JP2017022994A - Electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric motor which can be driven with good energy efficiency, and can be simply and inexpensively manufactured.SOLUTION: An electric motor 10 is provided with a rotor 12 equipped with a plurality of permanent magnets 16 aligned in a circumferential direction; and a stator device equipped with a coil assembly at least partially surrounding the permanent magnets 16. The stator device has a first stator 14 and a second stator 18 equipped with a plurality of coils, and the coils of the first stator 14 and the second stator 18 are respectively formed as frame-shaped coils 20 and 28. Coils 20 of the first stator 14 are arranged on the outside of the permanent magnets 16 in a radial direction, and coils 28 of the second stator 18 are arranged on the inside of the permanent magnets 16 in the radial direction. The coils 20 and 28 are arranged in the radial direction along a coil winding shaft, and the permanent magnets 16 are arranged in the radial direction along its magnetization direction.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an electric motor having a rotor including a plurality of permanent magnets arranged along a circumferential direction and a stator device including a winding assembly that at least partially surrounds the permanent magnets.

  Electric motors in the form of small drive mechanisms that consume little energy are becoming increasingly important. Such a small drive mechanism is, for example, a small pump drive mechanism and a fan drive mechanism in an automation apparatus. Even more advantageous is the use of this type of small drive mechanism in medical technology. Small drive mechanisms are generally designed for maximum drive parameters. However, these small drive mechanisms are usually driven in a so-called partial load region. In order to apply these small drive mechanisms to the above-described applications, the drive function is incorporated into the process as it is as a mechatronic system. In such a case, the electric motor becomes an integrated built-in component.

  In addition to these structural ambient conditions, I would like to make these small drive mechanisms variable in rotation speed. For this reason, for example, it is possible to configure the drive mechanism as an inverter control type and include an intermediate voltage circuit including a pulse control type inverter. Moreover, in the case of a portable device, the intermediate voltage circuit may be replaced with a DC voltage source such as a battery. In particular, an electric motor that is generally desired for application in medical technology is an electric motor that can supply high torque, is lightweight, and has high energy efficiency, slight heating, and high operational stability without unevenness. It is.

  In order to achieve these requirements, a permanent magnet excitation type AC voltage servomotor is generally used together with a pulse control type inverter. In the case of such an electric motor, the stator is usually formed by a laminated thin plate wound with windings, which tends to increase magnetic loss or iron loss as the rotational speed increases. In particular, during partial load driving, energy efficiency is significantly degraded due to iron loss that is actually unrelated to the load. Further, the active members of this type of motor include components that are typically made of iron, which are heavy components that are undesirable and can cause cogging torque.

  According to a linear motor known from EP 1 858 142 A1, a permanent magnet is provided on the secondary side, and a multiphase winding through which a current flows is provided on the movable primary side. In this case, in order to increase the achievable driving force, the permanent magnet is arranged so that the N pole and the S pole are juxtaposed side by side in the direction of movement. Furthermore, in this case, the coils of the multiphase winding are configured such that they at least partly surround the secondary permanent magnet.

  The basic principle of a linear motor described in EP 1 858 142 A1 can be applied to a rotary motor. In that case, the rotor has a plurality of circumferentially arranged permanent magnets, and the stator has a winding assembly that at least partially surrounds the permanent magnets. For this purpose, the stator has, for example, a coil bent into a U-shape. However, the production of these coils is particularly cumbersome especially when the rotor diameter is small.

  Accordingly, an object of the present invention is to enable an electric motor of the type described at the beginning to be driven with high energy efficiency and to be manufactured simply and at low cost.

  According to the invention, this problem is solved by the electric motor according to claim 1. Advantageous embodiments of the invention are indicated in the dependent claims.

  An electric motor according to the present invention includes a rotor including a plurality of permanent magnets arranged along a circumferential direction, and a stator device including a winding assembly that at least partially surrounds the permanent magnets. And a first stator having a plurality of windings. In this case, the stator device has a second stator, and the windings of the first stator and the second stator are each formed as a frame-like coil, and the coil of the first stator is a permanent magnet in the radial direction. The coils of the second stator are arranged radially inside the permanent magnets, and the coils are arranged radially along their winding axes, and the permanent magnets Are arranged radially along the magnetization direction of the permanent magnets.

  The electric motor has a rotor, and a plurality of permanent magnets are juxtaposed along the circumferential direction of the electric motor. The rotor can be coupled to a suitable shaft and the motor torque can be extracted from that shaft. Furthermore, the electric motor has a first stator located on the outer side and a second stator located on the inner side. The first stator and the second stator have appropriate windings in the form of coils, each of which is juxtaposed in the circumferential direction. For this reason, the permanent magnet in the rotor is surrounded by a coil from two sides. Thereby, a high magnetic force can be supplied.

  Furthermore, the motor can also be configured such that only the outer stator or the inner stator is provided with the coils belonging to it. As an alternative, in addition to the coils of the first and second stators, the motor can be provided with further coils that at least partially surround the permanent magnet.

  The coils of the first stator and the second stator are substantially frame-shaped. These coils are composed of wire windings, for example, formed as air-core coils, and are arranged in the electric motor so as to be arranged in the radial direction along the winding axis of these coils. In other words, these coils have through openings, and the coils are arranged along the through openings in the radial direction of the electric motor. These coils can be easily manufactured as separate parts and can be placed in an electric motor. Such a coil type is particularly suitable when applied to a motor having a small diameter or a small electric drive mechanism. In this case, neither a slot nor a yoke is required for the electric motor. Therefore, no magnetic loss depending on the frequency occurs. Further, there is no residual torque caused by fluctuations in the magnetic permeability of the stator.

  It is advantageous to arrange the permanent magnets so that the magnetization directions of the juxtaposed permanent magnets are opposite to each other in the radial direction. The magnetization directions of the individual permanent magnets extend from the south pole to the north pole of the permanent magnets. By arranging the permanent magnets in this way, a compact design can be easily realized. In addition, the permanent magnet can be manufactured as an individual part easily and at low cost, and thereby a simple structure of the electric motor can be realized.

  According to one embodiment, the coil has a greater spatial extent or dimension in the direction perpendicular to the winding axis than in the winding axis direction. In other words, each coil in the first stator and the second stator has a flat shape. These coils are formed as flat coils, for example. The spatial extent of these coils can be made as large as possible in the direction perpendicular to the winding axis. In this way, the force generated by those coils and exerted on the permanent magnet can be increased. In particular, these coils should be formed so that the ratio between the power induced in the windings and the mechanical force generated by the motor is small. In this way, the electromagnetic utilization efficiency can be increased, and a stronger force and a larger torque can be generated even if the current density remains constant. Therefore, high torque can be supplied by the electric motor according to the present invention.

  According to one advantageous embodiment, the coils of the first stator and / or the second stator are curved along the circumferential direction of the motor. In this case, the coil of the second stator can be curved more in the circumferential direction than the coil of the first stator. By curving the coil in the circumferential direction, the electric field of the coil and the magnetic field generated by the permanent magnet of the rotor are positioned perpendicular to each other. By doing so, it is possible to generate a component of extremely strong force in the circumferential direction, and thus it is possible to generate a high torque by this electric motor.

  According to still another embodiment, the number of turns of the coil and / or the cross-sectional area of the winding wire in the first stator is different from the number of turns of the coil and / or the cross-sectional area of the winding wire in the second stator. In this way, the electric field generated from the coil can be easily matched based on the number of turns and / or the cross-sectional area. Similarly, the number of turns and / or the cross-sectional area of the coils in the first stator and the second stator can be matched to the current intensity applied to the coils.

  It is further advantageous that the permanent magnet has substantially the shape of a hollow cylindrical section. If the electric motor is configured as a linear motor, a rectangular permanent magnet can be used. A permanent magnet having this kind of geometric shape can be manufactured easily and at low cost. Similarly, the permanent magnet may be cylindrical. Further conceivable here is to curve the permanent magnet in the circumferential direction. By doing in this way, an electric motor can be manufactured easily and at low cost.

  It is further advantageous that the number of coils in the first stator and the second stator is a multiple of three. In this case, one coil of the first stator and one coil of the second stator are aligned and aligned with each other in the radial direction of the electric motor, and are electrically connected in series. As an alternative to this, one coil of the first stator can also be electrically connected in parallel with one coil of the second stator, thereby generating an induced voltage equal to the first stator and the second stator. be able to. In this case, the directions of the current intensity applied to the first stator coil and the second stator coil belonging to the same winding segment can be opposite to each other. In this way, the coil can be easily driven by the three-phase voltage power source.

  According to one embodiment, the first stator and / or the second stator has a support structure with a plurality of support members formed for coil winding. These supporting members provide a kind of winding assistance means. In this way, the first stator and the second stator can be easily manufactured.

Here, it is advantageous to manufacture the support structure and the support member from an electrically insulating material, for example, from a material having a relative permeability of 1. By placing the coil or winding around the electrically insulating material, no eddy current loss occurs. Therefore, the electric motor can be driven extremely efficiently. If a material having a relative permeability μ _r = 1 is used, no additional hysteresis loss occurs.

  The principle and advantages of the electric motor described so far can be transferred to a linear motor.

  Next, the present invention will be described in detail with reference to the drawings.

The perspective view which shows arrangement | positioning of the permanent magnet of the rotor of an electric motor, and the coil of a 1st stator. Development view showing arrangement of permanent magnet and coil Side cross-sectional view of electric motor Top view of electric motor Perspective view of electric motor Side view showing second stator and rotor of electric motor The perspective view which shows arrangement | positioning of the coil of a 1st stator and a 2nd stator View of the second stator support structure from above

  The examples described in detail below constitute advantageous embodiments of the invention.

  FIG. 1 is a perspective view showing the arrangement of the permanent magnets 16 of the rotor with respect to the coil 20 of the first stator of the electric motor. The permanent magnet 16 is rectangular. The permanent magnets 16 are juxtaposed along the circumferential direction 22. Here, the permanent magnets 16 are arranged in the radial direction 24 along their magnetization directions 40 extending from the south pole to the north pole. Furthermore, in this case, the permanent magnets 16 are arranged such that the magnetization directions 40 of the juxtaposed permanent magnets 16 are opposite to each other.

  The coil 20 of the first stator has a substantially frame-like structure. In this case, the coil 20 is disposed so as to be located outside the permanent magnet 16 in the radial direction 24. Moreover, the coils 20 are arranged such that their winding shafts 26 are located in the radial direction 24 of the motor.

In FIG. 2, the arrangement of the permanent magnet 16 and the coil 20 is shown as a development view. This electric motor is configured such that the number N ^{* of the} coils 20 is a multiple of three. In this way, the coil 20 can be connected to the three-phase voltage power source. In this way, an electric motor having a basic pole number 2p is formed. In doing so, the following rules apply:
The number of frame coils N ^* must be divisible by 3:

  Here, for the quotient of the constant p / n, p / n must be an integer, where n ≠ 3, 6, 9,. . . It is.

  If z is an even number, each winding phase is constituted by 2p / n coil groups for each z / 2 frame coils.

によって構成される。３つの巻線相の各々は、それぞれｚ／２＝２／２＝１個のフレームコイルを有する２ｐ／ｎ＝１０／５＝２個のコイル群によって構成される。 Here, the above-described law will be described by applying it to an embodiment of a 10-pole motor. In this case, the basic number of poles is 2p = 10. Therefore, the constant quotient z / n = 2/5. Therefore, each winding side

Consists of. Each of the three winding phases is constituted by 2p / n = 10/5 = 2 coil groups each having z / 2 = 2/2 = 1 frame coils.

  1 and 2 show the arrangement of permanent magnets 16 and coils 20 of an electric motor having a first stator located on the outside. Moreover, it is advantageous that the motor has a second stator located inside, in the case of the second stator, the coil is arranged inside the permanent magnet 16 in the radial direction 24.

  FIG. 3 shows a side sectional view of the 10-pole motor 10. The electric motor 10 has a rotor 12 that is mechanically connected to a shaft 30. Furthermore, the rotor 12 has a plurality of permanent magnets 16, which are arranged on a hollow cylindrical body extending in the axial direction in a radially extending disk. Furthermore, the electric motor 10 includes a first stator 14 including a plurality of coils 20 and also includes a second stator 18 including a plurality of coils 28. The coil 20 of the first stator 14 and the coil 28 of the second stator 18 are curved in the circumferential direction 22 of the electric motor 10. Similarly, the permanent magnet is also curved along the circumferential direction 22.

  FIG. 4 shows a plan view of the electric motor shown in FIG. From this figure, it can be seen that the rotor 12 of the electric motor has ten permanent magnets 16. This figure also shows that the first stator 14 has six coils 20. In this case, the coil 20 of the first stator 14 is disposed outside the permanent magnet 16 of the rotor 12 in the radial direction 24 of the electric motor 10. Similarly, the second stator 18 also has six coils 28. In this case, the coil 28 of the second stator 18 is disposed so as to be located inside the rotor 12 in the radial direction 24.

  FIG. 5 shows a perspective view of the electric motor 10 as viewed from below. Particularly shown in this figure is the coil 20 of the first stator 14. In FIG. 6, a partial view of the electric motor 10 is drawn without showing the first stator 14. Shown in this figure is a rotor 12 of an electric motor 10 having a permanent magnet 16. Further, in this figure, the coil 28 of the second stator 18 is also shown.

  In FIG. 7, the arrangement of the coil 20 of the first stator 14 and the coil 28 of the second stator 18 is depicted in a perspective view. Each of these coils 20 and 28 has a substantially frame-like structure. Since the coils 20 and 28 are formed of a wound wire rod, they form a corresponding air-core coil. In this case, in the direction extending along the winding axis 26, the spatial extent or dimension of these coils is smaller than the direction 32 extending perpendicular to the winding axis 26. In other words, the coils 20 and 28 have a flat shape. In particular, these coils 20 and 28 should be formed so that the ratio between the electric power induced in the winding and the mechanical force is small. In this way, it is possible to generate a stronger force and a larger torque while the current density remains constant.

  Furthermore, the coils 20 and 28 are curved along the circumferential direction of the electric motor 10. As shown in FIG. 7, the number of turns of the coil 20 and the coil 28 can be made different. In the example shown here, the number of turns of the coil 28 of the second stator 18 is less than that of the coil 20 of the first stator 14. In this case, the cross-sectional area of the wire of the coil 20 of the first stator 14 can be formed so as to be different from the cross-sectional area of the wire of the coil 28 of the second stator 18.

  FIG. 8 shows a state in which the support structure 34 of the inner stator 18 is viewed from above. In this case, the support structure 34 has a plurality of support members 36. These support members 36 are formed by projecting portions extending in the radial direction, and the projecting portions have notches 38 on both sides. Wires can be accommodated in the notches 38, that is, individual coils 28 can be wound there. Here, it is advantageous to form the support structure 34 and the support member 36 from an electrically insulating material having a relative magnetic permeability of 1, for example.

DESCRIPTION OF SYMBOLS 10 Electric motor 12 Rotor 14 Stator 18 Stator 20 Coil 22 Circumferential direction 24 Direction 26 Winding shaft 28 Coil 30 Shaft 32 Direction 34 Support structure 36 Support member 38 Notch 40 Magnetization direction N N pole S S pole

Claims (9)

A rotor (12) comprising a plurality of permanent magnets (16) arranged along a circumferential direction (22);
A stator arrangement comprising a winding assembly at least partially surrounding the permanent magnet (16),
The stator device has a first stator (14) with a plurality of windings,
In the electric motor (10),
The stator device comprises a second stator (18);
The windings of the first stator (14) and the second stator (18) are respectively formed as frame-like coils (20, 28),
The coil (20) of the first stator (14) is arranged outside the permanent magnet (16) in the radial direction (24),
The coil (28) of the second stator (18) is arranged inside the permanent magnet (16) in the radial direction (24),
The coils (20, 28) are arranged along the winding axis (26) of the coils in the radial direction (24),
The electric motor (10), characterized in that the permanent magnets (16) are arranged in a radial direction (24) along the magnetization direction (40) of the permanent magnets.   The electric motor (10) according to claim 1, wherein the permanent magnets (16) are arranged such that the magnetization directions (40) of the juxtaposed permanent magnets (16) are opposite to each other in the radial direction.   The coil (20, 28) has a greater spatial extent in a direction (32) perpendicular to the winding axis (26) than in the direction of the winding axis (26). Electric motor (10).   The coil (20, 28) in the first stator (14) and / or the second stator (18) is curved along a circumferential direction (22) of the electric motor (10). The electric motor (10) according to any one of claims 3 to 4.   The number of turns of the coil (20) and / or the cross-sectional area of the winding wire in the first stator (14), and the number of turns of the coil (28) and / or the cross-sectional area of the winding wire in the second stator (18). The electric motor (10) according to any one of claims 1 to 4, which is different from the electric motor (10).   The electric motor (10) according to any one of claims 1 to 5, wherein the permanent magnet (16) has a shape of a section of a hollow cylindrical body.   The electric motor (10) according to any one of claims 1 to 6, wherein the number of coils in the first stator (14) and the second stator (18) is a multiple of three.   The first stator (14) and / or the second stator (18) includes a support structure (34) including a plurality of support members (36) formed to wind the coils (20, 28). The electric motor (10) according to any one of claims 1 to 7, further comprising:   The electric motor according to claim 8, wherein the support structure (34) and the support member (36) are made of an electrically insulating material, for example, a material having a relative permeability of 1. (10).

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