JPH0322872A - Ultrasonic motor device - Google Patents

Abstract

PURPOSE:To generate a high number of revolution in a low load and generate a high torque in a high load by a method wherein a plurality of oscillation bodies is arranged concentrically and a traveling wave is excited in the elastic body of one oscillation body while a stationary wave is generated in the elastic body of the other oscillation body. CONSTITUTION:A rotor 21 is formed integrally with a rotating piece 23 and another rotating piece 25 while the rotor 21 is arranged pivotably by a shaft 31 arranged in a supporting table 3. An oscillation body 5, having a larger outer diameter, and another oscillation body 9, having an outer diameter smaller than the same of the oscillation body 5, are constituted of annular elastic bodies 13, 17 and annular piezo-electric bodies 15, 19 which are provided with outer diameters same substantially as annular grooves respectively. When a traveling wave is excited in the elastic body 13 of the oscillation body 5 having a larger outer diameter, a high torque may be obtained while a high number of revolution may be obtained upon a low load when the traveling wave is excited in the elastic body 17 of the oscillation body 9 having smaller outer diameter.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an ultrasonic motor device, which is particularly capable of increasing torque under high loads and increasing rotation speed under low loads. The present invention relates to an ultrasonic motor device.

(Prior Art) In recent years, various ultrasonic motors that obtain driving force from ultrasonic vibrations have been developed and put into practical use. This type of ultrasonic motor has fewer parts than conventional motors and is simpler to configure, and can also achieve stable rotation and high torque in the low-speed rotation range, as well as high responsiveness and holding torque. It has various advantages such as no lines of magnetic force.

Further, drive methods for ultrasonic motors include a "traveling wave method" and a "standing wave method." The structure and operation of the "traveling wave type" ultrasonic motor will be explained below.

In a conventional ultrasonic motor, a piezoelectric body having the same shape as the elastic body is fixed to an annular elastic body to form a vibrating body. By applying a frequency voltage of a predetermined frequency to this piezoelectric body, a standing wave is excited in the vibrating body, and the space becomes λ in time.
A traveling wave is generated from two standing waves with a /4 phase shift.

This traveling wave causes an arbitrary point on the surface of the elastic body (hereinafter referred to as a mass point) to perform an elliptical motion, causing the rotor placed on the elastic body to rotate in the opposite direction to the traveling direction of the traveling wave. I have to.

As described above, since the peak of the traveling wave contacts the rotor and rotates the rotor, when the outer diameter of the vibrating body is small, the maximum torque generated in the ultrasonic motor is low and the no-load rotation speed is low. If the outer diameter is large, the maximum torque will be high and the no-load rotation speed will be small.

(Problem to be Solved by the Invention) However, if we assume that this ultrasonic motor is applied to an electrically retractable door mirror, for example, although a high rotation speed is required during low load to normally rotate the door mirror, When the vehicle is frozen, high torque is required to rotate the door mirrors.

Therefore, in order to obtain a large maximum torque, the vibrating body 4'l
) It is possible to set the outer diameter to a large value.

1- However, the outer diameter of the vibrating body is set to a large value, l.
．． ．． ．． :S and can obtain large maximum torque,
Although the torque generated in the direction opposite to the moment of stopping, so-called lock torque, increases, the number of rotations decreases, which is a problem to be solved.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an ultrasonic motor device that can obtain high rotational speed during low loads and high torque during high loads. .

[Structure of the Invention] (Means for Solving the Problems) The present invention provides means for achieving the above object. death,
In an ultrasonic motor device that drives a movable body disposed in contact with an annular surface of the elastic body by a traveling wave excited in the elastic body, a plurality of the vibrating bodies are arranged concentrically, and the movable body The body is brought into contact with the toric surfaces of the respective elastic bodies, and a traveling wave is excited in the elastic body of one vibrating body, and a standing wave is generated in the elastic body of the other vibrating body. do.

(Function) The present invention forms a vibrating body by fixing a piezoelectric body to an annular elastic body. In addition, a plurality of vibrating bodies with different outer diameters are arranged concentrically. Furthermore, a movable body is arranged so as to be in contact with the toric surface of each elastic body. By exciting a traveling wave in the elastic body of any one of the plurality of vibrators, a movable body placed in contact with this vibrator is driven. Further, at this time, by exciting a fixed flower wave to the elastic body of the other vibrating body, the contact resistance of the other vibrating body with the movable body is reduced.

Therefore, by appropriately selecting a vibrating body that excites a traveling wave from among a plurality of vibrating bodies having different outer diameters, an optimal driving state can be obtained. For example, if a traveling wave is excited in an elastic body of a vibrating body having a large outer diameter, a large torque can be obtained. Furthermore, by exciting a traveling wave in the elastic body of the vibrating body with a small outer diameter, a high rotational speed can be obtained under low load.

(Example) Hereinafter, an example according to the present invention will be described in detail with reference to the drawings.

First, the general structure of the ultrasonic motor 1 of this embodiment will be explained with reference to the longitudinal cross-sectional view of FIG.

The support base 3 is a disc body with two annular grooves arranged concentrically on two sides, and a hole is bored in the center of the disc body. Further, a shaft 31 passing through this hole by one inch is rotatably supported by a bearing 35 disposed on the f-plane side of the support base 3.

The vibrating body 5 having a large outer diameter and the vibrating body 9 having an outer diameter smaller than this vibration +45 are each a circular ring having an outer diameter approximately the same as that of the full ring, as shown in FIG. It is composed of an elastic body 13.17 and an annular piezoelectric body 15.19 fixed to the lower surface of the supple body 13.17.

The elastic bodies 13.1.7 each have flannel 13a on the inside.
, 1.7a, and this flange 13g, 1.7a.
Vibration absorbing material 7.11 made of rubber or other material on the bottom side of a.
The elastic bodies 13 and 17 are respectively fixed to the protrusions between the annular structures formed on the support base 3 via the vibration absorbers 7 and 11.

In the annular piezoelectric body 15, a plurality of polarized electrostrictive elements are arranged in each region A and B. The electrostrictive elements in each of the coverage areas A and B are arranged so that their phases differ by 90@ from each other. Also area A
As shown in FIG. 5, electrodes 5a and 5b are provided on the electrostrictive elements in regions B and B, respectively. This electrode 5a
When a frequency voltage of a predetermined frequency having a phase difference of 90° from each other is applied to the elastic body 13 and 5b, a progressive vibration wave, that is, a traveling wave is generated, causing a mass point on the surface of the elastic body 13 to move in an elliptical manner.

Furthermore, when frequency voltages of the same phase are applied to the electrodes 5a and 5b, a standing wave is excited on the surface of the elastic body 13.

Similarly, on the piezoelectric body 19 fixed on the surface of the annular body 17, a plurality of polarized electrostrictive elements are arranged in regions A and B, respectively. The electrostrictive elements in these regions A and B are arranged so that their phases differ by 90@ from each other. Furthermore, electrodes 9a and 9b are provided on each of the electrostrictive elements in region A and region B, as shown in FIG. These electrodes 9a and 9
When frequency voltages of a predetermined frequency with a phase difference of 90'' are applied to the electrodes 9a and 9b, a traveling wave is generated and causes the mass point on the body 17 to move in an elliptical manner.Furthermore, a frequency voltage of the same phase is applied to the electrodes 9a and 9b. When applied, a standing wave is excited onto the elastic body 17.

The rotor 21 has a rotor 23 and a rotor 25 integrally formed. An annular rotor 2 provided facing the vibrating body 5
A lining 27 made of a material with excellent wear resistance and a high coefficient of friction is fixed to 3.
It is provided in contact with the annular surface of the elastic body 13 via. Further, a lining 29 is fixed to the annular rotor 25 provided facing the vibrating body 9, and is provided in contact with the annular surface of the corresponding elastic body 17 via the lining 29.

The rotor 21 is fixed to the shaft 31 via a leaf spring 33. Further, the elastic force of the leaf spring 33 fixes the rotor 21 to the vibrating bodies 5 and 9 in a pressed state.

In addition, a shaft 31 is rotatably provided in the center of the support base 3, and a rotor 2 is fixed to the shaft 1, 31.
1 is also rotatably provided with respect to the support base 3. Also, the shaft 31 of the rotating part in which the bearing 35 is inserted
A screw 37 is attached to the holder.

FIG. 3 is a graph showing the rotation speed relative to the torque of the ultrasonic motor. Curve A shown in FIG. is a characteristic curve of an ultrasonic motor having only an annular vibrating body 9 with a small outer diameter.

As is clear from FIG. 3, the ultrasonic motor having the characteristic of curve A can obtain a large torque, but on the other hand, the number of rotations decreases. On the other hand, an ultrasonic motor having the characteristic of curve B can obtain a large number of revolutions, but the torque decreases. Therefore, in the embodiment according to the present invention, the torque TK at which both curves intersect, below, the vibrating body 9 shown on curve B is driven, and conversely, the torque TK, above, the vibrating body 5 shown on curve A is driven. That's what I do.

That is, the torque applied to the ultrasonic motor 1 is torque TK
, or more, a traveling wave is generated in the vibrating body 5 to rotate the rotor 23 corresponding to the vibrating body 5. At this time, a standing wave is generated for the other vibrating body 9 to reduce the frictional force between the vibrating body 9 and the rotor 25.

Conversely, when the torque applied to the ultrasonic motor is less than torque TK, a traveling wave is generated in the vibrating body 9 to rotate the rotor 25 corresponding to the vibrating body. Also, at this time, by generating a standing wave on the vibrating body 5, the vibrating body 5 and the rotor 2 are
3 to reduce the frictional force between the two.

Next, a circuit configuration for driving the ultrasonic motor according to the present invention will be explained with reference to FIG.

The electrode 5C is arranged on an electrostrictive element that is insulated from the aforementioned electrode 5a s')b, and the electrode 5d outputs a detection signal according to the vibration state of the electrostrictive element A.
This is a common electrode for a, 5b and 5c.

Similarly, the electrode 9C is placed on an electrostrictive element that is insulated from the electrodes 9a and 9b described above, and outputs a detection signal according to the vibration state of this electrostrictive element. Matata Den II! 9d is the electrode 9a
Common electrode for s9b and 9C.

Control circuit 41 is connected to electrodes 5C and 9C.

This control circuit 41 is a micro combination. It has an arithmetic processing means such as a single controller, and controls the entire device. Specifically, it has a resonant frequency automatic tracking circuit section, and performs automatic tracking so that the driving frequency of the frequency voltage applied to the vibrating body 5 or 9 becomes a value near a specific resonant frequency.

Therefore, if the drive frequency fluctuates due to temperature changes, etc.;'. l This vibration frequency automatic tracking circuit unit tracks the value of the drive frequency to a value near the resonance frequency.

Further, the control concave passage 41 has a 1-lux detection means for detecting the torque of the ultrasonic motor 1. Physically the 4th
As shown in the figure, it is known that when the torque of the ultrasonic motor 1 increases, the electric current increases accordingly. Therefore, the torque 1, which is the threshold level, increases. A current value l1 corresponding to K1 is stored, and if the power supply current is larger than this threshold current value 1., it is determined that the torque of the ultrasonic motor 1 is greater than torque Tkl.

Conversely, if the power supply current is less than the current value 1, it is determined that the torque of the ultrasonic motor 1 is less than the torque TK.

The control circuit 41 is connected to the traveling wave generation circuits 43, 53 and the standing wave generation circuits 44, 54, respectively, so that, for example, the torque of the ultrasonic motor 1 is 1·L TK. When it is determined that the above is the case, the traveling wave generation circuit 43 and the standing wave generation circuit 54 are driven.

Conversely, when it is determined that the torque of the ultrasonic motor 1 is less than the torque TK, the standing wave generating circuit 441 and the traveling wave generating circuit 53 are driven.

The traveling wave generating circuit 43 is connected to the electrode 5a via an amplifier 45 and a coil 46, and is also connected to the electrode 5b via an amplifier 47 and a coil 48, so that the traveling wave generating circuit 43 is out of phase with respect to both electrodes. 90'' different frequency voltages are applied. This excites the vibrating body 5 and generates a traveling wave.

The standing wave generating circuit 44 is connected to the electrode 5a via an amplifier 45 and a coil 46, and is also connected to the electrode 5b via an amplifier 47 and a coil 48. Apply a frequency voltage with a phase of . As a result, standing waves are generated in the vibrating body 5.

The traveling wave generating circuit 53 is connected to the electrode 9a via an amplifier 55 and a coil 56, and is also connected to the electrode 9b via an amplifier 57 and a coil 58. 90@apply different frequency voltages. As a result, a traveling wave is generated in the vibrating body 9.

The standing wave generating circuit 54 is connected to the electrode 9a via an amplifier 55 and a coil 56, and is also connected to the electrode 9b via an amplifier 57 and a coil 58. Frequency voltages having the same phase are applied to 9a and 9b. As a result, standing waves are generated in the vibrating body 9.

Next, the operation will be explained with reference to FIG.

When the ultrasonic motor 1 starts driving, the vibrating body 9 is driven. Therefore, when the power switch (not shown) is turned on in step S1, the control circuit 41 drives the standing wave generation circuit 44 and the traveling wave generation circuit 53. This causes the vibrating body 5 to generate a standing wave and the vibrating body 9 to generate a traveling wave. As a result, the rotation T-25 corresponding to the vibrating body 9 is driven, and the rotor 21 is rotated. At this time, since a standing wave is generated in the vibrating body 5, the holding torque between the cicada body 13 and the lining 27 is released.

Subsequently, in step S3, the power supply current 9 to the elastic body 9 is
The value of is monitored, and the current value Ul of this current value I9 is the reference value! If it is greater than or equal to τ, {・1 and step S
Return to step 1 and continue to drive the ζ vibrating body 9.

Conversely, in step S3, the current value l9 is
jjl. If it is less than I1, the process advances to step S5, and the vibrating body 5 is driven. That is, the control circuit 41 drives the traveling wave generation circuit 43 and the standing wave generation circuit 54.

As a result, a traveling wave is generated in the vibrating body 5, and the rotor 23 corresponding to the vibrating body 5 is rotated.

At this time, since a standing wave is generated in the other vibrating body 9, the holding torque between the elastic body 17 and the lining 29 is released.

Subsequently, in step S7, the power supply current I5 for the vibrating body 5 is
The value of is monitored, and this current value l5 is the current value which is the reference value! , or less, the process returns to step S5 and continues to drive the vibrating body 5.

If the current value l5 is equal to or greater than the current value i1 in step S7, the process returns to step S1 and the vibrating body 9 is selected and driven.

As described above, the torque of the ultrasonic motor is determined based on the value of the power supply current to the vibrating body, and the vibrating body to be driven is selected according to the value of this 1 lk, so a simple circuit structure or Accordingly, an appropriate vibrating body can be easily and reliably selected from a plurality of vibrating bodies.

Incidentally, in this embodiment, the rotor 23 and the rotor -r25 are constructed as one unit, but the present invention is not limited to this, and for example, a plate spring may be provided on each of the rotor 23 and the rotor 25. Even if the driving force is obtained through this leaf spring, the object of the present application can be achieved and the gist of the present application is not departed from.

[Effects of the Invention] As explained above, according to the present invention, a plurality of vibrating bodies having different array shapes are arranged concentrically, and each movable body is brought into contact with the circular curve of the elastic body, so that one vibrating body Since a traveling wave is generated at the same time as a standing wave is generated at other vibrating bodies, high torque can be obtained, and high rotational speed can be obtained at low load.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view of an ultrasonic motor according to the present invention, Fig. 2 is an explanatory diagram showing vibrating bodies arranged in a concentric opening shape and having different numbers of outer diameters, and Fig. 3 is an ultrasonic motor 01.・A graph showing the rotation speed versus torque, FIG. 4 is a graph showing the value of power supply current versus torque of the ultrasonic motor, and FIG. 5 is a block diagram showing the drive circuit for driving the ultrasonic motor.
FIG. 6 is a flowchart showing the control processing of the same control path. 5, 9... Vibrating body 13, 17... Elastic body] 5, 19... Piezoelectric body 21... Rotor 23, 25... Rotor 41... Control circuit 43, 53... - Traveling wave generation circuit 44, 54...Standing wave generation circuit 37 Fig. 1

Claims (1)

[Claims] A vibrating body is formed by fixing a piezoelectric body to an annular elastic body,
In an ultrasonic motor device that drives a movable body disposed in contact with an annular surface of the elastic body by a traveling wave excited in the elastic body, a plurality of the vibrating bodies are arranged concentrically, and the movable body The ultrasonic device is characterized in that the body is brought into contact with the toric surface of each elastic body, and a traveling wave is excited in the elastic body of one vibrating body, and a standing wave is excited in the elastic body of the other vibrating body. Sonic motor device.