Multi-slot brushless hollow cup motor and linear joint module

Abstract

The application discloses a multi-slot pole brushless hollow cup motor and a linear joint module, wherein the multi-slot pole brushless hollow cup motor comprises a rotor, a rotor magnetic steel, a stator winding and a stator yoke portion arranged in sequence, the rotor magnetic steel is fixed to the outer circumferential surface of the rotor and rotates synchronously with the rotor, the stator winding is a solidified hollow cup winding, the coil is divided into three-phase windings, the coils of the same-phase winding are directly connected in series inside in the winding process of the stator winding, the connection is sequentially carried out across two coils when the coils are connected in series, only two terminal heads are led out for each-phase winding, and only six terminal heads are led out in total for the three-phase windings.

Description

Technical Field

[0001] This application relates to the field of hollow cup motor technology, and more specifically to a multi-slot brushless hollow cup motor and a linear joint module. Background Technology

[0002] Currently, brushless coreless motors offer advantages such as high efficiency, fast response, and stable operation, and are widely used in humanoid robots, medical devices, aerospace, and other fields. The motor mainly consists of a stator core, coreless windings, and a permanent magnet rotor. Currently, brushless coreless motors primarily have 2 poles on the rotor, and the coreless windings often use a 3-slot or 6-slot topology. These coreless motors are not suitable for large sizes, have relatively low output power, and can only be used in applications with low loads.

[0003] Related technologies also include hollow cup motors with multiple slots and poles, such as 12-slot 4-pole motors. However, the traditional hollow cup winding process for manufacturing such multi-slot pole motors is quite complex. A large amount of copper wire is only used for end connections and does not participate in electromagnetic energy conversion, resulting in winding copper loss accounting for more than 60% of the total motor loss. The motor generates severe heat during operation, significantly limiting continuous working time. At the same time, although the air gap magnetic flux density of the few-pole structure is high, the yoke is thicker, compressing the space between the winding and the magnet, making it difficult to meet the application requirements of high torque and high power density, and more suitable for applications with smaller loads. Summary of the Invention

[0004] The purpose of this application is to provide a multi-slot brushless coreless motor and a linear articulation module to reduce copper loss, improve efficiency, reduce motor heat generation, and enhance the practicality of the brushless coreless motor.

[0005] To achieve the above objectives, the technical solution adopted in this application is as follows: A multi-slot brushless hollow cup motor is provided, comprising: a rotor, rotor magnets, stator windings, and a stator yoke arranged sequentially. The rotor magnets are fixed to the outer circumference of the rotor and rotate synchronously with the rotor. The stator windings are solidified hollow cup windings, each consisting of multiple coils. These coils are divided into three-phase windings. During the winding process of the stator windings, the coils of each phase are directly internally connected in series, with the series connection spanning two coils sequentially. Each phase winding has only two terminals, resulting in a total of six terminals for the three-phase windings. The dimensional parameters of the multi-slot brushless hollow cup motor include the number of stator slots. With the number of motor poles The number of stator slots is equal to the number of coils. The number of pole pairs of the motor, and the number of stator slots is also specified. With the number of poles of the motor ratio The number of poles of the motor It is an even natural number greater than two; there is a numerical relationship between the thickness of the stator yoke and the thickness of the rotor magnet, that is, it must satisfy... ;in, and This is the magnetic circuit correction factor. The thickness of the rotor magnet is given. The thickness of the stator yoke is in millimeters. The magnetic flux density of the stator yoke is given. The remanence of the magnet is expressed in tons (T); it must also satisfy condition 3 > 1. >0.8, where, That is, the thickness value of the stator winding. This is the outer diameter value of the stator. The value represents the inner diameter of the rotor magnet, in millimeters.

[0006] Preferably, each coil is flattened after winding, and the coil includes two axially extending straight sides; and after flattening, the pitch of a single coil is... , ;in, This is the outer diameter value of the stator winding. This is the inner diameter value of the stator winding. This refers to the straight edge distance of a single winding coil after it has been unfolded, in millimeters. That is, the number of stator slots. and This refers to the coil pitch parameter value.

[0007] Preferably, the flattened coil has two oppositely arranged winding apex angles. The angle is twice the tilt angle at the winding end, and thus the tilt angle at the winding end... ;in This is the total axial length of the winding. The axial length of the straight side of the coil in the winding, in millimeters. For angle parameters.

[0008] Further optimization, the slot fill factor constraint is expressed as: ; in, Maximum wire diameter with enamel coating, in millimeters. The number of turns in a single coil. For the number of roots, and This is the slot fill factor.

[0009] In a further preferred embodiment, the inner diameter of the stator yoke and the outer diameter of the stator winding are provided with an insulating tape gap on one side.

[0010] Further preferably, the rotor magnet is arranged in a tile-like or ring-like structure.

[0011] Preferably, each coil of the stator winding is wound with a full pitch, and its pitch is... It equals 3.

[0012] Preferably, along the axial direction of the multi-slot brushless hollow cup motor, one end face of the stator winding is flush with the corresponding end face of the stator yoke, and the other end face of the stator winding is axially offset relative to the other corresponding end face of the stator yoke.

[0013] As a preferred embodiment, in a single coil after flattening, a straight edge extending axially is used to connect the oppositely arranged winding apex angles, the winding apex angles including a first apex angle and a second apex angle; wherein, the axial distance between the first apex angle and the second apex angle is the total axial length of the stator winding, and the axial length of the stator yoke is greater than or equal to the axial length of the straight edge and less than or equal to the total axial length of the stator winding.

[0014] As another preferred option, this application also provides a linear joint module, which is suitable for use within a robot structure, and the linear joint module includes the multi-slot brushless hollow cup motor described in any of the above-mentioned claims.

[0015] Compared with the prior art, the beneficial effects of this application are as follows: By establishing a systematic parameter coordination constraint system, the core problems of existing multi-slot hollow cup motors—lack of scientific design basis and high degree of blind parameter matching—are effectively solved. By pre-setting the magnetic circuit matching relationship between the thickness of the stator yoke and the thickness of the rotor magnets, precise matching between the magnetizing capacity of the rotor magnets and the magnetic flux carrying capacity of the stator yoke can be achieved. This avoids both low air gap magnetic flux density caused by insufficient magnetizing capacity of the magnets and increased iron loss and worsened temperature rise caused by magnetic saturation of the stator yoke. On this basis, through the synergistic effect of winding pitch constraints and slot fill factor constraints, the geometry and spatial distribution of the windings can be optimized, reducing the amount of ineffective copper wire at the winding ends, effectively reducing winding copper loss, while also taking into account the feasibility of the winding manufacturing process.

[0016] In this type of motor, the coils of the same phase winding are directly connected in series internally during the winding process of the stator winding. No additional intermediate taps are required during the winding process. Each phase winding only has two terminals after winding, which serve as the input and output terminals of that phase winding, respectively. The three-phase winding has a total of only six terminals. This eliminates the cumbersome phase separation, bridging, and welding processes required on the outside of the motor due to the large number of coils in traditional multi-slot hollow cup motors. This greatly simplifies the motor manufacturing process, improves production efficiency, and has high practicality. At the same time, it significantly reduces the potential fault risks such as poor welding, cold solder joints, and broken wires caused by many external solder joints, and improves the consistency and long-term reliability of motor operation. Since there are no external solder joints, the space occupied at the winding ends is lower, and the structure is more compact. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a multi-slot brushless hollow cup motor.

[0018] Figure 2 This is a schematic diagram of the structure of a multi-slot brushless hollow cup motor from a side view.

[0019] Figure 3 This is a structural schematic diagram of a multi-slot brushless hollow cup motor from the main viewpoint.

[0020] Figure 4 This is a cross-sectional view of the structure of a multi-slot brushless hollow cup motor.

[0021] Figure 5 This is a diagram showing the unfolded structure of a single coil.

[0022] Figure 6 Draft a diagram for coil winding.

[0023] Figure 7 The graph shows the simulation results of the rotor magnetic circuit matching coefficient and the air gap magnetic flux density amplitude.

[0024] Figure 8 Line graph showing the simulation results of the radial dimension comprehensive matching coefficient and the unit copper loss torque ratio of a multi-slot brushless hollow cup motor.

[0025] Figure 9 The plot shows the simulation results of the winding pitch ratio and torque copper loss ratio.

[0026] Figure 10 The plot shows the simulation results of the winding end tilt angle versus the torque copper loss ratio.

[0027] In the diagram: 1. Multi-slot brushless hollow cup motor; 10. Rotor; 20. Rotor magnet; 30. Stator winding; 31. Coil; 32. First apex angle; 33. Second apex angle; 34. Straight side; 40. Stator yoke. Detailed Implementation

[0028] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0029] In the description of this application, it should be noted that the directional terms such as "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this application.

[0030] It should be noted that the terms "first," "second," etc., in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0031] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0032] In a preferred embodiment, see Figures 1 to 6 This application provides a multi-slot brushless hollow cup motor 1. The motor adopts a radially nested coaxial structure, including a rotor 10, rotor magnets 20, stator windings 30, and stator yoke 40 arranged sequentially from the inside to the outside. The rotor 10 is a cylindrical rotating body structure, made of magnetically conductive carbon steel with high mechanical strength, which can withstand large centrifugal force at high speeds and effectively reduce the moment of inertia of the motor, thereby improving the dynamic response performance of the motor. The rotor magnets 20 are multiple independent permanent magnet blocks, which are uniformly bonded to the outer circumferential surface of the rotor 10 with high-strength structural adhesive. All rotor magnets 20 are arranged at equal intervals along the circumferential direction of the rotor 10 and rotate synchronously with the rotor 10. The stator windings 30 are solidified hollow cup windings, which are located between the rotor magnets 20 and the stator yoke 40. A uniform single-sided air gap is maintained between the inner circumferential surface of the stator windings 30 and the outer circumferential surface of the rotor magnets 20 to ensure that the rotor 10 can rotate freely and that the magnetic field can be effectively coupled.

[0033] The stator winding 30 has multiple stator slots, which are virtual slots evenly distributed along the circumference of the stator winding 30. These slots define the winding position and arrangement of the coils 31. The number of stator slots is an even natural number greater than or equal to six. The rotor magnet 20 is magnetized to form the number of motor poles, which is an even natural number greater than or equal to two. The number of motor poles is represented by the number of motor pole pairs, denoted by P. The number of motor pole pairs refers to the number of pairs of N / S poles appearing on the rotor magnet 20. The corresponding number of motor poles refers to the total number of N and S poles formed by the rotor magnet 20. Therefore, the number of motor poles is represented as 2P, and the ratio of the number of stator slots to the number of motor poles must be three. As a specific, non-limiting example, the number of stator slots could be twelve, corresponding to four motor poles. The number can also be eighteen, corresponding to six motor poles; more preferably, this embodiment provides a multi-slot brushless hollow cup motor 1 with 24 stator slots and 8 motor poles, the ratio of the number of stator slots to the number of motor poles is 3, and the stator winding 30 is wound with coils 31 of the same number as the number of stator slots. That is, in this embodiment, the stator winding 30 is composed of 24 independent coils 31, and all coils 31 are divided into three groups, A phase, B phase and C phase, according to the connection rules of three-phase windings, and each group contains an equal number of coils 31.

[0034] The winding structure of coil 31 is as follows Figure 6As shown, the coils 31 of the same phase winding are directly connected in series internally during the winding process of the stator winding 30. No additional intermediate taps need to be brought out during the winding process. Each phase winding only brings out two terminals after the winding is completed, which serve as the input and output terminals of that phase winding, respectively. The three-phase winding only brings out six terminals in total, namely A+, A-, B+, B-, C+, and C-. All terminals are concentrated on the same axial end face of the stator winding 30, and no bridging or welding operation of the same phase coils 31 is required outside the motor. It should be noted that the specific series connection pattern is as follows: starting from the first coil 31 of the phase, the coils are connected sequentially along the stator slots in the circumferential direction, skipping over two coils 31 at a time. Each coil 31 has two output terminals: a left output terminal and a right output terminal. That is, the right output terminal of the first coil 31 is directly connected to the right output terminal of the fourth coil 31, and the left output terminal of the fourth coil 31 is then connected to the left output terminal of the seventh coil 31, and so on, until all coils 31 of the phase are connected. The coils are connected in series to form a closed current path. Each phase winding has eight coils wound in alternating forward and reverse directions. Taking the 24-slot 8-pole motor of this embodiment as an example, each phase winding contains eight coils, with the winding direction following the sequence "forward-reverse-reverse-reverse-reverse-reverse". That is, the first coil and the fourth coil are wound in opposite directions. Forward winding means the coil starts winding from the left exit end, winding a single coil for N turns, and then exits from the right exit end. Reverse winding means the coil starts winding from the right exit end, winding a single coil for N turns, and then exits from the left exit end, ensuring the symmetry of the winding magnetic field. No additional wire connectors or taps are needed at any intermediate nodes during this connection process. After completing the winding and internal series connection of all three-phase coils 31, one terminal is led out from each end of each phase winding. A total of six terminals are led out from the three-phase windings to the outside of the motor for connection to the drive controller. This wiring method completely eliminates the cumbersome phase separation, bridging, and welding processes required externally for traditional multi-slot hollow cup motors due to the large number of coils (31). This greatly simplifies the motor manufacturing process, significantly reduces the potential risks of poor welding, cold solder joints, and broken wires caused by numerous external solder points, and improves the consistency and long-term reliability of motor operation. Furthermore, since no external solder points are needed, the space occupied at the winding ends is lower, resulting in a more compact structure.

[0035] Specifically, regarding the forming process of coil 31, in this embodiment, after each coil 31 is wound according to the above connection rules, it also needs to be flattened. The flattened coil 31 has a hexagonal structure; the rhomboid structure is a special case of the hexagonal structure. The purpose of flattening is to make the end shape of the winding regular, reduce the ineffective length at the ends, and allow the winding to fit into the annular space of the hollow cup motor. The flattened coil 31 has two straight edges 34 extending along the motor axis. These two straight edges 34 are the core part that generates cutting magnetic lines of force and generates torque. The span between the two straight edges 34 in the stator circumferential direction is defined as the pitch, which directly determines the response characteristics of the winding to different harmonic magnetic fields. When the obtained pitch value is controlled within the range of 2.5 to 3.5, the motor can obtain high output torque with low copper loss, which is within the engineering feasible range. If this value is too low, it indicates that the pitch of coil 31 is too small, the winding fails to fully link the effective working magnetic flux, the magnet utilization rate is insufficient, and the torque generated under the same current is limited. Under full-pitch conditions, the fundamental factor of the winding reaches its highest value when the pitch is 3, the magnetic flux linkage is the largest, and the magnetic field utilization efficiency reaches its optimal value. When the pitch exceeds 3, the magnetic flux linkage begins to decrease, the motor performance decreases accordingly, the length of the end of coil 31 and the total length of copper wire also increase significantly, leading to increased winding resistance, a sharp increase in copper loss, and ultimately a decrease in output torque per unit copper loss. Therefore, limiting the dimensionless value corresponding to the pitch of a single coil 31 after flattening and forming to the optimal range of 2.5 to 3.5 can fully utilize the magnetic field of the magnet while minimizing the winding's own losses, enabling the motor to achieve high torque density and high efficiency operation.

[0036] Furthermore, as a preferred method, when each coil 31 of the stator winding 30 is wound with a full pitch, that is, after a single coil 31 is flattened and formed, the circumferential span between its two straight sides 34 exactly corresponds to the three stator slot pitches. At this time, the corresponding dimensionless value mentioned above is three. Under the full pitch condition, the fundamental factor of the winding reaches its highest level, the magnetic field utilization efficiency reaches its optimal level, and the output torque per unit copper loss also reaches its peak value, which is the best balance point between comprehensive electromagnetic performance and process feasibility.

[0037] In addition to optimizing the span of coil 31, this embodiment also precisely limits the apex angle of a single coil 31 after flattening. The flattened single coil 31 has two axially opposite first apex angles 32 and 33, formed by bending the coil 31 at the end of the stator winding 30. Under ideal process conditions, the angles of the first apex angle 32 and the second apex angle 33 are equal to ensure the symmetry of the winding force and the uniformity of the end space distribution. The size of the apex angle directly affects the shape of the winding end and the end space fill rate. Therefore, limiting the angles of the first apex angle 32 and the second apex angle 33 of the flattened single coil 31 to less than or equal to 100 degrees (i.e., half-angle less than or equal to 50 degrees) effectively avoids the risk of an unlimited increase in end slot fill rate leading to a forced reduction in wire diameter. This ensures process feasibility while maintaining the motor operating in a high torque density and high efficiency range.

[0038] The multi-slot brushless hollow cup motor 1 in this embodiment has specific structural features in the axial direction, see details below. Figure 1 , Figure 2 and Figure 4 Along the axial direction of the motor, one end face of the stator winding 30 is flush with the corresponding end face of the stator yoke 40, while the other end face of the stator winding 30 is axially offset relative to the other corresponding end face of the stator yoke 40, and the two are not coplanar. This structure makes the motor present an asymmetrical shape in the axial direction. This asymmetrical design is beneficial for the actual installation and system integration of the coreless motor, as the axial offset space between the winding end and the yoke end face can be used to arrange other components, or to reserve sufficient and safe clearance for wiring and cable routing, thereby improving space utilization and layout flexibility.

[0039] To further clarify the geometric relationship of this axially asymmetrical structure and ensure the reliability of the motor, this embodiment comprehensively designs the axial length of the stator yoke 40 and the axial length of the stator winding 30. The straight edge 34 in the flattened single coil 31 connects the first apex 32 and the second apex 33, see [reference needed]. Figure 5The axial length of the straight side 34 is the axial length of the straight side of the winding. The axial distance between the two vertices is the total axial length of the entire stator winding 30. The axial length of the stator yoke 40 is set to be greater than or equal to the axial length of the straight side 34, and less than or equal to the total axial length of the stator winding 30. Thus, the length of the stator yoke 40 is greater than or equal to the axial length of the straight side of the winding, which ensures that all current-carrying conductors that generate effective torque are completely enveloped within the magnetic path of the stator yoke 40. When the straight side 34 cuts the magnetic flux within its entire axial length, the back side has yoke material to provide a low magnetic resistance magnetic flux loop, ensuring the uniformity and consistency of the magnetic field and avoiding torque loss and increased local leakage flux due to missing magnetic circuits. At the same time, the length of the stator yoke 40 is less than or equal to the total axial length of the stator winding 30, taking into account the existence of the bent portion at the end of the winding. The yoke will not unnecessarily extend beyond the end of the coil 31, thereby avoiding waste of the motor's axial dimensions and increased weight, which is conducive to achieving miniaturization and lightweight design of the motor.

[0040] Furthermore, this application also provides a size matching method for a multi-slot brushless hollow cup motor 1, see [link to relevant documentation]. Figure 3 , Figures 5 to 10 The size matching method for the multi-slot brushless hollow cup motor 1 is applicable to the multi-slot brushless hollow cup motor 1 as described in any of the above-mentioned methods. The size matching method includes: determining the number of stator slots of the multi-slot brushless hollow cup motor 1. With the number of motor poles , The number of pole pairs of the motor is to meet the requirement of the number of stator slots. With the number of motor poles ratio Set the inner diameter value of rotor magnet 20. Stator outer diameter value Stator yoke 40 magnetic flux density The single-sided air gap value defined by the stator winding 30 and the rotor magnet 20 and the total axial length of stator winding 30 For a fixed value, the remanence of the rotor magnet 20 is... The maximum value of the magnet used is taken as the constant value, and the outer diameter of the stator is the outer diameter of the stator winding 30. With a stator yoke thickness of 40 The sum of these values ​​is used to determine the thickness of the stator yoke at 40 mm. Rotor magnet 20mm thickness Thickness of stator winding 30 The unknown parameters to be solved are: the thickness of the stator yoke 40 mm is calculated based on the numerical matching parameters set above. With the thickness of the magnet The appropriate value range; for a stator yoke with a thickness of 40 mm. With the thickness of the magnet Set the value to obtain the thickness value of stator winding 30. Based on the winding pitch constraint and slot fill factor constraint, the straight edge distance of a single winding coil 31 after unfolding is calculated. and the axial length of the straight side of the winding 34 The applicable value range, and the distance of the straight edge. and the axial length of the straight side of the winding 34 Set the values ​​to complete the selection of the multi-slot brushless hollow cup motor 1.

[0041] Specifically, in this embodiment, the number of stator slots Q is selected as 24, and the number of motor poles is 8, that is, the number of motor pole pairs P is equal to 4. This configuration meets the design requirement that the ratio of the number of stator slots to the number of motor poles is 3. The use of this slot-pole combination, with an integer number of slots per pole per phase, is beneficial for forming a symmetrical three-phase winding, reducing cogging torque and torque ripple, and at the same time provides a structural basis for the subsequent direct series connection of each phase coil 31.

[0042] Furthermore, there is a numerical relationship between the thickness of the stator yoke 40 and the thickness of the magnet, meaning that it must meet certain requirements. ;in, and This is the magnetic circuit correction factor. For the thickness of the magnet, The stator yoke is 40 mm thick. The stator yoke has a magnetic flux density of 40. The remanence of the magnet is expressed in tons (T); it must also satisfy condition 3 > 1. >0.8, This refers to the thickness of the stator winding, in millimeters, and specifically the thickness of stator winding 30. ;in This is the outer diameter value of the stator winding 30. This is the inner diameter value of rotor magnet 20. The air gap value defined by the stator winding 30 and the rotor magnet 20 is expressed in millimeters.

[0043] Specifically, it should be noted that finite element simulations were performed for the stator and rotor coordinated design; see [link / reference]. Figure 7 The results show that the x-axis is , Indicates the total magnetization capacity. This indicates the magnetic flux carrying capacity of the stator yoke 40. The magnetic flux passes through each pair of poles; the more poles there are, the smaller the magnetic flux per pole. Therefore, the stator yoke can be designed to be thinner. This indicates whether the magnet's remanence is sufficient to drive the yoke. Specifically, the formula reflects the relative relationships of various parameters: when the magnet's remanence... Magnetic flux density of stator yoke 40 and the number of motor pole pairs P When the parameters are fixed, the thickness of the magnet The larger the size, the more stator yoke thickness is required. The thicker the magnet, the better; conversely, the thinner the magnet, the better. Residual magnetism of magnets and the number of motor pole pairs P When the parameters are fixed, the stator yoke thickness The thicker the stator yoke, the higher the allowable magnetic flux density. The smaller the value, the lower the value; the vertical axis represents the air gap magnetic flux density amplitude, in tons (T). When the magnetic flux density is less than 0.35, the magnet thickness is low or the remanence is low, resulting in insufficient magnetic flux. Less flux passes through the air gap to the yoke, causing a decrease in the air gap magnetic flux density amplitude, which in turn leads to a reduction in output torque. When the magnetic flux density is greater than 1.25, if the magnet is too thick or the yoke is too thin, a large amount of magnetic flux will arrive at the stator yoke 40. However, if the yoke is too narrow, it will not be able to receive a large amount of magnetic flux, resulting in magnetic saturation of the yoke. Magnetic saturation will lead to increased iron loss on the one hand, and decreased motor overload capacity on the other hand, ultimately leading to decreased motor efficiency, reduced operational reliability, and the inability to increase the air gap magnetic flux density amplitude.

[0044] Also see Figure 8 Furthermore, finite element simulations were conducted on the stator-rotor co-design, and the results show that: 3> Within the range of >0.8, the motor can achieve higher torque density with lower copper losses. When the value is ≤0.8, it indicates that the rotor magnet thickness is too large, the radial space of the stator yoke and winding spool is excessively occupied, and the insufficient amount of winding copper wire leads to increased resistance and copper loss. At the same time, insufficient stator yoke thickness easily causes magnetic saturation, increasing iron loss, and ultimately resulting in a significant decrease in the torque ratio per unit copper loss. When the value is ≥3, it indicates that the rotor magnet thickness is too small, resulting in insufficient magnetic supply capacity, which leads to a decrease in air gap magnetic flux density and a decrease in output torque. At the same time, the excessive thickness of the stator yoke or winding spool causes a waste of radial space, increasing the overall size of the motor but not increasing the torque density accordingly.

[0045] Therefore, this application document limits At the same time, ensure Within this range, the motor can achieve a balance between torque density and efficiency, ensuring that the ratio of magnet thickness to yoke thickness matches the magnetic circuit saturation characteristics under different pole pairs, thus avoiding oversaturation of the stator yoke or waste of magnets.

[0046] Therefore, when selecting the multi-slot brushless hollow cup motor 1, the inner diameter value of the rotor magnet 20 is given based on the overall dimensions and performance objectives of the motor. The outer diameter of the stator is 12 mm. It is 23 mm long, and the stator yoke has a magnetic flux density of 40. Take 1.5T as the value of the single-sided air gap defined between the stator winding 30 and the rotor magnet 20. The total axial length of stator winding 30 is 0.3 mm. It is 35 mm long. Remanence of the magnet. The maximum value is taken based on the selected magnet grade. The remanence of the magnet used in this embodiment is... The value is 1.44T, and this is used as a fixed value in the calculation. These parameters determine the basic volume of the motor, the air gap magnetic circuit length, and the excitation capacity boundary. The remaining key unknown dimension is the 40mm thickness of the stator yoke. Rotor magnet 20mm thickness and the thickness of stator winding 30 H This will be obtained through optimized matching based on these fixed parameters.

[0047] From the above inequality regarding whether the magnetic circuit is balanced, we can obtain: This gives the range of the ratio of magnet thickness to yoke thickness: Therefore, under the premise of satisfying magnetic circuit matching, the ratio of the thickness of the rotor magnet 20 to the thickness of the stator yoke 40 should be between 1.458 and 5.208. Meanwhile, based on... , can be obtained Based on the above ratio, and considering the actual machining accuracy and standardization requirements, a stator yoke thickness of 40mm can be selected. The appropriate value is determined. In this embodiment, the stator yoke thickness is set to 40 mm. If the value is 0.9 mm, then the corresponding magnet thickness is... The lower limit for the value is 1.31 mm, and the upper limit is approximately 4.69 mm. Considering the compactness of the radial space of the hollow cup motor, the influence of the rotor's outer diameter on the moment of inertia, and the standardized thickness specifications of the magnets, the thickness of the rotor magnet 20 is further increased. The preferred practical range is defined as 2.25 mm to 2.8 mm. Within this range, the thickness of the rotor magnet 20 can be flexibly selected according to specific torque density, speed, and cost requirements. The diameter is 2.5 mm, which meets the magnetic circuit cooperative constraint.

[0048] After completing the stator yoke with a thickness of 40 mm With the thickness of the magnet After obtaining the initial values, it is necessary to determine the radial thickness of the stator winding 30. The outer diameter of the stator winding 30 and the inner diameter of stator winding 30 Based on the radial dimension chain of the motor, from the inside out, the dimensions are: inner diameter of rotor magnet 20, magnet thickness, single-sided air gap, stator winding thickness 30, and stator yoke thickness 40. The outer diameter of stator winding 30... Then it is millimeters, due to the outer diameter of the stator winding 30 There is a certain gap between the stator yoke 40 and the outer diameter of the stator winding 30. A 0.1 mm gap of insulating tape is provided between the stator yoke 40 and the winding yoke 30 for winding and fixing the insulating tape; therefore, the outer diameter of the stator winding 30 in this application is preferably [missing information]. The value is 21 mm; the inner diameter of the stator winding is 30 mm. It can be calculated by the following formula millimeters; and thus the thickness of the stator winding 30 mm. That is, half the difference between the outer diameter and the inner diameter of the winding, i.e. Millimeters.

[0049] Furthermore, winding pitch And must meet ;in, This is the inner diameter value of the stator winding 30. This refers to the straight edge distance of a single winding coil 31 after unfolding, in millimeters. That is, the number of stator slots. and The coil pitch parameter value is 31; winding apex angle. The angle is twice the tilt angle at the winding end, and thus the tilt angle at the winding end... ;in This is the total axial length of the winding. The axial length of the straight side of the winding is 34 mm. For angle parameters.

[0050] Specifically, to verify Impact on motor performance This refers to the pitch of the two straight sides of the hollow cup coil 31 after it is biased and formed. Finite element simulations were performed for different values. The output torque under unit copper loss, i.e., the ratio of torque to copper loss, was used as the evaluation index, with the unit being mNm / W.

[0051] See simulation results Figure 9 The x-axis is The vertical axis represents the torque-to-copper loss ratio. Therefore, when As the value increases, the magnetic field is utilized more fully, and the output torque gradually increases for the same copper loss; when As the value increases, the magnetic field utilization rate begins to decrease. Higher end heights and longer copper wires lead to increased resistance and copper losses, resulting in a gradual decrease in output torque for the same copper loss. The range is the engineering feasible region obtained by optimizing the output curve per unit copper loss through finite element simulation. It is not a precise value derived from theory, but has practical guiding significance. Within this range, the motor can obtain higher torque with lower copper loss.

[0052] At the same time, further based on the target Finite element simulation was performed; see [link / reference] Figure 10 The results showed that when As the angle increases from 40° to 47.5°, the torque-to-copper-loss ratio shows an upward trend, reaching a peak near 47.5°; while when After the angle exceeds 47.5°, the output power per unit copper loss begins to decrease, due to the excessively large angle corresponding to the axial length of the straight side of the winding. Increasing the angle flattens the winding ends, limiting the number of turns of coil 31 within the same winding space. Furthermore, an excessively large angle increases the end slot fill factor, reducing the winding space. The end slot fill factor is constrained by the coil 31 manufacturing process; therefore, when the end slot fill factor reaches its limit, the winding coil 31 needs a smaller wire diameter, increasing resistance and copper loss, leading to a decrease in output torque per unit copper loss. At ≤50°, the output per unit copper loss remains above 90% of the peak value, still within the high-performance range; therefore, the output per unit copper loss as defined in this application document is within the high-performance range. Within the range of ≤50°, the motor can achieve higher torque density with lower copper loss, while taking into account both slot fill factor and process feasibility.

[0053] Furthermore, the straight edge distance of a single winding coil 31 after unfolding is calculated. And the axial length of the straight side of the winding 34 At that time, the pitch constraint condition is expressed as: ;in Taking the value 3.14, we get: Unit: millimeter; introduces vertex angle constraint; winding end tilt angle. That is, after flattening and forming, the tangent of the half-apex angle of coil 31 satisfies: ≤50°, and This is to prevent excessive tilting of the end from causing a sudden increase in the slot fill factor.

[0054] Preferably, the slot fill factor constraint is expressed as: ;in, The maximum wire diameter for the paint coating, in millimeters. This refers to the number of turns in a single coil of the winding. For the number of roots, and This is the slot fill factor.

[0055] Therefore, further, a fill factor constraint is applied to the above calculation results, and the maximum wire diameter of the paint layer is set. The diameter is 0.304 mm, and the number of turns per coil in the winding is... It is 18, and it is wrapped around the root number. Substituting 1 into the constant factor calculation, we get: ; (in ) that is Therefore, after simplification, we get: At this point, all constraints are combined: ; Angle constraint requirements ≤1.1918; the upper limit of the actual effectiveness of the slot fill factor constraint is... ≤1.09, lower limit is ≥0.72. Therefore, when selecting the axial length of the straight side of the winding (34),... At that time, it is necessary to ensure that there is The value satisfies all of the above conditions simultaneously.

[0056] Therefore, this application document specifies the axial length of the straight side of the winding as 34. The value is taken to be between 26 mm and 28 mm for verification. This is when the axial length of the straight side of the winding is 34 mm. When the value is 26 mm, The value is 9 mm, obtained from the lower limit of the fill factor. ≥0.720×9=6.48 mm, from the upper limit... ≤1.090×9=9.81 mm, since the upper limit of the pitch constraint is 8.84 mm, therefore The actual acceptable value is between 6.48 mm and 8.84 mm. Similarly, when... When the value is 28 mm, The value is 7 mm, obtained from the lower limit of the fill factor. ≥5.04 mm, obtained from the upper limit ≤1.090×7=7.63 mm. Since the lower limit of the pitch constraint is 6.32 mm, therefore... The actual acceptable value is between 6.32 mm and 7.63 mm.

[0057] Clearly, there exists an axial length of 34mm belonging to the straight side of the winding within the range of 26mm to 28mm. To maximize the fundamental factor of the winding magnetic field, a full-pitch winding is preferred, meaning a pitch of 3 is chosen. Then, by calculation, we can obtain Millimeters. This refers to the distance of the straight edge of a single winding coil 31 after unfolding. The value of 7.579 mm falls between 6.48 mm and 8.84 mm, and also between 6.32 mm and 7.63 mm, thus determining the axial length of the 34-inch straight side of the winding. You can choose either 26mm or 28mm at this point.

[0058] Select the axial length of the straight side of the winding as 34. The value is 28 mm, which is used for the full-rate check of the groove. ≈89%, meeting the process requirements; if the axial length of the straight side of the winding is selected as 34... To verify the full-rate of the groove, we substitute 26 mm. Substituting the values ​​into the calculation, the fill factor of the tank is approximately 79%, which still meets the process requirements.

[0059] Furthermore, in a specific embodiment, a 24-slot, 8-pole multi-slot brushless hollow cup motor 1 is also disclosed, and all dimensional parameters of the motor satisfy the above-mentioned dimensional matching relationship. The stator slot number of this multi-slot brushless hollow cup motor 1 is... The number of motor poles is 24. The outer diameter of the stator is 8. It is 20 mm, corresponding to the inner diameter of rotor magnet 20. The total axial length of the winding is 12 mm. The axial length of the straight side of coil 31 in the winding is 34 mm. The outer diameter of the stator winding is 26 mm, and the outer diameter of the stator winding is 30 mm. The inner diameter of the stator winding is 18 mm. The single-sided air gap value defined between the stator winding 30 and the rotor magnet 20 is 15.6 mm. The thickness of rotor magnet 20 is 0.3 mm. The thickness of the stator yoke is 1.5 mm, and the thickness of the stator yoke is 40 mm The remanence of the magnet is 0.9 mm. The magnetic flux density of the stator yoke 40 is 1.44T. It is 1.5T, with 31 turns per coil. The number of parallel windings is 20. 1, the maximum wire diameter of the winding with enamel coating. The straight edge distance of a single winding coil 31 after unfolding is 0.229 mm. That is, 6.6 mm, pitch y is 3, and winding apex angle The temperature was 79 degrees Celsius, and the fill factor reached 80.9%.

[0060] In one embodiment, this application also provides a linear joint module, which is suitable for use within a robot structure, and the linear joint module includes the multi-slot brushless hollow cup motor 1 described in any one of the above claims.

[0061] Therefore, through the organic combination of multiple technical features such as slot-pole matching, winding connection method, geometric constraints of coil 31, stator and rotor magnetic circuit collaborative design, and comprehensive management of slot fill factor, the multi-slot pole brushless coreless motor 1 provided in this application has achieved significant technical progress. This motor is no longer limited by the low torque density and low output of traditional low-pole coreless motors, and can output higher torque, making it suitable for applications requiring high torque density. Its unique internal direct series connection of the same-phase coils 31 reduces the number of external wiring terminals of the three-phase windings to a minimum of six, completely eliminating the complex external wire bridging and welding processes, greatly simplifying the production process and improving product consistency, reliability, and manufacturing efficiency. Simultaneously, through refined constraints on the coil 31 span and apex angle, the motor is ensured to always operate in a high-efficiency range, and the stator-rotor collaborative design principle avoids design redundancy and performance bottlenecks. Furthermore, the axial asymmetric structure and clear axial dimensional relationship make the motor more adaptable and flexible during system integration. All the size definitions, parameter ranges, and coordination coefficients were obtained through extensive analysis using finite element simulation and optimization in conjunction with actual process verification. These results are engineering feasibility studies with strong practical guidance, enabling those skilled in the art to manufacture multi-slot brushless hollow cup motors with high torque density, high reliability, and low process complexity based on the parameters and relationships described.

[0062] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. A multi-slot brushless hollow cup motor, characterized in that, include: The rotor, rotor magnet, stator winding, and stator yoke are arranged sequentially. The rotor magnet is fixed to the outer circumference of the rotor and rotates synchronously with the rotor. The stator winding is a solidified hollow cup winding, which is composed of multiple coils. The multiple coils are divided into three-phase windings. The coils of the same phase winding are directly connected in series internally during the winding process of the stator winding. When connected in series, they are connected sequentially across two coils. Each phase winding has only two terminals, and the three-phase winding has only six terminals in total. The dimensional parameters of the multi-slot brushless hollow cup motor include the number of stator slots. With the number of motor poles The number of stator slots is equal to the number of coils. The number of pole pairs of the motor, and the number of stator slots is also specified. With the number of poles of the motor ratio The number of poles of the motor It is an even natural number greater than two; There is a numerical relationship between the thickness of the stator yoke and the thickness of the rotor magnet, that is, it must meet the following requirements. Where 1.25 and 0.35 are magnetic circuit correction coefficients. The thickness of the rotor magnet is [missing information]. The thickness of the stator yoke is in millimeters. The magnetic flux density of the stator yoke is given. Remanence of the magnet, measured in tons (T). Simultaneously, it must meet the following requirements. ,in, The thickness value of the stator winding. This is the outer diameter value of the stator. The value represents the inner diameter of the rotor magnet, in millimeters.

2. The multi-slot brushless hollow cup motor as described in claim 1, characterized in that, Each coil is flattened after winding, and each coil includes two axially extending straight sides; and after flattening, the pitch of each coil is... , ;in, The outer diameter value of the stator winding is given. This is the inner diameter value of the stator winding. The distance between the straight edges of a single winding coil after unfolding, in millimeters. The number of stator slots, and This refers to the coil pitch parameter value.

3. The multi-slot brushless hollow cup motor as described in claim 2, characterized in that, The flattened coil has two oppositely arranged winding apex angles. The angle is twice the tilt angle at the winding end, and thus the tilt angle at the winding end... ;in This is the total axial length of the winding. The axial length of the straight side of the coil in the winding, in millimeters. For angle parameters.

4. The multi-slot brushless hollow cup motor as described in claim 3, characterized in that, Slot fill factor constraint is expressed as ;in, Maximum wire diameter with enamel coating, in millimeters. The number of turns in a single coil. For the number of roots, and This represents the slot fill factor.

5. The multi-slot brushless hollow cup motor as described in claim 1, characterized in that, An insulating tape gap is provided on one side between the inner diameter of the stator yoke and the outer diameter of the stator winding.

6. The multi-slot brushless hollow cup motor as described in claim 1, characterized in that, The rotor magnets are arranged in a tile-like or ring-like structure.

7. The multi-slot brushless hollow cup motor as described in claim 2, characterized in that, Each coil of the stator winding is wound with a full pitch. It equals 3.

8. The multi-slot brushless hollow cup motor as described in claim 3, characterized in that, Along the axial direction of the multi-slot brushless hollow cup motor, one end face of the stator winding is flush with the corresponding end face of the stator yoke, and the other end face of the stator winding is axially offset relative to the other corresponding end face of the stator yoke.

9. The multi-slot brushless hollow cup motor as described in claim 8, characterized in that, In the flattened coil, the straight edge extending axially is used to connect the oppositely arranged winding apex angles, the winding apex angles including a first apex angle and a second apex angle; Wherein, the axial distance between the first vertex and the second vertex is the total axial length of the stator winding, and the axial length of the stator yoke is greater than or equal to the axial length of the straight side and less than or equal to the total axial length of the stator winding.

10. A linear joint module, characterized in that, The linear joint module is suitable for use within a robot structure, and the linear joint module includes a multi-slot brushless hollow cup motor as described in any one of claims 1-9.

Images