Rotary motor

Abstract

The objective of this invention is to provide a rotary motor that reduces eddy current losses and hysteresis losses generated at the location where the electromagnet is fastened. The rotary motor of this invention has a stator and a rotor disposed inside the stator. The stator has a stator core, stator slots arranged circumferentially in the stator core, and stator windings arranged in the stator slots. The rotor has a central shaft, rotor slots, and rotor conductors. The stator has a low-resistance fastening member on the outer periphery of the stator core. The low-resistance fastening member has a fastening portion disposed outside the stator and a stator conductor disposed inside it. The resistance of the stator conductor is lower than the resistance of the fastening portion.

Description

[Technical Field]

[0001] This invention relates to a rotary electric motor. [Previous Technology]

[0002] Regarding rotary electric machines, a structure is known of stacking a plurality of electromagnetic steel plates along the axial direction and fastening the electromagnetic steel plates. For example, the rotary electric machine described in Patent Document 1 includes: two clamps that clamp the electromagnetic steel plates stacked along the axial direction from both outer sides of the axial direction; and a plurality of fastening rods that fasten the two clamps from both outer sides of the axial direction.

[0003] [Prior Art Documents] [Patent Documents] [Patent Document 1] Japanese Patent Application Publication No. 2023-5315 [Summary of the Invention]

[0004] [Problem to be Solved by the Invention] The rotary motor in Patent Document 1 ensures that the thickness of the clamp has sufficient rigidity. However, when the clamp and the fastening rod are coupled with magnetic flux generated by the rotating magnetic field, eddy current losses and hysteresis losses are generated. However, countermeasures to reduce these losses have not yet been studied.

[0005] Therefore, the object of the present invention is to provide a rotary motor that can reduce eddy current losses and hysteresis losses generated at the location where the electromagnet is fastened.

[0006] [Technical means to solve the problem] One of the means to solve the problem in this invention is as follows.

[0007] A rotary electric machine has a stator and a rotor disposed inside the stator. The stator has a stator core, stator slots disposed circumferentially in the stator core, and stator windings disposed in the stator slots. The rotor has a central shaft, rotor slots, and rotor conductors. The stator has a low-resistance fastening member on the outer periphery of the stator core. The low-resistance fastening member has a fastening portion disposed outside the stator and a stator conductor disposed inside it. The resistance of the stator conductor is lower than that of the fastening portion.

[0008] [Effects of the Invention] According to the present invention, eddy current losses and hysteresis losses generated at the location where the electromagnet plate is fastened can be reduced, thereby increasing the efficiency of the rotary motor.

[0009] Further means and effects of the present invention will be made clear from the following description in its entirety.

Implementation Method

[0011] Hereinafter, embodiments will be described with reference to the drawings. Each embodiment is described with a focus on the stator structure that reduces eddy current losses and hysteresis losses generated at the location where the electromagnetic steel plate is fastened, which is a feature of the present invention.

[0012] [Example 1] As an example of a rotary motor, a squirrel-cage induction motor will be used for illustration.

[0013] Figure 1A is a sectional view of Figure 2A at section BB. On the other hand, Figure 2A is equivalent to a sectional view of Figure 1A at section AA. Also, Figure 1B is an enlarged view of part EX1 in Figure 1A, and Figure 2B is an enlarged view of part EX2 in Figure 2A.

[0014] Figure 3 is a CC sectional view of Figure 2A, which corresponds to the end of the rotary motor.

[0015] The stator 1 and the rotor 5 are radially opposed to each other through an air gap 12. The stator 1 has a stator core 2 and a stator winding 4 wound in a stator slot 3 formed in the stator core 2. The rotor 5 has a rotor core 6, a rotor slot 7 formed in the rotor core 6, a rotor conductor 8 disposed in the rotor slot 7, a rotor short-circuit ring 11 sandwiching the rotor conductor 8 from both outer sides in the axial direction, and a shaft 9 disposed on the inner circumference of the rotor core 6.

[0016] In the stator 1, a plurality of electromagnetic steel plates of the stator core 2 are fastened together axially. In this embodiment, as shown in Figures 1A, 2A, and 3, a low-resistance fastening member 10 is provided on the outer periphery of the stator 1.

[0017] The features of the low-resistance fastening member 10 will be explained with reference to enlarged views of Figures 1B and 2B. The low-resistance fastening member 10 of this embodiment has a fastening portion 10A. The fastening portion 10A is axially conductive. Furthermore, when viewed radially along the electromagnetic steel plate, a stator conductor 10B is axially conductive between the stator winding 4 and the fastening portion 10A. Moreover, the fastening portion 10A can be considered as a fastening member.

[0018] Furthermore, by making the resistivity of the stator conductor 10B lower than that of the fastening portion 10A, a low-resistance fastening member 10 is achieved. In this way, by utilizing the fastening portion 10A, which is involved in maintaining strength, and the stator conductor 10B, which is involved in reducing resistance, a low-resistance fastening member 10 that achieves both strength and low resistance is constructed.

[0019] Next, using Figure 4, the principle that this configuration can reduce eddy current losses and hysteresis losses generated at the location where the electromagnetic steel plate is fastened will be explained.

[0020] Figure 4 illustrates the principle of magnetic flux cancellation at the fastening point caused by the eddy currents in the stator conductors. The circled × symbol represents the eddy current in 10B, the solid arrow represents the flow of magnetic flux generated by the excitation current of the stator winding 4, and the dashed arrow represents the flow of magnetic flux generated by the eddy currents in the stator conductor 10B. Furthermore, at the fastening point 10A, the overlapping of the solid and dashed arrows, which are in opposite directions, indicates that they cancel each other out.

[0021] Furthermore, in order to generate this cancellation, the resistance of the stator conductor 10B needs to be lower than that of the fastening part 10A.

[0022] According to Faraday's law, an induced electromotive force is generated in the stator conductor 10B in the direction that counteracts the change in magnetic flux generated by the excitation current of the stator winding 4. This induced electromotive force, through the magnetic flux generated by the eddy currents in the stator conductor 10B, counteracts the magnetic flux generated by the excitation current of the stator winding 4, reducing the magnetic flux linked at the fastening portion 10A. This reduces eddy current losses and hysteresis losses generated at the fastening portion 10A.

[0023] As described above, according to this embodiment, a rotary motor that reduces eddy current losses and hysteresis losses generated at the location where the electromagnetic steel plate is fastened can be realized.

[0024] [Example 2] FIG2B is used to illustrate the difference between this embodiment and Example 1.

[0025] This embodiment differs from Embodiment 1 in that it includes a stator short-circuit ring 10C that short-circuits adjacent low-resistance fastening members 10 or adjacent stator conductors 10B. Thus, for example, in FIG1A, adjacent low-resistance fastening members can be electrically connected using the stator short-circuit ring 10C. Adjacent stator conductors 10B are short-circuited using the stator short-circuit ring 10C. This can also be described as short-circuiting at least one of the adjacent low-resistance fastening members in the radial direction of the rotating motor using the stator short-circuit ring 10C.

[0026] The eddy current generated in the stator conductor 10B increases due to the presence of stator short-circuit rings 10C on both outer sides of the stator core 2 along the axial direction, which short-circuit multiple stator conductors 10B. This is because the direction of the induced electromotive force generated in the stator conductor 10B is one direction when only one stator conductor 10B is considered. Therefore, if stator short-circuit rings 10C are provided, they short-circuit with other stator conductors 10B generated in the opposite direction, reducing the resistance and increasing the eddy current.

[0027] If the eddy current increases, the magnetic flux generated by the excitation current of the stator winding 4 can be more effectively counteracted. Moreover, the magnetic flux linked at the fastening part 10A is reduced more, and the eddy current loss and hysteresis loss generated at the fastening part 10A can be reduced more significantly compared to the case of Embodiment 1.

[0028] Furthermore, in order to generate a cancellation at the fastening part 10A, the resistance of the stator short-circuit ring 10C needs to be lower than that of the fastening part 10A.

[0029] By incorporating the stator short-circuit ring 10C, the resistance is sufficiently lower than the reactance. Therefore, the magnitude of the eddy current is determined by the reactance. Furthermore, the eddy current loss generated in the stator conductor 10B and the stator short-circuit ring 10C is proportional to the resistivity. Therefore, by using materials with low resistivity, such as copper, aluminum, or brass, for the stator conductor 10B and the stator short-circuit ring 10C, suppression of eddy current losses can be achieved.

[0030] In the above embodiment, the effect of further improving the reduction of eddy current loss and hysteresis loss in Embodiment 1 is achieved.

[0031] Furthermore, in order to further improve the effect, it is even more ideal that the stator short-circuit ring 10C is disposed between each adjacent low-resistance fastening member 10 or between each adjacent stator conductor 10B.

[0032] Furthermore, in order to further improve the effect, it is even more ideal that the stator short-circuit ring 10C is provided on both sides or both ends of the axial direction in the low resistance fastening member 10.

[0033] [Example 3] This example is basically the same as Example 1 or Example 2. Therefore, it will be described with a focus on the differences from Example 1 and Example 2.

[0034] Figure 5A corresponds to Figure 1A, and Figure 5B corresponds to Figure 1B. Also, Figure 5B is an enlarged view of part EX3 of Figure 5A.

[0035] The rotary motor of this embodiment is characterized by having a housing 13.

[0036] The outer casing 13 is disposed radially outside the stator 1 to fix the stator 1. At least one of the outer casing 13 and the fastening part 10A is a magnetic body.

[0037] When the outer casing 13 is magnetic, regardless of whether the fastening part 10A is magnetic or non-magnetic, according to Faraday's law, an induced electromotive force is generated in the stator conductor 10B in the direction that cancels the change in magnetic flux generated by the excitation current of the stator winding 4. This induced electromotive force, through the magnetic flux generated by the eddy currents in the stator conductor 10B, cancels the magnetic flux generated by the excitation current of the stator winding 4, reducing the magnetic flux linked between the fastening part 10A and the outer casing 13. This reduces eddy current losses and hysteresis losses generated between the fastening part 10A and the outer casing 13.

[0038] When the outer casing 13 is a non-magnetic material and the fastening part 10A is a magnetic material, according to Faraday's law, an induced electromotive force is generated in the stator conductor 10B in the direction that cancels the change in magnetic flux generated by the excitation current of the stator winding 4. This induced electromotive force, through the magnetic flux generated by the eddy currents in the stator conductor 10B, cancels the magnetic flux generated by the excitation current of the stator winding 4, reducing the magnetic flux linked in the fastening part 10A. This reduces eddy current losses and hysteresis losses generated in the fastening part 10A.

[0039] Assuming that both the outer casing 13 and the fastening part 10A are non-magnetic, since almost no induced electromotive force is generated in the stator conductor 10B, the reduction effect of eddy current loss generated in the fastening part 10A and the outer casing 13 is hardly obtained.

[0040] In this embodiment, in addition to the effects of Embodiment 1 or Embodiment 2, the reduction of eddy current loss and hysteresis loss can be further achieved.

[0041] [Example 4] The differences between this embodiment and Example 3 will be explained. Figure 6A corresponds to Figure 5A, Figure 6B corresponds to Figure 5B, and is an enlarged view of EX4 in Figure 6A. Furthermore, Figure 6A is a cross-sectional view of EE in Figure 7A. On the other hand, Figure 7A is a cross-sectional view of DD in Figure 6A. Moreover, Figure 7A also corresponds to Figure 2A, and Figure 7B also corresponds to Figure 2B.

[0042] In this embodiment, the point at which the fastening part 10A and the stator conductor 10B of Embodiment 1 are used to fasten the stator conductor 10D is different from that of Embodiments 1 to 3.

[0043] In this embodiment, it is designed to replace the outer shell 13 to achieve mutual cancellation at the fastening portion 10A of Embodiment 1 or Embodiment 2. Therefore, it is ideal for the outer shell 13 to be a magnetic material.

[0044] In this embodiment, the effects of reducing eddy current loss and hysteresis loss can also be achieved.

[0045] [Example 5] The difference between this embodiment and Example 4 is that the fastening sub-conductor 10D is made of high-strength brass. In this way, the fastening of the electromagnetic steel plate by the fastening sub-conductor 10D can be achieved, and the fastening sub-conductor 10D can be integrated with the fastening part.

[0046] [Example 6] The difference between this embodiment and Example 4 is that the fastening sub-conductor 10D is set to have a lower resistance than the outer casing 13.

[0047] This can further improve the effect of reducing eddy current loss and hysteresis loss.

[0048] [Example 7] The differences between this embodiment and Example 4 will be explained. Figure 8A corresponds to Figure 6A, Figure 8B corresponds to Figure 6B, and is an enlarged view of EX6 in Figure 8A. Furthermore, Figure 8A is a cross-sectional view of Figure 9A (GG section). On the other hand, Figure 9A is a cross-sectional view of Figure 8A (FF section). Moreover, Figure 9A also corresponds to Figure 2A, and Figures 9B and 9C also correspond to Figure 2B.

[0049] Furthermore, Figure 9B is an enlarged view of EX7 in Figure 9A. Also, Figure 9C is an enlarged view of EX7 in Figure 9A, just like Figure 9B, and is used to illustrate the configuration of the position offset from that in Figure 9B.

[0050] The hole for fixing the stator conductor 10E is located on the radially outer side of the stator core 2 and the hole for fixing the stator short-circuit ring 10C.

[0051] Comparing Figure 8B and Figure 6B, it is shown that in Figure 8B of this embodiment, the fixed sub-conductor 10D is not in close contact with the outer casing 13, but is disposed at a position that is separated from the outer casing 13 by the stator core 2. In this sense, in Figure 8A, the fixed sub-conductor is represented as 10E.

[0052] Thus, even if the fixed sub-conductor 10D is not in close contact with the housing 13, the present invention is still included in the scope of its disclosure.

[0053] The fastening sub-conductor 10D, as an example, can be formed in a wide range of configurations, as shown in FIG9B. Furthermore, as shown in FIG9B and FIG9C, it also includes cases where it is formed discontinuously. One example of a discontinuous formation is the use of components such as rivets or seam plates that achieve the fastening function after stamping, which is ideal. In this way, the electromagnetic steel plate can be fastened by the fastening sub-conductor 10D, achieving a structure integrated with the fastening part. Furthermore, as an example of the material used, brass, which has excellent strength, can also be used.

[0054] Furthermore, in this embodiment, the same effect as in Embodiment 4 can be achieved at the location where the fixed sub-conductor 10D is located.

[0055] Furthermore, in the entire description of this application, the stator conductor may not necessarily be connected to the fastening part, and may be set independently at a distance from the fastening member when viewed along the radial direction of the stator.

[0056] Furthermore, throughout the entire description of this application, it is sufficient to have at least one low-resistance fastening member. Also, the spacing is not limited to equal spacing, but also includes cases of unequal spacing.

[0057] The ideas and concepts of the present invention have been described above using various embodiments. Of course, examples implemented by combining embodiments are also included within the scope of the present invention. Furthermore, any variations or similar examples using the disclosed ideas or concepts are also included within the scope of the present invention.

[0058] Furthermore, one example of the invention of this application described using the above embodiments may be presented as follows.

[0059] <1> A rotary electric machine having a stator and a rotor disposed inside the stator, the stator having a stator core, stator slots disposed circumferentially in the stator core, and stator windings disposed in the stator slots, the rotor having a central shaft, rotor slots, and rotor conductors, and the stator having a low-resistance fastening member on the outer periphery of the stator core, the low-resistance fastening member having a fastening portion disposed outside the stator and a stator conductor disposed inside it, the resistance of the stator conductor being lower than the resistance of the fastening portion. <2> The rotary electric machine of <1> wherein the strength of the fastening portion is higher than the strength of the stator conductor. <3> The rotary electric machine of <1> or <2> wherein a stator short-circuit ring is provided in the radial direction of the rotary electric machine to short-circuit the low-resistance fastening members. <Item 4> As in <Item 3>, the resistance of the aforementioned stator short-circuit ring is lower than the resistance of the aforementioned fastening portion. <Item 5> As in <Item 4>, the aforementioned stator short-circuit ring is disposed on both sides or both ends of the axial direction by the aforementioned low-resistance fastening member. <Item 6> As in <Item 1> or <Item 2>, the rotary motor has a housing disposed outside the aforementioned stator, and at least one of the aforementioned housing and the aforementioned fastening portion is a magnetic material. <Item 7> As in <Item 3>, the rotary motor has a housing disposed outside the aforementioned stator, and at least one of the aforementioned housing and the aforementioned fastening portion is a magnetic material. <Item 8> A rotary electric machine having a stator and a rotor disposed inside the stator, the stator having a stator core, stator slots disposed circumferentially in the stator core, and stator windings disposed in the stator slots, the rotor having a central shaft, rotor slots, and rotor conductors, and the stator having a fixed rotor conductor on the outer periphery of the stator core, and the rotary electric machine having a housing disposed outside the stator, at least one of the housing and the fixed rotor conductor being magnetic. <Item 9> The rotary electric machine of <Item 8>, wherein the fixed rotor conductor has a lower resistance than the housing. <Item 10> The rotary electric machine of any one of <Item 8> or <Item 9>, wherein the fixed rotor conductor is opposed to the housing, separating the stator core. <Item 11> The rotary electric machine of <Item 10>, wherein the fixed rotor conductor has a formed portion and a non-formed portion. <Item 12> The rotary motor of <Item 11> wherein the aforementioned forming part is composed of rivets or seam plates. <Item 13> The rotary motor of <Item 8> wherein the aforementioned housing is a magnetic body and the aforementioned fastening dowel conductor is brass. [Simplified Explanation of the Diagram]

[0010] Figure 1A is a sectional view of Figure 2 (BB) showing the main part of the rotating electric machine. Figure 1B is an enlarged view of part EX1 in Figure 1A. Figure 2A is a sectional view of Figure 1 (AA) showing the main part of the rotating electric machine. Figure 2B is an enlarged view of part EX2 in Figure 2A. Figure 3 is a sectional view of Figure 2 (CC) showing the outer side of the rotating electric machine along its axial direction. Figure 4 is a diagram illustrating the principle of how the magnetic field generated by the eddy currents in the stator conductors cancels the magnetic flux linked at the fastening part. Figure 5A is a sectional view of the main part of the rotating electric machine. Figure 5B is an enlarged view of part EX3 in Figure 5A. Figure 6A is a sectional view of Figure 7 (EE) showing the main part of the rotating electric machine. Figure 6B is an enlarged view of part EX4 in Figure 6A. Figure 7A is a sectional view of Figure 6 (DD) showing the main part of the rotating electric machine. Figure 7B is an enlarged view of part EX5 in Figure 7A. Figure 8A is a sectional view of Figure 9 (GG) showing the main part of the rotating electric machine. Figure 8B is an enlarged view of part EX6 in Figure 8A. Figure 9A is a sectional view of the main part of the rotary electric machine shown in Figure 8. Figure 9B is an enlarged view of part EX7 in Figure 9A. Figure 9C is an enlarged view of part EX7 in Figure 9A, and is a view at a position offset from Figure 9B.

Claims

1. A rotary electric machine having a stator and a rotor disposed inside the stator, the stator having a stator core, stator slots disposed circumferentially in the stator core, and stator windings disposed in the stator slots, the rotor having a central shaft, rotor slots, and rotor conductors, and the stator having a low-resistance fastening member on the outer periphery of the stator core, the low-resistance fastening member having a fastening portion disposed outside the stator and a stator conductor disposed inside it, the fastening portion and the stator conductor extending axially along the entire length of the stator core, and the resistance of the stator conductor being lower than the resistance of the fastening portion.

2. The rotating motor of claim 1, wherein the strength of the aforementioned fastening part is higher than the strength of the aforementioned stator conductor.

3. The rotary motor of claim 1 or 2, wherein a stator short-circuit ring is provided in the radial direction of the rotary motor to short-circuit the aforementioned low-resistance fastening members.

4. The rotating motor as claimed in claim 3, wherein the resistance of the aforementioned stator short-circuit ring is lower than the resistance of the aforementioned fastening part.

5. The rotary motor as claimed in claim 4, wherein the aforementioned stator short-circuit ring is disposed on both sides or both ends of the axial direction by means of the aforementioned low-resistance fastening member.

6. The rotary motor of claim 1 or 2, having a housing disposed outside the aforementioned stator, wherein at least one of the aforementioned housing and the aforementioned fastening portion is a magnetic material.

7. The rotary motor of claim 3, having a housing disposed outside the aforementioned stator, wherein at least one of the aforementioned housing and the aforementioned fastening portion is a magnetic material.

8. A rotary electric machine having a stator and a rotor disposed inside the stator, the stator having a stator core, stator slots disposed circumferentially in the stator core, and stator windings disposed in the stator slots, the rotor having a central shaft, rotor slots, and rotor conductors, and the stator having a fixed rotor conductor on the outer periphery of the stator core, the fixed rotor conductor extending axially along the entire length of the stator core, and the rotary electric machine having a housing disposed outside the stator, at least one of the housing and the fixed rotor conductor being a magnetic material.

9. The rotary motor of claim 8, wherein the aforementioned fastener conductor has a lower resistance than the aforementioned housing.

10. The rotating electric motor as claimed in either claim 8 or 9, wherein the aforementioned fixed stator conductor separates the aforementioned stator core from the aforementioned housing.

11. The rotary motor of claim 10, wherein the aforementioned fastening guide system is composed of rivets or mortise plates.

12. The rotary motor of claim 8, wherein the aforementioned housing is a magnetic material and the aforementioned fastening conductor is brass.

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