JPH0246179A - Ultrasonic linear motor - Google Patents

Abstract

PURPOSE:To excite two flexural oscillations effectively by machining the neighborhood of both ends of an elastic body square pillar into circular cross sections and by supporting and fixing these cross sections. CONSTITUTION:An oscillator 20 used for an ultrasonic linear motor has an elastic body square pillar 16 with a square cross section. At the part equivalent to 0.22 of the length from both sides the pillar is machined to be a slit 19 with a circular cross section. The oscillator 20 is constituted by sticking piezoelectric bodies 17 and 18 to two rectangular surfaces side by side of the elastic body 16. When AC electric field close to resonance frequency is applied to this piezoelectric body 17, the oscillator 20 performs flexural oscillation in the direction of an arrowhead B; when AC electric field is applied to the piezopelectric body 18, the oscillator 20 performs flexural oscillation in the direction of an arrowhead C. In this way, a low oscillating energy will do because of stable movement of the oscillator 20.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an ultrasonic linear motor that generates driving force using elastic vibrations produced by a piezoelectric body.

BACKGROUND OF THE INVENTION In recent years, ultrasonic linear motors have attracted attention in which elastic vibrations are excited in a vibrating body made of a piezoelectric material such as a piezoelectric ceramic, and this vibration is used as a driving force.

Hereinafter, the conventional technology of ultrasonic linear motors will be explained with reference to the drawings.

FIG. 6 is an overview diagram of a conventional ultrasonic linear motor.
The disk-shaped piezoelectric bodies 1 and 2 are replaced by cylindrical elastic bodies 3 and 4.
The vibrating body 5 is configured by sandwiching and fixing the vibrating body 5 between the vibrating body 5 and the vibrating body 5.

When an alternating current electric field near the resonant frequency of the vibrating body 5 is applied to the piezoelectric bodies 1 and 2, the vibrating body 5 vibrates in the vertical vibration mode in the vertical vibration mode, as shown by the arrow in the figure.

The mechanical impedance seen from the vibration surface of the vibrating body 5 is impedance-converted by the horn 6, and matched to the mechanical impedance for the bending vibration of the transmission rod 7. The tip of the horn 6 is acoustically coupled to a portion of the transmission rod 7 near one end. Therefore, the vertical vibration of the vibrating body 5 is efficiently transmitted to the transmission rod 7 by the horn 6, and the transmission rod 7 bends and vibrates. This bending vibration progresses from one end of the transmission rod 7 to the other end.

In a part near the other end of the transmission rod 7, the horn 8 is connected as in the one end.
The tips of the two are acoustically coupled. By sandwiching and fixing the disk expansion piezoelectric bodies 9 and 10 between cylindrical elastic bodies 11 and 12, a moving body 13, which is exactly the same as the vibrating body 5, is constructed. This vibrating body 13 is connected to the horn 8. Therefore, the bending vibration that has progressed from one end of the transmission rod toward the other end is transmitted to the moving body 13 by the horn 8 and converted into vertical vibration of the vibrating body 13. A load R with impedance matching is connected to the piezoelectric bodies 9 and 10, and the above-mentioned vertical vibration is consumed by the load R. Therefore,
In the transmission rod 7, bending vibration exists only as a traveling wave.

A moving body 14 is driven by the bending vibration traveling through the transmission rod 7, and moves in a direction opposite to the traveling direction of the traveling wave. In the above description, the moving direction of the moving body 14 is assumed to be one direction, but if the driving end is reversed, the moving body 14 also moves in the opposite direction.

FIG. 7 shows the principle of how the traveling elastic wave of pounding drives the moving body. By photographing the deflection of the transmission rod 7, a point (for example, point A) on the surface of the transmission rod 7 draws an elliptical locus in the vertical direction W and the horizontal direction U. The velocity at the apex of this elliptical trajectory is opposite to the direction of travel of the wave. If the movable body 14 is placed on top of the transmission rod 7 under pressure, the movable body 14 will only touch the transmission rod 7 near the top of the wave.
come into contact with. Therefore, the movable body 14 is driven in the direction opposite to the direction in which the waves travel due to the frictional force between the transmission rod 7 and the movable body 14 and the speed in the lateral direction of the elliptical trajectory.

In addition, 15 in the same figure indicates the horizontal component of the elliptical locus,
A wear-resistant friction material for efficient removal.

Problems to be Solved by the Invention As described above, the conventional ultrasonic linear motor described above excites a Langevin-structured moving body in a longitudinal vibration mode, and transmits the vibration of the vibrating surface of the moving body to a transmission rod using a horn to excite bending vibration. Therefore, it is necessary to accurately match the mechanical impedance between the vibration surface and the horn, and between the horn and the transmission rod. In reality, this is very difficult and results in some losses.

Furthermore, in order to excite only traveling waves in the transmission rod, the vibration energy input from one side must be completely eliminated from the other side.

In addition, in order to move a relatively small moving body, the vibrating body and transmission rod must be moved. Therefore, there were problems of low efficiency and large dimensions.

Means for Solving the Problem A photographing body is constructed by fixing a piezoelectric material to two adjacent rectangular surfaces of an elastic prism having a square cross section, and the length of the prism is fixed at both ends of the prism, or between both ends. 0.
Process the vicinity corresponding to 22 so that it has a circular cross section,
The circular cross section is supported and fixed, and an alternating current electric field is applied to the two piezoelectric bodies to excite bending vibration in the vibrating body. , the above-mentioned photographing body is moved by being pressurized and installed on the rail.

Effect By applying an alternating current electric field to the two piezoelectric bodies, two bending vibrations with a spatially different phase of 90 degrees are excited in the vibrating body, and the vibration of one of the two rectangular surfaces of the vibrating body without the piezoelectric body is excited. By installing the surface under pressure on the rail and moving the above-mentioned moving body, the ratio of the vibration energy of the vibrating body to the mechanical output can be reduced, making it possible to reduce dimensions, reduce weight, and increase efficiency. can.

By processing both ends of the elastic prism, or the vicinity corresponding to 0.22 of the length of the prism from both ends, into a circular cross section, and supporting and fixing the circular cross section, the two deflection images can be obtained. so that the effect on the movement is the same.
The photographing body can be supported and fixed, and therefore the above two flexural vibrations can be efficiently excited.

EXAMPLE Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view of a vibrating body used in an ultrasonic linear motor according to an embodiment of the present invention. The elastic prism 16 having a square cross section has a slit 19 formed in the vicinity corresponding to a length of 0°22 from both ends so as to have a circular cross section.

The vibrating body 20 is constructed by bonding the piezoelectric bodies 17 and 18 to two adjacent rectangular surfaces of the elastic body 16, respectively. When an alternating current electric field near the resonance frequency is applied to the piezoelectric body 17, the vibrating body 20 bends in the direction of arrow B and performs imaging. Furthermore, when an alternating electric field is applied to the piezoelectric body 18, the vibrating body 20 bends and vibrates in the direction of arrow C.

FIG. 2 is a longitudinal displacement distribution diagram when only one piezoelectric body of the vibrating body of FIG. 1 is driven. Since the two deflection images are spatially out of phase by 90 degrees, the two piezoelectric bodies 1
When alternating current electric fields with a phase shift of 90 degrees are applied to 7 and 18, the rectangular surface of the vibrating body 20 rotates within a plane perpendicular to the rectangular surface. According to the displacement distribution shown in FIG. 2, the rotational motion is maximum at the center of the vibrating body 20.

The position of the slit 20 corresponds to the position of the node of the displacement distribution shown in FIG. As shown in FIG. 3, the vibrating body 20 is connected to supports A21 and A22 having semicircular holes, and a support 823 having two semicircular holes corresponding to the positions of the slits 20. By supporting and fixing via 20.

It is possible to fix the position with small loss and with the same effect on two bending vibrations. As a result, the impedance characteristics of the two vibrations match, and the control of the rotational movement described above becomes easy.

If the rail 24 is configured so as to touch the center of the rectangular surface of the vibrating body 20 to which the piezoelectric body is not bonded, the vibrating body itself will touch the rail 24 by applying an AC voltage to each of the two piezoelectric bodies. move along at maximum speed. In this embodiment, one vibrating body is used, but a similar motion can be achieved even if a plurality of vibrating bodies are arranged in parallel.

FIG. 4 is a perspective view of a vibrating body used in an ultrasonic linear motor according to another embodiment of the present invention. 25 is an elastic prism having a square cross section, and piezoelectric bodies 26 and 27 are adhered to two adjacent rectangular surfaces to form a vibrating body 28.

Both ends of the elastic body 25 are processed to have a circular cross section. When an alternating current electric field near the resonance frequency is applied to the piezoelectric body 26, the vibrating body 28 bends and vibrates in the direction of the arrow.

Furthermore, when an alternating current electric field is applied to the piezoelectric body 27, the moving body 2
8 bends and vibrates in the direction of arrow E.

FIG. 5 shows the displacement distribution in the length direction when one piezoelectric body of the vibrating body shown in FIG. 4 is driven. Similar to the bending vibration of the imaging body 20 shown in FIG. 1, the two bending vibrations are spatially 9
Since the phase is shifted by 0 degrees, if an AC electric field with a phase shift of 90 degrees is applied to the two piezoelectric bodies 26 and 27, the vibrating body 2
The rectangular surface of 8 rotates in a plane perpendicular to the rectangular surface.

According to the displacement distribution shown in FIG. 5, the rotational motion is maximum at the center of the vibrating body 28.

As shown in FIG. 3, by supporting and fixing the image pickup body 28 between two supports having semicircular holes so as to sandwich the circular cross section at both ends, the loss is small and the vibration is resistant to two bending vibrations. Position fixation with the same influence is possible. As a result, the impedance characteristics of the two vibrations match, and the control of the rotational movement described above becomes easy.

In addition, as in the case shown in FIG. 3, if the rail is configured so that it hits the center of the rectangular surface of the vibrating body 28 to which the piezoelectric body is not bonded, an alternating current voltage can be applied to each of the two piezoelectric bodies. By doing so, the vibrating body itself moves along the rail at maximum speed.

Effects of the Invention According to the present invention, by moving the vibrating body,
An ultrasonic linear motor can be realized using small vibration energy. In other words, it is possible to provide an ultrasonic linear motor with a simple structure, small size, light weight, and high efficiency.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a vibrating body used in an ultrasonic linear motor according to an embodiment of the present invention, FIG. 2 is a longitudinal displacement distribution diagram of the bending vibration of the moving body shown in FIG. 1, and FIG. FIG. 1 is a perspective view showing the support and fixation of the vibrating body and the configuration of the ultrasonic linear motor, FIG. 4 is a perspective view of the vibrating body used in the ultrasonic linear motor of another embodiment, and FIG. FIG. 6 is an overview diagram of a conventional ultrasonic linear motor, and FIG. 7 is an explanatory diagram showing the driving principle of the ultrasonic linear motor. 16...Elastic body, 17.18...Piezoelectric body, 19...Slit, 20...Vibrating body, 21.22... Support A, 23...
・Support B24...Rail, 25...
Elastic body, 26.27...Piezoelectric body, 28...
...Vibrating body. Name of agent: Patent attorney Shigetaka Awano and one other person

Claims (1)

[Claims] A vibrating body is constructed by fixing a piezoelectric material to two adjacent rectangular surfaces of an elastic prism having a square cross section, and the vibrating body is formed from both ends of the prism, or from both ends to 0.2 of the length of the prism.
The vicinity corresponding to 2 is processed to have a circular cross section, supported and fixed via the circular cross section, and an alternating current electric field is applied to the two piezoelectric bodies to excite two bending vibrations in the vibrating body. An ultrasonic linear motor, characterized in that the vibrating body is moved by pressurizing one of the two rectangular surfaces of the vibrating body without a piezoelectric body on a rail.