JPS5832518B2 - piezoelectric motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the field of electrical engineering, and more particularly to motors.

There is a gap between the rotor and stator, the mechanical torque produced on the rotor is given by the interaction of electric and magnetic fields between the rotor and stator, and in the case of an inner rotor motor, the base to which the motor is glued A type of motor is known in which a rotor is attached to the inside of a stator that is stationary relative to the stator, and in the case of an outer rotor motor, a rotor is attached to the outside of the stator so that the rotor continuously rotates.

In the case of an outer rotor, the rotors are journal-coupled to the stator by bearings.

Known motors, in which the electric fields interact due to the presence of Coulomb forces between the rotor and stator charges, have no windings, but
Relatively low specific power rating and low efficiency.

Therefore, such motors are generally used only for display purposes.

Motors that operate by the interaction of magnetic fields generated by current flowing through rotor and stator windings are also known.

Such motors can be divided into two types.

One is a type of motor in which the current flowing through the rotor winding and the current flowing through the stator winding are supplied from an external power source, and the other is a type of motor in which the current flowing through the rotor winding is induced by the current flowing through the stator winding. This is the type of motor that is used.

In most cases, the first type of motor is a DC motor and the second type of motor is an AC motor.

A significant drawback of this type of motor is the inclusion of windings in its construction.

This complicates the manufacture of the motor and therefore increases costs.

Since the mechanical power output at the shaft of these motors is dependent on the gap between the stator and rotor, the cost of the motor increases as the requirements for manufacturing accuracy of the motor become more stringent.

When the output of the motor decreases, the inductance of the windings decreases, so the input resistance of the motor decreases, and the power supply voltage must be lowered accordingly, requiring a separate transformer.

Therefore, the total cost of equipment associated with these motors further increases.

Furthermore, the rotational speed of these motors is usually high (often over 100 Orpm) and therefore most require expensive reduction gears for practical applications.

The high cost of induction motors is also due to the complexity of manufacturing the stator and rotor, which are assembled from thin sheet materials made from alloys of iron and expensive metals such as nickel or manganese.

The high specific gravity of the rotor and stator components and the winding material copper is also the reason why the ratio of the total weight of the motor to the output at the output shaft is high, and this is especially true for small motors with an output of 10W or less. That's about it.

A large moment of inertia of the rotor makes it difficult to start and stop the motor quickly.

Also, the starting current is very high and may overload the power supply.

Additionally, these motors have low power factors, spark discharges between the commutator and brushes that create noise disturbances in other electrical circuits, low efficiency for small power motors, and the need for expensive bearings for high speed rotation. high temperatures and polluted atmospheres require special protection of the motor, operation in rarefied air and vacuum affects power ratings, and AC motors require low operating frequencies.

However, despite these drawbacks, these motors are widely used.

The reason is that there are no motors that can compete with electromagnetic motors in terms of large parameters such as output and efficiency.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to overcome the above-mentioned drawbacks.

Another object of the invention is to use piezoelectric devices capable of converting electrical power into mechanical energy in order to create a fundamentally new construction of motors.

These and other objects provide a stator and a rotor, the stator and rotor being pressed one against the other with a constant force such that a frictional contact is made between said stator and rotor; is a piezoelectric motor that operates on a rotor surface formed by a line segment rotation locus centered on the axis of rotation of the rotor, in which at least one piezoelectric vibrator that generates longitudinal vibration is provided on the stator; A portion of the surface of the piezoelectric vibrator is in frictional contact with at least a portion of the surface of the rotor;
The piezoelectric vibrator has polarization and a shape that causes longitudinal vibration and lateral vibration in the frictional contact portion, and one of the longitudinal vibration and lateral vibration drives the rotor,
The other is achieved by a piezoelectric motor characterized in that it changes the force acting between said stator and rotor.

The rotor of this motor is mounted to the stator by at least one bearing.

In order to bring the rotor and stator into continuous contact, the rotor has a body in which at least the portion of the surface that engages with the stator is formed by rotation of at least one extended straight line about the central axis of rotation of the rotor. is formed as.

It is convenient to form the entire rotor as a body that rotates about the axis of rotation of the rotor.

The support can be attached by an object whose product of density and Young's modulus is less than one-tenth of a similar product calculated for the material of construction of the piezoelectric element of the transducer.

The stator can incorporate a vibrator that performs longitudinal and transverse vibrations.

The stator can incorporate a vibrator that performs longitudinal vibration and bending vibration, a vibrator that performs torsional vibration and transverse vibration, a vibrator that performs torsional vibration and longitudinal vibration, and a vibrator that performs shear vibration and longitudinal vibration.

The rotor can be composed of a vibrator that performs transverse vibration and a vibrator that performs sliding vibration.

The vibrator can be fixed to a support at least at the lowest vibration speed.

The stator vibrator can be composed of a piezoelectric element.

The vibrator of the rotor can also be composed of a piezoelectric element.

A piezoelectric element of the stator oscillator can be provided in the area of engagement between the rotor and the stator, and the stator with a lining of wear-resistant material is acoustically coupled to the piezoelectric element.

The oscillator can be made in the form of a rectangular plate.

The stator oscillator can be made in the shape of a rond of decreasing cross-sectional area, and the rotor engages the oscillator at the end of the rond where the cross-sectional area is smallest.

The oscillator of the stator can be made in the form of a helical rotor, the rotor being located intermediate the ends of this helical rotor.

The piezoelectric element of the vibrator can have the same shape as the vibrator.

The wear-resistant lining can be in the form of a thin-walled cylinder.

A piezoelectric element can be formed from two acoustically coupled layers separated by at least one electrode.

The surface of one electrode can have a layer of metal acoustically coupled thereto.

Piezoelectric elements can be made of ferroelectric piezoelectric materials.

Piezoelectric elements can be made of ceramic materials.

A piezoelectric element can be polarized in a direction perpendicular to its electrodes and in a direction parallel to the electrodes.

The rotor and stator are pressed together by at least one resilient member, such as a spring.

One end of the elastic member can be attached to the support of the vibrator,
The other end can be attached to the vibrator itself.

Both ends of the elastic member can be attached to two vibrators of the stator or to the rotor.

A voltage can be applied to the electrodes of the piezoelectric elements of the vibrators belonging to the rotor via elastically biased contacts from a power source.

Electrodes can be coated on the cylindrical surfaces of hollow cylinders that are polarized in a direction perpendicular to them.

The piezoelectric element is polarized in the thickness direction and can be in the form of a disk with electrodes on the main surface.

The layers of piezoelectric elements can run parallel to the external electrodes and can be connected in parallel to each other.

Adjacent layers are polarized in opposite directions.

The rotor can be received symmetrically between two parallel piezoelectric plates.

These piezoelectric plates are pressed against the rotor by two springs attached to the frame on which the piezoelectric plates are mounted.

Each frame is one quarter of the length of the piezoelectric plate from the end of the piezoelectric plate.
These frames can move freely in the four grooves of the support.

Electrodes are provided on the main surface of the piezoelectric plate, and are polarized in two different directions in the thickness direction, and are mutually polarized in one direction.

The inner electrode and the outer electrode are connected to each other.

The piezoelectric element of the stator can symmetrically enclose the rotor inside it and can have electrodes on its cylindrical surface.

The piezoelectric elements are oppositely polarized in a direction perpendicular to their electrodes such that the polarization divides the piezoelectric element into an even number of equal parts.

A lining made of a wear-resistant material is mounted symmetrically on the inner surface of the piezoelectric element at the interface between the parts.

The number of those linings is half the number of said parts.

Two piezoelectric elements can be mounted on the shaft of the rotor with respect to the stator.

Electrodes are attached to the sides of these piezoelectric elements.

These piezoelectric elements can be moved axially and are polarized in a direction perpendicular to the electrodes.

The piezoelectric element is pressed against a stator lining made of wear-resistant material.

The transverse cylindrical shape of these linings is made into an isosceles triangle, and the internal and external electrodes of the piezoelectric elements are connected to each other.
The piezoelectric elements are polarized in opposite directions.

The stator may include two oscillators in the form of two-layer piezoelectric plates with openings.

The rotor is pressed against the piezoelectric plates and the shut extends through the openings.

The piezoelectric element is a vibrator that generates a second harmonic of vertical vibration of the piezoelectric plate in the longitudinal direction and a second harmonic of bending vibration of the piezoelectric plate in the width direction.

The piezoelectric element has a common electrode connected to one electrode of the power source, one electrode connected to the other electrode of the power source for exciting one type of vibration, and one electrode connected to the other electrode of the power source for exciting one type of vibration. and a second electrode.

This second electrode is connected to the first electrode via a two-circuit selection switch.

The second electrode can be connected directly via a selection switch or further via an inverter or transformer.

Of the four electrodes of the motor, two electrodes are used to excite one type of vibration and are connected to a power source.

The other two electrodes are for exciting other types of vibrations and are connected to the power supply via a double-pole, double-throw switch.

The piezoelectric element can include at least one additional electrode connected to a load.

The stator vibrator may include a two-layer piezoelectric element.

The piezoelectric element has two electrodes in each layer, creating two regions within the piezoelectric element that are not electrically connected.

The layer is polarized in one direction in one region and in the other direction in another region.

The outer conductive coatings of each region are interconnected. The motor may include at least one additional electrode pressed against the stator.

On the rotor shaft passing through the stator, it is possible to mount two rotary bodies which can be moved axially symmetrically on either side of the stator.

Each rotating body is, for example, in the shape of a truncated cone, and has holes and grooves for mounting the rotating body on the rotor shaft.

The two rotating bodies are pressed against the sides of the stator.

Two vibrators can be provided in the stator.

One end of each oscillator is pivotally mounted, and a rotor is disposed between the oscillators, which is biased toward the end of one oscillator by a reversing device.

The reversing device may consist of an electromagnet, a portion of which is attached to the end of one of the oscillators.

When the motor disclosed herein is operated as a generator, its rotor is coupled to a drive that rotates the rotor.

At least one pair of electrodes of the at least one vibrator which excites one type of vibration is in this case connected to an electrical load.

The second electrode pair, which includes one electrode belonging to the first electrode pair, can be connected to an AC power source having the same frequency as the operating frequency of the motor.

A second pair of electrodes for exciting another type of vibration can be connected to an alternating current power source at a frequency that is the operating frequency of the motor.

The piezoelectric motor disclosed herein is a new type of windingless motor.

Since this motor has no windings, it is easy to manufacture and does not require much manpower.

Furthermore, this piezoelectric motor can reduce the amount of expensive materials used compared to a wound motor.

The cost of the motor is correspondingly reduced.

With a piezoelectric motor having one of the structures described above, the rating of low power motors is significantly improved.

Therefore, compared to an electromagnetic AC motor, the efficiency of a piezoelectric motor with an output below IOW is two to three times higher.

The dimensions of this motor are also reduced and can be made into a flat structure or an elongated shape.

No problems arise in constructing a low-speed motor with this piezoelectric motor, and therefore this motor does not require a reduction gear.

These piezoelectric motors are characterized by a large starting torque and a small moment of inertia, which makes them superior to electromagnetic motors and advantageous for use in various automation devices.

Another advantage is that this piezoelectric motor can be used as a small capacity generator.

Similar to the motor, this generator is simple in structure, small in size, and highly reliable.

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

The illustrated motor includes a base 1 (FIG. 1), a stationary part or stator 2, and a rotating part or rotor 3.

This rotor 3 is attached to the stator 2 by a bearing 4.

This motor is connected to a power supply 5 either directly or via a phase shifter 6.

This phase shifter 6 is used to electrically reverse the direction of rotation of the motor when necessary.

In the motor disclosed here, electric power is converted into mechanical power of rotation of the rotor 3 by a piezoelectric device, so
This motor was named a piezoelectric motor.

The sufficient and necessary features of the piezoelectric motor disclosed here are:
The stator 2 is connected to at least one oscillator 7 (second and third
．． 4), or the rotor 3 includes at least one oscillator 7' (FIG. 3), or both stator 2 and rotor 3 include at least one oscillator.

The vibrator 7 of the stator 2 includes a piezoelectric element 8, and the vibrator 7' of the rotor 3 similarly includes a piezoelectric element 8'.

The direction of polarization within the piezoelectric elements 8, 8' is indicated by arrows.

In this specification, the term "oscillator" refers to a resonator composed of piezoelectric elements that can store mechanical energy in the form of elastic vibrations.

In the following description, a stator or rotor with one or several oscillators and thus with one or several piezoelectric elements will be described as piezoelectrically operated. In a conventional stake or rotor, this means that electrical power is converted into mechanical power due to the inverse piezoelectric effect.

If the stator or rotor does not include a vibrator, no mechanical vibrations are generated by the electrical power.

A rotor or stake that does not contain an oscillator is therefore said to be piezoelectrically passive, or simply passive.

In order to increase the capacity of the piezoelectric motor, the stake 2 contains several oscillators 7, one end of each oscillator being pressed against the rotor 3 (FIG. 4).

In order to transmit the driving torque, the stator 2 and rotor 3
are pressed against each other.

The contact between stator 2 and rotor 3 occurs along a straight line belonging to the surfaces of vibrators 7, 7'.

At least the rotor 3 is arranged so that the portion of the surface of the rotor 3 that contacts the stake 2 is formed by a rotation trajectory when rotating at least one straight line AA (FIG. 2) about the rotation axis of the rotor 3. It is convenient to form

This requirement is also met when the entire rotor 3 is formed as a body of rotation about its axis of rotation.

Two major examples of basic configurations of the piezoelectric motors disclosed herein will now be described.

According to a first basic configuration example, the piezoelectric motor includes a holder 9 for a vibrator 7 (FIG. 2) and a stator 2 having a bearing 4 .

Vibrator 7 includes piezoelectric element 8 . The piezoelectric element 8 is in the form of a plate, on both sides of which electrodes 10.11 are provided.

The lead 12 of the electrodes io and i1 is a power source (not shown)
connected to.

The stator 2 is pressed against the rotor 3 by a pressure member 13.

The pressure member 13 also belongs to the stator structure.

The holder 9, the pressure member 13 and the bearing 4 are mounted on a housing (not shown) of a piezoelectric motor.

The rotor 3 is formed as a cylinder 14 . This cylinder 14 is mounted on a shaft 15.

The rotor 3 contacts the stator 2 along a certain straight line.

In the embodiment described here, the rotor 3 is piezoelectrically passive, so that the motor will be referred to as a piezoelectrically passive rotor or simply a piezoelectric motor with a passive rotor.

According to the second basic configuration example shown in FIG. 3, the stator 2 and rotor 3 each include vibrators 7 and 7'.

This motor will be referred to as a piezoelectric motor with a piezoelectrically active rotor and a stator, or simply a piezoelectric motor with an active rotor and stator.

In the structure described here of a piezoelectric motor with active rotor and stator, the vibrator 7' of the rotor 3 is constituted by a disc-shaped piezoelectric element 8'.

Electrodes IQ' and 11' of this piezoelectric element 8' are connected to a power source via a lead 12' and a brush 17.

The vibrator γ of the stator 2 includes a piezoelectric element 8 .

This piezoelectric element 8 is pressed against the rotor 3 via a lining 18 by a pressure member 13 .

The bearing 4, the pressure member 13, and the brush 17 are connected to the stator 2.
can be attached to the body of

Depending on the requirements placed on the piezoelectric motor, the stator and rotor can be of various constructions.

For example, the vibrator 7 (FIGS. 5 and 6) and the bearing 4 are mounted on a support 19 of the stator 2, and the vibrator 7 is fixed to the support 19 via an insulating layer 20.

This insulating layer 20 acoustically insulates the vibrator 7 from the support 19 .

The material constituting this insulating layer 20 can be any solid material as long as the product of its density and Young's modulus is one-tenth or less of the product of the density and Young's modulus of the vibrator 7. .

Such materials include rubber, cork, and wood.

The piezoelectric motor shown in FIGS. 5 and 6 has an insulating layer with a thickness of approximately 0.5 DEG, and the motor exhibits satisfactory characteristics.

Good acoustic insulation of the vibrator 7 from the support 19 increases the efficiency of the piezoelectric motor.

According to experimental and calculated data, the efficiency of this piezoelectric motor is two to three times higher than any conventional motor at capacities below LOW.

The characteristics and parameters of this piezoelectric motor depend to a large extent on the structure of the vibrator.

The structures of vibrators that perform longitudinal vibration, radial vibration, bending vibration, sliding vibration, torsional vibration, and various combinations of these vibrations are well known (for example, "Ultrasonic Transducer J 1969 Corona," edited by Yoshimitsu Kikuchi, published by the company).

In a vibrator having the structure described above, acoustic vibrations are simultaneously excited in several directions.

That is, when the vibrator 7 is plate-shaped (FIGS. 2 and 3), vibrations are excited not only in the longitudinal direction of the plate, but also in the width and thickness directions.

When the vibrators 7, 7' are disks (FIG. 3), vibrations are simultaneously excited radially in the thickness direction of the disks and in the generatrix direction of the cylinder.

Additionally, mechanical elastic waves propagate in the above direction.

If the vibrator has dimensions such that the integral part of the numerical value of the half-wave of the mechanical vibration corresponds to the dimension in one of the above-mentioned directions, resonance of the mechanical vibration will occur.

If the dimension in this direction is such that it accommodates one half wave, then the first harmonic is involved, and if the dimension is such that it includes two half waves, the second harmonic is involved, and it includes three half waves. If the dimensions are as follows, the third harmonic is involved.

Similarly, the harmonics corresponding to the number of included harmonics are related.

In addition, parasitic vibrations are also excited in the vibrator.

Parasitic vibrations reduce the electromechanical coupling coefficient of vibrations necessary for the operation of the motor (hereinafter referred to as operational vibrations).

Therefore, in the vibrator, in addition to operational vibrations, that is, torsional vibrations and longitudinal vibrations, which propagate along the cylindrical generating line, parasitic vibrations such as parasitic radial vibrations are also excited.

Therefore, for example, when talking about a longitudinal vibration type vibrator, it is meant that the longitudinal vibration is the only operational vibration.

The stator 2 has vertical vibration type vibrators (2nd, 4th, 5°6
It is convenient to use a vibrator that performs longitudinal vibration and bending vibration simultaneously (Fig. 7), or a vibrator that performs torsional vibration and longitudinal vibration simultaneously (Fig. 8).

However, if the vibrator 7 of the stator 2 generates longitudinal vibration and radial vibration at the same time (Fig. 9), and if the vibrator has a plate-like structure (Fig. 10), the stator 2 will generate both longitudinal vibration and sliding vibration. It includes a vibrator 7 that is generated.

The vibrator 7' of the rotor 3 can be a radial vibrator (FIG. 3).

In order to provide a high power frequency, the vibrator 7 of the rotor 3
' is a sliding type vibrator (Fig. 11).

A vibrator that performs torsional vibration has a low power supply frequency, whereas a vibrator that performs shear vibration and longitudinal vibration has a high power frequency.

A piezoelectric motor with a passive rotor 2 (FIGS. 2.4, 5.6), in which only one type of acoustic vibration is generated in one direction, cannot be electrically reversible.

That is, the rotational direction of the rotor cannot be reversed by switching the drawer lead.

Therefore, such motors are called non-reversible motors.

However, motors with an active rotor and an active stator (Fig. 3.11.12) and motors in which the vibrator 7 generates two types of vibration simultaneously (Fig. 7.8.10) are reversible motors.

The reason is that in these motors, the direction of rotation of the rotor 3 can be reversed by switching the pull-out lead.

Taking into account the direction of the vibrations to be excited and the direction of propagation of the vibrations, the vibrator γ can be mounted on the support 19 of the stator 2 with a minimum of acoustic energy loss and using practically any solid material.
It can be fixed to

Therefore, for example, the vibrator 7 is attached to the support 19 at least at the point where the vibration velocity is lowest (FIG. 12) (G
.

Magnetic and dielectric devices (Mag.
netic and dielectric device
ces) J1964, published by ENERGIYA Publishing House (Moscow), see ).

In the case of longitudinal, shear and torsional vibrations, the points of minimum vibration velocity are separated by a distance that can be divided by the dimension that defines the operating frequency of the transducer.

The dimension that determines the operating frequency is measured along the propagation direction of the sound wave, and the quantitative lowest point of oscillation speed is a point at a distance S given by the following equation from the end of the vibrator.

Here, S is a dimension that determines the frequency, and n is the number of harmonics of longitudinal vibration.

In the case of bending vibrations, the first minimum point of the vibration velocity is a distance S from the end of the vibrating rod.

This distance S can be approximately calculated from the following equation.

Here, n' is the number of harmonics of bending vibration.

Therefore, the vibrator can be mounted in the minimum vibration velocity region using the rectangular holder 9 (FIG. 2) or the frame-shaped holder (FIG. 12).

The vibrator 7 of the stator 2 can be fixed to the holder using adhesive, for example.

In addition to the piezoelectric elements 8, the lining 1 is also made of a non-piezoelectric material with sufficient wear resistance for the vibrator 7 of the stator 2.
8 is provided.

The lining 18 is coupled to piezoelectric elements to ensure acoustic contact between the rotor 3 and the stator 2.

By using this lining, the life of the piezoelectric motor is increased several times.

That is, the life of a piezoelectric motor with a hard metal lining is more than 2000 hours.

However, in applications where a life of 100 hours is sufficient, it is possible to reduce the number of parts in the motor by having the oscillators 7 or 7' of the stator 2 and rotor 3 each containing only a piezoelectric element 8 or 8'. Can be done (4th, 5th, 6th, 7th)
, 8, 9, 10.12).

If the wear force on the vibrator 7 (FIG. 3) of the stator 2 is considerably greater than the wear on the vibrator of the router 3, for example in a piezoelectric motor with an active rotor and an active stator,
It is convenient to equip the stator 2 with a wear-resistant lining 18 .

The vibrator 7' of the rotor 3 takes the form of a piezoelectric element 8' which is fixed in the lowest vibration velocity region of the shaft 15 of the rotor 3.

The lining 18 is shaped to ensure maximum coupling with the piezoelectric element 8.

This means that, for example, the lining 18 is attached not only to the end of the piezoelectric element 8, but also to one side of the plate-like piezoelectric element 8 (FIG. 13a).
), or by attaching it to both sides (Fig. 13b).

If the lining 18 is made in the shape of a beak (Fig. 13C)
, the drive torque of the piezoelectric motor becomes somewhat larger.

When selecting a piezoelectric motor design, it is necessary to select not only the type of vibrator but also its shape.

From a manufacturing standpoint, the most efficient shape of the transducer is a rectangular plate (2nd, 3rd, 4th, 5°6.7, 10th...
Figure 12).

However, in order to increase the efficiency of the motor, the stator 2
The vibrator 7 is made of a rod whose cross-sectional area gradually becomes smaller, or a plate whose thickness changes step by step (FIG. 14).

The rotor 3 contacts the end of the vibrator 7 where the cross-sectional area is the smallest.

In order to reduce the overall dimensions of the motor, the oscillator 7 of the stator 2 can be made as a helical rotor.

The rotor 3 is received between the ends of this helical rotor (FIG. 15).

In FIG. 15, the broken line shows the shape of the helical rotating body before the rotor 3 is inserted.

In order to reduce the dimensions of the piezoelectric motor and increase the operating frequency range by using torsional, radial and sliding vibrations, it is possible to use the oscillator 7 of the stator 2 (Figs. 8 and 9) or the oscillator 71 of the rotor 3 (Figs. 11. Make the shape shown in Figure 14 into a hollow cylinder.

The hollow cylindrical construction of the rotor 3 is particularly suitable for piezoelectric motors which are to be of flat construction, ie whose height is considerably smaller than the diameter (FIG. 11).

The above-mentioned structure of the vibrator does not indicate all possible vibrators, but should be considered as the main types.

These are such that, when deformed, they do not significantly change the power applied to the piezoelectric motor's shaft, or the main ratings of the motor, such as its rotational speed or efficiency.

Therefore, if the cylindrical shape is slightly distorted and tapered,
The linear velocity at various points along the rotor-stator contact line changes.

This creates noise during operation and adversely affects the motor rating.

The installation of the wear-resistant lining 18 must not be considered as a change in the shape of the transducer.

The reason for this is that the deformation of the lining does not serve to optimize the original shape of the vibrator, but is only necessary to create a stronger connection between the lining 18 and the piezoelectric element 8.

A piezoelectric motor in which the piezoelectric element 8 or 8' is hollow cylindrical has a thin-walled sleeve-like lining 18 (first L) with a bottom.
It is convenient to have 14 diagrams.

The lining 18 is fixed to the piezoelectric element 8 or 8' by adhesive, solder, or other suitable means to provide a good acoustical coupling between the lining 18 and the piezoelectric element 8 or 8'.

The above vibrator shape is the simplest.

It is convenient if the piezoelectric element 8 is similarly simple in shape, and furthermore, it is convenient if it is a replica of the shape of the vibrator.

That is, the piezoelectric elements 8 and 8' are rectangular plates (second, third, fourth
, 5, 6, 7, 10, 12), or a bar with a gradually decreasing cross-sectional area, such as a stepped plate (Fig. 14),
Hollow cylinder (Fig. 8,9゜11.14) or disk (Fig. 3)
．． It is convenient to use 1L12 figure) etc.

In practice, piezoelectric motors are required that operate at relatively low voltages, such as those supplied by dry cells or accumulators, with an output voltage of 1 to 50 volts.

In such a piezoelectric motor, a vibrator 7 of the stator 2 that performs sliding vibration in the thickness direction and longitudinal vibration can be used (FIG. 10).

The piezoelectric element 8 of this vibrator 7 is in the form of a two-layer plate with an electrode 21 between its layers 22.

A metal layer 23 is acoustically coupled to the surface of one electrode 11 of the piezoelectric element 8 to strengthen the strength of the vibrator 8.

Once the type of vibrator, its shape, and the shape of the piezoelectric element have been selected, it is necessary to determine the method necessary to excite the selected type of vibration.

This is done by selecting the polarization direction of the material, the electrode arrangement of the piezoelectric element, and the electrical connection of those electrodes.

As explained above, arrows in the figures are used to indicate the direction of polarization.

However, the direction of polarization shown by the arrow in the case of a hollow cylindrical piezoelectric element is true, and only if the piezoelectric element is made of a ferroelectrode ceramic material, such as a material that can be polarized in any direction. has.

Since piezoelectric ceramics are cheaper than piezoelectric crystals, piezoelectric ceramics are practically preferable in terms of the cost of piezoelectric motors.

On the other hand, crystalline piezoelectric materials generally have good piezoelectric properties.

Therefore, if the requirements for the electrical rating of the piezoelectric motor are more important than the requirements for cost, it is desirable to use crystalline materials for the piezoelectric elements of the disk-shaped and plate-shaped vibrators.

Among piezoelectric materials that do not fall into the ferroelectric category, quartz exhibits high mechanical strength and a high mechanical quality factor.

Therefore, it is convenient to use quartz crystals for piezoelectric motors that must have high specific power and high efficiency.

The shape of the vibrator and the shape of the piezoelectric element described above do not in themselves clearly determine the type of acoustic vibration excited by the vibrator.

To fully explain the vibrator, it is necessary to know how to polarize the piezoelectric element, how to attach and connect the electrodes.

The direction of polarization is characterized by the angle between the averaged vector of polarization and the electrode.

Therefore, a piezoelectric element is polarized perpendicular to its electrodes, which means that if an electric field is applied between those electrodes, the direction of the electric field vector at each point is the polarization vector at that point. It means to match the direction.

On the other hand, if the polarization vector is perpendicular to the electric field vector at each point of the piezoelectric element, then the piezoelectric element can be said to be polarized parallel to the electrodes.

In order to excite longitudinal and bending vibrations, at least a portion of the piezoelectric element should be polarized perpendicular to its electrodes.

In the case of plate-shaped, disk-shaped, hollow cylindrical, and spiral piezoelectric elements, polarization perpendicular to the electrodes can also be called thickness direction polarization (2.3, 4°, 5.12, 14, 15. Figure 16).

In order to vibrate shear and torsional vibrations, at least a portion of the piezoelectric element should be polarized parallel to its electrodes.

Therefore, a part of the piezoelectric element 8 is polarized parallel to the electrode 11.21 (FIG. 8), exciting longitudinal vibrations along the height of the cylinder, and the other part is polarized parallel to the electrode 10.21. Excite torsional vibration.

The above-described examples of polarization of a piezoelectric element do not represent all possible ways of polarizing a piezoelectric element.

However, all such polarization methods are known and can be characterized by the main principles described below.

1. As the value of the input impedance of the piezoelectric element of the vibrator increases, the distance between the electrodes 10 and 11 (FIG. 17) to which the electric field is applied increases.

Therefore, among the three types of structures shown in FIG. 17, the lowest impedance is obtained from the structure shown in FIG. 17a, and the highest impedance is obtained from the structure shown in FIG. 17C.

If a single element is polarized in its thickness direction, the input impedance of the piezoelectric element can be increased by dividing the piezoelectric element 8 (FIG. 18) into parts 24 and connecting the parts 24 in series. I can do it.

However, this series connection is only effective if the mechanical strains in all parts have the same general orientation.

When the harmonic order is 2 or higher (1st
9, 20), the mechanical strain periodically changes its orientation, at which time it passes through the lowest point of the mechanical strain (in the figure the longitudinal distribution of the mechanical strain of the plate is indicated by a dashed line).

It should be remembered that this can be obtained by connecting the sections 24 in parallel and changing the polarization direction of the sections 24 (FIG. 19a) or by cross-connecting the electrodes (FIG. 19b).

If the sections 24 are connected in series, it is sufficient to divide the electrodes 10.degree. 11 into several sections without changing the direction of polarization.

The example described above can be applied to the generation of all kinds of vibrations within piezoelectric elements.

However, bending vibration has certain unique characteristics.

Bending deformation without longitudinal deformation can occur in a two-layer plate (FIG. 21) in which the layers 22 are connected in parallel and the layers 22 are polarized in one direction through the thickness.

The same is true if the layers 22 are connected in series and their polarization occurs in opposite directions.

If the layers 22 are connected in series, the impedance will be four times greater than if they were connected in parallel.

The input impedance of the piezoelectric element 8 can be made sufficiently high if the layers 22 are not separated by electrodes but are oppositely polarized in the longitudinal direction (FIG. 22).

In this case, and in the case of single-sided electrodes where the electrodes are attached to the end faces (FIG. 17C), the efficiency of conversion of electrical energy into mechanical energy is maximum.

However, if the input impedance of the piezoelectric element is high, a high power supply voltage is required.

This narrows the field of application of such piezoelectric elements to piezoelectric motors.

By vertically dividing the piezoelectric element 8 into several layers 22 and separating these layers by parallel-connected electrodes 10.11, the input impedance of the piezoelectric element 8 can be reduced.

In the case of relatively thin piezoelectric elements, it is convenient to attach the electrodes 1o, ii to the surface of one or both sides of the plate.

In many designs of piezoelectric motors, the rotor 3 is pressed against the stator 2 by a pressure member 13 or 13'.

In the simplest structure of the piezoelectric motor, the pressure member 13
is a compression spring attached to the support 19 of the vibrator 7.

In order to reduce the biasing forces exerted on the bearing 4 , the pressure elements 13 , 13 ′ can be mounted on the two oscillators 7 of the stator 2 or on the oscillator 7 of the rotor 3 .

The pressure members 13, 13' can be constructed in the form of elastic gaskets or rubber braids.

In a piezoelectric morph with a relatively small shaft output, the pressure member 13
, 13' can be composed of permanent magnets.

In the piezoelectric motor with a passive stator and the piezoelectric morph with an active stake and an active rotor, the extraction lead of the piezoelectric element 8' of the stator 3 is connected to the power supply via the brush 17 (No. 3.11° 12.14) figure).

Usually, the brush 17 is combined with a commutator 25 (a third
, 14).

Commutator 25 is attached to shaft 15 of rotor 3.

Alternatively, the brush 17 can be used as the electrode 10', 11' of the rotor 3.
(Fig. 11.12).

This greatly simplifies the structure of the piezoelectric motor.

In order to receive low supply voltages, the disc-shaped piezoelectric element 8' is made of several layers 22 (FIG. 25).

The layer 22 extends parallel to the electrodes 10', 11' and is connected in parallel.

The parallel connection of the layers 22 is preferably carried out by conductive strips 27.

A thin-walled cylindrical lining 18 made of wear-resistant ceramic is fixed to the cylindrical surface of the piezoelectric element 8'.

A commutator 25 is associated with the rotor 3, and the rotor 3 is received within the stator 2.

The stator 2 has a hollow cylindrical shape, and one end of the plate 16 is fixed inside the hollow cylinder symmetrically about the rotation center axis of the rotor 3, and both ends of the plate 16 are in contact with the surface of the rotor 3. do.

Due to the inherent elasticity of these plates 16, the rotor 3 and stator 2 are pressed against each other.

This construction of a piezoelectric motor with a passive stator can use the rotor 3 of a piezoelectric motor (FIG. 14) with an active rotor and an active stator.

The rotor 3 has a hollow cylindrical shape that is polarized in the radial direction, and electrodes 10' and 11' are attached to the cylindrical surface.

The rotor 3 is inserted into a thin-walled sleeve-like lining 18.

A piezoelectric motor constructed in this way considerably increases the mechanical power.

In order to make this piezoelectric motor a reversible motor, it is constructed using an active rotor 3 and an active stator 2 (Section 3.11,
12, 14, 26).

In the structure shown in FIG. 26, the stator 2 is composed of two vibrators 7 that longitudinally vibrate at the second harmonic.

Electrodes 10 of these vibrators 7 are connected to each other.

Electrodes 11 are also connected to each other. In order to provide high voltages, the structure disclosed here has a rotor 3 containing a hollow cylindrical oscillator 7' (FIG. 14).

This rotor preferably takes the form of a rotor 3 of a piezoelectric motor with stepped oscillators 7 of a stator 2.

Stator 2 and rotor 3 are pressed together by a pressure member 13 mounted on a support (not shown) of stator 2.

The pressure member 13 contacts the respective surface of the vibrator 7 of the stake 2 .

In order to reduce the overall dimensions of the piezoelectric motor and increase its power on its shaft, the oscillator 7 of the stator 2 is of hollow cylindrical shape, symmetrically surrounding the rotor 3 (FIGS. 27 and 28).

Similarly, the piezoelectric element 8 of the vibrator γ has a hollow cylindrical shape, and electrodes 10.11 are attached to the cylindrical surface.

As far as the polarization direction is concerned, this piezoelectric element 8 is divided into an even number of regions (there are four such regions in FIG. 28).

These regions are designated with reference numbers 28.28'.

Regions 28, 28' are polarized in the thickness direction.

The polarization directions of each pair of adjacent regions are opposite.

With such a structure of the piezoelectric element 8, the area 28.28'
Resonance of longitudinal vibration along the circumferential surface of the piezoelectric element 8 occurs in the number of harmonics equal to the number of harmonics (in the structure shown in FIGS. 27 and 28, the fourth harmonic is emphasized).

In order to transmit the drive torque from the stator 2 to the rotor, a lining 18 made of a wear-resistant material is fitted inside the hollow cylindrical piezoelectric element symmetrically with respect to the axis of rotation of the rotor 3 .

The number of linings 18 is equal to half the number of areas 28, 28' (ie equal to 2 in the example described here).

It is convenient if the cross-sectional shape of the lining 18 is an isosceles triangle as shown in FIG.

The vibrator 7' of the loader 3 is preferably composed of two discs,
These discs are mounted on the shaft 15 of the rotor 3 so as to be movable in its longitudinal direction.

The vibrator 7' includes a hollow cylindrical piezoelectric element 8'.

An electrode 10ζ11' is attached to the cylindrical surface of this piezoelectric element, and is polarized in a direction perpendicular to the electrodes 10', 11'.

Electrodes 10' and IV are each connected to each other.

The two piezoelectric elements 8' are polarized in opposite directions.

This configuration, in combination with the connection of the electrodes 10', 11' and the polarization of the piezoelectric element 8', generates in-phase radial vibration in the vibrator 7' of the rotor 3.

The end of the pressure member 13' is attached to the side surface of the vibrator 7' of A-3.

This pressure member pushes the oscillator γ' of the rotor 3 towards the lining 18 of the oscillator 7 of the stator 2.

In this way, the rotor 3 and stator 2 are pressed against each other.

Therefore, the two oscillators 7' of the rotor 3 are connected to the stator 2.
should be arranged symmetrically to the vibrator 7.

Among the many advantages offered by piezoelectric motors is the ability to create flat motors.

A flat piezoelectric motor (FIG. 29.30), which is a simple variant of the piezoelectric motor of FIG. 16, has a stator 2 containing two oscillators 7 in the form of two-layer piezoelectric plates 29.

Each piezoelectric plate 29 has a hole in its center through which the shaft 15 of the rotor 3 passes.

A component 26 of the rotor 3 is mounted on the shaft 15.

This component 26 is formed as two disks that receive the vibrator 7 of the stator 2 between them.

These discs 26 are attached to the shaft 15 by pins 30, so that the discs 26 can be moved axially about the shaft 15.

A pressure member 13' in the form of a spring is connected to the disc 26 and provides a force pushing the rotor 3 onto the stator 2.

In the piezoelectric motor described here, the piezoelectric element 8 of the vibrator 7 of the stator 2 is a two-layer plate 29 (FIG. 31), with electrodes 11, 31 mounted between the layers 22 and electrodes 10, 21 is attached to the outer surface of the piezoelectric plate 29.

The outer electrodes 10.21 and the inner electrodes 11.31 are connected to each other and to a power source.

Each piezoelectric plate 29 is polarized in its thickness direction.

The direction of this polarization divides the piezoelectric plate 29 into three regions 28.
It is divided into 28' and 32.

The region 32 to which the electrodes 21.31 are attached includes half of the piezoelectric plate 29 in its width direction and is polarized in one direction in its thickness direction.

Two other electrodes 28.28' with electrode 10.11 divide the other half of the piezoelectric plate 29 into two longitudinally.

The layer 22 in each region 28, 28' is polarized in opposite directions through its thickness, and the regions 28 are polarized in opposite directions.

The arrangement and connection of the electrodes and the direction of polarization of the piezoelectric element cause the second harmonic of the longitudinal vibration of the piezoelectric element to be generated in the longitudinal direction, and the second harmonic of the bending vibration to be generated in the width direction.

The resonance frequency fn of longitudinal vibration can be calculated from the following equation.

Here, Nn is the frequency constant of the material.

In the case of bending vibration, the resonance frequency fn can be approximately calculated from the following equation.

β1 = 1.03 - For the first harmonic of bending vibration, β2
=2.83-For the second harmonic of bending vibration, here:
a is the thickness of the piezoelectric element, L is the length of the piezoelectric element, E is Young's modulus of the piezoelectric element, and ρ is the density of the piezoelectric element.

In the structure of the piezoelectric motor described here, the stator 2
The two oscillators 7 are excited in the same phase.

That is, each vibrator is excited such that the torque generated in each vibrator is added to the torque generated in other vibrators.

This is coupled in parallel to the axis 1 of the polarization direction force button 3.
arranged symmetrically with respect to a plane BB perpendicular to 5 and extending midway between the piezoelectric elements 8 of the stator 2;
This is ensured by the two piezoelectric elements 8 of the stator 2.

The vibrator 7 of the stator 2 is supported by a pin 33 (not shown) fixed to the piezoelectric element 8 in a region where the vibration velocity of the longitudinal vibration of the second harmonic in the longitudinal direction of each piezoelectric element 8 is the lowest. It will be installed.

In an electrically reversible piezoelectric motor with a passive rotor 3 (FIGS. 8 and 10), the oscillator 1 has three electrodes 10
．． 11.21.

The electrode 21 is called a common electrode because it is used to excite two types of vibration, and the other electrodes 10 and 11 are used to excite one type of vibration.

In order to make this motor a reversible motor, the common electrode 21 is connected to one electrode of the power source 5 (FIG. 8), and the electrode 10 is connected to the other electrode of the power source 5.

The electrode 11 is connected to a phase shifter 6, a single pole switch 34, and a converter 3.
5 to the electrode to which the electrode 10 of the power source 5 is connected.

The converter 35 preferably uses a transformer.

In a piezoelectric motor containing electrode pairs 10 and 11, 21 and 31 (
7 and 31), since each electrode pair vibrates the piezoelectric element 8 of the vibrator 7 with only one type of vibration, for example, the electrode pair 1
0 and 11 are connected to the power supply 5 via the bipolar switch 36,
The electrode pairs 21 and 31 are directly connected to the power source 5, and the electrodes 10 and 11 are connected directly to the power source 5.
By reversing the connection of the motor to the power source 5, the direction of rotation of the motor can be electrically reversed.

An electrically reversible piezoelectric motor with an active stator and an active rotor is likewise connected.

However, the difference between the two is that a bipolar switch 36 is provided to which electrodes io' and i1' are connected, whereas electrodes 10 and 11 are directly connected to the power source.

Generally, the piezoelectric motor is connected to the circuit of a DC-AC converter (Figure 32).

The frequency of this alternating current is equal to the resonant frequency of the motor.

In order to provide this converter with a feedback circuit, it is convenient to use at least one electrode 37 as a feedback source.

To do this, electrode 37 is connected to the base of transistor 38.

This transistor 38 is an amplification element within the feedback circuit.

In the DC voltage converter (FIG. 33), the piezoelectric element 8 is provided with two return electrodes 37.

Since this converter is constructed using two transistors 38, it can operate without using an inductance 39, unlike the circuit shown in FIG.

An electrically reversible piezo motor (FIG. 7) with electrode pairs 10, 11, 21 and 31 can be operated with one piezo element 8.

In one construction of such a piezoelectric motor υ, the oscillator 7 of the stator 2 is in the form of a two-layer piezoelectric element with two independent electrodes 10.21.

In each plane of the layer 22, the electrodes form two regions 28, 32 in the piezoelectric element 8 that are not electrically connected.

Polarization within region 32 of layer 22 is in one direction and polarization within region 28 is in the opposite direction.

The metal coatings on the opposing outer surfaces of layer 22 are interconnected to form electrodes 10.21.

Due to the structure of the piezoelectric element described here, the stator 2
The vibrator 7 can be operated in the longitudinal direction of the piezoelectric element with the first harmonic of longitudinal vibration, and can be operated in the longitudinal direction of the piezoelectric element with a higher harmonic of the bending vibration.

This piezoelectric motor structure can also be adopted for a piezoelectric motor having several rotors (FIG. 34).

This means that one stator 2 is also pressed against this stator by at least one additional rotor 40 (40
').

What is the force that pushes the stator and rotor 3, 40, 40' towards each other?

This is provided by the elasticity of the piezoelectric element 8, which is pre-bent when the piezoelectric motor is assembled.

By using several rotors, torque can be applied to several load devices.

In a similar construction of the piezoelectric motor, the two parts 26 of the rotor 3 (FIG. 35) are fixed to the shaft 15 of the rotor 3.

At any given time, the rotor 3 contacts only one side of the stator 2 by a respective one part 26 of the rotor 3.

By moving the entire rotor 3 in the axial direction using the arm 41, the direction of rotation of the motor can be reversed.

In this case, the direction of rotation of the motor is mechanically reversed.

This is done by applying a mechanical force F to the arm 41 in a corresponding direction.

However, to ensure that the motor can be reversed,
Opposite end faces of the vibrators 7 of the stator 2 that alternately contact the rotor 3 must correspond in opposite directions of rotation.

It is made as a hollow cylinder and has an electrode 10.11 on the end face.
This is carried out by the vibrator 7 of the stator 2 provided with.

The polarization of half of the piezoelectric element 8 takes place in the longitudinal direction of the cylinder, and the remainder of the piezoelectric element is polarized in the circumferential direction parallel to the electrodes 10.11.

The simplest structure of a piezoelectric motor is the vibrator 7 of the stator 2.
In the case of a plate-shaped motor in which longitudinal vibration is excited, the rotation can be mechanically reversed.

This is achieved by the stator 2 (FIG. 36) being provided with two oscillators 7 mounted at their ends on pivots 42.

The rotor 3 is received between both ends of the vibrator 7.

The rotor 3 is selectively pushed onto each end of one of the two vibrators 7 by the support member 43.

The receiver member 43 may include an electromagnet 44 .

In this case, a body 44' made of ferromagnetic material is attached to the end of one vibrator 7.

Body 44' is attracted to electromagnet 44 to reverse the direction of rotation of the motor.

It should be remembered that electrically reversible piezoelectric motors are characterized by an optimal phase relationship of the vibrations excited in the vibrator.

Therefore, it is convenient to connect at least one pair of electrodes via a phase shifter 6.

This includes electrode pairs 10 and 11 (Figure 3), 10 and 21 (first
0), 10 and 11 (Fig. 31).

It should also be noted that in the piezoelectric motor described here, the positions of the rotor and stator can be interchanged, as in other types of motors.

This is done by fixing the rotor in a fixed position (so that the rotor becomes a stator) and rotating the stator.

If the previous stator contained an oscillator, brushes could be provided to power the previous stake.

On the other hand, the brushes used on the previous rotor can be eliminated.

Similar to electric motors that utilize the interaction of electromagnetic fields, this piezoelectric motor has an axis 15 (FIG. 37) of the rotor 3 connected to the external prime mover 4.
5 and constitutes a reversible system in the sense that when at least one pair of electrodes of at least one vibrator is connected to a load 46, an alternating current voltage is generated between the terminals of the load 46.

This is the case in all designs of piezoelectric motors disclosed here, so that when these piezoelectric motors are operated as generators, they convert mechanical energy into electrical energy. Can be used as a transducer without winding.

However, if electrically reversible piezoelectric motors are selected from all the structures disclosed herein, they can be employed as actual generators for electrical power utilization (Art. 38.39.40). figure).

To do this, the electrode pair 10.21 (FIG. 38), which excites vibrations of the piezoelectric element 8 of the vibrator 7 that changes the force pressing the stator 2 against the rotor 3, is connected to the power source 5 and rotates the rotor 3. The electrode pair 11, 12 which generated the rotor driving force to cause the rotor to move is connected to the load 46.

In a piezoelectric motor including one piezoelectric element 8 having three lead-out leads, the electrode 10 and the common electrode 21 excite vibrations that change the force with which the rotor 3 is pressed against the stator 2, and the electrode 11 and the common electrode 21 generates a force that vibrates the rotor 3.

Therefore, when this piezoelectric motor is operated as a generator, the electrodes 10 and 21 are connected to the power source 5 (Fig. 38),
Electrodes 11 and 21 are connected to a load 46.

In a piezoelectric motor with four electrodes (No. 7.29°30
), electrodes 21 and 31 are connected to a load 46 (39th
figure).

In a piezoelectric motor having an active rotor and an active stator (Fig. 3.1L12.14.26°27.28), the electrodes 10', 11' of the piezoelectric element 8' of the rotor 3 are connected to the power supply 5, and the stator 2 The electrodes 10.11 of the piezoelectric element 8 are connected to a load 46 (FIG. 40).

Next, in connection with the operating principle of the piezoelectric motor of the present invention, some explanation will be given regarding the longitudinal vibration and transverse vibration that occur in the frictional contact portion.

In FIG. 41a, if body A is pressed against body B, for example by spring C, acoustic vibrations are excited in one body, for example B, in the direction of the compressive force, and by body A. The force applied to body B exceeds the frequency of vibration.

However, if lateral vibrations are excited in body B in relation to the above forces (FIG. 41b), the force exerted on body B by body A is unchanged.

If, in addition to the longitudinal vibrations (Figure 41a), transverse acoustic vibrations are excited in one body at the same frequency but slightly out of phase, the transversely oriented constant A force of is generated between the two bodies, causing body B to move (Figure 41C).

This principle of converting acoustic vibrations into vertical or rotational motion is the basic principle applied to the piezoelectric motor of the present invention.

This principle is further realized by two basic configurations.

The first is that vibrations in directions perpendicular to each other are excited in one body (A or B) (Fig. 41d), and the second is that vibrations are excited in both bodies (A and B). (Figure 41C).

The piezoelectric motor having a polarized oscillator disclosed herein operates as follows.

The piezoelectric motor starts a series of operations by connecting it to an alternating current 5, but without further explanation, the piezoelectric motor shown in FIG. 2 will be explained in the following five steps.

First stage: transformation of the alternating voltage applied to the electrode 10.11 via the lead 12 into alternating longitudinal deformations (Figs. 2a, 2b).

This transformation causes the lining 18 to be displaced in the longitudinal direction.

This conversion of energy is evident in piezoelectric materials and is called the inverse piezoelectric effect.

The degree of transformation in the case under consideration is the piezoelectric coefficient α3
．． characterized by

Second stage: In the motor shown in Figure 2, the end of the piezoelectric element abuts the rotor (Figure 2c).

As a result, a longitudinal displacement is possible when the piezoelectric element is rotated.

The frequency of the electric field is close to the resonant frequency of the longitudinal vibration of the piezoelectric element (ie, greater than 20,000 Hz).

The vibration frequency of the spring-type piezoelectric element method is several Hz.

As a result, the piezoelectric element has a "
be tightened.

That is, it cannot rotate at high frequencies. However, since the piezoelectric element has finite elasticity, it can only rotate (bend) within a certain angle (Figure 2d).

Third stage: The bending deformation at the end of the piezoelectric element moves the adjacent layers laterally in a timely manner.

That is, the bending wave begins to propagate from the ends of the piezoelectric element (see Figure 2e) and is reflected multiple times from both ends of the piezoelectric element, generating a standing wave.

As a result, the ends of the piezoelectric elements are in contact with the rotor, but are displaced laterally with some time lag relative to the longitudinal displacement.

Fourth stage: When point A (Figure 2f) vibrates at the same frequency in two mutually perpendicular directions with some phase shift, the trajectory of the motion of point A becomes an ellipse (Figure 2f). .

Point A moves clockwise or counterclockwise depending on the sign (direction) of the phase shift.

Stage 5: As the end of the piezoelectric element (point A) moves in an oval pattern, the end of the piezoelectric element should be released from engagement with the rotor during the reverse movement.

Thus, the end of the piezoelectric element imparts a rotational pulse to the rotor, is disengaged from engagement with the rotor to impart a subsequent pulse in the same direction to the rotor, and then returns to its original state.

The above is the basic operating principle of the piezoelectric motor shown in FIG.

In the special case where the trajectory of the movement of point A is circular, said point actually forms an axis of rotation that engages the rotor 3 and thus transmits its rotation to it.

As the amplitude of vibration increases, the diameter of this "drive shaft" increases, so the rotational speed of the rotor 3 increases.

- The higher the force, the higher the frequency, the higher the angular velocity of this "drive shaft" and therefore the rotational speed of the rotor 3.

Furthermore, as the diameter of the rotor 3 decreases, its rotational speed decreases.

Therefore, the rotational speed of the piezoelectric motor disclosed here depends on the dimensions of the rotor 3 and is proportional to the amplitude and frequency of the vibrations.

By controlling the frequency of vibration and the power supply frequency of the motor, the rotational speed of the motor can be increased from several revolutions per minute to several thousand revolutions per minute.

The above-described operating principle 6 of the piezoelectric motor is not the only one that explains its operation.

A second explanation of the operating principle of piezoelectric motors with passive rotors is the jostling or wedge effect.

This effect is such that when the rotor 3 is rotating counterclockwise, for example, the rotor 3 becomes clogged, and when the rotor 3 rotates clockwise, the rotor 3 is not clogged.

The wedge effect is such that the end of the vibrator 7 that is pressed against the rotor 3 is subjected to a torque and is forced into the gap between the vibrator 7 itself and the rotor 3 .

In other words, in the horizontal configuration the vibrator 7 is somewhat separated from the rotor 3 and the wedge is inserted into the gap between them.

When the rotor 3 rotates clockwise, the wedge is drawn into the gap, and when the rotor 3 rotates counterclockwise, the wedge is pulled out of the gap.

Due to this wedge effect, when the end of the oscillator 7 moves forward towards the rotor 3, the frictional force is considerably greater than the frictional force associated with the return movement of the end of the oscillator.

In this way, the rotor 3 is driven forward, and during the return movement the end of the oscillator 7 slides over the rotor 3.

The operation of the piezoelectric motor (FIG. 3) with active rotor 3 and active stator 2 is quite simple.

In this structure, since the second harmonic of longitudinal vibration is excited in the piezoelectric element 8 of this motor, it falls at the center of the plate of one of the vibrators at the highest value of vibration velocity.

Therefore, the lining 1 fixed to the stator 2
8 vibrates in the horizontal direction and sends a driving torque pulse to the rotor 3.
tell to.

The vibration of the piezoelectric element 8' of the rotor 3 changes the force with which the rotor 3 and stator 2 are pressed against each other.

If contact between the rotor 3 and the stator 2 occurs when the lining 18 moves to the right, the rotor 3 will rotate clockwise.

It is sufficient to switch the lead of the piezoelectric element 8 (or 81) and the contact is made when the lining 18 moves to the left, so that the rotor 3 rotates counterclockwise.

In a piezoelectric motor in which two types of vibrations are electrically excited by one vibrator, one type of vibration changes the force pressing the rotor 3 against the stator 2, and the other type of vibration changes the force that presses the rotor 3 against the stator 2. Transmits drive pulses to the rotor.

In a piezoelectric motor structure in which longitudinal vibration and bending vibration are excited in the vibrator 7 (FIG. 7), the bending vibration changes the force with which the rotor 3 and the stator 2 press against each other.

In the structure of a piezoelectric motor that employs a vibrator 7 that uses torsional vibration and longitudinal vibration along the height of a hollow cylinder (Fig. 8),
The longitudinal vibration changes the force with which the rotor 3 and stator 2 press against each other.

In a structure using the vibrator 1 (FIG. 9) of the stator 2 that excites longitudinal vibration and radial vibration, it is the longitudinal vibration that changes the force that pushes the rotor 3 against the stator 2.

In a structure having a vibrator 7 in which longitudinal vibration and shear vibration are excited in the thickness direction of the piezoelectric element 8 (FIG. 10), it is the longitudinal vibration that changes the force that pushes the rotor 3 toward the stator 2.

Longitudinal vibration is excited in the length direction of the vibrator 7 of the stator 2,
In a structure having a vibrator 7 in which bending vibration is excited in the width direction of the vibrator 7 (FIGS. 29 and 30), it is the bending vibration that changes the force pressing the rotor 3 against the stator 2.

In a piezoelectric motor having an active rotor 3 and an active stator 2, it is generally the rotor 3 that changes the force with which the rotor 3 and stator 2 press against each other.

Therefore, in a structure having an active rotor 3 and an active stator 2 (Figs. 12.14.27 and 28), the force with which the rotor 3 and stator 2 are pressed against each other is due to the force exerted by the oscillator 7 of the rotor 3, where the radial vibrations are excited. ’ can be changed by

In the structure including the vibrator 7 of the stator 2 in which the third harmonic of radial vibration is excited (FIG. 11), the rotor 3
It is the vibrator 7 of the stator 2 that changes the force with which the stator 2 and the stator 2 press against each other.

The reason why we chose harmonics of radial vibration in this case is because
This is explained by the need to match high-frequency shear vibrations with relatively low-frequency radial vibrations.

The operation of a piezoelectric motor (FIG. 4) in which the stator 2 is equipped with several vibrators 7 is basically the same as the operation of a piezoelectric motor (FIG. 2) having only one vibrator 7.

However, the power generated at the output shaft of the motor increases in proportion to the number of vibrators 7, and can increase to about several tens of W at the output shaft of the motor.

In the structure (FIG. 34) in which several rotors 3,40,40' are connected to the power supply, the efficiency of the piezoelectric motor as a whole is increased and the ratio of power to loss in the vibrator 7 is also increased.

The torque generated on the output shaft of the piezoelectric motor is greatly influenced by the force of the rotor 3 and the stake 2 pushing against each other.

In the simplest construction, in which the rotor 3 is pressed against the stator in one place (FIGS. 5 and 6), the force generated by the pressure member 13 is transmitted to the bearing 4, so that the wear of the bearing 4 is accelerated.

A structure in which the rotor 3 contacts the stator 2 at several locations symmetrically arranged around the circumference (No. 12.15.2)
6.27.28.29.30), rotor 3
Due to the mutual compensation of all the forces acting on the bearing 4 from the bearing 4, wear on the bearing 4 is prevented.

For piezoelectric motors operating without bearings, it is sufficient to press the rotor 3 and the stator 2 against each other in three places.

A pressure member 13' is connected to the shaft 1 between the bearing 4 and the rotor 3.
5 (FIG. 11), the pressure member 13'
The force acts to prevent the rotation of the rotor 3 to some extent.

This effect can be eliminated by attaching the pressure member 13/ to the rotor 3 (Fig. 8゜29.30), and also by attaching two pressure members 13/ to the rotor 3. (Fig. 27.28).

When two types of vibrations are excited in a reversible piezoelectric motor, the optimal relationship between the phases of each vibration, which transmits the drive torque and changes the force with which the rotor and stator press against each other, is not necessarily always the case. It's not something you can get.

Therefore, in order to be able to correct this phase relationship, it is necessary to connect the electrode pair 11° 21 (FIG. 8) used to excite one type of vibration to the power source via the phase shifter 6. It's convenient.

In general, considering that the power consumed by changes in the force of the rotor and stator pushing against each other is generally sufficiently smaller than the power consumed to generate the driving torque applied to the rotor 3, the phase shifter Conveniently, 6 is connected to electrodes which are used to vary the force with which the rotor and stator press against each other.

In order to reverse the rotation of the motor (FIG. 35) having a hollow cylindrical stator 2, the arm 41 is rotated by a specified angle and the rotor is displaced corresponding to the rotation angle.

For example, in this case, inside the piezoelectric element 8,
For example, third harmonic vibration of runout vibration and first harmonic vibration of longitudinal vibration (along the generatrix of the cylinder) are excited.

This harmonic order combination corresponds to the opposite direction of rotation of the rotor 3 when it is pressed against the stator 2 from the left and from the right, respectively.

In the structure of a piezoelectric motor that can be mechanically reversed (the third
6), the oscillator 7 of the stator 2 initially or normally rotates the rotor 3 in a clockwise direction.

When the reversing device 43 is activated, the body 44' is pulled together.

In order to counteract the effect of the pressure member 13, this pulling force pulls the rotor 3 away from one transducer 7 and towards the other transducer 7.
to engage.

The rotation of the rotor 3 is thereby reversed.

One feature of the piezoelectric motor disclosed herein is that it can operate over a wide power supply voltage range.

Importantly, we were able to expand the operating voltage range by selecting the optimal structure of the piezoelectric element itself, rather than at the expense of complicating the motor structure by increasing the number of coils. be.

Therefore, if it is necessary to operate with a power supply with a high output voltage, that voltage is applied across the width of the piezoelectric element (17th
), or applied along the length of the piezoelectric element (17th
Figure C1 Figure 18).

If piezoelectric elements are connected in series, the supply voltage can be correspondingly increased by a factor of 2 to 5 (Fig. 18.20, Fig. 21b).
).

Many of the advantages of the piezoelectric motor described above remain even when the piezoelectric motor is operated as a generator.

The operation of a non-reversible motor in operation as a generator is based on phenomena as explained below.

When the rotor 3 (FIG. 2) is rotated in the direction of clogging, a clogging phenomenon occurs, so that the vibrator 7 of the stator 2 is compressed.

This compression increases to a value of .

The oscillator then detaches itself. Then, the rotor 3 slips by a small angle, and the vibrator 7 returns to its original state.

This motion is accompanied by longitudinal and transverse vibrations.

When this motor is operating as a power generator, vibrations of the type that generate the drive torque applied to the rotor 3 are directly converted into electrical signals by the piezoelectric effect.

Since the spectrum of this electrical signal usually contains several harmonics, the power of the generated signal is only sufficient to perform rotational alignment of the rotor 3.

For this reason, these piezoelectric generators can be used as rotary transducers, for example for measuring the rotational speed of motors.

In order to excite the vibrator of the stator 2 or the vibrator of the rotor 3 to vibrate the seed wire that presses the rotor 3 against the stator 2, power is supplied by an external power source 5 (FIG. 38). It is possible to obtain a generator that can generate

In this case, the rotating rotor 3 transmits mechanical energy pulses to the piezoelectric element 8 at a frequency that controls the coupling.

These pulses excite the vibrator 7 at the same frequency as the holding frequency, and are converted in the piezoelectric element 8 into an electrical signal having a frequency that is the operating frequency of the piezoelectric motor.

Using the piezoelectric motor disclosed herein as a generator is practical when small electric power is required.

These motors can be easily attached to prime movers that rotate at relatively low angular velocities.

The advantages of this generator are its simple structure and high output frequency.

The production of this piezoelectric motor should be considered a quality breakthrough not only in the field of motor manufacturing, but also in electrical technology as a whole.

Obtaining low speeds without the use of auxiliary gearboxes No windings, resulting in ease of manufacture, low cost, non-flammability, conventional motors with power greater than IW 1.0 due to the simplicity of the conversion circuit when a DC power supply is used, and by connecting a small inductance ζ The rotational speed can be controlled by changing the power supply voltage, frequency and phase relationship, the rotational speed can be easily stabilized by selecting a high operating frequency, and the efficiency is 50% or more. Calculations show that with the corresponding piezoelectric material the efficiency can be 90% or more, the specific power in the shaft is as high as 0.2 W, "criJJ," and the power rating range is from 0.001 W to The main advantage of the piezoelectric motor of the present invention is that it has a wide power output of several tens of W. These advantages not only allow this piezoelectric motor to compete with conventional motors, but also expand the range of applications of the motor. It turns out.

Therefore, the development of integrated circuits, electronic components, electronic circuits, combined with piezoelectric motors, and advances in power supply technology have advanced us to the point where we can use robotic devices that can move independently in place of human power. Civilization will improve.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a piezoelectric motor according to the present invention, Fig. 2 is a perspective view showing the structure of a piezoelectric motor having a passive rotor, and Figs.
Figure 2f is an explanatory diagram for explaining the operating mode of the piezoelectric motor in Figure 2, Figure 3 is a schematic perspective view of the structure of a piezoelectric motor having an active rotor and an active stator, and Figure 4 is an explanatory diagram for explaining the operating mode of the piezoelectric motor in Figure 2. FIG. 5 is a schematic sectional view showing the structure of a piezoelectric motor in which the rotor and stator are mounted on a support. FIG. 6 is a plan view of the piezoelectric motor shown in FIG. 5. Figure 7 is a connection diagram of a reversible piezoelectric motor in which two types of vibrations are generated within the vibrator of the stator, and Figure 8 is a connection diagram of a piezoelectric motor in which a suppression member is attached to the rotor shaft. Schematic diagram: Figure 9 is a schematic diagram of the main parts of a piezoelectric motor in which longitudinal vibration and radial vibration are generated within the vibrator of the stator; Figure 10 is a diagram of a piezoelectric motor in which stator vibration and sliding vibration are generated. 11 is a schematic cross-sectional view of a flat piezoelectric motor having an active rotor and an active stator, and FIG. 12 is a schematic perspective view of a piezoelectric motor in which several transducers of the stakes are mounted on a movable frame. A schematic perspective view of the main parts, FIG. 13 is a sectional view of a wear-resistant lining fixed to a vibrator, and FIG. 14 is a schematic perspective view of a piezoelectric motor in which the cross section of the stator vibrator is variable. , FIG. 15 is a front view of a stator vibrator in the form of a spiral rotating body, FIG. 16 is a schematic perspective view of the main part of a piezoelectric motor in which the stator vibrator includes a metal layer, and FIG. 17 is a front view of a stator vibrator in the form of a spiral rotating body. Schematic perspective view showing electrode arrangement, No. 18
The figure is a schematic perspective view of a piezoelectric element of a vibrator including several regions connected in series, FIG. 19 is a schematic diagram showing the polarization mode of the regions of the piezoelectric element, and FIG. 20 is a fourth mode of acoustic vibration. A schematic diagram showing the series coupling of regions of a piezoelectric element which are made to vibrate with harmonics; FIG. 21 is a schematic diagram showing the interlayer coupling of a two-layer piezoelectric element; FIG. 22 is a diagram showing a two-layer coupling with electrodes on the end faces 23 is a schematic perspective view showing the parallel connection of electrodes of a piezoelectric element including several layers; FIG. 24 is a schematic perspective view showing the parallel connection of electrodes provided on the surface of the piezoelectric element. Figure 25 is a schematic diagram showing a cylindrical multilayer resonator;
6 is a schematic diagram of a piezoelectric motor with an active stator and a hollow cylindrical active rotor, FIG. 27 is a longitudinal cross-sectional view of a piezoelectric motor with an active rotor and an active stator made as a rotating body, and FIG. 28 is a diagram of FIG. A front view of the piezoelectric motor shown in FIG.
FIG. 9 is a longitudinal sectional view of another embodiment of the piezoelectric motor, FIG. 30 is a side view of the piezoelectric motor shown in FIG. 29, and FIG. 31 is a two-layer piezoelectric element designed to generate longitudinal vibration and bending vibration. Figures 32 and 33 are circuit diagrams of the simplest DC-AC converter for supplying power to the piezoelectric motor of the present invention, and Figure 34 is a schematic diagram of the main parts of the piezoelectric motor with an auxiliary rotor. A perspective view, FIG. 35 is a schematic vertical sectional view of a piezoelectric motor that can be mechanically reversed, FIG. 36 is a schematic diagram of the main parts of the piezoelectric motor including an electromagnet in the reversing mechanism, and FIG. 37 is a piezoelectric motor that operates as a generator. A circuit diagram showing how it is connected,
Fig. 38 is a circuit diagram showing a piezoelectric motor having three electrodes connected to operate as a generator, and Figs. 39 and 40 show a reversible piezoelectric motor having two pairs of electrodes operating as a generator. 41A and 41D are schematic diagrams for explaining longitudinal vibration and transverse vibration of the present invention. 2... Stator, 3... Rotor, 5...
...Power supply, 6...Phase shifter, 7...
・Stator oscillator, 8... Rotor oscillator,
7'...Piezoelectric element of stator, 8'...
- Rotor piezoelectric element, 10.10', 11.11'. 2L21', 31... Electrode, 13.13'...
... Pressure member, 15 ... Rotor shaft, 16.
...Plate, 17...Brush, 18.
... Lining, 19 ... Vibrator support, 22 ... Piezoelectric element layer, 23 ...
・Metal layer, 44... Electromagnet.

Claims (1)

[Claims] 1 comprising a stator and a rotor, the stator and rotor being pressed with a constant force, one against the other;
In a piezoelectric motor, a frictional contact is made between the stator and the rotor, and the frictional contact is made on the rotor surface formed by a rotation locus of a line segment centered on the axis of rotation of the rotor. At least one piezoelectric vibrator is provided on the stator, and a portion of the surface of the piezoelectric vibrator is in frictional contact with at least a portion of the surface of the rotor, and the piezoelectric vibrator generates longitudinal vibration in the frictional contact portion. and has a polarization and shape that causes transverse vibration, one of the longitudinal vibration and transverse vibration drives the rotor, and the other changes the force acting between the stator and rotor. piezoelectric motor.