JP2014187776A - Stator core for rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress increase in magnetic resistance and loss increase even when a stress is applied to teeth in a stator core for a rotary electric machine.SOLUTION: A stator core 10 for a rotary electric machine includes: an annular yoke 12; a plurality of teeth 14 that are protruding from the yoke 12 toward inside in a radial direction. The yoke 12 includes slits 28 formed at an outside in the radial direction so as to at least retain a maximum width d1 in a circumferential direction of a root part 20 at a neighborhood of root parts of both ends in a circumferential direction of each tooth 14.

Description

  The present invention relates to a stator core for a rotating electrical machine including an annular yoke and a plurality of teeth projecting radially inward from the yoke, and more particularly to suppression of increase in magnetic resistance and increase in rotating electrical machine loss due to stress concentration.

  Patent Document 1 and Patent Document 4 describe a stator for a rotating electrical machine in which at least a part of a coil wound around a tooth is covered with a resin mold.

  Patent Document 2 describes a stator core formed by connecting a plurality of divided cores in an annular shape. A notch having a circular cross section is provided at a connecting portion with the root portion of the tooth among the yoke constituent portions of the split core.

  In Patent Document 3, in the stator core, a slit extending in the radial direction is formed at a circumferential intermediate portion of a bottom portion of a slot formed between adjacent teeth on the inner peripheral surface of the yoke, and passes through the radial inner side of the yoke. It describes that the difference between the magnetic resistance of the magnetic flux and the magnetic resistance of the magnetic flux passing through the radially outward side is reduced to suppress the occurrence of magnetic saturation.

  Patent Document 4 describes a stator core including a slit formed at the root of a tooth so as to be inclined with respect to the axial direction. Patent Document 4 also describes a stator core including a slit formed in a tooth so as to be inclined with respect to any of a circumferential direction, a radial direction, and an axial direction.

JP 2011-45178 A JP 2005-130605 A JP 2010-115095 A JP 2010-252453 A

  As in the stators described in Patent Document 1 and Patent Document 4, the air gap between the stator coil and the teeth is reduced by resin to improve the heat dissipation from the stator coil to the teeth, and the insulation from the outside is enhanced. A configuration in which at least a coil is resin-molded is known for the purpose of illustration. In this configuration, when resin molding is performed in the manufacturing die, compression stress or bending stress is generated by injecting the resin into the teeth, and the resin may be solidified in a state where the stress is generated. Further, even when the teeth are not resin-molded as in the stators described in Patent Document 2 and Patent Document 3, when a coil is wound around the teeth, compressive stress or bending stress may be generated in the teeth. In this case, stress concentrates because the vicinity of both ends in the circumferential direction of the root portion of the teeth protruding in the radial direction from the inner peripheral surface of the yoke is a portion where the shape changes greatly. For this reason, in the stators described in Patent Document 1 to Patent Document 4, stress concentrates on the root portion of the teeth having a high magnetic flux density. This concentration of stress makes it difficult for the magnetic flux to pass through, so that the magnetic resistance of the stator core increases, and further, iron loss increases due to magnetic saturation at the stress concentration portion. Since an increase in iron loss leads to an increase in rotating electrical machine loss, improvement is desired.

  An object of the present invention is to provide a stator core for a rotating electrical machine that can suppress an increase in magnetic resistance and an increase in rotating electrical machine loss even when stress is generated in the teeth.

  A stator core for a rotating electrical machine according to the present invention includes an annular yoke and a plurality of teeth projecting radially inward from the yoke, wherein the yoke is at least in the vicinity of root portions at both ends in the circumferential direction of the teeth. It includes a slit formed radially outward so as to maintain the circumferential maximum width of the root portion. In addition, “formed at the radially outer side so as to maintain at least the maximum circumferential width of the root portion” means that the circumferential width between the slits on both sides of the teeth is larger than the maximum circumferential width of the root portion of the teeth. This also includes providing a slit so as not to be small.

  In the stator core for a rotating electrical machine according to the present invention, preferably, the yoke includes a minimum width portion having a minimum radial width on the outer peripheral side in the circumferential direction between adjacent teeth, and the back end of the slit. The slit yoke outer diameter distance h3, which is the radial distance between the radial outer end position H and the outer peripheral surface of the yoke, is equal to or greater than the radial width h1 of the minimum width portion.

  Further, in the stator core for a rotating electrical machine according to the present invention, preferably, the yoke includes a minimum width portion having a minimum radial width on the outer circumferential side in the circumferential direction between adjacent teeth, The area of the rectangular magnetic path section S1 having the one side length as the slit yoke outer diameter distance h3 is equal to or larger than the area of the rectangular magnetic path section S2 having the radial width h1 of the minimum width portion as one side length. .

  In the stator core for a rotating electrical machine according to the present invention, preferably, in the yoke, the radial width on the outer circumferential side in the circumferential direction between the adjacent teeth is on the outer diameter side in the circumferential end between the adjacent teeth. It is smaller than the radial width.

  In the stator core for a rotating electrical machine according to the present invention, it is preferable that the slit is in the radial direction so as to maintain the maximum width in the circumferential direction of the root portion in the vicinity of the root portions at both circumferential ends of the teeth in the yoke. They are formed parallel to each other toward the outside.

  According to the stator core for a rotating electrical machine of the present invention, even when stress is applied to the teeth, the stress concentration portion is moved to the outer diameter side of the yoke from the inner peripheral end at the circumferential end portion of the slot bottom between the teeth. Since the concentration of the magnetic flux density at the concentrated portion can be alleviated, an increase in magnetic resistance and an increase in rotating electrical machine loss can be suppressed.

It is a perspective view of the stator core for rotary electric machines of embodiment of this invention. It is the A section enlarged view of FIG. It is the figure which looked at FIG. 2 in the axial direction. It is the C section enlarged view of FIG. FIG. 2 is a perspective view of a stator including the stator core of FIG. 1. It is a figure which exaggerates and shows a mode that compression stress is added to teeth at the time of resin molding, and is a figure equivalent to a BB section of Drawing 3. It is a figure which shows a mode that a magnetic flux flows into the yoke from teeth in embodiment of this invention, Comprising: It is a figure equivalent to FIG. It is a figure which shows the circumferential direction part of the stator core for rotary electric machines of a comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Hereinafter, a case where the rotating electrical machine is an electric motor will be described, but the rotating electrical machine may be a generator or a motor generator having both functions of the electric motor and the generator. The electric motor or the motor generator may be used as a drive source for driving the wheels of the hybrid vehicle or the electric vehicle. Below, the same code | symbol is attached | subjected and demonstrated to the same element in all the drawings.

  FIG. 1 shows a perspective view of a stator core 10 for a rotating electrical machine according to the present embodiment. Hereinafter, the stator core 10 for a rotating electrical machine is simply referred to as a stator core 10. Stator core 10 includes an annular yoke 12 and a plurality of teeth 14 projecting radially inward from yoke 12. Stator core 10 is formed of a laminate of a plurality of electromagnetic steel plates. A stator coil 32 is wound around each tooth 14 by concentrated winding or distributed winding when a stator 30 shown in FIG. 6 to be described later is formed.

  A slot 16 is formed between the teeth 14 adjacent to each other in the circumferential direction of the stator core 10. The slot 16 is formed between the circumferential side surfaces of the teeth 14 adjacent to each other in the circumferential direction. A portion of the stator coil 32 of FIG. 6 is accommodated in the slot 16.

  FIG. 2 shows an enlarged view of part A of FIG. Each tooth 14 is provided on the radially inner side surface of the yoke 12 and has a front end face 18 facing a rotor (not shown). The teeth 14 have the smallest circumferential width of the yoke 12 at the distal end including the distal end surface 18, and the circumferential width gradually increases from the radially intermediate portion toward the radially outer side. 20, the circumferential width d1 is the maximum.

  FIG. 3 is a view of FIG. 2 viewed in the axial direction, and FIG. 4 is an enlarged view of part C of FIG. The yoke 12 has a tapered surface 22 formed so as to be inclined in a V shape radially inward from the circumferential central portion of the bottom of the slot 16 toward the teeth 14 on both sides on the inner circumferential surface serving as the bottom of each slot 16. Have Further, the yoke 12 is provided on the outer diameter side of the central portion in the circumferential direction of the bottom portion of the slot 16, and the yoke 12 has a minimum width portion 24 having a width h 1 having a minimum radial width, and the yoke 12 has a slot. And a maximum width portion 26 having a width h2 in which the radial width is the maximum among the portions that are provided on the outer diameter side of both ends in the circumferential direction of the bottom portion of the 16 and that are separated from the teeth 14 in the circumferential direction. The minimum width portion 24 corresponds to the outer diameter side portion of the point G where the end portions of the two tapered surfaces 22 are connected in a V shape on the inner peripheral surface of the yoke 12.

  As shown in FIG. 4, the yoke 12 includes slits 28 provided in the vicinity of the root portions 20 at both ends in the circumferential direction of the teeth 14. The slits 28 in the vicinity of the root portion 20 of each tooth 14 are formed in parallel to each other toward the radially outer side so as to maintain the maximum width d1 in the circumferential direction of the root portion 20. Each slit 28 penetrates the yoke 12 over the entire axial length. In this case, each slit 28 is formed radially outward so as to maintain at least the circumferential maximum width d1 of the root portion 20 in the vicinity of the root portion 20 at both circumferential ends of each tooth 14. The phrase “formed at the radially outer side so as to maintain at least the maximum circumferential width of the root portion 20” means that the circumferential width between the slits 28 on both sides of the teeth 14 is the maximum in the circumferential direction of the root portion 20. This means that the slit 28 is provided so as not to be significantly smaller than d1. The slit 28 is not limited to the configuration in which the yoke 12 penetrates the entire length in the axial direction. The slit 28 is formed only in a portion near the end of the yoke 12 in the axial direction, and the slit 28 is not formed in the intermediate portion in the axial direction of the yoke 12. You may do it. In FIG. 4, a space is provided as a gap inside the slit 28, but portions of the yoke 12 provided on both sides of the slit 28 may be brought into contact with each other so that no space is generated in the slit 28. .

  Further, in the yoke 12, the radial width on the outer peripheral side in the circumferential direction between adjacent teeth 14 includes the outer diameter side at the end in the circumferential direction between adjacent teeth 14 including the width h 1 of the minimum width portion 24. It is smaller than the radial width h2 of the maximum width portion 26.

  In the yoke 12, the slit yoke outer-diameter distance h <b> 3, which is the radial distance between the radial outer end position H serving as the back end of the slit 28 and the outer peripheral surface of the yoke 12, is the radial direction of the minimum width portion 24. It is not less than the width h1 (h3 ≧ h1). 3 and 4, a broken line I indicates a part of a circumscribed circle passing through the inner diameter side position G of each minimum width portion 24, and the slit yoke outer diameter distance h <b> 3 and the minimum width portion 24 are The relationship (h3 ≧ h1) with the radial width h1 is well understood. The slit 28 is provided so that the distance h3 between the slit yoke outer diameters is not smaller than the radial width h1 of the minimum width portion 24. Further, as shown in FIG. 1, in the yoke 12, the area of the radial rectangular magnetic path cross section S1 with the slit yoke outer diameter distance h3 as the length of one side is defined, and the radial width h1 of the minimum width portion 24 is defined as one side. The area is equal to or larger than the area of the rectangular magnetic path section S2 in the radial direction. The formation of such slits 28 can suppress an increase in magnetic resistance and an increase in rotating electrical machine loss in the stator core 10, and the reason will be described later.

  The stator core 10 is used to form the stator 30 shown in FIG. Stator 30 includes a stator core 10 and a three-phase stator coil 32 of U phase, V phase, and W phase wound around a plurality of teeth 14 of stator core 10. The coil ends projecting outward from the axial side surface of the stator core 10 at both axial end portions of the stator coil 32 are resin-molded at two-dot chain lines J in FIGS. The stator 30 is fixed inside a case (not shown).

  The stator core 10 is formed of a plurality of divided cores separated at a plurality of locations in the circumferential direction, the stator coils are resin-molded in a state where the stator coils are wound around the respective divided cores, and then the divided cores are connected in an annular shape. Thus, a stator may be formed.

  A rotating electrical machine (not shown) is formed by rotatably supporting a rotating shaft on which a rotor is fixed with respect to a case, and disposing the rotor inside the stator 30 so as to face each other. The rotor includes permanent magnets or rotor coils provided at a plurality of locations in the circumferential direction. When a rotating electrical machine is used as an electric motor, a rotating magnetic field that acts on the rotor from the stator 30 is generated by passing a three-phase alternating current through the three-phase stator coil 32. The rotor is driven to rotate by a rotating magnetic field acting from the stator 30.

  According to the stator core 10 having the above-described configuration, slits parallel to each other toward the radially outer side so as to maintain the circumferential maximum width d1 of the root portion 20 in the vicinity of the root portions 20 at both circumferential ends of the teeth 14. 28 is formed. For this reason, even when a stress is generated in the teeth 14, an increase in magnetic resistance and an increase in loss can be suppressed. The reason for this will be described next.

  When the teeth 14 are resin-molded by injecting resin in a manufacturing mold (not shown), compressive stress or bending stress is generated in the teeth 14, and the resin may be solidified in that state. FIG. 6 is a diagram exaggeratingly showing a state in which compressive stress is generated in the teeth 14 during resin molding, and shows a diagram corresponding to the BB cross section of FIG. 3. It should be noted that the number of plate members 34, which are electromagnetic steel plates, is not limited to the number assumed from FIG. 6, but may be increased as compared with the case of FIG. As shown by a two-dot chain line in FIG. 6, the axial length of the teeth 14 of the stator core 10 formed of a laminated body in which plate members 34 are laminated in the axial direction is the same as the axial length of the yoke 12 before resin injection. is there. In this case, there is a gap between the plate members 34 due to the slight bending of each plate member 34. On the other hand, by injecting resin around a stator coil (not shown) wound around the teeth 14, the teeth 14 are bent and compressed so that there is no gap between the plate members 34 as indicated by solid lines. .

  On the other hand, in the present embodiment, the portion where the shape of the yoke 12 changes abruptly moves to the outer diameter side by the formation of the slit 28 described above. In this case, a stress concentration portion is generated in a portion indicated by a frame R in FIG. 6 and a portion indicated by a hatched square frame P1 in FIGS. This stress concentration portion is on the outer diameter side of the yoke 12 with respect to the inner peripheral end K (FIGS. 3, 4, 6, and 7) at the circumferential end of the bottom portion of the slot 16. In this case, as indicated by an arrow in FIG. 7, as the magnetic flux flowing from the root portion 20 of the tooth 14 to the slot 16 side portion of the yoke 12, the magnetic flux flowing across the slit 28 from the root of the tooth 14, and from this root A magnetic flux that flows radially outward and does not cross the slit 28 is generated. For this reason, unlike the case where the magnetic flux flows through the stress concentration portion only from the root of the tooth to the outside in the radial direction of the yoke, the concentration of the magnetic flux density at the stress concentration portion can be alleviated, thereby suppressing an increase in the magnetic resistance of the stator core 10. it can. Further, the magnetic flux flows in the circumferential direction from the root of the tooth 14 across the slit 28, and it is difficult to cause magnetic saturation in the stress concentration portion, thereby reducing the iron loss. For this reason, since the increase in rotating electrical machine loss can be suppressed, the torque fall of a rotating electrical machine can be suppressed.

  In addition, when both sides of the slit 28 of the yoke 12 are brought into contact with each other to eliminate the space in the slit 28, the magnetic resistance of the magnetic flux flowing from one side to the other side of the slit 28 can be reduced. For this reason, the magnetic flux which flows across the slit 28 can be increased, and the increase in magnetic resistance and the increase in rotating electrical machine loss can be suppressed more efficiently.

  On the other hand, in the case of the comparative example in which the slit 28 is not formed in the stator core 10, the stress concentration portion when stress is applied to the teeth 14 is a two-dot chain line square frame P <b> 2 in FIG. It becomes a part to show. For this reason, in a comparative example, it becomes difficult for a magnetic flux to pass in the root part 20 of the teeth 14 used as a stress concentration part, the magnetic resistance increases by increasing the magnetic flux density in the root part 20, and the root part having a higher magnetic flux density. The magnetic saturation at 20 may increase the iron loss and increase the rotating electrical machine loss.

  Further, in this embodiment, the distance h3 between the slit yoke outer diameters between the radial outer end position H (FIG. 4) serving as the back end of the slit 28 and the outer peripheral surface of the yoke 12 is the minimum width portion 24 of the yoke 12. The radial width of h1 is greater than or equal to h1 (h3 ≧ h1). Further, the area of the rectangular magnetic path cross section S1 having the length of one side as the slit yoke outer diameter distance h3 is equal to or larger than the area of the rectangular magnetic path cross section S2 having the radial width h1 of the minimum width portion 24 as the length of one side. is there. Therefore, even when the slit 28 is formed in the yoke 12, the slit yoke outer diameter is larger than the area of the magnetic path cross section S2 including the minimum width portion 24 through which the magnetic flux passes through the yoke 12 and the magnetic path cross sectional area becomes the minimum value. The area of the magnetic path cross section S1 including one side of the distance h3 does not become small. Therefore, since the slit 28 can be formed without reducing the magnetic path cross-sectional area of the yoke 12, it is possible to efficiently reduce the magnetic resistance and the iron loss.

  In addition, since slits 28 are formed in parallel with each other in the vicinity of the root portions 20 at both ends in the circumferential direction of the teeth 14, the slits 28 do not extend in the circumferential direction toward the slots 16 in the yoke 12, and the teeth 12 of the yoke 12 are included. It is possible to suppress the magnetic path from being restricted by the slit 28 in a portion deviated from the circumferential direction 14. As another embodiment different from this embodiment, the slits 28 in the vicinity of the root portion 20 of each tooth 14 are spaced apart from each other toward the radially outer side so as to maintain the maximum circumferential width d1 of the root portion 20. It is good also as a structure formed so that it may spread. Also in this case, each slit 28 is formed radially outward so as to maintain at least the circumferential maximum width d1 of the root portion 20 in the vicinity of the root portion 20 at both circumferential ends of each tooth 14.

  In the present embodiment, in the yoke 12, the radial width on the outer circumferential side in the circumferential direction between adjacent teeth 14 is smaller than the radial width on the outer circumferential side in the circumferential direction between the teeth 14. For example, in the yoke 12, the radial width on the outer peripheral side in the circumferential direction between the adjacent teeth 14 is smaller than the radial width h <b> 2 of the maximum width portion 26 at the circumferential end between the teeth 14. For this reason, in the yoke 12, the radial width at the circumferential intermediate portion on the outer diameter side of the bottom portion of the slot 16 is not excessively larger than the required magnetic path cross-sectional area, thereby reducing the weight of the stator core 10 and reducing the material. Cost reduction can be achieved.

  On the other hand, in the configuration described in Patent Document 2, a groove having a circular cross section is formed at the circumferential end of the root portion of the tooth. However, in such a configuration, the circumferential width at the root portion of the tooth is reduced by the groove portion, and the magnetic path cross-sectional area at the tooth is reduced. For this reason, the magnetic flux density increases, the torque of the rotating electrical machine decreases, and the loss may increase. Further, when the stator coil wound around the teeth is resin-molded, the magnetic flux concentrates on the portion where the bending stress is concentrated at the root of the teeth, and the rotating electrical machine loss further increases. According to this embodiment, even if the slit 28 is formed, the circumferential width d1 of the root portion 20 of the tooth 14 is not reduced, so that such inconvenience can be prevented.

  FIG. 8 is a view showing a part in the circumferential direction of a stator core 10 for a rotating electrical machine of a comparative example. In the comparative example, a slit 40 is formed in the yoke 12 so as to extend radially outward at a circumferential intermediate portion of the bottom of the slot 16. In such a comparative example, when the slit 40 is not formed, the stress concentration portion is a portion indicated by a broken line frame Q1 in FIG. 8, whereas when the slit 40 is formed, the stress concentration portion is a broken line frame Q2. It becomes a portion to be shown and moves to the outside in the radial direction. On the other hand, in the yoke 12, this stress concentration portion reaches the vicinity of the radially outer end of the slit 40, which is near the circumferential middle portion of the bottom of the slot 16, and the circumferential length of the stress concentration portion increases. For this reason, the loss reduction effect in a rotary electric machine cannot be expected. In this embodiment, since the slit 28 is formed in the vicinity of the root portion 20 of the tooth 14 so as to maintain the circumferential width d1 of the root portion 20, the stress concentration portion is not increased in the circumferential direction. For this reason, rotating electrical machine loss can be reduced efficiently.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to such embodiment at all, and it can implement with a various form in the range which does not deviate from the summary of this invention. Of course. For example, although the case where the stator coil is resin-molded has been described above, the present invention can also be applied to a configuration in which the stator coil is not resin-molded. Even in this configuration, even when the stator coil is wound around the teeth with high tension and stress is applied to the teeth, an increase in the magnetic resistance of the teeth and an increase in the rotating electrical machine loss can be suppressed.

  In the above embodiment, the case has been described in which the circumferential widths of the teeth are tapered such that the circumferential side surfaces are inclined so as to gradually decrease toward the root portion on the outer diameter side. It is good also as a teeth shape from which a circumferential direction width becomes equal from a base part to a tip part.

  10 Stator Core, 12 Yoke, 14 Teeth, 16 Slot, 18 Tip Surface, 20 Root, 22 Tapered Surface, 24 Minimum Width, 26 Maximum Width, 28 Slit, 30 Stator, 32 Stator Coil, 34 Plate, 40 Slit .

Claims (5)

An annular yoke and a plurality of teeth projecting radially inward from the yoke;
The yoke includes a slit formed on the radially outer side so as to maintain at least the maximum circumferential width of the root portion in the vicinity of the root portions at both ends in the circumferential direction of the teeth. Stator core. In the stator core for rotating electrical machines according to claim 1,
The yoke includes a minimum width portion having a minimum radial width on the outer peripheral side in the circumferential direction between adjacent teeth, and a radially outer end position H serving as a back end of the slit and an outer peripheral surface of the yoke. A stator core for a rotating electrical machine, wherein a distance y3 between the outer diameters of the slit yokes, which is a radial distance between the first and second coils, is equal to or greater than a radial width h1 of the minimum width portion. In the stator core for rotating electrical machines according to claim 1 or 2,
The yoke includes a minimum width portion having a minimum radial width on the outer peripheral side in the circumferential direction between adjacent teeth, and the yoke has a rectangular length having a length h1 between the slit yoke outer diameters. The stator core for a rotating electrical machine is characterized in that the area of the magnetic path cross section S1 is equal to or larger than the area of the rectangular magnetic path cross section S2 having the radial width h1 of the minimum width portion as one side length. In the stator core for rotating electrical machines according to claim 1,
In the yoke, the radial width on the outer circumferential side in the circumferential direction between the adjacent teeth is smaller than the radial width on the outer diameter side in the circumferential end between the adjacent teeth. Stator core. The stator for a rotating electrical machine according to any one of claims 1 to 4,
In the yoke, the slits are formed in parallel to each other outward in the radial direction so as to maintain the maximum width in the circumferential direction of the root portion in the vicinity of the root portions at both ends in the circumferential direction of the teeth. A stator for a rotating electrical machine.

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