Motor, machine tool

Abstract

The present invention provides a motor and a machine tool. The motor includes a stator core and a rotor core. The stator core has a central hole, and the rotor core is installed in the central hole. The hole wall of the central hole has a plurality of first inclined notch segments formed by a plurality of notches and extending obliquely along the axial direction of the stator core. A plurality of permanent magnets are provided on the outer peripheral wall of the rotor core, and the plurality of permanent magnets are arranged obliquely along the axial direction of the rotor core to form a first inclined pole segment. The inclined extension direction of the first inclined notch segment is not parallel to the inclined arrangement direction of the first inclined pole segment. According to the present invention, the inclined extension direction of the first inclined notch segment on the stator core and the inclined arrangement direction of the first inclined pole segment on the rotor core form a spatial intersection, which can make the inclination angles of the inclined notch and the inclined pole relatively small. Therefore, while effectively reducing the cogging torque and reducing the torque ripple, a large motor torque output can be ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor manufacturing, and particularly relates to a motor and a machine tool. Background Art

[0002] A traditional surface-mounted permanent magnet synchronous motor mainly consists of a stator core, windings, permanent magnets, a rotor core, and a rotating shaft. When the motor windings are not energized and the rotor rotates relative to the stator, due to the presence of slot openings, the air-gap permeance of the motor is unevenly distributed in the circumferential direction, causing changes in magnetic field energy storage. The tangential component of the interaction force between the permanent magnet and the iron core fluctuates, thereby generating cogging torque.

[0003] Cogging torque is one of the unique problems of permanent magnet motors. When the motor rotates, the amplitude of the cogging torque changes periodically, and its average value over one cycle is zero. The existence of cogging torque has a certain impact on the control accuracy of the motor.

[0004] To reduce cogging torque, traditional motors generally adopt the method of skewing slots or poles. For a stator with a small number of slots, when using the skewing slots method, the skewing angle is relatively large, which makes production and manufacturing difficult, increases the copper consumption, increases the copper loss, resulting in increased costs and elevated motor temperature rise, and reduced efficiency. Similarly, for a motor with a small number of stator slots, when using skewed poles, a relatively large skewing angle is required, which can play a positive role in weakening the cogging torque. However, with the same amount of permanent magnet material, the output torque will be significantly reduced, and this disadvantage needs to be compensated by technical means. For example, to achieve a better effect in weakening cogging torque by using only skewed slots or poles, it is necessary to skew by one slot pitch angle. For example, for a 12-slot motor, the slots or poles need to be skewed by 30 degrees, and for a 36-slot motor, the slots or poles need to be skewed by 10 degrees; the larger the skewed pole angle, the lower the effective utilization rate of magnetic field energy and the lower the effective utilization rate of copper. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to provide a motor and a machine tool, in which the inclined extension direction of the first skewed slot section on the stator core forms a spatial intersection with the inclined setting direction of the first skewed pole section on the rotor core, so that the inclined angles of the skewed slot and the skewed pole can be relatively small, thereby effectively reducing the cogging torque and torque ripple while ensuring a large motor torque output.

[0006] To solve the above problems, the present invention provides a motor, including a stator core and a rotor core. The stator core has a central hole, and the rotor core is installed in the central hole. The hole wall of the central hole has a plurality of first inclined notch segments formed by a plurality of notches and extending obliquely along the axial direction of the stator core. A plurality of permanent magnets are provided on the outer peripheral wall of the rotor core, and the plurality of permanent magnets are arranged obliquely along the axial direction of the rotor core to form a first inclined pole segment. The inclined extension direction of the first inclined notch segment is not parallel to the inclined arrangement direction of the first inclined pole segment.

[0007] In some embodiments, define the radial plane where the first end face of the stator core is located as the first plane, and the radial plane where the second end face of the stator core is located as the second plane. Project from the second plane onto the first plane. A point on any notch on the second plane is projected onto the first plane as point A, and the corresponding point on the first plane to the point on the any notch is point A'. The central angle θ of point A and point A' with respect to the axis of the central hole is the inclination angle of the notch. Define the radial plane where the first end face of the rotor core is located as the third plane, and the radial plane where the second end face of the rotor core is located as the fourth plane. Project from the fourth plane onto the third plane. A point on any permanent magnet on the fourth plane is projected onto the third plane as point B, and the corresponding point on the third plane to the point on the any permanent magnet is point B'. The central angle α of point B and point B' with respect to the axis of the central hole is the inclination angle of the permanent magnet, and α = kθ, where k is a natural number and 1 ≤ k ≤ 5.

[0008] In some embodiments, the stator core is formed by assembling multiple core segments enclosing each other. The core segments are formed by a plurality of core laminations stacked along the axial direction of the stator core. The core lamination has a yoke portion and a tooth portion on the side of the yoke portion close to the central hole. A boot portion is provided at the free end of the tooth portion. When projected onto the first plane, the maximum radial thickness of the boot portion is H, and the radial thickness of the notch is G, and 3.9 ≤ H / G ≤ 4.1.

[0009] In some embodiments, the boot portion has a boot cantilever extending along the circumferential direction of the stator core. The side of the boot cantilever facing away from the rotor core has an inclined surface, and the inclined surface is inclined from the free end of the boot cantilever towards the tooth portion side. On the first plane, the connection line between the center point of the notch corresponding to the boot cantilever and the axis of the central hole is the first connection line, and the angle between the inclined surface and the first connection line is β, and 65° ≤ β ≤ 70°.

[0010] In some embodiments, in the axial direction of the rotor core, the yoke portions and tooth portions of the plurality of core laminations have the same dimensions, and the boot portions have different dimensions.

[0011] In some embodiments, θ = 6° and α = 6°.

[0012] In some embodiments, a second inclined notch section is further provided on the hole wall of the central hole. The second inclined notch section communicates with the first inclined notch section, and the inclined extension direction of the second inclined notch section is opposite to that of the first inclined notch section.

[0013] In some embodiments, a third inclined notch section is further provided on the hole wall of the central hole. The third inclined notch section communicates with the second inclined notch section, and the inclined extension direction of the third inclined notch section is parallel to that of the first inclined notch section.

[0014] The present invention also provides a machine tool, including the motor as described above.

[0015] For the motor and the machine tool provided by the present invention, the inclined extension direction of the first inclined notch section on the stator core forms a spatial intersection with the inclined setting direction of the first inclined pole section on the rotor core, which can make the inclination angles of the inclined notch and the inclined pole relatively small. Therefore, while effectively reducing the cogging torque and reducing the torque ripple, it can also ensure a large motor torque output. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram (axial projection) of the stator core in a motor according to an embodiment of the present invention;

[0017] Figure 2 is Figure 1 a schematic structural diagram of the iron core punching sheet of the second end face in the iron core split of the stator core in

[0018] Figure 3 is Figure 1 a schematic structural diagram of the iron core punching sheet of the first end face in the iron core split of the stator core in

[0019] Figure 4 is a schematic structural diagram (three - dimensional, including magnetic steel) of the rotor core in a motor according to an embodiment of the present invention;

[0020] Figure 5 is a schematic structural diagram (axial projection, including magnetic steel) of the rotor core in a motor according to an embodiment of the present invention;

[0021] Figure 6 is a schematic diagram of the spatial intersection of the first inclined notch section and the magnetic steel inclined pole in a motor according to an embodiment of the present invention;

[0022] Figure 7 is Figure 1 a schematic three - dimensional structural diagram of the iron core split of the stator core in

[0023] Figure 8 It is a three - dimensional structural schematic diagram of the split iron core of the stator core of the motor according to another embodiment of the present invention, which is matched with the stator core having a first slotted notch section and a second slotted notch section;

[0024] Figure 9 It is a three - dimensional structural schematic diagram of the split iron core of the stator core of the motor according to still another embodiment of the present invention, which is matched with the stator core having a first slotted notch section, a second slotted notch section, and a third slotted notch section;

[0025] Figure 10 It is a comparison diagram of the effects of separately adopting the slotted notch or skewed pole structure in the related art and the combined method of the slotted notch and skewed pole of the present invention in reducing cogging torque;

[0026] Figure 11 It is a comparison diagram of the effects of separately adopting the slotted notch or skewed pole structure in the related art and the combined method of the slotted notch and skewed pole of the present invention in reducing torque ripple;

[0027] Figure 12 It is a correlation curve diagram of H / G and cogging torque;

[0028] Figure 13 It is a correlation curve diagram of β and cogging torque.

[0029] The reference signs are shown as:

[0030] 1, stator core; 11, central hole; 12, slot opening; 13, iron core punching sheet; 131, yoke part; 132, tooth part; 133, boot part; 1331, boot cantilever; 14, first slotted notch section; 2, rotor core; 21, permanent magnet. Specific embodiments

[0031] Refer to in combination Figures 1 to 13As shown, according to an embodiment of the present invention, a motor is provided, including a motor stator having a stator core 1 and a motor rotor having a rotor core 2. The stator core 1 has a central hole 11, and the rotor core 2 is installed in the central hole 11. The hole wall of the central hole 11 has a plurality of first inclined notch segments 14 formed by a plurality of notches 12 and extending obliquely along the axial direction of the stator core 1. A plurality of permanent magnets 21 are provided on the outer peripheral wall of the rotor core 2, and the plurality of permanent magnets 21 are arranged obliquely along the axial direction of the rotor core 2 to form a first inclined pole segment (in terms of the specific implementation of the inclined pole, for example, it can be achieved by performing inclined pole magnetization on an integral magnetic ring. Objectively, it can also be considered to be formed by the inclined poles of a plurality of permanent magnets 21). The inclined extension direction of the first inclined notch segment 14 is not parallel to the inclined setting direction of the first inclined pole segment, that is, the inclined extension direction of the first inclined notch segment 14 and the inclined setting direction of the first inclined pole segment form a cross in space. In this technical solution, the inclined extension direction of the first inclined notch segment 14 on the stator core 1 and the inclined setting direction of the first inclined pole segment on the rotor core 2 form a spatial cross, which can make the inclined angles of the inclined notch and the inclined pole relatively small. Thus, while effectively reducing the cogging torque and reducing the torque ripple, it can also ensure a large motor torque output. That is, the present invention effectively avoids the contradictory requirements of a large inclined angle for reducing torque ripple and a small inclined angle for increasing output torque in the prior art when performing inclined notch or inclined pole design alone by performing inclined pole treatment on the rotor core 2 and inclined notch treatment on the stator core 1 at the same time.

[0032] In some embodiments, define the radial plane where the first end face of the stator core 1 is located as the first plane, and the radial plane where the second end face of the stator core 1 is located as the second plane. Project from the second plane onto the first plane. The projection of a point on any notch 12 on the second plane on the first plane is point A, and the corresponding point on the first plane to the point on any notch 12 is point A'. The central angle θ with respect to the axis of the central hole 11 between point A and point A' is the inclined angle of the notch 12. Define the radial plane where the first end face of the rotor core 2 is located as the third plane, and the radial plane where the second end face of the rotor core 2 is located as the fourth plane. Project from the fourth plane onto the third plane. The projection of a point on any permanent magnet 21 on the fourth plane on the third plane is point B, and the corresponding point on the third plane to the point on any permanent magnet 21 is B'. The central angle α with respect to the axis of the central hole 11 between point B and point B' is the inclined angle of the permanent magnet 21, and α = kθ, where k is a natural number and 1 ≤ k ≤ 5. This technical solution is particularly applicable to a 12-slot motor. When k > 5, the reduction of the cogging torque is not obvious, but the output torque decreases significantly.

[0033] In some embodiments, the stator core 1 is formed by assembling multiple core segments enclosing each other. Each core segment is formed by multiple core laminations 13 stacked along the axial direction of the stator core 1. The core lamination 13 has a yoke portion 131 and a tooth portion 132 on one side of the yoke portion 131 close to the central hole 11. A boot portion 133 is provided at the free end of the tooth portion 132. When projected onto the first plane, the maximum radial thickness of the boot portion 133 is H, and the radial thickness of the slot opening 12 is G, where 3.9 ≤ H / G ≤ 4.1. For details, refer to Figure 12 It can be seen that the cogging torque first decreases and then increases as H / G increases. In order to keep the cogging torque of the motor within a relatively small range, it is preferably 3.9 ≤ H / G ≤ 4.1.

[0034] In some embodiments, the boot portion 133 has a boot cantilever 1331 extending along the circumferential direction of the stator core 1. One side of the boot cantilever 1331 facing away from the rotor core 2 has an inclined surface, which is inclined from the free end of the boot cantilever 1331 towards the tooth portion 132. On the first plane, the connection line between the center point of the slot opening 12 corresponding to the boot cantilever 1331 (i.e., the projection point of the center line of the slot opening 12 on the first plane) and the axis of the central hole 11 is the first connection line, and the angle between the inclined surface and the first connection line is β, where 65° ≤ β ≤ 70°. For details, refer to Figure 13 It can be seen that as β increases, the cogging torque first decreases and then increases. In order to keep the cogging torque of the motor within a relatively small range, it is preferably 65° ≤ β ≤ 70°.

[0035] In some embodiments, in the axial direction of the rotor core 1, the dimensions of the yoke portions 131 and the tooth portions 132 of multiple core laminations 13 are the same, while the dimensions of the boot portions 133 are different. That is, in the same core segment, only the dimensions of the boot portions 133 of the core laminations 13 stacked along its axial direction are different. The formation of the first inclined slot section 14 is based on this difference in the dimensions of the boot portions 133. The same dimensions of the corresponding yoke portions 131 and tooth portions 132 can improve work efficiency and the processing and manufacturing of the laminations. It can be understood that in each core segment, the boot portions 133 of multiple core laminations stacked along its axial direction are angularly misaligned axially. For example, when there are N core laminations in total, the misalignment angle at the corresponding slot openings of the boot portions 133 of two adjacent core laminations axially is θ / N.

[0036] The motor rotor is composed of a shaft, a rotor core 2, and a permanent magnet 21, as shown in Figure 4As shown, after the rotor core 2 is heated and expanded, it is shrink-fitted onto the shaft. The permanent magnets 21 (forming a magnetic ring) are pasted onto the rotor core 2 with a strong adhesive glue. The magnetic ring is magnetized by the skewed pole magnetization method, that is, each magnetic pole of the magnetic ring is inclined at a certain angle in the axial direction of the motor, and each magnetic pole of the magnetic ring is evenly distributed alternately as N and S.

[0037] In some embodiments, θ = 6° and α = 6°, that is, a combination of a skewed pole angle of 6° and a skewed slot opening angle of 6° is adopted. For the corresponding technical effects after the combination, reference can be made to Figure 10 , Figure 11 . It can be seen that the motor adopting the combination can significantly reduce the cogging torque and torque ripple.

[0038] In some embodiments, the hole wall of the central hole 11 further has a second skewed slot opening section, which communicates with the first skewed slot opening section 14, and the inclined extension direction of the second skewed slot opening section is opposite to that of the first skewed slot opening section 14, forming a V-shaped skewed slot opening structure in appearance. In some embodiments, the hole wall of the central hole 11 further has a third skewed slot opening section, which communicates with the second skewed slot opening section, and the inclined extension direction of the third skewed slot opening section is parallel to that of the first skewed slot opening section 14, forming an S-shaped skewed slot opening structure in appearance. From the perspective of actual production, the combination of V-shaped (i.e., V-shaped) and S-shaped (i.e., S-shaped) with skewed poles has a better effect on weakening the cogging torque than the straight-shaped one, but the disadvantage is that the processing is more complex.

[0039] According to an embodiment of the present invention, there is also provided a machine tool, including the motor as described above.

[0040] It is easy for those skilled in the art to understand that, on the premise of no conflict, the above-mentioned advantageous ways can be freely combined and superimposed.

[0041] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. The above is only the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, several improvements and variations can be made without departing from the technical principle of the present invention, and these improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A motor, characterized in that, it includes a stator core (1) and a rotor core (2). The stator core (1) has a central hole (11), and the rotor core (2) is installed in the central hole (11). On the hole wall of the central hole (11), there are a plurality of first inclined notch segments (14) formed by a plurality of notches (12) and extending obliquely along the axial direction of the stator core (1). On the outer peripheral wall of the rotor core (2), there are a plurality of permanent magnets (21). The plurality of permanent magnets (21) are arranged obliquely along the axial direction of the rotor core (2) to form a first inclined pole segment. The inclined extension direction of the first inclined notch segment (14) is not parallel to the inclined setting direction of the first inclined pole segment; define the radial plane where the first end face of the stator core (1) is located as the first plane, and the radial plane where the second end face of the stator core (1) is located as the second plane. Project from the second plane onto the first plane. A point on any notch (12) on the second plane is projected onto the first plane as point A, and the corresponding point on the first plane to the point on the any notch (12) is point A'. The central angle θ of point A and point A' relative to the axis of the central hole (11) is the inclination angle of the notch (12); define the radial plane where the first end face of the rotor core (2) is located as the third plane, and the radial plane where the second end face of the rotor core (2) is located as the fourth plane. Project from the fourth plane onto the third plane. A point on any permanent magnet (21) on the fourth plane is projected onto the third plane as point B, and the corresponding point on the third plane to the point on the any permanent magnet (21) is point B'. The central angle α of point B and point B' relative to the axis of the central hole (11) is the inclination angle of the permanent magnet (21), and α = kθ, where k is a natural number and 1 ≤ k ≤ 5.

2. The motor according to claim 1, characterized in that, the stator core (1) is formed by assembling and enclosing multiple core parts. The core parts are formed by a plurality of core laminations (13) stacked along the axial direction of the stator core (1). The core lamination (13) has a yoke portion (131) and a tooth portion (132) on the side of the yoke portion (131) close to the central hole (11). A boot portion (133) is provided at the free end of the tooth portion (132). When projected onto the first plane, the maximum radial thickness of the boot portion (133) is H, and the radial thickness of the notch (12) is G, and 3.9 ≤ H / G ≤ 4.

1.

3. The motor according to claim 2, characterized in that, The boot portion (133) has a boot cantilever (1331) extending along the circumferential direction of the stator core (1). One side of the boot cantilever (1331) facing away from the rotor core (2) has an inclined surface, and the inclined surface is inclined from the free end of the boot cantilever (1331) towards the tooth portion (132). On the first plane, the connecting line between the center point of the notch (12) corresponding to the boot cantilever (1331) and the axis of the central hole (11) is the first connecting line, and the included angle between the inclined surface and the first connecting line is β, where 65° ≤ β ≤ 70°.

4. The electric machine according to claim 2, characterized in that in the axial direction of the stator core (1), the yoke portions (131) and the tooth portions (132) of the plurality of core laminations (13) have the same dimensions, and the boot portions (133) have different dimensions.

5. The electric machine according to claim 1, characterized in that θ = 6° and α = 6°.

6. The electric machine according to claim 1, characterized in that the hole wall of the central hole (11) further has a second inclined notch section, the second inclined notch section communicates with the first inclined notch section (14), and the inclined extension direction of the second inclined notch section is opposite to that of the first inclined notch section (14).

7. The electric machine according to claim 6, characterized in that the hole wall of the central hole (11) further has a third inclined notch section, the third inclined notch section communicates with the second inclined notch section, and the inclined extension direction of the third inclined notch section is parallel to that of the first inclined notch section (14).

8. A machine tool, characterized in that it includes the electric machine according to any one of claims 1 to 7.

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