JPH1066364A - Small size motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small size motor having no exciting coil. SOLUTION: A rotor 10 consisting of a rotatable permanent magnet is provided around a rotary shaft 9. At least one pair of stators 5, 6, 7 and 8 are provided in a plane vertical to the rotary shaft 9 at approximately equal intervals. The stators 5, 6, 7 and 8 have identical construction. Each stator has a magnetic force control device, a permanent magnet and a piezoelectric device which are piled in series and housed in a housing. The respective tip parts 1a of the magnetic force control devices of the facing stators have the same polarity and face rotor 10. By applying a voltage successively to the stators 5, 6, 7 and 8 successively clockwise, the rotor 10 can be turned clockwise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a configuration of a small motor used for a timepiece and a small portable device which requires further miniaturization in the future.

[0002]

2. Description of the Related Art A conventional driving force generating mechanism for a small motor comprises a rotor composed of a permanent magnet and a stator composed of an exciting coil, similarly to a large motor. The small motor causes an exciting current to flow through the exciting coil to generate a magnetic field, and rotates the rotor using the magnetic force generated between the exciting coil and the magnetic moment as a driving force.

[0003]

To reduce the size of the exciting coil, it is desirable to reduce the diameter of the conducting wire. However, if the diameter of the conducting wire is less than 10 μm, the conducting wire is likely to be cut, which is not practical.

[0004] Further, since the coil may require a considerably large number of turns, it is difficult to reduce the size of the exciting coil. Since the exciting coil occupies a large volume in the configuration of the motor, it is difficult to reduce the size of the entire motor unless the exciting coil can be reduced in size.

[0005] An object of the present invention is to solve the above-mentioned problem and to provide a small motor which can be downsized as a whole by eliminating an excitation coil.

[0006]

In order to achieve the above object, a small motor according to the present invention employs the following configuration.

A small motor according to the present invention includes a rotor composed of a permanent magnet, and a stator in which a permanent magnet, a piezoelectric element, and a magnetic force control element whose magnetic permeability changes due to pressure generated by displacement of the piezoelectric element are stacked. It is characterized by the following.

Further, the small motor according to the present invention is characterized in that it has a mechanism for canceling the magnetic force due to the residual magnetic permeability of the magnetic force control element.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a configuration of a stator used for a small motor according to an embodiment of the present invention. FIG. 2 is a front view of the small motor according to the embodiment of the present invention, and shows a state where almost no force is applied to the rotor. 3 shows a state in which a voltage is applied to one of the stators in FIG. 2, and FIG. 4 shows a state in which a voltage is applied to another one of the stators in FIG. FIG. 5 is a waveform diagram showing timing for applying a voltage to the stator.

In FIG. 1, reference numeral 1 denotes a cylindrical magnetic force control element whose magnetic permeability changes when pressure is applied, and has a tip portion 1a having a small diameter. Reference numeral 2 denotes a cylindrical permanent magnet having magnetic poles in a cylindrical axis direction, and reference numeral 3 denotes a cylindrical piezoelectric element which is displaced in a cylindrical axis direction by an applied voltage. The cylindrical magnetic force control element 1 is placed in contact with one magnetic pole of the permanent magnet 2. Further, the cylindrical piezoelectric element 3 is placed in contact with the other magnetic pole of the permanent magnet. Reference numeral 4 denotes a cylindrical housing that encloses the magnetic force control element 1, the permanent magnet 2, and the pressure transmission element 3 stacked in the cylindrical axis direction without any gap.
However, only the tip 1a is not covered. Here, the magnetic force control element 1
The reason why the portion 1a is not covered with the housing 4 is to expose a portion (1a) having a high magnetic permeability to the outside of the housing 4. At this time, the housing 4 and the magnetic force control element 1 covered with the housing 4 and the housing 4
The permanent magnet 2 covered by the housing 4 and the piezoelectric element 3 covered by the housing 4 and the housing 4 are not joined to each other. The housing 4
Is made of a highly rigid material in order to convert the displacement generated by the piezoelectric element 3 into pressure. The housing 4 is made of a material having a low magnetic permeability such as SUS304 in order to prevent the magnetic force from wrapping around. Reference numeral 5 denotes a stator as a magnetic force control mechanism including a magnetic force control element 1, a permanent magnet 2, and a pressure transmission element 3.

In this embodiment, a case where a high magnetostrictive material (TbDy) Fe is used as a magnetic force control element will be described. (TbDy) Fe has the property that the magnetic permeability changes when a pressure is applied in the direction of the magnetic field, and when a pressure of about 10 MPa is applied, the magnetic permeability changes by about 30%.

In this configuration, when a voltage is applied to the piezoelectric element 3, the piezoelectric element 3 is displaced in the axial direction, so that pressure is applied to the magnetic force control element 1 via the permanent magnet 2. Thereby, the magnetic permeability of the magnetic force control element 1 changes, and the magnitude of the magnetization of the magnetic force control element 1 generated by the magnetic field generated by the permanent magnet 2 changes. This results in a change in the magnetic field. Therefore, the permanent magnet 2
Will change on the opposite side of the contact surface of the magnetic force control element 1 in contact with the permanent magnet 2. As a result, the magnetic force generated by the permanent magnet 2 can be controlled by the applied voltage.

In the conventional motor, the excitation coil is used for controlling the magnetic force on the stator side, but in the present invention, the magnetic force is controlled using the stator which is the magnetic force control mechanism described here.

In FIG. 2, reference numeral 5 denotes the stator shown in FIG. 1, and reference numerals 6, 7, and 8 denote stators having the same configuration as 5.
Reference numeral 10 denotes a rotor composed of a permanent magnet having a pair of magnetic poles of an N pole and an S pole, and 9 denotes a rotation axis. The rotor 10 is rotatably supported via a rotation shaft 9.

In this embodiment, the stators 5, 6,
With the tip 1 a of the magnetic force control element 1 oriented in the direction of the rotation axis 9 in a plane perpendicular to the rotation axis 9, the distance between the tip 1 a and the center of the rotation axis 9 is set to the radius of the rotor 10. At a slightly larger distance, they are arranged at regular intervals of approximately 90 degrees in the rotation direction. Here, the reason why the distance between the rotor 10 and each of the stators 5, 6, 7, and 8 is reduced is to effectively use the magnetic force.

Although the magnetic permeability of (TbDy) Fe decreases when pressure is applied, its value cannot be extremely reduced as a property of this substance. Therefore, in the stator of this embodiment, the magnetic permeability always exceeds a certain value.
This constant value will be referred to as the residual magnetic permeability. (TbD
y) The permeability of Fe is about 4 to 6 times the vacuum permeability, and the permeability remains about 4 times the vacuum permeability even in the lowest state.

In FIG. 2, the permanent magnets of the two opposing stators 5 and 7 and 6 and 8 have the same magnetic pole on the rotor 10 side, and in an environment where no voltage is applied to any of the stators, The arrangement is such that the forces in the rotational direction exerted on the rotor 10 by the two opposing permanent magnets cancel each other. With this configuration, the stators 5, 6, which work on the rotor 10,
The magnetic forces due to the residual magnetic permeability possessed by 7, 8 can be canceled out, and a state is created in which almost no force is applied to the rotor 10 in the rotational direction.

Next, the operation of the small motor will be described. In FIG. 5, V5, V6, V7, and V8 denote voltage waveforms applied to the stators 5, 6, 7, and 8, respectively, and the period during which the waveform rises represents the period during which a voltage is applied.

First, no voltage is applied to any of the stators. For example, at the timing T0 in FIG. 5, the magnetic forces due to the residual magnetic permeability between the opposing stators cancel each other out, and the rotor 10 rotates. Since no force is applied, the rotor 10 is stopped (FIG. 2). When the voltage V6 is applied to the piezoelectric element of the stator 6 at the timing of T1, pressure is applied to the magnetic force control element of the stator 6 via the permanent magnet, and the magnetic permeability of the magnetic force control element decreases in the direction in which the magnetic force decreases. , The balance of magnetic force between the opposing stator 8 is lost, and the S pole of the rotor 10 is attracted to the N pole of the stator 8. For this reason, the rotor 10 rotates clockwise from the direction of FIG. 2 (FIG. 3).

Further, at the timing of T2, the voltage V6 applied to the stator 6 is cut off, the pressure applied to the magnetic force control element is removed, and at the same time, the voltage V7 is applied to the adjacent stator 7 in the clockwise direction. When pressure is applied to the magnetic force control element,
The magnetic balance between the stators 6, 8 is restored, and the stators 5, 7
The rotor 10 further rotates clockwise by 90 degrees under the influence of the newly generated magnetic imbalance similar to that described above (FIG. 4).

Further, by successively applying voltages V8, V5, V6, and V7 to the stators 8 and 5 sequentially as shown in FIG. 5, the rotor 10 continuously rotates clockwise and serves as a motor. Can work. If the direction of the voltage application is changed, the rotation can be reversed, and the rotation speed can be naturally adjusted by changing the frequency of the voltage application.

In the embodiment of FIG. 2, the stators 5, 6, 7,
Although all the N poles of the eight permanent magnets are directed to the direction of the rotor 10, a configuration in which all the N poles are replaced with S poles may be adopted. In order to cancel the magnetic force due to the residual magnetic permeability between the stators arranged opposite to each other, it is sufficient that the magnetic poles of the permanent magnets facing the rotor 10 are the same. The magnetic poles of the stator towards the rotor 10 need not all be the same.

FIG. 6 is a front view of a small motor having two stators according to another embodiment of the present invention.
(A) shows a state where almost no force is applied to the rotor. FIG. 6B shows a state in which a voltage is applied to one stator, and FIG. 6C shows a state in which a voltage is applied to the other stator.

In FIG. 6, reference numerals 9, 10, 11 and 12 denote a rotating shaft, a rotor and an opposing stator having the same structure as in FIG. 1, and 13 denotes a very small piece of soft magnetic material. The position where the small pieces 13 are arranged is determined by rotating the stator 1 in the rotation direction.
1 and 12 (here, closer to the stator 12). Here, the force in the rotation direction due to the magnetic force acting between the small piece 13 and the magnetic pole of the rotor 10 is fixed to the stators 11 and 12.
Is smaller than the force in the rotational direction caused by the difference between the magnetic force of the large magnetic force and the magnetic force of the small magnetic force.

In FIG. 6A, one of the magnetic poles (N pole in this case) of the rotor 10 is at a position close to the small piece 13. In FIG. 6B, when a voltage is applied to the stator 11, the magnetic force of the stator 11 decreases due to a change in the magnetic permeability, and the rotation direction acting on the rotor 10 due to the difference between the other stator 12 and the magnetic force of the stator 11. Force overcomes the holding force in the rotating direction acting on the rotor 10 by the small pieces 13, and the S pole of the rotor 10 is attracted to the N pole of the stator 12. As a result, the rotor 10 rotates counterclockwise from the direction shown in FIG. Leads to. Once the applied voltage is removed here, the stator 1
As shown in FIG. 6 (c), the rotor 10 further rotates counterclockwise because the torques of the rotors 1 and 12 cancel each other and do not act on the rotor 10. S pole) is attracted to the small piece 13. At this point, it is clear that when a voltage is applied to the stator 12, the rotor 10 further rotates counterclockwise.

In order to rotate the rotor 10 clockwise, the small pieces 13 are previously arranged at a position rotated 90 degrees counterclockwise from the position in FIG.
The stator to which the voltage is applied first may be 12. Thus, the selection of the stator to which the voltage is first applied and the small pieces 13
It has been shown that the rotation direction of the rotor 10 can be controlled by the addition and the arrangement thereof.

In the case of four stators, except for a mechanism for controlling the rotation direction, it can be considered as a combination of the mechanisms of the two stators. Similarly, when N is a natural number, 2 × N Constituting a motor having a plurality of stators, sequentially applying an applied voltage to a plurality of piezoelectric elements to cause displacement, changing the magnetic force of the corresponding stator by the displacement, and between the stator and the rotor. Obviously, the rotor can be rotated in either direction by changing the applied force and turning the change clockwise or counterclockwise as viewed from the axis of rotation.

Further, in the embodiment of the present invention, the shape of the stator is a cylindrical shape which is easy to process. However, a polygonal prism may be used, and the shape may be a flat plate or the like according to the design of the motor. There are no particular restrictions.

As described above, the piezoelectric element used in the embodiment of the present invention includes barium titanate, lead zirconate titanate,
Piezoelectric ceramics such as multi-component solid solution ceramics,
Any material exhibiting piezoelectricity such as barium titanate single crystal, quartz, Rochelle salt, etc. may be used.

Further, the magnetostrictive material used as the magnetic force control element in the embodiment of the present invention has a large magnetostriction (TbDy) F.
e, especially those having anisotropy in the crystal are advantageous,
Any substance, such as an alloy of a rare earth metal and a transition metal such as TbFe2, DyFe2, and SmFe2, a magnetic oxide, and a fluoride, which has a large change in magnetic permeability due to pressure, may be used. In FIG. 1, the tip 1a of the magnetic force control element does not necessarily need to be made of a magnetostrictive material, but may be made of a soft magnetic material with good workability and high magnetic permeability, which is joined to the magnetostrictive material. good.

In the future, if a material that can control the magnetic force and change the magnetic permeability from ferromagnetic to paramagnetic is discovered,
Further, a more efficient small motor can be provided.

[0032]

As is apparent from the above description, the small motor according to the present invention converts the displacement of the piezoelectric element, which is displaced by the applied voltage, into pressure, and applies the pressure to the magnetic force control element to control and fix the magnetic force. Since the magnetic force of the child is changed and the rotor is rotated, a large coil is not necessary, and a small machine, for example, a small watch movement, a small portable device, or a pixel driven type by a motor, not too large display. A panel or the like can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a magnetic force control mechanism (stator) used for a small motor according to an embodiment of the present invention.

FIG. 2 is a front view showing a configuration of a small motor according to an embodiment of the present invention.

FIG. 3 is a front view illustrating the operation of the small motor in FIG. 2;

FIG. 4 is a front view illustrating the operation of the small motor in FIG. 2;

FIG. 5 is a waveform diagram of a driving voltage for rotating the small motor of FIG. 2;

FIG. 6 is a front view illustrating the operation of a small motor according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Magnetic force control element 1a Tip part 2 Permanent magnet 3 Piezoelectric element 4 Frame 5, 6, 7, 8, 11, 12 Magnetic force control mechanism (stator) 9 Rotating shaft 10 Rotor 13 Small piece V5, V6, V7, V8 Applied voltage T0, T1, T2, T3, T4, T5, T6, T7 Timing

Claims (2)

[Claims] 1. A rotor comprising a permanent magnet, and a stator in which a permanent magnet, a piezoelectric element, and a magnetic force control element whose magnetic permeability changes due to pressure generated by displacement of the piezoelectric element are stacked. Small motor. 2. The small motor according to claim 1, further comprising a mechanism for canceling a magnetic force due to a residual magnetic permeability of the magnetic force control element.