained. When the adhesive layer 113 is a non-conductive adhesive layer, the lead wire on the AC circuit 120 side or the like may be directly connected to the inner electrode 114 side of the plate-like piezoelectric element 111.

  The elastic metal plate 112 (blade) is usually made of a flat steel plate such as SUS or a metal plate such as brass. As described above, the rectangular opening 112a is formed in the base end side of the metal plate, that is, the bonding portion with the plate-like piezoelectric element 111, thereby forming a non-bonding region A. The opening 112a can be opened by press working or the like. The function of the non-adhesion region A is not particularly limited to the opening because it serves to reduce the adhesive force with the plate-like piezoelectric element 111. For example, it may be a dent or a slit where no adhesive layer is formed. Furthermore, it may be a portion (region) where the adhesive layer is not formed simply by masking or the like.

FIG. 3 shows another example of the piezoelectric fan device according to the present invention, and FIG. 4 shows a schematic manufacturing process thereof. In the figure, the 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 (PZT, etc.) 111, 111 via adhesive layers 113, 113. It is made of an elastic metal plate (steel material such as SUS or brass material) 112, and basically has the same structure as the piezoelectric fan device 100A. Needless to say, a rectangular opening 112 a is formed in the base end side of the elastic metal plate 112, that is, at a bonding portion with the plate-like piezoelectric element 111, thereby forming a non-bonding region A. The same components as those of the piezoelectric fan device 100A are denoted by the same reference numerals.
In this piezoelectric fan device 100B, since there are two plate-like piezoelectric elements 111, 111, a larger amplitude effect of the elastic metal plate 112 can be obtained compared to the piezoelectric fan device 100A. That is, a greater cooling effect can be obtained.

<Examples and comparative examples>
In order to confirm the effect of the piezoelectric fan device according to the present invention, the structure is the same as that of the monomorph type piezoelectric fan device 100A of the present invention shown in FIG. 1 and has the dimensions shown in FIGS. Examples 1 to 10 and Comparative Examples 2 to 3) and the same structure as the conventional monomorph type shown in FIG. 8 and having the dimensions shown in FIG. 7 (Comparative Example 1) were produced. Then, an AC voltage of ± 12 V was applied to perform an amplitude test on the elastic metal plate. The results were as shown in Table 1.

  In the piezoelectric fan device of each sample, the length of the elastic metal plate (using SUS301) 112 and the length of the elastic metal plate (using SUS301) 12 are both 20 mm, and the width is 4.0 mm. The length (L0) of the elements (using PZT) 111 and 11 is 10.0 mm. The thickness of the elastic metal plates 112 and 12 of the piezoelectric fan device 100A is 0.05 mm. Furthermore, Table 1 shows values of the length L2, the height H2, and the bonding margin widths L1 and H1 of the bonding portion in the same structure as the piezoelectric fan device 100A.

From the amplitude data in Table 1 (amplitude evaluation result), if a non-adhesive region composed of a rectangular opening or the like is provided at the bonded portion between the elastic metal plate and the plate-like piezoelectric element, the effect of increasing the amplitude of the elastic metal plate is obtained. You can see that In particular, in the case of an opening, it can be seen that the effect of increasing the amplitude increases as the opening area (L1 × H2) increases. However, the bonding margin width L1 of the bonding portion in the width direction of the elastic metal plate needs to be 1.0 mm or more.
That is, as in Comparative Examples 2 to 3, when the thickness is less than 1.0 mm, the adhesive layer is peeled off during driving, which is too narrow to obtain sufficient adhesive strength.

  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 an exploded perspective view and an assembled view of a piezoelectric fan unit of the apparatus 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. 3 is an exploded perspective view and an assembled view of a piezoelectric fan unit of the apparatus of FIG. 2. It is a partially exploded perspective view of the sample corresponding to the piezoelectric fan apparatus of FIG. It is the top view which showed opening of the elastic metal plate of the piezoelectric fan part of FIG. It is a perspective view of the sample corresponding to the piezoelectric fan apparatus of the following FIG. 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 metal plate, 112a ... Opening, 113 ... Adhesive layer, 114. ..Electrodes 120 ... AC circuit 130 ... support part A ... non-adhesive region

Claims (5)

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 portion composed of a plate-like elastic metal plate having a longer length than the plate-like piezoelectric element. In the 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 metal plate, while being supported and fixed to the cantilever at the part,
A piezoelectric fan device characterized in that a non-bonding region is provided in a bonding portion between the elastic metal plate and the plate-like piezoelectric element. One end side or midway of a piezoelectric fan unit comprising two plate-like piezoelectric elements and a flat elastic metal plate sandwiched between the two plate-like piezoelectric elements and having a longer length than the two 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 non-bonding region is provided in a bonding portion between the elastic metal plate and the two plate-like piezoelectric elements. The piezoelectric fan device according to claim 1, wherein the non-bonding region is an opening opened in an elastic metal plate. The piezoelectric fan device according to claim 3, wherein the opening is rectangular. 5. The piezoelectric fan device according to claim 4, wherein the opening is rectangular, and the bonding margin width of the bonding portion in the width direction of the elastic metal plate around the opening is 1.0 mm or more.

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