JPH01177879A - Oscillatory wave linear motor - Google Patents

Abstract

PURPOSE:To select the characteristics of thrust and speed arbitrarily by forming recessed sections so that the groove width of the left side face and right side face of a stator having a linear section is made to differ and bringing a stator substrate into pressure-contact with side faces with the exception of the neutral plane of the stator. CONSTITUTION:An oscillatory wave linear motor is composed of a stator 1, a piezoelectric element 5, a slider 9, a cushion 11, a stator substrate 12, a linear bearing 13, etc. When a plurality of recessed sections 4 in which the groove width of the left side face and right side face of the linear section of a resonator is made to differ are shaped to one end face of the resonator having the linear section constituted of an elastic body in the stator 1 and curved oscillations having amplitude in the thickness direction of the stator 3 are excited as the direction of transmission of oscillations in the longitudinal direction, amplitude is excited vertically, using a neutral face as a boundary and in the direction vertical to the thickness direction of the stator. The two oscillations, oscillations in the longitudinal direction with amplitude in the thickness direction are combined with oscillations in the left and right direction of the stator 1, thus acquiring oscillations having an elliptical orbit.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vibration wave linear motor, and particularly to an ultrasonic linear motor using ultrasonic vibration as a driving source.

(Prior technology) In recent years, ultrasonic linear motors that obtain linear motion by exciting ultrasonic vibrations using electromechanical coupling elements such as piezoelectric ceramics have attracted attention as motors that are small and can achieve high response characteristics. has been done. Regarding the vibration wave linear motor using ultrasonic waves, for example, the Institute of Electronics and Communication Engineers technical research report US86-16, US87-5, etc., JP-A-61
-35177 is introduced. An example of a conventional ultrasonic linear motor and its principle will be described below with reference to the drawings.

The ultrasonic linear motor shown in FIG. 5 is a traveling wave linear motor that uses a track-type vibrator, and has a piezoelectric element 5 bonded and integrated with the lower surface of a trunk-type elastic vibrator as a stator. As shown in FIG. 6, the piezoelectric element 5 has electrodes divided into two electrode groups A and B, and
) J4 (λ is the wavelength of the natural vibration mode of the stator 1) and are shifted by an odd number of times. Also, the length of each electrode (
The length in the track direction is set to 1/2 of λ, and the polarization directions of adjacent electrodes are alternately reversed as shown by + and - symbols in FIG. Then, by covering the surfaces of electrode groups A and H with conductive paint or by connecting them with conductive wires, the electrodes in electrode groups A and B are combined into one electrode. A slider is pressed onto the stator 1 with a predetermined pressure due to gravity or the force of a spring. The sliding surface of the slider is made of a wear-resistant material, for example, a lining surface 14 made of a composite plastic material with aromatic polyamide fiber as a filler and a polyurethane resin as a matrix.
By providing this, abrasion with the stator 1 is prevented.

Next, when alternating current voltages whose temporal phases are shifted by 90 degrees are applied to electrode groups A and B, each electrode alternately expands and contracts in the circumferential direction, and bending vibration occurs in the stator 1 due to the bimetallic effect. As a result, two standing waves are generated at electrode A and electrode B with a wavelength corresponding to the length of the two electrodes, which are shifted by 90 degrees in position and phase from each other, and are combined to form a traveling wave. . As shown in FIG. 7, when focusing on one point C on the surface of the stator 1, the traveling wave on the stator 1 traces an elliptical trajectory.

Since the lining surface 14 is in contact with the apex of the traveling wave of the stator, the slider 9 can be moved by friction in the direction of the trajectory of the apex of the ellipse. move on. The speed of the slider is related to the speed of the elliptical trajectory, and the output thrust is between stator 1 and slider 9.
It is determined by the coefficient of friction between the

In addition, in JP-A-61-191278, a plurality of vibration waves are installed in the stator in order to increase the vibration amplitude in the longitudinal direction of the stator, which is obtained by exciting a bending traveling wave having an amplitude in the thickness direction of the stator, in the stator made of an elastic body. It is proposed that a convex portion be provided.

(Problem to be Solved by the Invention) The characteristic curve of the monitor representing the relationship between the speed and thrust of the slider of the vibration wave linear motor is as shown in Fig. 8. Like a linear step motor, it has the characteristic that the lower the speed, the greater the thrust. Furthermore, in the case of the ultrasonic motor, the stator's natural frequency and the corresponding vibration mode excited by the electrodes of the piezoelectric element are determined at the time of design, so the stator itself has unique characteristics. , the slope of the characteristic curve of thrust versus speed shown in FIG. 8 does not depend on the input voltage. Therefore, it is impossible to arbitrarily set the relationship between thrust and speed for a given input voltage. This is a drawback and problem of the ultrasonic linear motor compared to the conventional electromagnetic linear motor.

Further, in the case of an ultrasonic motor constituted by a stator provided with a plurality of recesses, the amplitude in the longitudinal direction at one end surface of the stator in contact with the slider changes depending on the depth of the four recesses.

Therefore, although the depth of the recess is one variable that controls the speed of the slider, the depth of the recess also changes the natural frequency of the stator. For this reason, it may not be possible to set the natural frequency of the stator within a desired excitation frequency range unless the thickness and width of the stator are corrected. This was a problem in ultrasonic linear motors, as it was a limitation when designing the stator. Note that the desirable excitation frequency here is
This is a frequency in the ultrasonic range ranging from 20 kHz, which is beyond the human audible range, to a frequency limited by the performance of the power source, for example, 200 kHz.

The purpose of the present invention is to enable the thrust and speed characteristics to be arbitrarily selected using the same stator, and to prevent the drive frequency from deviating from the ultrasonic range even when the outer shape of the stator is limited.
The object of the present invention is to provide a vibration wave linear motor that can set a wider range of thrust and speed than conventional ones.

(Means for Solving the Problems) The present invention provides a stator having a structure in which a vibrator for converting an electric signal having a vibration waveform into mechanical vibration is provided on one end surface of a resonator having a straight portion made of an elastic body. In the vibration wave linear motor in which the resonator and the slider are in pressurized contact, a plurality of four parts are provided on the other end surface of the resonator, the left side surface and the right side surface having different groove widths, and the stator side surface excluding the neutral surface of the stator. Furthermore, there is provided a vibration wave linear motor characterized in that the sliding surface of the slider having the left or right side surface as the sliding surface is pressed into contact with the sliding surface.

(Function) As shown in the top perspective view of the stator in FIG. 1(b), a groove width between the left side and right side of the straight portion of the resonator is formed on one end surface of the resonator having a straight portion made of an elastic body. When a stator 1 provided with a plurality of recesses 4 having different values is excited with a bending vibration having an amplitude in the thickness direction of the stator (the depth direction of the recess) with the longitudinal direction of the stator as the vibration transmission direction, the recesses 4 are The stator is excited with a vibration having an amplitude in a direction perpendicular to the direction in which the bending vibration is transmitted and perpendicular to the thickness direction of the stator, that is, in the left-right direction of the side surface of the stator, with the neutral plane of the elastic body as the boundary. This is because in a stator that has a plurality of four parts 4 having the above characteristics, the bending rigidity is different between the right and left sides of the stator, and when bending vibration is transmitted, the amount of expansion and contraction of the elastic body is different between the right and left sides of the stator. This is because the bending strain generated in the stator produces vibrations with amplitude in the left-right direction of the side surface of the stator. This vibration in the left and right direction of the stator and the vibration in the longitudinal direction, which has an amplitude in the stator thickness direction and is transmitted in the longitudinal direction, are obtained, and by combining these two vibrations, the side of the stator and the neutral The mass point on the right side or left side, excluding the intersection line with the surface, vibrates with an elliptical orbit. The vibration that excites the horizontal vibration of the stator described above may be a standing wave instead of a traveling wave, but by using a traveling wave that has an amplitude in the stator thickness direction, horizontal vibration and circumferential vibration can be obtained at the same time. Can be done.

The above-mentioned vibration that has an amplitude in the horizontal direction of the side surface of the stator has a phase reversed at the neutral plane of the elastic body, so the amplitude is zero at the neutral plane and increases as the distance from the neutral plane increases, and the elastic body It is maximum at the top or bottom.

Therefore, by changing the position where the slider makes pressure contact, the relationship between both thrust and speed can be defined. In other words, when the pressure contact position of the slider is close to the neutral plane, the ratio of change in thrust to speed becomes steep, resulting in a characteristic that prioritizes thrust over speed, and when the pressure contact position of the slider is close to the neutral plane. If the distance is far from , the ratio of thrust to speed becomes gentle, and a characteristic that gives priority to speed over thrust is obtained. Therefore, vibration wave linear motors with different characteristics can be obtained using the same stator.

Furthermore, the difference in groove width between the left side and right side of the stator in the recess is related to the amplitude of vibration amplitude in the left and right direction of the stator, and the difference in groove width between the left and right sides of the stator changes. By doing this, the speed can be changed by making the change in the natural frequency of the stator smaller than by changing the depth of the recess 4. This is due to the following reasons. That is, by changing the groove width between the left side and right side, the bending rigidity on the left and right sides of the stator changes, inducing lateral vibration. Compared to changing the depth of the four portions 4, changing the difference in groove width between the left and right side surfaces results in a smaller change in the natural frequency of the stator. Even when the width and thickness of the stator are specified, the difference in groove width between the left side and right side of the recess becomes a geometrical and dimensional parameter that determines the speed and thrust of the slider.

(Example) FIG. 1(a) is a sectional view showing the basic configuration of the present invention,
In the figure, 1 is a track-shaped stator made of an elastic material, and an electric signal, for example, a frequency of 44 kHz, is sent to a piezoelectric element 5 having an electrode structure shown in the explanatory diagram of FIG. An electric signal having a width of 100 nm is input to excite a bending traveling wave having an amplitude in the thickness direction of the stator. The track shape is shown in Figure 5 and is 80m long in the longitudinal direction.
It has m straight sections.

In addition, as shown in the perspective view of FIG. 1(b), the stator 1 has a groove width ratio of, for example, 1:2 on the left and right side surfaces of the stator.
A plurality of four parts 4 are provided at equal intervals. In this case stator 1
The shape and dimensions of the piezoelectric element 5 are predetermined so that its natural vibration matches the frequency of the intended input electrical signal. Further, as for the piezoelectric element 5, a traveling wave is generated by inputting electric signals having vibration waveforms whose phases are different from each other by 90 degrees to the electrode group A and the electrode group B of the piezoelectric element shown in FIG. 6.

The vibration in the thickness direction of the stator accompanying the traveling wave can provide a vibration amplitude 6 in the longitudinal direction of the stator as shown in FIGS. 2(a) and 2(b). At the same time, Figure 2 (c
) Vibration 7 with amplitude in the left and right direction as shown in the plan view of
occurs. In order to easily obtain a vibration amplitude of 7 in the thickness direction, the ratio between the thickness and width of the stator is preferably 0.5 to 3. The vibration amplitude 6 in the longitudinal direction of FIG. 2(a) caused by the traveling wave and the vibration amplitude 7 in the left-right direction of FIG. A vibration 8 having an elliptical orbit is generated on the side surface of the stator 1 except for the intersection line with the neutral plane. That is, Fig. 2(a)
, (b) and timings 31-34 in FIG. 2(c) are combined to become timings 31-34 of the elliptical orbit shown in FIG. 2(d). The vibration 8 generated on the left side surface of the stator 1 can be suppressed by applying a structure in which the slider 9 is brought into pressure contact with the side surface of the stator 1, as shown in the cross-sectional view of FIG. 1(a). The motion in the longitudinal direction near the apex of the orbit, that is, the motion in the longitudinal direction near the apex, that is, Fig. 2 (
In d), when the slider is located on the left side, the movement at timing 33 is converted into a linear movement of the slider, and when the slider is located on the right side, the movement at timing 31 is converted into linear movement of the slider. For the portion of the slider 9 that comes into contact with the stator 1, a material with excellent wear resistance, such as an aromatic polyamide synthetic resin, is used. In addition, if a configuration is adopted in which the pressurized contact position of the slider 9 on the side surface of the stator 1 can be changed in FIG. 1(a), in the drooping characteristic of the vibration wave linear motor shown in FIG. It is possible to change the slope of the stator even if the stator is the same, and a thrust or speed priority linear motor can be realized with the same stator.

Since the directions of the elliptical orbits of the right and left sides of the stator 1 are opposite in the part that contacts the slider 9, the near motor has the configuration shown in FIG. The direction of movement is opposite to that of the near motor.

FIG. 3 shows another embodiment of the traveling wave vibration excitation method, in which two Langevin oscillators 21 and 22 are used as the oscillators. The stator having the recessed portion is located between two vibrators, and these two vibrators excites a bending traveling wave having an amplitude in the thickness direction in the stator. The structure of the rotor and stator may be the same as that shown in FIG. 1(a).

FIG. 4 shows another embodiment in which the ratio of the groove widths on the left and right sides of the recess 4 provided in the stator 1 is changed. The dimensions of the stator 1, the depth, and the number of recesses 4 are the same as those shown in FIG.
) is larger than that of In the embodiment of the four parts 4 shown in FIG. 1(b) and the embodiment of the recessed part 4 shown in FIG. Comparing the radial vibration 13 of the outer edge of the tip of the concave portion shown in FIG. 4, the amplitude of the horizontal vibration of the four parts shown in FIG. A linear motor that is larger and therefore has four sections as shown in FIG. 4 has high speed, low thrust characteristics.

Note that any modification may be made without departing from the purpose, and the side surface shape of the recess 4 in FIG. 1(b) or FIG. does not limit the scope of the claims.

(Effects of the Invention) The recessed portion is provided so that the groove widths of the left and right side surfaces of the stator having a straight portion are different, and the left or right side surface is formed as a sliding surface on the stator side surface excluding the stator neutral surface. The stator has a configuration in which the sliding surfaces of the slider are in pressure contact with each other, and is obtained by inputting an electric signal to the vibrator and exciting a bending traveling wave having an amplitude in the thickness direction of the stator in the stator. By combining the vibration amplitude in the longitudinal direction and the vibration amplitude in the width direction perpendicular to the thickness direction and the longitudinal direction of the stator, which occur simultaneously with the vibration in the thickness direction of the stator, the intersection line between the stator side surface and the neutral plane can be determined. According to the vibration wave linear motor, which excites elliptical vibration on the side surface of the stator and generates thrust in a linear direction on the slider that comes into pressure contact with the elliptical vibration, by changing the position of the slider where the slider makes pressure contact, priority is given to the thrust or the speed is increased. This has the effect that a vibration wave linear motor having characteristics that give priority to can be realized using the same stator. Furthermore, by changing the difference in the groove width of the recess on the left and right side surfaces of the stator, there is an effect that the speed and thrust characteristics of the vibration wave linear motor can be changed.

The vibration wave linear motor of the present invention allows the characteristics of thrust and speed to be arbitrarily selected using the same stator, and even if the outer shape of the stator is limited, the driving frequency does not deviate from the ultrasonic range (a wider range than before). You can set the appropriate thrust and speed.

[Brief explanation of the drawing]

FIG. 1(a) is a sectional view showing an embodiment of the present invention;
b) is a perspective view showing the stator of the present invention, FIG. 2(a)-
(d) is an explanatory diagram showing the state of vibration according to the present invention;
Figure 4 is a perspective view showing a stator according to a second embodiment of the present invention, Figure 4 is a perspective view of the upper surface of the stator showing an embodiment of the four parts according to the present invention, and Figure 5 is a sectional view of a conventional vibration wave linear motor. , FIG. 6 is an explanatory diagram showing the polarization of the piezoelectric element bonded to the stator, FIG. 7 is an explanatory diagram showing the state of vibration due to traveling waves, and FIG. 8 is an explanatory diagram showing the drooping characteristics of the motor. DESCRIPTION OF SYMBOLS 1... Stator, 4... Recessed part, 5... Piezoelectric element,
9...Slider, 11...Cushion, 12...
Stator board, 13... Linear bearing, 14... Lining, 21.22... Langevin vibrator, A,
B... electrode group, C, D... one point on the stator surface.

Claims (1)

[Claims] In a vibration wave linear motor in which a slider is brought into pressurized contact with a stator having a structure in which a vibrator for converting an electric signal having a vibration waveform into mechanical vibration is provided on one end face of a resonator having a straight portion made of an elastic body. , a plurality of recesses are provided on the other end surface of the resonator, the left side surface and the right side surface having different groove widths, and the left or right side surface is a sliding surface on the stator side surface excluding the neutral surface of the stator A vibration wave linear motor characterized in that the sliding surface of a slider is brought into pressure contact.