JPS59224500A - Piezoelectric fan - Google Patents

Abstract

PURPOSE:To aim at an increase in joining strength, by clamping a plate member between a pair of piezoelctric elements, and making an end part of the said plate member project from each end part of the paired piezoelectric elements, while setting the said projected part down to a vibrating part and widening a joining area between the plate member and these piezoelectric elements. CONSTITUTION:When an AC signal is impressed between a lead wire 5 and each of support plates 3 and 4, a paired piezoelectric element 1 is bent and vibrated and thereby a plate member 2 and a vibrating part 2a, that is, a part of (a) (see illustration) resonates, making a large amplitude of vibratin obtainable, whereby a flow of air is excited by this vibration. In this device, the plate member 2 consisting of polyethyleneterephtalate resin is held between a pair of piezoelectric elements 1 constituted of a zircon acid titanate porcelain, then locked together with a bonding agent, and an end part of the said member 2 is made to project from each end part of these piezoelectric elements 1, thus the vibrating part 2a is formed up. With this constitution, a joining area between the plate member 2 and these piezoelectric elements 1 become widened so that the joining strength increases.

Description

[Detailed Description of the Invention] The present invention relates to a piezoelectric fan using a piezoelectric element, and its uses include cooling electronic components, introducing small amounts of air, smoke, etc., and other applications that do not require a large air volume. use

Conventionally, this type of piezoelectric fan has a structure as shown in FIGS. 1 and 2, and by applying an alternating current signal to a pair of piezoelectric elements 1, the piezoelectric elements 1 bend and vibrate to excite wind. However, in order to increase the air blowing capacity, a diaphragm 2 is attached to the tip.

However, the conventional type has a problem in that the bonding strength between the diaphragm 2 and the piezoelectric element 1 is weak.

Therefore, in order to solve the above problems, the present invention fixes a plate member between a pair of piezoelectric elements, makes the end of the plate member protrude from the end of the pair of piezoelectric elements, and vibrates the protrusion. It was established as a department.

The present invention will be explained in detail below using specific examples. Third
In FIGS. 1 to 5, 1 is a piezoelectric element, which is made of, for example, lead zirconate titanate (PZT') porcelain.

1a is a thin film electrode made of Ag, Ni, Aj! A conductive metal such as the above is formed on both sides of the piezoelectric element 1 by a method such as printing, plating, or evaporation.

(2) b is a metal plate for ensuring electrical continuity between the electrode 1a and the lead wire 5; The material of this metal plate 1b is as follows:
A7! , Cu, Kovar, etc. may be used. In the figure, 10 indicates the polarization direction of the piezoelectric element l. 2 is a plate member, and its material is suitably polyethylene terephthalate resin. The piezoelectric element 1, the metal plate 1b, and the plate member 2 are bonded together with an adhesive and are combined together. Further, the piezoelectric elements 1 are bonded together so that the polarization directions 1c are in the same direction. Note that the end of the plate member 2 protrudes from the end of the piezoelectric element 1 and serves as a vibrating section 2a. The piezoelectric fan configured as described above is fixed to the case 7 by tightening the metal support plates 3 and 4 with the pinch screws 6. The support plate 3.4 also serves as an electrode,
It is electrically connected to the piezoelectric element 1 by, for example, soldering. The lead wire 5 described above is attached to the metal plate 1b with solder or the like.

In the above configuration, the operation will be explained next.

When an AC signal is applied between the lead wire 5 and the support plates 3 and 4, the piezoelectric element 1 bends and vibrates. If the alternating current signal is set appropriately, the vibrating portion 2a of the plate member 2, that is, the portion a in the figure, resonates, and a large amplitude can be obtained. This vibration excites the air flow.

The characteristics of the piezoelectric fan of the present invention are closely related to the ratio of the lengths of the plate member 2 and the piezoelectric element 1, and the thickness of the plate member 2, ie, t in FIG. 4.

FIG. 8 shows the relationship between the ratio of the piezoelectric element 1 to the overall length, that is, b/(a+b) in FIG. 4, and the air volume.
The thickness of the plate member 2 is 0.1 mm, 0.25 fin, and 0.5 mm. As shown in FIG. 8, the air volume has a maximum value at a value of b/(a+b). b/(
When a+b) is small, that is, when the ratio of piezoelectric element 1 to the entire length is small, the vibration form of the piezoelectric fan becomes as shown by the broken line in FIG. In other words, there is a large vibration gorge in which the vibrating portion 2a resonates, and the resonance of the piezoelectric element 1 is slight. Conversely, when b/(a+b) is larger than the point where the wind foot becomes maximum, that is, when the ratio of piezoelectric element 1 to the entire length is large, as the ratio of piezoelectric element 1 increases, The amplitude increases, and finally, as shown in FIG. 7, the piezoelectric element 1 and the plate member 2 come to resonate together. In this way, when the amplitude of the piezoelectric element 1 is large,
The piezoelectric element 1 deteriorates rapidly.

Furthermore, the piezoelectric fan of the present invention can be applied to a fan for introducing smoke into a smoke sensor that detects smoke from cigarettes, etc., a fan for introducing air into an internal temperature sensor that detects the temperature inside the vehicle interior of an automobile, etc. , and when considering these applications, b/(a
+b) The effective range of the plate thickness of the plate member 2 is shown in FIG. In Figure 9, the vertical axis is b/(a(-b). Point A (
Below the line connecting point B (10, 5/9) and point B (10, 5/9), the air volume is 0.5 n? / l (The following is the smoke sensor, internal temperature sensor, fan closure-C is not suitable due to insufficient air volume. Also, point C (to, 1/9) and point D (
2, 7/9), vibration forms as shown in FIG. 7 occur, which is undesirable because it causes shock and rapid deterioration of the element 1. In addition, when the thickness of the plate member 2 is thinner than 100 μm, that is, point B (10,5/9) and point C (10,7/
9) Since the plate member 2 is thinner on the right side of the line connecting
Significantly affected by dirt from cigarettes, etc. That is, the change in resonance frequency due to dirt adhering to the vibrating portion 2a is large. Conversely, if the thickness of the plate member 2 is thicker than 500 μm, that is, on the left side of the tie connecting point A (2, 2/9) and point D (2, 7/9), the plate member 2 and piezoelectric element 1 The difference in the thermal expansion coefficients of the two materials has a large effect, causing problems such as peeling of the bonded portion.

Note that the above characteristics are based on the total length of the piezoelectric fan, that is, a+b=4
In the fifth period, the thickness of the piezoelectric element 1 was 200 μl, and the applied voltage was 50 V r, m, s. Even if this total length is changed, the effective range shown in FIG. 9 remains the same. In other words, as the overall length increases, the deflection amplitude of the piezoelectric fan increases, but conversely, the resonant frequency decreases, so the air volume remains the same. Moreover, if the thickness of the piezoelectric element 1 is less than 100100I1, the ζ-strength is weak, and if it is more than 400 pm, a high applied voltage is required, which is not preferable.

Further, as the material for the plate key 2, polyethylene lenticule reflex 1 is suitable because it has excellent strength.

The piezoelectric fan of the present invention is not limited to the above-mentioned embodiments, but can be modified in various ways as described below.

(1) As shown in FIG. 10, instead of the metal plate 1b,
A part of the plate member 2 may be made into a metal plate 8 to ensure conduction with the electrode 1a.

(2) As shown in FIG. 11, instead of the metal plate 1b,
A metal 119 is buried in a part of the plate member 2 to ensure conduction with the electrode 1a.

(3) In Figure 4, the piezoelectric elements 1 are pasted together so that their polarization directions 1c are in the same direction, but as shown in Figure 12, they are pasted together so that their polarization directions 1c are opposite to each other. ze is also fine. In this case, A
An electrode 11 such as g is attached and sandwiched between the piezoelectric element 1 and the support plate 3. Take out the lead wire 5 from the electrode 11 and
A voltage is applied between the support plate 4 and the support plate 4. At this time, a lead wire 5' is required to ensure conduction between the two metal plates 1b.

As described above, according to the present invention, since the plate member is sandwiched between a pair of piezoelectric elements, the bonding area between the plate member and the piezoelectric element is wide, and therefore, the excellent effect of improving strength can be obtained. It will be done.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a conventional example, FIG. 2 is a sectional view of FIG. 1, FIG. 3 is a perspective view showing an embodiment of the present invention, FIG. 4 is a sectional view of FIG. 3, and FIG. The figure is a front view showing the installed state of the piezoelectric fan in FIG. 3, FIGS. 6 and 7 are schematic diagrams of the piezoelectric fan for explaining the operation of the present invention, and FIGS. 8 and 9 are for explaining the operation of the present invention. Characteristic diagrams, Figures 10 and 11
The figure is a partially broken perspective view showing another embodiment of the present invention.
FIG. 2 is a sectional view showing still another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Piezoelectric element, 2... Plate member, 2a... Vibration part, 3° 4... Support plate.

Claims (1)

[Scope of Claims] (11) A piezoelectric fan comprising a pair of piezoelectric elements coupled to each other and configured to blow air using bending vibration of the pair of piezoelectric elements, wherein a plate is provided between the pair of piezoelectric elements. The member is clamped and fixed, and the end of the plate member is made to protrude from the end of the pair of piezoelectric elements, and the 0ij small protruding end of the plate member is used as a vibrating part, and both sides of the pair of piezoelectric elements are nil. A piezoelectric fan with a support part provided on the (211iii) plate member is made of polyethylene terephthalate 4L1 resin material, and on the orthogonal coordinates, the horizontal axis is the reciprocal of the plate IK of the plate member (unit: ++n'), When the ratio of the length of the pair of piezoelectric elements to the length from the protruding end of the plate member No. 1111 to the part of the pair of piezoelectric elements excluding the stem portion No. 1111 is taken as the vertical axis. ,(
2,2/9), (10,5/!J), (10°7/9
), (2, 7/9), the thickness of the plate member and the length of the pair of piezoelectric elements excluding the support portion are set within a rectangular range connected by four points, (2, 7/9). Piezoelectric fan according to item 1.