JPH0533688U - Ultrasonic motor - Google Patents

Abstract

(57) [Summary] [Purpose] The load of compression on the rotor is made uniform and high efficiency,
Achieve high torque, stabilize characteristics, and achieve compactness. [Structure] Ultrasonic motor rotor 20 has first magnet 22
The second magnet 22b which is provided with a and repels it
Nut 2 for screwing the shaft to a central shaft 24 that pivotally supports the rotor
Stick to 3.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an ultrasonic motor, and more particularly to an ultrasonic motor that excites ultrasonic vibrations in a piezoelectric vibrator to generate driving force.

[0002]

[Prior Art]

 The recently developed ultrasonic motor is a motor based on a new principle that obtains rotational force by ultrasonic vibration. Compared to the conventional electromagnetic motor based on the interaction between current and magnetic field, it has characteristics of low speed and high torque. In other words, the torque per unit volume is much higher than that of the electromagnetic motor, and it is possible to reduce the brake and the brake when using it at a low speed. It has the advantage of excellent responsiveness due to its large holding power. Various ultrasonic motors have been proposed so far, for example, an ultrasonic motor using longitudinal-torsion composite vibration reported in pp. 821 to 822 of the Acoustical Society of Japan (Oct. 1988). -There is something like that. Such an ultrasonic motor is practical as a device having a small diameter and high torque.

FIG. 2 is a sectional view showing the right half of an ultrasonic motor as a conventional example in cross section. As shown in FIG. 2, the conventional ultrasonic motor comprises a stator 60 and a rotor 70. The stator 60 includes a vertical vibrator (hereinafter, referred to as a vertical vibrator) 61 made of a laminated piezoelectric actuator, and a Langevin type piezoelectric element for torsional vibration excitation (hereinafter, referred to as a torsional vibrator) 62. , The metal block 64 and the insulators 66a and 66b (hereinafter, considered as a part of the vertical oscillator 61), and are stacked on the head portion 65 of the central axis 67a. The head mass 63 is centrally supported by the central shaft 67a and abuts on the stator 60 to be stacked. The rotor 70 is rotatably supported via a bearing 71 on a central shaft 67b arranged on the same axis as the central shaft 67a and fixed to the head mass 63, and is mounted in contact with the head mass 63. A pedestal 74 and a spring 72 are mounted on the rotor 70 in a state of being inserted into the central shaft 67b, and a nut 73 is screwed to the central shaft 67b and abuts on the spring 72 at the upper end of the same. .. The stator 60 is driven in a torsional resonance mode, but the vertical oscillator 61 is excited non-resonantly in a form matching the resonance frequency of the stator 60. Also, as is well known in the operation of the transducer portion of the mechanical channel filter using the torsion mode, the stator 60 operates in the mode by the torsional deformation of the round bar similar to the movement of squeezing the cloth. Moreover, the momentum is further amplified by the head mass 63. Therefore, the end face of the head mass 63 where the stator 60 and the rotor 70 contact each other can generate a rotational force in the clockwise direction and the counterclockwise direction at the resonance frequency.

Here, a case where the rotor 70 is rotated counterclockwise will be described. When the end face of the head mass 63 abutting on the rotor 70 rotates counterclockwise so that the nut-tightened stator 60 gives a counterclockwise rotational force to the rotor 70, the vertical vibrator 6 1 Is extended in the axial direction in synchronism with the torsional vibration, and a voltage is applied from another power source so as to cause deformation, and the rotor 70 and the head mass 63 are momentarily and strongly pressed against each other. The frictional force at this time allows the rotor 70 to obtain a large rotational force in the counterclockwise direction. Furthermore, when the surface of the head mass 63 that contacts the rotor 70 rotates clockwise, the longitudinal vibrator 61 is contracted in the axial direction, and the pressure contact force between the rotor 70 and the head mass 63 is temporally reduced to zero. Then, the clutch works so as not to transmit the clockwise torsional vibration displacement to the rotor 70. Therefore, the rotor 70 can smoothly rotate in the counterclockwise direction by a series of operations of the torsional vibration of the stator 60 and the stretching vibration of the vertical vibrator 61 disposed in the stator portion. ..

On the other hand, when the rotor 70 is rotated clockwise, the stator 60 is excited at the torsional resonance frequency as it is, and the rotor 70 is reversed to the vertical oscillator 61 that performs the clutch operation. It is only necessary to change the phase so that the phase is different by 180 degrees from the case of rotating clockwise. In this case as well, the rotor 70 can smoothly rotate clockwise in the same manner.

The vertical vibrator 61 and the torsional vibrator 62 are both made of piezoelectric ceramics. As is well known, the piezoelectric ceramics are extremely strong against a compressive force, but are strong against a tension. Extremely brittle. It is necessary to apply a large compressive bias stress to the vertical oscillator 61 and the torsion oscillator 62 at all times. Also, in order to transmit the rotation of the stator 60 to the rotor 70, it is essential that the head mass 63 and the rotor 70 are strongly pressed, and the central shaft 67b is used to connect the head mass 63 and the rotor 70 to each other. The solid coil spring 72 and the nut 73 are pressed and held via the pedestal 74 and the bearing 71. Further, in order for the stator 60 to perform torsional vibration, the head mass 63, the vertical oscillator 61 and the torsional oscillator 62 must be firmly connected. Therefore, in the conventional ultrasonic motor, the vertical oscillator 61 and the torsion oscillator 62 are fastened and coupled to the head mass 63 by the central shaft 67a.

[0007]

[Problems to be solved by the device]

 In the conventional ultrasonic motor, the head mass 63 and the rotor 70 are held by a strong coil spring 72, which is why the spring having a tough spring constant and excellent impact resistance are used. Bearings are needed. However, when a compression coil spring is used, there are problems that the radial direction is restricted due to stress, the wire diameter becomes thin due to manufacturing, and the length becomes long. Further, when the wire rod is also shortened by using a leaf-spring type compression coil spring, there is a problem in that the end face of the spring is poorly seated and uniform pressure contact cannot be obtained. Therefore, in any case, the use of the coiled splint inevitably lengthens the ultrasonic motor. Also, a bearing 71 is built in so that the rotor 70 can rotate smoothly, but since it is driven at an extremely high drive frequency of several tens of kilohertz, the inner and outer rings of the bearing and the ball are subjected to an impact compression load. In response to this, the heat rises and the oil content evaporates, causing damage. The present invention solves the above problems, makes the load of compression load on the rotor uniform, realizes high efficiency and high torque, and is stable and reliable with no change in characteristics over a long period of time. The objective is to provide an ultrasonic motor that has high cost and can be made compact.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a stator comprising a vertical / torsional composite oscillator, a head mass for transmitting the vibration mode of the stator, and a central support for the stator and head mass. In an ultrasonic motor composed of a central axis that rotates, and a rotor that is pivotally supported by the central axis and is pressed against the head mass, a rotor is provided with a first magnet that is rotatable with respect to the central axis. And an ultrasonic motor in which a second magnet repulsive to the first magnet is arranged at a position opposed to the first magnet of a nut screwed to the central axis. It is what constitutes.

[0009]

【Example】

 Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional structural view showing the right half of an ultrasonic motor according to an embodiment of the present invention. Reference numeral 10 is a stator, 11 is a head mass, 12 is a sliding member, 20 is a rotor, 21 is a bearing, 22a and 22b are magnets, 23 is a nut, and 24 is a central axis. The stator 10 is composed of the same components as those described in FIG. Further, the operation of the ultrasonic motor stator 10 of the present embodiment is performed according to the same principle as in the conventional case of FIG. The rotor 20 has a cylindrical shape, a bearing 21 and a first magnet 22a are arranged in the cylinder, and is rotatably supported by a central shaft 24. Further, a screw portion is provided near the tip of the central shaft 24, and a nut 23 is provided, and the nut is provided with a second magnet 22b in a direction repulsive to the first magnet 22a. Therefore, the force with which the end surface of the rotor 20 presses the stator 10 is adjusted by adjusting the space between the second magnet 22b and the first magnet 22a by the nut 23, and of course the pressure contact force adjustment. Is also possible. The sliding member 12 is a member having excellent wear resistance and is bonded to the end surface of the head mass 11.

To enable the ultrasonic motor to operate, the stator 10 and the rotor 20 must be pressed against each other with a strong static force when the ultrasonic motor is not operating. The central shaft 24, the nut 23, and the second magnet 22b constitute static pressure applying means, and the second magnet 22b repulsive to the first magnet 22a supporting the rotor is provided with a slight gap so that the nut 23 When the rotor 20 rotates, the central shaft 24 and the nut 23 as the pressure applying means do not rotate. As is apparent from the above-mentioned configuration, the stator 10 operates in a mode due to the torsional deformation of the round bar, which is similar to a squeezing motion with a rag. By the way, since the rotor 20 receives the elliptical motion of the end surface of the head mass 11 and rotates by frictional force, it can be seen that the pressure contact force to the end surface of the head mass 11 significantly affects the characteristics. Therefore, it is necessary to optimally adjust the pressing force with the nut 23 and fix the nut 23 to the shaft 24 completely. Therefore, it is effective to melt and fix several points of the connecting screw portion of the central shaft 24 and the nut 23 by spot welding. In addition to laser spot welding, electric spot welding can be used for spot welding.

[0011]

[Effect of the device]

 The present invention has the following effects. The ultrasonic motor of the present invention is arranged so as to repel the magnet inside the rotor and is provided in a non-contact state, so that the pressure contact force to the rotor can be equalized, and the bearing Since the press contact force that was being received became non-contact, rotation fluctuation was minimized and high efficiency and high torque could be realized. Furthermore, since the pressure contact means utilizes the repulsive force of the magnets from the springs, the springs become unnecessary and the total length of the motor can be reduced, enabling compact mounting in the device.

[Brief description of drawings]

FIG. 1 is a cross-sectional structural view showing the right half of an ultrasonic motor according to an embodiment of the present invention.

FIG. 2 is a structural view showing a right half of an ultrasonic motor as a conventional example in a cross section.

[Explanation of symbols]

 10 Stater 11 Head Mass 12 Sliding Material 20 Rotor 21 Bearing 22a First Magnet 22b Second Magnet 23 Nut 24 Center Shaft

Claims (1)

[Scope of utility model registration request] 1. A stator comprising a vertical / torsional composite oscillator, and a head mass for transmitting a vibration mode of the stator.
In an ultrasonic motor composed of a central axis that centrally supports the stator and the head mass, and a rotor that is pivotally supported by the central axis and that is pressed against the head mass.
The rotor is provided with a first magnet that is rotatable with respect to the central axis, and a second screw that repels the first magnet is provided at a position of the nut screwed to the central axis opposite to the first magnet. An ultrasonic motor characterized by arranging a magnet.