JP2010193591A - Ultrasonic motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic motor capable of uniformly and easily pre-pressing a multilayer piezoelectric element. <P>SOLUTION: The ultrasonic motor 1 includes a bar-like elastic body 12, a pair of multilayer piezoelectric elements 18 having both ends held by the bar-like elastic body 12, disposed on a front surface 12a and a rear surface 12b while having an acute angle between the displacement direction and the longitudinal direction of the bar-like elastic body 12, and disposed on the bar-like elastic body 12 so as to be inclined in an opposite direction to each other when viewed regularly face to face in the longitudinal direction of the bar-like elastic body 12, and a friction piece 26 joined to the tip portion of the bar-like elastic body 12. In the ultrasonic motor 1, alternating voltages having different phases are applied to the pair of multilayer piezoelectric elements 18 respectively, thereby simultaneously exciting longitudinal vibration and torsional vibration to excite ultrasonic elliptic movement in the friction piece 26. The ultrasonic motor 1 includes a pre-pressing mechanism 80 for simultaneously and uniformly pre-pressing the multilayer piezoelectric elements 18 along the stacked direction thereof in order to firmly fix the multilayer piezoelectric elements 18 to the bar-like elastic body 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ultrasonic motor using a piezoelectric element as a drive source.

  In recent years, ultrasonic motors have attracted attention as new motors that replace electromagnetic motors. Ultrasonic motors use vibrations of vibrators such as piezoelectric elements. Compared to conventional electromagnetic motors, ultrasonic motors produce low rotation and high torque without gears, large holding power, high resolution, quietness, and magnetic noise. In addition, there are advantages such as not being affected by magnetic noise.

  For example, Patent Document 1 discloses an ultrasonic motor that can be configured using one type of piezoelectric element and has a simple configuration.

JP 09-121573 A

  In the ultrasonic motor disclosed in Patent Document 1, one side surface and the other side surface of the basic elastic body are opposed to each other, and laminated piezoelectric elements are respectively disposed on the one side surface and the other side surface. ing. In order to fix the laminated piezoelectric element to the basic elastic body, it is necessary to preload the laminated piezoelectric element against the basic elastic body by a holding elastic body or the like. This preload is a compressive force applied to the multilayer piezoelectric element. Further, when the holding elastic body is used, it is necessary to use another part such as an assembly jig.

  However, since the holding elastic body separately preloads the stacked piezoelectric elements on one side surface and the other side surface, there is a possibility that preloading may not be performed uniformly (preload may vary). There is a possibility of affecting the performance of the vibrator. Further, when using a holding elastic body for preloading the multilayer piezoelectric element, an assembly jig is required, and preloading cannot be performed easily, and preloading takes time.

  The present invention has been made in view of these circumstances, and an object of the present invention is to provide an ultrasonic motor capable of preloading uniformly and easily on a laminated piezoelectric element.

  In order to achieve the object, the present invention provides a rod-shaped elastic body and the rod-shaped elastic body in a state where both ends are held by the rod-shaped elastic body and have an acute angle in an angle between a displacement direction and a longitudinal direction of the rod-shaped elastic body. A pair of stacked piezoelectric elements disposed on the two opposing side surfaces of the body and further disposed in the rod-shaped elastic body so as to be inclined in opposite directions when viewed in the longitudinal direction of the rod-shaped elastic body; A friction element joined to the tip of the rod-shaped elastic body, and by applying alternating voltages having different phases to the pair of stacked piezoelectric elements, longitudinal vibration and torsional vibration are simultaneously excited. An ultrasonic motor for exciting the frictional element with an ultrasonic elliptical motion, in order to tightly fix the multilayer piezoelectric element to the rod-like elastic body, the multilayer piezoelectric element is stacked in the stacking direction of the multilayer piezoelectric element along To provide an ultrasonic motor, characterized by comprising a preload mechanism at and evenly preload.

  ADVANTAGE OF THE INVENTION According to this invention, the ultrasonic motor which can preload uniformly and easily to a lamination type piezoelectric element can be provided.

FIG. 1 is a top view of an ultrasonic transducer constituting the ultrasonic motor according to the first embodiment of the present invention. FIG. 2 is a diagram (front view) of the ultrasonic transducer viewed from the α direction shown in FIG. 1. FIG. 3 is a view (back view) of the ultrasonic transducer viewed from the β direction shown in FIG. 1. 4 is a diagram (right side view) of the ultrasonic transducer viewed from the γ direction shown in FIG. 5 is a view (left side view) of the ultrasonic transducer viewed from the δ direction shown in FIG. FIG. 6 is a side view of an ultrasonic motor using an ultrasonic transducer. FIG. 7 is an exploded view of an ultrasonic motor using an ultrasonic transducer. FIG. 8 is a side view of an ultrasonic motor using the ultrasonic transducer in the second embodiment. FIG. 9 is an exploded view of an ultrasonic motor using the ultrasonic transducer according to the second embodiment. FIG. 10 is an exploded view of an ultrasonic motor using the ultrasonic transducer in the third embodiment. FIG. 11 is a side view of an ultrasonic motor using the ultrasonic transducer in the third embodiment. FIG. 12 is an exploded view of an ultrasonic motor using the ultrasonic transducer in the fourth embodiment. FIG. 13 is a side view of an ultrasonic motor using the ultrasonic transducer in the fourth embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The first embodiment will be described with reference to FIGS.
As shown in FIGS. 1 to 7, the ultrasonic motor 1 includes an ultrasonic vibrator 10 that generates ultrasonic vibrations, and a rotor 53 that is a driven member to which the vibrations of the ultrasonic vibrator 10 are transmitted and driven. A pressing mechanism 70 that applies a pressing force to the driven member (rotor 53) and the ultrasonic transducer 10, and a preload mechanism 80 that applies a preload to a laminated piezoelectric element 18 (described later) provided in the ultrasonic transducer 10. Have.

  The ultrasonic vibrator 10 includes an electromechanical transducer that is excited by applying an alternating voltage to a basic elastic body 12 that is a prismatic or cylindrical rod-shaped elastic body made of, for example, a brass material (C2801P O material) and a drive source (not shown). The laminated piezoelectric element 18 is arranged at the upper end in the longitudinal direction of the basic elastic body 12 so as to face the driven member (rotor 53). And a sliding driver 26 for transmission.

  As shown in FIG. 2, the front surface 12a of the basic elastic body 12 has a recess 16a, and as shown in FIG. 3, the back surface 12b of the basic elastic body 12 facing the front surface 12a has a recess 16b. The recesses 16a and 16b are not necessarily limited to the front surface 12a and the back surface 12b, and may be disposed on the side surfaces 12c and 12d facing the basic elastic body 12.

  The concave portion 16 a is disposed on the front surface 12 a in a state where it is inclined by a desired angle with respect to the height (longitudinal) direction of the basic elastic body 12. Similarly to the recess 16a, the recess 16b is disposed on the back surface 12b while being inclined by the same desired angle as the recess 16a with respect to the height (longitudinal) direction of the basic elastic body 12. In this case, the recesses 16a and 16b are attached in the opposite direction when viewed from the front. The inclination angle of the recesses 16a and 16b is an acute angle between the height (longitudinal) direction of the basic elastic body 12 and the longitudinal direction of the recesses 16a and 16b.

  A laminated piezoelectric element 18 and a holding elastic body 83 (described later) for holding the laminated piezoelectric element 18 are inserted into the recesses 16a and 16b, respectively. The laminated piezoelectric element 18 is a vibration main body that generates vibrations by ultrasonic waves, and is an electromechanical conversion element. The holding elastic body 83 is disposed closer to the base end portion 13a of the basic elastic body 12 than the stacked piezoelectric element 18 in the recesses 16a and 16b. Since the laminated piezoelectric element 18 and the holding elastic body 83 are inserted into the recesses 16a and 16b, they are arranged in a state where they are inclined by a desired angle similarly to the recesses 16a and 16b.

  As shown in FIGS. 4 and 5, the side surfaces of the laminated piezoelectric element 18 and the holding elastic body 83 are projected at the same position in the longitudinal direction on both the front and back surfaces. That is, the laminated piezoelectric element 18 has two front sides 12a and 12b, which are the two opposite sides of the basic elastic body 12, with an acute angle between the displacement direction and the longitudinal direction of the basic elastic body 12, respectively. Arranged. Further, these laminated piezoelectric elements 18 are disposed on the basic elastic body 12 so as to be inclined in directions opposite to each other when viewed in the longitudinal direction of the basic elastic body 12.

  The laminated piezoelectric element 18 and holding elastic body 83 arranged in the recess 16a, and the laminated piezoelectric element 18 and holding elastic body 83 arranged in the recessed section 16b sandwich the basic elastic body 12. Will be. Further, both ends of the laminated piezoelectric element 18 are held by the basic elastic body 12 (the concave portions 16a and 16b and the holding elastic body 83).

  In addition, the electrical terminals extending from the laminated piezoelectric element 18 inserted into the recess 16a are an A terminal and a GND terminal, respectively. In addition, the electrical terminals extending from the laminated piezoelectric element 18 inserted into the recess 16b are a B terminal and a GND terminal, respectively.

Next, the laminated piezoelectric element 18 will be described in detail.
The laminated piezoelectric element 18 is formed by laminating a plurality of plate-like piezoelectric elements 18f, and sandwiching the laminated piezoelectric elements 18f between two insulating plates (not shown). It is inclined and arranged. Such lamination may be performed using an adhesive or by an integral firing method.

  The piezoelectric element 18 f is a piezoelectric element for driving the ultrasonic transducer 10. The piezoelectric element 18f has a thickness of, for example, 100 μm and is, for example, a lead zirconate titanate piezoelectric ceramic element (PZT). A part of the piezoelectric element 18f may be used for vibration detection, for example.

  An internal electrode (not shown) having either a + electrode or a − electrode is formed on the front surface and the back surface of the piezoelectric element 18f. As described above, when the piezoelectric elements 18f are stacked, the piezoelectric elements 18f having the positive electrode internal electrode and the piezoelectric elements 18f having the negative electrode internal electrode are alternately stacked.

  The internal electrode has a thickness of 4 μm, for example, and is, for example, a silver palladium alloy. The area of the internal electrode is preferably as close as possible to the area of the piezoelectric element 18f.

  In addition, the connection in the case of lamination | stacking of internal electrodes is performed by the external electrode which each short-circuited. Then, a high voltage is applied between the internal electrode of the positive electrode and the internal electrode of the negative electrode to polarize the piezoelectric element 18f and activate it piezoelectrically.

  The configuration of the laminated piezoelectric element 18 need not be limited to the above.

  The tip end portion 13b of the basic elastic body 12 that is the upper end portion of the ultrasonic vibrator 10 is a sliding drive made of, for example, a friction element made of a grindstone in which alumina ceramic abrasive grains are dispersed in an annular phenol resin or a composite resin. The child 26 is joined.

  The ultrasonic motor 1 applies alternating voltages having different phases to the pair of laminated piezoelectric elements 18 to simultaneously excite longitudinal vibration and torsional vibration, and excites the ultrasonic elliptical motion to the sliding driver 26. .

  A through hole 30 is formed on the central axis of the basic elastic body 12. A female screw 32 is threaded at the node position of the longitudinal vibration of the ultrasonic transducer 10 on the central axis of the through hole 30 (see FIG. 7).

  A shaft 51 in a first elastic body 81 to be described later is fitted into the through hole 30. As shown in FIG. 2, the shaft 51 has a length protruding from the distal end portion 13 b of the ultrasonic transducer 10.

The shaft 51 is threaded with a male screw 58 and a male screw 59.
The male screw 58 is arranged on the shaft 51 so as to correspond to the arrangement position of the female screw 32 (node position of longitudinal vibration of the ultrasonic transducer 10). The male screw 58 is screwed into the female screw 32 and then fixed by adhesion. As a result, the shaft 51 is bonded and fixed at the longitudinal vibration node of the basic elastic body 12.
The male screw 59 is disposed at the distal end portion of the shaft 51 protruding from the distal end portion 13b. The male screw 59 is disposed on the shaft 51 so as to correspond to the position where the nut 57 is disposed. A nut 57 is fitted to the male screw 59.

  An annular rotor 53 that is driven by the sliding driver 26 is disposed on the sliding driver 26 that is the upper end of the ultrasonic transducer 10. Specifically, a sliding material 53 a made of, for example, an annular ceramic is attached to the lower surface of the rotor 53 facing the sliding driver 26. The cross-sectional shape of the rotor 53 and the cross-sectional shape of the sliding member 53a are the same, and the rotor 53 is driven by being brought into contact with the sliding driver 26 via the sliding member 53a.

  A radial bearing 54 is disposed inside the rotor 53. A spring holder 55 is disposed on the rotor 53. The spring holder 55 positions and holds the coil spring 56.

  A shaft 51 is inserted through the rotor 53, the sliding member 53 a, the radial bearing 54, and the spring holder 55.

  The rotor 53 is pressed and fixed by a coil spring 56 so as to be rotatable toward the sliding drive element 26 via a spring holder 55 and a radial bearing 54. More specifically, the sliding member 53 a is pressed and fixed to the sliding driver 26.

  The coil spring 56 is held by a spring holder 55 and is prevented from coming off from the spring holder 55 (shaft 51) by a nut 57. The nut 57 adjusts the pressing force of the coil spring 56.

  That is, the coil spring 56 surrounds the shaft 51 in a spiral shape, is held by the spring holding body 55, and is disposed so as not to be detached from the shaft 51 by the nut 57. The pressing force of the coil spring 56 is adjusted by the nut 57. The coil spring 56 presses the rotor 53 against the sliding driver 26 via the spring holder 55 and the radial bearing 54 by the pressing force of the coil spring 56.

  Thus, the nut 57, the coil spring 56, the spring holder 55, and the radial bearing 54 are a pressing mechanism 70 that presses the rotor 53 against the sliding driver 26.

  On the base end portion 13a (the lower surface 12g) of the basic elastic body 12, a convex portion 15 that is convex in the longitudinal direction is disposed. The convex portion 15 is fitted into an opening 82a provided in a second elastic body 82 described later. A through hole 15 a that communicates with the through hole 30 is disposed in the convex portion 15.

  Further, the ultrasonic motor 1 presses the holding elastic body 83 along the longitudinal direction of the basic elastic body 12 in order to closely fix the laminated piezoelectric element 18 to the basic elastic body 12 in the ultrasonic vibrator 10. A preload mechanism 80 for preloading the stacked piezoelectric element 18 along the stacking direction of the stacked piezoelectric element 18 is provided. This preload mechanism 80 simultaneously and equally (with equality) causes the laminated piezoelectric element 18 on the front surface 12a side to be inserted into the recess 16a and the laminated piezoelectric element 18 on the back surface 12b side to be inserted into the recessed part 16b. Preload. This preload is to press the holding elastic body 83 and apply a pressure higher than the atmospheric pressure to the laminated piezoelectric element 18 in order to firmly fix the laminated piezoelectric element 18 to the basic elastic body 12 without a gap. The compression force applied to the laminated piezoelectric element 18 is shown.

  The preload mechanism 80 preloads the multilayer piezoelectric element 18, and the multilayer piezoelectric element 18 is fixed to the basic elastic body 12, so that the vibration of the multilayer piezoelectric element 18 is transmitted to the basic elastic body 12.

  The preload mechanism 80 is disposed on the base end portion 13a (lower surface 12g) side of the basic elastic body 12, and in the longitudinal direction of the basic elastic body 12, the pressing mechanism 70, the sliding driver 26, It is arranged on the opposite side to the rotor 53.

  The preload mechanism 80 includes a first elastic body 81 that presses the basic elastic body 12 from the base end portion 13a (lower surface 12g) side of the basic elastic body 12, and a base end portion of the first elastic body 81 and the basic elastic body 12. 13a, a second elastic body 82 that transmits the pressing force of the first elastic body 81 to the base end portion 13a of the basic elastic body 12, and the laminated piezoelectric element 18 as the basic elastic body 12. In order to tightly fix the laminated piezoelectric element 18 by the pressing force transmitted from the first elastic body 81 via the second elastic body 82, the laminated piezoelectric element 18 is simultaneously and uniformly preloaded toward the basic elastic body 12. It has a holding elastic body 83 for holding the multi-layer piezoelectric element 18 so that the multi-layer piezoelectric element 18 is firmly fixed to the basic elastic body 12 by preloading.

  The first elastic body 81 can be screwed into the through hole 30 as a central axis of the ultrasonic motor 1, and has a shaft 51 inserted through the through hole 30. The first elastic body 81 is fixed to the basic elastic body 12 by screwing.

  As shown in FIG. 2, the shaft 51 has a length protruding from the distal end portion 13 b of the basic elastic body 12. The protruding length is a length in which the sliding driver 26, the rotor 53, and the pressing mechanism 70 are disposed as shown in FIG. Thus, the shaft 51 is also a support shaft that supports the sliding driver 26, the rotor 53, and the pressing mechanism 70. The shaft 51 has the male screws 58 and 59 as described above. Further, when the shaft 51 is inserted into the through hole 30, the first elastic body 81 press-fits the second elastic body 82 into the through hole 15a (basic elastic body 12), and the second elastic body 82 is moved to the first elastic body 81. It is sandwiched between the elastic body 81 and the basic elastic body 12. The first elastic body 81 fixes the second elastic body 82 to the basic elastic body 12 by this press-fitting.

  The second elastic body 82 includes an opening 82 a into which the convex portion 15 is fitted, and a pair of pressing portions 82 b that press the holding elastic body 83 by the first elastic body 81.

  The second elastic body 82 transmits the force generated when the first elastic body 81 is screwed to the basic elastic body 12 to the holding elastic body 83.

  The opening 82 a penetrates along the longitudinal direction of the second elastic body 82. Therefore, when the convex portion 15 is fitted into the opening 82a and the shaft 51 is inserted through the through holes 15a and 30, the basic elastic body 12, the first elastic body 81, and the second elastic body 82 are integrated. At this time, the central axes of the basic elastic body 12, the first elastic body 81, and the second elastic body 82 coincide (integrate).

  The pressing portion 82 b presses the holding elastic body 83 by a fastening force by screwing the first elastic body 81 and the basic elastic body 12.

  A pair of pressing portions 82b are disposed on the second elastic body 82 so as to correspond to the holding elastic body 83 inserted into the recess 16a and the holding elastic body 83 inserted into the recess 16b. The pressing portions 82b press the holding elastic bodies 83 simultaneously and with equal force.

  The holding elastic body 83 preloads the stacked piezoelectric elements 18 simultaneously and evenly based on the pressing force in the pressing portion 82b. The holding elastic body 83 has a transmission portion 83 a that transmits the preload from the lower surface 18 b side of the multilayer piezoelectric element 18 to the multilayer piezoelectric element 18 along the stacking direction of the multilayer piezoelectric element 18 when preloading. ing. The transmission portion 83a is a mounting surface of the holding elastic body 83 on which the stacked piezoelectric element 18 is mounted (contacted). The transmission part 83a is tilted as desired so that the multilayer piezoelectric element 18 tilts as described above.

  Note that an adhesive such as an epoxy resin is applied to the lower surface 18b which is a mounting surface of the multilayer piezoelectric element 18 mounted on the transmission portion 83a. Since the laminated piezoelectric element 18 is bonded to the holding elastic body 83 with an adhesive, when the transmitting portion 83 a transmits the preload to the laminated piezoelectric element 18, the laminated piezoelectric element 18 passes through the holding elastic body 83. It is closely fixed to the basic elastic body 12. As described above, the holding elastic body 83 holds the laminated piezoelectric element 18 by the transmission portion 83a, and tightly fixes the laminated piezoelectric element 18 to the basic elastic body 12.

  The holding elastic body 83 is bonded to the basic elastic body 12 via the recesses 16a and 16b, and both ends are held by the basic elastic body 12 together with the laminated piezoelectric element 18.

  In the present embodiment, the second elastic body 82 and the holding elastic body 83 are separate bodies.

  The outer diameter of the second elastic body 82 is smaller than the outer diameter of the first elastic body 81 and the outer diameter of the basic elastic body 12. Therefore, the second elastic body 82, the first elastic body 81, and the basic elastic body 12 form a groove portion 14 having a depth of about 1 mm to about 2 mm. By changing the length dimension below the groove 14 (on the side opposite to the laminated piezoelectric element 18) and setting the relative position of the groove 14 to an appropriate (desired) position, the resonance frequency between the resonance longitudinal vibration mode and the resonance torsional vibration is obtained. Almost match.

Next, the operation method of the present invention will be described.
First, a method for manufacturing the ultrasonic transducer 10 will be described.
The laminated piezoelectric element 18 is placed on the transmission portion 83a. An adhesive is applied to the lower surface 18b. Therefore, the laminated piezoelectric element 18 is bonded to the transmission portion 83a. The holding elastic body 83 that holds the laminated piezoelectric element 18 placed on the transmission portion 83a is disposed in the recesses 16a and 16b.

  Next, the convex portion 15 is fitted into the opening 82a. At this time, the pressing portion 82 b comes into contact with the holding elastic body 83. Next, the shaft 51 is inserted through the through holes 15 a and 30. At this time, the first elastic body 81, the second elastic body 82, and the basic elastic body 12 have the same center axis. The male screw 58 is adhesively fixed after being screwed into the female screw 32. Thus, the shaft 51 is bonded and fixed to the longitudinal vibration node of the basic elastic body 12.

At this time, the male screw 58 and the female screw 32 are screwed together to press-fit the second elastic body 82 into the basic elastic body 12 and fix the second elastic body 82 to the basic elastic body 12.
At this time, the pressing portion 82b presses the holding elastic body 83.

  The pressing force is adjusted by adjusting the screwing of the first elastic body 81, and the pressing portion 82b presses the holding elastic body 83 from the base end portion 13a side of the basic elastic body 12 in accordance with this adjustment. To do.

  The pressing portions 82b press the holding elastic bodies 83, respectively. At this time, the pressing portion 82b presses the holding elastic body 83 in the recessed portion 16a and the holding elastic body 83 in the recessed portion 16b simultaneously and with the same amount of pressing force. That is, the holding elastic body 83 in the concave portion 16a and the holding elastic body 83 in the concave portion 16b are simultaneously pressed by the pressing portion 82b with an equal pressing force.

  Thereby, in the holding elastic body 83, the transmission portion 83a preloads the multilayer piezoelectric element 18 along the stacking direction of the multilayer piezoelectric element 18 from the lower surface 18b side based on this pressing force. That is, the multilayer piezoelectric element 18 is preloaded based on the pressing force through the transmission portion 83a.

  The holding elastic body 83 holds the laminated piezoelectric element 18, preloads the laminated piezoelectric element 18, and tightly fixes the laminated piezoelectric element 18 to the basic elastic body 12 without a gap. Therefore, the laminated piezoelectric element 18 is tightly fixed to the basic elastic body 12 in a preloaded state.

  The multilayer piezoelectric element 18 is disposed in each of the recesses 16a and 16b. Each laminated piezoelectric element 18 is simultaneously given the same preload by the pressing portion 82b and the transmission portion 83a. Therefore, variations in preload with respect to the stacked piezoelectric elements 18 respectively disposed in the recesses 16a and 16b can be suppressed.

  At this time, the holding elastic body 83 is bonded or screwed to the basic elastic body 12 via the recesses 16a and 16b.

Next, the operation of the ultrasonic transducer 10 will be described.
In the ultrasonic transducer 10, the primary resonance longitudinal vibration of the ultrasonic transducer 10 is excited at the same frequency Fr as the primary resonance longitudinal vibration and the primary (secondary resonance torsion below the groove 14). It can be done.
Resonant longitudinal vibration is vibration in the direction of arrow Z shown in FIG. The primary resonance torsional vibration is vibration in the direction of arrow ω shown in FIG. 1 and is vibration with the vibration direction of resonance longitudinal vibration (direction of arrow Z) as the axis of torsion. In the vicinity of this frequency, it is formed in such a shape that there is no natural vibration of resonance bending vibration.

First, when an alternating voltage with the frequency Fr and amplitude Vr is applied to the A terminal and an alternating voltage with the same frequency and amplitude and phase is applied to the B terminal, the resonance longitudinal vibration is excited. The node position of the resonant longitudinal vibration exists on the central axis of the basic elastic body 12 and at substantially the center in the longitudinal direction of the ultrasonic transducer 10.
Next, when an alternating voltage having the frequency Fr and amplitude Vr is applied to the A terminal and an alternating voltage having the same frequency and the same amplitude and opposite phase is applied to the B terminal, the resonance torsional vibration is excited. In the resonance torsional vibration, the node position is at the center in the longitudinal direction on the central axis of the basic elastic body 12.
Furthermore, when an alternating voltage with the frequency Fr and amplitude Vr is applied to the A terminal and an alternating voltage with the same frequency and the same amplitude and a phase different by 90 degrees is applied to the B terminal, the resonant longitudinal vibration and the resonant torsional vibration are combined. Ultrasonic elliptical vibration is excited at the position of the sliding driver 26.

  Next, an operation method of the ultrasonic motor 1 of the present embodiment using the ultrasonic transducer 10 will be described with reference to FIGS. 6 and 7. 6 and 7, and in the method of manufacturing the ultrasonic transducer 10 described above, the shaft 51 is inserted into the through hole 15a, and the female screw 32 and the male screw 58 provided in the through hole 30 (see FIG. 7) are provided. When screwed, the shaft 51 is adhered and fixed to the basic elastic body 12 at the longitudinal vibration node of the basic elastic body 12.

  A rotor 53 is pressed and fixed to the sliding driver 26 (upper end portion of the ultrasonic transducer 10) by a coil spring 56 via a radial bearing 54 and a spring holder 55. The pressing force of the coil spring 56 is adjusted by a nut 57. The rotor 53 abuts on the sliding driver 26 via the sliding member 53a. Thereby, the pressing mechanism 70 is formed.

As described above, an alternating voltage having a frequency Fr, an amplitude Vr, and a phase difference of +90 degrees or −90 degrees is applied to the A terminal and the B terminal of the ultrasonic transducer 10. Then, the rotor 53 rotates clockwise or counterclockwise with respect to the sliding driver 26.
As described above, in the present embodiment, the first elastic body 81 is screwed in the preload mechanism 80, so that the laminated piezoelectric element 18 is simultaneously and equally forced by the second elastic body 82 and the transmission portion 83a. Preload can be easily performed. Further, in the present embodiment, it is possible to prevent variations in preload with respect to the stacked piezoelectric elements 18 respectively disposed in the recesses 16a and 16b, and to keep the performance of the ultrasonic motor 1 high.

  Further, in the present embodiment, when the ultrasonic motor 1 is manufactured (assembled), the laminated piezoelectric element 18 can be easily preloaded only by screwing the first elastic body 81, and the preloading effort can be reduced. It can be omitted.

  In the present embodiment, even if the holding elastic body 83 is used, the ultrasonic motor 1 can be easily manufactured by simply screwing the first elastic body 81 without using a jig or the like. 1 can be made inexpensive.

  In this embodiment, the preload can be adjusted by adjusting the screwing of the first elastic body 81. In the present embodiment, the preload mechanism 80 is disposed on the opposite side of the pressing mechanism 70, the sliding driver 26, and the rotor 53 with the laminated piezoelectric element 18 sandwiched in the longitudinal direction of the basic elastic body 12. Therefore, in this embodiment, even after the ultrasonic motor 1 is manufactured, the screwing of the first elastic body 81 can be adjusted, and the preload can be adjusted.

  In the present embodiment, the force (preload) for fixing the multilayer piezoelectric element 18 to the basic elastic body 12 can be directly transmitted to the multilayer piezoelectric element 18. Therefore, in the present embodiment, it is possible to efficiently transmit the preload to the multilayer piezoelectric element 18 and improve the preload transmission efficiency.

  Further, in the present embodiment, the second elastic body 81 is press-fitted and fixed to the basic elastic body 12 by the first elastic body 81, thereby holding the pressing force of the first elastic body 81 through the second elastic body 82. It can be transmitted to the elastic body 83 without waste.

  Further, in the present embodiment, the force when the first elastic body 81 screws the second elastic body 82 to the basic elastic body 12 by fixing the second elastic body 82 to the basic elastic body 12 by press-fitting. Can be prevented from being directly transmitted to the holding elastic body 83 and the basic elastic body 12.

Next, a second embodiment will be described with reference to FIGS. About the same structure as 1st Embodiment, description is abbreviate | omitted by attaching | subjecting the same referential mark as 1st Embodiment.
In the present embodiment, the second elastic body 82 is integral (same body) with the holding elastic body 83.

  Thereby, in this embodiment, the number of parts of the ultrasonic motor 1 can be reduced, the number of assembling steps can be reduced, and the cheaper ultrasonic motor 1 can be provided. In the present embodiment, the ultrasonic motor 1 can be assembled more easily.

Next, a third embodiment will be described with reference to FIGS. About the same configuration as the first and second embodiments. The same reference numerals as those in the first and second embodiments are assigned, and the description thereof is omitted.
The basic elastic body 12 of the present embodiment has a groove portion 14 having a depth of about 1 mm to about 2 mm formed (concave) over the entire circumference, for example, on the outer circumference at a position of 11 mm from the lower end. By changing the length dimension below the groove 14 (on the side opposite to the laminated piezoelectric element 14) and setting the relative position of the groove 14 to an appropriate (desired) position, the resonance frequency between the resonance longitudinal vibration mode and the resonance torsional vibration is obtained. Almost match.

  The outer diameter D1 of the base end portion 13a of the basic elastic body 12 positioned above the groove portion 14 is smaller than the outer diameter D2 of the distal end portion 13b of the basic elastic body 12 on the sliding driver 26 side. That is, the base end portion 13 a of the basic elastic body 12 has a smaller diameter than the distal end portion 13 b of the basic elastic body 12. A thread 12 h is formed on the outer periphery of the base end portion 13 a of the basic elastic body 12.

  The preload mechanism 80 of the present embodiment is configured to fix the laminated piezoelectric element 18 to the basic elastic body 12 by screwing the holding elastic body 83 via the screw thread 12h, and thereby via the holding elastic body 83. And a pressing ring 84 for preloading the laminated piezoelectric element 18.

  The inner diameter D3 of the pressing ring 84 is larger than the outer diameter D1 of the base end portion 13a of the basic elastic body 12. The central axis of the pressing ring 84 is arranged on the same straight line as the central axis of the basic elastic body 12.

  Further, the holding elastic body 83 of the present embodiment has a ring shape. The holding elastic body 83 applies a preload simultaneously to each of the stacked piezoelectric elements 18 by the pressing ring 84 screwing the holding elastic body 83 through the thread 12h.

  In the present embodiment, the same effect as in the first embodiment can be obtained. Moreover, in this embodiment, the press ring 84 and the base end part 13a of the basic elastic body 12 are integrated. Therefore, in this embodiment, vibration can be efficiently transmitted to the rotor 53 that is the driven material via the shaft 51, vibration loss can be reduced, and vibration transmission efficiency can be improved.

  Next, a fourth embodiment will be described with reference to FIGS. About the same configuration as the first, second, and third embodiments. The same reference numerals as those in the first, second, and third embodiments are assigned, and the description thereof is omitted.

The holding elastic body 83 of the present embodiment is disposed closer to the distal end portion 13b side of the basic elastic body 12 than the stacked piezoelectric element 18 in the recesses 16a and 16b.
The holding elastic body 83 holds the laminated piezoelectric element 18 from the upper surface 18a of the laminated piezoelectric element 18. The outer diameter D2 of the distal end portion 13b of the basic elastic body 12 is the outer diameter of the proximal end portion 13a of the basic elastic body 12. It is smaller than D1. That is, the distal end portion 13 b of the basic elastic body 12 has a smaller diameter than the proximal end portion 13 a of the basic elastic body 12. In the case of the present embodiment, the outer diameter D1 of the base end portion 13a of the basic elastic body 12 is substantially the same as the outer diameter of the middle end portion of the basic elastic body 12 in which the multilayer piezoelectric element 18 is disposed. A thread 12 h is formed on the outer periphery of the tip end portion 13 b of the basic elastic body 12.

  In this case, the pressing ring 84 preloads the laminated piezoelectric element 18 via the holding elastic body 83 by screwing the tip end portion 13b of the basic elastic body 12 through the screw thread 12h. At this time, the central axis of the pressing ring 84 is arranged on the same straight line as the central axis of the basic elastic body 12.

  Thereby, in this embodiment, the assembly from the front-end | tip part 13b side of the basic elastic body 12 by which the sliding drive element 26, the rotor 53, and the press mechanism 70 are arrange | positioned is attained, and the ultrasonic motor 1 is assembled easily. Can do.

  Further, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Ultrasonic motor, 10 ... Ultrasonic vibrator, 12 ... Basic elastic body (rod-like elastic body), 12a ... Front, 12b ... Back, 12c, 12d ... Side, 13a ... Base end, 13b ... Tip, 14 ... groove, 15 ... convex, 15a ... through hole, 16a, 16b ... concave, 18 ... stacked piezoelectric element, 18a ... upper surface, 18b ... lower surface, 18f ... piezoelectric element, 26 ... sliding drive element (friction element), DESCRIPTION OF SYMBOLS 30 ... Through-hole, 32 ... Female thread, 51 ... Shaft, 53 ... Rotor, 53a ... Sliding material, 54 ... Radial bearing, 55 ... Spring holder, 56 ... Coil spring, 57 ... Nut, 58 ... Male screw, 70 ... Pressing mechanism , 80: Preload mechanism, 81: First elastic body, 82a: Opening portion, 82: Second elastic body, 82b: Pressing portion, 83: Elastic body for holding, 83a: Transmission portion.

Claims (7)

A rod-shaped elastic body;
Both ends are held by the rod-shaped elastic body, and are respectively disposed on two opposing side surfaces of the rod-shaped elastic body with an acute angle between the displacement direction and the longitudinal direction of the rod-shaped elastic body, A pair of stacked piezoelectric elements disposed in the rod-shaped elastic body so as to be inclined in opposite directions as viewed in the longitudinal direction of the rod-shaped elastic body;
A friction member joined to the tip of the rod-shaped elastic body;
Comprising
An ultrasonic motor that excites longitudinal vibration and torsional vibration simultaneously by applying alternating voltages having different phases to the pair of stacked piezoelectric elements, and excites ultrasonic elliptical motion in the friction element,
In order to tightly fix the multilayer piezoelectric element to the rod-like elastic body, a preload mechanism is provided for preloading the multilayer piezoelectric element simultaneously and uniformly along the stacking direction of the multilayer piezoelectric element. Ultrasonic motor. The preload mechanism is
A first elastic body that presses the rod-shaped elastic body from the base end side of the rod-shaped elastic body;
A second elastic body that is disposed between the first elastic body and a base end portion of the rod-shaped elastic body and transmits a pressing force of the first elastic body to the rod-shaped elastic body;
In order to fix the laminated piezoelectric element to the rod-like elastic body, the laminated piezoelectric element is attached to the basic elastic body by a pressing force transmitted from the first elastic body through the second elastic body. The holding elastic body that pre-loads simultaneously and evenly and holds the laminated piezoelectric element;
The ultrasonic motor according to claim 1, comprising:   3. The ultrasonic wave according to claim 2, wherein the holding elastic body includes a transmission unit that transmits the preload to the stacked piezoelectric element along a stacking direction of the stacked piezoelectric element when preloading. motor.   The ultrasonic motor according to claim 3, wherein the first elastic body is fixed to the rod-shaped elastic body by screwing.   The said 1st elastic body press-fits the said 2nd elastic body to the said rod-shaped elastic body, The said 2nd elastic body is fixed to the said rod-shaped elastic body by press-fit, The said elastic body of Claim 3 characterized by the above-mentioned. Ultrasonic motor.   The ultrasonic motor according to claim 3, wherein the second elastic body is integral with the holding elastic body.   The ultrasonic motor according to claim 3, wherein central axes of the first elastic body, the second elastic body, and the rod-shaped elastic body are integrated.

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