Frameless torque motor rotor of a Halbach array and assembly method thereof

Abstract

The application discloses a frameless torque motor rotor of a Halbach array and an assembling method, and belongs to the technical field of motors. The rotor comprises an aluminum inner ring with a positioning groove, circumferentially arranged magnetic steels, a jointing adhesive, and an outer carbon fiber winding layer. The number of the magnetic steels is 4n to form n pole pairs. The magnetic steels are continuously and gradually arranged in a 45-degree oblique magnetization mode (↗↘↖↗). Adjacent equivalent N poles and equivalent S poles are formed by four magnetic steels, and one pole pair is formed by four magnetic steels. The aluminum inner ring, the adhesive, and the carbon fiber layer are cooperatively fixed to replace a traditional rotor tooth structure, thereby effectively reducing the rotational inertia. In combination with the above array, the air gap magnetic density and the torque density are significantly improved, and the frameless torque motor rotor is suitable for lightweight robot joints.

Description

Technical Field

[0001] This invention belongs to the field of frameless torque motor technology, specifically a frameless torque motor rotor of a Heilbeck array and its assembly method. Background Technology

[0002] A frameless torque motor is a precision drive device that removes the motor housing, bearings, and output shaft of a traditional motor, retaining only the stator (ring coil) and rotor (a ring-shaped rotating body with permanent magnets). Its basic design concept is to directly embed the motor into the mechanical structure of the equipment itself, with the equipment's own bearings and housing providing support and positioning, thereby achieving the core goals of high torque density, zero backlash, and compact lightweight design. The rotor of a frameless torque motor typically consists of permanent magnets and a support structure. The rotor is directly and rigidly connected to the load, eliminating intermediate transmission components such as gears and belts, thus avoiding transmission losses and precision degradation.

[0003] Currently, the magnet arrangement of frameless torque motor rotors mostly adopts the traditional surface-mounted (SPM) structure, where permanent magnets are attached to the outer surface of the rotor core or supporting frame. For example, Chinese patent application CN120979051A discloses a stator and rotor lamination and magnet for a frameless torque motor, in which the rotor lamination is configured as a surface-mounted rotor, and the magnet is tile-shaped and embedded in the middle of the boss on the outer circle of the rotor lamination. Another example is Chinese patent application 202511376341.3, which discloses a stator and rotor lamination and magnet for a concentrated winding frameless torque motor, also employing a surface-mounted rotor structure, with the magnet embedded between two bosses on the outer edge of the rotor. In addition, Chinese invention patent with authorization announcement number CN100568668C discloses a rotor of a brushless DC motor, including a frame, multiple rotor teeth and multiple magnets fixed between the rotor teeth. The magnets are arranged in the radial direction with their sides facing each other and having the same polarity. The magnets are fixed by the cooperation of the protrusion and the hook-shaped groove and the stop protrusion.

[0004] However, the existing technology can be further explored and improved in the following aspects: (1) In the traditional surface-mounted magnet arrangement, the magnetic flux distribution on the air gap side is not concentrated enough, and there is a large leakage magnetic flux on the back iron side, which limits the further improvement of the air gap magnetic flux density. (2) The magnet fixing structure of the existing rotor is relatively complex. For example, CN100568668C requires multiple rotor teeth, hooks, hook-shaped slots and stop protrusions, etc., which increases the rotational inertia and axial dimension of the rotor, which is not conducive to the thinning and lightweight requirements of frameless torque motors. (3) When the existing surface-mounted rotor rotates at high speed, the magnets bear a large centrifugal force, which poses a risk of magnet detachment. The traditional sheathing scheme (such as stainless steel sheath) will increase the weight and inertia of the rotor. Therefore, it is meaningful and challenging to develop a new rotor structure and its assembly method that can achieve magnetic field directional enhancement, structural simplification and reliable magnet fixing in the rotor of frameless torque motor. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a frameless torque motor rotor with a Hellbeck array and its assembly method. The invention aims to combine the Hellbeck array magnets with the frameless and rotor toothless structure of the frameless torque motor, using an aluminum inner ring as a support frame, and achieving reliable fixing of the magnets through positioning grooves, gap filling, and carbon fiber winding. This significantly improves the air gap magnetic flux density and torque density while reducing rotor rotational inertia and simplifying the structure.

[0006] To achieve the above objectives, the present invention provides a frameless torque motor rotor with a Hale-Becker array, comprising: an annular aluminum inner ring; 4n magnets arranged circumferentially along the aluminum inner ring, wherein the magnets are arranged in a Hale-Becker array, and the magnetization direction of each magnet is a 45° oblique magnetization direction distributed along the annular circumference, forming a continuous gradual magnetization in the directions of upper right (↗), lower right (↘), upper left (↖), and upper right (↗); wherein adjacent magnets magnetized in the upper right (↗) direction and magnets magnetized in the lower right (↘) direction are equivalent to a N pole, and adjacent magnets magnetized in the upper left (↖) direction and magnets magnetized in the upper right (↗) direction are equivalent to a S pole. The magnetic field components of the equivalent N pole and the equivalent S pole on the air gap side are superimposed, while the magnetic field components on the back iron side are canceled out. The inner end face of the magnet is in contact with the outer peripheral surface of the aluminum inner ring, and a circumferential gap is formed between adjacent magnets. An adhesive is filled in the circumferential gap between adjacent magnets, and the adhesive simultaneously bonds the side surfaces of adjacent magnets and the interface between the inner end face of the magnet and the outer peripheral surface of the aluminum inner ring. A carbon fiber winding layer is wound radially outward on the plurality of magnets, and the carbon fiber winding layer applies a radially inward preload to the plurality of magnets, so that the inner end face of the magnet and the outer peripheral surface of the aluminum inner ring and the adjacent magnets are kept in close contact.

[0007] Preferably, n is a positive integer, and the number of pole pairs is n. In the Heilbeck array, the magnets with different oblique magnetization directions are arranged sequentially along the circumference, and every two adjacent obliquely magnetized magnets are equivalent to a magnetic pole. Specifically, adjacent magnets magnetized in the upper right (↗) direction and magnets magnetized in the lower right (↘) direction form an N pole, and adjacent magnets magnetized in the upper left (↖) direction and magnets magnetized in the upper right (↗) direction form an S pole. Every two pairs of adjacent magnets with equivalent N poles and every two pairs of adjacent magnets with equivalent S poles, a total of four magnets, form a complete pole pair. Therefore, the number of magnets is 4n, forming n pole pairs. More preferably, the number of magnets is 52, forming 13 pole pairs (i.e., 26 magnetic poles).

[0008] Preferably, the outer circumferential surface of the aluminum inner ring is provided with a plurality of positioning grooves, the number of positioning grooves being the same as the number of magnets, and each positioning groove being used to accommodate the inner end of a magnet, so as to realize the circumferential positioning of the magnet and prevent the magnet from slipping in the circumferential direction.

[0009] Preferably, the magnet is tile-shaped in a cross section perpendicular to the axial direction, and the outer arc surface and inner arc surface of the tile-shaped magnet are arranged concentrically, with the circumferential gap between adjacent tile-shaped magnets maintaining the same width in the radial direction.

[0010] Preferably, the carbon fiber winding layer is a Bohr carbon fiber winding layer, which is formed by winding carbon fiber bundles in a circumferential direction, with 2 to 8 winding layers, and the fiber orientation between adjacent fiber layers is arranged in a cross pattern, and the radial thickness of the carbon fiber winding layer is 0.5 mm to 3.0 mm.

[0011] Preferably, the adhesive is an epoxy resin structural adhesive, which, after curing, forms an adhesive layer between adjacent magnets and between the magnet and the aluminum inner ring, and the shear strength of the adhesive layer is not less than 25 MPa.

[0012] Preferably, the center of the aluminum inner ring is provided with a hollow through hole extending along the axial direction, and the diameter of the hollow through hole is 60% to 80% of the outer diameter of the aluminum inner ring.

[0013] Preferably, the Heilbeck array makes the air gap magnetic flux density at the outer surface of the rotor sinusoidally distributed along the circumference, and the difference between the average magnetic induction intensity of the N pole and the S pole does not exceed 5%.

[0014] This invention also provides a method for assembling a frameless torque motor rotor of a Heilbeck array, comprising the following steps: S1: Provide an annular aluminum inner ring, wherein a plurality of positioning grooves are provided on the outer circumferential surface of the aluminum inner ring, and the number of positioning grooves is consistent with the number of magnets to be arranged. S2: Multiple magnets are embedded into the positioning slots one-to-one according to the Hellbeck array, so that the inner end face of each magnet is in contact with the bottom surface of the positioning slot, and a circumferential gap is formed between adjacent magnets. In the Hellbeck array, the magnetization direction of each magnet is a 45° oblique magnetization direction distributed along the annular circumference, that is, one magnetizes in the upper right ↗ direction, the next magnetizes in the lower right ↘ direction, the next magnetizes in the upper left ↖ direction, and the next magnetizes in the upper right ↗ direction, forming a continuous gradual magnetization; and adjacent magnets magnetized in the upper right ↗ direction and the lower right ↘ direction are equivalent to a N pole, and adjacent magnets magnetized in the upper left ↖ direction and the upper right ↗ direction are equivalent to a S pole. S3: Fill the circumferential gap between adjacent magnets with adhesive, which simultaneously wets the side surface of the magnet and the interface between the inner end face of the magnet and the bottom surface of the positioning groove. S4: Wind carbon fiber bundles around the radial outer side of the plurality of magnets. During winding, apply a circumferential tension of 50N to 200N to form a carbon fiber winding layer. The carbon fiber winding layer applies a radial inward preload to the magnets, so that the inner end face of the magnets is tightly attached to the bottom surface of the positioning groove. S5: Curing the adhesive and the resin matrix in the carbon fiber winding layer at a temperature of 60°C to 100°C for 2 to 6 hours, so that the magnet, aluminum inner ring and carbon fiber winding layer are cured into an integrated structure.

[0015] Beneficial technical effects of the present invention: This invention combines Helbeck array magnets with the frameless, rotorless gearless structure of a frameless torque motor, and achieves the following beneficial technical effects through quadruple fixation: aluminum inner ring, positioning groove positioning, gap filling adhesive, and carbon fiber winding. (1) This invention uses a Halebeck array to arrange the magnets. Utilizing the self-shielding effect of the magnetic field of the Halebeck array, the horizontal components of the magnetic field of adjacent magnets are superimposed, significantly increasing the magnetic flux density on the air gap side, while the vertical components cancel each other out, resulting in a significant attenuation of the magnetic field on the back iron side. Measured data show that the Halebeck array rotor with 52 magnets and 13 pole pairs (i.e., 26 magnetic poles) exhibits 13 complete sinusoidal cycles in the air gap magnetic field waveform along the 360-degree circumference. The waveform is smooth and continuous, indicating a reasonable magnetic circuit design and excellent sinusoidal distribution characteristics of the air gap magnetic field. This is crucial for reducing the cogging torque and torque pulsation of the motor. The average magnetic induction intensity of the N pole reaches 606.45 mT, and the average value of the S pole reaches 595.67 mT. The combined average value is approximately 601.06 mT. The errors of the N and S poles are only about 1.15% and 1.02%, respectively, indicating excellent consistency in magnetization and assembly of the magnets under the Halebeck array, and uniform magnetic field strength. The average zero-crossing intervals of the N and S poles are 13.77 degrees and 13.92 degrees, respectively, which perfectly match the theoretical interval of 26 magnetic poles (i.e., 13 pole pairs) (360°÷26≈13.846°), with an error of only about 1.4%, proving the extremely high positioning accuracy of the multi-magnet arrangement.

[0016] (2) This invention uses an aluminum inner ring as the supporting frame for the magnets, replacing the complex multi-part structure of rotor teeth, frame, protrusions, hook-shaped grooves, and stop protrusions in the traditional solution. The aluminum inner ring has a low density (approximately 2.7 g / cm³). 3 With its advantages of good machinability, its ring structure not only provides a precise positioning reference for the magnet, but also provides a through channel for cables, optical paths, air paths and so on through its large-size hollow design (the hollow diameter can reach 60% to 80% of the outer diameter), which significantly improves the integration of mechanical design.

[0017] (3) This invention employs a multi-layered fixing method for magnets, combining positioning groove positioning, gap filling with adhesive, and carbon fiber winding. The positioning groove achieves initial precise positioning of the magnet and prevents circumferential slippage. The epoxy resin adhesive forms a high-strength adhesive layer (shear strength not less than 25MPa) between the magnet and the aluminum inner ring, as well as between adjacent magnets. The carbon fiber winding layer applies a uniform pre-tightening force (winding tension 50N to 200N) to the magnet in the radial direction, ensuring a tight fit between the inner end face of the magnet and the bottom surface of the positioning groove. This triple fixing method effectively prevents the magnet from falling off or shifting due to centrifugal force during high-speed rotation. Simultaneously, the low density of the Poiseu carbon fiber winding layer (approximately 1.8g / cm³) further enhances its effectiveness. 3 It has high specific strength and provides reliable radial constraint without significantly increasing the moment of inertia.

[0018] (4) The assembly method provided by this invention is simple in process and highly operable. It ensures the arrangement accuracy of the Heilbeck array through positioning grooves, achieves the integrated molding and pre-tightening of the carbon fiber winding layer through high-tension circumferential winding, and achieves the integrated shaping of the overall structure through heating and curing, making it suitable for mass production. Measured data show that the N pole area and S pole area reach 70216.5 and 69861.0 mT·Deg, respectively, and the total magnetic flux area reaches 140077.4 mT·Deg, demonstrating the substantial and outstanding effect of the technical solution of this invention in improving the rotor torque density and running stability of the frameless torque motor. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the frameless torque motor rotor of the Heilbeck array of the present invention; Figure 2 This is a MAGTEC magnetic field test diagram of the rotor of the present invention in a 360-degree circumferential direction, where the left side is the air gap magnetic field waveform curve and the right side is the magnetic performance parameter data table. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort should be within the scope of protection of this application.

[0021] It should be noted that the term "comprising" in the specification and claims of this application is intended to cover a non-exclusive inclusion. For example, a method comprising a series of steps is not necessarily limited to those explicitly listed, but may include other steps not explicitly listed or inherent to these methods. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. The present application will now be described in detail with reference to embodiments.

[0022] Unless otherwise specified, all materials and reagents used in the following embodiments and comparative examples of this invention are commercially available. The aluminum inner ring is made of 6061-T6 aluminum alloy by machining, with a density of 2.7 g / cm³. 3The yield strength is ≥240MPa. The magnets are made of sintered neodymium iron boron (NdFeB) permanent magnet material, grade N52, with remanence Br≥1.44T, intrinsic coercivity Hcj≥876kA / m, and a maximum operating temperature of 80℃. The carbon fibers are made of polyacrylonitrile (PAN) based carbon fiber tow, with a single filament diameter of 7μm, tensile strength ≥3500MPa, elastic modulus ≥230GPa, and density of 1.8g / cm³. 3 The epoxy resin adhesive is a two-component epoxy structural adhesive with a pot life of 60 minutes after mixing. After curing, the shear strength is ≥25MPa, and the working temperature range is -40℃ to 120℃.

[0023] Example 1

[0024] This embodiment provides a frameless torque motor rotor with a Heilbeck array, comprising: an annular aluminum inner ring; 52 magnets arranged circumferentially along the aluminum inner ring, the 52 magnets being arranged in a Heilbeck array, here having 13 pole pairs (i.e., 26 magnetic poles); epoxy resin adhesive filling the gaps between adjacent magnets; and a 4-layer Poiseuille carbon fiber winding layer wound radially outward of the 52 magnets.

[0025] like Figure 1 As shown, the outer diameter of the aluminum inner ring is 180 mm, the diameter of the hollow through hole is 120 mm (i.e., the diameter of the hollow through hole is 66.7% of the outer diameter of the aluminum inner ring), and the axial thickness is 15 mm. Fifty-two positioning grooves are evenly distributed on the outer circumferential surface of the aluminum inner ring. The circumferential width of the positioning grooves is 8.2 mm, and the depth is 1.5 mm. These grooves are used to precisely position the 52 magnets during assembly and prevent them from slipping in the circumferential direction.

[0026] The magnets are tile-shaped, with the radius of curvature of their inner arc surface matching that of the outer circumference of the aluminum inner ring (R=90mm), and the radius of curvature of their outer arc surface being R=93.5mm. The radial thickness is 3.5mm, the axial width is 15mm, and the circumferential arc length is 8.0mm (measured from the inner arc surface). Each tile-shaped magnet has rounded corners on all four sides with a radius of 0.5mm to avoid stress concentration. The 52 magnets are arranged in a Hellbeck array, meaning the magnetization direction of each tile-shaped magnet is a 45° oblique magnetization direction distributed along the annular circumference, sequentially forming a continuous, gradual magnetization from right-upper right (↗), right-lower right (↘), left-upper left (↖), and right-upper right (↗). Specifically, adjacent magnets magnetized in the upper right (↗) direction and magnets magnetized in the lower right (↘) direction are equivalent to one N pole, and adjacent magnets magnetized in the upper left (↖) direction and magnets magnetized in the upper right (↗) direction are equivalent to one S pole. Each pair of two equivalent N poles and each pair of two equivalent S poles, totaling four tile-shaped magnets, constitutes a complete pole pair. Therefore, 52 tile-shaped magnets form 13 pole pairs (i.e., 26 magnetic poles). After the tile-shaped magnets are embedded in the positioning groove, the circumferential gap between adjacent magnets remains equal in the radial direction, with a gap width of 0.3 mm.

[0027] Epoxy resin adhesive fills the circumferential gap between adjacent magnets, while also wetting the sides of the magnets and the interface between the inner end face of the magnet and the bottom surface of the positioning groove. After curing, the epoxy resin adhesive forms an adhesive layer between adjacent magnets and between the magnet and the aluminum inner ring, with a shear strength of 27.5 MPa.

[0028] The Bosch carbon fiber winding layer is formed by circumferentially winding carbon fiber bundles, with a total of [number] layers. The first layer is wound clockwise, and the second layer is wound counterclockwise. The fibers in adjacent layers are arranged in a cross-directional pattern at a 50° angle. The total radial thickness of the carbon fiber winding layer is 1.2 mm. The carbon fiber winding layer applies a radially inward preload to the 52 magnets, ensuring a tight fit between the inner end faces of the magnets and the bottom surface of the positioning grooves, and maintaining close contact between adjacent magnets.

[0029] In this embodiment, the magnets are pre-magnetized before assembly. A non-magnetic clamp is used to assist in positioning during embedding into the positioning slot, preventing misalignment due to mutual attraction or repulsion. Simultaneously, a thermally conductive silicone rubber buffer layer with a thickness of approximately 0.15 mm is coated between the outer circumference of the aluminum inner ring and the inner end face of the magnet to compensate for stress caused by the difference in thermal expansion coefficients between aluminum and carbon fiber.

[0030] This embodiment also provides a method for assembling the frameless torque motor rotor of the Heilbeck array, including the following steps: S1: Provides an annular aluminum inner ring. The annular aluminum inner ring is machined from 6061-T6 aluminum alloy bar, with an outer diameter of 180mm, a hollow through-hole diameter of 120mm, and an axial thickness of 15mm. Fifty-two locating grooves are evenly milled onto the outer circumference of the aluminum inner ring, with a circumferential width of 8.2mm and a depth of 1.5mm.

[0031] S2: Embed 52 tile-shaped magnets one-to-one into the positioning slots according to the Hellbeck array, so that the inner end face of each tile-shaped magnet is in contact with the bottom surface of the positioning slot, and a circumferential gap (0.3mm) is formed between adjacent tile-shaped magnets. In the Hellbeck array, the magnetization direction of each magnet is a 45° oblique magnetization direction distributed along the annular circumference, that is, one magnetizes in the upper right ↗ direction, the next magnetizes in the lower right ↘ direction, the next magnetizes in the upper left ↖ direction, and the next magnetizes in the upper right ↗ direction, forming a continuous gradual magnetization; and adjacent magnets magnetized in the upper right ↗ direction and the lower right ↘ direction are equivalent to a N pole, and adjacent magnets magnetized in the upper left ↖ direction and the upper right ↗ direction are equivalent to a S pole.

[0032] S3: Fill the circumferential gaps between adjacent tile-shaped magnets with epoxy resin adhesive. Using a dispensing gun, inject the two-component epoxy structural adhesive into the gaps between adjacent magnets at a pressure of 0.3 MPa, ensuring the adhesive fills all gaps and fully wets the sides of the magnets and the interface between the inner end face of the magnet and the bottom surface of the positioning groove. After dispensing, allow the adhesive to stand at room temperature for 30 minutes to allow it to initially level and remove air bubbles.

[0033] S4: A tow of Poiseuille carbon fiber is wound radially around the outer side of the 52 tile-shaped magnets to form a carbon fiber winding layer. A circumferential winding method is used, with a circumferential tension of 120N applied during winding. The winding sequence is as follows: the first layer is wound clockwise, the second layer counterclockwise, the third layer clockwise, and the fourth layer counterclockwise, with a fiber orientation crossing angle of 50° between adjacent fiber layers. The total number of winding layers is 4, and the total radial thickness of the carbon fiber winding layer is 1.2mm. The carbon fiber winding layer applies a radially inward preload to the magnets, ensuring a tight fit between the inner end face of the magnet and the bottom surface of the positioning groove.

[0034] S5: Curing the epoxy resin adhesive and the resin matrix in the carbon fiber winding layer. The completed rotor is placed in a constant temperature oven and cured at 80°C for 4 hours to fully cure the epoxy resin adhesive and simultaneously cure and set the epoxy resin matrix of the carbon fiber winding layer. After curing, it is naturally cooled to room temperature (cooling rate not exceeding 2°C / min to prevent structural deformation caused by thermal stress), thus obtaining the finished frameless torque motor rotor of the Heilbeck array.

[0035] Example 2

[0036] This embodiment provides a frameless torque motor rotor with a Heilbeck array. Except for the following differences, the rest of the structure is the same as in Embodiment 1: The device contains 48 magnets, forming 12 pole pairs (i.e., 24 magnetic poles). The outer diameter of the aluminum inner ring is 160 mm, the diameter of the hollow through-hole is 100 mm (62.5% of the outer diameter), and the axial thickness is 12 mm. Forty-eight positioning grooves are evenly distributed on the outer circumference of the aluminum inner ring.

[0037] The carbon fiber winding layer has 3 winding layers (the first layer is clockwise, the second layer is counterclockwise, and the third layer is clockwise), the winding tension is 100N, and the total radial thickness of the carbon fiber winding layer is 0.9mm.

[0038] The curing temperature of the epoxy resin adhesive is 70℃, and the curing time is 5 hours.

[0039] The assembly method in this embodiment is basically the same as that in embodiment 1, except that the number of magnets, the number of positioning slots, and the corresponding adjustments to the process parameters are all different.

[0040] Example 3

[0041] This embodiment provides a frameless torque motor rotor with a Heilbeck array. Except for the following differences, the rest of the structure is the same as in Embodiment 1: The magnet is rectangular, with a radial length of 30mm, a circumferential width of 8mm, and an axial thickness of 15mm. The outer circumferential surface of the aluminum inner ring 1 is a smooth cylindrical surface without positioning grooves. Instead, a special positioning fixture is used to precisely position the magnet during assembly.

[0042] The carbon fiber winding layer has 6 winding layers, a winding tension of 150N, and a total radial thickness of 1.8mm.

[0043] The curing temperature of the epoxy resin adhesive is 90℃, and the curing time is 3 hours.

[0044] The assembly method in this embodiment is basically the same as that in embodiment 1, except that in step S2, a special positioning fixture is used to arrange 48 rectangular magnets in a Hellbeck array on the outer circumference of the aluminum inner ring, and the positioning fixture is removed after the adhesive has initially cured.

[0045] Example 4

[0046] This embodiment provides a frameless torque motor rotor with a Heilbeck array. Except for the following differences, the rest of the structure is the same as in Embodiment 1: The device contains 60 magnets, forming 15 pole pairs (30 magnetic poles). The outer diameter of the aluminum inner ring is 200 mm, the diameter of the hollow through-hole is 160 mm (80% of the outer diameter), and the axial thickness is 18 mm. Sixty positioning grooves are evenly distributed on the outer circumference of the aluminum inner ring.

[0047] The carbon fiber winding layer has 5 winding layers, a winding tension of 180N, and a total radial thickness of 1.5mm.

[0048] The curing temperature of the epoxy resin adhesive is 100℃, and the curing time is 2 hours.

[0049] The assembly method in this embodiment is basically the same as that in embodiment 1, except that the number of magnets, the number of positioning slots, and the corresponding adjustments to the process parameters are all different.

[0050] Comparative Example 1 Except for the following differences, the remaining steps are the same as in Example 1: This comparative example does not include a carbon fiber winding layer. After step S3 (gap filling), the carbon fiber winding in step S4 is not performed. Instead, the filled rotor is directly placed in a constant temperature oven and cured at 80°C for 4 hours to obtain a comparative rotor product with the magnets fixed only by epoxy resin adhesive.

[0051] Comparative Example 2 Except for the following differences, the remaining steps are the same as in Example 1: The magnets in this comparative example are not arranged in a Hellbeck array, but rather in a traditional surface-mount arrangement. All 52 magnets are magnetized radially, with their N and S poles alternating circumferentially. The shape, size (tile-shaped), and number (52) of the magnets are the same as in Example 1. No positioning grooves are provided on the outer circumference of the aluminum inner ring 1; the magnets are arranged and positioned using a dedicated positioning fixture.

[0052] Comparative Example 3 Except for the following differences, the remaining steps are the same as in Example 1: The magnets in this comparative example are fixed using the fixing method described in Chinese Invention Patent No. CN100568668C, which involves setting 26 trapezoidal rotor teeth (instead of positioning grooves). The rotor teeth are connected to the outer circumference of the aluminum inner ring at regular intervals in the radial direction. A hook is formed on the inner top surface of each rotor tooth, and a hook-shaped groove is correspondingly provided on the outer surface of the aluminum inner ring. First and second stop protrusions are formed on the inner and outer parts of the rotor teeth to prevent the magnets from separating. 52 magnets are fixed between the 26 rotor teeth, and the facing sides of the magnets have the same polarity (instead of a Hellbeck array). The remaining number of magnets, the number of pole pairs (26 poles), and the magnet material are the same as in Example 1.

[0053] Comparative Example 4 Except for the following differences, the remaining steps are the same as in Example 1: In this comparative example, the outer protective layer of the magnet uses a 304 stainless steel sheath instead of a carbon fiber winding layer. The 304 stainless steel sheath is 1.0 mm thick, and its inner diameter matches the outer diameter of the magnet's outer arc surface. It is fitted onto the radial outer side of the magnet using a thermoforming method. The number of the remaining magnets (52) and their arrangement (Haelbeck array) are the same as in Example 1.

[0054] Test case To verify the rotor performance of different embodiments and comparative examples of the present invention, the following test methods were used to compare and evaluate each rotor sample.

[0055] Test samples: Three rotor samples (n=3) were prepared according to the methods of Examples 1-4 and Comparative Examples 1-4 respectively. The hollow through holes in the aluminum inner rings of all samples were fitted with the same model of test shaft. The stator was a frameless torque motor stator of the same specification (the single-sided working air gap between the inner diameter of the stator and the outer surface of the rotor was 0.5mm).

[0056] Test method: (1) Moment of inertia test: In accordance with the relevant provisions of GB / T2900.25-2008 "Electrical Engineering Terminology: Rotating Electrical Machines", the moment of inertia of each rotor sample was measured using the three-wire pendulum method. The testing instrument was a three-wire pendulum moment of inertia tester with a measurement accuracy of ±0.5%. Each sample was measured 3 times and the average value was taken.

[0057] (2) Air gap magnetic flux density test: The magnetic flux density on the outer surface (i.e., the air gap side) of each rotor sample was measured using the MAGTEC magnetic field testing system. During the test, the rotor sample was fixed on a precision rotating stage, and the magnetic field probe was fixed on a fine-tuning bracket. The sensitive point of the probe was 0.5 mm away from the outer surface of the rotor (i.e., the working air gap distance). The magnetic flux density values ​​at 360 points along the rotor circumference at intervals of 1° / step were measured, and the peak magnetic flux density B_peak(T) was recorded and the average value B_avg(T) was calculated. Each sample was measured once at three different axial positions along the circumference, and the average value of the three measurements was taken as the final result for that sample. The test environment temperature was 25℃±2℃.

[0058] like Figure 2As shown, the MAGTEC magnetic field test results of the rotor in Embodiment 1 of the present invention in a 360-degree circumferential direction show that the air gap magnetic field waveform exhibits 13 complete sinusoidal cycles within the mechanical angle range of 0 to 360 degrees. The waveform is smooth and continuous, indicating that the magnetic circuit design is reasonable and the air gap magnetic field has excellent sinusoidal distribution characteristics. The average magnetic induction intensity of the N pole reaches 606.45 mT, and the average value of the S pole reaches 595.67 mT, with a combined average of approximately 601.06 mT. The errors of the N pole and the S pole are only about 1.15% and 1.02%, respectively, indicating that the magnetization and assembly consistency of the magnets under the Hellbeck array is excellent. The average zero-crossing point intervals of the N pole and the S pole are 13.77 degrees and 13.92 degrees, respectively, which perfectly match the theoretical interval of 26 magnetic poles (i.e., 13 pole pairs) (360° ÷ 26 ≈ 13.846°), with an error of only about 1.4%. The N-pole area and S-pole area reach 70216.5 and 69861.0 mT·Deg, respectively, and the total magnetic flux area reaches 140077.4 mT·Deg.

[0059] (3) Centrifugal Force Endurance Test: Each rotor sample was mounted on a high-speed rotating test bench and gradually accelerated from 0 rpm to 1.2 times the rated speed (i.e., 120% of the rated speed) at an acceleration of 500 rpm / s. The rotor was maintained at 120% of the rated speed for 30 minutes, and then decelerated to 0 rpm. After the operation, the internal structure of the rotor was non-destructively inspected using industrial CT to check for any magnet detachment, displacement, or cracking. Rating criteria: Grade A - No magnet detachment, displacement, or cracking; Grade B - No detachment but slight displacement or local micro-cracks; Grade C - Magnet detachment or significant displacement.

[0060] (4) Torque density test: Each rotor sample was assembled with a stator of the same specification to form a complete frameless torque motor. The output torque of each motor sample under rated current conditions was measured using a dynamometer. The torque density was calculated using the following formula: Torque density = Output torque (Nm) / Rotor mass (kg). The rotor mass was weighed using an electronic balance.

[0061] Test results: The test results for each test item are shown in Table 1.

[0062] Table 1. Rotor performance test results of each embodiment and comparative example.

[0063] *Note: In Comparative Example 1, the magnet fell off during the 120% rated speed holding phase of the centrifugal force endurance test, the test was terminated, and the torque density test could not be performed.

[0064] Test Result Analysis: (1) In terms of the moment of inertia, the moment of inertia of Embodiments 1-4 of the present invention is 0.65 kg·mm. 2 -1.02kg·mm 2 It was significantly lower than that of Comparative Example 3 (1.56 kg·mm²). 2 ) and Comparative Example 4 (1.34 kg·mm 2 The rotational inertia was reduced by approximately 52%-65% and 24%-51%, respectively. Among them, Example 2 had the lowest moment of inertia (0.65 kg·mm²). 2 The moment of inertia of Comparative Example 3 was only 41.7% of that of Comparative Example 4. Comparative Example 3, due to the use of multiple additional parts such as traditional rotor teeth, hooks, hook-shaped grooves, and stop protrusions, had the largest moment of inertia. This demonstrates that the present invention effectively reduces the moment of inertia of the rotor by eliminating additional parts such as rotor teeth and using a lightweight aluminum inner ring and carbon fiber winding layer. Comparative Example 4, due to the use of a 304 stainless steel sheath (density approximately 7.9 g / cm³),... 3 Its moment of inertia is significantly higher than that of Examples 1-4, indicating that carbon fiber materials have significant advantages in lightweighting.

[0065] (2) From the perspective of air gap magnetic flux density, the peak air gap magnetic flux density of Examples 1-4 of the present invention reaches 0.93T-0.96T, and the average magnetic flux density reaches 0.70T-0.73T, which is significantly higher than that of Comparative Example 2 (peak magnetic flux density 0.72T, average magnetic flux density 0.54T) and Comparative Example 3 (peak magnetic flux density 0.73T, average magnetic flux density 0.55T). Example 4 has the highest peak magnetic flux density (0.96T), which is because Example 4 has the largest number of magnets (60) and 15 pole pairs (i.e., 30 magnetic poles), making the magnetic field enhancement effect of the Hellbeck array more significant. The peak magnetic flux density of Examples 1-4 of the present invention is 29%-33% higher than that of Comparative Example 2, and the average magnetic flux density is 30%-35% higher. This indicates that the Hellbeck array, through the magnetic field self-shielding effect, enables the horizontal component magnetic fields to superimpose and significantly improves the magnetic flux density on the air gap side.

[0066] (3) Based on the centrifugal force tolerance test results, Examples 1-4 all achieved a Grade A rating. Comparative Example 1 (without carbon fiber winding layer) was rated Grade C, and the magnet detached after running at 120% rated speed for about 12 minutes, indicating that epoxy resin adhesive alone cannot reliably fix the magnet under the high centrifugal force generated by high-speed rotation. Comparative Examples 2-4 all achieved a Grade A rating, indicating that they can all meet the requirements of high-speed rotation as long as there is sufficient fixing strength.

[0067] (4) In terms of torque density, the torque densities of Examples 1-4 of the present invention reach 4.78 Nm / kg-4.92 Nm / kg, which are significantly higher than those of Comparative Example 2 (3.65 Nm / kg), Comparative Example 3 (2.84 Nm / kg), and Comparative Example 4 (3.12 Nm / kg). Among them, Example 2 has the highest torque density (4.92 Nm / kg), which is because Example 2 achieves a high air gap magnetic flux density with a smaller rotor outer diameter, while having the smallest rotor mass. Comparative Example 3 has the lowest torque density (2.84 Nm / kg), with the largest moment of inertia and the lowest air gap magnetic flux density, which fully demonstrates the comprehensive advantages of the present invention in both simplifying the structure (lightweighting) and improving magnetic flux density. The torque density of Comparative Example 4 is significantly lower than that of Examples 1-4, indicating that the advantage of the carbon fiber winding layer over the stainless steel sheath in terms of lightweighting is directly converted into an increase in torque density. The torque density of Examples 1-4 was increased by 30%-35% compared to Comparative Example 2, by 68%-73% compared to Comparative Example 3, and by 53%-58% compared to Comparative Example 4.

[0068] In summary, this invention combines the Hellbeck array magnets with the frameless structure of a frameless torque motor, and employs a quadruple fixing scheme of "aluminum inner ring + positioning groove positioning + gap filling + carbon fiber winding." This achieves significant and stable technical results in reducing rotor moment of inertia, increasing air gap magnetic flux density, and improving torque density. MAGTEC magnetic field test data further confirms that the Hellbeck array rotor, using 52 magnets and 13 pole pairs (i.e., 26 magnetic poles), exhibits a perfect sinusoidal distribution in its air gap magnetic field waveform, with excellent magnetic induction intensity consistency (N / S pole error of only about 1%) and extremely high pole pitch accuracy (error of only about 1.4%). This fully verifies the effectiveness of this technical solution in improving the rotor torque density and operational stability of the frameless torque motor.

[0069] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A frameless torque motor rotor with a Heilbeck array, characterized in that, include: An inner ring of aluminum; 4n magnets are arranged circumferentially along the inner aluminum ring. The magnets are arranged in a Halebeck array, in which the magnetization direction of each magnet is a 45° oblique magnetization direction distributed along the annular circumference, forming a continuous gradual magnetization in the direction of upper right ↗, lower right ↘, upper left ↖, and upper right ↗. Adjacent magnets magnetized in the direction of upper right ↗ and lower right ↘ are equivalent to a single N pole, and adjacent magnets magnetized in the direction of upper left ↖ and upper right ↗ are equivalent to a single S pole. The magnetic field components of the equivalent N pole and the equivalent S pole on the air gap side are superimposed, and the magnetic field components on the back iron side are canceled out. The inner end face of the magnet is in contact with the outer circumferential surface of the inner aluminum ring, and a circumferential gap is formed between adjacent magnets. An adhesive that fills the circumferential gap between adjacent magnets, the adhesive simultaneously bonding the side surfaces of adjacent magnets and the interface between the inner end face of the magnet and the outer circumferential surface of the aluminum inner ring; And a carbon fiber winding layer wrapped around the radially outer side of the plurality of magnets, the carbon fiber winding layer applying a radially inward preload to the plurality of magnets, so that the inner end face of the magnet and the outer peripheral surface of the aluminum inner ring and the adjacent magnets are kept in close contact.

2. The frameless torque motor rotor of the Heilbeck array according to claim 1, characterized in that: The n is a positive integer, and the number of pole pairs is n. In the Heilbeck array, the magnets with different oblique magnetization directions are arranged sequentially along the circumference, and every two adjacent obliquely magnetized magnets are equivalent to a magnetic pole. Specifically, adjacent magnets magnetized in the upper right direction and magnetized in the lower right direction form an N pole, and adjacent magnets magnetized in the upper left direction and magnetized in the upper right direction form an S pole. Every two pairs of adjacent magnets with equivalent N poles and every two pairs of adjacent magnets with equivalent S poles, a total of four magnets, form a complete pole pair.

3. The frameless torque motor rotor of the Heilbeck array according to claim 1, characterized in that: The outer circumferential surface of the aluminum inner ring is provided with multiple positioning grooves, the number of which is the same as the number of magnets. Each positioning groove is used to accommodate the inner end of a magnet, so as to realize the circumferential positioning of the magnet and prevent the magnet from slipping in the circumferential direction.

4. The frameless torque motor rotor of the Heilbeck array according to claim 1, characterized in that: The magnet is tile-shaped in a cross section perpendicular to the axial direction. The outer arc surface and the inner arc surface of the tile-shaped magnet are arranged concentrically, and the circumferential gap between adjacent tile-shaped magnets remains equal in the radial direction.

5. The frameless torque motor rotor of the Heilbeck array according to claim 1, characterized in that: The carbon fiber winding layer is a Bosch carbon fiber winding layer, which is formed by winding carbon fiber bundles in a circumferential direction. The number of winding layers is 2 to 8, and the fiber orientation between adjacent fiber layers is arranged in a cross pattern. The radial thickness of the carbon fiber winding layer is 0.5 mm to 3.0 mm.

6. The frameless torque motor rotor of the Heilbeck array according to claim 1, characterized in that: The adhesive is an epoxy resin structural adhesive. After curing, the epoxy resin structural adhesive forms an adhesive layer between adjacent magnets and between the magnets and the aluminum inner ring. The shear strength of the adhesive layer is not less than 25 MPa.

7. The frameless torque motor rotor of the Heilbeck array according to claim 1, characterized in that: The center of the aluminum inner ring is provided with a hollow through hole that runs through the axis, and the diameter of the hollow through hole is 60% to 80% of the outer diameter of the aluminum inner ring.

8. The frameless torque motor rotor of the Heilbeck array according to claim 1, characterized in that: The Heilbeck array makes the air gap magnetic flux density on the outer surface of the rotor sinusoidally distributed along the circumference, and the difference between the average magnetic induction intensity of the N pole and the S pole does not exceed 3%.

9. A method for assembling a frameless torque motor rotor of a Heilbeck array, characterized in that, Includes the following steps: S1: Provide an annular aluminum inner ring, wherein a plurality of positioning grooves are provided on the outer circumferential surface of the aluminum inner ring, and the number of positioning grooves is consistent with the number of magnets to be arranged. S2: Multiple magnets are embedded into the positioning slots one-to-one according to the Hellbeck array, so that the inner end face of each magnet is in contact with the bottom surface of the positioning slot, and a circumferential gap is formed between adjacent magnets. In the Hellbeck array, the magnetization direction of each magnet is a 45° oblique magnetization direction distributed along the annular circumference, that is, one magnetizes in the upper right ↗ direction, the next magnetizes in the lower right ↘ direction, the next magnetizes in the upper left ↖ direction, and the next magnetizes in the upper right ↗ direction, forming a continuous gradual magnetization; and adjacent magnets magnetized in the upper right ↗ direction and the lower right ↘ direction are equivalent to a N pole, and adjacent magnets magnetized in the upper left ↖ direction and the upper right ↗ direction are equivalent to a S pole. S3: Fill the circumferential gap between adjacent magnets with adhesive, which simultaneously wets the side surface of the magnet and the interface between the inner end face of the magnet and the bottom surface of the positioning groove. S4: Wind carbon fiber bundles around the radial outer side of the plurality of magnets. During winding, apply a circumferential tension of 50N to 200N to form a carbon fiber winding layer. The carbon fiber winding layer applies a radial inward preload to the magnets, so that the inner end face of the magnets is tightly attached to the bottom surface of the positioning groove. S5: Curing the adhesive and the resin matrix in the carbon fiber winding layer at a temperature of 60°C to 100°C for 2 to 6 hours, so that the magnet, aluminum inner ring and carbon fiber winding layer are cured into an integrated structure.

Images