JP2878517B2 - Ultrasonic motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor for rotating a rotor using ultrasonic vibration.

[0002]

2. Description of the Related Art In recent years, an ultrasonic motor that rotates a rotor by using ultrasonic vibration has been developed.
Such an ultrasonic motor includes a piezoelectric element that generates torsional vibration in an outer peripheral direction of the stator and a piezoelectric element that generates vibration in an axial direction in a state where a rotor is in contact with one surface of a cylindrical stator. Are provided. Then, by combining the vibrations of the two piezoelectric elements, the upper surface of the stator is moved so as to draw a Lissajous figure, and the rotor in contact with the upper surface is rotated.

By the way, in the ultrasonic motor having the above-described structure, it may be necessary to detect the number of rotations of the rotor in order to control the rotation of the rotor. As means for detecting the number of revolutions of the rotor, a magnetized portion is provided outside the rotor, and a magnetic detection sensor is arranged in opposition to the magnetized portion, or a commercially available encoder is mounted and used. It is possible.

[0004]

However, the structure in which the magnetized portion and the magnetic detection sensor are arranged outside the rotor as described above is inevitably increased in size and cannot meet the demand for downsizing. However, when a commercially available encoder is used, there is an unsolved problem that it is difficult to further reduce the manufacturing cost.

Accordingly, an object of the present invention is to provide an ultrasonic motor which is inexpensive and capable of detecting the rotation of the rotor while reducing the size.

[0006]

Akira This onset for achieving the above object means to provide a process, inner periphery which is fitted rotatably on the outer periphery of the fixed shaft
An ultrasonic motor including a rotor having a cylindrical surface, a first piezoelectric element that applies axial vibration to the rotor, and a second piezoelectric element that applies vibration in a substantially tangential direction about a fixed axis. A magnetized portion is provided on the inner peripheral side of the rotor ,
The position of the magnetized portion at a position facing the magnetized portion of the fixed shaft
A magnetic detector for detecting magnetism is provided
It is characterized by the following. In the present invention, the fixed shaft
, A molded member having two flat portions on the outer periphery is fixed.
And the two flat portions are parallel to the axis center of the fixed shaft.
And are formed non-parallel to each other, and the magnetic
It is preferable that the air detection unit is attached.

[0007]

The operation of the present invention having the above configuration will be described. And magnetized on the inner peripheral side of the rotor, since there is provided a magnetic sensor for detecting magnetism of the magnetized portion, nothing need not be placed on the outer circumferential side of the rotor, this by downsizing It is not necessary to mount a commercially available encoder or the like. Then, the rotation number of the rotor can be detected by the magnetic detection sensor.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a front view showing a structure of an ultrasonic motor as one embodiment, FIG. 2 is an enlarged sectional view showing an internal structure of a portion indicated by reference numeral A in FIG. 1, and FIG. 3 is an exploded view of a portion shown in FIG. It is a perspective view. The illustrated ultrasonic motor 1 includes a stator 23 and a rotor 4 rotatably fitted to the stator 23. The stator 23 includes a fixed shaft 2 having a circular cross section, washers 14 and 17 fitted to the fixed shaft 2, stoppers 12 and 13, a coil spring 11, a bearing 3, first and second piezoelectric elements 18 and 19, A first to a third fixing members 20 to 22; a molded member 10 disposed in the rotor 4; and a pair of Hall elements 8, 8 as a magnetic detection sensor attached to a part of the molded member 10. It has.

The fixed shaft 2 has a threaded portion 2a at one end.
Is formed, and the other end is formed as the large-diameter end 2b. First to third substantially cylindrical fixing members 20 to 22 are fixed to the central portion of the fixed shaft 2 by press fitting or the like. Among them, the first piezoelectric element 18 is provided between the first fixing member 20 and the second fixing member 21.
However, the second piezoelectric elements 19 are interposed between the second fixing member 21 and the third fixing member 22 in close contact with each other.

The first piezoelectric element 18 is formed by laminating a plurality of piezoelectric elements in the axial direction of the fixed shaft 2, and generates vibration in the axial direction of the fixed shaft 2. On the other hand, the second piezoelectric element 19 generates vibration in a circumferential direction that intersects the radial direction around the fixed shaft 2. When the first and second piezoelectric elements 18 and 19 are simultaneously driven, the rotor 4 is rotated about the fixed shaft 2.

On the outer peripheral surface of the first fixing member 20, four concave portions 20a to 20d (not shown) are formed at intervals of 90 degrees. These recesses 20a to 20d
Are provided at the bottom of the Hall elements 8, 8 disposed in the rotor 4.
A cylindrical play insertion hole 20e for loosely inserting the lead wires 8a to 8d for guiding the output signal from the outside to the outside is formed. A ring-shaped friction member 5 having a large friction coefficient is adhered to the illustrated left end surface 20f of the first fixing member 20, and one end surface 4a of the rotor 4 is in contact with the friction member 5.
The pressure between the end face 4 a of the rotor 4 and the friction member 5 is set by the elastic force of the spring 11.

The rotor 4 has a concave portion 4c formed in an end surface 4b, and the bearing 3 is fitted into the concave portion 4c, whereby the rotor 4 is rotatable about the fixed shaft 2. Insert holes 4d for fixing rubber members described later are formed on the outer peripheral surface at 90 ° intervals, and a ring-shaped magnetized member 7 is fixed on the inner peripheral surface. This magnetized member 7
In this embodiment, N poles and S poles (shown in FIG. 3) are alternately magnetized on the inner peripheral surface at equal angular intervals around the fixed shaft 2 so that the rotation speed can be detected. But
A magnetized portion may be formed only on a part of the inner peripheral surface of the magnetized member 7 so that the rotational phase can be detected. The Hall elements 8 are arranged on the fixed shaft 2 side facing the magnetized member 7.

The two Hall elements 8, 8 are mounted on a molded member 10 shown in FIGS. FIG. 4 is an enlarged front view showing the detailed structure of the molded member 10, and FIG.
FIG. 6 is an enlarged side view of the molded member. The illustrated molded member 10 has a substantially cylindrical shape made of a synthetic resin having a cylindrical through hole 10a formed at the center, and is fixed to the fixed shaft 2 by press-fitting or bonding through the through hole 10a. It has become. One end of the molded member 10 is formed as a small-diameter end 10e, and a pair of locking members for locking the inner wall of the through-hole 9a of the substrate 9 formed in a ring plate shape at the one end. 10b are formed so as to protrude so as to face each other via the through hole 10a. The locking members 10b and 10b
Between them, protruding pieces 10c are formed to protrude.

On the outer peripheral surface of the small-diameter end portion 10e, flat portions 10f and 10g are formed at opposing positions sandwiching the through hole 10a. The flat portions 10f and 10g are formed non-parallel so that the planes including the flat portions 10f and 10g intersect, and the Hall elements 8 and 8 are arranged here. Hall elements 8, 8 arranged on these flat portions 10f, 10g
Is for detecting the magnetism of the magnetized portion of the magnetized member 7, and is in a non-parallel state along the arranged plane portions 10f and 10g. Since the two Hall elements 8 are arranged in a non-parallel state in this way, when the rotor 4 rotates in one direction, a phase difference occurs between the signals output from the two Hall elements 8. By detecting this phase difference, it is possible to detect not only the number of rotations of the rotor 4 but also the direction of rotation of the rotor 4 with the two Hall elements 8.

The projecting pieces 10c, 10c are
The substrate 9 has a shape curved along the inner peripheral surface of a and positions the substrate 9 locked by the locking member 10b by the distal end surface 10d. The terminals of the Hall elements 8 are inserted into the substrate 9 and soldered. A loose insertion for wiring the lead wires 24, 25 of the first and second piezoelectric elements 18, 19 along the axial direction to the large-diameter end 2b side of the large-diameter end 2b of the fixed shaft 2. Holes 26 and 27 are formed, and a screw portion 28 for attaching the apparatus to an external member (not shown) is formed at the center.

Incidentally, the rotor 4 is rotatably supported by the bearing 3 and is brought into pressure contact with the friction member 5 by two nuts 15 and 16 screwed to the screw portion 2a. That is, the coil spring 11 sandwiched between the stoppers 12 and 13 is interposed between the two nuts 15 and 16 screwed to the screw portion 2a and the bearing 3 fitted to the rotor 4. Accordingly, when the nut 16 is screwed in the right direction in the figure, the coil spring 11 is gradually compressed, and the elastic force accompanying this compression acts on the rotor 4. Therefore, adjustment of the rotation resistance and the like of the rotor 4 may be performed by adjusting the nut 16. The nut 15 is for preventing the nut 16 from loosening.

FIG. 7 shows one use mode of the ultrasonic motor having the above structure. FIG. 7 is a front view partially including a cross section showing a use mode of the ultrasonic motor described in FIGS. 1 to 6, and FIG. 8 is a perspective view including a partial cross section of the rubber member shown in FIG. When the illustrated ultrasonic motor is used, it is fixed to an external mounting member 30 via a bolt 31 screwed into the screw portion 28 of the fixed shaft 2. A rubber member 32 as shown in FIG. 8 is fitted around the outer periphery of the rotor 4. The rubber member 32 has cylindrical projections 32a which can be inserted into insertion holes 4d formed on the inner peripheral surface of the outer peripheral surface of the rotor 4 at intervals of 90 degrees. To prevent deviation.

A large diameter end 2b of the fixed shaft 2 has a bearing 33 having a diameter equal to the diameter of the rubber member.
And a cylindrical rotating member 34 is commonly fitted to the rubber member 32 and the bearing 33. In such a structure, when the first and second piezoelectric elements 18 and 19 are simultaneously driven, the rotor 4 is driven to rotate to one of the two, but the driving force of the rotor 4 is transmitted via the rubber member 32. The power is transmitted to the rotating member 34.

The rotating direction and the rotating speed of the rotating member 34 are sequentially detected by the magnetizing member 7 and the Hall elements 8 arranged in the rotor 4. With the ultrasonic motor having the above-described structure, there is no need to dispose a magnetized portion outside the rotor 4 or a Hall element for detecting magnetism generated in the magnetized portion. Therefore, a cylindrical rotating member as shown in FIG. 7 can be driven without difficulty. Also,
Because the diameter value of such a rotating member can be set small,
Even in a place where the space of the attachment portion is limited, it can be easily attached.

In FIG. 7, a rotating member indicated by reference numeral 34 can be used as a drive shaft of various devices and equipment. For example, the rotating member 34 can be used as a winding drive shaft of a roll curtain or a blind.

[0021]

According to the present invention described in detail above, a rotor whose inner peripheral surface is rotatably fitted on a fixed shaft and has a cylindrical shape, and a first piezoelectric element for applying axial vibration to the rotor. When, in the ultrasonic motor and a second piezoelectric element which gives almost vibration in the tangential direction around the fixed shaft, and magnetized formed integrally on the inner peripheral side of the rotor, further said adhesive
A magnetism detecting section that is located on the inner peripheral side of the rotor with respect to the magnetized section and that is attached to a fixed shaft side facing the magnetized section and detects the magnetism of the magnetized section; The rotation state of the rotor can be grasped. Further, there is no need to mount a commercially available encoder, and it is possible to reduce the manufacturing cost. In addition, two magnetic detection units are provided.
Each magnetic detector is arranged in a non-parallel state, and each magnetic detector is
By detecting the phase difference of the signal output from the
It is possible to detect the direction of rotation as well as the number of rotations.
You.

[Brief description of the drawings]

FIG. 1 is a front view showing the structure of an ultrasonic motor as one embodiment.

FIG. 2 is an enlarged sectional view showing an internal structure of a portion indicated by reference numeral A in FIG.

FIG. 3 is an exploded perspective view of a portion shown in FIG. 2;

FIG. 4 is an enlarged front view showing a detailed structure of a molded member.

FIG. 5 is an enlarged bottom view of a molded member.

FIG. 6 is an enlarged side view of a molded member.

FIG. 7 is a front view partially including a cross-section showing a use mode of the ultrasonic motor described in FIGS. 1 to 6;

FIG. 8 is a perspective view including a partial cross section of the rubber member shown in FIG. 7;

[Explanation of symbols]

 2 Fixed shaft 4 Rotor 8 Magnetic detector 7 Magnetizing member 18 First piezoelectric element 19 Second piezoelectric element 23 Stator

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Toshio Aoki 1-19-26 Shibakubo-cho, Tanashi-shi, Tokyo (56) References JP-A-62-254668 (JP, A) JP-A-3-49572 (JP) , A) JP-A-1-17955 (JP, A) JP-A-4-2984 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02N 2/00

Claims (2)

(57) [Claims] 1. An interior which is rotatably fitted around an outer periphery of a fixed shaft .
An ultrasonic motor including a rotor having a cylindrical surface, a first piezoelectric element that applies axial vibration to the rotor, and a second piezoelectric element that applies vibration in a substantially tangential direction about a fixed axis. Wherein a magnetized portion is provided on the inner peripheral side of the rotor .
The magnetized portion is located at a position facing the magnetized portion of the fixed shaft.
An ultrasonic motor provided with a magnetic detecting unit for detecting the magnetism of the unit . 2. The fixed shaft has two flat portions on its outer periphery.
The molded member having is fixed, the two flat portions are
It is formed parallel to the center of the fixed shaft and non-parallel to each other.
And the magnetic detection unit is mounted on the two flat portions.
The ultrasonic motor according to claim 1.