Rotor and electric motor

Abstract

A rotor (2) comprises: a rotor core (4) fixed to a shaft (3) serving as a rotating shaft; and an end ring (5) provided to at least one end of two ends of the rotor core (4) in the rotational axis direction of the shaft (3). The end ring (5) provided to the at least one end of the two ends of the rotor core (4) has a plurality of projections (50) protruding out toward the rotational axis direction of the shaft (3). Each of the projections (50) is configured so as to be removable in order to adjust the balance of rotation, and so that a balance weight (6) for increasing the weight of the end ring (5) can be attached in order to adjust the balance of rotation.

Description

Rotor and motor

[0001] The present disclosure relates to a rotor and an electric motor.

[0002] Rotors that constitute electric motors are known. The rotational balance of the rotor is adjusted to obtain stable rotation and torque. For example, a rotor disclosed in Patent Document 1 includes a rotor core and a balancer that is provided axially away from at least one of the axial end faces of the rotor core. The balancer has a balancer body formed in an annular shape and multiple protrusions formed integrally with the balancer body. The rotational balance of the rotor is adjusted by removing some or all of the multiple protrusions to reduce the weight of the balancer.

[0003] Japanese Patent Application Laid-Open No. 2023-90242

[0004] However, with the technology disclosed in Patent Document 1, the only way to adjust the rotational balance of the rotor is to remove some or all of the protrusions and reduce the weight of the balancer. Therefore, if the amount of imbalance in the rotational balance of the rotor is large, it may not be possible to accurately adjust the rotational balance simply by reducing the weight of the balancer.

[0005] The present disclosure has been made in view of the above, and has an object to provide a rotor that can adjust the rotational balance with high precision even when the amount of unbalance of the rotor is large.

[0006] To solve the above-mentioned problems and achieve the object, the rotor according to the present disclosure includes a rotor core fixed to a shaft serving as a rotation axis, and an end ring provided on at least one of both ends of the rotor core in the direction of the rotation axis of the shaft. The end ring provided on at least one of both ends of the rotor core has a plurality of protrusions protruding in the direction of the rotation axis of the shaft. Each protrusion is removable to adjust the rotational balance, and is configured to allow the attachment of a balance weight that increases the weight of the end ring to adjust the rotational balance.

[0007] The rotor according to the present disclosure has the advantage that the rotational balance can be adjusted with high precision even if the amount of unbalance of the rotor is large.

[0008] 2 is a plan view showing a balance weight of the rotor according to the first embodiment; FIG. 4 is a cross-sectional view taken along arrows V-V in FIG. 4; FIG. 5 is an explanatory diagram showing the rotor according to the first embodiment, with the balance weight attached to the protrusion; FIG. 6 is a cross-sectional view taken along arrows VIII-VIII in FIG. 7;

[0009] Hereinafter, a rotor and an electric motor according to an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0010] First embodiment Fig. 1 is a front view showing an electric motor according to a first embodiment. Fig. 2 is a side view of the electric motor according to the first embodiment, as seen from the direction of arrow II shown in Fig. 1. As shown in Figs. 1 and 2, an electric motor 100 according to the first embodiment includes a cylindrical stator 1, a rotor 2 that is surrounded by the stator 1 and drives to rotate, and a shaft 3 that rotatably supports the rotor 2. The shaft 3 is disposed so as to pass through the rotor 2. Hereinafter, the direction in which the shaft 3 extends is referred to as the rotation axis direction X.

[0011] The stator 1 includes, for example, a stator core (not shown), insulators, and windings. The stator core is formed into a cylindrical shape extending in the rotation axis direction X by stacking, for example, a plurality of electromagnetic steel sheets, which are magnetic materials, in the rotation axis direction X. The insulators are attached to both axial ends of the stator core to insulate the stator core from the windings. The windings are wound around the stator core via the insulators.

[0012] As shown in Figures 1 and 2, the rotor 2 includes a rotor core 4 and a pair of end rings 5. The rotor core 4 is formed into a generally cylindrical shape extending in the rotation axis direction X by stacking, for example, a plurality of electromagnetic steel sheets, which are magnetic materials, in the rotation axis direction X. A through hole (not shown) is formed in the rotor core 4. The through hole is provided in the center of the rotor core 4 and passes through in the rotation axis direction X. The shaft 3 is inserted into the through hole. Note that the rotor core 4 may be configured, for example, to have a plurality of magnet insertion holes that pass through the rotor core 4 in the axial direction, with permanent magnets inserted in each magnet insertion hole.

[0013] 1 and 2 , the end rings 5 ​​are fixed to both ends of the rotor core 4 in the direction X of the rotation axis, i.e., to the load side and anti-load side of the rotor core 4. The end rings 5 ​​are made of non-magnetic plate-shaped members. A shaft hole into which the shaft 3 is inserted is provided in the center of the end ring 5. Note that the end rings 5 ​​do not necessarily have to be provided at both ends of the rotor core 4 in the direction X of the rotation axis, and may be provided at least at one end of the rotor core 4.

[0014] The rotational balance of the rotor 2 is adjusted to obtain stable rotation and torque. In conventional rotors, the rotational balance is adjusted, for example, by reducing the weight of the end rings 5 ​​or by increasing the weight of the end rings 5 ​​using balance weights. However, if the amount of imbalance in the rotor's rotational balance is large, the amount by which the end rings 5 ​​must be reduced or increased becomes large, and it may not be possible to accurately adjust the rotational balance by simply reducing or increasing the weight of the end rings 5.

[0015] Therefore, in the rotor 2 according to the first embodiment, the end rings 5 ​​have multiple protrusions 50 protruding toward the rotational axis direction X. Each protrusion 50 is removable to adjust the rotational balance of the rotor 2, and a balance weight 6 can be attached to increase the mass of the end rings 5 ​​to adjust the rotational balance of the rotor 2. As shown in FIGS. 1 and 2 , the protrusions 50 are regularly arranged along the circumferential direction of concentric circles centered on the rotation center C of the shaft 3. As an example, twelve protrusions 50 are shown in FIGS. 1 and 2 . The multiple protrusions 50 are formed with the same shape, size, and weight. The number of protrusions 50 is not limited to the twelve shown in the figures, and may be two or more. Furthermore, the protrusions 50 do not necessarily have to be the same shape, size, and weight, and may be different shapes, sizes, and weights. Furthermore, the protrusions 50 do not necessarily have to be provided on both of the pair of end rings 5; they may be provided on at least one of the end rings 5.

[0016] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2 . As shown in FIG. 3 , each protrusion 50 is formed of multiple protrusions 50a, 50b, and 50c with different outer shapes that gradually decrease in size along the rotation axis direction X. As an example, the protrusion 50 shown in FIG. 3 includes a protrusion 50a with the largest outer shape, a protrusion 50b with a smaller outer shape than the protrusion 50a, and a protrusion 50c with a smaller outer shape than the protrusion 50b. That is, the protrusion 50 is formed so that its outer shape gradually decreases in size along the rotation axis direction X in three stages. All of the protrusions 50a, 50b, and 50c, or some of the protrusions 50b and 50c, may be removed from each protrusion 50. When some of the protrusions 50b and 50c are removed, for example, both the protrusions 50b and 50c, or only the protrusion 50c, may be removed. The protrusions 50 are removed from the protrusions 50, with the protrusions 50 having the convex portions 50a, 50b, and 50c necessary for adjusting the rotational balance of the rotor 2. As described above, in the rotor 2 according to the first embodiment, the protrusions 50 have the convex portions 50a, 50b, and 50c, which allow the locations at which the end rings 5 ​​are to be reduced in weight to be precisely set, thereby enabling the rotational balance to be adjusted with high precision. Note that the protrusions 50 are not limited to the illustrated configuration having three convex portions 50a, 50b, and 50c, and may have two convex portions or four or more convex portions. Also, the protrusions 50 may be configured with a single convex portion.

[0017] FIG. 4 is a plan view showing a balance weight of the rotor according to the first embodiment. FIG. 5 is a cross-sectional view taken along the line V-V in FIG. 4 . The balance weight 6 shown in FIGS. 4 and 5 is provided to increase the weight of the end rings 5 ​​and adjust the rotational balance of the rotor 2. The balance weight 6 includes a cylindrical portion 60 that fits onto the protrusions 50 and a retaining portion 61 that maintains the state in which the cylindrical portion 60 is fitted onto the protrusions 50. The cylindrical interior of the cylindrical portion 60 has an inner shape that fits onto the respective convex portions 50a, 50b, and 50c of the protrusions 50, and the balance weight 6 is fitted onto one of the three convex portions 50a, 50b, and 50c. The retaining portion 61 is provided to maintain the state in which the cylindrical portion 60 is fitted onto the protrusions 50 so that the balance weight 6 does not come off the protrusions 50. The retaining portions 61 are formed as a pair of protrusions that protrude from opposing inner wall surfaces of the cylindrical portion 60 toward the protrusions 50a, 50b, and 50c and sandwich the side surfaces of the protrusions 50a, 50b, and 50c. When the balance weight 6 is fitted into the protrusions 50a, 50b, and 50c, the retaining portions 61 are elastically deformed and pushed open while being pressed in. The tips of the retaining portions 61 are formed with barbs that bite into the side surfaces of the protrusions 50a, 50b, and 50c. When attaching the balance weight 6 to the protrusions 50a, 50b, and 50c, it is sufficient to simply fit the cylindrical portion 60 into the protrusions 50a, 50b, and 50c; there is no need to hammer the balance weight 6 in forcefully. Therefore, there is no risk of the rotor 2 being damaged by the impact of hammering the balance weight 6 when attaching it. Furthermore, the burden on the worker caused by the hammering operation can be reduced. The retaining portion 61 is not limited to the pair of protrusions shown in the figure, and may have other shapes as long as it can maintain the state in which the tubular portion 60 is fitted into the protrusion portion 50 so that the balance weight 6 does not slip out of the protrusion portion 50.

[0018] FIG. 6 is an explanatory diagram schematically illustrating the rotor according to the first embodiment, with balance weights attached to the protrusions. As shown in FIG. 6 , the balance weights 6 are attached to the protrusions 50 that require adjustment of the rotational balance of the rotor 2 among the multiple protrusions 50. The balance weights 6 may be attached to all or some of the protrusions 50a, 50b, and 50c of each protrusion 50. As an example, FIG. 6 illustrates three balance weights 6 of different sizes attached to the corresponding protrusions 50a, 50b, and 50c. The balance weights 6 are held in a state in which the cylindrical portion 60 is fitted to the protrusions 50a, 50b, and 50c by clamping the sides of the protrusions 50a, 50b, and 50c with the tips of the retaining portions 61.

[0019] Of the three protrusions 50a, 50b, and 50c, the balance weight 6 may be provided, for example, only on the protrusion 50a, which has the largest outer diameter, or on both the protrusion 50a, which has the largest outer diameter, and the protrusion 50c, which has the smallest outer diameter. The protrusions 50a, 50b, and 50c on which the balance weight 6 is provided are determined appropriately in accordance with the adjustment of the rotational balance of the rotor 2. In this way, in the rotor 2 of the first embodiment, the locations where the balance weight 6 is installed to increase the mass of the end rings 5 ​​can be precisely determined, allowing for precise adjustment of the rotational balance.

[0020] Furthermore, the shape and size of the balance weight 6 are not limited to the configuration shown in the figure. Furthermore, the balance weight 6 is not limited to a configuration in which it is attached to each of the protrusions 50a, 50b, and 50c, but may be configured as a single unit so that it can be attached to all three of the protrusions 50a, 50b, and 50c at once. Furthermore, the holding portion 61 is not limited to the configuration shown in the figure, and may have other configurations. In short, the balance weight 6 may have other shapes as long as it can be attached to the protrusions 50.

[0021] As described above, the rotor 2 according to the first embodiment includes the rotor core 4 fixed to the shaft 3, which serves as the rotation axis, and the end ring 5 provided on at least one of the two ends of the rotor core 4 in the rotation axis direction X of the shaft 3. The end ring 5 provided on at least one of the two ends of the rotor core 4 has a plurality of protrusions 50 that protrude in the rotation axis direction X of the shaft 3. Each of the protrusions 50 is removable to adjust the rotational balance, and is configured to allow attachment of a balance weight 6 that increases the weight of the end ring 5 in order to adjust the rotational balance.

[0022] Therefore, in order to adjust the rotational balance of the rotor 2 according to the first embodiment, the protrusions 50 can be removed to reduce the weight of the end rings 5, and the balance weights 6 can be attached to the protrusions 50 to increase the weight of the end rings 5. This allows the rotational balance to be adjusted with high precision even if the amount of unbalance of the rotor 2 is large.

[0023] Furthermore, the balance weight 6 attached to the protrusion 50 has a cylindrical portion 60 having an inner shape that fits into the protrusion 50, and a retaining portion 61 that maintains the state in which the cylindrical portion 60 is fitted into the protrusion 50. This allows the balance weight 6 to remain attached to the protrusion 50 so that it will not come off the protrusion 50 even when the rotor 2 rotates at high speed.

[0024] Each protrusion 50 is formed of a plurality of protrusions 50a, 50b, 50c with different outer shapes so that the outer shape gradually decreases along the rotational axis direction X of the shaft 3. This allows the end ring 5 to be reduced in weight by gradually removing the protrusions 50a, 50b, 50c of the protrusions 50 in accordance with the amount of imbalance in the rotor 2, or the end ring 5 to be increased in weight by gradually attaching balance weights 6 to the protrusions 50a, 50b, 50c, thereby enabling precise adjustment of the rotational balance. Furthermore, since each protrusion 50 has a plurality of protrusions 50a, 50b, 50c, these protrusions serve as a guide for the amount of removal of the protrusions 50a, 50b, 50c and the amount of attachment of the balance weights 6 to the protrusions 50a, 50b, 50c, thereby improving the workability of adjusting the rotational balance.

[0025] Second Embodiment Next, a rotor according to a second embodiment will be described. Fig. 7 is an explanatory diagram showing a rotor according to the second embodiment. Fig. 8 is a cross-sectional view taken along the line VIII-VIII shown in Fig. 7.

[0026] 7 and 8 , each end ring 5 of the rotor 2 according to the second embodiment has three protrusions 51, 52, 53 arranged in the order of protrusions 53, 52, 51 in the radial direction from the center of rotation C of the shaft 3, and eight protrusions are arranged regularly in the circumferential direction of a concentric circle centered on the center of rotation C of the shaft 3. That is, a total of 24 protrusions 51, 52, 53 are provided on each end ring 5. By providing the end rings 5 ​​with multiple protrusions 51, 52, 53 in this way, it is possible to finely determine the locations where the end rings 5 ​​are to be reduced in weight by removing the protrusions 51, 52, 53 and the locations where the end rings 5 ​​are to be increased in weight by installing balance weights 6, thereby increasing the range of adjustment and enabling precise adjustment of the rotational balance of the rotor 2.

[0027] Furthermore, protrusion 51 is located on the outermost periphery of end ring 5. Protrusion 53 is located on the innermost periphery of end ring 5. Protrusion 52 is located between protrusions 51 and 53. Protrusions 51, 52, and 53 in the same row arranged radially from the rotation center C of shaft 3 have the same shape and weight. Protrusions 51, 52, and 53 arranged circumferentially on concentric circles centered on the rotation center C of shaft 3 have the same shape and weight. The balance amount that can be adjusted by removing protrusions 51, 52, and 53 and by attaching balance weights 6 of the same weight to protrusions 51, 52, and 53 is proportional to the distance from the rotation center C, provided that protrusions 51, 52, and 53 have the same shape and weight.

[0028] Here, the distance from the center of rotation C of the shaft 3 to the outer surface of the end ring 5 is r0. The axial center of the protrusion 51 located on the outermost periphery is r1 away from the center of rotation C of the shaft 3. The balance amount that changes when the protrusion 51 is removed is weight M×r1 / r0. The axial center of the protrusion 52 located in the middle is r2 away from the center of rotation C of the shaft 3. The balance amount that changes when the protrusion 52 is removed is weight M×r2 / r0. The axial center of the protrusion 53 located on the innermost periphery is r3 away from the center of rotation C of the shaft 3. The balance amount that changes when the protrusion 53 is removed is weight M×r3 / r0. In other words, the balance amount that can be adjusted by removing the protrusions 51, 52, and 53 and the balance amount that can be adjusted by attaching balance weights 6 of the same weight to the protrusions 51, 52, and 53 increase in the order of protrusion 51, protrusion 52, and protrusion 53. Therefore, the closer the axis of the protrusion 53 is to the rotation center C, the smaller the rotation moment that can be adjusted, and the more precisely the balance amount can be adjusted.

[0029] FIG. 9 is a cross-sectional view showing a modified example of the rotor according to the second embodiment. As shown in FIG. 9 , protrusions 51, 52, and 53 arranged in the same row along the radial direction from the center of rotation C of the shaft 3 are arranged so that the product of the distance from the center of rotation C to the axial center of each protrusion 51, 52, and 53 and its weight is equal to each other. For example, the weight of protrusion 51 located on the outermost periphery is defined as M1. The weight of protrusion 52 located in the middle is defined as M2, which is heavier than M1. The weight of protrusion 53 located on the innermost periphery is defined as M3, which is heavier than M2. In this case, for example, the weight M1×r1 / r0, which is the balance amount that changes when protrusion 51 is removed, the weight M2×r2 / r0, which is the balance amount that changes when protrusion 52 is removed, and the weight M3×r3 / r0, which is the balance amount that changes when protrusion 53 is removed, are arranged so that they are equal to each other. As a result, the rotor 2 can be adjusted to the same balance amount even if any of the protrusions 51, 52, and 53 is removed to reduce the weight. As a result, when adjusting the rotational balance during the manufacture of the rotor 2, it is only necessary to check the phases of the protrusions 51, 52, and 53, which can contribute to reducing adjustment errors.

[0030] Furthermore, for the multiple protrusions 51, 52, and 53 arranged in the same row along the radial direction from the center of rotation C of the shaft 3, the weight of the attached balance weight 6 can be adjusted according to the outer diameter of the protrusions 51, 52, and 53, so that the product of the weight and the distance from the center of rotation C to the axial center of each protrusion 51, 52, and 53 becomes equal to each other. As a result, the rotor 2 can be adjusted to the same amount of balance even if the balance weight 6 is attached to any of the protrusions 51, 52, and 53 to increase its weight. Even in this case, when adjusting the rotational balance during manufacture of the rotor 2, it is only necessary to check the phase of the protrusions 51, 52, and 53, which contributes to reducing adjustment errors.

[0031] The arrangement of the protrusions 51, 52, and 53 is not limited to the configuration shown in Figures 7 to 9. For example, the protrusions may be configured so that two or more are arranged radially from the rotation center C of the shaft 3. The protrusions may be configured so that two or more are arranged circumferentially on a concentric circle centered on the rotation center C of the shaft 3. The protrusions are not limited to the configuration having three protrusions shown in the figures, and may be configured so that two or more protrusions are included. The protrusions may also be configured as a single protrusion.

[0032] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies or may be combined with other embodiments. Furthermore, it is also possible to omit or modify part of the configurations without departing from the spirit of the invention.

[0033] REFERENCE SIGNS LIST 1 stator, 2 rotor, 3 shaft, 4 rotor core, 5 end ring, 6 balance weight, 50, 51, 52, 53 protrusions, 50a, 50b, 50c convex portions, 60 cylindrical portion, 61 holding portion, 100 electric motor.

Claims

1. A rotor comprising: a rotor core fixed to a shaft that serves as a rotating axis; and an end ring provided on at least one of both ends of the rotor core in the direction of the rotation axis of the shaft, wherein the end ring provided on at least one of both ends of the rotor core has a plurality of protrusions that protrude in the direction of the rotation axis of the shaft, and each of the protrusions is removable to adjust the rotational balance, and is configured so that a balance weight can be attached to increase the weight of the end ring to adjust the rotational balance.

2. A rotor as described in claim 1, characterized in that the balance weight attached to the protrusion has a cylindrical portion with an inner shape that fits into the protrusion, and a holding portion that keeps the cylindrical portion fitted into the protrusion.

3. A rotor according to claim 1 or 2, characterized in that each of the protrusions is formed by a plurality of convex portions having different outer shapes so that the outer shapes become smaller in stages along the rotational axis direction of the shaft.

4. A rotor as claimed in any one of claims 1 to 3, characterized in that at least two of the protrusions are provided radially from the centre of rotation of the shaft, and at least two of the protrusions are provided circumferentially on a concentric circle centred on the centre of rotation.

5. The rotor according to claim 4, wherein the plurality of protrusions provided along the radial direction from the center of rotation of the shaft have the same shape and weight.

6. A rotor as described in claim 4, characterized in that the multiple protrusions arranged radially from the center of rotation of the shaft are arranged so that the product of the distance from the center of rotation to the axial center of each protrusion and its weight is equal to each other.

7. An electric motor comprising: a cylindrical stator; and a rotor according to any one of claims 1 to 6 that is surrounded by the stator and driven to rotate.

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