JPH03253274A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To monitor the movement of sliding elements in driving by providing a contact detection means for detecting electrical contact states of the first and second conductive materials forming the sliding elements of the first elastic body and second elastic body of conductive materials. CONSTITUTION:With ultrasonic oscillation of an elastic body 21, the first and second conductive sliding members 60 and 61 repeat contact and non-contact operations. As a result, voltage value of a DC power supply 62 is detected by a voltmeter 63 connected electrically to two conductive sliding members 60 and 61 through the contact and non-contact operations mentioned above. Accordingly, contact time and non-contact time of a deformed oval track are found out. Continuity and breaking information of voltage are sent to a control circuit 64, and behavior of a sliding plane is detected. According to the constitution, the behavior of sliding elements in driving can be detected.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ultrasonic motor using ultrasonic vibration energy as a driving source, and more specifically to an ultrasonic motor whose vibration state can be detected and controlled. It is related to.

[Prior Art] In recent years, various ultrasonic motors have been developed that utilize the high-frequency mechanical vibration energy of ultrasonic vibrators and use frictional force as a driving source.
Applied research is underway. In this method, a movable element is pressed against an ultrasonic vibrator, and thrust is generated by frictional force caused by the pressing force to perform relative motion. As a conventional example, a standing wave type ultrasonic motor is shown in FIG.

In the linear ultrasonic motor 1, an ultrasonic vibrator 3 is fixed to a yoke 2, and a drive section 4 is formed at one end of the ultrasonic vibrator 3. A movable element 5 is pressed onto the drive section 4 by a rubber roller 6, and the movable element 5 is attached to the yoke 2.
It is supported by linear bearings 7a and 7b fixed to.

In the linear ultrasonic motor 1 configured as described above,
When the ultrasonic transducer 3 is excited, the movable element 5 receives a driving force due to the substantially elliptical vibration of the ultrasonic transducer 3, and moves in the direction of arrow A in the figure. This driving force is generated by the frictional force between the drive section 4 and the movable element 5.

In such an ultrasonic motor, the vibration amplitude of the ultrasonic vibrator generally ranges from submicrons to several tens of microns, and the driving frequency ranges from several kHz to several tens of kHz.
The range of z is used.

[Problem to be solved by the invention] However, since the above-mentioned ultrasonic motor is driven with minute amplitude and at a high frequency of several kHz to several tens of kHz, it is difficult to know the behavior of the sliding parts during driving. That was extremely difficult. For this reason, it has been difficult to determine whether the ultrasonic motor is being driven in an optimal friction state.

The present invention has been made to solve the above-mentioned problems, and by providing a vibration state detection means in the sliding parts of an ultrasonic motor, it is possible to know the behavior of the sliding parts during driving. The purpose is to obtain an ultrasonic motor that can Another object of the present invention is to obtain an ultrasonic motor that can be driven in an optimal frictional state and, as a result, can operate with high efficiency and reduce wear.

[Means for Solving the Problems] In order to achieve this object, the ultrasonic motor of the present invention includes a first elastic body that performs ultrasonic vibration, and a second elastic body that is crimped to the first elastic body. In the ultrasonic motor in which relative movement occurs between the first elastic body and the second elastic body due to ultrasonic vibration of the first elastic body, a sliding portion of the first elastic body and the second elastic body is provided. includes first and second conductive sliding members made of a conductive material, and contact detection means for detecting an electrical contact state of the first and second conductive sliding members.

Alternatively, in the ultrasonic motor as described above, at least one of the sliding parts of the first elastic body and the second elastic body is formed of a piezoelectric element, and a detection device for detecting an output signal of the piezoelectric element is provided. have the means.

Furthermore, it is even better to change the vibration locus according to a signal from the contact detection means.

[Operation] In the ultrasonic motor having the above configuration, the first conductive sliding member is attached to the sliding portion of the first elastic body that performs high-frequency vibration, and is crimped to the first elastic body. A second conductive sliding member is attached to a sliding portion of the second elastic body. Therefore, the first and second conductive sliding members repeat contact and non-contact with the ultrasonic vibration of the first elastic body.

As a result, the behavior of the sliding surface is detected by the contact detection means electrically connected to the two conductive sliding members,
A desired vibration trajectory can be controlled.

Alternatively, a piezoelectric element is attached to a sliding portion of the first elastic body or the second elastic body that vibrates at high frequency, and the piezoelectric element vibrates in response to pressure changes on the sliding surface caused by ultrasonic vibration of the first elastic body. As a result, the output voltage of the piezoelectric element changes. As a result, it is possible to detect not only contact/non-contact of the sliding surfaces but also changes in the pressure force.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

The ultrasonic transducer used in the present invention can be used, for example, in Japanese Patent Application No. 1-46
An ultrasonic transducer including a mechanical resonator as proposed in the specification and drawings attached to the '866 application may be used. An example of the configuration will be described below with reference to FIG.

The ultrasonic transducer 11 includes an elastic body 21 having a rectangular prism shape.
A first piezoelectric body 22 for exciting bending vibration in the elastic body 21 is attached to the upper surface of the elastic body 21 .

Second piezoelectric bodies 23a and 23b for exciting longitudinal vibration in the elastic body 21 are attached to the side surfaces of the elastic body 21 that are substantially orthogonal to the mounting surface.

The longitudinal center of the elastic body 21 is fixed by fixing bolts 24a and 24b for fixing the elastic body 21. The other ends of the fixing bolts 24a and 24b are
It is fixed to bases 25a and 25b.

Electrodes 27a and 27b are provided on the upper surface of the first piezoelectric body 22.
has been installed. The elastic body 21 itself also serves as a ground electrode, and is grounded to the bases 25a and 25b via the fixing bolts 24a and 24b.

The electrode 26 of the first piezoelectric body 22 and the electrodes 27a and 27b of the second piezoelectric body 23a and 23b are connected to amplifiers 28a and 28b.
An oscillator 30 is connected to the input terminals of a and 28b through a phase shifter 29.

Furthermore, the elastic body 21 has a predetermined frequency f in its thickness direction.
The shape and dimensions are adjusted so that it bends in a secondary mode at both free ends, and longitudinally vibrates in a primary mode at both free ends in the longitudinal direction at the same frequency f.

Generally, the resonant frequency of longitudinal vibration propagating in an elastic body is
Depends on the length of the elastic body. Further, the resonance frequency of bending vibration in the thickness direction of the elastic body depends on the length and thickness. Therefore, since it is easy to design the elastic body 21 as described above, the details thereof will be omitted.

The operation of the composite vibrator 11 configured as described above will be explained below. First, when an AC voltage of the predetermined frequency f is applied to the first piezoelectric body 22 from the AC power source 30 to cause it to vibrate, the elastic body 21 resonates in the secondary mode of bending vibration, and a standing wave is excited. Next, when an AC voltage of the frequency f is applied to the second piezoelectric bodies 23a and 23b to cause them to vibrate, the elastic body 2
1 vibrates in the first mode of longitudinal vibration and is excited by a standing wave.

In other words, the positions where the fixing bolts 24 and 24 are fixed are nodes of each standing wave.

At this time, the first piezoelectric body 22 and the second piezoelectric bodies 23 and 23
By adjusting the amplitude and phase of the voltage applied to the elastic body 21, it is possible to generate approximately elliptical vibration of any shape in the elastic body 21.

In the above embodiment, an ultrasonic vibrator that excites the first-order mode of longitudinal vibration and the second-order mode of bending vibration and generates approximately elliptical motion vibration by combining them is described, but the present invention is not limited to this. Various vibrations such as vibration, bending vibration, shear vibration, and torsional vibration can be synthesized, and higher-order modes may also be used.

The basic operating principle of an ultrasonic motor that suitably utilizes the above-mentioned ultrasonic transducer 11 will be explained with reference to FIGS. 2 and 3. In this figure, each member given the same reference numeral as in FIG. 1 indicates that it is the same as each component described in detail above.

In FIG. 2, the ultrasonic motor 30 has drive elements 32 formed at both ends that provide the maximum amplitude of the ultrasonic vibrator 11, and is further abutted against a rail 34, which is a second elastic body. has been done.

FIG. 3 shows piezoelectric bodies 22 and 23a of the ultrasonic transducer 11,
23b is a diagram showing a voltage waveform of a human power signal applied to the terminal 23b.

When an AC electric signal is applied to the ultrasonic vibrator 11 to excite it, the composite vibrator 11 generates a driving force by repeating vertical and bending vibrations as shown in FIGS. 2(a) to (d). do. That is, in FIG. 2(a), the phase of the circular vibration is adjusted so that the left end of the drive section 32 comes into contact with the rail 34 during expansion and contraction of the longitudinal vibration. Next, as the shape of the composite vibrator 11 changes as shown in FIGS. 2(a), (b), and (c) over time, the drive unit 3
The right end of 2 touches the rail 34. When the driver 32 and the rail 34 come into contact with each other, they receive a driving force due to the frictional force between them and generate thrust in a predetermined direction.

The directions always point in the same direction, as indicated by arrows A and B in the figure. The speed of the composite vibrator 11 is
adjustable by the voltage and phase of the input signal;
Further, the driving direction can be arbitrarily changed depending on the phase.

Next, a specific example of the configuration of the linear ultrasonic motor 30 will be described with reference to FIGS. 4 and 5.

FIG. 4 is a top view and a side view of the linear ultrasonic motor 30, and FIG. 5 is a sectional view taken along line cc' in FIG. 4.

In the figure, the ultrasonic transducer 11 has support members 40 formed at its nodes. The support member 40 is supported by a groove 42 provided in a yoke 41 so as to have a degree of freedom in the vertical direction. The yoke is movably mounted on the base 44 by two linear bearings 43a and 43b, and is movable in the direction of arrow A in FIG.

On the other hand, a plate spring 50.
A crimping mechanism is formed by a spring presser 51, a spring guide 52, and a holder 53.

These are the spring guides 52 supported by the holder 53.
By rotating the spring presser 51 along the screw groove formed in the plate spring 50, the height of the leaf spring 50 is adjusted and the pressing force is controlled.

Further, the rail 34 is installed on the base 44 so as to come into contact with the driver 32 of the ultrasonic transducer 11.

With the above configuration, the ultrasonic motor 30 has no structural limitations on the rail 34 on the stator side, and can create a trajectory of any curvature simply by providing a simple support mechanism. Can be configured. In addition, when the ultrasonic motor is not driven, it is held by frictional force, and the force is usually two to five times larger than that of the ultrasonic motor.
A slope having an arbitrary angle of 0 to 90 degrees can also be constructed.

Here, the configuration of the control device provided in the ultrasonic motor 30 will be explained below with reference to FIG. 6.

A first conductive sliding member 60 made of a conductive material is attached to one side of the drive section 32 of the ultrasonic transducer 11. Further, a second conductive sliding member 61 is also provided on the upper surface of the rail 34.
has been installed. A DC power source 62 is electrically connected in series to the first and second conductive sliding members 60, 61, and a voltmeter 63 is connected to the power source 62. Here, these first and second conductive sliding members 601
As the material of 61, a highly conductive oxide ceramic may be used to improve wear resistance. Specifically, for example, (1) 5n02. which is an oxide semiconductor. TiO2, GeO
2, Cu2Og20 (2) Re03 which is a metallic oxide (3) NTC, PTC, C whose resistance value is temperature dependent
Examples include TRV2O3 and Ti2O3.

The voltmeter 63 is configured to send voltage information to a control circuit 64, and the control circuit 64 controls the amplifier 28a.
The gain is configured to be adjusted arbitrarily.

As described in detail above, the driver element 32, which is a sliding part of the ultrasonic motor, moves in a substantially elliptical manner, and its movement trajectory shows, for example, the trajectory shown by the arrow in FIG. If a material with small slippage on the sliding surface is used, the condition for the maximum output thrust of the ultrasonic motor is considered to be the trajectory shown by arrow E in the figure, where the trajectory of the elliptical motion is nearly halved. It will be done.

That is, on the sliding surface of the ultrasonic motor, the kinetic energy of the ultrasonic vibrator 11 is stored as strain energy at the sliding portion, and all of this acts to accelerate the movable element. Therefore, if contact/non-contact of sliding parts can be detected and the elliptical trajectory can be controlled into a desired shape, a high-output, high-efficiency ultrasonic motor can be obtained.

The control method will be explained below.

A first conductive sliding member 60 is attached to a sliding portion of the driving section 32 of the elastic body 21 that performs high-frequency vibration, and the elastic body 2
A second conductive sliding member 61 is attached to a sliding portion of the rail 34, which is a second elastic body crimped onto the second elastic member 1. Therefore, as the elastic body 21 vibrates ultrasonically, the first and second conductive sliding members 60 and 61 repeat contact and non-contact. As a result, the voltage value of the DC power supply 62 is detected by the voltmeter 63 electrically connected to the two conductive sliding members 60 and 61, both in contact and in the non-contact manner.

Therefore, the contact time and non-contact time of the deformed elliptical orbit can be determined. The conduction/cutoff information of the voltage is sent to the control circuit 64, which detects the behavior of the sliding surface and applies bending vibration to the ultrasonic vibrator 11 so that the contact time and non-contact time are approximately equal. By controlling the amplitude of the voltage applied to the first piezoelectric body 22 to be excited, it is possible to make the elliptical vibration locus a desired locus, that is, the arrow E in FIG. 7. As a result, a high-output, high-efficiency ultrasonic motor can be realized.

Alternatively, if a piezoelectric element is separately attached to the sliding portion of the elastic body 21 or rail 34 that performs high-frequency vibration, the piezoelectric element changes as the pressure force on the sliding surface changes due to the ultrasonic vibration of the elastic body 21. Output voltage changes.

As a result, it is possible to detect not only contact/non-contact of the sliding surfaces but also changes in the pressing force.

The relationship between the elliptical vibration locus and the applied voltage amplitude as described above is
This can be clearly seen by using a prismatic composite resonator with a very simple structure. That is, the prismatic composite resonator 1
1 is considered to be very suitable for such control. vice versa,
In a Langevin type vibrator that combines multiple elastic bodies or uses a bolted structure, it is thought that changes in output and speed are unlikely to occur due to conditions other than phase due to the complexity of the structure.

Although the present embodiment has been described using a prismatic composite resonator as an example, the present invention is not limited thereto, and similar effects can be obtained by using a substantially flat plate-shaped resonator.

Further, in this embodiment, a piezoelectric material is used as an excitation source for the elastic material, but its shape is limited to a flat plate, and various shapes such as a disk shape and a laminated shape are possible.

Further, in this embodiment, the crimping mechanism has been described using a leaf spring as an example, but the present invention is not limited to this, and various springs such as coil springs, application of magnetic force, etc. can be considered.

In addition, various modifications can be made without departing from the spirit of the present invention.

[Effects of the Invention] As is clear from the detailed description above, according to the present invention, by providing a vibration state detection means in the sliding portion of the ultrasonic motor, the behavior of the sliding portion during driving can be monitored. By knowing this, the ultrasonic motor can be driven with optimal friction conditions. As a result, an ultrasonic motor capable of highly efficient operation and low wear can be obtained.

[Brief explanation of drawings]

1 to 7 show embodiments embodying the present invention. FIG. 1 is an explanatory diagram of an ultrasonic transducer used in this embodiment, and FIG. 2 is an explanatory diagram of an ultrasonic transducer used in this embodiment. FIG. 3 is a diagram showing the voltage waveform of a human power signal applied to the piezoelectric body of the ultrasonic vibrator, and FIG. 4 is a diagram showing the operation of the ultrasonic motor of the present invention. FIG. 5 is a diagram showing a top view and a side view of the sonic motor; FIG. 5 is a diagram showing a CC section in FIG. 4; FIG. 6 is a diagram illustrating a control device for the ultrasonic motor. FIG. 7 is a diagram illustrating the elliptical motion locus characteristics on the sliding surface of the ultrasonic motor. FIG. 8 is a diagram showing a conventional example of an ultrasonic motor. 1 4 0 1 63 and 64 2 23a and 23b First elastic body Second elastic body First conductive sliding member Second conductive sliding member Contact detection means First piezoelectric body Second piezoelectric body

Claims (1)

[Scope of Claims] 1. A first elastic body that performs ultrasonic vibration, and a second elastic body that is crimped to the first elastic body, and the ultrasonic vibration of the first elastic body causes the first elastic body to vibrate. In an ultrasonic motor configured to cause a relative movement between the first elastic body and the second elastic body, the sliding portions of the first elastic body and the second elastic body are made of a conductive material. An ultrasonic motor comprising: a second conductive sliding member; and a contact detection means for detecting an electrical contact state between the first and second conductive sliding members. 2. A first elastic body that performs ultrasonic vibration, and a second elastic body crimped to the first elastic body, and the first elastic body and the second elastic body are separated by the ultrasonic vibration of the first elastic body. In an ultrasonic motor configured to cause relative movement between the first elastic body and the second elastic body, at least one of the sliding parts of the first elastic body and the second elastic body is formed of a piezoelectric element, and an output signal of the piezoelectric element is transmitted to the ultrasonic motor. An ultrasonic motor characterized by being equipped with a detection means for detection. 3. The ultrasonic motor according to claim 1 or 2, wherein the ultrasonic motor is configured to change the vibration locus of the first elastic body in accordance with the signal from the detection means.