JP2018129950A - Rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an outer rotor-type rotary electric machine capable of obtaining high torque during a high load, while reducing a counter electromotive voltage and an iron loss during no-load or a low load.SOLUTION: A rotary electric machine 10 includes a stator 14, an annular outer rotor 18 disposed on an outer periphery of the stator 14, and in which multiple core pieces 38 and multiple outer magnets 40 are arranged side-by-side alternately in a circumferential direction, and a short circuit member (first member 42) being disposed at an outside in a radial direction of the outer magnets 40, and magnetically short-circuiting two core pieces 38 located at both sides of each outer magnet 40 in the circumferential direction. Each outer magnet 40 is magnetized in the circumferential direction, and in an opposite direction to the circumferential direction to the other outer magnet 40 adjacent in the circumferential direction, and the short circuit member is composed of a soft magnetic material having a maximum permeability higher than that of the core pieces 38, and saturation magnetization smaller than that of the core pieces 38.SELECTED DRAWING: Figure 3

Description

  The present application discloses a rotating electrical machine provided with a stator, an annular outer rotor disposed on the outer periphery of the stator.

  Conventionally, a permanent magnet type rotating electrical machine using a permanent magnet as a magnetic pole of a rotor is widely known. Generally, in a permanent magnet type rotating electrical machine, in order to obtain a high torque, it is necessary to increase the amount of magnetic flux (magnet magnetic flux) of a permanent magnet flowing through a stator. On the other hand, when the amount of magnet magnetic flux flowing through the stator is large when the current flowing through the stator coil is zero or small, no load, or low load, there is a problem that the back electromotive voltage and iron loss increase. The back electromotive force can be suppressed by performing field weakening control. However, when field weakening control is performed, it is necessary to separately supply a negative d-axis current that is used for field weakening and does not contribute to output, resulting in an increase in copper loss. Was invited.

  Patent Document 1 discloses a variable magnetic flux type rotating electrical machine in which the amount of magnet magnetic flux (linkage magnetic flux) flowing through the stator is variable. The rotating electrical machine of Patent Document 1 is an inner rotor type in which a rotor is arranged inside a stator, and the rotor has a permanent magnet magnetized in the radial direction. An electrical gap is formed between two adjacent permanent magnets in the rotor core. A magnetic flux bypass path formed by the two adjacent permanent magnets is formed between the gap and the outer peripheral edge of the rotor core. The magnetic flux bypass path is wider and has a lower magnetic resistance than the magnetic path formed between the gap and the permanent magnet. Therefore, when no current is supplied, a part of the magnetic flux emitted from the permanent magnet leaks to the adjacent permanent magnet via the magnetic flux bypass path. The leakage of the magnet magnetic flux is suppressed by the electron reaction when the stator coil is energized. As a result, when rotating in a no-load or low-load state, the amount of magnet magnetic flux flowing through the stator can be reduced, and the back electromotive voltage and iron loss can be reduced. In addition, when rotating at a high load, the magnetic flux leaking to the magnetic flux bypass decreases and the interlinkage magnetic flux increases, so that a high torque can be obtained.

Special table 2015-521838 gazette

  Here, among the rotating electrical machines, as disclosed in Patent Document 1, in addition to the inner rotor type rotating electrical machine in which the rotor is disposed inside the stator, the outer rotor type rotating electrical machine in which the rotor is disposed outside the stator. There is also. In the case of the outer rotor type, even if the radial thickness of the rotor is the same as that of the inner rotor type, the centrifugal force generated with rotation increases. For this reason, the outer rotor type is required to keep the radial thickness of the rotor small compared to the inner rotor type.

  In the technique disclosed in Patent Document 1, it is necessary to provide a magnetic flux bypass having a sufficient width between the electrical gap and the outer periphery of the rotor. Such a technique is effective in the inner rotor type in which the rotor has a large radial thickness. However, as described above, it is difficult to apply the technique of Patent Document 1 in the outer rotor type in which the radial thickness is required to be kept small in relation to the centrifugal force.

  Therefore, an object of the present application is to obtain an outer rotor type rotating electrical machine that can obtain a high torque at a high load and reduce a back electromotive voltage and an iron loss at a no load or a low load.

  A rotating electrical machine disclosed in the present application is a stator, an annular outer rotor disposed around an outer periphery of the stator, and an outer rotor in which a plurality of core pieces and a plurality of outer magnets are alternately arranged in a circumferential direction, and the outer A short-circuit member that is arranged on the radially outer side of the magnet and magnetically short-circuits two core pieces located on both sides of the outer magnet in the circumferential direction, and the outer magnet is adjacent to the circumferential direction and the circumferential direction. Magnetized in the circumferential direction opposite to the other outer magnet, the short-circuit member is made of a soft magnetic material having a maximum magnetic permeability higher than that of the core piece, and has a saturation magnetization smaller than that of the core piece. To do.

  With such a configuration, a part of the magnet magnetic flux is short-circuited via the short-circuit member in a no-load or low-load state where there is no or little current magnetic flux. As a result, the magnet magnetic flux flowing through the stator is lowered in a no-load / low-load state, and the back electromotive voltage and iron loss can be reduced. In a high load state where the current magnetic flux increases, the short-circuit member is magnetically saturated with the current magnetic flux, so that the short-circuited magnet magnetic flux decreases and the magnet magnetic flux flowing through the stator increases. As a result, a high torque can be output in a high load state.

  The outer magnet is arranged so that an outer peripheral edge thereof is radially inward from an outer peripheral edge of the core piece, and the short-circuit member has circumferential end faces of the two core pieces. The first member may be made of a soft magnetic material that is disposed so as to be in contact with or in close proximity to the core and has a maximum magnetic permeability higher than that of the core piece and has a saturation magnetization smaller than that of the core piece in contact with or in close proximity.

  By adopting such a configuration, the magnetic resistance of the short circuit magnetic path of the magnet magnetic flux is reduced, and the magnet magnetic flux flowing through the stator can be further reduced in a no-load / low-load state. As a result, the back electromotive voltage and the iron loss can be further reduced in the no-load / low-load state.

  The short-circuit member is arranged so that an inner peripheral surface thereof is in contact with or in close proximity to an outer peripheral surface of the two core pieces, and is made of a soft magnetic material having a maximum magnetic permeability higher than that of the core piece and the contact. Alternatively, a second member having a saturation magnetization smaller than that of the adjacent core pieces may be included.

  In this case, the second member may be a fixing outer cylinder that surrounds and fixes the outer periphery of the outer rotor.

  With this configuration, it is not necessary to provide a second member separately from the fixing outer cylinder, and the number of parts and cost of the rotating electrical machine can be reduced.

  The short-circuit member and the core piece may be close to each other via a gap.

  In such a configuration, the change characteristic of the linkage flux with respect to the load state can be adjusted by adjusting the size of the gap.

  According to the rotating electrical machine disclosed in the present application, a part of the magnet magnetic flux is short-circuited via the short-circuit member in a no-load or low-load state where there is no or little current magnetic flux. As a result, the magnet magnetic flux flowing through the stator is lowered in a no-load / low-load state, and the back electromotive voltage and iron loss can be reduced. In a high load state where the current magnetic flux increases, the short-circuit member is magnetically saturated with the current magnetic flux, so that the short-circuited magnet magnetic flux decreases and the magnet magnetic flux flowing through the stator increases. As a result, a high torque can be output in a high load state.

It is a schematic longitudinal cross-sectional view of a rotary electric machine. It is a schematic cross-sectional view of a rotary electric machine. It is the A section enlarged view of FIG. It is an image figure which shows the flow of the magnet magnetic flux in a low load state. It is an image figure which shows the flow of the magnet magnetic flux in a high load state. It is a figure which shows the simulation result of the magnet magnetic flux in a no-load state. It is a figure which shows the simulation result of the current magnetic flux in a high load state. It is a figure which shows the simulation result of the magnet magnetic flux in a high load state. It is a figure which shows another example of an outer rotor. It is a figure which shows another example of an outer rotor.

  Hereinafter, the rotating electrical machine 10 disclosed in the present application will be described with reference to the drawings. In the following, a dual rotor type rotating electrical machine having a rotor on both the inside and outside of the stator will be described as an example, but the technology of the present application is an outer rotor having a rotor arranged on the outside of the stator. As long as it is a type, it may be applied to either a dual rotor type or a single rotor type.

  FIG. 1 is a schematic longitudinal sectional view of the rotating electrical machine 10. FIG. 2 is a schematic cross-sectional view of the rotating electrical machine 10. FIG. 3 is an enlarged view of a portion A in FIG. The rotating electrical machine 10 is a dual rotor type rotating electrical machine having one stator 14 and two rotors 16 and 18. More specifically, as shown in FIGS. 1 and 2, the inner rotor 16 is fixed to the outer peripheral surface of the rotating shaft 20, and the stator 14 is disposed on the outer periphery of the inner rotor 16. An outer rotor 18 is disposed around the outer periphery of the outer rotor.

  The outer rotor 18 is fixed to the rotary shaft 20 via the connecting member 22. The connecting member 22 is a substantially flat plate member that is inserted into and fixed to the rotating shaft 20. An annular rib 22 a extending toward the outer rotor 18 is provided from the surface of the connecting member 22 facing the outer rotor 18. The front end surface of the annular rib 22a is fixed to the end surface of the outer rotor 18 in the axial direction. Then, the force for rotating the outer rotor 18 is transmitted to the rotary shaft 20 via the connecting member 22. In addition, the structure of the connection member 22 shown here is an example, and if the rotational force of the outer rotor 18 and the inner rotor 16 is transmitted to the rotating shaft 20, another structure may be sufficient. For example, the connecting member 22 may be fixed to the inner rotor 16 instead of the rotating shaft 20. In this case, the rotational force of the outer rotor 18 is applied to the rotating shaft 20 via the connecting member 22 and the inner rotor 16. Communicated. As another form, the inner rotor 16 may not be fixed to the rotating shaft 20, the inner rotor 16 and the outer rotor 18 may be fixed to the connecting member 22, and the connecting member 22 may be fixed to the rotating shaft 20. . In any case, in the dual rotor type rotating electrical machine 10, the rotational force of the inner rotor 16 and the outer rotor 18 is transmitted to one rotating shaft 20.

  The stator 14 includes a stator core 26 and a stator coil 28 wound around the stator core 26. As shown in FIG. 2, the stator core 26 includes an annular yoke 29, a plurality of inner teeth 30 projecting radially inward from the inner periphery of the yoke 29, and a plurality projecting radially outward from the outer periphery of the yoke 29. The outer teeth 32 are roughly divided. A space between two adjacent inner teeth 30 is an inner slot 31, and a space between two adjacent outer teeth 32 is an outer slot 33.

  The arrangement pitch angle and phase of the inner teeth 30 are the same as the arrangement pitch angle and phase of the outer teeth 32. In the illustrated example, the inner teeth 30 and the outer teeth 32 are both arranged in the circumferential direction at intervals of 15 degrees, and as a whole, 24 inner teeth 30 and 24 outer teeth 32 are provided. That is, the number of slots is 24 on both the inside and outside. The stator core 26 is composed of a plurality of electromagnetic steel plates (for example, silicon steel plates). The plurality of electromagnetic steel plates are positioned and joined to each other to constitute the stator core 26.

  Stator coil 28 is composed of three-phase coils, that is, a U-phase coil, a V-phase coil, and a W-phase coil. One end of each of the three-phase coils is connected to an input / output terminal (not shown), and the other end of each of the three-phase coils is coupled to each other to form a neutral point. That is, the stator coil 28 is star-connected. Of course, instead of the star connection, other connection modes such as a delta connection may be adopted.

  Windings constituting the coils of each phase are wound around the stator core 26. As a winding method of the winding, distributed winding in which the winding is wound over a plurality of slots, concentrated winding in which the winding is wound around one tooth, toroidal winding in which the winding is wound around the yoke 29, etc. It has been known. In this embodiment, the winding is wound by toroidal winding, that is, the winding is wound around the yoke 29. In this case, when a current is applied to the stator coil 28, the polarity of the magnetic field formed on the outer teeth 32 side and the polarity of the magnetic field formed on the inner teeth 30 side are reversed. However, the winding may be wound by concentrated winding or distributed winding as necessary. In any case, hereinafter, the magnetic flux generated when current is applied to the stator coil 28 will be referred to as “current magnetic flux”.

  The inner rotor 16 is a rotor disposed inside the stator 14, and includes an annular inner core 34 and an inner magnet 36 embedded in the inner core 34. The inner core 34 is configured by laminating a plurality of electromagnetic steel plates (for example, silicon steel plates). The inner magnet 36 is a permanent magnet that constitutes the magnetic pole of the inner rotor 16. The inner magnet 36 has a substantially rectangular shape that is flat when viewed in the axial direction, and is magnetized in the short side direction. The shape, number, arrangement position, and the like of the inner magnet 36 are not particularly limited, but it is desirable that the number of magnetic poles of the inner rotor 16 is the same as the number of magnetic poles of the outer rotor 18 as will be described later. In the present embodiment, the inner rotor 16 is provided with eight magnetic poles, and one magnetic pole is composed of two inner magnets 36 arranged in a substantially V shape that opens outward in the radial direction. Accordingly, the inner rotor 16 as a whole is provided with twice the number of magnetic poles, that is, 16 inner magnets 36. Further, it is desirable that the d axis Ldi of the inner rotor 16 and the d axis Ldo of the outer rotor 18 coincide. Here, the d-axis Ldi of the inner rotor 16 is a straight line connecting the circumferential center of the gap between the two inner magnets 36 constituting one magnetic pole and the center point of the rotating electrical machine 10.

  The outer rotor 18 is a rotor disposed on the outer periphery of the stator 14 and includes core pieces 38 and outer magnets 40 that are alternately arranged in the circumferential direction. The plurality of core pieces 38 and the outer magnet 40 are alternately arranged to form a substantially annular shape. Each core piece 38 is configured by laminating a plurality of electromagnetic steel plates (for example, silicon steel plates).

  The outer magnet 40 is a permanent magnet that constitutes the magnetic pole of the outer rotor 18. Since the outer magnet 40 is a permanent magnet, naturally, a constant magnetic flux is always generated from the outer magnet 40. Hereinafter, the magnetic flux generated from the outer magnet 40 is referred to as “magnet magnetic flux”, and among the magnetic flux, the magnetic flux that flows through the stator 14 and is linked to the stator coil 28 is referred to as “linkage magnetic flux”.

  The outer magnet 40 is substantially rectangular when viewed in the axial direction, and is arranged in such a posture that one side thereof is substantially parallel to the circumferential direction. Each outer magnet 40 is magnetized in a substantially circumferential direction. That is, the outer magnet 40 has an N pole at one circumferential direction and an S pole at the other circumferential end. Further, the magnetization directions of the two outer magnets 40 adjacent in the circumferential direction are opposite to each other in the circumferential direction. That is, the opposing surfaces of the two outer magnets 40 adjacent to each other in the circumferential direction are magnetized in such directions that they have the same pole. In this case, one magnetic pole is comprised in the circumferential direction one side part of each of the two outer magnets 40 adjacent to the circumferential direction. In other words, one outer magnet 40 constitutes part of one N magnetic pole and part of one S magnetic pole. A straight line connecting the circumferential center of the gap between the two adjacent outer magnets 40 and the center point of the rotating electrical machine 10 is the d-axis Ldo of the outer rotor 18.

  In this example, the number of magnetic poles of the outer rotor 18 is the same as the number of magnetic poles of the inner rotor 16. Therefore, eight outer magnets 40 are provided in the entire outer rotor 18. In the present embodiment, the d-axis Ldo of the magnetic pole of the outer rotor 18 and the d-axis Ldi of the magnetic pole of the inner rotor 16 are matched. Thus, if the two d-axes Ldo and Ldi are made to coincide, the angular relationship of the magnetic poles of the rotors 16 and 18 with respect to the rotating magnetic field of the stator 14 can be made the same on the outer side and the inner side. As a result, it is not necessary to switch between current and voltage control on the outer side and the rotor side. In the present embodiment, the polarity of the rotating magnetic field formed in the stator 14 is reversed between the inner side and the outer side due to the toroidal winding of the stator coil 28. In this case, the magnetic poles of the inner rotor 16 and the outer rotor 18 that are opposed in the radial direction across the stator 14 have the same polarity. That is, the N magnetic pole of the inner rotor 16 is disposed on the opposite side of the N magnetic pole of the outer rotor 18 with the stator 14 interposed therebetween, and the inner rotor is disposed on the opposite side of the S magnetic pole of the outer rotor 18 with the stator 14 interposed therebetween. Sixteen S magnetic poles are arranged.

  As described above, the stator coil 28 may be distributed winding or concentrated winding in which the winding is wound around the teeth 30 and 32 instead of the toroidal winding in which the winding is wound around the yoke 29. In the case of distributed winding or concentrated winding wound around the teeth 30 and 32, a winding method in which the winding directions of the windings are opposite to each other on the outer side and the inner side, and a winding method in which the winding directions are the same. There is. When the winding direction of the winding is the outer / inner, and the directions are reversed, the polarities of the rotating magnetic field generated by applying the current are opposite to each other at the outer / inner. In this case, it is desirable that the magnetic poles of the inner rotor 16 and the outer rotor 18 that are opposed in the radial direction across the stator 14 have the same polarity as in the case of toroidal winding. On the other hand, when the winding direction of the winding is the same for the outer / inner, the polarities of the rotating magnetic field generated by applying the current are the same for the outer / inner. In this case, it is desirable that the polarities of the magnetic poles of the inner rotor 16 and the outer rotor 18 that are radially opposed to each other with the stator 14 interposed therebetween are opposite to each other in the case of toroidal winding.

  The rotating electrical machine 10 further includes a short-circuit member that magnetically short-circuits the two core pieces 38 positioned on both sides in the circumferential direction with the outer magnet 40 interposed therebetween. Although various forms of the short-circuit member can be considered, in this example, the first member disposed on the radially outer side of the outer magnet 40 is used as the short-circuit member.

  That is, as is apparent from FIG. 3, in this example, the radial thickness of the outer magnet 40 is smaller than the radial thickness of the core piece 38. The outer peripheral edge of the outer magnet 40 is located on the radially inner side with respect to the outer peripheral edge of the core piece 38, and the inner peripheral edge of the outer magnet 40 is located on the radially outer side with respect to the inner peripheral edge of the core piece 38. From another viewpoint, a concave portion surrounded by the circumferential end surfaces of the pair of core pieces 38 and the outer peripheral surface of the outer magnet 40 is formed on the outer side in the radial direction of the outer magnet 40. The first member 42 is disposed in the recess.

  Both end surfaces in the circumferential direction of the first member 42 are in contact with circumferential end surfaces of the two core pieces 38, and the first member 42 has a magnetic path of magnetic flux flowing from one core piece 38 to the other core piece 38. Configure. The first member 42 is made of a soft magnetic material having a maximum magnetic permeability higher than that of the core piece 38, and has a lower saturation magnetization than the two core pieces 38 that are in contact with each other. Therefore, the short-circuit member (first member 42) is more likely to cause a magnetic flux to flow at a light load than the core piece 38, and magnetic saturation is likely to occur at a high load. The reason for providing such a short-circuit member (first member 42) is to make the amount of flux linkage variable according to the load state, which will be described in detail later.

  The rotating electrical machine 10 of this example further includes a fixing outer cylinder 44 that surrounds and fixes the outer periphery of the core piece 38. The fixing outer cylinder 44 is provided to prevent the core piece 38 and the outer magnet 40 from being separated by surrounding and restraining the core piece 38 and the outer magnet 40. The fixing outer tube 44 is made of a nonmagnetic material, such as stainless steel. The fixing outer cylinder 44 may be made of a soft magnetic material as will be described in detail later. In this case, the fixing outer cylinder 44 is a short-circuit member that magnetically short-circuits the two core pieces 38. Act as part.

  Next, in the outer rotor 18, the reason why the outer magnet 40 is magnetized in the circumferential direction and the short-circuit member (first member 42) is disposed on the outer peripheral side of the outer magnet 40 will be described. Of course, the outer rotor 18 is disposed on the radially outer side of the stator 14, so that the distance from the center of rotation is large, and the centrifugal force accompanying the rotation tends to increase. Therefore, in order to suppress an increase in centrifugal force, the outer rotor 18 is required to suppress the radial thickness as compared with the inner rotor 16.

  In addition, a current magnetic flux is generated in accordance with the current application to the stator coil 28. A part of the current magnetic flux is radially directed from the outer teeth 32 to the outer rotor 18 or from the outer rotor 18 to the outer teeth 32. Proceed to Therefore, when the outer magnet 40 is magnetized in the radial direction, a so-called “reverse magnetic field” in which a current magnetic flux flows in a direction opposite to the magnetization direction of the outer magnet 40 is generated. When such a reverse magnetic field is generated, demagnetization occurs in which the magnetic force of the outer magnet 40 is reduced. And demagnetization of the outer magnet 40 causes a decrease in magnet torque, and consequently a decrease in output torque of the rotating electrical machine 10.

  In the rotating electrical machine 10 disclosed in the present application, as described above, the outer magnet 40 is magnetized in the circumferential direction. Therefore, compared to the case of magnetizing in the radial direction, the radial thickness of the outer magnet 40 can be easily suppressed, and consequently the radial thickness of the outer rotor 18 can be suppressed. Further, by magnetizing the outer magnet 40 in the circumferential direction, a reverse magnetic field in which the current magnetic flux advances in the direction opposite to the magnetization can be suppressed, and demagnetization of the outer magnet 40 can be effectively prevented.

  Incidentally, in order to increase the output torque of the rotating electrical machine 10, it is necessary to increase the amount of magnet magnetic flux flowing into the stator 14, that is, the amount of flux linkage. On the other hand, when the amount of flux linkage is large, there is a problem that the back electromotive voltage and iron loss increase in a state where the current flowing through the stator coil 28 is zero or small, that is, in a no-load state or a low load state. The back electromotive force can be suppressed by performing field weakening control. However, when field weakening control is performed, it is necessary to separately supply a negative d-axis current for field weakening that does not contribute to the output, which increases copper loss. Invite.

  That is, it is desirable that the amount of flux linkage be variable according to the load state so that it is large in a high load state / high torque output state and small in a no load / low load state. Therefore, in the rotating electrical machine 10 disclosed in the present application, the first member 42 that functions as a short-circuit member is provided on the radially outer side of the outer magnet 40 in order to make the amount of interlinkage magnetic flux variable according to the load state. .

  As described above, the first member 42 is made of a soft magnetic material having a maximum magnetic permeability higher than that of the core piece 38, and has a saturation magnetization smaller than that of the core piece 38. The flow of the magnet magnetic flux when the first member 42 is provided will be described with reference to FIGS. 4 and 5, the broken line indicates the flow of the magnet magnetic flux. 4 shows a no-load state, and FIG. 5 shows a high-load state.

  In the no-load state or the low-load state, as shown in FIG. 4, a part of the magnet magnetic flux has a high maximum magnetic permeability and is smaller in magnetic resistance than the core piece 38 and easily flows into the first member 42. And flow. As a result, part of the magnet magnetic flux emitted from one end (N pole) of the outer magnet 40 flows to the other end (S pole) of the outer magnet 40 without flowing to the stator 14. That is, a part of the magnet magnetic flux is short-circuited without flowing to the stator 14. As described above, when a part of the magnet magnetic flux is short-circuited, the amount of magnet magnetic flux that flows to the stator 14, that is, the amount of interlinkage magnetic flux, is significantly reduced as compared with the case where the first member 42 is not provided.

  On the other hand, in a high load state in which a relatively large current is passed through the stator coil 28, as shown in FIG. Flows to the stator 14. This is because a large amount of current magnetic flux (magnetic flux having a high magnetic flux density) is generated in a high load state. The current magnetic flux generated in a large amount flows to the first member 42 with priority over the magnet magnetic flux. Further, since the saturation magnetization of the first member 42 is lower than the saturation magnetization of the core piece 38, the first member 42 is magnetically saturated before the core piece 38. As a result, in the high load state, the first member 42 is likely to be magnetically saturated by the current magnetic flux. When the first member 42 is magnetically saturated with the current magnetic flux, most of the magnetic flux does not flow to the first member 42 but flows to the stator 14. As a result, the amount of flux linkage can be kept large in a high load state.

  That is, in the rotating electrical machine 10 disclosed in the present application, a short-circuit member (first member 42) having a high maximum magnetic permeability and a small saturation magnetization is provided outside the outer magnet 40 in the radial direction. It can be large in a high load state and high torque output state, and small in a no load state or a low load state. As a result, the outer rotor type rotating electrical machine can output a high torque in a high load state while suppressing the occurrence of a counter electromotive voltage and iron loss in a no load or low load state.

  Next, simulation results of the flow of magnetic flux in the rotating electrical machine 10 illustrated in FIGS. 1 to 3 will be described. 6 shows a simulation result of the magnet magnetic flux in the no-load state, FIG. 7 shows a simulation result of the magnetic flux in the high load state, and FIG. 8 shows a simulation result of the magnet magnetic flux in the high load state. 6 to 8, the black density indicates the magnetic flux density, and the darker the black color, the higher the magnetic flux density.

  As shown in FIG. 6, in the no-load state, a part of the magnet magnetic flux generated by the outer magnet 40 passes from one end in the circumferential direction of the outer magnet 40 to the outer side in the radial direction of the outer magnet 40. Head to the end. That is, a part of the magnet magnetic flux is short-circuited without flowing to the stator 14. And since a part of magnet magnetic flux is short-circuited, the amount of flux linkage can be reduced and the back electromotive force and iron loss can be effectively suppressed.

  On the other hand, in a high load state, as shown in FIG. 7, the current magnetic flux flows into the first member 42, and the first member 42 is magnetically saturated. Therefore, as shown in FIG. 8, the magnet magnetic flux hardly flows into the first member 42, and most of the magnetic flux flows into the stator 14. As a result, in a high load state, the amount of flux linkage can be increased, and a high torque can be obtained.

  Further, the applicant of the present application simulated the loss amount in each of the high load state and the low load state. As a result, the loss amount in the high load state is almost the same regardless of the presence or absence of the short circuit member (first member), but the loss amount in the low load state is compared with the case where the short circuit member is not provided. It was found that the case where the short-circuit member was provided was lowered by about 10 to 20%. That is, according to the rotating electrical machine 10 disclosed in the present application, it is possible to reduce the amount of loss in the no-load / low-load state while preventing an increase in the loss amount in the high load state, and to improve the efficiency of the entire rotating electrical machine 10.

  The configuration described so far is only an example, and a short-circuit member made of a material having a maximum magnetic permeability higher than that of the core piece 38 and having a saturation magnetization smaller than that of the core piece 38 is arranged outside the outer magnet 40 in the radial direction. Other configurations may be changed as appropriate.

  For example, in the above description, the example in which the first member 42 that contacts the circumferential end surface of the core piece 38 is provided. However, instead of or in addition to the first member 42, the outer peripheral surface of the core piece 38 is contacted. A second member may be provided. For example, as shown in FIG. 9, instead of providing the first member 42, a second member 46 that contacts the outer peripheral surface of the core piece 38 may be provided. The second member 46 is made of a soft magnetic material having a maximum magnetic permeability higher than that of the core piece 38 and has a saturation magnetization smaller than that of the core piece 38 that is in contact with or close to the second member 46. The second member 46 may be provided separately from the fixing outer cylinder 44 that surrounds and fixes the outer periphery of the outer rotor 18, or the fixing outer cylinder 44 may be provided as the second member 46.

  Even in this case, in the no-load / low-load state, part of the magnet magnetic flux flows to the second member 46 and is short-circuited, so that the amount of flux linkage can be reduced. Moreover, if it becomes a high load state, since the 2nd member 46 will be magnetically saturated with a current magnetic flux and a magnet magnetic flux will become difficult to flow into the 2nd member 46, the amount of flux linkages will become large. That is, even in this case, the flux linkage is small in the no-load / low-load state and large in the high-load state. As a result, high torque can be obtained in a high load state while suppressing a back electromotive voltage and iron loss in a no-load / low-load state.

  However, the distance between the second member 46 and the outer magnet 40 is greater than that of the first member 42, and the magnetic flux of the magnet magnetic flux is greater when the second member 46 is used than when the first member 42 is used. The short circuit magnetic path becomes longer and the magnetic resistance becomes higher. As a result, compared to the case where the first member 42 is used, when the second member 46 is used, the magnetic flux is not short-circuited earlier (at a stage where the current value is low), and the amount of flux linkage is increased. . In other words, it can be said that providing the second member 46 instead of the first member 42 is more advantageous for operation in a high load state.

  On the other hand, when the first member 42 is used as the short-circuit member instead of the second member 46, the magnetic resistance of the short-circuit magnetic path of the magnet magnetic flux is reduced. Therefore, the short-circuit amount of the magnet magnetic flux can be increased, and the back electromotive voltage and the iron loss in the no-load / low-load state can be more effectively suppressed as compared with the case of FIG. In other words, it can be said that the case where only the first member 42 is provided without providing the second member 46 is more advantageous for reducing the loss in the no-load / low-load state.

  Further, the second member 46 may be provided together with the first member 42. In this case, the magnetic resistance of the short-circuit magnetic path of the magnet magnetic flux is reduced, and the volume of the entire short-circuit member (the first member 42 and the second member 46) is increased, so that the saturation magnetization is increased. As a result, the short-circuit amount of the magnet magnetic flux can be increased, and the back electromotive voltage and iron loss in the no-load / low-load state can be more effectively suppressed as compared with the cases of FIGS. Further, since the short-circuit member is not magnetically saturated until the load becomes relatively high, the state in which the back electromotive voltage and the iron loss are suppressed can be maintained until the current becomes relatively high.

  In the description so far, the short-circuit members (the first member 42 and the second member 46) are brought into contact with the core piece 38, but a gap G is provided between the short-circuit member and the core piece 38. Also good. That is, the short-circuit member and the core piece 38 may be configured to face each other without contacting each other. For example, as shown in FIG. 10, a gap G may be provided between the circumferential end of the first member 42 and the circumferential end of the core piece 38. Then, by adjusting the size of the gap G, it is possible to adjust the magnetic resistance of the short-circuit magnetic path of the magnet magnetic flux, and thus to adjust the variable characteristic of the amount of flux linkage with respect to the load.

  Moreover, all the structures of the rotary electric machine 10 demonstrated so far are examples, and may be suitably changed according to the required specification. For example, the rotating electrical machine 10 may be a single rotor type / outer rotor type rotating electrical machine 10 that does not have the inner rotor 16. Further, the number of magnetic poles and the number of teeth mentioned in the above description may be changed as appropriate.

DESCRIPTION OF SYMBOLS 10 Rotating electrical machine, 14 Stator, 16 Inner rotor, 18 Outer rotor, 20 Rotating shaft, 22 Connecting member, 26 Stator core, 28 Stator coil, 29 York, 30 Inner teeth, 32 Outer teeth, 38 Core pieces, 40 Outer magnet, 42 First member, 44 outer cylinder for fixing, 46 second member.

Claims (5)

A stator,
An annular outer rotor disposed on the outer periphery of the stator, and an outer rotor in which a plurality of core pieces and a plurality of outer magnets are alternately arranged in the circumferential direction;
A short-circuit member that is arranged on the outer side in the radial direction of the outer magnet and magnetically short-circuits two core pieces located on both sides in the circumferential direction of the outer magnet;
With
The outer magnet is magnetized in the circumferential direction and in the circumferential direction opposite to the other outer magnet adjacent in the circumferential direction,
The short-circuit member is made of a soft magnetic material having a maximum magnetic permeability higher than that of the core piece, and has a saturation magnetization smaller than that of the core piece.
Rotating electric machine characterized by that. The rotating electrical machine according to claim 1,
The outer magnet is arranged so that its outer peripheral edge is radially inner than the outer peripheral edge of the core piece,
The short-circuit member is disposed so that both circumferential end surfaces thereof are in contact with or in close proximity to the circumferential end surfaces of the two core pieces, and is made of a soft magnetic material having a maximum magnetic permeability higher than that of the core piece, and the contact or Including a first member having a saturation magnetization smaller than that of the adjacent core pieces,
Rotating electric machine characterized by that. The rotating electrical machine according to claim 1 or 2,
The short-circuit member is arranged so that an inner peripheral surface thereof is in contact with or in close proximity to the outer peripheral surface of the two core pieces, and is made of a soft magnetic material having a maximum magnetic permeability higher than that of the core piece, and the contact or proximity Including a second member having a smaller saturation magnetization than the opposing core piece,
Rotating electric machine characterized by that. The rotating electrical machine according to claim 3,
The rotating electric machine according to claim 2, wherein the second member is a fixing outer cylinder that surrounds and fixes the outer periphery of the outer rotor. The rotating electrical machine according to any one of claims 1 to 4,
The rotating electrical machine, wherein the short-circuit member and the core piece are in close proximity to each other via a gap.