Frameless torque parallel tooth stator core and rotor structure

Abstract

This invention discloses a frameless torque parallel-tooth stator core and rotor structure, relating to the field of motor technology. The stator core includes a stator core, a rotor ring, and magnets. The stator core comprises an annular stator yoke and stator teeth extending radially inward from the yoke, with stator slots formed between adjacent teeth to accommodate windings. The rotor ring is coaxially disposed on the inner side of the stator core. This frameless torque parallel-tooth stator core and rotor structure simplifies the assembly process and reduces costs through the parallel-tooth stator structure. The tooth width of the stator teeth remains constant in the radial extension direction, resulting in a simple rectangular straight cutting edge for the lamination die. This leads to uniform shear force distribution during stamping, reduces die processing steps, extends die life, and makes it easier to ensure alignment accuracy during lamination stacking, reducing magnetic circuit unevenness caused by stacking misalignment.

Description

Technical Field

[0001] This invention relates to the field of motor technology, specifically to a frameless torque parallel tooth stator core and rotor structure. Background Technology

[0002] The frameless torque motor features a parallel tooth stator core and rotor structure. The stator is made of silicon steel sheets stacked into a ring, with teeth evenly distributed at equal angles. The slots are straight, suitable for concentrated windings, and have high slot fill factor and low copper loss.

[0003] For example, Chinese Patent Publication No. CN115765234A discloses a stator assembly and a motor. In each phase winding branch of the stator assembly, the first coil group is wound gradually across layers in a first direction with a span y to the Mth slot layer; it is wound in the same layer with a span y1 = y+1 or y1 = y-1 to the Mth slot layer corresponding to the adjacent magnetic pole; it is wound gradually across layers in a second direction with a span y to the 1st slot layer; and it is wound in the same layer with a span y2 = 2y - y1 to... The first slot layer corresponds to adjacent magnetic poles; the connecting wires in the same layer connect the first coil group and the second coil group with a span y3; the second coil group enters from the first slot layer and is wound alternately in the circumference of the stator core along the first direction with a span y for one revolution in the adjacent two slot layers; then it is moved to the next group of adjacent two slot layers and wound in the circumference of the stator core along the first direction with a span y; this winding pattern is continued until the winding of the M / 2 groups of adjacent two slot layers to the Mth slot layer is completed. In the stator assembly of this application embodiment, the insulating paper in the same stator slot is eliminated.

[0004] For example, Chinese patent CN121566803A discloses a method for manufacturing a frameless torque motor stator core. The stator core includes a stator yoke, stator teeth, and stator coils. The stator yoke is annular, and the stator teeth have a sun tooth structure. The stator teeth include annular rings, tooth shoes, and tooth bodies. The stator teeth are fitted inside the stator yoke, and multiple tooth bodies are evenly distributed. The surfaces of the stator yoke and stator teeth are coated with a high-temperature resistant insulating film. The stator coils are fitted onto the tooth bodies. The manufacturing method includes the following steps: S100, making the stator yoke and stator teeth and performing a coating treatment; S200, winding and forming the stator coil; S300, assembling the stator core; S400, welding the wire feet; S500, potting and drying; S600, boring and shaping: boring the inner side of the annular part and the cured potting adhesive, boring away the annular part to completely isolate the two adjacent tooth shoe parts, thereby boring the closed slot of the stator core into an open slot; S700, performance testing.

[0005] Most of the existing technologies mentioned above improve the overall structure. However, the existing frameless torque motor parallel slot trapezoidal tooth structure results in complex assembly processes and high costs. The right-angle structure at the bottom of the stator slot causes stress concentration and local magnetic saturation. The right-angle intersection is a high-incidence area of ​​stress concentration, which is prone to micro-cracks under stamping and running vibration. At the same time, magnetic flux will be locally concentrated at the right angle, leading to magnetic saturation, increasing iron loss and reducing motor efficiency. Summary of the Invention

[0006] The purpose of this invention is to provide a frameless torque motor with parallel tooth stator core and rotor structure, in order to solve the problems of complex assembly process and high cost caused by the existing frameless torque motor with parallel slot trapezoidal tooth structure, stress concentration and local magnetic saturation caused by the right angle structure at the bottom of the stator slot, the right angle junction is a high-incidence area of ​​stress concentration, and microcracks are easily generated under stamping and running vibration. At the same time, magnetic flux will be locally concentrated at the right angle, resulting in magnetic saturation, increasing iron loss and reducing motor efficiency.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a frameless torque parallel tooth stator core and rotor structure, comprising a stator core, a rotor steel ring, and magnets; The stator core includes an annular stator yoke and stator teeth extending radially inward from the stator yoke. A stator slot for accommodating windings is formed between two adjacent stator teeth. The rotor ring is coaxially disposed on the inner side of the stator core, and a plurality of magnets are uniformly attached to the outer circumferential surface of the rotor ring. The stator teeth have a parallel tooth structure, that is, the tooth width of a single stator tooth remains constant along its radial extension path. The sidewalls of the stator teeth intersect perpendicularly with the bottom surface of the stator slots, forming a right-angle intersection. The stator slots are symmetrically provided with bottom fillets near the bottom corners of the right-angle intersections, and the bottom fillets smoothly connect the sidewalls of the stator teeth and the bottom surface of the stator slots.

[0008] Furthermore, the stator outer diameter is defined as... The stator inner diameter is The outer diameter of the rotor is The inner diameter of the rotor is The stator tooth width is The minimum value of the stator slot width is The maximum value of the stator slot width is The minimum distance from the bottom of the stator slot to the outer circle of the stator is The maximum distance from the bottom of the stator slot to the outer circle of the stator is The maximum thickness of the magnet is The minimum thickness of the magnet is The air gap of the motor is The parameters satisfy the following relationship .

[0009] Furthermore, the diameter of the fillet at the bottom of the groove is defined as... It satisfies the following relationship: .

[0010] Furthermore, the ends of the stator teeth do not have crown structures extending into the stator slots, so that the stator slots form straight opening slots in the radial direction.

[0011] Furthermore, the bottom surface of the stator slot is an arc surface, and the center of the arc surface is located on the radial center line of the stator slot.

[0012] Furthermore, the magnet is a tile-shaped permanent magnet, and multiple magnets can be uniformly attached along the outer or inner circumferential surface of the rotor steel ring.

[0013] Furthermore, both the right-angle junction and the fillet at the bottom of the slot are symmetrically arranged about the radial center line of the stator slot.

[0014] Furthermore, the windings housed in the stator slots adopt a flat wire structure.

[0015] Furthermore, a circumferential gap is left between two adjacent magnets, and the circumferential gap is used to adjust the magnetic leakage coefficient of the motor.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This frameless torque parallel tooth stator core and rotor structure simplifies the assembly process and reduces costs through the parallel tooth stator structure. The tooth width of the stator teeth remains constant in the radial extension direction, so that the tooth cutting edge of the lamination die is a simple rectangular straight cutting edge. The shearing force is evenly distributed during the stamping process, the die processing steps are reduced, the service life is extended, and the alignment accuracy during lamination stacking is easier to ensure, reducing the problem of uneven magnetic circuit caused by stacking misalignment.

[0017] The rounded corners at the bottom of the slot achieve the dual effects of stress buffering and magnetic circuit optimization. They smoothly transition the right-angle intersection formed by the side wall of the stator teeth and the bottom surface of the stator slot, effectively dispersing the concentrated stress generated by stamping and electromagnetic vibration during motor operation, reducing the risk of microcracks in the stator core, and optimizing the direction of magnetic flux from the stator teeth into the stator yoke, reducing the phenomenon of local magnetic flux concentration, and reducing motor iron loss.

[0018] The synergistic design of straight slots and flat wire windings significantly improves motor performance. The straight slot structure with no tooth crown at the stator tooth end allows the flat wire windings to be directly inserted into the stator slots radially, improving winding efficiency and adapting to automated winding equipment. Furthermore, the slot fill factor of the flat wire windings is higher than that of traditional round wire windings, thereby reducing copper losses, increasing the power density of the motor, and improving operating efficiency.

[0019] The combination of unequal thickness magnets and circumferential gap effectively suppresses torque pulsation. The magnets adopt a tile-shaped structure that is thick in the middle and thin at both sides, so that the air gap magnetic permeability is approximately sinusoidally distributed along the circumference, reducing the harmonic content. The circumferential gap between adjacent magnets can flexibly adjust the magnetic leakage coefficient, further weakening higher harmonics, reducing torque pulsation, and reducing motor vibration and noise.

[0020] The structure has good versatility, and the core components can be adapted to both inner and outer rotor structures. There is no need to redevelop molds, which shortens the product development cycle for different application scenarios and reduces R&D and production costs. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the overall 2D structure of the present invention; Figure 3 This is a schematic diagram of the overall 3D structure of the present invention; Figure 4 This is a schematic diagram of the stator core structure of the present invention; Figure 5 This is a schematic diagram of a partial structure of the stator core of the present invention; Figure 6 This is a schematic diagram of a partial structure of the bottom arc of the stator core slot of the present invention; Figure 7 This is a schematic diagram of the magnet structure of the present invention; Figure 8 This is a schematic diagram of the rotor steel ring structure of the present invention; Figure 9 This is a schematic diagram of the overall rotor structure of the present invention; Figure 10 This is a graph showing the effect of the line current on the power density in this invention. Figure 11 This is a graph showing the effect of the line current on the efficiency of this invention.

[0022] In the diagram: 1. Stator core; 2. Rotor ring; 3. Magnet; 4. Stator yoke; 5. Stator teeth; 6. Stator slot; 7. Right-angle junction; 8. Slot bottom fillet. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1: Please refer to Figures 1 to 6 , Figure 8 and Figure 9 The present invention provides the following technical solution: The frameless torque parallel tooth stator core and rotor structure includes a stator core 1, a rotor steel ring 2, a magnet 3, a stator yoke 4, stator teeth 5, a stator slot 6, a right-angle intersection 7, and a slot bottom fillet 8.

[0025] During the manufacturing stage, the stator core 1 is made of multiple silicon steel laminations stacked together. During the lamination stamping process, since the stator teeth 5 adopt a parallel tooth structure, the tooth width remains constant throughout the radial direction. The cutting edge of the stamping die is a simple rectangular straight cutting edge. The punch moves in a reciprocating linear motion in a direction perpendicular to the lamination plane. When the cutting edge contacts the silicon steel sheet material, it generates a uniformly distributed shearing force to remove excess material from the stator slot 6 area.

[0026] Compared to the beveled cutting edge molds required for traditional trapezoidal teeth, this straight-edge mold requires fewer processing steps and exhibits more uniform wear of the cutting edge during stamping, which helps extend the mold's lifespan and reduce manufacturing costs. During lamination stacking, multiple processed laminations are sequentially stacked and aligned along the motor axis, and fixed into a single stator core 1 using riveting or welding. During stacking, the regularity of the parallel tooth structure makes it easier to ensure the alignment accuracy between laminations, reducing the problem of uneven magnetic circuit caused by stacking misalignment.

[0027] During the winding insertion stage, since the stator teeth 5 do not have a crown structure extending into the stator slot 6, the stator slot 6 forms a straight-open slot. The flat wire winding can be directly inserted from the slot opening along the radial direction of the stator slot 6 and then pushed axially to the bottom of the slot. Compared with closed or semi-closed slots with crowns, this straight-open slot structure avoids the complex action of the winding needing to bypass the crown, simplifies the mechanical movement process of winding, and can adapt to the high-speed operation of automated winding equipment. After winding is completed, the winding is fixed in the stator slot 6, and the stator teeth 5, as magnetic conductors, provide a closed magnetic circuit for the magnetic field generated by the winding.

[0028] When the motor is powered on, three-phase alternating current is supplied to the windings in the stator slots 6. The current flows along the motor axis in the windings. According to Ampere's circuital law, an alternating magnetic field distributed circumferentially is generated in the stator teeth 5 and the stator yoke 4. This magnetic field passes through the air gap between the stator and the rotor and interacts with the permanent magnet magnetic field generated by the magnets 3 attached to the outer circumference of the rotor steel ring 2. A tangential electromagnetic force is generated on the magnets 3. This electromagnetic force is transmitted to the rotor steel ring 2 through the adhesive force between the magnets 3 and the rotor steel ring 2, driving the rotor steel ring 2 to rotate around the motor axis, thereby driving the load connected to the rotor steel ring 2 to rotate.

[0029] During the magnetic field transmission process, the fillet 8 at the bottom of the stator slot 6 optimizes the magnetic circuit direction, allowing the magnetic flux to smoothly transition from the stator tooth 5 into the stator yoke 4. This reduces the local concentration of magnetic flux at the right-angle junction 7, helping to reduce the risk of local magnetic saturation and thus reducing the iron loss of the motor. At the same time, during motor operation, the electromagnetic force generates periodic mechanical stress inside the stator core 1. The fillet 8 at the bottom of the slot, through a smooth curved transition, can disperse the stress originally concentrated at the right-angle junction 7, reducing the possibility of microcracks in the stator core 1 under long-term vibration and improving the reliability of the structure.

[0030] Example 2: Please refer to Figures 1 to 6 and Figure 8 Based on Embodiment 1, the present invention provides the following technical solution: Magnets 3 are attached to the inner circumferential surface of the rotor steel ring 2 to form an external rotor frameless torque motor structure. All core components are interchangeable with those in Embodiment 1. During the manufacturing stage, the lamination stamping and stacking processes of the stator core 1 are completely consistent with those in Embodiment 1. The process advantages brought by the parallel tooth structure are also applicable. Only the extension direction of the stator teeth 5 needs to be adjusted to be radially outward. At this time, the slot width of the stator slot 6 gradually increases radially outward, forming a trapezoidal slot structure that is narrow on the inside and wide on the outside. The rotor steel ring 2 is coaxially sleeved on the outside of the stator core 1. Multiple magnets 3 are evenly attached to the inner circumferential surface of the rotor steel ring 2. A circumferential gap is also left between adjacent magnets 3 to adjust the magnetic leakage coefficient.

[0031] During operation, the rotating magnetic field generated by the three-phase current flowing into the stator windings passes through the air gap and interacts with the magnets 3 on the inner circumference of the rotor steel ring 2. The resulting tangential electromagnetic force acts on the magnets 3, thereby driving the rotor steel ring 2 to rotate around the axis of the stator core 1. Due to the larger moment of inertia of the outer rotor structure, this structure is more suitable for applications requiring low speed, high torque, and smooth operation.

[0032] In terms of magnetic circuit and stress distribution, the function of the slot bottom fillet 8 is the same as in Embodiment 1. It can effectively optimize the magnetic circuit at the junction of stator tooth 5 and stator yoke 4, disperse mechanical stress, and avoid local magnetic saturation and stress concentration problems. The straight slot structure also facilitates the placement of flat wire windings, ensuring production efficiency and winding slot fill factor.

[0033] Example 3: Please refer to Figure 1 , Figure 4 , Figure 5 , Figure 10 and Figure 11 The present invention provides the following technical solution: During the winding manufacturing stage, the flat wire conductor is pre-bent into a coil shape that matches a single stator tooth 5. Since the stator slot 6 is a straight-opening slot, each coil can be directly fitted radially onto the corresponding stator tooth 5 and then pushed axially into the stator slot 6. This centralized winding insertion process eliminates the need for cross-slot wiring, simplifies mechanical movement, increases automation, and significantly shortens the production cycle.

[0034] During operation, the shorter end length of the concentrated winding helps reduce copper losses. Simultaneously, the rectangular cross-section of the flat wire winding allows for a tighter filling of the stator slots 6, increasing slot fill factor. This allows for a larger cross-sectional area conductor within the same stator volume, enabling the passage of larger currents, generating a stronger magnetic field, and improving the motor's torque density. During magnetic field transmission, the parallel tooth structure of the stator teeth 5 provides a uniform magnetic cross-section, resulting in a more even distribution of the magnetic field across the teeth. Combined with the optimization of the magnetic circuit by the slot bottom fillet 8, this further reduces iron losses and improves the motor's operating efficiency.

[0035] Example 4: Please refer to Figure 2 , Figure 7 and Figure 9 The present invention provides the following technical solution: The unequal thickness tile-shaped magnet 3, which is thicker in the middle and thinner at both ends, is used in conjunction with the parallel tooth stator structure to optimize the air gap magnetic field waveform. The maximum thickness of the magnet 3 is located in the middle and the minimum thickness is located at both ends of its circumference. This structure makes the effective magnetic permeability of the air gap approximately sinusoidal along the circumference.

[0036] During operation, when the rotating magnetic field generated by the stator winding interacts with the magnet 3, the harmonic content of the air gap magnetic field will be significantly reduced, which helps to reduce the torque pulsation of the motor and make the rotation of the rotor steel ring 2 more stable.

[0037] The circumferential gap between adjacent magnets 3 can be adjusted according to actual needs. By changing the size of the gap, the magnetic leakage coefficient of the motor can be adjusted. Appropriate magnetic leakage can weaken the high-order harmonics in the air gap magnetic field, further improve the operating performance of the motor, and reduce vibration and noise. In terms of magnetic circuit, the uniform air gap magnetic field generated by the unequal thickness magnets matches the uniform magnetic conduction structure of the parallel tooth stator, which can make the magnetic flux distribution in the stator teeth 5 and stator yoke 4 more reasonable. Combined with the magnetic circuit optimization effect of the slot bottom fillet 8, it can avoid local magnetic saturation in a larger load range and expand the high-efficiency operating range of the motor.

[0038] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" or "linked" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral connection; it can refer to a mechanical connection or an electrical connection; it can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A frameless torque parallel tooth stator core and rotor structure, comprising a stator core (1), a rotor steel ring (2), and a magnet (3); characterized in that The stator core (1) includes an annular stator yoke (4) and stator teeth (5) extending radially inward from the stator yoke (4). A stator slot (6) for accommodating the winding is formed between two adjacent stator teeth (5). The rotor ring (2) is coaxially disposed on the inner side of the stator core (1). Multiple magnets (3) are uniformly attached to the outer circumferential surface of the rotor ring (2) along the circumference. The stator teeth (5) have a parallel tooth structure, that is, the tooth width of a single stator tooth (5) remains constant along its radial extension path. The sidewall of the stator teeth (5) intersects the bottom surface of the stator slot (6) perpendicularly to each other, forming a right-angle intersection (7). The stator slot (6) is symmetrically provided with a slot bottom fillet (8) at the bottom corner near the right-angle intersection (7). The slot bottom fillet (8) smoothly connects the sidewall of the stator teeth (5) and the bottom surface of the stator slot (6).

2. A frameless torque parallel tooth stator core and rotor structure according to claim 1, characterized in that: Define the stator outer diameter as The stator inner diameter is The outer diameter of the rotor is The inner diameter of the rotor is The stator tooth width is The minimum value of the stator slot width is The maximum value of the stator slot width is The minimum distance from the bottom of the stator slot to the outer circle of the stator is The maximum distance from the bottom of the stator slot to the outer circle of the stator is The maximum thickness of the magnet is The minimum thickness of the magnet is The air gap of the motor is The parameters satisfy the following relationship D 1 - D i 1 - 2 * b j 1 * b j 2 + h 1 - h 2 * D i 2 - D 2 W s 2 - W s 1 * D 1 - D i 1 * g < b t 1 < D 1 - D i 1 - 2 * b j 1 * b j 2 + h 1 - h 2 * D i 2 - D 2 W s 2 - W s 1 * D 1 - D i 1 * 3 g .

3. A frameless torque parallel tooth stator core and rotor structure according to claim 2, characterized in that: The diameter of the fillet (8) at the bottom of the groove is defined as follows: It satisfies the following relationship: .

4. A frameless torque parallel tooth stator core and rotor structure according to claim 3, characterized in that: The stator teeth (5) do not have a crown structure extending into the stator slot (6) at their ends, so that the stator slot (6) forms a straight opening slot in the radial direction.

5. A frameless torque parallel tooth stator core and rotor structure according to claim 4, characterized in that: The bottom surface of the stator slot (6) is an arc surface, and the center of the arc surface is located on the radial center line of the stator slot (6).

6. A frameless torque parallel tooth stator core and rotor structure according to claim 5, characterized in that: The magnet (3) is a tile-shaped permanent magnet, and multiple magnets (3) can be uniformly attached along the outer or inner circumferential surface of the rotor steel ring (2).

7. A frameless torque parallel tooth stator core and rotor structure according to claim 6, characterized in that: The right-angle junction (7) and the bottom fillet (8) of the slot are both symmetrically arranged about the radial center line of the stator slot (6).

8. A frameless torque parallel tooth stator core and rotor structure according to claim 7, characterized in that: The windings housed in the stator slot (6) are of a flat wire structure.

9. A frameless torque parallel tooth stator core and rotor structure according to claim 8, characterized in that: A circumferential gap is left between two adjacent magnets (3), and the circumferential gap is used to adjust the magnetic leakage coefficient of the motor.

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