JP2008109821A - Ultrasonic motor and electronic apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve output torque of an ultrasonic motor which has a simple structure and facilitates size reduction, to stabilize performance, and to reduce dispersions in the characteristics of individual products. <P>SOLUTION: The ultrasonic motor includes a wire having a coil-type stator at its one end, a vibration generator provided at the other end of the wire, and a moving body having an inside diameter that is smaller than the outside diameter of the stator, wherein the stator has a structure in which it is fitted to the smaller inside diameter portion of the moving body, in an elastically deformed state so that it becomes smaller in the radial direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic motor using an ultrasonic vibration of an elastic body as a drive source, and more particularly to an ultrasonic motor that can be mounted on a small electronic device such as a catheter.

  Ultrasonic motors that use ultrasonic vibrations of elastic bodies as a drive source take advantage of various excellent features that electromagnetic motors do not have. In addition to electronic devices such as camera autofocus mechanism drive sources, electromagnetic fields Adoption is progressing in various fields such as medical devices exposed to the environment. In addition, research and development of new types of ultrasonic motors are actively conducted because they are easy to downsize and have a high degree of freedom in shape.

Among these new types of ultrasonic motors, an ultrasonic motor that transmits ultrasonic vibrations to a coiled stator through an acoustic wave guide and drives a moving body arranged close to the stator (Patent Document 1) Since the diameter can be reduced and energy can be supplied from a distant place, it is expected to be applied to a catheter that can be inserted into a very thin portion such as a blood vessel in a human body.
WO2005 / 114824 Publication

  However, the type of ultrasonic motor that transmits ultrasonic vibrations to the coiled stator through the acoustic waveguide and drives the moving body arranged close to the stator moves only because the moving body is arranged close to the stator. The frictional force between the body and the stator is small, and the torque obtained is small. Further, the position of the contact point between the moving body and the stator fluctuates during the rotation of the moving body, resulting in fluctuations in the rotational speed and output torque. Further, even if the stator is slightly deformed, the moving body comes into contact only with a specific position of the stator (coil), and the rotational characteristics (the number of rotations and torque) of the moving body may be reduced. This is because when only a specific position of the stator (coil) is considered, the magnitude and direction of the elliptical motion caused by the vibration change with time.

  An object of the present invention is to obtain an ultrasonic motor having a simple structure but high output and high reliability.

  Therefore, in order to solve the above problems, an ultrasonic motor of the present invention includes a wire having a coiled stator at one end, a vibration generator provided at the other end of the wire, and an inner diameter smaller than the outer diameter of the stator. And the stator is engaged with the inner diameter portion of the moving body in an elastically deformed state so as to be reduced in the radial direction.

  According to this, since the pressure contact force acts between the moving body and the stator, the output torque of the ultrasonic motor increases.

  Here, a tapered portion having a diameter larger than the diameter of the outer periphery of the stator is provided at the end of the moving body. This makes it easier to incorporate the stator into the moving body.

  As another configuration of the ultrasonic motor of the present invention, a wire having a coiled stator at one end, a vibration generating device provided at the other end of the wire, and a moving body having an outer diameter larger than the inner diameter of the stator And the stator is engaged with the outer diameter portion of the movable body in a state of being elastically deformed so as to increase in diameter.

  According to this, since the pressure contact force acts between the moving body and the stator, the output torque of the ultrasonic motor increases.

  Here, a tapered portion having a diameter smaller than the diameter of the inner periphery of the stator is provided at the end of the moving body. This makes it easy to incorporate the moving body into the stator.

  The vibration generator is a vibration generator that applies longitudinal vibration from the other end of the wire toward the stator. According to this, since a large vibration energy can be input to the stator, the output of the ultrasonic motor is increased.

  In addition, a wire having a coiled stator at one end, a vibration generator provided at the other end of the wire, and a moving body in contact with the stator, the length of the stator coil per turn is in the stator. It is set equal to a multiple of the wavelength of the generated vibration wave. And the convex part which contacts a stator is provided in a moving body. And the number of this convex part is made equal to the wave number of the vibration wave produced within the wire circumference which forms the coil of a stator.

  According to this, since the contact between the stator and the moving body is stabilized, the output of the ultrasonic motor is improved, and variations in the individual ultrasonic motors can be reduced.

  As a method for assembling these ultrasonic motors, the first step of inclining the angle between the rotation center axis of the moving body and the center axis of the coil forming the stator, and the tip of the moving body following the first step The second step of inserting the stator into the inner periphery, the third step of aligning the rotation center axis of the moving body with the central axis of the coil following the third step, and the entire stator following the third step And a fourth step of accommodating the inner peripheral portion of the movable body.

  Alternatively, the first step of disposing the moving body and the stator by tilting the angle between the rotation center axis of the moving body and the center axis of the coil forming the stator, and following the first step, the tip of the moving body is attached to the stator. The second step of inserting the inner peripheral portion, the third step of aligning the rotation center axis of the movable body and the central axis of the coil following the third step, and the third step following the third step And an assembly method of an ultrasonic motor having a fourth step of being housed therein.

  Furthermore, an assembly method of an ultrasonic motor that is engaged with the inner peripheral portion or the outer peripheral portion of the stator while rotating the moving body is adopted.

  According to these, since the stator and the moving body can be easily engaged, the ultrasonic motor can be downsized and the cost can be reduced.

  And it is set as the catheter provided with these ultrasonic motors.

  According to this, a catheter having a small influence on the human body can be realized.

  According to the present invention, an extremely small and high output ultrasonic motor can be obtained with a simple structure, and the performance variation of each ultrasonic motor can be reduced. In addition, the performance stability of the ultrasonic motor can be improved in various usage environments. As a result, application to electronic devices that are extremely small and require high reliability becomes possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The structure and driving principle of the ultrasonic motor 100 according to the first embodiment of the present invention will be described with reference to FIGS. The ultrasonic motor 100 of the present invention is arranged on the outer periphery of the wire 1 having a coil-shaped stator 1a at one end, the vibration generator 6 serving as a vibration source provided at the other end of the wire 1, and the stator 1a. A substantially cylindrical moving body 2, a guide member 4 for guiding the rotation of the moving body 2, a movement restricting member 5 provided at an end of the guide member 4, and an output member 3 for taking out the rotational output of the moving body 2 , Is composed of.

  When a vibration wave is input from the vibration generator 6 to the wire 1, the vibration wave is transmitted to the coil-shaped stator 1a. The surface of the stator 1a is elliptically moved by the transmission of the vibration wave. Since the direction of the elliptical motion is opposite to the traveling direction of the vibration wave, the moving body 2 rotates in this direction. Projections 2 a are provided on the outer periphery of the moving body 2 over the entire circumference in the circumferential direction, and are guided to be rotatable on the inner periphery of the guide member 4. The output member 3 is fixed to the tip of the moving body 2 and rotates integrally with the moving body 2. The moving body 2 is moved in the direction of the rotation center axis by a restricting portion 4 a provided at one end of the guide member 4 and a convex portion 5 a of the movement restricting member 5 fixed to the other end of the guide member 4.

  If the elliptical motion can be generated on the surface of the stator 1a, the form of the vibration generator 6 is not limited. However, longitudinal vibration excited by a Langevin type vibrator capable of outputting a large output is used. Is good.

  FIG. 1B is a diagram showing an arrangement method when the Langevin type vibrator 300 is used as the vibration generator 6. The wire 1 is fixed to the tip of the Langevin type vibrator 300 (horn 20a) by welding or the like, and the longitudinal vibration is transmitted in the longitudinal direction of the wire 1, that is, the direction of the stator 1a. The Langevin type vibrator 300 includes cylindrical blocks 20b and 20c constituting a vibrating body 20 made of metal such as duralumin arranged with two disk-type piezoelectric elements 21 and 22 interposed therebetween, and bolts or welds (not shown) on the cylindrical block 20b. The horn 20a is fixed by, for example. The horn 20a has a thin tip (joined portion with the wire 1) and plays a role of expanding vibration. The piezoelectric elements 21 and 22 are disposed between the cylindrical blocks 20b and 20c, and are fixed in a state where a compressive force is applied by fastening the cylindrical blocks 20b and 20c with bolts (not shown). Electrodes (not shown) are provided on the entire surface of the piezoelectric elements 21 and 22, and are electrically connected to the outside by lead wires 23, 24 and 25. The piezoelectric elements 21 and 22 are polarized in the thickness direction, and are arranged so that the polarization directions are opposite to each other. When the lead wire 23 is grounded and an AC signal having a resonance frequency of the Langevin vibrator 300 is applied to the lead wires 24 and 25, longitudinal vibration is excited in the vibrating body 20. When the longitudinal vibration propagating through the wire 1 is incident on the stator 1a, a bending vibration wave is caused by the presence of a curve of the wire constituting the stator 1a (coil), and this causes an elliptical motion. By transmitting the longitudinal vibration to the wire 1 in this way, when the wire 1 comes into contact with another member, the vibration is difficult to attenuate and even if the wire becomes long, the vibration wave can be efficiently transmitted from the vibration generator 6 to the stator 1a. . Incidentally, when bending vibration is applied to the wire-1, if the wire comes into contact with another member, the vibration is easily attenuated.

  By the way, a pressure contact force acts between the stator 1a and the moving body 2, and thereby a large frictional force is obtained between them, and this mechanism will be described. FIG. 2 is a view showing the movable body 2 and the stator 1a before assembly. The diameter D1 of the inner diameter portion 2d of the moving body 2 is smaller than the outer shape D3 of the stator 1a. However, when the stator 1a is elastically deformed so as to be reduced in the radial direction and is accommodated in the inner diameter portion 2d of the movable body 2, the stator 2 tends to expand in the radial direction. As a result, a pressure contact force acts between the stator 1 a and the moving body 2. Further, as a device for facilitating accommodation of the stator 1a in the inner diameter portion 2d of the moving body 2, a taper portion having a diameter (D2) larger than the outer shape D3 of the stator 1a is provided at the end of the stator 2. By inserting the stator 1a from the tapered portion 2b, the diameter of the stator 1a is reduced and fits in the inner diameter portion 2d of the movable body 2.

  By adopting such a structure, the stator 1a and the moving body 2 are pressed against each other without a pressure member, so that a large frictional force acts between them, and the output torque of the ultrasonic motor 100 increases. . Further, since the movable body 2 and the stator 1a are always in pressure contact, the rotational characteristics of the ultrasonic motor 100 are stabilized. Furthermore, the frictional force between the moving body 2 and the stator 1a is ensured and driven stably even in an environment exposed to liquid, such as underwater.

(Embodiment 2)
A second example of the ultrasonic motor of the present invention will be described with reference to FIGS. Here, the description will focus on the differences from the ultrasonic motor 100 shown in the first embodiment. Therefore, the difference between the ultrasonic motor 100 will be described focusing on the stator and the moving body which are the main elements constituting the ultrasonic motor.

  In the ultrasonic motor 100, the stator 1a is disposed on the inner diameter portion 2d of the moving body 2. However, in the ultrasonic motor of the second embodiment, the stator 7a is disposed around the outer peripheral portion 8b of the moving body 8. . Similarly to the ultrasonic motor 100, the ultrasonic motor according to the second embodiment has a structure in which a pressure contact force acts between the stator 7a and the moving body 8, thereby obtaining a large frictional force therebetween. This mechanism will be explained. FIG. 4 shows the movable body 8 and the stator 7a before assembly. The diameter D5 of the outer diameter portion 8b of the moving body 8 is larger than the outer shape D6 of the stator 7a. The movable body 8 is inserted into the inner diameter portion of the stator 7a in a state where the stator 7a is elastically deformed so as to have a larger diameter. Since the stator 7a tends to shrink in the radial direction, a pressing force acts between the stator 7a and the moving body 8. At this time, as a device for facilitating accommodation of the movable body 8 in the inner diameter portion of the stator 7a, a tapered portion 8a having a smaller diameter (D4) than the outer shape D6 of the stator 7a is provided at the end of the movable body 8. By inserting the stator 7a from the tapered portion 8a, the diameter of the stator 7a is expanded and fits in the inner diameter portion of the stator 7a.

  Next, an improved example of the moving body 8 (moving body 9) will be described with reference to FIG. FIG. 5A is a view of the relationship between the moving body 9 and the stator 10 in a stopped state as seen from the radial cross section of the moving body 9, and FIG. 5B is a contact between the moving body 9 and the stator 10 during driving. It is the figure which looked at the state from the radial direction cross section of the moving body. Convex portions 9 a are provided at three locations at equal intervals in the circumferential direction of the moving body 9. The circumferential length of each convex portion 9a is set shorter than the circumferential interval between adjacent convex portions 9a (the portion not in contact with the stator 10). In addition, the number of convex portions 9 a provided on the moving body 9 is set to be equal to the wave number of vibration waves generated in one circumference of the wire forming the coil of the stator 10. The magnitude and direction of the elliptical motion generated on the surface of the stator 10 due to the vibration wave differs depending on the circumferential position of the stator, but the structure of such a moving body 9 has the largest amplitude and the direction of displacement is the same in the same place. Only the movable body 9 and the stator 10 can be brought into contact with each other. Accordingly, the rotational output of the ultrasonic motor is improved, and the rotational speed and output torque are stabilized.

  In particular, by making the length of one round of the coil of the stator 10 equal to a multiple of the wavelength of the vibration wave generated in the stator 10, the convex portion of the moving body 9 is positioned in the rotational axis direction at the circumferential position of the moving body 9. Therefore, the moving body 9 can be easily processed and downsized.

  However, when the length of one round of the coil of the stator 10 cannot be made equal to a multiple of the wavelength of the vibration wave generated in the stator 10 as described above, the circumferential position of the convex portion 9a is set to the rotation of the moving body 9. A similar contact state can be obtained between the moving body 9 and the stator 10 by changing according to the central axis direction (providing the convex portion 9a in a spiral shape).

  By the way, in FIG. 5, the type in which the moving body 9 is housed in the inner peripheral portion of the stator 10 has been described. However, in the case of an ultrasonic motor of the type in which the stator is housed in the inner peripheral portion of the moving body, the inner diameter portion of the moving body. A convex portion may be provided on the surface.

(Embodiment 3)
Next, a method for assembling the ultrasonic motor of the present invention will be described with reference to FIGS. First, a method for assembling an ultrasonic motor of the type in which the stator 1a is disposed on the inner diameter portion 11a of the moving body 11 will be described. In the first step (FIG. 6 (a)), the movable body 11 and the stator 1a are arranged by tilting the angle between the rotation center axis L1 of the movable body 11 and the central axis L2 of the coil forming the stator 1a. Then, following the first step, in the second step (FIG. 6B), the tip of the stator 1a is inserted into the tip of the inner peripheral portion 11a of the movable body 11. In the third step (FIG. 6C), the rotation center axis L1 of the movable body 11 and the center axis L2 of the stator 1a are aligned so that the entire tip of the stator 1a is accommodated in the inner peripheral portion 11a of the movable body 11. . Following the third step, in the fourth step (FIG. 6D), the stator 1a is pushed in the direction of the arrow P so that the entire stator 1a is accommodated in the inner peripheral portion 11a of the movable body 11. At this time, the stator 1 a smoothly enters the inner diameter portion 11 a of the moving body 11 by pushing the stator 1 a while rotating it in the direction of the arrow R. The ratio of the speed in the direction of arrow P that moves the stator 1a to the speed in the direction of arrow R is preferably matched to the shape of the coil forming the stator 1a (wire trajectory).

  FIG. 7 is a view showing a method of assembling an ultrasonic motor of the type in which the stator 7a is arranged around (outside) the moving body 12. FIG. In the first step (FIG. 7A), the movable body 12 and the stator 7a are arranged with the angle between the rotation center axis L4 of the movable body 12 and the central axis L3 of the coil forming the stator 7a inclined. Then, following the first step, in the second step (FIG. 7B), the tip of the stator 12 is inserted into the tip of the inner peripheral portion 7 of the stator 7a. In the third step (FIG. 7 (c)), the rotation center axis L4 of the moving body 12 is aligned with the stator 7a center axis L3, so that the entire tip of the moving body 12 is accommodated in the inner peripheral portion of the stator 7a. Subsequent to the third step, in the fourth step (FIG. 7D), the moving body 12 is pushed in the direction of the arrow P so that the entire moving body 12 is accommodated in the inner peripheral portion of the stator 7a. At this time, the moving body 12 is smoothly entered by being pushed into the stator 7a while being rotated in the direction of the arrow R.

(Embodiment 4)
Next, an ultrasonic endoscope 200 will be described with reference to FIG. 8 as a representative of a catheter that is an electronic apparatus using the ultrasonic motor of the present invention. FIG. 8 is a view showing a cross section of the catheter. The catheter 200 fixes the stator 1a, the movable body 11 disposed on the outer periphery thereof, the guide member 18 for guiding the rotation of the movable body 11, the vibrator disposed on the inside of the guide member 18 and the stator 1a, A movement regulating member 19 that regulates the movement of the moving body 11 in the rotation axis direction, a lead wire 15 for inputting an electric signal from the outside to the vibrator 14 and obtaining an electric signal output from the vibrator 14, a moving body 11 comprises a reflecting mirror 16 fixed to the tip of 11 and a cover 17 covering the whole of these components.

  When an ultrasonic wave is radiated from the vibrator 14 composed of a piezoelectric element (arrow R1), it is reflected by the reflecting mirror 16, is radiated in the direction of the arrow R2, and strikes the inner wall of the blood vessel. Furthermore, the ultrasonic wave (R3) reflected by the inner wall is incident on the mirror again, reflected, and then incident on the vibrator 14 (R4). This operation is performed while rotating the reflecting mirror 16 fixed to the moving body 11, and by analyzing the output signal of the vibrator 14, information on the entire circumference of the blood vessel inner wall can be obtained. Although the case 17 is filled with a liquid close to the acoustic impedance in the blood vessel, the ultrasonic motor of the present invention operates stably even in such an environment.

  Further, the ultrasonic motor of the present invention employs a method in which ultrasonic vibration is transmitted through a wire, not energy supplied to the stator by power supply through a lead wire. Therefore, if the vibration source is provided outside the body, there is no influence on the body due to the temperature rise due to electric power, and there is no need to worry about current flowing through the body.

  The ultrasonic motor of the present invention supplies energy to the stator by inputting ultrasonic vibration itself instead of electric power, and can supply energy from a distant place, so that it is inserted into a blood vessel or the like of a human body. Applicable to catheters and the like. Further, since the structure is simple and the size can be easily reduced, the invention can be applied to a drive source of other small electronic devices.

It is a figure which shows the structure of the ultrasonic motor of Embodiment 1 of this invention. It is a figure which shows the relationship between the moving body and stator in the ultrasonic motor of Embodiment 1 of this invention. It is a figure which shows the structure of the ultrasonic motor of Embodiment 2 of this invention. It is a figure which shows the relationship between the mobile body and stator in the ultrasonic motor of Embodiment 2 of this invention. It is a figure which shows the structure of the moving body of Embodiment 2 of this invention. It is a figure which shows the assembly method of the ultrasonic motor of Embodiment 3 of this invention. It is a figure which shows another assembly method of the ultrasonic motor of Embodiment 3 of this invention. FIG. 6 is a diagram showing a structure of a catheter using an ultrasonic motor according to a fourth embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wire 1a, 10 Stator 2, 8, 9, 11 Moving body 6 Vibration generator 4, 18 Guide member 5, 19 Movement control member

Claims (12)

A wire with a coiled stator at one end;
A vibration generator provided at the other end of the wire;
A moving body having an inner diameter smaller than the outer diameter of the stator;
The ultrasonic motor is characterized in that the stator is engaged with an inner diameter portion of the movable body in a state of being elastically deformed so as to decrease in the radial direction. A wire with a coiled stator at one end;
A vibration generator provided at the other end of the wire;
A moving body having an outer diameter larger than the inner diameter of the stator;
The ultrasonic motor is characterized in that the stator is elastically deformed so as to increase in diameter and is engaged with an outer diameter portion of the movable body.   2. The ultrasonic motor according to claim 1, wherein a tapered portion having a diameter larger than an outer peripheral diameter of the stator is provided at an end portion of the moving body.   3. The ultrasonic motor according to claim 2, wherein a taper portion having a diameter smaller than an inner peripheral diameter of the stator is provided at an end portion of the moving body.   3. The super generator according to claim 1, wherein the vibration generator is a vibration generator that applies longitudinal vibration from the other end of the wire toward the stator from the other end of the wire. 4. Sonic motor. A wire with a coiled stator at one end;
A vibration generator provided at the other end of the wire;
A moving body in contact with the stator;
The ultrasonic motor according to any one of claims 1 to 5, wherein a length of one round of the coil of the stator is equal to a multiple of a wavelength of a vibration wave generated in the stator.   The ultrasonic motor according to claim 1, wherein the moving body has a convex portion that comes into contact with the stator.   The ultrasonic motor according to claim 7, wherein the number of convex portions equal to the wave number of vibration waves generated in one circumference of the wire forming the coil of the stator is provided. A first step of inclining an angle between a rotation center axis of the movable body and a central axis of a coil forming the stator; and the stator is inserted into the inner peripheral portion of the distal end of the movable body following the first step. Following the second step, following the third step, a third step of aligning the rotation center axis of the movable body with the central axis of the coil, and following the third step, moving the entire stator A fourth step to fit in the inner circumference of the body;
The method for assembling an ultrasonic motor according to claim 1. A first step of arranging the moving body and the stator by tilting an angle between a rotation center axis of the moving body and a center axis of a coil forming the stator; and following the first step, A second step of inserting the tip into the inner periphery of the stator, a third step of aligning the rotation center axis of the movable body and the center axis of the coil following the third step, and the third step A fourth step of storing the movable body in the stator following the step of
The method for assembling an ultrasonic motor according to claim 2, wherein:   The ultrasonic motor assembling method according to any one of claims 1 to 8, wherein the moving body is engaged with an inner peripheral portion or an outer peripheral portion of the stator while rotating.   A catheter comprising the ultrasonic motor according to any one of claims 1 to 8.

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