Rotating electric machine and rotor thereof

Abstract

The object of the present invention is to obtain a rotary electric motor and its rotor that can reduce the stress generated in the rotor core. A pair of second stress-relieving grooves (33h) are provided on the inner circumference of the rotor core (33). The pair of second stress-relieving grooves (33h) are located on the rotor core (33) at a position offset from each other by 180° in the circumferential direction and are opposite to each other. In addition, the pair of second stress-relieving grooves (33h) are located at a position offset from a pair of keys (33f) in the circumferential direction of the rotor core (33). Each protrusion (33i) is provided between the first stress-relieving groove (33g) and the second stress-relieving groove (33h).

Description

Technical Field

[0001] This disclosure relates to a rotary electric machine and its rotor. Background Technology

[0002] In conventional rotary electric motor rotors, a key portion is provided on the inner circumference of the rotor core. A recess is provided near the key portion (for example, see Patent Document 1). Existing technical documents Patent documents

[0003] Patent Document 1: Japanese Patent No. 5567775 Summary of the Invention

[0004] In the conventional rotor described above, stress generated in the rotor core can be reduced by providing a recess near the key. However, to increase the rotor's maximum speed, it is necessary to further reduce the stress generated in the rotor core.

[0005] This disclosure was made to solve the above-mentioned technical problems, and its purpose is to obtain a rotating electric motor and its rotor that can reduce the stress generated in the rotor core.

[0006] The rotor of the rotary electric motor disclosed herein is characterized by comprising: a rotor body having a cylindrical rotor core and a plurality of permanent magnets, the cylindrical rotor core having a shaft hole at its center, the plurality of permanent magnets being fixed to the rotor core, and the rotor body having a plurality of magnetic poles spaced apart from each other in the circumferential direction of the rotor core; and a shaft inserted into the shaft hole and fixed to the rotor core, the shaft having a keyway on its outer circumference, and a key, a first stress-relieving groove, a second stress-relieving groove, and a protrusion on the inner circumference of the rotor core, the key fitting into the keyway, the first stress-relieving groove, and the second stress-relieving groove. The groove is located near the key portion in the circumferential direction of the rotor core. The bottom surface of the first stress relief groove in the cross section perpendicular to the axial direction of the rotor core is formed by one or more first arcs, including a first maximum arc which is the largest arc with the largest radius. The bottom surface of the second stress relief groove in the cross section perpendicular to the axial direction of the rotor core is formed by one or more second arcs, including a second maximum arc which is the largest arc with the largest radius. The protrusion is located between the first stress relief groove and the second stress relief groove and is in contact with the outer periphery of the shaft. In the cross section perpendicular to the axial direction of the rotor core, the protrusion is located between two adjacent d-axises.

[0007] The rotating electric machine and its rotor according to this disclosure can reduce the stress generated in the rotor core. Attached Figure Description

[0008] Figure 1 This is a schematic cross-sectional view of the rotary motor according to Embodiment 1. Figure 2 yes Figure 1 A cross-sectional view of the rotor along line II-II. Figure 3 It is an enlarged representation Figure 2 A partial sectional view. Figure 4 This is a cross-sectional view of the rotor in Embodiment 2. Figure 5 This is a cross-sectional view of the rotor in Embodiment 3. Figure 6 This is a cross-sectional view of the rotor in embodiment 4. Figure 7 This is a table showing the analysis results of the maximum principal stress generated in the rotor core of Embodiments 1 to 4. Figure 8 It means in Figure 7 Contour plot of the deformation of the rotor core when centrifugal force is applied to the rotor core of the comparative example. Figure 9 This is a contour map showing the deformation of the rotor core when centrifugal force is applied to the rotor core in Embodiment 4. Detailed Implementation

[0009] The embodiments will now be described with reference to the accompanying drawings. Implementation Method 1 Figure 1 This is a schematic cross-sectional view of the rotary electric motor of Embodiment 1, showing a section along the center of rotation. Figure 1 In the rotating motor, there is a cylindrical frame 1, a cylindrical stator 2, a rotor 3, a first bearing 4, and a second bearing 5.

[0010] The stator 2 has a cylindrical stator core 21 and multiple stator coils 22. The stator core 21 is held inside the frame 1. Furthermore, the stator core 21 is composed of multiple stator electromagnet plates. These multiple stator electromagnet plates are stacked along the axial direction of the stator core 21. The axial direction of the stator core 21 is parallel to the rotation center C0 of the rotor 3. Figure 1 The left and right directions.

[0011] The rotor 3 is disposed inside the stator core 21. In addition, the rotor 3 has a rotor body 31 and a shaft 32.

[0012] The rotor body 31 has a cylindrical rotor core 33, multiple permanent magnets 34, a circular first end plate 35, and a circular second end plate 36.

[0013] A shaft hole 33a is provided at the center of the rotor core 33. The shaft 32 is inserted into the shaft hole 33a and fixed to the rotor core 33. In addition, the shaft 32 is fixed to the rotor core 33 by press-fitting or thermoforming. Furthermore, the shaft 32 is held in place by the first bearing 4 and the second bearing 5 so that it can rotate relative to the frame 1.

[0014] The rotor body 31 rotates together with the shaft 32 around the rotation center C0. Furthermore, the rotor body 31 is positioned between the first bearing 4 and the second bearing 5.

[0015] The rotor core 33 is composed of multiple rotor electromagnetic steel plates. These plates are stacked along the axial direction of the rotor core 33. The axial direction of the rotor core 33 is parallel to the rotation center C0. Figure 1 The left and right directions.

[0016] The outer peripheral surface of the rotor core 33 is separated from the inner peripheral surface of the stator core 21 by an air gap.

[0017] Multiple permanent magnets 34 are embedded within the rotor core 33. A first end plate 35 is in contact with the first axial end face of the rotor core 33. The first axial end face is the end face opposite to the first bearing 4. A second end plate 36 is in contact with the second axial end face of the rotor core 33. The second axial end face is the end face opposite to the second bearing 5.

[0018] That is, the rotor core 33 is sandwiched between the first end plate 35 and the second end plate 36. This prevents the multiple permanent magnets 34 from scattering from the rotor core 33. The shaft 32 passes through the first end plate 35 and the second end plate 36.

[0019] To adjust rotational balance, a balance hole (not shown) is provided on the first end plate 35 or the second end plate 36, or a balance plate 37 is attached.

[0020] Figure 2 yes Figure 1 A cross-sectional view of the rotor 3 along line II-II, showing a section perpendicular to the axial direction of the rotor core 33. Multiple magnet mounting portions 33b are provided in the rotor core 33. These multiple magnet mounting portions 33b are arranged radially away from the shaft hole 33a in the rotor core 33. The radial direction of the rotor core 33 is orthogonal to the rotation center C0.

[0021] Furthermore, multiple magnet mounting portions 33b are arranged at equal intervals around the rotor core 33 in the circumferential direction. The circumferential direction of the rotor core 33 is along the direction of a circle centered on the rotation center C0.

[0022] Each magnet mounting portion 33b has a first insertion hole 33c and a second insertion hole 33d. When viewed in a cross section perpendicular to the axial direction of the rotor core 33, the first insertion hole 33c and the second insertion hole 33d in each magnet mounting portion 33b are configured in a V-shape that opens radially outward toward the rotor core 33.

[0023] Multiple permanent magnets 34 are arranged along the axial direction of the rotor core 33 and inserted into the first insertion hole 33c and the second insertion hole 33d in each magnet mounting part 33b. The first insertion hole 33c and the second insertion hole 33d are continuously arranged throughout the axial direction of the rotor core 33.

[0024] Multiple magnetic poles 31a are formed on the rotor body 31. These magnetic poles 31a are arranged at equal intervals around the rotor core 33 in the circumferential direction. Figure 2 In the rotor body 31, eight magnetic poles 31a are formed on the outer periphery. Each magnetic pole 31a consists of a magnet mounting part 33b and a plurality of permanent magnets 34 mounted on the magnet mounting part 33b.

[0025] A plurality of lightweight holes 33e are provided in the rotor core 33. Each lightweight hole 33e is provided between two adjacent magnet mounting portions 33b in the circumferential direction of the rotor core 33. Furthermore, each lightweight hole 33e is provided continuously throughout the axial direction of the rotor core 33.

[0026] Each lightweight hole 33e has the function of making the rotor core 33 lighter. In addition, each lightweight hole 33e can also have the function of adjusting the rotational balance of the rotor 3.

[0027] A pair of keyways 32a are provided on the outer periphery of the shaft 32. Each keyway 32a is a straight line parallel to the rotation center C0. The pair of keyways 32a are arranged to be offset from each other by 180° in the circumferential direction of the rotor core 33.

[0028] A pair of key portions 33f are provided on the inner circumference of the rotor core 33. The pair of key portions 33f are located at a position 180° offset from each other in the circumferential direction of the rotor core 33 and are opposite to each other.

[0029] Each key portion 33f protrudes radially inward from the inner circumference of the rotor core portion 33 and fits into the corresponding keyway 32a.

[0030] Two pairs of first stress-relieving grooves 33g are provided on the inner circumference of the rotor core 33. Each pair of first stress-relieving grooves 33g is provided on both sides of the corresponding key portion 33f. That is, each first stress-relieving groove 33g is provided near the key portion 33f in the circumferential direction of the rotor core 33.

[0031] Each first stress-relieving groove 33g is a straight groove along the axial direction of the rotor core 33. The bottom surface of the first stress-relieving groove 33g in a section perpendicular to the axial direction of the rotor core 33 is formed by one or more first circular arcs. Furthermore, the one or more first circular arcs includes a first maximum circular arc. The first maximum circular arc is the arc with the largest radius among the one or more first circular arcs.

[0032] The two pairs of first stress relief grooves 33g suppress stress concentration at a pair of key sections 33f when the rotor 3 rotates.

[0033] A pair of second stress-relieving grooves 33h are provided on the inner circumference of the rotor core 33. The pair of second stress-relieving grooves 33h are located at a position 180° offset from each other in the circumferential direction of the rotor core 33 and are opposite to each other. In addition, the pair of second stress-relieving grooves 33h are located at a position 90° offset from the pair of keys 33f in the circumferential direction of the rotor core 33.

[0034] Each second stress-relieving groove 33h is a straight groove along the axial direction of the rotor core 33. The bottom surface of the second stress-relieving groove 33h in a section perpendicular to the axial direction of the rotor core 33 is formed by one or more second circular arcs. Furthermore, the one or more second circular arcs includes a second largest circular arc. The second largest circular arc is the arc with the largest radius among the one or more second circular arcs.

[0035] Two pairs of protrusions 33i are provided on the inner circumference of the rotor core 33. Each pair of protrusions 33i is located on both sides of the corresponding second stress relief groove 33h. Each protrusion 33i is located between the first stress relief groove 33g and the second stress relief groove 33h. In addition, each protrusion 33i is in contact with the outer circumference of the shaft 32.

[0036] Furthermore, in a section perpendicular to the axial direction of the rotor core 33, each protrusion 33i is located between two adjacent d-axises. That is, each protrusion 33i is located at a position not on either d-axis. Each d-axis is a straight line connecting the center of the magnetic pole 31a to the center C0 of the shaft 32.

[0037] In a section perpendicular to the axial direction of the rotor core 33, the center of the shaft 32 is the same as the rotation center C0. Therefore, the center of the shaft 32 is also marked "C0".

[0038] Figure 3 It is an enlarged representation Figure 2 A partial sectional view. In Figure 3 In the first case, the bottom surface of the second stress-relieving groove 33h is formed by only one second circular arc, that is, only the second largest circular arc. However, the bottom surface of the second stress-relieving groove 33h can also be formed by multiple second circular arcs. In this case, the multiple second circular arcs are smoothly connected to each other in the circumferential direction of the rotor core 33.

[0039] When observing a section perpendicular to the axial direction of the rotor core 33, the center of each protrusion 33i lies on a straight line L4 that bisects the angle between the key line L3 and the second groove line L2. The key line L3 is a straight line passing through the center of the key 33f and the center C0 of the rotor core 33. The second groove line L2 is a straight line passing through the center C0 of the rotor core 33 and the center C2 of the circle along the second largest circular arc.

[0040] When observing a section perpendicular to the axial direction of the rotor core 33, the center C2 of each second maximum arc is located 90° off-center from the center of each key 33f in the circumferential direction of the rotor core 33. Furthermore, four protrusions 33i are arranged at 90° intervals in the circumferential direction of the rotor core 33.

[0041] In Embodiment 1, a pair of key portions 33f are located at a position offset from each other by 180°. Therefore, the second groove straight line L2 is a straight line on the center of the arc formed by connecting the center C0 of the rotor core 33 and the center of the other key portion 33f with the center C0 as the center.

[0042] In addition, Figure 3 In the rotor core 33, d1 is the maximum distance between the bottom surface of the first stress-relieving groove 33g and the outer periphery of the shaft 32 in the radial direction. d2 is the maximum distance between the bottom surface of the second stress-relieving groove 33h and the outer periphery of the shaft 32 in the radial direction.

[0043] R1 is the radius of the circle along the first maximum circular arc. R2 is the radius of the circle along the second maximum circular arc. C1 is the center of the circle along the first maximum circular arc. L1 is the first slot line, i.e., the line passing through the center C0 of the rotor core 33 and the center C1 of the circle along the first maximum circular arc.

[0044] Furthermore, the first imaginary circle Cv1 is a circle centered on the center C0 of the rotor core 33 and externally tangent to all the first stress-relieving grooves 33g. The second imaginary circle Cv2 is a circle centered on the center C0 of the rotor core 33 and externally tangent to all the second stress-relieving grooves 33h.

[0045] In the aforementioned rotary electric motor and its rotor 3, a pair of second stress-relieving grooves 33h are provided on the inner circumference of the rotor core 33. Furthermore, each protrusion 33i is disposed between the first stress-relieving groove 33g and the second stress-relieving groove 33h. Additionally, each protrusion 33i is located between two adjacent d-axises.

[0046] Therefore, the stress generated in the rotor core 33, especially the stress generated on the inner circumference of the rotor core 33, can be reduced. This improves the durability of the rotor core 33. Furthermore, the maximum speed of the rotor 3 can be increased.

[0047] Furthermore, each protrusion 33i is positioned off-axis, i.e., offset from the center of the magnetic pole 31a. Therefore, by pressing the shaft 32 into the rotor core 33, stress generated around each magnetic pole 31a is suppressed. This, in turn, suppresses the decrease in the fatigue life of the rotor core 33.

[0048] Furthermore, the center C2 of each second largest arc is located 90° offset from the center of each key portion 33f in the circumferential direction of the rotor core 33. This allows for more uniform deformation of the rotor core 33. Consequently, the air gap between the stator core 21 and the rotor core 33 becomes more uniform, improving the reliability and durability of the rotor core 33.

[0049] Furthermore, a pair of second stress-relieving grooves 33h are positioned 90° offset from a pair of keys 33f in the circumferential direction of the rotor core 33. Therefore, multiple regions on the inner circumference of the rotor core 33 that are in close contact with the outer circumference of the shaft 32 are evenly arranged along the circumferential direction of the rotor core 33. This prevents the rotor core 33 from deforming into an elliptical shape when the shaft 32 is inserted into the shaft hole 33a, thereby improving the reliability and durability of the rotor 3.

[0050] Furthermore, the center of each protrusion 33i is located on a straight line L4 that bisects the angle between the key line L3 and the second groove line L2. Therefore, the deformation of the rotor core 33 can be made more uniform. This, in turn, makes the air gap between the stator core 21 and the rotor core 33 more uniform, improving the reliability and durability of the rotor core 33.

[0051] Implementation Method 2 then, Figure 4 This is a cross-sectional view of rotor 3 in embodiment 2, showing the equivalent of Figure 1 The cross-section along line II-II. In Embodiment 2, when observing the cross-section perpendicular to the axial direction of the rotor core 33, d2 ≤ 3 × d1 × (R2 / R1) is satisfied. In particular, in Figure 4 In this case, d2 / d1 = 3 × (R2 / R1). Furthermore, R2 / R1 is 1.3.

[0052] The definitions of d1, d2, R1, and R2 are as follows: Figure 3 Their definitions are the same. Furthermore, besides... Figure 4 Apart from the structure shown, the structure of the rotary electric motor is the same as that in Embodiment 1.

[0053] According to the above structure, the stress generated on the inner circumference of the rotor core 33 can be reduced more reliably, and the durability of the rotor core 33 can be further improved.

[0054] Implementation Method 3 then, Figure 5This is a cross-sectional view of rotor 3 in embodiment 3, showing the equivalent of Figure 1 The cross section along line II-II. In embodiment 3, when observing the cross section perpendicular to the axial direction of the rotor core 33, d2 / d1 = 3 × (R2 / R1) is also satisfied. However, R2 / R1 is 1.8.

[0055] The definitions of d1, d2, R1, and R2 are as follows: Figure 3 Their definitions are the same. Furthermore, besides... Figure 5 Apart from the structure shown, the structure of the rotary electric motor is the same as that in Embodiment 1.

[0056] According to the above structure, the stress generated on the inner circumference of the rotor core 33 can be reduced more reliably, and the durability of the rotor core 33 can be further improved.

[0057] Implementation Method 4 then, Figure 6 This is a cross-sectional view of rotor 3 in embodiment 4, showing the equivalent of Figure 1 The cross-section along line II-II. In Embodiment 4, the radius R2 of the circle along the second largest circular arc is larger than the radius R2 of Embodiments 1 to 3. Furthermore, d2 / d1 is smaller than d2 / d1 of Embodiments 1 to 3.

[0058] The definitions of d1, d2, and R2 are as follows: Figure 3 Their definitions are the same. Furthermore, besides... Figure 6 Apart from the structure shown, the structure of the rotary electric motor is the same as that in Embodiment 1.

[0059] The same effect as in Implementation Method 1 can be achieved through the above structure.

[0060] Here, Figure 7 This is a table showing the analysis results of the maximum principal stress generated in the rotor core 33 of Embodiments 1 to 4, respectively. Figure 7 In the "First Stress Relief Groove" column, the maximum principal stress generated at the edge of the first stress relief groove 33g is shown. In the "Second Stress Relief Groove" column, the maximum principal stress generated at the edge of the second stress relief groove 33h is shown.

[0061] In addition, the "comparative example" is the same rotor core as the rotor core 33 of Embodiment 1, except that it does not have a pair of second stress relief grooves 33h.

[0062] Furthermore, the maximum principal stress is the maximum principal stress generated when the shaft 32 is pressed into the rotor core 33 and the centrifugal force generated by the rotation is added to the rotor core 33.

[0063] like Figure 7As shown, the maximum principal stress generated at the edge of the first stress relief groove 33g in Embodiments 1 to 4 is smaller than the maximum principal stress generated at the edge of the first stress relief groove 33g in the comparative example.

[0064] Furthermore, the maximum principal stress generated at the edge of the second stress relief groove 33h in Embodiment 1 is smaller than the maximum principal stress generated at the edge of the first stress relief groove 33g in the Comparative Example.

[0065] Furthermore, in Embodiment 2, the maximum principal stress generated at the edge of the first stress-relieving groove 33g is sufficiently smaller than the maximum principal stress generated at the edge of the first stress-relieving groove 33g in the comparative example. However, in Embodiment 2, the maximum principal stress generated at the edge of the second stress-relieving groove 33h is only slightly smaller than the maximum principal stress generated at the edge of the first stress-relieving groove 33g in the comparative example.

[0066] Furthermore, in Embodiment 3, the maximum principal stress generated at the edge of the first stress-relieving groove 33g is sufficiently smaller than the maximum principal stress generated at the edge of the first stress-relieving groove 33g in the comparative example. However, in Embodiment 3, the maximum principal stress generated at the edge of the second stress-relieving groove 33h is only slightly smaller than the maximum principal stress generated at the edge of the first stress-relieving groove 33g in the comparative example.

[0067] As shown in the analysis results of embodiments 2 and 3, the dimensions of the first stress relief groove 33g and the second stress relief groove 33h can be appropriately selected as long as they satisfy the range of d2≤3×d1×(R2 / R1).

[0068] In Embodiment 4, the maximum principal stress generated at the edge of the first stress-relieving groove 33g is smaller than the maximum principal stress generated at the edge of the first stress-relieving groove 33g in Embodiment 1. Furthermore, in Embodiment 4, the maximum principal stress generated at the edge of the second stress-relieving groove 33h is smaller than the maximum principal stress generated at the edge of the second stress-relieving groove 33h in Embodiment 1.

[0069] Next, the analysis results of the radial deformation of the rotor core 33 will be explained. Figure 8 It means in Figure 7 Contour plot of the deformation of the rotor core when the rotor core of the comparative example is subjected to centrifugal force generated by rotation. Figure 9 This is a contour map showing the amount of deformation of the rotor core 33 when centrifugal force generated by rotation acts on the rotor core 33 in Embodiment 4.

[0070] exist Figure 8 In the middle, the distribution of the same-color lines is elliptical. Therefore, it can be seen that the rotor core 33 without a pair of second stress-relieving grooves 33h is deformed into an elliptical shape. On the other hand, in Figure 9 In the rotor core 33 of embodiment 4, the distribution of the same-color lines is nearly circular. This indicates that elliptical deformation is suppressed.

[0071] Furthermore, the number of key portions 33f, the number of first stress relief grooves 33g, the number of second stress relief grooves 33h, and the number of protrusions 33i are not necessarily limited to the examples described above. (Symbol Explanation)

[0072] 3. Rotor; 31. Rotor body; 31a. Magnetic pole; 32. Shaft; 33a. Keyway; 33. Rotor core; 33a. Shaft hole; 33f. Key; 33g. First stress relief groove; 33h. Second stress relief groove; 33i. Protrusion; 34. Permanent magnet.

Claims

1. A rotor of a rotary electric machine characterized by comprising: include: The rotor body has a cylindrical rotor core and multiple permanent magnets. The cylindrical rotor core has a central shaft hole. The multiple permanent magnets are fixed to the rotor core. The rotor body has multiple magnetic poles spaced apart from each other in the circumferential direction of the rotor core. A shaft is inserted into the shaft hole and fixed to the rotor core. A keyway is provided on the outer circumference of the shaft. The inner circumference of the rotor core is provided with a key, a first stress-relieving groove, a second stress-relieving groove, and a protrusion. The key portion fits into the keyway. The first stress-relieving groove is disposed near the key portion in the circumferential direction of the rotor core. The bottom surface of the first stress relief groove in the cross section perpendicular to the axial direction of the rotor core is composed of one or more first arcs, including a first maximum arc which is the arc with the largest radius. The bottom surface of the second stress relief groove in the cross-section perpendicular to the axial direction of the rotor core is composed of one or more second arcs, including a second maximum arc which is the arc with the largest radius. The protrusion is disposed between the first stress-relieving groove and the second stress-relieving groove, and is in contact with the outer periphery of the shaft. In a cross section perpendicular to the axial direction of the rotor core, the protrusion is positioned between two adjacent d-axis.

2. The rotor of the rotary electric motor as described in claim 1, characterized in that, When observing a cross-section perpendicular to the axial direction of the rotor core, The center of the circle along the second maximum arc is located at a position offset by 90° from the center of the key in the circumferential direction of the rotor core.

3. The rotor of the rotary electric motor as described in claim 1, characterized in that, When observing a cross-section perpendicular to the axial direction of the rotor core, The center of the protrusion is located on a straight line that bisects the angle between the key line and the second groove line. The key line is a straight line that passes through the center of the rotor core and the center of the key. The second slot line is a straight line that passes through the center of the rotor core and the center of the circle along the second maximum circular arc.

4. The rotor of the rotary electric motor as described in claim 2, characterized in that, When observing a cross-section perpendicular to the axial direction of the rotor core, The center of the protrusion is located on a straight line that bisects the angle between the key line and the second groove line. The key line is a straight line that passes through the center of the rotor core and the center of the key. The second slot line is a straight line that passes through the center of the rotor core and the center of the circle along the second maximum circular arc.

5. The rotor of the rotating electric motor as described in any one of claims 1 to 4, characterized in that, When observing a cross-section perpendicular to the axial direction of the rotor core, If we define the maximum distance between the bottom surface of the first stress-relieving groove in the radial direction of the rotor core and the outer periphery of the shaft as d1, and the maximum distance between the bottom surface of the second stress-relieving groove in the radial direction of the rotor core and the outer periphery of the shaft as d2, and define the radius of the circle along the first maximum arc as R1, and the radius of the circle along the second maximum arc as R2, then... Then d2 ≤ 3 × d1 × (R2 / R1) is satisfied.

6. A rotary electric motor, characterized in that, The rotor includes any one of claims 1 to 5.

Images