JP2004104921A - High response stepping motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high response stepping motor capable of exhibiting high responsiveness by a simple structure while keeping stabilized characteristics. <P>SOLUTION: The high response stepping motor is configured such that a stator unit 10A is constituted by sandwiching a coil inside two stator yokes 11, 13 in which pole teeth 12 formed by bending soft magnetic steel plates and arranged along the internal periphery of the motor are engaged with each other. The motor comprises a stator assembly in which the two stator units 10A are fixed back to back, and a rotor 20 having a field rotor magnet 24 at its external periphery and arranged to the stator assembly so as to oppose the pole teeth 12. The total length La of an engaging part 13b where the two stator yokes 11, 13 are engaged is made to be double or less of the total of root length Lb of the pole teeth of the stator yokes 11, 13. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a stepping motor, and more particularly to a high-speed response stepping motor having a simple structure capable of high-speed response.
[0002]
[Prior art]
In recent years, the use range of PM type stepping motors as actuators for various devices has been steadily expanding due to its good controllability. However, with the high performance of various devices, PM type stepping motors also require high-speed response. Have been.
[0003]
FIG. 6 shows a perspective view of a conventional PM type stepping motor, FIG. 6 (A) is an exploded perspective view of the conventional PM type stepping motor, and FIG. 6 (B) shows a conventional PM type stepping motor. FIG. 4 is an exploded perspective view of a stator used.
[0004]
As shown in FIG. 6A, a conventional PM type stepping motor includes a first stator unit 30A and a second stator unit 30B fixed to each other back to back, and a first stator unit 30A and a second stator unit. And a rotor 40 rotatably disposed on the unit 30B and having a field rotor magnet 44 on its outer periphery.
[0005]
As shown in FIG. 6B, the first stator unit 30A includes an upper stator yoke 31, a lower stator yoke 33, and a coil part 35 for excitation, which are vertically combined. The upper stator yoke 31 and the lower stator yoke 33 are formed with a plurality of pole teeth 32 by being pulled out and raised along the inner circumferential edge. The second stator unit 30B fixed to the first stator unit 30A back to back has the same configuration.
[0006]
In any of the stator yokes, the pole teeth of the number corresponding to the number of steps of one rotation required for the stepping motor are arranged at regular intervals, and the first stator unit 30A and the second stator unit 30B are arranged. The upper and lower stator yokes 31 and 33 are arranged such that pole teeth 32 that are vertically opposed to each other are shifted from each other by an electrical angle of 180 °. Further, the pole teeth 32 of the first stator unit 30A and the pole teeth 32 of the second stator unit 30B are arranged so as to be shifted from each other by an electrical angle of 90 °. The rotor 40 can be driven to rotate by the stator unit 30B.
[0007]
The movement of the PM type stepping motor is such that the pole teeth 32 of the upper stator yoke 31 and the lower stator yoke 33 are excited to the N pole and the S pole by the energization of the coil portion 35, and the rotor magnet 44 for the field responds to the excitation. Reference numeral 40 rotates around the rotation shaft 41, and the output is the value of the magnetic pole integrated over the entire circumference. In the magnetic path of the first stator unit 30A and the second stator unit 30B, the magnetic flux generated by the energization of the coil portion 35 is output from the N pole of one of the pole teeth 32 of the upper stator yoke 31 or the lower stator yoke 33. The opposite side which enters the S pole of the field rotor magnet 44, enters the S pole of the pole teeth 32 of the stator yoke on the opposite side from the N pole of the field rotor magnet 44, and goes to the outer periphery of the stator yoke and is fitted. Is the route returning to the stator.
[0008]
Here, the place where the magnetic flux is concentrated most, that is, the place where the so-called magnetic flux density becomes the highest, is the root of the pole teeth 32 of the upper stator yoke 31 and the lower stator yoke 33, and the other part has a large cross-sectional area of the magnetic path and the magnetic flux density. It is lower. Basically, the amount of magnetic flux in the magnetic path is limited at the position (location) where the magnetic flux density is the highest, so the other parts exist as inductance and are unnecessary only by increasing iron loss, An extra portion magnetically exists as the upper structure and as a magnetic shield.
[0009]
Therefore, in the conventional PM stepping motor, the fitting amount between the upper stator yoke 31 and the lower stator yoke 33 is increased, and the inductance is increased. As a result, the electric time constant becomes large, and in high-frequency driving for high-speed response, it takes time for the current to rise, so that sufficient current cannot be flowed within the specified time, and torque cannot be generated enough to continue rotation and stop. And could not meet the demand for high-speed response.
[0010]
The upper stator yoke 31 and the lower stator yoke 33 are fitted to each other by an inner surface 31a of the upper stator yoke 31 formed in one cup shape and an outer peripheral surface 33a of the lower stator yoke 33 formed in the other annular shape. However, since very high dimensional accuracy is required to fit the entire surface, and the upper stator yoke 31 formed in a cup shape has various notches and poor roundness, Had a gap, the level of fitting varied, and it was impossible to stabilize the magnetic resistance. For this reason, the variation in characteristics tends to be large, and the fitting between the upper stator yoke 31 and the lower stator yoke 33 cannot be stabilized, resulting in poor cost performance.
[0011]
In addition, a hybrid type stepping motor can be used for equipment requiring high-speed response, but the structure of the rotor and stator yoke is extremely complicated. There are sensors that perform closed-loop control by arranging sensors, but they are still extremely complicated, and have a problem that they cannot be used for very expensive and low-priced, high-performance devices required by the times.
[0012]
[Problems to be solved by the invention]
The present invention has been made in view of such a conventional problem, and has as its object to provide a high-speed response type stepping motor that maintains stable characteristics, has a simple structure, and enables high-speed response.
[0013]
[Means for Solving the Problems]
The high-speed responsive stepping motor according to the present invention comprises a stator unit in which a coil is sandwiched inside two stator yokes in which pole teeth formed by bending a steel plate of a soft magnetic material along an inner circumference are combined with each other, A stator assembly having two units fixed back-to-back, and a rotor having a field rotor magnet on the outer periphery and disposed on the stator assembly so as to face the pole teeth; The total length of the fitting portion where the yoke is fitted is set to be not more than twice the total length of the pole teeth of the stator yoke.
[0014]
Further, in the high speed response type stepping motor according to the present invention, the one stator yoke has a cup shape and the other stator yoke has an annular shape fitted inside the cup shaped stator yoke. The length of the fitting portion is set based on the outer peripheral shape of.
[0015]
Further, in the high-speed response stepping motor according to the present invention, the annular stator yoke has cutouts formed at predetermined intervals along the outer periphery, and sets the length of the fitting portion.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0017]
FIG. 1 is a configuration diagram of a high-speed response type stepping motor according to the present invention.
[0018]
As shown in FIG. 1, a high-speed response type stepping motor according to the present invention is a PM type stepping motor, wherein 1 and 2 are flanges formed by punching a galvanized steel sheet, 3 is a bearing made of an oil-impregnated alloy, Reference numeral 11 denotes a cup-shaped upper stator yoke which is formed by bending a steel plate of a soft magnetic material three-dimensionally into a cup shape and has pole teeth 12 on the inner periphery, 15 denotes a coil formed by winding a polyurethane copper wire or the like, and 14 denotes a coil 15 Is a lower stator yoke having an annular shape having pole teeth 12 on its inner periphery, and a first stator unit 10A is formed of an upper stator yoke 11 and a lower stator yoke. 13 and the coil 15 held on the bobbin 14 are sandwiched and combined. The second stator unit 10B has the same configuration as the first stator unit 10A, and is fixed back to back with the first stator unit 10A. The first stator unit 10A and the first stator unit 10B constitute a stator assembly.
[0019]
Reference numeral 21 denotes a shaft serving as a center of rotation, and reference numeral 24 denotes a field which has a plurality of magnetic poles formed by magnetizing the outer periphery thereof and is disposed to face the pole teeth 12 of the upper stator yoke 11 and the lower stator yoke 13. The magnet rotor magnet 23 is a sleeve for fastening and holding the field magnet 24 and the shaft 21. The rotor 20 is composed of the shaft 21, the field rotor magnet 24, and the sleeve 23. The rotor 20 is press-fitted and fixed on the basis of the shaft 21 that is the center of rotation, and an adhesive is applied to the outer periphery of the sleeve 23. It is manufactured by coating, inserting the field magnet rotor magnet 24 coaxially, and bonding and fixing.
[0020]
The rotor 20 is made of an oil-impregnated bearing 3 caulked and fixed to the flange 1 such that the field rotor magnet 24 faces the pole teeth 12 of the first stator unit 10A and the second stator unit 10B at a small interval. Shaft 21 is inserted from below, the flange 1 is fixed to the first stator unit 30A by plasma welding or the like, and the shaft 21 is inserted from above into a bearing (not shown) fixed to the flange 2 by caulking. It is fixed to the second stator unit 30B by plasma welding or the like, and is rotatably attached to the first stator unit 10A and the second stator unit 10B.
[0021]
FIG. 2 is a sectional view of the first stator unit 10A used in the high-speed response stepping motor according to the present invention.
[0022]
As shown in FIG. 2, the first stator unit 10 </ b> A is fitted with an inner surface of an upper stator yoke 11 formed in a cup shape and an outer peripheral surface of a lower stator yoke 13 formed in an annular shape. Let me. By this fitting, the inner surface of the upper stator yoke 11 and the outer peripheral surface of the lower stator yoke 13 intermittently fit. Moreover, when the upper stator yoke 11 and the lower stator yoke 13 are fitted, the pole teeth 12 of the upper stator yoke 11 and the lower stator yoke 13 are arranged so as to be combined at equal intervals. A coil 15 is accommodated inside the upper stator yoke 11 and the lower stator yoke 13. Note that the second stator unit 10B shown in FIG. 1 is stacked back to back with the first stator unit 10A and integrated by a method such as molding using a polymer material.
[0023]
FIG. 3 is a plan view of an annular lower stator yoke used in the high-speed stepping motor according to the present invention.
[0024]
As shown in FIG. 3, the lower stator yoke 13 formed in an annular shape has notches 13a formed at predetermined intervals along the outer periphery, and a fitting portion 13b is formed by forming the notches 13a. I have. The fitting portion 13b of the lower stator yoke 13 is fitted on the inner surface of the end of the upper stator yoke 11 formed in the cup shape shown in FIG. The fitting length, which is the sum of the lengths La of the fitting portions 13b, is not more than twice the total length of the base length Lb of the pole teeth 12 by setting the fitting by the notch portion 13a to several places instead of the entire circumference. And Therefore, the high-speed response type stepping motor according to the present invention can suppress the inductance more than necessary, and can stably fit without increasing the dimensional accuracy of the upper stator yoke 11 and the lower stator yoke 13. High-speed response can be performed stably at low cost.
[0025]
FIG. 4 is a graph showing a change in inductance and a change in torque depending on the fitting length in the high-speed response stepping motor according to the present invention.
[0026]
As shown in FIG. 4, this graph shows the change in inductance and the change in torque with respect to the fitting length ratio to the fitting length based on the total length of the pole teeth described in FIG. I have. As is clear from the graph of FIG. 4, when the fitting length ratio is low, that is, when the fitting length is short, the inductance is reduced, and the torque is very small when the fitting length ratio is 2, that is, when the pole tooth length is twice or less. It can be seen that it has not changed.
[0027]
FIG. 5 is a graph showing characteristics of the conventional PM type stepping motor and the high-speed response type stepping motor of the present invention depending on the fitting length.
[0028]
This graph compares the relationship between torque and current with respect to rotation frequency when the high-speed response type stepping motor of the present invention is 32 steps and the fitting length ratio is 1.3, as compared with the conventional product (fitting length ratio of 2.4). are doing. Tj indicates the torque characteristic of the conventional PM stepping motor, Tn indicates the torque characteristic of the high-speed response stepping motor of the present invention, Ij indicates the current characteristic of the conventional PM stepping motor, and In indicates 4 shows current characteristics of the high-speed response type stepping motor of the present invention.
[0029]
The high-speed response type stepping motor of the present invention has a larger current than the conventional PM type stepping motor as a whole, but has a better torque characteristic especially in the high speed region than the conventional PM type stepping motor. .
[0030]
In the embodiment of the present invention, the notches 13a are formed at predetermined intervals along the outer periphery of the lower stator yoke 13 formed in an annular shape, and the length of the fitting portion 13b is set. However, a notch may be formed at the lower end of the outer periphery of the upper stator yoke 11 formed in a cup shape.
[0031]
Further, in the embodiment of the present invention, the PM type stepping motor which is an inner rotor type has been described. However, naturally, the gist of the present invention can be applied to an outer rotor type stepping motor.
[0032]
As described above, according to the embodiment of the present invention, the PM type stepping motor can maintain stable characteristics, and can achieve a high-speed response with a simple structure.
[0033]
【The invention's effect】
The high-speed responsive stepping motor according to the present invention comprises a stator unit in which a coil is sandwiched inside two stator yokes in which pole teeth formed by bending a steel plate of a soft magnetic material along an inner circumference are combined with each other, A stator assembly having two units fixed back-to-back, and a rotor having a field rotor magnet on the outer periphery and disposed on the stator assembly so as to face the pole teeth. Since the total length of the fitting portion to which the yoke is fitted is less than twice the total length of the roots of the pole teeth of the stator yoke, optimization of inductance, which is a hindrance to high-speed response, and improvement of the stator yoke It is possible to stabilize the fitting between each other, maintain stable characteristics, and enable high-speed response at low cost.
[0034]
Further, in the high speed response type stepping motor according to the present invention, the one stator yoke has a cup shape and the other stator yoke has an annular shape fitted inside the cup shaped stator yoke. Since the length of the fitting portion is set based on the outer peripheral shape, the length of the fitting portion can be accurately set, and the fitting between the stator yokes can be stabilized.
[0035]
Furthermore, in the high-speed response type stepping motor of the present invention, the annular stator yoke forms cutouts at predetermined intervals along the outer periphery and sets the length of the fitting portion. The length of the fitting portion can be set more accurately, and the fitting between the stator yokes can be stabilized.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a high-speed response type stepping motor according to the present invention.
FIG. 2 is a cross-sectional view of a first stator unit 10A used in a high-speed response stepping motor according to the present invention.
FIG. 3 is a plan view of an annular lower stator yoke used in the high-speed response stepping motor according to the present invention.
FIG. 4 is a graph showing a change in inductance and a change in torque depending on a fitting length in a high-speed response type stepping motor according to the present invention.
FIG. 5 is a graph showing characteristics according to a difference in fitting length between a conventional PM type stepping motor and a high-speed response type stepping motor of the present invention.
FIG. 6 is a perspective view of a conventional PM stepping motor, FIG. 6A is an exploded perspective view of the conventional PM stepping motor, and FIG. 6B is a perspective view of the conventional PM stepping motor. FIG. 4 is an exploded perspective view of a stator used.
[Explanation of symbols]
1, 2 Flange 3 Bearing 10A First stator unit 10B Second stator unit 11 Upper stator yoke 12 Polar teeth 13 Lower stator yoke 13a Notch 13b Fitting portion 13c Fitting surface 14 Bobbin 15 Coil 21 Shaft 23 Sleeve 24 Field magnet rotor magnet 20 rotor

Claims (3)

A stator in which a coil is sandwiched inside two stator yokes in which pole teeth formed by bending a steel plate of a soft magnetic material along the inner circumference are combined with each other, and the two stator units are fixed back to back. An assembly and a rotor having a field rotor magnet on the outer periphery and disposed on the stator assembly in opposition to the pole teeth, wherein a length of a fitting portion in which the two stator yokes are fitted. A high-speed response type stepping motor, wherein the total length is not more than twice the total length of the pole teeth of the stator yoke. One of the stator yokes has a cup shape, the other has an annular shape that fits inside the stator yoke of the cup shape, and the outer shape of the stator yoke of the annular shape has a length of the fitting portion. The high-speed response type stepping motor according to claim 1, wherein the setting is performed. The high-speed stepping motor according to claim 2, wherein the annular-shaped stator yoke forms notches at predetermined intervals along an outer periphery thereof, and sets the length of the fitting portion. .

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