JPH0638715B2 - Stepping motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stepping motor in which a rotor is rotated by a constant angle.

As a conventional stepping motor, for example, a plurality of iron pieces are provided on the outer circumference of the rotor with a constant pitch, and a plurality of magnetic poles are arranged on the inner circumference of the stator so that the deviation with respect to the iron piece of the rotor is sequentially increased by a certain angle. It is known that the rotor is rotated by a constant angle by sequentially exciting each magnetic pole by attracting iron pieces, but in this way magnetic force attracts the iron pieces of the rotor. In a stepping motor that rotates the rotor by rotating the rotor, the magnetic pole and the iron piece do not mechanically engage with each other.Therefore, when the rotor is rotated, the magnetic pole and the iron piece are aligned at a position that resists the inertial force of the rotor. It was difficult to stop it surely, and there was a defect that lacked certainty.

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 having a novel structure that can reliably rotate a rotor at a constant angle.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIGS. 1 and 2, 1 has a central hole 2 and has a star-shaped cross section in which eight bulges 3 are radially provided at intervals of 45 degrees over the entire length of the outer peripheral surface. A cylindrical body, which is attached to a pair of legs 5 and 5 in a horizontal posture, and in the center hole 2 of the body 1, a cylindrical rotor 6 having an elliptical outer peripheral surface is provided at one end. The protruding output shaft 7 is protruded to the outside of the body 1 and is concentrically fitted to the bearing 1.
And 9 are rotatably supported about a horizontal axis via the inner and outer peripheral surfaces of the rotor 6 and the inner ring 11 fixed to the rotor 6 and a flexible synthetic resin. A bearing 10 including a large number of balls 13 is fitted between the outer ring 12 and the outer ring 12, and a ring body 15 made of a flexible metal thin plate is fitted on the outer circumference of the bearing 10 over the entire length of the rotor 6. Has been done.

On the inner peripheral surface of each bulging portion 3 of the body 1, a guide groove 17 facing the center of rotation of the rotor 6 is bored over the entire length,
In each guide groove 17, a pressing body 18 engageable with the outer peripheral surface of the ring body 15 is provided with sliding plates 19 and 20 having a small friction coefficient.
Through which the rotor 6 is freely moved back and forth in the direction of the center of rotation, and a pair of extendable actuators 30, 30 for driving the pressing bodies 18 are mounted on the lower surface of each pressing body 18.
Of the pressing body 18, the supporting portions 22, 22 are provided so as to obliquely face each other, and the tapered supporting holes 23, 2 are provided on the corresponding surfaces.
3 is provided, and support portions 25, 25 are provided at both ends of a fixed body 24 fixed to the bottom of the guide groove 17 so that the support portions 25, 25 face diagonally opposite to the support portions 22, 22. The corresponding supporting surfaces 26, 26 are formed in the corresponding surfaces, and the pair of actuators 30, 30 are
The tapered stator 41 is fitted in the support hole 26 of the fixed body 24, and the similarly tapered actuator 48 is fitted in the support hole 23 of the pressing body 18, and the pressing bodies 18 are provided at both ends thereof. A pair of rings 28, which are inscribed in the pressing portion 27 formed on the 18 and are excellent in elastic force for returning the pressing body 18,
28 is fitted.

Approximately, the actuator 30 uses a laminated piezoelectric ceramic developed by NEC Corporation, and the piezoelectric ceramic 31 is composed of lead magnesium niobate and titanic acid as shown in FIG. Lead binary solid solution ceramic {(1-X) pb (Mg1 / 3Nb2 / 3) O ₃ −
PbTiO ₃ } of which the X is close to 0.35 and the ceramic plate 32 and the internal electrode plate 33 are alternately laminated and integrated, and the sintered element is cut into a desired shape and size. The inner electrode plates 33 exposed on the upper and lower sides are electrically insulated by an insulating material 34 in every other layer, and the outer electrode plates 35 and 36 are attached to the upper and lower both sides to form the inner electrode plates 33 in every other layer. The structure is electrically connected to the external electrode plates 35 and 36. Even if the applied voltage is low, a certain amount of strain is generated, and even if the voltage is repeatedly applied, there is no deterioration at all, and the response speed is high. Is extremely fast.

As shown in FIGS. 3 and 4, the actuator 30 of this embodiment has the stator 41 at one end and the opening 4 at the other end.
2 is formed on the inner peripheral surface of the metal square tube 40 formed with 2 and made of a synthetic resin liner 43 such as Teflon having a small friction coefficient and an excellent insulating property. A plurality of them are stacked and fitted in the liner 43 freely through an insulating plate 44 made of ceramic, and the electrode plates of the same polarity among the external electrode plates 35 and 36 of the individual piezoelectric ceramics 31 are electrically connected. Connect at 50, opening 4
The lead wires 45 and 46 connected to the two external electrode plates 35 and 36 on the second side are guided to the outside through the insertion holes 51 formed in the square tube 40, and the actuator 48 is provided in the opening 42 of the square tube 40. Has a structure in which the piezoelectric ceramics 31 are slidably fitted and coupled to the piezoelectric ceramics 31 via an insulating plate 49 made of ceramics. By energizing the actuator 30 and applying a voltage to each piezoelectric ceramics 31, The piezoelectric ceramic 31 extends in the stacking direction, and the sum of the strains causes the actuator 4 to move.
When 8 is pushed to move forward and cut off the energization, the piezoelectric ceramic 31 contracts and the actuator 48 retracts into the rectangular tube 40. By applying a high frequency pulse voltage to the actuator 30, The actuator 48 reciprocates at a high speed.

The displacement position of the actuator 48 of the actuator 30 is relatively small, and it is difficult to obtain the moving stroke required for the pressing body 18 only by the displacement amount, but in the present embodiment, the actuator 30 The stator 41 is fitted in the support hole 26 of the fixed body 24, and the actuator 48 is fitted in the support hole 23 of the pressing body 18, respectively, and is supported in an oblique posture with respect to the advancing / retreating direction of the pressing body 18, and the pressing body 18 is also supported. Is a sliding plate 19, 1
Since the rotor 6 can only be moved forward and backward in the direction of the rotation center of the rotor 6 when the actuator 9 is extended, the extension of the guide groove 17 in the longitudinal direction is restricted, so that the actuator 48 moves the rotation center of the rotor 6. By acting so as to escape in the direction, a slight displacement amount of the actuator 48 is amplified to push up the pressing body 18 by a necessary stroke.

This will be described with reference to FIG. 5, in which the actuator 30 is tilted by an angle θ before energization and is between OY1, and when the actuator 48 advances due to energization, the actuator 48 rotates about O to rotate OY2. If the operator 48 is located between them, the advancing change position of the actuator 48 is Δx, the pushing-up displacement amount of the pressing body 18 is Δy, and
When the distortion rate of the actuator 30 is ρ and the ratio of Δx and Δy is obtained, Then, when ρ = 8 × 10 ⁻⁴ and θ = 1 °, Δy / Δx = 32.74, and the pushing displacement 18 of the pressing body 18 is Displacement amount of child 48 △ x
32.74 times that.

Incidentally, in this embodiment, θ = 2 ° is set,
When Δy / Δx at this time is calculated from the equation (1), 22.
74.

As described above, in this embodiment, the displacement amount of the actuator 48 is amplified, and the tip of the pressing body 18 presses the ring body 15 through the bearing 10 against the shortest diameter portion of the outer peripheral surface of the rotor 6. It is designed to move forward to a position where it can.

Further, in the present embodiment, since the actuators 30 are installed two by two with their directions reversed, a large driving force can be obtained and the pressing body 18 can be driven straight without tilting with respect to its advancing / retreating direction. It's ready.

Next, the operation of the present embodiment is shown in FIG. 2 and the sixth operation principle.
It will be described with reference to the drawings.

As shown in FIGS. 2 and 6 (a), the pressing bodies 18 at the positions IV and VIII facing each other are moved forward so that the minor diameter portion of the rotor 6 is aligned with the positions IV and VIII, and the major diameter portion is In the state of matching the positions II and VI, which are shifted by 90 degrees,
When the actuators 30 at the positions I and V, which are deviated from the positions IV and VIII by 45 degrees in the counterclockwise direction, are energized and the actuators 30 at the positions IV and VIII are de-energized, the pressing bodies 18 at the positions I and V cause the elastic ring 28. While pushing forward, the pushing bodies 18 at the positions IV and VIII are retracted by the elastic force of the elastic ring 28, and the pushing bodies 18 at the positions I and V move forward from the short diameter portion of the outer peripheral surface of the rotor 6. The part displaced by 45 degrees in the counterclockwise direction is the ring body 15 and the bearing 1.
0, the tangent line of this portion is inclined clockwise with respect to the direction perpendicular to the center of rotation, and a tangential component force that imparts a counterclockwise rotational force to the rotor 6 is generated. Thus, the rotor 6 slides on the inner circumference of the ring body 15 and rotates counterclockwise, and as shown in FIG. 6 (b), the rotor 6 rotates 45 degrees, and its minor axis portion is located at positions I and V. To stop at a point where the tangential component force becomes O, and in this state, the pressing bodies 18 at the positions II and VI adjacent thereto are deviated from the minor axis portion of the rotor 6 by 45 degrees in the counterclockwise direction. ,
Subsequently, when the actuator 30 at the positions II and VI is energized to move the pressing body 18 forward, and the actuator 30 at the positions I and V is de-energized to retract the pressing body 18, the same operation as described above is performed. Therefore, as shown in FIG. 6 (c), the rotor 6 has a minor axis portion at position II.
And VI until they are aligned with VI and VI, and then the actuators 30 at positions III and VII adjacent thereto are energized to move the pressing body 18 forward, and at positions II and II.
When the actuator body 30 of VI is de-energized and the pressing body 18 is retracted, as shown in FIG.
Further rotates 45 degrees in the same direction.

Thus, positions I and V, positions II and VI, which face each other,
By repeating energization and interruption of electricity to the actuators 30 at positions III and VII and positions IV and VIII, the rotor 6 can be rotated counterclockwise by 45 degrees, and the minor axis portion of the rotor 6 has a predetermined diameter. When the actuator 30 is kept energized when it is aligned with the pair of positions, the rotor 6
Can be held stationary at that position.

Further, the pressing body 18 is driven by an actuator 30 using a laminated piezoelectric ceramic. Since the actuator 30 is excellent in high-speed response, a high-frequency pulse voltage whose phase is sequentially shifted is applied. By doing so, the rotor 6 can be smoothly and continuously rotated.

Incidentally, when the pressing body 18 is sequentially driven in the clockwise direction, contrary to the above embodiment, the rotor 6 can be rotated in the clockwise direction by 45 degrees.

Further, as in the above embodiment, in order to rotate the rotor 6 in one direction and the rotor 6 has an elliptical shape, it is necessary to sequentially press the portions where the tangents of the outer peripheral surface of the rotor 3 are inclined in the same direction. Therefore, for this purpose, it is necessary to install three or more pressing bodies 18. As in the above-described embodiment, if the number of the pressing bodies 18 is an even number and the rotor 6 is sandwiched by the two pressing bodies 18 that are symmetrical with respect to the center of rotation, the driving force of the rotor 6 is increased. It is possible to obtain a large value and an advantage that no bending moment acts on the rotor 6 when the rotor 6 is pressed is obtained.

Further, in the above embodiment, the outer peripheral surface of the rotor 6 has an elliptical shape, but this is not an elliptical shape that is geometrically strict, but an oblong shape obtained by flattening a perfect circle or a vertex of a triangle. Like a rice ball shape with a circular arc shape, the part near the center of rotation and the part far from the center of rotation are connected by a curve in which the angle between the tangent at the intersection with the straight line facing the center of rotation and the straight line changes continuously. The non-circular shape may be replaced with, for example, when the rotor 6 is a rice ball shape, the rotor 6 is
Although the rotor 6 forms a symmetric shape that coincides with the original shape by rotating the rotor 6 degrees, in this case, since the angle at which the rotor 6 can be rotated at one time is less than 60 degrees, it is difficult to rotate the rotor 6 in one direction. Similarly, three or more pressing bodies 18 are required.

As described in detail with reference to the above embodiments, in the stepping motor of the present invention, the stepping motor of the present invention has a tangential line at a point of intersection between a portion close to the rotation center and a portion far from the rotation center with a straight line facing the rotation center. A rotor (6) having a non-circular outer peripheral surface connected by a curve whose angle formed by the straight line changes continuously, and the rotor (6) is rotatably supported in the cylindrical body (1), and In each of three or more guide grooves (17) formed on the circumferential surface at intervals in the circumferential direction, a pressing body (18) capable of advancing and retracting the rotor (6) in the direction of the rotation center is provided. ,
An actuator (30) for advancing and retracting each of the pressing bodies (18) by expanding and contracting by using a laminated piezoelectric ceramic that generates a strain by applying a voltage as a driving source is provided in the back of each of the guide grooves (11). Provided and the pressing body (18)
And a controller for applying a voltage to the actuator (30) so as to sequentially press the portions where the tangents of the curved portion are inclined in the same direction when the rotor (6) moves forward. That is, the pressing body at the position corresponding to the portion where the tangent line in the curved portion of the outer peripheral surface of the rotor inclines in the same direction is sequentially advanced, and the pressing body immediately pushes that portion to rotate the rotor. Therefore, the rotor can be surely rotated in one direction at a constant angle, and the rotor is mechanically engaged in a state where the pressing body presses a portion of the outer peripheral surface of the rotor near the rotation center. Since the rotation is stopped, the rotor can be reliably stopped at a predetermined position, and each pressing body is driven by an actuator using a laminated piezoelectric ceramic with excellent high-speed response. Since the, it can be smoothly continuous rotation Yotsute, the rotor in applying successive phase-shifted high frequency pulse voltage respectively in the actuator, further, an effect that does not cause dielectric failure or interference.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of an embodiment of a stepping motor of the present invention, FIG. 2 is a partially cutaway left side view thereof, FIG. 3 is a sectional view of an actuator, and FIG. 4 shows details of a piezoelectric ceramic. 3 is a partially enlarged view of FIG. 3, FIG. 5 is an explanatory view of displacement amplification of an actuator, and FIG. 6 is an operation principle diagram of a stepping motor. 1: Body, 6: Rotor, 18: Pressing body, 30: Actuator, 31: Piezoelectric ceramic

Claims (1)

[Claims] 1. A non-circular outer peripheral surface in which a portion close to the center of rotation and a portion far from the center of rotation are connected by a curve whose angle between the tangent line at the intersection with a straight line facing the center of rotation and the straight line changes continuously. The rotor (6) is rotatably supported in the tubular body (1), and three or more guide grooves (17) are formed on the inner peripheral surface of the body (1) at circumferential intervals. Each of them is provided with a pressing body (18) capable of advancing and retracting in the direction of the rotation center of the rotor (6), and at the back of each of the guide grooves (11), a laminated piezoelectric element that generates a strain by applying a voltage. An actuator (30) for advancing and retracting each of the pressing bodies (18) by expanding and contracting by using a ceramic as a driving source is provided, and the outer peripheral surface of the rotor (6) is advanced when the pressing bodies (18) advance. The part where the tangent line in the curved part is inclined in the same direction Then scan Tetsu ping motor, characterized in that a control unit for applying a voltage to the actuator (30) so as to press.