JPH0697859B2 - Ultrasonic elliptical transducer - Google Patents

Description

TECHNICAL FIELD The present invention relates to an ultrasonic elliptical oscillator, and more particularly to improvement of its characteristics.

[Conventional technology]

As an ultrasonic elliptical oscillator used for a drive source of an ultrasonic motor, a cantilever ultrasonic torsion elliptical oscillator (Japanese Patent Application No. 59-170380) already proposed by the present inventor shows particularly excellent characteristics. It is getting attention. However, it is a relative expression that the characteristics are excellent, and there are almost no conventional ultrasonic transducers that can directly generate elliptical vibration, and even if they exist, only those with low generation efficiency can be found. This is because the.

The present inventor has subsequently studied in detail the relationship between the design condition and the characteristic of the cantilever elliptical oscillator, and as a result, the function of the torsional connector, which is the main constituent element of the elliptic oscillator, can be more efficiently achieved. We have found the optimum conditions that can be exhibited. That is, the conventional torsional connector has the drawback that it has not been manufactured under quantitative design conditions.

[Problems to be solved by the invention]

The present invention solves the drawback that the conventional ultrasonic elliptical oscillator has been designed exploratoryly, so that its function has not been fully exerted, and based on theoretical optimum design, it has an excellent super performance. An object is to provide a sound wave elliptical oscillator.

[Means for solving problems]

The ultrasonic elliptical oscillator is the vertical vibration of the piezoelectric thickness oscillator.It excites the flexural vibration of the torsional coupler and couples it with the torsional vibration to form an elliptical vibration on the end face of the ultrasonic oscillator. Is generated. In other words, the ultrasonic elliptical oscillator must be a resonance system for all of vertical vibration, flexural vibration, and torsional vibration. It was considered impossible to satisfy this condition with the actual complicated shape of the oscillator, but rather I was content with the fact that good results were obtained from experimental trials. However, since they are accidental products, the yield is low and they are not suitable for mass production.

Therefore, a theoretical study was conducted, and the optimum conditions for the torsional connector were first determined and a separate application was filed. Here, as the condition of the warp vibrator that ideally excites the flexural vibration of the torsional coupler, the neck of the cap bolt that connects the torsional connector that excites at the resonance frequency fr (B) of the flexural vibration and the piezoelectric thickness oscillator is used. The conditions under which a 1/4 wavelength warp wave with respect to fr (B) was selected along the height from the surface to the upper surface of the beam of the torsion coupler.

〔Example〕

FIG. 1 is a front view showing an embodiment of an ultrasonic elliptical oscillator according to the present invention, and FIG. 2 is an explanatory view of its shape and dimensions. The ultrasonic elliptical oscillator is configured to excite the torsion coupler 1 by the vertical vibration of the piezoelectric thickness oscillators 6 and 7.

As one example, the torsion connector 1 is made of aluminum and has a groove 3 of 16.5 mm in width at the bottom of a disk 1a having a diameter D of 30 mm and a thickness T of 7 mm. The thickness of the disk 1a of the crescent-shaped leg 4 on both sides is 7.5mm, that is, the leg 4 is 0.5mm thick, and the center of the groove 3 is 8mm in diameter.
The cap bolt has a screw hole, and a beam 1 with a height of 10.6 mm and a thickness of 7 mm is provided diagonally with the groove 3 on the upper part of the disc 1a, from the bottom of the crescent leg part 4. The height h of the connector to the upper surface of the beam 2 is 18.1 mm.

When the leg 4 is vertically vibrated and excited, a disc 1a is produced at a frequency of 42 KHz.
A bending resonance occurs in the beam 2, which causes a torsional vibration in the beam 2. The torsional vibration is coupled with the torsional resonance of the beam 2 with respect to the axis of the disc 1a, and twists along the height h of the torsion connector 1. 1/4 wavelength of vibration stands. Therefore, the vertical vibration of 42 KHz couples the vibration with the torsional vibration of the same frequency.
Elliptical vibration is generated on the upper surface of, that is, on the end surface of the ultrasonic elliptical transducer.

To construct an ultrasonic motor using the ultrasonic elliptical vibrator as a stator, it is better to design the vertical component of the amplitude of the elliptical vibration so as not to be smaller than the horizontal component. For example, the thickness vibration generated when a sine wave voltage of 42 KHz is applied to the piezoelectric thickness vibrators 6 and 7 through the terminal plate 9 is amplified by the aluminum vibrating body plate 5, and the leg portion 4 of the torsion coupler 1 is vibrated. give. Therefore, from the neck surface 10a of the cap bolt 10 connecting the two piezoelectric thickness vibrations 6 and 7, the vibrating body plate 5 and the torsional connector 1 to the upper surface of the vibrating body plate 5,
That is, it is designed so that the wavelength rises to 1/4 of the vertical vibration up to the bottom surface (Hh) of the crescent moon leg portion 4 of the torsion connector 1. In other words, (H-h) = 31.2mm, the thickness of the body plate 5 is 28.9mm
Then, a strong warp vibration acts on the crescent moon leg portion 4, but this warp vibration becomes smaller along the height h of the torsional vibrator, and attenuates to an amplitude of 1/2 or less on the upper surface of the beam 2. Therefore, the elliptical vibration combined with the torsional vibration of the connector 1 is flat, and the vertical component is less than 1/2 of the horizontal component, which is not suitable for the purpose.

On the contrary, when the thickness of the body plate 5 is set to 10.8 mm, the height H between the neck surface 10a of the cap bolt 10 and the upper surface of the beam 2 is H = 31.
A 1/4 wavelength of the vertical vibration of 2 mm rises and violent vertical vibration occurs on the upper surface of the beam 2. At this time, the amplitude of the vertical vibration acting on the leg portion 4 of the torsion coupler 1 is about half the amplitude of the upper surface of the beam 2, and the amplitude of the torsional vibration generated thereby is amplified by the resonance system. It becomes a value slightly smaller than the amplitude of the vertical vibration of the upper surface, and the synthesized elliptical vibration becomes an elliptical vibration of a vertical length that is slightly closer to a circle, and an ultrasonic elliptical oscillator that generates the ideal ideal elliptical vibration at the end surface is generated. I was able to make it.

FIG. 3 is an exploded perspective view of an ultrasonic motor using this ultrasonic elliptical vibrator. Reference numeral 11 in the figure is a connecting bolt, which connects the above-described ultrasonic elliptical oscillator serving as a stator and the rotor 12. Reference numeral 14 is a coil spring loosely fitted to the connecting bolt 11, and 13 is an output shaft.

Although aluminum is used as the material of the torsional connector in the above embodiment, stainless steel, nickel, iron or the like, which has a small loss during ultrasonic vibration, may be used.

〔The invention's effect〕

By arranging the beam diagonally with respect to the center axis of the flexural vibration of the disk, the torsional vibration is generated in the beam through the flexural vibration of the disk excited by the vertical vibration. In an ultrasonic elliptical oscillator that combines torsional vibrations of the same frequency to generate elliptical vibrations on the upper surface of the beam and a piezoelectric thickness oscillator that excites this by vertical vibration, The height from the neck surface of the cap bolt that connects the child and the piezoelectric thickness vibrator to the upper surface of the beam of the torsional connector becomes equal to 1/4 wavelength of the warp wave excited at the bending resonance frequency of the disk. Configured as
Therefore, the ultrasonic elliptical vibrator according to the present invention can generate circular or vertical elliptical vibration at its end face, and has an effect of exhibiting excellent performance suitable for a stator of an ultrasonic motor.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of an ultrasonic elliptical oscillator according to the present invention, FIG. 2 is an explanatory view of its shape and dimensions, and FIG. 3 is an ultrasonic motor using the ultrasonic elliptical oscillator. It is an exploded perspective view. 1 ... torsional connector, 1a ... disk, 2 ... torsional connector beam, 3 ... torsional connector groove, 4 ... torsional connector leg,
5 ... Ultrasonic elliptical oscillator body plate, 6,7 ... Piezoelectric thickness oscillator, 8 ... Cap bolt washer, 9 ... Terminal plate, 10 ...
Cap bolt, 10a ... neck.

Claims (2)

[Claims] 1. A result of causing torsional vibration in a beam through bending vibration of a disk excited by vertical vibration by adopting a configuration in which a beam is arranged obliquely with respect to a center axis of bending vibration of the disk. , Vertical vibration and torsional vibration of the same frequency are combined,
In an ultrasonic elliptical oscillator that combines a torsional coupler that generates elliptical vibration on the upper surface of a beam and a piezoelectric thickness oscillator that is excited by vertical vibration, the torsional coupler and the piezoelectric thickness oscillator are connected. It is characterized in that the height from the neck surface of the cap bolt to the upper surface of the beam of the torsional connector is equal to 1/4 wavelength of a warp wave excited at the bending resonance frequency of the disc. Ultrasonic elliptical transducer. 2. The ultrasonic elliptical oscillator according to claim 1, wherein the height from the neck surface of the cap bolt to the upper surface of the beam is H, and the thickness of the disc of the torsion connector is T. , And the diameter is D, and the ultrasonic elliptical oscillator is characterized in that the relational expression H = 0.243 D ² / T is satisfied.