JPS6022477A - Step motor - Google Patents

Abstract

PURPOSE:To form a pulse motor which has good efficiency and excellent response by rotating an output shaft with the deformation of a piezoelectric element for producing a strain in response to a pulse signal as the rotary motion by deformation/rotation converting means. CONSTITUTION:An output shaft 14 mounted with an outer teeth gear 27 is rotatably supported via a bearing 14 to a housing 13 formed of annular plates 13a, 13b, and deformation generators 15a-15c in which piezoelectric elements 16a- 16c are contained in deformation enlarging units 17a-17c are rockably supported via pins 12a-12d. An inner gear 26 of hexagonal shape to be engaged with a low rigidity unit 25 of the unit 17 is provided, and disposed eccentrically with respect to the center of rotation of the gear 27. Therefore, when a pulse voltage is sequentially applied to piezoelectric elements 16a-16c to rotate the shaft 14 via the unit 17, the inner and outer gears 26, 27 to reduce the loss, thereby improving the response property.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a step motor, and more particularly, to a step motor that rotates an output shaft by converting deformation of a strain element that generates strain into rotational motion in response to a pulse signal.

(Prior art) As is well known, a step motor has an output shaft that rotates by a fixed angle in response to an input pulse signal, and is used as a drive source for positioning a controlled object using digital control. . Conventionally, such step motors are known to use magnetic coils, and this type of step motor has a plurality of stator windings and convex poles corresponding to the stator windings. It has a rotor,
It rotates by sequentially inputting pulse signals to the stator winding.

However, the step motor using the above-mentioned magnet coil has a problem in that copper loss and iron m are generated when the stator winding is energized, resulting in lower efficiency and generation of heat. Furthermore, since the stator winding has inductance, there is another drawback that its response speed is low.

(Objective and Structure of the Invention) The present invention has been made in view of the above-mentioned drawbacks, and in order to improve efficiency and response speed, the present invention includes a strain element that causes °ζ deformation in response to a pulse signal; and a deformation/rotation conversion means that engages with the strain element and the output shaft to convert the deformation of the strain element into rotational motion and transmits it to the output shaft, the output shaft rotating by a predetermined angle in response to a pulse signal. It provides a mode of communication.

The step motor according to the present invention causes a one-dimensional deformation of the strain element by inputting a pulse fl'1 to the strain element such as a piezoelectric element, and transforms the deformation of the strain element into a rotational movement using a deformation rotation conversion means. is transmitted to the output shaft, and the output shaft rotates. Therefore, unlike a conventional step motor using a solenoid, copper loss or iron loss does not occur, and furthermore, since the strain element has no inductance, its responsiveness is improved.

(Example) Embodiments of the present invention will be described below based on the drawings.

1 to 3 are diagrams showing one embodiment of the present invention.

First, to explain the configuration, reference numeral 11 indicates a step motor as a whole, and this step motor 11 is made up of two annular plates 13a and 13b connected by six pins 12a, 12b, 12c, 12d, 12e, and 12f. It has a housing 13 consisting of. Each pin 12a, 12b, 12
c, 12d, 12e, 12f are respective annular plates 13a, 13
It consists of a small diameter part fitted to the b, and a large diameter part between the small diameter parts, and the large diameter part is interposed between the annular plates 13a and 13b so that the annular plates 13a and 13b are spaced apart at a predetermined interval and the annular plate 13a ,1
3b are held substantially parallel. These annular plates 13a,
13b, the output shaft 14 rotatably passes through the hair rings 14a and 14b, and IN 1eFi 13
Between a and 13b, three first, second, and third deformation generators 15a, 15b, and 15C are arranged at equal intervals (120 degree intervals) around the output shaft 14.

Each of the deformation generators 15a, +5b, 15c utilizes a well-known piezoelectric element that causes elongation deformation when a voltage is applied as a strain element, and each of the deformation generators 15a, +5b, 15c uses a piezoelectric element 16a, 16b connected to a drive device to be described later. , 16c, and deformation expanders 17a, 17b, ITC that magnify the deformation of the piezoelectric elements 16a, 16b, 16C. Note that each of the deformation generators 15a, 15b, and 15c has the same configuration, so in the following description, only the first deformation expander 15a will be explained, and the other second and third deformation generators 15b will be explained.
, 15C are designated by the same reference numerals and the suffix "c" is added to distinguish them, and the explanation thereof will be omitted.

The deformable expander 17a consists of a frame 19a in which a storage hole 18a is formed to accommodate the first piezoelectric element 16a, and a base 20a, a pair of arm parts 21a and 22a, and an extension part 23a are set in the frame 19a. ing.

A through hole 24a is formed in the base 20a, and the through hole 24a is formed in the base 20a.
The pin 12a is rotatably passed through the base 20a.
That is, the frame body 19a is swingably supported by the housing 13. Each of the arm parts 21a and 22a has one end connected to the base part 20a by a thin, low-rigidity part so as to be rotatable, and the other end, which is an extension part 23a, connected to both ends of the extension part 23a. The piezoelectric element 16a is connected by a low-rigidity portion and rotates about the connection portion with the base portion 20a as the piezoelectric element 16a expands and contracts. The elongated portion 23a has a low rigidity portion 25a that is bendable and deformable and engages with an internal gear to be described later.
is formed and can be expanded by deforming the low rigidity portion 25a. Note that the low-rigidity portion 25a of the extension portion 23a is located radially outward from the imaginary straight line connecting the joint portion of the extension portion 23a and the arm portion 21a%22a.

This first deformation occurrence 'lA15a occurs when a driving pulse voltage is input to the piezoelectric element 16a and the piezoelectric element 16a undergoes elongation deformation.
, 22a rotate in the direction of moving away from each other around the joint with the base 20a, so the extending portion 23a extends while deforming the low-rigidity portion 25a, and at this time, the low-rigidity portion 25a The gear is pressed radially inward in the direction indicated by arrow A in the figure.

The thickness of the frame 19a and the piezoelectric element 16a is made slightly smaller than the distance between the annular plates 13a, 13I so that they do not slide on the inner surfaces of the annular plates 13a, 1; (b) when they swing. In addition, in the gap between the frame body 19a and the annular plate 138.13b at both ends of the large diameter portion of the pin 12a,
It is preferable to install a thin disk-shaped thrust bearing.

26, the first round part is (j 1st, 2nd, 3rd, 4th, 5th and 1st corner tI% t2, L3, t-4
, L5, and LG, and internal teeth are formed on the inner periphery of the internal gear, and 27 is an output with external teeth that mesh with the internal teeth of the internal gear 26 formed on the outer periphery. axis 14
The internal gear 26 and the external gear 27 have eccentric rotation centers. The number of teeth of the internal gear 26 is one or more greater than the number of teeth of the external gear 27. The internal gear has first, third, and fifth corner portions 1 formed on its outer periphery. ．． 1. ,t,
engages each deformation generator 15a, 15b, 15C, and the deformation generators 15a, 15b, 15c operate in a predetermined order, thereby causing each corner 1. ．． 13.15 is pressed and revolves, rotating the external gear 27, that is, the output shaft 14.

That is, the internal gear 26 and the external gear 27 constitute a planetary gear reduction gear. Further, the internal gear 26 and the external gear 27 constitute a deformation rotation conversion means 28.

As shown in FIG. 2, the drive device 29 is connected to a distribution circuit 30 to which a command pulse signal C is input from a control device (not shown) and a line distribution circuit 30, and supplies a drive pulse voltage P to the first deformation generator 15a. The first voltage amplification circuit outputs a! j! t31a
and a second deformation generator +5 b connected to the distribution circuit 30.
-・Second voltage amplification circuit 3 that outputs the drive pulse voltage pb
1b, an 883 voltage amplification circuit 31c that is connected to the distributor Tj1130 and outputs the drive pulse voltage pc to the third deformation generator 15c, and an 883 voltage amplification circuit 31c that is connected to an AC power source (not shown) and is connected to the distribution circuit 3.
0 and 11 second and third voltage amplification circuits 31a, 31b
, 31c. The distribution circuit 30 maintains the drive pulse voltages Pa, Pb, and Pc of the voltage amplification circuits 1m31a, 31b, and 31c in a predetermined phase relationship in synchronization with the command pulse signal C. Voltage Pa, pb.

Pc has a phase as shown in FIG. 3a. That is,
Each of the driving pulse voltages Pa, Pb, and Pc is set such that the pulse amplitude l1tiiA is set to about 1,000 V, the dual tip lid D has 50%, and each driving pulse voltage P
The phase difference between a, Pb, and Pc is 60 deH.

Next, the action will be explained.

In the step motor 11 according to the present invention, as described above, the piezoelectric elements 16 a , 16 b , 16
C is the drive pulse voltage Pa, pb, Pc from the drive device 29
is applied, the first, third and fifth corners 1. of the internal gear 26 are deformed. ．． 13.1. Press. On the other hand, the driving pulse voltages P a % P b 1 P c are
Since the internal gear has the relationship (phase) shown in Figure a, its corner 1. , t2, t3, t-4, t5,
t, a force A l , A2 as shown by the arrow in Figure 1 a
, A3, A-4, A5, and Ag are sequentially added to it and it revolves. That is, the internal gear 26 is swingably supported with respect to the housing 13, and the first deformation generator 15
When only the first corner t is pressed by the force A1, the first corner 1.b receives the force A1, and the first corner 1. and when the third corner t3 is pressed, the first corner 1. and force A2 as a resultant force of forces A, A3 applied to the second corner t20, and similarly, forces A3, A-4, A5, A-4, A5, Ao is added. Therefore, the internal gear 26 is driven by the drive pulse voltage p2. In one cycle of pb, T)c, the external gear 27 is driven by one revolution, and the output shaft 14 is rotated by a predetermined angle. Note that the rotation angle θ of the output shaft 14 each time the voltage applied to the piezoelectric elements 16a, 161) and I(ic) changes is calculated by the following equation.

θ-((Z2-z,)/z,) -1/ (2N)X
360 deg - complete set However, Z: Number of teeth of gear 27 Z2i Number of teeth of internal gear 26 N; Number of 11M of piezoelectric element 16 As described above, in the step motor 11 of the present invention, the output The power for rotating the shaft 14 is generated by the piezoelectric element +6
a, 16 b, +6 (: Pulse voltage Pa.

When applying P b -, P c, the piezoelectric element +
6a.

In addition, the piezoelectric elements 1 16a, 16b, and 16c do not generate heat when energized and quickly deform in response to the applied voltage, so they can achieve high efficiency without generating heat or the like. In addition, it is possible to obtain good responsiveness, and it is also possible to make the device compact, especially thin.

Next, even if the drive pulse voltages Pa, Pb, and Pc are not applied to any of the piezoelectric elements 16a, 16b, and 16c, the step motor 11 is configured such that the internal gear 26 and the external gear 27 are in mesh with each other. In addition, since the internal gear 26 and each deformation generator 15a, 15b, 15c are engaged, the output shaft 14 is mechanically restrained. That is, since the step motor 11 has a mechanical self-holding function, there is no need to provide a special self-holding mechanism.

Note that in this embodiment, each piezoelectric element 16a, 16
b, 16c to drive pulse voltage pa with the phase shown in FIG. 3a.
spb', Pc were applied, but the step motor 11 rotates even if driving pulse voltages Pa, Pb, 2pc are applied with the phases shown in FIG.

However, with the phase shown in FIG. 3, the drive pulse voltage Pa,
When Pb and Pc are applied, the internal gear 26 has 120
dcg interval force A, , A3 , A.

are added sequentially. Note that in this case, the rotation angle θ per 1′ HA motion pulse is twice the value calculated using the 81° formula described above.

4a, b and 5 a, b show two other embodiments of the invention. These embodiments use more deformation generators to reduce the step angle. In the following description, the same parts as those in the embodiment described above are given the same numbers, and the description thereof will be omitted.

First, the step motor 11 shown in FIG.
deformation generators 15a, 15b, 15C115d, 15
It uses e. That is, as shown in the figure,
The internal gear has five corners t1 and t2 on its outer periphery.
, t3, t'4, t,
Housing 1 is attached to the five corners 1°3 t2, t3, t-4, and t, respectively.
Deformation generators 15a, 15b, which are swingably supported by
15c, 15d, and 15e are engaged. Further, internal teeth having a number of teeth that is one or more more than the number of teeth of the external gear 27 provided on the output shaft 14 are formed on the inner circumference of the internal gear 26 . constitutes a planetary gear reducer as in the first embodiment.

Further, the internal gear 26 and the external gear 27 constitute a deformation rotation conversion means 28. In this step motor 11, as in the above-described embodiment, the driving device 29 inputs a drive to each deformation generator 15a, 15b, 15C115d, 15(+ piezoelectric element 16a, 16b, 16c, 16d, 16e). Pulse signals Pa, P b, Pc,
By controlling the phase of PdXPe to a predetermined relationship, the internal gear 26 revolves, and the external gear 27, that is, the output shaft 14, is rotated by a predetermined angle.

This step motor 11 includes five deformation generators 15a,
15b, 15c, 15d, and 15e, the step angle can be made smaller than that of the above-mentioned embodiment.
1 deformation generator +5 a, 15 b, 15 c
.

15d, and these deformation generators 15a, 151), 1
5C115 (1 makes the internal tooth i'li 26 revolve.The internal gear 21i 4.1 is a square whose outer periphery has four corners t, , +2, t, , t', These corners Ll, t2, +3, t
-4 respectively deformation generators 15a, 15b, 15
c, 15d are engaged.

Even in this step motor 11, each deformation generator 15
Piezoelectric elements 16a, 16a, 15b, 15c, 15d
b, 16c, +6 d - By applying a drive pulse voltage with a predetermined phase difference, the internal gear 26 revolves and drives the external gear 27, so the output shaft 14 rotates.

(Effects of the Invention) As explained above, according to the step motor of the present invention, the output shaft rotates by converting the deformation of the strain element, which deforms when a voltage is applied, into rotational motion. Efficiency is improved and responsiveness is improved without causing such losses, and furthermore, it is possible to achieve miniaturization, especially thinning, and furthermore, it is possible to obtain a mechanical self-holding function.

[Brief explanation of the drawing]

1 to 3 are diagrams showing one embodiment of a step motor according to the present invention, in which FIG. 1a is a sectional front view, and FIG.
The figures are a sectional view taken along the line II in Fig. 1a, Fig. 2 is a block diagram showing the drive device, Fig. 3a is a timing chart showing the negative aspect of the drive pulse voltage applied to the piezoelectric element, and Fig. is a timing chart showing another aspect of the drive pulse voltage. FIGS. 4a and 4b are views showing other embodiments of the step motor according to the present invention, with FIG. 4a being a sectional front view and FIG. 4 being a side view. FIGS. 5a and 5b are views showing still another embodiment of the step motor according to the present invention. FIG. 5a is a sectional front view, and FIG. 5B is a side view. 11-----Step motor, 13-------Motor housing, 14-------One output shaft, 15a, 15b115c115ds 15e------
・Deformation generator, 16a, 16b, 16c, 16d
, 16 e...Piezoelectric element (strain element), 17a, 17b, 17c, 17d, 17e...-1111 deformable expander, 26--internal gear, 27-----1 Gear, 2B - One modified rotation conversion means. Patent Applicant Teijin Seiki Co., Ltd. Representative Patent Attorney Agagun Part +7 Figure 2 1-J Figure 3 Figure 4 Doji 406- (b)

Claims (2)

[Claims] (1) In a step motor whose output shaft rotates by a predetermined angle in response to an input pulse signal, a strain element that causes deformation in response to the pulse signal, and a strain element that engages with the strain element and the output shaft, and A step motor comprising: a deformation/rotation conversion means for converting deformation of a strain element into rotational motion and transmitting the rotational motion to the output shaft. (2) The deformation/rotation converting means eccentrically meshes with the external gear provided on the output shaft and the lunar gear, engages with the strain element at its outer periphery, and is pressed by the strain element. C: an internal gear that revolves around the external gear, and the strain element 0;1 is swingably supported on the motor housing. The step motor described in item (1).