JP2004289939A - N-phase permanent magnet type stepping motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an n-phase permanent magnet type stepping motor by which workability at a manufacturing process can be improved without enlarging a size and deteriorating accuracy while improving torque. <P>SOLUTION: A rotor shaft 12 is rotatably supported to a box 10 via bearings 11a, 11b, a rotor 13 of a permanent magnet shape is installed to the external periphery of the rotor shaft 12, and the stator 20 of a claw pole shape is fixed to the inside of a casing 10a so as to surround the external periphery. The stator 20, if it has six phases, is composed of axially arranged six unit stators 21 to 26. The unit stator 21 is constituted by arranging a coil 21c between a pair of yoke elements 21a, 21b. The coil 21c is a weld-formed cylindrical shaped bobbin-less coil that is formed such that a single flat wire is disposed in the widthwise direction and wound to the coil in two rows in the thickness direction so as to be overlapped with each other, and ends E1, E2 of the wire are ended at outermost sides of the rows, respectively. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an n-phase permanent magnet type stepping motor suitable as a drive source for OA equipment such as a printer and a copier for PPC.
[0002]
[Prior art]
FIG. 5 is a sectional view showing the structure of a conventional two-phase inner rotor type permanent magnet type (hereinafter abbreviated as PM type) stepping motor.
This motor has a housing 1 configured by fitting a plate 1b to an open end of a cup-shaped casing 1a.
Bearings 2a and 2b are mounted at the center of the bottom surface of the casing 1a and the center of the plate 1b, respectively, and the rotor shaft 3 is rotatably supported via the bearings.
On the outer periphery of the rotor shaft 3, a cylindrical rotor 4 in which S poles and N poles are alternately magnetized at an equal pitch along the rotation direction is attached, and the outer periphery of the rotor 4 is separated by a predetermined gap. , A claw-pole-shaped stator 5 is fixed inside the casing 1a.
[0003]
The stator 5 is composed of two unit stators 5a and 5b arranged in the axial direction.
The unit stator 5a is configured by winding a circular coil 8 around a bobbin 7 and a yoke 6 formed by combining a pair of annular yoke elements having claw poles formed on the inner circumference so that the claw poles are alternately meshed. And a coil assembly 9 disposed between the pair of yoke elements. The other unit stator 5b is similarly configured.
[0004]
FIGS. 6 and 7 are perspective views respectively showing a winding start and a winding end when the coil 8 is wound around the bobbin 7 of the coil assembly 9.
At the beginning of the winding, as shown in FIG. 6, one end of the coil 8 is entangled with the terminal 7a, and the winding start portion is fixed to the side wall of the bobbin 7 with a tape T so that the coil 8 does not move at the time of winding.
Thereafter, the coil 8 is wound a predetermined number of times, and at the end of winding, as shown in FIG. 7, the other end of the coil 8 is entangled with the terminal 7b, and the tape T is peeled off to complete the coil assembly 9.
[0005]
The inner rotor type PM stepping motor as described above is also disclosed, for example, in FIG.
The motor disclosed in FIG. 1 of Patent Document 1 is a three-phase PM type stepping motor using three unit stators, and the coil of FIG. 1 has been described in paragraph numbers 0003 to 0004 of the present specification. The configuration is the same as that of the conventional example.
[0006]
[Patent Document 1] Japanese Patent Application Laid-Open No. 07-95756
[0007]
[Problems to be solved by the invention]
However, since the conventional PM type stepping motor described above uses a round wire for the coil, the space factor of the copper wire is low, and the bobbin 7 is required, so that the torque is improved without increasing the size. Is difficult.
To increase the torque for the same size, it is necessary to increase the amount of copper. However, to increase the amount of copper in a conventional configuration using a round wire, the thickness of the bobbin 7 must be reduced. However, when the thickness of the bobbin 7 is reduced, the bobbin 7 is deformed by the tension of the coil 8, and particularly in the case of multi-phase, the accuracy of the motor is reduced due to the variation between phases.
[0008]
In the manufacturing process, the tip of the coil must be fixed to the bobbin 7 with the tape T at the beginning of winding of the coil 8, but this operation has to be manually performed, and there is a problem that workability is poor.
[0009]
The present invention solves the above-mentioned problems (problems) of the prior art, and can improve torque without increasing the size and without lowering the accuracy. It is an object of the present invention to provide an n-phase PM type stepping motor capable of improving the above compared with the conventional.
[0010]
[Means for Solving the Problems]
An n-phase PM type stepping motor according to the present invention has an S pole and an N pole alternately arranged along the rotation direction on the outer periphery of a rotor shaft rotatably supported by a pair of bearings provided at both ends of a housing. An n-phase permanent magnet configured by fixing a claw-pole-shaped stator to a housing so that a cylindrical rotor magnetized at an equal pitch is attached to the In the magnet type stepping motor, the stator is composed of n (n is an integer of 1 or more) unit stators arranged in the axial direction, and each unit stator is twice the magnetizing pitch of the rotor. A yoke is formed by combining a pair of annular yoke elements having claw poles formed on the inner circumference at a pitch so that the claw poles alternately mesh with each other, and a coil is arranged between the pair of yoke elements constituting the yoke. And one coil A bobbin-less coil formed by arranging rectangular wires in the width direction, overlapping them in the thickness direction in two rows, winding them in the same direction, and welding the two ends in a cylindrical shape so that the two ends end up on the outermost side of each row. There is a feature.
[0011]
According to the above configuration, by using a rectangular wire for the coil, the space factor can be improved as compared with the case of a round wire, and a bobbin is not required. A larger space can be secured than before, and the amount of copper can be increased to improve torque. In addition, since the flat wire is wound in two rows, and both ends end at the outermost side of the row, it is easy to attach and pull out the lead wire.
[0012]
Further, two ends of the flat wire forming the coil may be formed so as to face outward in the same direction, and a lead wire may be connected to each of these ends to supply power from the outside. In this case, attachment of the lead wire is further facilitated.
By arranging six unit stators in parallel in the axial direction, a 6-phase PM stepping motor can be made compact.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the n-phase permanent magnet type stepping motor of the present invention will be described. FIG. 1A is a longitudinal sectional front view of an inner rotor type 6-phase PM stepping motor according to an embodiment of the present invention, and FIG. 1B is a sectional view taken along line BB 'in FIG. FIG. 2 is a longitudinal sectional front view showing the stator of the motor shown in FIG.
In FIG. 2, power supply lead wires extending from the coils of the unit stators 21 to 26 are not shown.
[0014]
The six-phase PM type stepping motor according to the present embodiment has a casing 10 formed by fitting plates 10b and 10c to both ends of a casing 10a made of a cylindrical magnetic material. Bearings 11a and 11b are mounted at the centers of the plates 10b and 10c, respectively, and the rotor shaft 12 is rotatably supported via the bearings.
[0015]
A cylindrical permanent magnet 13b in which S poles and N poles are alternately magnetized at an equal pitch along the rotation direction is attached to the outer periphery of the rotor shaft 12 via a support 13a also having a back yoke function. The permanent magnet type rotor 13 is formed from the support 13a and the permanent magnet 13b.
A claw-pole-shaped stator 20 is fixed inside the casing 10a so as to surround the outer periphery of the rotor 13 with a predetermined gap therebetween.
[0016]
As shown in FIG. 2, the stator 20 is composed of n (n is an integer of 1 or more) arranged in the axial direction, in this example, six unit stators 21 to 26. These unit stators will be described with reference to FIGS.
FIG. 3 is an exploded view of one unit stator 21.
FIGS. 4A and 4B are explanatory views showing the attachment of the lead wires to the assembled unit stator 21. FIG. 4A is a front view, and FIG. 4B is a side view.
[0017]
As shown in FIG. 3, the unit stator 21 includes a yoke formed by a pair of yoke elements 21a and 21b, and a coil 21c disposed between the pair of yoke elements 21a and 21b. .
Each of the yoke elements 21a and 21b is formed by forming a trapezoidal claw pole CP in a direction perpendicular to the circular disk along the inner periphery of the circular disk. The claw poles CP are arranged at a pitch that is twice the magnetization pitch of the rotor 13.
The yoke elements 21a and 21b are made of a magnetic material, and have an insulating coating on the surface.
[0018]
As shown in FIG. 4, the coil 21c is formed by arranging one rectangular wire in the width direction, overlapping in the thickness direction in two rows, winding in the same direction, and winding the two ends E1, E2 on the outermost side of each row. It is a bobbinless coil formed by welding in a cylindrical shape after winding.
[0019]
The coil 21c is fitted around the claw pole CP of one yoke element 21a as shown by an arrow in FIG. 3, and the other yoke element 21b is combined so that the claw poles of both yoke elements mesh alternately. Fit.
As described above, the unit stator 21 is formed by sandwiching the bobbin-less coil 21c formed of a rectangular wire by the pair of yoke elements 21a and 21b.
[0020]
The space factor can be improved by using a rectangular wire for the coil as described above, and the copper amount is increased by about 20% even in the same arrangement space as compared with the case where a round wire is used as in the conventional example. be able to.
Further, by using a bobbin-less coil, a larger coil space can be ensured than when a conventional bobbin is used.
Therefore, as compared with a conventional bobbin-wound round wire coil, the amount of copper can be increased by about 50% even with the same external size. If the amount of copper is increased, the strength of the magnetic field can be increased, so that the torque can be significantly improved without increasing the size of the motor.
[0021]
Further, as described above, the conventional coil using the bobbin has a problem that the bobbin is deformed by the tension of the coil when winding the copper wire, and the accuracy of the motor is reduced, particularly when the bobbin is thin. However, in the present embodiment, since the coil 21c is welded in advance and fixed in a predetermined shape, the coil 21c does not deform after being incorporated in the yoke element, and does not apply stress to the yoke elements 21a and 21b.
[0022]
As shown in FIG. 4, the two ends E1 and E2 of the rectangular wire forming the coil 21c are formed so as to face outward in the same direction, and lead wires R1 and R2 are connected to these ends E1 and E2, respectively. It is connected.
If the rectangular wire is wound in one row instead of being arranged in two rows in the width direction as in the present embodiment, one end is located inside the coil, so that it is difficult to connect lead wires.
In this regard, in the present embodiment, since both ends E1 and E2 are pulled out in the same direction on the outside, the lead wires R1 and R2 can be easily connected.
In addition, since the terminals E1 and E2 serve as terminals as they are, a step of tying a copper wire to a terminal provided on a bobbin as in the related art is unnecessary, and therefore, there is no need to fix the beginning of winding with tape or the like. In addition, workability at the time of coil winding can be improved.
[0023]
The coil 21c of the unit stator 21 is externally supplied with power through these lead wires R1 and R2. The other unit stators 22 to 26 have the same configuration as the unit stator 21 described above, and lead wires are connected to each of them.
[0024]
In order to drive the stepping motor shown in FIG. 1, the lead wires drawn from the unit stators 21 to 26 are connected to a drive circuit. The drive circuit includes a plurality of switching elements, and sequentially turns them on and off at a predetermined timing, so that a current is sequentially supplied to the coils of each unit stator to excite them, thereby rotating the rotor by one step angle. Can be.
[0025]
In the case of single-phase or two-phase (one or two unit stators, n = 1 or 2), a bipolar drive system in which four switching elements are connected in a bridge to a single coil Use a circuit. In this case, by continuously switching the current in both directions to each coil, a continuously changing magnetic field is formed, thereby rotating the rotor.
[0026]
In the case of three or more phases (n ≧ 3), in addition to the bipolar driving method, a driving circuit of a unipolar driving method using one switching element for a single coil can be used depending on the driving method. In the latter case, the switching elements are sequentially turned on and off, so that a current in the same direction flows through the coils of each unit stator in order to form a continuously changing magnetic field, thereby rotating the rotor.
[0027]
【The invention's effect】
Since the n-phase PM stepping motor according to the first aspect of the present invention is configured and operated as described above, it has the following excellent effects.
(1) By using a rectangular wire for the coil, the space factor can be improved as compared with the case of using a round wire, so that the copper amount can be increased by about 20% even in the same space.
Further, by using a bobbinless coil, the amount of copper can be increased by about 50% even with the same outer shape. As a result, the magnetic field can be increased and the torque can be increased even if the size is the same.
Alternatively, the motor can be made smaller than before without reducing the torque.
(2) Since the coil is formed by welding after winding the rectangular wire, there is no stress on the yoke element, and it is possible to prevent a decrease in accuracy due to deformation of the yoke element.
In particular, in the case of multi-phase, variations between phases can be suppressed and the accuracy of the motor can be maintained high.
(3) Since the bobbin is not required, the number of parts is reduced, and a die for forming the bobbin is not required, so that the manufacturing cost can be reduced.
(4) Since a flat wire is used, the end can serve as a terminal as it is, and there is no need to tie a copper wire to a terminal provided on a bobbin as in the related art, and therefore, a tape or the like is used. There is no need to fix the start of winding, and workability during coil winding can be improved.
[0028]
Also, in the n-phase PM stepping motor according to the second aspect of the present invention, the two ends of the rectangular wire forming the coil are formed so as to face outward in the same direction. In addition to this, there is an effect that a lead wire can be easily connected to the end of the flat wire.
[0029]
Furthermore, the six-phase PM type stepping motor according to the third aspect of the present invention has a configuration in which six unit stators are arranged in the axial direction without the bobbin, in addition to the effect of the first aspect of the present invention. There is an effect that a 6-phase PM type stepping motor, which is highly practical among polyphases, can be configured to be more compact than a conventional one.
[Brief description of the drawings]
FIG. 1A is a longitudinal sectional front view of an inner rotor type 6-phase PM stepping motor according to an embodiment of the present invention, and FIG. 1B is a sectional view taken along line BB ′ of FIG. is there.
FIG. 2 is a vertical sectional front view showing a motor stator according to the embodiment.
FIG. 3 is an exploded view of one unit stator of the motor according to the embodiment.
4A and 4B are explanatory views showing attachment of a lead wire to a unit stator of the motor according to the present embodiment, wherein FIG. 4A is a front view and FIG. 4B is a side view.
FIG. 5 is a vertical sectional front view of a conventional two-phase PM stepping motor.
6 is a partial perspective view showing a state of starting winding of a coil constituting a unit stator of the motor of FIG. 5;
FIG. 7 is a partial perspective view showing a state where winding of a coil constituting a unit stator of the motor of FIG. 5 is completed.
[Explanation of symbols]
10: Casing 10a: Casing 10b, 10c: Plate 11a, 11b: Bearing 12: Rotor shaft 13: Rotor 13a: Support 13b: Permanent magnet 20: Stators 21 to 26: Unit stator 21a, 21b: Yoke Element CP: claw pole 21c: coil E1, E2: terminal R1, R2: lead wire

Claims (3)

Cylindrical rotation in which S-poles and N-poles are alternately magnetized at equal pitches along the rotation direction on the outer periphery of a rotor shaft rotatably supported by a pair of bearings provided at both ends of the housing. A n-phase permanent magnet type stepping motor configured by fixing a claw-pole-shaped stator to the housing so as to surround the rotor with a predetermined gap surrounding the rotor.
The stator is composed of n (n is an integer of 1 or more) unit stators arranged in the axial direction, and each of the unit stators has an inner pitch of twice the magnetization pitch of the rotor. A pair of annular yoke elements having a claw pole formed on the periphery are combined so that the claw poles alternately mesh with each other to form a yoke, and a coil is arranged between the pair of yoke elements forming the yoke, The coil is formed by arranging one rectangular wire in the width direction, overlapping in the thickness direction in two rows, winding in the same direction, winding in the same direction, and welding the two ends to a cylindrical shape such that the two ends end in the outermost of each row. An n-phase permanent magnet type stepping motor characterized in that it is a formed bobbinless coil. The two ends of the rectangular wire constituting the coil are formed so as to face outward in the same direction, and a lead wire is connected to each of the two ends to supply power from outside. The n-phase permanent magnet type stepping motor according to claim 1. The six-phase permanent magnet type stepping motor according to claim 1 or 2, wherein the six unit stators are arranged in parallel in the axial direction.

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