JP2008263000A - Piezoelectric fan device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric fan device which is composed of piezoelectric elements for locally cooling the periphery of a chip such as LSI in various types of electronic apparatuses and has excellent cooling performance because of its amplitude increasing effect. <P>SOLUTION: The piezoelectric fan device 100A comprises a piezoelectric fan 110 composed of two plate-like piezoelectric elements 111 and 111 and an elastic metal plate 112 having a length longer than those of the plate-like piezoelectric elements and interposed between these plate-like piezoelectric elements, and an AC circuit 120 for applying an AC voltage between electrodes 114 and 114 of these plate-like piezoelectric elements 111 and 111. The piezoelectric fan 110 is supported and fixed in a cantilevered manner by a supporting portion 130 at its one end or midway. On the free end side of the elastic metal plate 112 opposite from the supporting portion side, one or two amplitude increasing portions (slits) 112a are formed. By this structure, an amplitude increasing effect is obtained. <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

  A schematic structure of the piezoelectric fan device is shown in FIG. In this apparatus, two plate-like piezoelectric elements (usually ceramic elements made of PZT or the like) 11 and 11 are attached to both surfaces of a longer elastic metal plate (blade) 12 via adhesive layers 13 and 13. It is attached. The both plate-like piezoelectric elements 11 and 11 have electrodes 14 and 14 formed on both surfaces thereof, and are integrated with the elastic metal plate 12 to form the piezoelectric fan portion 10. 11, an AC circuit 20 for applying an AC voltage is connected between the outer electrodes 14 and 14, and one end of the piezoelectric fan unit 10 (in the middle or the like is also possible) is connected to a support part which is a fixed part At 30, it is supported and fixed as a cantilever type.

  In the case of this piezoelectric fan device, when an AC voltage is applied, when one plate-like piezoelectric element 11 expands, the other plate-like piezoelectric element 11 contracts, and conversely, when one plate-like piezoelectric element 11 shrinks, the other plate-like piezoelectric element 11 shrinks. Since the plate-like piezoelectric element 11 extends, the piezoelectric fan unit 10 is bent and moved 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 order to enhance the fan function, a diaphragm made of a thin plate made of plastic or the like is provided on the free end side of the elastic metal plate 12 as necessary.

  The piezoelectric fan device having such a structure has no advantage of electromagnetic interference, can be installed close to a heat source such as an LSI or a CPU, and has the advantage of being small in size and simple in structure. There was a problem like this.

That is, in this apparatus, in order to obtain a smaller and higher amplitude of the elastic metal plate 12, the normal thickness of the plate-like piezoelectric element 11 has been reduced.
However, if the element is made too thin, there arises a problem that sufficient mechanical strength cannot be ensured, so that there is a limit to thinning the element.

  Therefore, the present inventors pay attention to the elastic metal plate 12 which is a portion other than the element, and in order to obtain a high (large) amplitude on the free end side of this plate, the longitudinal portion is used as an amplitude increasing portion for increasing the amplitude. When one or two or more slits (concave grooves) perpendicular to the direction were provided, good results were obtained.

  The present invention was invented based on such an idea, and by simply providing one or more slits on the free end side of an elastic metal plate (blade), it has a high amplitude, that is, a high fan function. A piezoelectric fan device is provided.

The present invention according to claim 1 includes two plate-like piezoelectric elements and a flat elastic metal plate having a longer length than both the 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 is characterized in that one or more amplitude increasing portions are provided on the free end side of the elastic metal plate in the direction opposite to the support portion side.

According to a second aspect of the present invention, there is provided a piezoelectric device 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 length longer than the two plate-like piezoelectric elements. A piezoelectric fan including an AC circuit that supports and fixes one end side or midway of the fan portion in a cantilever manner with a support portion and applies an AC voltage to the electrode on the outer surface of the plate-like piezoelectric element and the elastic metal plate In the device
The piezoelectric fan device is characterized in that one or more amplitude increasing portions are provided on the free end side of the elastic metal plate in the direction opposite to the support portion side.

  The present invention according to claim 2 is characterized in that the amplitude increasing portion is formed of a slit orthogonal or intersecting with the longitudinal direction on both sides or one side of the flat elastic metal plate. 2. The piezoelectric fan device according to 2.

  According to the piezoelectric fan device of the present invention, a bimorph type piezoelectric fan device composed of two plate-shaped piezoelectric elements and an elastic metal plate (blade), or a unimorph type composed of one plate-shaped piezoelectric element and an elastic metal plate. In the piezoelectric fan device, since the amplitude increasing portion, for example, one or more slits are provided in the longitudinal direction on both sides or one side of the elastic metal plate on the free end side, high amplitude can be obtained. That is, a high fan function can be obtained. At this time, since the thickness of the elastic metal plate itself does not need to be particularly thin, the mechanical strength of the elastic metal plate itself is not impaired.

FIG. 1 shows an example of a piezoelectric fan device according to the present invention.
In the figure, reference numeral 100A denotes a bimorph type piezoelectric fan device, and 110 denotes two plate-like piezoelectric elements 111 and 111 attached to both surfaces of a longer elastic metal plate 112 through adhesive layers 113 and 113, respectively. In addition, the piezoelectric fan unit is provided with electrodes 114 and 114 of both plate-like piezoelectric elements 111 and 111. 120 is an AC circuit for applying an AC voltage between the electrodes 114 and 114 on the outer surfaces of both plate-like piezoelectric elements 111 and 111, and 130 is cantilevered at one end side of the piezoelectric fan unit 110 (in the middle or the like). It is a support part which consists of a fixed component supported by a type | mold.

  The elastic metal plate 112 (blade) is usually made of a flat metal plate such as brass or SUS, or a hard resin plate such as PET, and has two slits (recesses) on its free end (free end) side. (Groove) 112a is provided as an amplitude increasing portion. The slit 112a partially reduces the rigidity (mechanical strength) on the free end side of the elastic metal plate 112.

  Due to the decrease in rigidity, the flexibility on the free end side of the elastic metal plate 112 is increased and is easily bent. As a result, an effect of increasing the amplitude on the free end side is obtained. In view of this amplitude increasing effect, a slit having a shape orthogonal to the longitudinal direction of the plate material is desirable. However, in terms of the function of increasing the amplitude, a cross-type slit slightly deviated from the orthogonal state may be used. Further, the number of slits is not particularly limited depending on the degree of increase in amplitude to be obtained, and may be 2 or more. Further, the surface on which the slit is formed may be a flat double-sided surface or a single-sided surface, or a combination of these may be used as appropriate.

  A specific method for forming the slit is not particularly limited, but may be mechanical polishing, chemical polishing (etching), a press method, or the like. Here, the pressing method is a method of forming a concave groove by pressing a blade member (such as a roll-type blade or a rod-shaped blade). The width and depth of the slit are not particularly limited, and can be set as appropriate. However, it is necessary to carry out within a range in which necessary mechanical strength is not lost due to the formation of the slit. Further, the shape of the slit is not particularly limited, and may be a square groove or a curved groove. Moreover, the whole slit may be an aggregate of a plurality of thin grooves. Furthermore, broadly, the slit portion only needs to have a function of reducing the rigidity of the blade, and thus may be a large number of short cuts, a large number of small holes, and dents arranged in the width direction of the flat plate.

FIG. 2 shows another example of the piezoelectric fan device according to the present invention.
In the figure, reference numeral 100B denotes a unimorph type piezoelectric fan device. This device has the same structure as the piezoelectric fan device 100A except that the piezoelectric fan unit 110 is composed of a single plate-like piezoelectric element 111 and an elastic metal plate 112 to which the piezoelectric fan unit 110 is attached via an adhesive layer 113. is there.

Also in this piezoelectric fan device 100B, the elastic metal plate 112 (blade) is usually made of a flat metal plate such as brass or SUS, or a hard resin plate such as PET, and on its free end (free end) side, Two slits (concave grooves) 112a are provided as amplitude increasing portions.
For this reason, as with the piezoelectric fan device 100A, the flexibility on the free end side of the elastic metal plate 112 is increased and is easily bent. As a result, an effect of increasing the amplitude on the free end side is obtained.
The shape of the slit 112a and the method of forming the slit 112a in the elastic metal plate 112 of this device are the same as those of 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, samples shown in FIGS. 3A to 3C were manufactured, and an amplitude test of an elastic metal plate (blade) was performed.
FIGS. 3A and 3B correspond to the piezoelectric fan device 100A of FIG. 1, and in FIG. 3A, one slit 112a (L1 from the tip) is formed on both surfaces of the elastic metal plate 112 on the free end side. Position). In FIG. 3B, two slits 112a (positions L1 and L2 from the tip) are provided on both surfaces of the elastic metal plate 112 on the free end side. FIG. 3C corresponds to the conventional piezoelectric fan device of FIG. 4 and has no slit on the free end side of the elastic metal plate 12. In each sample, the length of the elastic metal plates 112 and 12 is 20 mm, the width is 4.0 mm, and the length of the plate-like piezoelectric elements 111 and 11 is 7.5 mm. The slit 112a has a width of 1.0 mm and a depth of 50 μm.
In this amplitude test, in the apparatus shown in FIGS. 3A and 3B, the positions (L1, L2) of the slit 112a were variously changed. The results are shown in Table 1.

  According to Table 1, when compared with the amplitude (comparative example 1) in the conventional piezoelectric fan device of FIG. 3C as a reference, the piezoelectric fan device 100A according to the present invention corresponds to FIG. In the case of the elastic metal plate 112 of (B), although it varies depending on the formation position, it can be seen that an amplitude amplification effect of about 5 to 30%, that is, an amplitude increase effect is obtained.

  Even in the unimorph type piezoelectric fan device 100B, since the structure of the elastic metal plate 112 is the same as that of the piezoelectric fan device 100A, it is clear that a predetermined amplitude increasing effect can be obtained.

  The point of providing the amplitude increasing portion, which is a feature of the present invention, is not limited to the bimorph type or unimorph type, but in other piezoelectric fan devices, the elastic metal plate that vibrates, and the member corresponding thereto It can also be applied to the case of providing.

It is the schematic explanatory drawing which showed an example of the piezoelectric fan apparatus which concerns on this invention. It is the schematic explanatory drawing which showed the other example of the piezoelectric fan apparatus which concerns on this invention. (A)-(C) It is the schematic explanatory drawing which showed the sample for the amplitude test in a piezoelectric fan apparatus. It is the schematic explanatory drawing which showed the 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 ... Amplitude increasing part (slit), 113 ... Adhesive layer, 114... Electrode, 120... AC circuit, 130.

Claims (3)

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,
The piezoelectric fan device according to claim 1, wherein one or more amplitude increasing portions are provided on the free end side of the elastic metal plate opposite to the support portion side. One plate-like piezoelectric element and the plate-like piezoelectric element are fixed, and at one end side or in the middle of a piezoelectric fan portion composed of a plate-like elastic metal plate having a longer length than both the plate-like piezoelectric elements, In the piezoelectric fan device provided with 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 in a cantilever manner by the support portion,
The piezoelectric fan device according to claim 1, wherein one or more amplitude increasing portions are provided on the free end side of the elastic metal plate opposite to the support portion side. 3. The piezoelectric fan device according to claim 1, wherein the amplitude increasing portion is formed of a slit orthogonal to or intersecting with the longitudinal direction on both sides or one side of the flat elastic metal plate.

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