JPH0231600Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a polymer bimorph fan suitable for being driven by AC power sources having different frequencies.

BACKGROUND TECHNOLOGY Bimorph fans can output a relatively large amount of air with a relatively small electrical input, and have the advantage that they generate fewer harmful magnetic lines of force and resonance than conventional electromagnetic motor-driven fans. Because of this, it is attracting attention as a cooling device for electrical components such as cathode ray tubes, rectifiers, and transistors, and other devices. This bimorph fan, especially a polymeric bimorph fan, usually
It is obtained by fixing one end of a bimorph diaphragm, which is made by laminating multiple polymer piezoelectric films with different properties that expand or contract when voltage is applied and sandwiching them between electrodes. By applying , the diaphragm swings alternately in opposite directions using the fixed part as a fulcrum, and air can be sent to the object to be cooled through a motion similar to that of a fan.

However, in order to give a constant electrical input to this bimorph fan, make it vibrate efficiently, and output a large amount of air, it is necessary to give an AC input that matches its resonant frequency, but as is well known, it depends on the location. There is a problem in that the frequencies of the AC power sources that can be used are different. For example, even if you apply an AC input of 60 Hz to a bimorph fan with a resonant frequency of 50 Hz, you will not be able to obtain an output of 1/10 of the expected output. In order to drive such electric devices with different appropriate frequencies, it is conceivable to perform frequency conversion using a converter or the like to provide an AC input with an appropriate frequency. However, such means are generally expensive and also occupy a relatively large amount of space, which detracts from the advantages of bimorph fans as compact cooling devices.

On the other hand, the frequency selection characteristics of polymer bimorph fans are extremely sensitive, and for example, to provide an intermediate resonant frequency of 55Hz for 50Hz/60Hz switching,
When adjusting its effective vibration length, 50Hz and 60Hz
No matter which AC input is applied, the output is much lower than the expected output.

Purpose of the invention In view of the above-mentioned circumstances, the main purpose of the present invention is to provide a polymer bimorph fan that can easily follow AC power sources whose frequencies vary depending on the region.

Structure of the invention As a result of the various tests described in the background art section above, the inventors of the present invention found that, considering the sensitive frequency selection characteristics of polymer bimorph fans, a single It is not effective to use a bimorph diaphragm to deal with this problem, so it is recommended to prepare multiple bimorph diaphragms, each with a resonant frequency that corresponds to the power supply frequency that is planned to be used, and to use one as the main power source depending on the power supply that is actually used. However, it has been found that it is effective and realistic to have a structure in which the other functions only in an auxiliary manner.

The bimorph fan of the present invention is based on such knowledge, and more specifically, bimorph diaphragms made of multiple polymer bimorphs with different effective vibration lengths from the fixed part to the tip of the vibrating part are assembled in close proximity to each other. The device is characterized in that it is fixed to a jig and connected to an alternating current power source.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

Embodiment FIG. 1 is a perspective view of a polymer bimorph fan according to an embodiment of the present invention.

Referring to FIG. 1, this bimorph fan has two polymer bimorph diaphragms 1 and ₂ , each having an effective vibration length of l ₁ and l 2, fixed to a jig 3 made of plastic, for example. It is connected to an AC power source 6 via terminals 4a, 4b and a switch 5. Bimorph diaphragms 1 and 2 each have 6
having essentially the same layer configuration of the layers. Regarding the bimorph diaphragm 1, its layer structure and its connection circuit are shown in FIG. That is, the diaphragm 1 has a thickness of about 200 μm with A1 vapor deposited films (not shown) having a thickness of about 400 to 1000 Å provided on both sides, and each has polarization characteristics as shown by the arrows in FIG. Six layers of polymer piezoelectric films (for example, polyvinylidene fluoride films) 11 to 16 having the following properties are bonded and laminated via an adhesive (not shown). Connect the wires to this diaphragm 1 as shown in FIG.
When closed and electrical input is applied, the upper half of the polymer piezoelectric films 11 to 13 and the lower half of the polymer piezoelectric film 14
In ~16, the expansion and contraction characteristics are reversed, and under a constant electric field, one side undergoes deformation that extends and the other contracts, so it vibrates with the alternation of the electric field, and as a whole, it produces a larger vibration output than the two-layer bimorph. Can be done.

The respective effective vibration lengths l ₁ and l ₂ of bimorph diaphragms 1 and 2 are in this example approximately
30 mm and approximately 27 mm, and are set to provide resonant frequencies of 50 Hz and 60 HZ, respectively. More specifically, l ₁ and l ₂ are determined by the following formula ω ₀ =1.015t/l ² √ (where t, Y, and ρ are the thickness, Young's modulus, and density of the bimorph diaphragm, respectively) It can be roughly estimated as the value of l that makes the resonance frequency ω ₀ 50Hz or 60Hz, but for bimorph diaphragms that are laminated bodies, constants such as t, Y, and ρ are not necessarily uniquely determined, so further confirmation is required experimentally. It is preferable to do so.

When the switch 5 of the bimorph fan shown in FIG. 1 is closed, the frequency of the power supply 6 that provides electrical input is
In the case of 50 Hz, the bimorph diaphragm 1 mainly vibrates, and in the case of 60 Hz, the diaphragm 2 mainly vibrates, and the other vibrates very slightly. However, since such slight vibrations do not particularly adversely affect the characteristics of the bimorph fan as a whole, it is not necessary to cut off the input with an additional switch.

Note that the mutual vibration direction of the bimorph diaphragms 1 and 2 can be either parallel type (vibrates in the same direction) or parallel type (vibrates in opposite directions) depending on how they are connected to the power source 6. can.

The bimorph fan consisting of these bimorph diaphragms 1 and 2 is preferably housed in a cylinder or wind tunnel that opens toward the object to be cooled, as disclosed in Japanese Patent Application No. 58-32083 by the present inventors. It is preferable to do so.

Modifications The number of bimorph diaphragms can be two or more depending on the number of planned frequencies.

Also, when two diaphragms are used, they are not parallel as shown in Figure 1, but are located almost on the same plane at rest, as shown in Figure 3 (the connection to the power source is omitted). It can also be provided as follows. However, this form is not preferable because it increases the dead volume as a whole. This tendency is especially strong when bimorph fans are housed in a wind tunnel.

In addition, instead of forming two diaphragms independently, as shown in FIG. 4 (the connection to the power source is omitted), both ends 11 and By fixing the folded part 13 with the jig 3 and connecting the terminals 4a and 4b to the folded part 13, it is possible to use a common terminal for the two diaphragms, and the connection structure is improved accordingly. becomes easy. However, in this case, the mutual vibration type of the diaphragms 11 and 12 is substantially limited to the clasping type, but this does not cause any particular inconvenience.

In addition, in the above example, the polymeric piezoelectric material is polyvinylidene fluoride and a six-layer bimorph is used. However, as long as the necessary vibration can be extracted, the type of polymeric piezoelectric material and the constituent layers of the bimorph can be changed. The number is arbitrary.

Effects of the Invention As described above, the present invention provides a polymer bimorph fan with a relatively simple configuration that can easily follow power supplies with frequencies that vary depending on the region.

[Brief explanation of the drawing]

FIGS. 1, 3, and 4 are perspective views showing embodiments of the present invention, and FIG. 2 is an explanatory diagram of the laminated structure of a bimorph diaphragm and its connection to a power source. 1, 2, 11, 12...bimorph diaphragm, 1
1 to 16...Polymer piezoelectric film, 3...Jig, 4
a, 4b...Terminal, 6...AC power supply. Representative figure: Figure 1.

Claims (1)

[Claims for Utility Model Registration] 1. Bimorph diaphragms consisting of a plurality of polymer bimorphs with different effective vibration lengths from the fixed part to the tip of the vibrating part are fixed to a jig in close proximity to each other, and each is connected to an AC power source. A bimorph fan who is characterized by 2. The bimorph fan according to claim 1, which uses two bimorph diaphragms. 3. The bimorph fan according to claim 2, wherein the two bimorph diaphragms are fixed to a jig so that they are substantially coplanar in a resting position. 4. The bimorph fan according to claim 2, wherein the two bimorph diaphragms are fixed to a jig so that their main surfaces are substantially parallel in the rest position. 5. According to claim 4 of the utility model registration, two bimorph diaphragms are formed by folding one continuous bimorph so that they are almost parallel to each other and fixing the folded parts to a jig. Bimorph fan described. 6 The effective vibration length of the two bimorph diaphragms is
Utility model registration claims Paragraph 2~ whose lengths give resonance frequencies of 50 Hz and 60 Hz, respectively.
The bimorph fan according to any of paragraph 5.