JP2004289880A - Piezoelectric motor and fan using piezoelectric motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric motor that has high efficiency while having a simple constitution. <P>SOLUTION: A piezoelectric motor 10 is equipped with a stator 11 where a parallelogram constantly elastic body 20 is caught with two sheets of piezoelectric ceramics 30 and 40, and a columnar rotor 12 which contacts with one side of the parallelogram, and is formed with a projection 21 at the vertex of a parallelogram. More specifically, the parallelogram has acute vertexes 22, obtuse vertexes 23, short sides 24 and long sides 25, and the two sheets of piezoelectric ceramics 30 and 40 to sandwich the constantly elastic body 20 exposing the short sides 24 which include the acute vertexes 22 to the outside, and the rotor 12 makes contact with the vicinity of the projection 21 of the short side 24, and the projection 21 is formed at the acute vertex 22. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a piezoelectric motor that operates by a piezoelectric effect, and a fan using the piezoelectric motor.
[0002]
[Prior art]
(1). When the piezoelectric ceramic is made into a parallelogram (that is, obliquely symmetric), the longitudinal vibration and the bending vibration are combined to generate a circular motion or an elliptical motion on one side of the parallelogram. Then, a piezoelectric motor can be configured by bringing a rotating shaft into contact with one side of the parallelogram. A piezoelectric motor including such a parallelogram-shaped stator made of piezoelectric ceramics and a rotor in contact with one side of the parallelogram is known (Non-Patent Document 1 below).
[0003]
(2). 2. Description of the Related Art Fans using an electromagnetic motor are widely used for cooling electric equipment. However, there has been a case where components of the electronic device malfunction due to electromagnetic noise generated from the electromagnetic motor. In order to solve this problem, there has been known an example in which a fan is configured by using a piezoelectric motor that does not generate electromagnetic noise in principle (Japanese Patent Application Laid-Open No. H11-163,837).
[0004]
[Non-patent document 1]
Aoyagi, Tomikawa, "Ultrasonic motor using longitudinal-bending coupled vibration of obliquely symmetric piezoelectric plate", IEICE Transactions on Electronics, CI, November 1995, Vol. J78-CI, No. 11, pp. 560-566
[Patent Document 1]
JP-A-5-275876 (FIG. 3 etc.)
[0005]
[Problems to be solved by the invention]
However, although the piezoelectric motor described in Non-Patent Document 1 has a simple structure and is suitable for miniaturization and weight reduction, the efficiency is still insufficient.
[0006]
Further, the piezoelectric motor used in the fan described in Patent Document 1 has an extremely complicated structure including a rotor integrated with the impeller and a disk-shaped vibrator having a center different from that of the impeller. In addition, the vibrator has substantially the same area as the entire impeller, and has a considerably large thickness in order to have strength in its size. Therefore, the fan itself is large, heavy and thick.
[0007]
[Object of the invention]
Therefore, a first object of the present invention is to provide a “piezoelectric motor” having a simple configuration and high efficiency. A second object of the present invention is to provide a "fan using a piezoelectric motor" which realizes a reduction in thickness, size, weight, and efficiency.
[0008]
[Means for Solving the Problems]
First, the “piezoelectric motor” according to the present invention will be described.
[0009]
A piezoelectric motor according to the present invention (Claim 1) includes a stator in which a parallelogram-shaped constant elastic body is sandwiched between two pieces of piezoelectric ceramics, and a cylindrical rotor in contact with one side of the parallelogram. A projection is provided at the vertex of the shape. For example, a parallelogram has acute and obtuse angle vertices and short sides and long sides, and two piezoelectric ceramics have a short side including an acute angle vertices outside and sandwich a constant elastic body, and a rotor has a short side. The projection is provided at the vertex of the acute angle.
[0010]
When the piezoelectric ceramic is made into a parallelogram, the longitudinal vibration and the bending vibration combine to generate a circular motion or an elliptical motion on one side of the parallelogram. When the rotor contacts one side of the parallelogram, the rotor rotates. At this time, if the protrusion is provided at the vertex of the parallelogram, the protrusion is bent and the displacement is enlarged. In addition, the elastic deformation of the protruding portion when the rotor is stuck makes it easy to cause deformation from longitudinal vibration to bending vibration or the reverse mode. Therefore, the circular or elliptical locus of the displacement increases, and the driving efficiency (rotational efficiency) improves.
[0011]
In other words, the protruding portion is set to have a length at which the longitudinal vibration displacement is amplified and transformed, and has a configuration in which the in-plane bending vibration mode is degenerated. As a result, the longitudinal vibration velocity can be amplified and transformed, so that the in-plane flexural vibration velocity of the projections which are excited accompanyingly increases. Therefore, even higher speed rotation can be obtained by sticking the rotor with the tip of the protrusion having a higher vibration speed.
[0012]
Next, a “fan using a piezoelectric motor” according to the present invention will be described.
[0013]
A fan according to the present invention (claim 3) rotates an impeller using a piezoelectric motor. The piezoelectric motor includes a columnar rotor and a stator that is provided in a radial direction of the rotor and provides a rotational force in contact with the rotor. Further, the rotor is the rotating shaft of the impeller, or the rotor is connected to the rotating shaft of the impeller. The stator may have any shape such as a bar, a plate, a triangle, a square, a polygon, a circle, an ellipse, and the like.
[0014]
In a conventional fan using an electromagnetic motor, the center of the electromagnetic motor must be set in the direction of the rotation axis of the impeller, and this point has hindered the reduction in thickness. This problem also applies to the fan using the piezoelectric motor described in Patent Document 1 described above. On the other hand, in the fan according to the present invention, since the piezoelectric motor is installed in the radial direction of the rotation shaft of the impeller, it is easy to reduce the thickness.
[0015]
A fan according to the present invention (claim 4) rotates an impeller using a piezoelectric motor. The piezoelectric motor has a stator in which a parallelogram-shaped constant elastic body is sandwiched between two pieces of piezoelectric ceramics, and a columnar rotor in contact with one side of the parallelogram. Further, the rotor is the rotating shaft of the impeller, or the rotor is connected to the rotating shaft of the impeller. For example, a parallelogram has acute and obtuse angle vertices and short sides and long sides, and two piezoelectric ceramics have a short side including an acute angle vertices outside and sandwich a constant elastic body, and a rotor has a short side. (Claim 5).
[0016]
In the piezoelectric motor used for the fan according to the present invention, the stator comes into contact with the outer periphery of the columnar rotor. Therefore, in the fan according to the present invention, since the piezoelectric motor is installed in the radial direction of the rotation shaft of the impeller, it is easy to reduce the thickness.
[0017]
The piezoelectric motor used in the fan according to the present invention may be the above-described piezoelectric motor according to the present invention (claim 6). In this case, since the efficiency of the piezoelectric motor is high, the efficiency of the fan is also improved.
[0018]
Further, the impeller further includes a housing having an air inlet in the rotation axis direction of the impeller and having an air outlet in a radial direction of the impeller, wherein the impeller has an inner axial fan portion and an outer centrifugal fan portion. (Claim 7). Air is taken into the suction port from the rotation axis direction of the impeller, and is discharged from the discharge port in the radial direction of the impeller. In such a structure, the thinner the thickness, the easier the air flows back. In the present invention, since the inside of the impeller constitutes the axial fan portion, the air taken into the suction port is further pushed in the direction of the rotation axis of the impeller. Therefore, stagnation or backflow of the taken-in air can be prevented, so that the blowing capacity, that is, the efficiency, is improved. Along with this, it is possible to further reduce the thickness.
[0019]
Further, the housing may have a shape along a step formed at a joint between the axial fan unit and the centrifugal fan unit (claim 8). In this case, a gap between the axial fan unit and the centrifugal fan unit at the joint between the axial fan unit and the centrifugal fan unit is reduced. Therefore, stagnation or backflow of air in this portion can be prevented, and the blowing capacity, that is, efficiency is improved. Along with this, it is possible to further reduce the thickness.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
1 and 2 show an embodiment of the piezoelectric motor according to the present invention, wherein FIG. 1 [1] is a plan view, FIG. 1 [2] is a vertical sectional view taken along the line II in FIG. FIG. 2 is a partially enlarged view of FIG. 1 [1] showing an operation principle. Hereinafter, description will be made based on these drawings.
[0021]
The piezoelectric motor 10 of the present embodiment includes a stator 11 in which a parallelogram-shaped constant elastic body 20 is sandwiched between two pieces of piezoelectric ceramics 30 and 40, and a columnar rotor 12 that is in contact with one side of the parallelogram. The projection 21 is provided at the apex of the parallelogram. Specifically, the parallelogram has an acute angle vertex 22 and an obtuse angle vertex 23, and a short side 24 and a long side 25, and the two piezoelectric ceramics 30 and 40 project the short side 24 including the acute angle vertex 22 outside. The rotor 12 is in contact with the protruding portion 21 on the short side 24 or in the vicinity thereof, and the protruding portion 21 is provided on the long side 25 side of the acute angle vertex 22.
[0022]
The constant elastic body 20 is a stainless plate. The piezoelectric ceramics 30 and 40 are rectangular plates made of a commercially available general material, and electrodes 31 and 32 are provided on surfaces that are not in contact with the constant elastic body 20, respectively. The constant elastic body 20 and the piezoelectric ceramics 30 and 40 are fixed via a conductive adhesive. In addition, since the structure is such that the constant elastic body 20 is sandwiched between the piezoelectric ceramics 30, 40, the relatively brittle piezoelectric ceramics 30, 4 can be easily supported while maintaining high rigidity. As a result, the piezoelectric ceramics 30 and 40 can be made thinner, so that the piezoelectric motor 10 can be made thinner and the driving voltage can be made lower.
[0023]
The protrusion 21 has a parallelogram shape like the constant elastic body 20. When the length of the short side and the length of the long side of the projection 21 are, for example, 1/10 to 1/20 of the short side 24 and the long side 25 of the constant elastic body 20, favorable performance can be obtained. As an example of actual dimensions, the acute angle is 60 °, the obtuse angle is 120 °, the short side 24 is 6.7 mm, the long side 25 is 14.8 mm, and the thickness of the stator 11 is 0.9 mm.
[0024]
Next, the operation of the piezoelectric motor 10 will be described.
[0025]
As shown in FIG. 1 [2], a rectangular wave voltage is applied from the power supply 13 so that the electrodes 31 and 32 become positive electrodes and the constant elastic body 20 becomes a negative electrode. Then, when a voltage is applied to the piezoelectric ceramics 20, 30, the longitudinal vibration and the bending vibration of the piezoelectric ceramics 20, 30 are combined to generate a displacement 26 (FIG. 2) on the short side 24 of the constant elastic body 20. . As a result, a circular motion 27 (FIG. 2) occurs on the short side 24, and the rotor 12 in contact with the short side 24 rotates (arrow 28).
[0026]
At this time, if the protrusion 21 is provided on the vertex 22 of the constant elastic body 20, the protrusion 21 is bent and the displacement 26 of the short side 24 is enlarged. In addition, the elastic deformation of the protruding portion 21 when the rotor 12 strikes makes it easy to cause deformation from longitudinal vibration to bending vibration or the reverse mode. As a result, the trajectory of the circular motion 27 of the displacement 26 is increased, so that the driving efficiency is improved.
[0027]
3 and 4 show a first embodiment of a fan according to the present invention. FIG. 3 is a plan view showing a state in which a cover is removed, and FIG. 4 is a vertical sectional view taken along line IV-IV in FIG. . Hereinafter, description will be made based on these drawings. However, the same parts as those in FIG.
[0028]
The fan 50 according to the present embodiment includes the piezoelectric motor 10, an impeller 60, a housing 70, and the like, and the rotor 12 serves as a rotation axis of the impeller 60. The impeller 60 includes a central disk portion 61, an inner axial fan portion 62, and an outer centrifugal fan portion 63. The housing 70 includes a lid 71 and a housing 72, and has an air inlet 73 in the rotation axis direction of the impeller 60 and an air outlet 74 in a radial direction of the impeller 60.
[0029]
The stainless steel plate constituting the constant elastic body 20 is extended from the center of the stator 11 in the lateral direction to form support portions 51 and 52. The tips of the support parts 51 and 52 are fixed to the housing part 72 by screws 53 and 54. A long hole 55 for position adjustment is provided at the tip of the support portion 51. The rotor 12 is made of ceramics and is supported by pivot bearings 56 and 57 also made of ceramics.
[0030]
The impeller 60 is made of a synthetic resin. In the vertical direction in FIG. 4, the blades of the axial flow fan unit 62 rise obliquely along the rotation direction of the impeller 60 (arrow 28) and curve downward (hereinafter, “arc-shaped”). It is.) The blades of the centrifugal fan unit 63 have a vertically upright shape.
[0031]
The lid 71 has a square plate shape, and has a circular inlet 73 opened in the center. Further, the lid 71 has a shape along a step generated at a joint between the axial fan 62 and the centrifugal fan 63. Therefore, the gap between the lid 71 and the joint between the axial fan 62 and the centrifugal fan 63 is small. The accommodation section 72 has a flat rectangular parallelepiped shape, does not have an upper surface, and has an outlet 74 on one side. A lid 71 is fixed to the upper surface of the housing 72 with a screw or the like. To describe an example of the actual dimensions of the size of the housing 70, the vertical and horizontal directions shown in FIG. 3 are each 35 mm, and the thickness shown in FIG. 4 is 5 mm.
[0032]
Next, the operation of the fan 50 will be described.
[0033]
The air 58 is taken into the suction port 73 from the upper surface of the housing 70, that is, from the rotation axis direction of the impeller 60. The air 59 is discharged from the discharge port 74 in the side surface of the housing 70, that is, in the radial direction of the impeller 60. At this time, since the inside of the impeller 60 is the axial fan portion 62, the air 58 introduced into the suction port 73 is further pushed in the direction of the rotation axis of the impeller 60. Therefore, stagnation or backflow of the taken-in air 58 can be prevented, and the blowing capacity, that is, the efficiency, is improved.
[0034]
Further, in the piezoelectric motor 10, the stator 11 comes into contact with the outer periphery of the columnar rotor 12. Therefore, in the fan 50, since the piezoelectric motor 10 is installed in the radial direction of the rotation shaft of the impeller 60, the thickness can be easily reduced. Further, since the piezoelectric motor 10 according to the present invention is used, the efficiency of the fan 50 is improved.
[0035]
In other words, the fan 50 has a shape in which the axial fan portion 62 and the centrifugal fan portion 63 are combined. On the outside of the impeller 60, the blades are stepped, and the lid 71 is covered along the blades in order to effectively exert the effect of the centrifugal fan unit 63. The axial fan portion 62 has a blade having an arc shape so that the air 58 once taken in does not flow back to the suction port 73. Further, by making the blades of the axial flow fan portion 62 arc-shaped, the arc portion of the blades functions as a lid, so that the effect of the centrifugal fan portion 63 also works effectively.
[0036]
When the impeller 60 was used, the airflow was about twice as large as that when the conventional centrifugal fan impeller was used. Further, by using the ceramic rotor 12 and the pivot bearings 56 and 57, the rotation of the fan 50 starts up smoothly (that is, the rotation speed is stabilized).
[0037]
FIG. 5 [1] is a schematic configuration diagram showing a second embodiment of the fan according to the present invention, and FIG. 5 [2] is a schematic configuration diagram showing a conventional fan. Hereinafter, description will be made based on these drawings.
[0038]
The conventional fan 90 includes an electromagnetic motor 91, an impeller 92, and the like, and has a structure in which air 93 is sucked in from a rotation axis direction of the impeller 92 and discharged in a radial direction of the impeller 92. However, this structure has the following problems. In order to reduce the thickness of the fan 90, an electromagnetic motor 91 must be provided on the air suction side. Then, the presence of the electromagnetic motor 91 impedes the flow of air. That is, since the electromagnetic motor 91 is disposed on the suction port side to block the air flow path, the air flow is restricted.
[0039]
On the other hand, the fan 80 of the present embodiment includes the piezoelectric motor 81, the impeller 82, and the like according to the present invention, sucks the air 83 from the rotation axis direction of the impeller 82, and Is discharged. In the fan 80, since the piezoelectric motor 81 is extremely thin, the piezoelectric motor 81 can be arranged below the impeller 82. Since there is no flow path for the air 83 below the impeller 82, the piezoelectric motor 81 does not hinder the flow of the air 83. In addition, since the piezoelectric motor 81 is held below the impeller 82, a large space is created on the suction port side, and the air volume increases.
[0040]
It is needless to say that the present invention is not limited to the above embodiment. For example, the piezoelectric motor used in the fan according to the present invention is not limited to the piezoelectric motor according to the present invention, and may be another conventional piezoelectric motor.
[0041]
【The invention's effect】
According to the piezoelectric motor of the present invention, the stator includes a stator in which a parallelogram-shaped constant elastic body is sandwiched between two piezoelectric ceramics, and a columnar rotor in contact with one side of the parallelogram. Since the projection has a circular locus or an elliptical locus of displacement, the efficiency can be improved.
[0042]
According to the fan according to the present invention, since the piezoelectric motor is installed in the radial direction of the rotation shaft of the impeller, the thickness can be reduced. Therefore, reduction in size and weight can also be realized. Further, when the piezoelectric motor according to the present invention is used, the efficiency of the fan can be improved since the efficiency of the piezoelectric motor is high. Further, when an impeller having an inner axial fan portion and an outer centrifugal fan portion is used, stagnation or backflow of the taken-in air can be prevented, so that the blowing capacity can be improved. Along with this, further thinning can be realized. At this time, when the shape along the step of the joint between the axial fan portion and the centrifugal fan portion is applied to the housing, stagnation or backflow of air in this portion can be prevented, so that the efficiency can be further improved. , Can be made thinner [Brief description of drawings]
1 shows an embodiment of a piezoelectric motor according to the present invention, wherein FIG. 1 [1] is a plan view, and FIG. 1 [2] is a vertical sectional view taken along the line II in FIG. 1 [1].
FIG. 2 is a partially enlarged view of FIG. 1 [1] showing an operation principle of the piezoelectric motor of FIG. 1;
FIG. 3 is a plan view of the fan according to the first embodiment of the present invention, with a lid removed.
FIG. 4 is a vertical sectional view taken along line IV-IV in FIG. 3;
FIG. 5 [1] is a schematic configuration diagram showing a second embodiment of a fan according to the present invention, and FIG. 5 [2] is a schematic configuration diagram showing a conventional fan.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Piezoelectric motor 11 Stator 12 Rotor 20 Constant elastic body 21 Protrusion part 22 Vertex of acute angle 23 Vertex of obtuse angle 24 Short side 25 Long side 30, 40 Piezoelectric ceramics 50 Fan 60 Impeller 62 Axial fan part 63 Centrifugal fan part 70 Housing 73 Inlet 74 Outlet

Claims (8)

A stator comprising a parallelogram-shaped constant elastic body sandwiched between two pieces of piezoelectric ceramics, and a columnar rotor in contact with one side of the parallelogram, wherein a protrusion is provided at a vertex of the parallelogram,
Piezo motor. The parallelogram has acute and obtuse vertices and short sides and long sides, and the two piezoelectric ceramics extend out of the short side including the acute vertices and sandwich the constant elastic body. Is in contact with the short side, the protrusion is provided at the apex of the acute angle,
The piezoelectric motor according to claim 1. In a fan that rotates an impeller using a piezoelectric motor,
The piezoelectric motor has a columnar rotor and a stator that is provided in a radial direction of the rotor and provides a rotational force in contact with the rotor,
The rotor is a rotating shaft of the impeller, or the rotor is connected to a rotating shaft of the impeller,
A fan characterized by that. In a fan that rotates an impeller using a piezoelectric motor,
The piezoelectric motor has a stator in which a parallelogram-shaped constant elastic body is sandwiched between two pieces of piezoelectric ceramics, and a columnar rotor in contact with one side of the parallelogram,
The rotor is a rotating shaft of the impeller, or the rotor is connected to a rotating shaft of the impeller,
A fan characterized by that. The parallelogram has acute and obtuse vertices and short sides and long sides, and the two piezoelectric ceramics extend out of the short side including the acute vertices and sandwich the constant elastic body. Is in contact with the short side,
The fan according to claim 4. In a fan that rotates an impeller using a piezoelectric motor,
The piezoelectric motor is the piezoelectric motor according to claim 1 or 2,
The rotor is a rotating shaft of the impeller, or the rotor is connected to a rotating shaft of the impeller,
A fan characterized by that. The impeller further includes a housing having an air inlet in a rotation axis direction of the impeller and having an air outlet in a radial direction of the impeller, wherein the impeller has an inner axial fan portion and an outer centrifugal fan portion. Having,
The fan according to claim 3. The housing has a shape along a step generated at a joint between the axial fan unit and the centrifugal fan unit,
The fan according to claim 7.

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