JP2011199919A - Stator of electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise by preventing circular vibration of a stator.SOLUTION: In the stator 4 of an electric motor 1, an electromagnetic steel plate having a yoke 40 and a plurality of teeth 41 projecting toward an inner peripheral direction from the yoke 40, is stacked in a direction of a rotating shaft of an electric motor 1, and a plurality of slots 43 formed by the adjacent teeth 41 and the yoke 40 are arranged circumferentially. The rigidity of the yoke 40 differs in the two adjacent slots 43, and the rigidity of the yoke 40 differs between one end and the other end in a direction of the rotating shaft in the same slot 43.

Description

  The present invention relates to a structure of a stator of an electric motor.

  Patent Document 1 discloses a technique for suppressing the vibration in the circumferential direction of the teeth and improving the sound vibration performance of the electric motor by installing a wedge formed of an insulating member in the opening at the tip of the teeth of the stator. .

JP 2008-245403 A

  By the way, in an electric motor, the radial electromagnetic force generated between the teeth of the stator and the rotor periodically fluctuates with the rotation of the rotor, and this becomes an excitation force that causes the stator to ring. Let This annular vibration of the stator propagates to the case on the outer peripheral side of the stator, and the case vibrates in the radial direction to generate sound. In particular, when the periodic fluctuation of the excitation force coincides with the ring vibration, the stator resonates and generates a large noise.

  In the technique described in Patent Document 1, the circumferential vibration of the teeth is suppressed by limiting the circumferential movement of the teeth tip, but the circumferential vibration of the teeth does not resonate with the excitation force, Since the stator does not vibrate in the radial direction, there is a problem that the effect of suppressing noise is poor.

  Therefore, an object of the present invention is to suppress noise by suppressing vibration in the radial direction of the stator.

  The stator of the electric motor of the present invention is formed by laminating electromagnetic steel sheets having a yoke portion and a plurality of teeth portions protruding from the yoke portion in the inner circumferential direction in the direction of the rotation axis of the electric motor. A plurality of slot portions formed with the yoke portion are arranged in the circumferential direction. The rigidity of the yoke portion differs between two adjacent slots, and the rigidity of the yoke portion differs between the one end side and the other end side in the rotation axis direction in the same slot.

  According to the present invention, when the stator vibrates in an annular shape, the tooth portion is twisted and shear strain is generated. In a stator made by laminating electromagnetic steel sheets, if shear strain occurs in the teeth, a frictional force is generated between each electromagnetic steel sheet, and this frictional force acts as a resistance that attenuates the annular vibration of the stator. The vibration noise of the motor is reduced.

It is sectional drawing seen from the axial direction of the electric motor to which 1st Embodiment is applied. 1 shows a stator according to a first embodiment, wherein (a) is a front view of the stator as viewed from the axial direction of the motor, (b) is a sectional view taken along line II-II in (a), and (c) is a stator. It is the rear view which looked at from the opposite side to (a). It is a figure which shows the vibration mode of a stator. It is the figure shown about the deformation | transformation of the stator in the vibration mode of n = 0, (a) has shown about this embodiment, (b) has shown about the structure which does not have a groove part. It is a figure for demonstrating the vibration reduction effect. It shows about the stator of 2nd Embodiment, (a) is the front view which looked at the stator from the axial direction of the electric motor, (b) is sectional drawing along the VI-VI line of (a), (c) is a stator It is the rear view which looked at from the opposite side to (a). It shows about the stator of 3rd Embodiment, (a) is the front view which looked at the stator from the axial direction of the electric motor, (b) is sectional drawing along the VII-VII line of (a), (c) is a stator It is the rear view which looked at from the opposite side to (a).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of the electric motor 1 to which the first embodiment is applied as viewed from the axial direction.

  The electric motor 1 is an AC motor, and includes a rotor 3 connected to a shaft 2 that transmits rotation, a stator 4 that surrounds the periphery of the rotor 3, and a case 5 that covers the outer peripheral side of the stator 4.

  The rotor 3 is an inner rotor arranged at a predetermined minute interval on the inner peripheral side of the stator 4 formed in a cylindrical shape. The rotor 3 includes a rotor core 31, a permanent magnet 32 embedded in the rotor core 31, and the like. To do.

  The rotor core 31 is formed by laminating thin plate-like steel plates in order to prevent eddy currents, and a plurality of permanent magnets are provided near the inner periphery of the rotor core 31 so as to form an annular shape when viewed from the axial direction. 32 is fixed. These permanent magnets 32 form a magnetic path with the electromagnet of the stator 4 described later in a state where the rotor 31 is assembled to the stator 4.

  The stator 4 is a stator formed in a cylindrical shape. The stator 4 is formed by laminating electromagnetic steel plates in the axial direction in order to prevent eddy currents, and includes a yoke part 40, a tooth part 41 projecting in a tooth shape from the yoke part 40, and a tooth part. Insulating member 6 which covers 41 so as to cover 41, and coil 42 which is wound around insulating portion 6 around tooth portion 41.

  When a space formed by the adjacent teeth portion 41 and the inner peripheral surface of the yoke portion 40 is defined as a slot 43, grooves 51 and 52 are provided on the inner peripheral surface of the yoke portion facing the slot 43. Details of the grooves 51 and 52 will be described later.

  The stator 4 may be formed by laminating the disk-shaped electromagnetic steel plates shown in FIG. 1 in the axial direction, or as a so-called divided type in which the circular cross section shown in FIG. 1 is divided into a plurality of portions in the circumferential direction. Also good.

  2A and 2B are views for explaining the groove 51, in which FIG. 2A is a front view of the stator 4 viewed from the axial direction of the electric motor 1 as in FIG. 1, and FIG. 2B is a II-II line of FIG. (C) is the rear view which looked at the stator 4 from the opposite side to (a).

  As shown in FIG. 2A, six slots 43 are arranged in the stator 4 at equal intervals in the circumferential direction. Of these, the number of the slots 43 provided with the grooves 51 is three, and the slots 43 provided with the grooves 51 and the slots 43 not provided are alternately arranged.

  The groove 51 and the groove 52 to be described later refer to a notch provided from the surface facing the slot 43 of the yoke portion 40 toward the radially outer side of the stator 4.

  On the other hand, as for the groove 52, as shown in FIG. 2C, the slot 43 provided with the groove 52 and the slot 43 not provided are alternately arranged. However, the groove 43 is not provided in the slot 43 provided with the groove 51, and the groove 51 is not provided in the slot 43 provided with the groove 52. That is, the slots 43 provided with the grooves 51 and the slots 43 provided with the grooves 52 are alternately arranged in the circumferential direction.

  As shown in FIG. 2B, the groove 51 extends from one end of the stator 4 to the vicinity of the center of the stator 4 along the axial direction, and the groove 52 extends from the other end of the stator 4 along the axial direction of the stator 4. Extends to near the center. However, the axial lengths of the grooves 51 and 52 are set so as not to exceed half of the axial length of the stator 4.

  Next, the function and effect obtained by providing the grooves 51 and 52 will be described.

  When the electric motor 1 is operated, the electromagnetic force acting between the inner peripheral tip of the tooth portion 41 and the rotor 3 periodically changes with the rotation of the rotor 3, thereby causing the stator 4 that is a stator to be circular. Ring vibration occurs. Observation of the form of this ring vibration revealed that the vibration mode shown in FIG. 3 was obtained.

  FIG. 4 shows the result of examining the deformation of the stator 4 in the vibration mode of n = 0, which has the highest sound generation efficiency in the vibration mode of FIG. 3, and (a) shows the present embodiment, (b) shows the result. For comparison, a stator (which is referred to as a conventional type) without the grooves 51 and 52 is shown.

  In the conventional type, the amplitude and phase are uniform from one end to the other end in the axial direction. On the other hand, in the stator 4 of the present embodiment, since the grooves 51 and 52 are provided, the rigidity is not uniform in the axial direction. Twisting and shearing strain is generated by this twisting. Since the stator 4 is configured by laminating a large number of thin plates in the axial direction, friction occurs between the thin plates when shear strain occurs in the tooth portion 41. Since this friction acts as a resistance for attenuating the annular vibration of the stator 4, vibration noise of the electric motor 1 due to the vibration of the stator 4 is reduced.

  FIG. 5 is a diagram illustrating the above-described vibration reduction effect. The horizontal axis indicates the frequency [Hz], the vertical axis indicates the vibration intensity [dB], the solid line indicates the vibration of the present embodiment, and the broken line indicates the conventional vibration.

  Comparing the vibration intensity of the present embodiment with that of the conventional type at the frequency with the highest vibration intensity in the conventional type (frequency in the case of the vibration mode of n = 0), the present embodiment is clearer as shown in FIG. It can be seen that the vibration intensity is low.

  As described above, in the present embodiment, the following effects can be obtained.

  (1) Since the rigidity of the yoke part 40 is different in the two adjacent slots 43, and the rigidity of the yoke part 40 is different between the one end side and the other end side in the rotation axis direction in the same slot 43, the stator 4 has an annular vibration. When the teeth portion 41 is deformed, the teeth portion 41 is twisted. At this time, the vibration is attenuated by the frictional force generated between the electromagnetic steel sheets, and the noise is reduced.

  (2) The rigidity between the adjacent slots 43 and between both ends in the rotation axis direction of the same slot 43 is made different depending on whether or not the groove portion is provided in the yoke portion 40 between the adjacent slots 43. For this reason, the grooves 51 and 52 can be provided only by changing the shape of the punch for forming the electromagnetic steel sheet. That is, since a new member for providing the grooves 51 and 52 is not necessary, an increase in cost can be prevented.

  (3) A yoke portion 40 having a groove 51 extending from one end in the rotation axis direction to the other end side and not reaching the other end, and extending from the other end in the rotation axis direction toward the one end side and to one end The yoke portions 40 having the groove portions 52 that do not reach are alternately arranged in the circumferential direction. Therefore, since only one type of punch for forming the electromagnetic steel sheet needs to be prepared, an increase in cost can be prevented.

  (4) Since the value obtained by adding the axial length of the groove 51 provided in one of the adjacent slots 43 and the axial length of the groove portion 52 provided in the other is equal to or less than the axial length of the stator 4, the yoke portion There is no portion where the radial thickness of 40 is reduced over the entire circumference. Thereby, the fall of the resonant frequency can be suppressed.

  A second embodiment will be described.

  6A and 6B are diagrams for explaining the stator 4 of the present embodiment. FIG. 6A is a front view of the stator 4 viewed from the axial direction of the electric motor 1 in the same manner as FIG. 1, and FIG. Sectional drawing along VI-VI line, (c) is the rear view which looked at the stator 4 from the opposite side to (a).

  Due to the configuration of the magnetic circuit, the tips of adjacent teeth portions 41 need to be open. That is, the slot 43 needs to be open toward the inner peripheral side of the stator 4.

  In this embodiment, as shown in FIGS. 6A and 6C, the connection members 61 and 62 formed of an insulating member such as ceramic or resin are arranged so as to be sandwiched between the open gaps.

  As shown in FIG. 6A, the connecting member 61 has an axial length that extends from one end of the stator 4 toward the other end but does not reach the other end. The slots 43 in which the connecting members 61 are arranged and the slots 43 in which the connecting members 61 are not arranged are alternately arranged in the circumferential direction.

  On the other hand, the connection member 62 extends from the other end of the stator 4 toward one end, but has an axial length that does not reach one end. As with the connection member 61, the slots 43 in which the connection members 62 are disposed and the slots 43 that are not provided are alternately arranged.

  However, the connection member 62 is not disposed in the slot 43 in which the connection member 61 is disposed, and the connection member 61 is not disposed in the slot 43 in which the connection member 62 is provided. That is, the slots 43 in which the connection members 61 are arranged and the slots 43 in which the connection members 62 are arranged are alternately arranged in the circumferential direction.

  Further, as shown in FIG. 6B, the axial positions of the connecting member 61 and the connecting member 62 are not overlapped on the cross section along the axial direction.

  When the connection member 61 or the connection member 62 is disposed as described above, the adjacent tooth portions 41 support each other at the disposed portion, so that vibration in the circumferential direction of the teeth portion 41 can be suppressed. On the other hand, since there is no such effect in the portion not arranged, the vibration in the circumferential direction of the tooth portion 41 is larger than that in the portion where the connection members 61 and 62 are arranged.

  Therefore, when the motor 1 is operated and the stator 4 undergoes annular vibration, the deformation of the stator 4 does not become uniform in the axial direction, and the teeth 41 are twisted so as to be sheared in the laminating plane. Shear strain occurs. Since the stator 4 is configured by laminating a large number of thin plates in the axial direction, friction occurs between the thin plates when shear strain occurs in the tooth portion 41. Since this friction acts as a resistance for attenuating the annular vibration of the stator 4, vibration noise of the electric motor 1 due to the vibration of the stator 4 is reduced.

  As described above, in the present embodiment, in addition to the same effects as in the first embodiment, the following effects can be obtained.

  (5) Rigidity between adjacent slots 43 and between both ends in the rotation axis direction of the same slot 43 depending on whether or not connecting members 61 and 62 that connect at least a part of mutually opposing surfaces of adjacent teeth portions 41 are arranged. Therefore, the rigidity can be varied without affecting the magnetic circuit.

  (6) A slot 43 including a connecting member 61 that extends from one end in the direction of the rotation axis toward the other end and does not reach the other end, and extends from the other end in the direction of the rotation axis toward one end and to one end Slots 43 having connecting members 62 that do not reach are alternately arranged in the circumferential direction. Accordingly, it is sufficient to produce only one type of connection members 61 and 62, so that an increase in cost can be prevented.

  (7) Since the value obtained by adding the axial length of the connecting member 61 provided in one of the adjacent slots 43 and the axial length of the connecting member 62 provided in the other is equal to or less than the axial length of the stator 4 The shear deformation at the boundary between the part and the part that is not can be made larger. Thereby, the vibration damping effect can be further increased.

  A third embodiment will be described.

  7A and 7B are diagrams for explaining the stator 4 of the present embodiment. FIG. 7A is a front view of the stator 4 viewed from the axial direction of the electric motor 1 in the same manner as FIG. 1, and FIG. Sectional drawing along the VII-VII line, (c) is the rear view which looked at the stator 4 from the opposite side to (a).

  As shown in FIG. 7A, the stator 4 has six slots 43 arranged at equal intervals in the circumferential direction. Of these, the number of the slots 43 provided with the grooves 51 is three, and the slots 43 provided with the grooves 51 and the slots 43 not provided are alternately arranged.

  On the other hand, as for the groove 52, as shown in FIG. 7C, the slot 43 provided with the groove 52 and the slot 43 not provided are alternately arranged. However, the slots 43 provided with the grooves 51 and the slots 43 provided with the grooves 52 are alternately arranged in the circumferential direction.

  7B, the groove 51 extends from one end of the stator 4 to the vicinity of the center of the stator 4 along the axial direction, and the groove 52 extends from the other end of the stator 4 along the axial direction. Extends to near the center. However, the axial lengths of the grooves 51 and 52 are set so as not to exceed half of the axial length of the stator 4.

  Further, as shown in FIGS. 7A and 7C, the connection members 61 and 62 formed of ceramic, resin, or the like are arranged so as to be sandwiched between the gaps between the adjacent tooth portions 41.

  As shown in FIG. 7A, the connecting member 61 extends from the other end of the stator 4 toward one end, but has an axial length that does not reach one end. The slot 43 in which the connecting member 61 is disposed is a slot 43 in which the groove 51 is provided.

  On the other hand, the connection member 62 extends from one end of the stator 4 toward the other end, but has an axial length that does not reach the other end. The slot 43 in which the connecting member 62 is disposed is the slot 43 in which the groove 52 is provided.

  Further, as shown in FIG. 7B, the axial positions of the connecting member 61 and the connecting member 62 are made not to overlap on a cross section along the axial direction.

  That is, the adjacent teeth 41 are open at the axial end on the side where the grooves 51 and 52 are provided, and the teeth are connected by the connecting members 61 and 62 at the axial end on the side where the grooves 51 and 52 are not provided. 41 is connected.

  As described above, in the stator 4 of this embodiment, the tip of the tooth portion 41 is open in the axial range where the grooves 51 and 52 are provided, and the connecting member 61 is provided in the axial range where the grooves 51 and 52 are not provided. 62, the tip of the tooth part 41 is connected.

  Thereby, the vibration in the circumferential direction of the tooth portion 41 adjacent to the slot 43 provided with the grooves 51 and 52 is not hindered by the connecting members 61 and 62. Further, depending on the setting of the axial lengths of the grooves 51 and 52 and the connection members 61 and 62, the resonance frequency is reduced by providing the grooves 51 and 52, and the resonance frequency is increased by arranging the connection members 61 and 62. The balance can be adjusted. That is, the above-described shear deformation of the tooth portion 41 can be further increased, and the vibration damping effect due to friction caused by the shear deformation can be further increased.

  As described above, in the present embodiment, in addition to the same effects as those in the first embodiment and the second embodiment, the following effects can be obtained.

  (8) One slot 43 has grooves 51, 52 and connecting members 61, 62. In the axial range where the grooves 51, 52 are provided, the arrangement of the connecting members 61, 62 is prohibited, and the connecting members 61, 62 are The arrangement of the grooves 51 and 52 is prohibited in the arranged axial range. As a result, the axial range in which the grooves 51 and 52 are provided and the axial range in which the tooth portion 41 is connected are always shifted, so that the shear deformation of the teeth portion 41 is further increased, and the vibration damping effect is increased. Can be larger.

  The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims. For example, in the drawings used for the above description, the cross-sectional shape of the grooves 51 and 52 when viewed from the axial direction is a rectangle, but it may be a triangle, a trapezoid, or the circumferential direction of the grooves 51 and 52. The length may extend over the entire area between adjacent teeth portions 41. This is because, although the magnitude of the effect obtained varies depending on the shape and size of the grooves 51 and 52, the vibration suppressing effect of the stator 4 can be obtained if the rigidity of the stator 4 becomes uneven in the circumferential direction.

  Further, the axial length of the grooves 51 and 52 or the connecting members 61 and 62 may be shorter than the length shown in FIG. In this case, although the magnitude of the effect to be obtained is changed, if the amplitude and phase of the vibration mode are shifted at both ends in the axial direction and the tooth portion 41 is twisted, shear distortion occurs and a vibration suppressing effect is obtained. It is.

DESCRIPTION OF SYMBOLS 1 Electric motor 2 Shaft 3 Rotor 4 Stator 5 Case 6 Insulating member 31 Rotor core 32 Permanent magnet 40 Yoke part 41 Teeth part 42 Winding 51 Groove 52 Groove 61 Connection member 62 Connection member

Claims (8)

A slot formed by laminating electromagnetic steel plates having a yoke portion and a plurality of teeth portions projecting inward from the yoke portion in the direction of the rotating shaft of the motor, and formed by the adjacent teeth portion and the yoke portion. In the stator of an electric motor that is arranged in the circumferential direction,
The stator of an electric motor characterized in that the rigidity of the yoke portion is different between two adjacent slots, and the rigidity of the yoke portion is different between one end side and the other end side in the rotation axis direction in the same slot.   The stator of the electric motor according to claim 1, wherein the rigidity between the adjacent slots and between both ends in the rotation axis direction of the same slot is made different depending on whether or not a groove is provided in the yoke portion between the adjacent slots.   The yoke portion having the groove that extends from one end in the rotation axis direction to the other end side and does not reach the other end, and extends from the other end in the rotation axis direction to the one end side and does not reach one end The stator for an electric motor according to claim 2, wherein the yoke portions including the groove portions are alternately arranged in a circumferential direction.   4. The electric motor according to claim 3, wherein a value obtained by adding an axial length of the groove provided in one of the adjacent slots and an axial length of the groove provided in the other is equal to or less than an axial length of the stator. 5. Stator.   2. The rigidity between adjacent slots and between both ends in the rotation axis direction of the same slot is made different depending on whether or not a connection member that connects at least a part of mutually facing surfaces of the adjacent teeth portions is arranged. The stator of the electric motor according to any one of 4.   The slot including the connecting member that extends from one end of the rotating shaft direction toward the other end and does not reach the other end, and extends from the other end in the rotating shaft direction toward the one end side, but does not reach the one end The stator of the electric motor according to claim 5, wherein the slots including the connection members are alternately arranged in a circumferential direction.   The value obtained by adding the axial length of the connecting member provided in one of the adjacent slots and the axial length of the connecting member provided in the other is equal to or less than the axial length of the stator. The stator of the electric motor. One slot having the groove and the connecting member;
The electric motor according to any one of claims 1 to 7, wherein the connection member is prohibited from being disposed in an axial range where the groove is provided, and the groove is prohibited from being disposed in an axial range where the connection member is disposed. Stator.

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