JPH0334306B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stepping motor that rotates a rotor intermittently by a constant angle.

Examples of conventional stepping motors include:
A plurality of iron pieces are provided on the outer periphery of the rotor at a constant pitch, and a plurality of magnetic poles are arranged on the inner periphery of the stator so that the deviation from the rotor iron pieces increases by a constant angle, and each magnetic pole is sequentially energized. It is known that the rotor is rotated by a fixed angle by suctioning iron pieces.
In a stepping motor that uses magnetic force to attract the iron pieces of the rotor to rotate the rotor, the magnetic poles and the iron pieces do not mechanically engage, as they do when teeth mesh with each other, so the rotor cannot be rotated. When the magnetic pole is rotated, it is difficult to resist the inertial force and reliably stop the magnetic pole and the iron piece at a position where they are aligned, resulting in a problem of lack of positive action.

The present invention has been completed in view of the above points, and an object of the present invention is to provide a stepping motor with a novel structure that can reliably rotate a rotor by a constant angle.

Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

1 is a cylindrical body having a center hole 2 and a star-shaped cross section with eight bulges 3 protruding radially at intervals of 45 degrees over the entire length of the outer circumferential surface; A cylindrical rotor 6 with an output shaft 7 protruding from one end is fitted concentrically into the center hole 2 of the body 1 through bearings 8 and 9. The rotor 6 is supported to rotate freely around a horizontal axis, and a large number of isosceles triangular outer peripheral teeth 10 are continuously formed at a constant pitch on the outer peripheral surface of the rotor 6.

A guide groove 11 facing the center of the rotor 6 is formed on the inner circumferential surface of each bulging portion 3 of the body 1 over the entire length. A pressing body 13 formed with a plurality of feed teeth 14 having the same pitch as the outer circumferential teeth 10 is fitted so as to freely advance and retreat in the direction of the center of the rotor 6 via sliding plates 16 and 17 having a small coefficient of friction. The positional relationship of these feed teeth 14 with respect to the outer tooth 10 is based on the two feed teeth 14 facing each other that align with the outer tooth 10, and the three feed teeth 14 between them are aligned with the outer tooth 10. The phase shift for
It is designed to increase sequentially in the counterclockwise direction by 4 pitches, and as shown in FIG. The teeth 14b are out of phase with the outer peripheral teeth 10 by 1/4 pitch, and the feed teeth 14c are positioned facing each other.
The feed teeth 14d are out of phase with the outer teeth 10 by 2/4 pitch, and the feed teeth 14d are out of phase with the outer teeth 10 by 3/4 pitch.

On the lower surface of each pressing body 13, a pair of extendable and contractible actuators 30 for driving the pressing body 13,
30 are installed in diagonal positions in opposite directions, and support parts 19, 19 are provided on both ends of the pressing body 13 so as to diagonally face each other, and tapered support holes 20, 20 are provided on the respective corresponding surfaces. A fixed body 21 is fixed to the bottom of the guide groove 11.
Support parts 22, 22 are provided at both ends of the support part 1.
The pair of actuators 3 are protruded so as to face diagonally oppositely to the actuators 9 and 19, and have tapered support holes 23 and 23 bored in their respective corresponding surfaces.
0,30, the tapered stator 41 is the fixed body 21
A similarly tapered actuator 48 is fitted into the support hole 20 of the pressing body 13 , and a pressing part 25 formed in each pressing body 13 has an inner part at both ends of each pressing body 13 . Pressing body 13 so as to be in contact with each other
A pair of rings 26, 2 with excellent elasticity for the return of
6 is fitted.

The actuator 30 uses a laminated piezoelectric ceramic recently developed by NEC Corporation.
1, as shown in Fig. 4, is a binary solid solution ceramic of magnesium-lead niobate and lead titanate {(1-X)Pb(Mg _1/3 Nb _2/3 )O ₃ -PbTiO ₃ }. Ceramic board 3 made of a material whose X is close to 0.35
2 and internal electrode plates 33 are alternately laminated and integrated and sintered and cut into a desired shape and size, and the internal electrode plates 33 exposed on the entire circumference are coated with insulating material 34 every other layer on both upper and lower sides. The structure is such that external electrode plates 35 and 36 are attached to both the upper and lower sides, and the internal electrode plates 33 are electrically connected to the external electrode plates 35 and 36 every other layer. Even if the voltage is low, it will generate more than a certain amount of distortion, and even if the voltage is repeatedly applied, it will not deteriorate at all.
Moreover, it has a feature of extremely fast response speed.

As shown in FIGS. 3 and 4, the actuator 30 of this embodiment has the stator 41 at one end,
A liner 43 made of synthetic resin such as Teflon, which has a small coefficient of friction and excellent insulation properties, is formed on the inner peripheral surface of a rectangular metal tube 40 with an opening 42 formed at the other end, and is formed into a rectangular shape. A large number of piezoelectric semi-conductors 31 are stacked one on top of the other, and are slidably fitted into the liner 43 via a ceramic insulating plate 44, so that the external electrode plates 35 and 36 of the individual piezoelectric ceramics 31 have the same polarity. electrode plates are connected with electric wires 50, and lead wires 45 and 46 connected to both external electrode plates 35 and 36 on the opening 42 side are led to the outside through an insertion hole 51 formed in the rectangular tube 40,
The actuator 48 described above is slidably fitted into the opening 42 of the square tube 40, and an insulating plate 49 made of ceramic is inserted.
When the actuator 30 is energized and a voltage is applied to each piezoelectric ceramic 31, each piezoelectric ceramic 31 stretches in the overlapping direction, and is activated by the sum of the strain. When the actuator 48 is pushed forward and the current is cut off, the piezoelectric ceramic 31 contracts and the actuator 4
8 is designed to retreat into the rectangular tube 40, and by applying a high frequency pulse voltage to this actuator 30, the actuator 48 reciprocates at high speed.

Note that the amount of displacement of the actuator 48 of this actuator 30 is relatively small, and it is difficult to obtain the movement stroke required for the pressing body 13 with only that amount of displacement.
0, the stator 41 is inserted into the support hole 23 of the fixed body 21.
Then, the actuators 48 are fitted into the support holes 20 of the pressing body 13, so that the pressing body 13 is supported in an oblique posture with respect to the forward and backward direction of the pressing body 13, and the pressing body 13 is attached to the sliding plates 16, 1.
Since the actuator 3 can only move forward and backward toward the center of the rotor 6 using the actuator 6 as a guide,
0 expands, the lengthwise expansion of the guide groove 11 is restricted and the actuator 48 acts to escape toward the center of the rotor 6, thereby amplifying the slight displacement of the actuator 48. The pressing body 13 is pushed up by a necessary stroke.

This will be explained with reference to FIG. 5. Before energization, the actuator 30 is tilted by an angle θ and is located between _OY1 , and when the actuator 48 is advanced by energization, it rotates around O. Assuming that the actuator 48 is located between OY ₂ and the forward displacement amount of the actuator 48 is △x, the push-up displacement amount of the pressing body 13 is Δy, and the strain rate of the actuator 30 is ρ, calculate the ratio of △x and △y. Then, the relational expression Δy/Δx=√(1+ρ) ² −cos ² θ−sinθ/ρ (1) is obtained, where ρ=8×10 ^-4 , θ=
When the angle is 1°, Δy/Δx=32.74, and the upward displacement amount Δy of the pressing body 13 is 32.74 times the advancing displacement amount Δx of the actuator 48.

Incidentally, in this embodiment, θ=2°, and Δy/Δx at this time is found to be 22.74 from equation (1).

As can be understood from the above, in this embodiment, the amount of displacement of the actuator 48 is amplified, and the pressing body 13 is
is advanced to a position where its feed teeth 14 mesh with the outer teeth 10 of the rotor 6.

Further, in this embodiment, the actuator 30 is
Since two devices are installed with the directions opposite to each other, a large driving force can be obtained, and the pressing body 1
3 can be driven straight without tilting in the direction of movement.

Next, the operation of this embodiment will be explained.

As shown in FIG. 2, in a state in which the pressing bodies 13 are moved forward in positions facing each other and the feed dog 14a is engaged with the outer tooth 10, the feed dog 14b is at a 1/4 pitch with respect to the outer tooth 10. Actuator 3 in adjacent positions and out of phase
When the actuator 30 of Position and is de-energized, the pressing body 13 of Position and moves forward while pressing the elastic ring 26, and the pressing body 13 of Position and moves backward by the elasticity of the elastic ring 26. However, as described above, the position of the feed dog 14b is 1/4 pitch out of phase with respect to the outer tooth 10, and the tip of the feed dog 14b is on the front side of the outer tooth 10 in the clockwise direction in FIG. Since the feed dog 14b corresponds to the slope of The rotor 6 is rotated counterclockwise, and when the tip of the feed dog 14b touches the root of the outer tooth 10, the rotor 6 rotates exactly 1/4 pitch,
In this state, the feed dog 14c at the adjacent position is out of phase with the outer tooth 10 by 1/4 pitch, so the actuator 30 at the adjacent position is subsequently energized to advance the feed dog 14c. together with the position and actuator 30
By cutting off the energization and retracting the feed dog 14b, the rotor 6 rotates 1/4 pitch in the same direction again, and the actuator 30 at the adjacent position is energized to advance the feed dog 14d. When the feed dog 14c is moved backward by cutting off the power supply to the actuator 30 at the position , the rotor 6
rotates another 1/4 pitch.

In this way, by repeating the energization and de-energization of the actuator 30 in the mutually facing positions, positions, positions, and positions in a constant cycle, the rotor 3 is moved 1/4 in the counterclockwise direction.
The rotor 6 can be rotated intermittently in pitches, and when a predetermined pair of feed teeth 14 engage with the outer tooth 10, if the actuator 30 is kept energized, the rotor 6 can be stopped at an arbitrary rotation angle. .

Further, the pressing body 13 is driven by an actuator 30 using a laminated piezoelectric semi-conductor, and since these actuators 30 have excellent high-speed response, they can sequentially apply high-frequency pulse voltages out of phase. By applying the power, the rotor 6 can be smoothly and continuously rotated.

In the above embodiment, the outer teeth 10 are in the form of an isosceles triangle, and slopes are formed on both sides. Therefore, when the pressing body 13 is sequentially driven clockwise, contrary to the above embodiment, the rotor 6 1/4 clockwise
It can be rotated in pitch increments, but
When the rotor 6 only needs to be rotated in one direction, the outer peripheral teeth 10 may have a sawtooth shape with a slope on only one side.

Further, in the above embodiment, the feed teeth 14 having the same phase with respect to the outer tooth 10 are arranged two by two so as to sandwich the rotor 6, thereby increasing the driving force and bending the rotor 6 when the outer tooth 10 is pushed. Although it is designed so that no moment acts, instead of such a configuration, the feed teeth 14 may be provided around the entire circumference, the phase of which is shifted by a certain angle in one direction.

Further, the number of feed dogs 14 can be two or more, and for example, when two feed dogs 14 are installed, the outer peripheral teeth 10 are made serrated so that the tooth tip of the feed dog 14 that is about to move forward is It is only necessary to install the device so that it does not come into contact with the tips of the outer peripheral teeth 10.

As specifically explained in the above embodiment,
The stepping motor of the present invention includes a cylindrical rotor 6, which is rotatably supported in a center hole 2 of a cylindrical body 1, and a cylindrical rotor 6 having a large number of peripheral teeth 10 having an inclined surface on one or both sides is provided on the outer peripheral surface. , the outer circumferential tooth is provided in each of a plurality of guide grooves 11 formed on the inner circumferential surface of the body 1 at intervals in the circumferential direction, and sliding plates 16 and 17 having a small friction coefficient are attached to both side surfaces and both end surfaces. A pressing body 13 that has a feed dog 14 that engages with the slope of the rotor 6 and is freely movable toward the center of the rotor 6;
Rings 26 made of an elastic body are attached to both ends of the pressing body 13 so that the feeding teeth 14 are fitted with different phases to the outer peripheral teeth 10 and urging the pressing body 13 toward the back of the guide groove 11. A laminated piezoelectric ceramic 31 that causes distortion when a voltage is applied.
An actuator 30 that expands and retracts using a drive source is fitted into the inner part of each guide groove 11 with the actuator 30 facing diagonally with respect to the advancing and retreating direction of the pressing body 13.
The actuator 48 formed at the tip of the pressing body 13
The actuator 30 expands and contracts to sequentially move the pressing bodies 13 forward and backward, and when the pressing bodies 13 move forward, the feed dog 14 presses the slope of the outer tooth 10, thereby moving the rotor. 6
The gist of this system is to rotate the rotor by a constant angle, and the pressing bodies that are out of phase with the teeth of the rotor are sequentially advanced, and the engaging part of the pressing bodies directly engages the teeth of the rotor. Since the rotor is rotated by pressing the slope of the rotor, the rotor can be rotated reliably by a certain angle, and the rotation of the rotor can be stopped by mechanical engagement between the teeth of the rotor and the engaging part of the pressing body. This makes it possible to reliably stop the rotor at any rotation angle, and also to prevent the rotor from rotating when an external force is applied to it. Since each pressing body is driven by an actuator using a shaped piezoelectric ceramic, by sequentially applying out-of-phase high-frequency pulse voltages to each actuator,
The rotor can be rotated smoothly and continuously, and furthermore, there is an effect that no induction interference or radio wave interference occurs.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway front view of one embodiment of the stepping motor of the present invention, Fig. 2 is a partially cutaway left side view thereof, Fig. 3 is a sectional view of the actuator, and Fig. 4 shows details of the piezoelectric ceramic. FIG. 3 is a partially enlarged view of FIG. 3, and FIG. 5 is an explanatory diagram of displacement amplification of the actuator. 1: Body, 6: Rotor, 10: Peripheral tooth, 1
3: Pressing body, 14; Feed dog, 30; Actuator, 31: Piezoelectric ceramic, 40: Square tube, 41:
Stator, 43: liner, 48: actuator.

Claims (1)

[Claims] 1. A cylindrical rotor 6 having a large number of peripheral teeth 10 with slopes on one side or both sides is rotatably supported in the center hole 2 of a cylindrical body 1, and Sliding plates 1 with a small coefficient of friction are formed at intervals in the circumferential direction and have a small friction coefficient on both side and end surfaces.
A feed dog 14 that engages with the slope of the outer tooth 10 is provided in each of the plurality of guide grooves 11 to which the feed teeth 6 and 17 are attached.
A pressing body 13 having a structure and capable of freely moving forward and backward in the direction of the center of the rotor 6 is fitted with different phases of the feed dog 14 relative to the outer tooth 10, and the pressing body 13 is inserted into the guide groove 11. A ring 26 made of an elastic body is attached to both ends of the pressing body 13, and an actuator 30, which expands and contracts using a laminated piezoelectric ceramic 31 that generates distortion when a voltage is applied as a driving source, is attached to the pressing body 13. The actuator 48 formed at the tip of the actuator 30 is fitted into the inner part of each of the guide grooves 11 obliquely with respect to the forward and backward direction of the actuator 30 , and the actuator 48 formed at the tip of the actuator 30 is engaged with the pressing body 13 . The rotor 6 is rotated by a constant angle by sequentially advancing and retracting each pressing body 13 and pressing the slope of the outer tooth 10 with the feed dog 14 when the pressing body 13 moves forward. Features a stepping motor.