Coreless motor commutator and coreless motor

Abstract

The invention relates to the technical field of commutators, and discloses a coreless motor commutator and a coreless motor, the commutator comprises a conductive assembly formed by enclosing a plurality of integrally formed conductive sheets, and an insulating substrate combined with the conductive assembly through injection molding, and the width of a leading-out section of each conductive sheet is smaller than that of a brush contact section of the conductive sheet. The insulating matrix is filled between the adjacent leading-out sections and completely wraps the inner surface of the conductive assembly, and the leading-out sections are provided with exposed winding welding ends; the insulating substrate is provided with a non-penetrating groove, the groove is recessed along the radial direction and extends along the axial direction, and the groove extends from the second end of the electric brush contact section and exceeds the first end, but does not exceed the leading-out section. According to the hollow cup motor commutator and the hollow cup motor, through the design of integral forming and non-penetrating grooves, the sheet arranging procedure is omitted, the production efficiency is improved, meanwhile, the mechanical strength is enhanced, the risk that glue permeates into and blocks the groove bodies during assembling and gluing is reduced, and therefore the overall reliability of the hollow cup motor commutator and the hollow cup motor is improved, and the service life of the hollow cup motor commutator and the hollow cup motor is prolonged.

Description

Technical Field

[0001] This invention relates to the field of commutator technology, specifically to a coreless motor commutator and a coreless motor. Background Technology

[0002] As a core component of a coreless motor, the commutator's performance directly determines the motor's reliability, lifespan, and operational quality. In related technologies, a coreless motor commutator typically comprises a conductive assembly formed by multiple conductive sheets and an insulating substrate bonded to the conductive assembly. There are two main manufacturing processes: the first involves individually machining the conductive sheets, arranging them circumferentially through a sheet-laying process, and then bonding them to the insulating substrate; the second involves integrally forming a conductive blank ring through stamping, eliminating the need for separate sheet arrangement, directly injection molding it to the insulating substrate, and then dividing the conductive blank ring into multiple mutually insulated conductive sheets through a milling process, forming independent conductive zones.

[0003] In the manufacturing of small-diameter commutators, the second type of manufacturing process faces challenges such as narrow slot width and high process precision requirements. This makes it difficult to guarantee the circumferential spacing consistency of the conductive sheets and the overall mechanical strength. In addition, during the milling process, adjacent conductive sheets of the commutator are often separated and insulated by through slots that penetrate the insulation substrate at opposite ends along the axial direction. However, the through slot structure has two main drawbacks. First, it requires a significant amount of structural subtraction from the insulation substrate, affecting the structural strength and service life of the commutator. Second, during the product coating process, the adhesive can easily leak into the slot along one end, causing blockage and affecting the toner discharge function. Summary of the Invention

[0004] This invention provides a hollow cup motor commutator to solve the problems of poor circumferential spacing of conductive sheets, low strength of insulating substrate, and easy blockage of slots when small-diameter commutators are manufactured using a stamping integral forming process.

[0005] In a first aspect, the present invention provides a commutator for a hollow cup motor, comprising: a conductive component, wherein the conductive component is a coaxial cylindrical structure formed by multiple conductive sheets, the multiple conductive sheets being evenly spaced along the circumference; each conductive sheet includes an integrally formed brush contact section and a lead-out section, the brush contact section having a first end and a second end arranged axially at relative intervals, the lead-out section being connected to the first end of the brush contact section, and the circumferential dimension w1 of the lead-out section being smaller than the circumferential dimension w2 of the brush contact section; and an insulating substrate, the insulating substrate being injection molded to the conductive component. The components are connected as a single unit, filling the space between the lead-out sections of two adjacent conductive sheets and completely covering the circumferential inner surface of the conductive component; the lead-out section has an exposed section extending out of the insulating substrate, the end of the exposed section away from the first end forming a winding welding end; the portion of the insulating substrate located between adjacent conductive sheets has a groove, the groove being recessed radially toward the commutator central axis and extending axially; in the extending direction of the groove, the groove extends from the second end of the brush contact section and beyond the first end of the brush contact section, but does not extend beyond the lead-out section.

[0006] Beneficial effects: By adopting a process of stamping the conductive blank ring and injection molding the insulating substrate into one piece and then milling the grooves, separate arrangement of the sheets is eliminated, effectively avoiding the problem of poor circumferential spacing consistency of conductive sheets caused by narrow groove width and high precision requirements in the manufacturing of small-diameter commutators. This significantly improves the overall mechanical strength of the conductive components. At the same time, the non-through groove design not only achieves separation and insulation between adjacent conductive sheets, but also reduces the structural deduction of the insulating substrate, ensuring the structural strength and service life of the commutator. It also avoids groove blockage caused by glue leakage during the gluing process, ensuring stable and reliable toner discharge function. In addition, the clearly defined exposed section of the lead-out section and the winding welding end structure at the end provide a stable connection foundation for the motor windings, further improving the assembly reliability and operational stability of the commutator.

[0007] In one alternative embodiment, the insulating substrate forms a bottom surface on a side radially facing the groove, the bottom surface including a planar segment and a curved segment connected along the extension direction of the groove, wherein the curved segment is formed on a side near the first end of the brush contact segment; the groove depth of the groove corresponding to the curved segment gradually decreases along the direction extending from the second end to the first end.

[0008] Beneficial effects: The design of the gradual depth allows the groove to transition smoothly at the termination area, which helps to improve the strength of the insulating substrate at this point, thereby enhancing the crack resistance of the insulating substrate in this area and the overall structural durability.

[0009] In one alternative embodiment, the brush contact segment has a chamfer on its inner circumferential surface near the first end, the shape of which matches the curved surface segment.

[0010] Beneficial effects: By pre-thinning the radial thickness of the conductive sheet in the groove end region, it helps to ensure that the annular connecting strip connecting each conductive sheet can be completely cut off in the subsequent milling process, thereby improving the reliability of electrical isolation of the conductive sheet and the yield.

[0011] In one alternative implementation, the curvature of the surface segment is greater than or equal to 0.125.

[0012] Beneficial effects: By limiting the curvature of the surface segment to this range, larger diameter and stronger milling cutters can be used during machining. While ensuring reliable disconnection of conductive connections, the stability and machining accuracy of the milling process are improved, which helps to ensure the consistency of slot width and the overall quality of the commutator.

[0013] In one optional embodiment, the axial dimension of the brush contact section is h1, and the axial dimension of the commutator is h2, satisfying: h1 / h2≥0.4.

[0014] Beneficial effects: By limiting the minimum axial proportion of the brush contact area, the necessary space can be left for the insulating substrate to perform its support and fixing functions while ensuring the stable contact and commutation performance of the brush. This achieves an optimized balance between electrical performance and mechanical structure within a limited axial dimension.

[0015] In one alternative embodiment, the circumferential dimension w1 of the lead-out section and the circumferential dimension w2 of the brush contact section satisfy the following condition: 0.3 ≤ w1 / w2 ≤ 0.8.

[0016] Beneficial effects: By limiting w1 / w2 within this range, the electrical system ensures that the lead-out section has sufficient cross-sectional area to carry current, the mechanical system avoids insufficient strength caused by an excessively narrow lead-out section, and the process system prevents the punch in the stamping die from being too fragile. This comprehensively optimizes the electrical performance, reliability, and manufacturability of the product.

[0017] In one optional embodiment, the lead-out section includes a first section and a second section, the second section being connected to the first section via a bend, the first section and the second section being arranged at an angle, and the portion of the second section extending out of the insulating substrate forming the exposed section.

[0018] Beneficial effects: It provides more flexible space for the lead-out, arrangement and welding of winding wires, making the winding connection more convenient and reliable in the extremely compact micro motor, and also helps to reduce the risk of short circuits caused by space conflicts at the connection points.

[0019] In one alternative embodiment, the circumferential dimension of the winding welding end is w3, satisfying: w3 / w1≥1.1.

[0020] Beneficial effects: It increases the contact area of ​​the winding welding end, which helps to reduce the contact resistance and current density at the welding point. This not only makes it easier to form a reliable connection during the welding process, but also improves the durability of the welding point under long-term vibration and thermal cycling, and enhances the stability of the electrical connection.

[0021] In one optional embodiment, the insulating substrate includes a lower cylinder and an upper cylinder arranged coaxially, the groove is formed on the outer periphery of the lower cylinder, and the bent portion is embedded and fixed in the upper cylinder; the inner diameter of the upper cylinder is equal to the inner diameter of the lower cylinder, and the outer diameter of the upper cylinder is greater than the outer diameter of the lower cylinder.

[0022] Beneficial effects: This stepped structure provides more material thickness for the upper cylinder, thereby enhancing the covering and fixing strength of the bending part and the lead-out section; at the same time, the increased outer diameter area can serve as an assembly positioning reference, improving the accuracy and convenience of commutator assembly in the motor.

[0023] Secondly, the present invention also provides a coreless motor, including the coreless motor commutator of any of the above claims.

[0024] Beneficial effects: Due to the adoption of the commutator with high precision, high strength, high reliability and optimized structural design, the motor as a whole can achieve smoother commutation performance, lower operating noise and sparks, higher mechanical reliability and longer service life. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is one of the structural schematic diagrams of a hollow cup motor commutator according to an embodiment of the present invention;

[0027] Figure 2 This is an unfolded view of the conductive blank ring of a hollow cup motor commutator according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the conductive component of a hollow cup motor commutator according to an embodiment of the present invention; Figure 4 This is a second schematic diagram of the structure of a hollow cup motor commutator according to an embodiment of the present invention; Figure 5 This is a top view of a hollow cup motor commutator according to an embodiment of the present invention; Figure 6 for Figure 5 A cross-sectional view along QQ.

[0028] Explanation of reference numerals in the attached figures: 1. Conductive sheet; 101. Brush contact section; 1011. First end; 1012. Second end; 1013. Chamfer; 1014. Inner hook structure; 102. Lead-out section; 1021. First section; 1022. Second section; 1023. Exposed section; 1024. Bending part; 1025. Winding welding end; 2. Insulating substrate; 201. Groove; 202. Bottom surface; 2021. Planar section; 2022. Curved section; 203. Lower cylinder; 204. Upper cylinder. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0030] Currently, the mainstream manufacturing process for coreless motor commutators in the industry is still the traditional method of "single-piece stamping-layout-injection molding". Although it can meet basic production needs, it has problems such as low efficiency and large human influence. The process of stamping the conductive blank ring and the insulating substrate into one piece and then injection molding and milling the groove has obvious advantages in production efficiency and cost control because it does not require separate layout. It is gradually becoming the direction explored by the industry, especially suitable for scenarios with high requirements for mass production efficiency.

[0031] However, the second type of process faces significant technical challenges in manufacturing small-diameter hollow cup motor commutators. On the one hand, the small spacing between the conductive plates in small-diameter commutators results in extremely narrow grooves that need to be machined in the milling process. This places extremely high demands on the precision of the processing equipment and the control of the operating process. In actual production, it is difficult to accurately control the groove width and position, which in turn leads to poor circumferential spacing consistency among the conductive plates. This not only affects the smoothness of current switching during commutation but also reduces the overall mechanical strength of the conductive components. Under the centrifugal force and thermal stress generated by the high-speed operation of the motor, the conductive plates are prone to loosening, deformation, or even failure.

[0032] On the other hand, in related technologies, to achieve separation and insulation between adjacent conductive plates, a through-slot structure that runs axially through both ends of the insulating substrate is commonly used. This through-slot also serves to accommodate and drain carbon dust generated by carbon brush friction. However, the through-slot structure has drawbacks: First, the through-slot completely penetrates the upper and lower end faces of the insulating substrate along the axial direction, resulting in a large amount of structural reduction in the insulating substrate, which damages the integrity of the insulating substrate. This leads to a decrease in the overall structural strength of the commutator, making it prone to cracking due to stress concentration during long-term use, thus shortening its service life. Second, the commutator requires adhesive application during assembly to ensure reliable connection. However, the through-slot design makes it easy for adhesive to seep into the inside of the slot along one end. After the adhesive cures, it will cause blockage in the slot, preventing timely drainage of carbon dust generated by carbon brush friction. This carbon dust will accumulate at the contact points between the conductive plates and the brushes, increasing contact resistance, affecting conductivity, and accelerating wear on the brushes and conductive plates. This further reduces the operational stability and service life of the commutator and even the entire motor.

[0033] The following is combined with Figures 1 to 6 The following describes embodiments of the present invention.

[0034] According to an embodiment of the present invention, a commutator for a hollow cup motor is provided, comprising: a conductive component, which is a coaxial cylindrical structure formed by multiple conductive sheets 1, the multiple conductive sheets 1 being evenly spaced along the circumference; each conductive sheet 1 includes an integrally formed brush contact section 101 and a lead-out section 102, the brush contact section 101 having a first end 1011 and a second end 1012 arranged axially at relative intervals, the lead-out section 102 being connected to the first end 1011 of the brush contact section 101, and the circumferential dimension w1 of the lead-out section 102 being smaller than the circumferential dimension w2 of the brush contact section 101; and an insulating substrate 2, the insulating substrate 2 being injection molded to the conductive component. The components are connected as one unit, filling the space between the lead-out sections 102 of two adjacent conductive sheets 1 and completely covering the circumferential inner surface of the conductive assembly; the lead-out section 102 has an exposed section 1023 extending out of the insulating substrate 2, and the end of the exposed section 1023 away from the first end 1011 forms a winding welding end 1025; the portion of the insulating substrate 2 located between adjacent conductive sheets 1 is provided with a groove 201, the groove 201 is recessed radially toward the central axis of the commutator and extends axially; in the extension direction of the groove 201, the groove 201 extends from the second end 1012 of the brush contact section 101 and exceeds the first end 1011 of the brush contact section 101, but does not exceed the lead-out section 102.

[0035] In this embodiment, as Figure 1As shown, multiple conductive sheets 1 are arranged circumferentially at uniform intervals around a central axis. The angular distance or arc length between each conductive sheet 1 in the circumferential direction around the central axis is approximately equal. Each conductive sheet 1 includes an integrally formed brush contact section 101 and a lead-out section 102. Integral forming means that the brush contact section 101 and the lead-out section 102 are simultaneously formed from a continuous conductive material blank through processes such as stamping or casting. There is no subsequent welding or riveting connection interface between them, thus providing higher mechanical integrity and conductive reliability. The brush contact section 101 has a first end 1011 and a second end 1012 that are spaced apart along the axial direction. The axial direction refers to the direction parallel to the central axis of the commutator. The first end 1011 and the second end 1012 define the two axially opposite ends of the brush contact section 101. The lead-out section 102 is connected to the first end 1011 of the brush contact section 101, and the circumferential dimension w1 of the lead-out section 102 is smaller than the circumferential dimension w2 of the brush contact section 101. The circumferential dimension can be understood as the width of the conductive sheet 1 in the circumferential direction. The design that w1 is smaller than w2 makes the lead-out section 102 narrower in width compared to the brush contact section 101. On the one hand, this provides a clear location for the winding connection at the end of the lead-out section 102 within a limited space. On the other hand, the narrowed root design also creates space for the subsequent filling and covering of the insulating substrate 2, which helps to enhance the bonding force.

[0036] The insulating substrate 2 is integrally connected to the conductive components via injection molding. In this embodiment, the insulating substrate 2 is a structure made of insulating materials such as phenolic resin, and its main function is to fix, support, and isolate each conductive sheet 1. Injection molding refers to the process of injecting molten insulating material into a mold cavity containing the conductive components, and then cooling and solidifying it to form an integral structure. The insulating substrate 2 fills the space between the lead-out sections 102 of two adjacent conductive sheets 1 and completely covers the circumferential inner surface of the conductive components. Complete coverage means that when viewed from the internal central axis direction of the commutator, the inner wall surface of the conductive components is completely covered by the insulating substrate 2 material, with no conductive parts exposed, which effectively prevents the risk of internal short circuits. The lead-out section 102 has an exposed section 1023 extending out of the insulating substrate 2. The exposed section 1023 is the part of the lead-out section 102 that is not covered by the insulating substrate 2, and the end of the exposed section 1023 away from the first end 1011 forms a winding welding end 1025. The winding welding end 1025 is a specific area on the exposed section 1023 used to achieve a firm electrical connection with the winding conductor through processes such as spot welding and soldering.

[0037] A groove 201 is formed in the portion of the insulating substrate 2 located between adjacent conductive sheets 1. In this embodiment, the groove 201 is a trench structure on the insulating substrate 2 used to physically separate adjacent conductive sheets 1. The groove 201 is recessed radially toward the central axis of the commutator and extends axially. Radial refers to the direction from the outer surface of the commutator toward the central axis. Specifically, the groove 201 is milled inward (towards the central axis) from the outer peripheral surface of the insulating substrate 2. In the extending direction of the groove 201, the groove 201 extends from the second end 1012 of the brush contact section 101 and beyond the first end 1011 of the brush contact section 101, but does not extend beyond the lead-out section 102. This means that the groove 201 has a certain length in the axial direction. It starts in the area where the second end 1012 of the brush contact section 101 is located, extends towards the first end 1011, and its end exceeds the axial position of the first end 1011, but terminates within the range of the lead-out section 102, without penetrating to the end face of the insulating substrate 2 on the lead-out section 102 side. This non-penetrating blind groove design makes the groove 201 closed at one axial end (near the lead-out section 102 end).

[0038] Through the above structure, the hollow cup motor commutator provided in this embodiment has the following beneficial effects: First, the conductive components adopt an integrated molding design combined with injection molding process, omitting the separate assembly step in the traditional process, thus improving production efficiency and product consistency. Second, the non-through design of the groove 201 reduces excessive subtraction of the insulating substrate 2 structure, helping to maintain the integrity and mechanical strength of the insulating substrate 2. At the same time, since the groove 201 is closed at one end in the axial direction, the risk of adhesive seeping into and clogging the groove 201 during assembly operations such as applying adhesive at the end of the commutator can be reduced, which is beneficial to maintaining the carbon powder drainage function of the groove 201.

[0039] In one embodiment, the insulating substrate 2 forms a bottom surface 202 on the side radially facing the groove 201. The bottom surface 202 refers to the deepest part of the groove 201, i.e., the surface closest to the central axis of the commutator. The bottom surface 202 includes a planar segment 2021 and a curved segment 2022 connected along the extension direction of the groove 201. The curved segment 2022 is formed on the side near the first end 1011 of the brush contact segment 101. Along the direction extending from the second end 1012 to the first end 1011, the groove depth of the groove 201 corresponding to the curved segment 2022 gradually decreases. Here, the groove depth refers to the radial distance from the original outer circular surface of the insulating substrate 2 before the groove 201 is formed to the bottom surface 202 of the groove 201. Specifically, the curved segment 2022 is a smoothly transitioned curved surface, the curvature of which is substantially the same as the diameter of the circular milling cutter used in the milling of the groove 201. This bottom surface 202 structural design allows the groove 201 to smoothly become shallower near the first end 1011, forming a gradual transition area. This design helps optimize the stress distribution in this area, reducing the risk of stress concentration that may be caused by abrupt changes in groove depth, thereby potentially improving the crack resistance and overall durability of the insulating substrate 2 in this critical area.

[0040] In one embodiment, further combination Figure 5 and Figure 6 As shown, the brush contact section 101 has a chamfer 1013 formed on its inner circumferential surface near the first end 1011. The shape of the chamfer 1013 matches the curved surface section 2022. The inner circumferential surface refers to the surface of the brush contact section 101 facing the central axis of the commutator. The chamfer 1013 is a bevel or arc surface formed after removing sharp corners of the material. The chamfer 1013 is associated with the curved surface section 2022 of the groove 201, and its main purpose is to ensure the feasibility of subsequent milling processes. Specifically, during the manufacturing process, the conductive component is first combined with the insulating substrate 2 in the form of an integrally formed annular toothed blank ring (each tooth is connected by an annular connecting strip). After the insulating substrate 2 is formed, the groove 201 needs to be cut out by high-speed precision milling to cut the annular connecting strip, so that each conductive piece 1 is electrically insulated and separated from each other. The shape of the curved surface section 2022 at the bottom of the groove 201 is determined by the tip arc or side shape of the milling cutter. If the conductive sheet 1 does not have a chamfer 1013 at this location, its inner circumferential surface will maintain its full thickness. When milling to the end of the groove 201 (i.e., the curved section 2022), the total amount of insulating and conductive material removed may be insufficient, resulting in the annular connecting strip not being completely cut off, leading to micro-connections. Setting the chamfer 1013 effectively pre-thinns the radial thickness of the conductive sheet 1 in this area. During the milling of the groove 201, the milling cutter, while forming the curved section 2022, ensures that the thinned conductive material, along with the insulating material, is completely cut off, thereby reliably separating each conductive sheet 1.

[0041] In one embodiment, further combination Figure 5 and Figure 6 As shown, the curvature of surface segment 2022 is greater than or equal to 0.125. The curvature of surface segment 2022 is basically consistent with the curvature of the circular end mill used to machine the groove 201. For surface segment 2022, its curvature is directly determined by the geometric parameters of the end mill; specifically, its curvature is equal to the reciprocal of the radius R of the circular end mill, i.e., 1 / R. Designing the curvature of surface segment 2022, or in other words, as an arc surface matching a circular end mill of a specific size, is based on a comprehensive consideration of machining reliability and tool life. Specifically, a larger radius of curvature for surface segment 2022 means that a larger diameter end mill with a thicker shank can be used during machining. This significantly improves the rigidity and strength of the end mill itself, which is beneficial for maintaining stability when milling small-diameter deep grooves at high speeds, reducing tool deflection and vibration, thereby improving the machining accuracy of groove width and depth. Therefore, the curvature of the curved segment 2022 (or the corresponding diameter of the milling cutter) needs to be set within a range of greater than or equal to 0.125 to ensure reliable disconnection of the conductive connection while using a tool with higher strength to guarantee machining quality and efficiency.

[0042] For example, the curvature of surface segment 2022 can be 0.125, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, or a value within the range of any two of the above values.

[0043] In one embodiment, further combination Figure 1 and Figure 2 As shown, the axial dimension of the brush contact section 101 is h1, and the axial dimension of the commutator is h2, satisfying h1 / h2≥0.4. Specifically, in a miniature commutator, the brush contact section 101 needs a sufficient axial length h1 to ensure that the brush has a sufficient and stable contact area. This plays a positive role in maintaining the smoothness of current switching and suppressing commutation sparks. If the ratio of h1 / h2 is too low, it means that the brush contact section 101 is too short and may not meet the above basic electrical performance requirements. Conversely, if the ratio of h1 / h2 is too high, it means that the available space (h2-h1) of the insulating substrate 2 in the axial direction is excessively compressed. The insulation substrate 2's coverage and fixing length for the brush contact section 101 and the lead-out section 102 is insufficient, which may weaken its positioning and support effect. The fixing length of the lead-out section 102 within the insulating substrate 2 may also be limited.

[0044] For example, the value of h1 / h2 can be 0.4, 0.5, 0.6, 0.7, etc., or a value within the range of any two of the above values.

[0045] In one embodiment, such as Figure 2As shown, the circumferential dimension w1 of the lead-out section 102 and the circumferential dimension w2 of the brush contact section 101 satisfy the following condition: 0.3 ≤ w1 / w2 ≤ 0.8. Specifically, when integrally stamping the blank of the conductive component (i.e., the annular toothed structure), the ratio of w1 / w2 directly determines the circumferential gap between two adjacent lead-out section prototypes 102. If the ratio of w1 / w2 is too large, it means that w1 is relatively large, and the material gap between adjacent lead-out sections 102 will be very narrow. The punch thickness required to process this narrow gap will be correspondingly very thin. An excessively thin punch lacks strength during continuous stamping, is prone to breakage or excessive wear, resulting in a short punch life, which not only increases production costs but also affects the dimensional stability and product yield of the stamping process. Conversely, if the ratio of w1 / w2 is too small, it means that the width w1 of the lead-out section 102 itself is too narrow. A narrow lead-out section 102 will cause two problems: First, its cross-sectional area is reduced, which may lead to a decrease in current carrying capacity (overcurrent capacity) and affect motor performance; second, its mechanical strength is weakened, and it is more likely to deform or be damaged in subsequent bending processing, injection molding pressure and motor operation vibration, thus reducing reliability.

[0046] Therefore, by limiting w1 / w2 to an optimized range, it is possible to avoid creating an overly fragile punch structure during the stamping stage while ensuring sufficient current carrying capacity and structural strength of the lead-out section 102. This balances electrical performance, mechanical reliability, mold life, and process feasibility, which is crucial for the stable and efficient production of small-diameter commutators (especially those with an outer diameter of 4.0 mm). For example, in the manufacturing process of a 9-blade φ4.0 commutator, by controlling the ratio of w1 to w2 within a reasonable range, the punch width can be maintained above 0.8 mm while ensuring electrical performance, thus meeting the strength requirements for continuous production.

[0047] For example, the value of w1 / w2 can be 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, etc., or a value within the range of any two of the above values.

[0048] In one embodiment, further combination Figure 1 and Figure 3As shown, the lead-out section 102 includes a first section 1021 and a second section 1022. The first section 1021 is connected to the first end 1011, and the second section 1022 is connected to the first section 1021 via a bend 1024. The first section 1021 and the second section 1022 are arranged at an angle, and the portion of the second section 1022 extending out of the insulating substrate 2 forms an exposed section 1023. The bend 1024 refers to the connection area where the direction changes between the first section 1021 and the second section 1022; it can be a bend or a rounded transition. After being bent by the bending section 1024, an angle is formed between the second segment 1022 and the first segment 1021. This angle causes the second segment 1022 to deflect in the spatial direction relative to the first segment 1021 (and thus relative to the brush contact segment 101). For example, the second segment 1022 can be bent radially outward of the commutator, so that the portion of the second segment 1022 extending out of the insulating substrate 2 forms an exposed segment 1023. The end of the exposed segment 1023 then forms a winding welding end 1025, which is welded to the winding.

[0049] The bending portion 1024 is the area in the lead-out section 102 where stress is concentrated. In some embodiments, the thickness of the bending portion 1024 and / or the thickness of the second section 1022 can be increased. Specifically, within the limits of material availability and space layout, the material distribution in this area can be thickened by adjusting the stamping die. This localized thickening design can effectively improve the structural rigidity of the bending portion 1024, enhance its resistance to bending deformation and fatigue fracture, thereby further improving the reliability of the lead-out section 102 in motor assembly and long-term vibration operation environments. At the same time, increasing the thickness of the second section 1022 also helps to increase the mechanical load-bearing capacity of its end winding welding end 1025, and may improve its flow cross-section to some extent.

[0050] This design provides greater flexibility in the lead-out, arrangement, and soldering of winding wires, making winding connections more convenient and reliable within the extremely compact micro-motor. It also helps reduce the risk of short circuits caused by spatial conflicts at connection points. The option to locally thicken the bend 1024 and the second segment 1022 provides design redundancy to enhance the strength of this area without altering the overall layout.

[0051] In one embodiment, such as Figure 2As shown, the circumferential dimension of the winding welding end 1025 is w3, satisfying: w3 / w1≥1.1. By locally widening the end of the lead-out section 102 to form a wider winding welding end 1025, the contact area between the winding welding end 1025 and the motor winding conductor is increased. A larger contact area helps to reduce the contact resistance and current density at the connection, making it easier to form a strong weld point during the welding process (such as spot welding), and improving the weld point's resistance to vibration and thermal fatigue during long-term operation. For the miniature commutator lead-out section 102, which is already very narrow (e.g., 0.6 mm), widening the end locally (e.g., to 0.8 mm) to form the welding end can effectively solve the problem of unreliable connection caused by the small welding surface, and significantly improve the quality and stability of the electrical connection between the commutator and the winding.

[0052] For example, the value of w3 / w1 can be 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, etc., or a value within the range of any two of the above values.

[0053] In one embodiment, such as Figure 1 and Figure 4 As shown, the insulating substrate 2 includes a lower cylinder 203 and an upper cylinder 204 arranged coaxially. A groove 201 is formed on the outer periphery of the lower cylinder 203, and a bent portion 1024 is embedded and fixed inside the upper cylinder 204. The inner diameter of the upper cylinder 204 is equal to the inner diameter of the lower cylinder 203, and the outer diameter of the upper cylinder 204 is greater than the outer diameter of the lower cylinder 203.

[0054] The groove 201 is mainly formed in the lower cylinder 203, corresponding to the area accommodating the brush contact section 101. The bent portion 1024 is embedded and fixed inside the upper cylinder 204. The upper cylinder 204 completely covers and fixes the bent portion 1024 of the lead-out section 102 and its adjacent first section 1021, providing solid support and protection for the bent structure and preventing it from deforming or loosening due to stress. The equal inner diameters of the upper cylinder 204 and the lower cylinder 203 ensure the continuity of the internal cavity of the insulating substrate 2, facilitating the assembly of the commutator on the motor shaft. The outer diameter of the upper cylinder 204 is larger than that of the lower cylinder 203, making the upper cylinder 204 more prominent in the radial direction. This provides more material thickness for the internally embedded bent portion 1024 and the lead-out section 102, enhancing the fixing strength. On the other hand, the increased outer diameter area can also serve as a reference for the commutator's axial positioning in the motor or as a stop for cooperation with other components, improving assembly accuracy and convenience. The lower cylinder 203 and the upper cylinder 204 can be integrally injection molded, with the difference in inner and outer diameters naturally formed through mold design.

[0055] In one embodiment, further combination Figure 5 and Figure 6As shown, an inner hook structure 1014 is also formed on the inner circumferential surface of the conductive sheet 1 near the second end 1012 of the brush contact section 101. Specifically, the inner hook structure 1014 refers to a feature that protrudes from the inner circumferential surface of the conductive sheet 1 toward the central axis of the commutator. This protrusion can take various forms, such as a partial boss, an axially extending short rib, or a hook with a specific profile. In some preferred embodiments, the protrusion is designed as a wedge or hook shape with inclined sides, that is, the height of the protrusion gradually increases from the body of the conductive sheet 1 toward the second end 1012, forming a "slanted insertion" shape. Molten insulating matrix 2 material flows into and fills the cavity around the inner hook structure 1014. After the insulating material has cured, when the conductive sheet 1 is subjected to axial tensile force (e.g., tension from the winding wire or thermal expansion stress) or circumferential shear force, the inner hook structure 1014 and the insulating material surrounding it will be mechanically interlocked, increasing the resistance to pulling the conductive sheet 1 out of the insulating substrate 2, thereby improving the mechanical bonding force between the conductive sheet 1 and the insulating substrate 2.

[0056] Specifically, in one embodiment of the present invention, the method for preparing the commutator of the hollow cup motor is as follows: Step 1: Integral stamping to form a conductive blank ring Using a precision progressive die, copper alloy strip is formed into a complete annular toothed structure, known as a conductive blank ring, in a single stamping stroke. This conductive blank ring comprises multiple (e.g., nine) circumferentially evenly distributed toothed sections. These toothed sections form the initial shape of the subsequent lead-out section 102 of the individual conductive sheet 1. The toothed sections are connected radially inward by a continuous, complete annular connecting strip. This annular connecting strip is the part that needs to be cut off in the subsequent milling process. During this stamping process, the inner hook structure 1014 on the conductive sheet 1 can also be formed simultaneously, which is used to form a mechanical interlock with the insulating material in subsequent injection molding to enhance the bonding force.

[0057] Step 2: Injection molding of the insulating substrate The conductive blank ring obtained in step one is degreased and cleaned to remove residual oil and impurities from the stamping process, ensuring a clean surface and enabling a strong bond with the insulating substrate 2 material in the subsequent injection molding process. The cleaned conductive blank ring is then positioned in a dedicated injection mold cavity. Molten engineering plastic (e.g., phenolic resin) is then injected into the mold, filling and covering the predetermined area of ​​the conductive blank ring. Specifically, the insulating material fills all gaps between adjacent conductive pieces 1 and completely covers the circumferential inner surface of the conductive blank ring (i.e., the inner wall where the annular connecting strip is located) and the tooth root portion. After the insulating material cures, an insulating substrate 2 is formed, tightly bonded to the conductive blank ring. At this point, although the various toothed portions of the conductive blank ring are fixed by the plastic, they are still electrically and structurally connected to each other through the annular connecting strip that is not filled with plastic.

[0058] Step 3: Milling the groove Before milling the groove, the semi-finished product obtained in step S3 can be heat-treated to eliminate the internal stress generated during the stamping process of the copper conductive blank ring and stabilize its size; and promote the post-curing of the insulating matrix 2 material, improve its cross-linking degree, mechanical strength and dimensional stability, so that the product can better withstand the thermal shock during motor operation.

[0059] Using a high-speed precision milling machine equipped with a circular milling cutter of a specific diameter, milling is performed along a predetermined path distributed circumferentially along the insulating substrate 2. The milling cutter cuts into the commutator from one end (corresponding to the second end 1012 of the brush contact section 101) and advances axially, forming a groove 201. This groove 201 cuts radially inward, with a depth sufficient to completely sever the insulating substrate 2 and the annular connecting strip of the conductive blank ring embedded therein. The groove 201 extends axially, its end extending beyond the connection point (first end 1011) between the brush contact section 101 and the lead-out section 102, but terminating before the area of ​​the lead-out section 102, forming a non-through structure. Through this step, the originally integral conductive blank ring is divided into multiple circumferentially insulated and independent conductive sheets 1. The shape of the curved section 2022 at the bottom of the groove 201 is determined by the arc shape of the milling cutter, ultimately forming the commutator.

[0060] According to an embodiment of the present invention, in another aspect, a coreless motor is also provided, which includes the coreless motor commutator described in any of the foregoing embodiments. Due to the use of the commutator with high consistency, high strength, reliable connection, and optimized groove 201 structure, the coreless motor achieves smoother commutation performance, lower operating noise and sparking, higher mechanical reliability, and longer service life overall. This motor is particularly suitable for applications with stringent requirements for size, precision, and reliability, such as miniature drive units in precision medical devices, robot joints, high-end models, and aerospace equipment.

[0061] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A commutator for a hollow cup motor, characterized in that, include: A conductive component is a coaxial cylindrical structure formed by multiple conductive sheets (1), which are evenly spaced along the circumference. Each conductive sheet (1) includes an integrally formed brush contact section (101) and a lead-out section (102). The brush contact section (101) has a first end (1011) and a second end (1012) that are spaced apart from each other along the axial direction. The lead-out section (102) is connected to the first end (1011) of the brush contact section (101), and the circumferential dimension w1 of the lead-out section (102) is smaller than the circumferential dimension w2 of the brush contact section (101). An insulating substrate (2) is integrally connected to the conductive component by injection molding. It fills the space between the lead-out sections (102) of two adjacent conductive sheets (1) and completely covers the circumferential inner surface of the conductive component. The lead-out section (102) has an exposed section (1023) extending out of the insulating substrate (2). The end of the exposed section (1023) away from the first end (1011) forms a winding welding end (1025). The insulating substrate (2) has a groove (201) between adjacent conductive sheets (1). The groove (201) is recessed radially toward the central axis of the commutator and extends axially. In the extension direction of the groove (201), the groove (201) extends from the second end (1012) of the brush contact section (101) and beyond the first end (1011) of the brush contact section (101), but does not extend beyond the lead-out section (102).

2. The hollow cup motor commutator according to claim 1, characterized in that, The insulating substrate (2) has a bottom surface (202) formed on one side radially toward the groove (201). The bottom surface (202) includes a planar segment (2021) and a curved segment (2022) connected along the extension direction of the groove (201). The curved segment (2022) is formed on one side near the first end (1011) of the brush contact segment (101). Along the direction extending from the second end (1012) to the first end (1011), the groove depth of the groove (201) corresponding to the curved segment (2022) gradually decreases.

3. The hollow cup motor commutator according to claim 2, characterized in that, The brush contact section (101) has a chamfer (1013) formed on the inner circumferential surface near the first end (1011), and the shape of the chamfer (1013) matches the curved surface section (2022).

4. The hollow cup motor commutator according to claim 2, characterized in that, The curvature of the surface segment (2022) is greater than or equal to 0.

125.

5. The hollow cup motor commutator according to any one of claims 1 to 4, characterized in that, The axial dimension of the brush contact section (101) is h1, and the axial dimension of the commutator is h2, satisfying: h1 / h2≥0.

4.

6. The hollow cup motor commutator according to any one of claims 1 to 4, characterized in that, The circumferential dimension w1 of the lead-out section (102) and the circumferential dimension w2 of the brush contact section (101) satisfy the following condition: 0.3≤w1 / w2≤0.

8.

7. The hollow cup motor commutator according to claim 1, characterized in that, The lead-out section (102) includes a first section (1021) and a second section (1022). The second section (1022) is connected to the first section (1021) via a bend (1024). The first section (1021) and the second section (1022) are arranged at an angle. The portion of the second section (1022) extending out of the insulating substrate (2) forms the exposed section (1023).

8. The hollow cup motor commutator according to claim 7, characterized in that, The circumferential dimension of the winding welding end (1025) is w3, which satisfies: w3 / w1≥1.

1.

9. The hollow cup motor commutator according to claim 8, characterized in that, The insulating substrate (2) includes a lower cylinder (203) and an upper cylinder (204) arranged coaxially. The groove (201) is opened on the outer periphery of the lower cylinder (203), and the bent part (1024) is embedded and fixed in the upper cylinder (204). The inner diameter of the upper cylinder (204) is equal to the inner diameter of the lower cylinder (203), and the outer diameter of the upper cylinder (204) is greater than the outer diameter of the lower cylinder (203).

10. A hollow cup motor, characterized in that, Includes the hollow cup motor commutator as described in any one of claims 1 to 9.

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