Iron core for frameless motor and frameless motor

Abstract

To provide an iron core for a frameless motor having improved cooling characteristics, and a frameless motor.SOLUTION: An iron core for a frameless motor is a cylindrical iron core formed by laminating a plurality of tabular iron core materials in each of which an opening is formed in a central part, and includes a plurality of rugged parts disposed in rotational symmetry on an outer peripheral surface. A frameless motor comprises a cylindrical iron core formed by laminating a plurality of tabular iron core materials in each of which an opening is formed in a central part, the iron core including a plurality of rugged parts disposed in rotational symmetry on an outer peripheral surface.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present embodiment of the present invention relates to a core for a frameless motor and a frameless motor.

Background Art

[0002] For example, as a motor used in self-propelled devices such as trains and elevators, a frameless motor that omits a frame for housing the motor is used. Since the motor itself is protected by the housing of the device, there is no need to consider rain or snow, and since it is an operating environment where dust and dirt do not easily adhere, it can operate as a motor even without a frame.

[0003] For example, Patent Document 1 discloses a frameless motor including a cylindrical stator core formed by laminating a plurality of thin steel plates, a load-side bracket fixed to the load-side end face of the stator core, a counter-load-side bracket fixed to the counter-load-side end face of the stator core, a rotor provided inside the stator core with a gap therebetween, a shaft supported by the load-side bracket and the counter-load-side bracket and fixed to the rotor, and bolts for fixing the load-side and counter-load-side brackets to the stator core. In the frameless motor, the load-side bracket and the counter-load-side bracket each have legs integrally formed with the bracket main body portion, and attachment holes are provided in the legs.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, there has been a demand for miniaturization and weight reduction of motors. When a motor is miniaturized while maintaining its output, the energy density of the motor increases, raising concerns about an increase in the temperature generated in the motor. Therefore, improvement of the cooling characteristics of the stator core is required.

[0006] Therefore, there is provided a core for a frameless motor with improved cooling characteristics and a frameless motor.

Means for Solving the Problem

[0007] The core for a frameless motor according to the present embodiment is a cylindrical core formed by laminating a plurality of plate-shaped core materials having an opening formed in the central portion, and includes a plurality of concavo-convex portions arranged rotationally symmetrically on the outer peripheral surface.

[0008] The frameless motor according to the present embodiment is a cylindrical core formed by laminating a plurality of plate-shaped core materials having an opening formed in the central portion, and includes a core having a plurality of concavo-convex portions arranged rotationally symmetrically on the outer peripheral surface.

Brief Description of the Drawings

[0009]

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Mode for Carrying Out the Invention

[0010] Hereinafter, a frameless motor according to a plurality of embodiments and a stator core for the frameless motor will be described with reference to the drawings. Note that substantially the same elements in the plurality of embodiments are denoted by the same reference numerals and their description will be omitted. Hereinafter, the stator core may be simply referred to as a core.

[0011] (First Embodiment) The first embodiment will be described with reference to FIGS. 1 to 6. The core 10 shown in FIG. 1 is used for a frameless motor (not shown). The core 10 is formed in a cylindrical shape such as a substantially cylindrical shape or a substantially polygonal cylindrical shape, and includes an inner peripheral surface 11 and an outer peripheral surface 12. The inner peripheral surface 11 of the core 10 is substantially cylindrical. The circumferential direction of the inner peripheral surface 11 is referred to as the circumferential direction of the core 10, the radial direction of the inner peripheral surface 11 is referred to as the radial direction of the core 10, and the axial direction of the inner peripheral surface 11 is referred to as the axial direction of the core 10. In this specification, the axial view is referred to as the plan view. A rotor (not shown) is disposed inside the core 10, and the central axis of the core 10 coincides with the rotation axis of the rotor. In the present embodiment, the core 10 is formed in a substantially square cylindrical shape.

[0012] The iron core 10 includes a plurality of teeth portions 13 and a yoke portion 14. The plurality of teeth portions 13 protrude toward the central portion and form the inner peripheral surface 11. The yoke portion 14 is disposed on the radially outer side of the plurality of teeth portions 13 and forms the outer peripheral surface 12. The iron core 10 is formed by laminating a plurality of iron core materials 20. The iron core material 20 is, for example, a plate-shaped electromagnetic steel sheet such as a silicon steel sheet that has been punched into an annular shape.

[0013] The iron core material 20 has an inner peripheral portion 21 and an outer peripheral portion 22. The inner peripheral portion 21 and the outer peripheral portion 22 have a rotationally symmetric shape about the axial direction of the iron core 10. In the present embodiment, the iron core material 20 has a substantially square shape in plan view. That is, the outer peripheral portion 22 has four side portions 221 and four corner portions 222 that connect the respective side portions 221.

[0014] Adjacent iron core materials 20 are laminated such that the corner portions 222 overlap each other in the axial direction.

[0015] Further, the iron core material 20 includes a plurality of recesses 23 disposed rotationally symmetrically on the outer peripheral portion 22. The recesses 23 are formed by indenting a part of the outer peripheral portion 22 of the iron core material 20 toward the inner peripheral portion 21. In the present embodiment, the recesses 23 are formed by indenting a part of the outer peripheral portion 22 radially inward. That is, in the present embodiment, the plurality of recesses 23 are formed radially.

[0016] The iron core 10 includes a plurality of uneven portions formed rotationally symmetrically on the outer peripheral surface 12, and the surface area of the iron core 10 is set to be larger than that of the iron cores 100a and 100b without uneven portions on the outer peripheral surfaces 102a and 102b shown in FIG. 3 or FIG. 4. Thereby, the heat exchange efficiency when the outside air touches the iron core 10 can be improved, and the cooling characteristics of the frameless motor can be improved.

[0017] The iron core 10 has a plurality of groove portions 15 on its outer peripheral surface 12 as a plurality of concavo-convex portions. The plurality of groove portions 15 extend parallel to the axial direction and are arranged rotationally symmetric with respect to the central axis of a rotor (not shown). The plurality of groove portions 15 function as cooling passages that allow the passage of outside air. Therefore, particularly when the passing direction of the outside air coincides with the axial direction of the iron core 10, the cooling efficiency of the iron core 10 and the frameless motor can be further improved.

[0018] When the iron core 10 is an N-sided cylinder, the groove portions 15 can be arranged symmetrically n times. In the present embodiment, the groove portions 15 are arranged symmetrically four times. In this case, each groove portion 15 is formed by denting the outer peripheral surface 12 in the radial direction, that is, the plurality of groove portions 15 are arranged radially with respect to the central axis.

[0019] Each recessed portion 23 has a common width w which is the length dimension in the circumferential direction. In this case, each groove portion 15 also has the width w. Further, each recessed portion 23 has a depth d which is the length dimension in the radial direction. In this case, each groove portion 15 also has the depth d. In the present embodiment, the depth d varies depending on the position of the recessed portion 23. In this case, an imaginary line L connecting the bottom portions 231 of the recessed portions 23 draws a concentric circle with the substantially circular shape formed by the inner peripheral portion 21. That is, the closer to the corner portion 222, the longer the depth d of the recessed portion 23 becomes.

[0020] Here, for a motor provided with a case for housing the motor body, the cooling characteristics can be improved by increasing the surface area by providing fins on the frame or the like. However, for a frameless motor, the iron core cannot be cooled by fins.

[0021] On the other hand, according to the present embodiment described above, the iron core 10 for a frameless motor is a cylindrical iron core formed by laminating a plurality of plate-shaped iron core materials 20 having openings formed in the central portions. The iron core 10 has a plurality of concavo-convex portions arranged rotationally symmetrically on the outer peripheral surface 12, in this case, groove portions 15.

[0022] According to this, by increasing the surface area of the iron core 10 directly exposed to the outside air, the cooling characteristics of the iron core 10 and thus the frameless motor can be improved.

[0023] The iron core 10 includes, as uneven portions, a plurality of groove portions 15 extending along the lamination direction of the iron core material 20 on the outer peripheral surface 12.

[0024] As a result, since the plurality of groove portions 15 function as air passages, that is, cooling paths, the cooling efficiency of the iron core 10 can be further improved.

[0025] The frameless motor of the present embodiment is a cylindrical iron core formed by laminating a plurality of plate-shaped iron core materials 20 having an opening formed in the central portion, and includes an iron core 10 having a plurality of uneven portions arranged rotationally symmetrically on the outer peripheral surface 12. In this case, the groove portions 15 are provided.

[0026] In addition, in the present embodiment, the concave portion 23 is formed by recessing a part of the outer peripheral portion 22 inward in the radial direction, but it is not limited to this. In other embodiments, for example, as in the iron core 10b shown in FIG. 5, the groove portion 15 may be formed by recessing in a direction perpendicular to each side of the square forming the outer peripheral surface 12. In this case, the depth d of each groove portion 15 may be common over the entire outer peripheral surface 12.

[0027] Furthermore, in the present embodiment, the iron core 10 is substantially square cylindrical, but it is not limited to this. In other embodiments, the iron core may be, for example, substantially regular polygonal cylindrical such as substantially hexagonal cylindrical or substantially octagonal cylindrical, or may be substantially cylindrical as shown in FIG. 6. The substantially cylindrical iron core 10b has each groove portion 15 formed by recessing the outer peripheral surface 12 in the radial direction in the same manner as in the present embodiment. That is, the plurality of groove portions 15 are arranged radially with respect to the central axis.

[0028] (Second Embodiment) With reference to FIGS. 7 and 8, the second embodiment will be described. The iron core 30 of the present embodiment includes an inner peripheral surface 31 and an outer peripheral surface 32. The outer peripheral surface 32 includes a plurality of uneven portions arranged rotationally symmetrically.

[0029] The iron core 30 is formed by laminating a plurality of iron core materials 40. In this case, the plurality of uneven portions are formed by the rotation during the lamination of the iron core materials 40. The outer shape of the iron core material 40 is formed into a substantially regular polygon in plan view. In the present embodiment, the iron core material 40 is formed into a substantially regular octagon in plan view. The iron core material 40 has an inner peripheral surface 41 and an outer peripheral surface 42. The outer peripheral surface 42 has side portions 421 and corner portions 422 connecting the respective side portions 421.

[0030] In the present embodiment, the plurality of iron core materials 40 are laminated such that the corner portions 422 of at least some of the iron core materials 40 do not overlap each other in the axial direction. That is, the iron core materials 40 can be laminated such that the positions of the corner portions 422 are staggered for each single sheet or for a plurality of sheets. In the present embodiment, the iron core materials 40 are laminated such that the positions of the corner portions 422 are staggered for each single sheet, and the corner portions 422 of adjacent iron core materials 40 do not overlap each other in the axial direction. Therefore, the outer peripheral surface 32 of the iron core 30 has a plurality of uneven portions formed between the corner portions 422 of adjacent iron core materials 40. Thereby, the surface area of the iron core 30 can be increased, and the cooling characteristics of the iron core 30 and thus the frameless motor can be improved.

[0031] When the iron core 30 is in a substantially regular N-sided cylindrical shape, adjacent iron core materials 40 for each single sheet or for a plurality of sheets can be arranged to be relatively rotationally moved by 360 / N×m° where m is an integer. In the present embodiment, N = 8 and m = 2. That is, adjacent iron core materials 40 are arranged to be relatively rotationally moved by 22.5° each.

[0032] Here, when the shape of the iron core is changed, the rigidity of the iron core changes. The change in the rigidity of the iron core causes a change in the bending natural vibration characteristics that are the cause of the vibration and noise of the motor. FIG. 8 is a graph of the response magnification with respect to the frequency of a cylindrical iron core 100a (line A), a cylindrical iron core 10b (line B) having a groove portion 15 on the outer peripheral surface 12, and the iron core 30 (line C). In particular, for noise countermeasures, it is known that the influence of the response magnification at frequencies of 3000 Hz or less is large.

[0033] As shown in FIG. 8, the core 30 of the present embodiment is inferior to the core 100a at frequencies of 3000 Hz or less, but has an improved response magnification compared to the core 10b. Therefore, it can be understood that the core 30 of the present embodiment maintains the rigidity against bending and twisting without excessively impairing the cooling characteristics compared to the conventional core while improving the cooling characteristics.

[0034] According to the core 30 of the present embodiment, the core material 40 has a polygonal outer shape. The core materials 40 are laminated such that the positions of the corner portions 422 of the core material 40 are staggered for each single sheet or for each plurality of sheets.

[0035] Thereby, the surface area of the core 30 can be increased, and the cooling characteristics of the core 30 and thus the frameless motor can be improved. For example, when the outer shape of the core material 40 is a substantially regular octagon as in the present embodiment, it is possible to obtain a surface area equal to or greater than that obtained by providing a plurality of groove portions on the outer peripheral surface of a cylindrical core, so that it is easy to improve the cooling characteristics.

[0036] (Third Embodiment) The third embodiment will be described with reference to FIGS. 9 to 11. The core 50 of the present embodiment is formed by laminating core materials 60, similarly to the above-described embodiments. The core 50 includes an inner peripheral surface 51 and an outer peripheral surface 52. A plurality of concavo-convex portions are formed on the outer peripheral surface of the core 50 in a rotationally symmetric manner.

[0037] The core material 60 has a substantially regular polygonal outer shape in plan view. The outer peripheral portion 62 of the core material 60 has side portions 621 and corner portions 622. In the present embodiment, the core material 60 has a substantially regular octagonal outer shape in plan view.

[0038] In this case, the plurality of concavo-convex portions are formed by recesses 63 formed in the core material 60 and by the rotation during the lamination of the core materials 60. That is, the core 40 of the present embodiment includes a plurality of core materials 60 laminated by relatively rotating and moving for each adjacent single sheet or each plurality of sheets, and groove portions 55 extending in the axial direction formed by the recesses 63 formed in the outer peripheral portion 62 of the core material 60.

[0039] When the iron core 50 is substantially a regular N-sided cylindrical shape, the iron core material 60 can be arranged to be relatively rotationally moved by 360 / N*m° for each adjacent single piece or multiple pieces, where m is an integer. In this embodiment, N = 8 and m = 2. That is, the adjacent iron core materials 60 are arranged to be relatively rotationally moved by 22.5° each. Therefore, in the plan view of the iron core 50, the corner portions 622 of the adjacent iron core materials 60 are arranged in a staggered manner.

[0040] The plurality of concave portions 63 are arranged rotationally symmetrically on the outer peripheral portion 62, and are formed by indenting a part of the outer peripheral portion 62 radially inward. The concave portions 63 are arranged radially with respect to the central axis of the iron core 50. The concave portions 63 are arranged so as to axially overlap with any one of the concave portions 63 of the other iron core materials 60 when the adjacent iron core materials 60 are rotated by 360 / N*m° each. In this case, the number of the concave portions 63 can be expressed as N×l, where l is an integer. In the example shown in FIG. 9, l = 2, and the number of the concave portions 63, that is, the number of the groove portions 55, is 16.

[0041] Here, for the iron core 30 (l = 0) without the groove portion formed, the iron core 50d (l = 3) with 24 groove portions 55 shown in FIG. 10, and the iron core 50e (l = 6) with 48 groove portions 55 shown in FIG. 11, the response magnification with respect to the frequency was examined. In FIG. 12, the line C indicates the response magnification of the iron core 30, the line D indicates the response magnification of the iron core 50d, and the line E indicates the response magnification of the iron core 50e. In this case, the width w and the depth d of the groove portions 55 of the iron core 50d and the iron core 50e are set to be the same.

[0042] As shown in FIG. 12, it can be seen that when the number of the groove portions 55 is changed, the peak of the natural frequency shifts. Also, a change was also seen in the response magnification in the frequency region of 3000 Hz or less that is affected by noise.

[0043] Subsequently, for the iron core 50 shown in FIG. 9, the depth d or the width w of the groove portion 55 was changed to examine the change in the natural frequency. The graph shown in FIG. 13 shows that the width w of the groove portion 55 is 6.00×10 -3It shows the natural frequencies when the depth d of the groove portion 55 is changed while being fixed to -2 It shows the natural frequencies when the width w of the groove portion 55 is changed while being fixed to. It can be seen that when the depth of the groove portion 55 is increased, the natural frequency uniformly decreases.

[0044] Therefore, in the design of the core 50, it is possible to predict the natural frequency of the frameless motor based on the depth d and the width w of the groove portion 55. Therefore, by avoiding the natural frequency determined by the number of slots of each frameless motor and setting the depth d, width w, and number of the groove portion 55, it is possible to provide a frameless motor that suppresses electromagnetic noise while improving the cooling characteristics.

[0045] Also according to the present embodiment, the same effects as those of the above embodiments are achieved.

[0046] According to the cores 50, 50d, and 50e for the frameless motor of the present embodiment, the core material 60 has a polygonal outer shape, and the core materials 60 are laminated such that the positions of the corner portions 622 are staggered for each single sheet or a plurality of sheets. The cores 50, 50d, and 50e include a plurality of groove portions 55 extending along the lamination direction of the core material 60 on the outer peripheral surface 52.

[0047] Accordingly, according to the characteristics of the frameless motor using the cores 50, 50d, and 50e and the specification environment of the motor, the number and shape of the groove portions 55 can be designed in consideration of rigidity and cooling characteristics. For example, when cooling characteristics are more critical than rigidity, the number of groove portions 55 can be increased. On the other hand, when cooling characteristics are not so required but noise suppression is necessary, the number of groove portions 55 can be decreased, etc., thus expanding the degree of freedom in motor design. Furthermore, since the natural frequency can be predicted based on the depth d and / or width w of the groove portion 55, by utilizing this, the depth d and / or width w of the groove portion 55 are determined so as to avoid the natural frequency of the frameless motor, and thus cores 50, 50d, and 50e for a frameless motor having both cooling characteristics and rigidity characteristics can be provided.

[0048] As described above, a plurality of embodiments of the present invention have been explained. However, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention and are included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0049] 10... Core, 12... Outer peripheral surface, 15... Groove portion, 20... Core material, 22... Outer peripheral portion, 23... Concave portion, 30... Core, 32... Outer peripheral surface, 40... Core material, 42... Outer peripheral portion, 422... Corner portion, 50... Core, 50d... Core, 50e... Core, 52... Outer peripheral surface, 55... Groove portion, 60... Core material, 62... Outer peripheral portion, 622... Corner portion, 63... Concave portion

Claims

1. A cylindrical core formed by laminating a plurality of plate-shaped core materials with an opening formed in the central portion, comprising a plurality of uneven portions arranged rotationally symmetrically on the outer peripheral surface, a core for a frameless motor.

2. As the uneven portions, comprising a plurality of groove portions extending along the lamination direction of the core material on the outer peripheral surface, the core for a frameless motor according to Claim 1.

3. The core material has a polygonal outer shape, and the plurality of core materials are laminated such that the positions of the corners of the core materials are staggered for each one or each plurality of sheets, the core for a frameless motor according to Claim 1.

4. The core material has a polygonal outer shape and is laminated such that the positions of the corners of the core materials are staggered for each one or each plurality of sheets, comprising a plurality of groove portions extending along the lamination direction of the core material on the outer peripheral surface, the core for a frameless motor according to Claim 1.

5. A frameless motor comprising the core according to any one of Claims 1 to 4.

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