Rotor core, rotor, and motor

Abstract

A plurality of pairs of V-shaped magnet slots (20) are formed in the rotor core (10a). A plurality of holes (30) are formed between each pair of magnet slots. The hole (30) includes a substantially isosceles triangle (T, 31) whose apex angle faces the center of the rotor core and a circular arc (32) connected to the bottom side of the isosceles triangle. At least a portion of the arc is located further outward in the radial direction of the rotor core than a first line segment connecting the outermost portion of the magnet slot.

Description

Technical Field

[0001] Embodiments of the present invention relate to a rotor core, a rotor, and a motor. Background Art

[0002] A plurality of pairs of magnet slots arranged in a V shape are formed on the end surface of the rotor core of the motor, and a magnet is inserted into each magnet slot. In addition, holes are formed in the rotor core for the purpose of reducing the weight of the rotor core and the inertia (for example, refer to Japanese Patent No. 6987310). However, when holes are formed inside each pair of magnet slots arranged in a V shape, the flow of magnetic flux is hindered, and the torque is reduced.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 6987310 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In order to increase the torque, it is considered to rotate the V-shaped front end of each pair of magnet slots and extend them radially inward of the core. However, in this case, the area of ​​the rotor core where the holes can be formed becomes smaller. As a result, it is difficult to achieve lightweight and reduce inertia.

[0008] Therefore, a lightweight rotor core, rotor, and motor that can reduce inertia without reducing torque are desired.

[0009] Solutions to Solve Problems

[0010] According to a first embodiment of the present disclosure, a rotor core is provided, in which a plurality of pairs of magnet slots extending along the axial direction of the rotor core are formed, the plurality of pairs of magnet slots being arranged at equal intervals in the circumferential direction of the rotor core in a radial cross section of the rotor core, each pair of the plurality of pairs of magnet slots comprising a first magnet slot inclined in a counterclockwise direction relative to a radius of the rotor core and a second magnet slot inclined in a clockwise direction relative to the radius of the rotor core, and a spaced-apart magnet slot extending along the axial direction of the rotor core is formed between the first magnet slot and the second magnet slot in each pair of the magnet slots. A plurality of holes extending in the axial direction of the core, in the radial cross section of the rotor core, the plurality of holes are respectively composed of a substantially isosceles triangle with its vertex facing the center of the rotor core and an arc protruding from the base of the isosceles triangle toward the radial outside of the rotor core, in the radial cross section of the rotor core, at least a portion of the arc of the hole is located radially outside the rotor core compared to a first line segment in the radial cross section of the rotor core, and the first line segment is a line segment between a portion of the first magnet slot located at the outermost side of the rotor core and a portion of the second magnet slot located at the outermost side of the rotor core.

[0011] The objects, features and advantages of the present invention will become more apparent from the following description of the embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is an axial cross-sectional view of the electric motor according to the first embodiment of the present invention.

[0013] Figure 2 This is a radial cross-sectional view of the rotor of the electric motor according to the first embodiment.

[0014] Figure 3 yes Figure 2 A first enlarged partial view of the rotor is shown.

[0015] Figure 4 yes Figure 2 A second enlarged view of a portion of the rotor is shown.

[0016] Figure 5 yes Figure 2 A third enlarged partial view of the rotor is shown.

[0017] Fig. 6A It is a partial cross-sectional view showing the magnetic flux of a motor in the related art.

[0018] Figure 6B : is a graph showing the relationship between time and torque of a motor in the related art.

[0019] Fig. 7AThis is a partial cross-sectional view showing the magnetic flux of the electric motor according to the first embodiment.

[0020] Figure 7B 1 is a diagram showing the relationship between time and torque of the electric motor according to the first embodiment.

[0021] Figure 8 This is a radial cross-sectional view of the rotor core of the electric motor according to the first embodiment. DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In all the drawings, corresponding components are denoted by common reference numerals.

[0023] Figure 1 This is a cross-sectional view of the motor in the axial direction according to the first embodiment of the present invention. Figure 1 As shown, the motor 1 includes a stator 9 and a rotor 10 rotatably supported by the stator 9. A first bearing 7 and a second bearing 8 are arranged on the inner circumferential surface of the stator 9. Moreover, a shaft portion 5 passing through the rotor 9 is rotatably supported by the stator 9 by the first bearing 7 and the second bearing 8. In addition, a detector 6 for detecting the rotation speed of the shaft portion 5 is installed at one end of the stator 9.

[0024] Figure 2 This is a radial cross-sectional view of the rotor of the electric motor according to the first embodiment. Figure 2 The rotor 10 shown is in a substantially annular shape and has a through hole at the center for the shaft portion 5. However, as will be described below, the outer peripheral surface of the rotor 10 is preferably not smooth.

[0025] A plurality of pairs of magnet slots 20 extending along the axial direction of the rotor 10 are formed on the rotor 10 at equal intervals in the circumferential direction. Each pair of magnet slots 20 includes a first magnet slot 21 tilted counterclockwise relative to the radius of the rotor 10 and a second magnet slot 22 tilted clockwise relative to the radius of the rotor 10. The absolute values ​​of the tilt angles of the first magnet slot 21 and the second magnet slot 22 relative to the radius are preferably equal to each other.

[0026] Permanent magnets 21a and 21b are inserted into the magnet slots 21 and 22, respectively. Therefore, the magnet slots 21 and 22 are substantially rectangular parallelepiped shapes corresponding to the shapes of the permanent magnets 21a and 21b, and are preferably the same shape as each other. In addition, in order to easily insert and remove the permanent magnets 21a and 21b, it is preferable to form additional cutouts in the magnet slots 21 and 22.

[0027] The magnet slots 21 and 22 are arranged to converge toward the inner side in the radial direction of the rotor 10. In other words, the magnet slots 21 and 22 are formed in a substantially V-shape. However, the magnet slots 21 and 22 do not need to be connected to each other in the inner side in the radial direction.

[0028] and, Figure 2 In the embodiment, the outer periphery of the rotor 10 is composed of a plurality of first outer periphery portions 11 and a plurality of second outer periphery portions 12 respectively connecting the plurality of first outer periphery portions 11. In other words, the plurality of first outer periphery portions 11 and the plurality of second outer periphery portions 12 are alternately arranged in the circumferential direction of the rotor 10. Figure 2 It can be seen that the plurality of first peripheral portions 11 correspond to respective regions of the plurality of pairs of magnet slots 20. Furthermore, the plurality of second peripheral portions 12 correspond to regions between two adjacent pairs of magnet slots 20 among the plurality of pairs of magnet slots 20, respectively.

[0029] Furthermore, the outermost portion of the first outer peripheral portion 11 is located outside the radial direction of the rotor 10 relative to the outermost portion of the second outer peripheral portion 12. In other words, the plurality of first outer peripheral portions 11 as convex portions and the plurality of second outer peripheral portions 12 as concave portions are alternately arranged in the circumferential direction of the rotor 10. The first outer peripheral portion 11 as a whole is located on a circle whose radius is a line segment connecting the center O of the rotor 10 and the outermost portion of the first outer peripheral portion 11 (hereinafter referred to as Figure 8 Furthermore, the outermost portion of the second peripheral portion 12 is preferably located radially outside the rotor 10 relative to a pair of permanent magnets 21b and another pair of permanent magnets 21a in two pairs of magnet slots 20 adjacent to the second peripheral portion 12.

[0030] Thus, since the outer circumference of the rotor 10 is not a perfect circle, when the motor 1 having the rotor 10 is driven, the change in the number of magnetic flux linkages becomes small, and as a result, it is possible to prevent the cogging torque and torque ripple from becoming larger. Therefore, in the first embodiment of the present invention, the controllability of the motor 1 having the rotor 10 can be improved.

[0031] and, Figure 2 In the example, the outermost part of the first peripheral part 11 is composed of at least one curve. The first peripheral part 11 in one example is defined by the formula r=D-E / cos(Fθ) (D, E, F are positive numbers). In this case, the first peripheral part 11 is reliably located inside the above-mentioned circle and becomes smooth.

[0032] Moreover, the outermost portion of the second peripheral portion 12 is respectively composed of at least one straight line. In the illustrated embodiment, the outermost portion of the second peripheral portion 12 includes a straight line substantially parallel to one side of a pair of permanent magnets 21a and one side of another pair of permanent magnets 21b in two pairs of magnet slots 20 adjacent to the second peripheral portion 12.

[0033] In an embodiment not shown in the figure, the outermost portion of the first outer peripheral portion 11 may be composed of at least one straight line, and the outermost portion of the second outer peripheral portion 12 may be composed of at least one curved line. Furthermore, both the outermost portion of the first outer peripheral portion 11 and the outermost portion of the second outer peripheral portion 12 may be composed of at least one straight line, and further, both the outermost portion of the first outer peripheral portion 11 and the outermost portion of the second outer peripheral portion 12 may be composed of at least one curved line. Furthermore, at least one of the outermost portion of the first outer peripheral portion 11 and the outermost portion of the second outer peripheral portion 12 may be composed of at least one straight line and at least one curved line. In such a case, the outermost portions of the plurality of first outer peripheral portions 11 are also located on the outer side of the rotor 10 in the radial direction compared to the outermost portions of the plurality of second outer peripheral portions 12, so that the outer periphery of the rotor 10 has a shape different from a perfect circle. Therefore, it can be seen that the same effect as the above-mentioned embodiment is obtained.

[0034] In a modification of the first embodiment (not shown), the first outer peripheral portion 11 may be located radially inward of the rotor 10 relative to the second outer peripheral portion 12. In this case, the same effects as those of the above embodiment are obtained, and the modification is within the scope of the first embodiment.

[0035] like Figure 2 As shown, a plurality of holes 30 extending in the axial direction of the rotor 10 are formed on the end surface of the rotor 10 at equal intervals in the circumferential direction. Figure 3 yes Figure 2 The first enlarged view of the rotor is shown. Figure 2 and Figure 3 It can be seen that the plurality of holes 30 are respectively formed in the regions of the rotor 10 corresponding to the first outer peripheral portion 11. Strictly speaking, the holes 30 are formed between the first magnet slot 21 and the second magnet slot 22 of the pair of magnet slots 20. The shape of the holes 30 will be described below.

[0036] Similarly, a plurality of groups of holes 41 and 42 extending in the axial direction of the rotor 10 are formed at equal intervals in the circumferential direction on the end surface of the rotor 10. Figure 2 and Figure 3 It can be seen that a plurality of groups consisting of holes 41 and 42 are respectively formed in the region of the rotor 10 corresponding to the second outer peripheral portion 12. Furthermore, the hole 41 is formed on the outer side in the radial direction of the rotor 10 compared to the hole 42, and the hole 41 is smaller than the hole 42. In one example, the hole 41 is circular, and the hole 42 is an oblong whose width decreases from the inner side to the outer side in the radial direction of the rotor 10. Alternatively, at least one of the holes 41 and 42 may be an oblong or elliptical shape.

[0037] The shape of the hole 30 is described below. Figure 3As shown, the hole 30 is composed of a first portion 31 and a second portion 32 located radially outward of the rotor 10 relative to the first portion 31. The center lines of the first portion 31 and the second portion 32 are located on a radius R of the rotor 10. In addition, in the following Figure 8 In the present specification, the “radius R” is a portion of a straight imaginary line extending from the center O of the rotor 10 and passing through the center line of the hole 30. In other words, the “radius R” is a line segment connecting the center O of the rotor 10 and the edge of the first outer peripheral portion 11 from the center O.

[0038] like Figure 3 As shown, the first portion 31 is in the shape of a substantially isosceles triangle T whose vertex is directed toward the center O of the rotor 10. Furthermore, the second portion 32 is in the shape of an arc, such as a semicircle, protruding from the base of the isosceles triangle T toward the outside in the radial direction of the rotor 10. The first portion 31 and the second portion 32 are preferably smoothly connected to each other.

[0039] The reason for setting it as a "substantially isosceles triangle" is that it includes cases where the vertex of the isosceles triangle T has rounded corners, where the two hypotenuses 33 of the isosceles triangle T are each composed of a plurality of straight lines, and where the two hypotenuses 33 of the isosceles triangle T each include a curve, which are different from a perfect isosceles triangle. Furthermore, the arc as the second portion 32 may be longer or shorter than the arc of a semicircle. In addition, the arc as the second portion 32 may be an arc of an ellipse.

[0040] Figure 3 In the embodiment, in a pair of magnet slots 20, a portion of the first magnet slot 21 located at the outermost side of the rotor 10 is referred to as "X", and a portion of the magnet slot 22 located at the outermost side of the rotor 10 is referred to as "X'". Furthermore, at least a portion of the arc as the second portion 32, for example, point A, is located radially outside the rotor 10 relative to the straight line XX'.

[0041] In this way, since at least a portion of the hole 30 is located outside the radial direction of the rotor 10 relative to the straight line XX', the length of the hole 30 on the radius R is longer than the length of the side of the permanent magnets 21a and 21b facing the hole 30 (equivalent to the width of the permanent magnet). Therefore, in the first embodiment, a large hole 30 can be formed, and as a result, the rotor 10 can be made lighter and the motor 1 can be made faster. In addition, the second portion 32 is an arc, so that the flow of magnetic flux is not hindered when the motor 1 having the rotor 10 is driven.

[0042] As described above, the first outer peripheral portion 11 forming the hole 30 preferably protrudes outward in the radial direction of the rotor 10 more than the second outer peripheral portion 12. In this case, the hole 30 can be formed longer in the radial direction of the rotor 10 only in the protruding portion of the first outer peripheral portion 11. Therefore, it is known that the hole 30 can be enlarged and the rotor 10 can be reduced in weight.

[0043] Figure 4 yes Figure 2 A second enlarged detail of the rotor is shown. Figure 4 , each hypotenuse 33 of the first portion 31 of the hole 30 has a first straight portion 33a extending from the base of the substantially isosceles triangle T and a second straight portion 33b extending from the distal end of the first straight portion 33a toward the point B of the vertex of the substantially isosceles triangle T. Figure 3 and Figure 4 It can be seen that the first straight line portion 33a is connected to the second portion 32. In addition, the intersection B between the two second straight line portions 33b may also have an arc.

[0044] Figure 4 In FIG. 3 , the first straight line portion 33a and the second straight line portion 33b intersect at the intersection point C. Figure 3 and Figure 4 It can be seen that the intersection point C is located outside the substantially isosceles triangle T relative to the hypotenuse corresponding to the intersection point C. In other words, Figure 4 The angle formed by the radius R and the first straight portion 33a is shown to be smaller than the angle formed by the radius R and the second straight portion 33b.

[0045] Therefore, the first portion 31 having the above-mentioned shape is larger than the first portion 31 which is a perfect isosceles triangle T. Furthermore, the hole 30 becomes larger, and accordingly, the weight of the rotor 10 can be reduced. Moreover, the second straight portion 33b extends from the vicinity of the point B in such a manner as to enlarge the hole 30, but the first straight portion 33a extends in such a manner as to suppress the enlargement of the hole 30. In other words, the hole 30 is preferably formed to be larger on the radial inner side of the rotor 10 and smaller on the radial outer side of the rotor 10. Thus, it is possible to avoid the hole 30 from becoming extremely large, and it is possible to suppress the flow of the magnetic flux on the radial outer side of the rotor 10 from being obstructed.

[0046] and, Figure 4In a pair of magnet slots 20, a portion of the first magnet slot 21 closest to the radius R is set to "Y", and a portion of the second magnet slot 22 also closest to the radius R is set to "Y'". Moreover, the vertex B on the vertex side of the substantially isosceles triangle T is located near the straight line YY'. The vertex B may also be located at the intersection of the straight line YY' and the radius R, and may also be located on the radial inside of the rotor 10 relative to the straight line YY'. In this way, since the end of the hole 30 located on the radial inside of the rotor 10 is located near the straight line YY', the hole 30 becomes larger, and as a result, the rotor 10 can be made lighter.

[0047] Furthermore, the vertex B is preferably located radially outside the straight line YY' in the rotor 10. This ensures the strength of the rotor 10. When the rotor 10 is formed by stacking a plurality of magnetic plates in the axial direction of the rotor 10, the strength of the plurality of magnetic plates can be ensured, so the above structure is particularly preferred.

[0048] and, Figure 5 yes Figure 2 The third partial enlarged view of the rotor is shown. Figure 5 In the example shown, with radius R (refer to Figure 3 , Figure 4 ) The maximum width L2 of the hole 30 perpendicular to the rotor 10 is approximately equivalent to the base of the substantially isosceles triangle T. Moreover, the maximum width L2 is preferably less than 1 / 3 of the length L1 of the straight line XX'. In this way, the hole 30 can be prevented from becoming extremely large, and the flow of magnetic flux outside the rotor 10 in the radial direction can be suppressed from being hindered.

[0049] and, Figure 5 The line segment L3 shown is the length between the edge 5a of the through hole of the rotor 10 into which the shaft portion 5 is inserted and the outermost portion of the rotor 10, and shows a length of a portion on the radius R. Furthermore, the line segment L4 shows the length between the outermost portion of the hole 30 in the radial direction of the rotor 10 and the outermost portion in the radial direction of the rotor 10. In other words, the line segment L4 is the shortest distance between the first outer peripheral portion 11 and the second portion 32 of the hole 30.

[0050] and, Figure 5 The length of the line segment L3 is preferably shorter than 10 times the length of the line segment L4. In one example, the length of the line segment L3 is 10 times the length of the line segment L4. In this case, the hole 30 can be kept relatively large, and the flow of the magnetic flux on the radially outer side of the rotor 10 can be suppressed from being obstructed.

[0051] Here, Fig. 6A is a partial cross-sectional view showing the magnetic flux of a motor in the prior art, Fig. 7A This is a partial cross-sectional view showing the magnetic flux of the electric motor according to the first embodiment. Fig. 6A The motor 1' shown comprises a stator 9' and a rotor 10'. Fig. 7A The motor 1 shown includes a stator 9 and the above-mentioned rotor 10. The structure of the rotors 10 and 10' is well known, so the description thereof is omitted. Fig. 6A and Fig. 7A It is understood that even when the holes 30, 41, 42 are formed as in the motor 1, the flow of magnetic flux is not blocked by the holes 30 etc. Furthermore, the motor 1 is lighter than the motor 1' by the amount that the holes 30, 41, 42 are formed.

[0052] and, Figure 6B is a diagram showing the relationship between time and torque of a motor in the prior art, Figure 7B 1 is a diagram showing the relationship between time and torque of the motor according to the first embodiment. In the above-mentioned figure, the horizontal axis shows time, and the vertical axis shows the torque of the motor 1, 1'. Figure 6B In the example, the maximum torque of the motor 1' is between 100 Nm and 101 Nm. Figure 7B The maximum value of the torque of the motor 1 is between 91.5 Nm and 92 Nm. That is, even when the holes 30, 41, and 42 are formed, the reduction in torque can be suppressed to less than 10%.

[0053] Thus, even when the holes 30, 41, and 42 are formed, the torque does not decrease significantly, and a practical torque can be generated. It is clear to those skilled in the art that the same effect can be obtained when only the hole 30 is formed in the first embodiment.

[0054] Therefore, in the first embodiment of the present invention, the rotor 10 can be lightweight by forming the hole 30, etc., and the inertia can be reduced without significantly reducing the torque. In other words, a lightweight rotor 10 can be provided without reducing the torque and reducing the inertia. Therefore, the motor 1 having the rotor 10 can achieve high acceleration.

[0055] and, Figure 8 This is a radial cross-sectional view of the rotor core of the electric motor according to the first embodiment. Figure 8 The rotor core 10a of the rotor 10 shown is formed from Figure 2 The rotor 10 shown is a rotor core after all permanent magnets 21a, 21b and the rotor 5 are removed. Figure 8 Other elements and references shown Figure 2 The elements of the description are the same. Figure 8 The rotor core 10a shown and Figure 1 The electric motor 1 shown in FIG. 1 and FIG. 2 is also included in the scope of the first embodiment of the present invention.

[0056] The embodiments of the present disclosure have been described in detail, but the present disclosure is not limited to the above-mentioned embodiments. The above-mentioned embodiments can be subjected to various additions, substitutions, changes, partial deletions, etc. without departing from the scope of the main purpose of the invention, or without departing from the idea and main purpose of the present invention derived from the contents recorded in the claims and their equivalents. For example, in the above-mentioned embodiments, the order of each action and the order of each process are shown as an example and are not limited to the above-mentioned contents. Moreover, the same applies to the case where numerical values ​​or formulas are used in the description of the above-mentioned embodiments. Moreover, embodiments in which several embodiments of the above-mentioned embodiments are appropriately combined are included in the scope of the present disclosure.

[0057] Explanation of symbols

[0058] 1—motor, 5—shaft, 9—stator, 10—rotor, 10a—rotor core, 11—first peripheral portion, 12—second peripheral portion, 20—magnet slot, 21—first magnet slot, 22—second magnet slot, 21a, 21b—permanent magnet, 30—hole, 31—first portion, 32—second portion, 33—hypotenuse, 33a—first straight portion, 33b—second straight portion, 41, 42—holes, T—roughly isosceles triangle.

Claims

1. A rotor core, characterized in that: The rotor core is formed with a plurality of pairs of magnet slots extending along the axial direction of the rotor core. The plurality of pairs of magnet slots are arranged at equal intervals in a circumferential direction of the rotor core in a radial cross section of the rotor core. Each pair of magnet slots of the plurality of pairs of magnet slots comprises a first magnet slot inclined in a counterclockwise direction relative to a radius of the rotor core and a second magnet slot inclined in a clockwise direction relative to the radius of the rotor core. Furthermore, a plurality of holes extending along the axial direction of the rotor core are formed between the first magnet slot and the second magnet slot in each pair of magnet slots. In a radial cross section of the rotor core, the plurality of holes are respectively formed by a substantially isosceles triangle whose apex is directed toward the center of the rotor core and an arc protruding from the base of the isosceles triangle toward the outside in the radial direction of the rotor core. In the radial cross-section of the rotor core, at least a portion of the arc of the hole is located radially outside the rotor core compared to a first line segment, and the first line segment is a line segment between a portion of the first magnet slot located at the outermost side of the rotor core and a portion of the second magnet slot located at the outermost side of the rotor core.

2. The rotor core according to claim 1, characterized in that: The outer periphery of the rotor core is composed of a plurality of first outer periphery portions and a plurality of second outer periphery portions respectively connecting the plurality of first outer periphery portions. The plurality of first peripheral portions correspond to respective regions of the plurality of pairs of magnet slots. The plurality of second peripheral portions correspond to the areas between two adjacent pairs of magnet slots among the plurality of pairs of magnet slots, respectively. The outermost portions of the plurality of first outer peripheral portions are located radially outward of the rotor core relative to the outermost portions of the plurality of second outer peripheral portions.

3. The rotor core according to claim 2, characterized in that: The plurality of first peripheral portions are composed of at least one curve, The plurality of second peripheral portions are formed by at least one straight line.

4. The rotor core according to any one of claims 1 to 3, characterized in that: The two hypotenuses of the substantially isosceles triangle respectively have a first straight line portion extending from the base and a second straight line portion extending from a distal end of the first straight line portion toward a vertex of the substantially isosceles triangle. An intersection point between the first straight line portion and the second straight line portion is located outside the substantially isosceles triangle with respect to a hypotenuse corresponding to the intersection point.

5. The rotor core according to any one of claims 1 to 4, characterized in that: The length of the base of the substantially isosceles triangle is less than or equal to 1 / 3 of the length of the first line segment.

6. The rotor core according to any one of claims 1 to 5, characterized in that: A through hole is formed for inserting the shaft portion of the rotor core. A length of a third line segment located on the radius of the rotor core and connected from the outer edge of the through hole to the first outer peripheral portion is shorter than 10 times a distance from the first outer peripheral portion to the arc on the third line segment.

7. A rotor, characterized in that: have: The rotor core according to any one of claims 1 to 6; a shaft portion inserted into the rotor core; and Magnets are respectively inserted into the multiple pairs of magnet slots of the rotor core.

8. An electric motor, characterized in that: have: The rotor of claim 7; and The stator is arranged around the rotor.

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