JPH0479715B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application and Purpose of the Invention] The present invention relates to the improvement of an ultrasonic vibrator, and provides an ultrasonic vibrator that allows the vibrator to generate ultrasonic vibrations in an elliptical motion, and in which the excitation is facilitated. The purpose is to [Prior Art] The purpose of conventional ultrasonic transducers was to generate strong longitudinal vibrations, as typified by the Languevin type. On the other hand, the development of technologies that utilize the powerful rotational torque generated by ultrasonic vibrations, such as ultrasonic motors and ultrasonic parts feeders, has recently been progressing. Although various methods for generating rotational torque have been proposed, the most excellent method is, for example, to generate an elliptical motion on the surface of a motor stator and rotate a rotor that is crimped thereto. It would be convenient if the vibration surface of the ultrasonic vibrator could be used directly as a stator, but we could not find a way to efficiently generate strong elliptical motion on the surface of a single ultrasonic vibrator.
It was not practical because it required a combination of multiple exciters, which produced only low-efficiency and weak vibrations. [Means for Solving the Problems] The present invention solves the above-mentioned drawbacks of the prior art, and is an ultrasonic transducer that excites torsional vibration in a cylindrical torsional resonator using a piezoelectric vibrator. The above object has been achieved by selecting the relationship between the diameter and wall thickness of the cylinder so that bending vibration is parasitic on the surface. The present inventor has already developed a piezoelectric thickness vibrator, a longitudinal mode resonator, and a
We proposed a vibrator that integrates a torsion coupler and a torsion resonator. The principle is that a torsional resonator and a longitudinal vibration resonator are coupled by a torsional coupler, and it is necessary for both to resonate. However, it was subsequently discovered that a torsional resonator can oscillate torsional vibration simply by driving it with a piezoelectric thickness vibrator, and the present invention was created. The main component of the torsional/bending mode coupled ultrasonic transducer of the present invention is only a cylindrical torsional resonator,
Since there are no unnecessary restrictions such as longitudinal resonators or torsional resonators in the resonance conditions, it is possible to efficiently oscillate combined torsional and bending mode vibrations, and the design of the resonator has become easier. [Example] FIGS. 1 and 2 are a front view and a side view showing an example of an ultrasonic transducer. In the figure, 1 is a piezoelectric thickness vibrator made of ceramic, 2 is a lead wire attached to the electrode of the piezoelectric thickness vibrator 1, 3 is a torsion resonator, 4 is a washer, and 5 is a cap bolt for tightening these. As shown in these figures, the torsional resonator 3 of the vibrator of the present invention is basically a cylindrical shape with a bottom, and has a basic shape or a slightly modified shape. The basic elements of the torsion/bending mode coupling condition are the height and wall thickness of the cylindrical torsional resonator 3, and the diameter of the cylinder couples the two. Since changing the diameter changes the way of coupling, it is possible to arbitrarily realize various vibration modes in the vibrator. Note that the apparent shape of the actual vibrator is, for example, the torsion coupler 14 as shown in FIGS. 3 and 4.
However, the torsional coupler 14 is simply a means to improve the efficiency of generating torsional vibration in the torsional resonator 13 using the piezoelectric thickness vibrator 11, as shown in FIGS. 1 and 2. It is not necessary to use it.
In other words, the resonant frequency of torsional vibration generated in the vibrator is not affected by the torsional coupler. As it turned out that the longitudinal oscillator was completely unnecessary, it was excluded. The torsion coupler 14 is connected to the cylindrical torsion resonator 1 with a bottom.
When the bolts 15 are tightened and joined to the bottom of the housing 3, surprisingly, the length of the bolts 15 has the greatest influence on the excitation conditions of the resonance state. The torsional/bending mode coupled ultrasonic transducer of the present invention can excite vibrations in various modes depending on how it is designed, and has different functions, so it has a wide range of uses. Since it is not easy to explain how the excited vibration mode changes depending on the design method and how the function of the resonator changes, we selected 30 representative examples from among the examples. It is shown in the table below. These examples show how the vibration mode excited in the transducer and the transducer function change as the dimensions of each part of the torsional/bending mode coupled ultrasonic transducer of the present invention are changed. It is. First, in order to clarify the parts whose dimensions are to be changed, the dimension numbers of each part are shown in FIG. 4. In each of the examples shown in the table, the dimensions are the same for all examples: the thickness of the torsion resonator is 7 mm, and the thickness of the piezoelectric vibrator is 2 mm.
It is. If these were changed, the result would appear to be complicated and there would be a risk of confusion, and we could not find any content to be added as essentially new information, so we omitted the examples. In the table, the dimensions to be changed are roughly divided into five groups: torsion resonator, torsion coupler, piezoelectric vibrator, washer, and bolt.As for the resonator, coupler, and piezoelectric vibrator, there are multiple dimensions to be changed. , each subdivided. Examples are shown in order of the diameter of the resonator, and each group is distinguished by a double ruled line. The resonance frequency, vibration mode, and function of the vibration mode excited with the dimension change are shown in the right column. The configurations of the torsion/bending mode coupled ultrasonic transducer of the present invention can be roughly divided into three types shown in FIGS. 3, 4, and 5. The vibrators shown in FIG. 3 and FIG. 5 are made of the same parts and differ only in the way they are constructed. That is, the vibrator shown in FIG. 5 has a structure in which a torsion coupler 14, a piezoelectric vibrator 11 made of ceramic, and a washer 16 are housed inside a torsion resonator 13, and are secured by tightening from the inside with bolts 15, making it more compact. Another feature is that it is convenient for utilizing the vibration of the outer surface of the bottom of the resonator. In contrast, the vibrator shown in FIG. 4 is characterized in that the cylinder of the torsional resonator 13 is not a straight cylinder, but has a trapezoidal side surface. The difference between the model shown in Fig. 3 and the model shown in Figs. 2 and 4 is that H = Hw in the cylindrical dimension.
(models shown in Figures 3 and 5) or H≒Hw (models shown in Figure 4). In the table, Examples Nos. 4 and 6 are A type shown in FIG. 3, Example Nos. 5 and 7 are C type shown in FIG. 5, and Examples Nos. 8 to 16 are H-Hw type. = 7mm, and rather than a B-type, it is a shape with a chamfered bottom of an A-type, and is classified as an A-type. Example No.
1, 2, 3 and Example Nos. 17 to 30 are type B shown in FIG. The model name is shown in the rightmost column of the table.

【table】

〔Effect of the invention〕

As explained above, in a cylindrical ultrasonic torsional resonator excited by a piezoelectric vibrator, the present invention changes the relationship between the diameter and wall thickness with respect to the length of the cylinder so that bending vibration is parasitic on the cylindrical surface. The structure was designed to feature the selected features. Therefore, by changing the diameter and wall thickness conditions for the length of the cylindrical torsional resonator, the ultrasonic transducer can be adjusted to various surfaces of the resonator, such as side surfaces, end surfaces, inner surfaces, inner bottom surfaces, outer bottom surfaces, and the like. Since it is possible to generate various modes of elliptical vibration on the tangents of these surfaces, it is ideal for use as a vibrator for ultrasonic motors, for example, and is effective as a compensation for defective technology that did not exist in the past. big.

[Brief explanation of the drawing]

The figures are all for explaining the ultrasonic transducer according to the embodiment of the present invention, and FIGS. 1 and 2 are a front view and a side view showing an example of the ultrasonic transducer,
Figures 3, 4, 5, 13 and 14
The figure is an explanatory diagram showing another example of an ultrasonic transducer.
Figure, Figure 7, Figure 8, Figure 9, Figure 10, Figure 11
Figure, Figure 12, Figure 15, Figure 16, Figure 17,
FIG. 18, FIG. 19, FIG. 20, and FIG. 21 are diagrams explaining the principle of each embodiment of the present invention. 1, 11, 81...Piezoelectric thickness vibrator, 3, 1
3,71,83,111,121,123,12
5,141...Torsional resonator, 5,15,85...
bolt.

Claims (1)

[Claims] 1. In a cylindrical ultrasonic torsional resonator excited by a piezoelectric vibrator, the relationship between the diameter and wall thickness with respect to the length of the cylinder is selected so that bending vibration is parasitic on the cylindrical surface. An ultrasonic transducer that combines torsion and bending modes. 2. The ultrasonic transducer according to claim 1, characterized in that the relationship between the diameter and wall thickness of the torsion resonator cylinder relative to its length is selected so that a bending traveling wave is generated on the cylindrical surface.・Bending mode coupled ultrasonic transducer. 3. In the ultrasonic transducer described in claim 1, the relationship between the diameter and wall thickness of the torsional resonator cylinder relative to its length is such that a symmetrical bending standing wave is generated along the circumference on the cylindrical surface. A torsion/bending mode coupled ultrasonic transducer featuring selected features. 4. In the ultrasonic transducer according to claim 1, the relationship between the diameter and wall thickness of the torsional resonator cylinder with respect to its length is determined along the axis at at least one pair of locations on the axially symmetrical end face of the cylinder. A torsional/bending mode coupled ultrasonic transducer is selected such that elliptical vibrations with opposite directions are generated. 5. In the ultrasonic vibrator according to any one of claims 1, 2, 3, and 4, the vibration excitation efficiency is increased by using a torsion coupler. A torsional/bending mode coupled ultrasonic transducer featuring the following.