JPS63133861A - Stepping motor - Google Patents

Abstract

PURPOSE:To increase the volumetric ratio of a coil, by concentrating flux, generated in cylindrical driving coils, into an inner cylindrical stator magnetic pole and an outer stator magnetic pole to arrange the flux in the areas of plural radii of curvature. CONSTITUTION:A stepping motor 10 is equipped with a frame 12, a stator 14 and a rotor 26. A housing 16 is fixed to the yoke 15 of the stator 14 and the output shaft 22 of the rotor 26 is supported through bearings 18, 20. Cylindrical driving coils 28-32 of first-third phase are arranged in the stator 14 concentrically with different radii of curvature while inner and outer cylindrical stator magnetic poles 34-44 of first-third phase are arranged inside and outside of the coils. A plurality of arc-shaped magnetic pole teeth 34p-44p, a plurality of troughs 34c-44c and a plurality of slits 34s-44s are formed on said magnetic poles 34-44. Cylindrical magnetism interrupting members 46-50 and magnetism interrupting rings 52-56 are arranged to prevent the leakage of magnetism whereby the electromagnetic energy converting efficiency of the motor may be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a stepping motor, and more particularly to a highly efficient stepping motor with increased effective energy density.

2. Description of the Related Art As various information devices, OA devices, and FA devices have become more energy-saving, smaller, lighter, and more sophisticated in recent years, the need for small, lightweight, high-performance, and energy-saving stepping motors has been increasing. In conventional stepping motors, the rotor is placed inside a stator with multiple phases, and the magnetic poles of multiple phases are divided on the same plane, so when the number of phases is large, the magnetic pole per phase becomes small. This has the disadvantage that the area of the magnetic poles facing the rotor becomes smaller, resulting in a significant decrease in the output torque of the motor. Moreover, in conventional stepping motors, the drive coil must be arranged within a narrow cross-sectional area divided within the same plane of the stator. Therefore, if you try to increase the number of turns of the coil to increase the output torque, the motor The disadvantage was that it became large. Furthermore, these stepping motors have a drawback in that the magnetic deviation between adjacent magnetic poles in the stator is large, and the effective magnetic flux actually used to drive the rotor is small. Furthermore, the output torque of the stepping motor is determined by the number of turns (n) of the drive winding and the square of the drive current (I) of this winding (nl
)', in order to more effectively reduce the size and improve the performance of the stepping motor, the ratio of the I drive winding per unit volume of the stepping motor, that is, the total volume of the stator and rotor. Although it is necessary to increase the ratio of the volume of the drive winding to.

In conventional stepping motors, due to their special structure, it was not possible to increase the ratio of drive windings per unit volume of the stepping motor. These shortcomings have been a major bottleneck in realizing stepping motors that are smaller and lighter, more energy efficient, have higher performance, and larger capacity machines.

[Purpose of the invention]

Therefore, the purpose of this invention is to increase the effective energy density.

An object of the present invention is to provide a stepping motor with high electromagnetic energy conversion efficiency.

Another object of the present invention is to provide a highly efficient stepping motor that can save energy, be miniaturized, and improve gj performance.

Another object of the invention is to provide a stepping motor with less magnetic leakage and less electromagnetic noise.

Another object of the present invention is to provide a low-cost stepping motor that is simple in structure, easy to assemble, and can be put to practical use in small to large capacity machines.

Another object of this invention is to reduce the inertia of the rotor, and to reduce the power density (kw/kg) and power rate (kw/kg).
The object of the present invention is to provide a stepping motor with significantly improved speed (w/s).

Another purpose of this invention is to reduce the air gap and increase the starting torque.

The purpose of the present invention is to provide a stepping motor with excellent slewing characteristics.

[Structure of the invention]

In the stepping motor of the present invention, a plurality of phases of cylindrical drive windings having different radii of curvature are arranged concentrically in the stator, and an inner cylindrical stator magnetic pole and an external cylindrical stator magnetic poles are arranged concentrically, and a plurality of 6J&pole teeth are formed on the front surfaces of the inner cylindrical stator magnetic pole and the outer cylindrical stator magnetic pole, each divided in the circumferential direction with a predetermined tooth pitch relationship; A plurality of magnetic pole teeth are formed in the rotor disk that are divided in the circumferential direction and extend in the radial direction, and each magnetic pole tooth of the rotor disk is arranged to face the magnetic pole teeth of each phase of the stator via an air gap. It is characterized by what it did.

〔Example〕

A preferred embodiment of the stepping motor according to the present invention will be described with reference to FIGS. 1 to 3. In Figure 1.2,
The stepping motor 10 has a frame 12 and a frame 1.
The stator 14 is supported by the stator 2. Preferably.

The stator 14 includes a disc-shaped stator yoke 15 fixed to the mount portion 12a of the frame 12. A housing 16 is fixed to the stator yoke 15 by welding or other suitable means. The six frames 12 are made of a non-magnetic metal material that is a good thermal conductor, and an output shaft 22 is rotatably supported through bearings 18 and 20, respectively. Further, the stepping motor 10 has an output shaft 2
2 and a rotor 26 fixed with a screw 24.

The stator 14 has first to third phase cylindrical drive windings 28, 30, 32 concentrically arranged with different radii of curvature.

Inside and outside of the first phase cylindrical drive winding 28, first phase internal cylindrical stator magnetic poles 3 made of a material with high magnetic permeability are respectively provided.
4 and external cylindrical stator poles 36 are arranged. First phase inner cylindrical stator pole 34 and outer cylindrical stator pole 36
The rear part of the stator yoke 15 is magnetically coupled to the stator yoke 15. A second phase internal cylindrical stator magnetic pole 38 and an external cylindrical stator magnetic pole I@40 made of a material with high magnetic permeability are arranged inside and outside the second phase cylindrical quick-acting winding 30, respectively.

The rear portions of the second phase internal cylindrical stator magnetic poles 38 and external cylindrical stator magnetic poles 40 are magnetically coupled by the stator yoke 15 . Similarly, a third phase internal cylindrical stator magnetic pole 42 and an external cylindrical stator magnetic pole 44 made of a material with high magnetic permeability are arranged inside and outside the third phase cylindrical egg motion winding 32, respectively. The stator poles and the rear portions of the external cylindrical stator poles are magnetically coupled by a stator yoke 15.

A plurality of small teeth, that is, arc-shaped magnetic pole teeth 34P and 36P, are formed at equal intervals in the circumferential direction at a pitch angle α° on the front surface or axial end face of the first phase internal cylindrical stator magnetic pole 34 and the external cylindrical stator magnetic pole 36, respectively. and multiple valleys 34
0 circular arc magnetic pole teeth 34F in which C, 36C are formed,
36P are the N pole and S pole of the 1st phase, respectively, in the same phase.
constitute the poles. The front surfaces of the second phase internal cylindrical stator magnetic pole 38 and the external cylindrical stator magnetic pole 40 have the same pitch angle α° with respect to the first phase magnetic ti1134P and 36P, respectively, and a 1/3 pitch (α°/3) in the CW force direction. A plurality of misaligned arc-shaped magnetic pole teeth 38P, 40P and troughs 38C, 40
C is formed, and the arc-shaped magnetic pole teeth 38F and 40P constitute the second phase S pole and N pole, respectively. A second phase magnetic pole 38P is provided in front of the third phase internal cylindrical stator magnetic pole 42 and the external cylindrical stator magnetic pole 44, respectively.

A plurality of arc-shaped magnetic pole teeth 42P, 44P and troughs 42C and 44G are formed with the same pitch angle α゜ but shifted by 1/3 pitch (α°/3) in the CW force direction with respect to 401'. .2P and 44P constitute the N and S poles of the third phase.

1st to 3rd phase arc-shaped magnetic pole teeth 34P, 36P, 38P
, 40T', 42F, and 44P have a plurality of thin slits 34S and 36S extending in the radial direction.

38S, 40S, 423, and 448 are formed, respectively. This is because due to the magnetic skin effect caused by the varying magnetic flux when the cylindrical drive winding turns on and off, the area of strong magnetic flux density that effectively contributes to electromagnetic force becomes extremely narrow, increasing magnetic resistance and reducing the total magnetic flux. This is to prevent the output torque of the motor from decreasing. These slits effectively suppress eddy currents, which are the effects of demagnetizing fields on fluctuating magnetic flux, and thus have the effect of uniformly distributing the strong magnetic flux portion over a wide portion of each arcuate magnetic pole tooth of each phase. Furthermore, by forming a plurality of slit portions in each arc-shaped magnetic pole tooth, the amount of change in the strength of the magnetic field and the magnetic flux density can be greatly changed as the rotor 26 rotates, which has a significant effect on increasing the output of the stepping motor.

A cylindrical magnetic shielding member 46 made of a conductive material is disposed between the first phase external cylindrical stator magnetic pole 36 and the housing 16. A cylindrical magnetic shielding member made of a conductive material such as copper or aluminum is provided between the first phase internal cylindrical stator magnetic pole 34 and the second phase external cylindrical stator magnetic pole 40 to block magnetic leakage between these magnetic poles. 48 are arranged. The front surface of the magnetic shielding member 48 preferably has an adjacent arcuate magnetic pole tooth 34.
It can be aligned to the front of P and 40P. A cylindrical magnetic shielding member 50 is disposed between the second phase internal cylindrical stator magnetic pole 38 and the third phase external cylindrical stator magnetic pole 44 to effectively prevent magnetic leakage between adjacent magnetic poles.

Magnetic isolation rings 52, 54, 56 made of conductive metal J111 such as aluminum or copper are arranged in front of the first to third phase cylindrical drive windings 28, 30, 32. The magnetic shielding rings 52, 54, 56 have first phase arcuate magnetic pole teeth 34P, 3613. Second phase arc-shaped magnetic pole teeth 38P, 40
P, and is located in the radial annular gap between the arcuate magnetic pole teeth 42P and 44P of the third phase, and improves the electromagnetic energy conversion efficiency of the motor by blocking magnetic leakage between adjacent magnetic pole teeth of each phase. − to make. In particular, when the motor is downsized, magnetic leakage between the NS magnetic pole teeth of each phase is effectively prevented, resulting in a highly efficient super-heavy motor. Furthermore, it also serves to effectively prevent radiation of electromagnetic noise to the outside of the motor due to the turning on and off of the cylindrical drive windings 28, 30, 32.

In the above configuration, the magnetic flux generated by each of the cylindrical drive windings 28 to 32 is more concentrated between the opposing magnetic pole surfaces of the rotor 26 and the stator 14 via the arc-shaped magnetic pole teeth of each phase, so that the maximum electromagnetic energy can be obtained. Therefore, the electromagnetic energy conversion efficiency is high, and the maximum output torque can be obtained with a small amount of electrical energy.

Furthermore, the magnetic flux generated by the cylindrical drive winding of each phase is directly concentrated on the high magnetic permeability internal cylindrical stator magnetic poles and external cylindrical stator magnetic poles, and magnetic leakage to magnetic fields other than the magnetic pole teeth is blocked by magnetic isolation rings 52 to 56. Therefore, the magnetic flux concentrates more on the arc-shaped magnetic pole teeth of each phase. Therefore, since the number of effective magnetic fluxes converted into electromagnetic energy increases, the efficiency of the motor is significantly improved and the motor can be made smaller and lighter. Further, four faces in the cross section of the cylindrical drive winding of each phase are in contact with a thermally conductive material, and these thermally conductive materials are further thermally coupled to the stator yoke and housing of the motor, and are connected to a load device via the frame 12. Because of this connection, the heat conduction area of the drive winding is dramatically expanded, and the heat dissipation of the winding is significantly improved. Therefore, there is an effect that the cooling efficiency of the motor is increased and the overload capacity can be increased. In addition, the first
In the embodiment shown in FIG. 2, arc-shaped magnetic pole teeth 34P, 36P,
38P, 4. OF, 42P, 44F are the internal cylindrical stator magnetic poles 34, 38, 42 and the external cylindrical stator magnetic poles 3 of each phase.
6,40°44, these arcuate magnetic poles are formed only on one of the internal cylindrical stator magnetic poles and external cylindrical stator magnetic poles of each phase, and on the other side are the arcuate magnetic poles formed on both the inner and outer cylindrical stator magnetic poles. In FIG. 2, not circular magnetic poles may be formed.

Reference numeral 59 indicates a cut portion for attachment.

In FIG. 3, the rotor 26 is formed with a through hole 62 for the mounting screw 24 of the rotary shaft 22 made of a high magnetic permeability material such as soft iron or silicon steel plate, and the rotor disk 6o is provided with the screw 24 on the rotating shaft 22.
is fixed. The rotor disk 6o has a plurality of arc-shaped rotor magnetic poles 64 extending in the radial region with first to third curvatures and having a pitch angle α'' in the circumferential direction, and a plurality of low permeance portions or cutouts 66. Adjacent rotor magnetic poles 64 are connected by a bridge portion or a rim portion 68 to have a reinforcing effect.The rotor magnetic poles 64 of the rotor disk 6o are arranged in a plurality of radii of curvature regions corresponding to the first to third phase stator magnetic poles in the radial direction. Multiple thin slits 64 extending
It is equipped with SI, 64SH, and 645m, respectively. Each of these slits is a slit 34 of an arcuate magnetic pole tooth of the stator.
S, 36S.

38S, 40S, 42S, and 44S to form a constant skew angle. Slit 6451, 64
SII, 645111 reduces magnetic resistance by suppressing eddy currents that occur when magnetic flux passes in the radial direction within the rotor magnetic pole teeth 64 and uniformly distributing the 1 strong magnetic flux density portion throughout the rotor magnetic pole teeth 64. This has the effect of increasing the effective magnetic flux. Moreover, the rotor magnetic pole teeth 64
By suppressing the eddy currents in the motor, it is possible to effectively prevent instability and resonance phenomena that occur due to a drop in torque characteristics in the medium or high speed range of the motor.
Stable torque characteristics can be obtained from low speed range to high speed range. Furthermore, in combination with the slits in the arc-shaped magnetic pole teeth of the stator, as the rotor disk 6o rotates, the strength of the magnetic field between the opposing magnetic pole surfaces of the stator and rotor and the amount of change in magnetic flux density are greatly changed, which increases the output torque of the remoter. A significant increase can be achieved. If it is desired to further reduce the size and weight of the stepping motor, the magnetic pole teeth of the rotor disk 60 may be constructed of permanent magnets (not shown in the figure). Furthermore, the magnetic pole teeth 64 of the rotor disk 6o may be formed in the same plane. However, arcuate magnetic pole teeth may be formed in the axial convex region in different planes with different axial thicknesses of the rotor disk, and the concave region may be a low permeance portion instead of a cutout.

In the above configuration, when the first phase cylindrical drive winding 28 is excited, the magnetic flux generated by the coil 28 is transferred to the inner cylindrical stator pole 34. The stator yoke 15 and the external cylindrical stator magnetic pole 36 are focused, and at this time, the arcuate magnetic pole teeth 34
P and 36P are excited as N and S poles, respectively, as shown by arrows F in FIG. 1, and attract the arc-shaped magnetic pole teeth 64 of the rotor 26. At this time.

The rotor 26 comes to rest at a stable point where the cutout 66 of the rotor disk 60 coincides with the first phase troughs 34G, 36C. As described above, when the rotor magnetic pole 64 of the rotor 26 moves over the first phase magnetic pole teeth 34P and 36P of the stator,
Since the strength of the magnetic field between the opposing magnetic pole surfaces of the stator and rotor and the amount of change in magnetic flux density vary greatly depending on the slits, the torque can be significantly increased depending on the number of slits. Moreover, since magnetic isolation rings 52 to 56 are arranged in the radial gaps between the magnetic pole teeth of each phase of the stator, magnetic leakage between the stator magnetic pole teeth is completely blocked, and the magnetic flux is directed to the target. Large electromagnetic energy acts on the rotor 26, concentrated only in the magnetic field. Next, when the first phase cylindrical drive winding 28 is turned off and the second phase cylindrical quick acting winding 830 is turned on, the second phase stator magnetic pole teeth 38P and 40P each turn to the S pole. , is excited to the north pole and attracts the rotor magnetic pole 64 of the rotor 26. At this time, the rotor magnetic pole 64 of the rotor 2G moves clockwise, so the rotor 26 steps clockwise at a pitch angle of α0/3. Furthermore, the second phase cylindrical drive winding 1iA30 turns
When the third phase cylindrical drive winding 32 is turned on, the rotor magnet wA64 of the rotor 26 is attracted clockwise, and the rotor 26 walks clockwise at a pitch angle of α@/3. proceed. In this way, by sequentially exciting the cylindrical drive windings 28 to 32 of the first to third phases in the sequence of ■→■→■, the rotor 26 advances clockwise by α@/3 pitch angles. .

The counterclockwise rotation of the rotor 26 is caused by the first to third phase drive windings! It is obtained by excitation in the sequence →■→■→■→■→■.

The stepping motor of the above embodiment may be driven by one-phase excitation or two-phase excitation. By connecting a suitable encoder or resolver to the stepping motor of the present invention, it can also be used as a low-speed control motor. In addition, Phase 1 to Phase 3
It is also possible to connect the phase cylindrical drive coil to an AC power source and use it as a general-purpose low-speed AC motor.

In the above embodiments, the rotor has been described as consisting of a disk with high magnetic permeability, but the rotor may also have a structure in which arc-shaped magnetic poles made of high magnetic permeability material or permanent magnets are embedded in a disk of non-magnetic material. The thickness of the rotor disk in the axial direction may be changed so that the convex portion facing the stator constitutes an arcuate magnetic pole, and the concave portion may be used as a low permeance portion instead of a cutout.

Although the stepping motor of the present invention has been shown as being applied to a flange type motor as an example, it goes without saying that it can also be applied to a single cylindrical type motor.

〔effect〕

As is clear from the following, in the multiphase stepping motor of the present invention, the magnetic flux generated by the cylindrical drive winding in each phase is concentrated on the internal cylindrical stator magnetic pole and the external cylindrical stator magnetic pole, and each phase is Due to the arrangement in multiple radii of curvature regions in the direction, the volume ratio of the windings per unit volume of the motor can be significantly increased, and therefore the output torque of the motor can be reduced by the number of turns n of the windings and the driving current I
By significantly increasing the stepper motor in proportion to the square of (nI), it is possible to achieve higher efficiency that could not be achieved in the past.As a result, the stepping motor can be made ultra-small and lightweight, with high-speed response and high performance. 6. In particular, when making a stepping motor smaller and lighter, even if the distance between the arc-shaped magnetic pole teeth of each phase becomes smaller, the magnetic flux generated in the drive winding can be improved by placing a magnetic isolation ring between the magnetic pole teeth of each phase. No leakage into the gap between the arc-shaped magnetic pole teeth.

Because all the magnetic flux is more concentrated between the opposing magnetic pole faces of the stator and rotor.

Maximum electromagnetic energy is obtained. Therefore, the electromagnetic energy conversion efficiency is extremely high, and a large energy saving effect can be obtained. Furthermore, the four sides of the cross section of the cylindrical drive winding of each phase are surrounded by good thermal conductors, and these good thermal conductors are thermally conducted to the casing and end housing, which are also good thermal conductors. The heat conduction area of one winding is significantly increased, the heat dissipation of the winding is extremely efficient, and the overload capacity of the motor is significantly increased. Furthermore, since the cylindrical drive winding of each phase is surrounded by the inner cylindrical stator pole, the outer cylindrical stator pole, the stator yoke, and the magnetic isolation ring, the radiation of electromagnetic noise from the motor to the outside can be significantly reduced. Furthermore, a large number of slits are formed in the rotor disk and the magnetic pole teeth of the stator in parallel with the magnetic path.

The total magnetic flux can be significantly increased by effectively preventing the magnetic reaction caused by the fluctuating magnetic flux, increasing the effective cross-sectional area in the magnetic circuit, and reducing the magnetic resistance.

Since slits are formed in the arc-shaped magnetic poles of the cylindrical drive winding of each phase and the arc-shaped magnetic poles of the rotor, as the rotor rotates, the strength of the magnetic field between the opposing south pole faces of the stator and rotor increases and the magnetic flux density increases. The amount of change in the magnetic pole surface increases significantly compared to the case of a flat magnetic pole surface, and the output torque of the motor becomes extremely large.

Therefore, a stepping motor that is capable of high-speed response, is smaller, lighter, and has higher performance than ever before is realized. In addition, the rotor disc has a large-area cutout, which significantly reduces the overall weight of the rotor disc, which has extremely low rotor inertia and high rotational torque, allowing for fast response and precise positioning. It also has excellent slewing characteristics.

The rotor disk is solid and has no brushes or commutators, so it can be used at high speeds. Moreover,
Since the stator and rotor disk can use cheap raw materials, and the structures of the stator, rotor disk, and drive winding are extremely simplified, processing and assembly are simple and can be manufactured at low cost, resulting in a significant cost reduction. The motor of the present invention has a simple structure and is strong, so it is suitable for high-speed, large-output applications, and can withstand high-temperature and high-temperature operation.
It has excellent resistance to low-temperature environments, and there is no deterioration in operating performance due to continuous use.

Although the present invention is applied to a three-phase stepping motor as an example, the basic concept of the present invention is not limited to three-phase motors.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a three-phase stepping motor according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken from the line ■-■ in FIG. 1, and FIG. 3 is a plan view of the rotor in FIG. Each is shown below. 12...Frame 14...
...Stator 26 ...Rotor

Claims (7)

[Claims] (1) Multi-phase cylindrical drive windings with different radii of curvature arranged concentrically, and inner cylindrical stator magnetic poles and outer cylindrical stator arranged concentrically inside and outside each of the cylindrical drive windings. a plurality of magnetic pole teeth divided in the circumferential direction at a front portion of at least one of the internal cylindrical stator magnetic pole and the external cylindrical stator magnetic pole of the plurality of phases with a predetermined tooth pitch relationship with each other; a stator,
It consists of a rotor disk having a plurality of magnetic pole teeth extending in the radial direction at circumferentially divided positions, and in each phase, the magnetic pole teeth of the rotor disk are opposed to the magnetic pole teeth of the stator via an air gap. A stepping motor characterized by: (2) The stator further includes a magnetic isolation ring disposed in the annular gap between the inner cylindrical stator pole and the outer cylindrical stator pole in front of the cylindrical drive winding of each of the plurality of phases. A stepping motor according to claim 1. (3) The stepping motor according to claim 1 or 2, wherein the magnetic pole teeth of the inner cylindrical stator magnetic pole and the outer cylindrical stator magnetic pole are arcuate magnetic pole teeth. (4) The stator further includes a stator yoke connected to rear portions of the inner cylindrical stator pole and the outer cylindrical stator pole.
Stepping motor according to item 1 or item 2. (5) The arc-shaped magnetic pole teeth of the stator magnetic poles are provided with a plurality of radially extending eddy current prevention slits, and the rotor disk magnetic pole teeth are provided with a plurality of radially extending eddy current prevention slits. Claim No. 3:
Stepping motor described in section. (6) The stepping motor according to claim 5, wherein the slits of the rotor disk form a constant skew angle with respect to the slits of the stator magnetic poles. (7) The stator further comprises a cylindrical magnetic shielding member between the internal cylindrical stator magnetic poles and the external cylindrical stator magnetic poles of adjacent phases in the plurality of phases. The stepping motor described in item 2.