JP2985901B2 - Piezo motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small motor used in electronic equipment and the like, and more particularly to a piezoelectric motor which generates a high torque at a low speed.

[0002]

2. Description of the Related Art Piezoelectric motors are characterized by being able to obtain high torque at low rotation speed and not generating electromagnetic noise as compared with conventional electromagnetic motors. It's being used. The basic driving principle of such a piezoelectric motor is that a piezoelectric element that generates an elliptical motion is used as a stator, and a rotor pressed against the piezoelectric element generates a rotary motion via a frictional force. FIG. 10 shows an example of the related art having such a configuration. The piezoelectric motor shown in FIG.
And the laminated piezoelectric displacement element 2 are combined. The combination of the two movements causes an elliptical motion at the upper end of the laminated piezoelectric displacement element 2 and rotates the rotor 3 pressed against the laminated piezoelectric displacement element 2. It produces torque. Note that reference numeral 4 in FIG.
Is a metal block for resonance.

[0003]

However, in the above-described conventional piezoelectric motors and the like, even if the laminated piezoelectric displacement element 2 is used, it is difficult to obtain an amplitude enough to reliably drive the rotor 3 to rotate. Remained unresolved. Therefore, an object of the present invention is to provide a piezoelectric motor capable of obtaining a certain driving force.

[0004]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
According to the piezoelectric motor of the present invention, the drive shaft supported by the support in a cantilever manner and a bolt insertion hole provided in the support in a state housed in the screw member , respectively. Drive shaft
Are arranged at predetermined angular intervals around the center , and are displaced by the application of voltages having sequentially changed phases, and give a force in a direction orthogonal to the axis near the fixed end to the drive shaft,
The drive shaft includes a plurality of drive elements for displacing and circularly moving the drive shaft at its open end, and a rotating body that is rotationally driven by the circular movement of the open end of the drive shaft. In the above configuration,
The drive element comes into contact with the drive shaft in a pressure-contact state via the rolling elements
Preferably, or preferably, a displacement magnifying mechanism for increasing the amount of displacement of the drive element is provided, and a force is applied to the drive shaft via the displacement magnifying mechanism .

[0005]

According to the piezoelectric motor of the present invention having the above-described structure, a voltage having a phase that is sequentially changed is applied to a plurality of drive elements housed and arranged in a screw member near the fixed end of the drive shaft. By applying this voltage, the driving shaft is , for example, a rolling element
Alternatively, deflection can be caused by the driving element via the displacement enlarging mechanism . The displacement due to this deflection is amplified as it approaches its open end, where the rotating body is provided. That is, the amplitude of the drive element due to the applied voltage is amplified by the drive shaft and transmitted to the rotating body. In this way, a reliable driving force can be obtained .

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a state in which a piezoelectric motor according to a first embodiment is assembled, and FIGS. 2 and 3 are exploded perspective views showing the piezoelectric motor shown in FIG. 1 in an exploded state. The piezoelectric motor 10 shown in FIGS. 1 to 3 includes first and second cases 11 and 12 each having a cylindrical shape fitted to each other, an output unit 25 housed in the second case 12, A substantially cylindrical drive shaft 16 secured to the open end of the portion 25;
A plurality of piezoelectric elements 19 are provided near the left end of the drive shaft 16 in the figure. The drive shaft 16 is formed of duralumin in the present embodiment, and has a large-diameter cylindrical mounting portion 16a formed at the left end as shown in FIG. 1 case 11
Can be mounted cantilevered. A plurality of conical holes 16b having a substantially V-shaped cross section are formed near the mounting portion 16a. Here, a laminated piezoelectric element 1 described later is used.
Rolling element (ball) 21 interposed in a press-contact state between the rolling element and ball 9
Is arranged. Further, a flange 16c is provided near the right end in the figure.
Are formed. The flange 16c is for positioning an internal gear (drive-side gear) 23 that forms a part of an output unit 25 described in detail below.

The first case 11 includes the drive shaft 16
It is made of the same duralumin, and has a substantially cylindrical shape with a bottom. An insertion hole 11a into which the mounting portion 16a of the drive shaft 16 is inserted is formed at the center of the left end surface 11e of the first case 11, and the second case 12 is fitted to the outer peripheral surface at the right end. A joining portion 11b is formed. The fitting portion 11b has a female screw portion 11 on an opposing outer peripheral surface around a drive shaft 16 housed therein.
c, 11c are drilled. Further, in the present embodiment, the drive shaft 1 is provided on the outer peripheral surface near the left end of the first case 11.
Bolt insertion holes 11d centered at 6 are formed at 90 degree intervals. Here, the laminated piezoelectric element 19 is arranged. The mounting portion 16a of the drive shaft 16 and the first case 1
1 insertion hole 11a is a potato screw (set screw)
20, 20 are fixed.

The illustrated screw member 17 is screwed into each of the bolt insertion holes 11d. The screw member 17 has a screw portion 17a formed on the outer peripheral surface, and a groove 17
It is a cylindrical shape formed with b. The multilayer piezoelectric element 19 is accommodated in this. This laminated piezoelectric element 1
Reference numeral 9 denotes a structure in which a plurality of piezoelectric elements are stacked in the longitudinal direction, and the amplitude is increased when the applied voltage is turned ON / OFF. Each of the laminated piezoelectric elements 19 is in pressure contact with the drive shaft 16 via the rolling element 21. Reference numeral 18 denotes a screw member 17.
This is a lock nut for preventing loosening. The output unit 25 shown in the present embodiment includes a driving gear 23 fixed to an open end (right end in the drawing) of the driving shaft 16 and the driving gear 23.
And a driven gear 13 rotatably arranged to mesh with the driven gear 13.

The driving side gear 23 has a substantially cylindrical shape, and has a concave portion 23b formed on the right end surface in the figure.
3b are internal teeth having teeth 23a formed on the inner peripheral surface. Further, an insertion hole 23 into which the drive shaft 16 is inserted is provided in the shaft center.
c is formed. The driven side gear 13 is an external tooth that meshes with the driving side gear 23, and has a shaft 13a having a threaded portion formed on the outer peripheral surface on one side of the center of rotation. It is rotatably supported by the second case 12 via the shaft 13a. The second case 12 is formed of the same duralumin as the first case 11, and has a substantially bottomed cylindrical shape as a whole. A concave portion 12a is formed in the center of the right end face in the figure, and lock nuts 14 and 15 for the driven gear 13 are screwed into the concave portion 12a.
3 and is driven to rotate. In this case, the rolling elements 22, 24
Are arranged across the wall surface on which the concave portion 12a is formed,
The driven-side gear 13 itself is rotatably supported via the holding force of the lock nuts 14 and 15. As shown in FIG. 2, pit holes 12b, 12b are formed on the outer peripheral surface at the left end in the figure at positions corresponding to the female screw portions 11c formed in the first case 11.

The diameter (tooth circle diameter) of the driven gear 13 is set smaller than the diameter (tooth circle diameter) of the recess 23b of the drive gear 23, and the drive shaft 16
Are not displaced, that is, in a neutral state, so that they do not come into contact with each other. That is, in this embodiment, the number of teeth formed on both sides is 404
The number of driven gears 13 is 400. By making the number of teeth slightly different in this way, a reduction ratio corresponding to the difference in the number of teeth is obtained. The speed reduction ratio in the case of this gear ratio is (4/400) = (1/100). still,
The number of teeth of the driving side gear and the driven side gear is not limited to the above number of teeth, and may be appropriately set in consideration of the reduction ratio to be obtained or the like. A general expression of the relation between the ratio of the number of teeth and the output rotation speed N in this motor is as follows: N = {(Z1-Z2) / Z2} × 60 × f (rpm) Where N is the number of output rotations, Z1 is the number of teeth on the driving side gear (internal gear), Z2 is the number of teeth on the driven side gear (external gear),
f is a vibration (rotational vibration) frequency (Hz).

The operation of the embodiment device having the above configuration will be described with reference to FIG. FIGS. 4A to 4D are explanatory views showing the operating states of the driving gear and the driven gear. Note that the actual difference in the number of teeth between the two gears is as small as four, and the difference in the diameter between the driving gear 23 and the driven gear 13 is small. However, in each of FIGS. The diameter ratio is exaggerated. First, in this embodiment, voltages having sequentially different phases are applied to the four laminated piezoelectric elements 19. As a result, the open end of the drive shaft 16 is displaced so as to draw a circular motion trajectory clockwise as shown in FIGS. 4 (A) to 4 (D). In this case, since the laminated piezoelectric element 19 is disposed near the fixed end of the drive shaft 16, the displacement of the drive shaft 16 displaced by the laminated piezoelectric element 19 is changed from the fixed end to the open end. To be amplified. When voltages having sequentially different phases are sequentially applied to the four stacked piezoelectric elements 19 in this manner, the meshing portion between the driven gear 13 and the driving gear 23 changes from the state shown in FIG. The state sequentially changes to the state shown in FIG. In FIG. 4, the center of the drive shaft 16 and the output shaft 13a is indicated by O1, and the center of the drive gear 23 is indicated by O2. When voltages having sequentially different phases are sequentially applied to the four stacked piezoelectric elements 19 to cause the open end of the drive shaft 16 to perform a circular operation, for example, as shown in FIGS. The center O2 of the gear 23 rotates clockwise about the center O1 of the shaft 13a or the like.

In the state shown in FIG. 1A, the drive shaft 16 (not shown in the figure) is displaced rightward in FIG.
Is moving rightward, and in this state, the driven gear 1
3 and the left side of the drive-side gear 23 mesh with each other. In this state, when voltages having different phases are sequentially applied to the four laminated piezoelectric elements 19, the open end of the drive shaft 16 is displaced to a state shown in FIG. . Due to such displacement of the drive shaft 16, the drive side gear 23 attached to the release end rotates the driven side gear 13 in the meshed state by a predetermined angle in the counterclockwise direction. Similarly, when the drive shaft 16 is sequentially displaced, the driven gear 13 meshed with the drive gear 23 is sequentially rotated counterclockwise by a predetermined angle.

When the drive shaft 16 is displaced from the state shown in FIG. 3D to the state shown in FIG.
It rotates by the difference between the number of teeth of the driving side gear 23 and the number of teeth of the driven side gear 13. In this embodiment, since the difference in the number of teeth is 4, if the series of movements shown in FIGS. 4A to 4D is performed 100 times, the driven gear 13 makes one rotation. That is,
In this embodiment, the reduction ratio is set to (1/100) as described above. When the application of the voltage to the multilayer piezoelectric element 19 is stopped, the curved displacement state of the drive shaft 16 is released, and the drive side gear 23 and the driven side gear 13 do not mesh with each other. Therefore, when it is necessary to stop the drive shaft 16 at a fixed rotational position, a state in which a voltage is applied to any one of the stacked piezoelectric elements 19 may be employed.

In the first embodiment described in detail above, the amplitude of the laminated piezoelectric element 19 that expands and contracts according to the applied voltage is amplified by the drive shaft 16. Therefore, it is possible to perform a reliable operation that cannot be obtained with a conventional piezoelectric motor of this type. Further, if the driving frequency of the multilayer piezoelectric element 19 is made to coincide with the primary resonance frequency of the driving shaft 16 or a frequency near the primary resonance frequency, the displacement of the open end of the driving shaft 16 can be further increased, thereby further ensuring Operation can be secured. Further, in the present embodiment, since the output unit is constituted by a gear, it is possible to output a constant rotation speed. Further, since the gear ratio can be set arbitrarily, a desired reduction ratio can be obtained. The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the invention. In the above embodiment, the output portion provided at the open end of the drive shaft is provided with an internal tooth fixed to the drive shaft, and a driven-side gear rotatably supported by the second case so as to be meshable therewith. However, the output unit may be configured as shown in FIG.

The output section 26 shown in FIG. 5 includes a drive member 27 having one end fixed and an external gear 26a formed at the other end, and an internal gear 28 meshing with the external gear 27a. It is provided with. That is, in the illustrated embodiment, the driving gear and the driven gear are replaced with each other to have the same configuration. Even with the output unit having such a configuration, the same effects as those of the illustrated or described embodiment can be obtained. By the way, in each of the above embodiments, the driving member has a circular cross section as an example. However, the driving member may have a cross section shown in FIGS. 6 to 8. First, the driving member 29 shown in FIG. 6 has a rectangular cross section. The same layered piezoelectric element 19 as described above is fixed on each side surface and near the fixed end portion 29a.

The driving member 30 shown in FIG. 7 has a triangular cross section, and the driving member 31 shown in FIG. 8 has a hexagonal cross section. in this case,
A piezoelectric element indicated by reference numeral 32 is pressed against each side surface. Even with a piezoelectric motor provided with each drive member having such a shape, the same effects as those of the above embodiments can be obtained. In each of the above embodiments, when no voltage is applied to the multilayer piezoelectric element, the dimensions and the number of teeth are set so that the driving gear and the driven gear do not mesh with each other. The difference between the number of teeth of the side gear and the number of teeth of the driven side gear may be further reduced so that when the driving side gear to which no voltage is applied is in the neutral state, the tooth tips of both gears are in mesh with each other. As a result, when no voltage is applied, the driven member does not rotate and is in a fixed state. Further, the driving side gear and the driven side gear may be elliptical instead of circular. Even with a piezoelectric motor having such a configuration, the same effects as those of the above-described embodiments can be obtained.

Further, in the present invention, a structure like the second embodiment shown in FIG. 9 is also possible. In this embodiment, the drive shaft 1
As a mechanism for displacing the piezoelectric element 6, a displacement enlarging mechanism 35 for enlarging the displacement of the laminated piezoelectric element 19 by leverage is provided. For example, the laminated piezoelectric element 19 and the displacement magnifying mechanism 3
4 are provided in the same manner as in the first embodiment, and by applying voltages having different phases to the respective laminated piezoelectric elements 19, the rotational displacement amount of the drive side gear 23 shown in FIG. The amplitude of the open end of the drive shaft 16 is enlarged. As a result, for example, when the number of teeth of the driving-side gear 23 and the number of teeth (reduction ratio) of the driven-side gear 13 are set to certain values, the pitch circle of the gear can be made larger than in the first embodiment. Module can be enlarged. Therefore, the teeth can be made large, the slip of the teeth of both gears can be eliminated, and the gear having a large module can be easily manufactured. FIG. 9
In this embodiment, as shown in FIG. 5, the driving side may be an external gear and the driven side may be an internal gear.

Further, in both the first and second embodiments, ie, FIGS. 1, 5 and 9, the gears 23 and 27a provided at the ends of the drive shaft are connected to the drive shaft 16 and the drive member 27. The other gear 2 is provided rotatably by a bearing.
By fixing 3, 28, the gear on the drive shaft side can also be rotated. Further, in each of the above embodiments, a piezoelectric material element is used as the driving element, but a giant magnetostrictive material element, a shape memory alloy element, or the like may be used.

[0019]

According to the present invention described in detail above, a piezoelectric motor capable of obtaining a certain driving force can be provided .

[Brief description of the drawings]

FIG. 1 is a sectional view showing a state in which a piezoelectric motor according to a first embodiment is assembled.

FIG. 2 is an exploded perspective view showing the piezoelectric motor shown in FIG. 1 in an exploded state.

FIG. 3 is an exploded perspective view showing the piezoelectric motor shown in FIG. 1 in an exploded state.

FIGS. 4A to 4D are explanatory diagrams showing a meshing state between a driving gear and a driven gear.

FIG. 5 is a configuration explanatory view showing another embodiment of the output unit.

FIG. 6 is a schematic perspective view showing another embodiment of the driving member.

FIG. 7 is a schematic perspective view showing another embodiment of the driving member.

FIG. 8 is a schematic perspective view showing another embodiment of the driving member.

FIG. 9 is a schematic diagram of a structure of a piezoelectric motor according to a second embodiment.

FIG. 10 is a perspective view showing a configuration of a conventional piezoelectric motor.

[Explanation of symbols]

 16, 29 to 31 Drive shaft 19, 32 Piezoelectric element 25 Output unit 23 Drive side gear 13 Driven side gear 35 Displacement enlargement mechanism

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Iwao Hayashi 440-11 Tsuruma, Machida-shi, Tokyo (72) Inventor Nobuyuki Iwatsuki 3-24-34 Nagatsuda, Midori-ku, Yokohama-shi, Kanagawa (56) References -167963 (JP, A) JP-A-60-229680 (JP, A) JP-A-60-160384 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02N 2/00

Claims (3)

(57) [Claims] 1. A drive shaft supported by a support in a cantilever manner, and a drive shaft which is screwed into a bolt insertion hole provided in the support while being housed in a screw member.
It is arranged at a predetermined angular interval, is displaced by applying a voltage of which phase is sequentially changed, and applies a force in the direction orthogonal to the axis near the fixed end to the drive shaft, thereby causing the drive shaft to A piezoelectric motor, comprising: a plurality of driving elements which are displaced at an open end to make a circular motion; and a rotating body which is rotationally driven by the circular motion of the open end of the drive shaft. 2. A drive element is pressed against a drive shaft via a rolling element.
The piezoelectric motor according to claim 1, wherein the piezoelectric motor contacts in a state. 3. A displacement magnifying mechanism for enlarging a displacement amount of the driving element is provided, a piezoelectric motor according to claim 1, wherein empowering the drive shaft through the displacement enlarging mechanism.