A method of manufacturing a rotor assembly and a rotor assembly

Abstract

The application discloses a rotor assembly preparation method and a rotor assembly, and relates to the technical field of motors, wherein the rotor assembly comprises a rotor shell, a rotor magnetic steel and a code disc, and the rotor assembly preparation method comprises the following steps: installing the rotor shell on a magnetic isolation support assembly, and defining a first filling groove and a second filling groove by the rotor shell and the magnetic isolation support assembly; filling the same magnetic steel raw material into the first filling groove and the second filling groove and performing pressure forming to obtain an integrated structure formed by a first magnetic steel part and a second magnetic steel part; placing the rotor assembly in a magnetizing equipment to perform first-time magnetization on the first magnetic steel part to form the rotor magnetic steel; and placing the rotor assembly after the first-time magnetization is completed in an encoder magnetizing mold to perform second-time magnetization on the second magnetic steel part to form the code disc, wherein the rotor magnetic steel and the code disc both have N poles and S poles which are arranged alternately in the circumferential direction, and the number of magnetic pole pairs of the code disc is greater than that of the rotor magnetic steel. The application solves the problem that the prior art is inconvenient to assemble.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a method for preparing a rotor assembly and the rotor assembly itself. Background Technology

[0002] Currently, with the rapid development of fields such as robotics, drones, and medical equipment, the requirements for miniaturization and integration in the fabrication methods of rotor components are increasing. In existing technologies, unmagnetized rotor magnets and encoder disks are typically manufactured separately, then magnetized separately using magnetization equipment, and finally installed onto the rotor component. However, the magnetized magnets possess strong magnetism, resulting in significant attractive or repulsive forces between them during assembly, leading to assembly difficulties and challenges in controlling positioning accuracy. Summary of the Invention

[0003] The main objective of this invention is to provide a method for preparing a rotor assembly and a rotor assembly to solve the problem of inconvenient assembly in the prior art.

[0004] To achieve the above objectives, the present invention proposes a method for manufacturing a rotor assembly, wherein the rotor assembly includes a rotor housing, rotor magnets, and an encoder disk, and the method for manufacturing the rotor assembly includes: The rotor housing is mounted on the magnetic shielding support assembly, and the rotor housing and the magnetic shielding support assembly define the first filling groove and the second filling groove. The same magnet raw material is filled into the first filling groove and the second filling groove and then pressed to form a first magnet part and a second magnet part arranged along the axial direction of the rotor housing. The second magnet part and the first magnet part are an integral structural component. The rotor assembly is placed in a magnetizing device, which has a first shielding groove, a second magnet part is disposed in the first shielding groove, and the first magnet part is exposed outside the first shielding groove. The first magnet part is magnetized for the first time by the magnetizing device to form a rotor magnet. The rotor magnet has N poles and S poles arranged alternately along the circumference of the rotor housing. After the first magnetization is completed, the rotor assembly is placed in the encoder magnetization mold. The encoder magnetization mold has a second shielding groove. The first magnet part is located in the second shielding groove, and the second magnet part is exposed outside the second shielding groove. The second magnet part is magnetized a second time through the encoder magnetization mold to form a code disk. The code disk has N poles and S poles arranged alternately along the circumference of the rotor housing. The number of magnetic pole pairs of the code disk is greater than the number of magnetic pole pairs of the rotor magnet.

[0005] In one embodiment, the code disk formed by the second magnet includes an outer code track and an inner code track arranged radially. The outer code track is located radially outside the inner code track, and there is a radial gap between the outer code track and the inner code track. The width of the radial gap is 0.5 mm to 3 mm.

[0006] In one embodiment, the outer ring code track and the inner ring code track are offset from each other in the circumferential direction, and the offset angle between the magnetic poles of the outer ring code track and the magnetic poles of the inner ring code track in the circumferential direction is 0.5°~10°.

[0007] In one embodiment, after the second magnetization is completed, each sensing magnetic pole of the code disk is detected point by point. The point-by-point detection step includes: The integrated structural component is rotated relative to the single-point detection head. For each preset angle, the magnetic induction intensity of a sensing magnetic pole corresponding to that angle is detected by the single-point detection head. The preset angle is 360° / N, where N is the total number of sensing magnetic poles of the code disk. If the test is qualified, the test continues to the next angle; if the test is unqualified, the unqualified sensing magnetic pole is magnetized by the single-point detection head until the magnetic induction intensity of the sensing magnetic pole reaches the preset threshold. The detection of all sensing magnetic poles of the code disk is completed sequentially.

[0008] In one embodiment, after the first magnetization is completed, the integrated structural component is transferred from the magnetization device to the encoder magnetization mold. During the transfer, the positioning angle of the integrated structural component along its circumference remains unchanged, and the deviation of the positioning angle does not exceed ±0.5°.

[0009] In one embodiment, the first shielding groove and the second shielding groove are made of a ferromagnetic material, wherein the relative permeability of the ferromagnetic material is ≥1000; The wall thickness of the first shielding groove is H1, and the wall thickness of the second shielding groove is H2, satisfying: 1mm≤H1≤4mm, 5mm≤H2≤12mm, and H2≥1.5H1.

[0010] In one embodiment, a pre-magnetization alignment is performed before the first magnetization. The pre-magnetization alignment step includes: placing the integrated structural component in the magnetization device, pre-magnetizing the first magnet part, and using the magnetic field generated by the pre-magnetization to rotate the integrated structural component to a preset circumferential alignment position, wherein the angular deviation of the circumferential alignment position does not exceed ±0.3°; and after the integrated structural component is aligned, the first magnet part is then magnetized for the first time.

[0011] In one embodiment, during the first magnetization and / or the second magnetization process, the temperature of the magnetization environment is detected. When the temperature of the magnetization environment exceeds a preset temperature range, the magnetization environment is cooled down. Magnetization continues after the temperature of the magnetization environment returns to the preset temperature range. The preset temperature range is 20℃~40℃.

[0012] In one embodiment, during the second magnetization, the magnetic poles of the second magnet are arranged in a Halebeck array, such that the magnetic induction intensity on the side of the second magnet facing the encoder detection element is greater than the magnetic induction intensity on the side away from the encoder detection element.

[0013] The present invention also proposes a rotor assembly, which is prepared by the rotor assembly preparation method described above.

[0014] In the rotor assembly manufacturing method provided by this invention, the first magnet and the second magnet are integrated into a single structural component before magnetization. Both the first and second magnetization processes are performed directly on this integrated component, eliminating the need to separately assemble the magnetized magnets and encoder onto the rotor assembly. This avoids the assembly difficulties and positioning accuracy issues caused by the attractive or repulsive forces between the magnetized magnets during assembly, thus improving assembly accuracy and product consistency. Simultaneously, during the first magnetization, the second magnet is positioned within the first shielding groove, thus avoiding the magnetization magnetic field and magnetizing only the first magnet. Similarly, during the second magnetization, the first magnet is positioned within the second shielding groove, again avoiding the magnetization magnetic field and magnetizing only the second magnet. Through the coordination of these two magnetization processes, the first and second magnets are magnetized independently, with no interference between the two steps. This achieves independent magnetization of the magnet and encoder on the integrated structural component, balancing structural compactness and functional zoning requirements. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 A schematic flowchart illustrating the method for preparing the rotor assembly provided by the present invention; Figure 2 This is a schematic diagram of the structure of the brushless motor provided by the present invention; Figure 3 for Figure 2 A schematic diagram of one embodiment; Figure 4This is a schematic diagram of the rotor assembly provided by the present invention.

[0017] Explanation of icon numbers: 110. Rotor housing; 120. Rotor magnet; 121. Encoder disk; 1211. Outer ring code track; 1212. Inner ring code track.

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] 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 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.

[0020] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0021] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0022] Please see Figure 1 In one embodiment of the present invention, a method for manufacturing a rotor assembly is provided, which is applied to a motor. The rotor assembly includes a rotor housing 110, rotor magnets 120, and an encoder disk 121. The method for manufacturing the rotor assembly includes: S100: The rotor housing 110 is mounted on the magnetic shielding bracket assembly, and the rotor housing 110 and the magnetic shielding bracket assembly define the first filling groove and the second filling groove. S200: The same magnet raw material is filled into the first filling groove and the second filling groove and pressure is applied to form a first magnet part and a second magnet part arranged along the axial direction of the rotor housing 110. The second magnet part and the first magnet part are an integral structural component. S300: The rotor assembly is placed in a magnetizing device. The magnetizing device has a first shielding groove, a second magnet is disposed in the first shielding groove, and the first magnet is exposed outside the first shielding groove. The first magnet is magnetized for the first time by the magnetizing device to form a rotor magnet 120. The rotor magnet 120 has N poles and S poles arranged alternately along the circumference of the rotor housing 110. S400: The rotor assembly after the first magnetization is completed is placed in the encoder magnetization mold. The encoder magnetization mold is provided with a second shielding groove. The first magnet part is located in the second shielding groove, and the second magnet part is exposed outside the second shielding groove. The second magnet part is magnetized for the second time through the encoder magnetization mold to form a code disk 121. The code disk 121 has N poles and S poles arranged alternately along the circumference of the rotor housing 110. The number of pole pairs of the code disk 121 is greater than the number of pole pairs of the rotor magnet 120.

[0023] In this embodiment, the first filling groove and the second filling groove are arranged at intervals along the axial direction of the rotor housing 110, and the first filling groove and the second filling groove are respectively coaxially arranged with the rotor housing 110; wherein, the first filling groove is used to form the rotor magnet 120, and its radial dimension and axial length are set according to the required rotor magnet 120 size; the second filling groove is used to form the code disk 121, and its radial dimension and axial length are set according to the required code disk 121 size, which is not limited here.

[0024] Understandably, the magnetic shielding bracket assembly is made of non-magnetic material, such as stainless steel or aluminum alloy, and is used to guide and isolate the magnetic circuit during the subsequent magnetization process to prevent the raw materials of the magnets in the first and second filling slots from interfering with each other during magnetization.

[0025] It is understood that the raw material for the magnet is a permanent magnet material, which can be selected from neodymium iron boron, ferrite, or samarium cobalt, etc. For example, the raw material for the magnet is anisotropic bonded neodymium iron boron material, which has a high magnetic energy product and good formability, and is suitable for making complex-shaped integral structural parts by pressure molding.

[0026] It is understandable that pressure molding can be performed using wet pressing, warm pressing, or cold pressing. For example, in a wet pressing process, the raw material for the magnet is a mixture of permanent magnet powder and a binder. The raw material is injected into a first filling tank and a second filling tank, and pressing is performed simultaneously with magnetic field orientation, ensuring the raw material is dense and oriented within the filling tanks. After molding, it is dried. Wet pressing allows the raw material to achieve good magnetic field orientation during the molding process, which is beneficial for improving magnetic properties after subsequent magnetization.

[0027] After pressure molding, a first magnet section and a second magnet section are obtained. The first magnet section and the second magnet section are arranged along the axial direction of the rotor housing 110, and both are integrally formed from the same magnet raw material. Through the cooperation of the magnetic shielding bracket assembly and pressure molding, the magnet raw materials in the first filling groove and the second filling groove can form an integral structural component before magnetization. It is not necessary to assemble the magnet and the code disk 121 onto the rotor housing 110 separately after magnetization, thereby avoiding the problems of assembly difficulties and positioning accuracy control caused by the strong magnetism of the magnet after magnetization.

[0028] For example, the magnetic shielding support includes a first magnetic shielding support and a second magnetic shielding support. The first magnetic shielding support is installed inside the rotor housing, and the first magnetic shielding support and the rotor housing define a first filling groove. Magnet raw material is filled into the first filling groove and pressurized to form a first magnet portion. Then, the second magnetic shielding support is installed inside the rotor housing 110, and the second magnetic shielding support, the rotor housing 110, and the first magnet portion together define a second filling groove. The same magnet raw material is filled into the second filling groove and pressurized to form a second magnet portion. During the pressurization process of the second magnet portion, the forming pressure is transmitted axially along the rotor housing 110 and acts on the first magnet portion, causing the first magnet portion to undergo secondary pressing on its already formed basis, thereby further increasing the density of the first magnet portion and making the bond between the first magnet portion and the second magnet portion tighter. Thus, the first magnet portion and the second magnet portion are integrally formed from the same magnet raw material.

[0029] In this embodiment, the magnetizing device has a first shielding groove. It can be understood that the first shielding groove is a groove-shaped space formed by ferromagnetic material within the magnetizing device, the shape of which matches the outer contour of the second magnet portion, and is used to shield the second magnet portion placed therein from the magnetic field during the magnetization process.

[0030] Optionally, the first shielding groove is made of ferromagnetic material with high magnetic permeability, which can provide a low magnetic resistance bypass channel for the magnetizing magnetic field, so that the magnetizing magnetic field passes along the wall of the first shielding groove and cannot penetrate into the internal space of the first shielding groove. Therefore, the magnetizing magnetic field of the first magnetization is shielded by the first shielding groove and cannot act on the second magnet part, and only the first magnet part is magnetized. After the first magnetization is completed, the first magnet part forms N poles and S poles that are alternately arranged in the circumference of the rotor housing 110. At this time, the first magnet part constitutes the rotor magnet 120.

[0031] After the first magnetization is completed, the rotor assembly after the first magnetization is removed from the magnetization equipment and placed in the encoder magnetization mold. Since the encoder magnetization mold is provided with a second shielding groove, it can be understood that the second shielding groove is a groove-shaped space formed by ferromagnetic material in the encoder magnetization mold. Its inner cavity shape is adapted to the outer contour of the first magnet part, and it is used to shield the magnet part placed therein during the magnetization process. The first magnet part is placed in the second shielding groove so that the first magnet part is completely covered by the second shielding groove, while the second magnet part is exposed outside the second shielding groove. Subsequently, the second magnet part is magnetized for the second time through the encoder magnetization mold. Due to the shielding effect of the second shielding groove, the magnetization magnetic field cannot act on the already magnetized first magnet part. Only the second magnet part is magnetized to form a code disk 121. The code disk 121 has N poles and S poles arranged alternately along the circumference of the rotor housing 110.

[0032] In this embodiment, the number of pole pairs in the code disk 121 is greater than the number of pole pairs in the rotor magnet 120. It should be noted that the number of pole pairs in the rotor magnet 120 determines the number of poles in the motor; fewer pole pairs result in higher magnetic flux density, thus generating a larger driving torque. The number of pole pairs in the code disk 121 determines the encoder's resolution; more pole pairs enable higher precision position detection. For example, during the first magnetization, the magnetizing device has 2 or 4 magnetization heads, resulting in the rotor magnet 120 having 2 or 4 poles, thus achieving a higher magnetic flux density. During the second magnetization, the encoder magnetizing mold has 16, 32, or 64 magnetization heads, resulting in the code disk 121 having 16, 32, or 64 poles, thus achieving high-resolution position detection. In this embodiment, the number of pole pairs in the code disk 121 is configured to be greater than the number of pole pairs in the rotor magnet 120, balancing driving performance and detection accuracy.

[0033] In this embodiment, the first magnet part and the second magnet part are formed as an integral structural component before magnetization. Both magnetizations are performed directly on the integral structural component, eliminating the need to assemble the magnets and code disk 121 separately after magnetization, thus avoiding assembly difficulties caused by assembly after magnetization. At the same time, through the cooperation of step-by-step magnetization and shielding groove, the two magnetization steps do not interfere with each other, realizing independent magnetization of two different functional areas on the same integral structural component.

[0034] In one implementation, see Figure 3 and Figure 4 The code disk 121 formed by the second magnet part includes an outer ring code track 1211 and an inner ring code track 1212 arranged radially. The outer ring code track 1211 is located radially outside the inner ring code track 1212. There is a radial gap between the outer ring code track 1211 and the inner ring code track 1212. The width of the radial gap is 0.5mm to 3mm.

[0035] In this embodiment, along the radial direction of the rotor housing 110, the outer ring code track 1211 and the inner ring code track 1212 are coaxially arranged with the rotor housing 110; the outer ring code track 1211 is used to form the outer ring detection track of the encoder, and the inner ring code track 1212 is used to form the inner ring detection track of the encoder, and both work in conjunction with the encoder detection element.

[0036] It is understandable that by setting a radial gap between the outer code track 1211 and the inner code track 1212, sufficient physical distance can be maintained between them in the radial direction. This avoids mutual interference between the magnetic fields of the outer code track 1211 and the inner code track 1212, ensuring that each code track outputs a clear and independent detection signal. It should be noted that if the radial gap is too small, the magnetic fields between the outer code track 1211 and the inner code track 1212 are prone to coupling, leading to signal crosstalk and affecting the encoder's detection accuracy. If the radial gap is too large, it will increase the radial dimension of the code disk 121, which is detrimental to the miniaturization of the rotor assembly. In this embodiment, the radial gap is controlled within the range of 0.5mm to 3mm, which ensures both the magnetic field isolation effect between the two code tracks and the compact design of the rotor assembly, resulting in a good balance between detection accuracy and structural dimensions for the code disk 121.

[0037] It is understandable that by configuring the code disk 121 formed by the second magnet section into an outer code track 1211 and an inner code track 1212, the two code tracks can each undertake different encoding functions. For example, the outer code track 1211 can serve as an incremental code track for outputting incremental position signals; the inner code track 1212 can serve as an absolute code track for outputting absolute position signals. With this configuration, the code disk 121 can simultaneously provide incremental and absolute signals, achieving higher performance encoding detection.

[0038] In one implementation, see Figure 3 and Figure 4 The outer ring code track 1211 and the inner ring code track 1212 are offset from each other in the circumferential direction, and the circumferential offset angle between the magnetic poles of the outer ring code track 1211 and the magnetic poles of the inner ring code track 1212 is 0.5° to 10°.

[0039] It is understandable that, since the rotor housing 110 is usually annular in circumference, the code disk 121 is also usually annular. The outer code track 1211 and the inner code track 1212 of the code disk 121 each have multiple magnetic poles arranged alternately in circumference. During the rotation of the code disk 121, the encoder detection element outputs a detection signal by sensing the changes in the magnetic field of the outer code track 1211 and the inner code track 1212. When the magnetic poles of the two code tracks are aligned in the circumferential direction, the magnetic poles of the outer code track 1211 and the inner code track 1212 pass through the sensing area of ​​the detection element at the same time. The detection signals output by the two tend to be consistent in phase, and the differentiation between the signals is poor, which is not conducive to improving the detection resolution. Moreover, the magnetic fields between the two magnetic poles are easy to superimpose or cancel each other, resulting in distortion of the detection signal waveform.

[0040] In this embodiment, by offsetting the magnetic poles of the outer code track 1211 and the inner code track 1212 in the circumferential direction, a phase difference is formed between the detection signal output by the outer code track 1211 and the detection signal output by the inner code track 1212, thereby forming two detection signals with a phase difference. The phase difference between the two detection signals allows the encoder to perform differential processing or quadrature decoding, thereby improving the encoder's detection resolution and signal anti-interference capability.

[0041] For example, when the outer code track 1211 and the inner code track 1212 have the same number of magnetic poles, both being 32 poles, the angle between two adjacent magnetic poles is 11.25°. At this time, the outer code track 1211 and the inner code track 1212 are offset by 5.625°, and the detection signals output by the two code tracks form a 90° phase difference, i.e., quadrature signals. Quadrature signals have excellent noise immunity and good signal orthogonality, which can effectively improve the encoder's detection resolution and position detection accuracy.

[0042] It should be noted that if the offset angle is too small, the phase difference between the detection signals output from the two code channels will be insufficient, making it difficult to form an effective signal distinction and limiting the improvement in detection resolution. If the offset angle is too large, the phase difference between the two detection signals will exceed the range of the signal processing circuit, increasing the difficulty of signal processing and even causing signal distortion. This embodiment controls the offset angle within the range of 0.5° to 10°, which can obtain a suitable signal phase difference, which is beneficial to both improving detection resolution and ensuring signal quality.

[0043] In an optional implementation, the offset angle between the magnetic poles of the outer code track 1211 and the magnetic poles of the inner code track 1212 can be set to half the angle between two adjacent magnetic poles. For example, when the number of magnetic poles in the outer code track 1211 and the inner code track 1212 is the same, offsetting the two code tracks by half the width of a magnetic pole allows the two detection signals to form a 90° phase difference, i.e., quadrature signals, thereby achieving higher detection accuracy.

[0044] In one embodiment, after the second magnetization is completed, each sensing magnetic pole of the code disk 121 is detected point by point. The point-by-point detection step includes: The integrated structural component is rotated relative to the single-point detection head. For each preset rotation angle, the magnetic induction intensity of a sensing magnetic pole corresponding to that angle is detected by the single-point detection head. The preset angle is 360° / N, where N is the total number of sensing magnetic poles on the code disk 121. If the detection is successful, the detection continues to the next angle. If the detection fails, the single-point detection head re-magnetizes the failed sensing magnetic pole until its magnetic induction intensity reaches a preset threshold. The detection of all sensing magnetic poles on the code disk 121 is completed sequentially.

[0045] Since the magnetic induction intensity of the sensing poles directly affects the amplitude and stability of the encoder detection signal, insufficient magnetic induction intensity or defects in some sensing poles can cause fluctuations in the encoder output signal and reduce the position detection accuracy. Therefore, after the second magnetization, each sensing pole of the code disk 121 needs to be tested point by point, and magnetization should be performed according to the test results.

[0046] For example, the integrated structural component is mounted on the testing fixture, with the code disk 121 positioned opposite to the single-point detection head. The single-point detection head has a magnetic sensor, the sensing area of ​​which is aligned with a sensing magnetic pole of the code disk 121 to detect the magnetic induction intensity of the sensing magnetic pole. The integrated structural component is rotated relative to the single-point detection head, and the single-point detection head pauses once for each preset angle of rotation to detect the magnetic induction intensity of the sensing magnetic pole corresponding to that angle. During the detection, the single-point detection head acquires the magnetic induction intensity signal of the sensing magnetic pole and compares the signal with a preset threshold.

[0047] In this embodiment, the preset angle is 360° / N, where N is the total number of sensing magnetic poles of the code disk 121. It can be understood that during detection, the angle of each rotation is exactly equal to the circumferential angle occupied by one magnetic pole, thus ensuring that with each rotation, the single-point detection head aligns with a different sensing magnetic pole, sequentially completing the detection of all sensing magnetic poles of the code disk 121.

[0048] For example, when the total number of sensing magnetic poles of the code disk 121 is 32, the preset angle is 360° / 32=11.25°, that is, one sensing magnetic pole is detected for every 11.25° rotation. After rotating and detecting 32 times in sequence, the detection of all 32 sensing magnetic poles of the code disk 121 can be completed.

[0049] If the magnetic induction intensity of the currently detected sensing pole reaches the preset threshold, the sensing pole is deemed qualified, and the system continues to rotate to the next angle to detect the next sensing pole. If the magnetic induction intensity of the currently detected sensing pole does not reach the preset threshold, the sensing pole is deemed unqualified. In this case, the unqualified sensing pole is magnetized using a single-point detection head, i.e., a magnetizing magnetic field is applied to the sensing pole individually until the magnetic induction intensity of the sensing pole reaches the preset threshold. After magnetization, the sensing pole is detected again for confirmation. If it passes the test, the system continues to rotate to the next angle to detect the next sensing pole. The above steps of rotation, detection, judgment, and magnetization are repeated sequentially until all sensing poles of the code disk 121 have been detected and magnetized.

[0050] Understandably, by performing point-by-point testing on each sensing magnetic pole of the code disk 121 after the second magnetization, it is possible to promptly identify and correct magnetic poles that have failed magnetization, thus avoiding fluctuations or distortions in the encoder output signal due to local magnetic pole defects. It can also ensure that the magnetic induction intensity of each sensing magnetic pole of the code disk 121 is consistent, improving the consistency of the magnetization quality of the code disk 121, thereby ensuring the amplitude stability and phase accuracy of the encoder output signal.

[0051] In one embodiment, after the first magnetization is completed, the integrated structural component is transferred from the magnetization device to the encoder magnetization mold. During the transfer, the positioning angle of the integrated structural component along its circumference remains unchanged, and the deviation of the positioning angle does not exceed ±0.5°.

[0052] It should be noted that after the first magnetization is completed, the first magnet part has formed N poles and S poles arranged alternately in the circumferential direction. These driving magnetic poles have a definite absolute position in the circumferential direction. During the second magnetization, it is necessary to maintain a predetermined relative positional relationship between the magnetizing pole head of the encoder magnetization mold and the magnetic poles formed in the first magnet part in the circumferential direction to ensure the circumferential positional accuracy between the magnetic poles of the code disk 121 and the magnetic poles of the rotor magnet 120.

[0053] In this embodiment, during the transfer process, the circumferential angle position of the integrated structural component when it completes its first magnetization in the magnetization device is consistent with the circumferential angle position of the integrated structural component when it is placed into the encoder magnetization mold, and the deviation of the positioning angle does not exceed ±0.5°.

[0054] It is understandable that the purpose of keeping the positioning angle unchanged is to ensure that there is a definite angular relationship between the starting position of the magnetic pole during the second magnetization and the starting position of the magnetic pole during the first magnetization. If the integrated structural component rotates during the transfer process, causing the positioning angle deviation to be too large, the circumferential position of the code disk 121 magnetic pole relative to the rotor magnet 120 magnetic pole during the second magnetization will deviate from the design value. When the deviation accumulates, it is easy to cause the phase relationship between the output signal of the code disk 121 and the rotor position signal to deviate from the expectation, affecting the detection accuracy of the encoder and the accuracy of motor control.

[0055] For example, when the number of magnetic pole pairs of the code disk 121 is 16, the included angle between adjacent magnetic poles is 11.25°; if the positioning angle deviation is 0.5°, then the deviation accounts for only about 4.4% of the included angle between adjacent magnetic poles, and its impact on the encoder detection signal is negligible.

[0056] Optionally, to achieve precise maintenance of the above positioning angle, the magnetizing equipment and the encoder magnetizing mold are respectively provided with positioning structures. The positioning structures can be positioning pins, positioning grooves, or clamps, etc., and are not limited here. The integrated structural component is circumferentially positioned in both the magnetizing equipment and the encoder magnetizing mold through the positioning structures, thereby ensuring the consistency of the circumferential position before and after the transfer.

[0057] In one embodiment, the first shielding groove and the second shielding groove are made of ferromagnetic material with a relative permeability ≥1000; the wall thickness of the first shielding groove is H1 and the wall thickness of the second shielding groove is H2, satisfying: 1mm≤H1≤4mm, 5mm≤H2≤12mm, and H2≥1.5H1.

[0058] It should be noted that the basic principle of magnetic shielding is to use a high-permeability material to provide a low-resistance bypass channel for the magnetic field, allowing the magnetic flux to pass along the wall of the shield, thereby preventing the magnetic field from penetrating the shield and entering its internal space. The parameter for measuring the magnetic permeability of a material is relative permeability. The relative permeability of vacuum is 1, while the relative permeability of ferromagnetic materials is usually much greater than 1. The higher the relative permeability, the more significant the shunting effect of the shield on the magnetic field, and the higher the shielding effectiveness. In this embodiment, the relative permeability of the first and second shielding slots is limited to ≥1000, which ensures that the shielding slots have sufficient shielding effect against the magnetized magnetic field, protecting the magnet portion located within the shielding slots from the influence of the magnetized magnetic field.

[0059] It should be noted that the wall thickness of the shield is another important characteristic affecting the shielding effect; increasing the wall thickness of the shield is equivalent to increasing the cross-sectional area of ​​the magnetic circuit, which can reduce the magnetic reluctance of the magnetic circuit and thus improve the shielding effectiveness; when the magnetic permeability of the material is the same, the thicker the wall, the more significant the shielding effect.

[0060] In this embodiment, since the first shielding groove is used to shield the second magnet part, and the volume of the second magnet part is relatively small, the magnetic field area that the first shielding groove needs to shield is small, and a wall thickness of 1mm to 4mm is sufficient to meet the shielding requirements. The second shielding groove is used to shield the first magnet part, and the volume of the first magnet part is much larger than that of the second magnet part. The magnetic field strength generated during magnetization is stronger and the magnetic field distribution range is wider. Therefore, a thicker wall thickness is required to ensure sufficient shielding effect. A wall thickness of 5mm to 12mm can ensure sufficient shielding of the first magnet part.

[0061] In one embodiment, the length of the first magnet part along the axial direction of the rotor housing 110 is L1, and the length of the second magnet part along the axial direction of the rotor housing 110 is L2, satisfying: 8≤L1 / L2≤12.

[0062] It should be noted that since the function of the rotor magnet 120 is to generate driving torque, it needs a large volume to obtain sufficient magnetic flux; the function of the encoder 121 is to provide position detection signal, and its magnetic poles are distributed circumferentially.

[0063] For example, when L1 is 16cm, L2 is 1.6cm, so that the rotor magnet 120 has sufficient axial length to ensure high magnetic flux density and driving torque, while the code disk 121 has appropriate axial length to ensure that the encoder detection element can effectively sense its magnetic field changes.

[0064] Understandably, if L1 / L2 is less than 8, it indicates that the axial length of the rotor magnet 120 is relatively short or the axial length of the code disk 121 is relatively long, resulting in insufficient magnetic flux of the rotor magnet 120 or excessive axial space occupied by the code disk 121, thus leading to a decrease in driving torque or difficulty in achieving miniaturization. If L1 / L2 is greater than 12, the axial length of the code disk 121 is too small, resulting in insufficient axial width of the magnetic poles of the code disk 121, making it difficult for the encoder detection element to effectively sense the magnetic field signal and affecting the detection accuracy.

[0065] In one embodiment, a pre-magnetization alignment is performed before the first magnetization. The pre-magnetization alignment step includes: placing the integrated structural component in the magnetization device, pre-magnetizing the first magnet part, and using the magnetic field generated by the pre-magnetization to rotate the integrated structural component to a preset circumferential alignment position, wherein the angular deviation of the circumferential alignment position does not exceed ±0.3°; and after the integrated structural component is aligned, the first magnet part is then magnetized for the first time.

[0066] It should be noted that the first magnet needs to be in an accurate circumferential position relative to the magnetizing coil in the magnetizing equipment in order to ensure the circumferential distribution accuracy of the N and S poles formed after the first magnetization. If there is a deviation in the circumferential position of the first magnet in the magnetizing equipment, the starting position of the magnetic poles formed after magnetization will deviate from the design value, which will affect the relative position accuracy between the code disk 121 magnetic pole and the rotor magnet 120 magnetic pole during the second magnetization, and ultimately affect the detection accuracy of the encoder.

[0067] Before the first magnetization, the integrated structural component is placed in a magnetization device to pre-magnetize the first magnet. It should be noted that pre-magnetization refers to initially magnetizing the first magnet with a magnetic field below the saturation magnetization intensity, creating a weak magnetic field. This weak magnetic field interacts with the positioning structure of the magnetization device, generating a torque that rotates the integrated structural component to a preset circumferential alignment position. After the integrated structural component reaches the preset circumferential alignment position, the first magnet is then magnetized for the first time. If the angular deviation exceeds 0.3° during alignment, the initial circumferential position of the magnetic poles formed after the first magnetization may deviate from the design value. This deviation will accumulate in the magnetic poles of the code disk 121 after the second magnetization, causing a phase shift in the output signal of the code disk 121, thus affecting the encoder's detection accuracy.

[0068] In this embodiment, the magnetic field strength for pre-magnetization is less than that for saturation magnetization. If the pre-magnetization magnetic field strength is too high, the first magnet will reach a high degree of magnetization prematurely, affecting the uniformity of the magnetic pole distribution during subsequent saturation magnetization; if the pre-magnetization magnetic field strength is too low, the generated torque will be insufficient to drive the integral structural component to rotate to the preset position. The pre-magnetization magnetic field strength can be set according to the grade of the magnet raw material and the desired pre-magnetization effect, and is not limited here.

[0069] This embodiment achieves automatic alignment of the integrated structural component through pre-magnetization and alignment, utilizing the interaction of magnetic fields. No additional structure is required, thereby reducing production costs and ensuring the circumferential positional accuracy of the magnetized poles.

[0070] In one embodiment, during the first magnetization and / or the second magnetization process, the temperature of the magnetization environment is detected. When the temperature of the magnetization environment exceeds a preset temperature range, the magnetization environment is cooled down. Magnetization continues after the temperature of the magnetization environment returns to the preset temperature range. The preset temperature range is 20℃~40℃.

[0071] It should be noted that during long-term operation or continuous magnetization, the magnetization coil and magnetization head will generate a large amount of Joule heat, causing the equipment temperature to rise. When the temperature of the magnetization environment is too high, the magnetic properties of the magnet raw material will decrease, resulting in insufficient magnetic flux density after magnetization and uneven magnetic field distribution between magnetic poles, affecting the long-term stability of the magnet.

[0072] Optionally, a temperature detection element may be provided in the magnetization equipment and / or encoder magnetization mold to detect the current temperature of the magnetization environment in real time.

[0073] The preset temperature range is 20℃~40℃. When the temperature of the magnetization environment is within this range, the magnetic properties of the magnet raw material are stable, the magnetization equipment works normally, and magnetization can be performed. If the temperature is too high, the controller activates a cooling device to cool the magnetization environment until the temperature returns to the preset range of 20℃~40℃. The controller then stops the cooling device and allows the magnetization operation to continue. The cooling device can be an air-cooled device, a water-cooled device, or a semiconductor refrigeration device; no specific limitation is made here.

[0074] In one embodiment, during the second magnetization, the magnetic poles of the second magnet are arranged in a Halebeck array, such that the magnetic induction intensity on the side of the second magnet facing the encoder detection element is greater than the magnetic induction intensity on the side away from the encoder detection element.

[0075] It should be noted that in the Heilbeck array, the magnetization direction of adjacent magnetic pole regions is rotated by a predetermined angle in sequence, so that the magnetic fields generated by each magnet are superimposed and enhanced in the same direction on one side of the array, and cancel each other out and weaken on the other side.

[0076] Because the Helbeck array has a unilateral magnetic focusing effect, after magnetization, the magnetic induction intensity on the side of the second magnet facing the encoder detection element is greater than the magnetic induction intensity on the side away from the encoder detection element. At this time, the magnetic field of the second magnet is concentrated on the side facing the encoder detection element, while the magnetic field on the side facing the first magnet is significantly weakened.

[0077] For example, in the second magnetization, the second magnet is magnetized by a multi-pole magnetization using an encoder magnetization mold; the magnetization poles of the encoder magnetization mold are arranged circumferentially, and the magnetization direction of each magnetization pole is rotated sequentially by a predetermined angle along the circumferential direction, so that the magnetization direction of each region of the second magnet is rotated sequentially by a predetermined angle along the circumferential direction, thereby forming a Heilbeck array; since the Heilbeck array has a unilateral magnetic focusing effect, the magnetic induction intensity on the side of the second magnet facing the encoder detection element is greater than the magnetic induction intensity on the side away from the encoder detection element.

[0078] The present invention also proposes a rotor assembly, see reference. Figures 2 to 4The rotor assembly includes a rotor housing 110, a rotor magnet 120, and an encoder disk 121, wherein the rotor magnet 120 and the encoder disk 121 are integral structures manufactured by the method described in any of the above-mentioned rotor assembly preparation methods.

[0079] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for manufacturing a rotor assembly, characterized in that, The rotor assembly includes a rotor housing, rotor magnets, and an encoder disk. The method for manufacturing the rotor assembly includes: The rotor housing is mounted on the magnetic shielding support assembly, and the rotor housing and the magnetic shielding support assembly define the first filling groove and the second filling groove. The same magnet raw material is filled into the first filling groove and the second filling groove and then pressed to form a first magnet part and a second magnet part arranged along the axial direction of the rotor housing. The second magnet part and the first magnet part are an integral structural component. The rotor assembly is placed in a magnetizing device, which has a first shielding groove, a second magnet part is disposed in the first shielding groove, and the first magnet part is exposed outside the first shielding groove. The first magnet part is magnetized for the first time by the magnetizing device to form a rotor magnet. The rotor magnet has N poles and S poles arranged alternately along the circumference of the rotor housing. After the first magnetization is completed, the rotor assembly is placed in the encoder magnetization mold. The encoder magnetization mold has a second shielding groove. The first magnet part is located in the second shielding groove, and the second magnet part is exposed outside the second shielding groove. The second magnet part is magnetized a second time through the encoder magnetization mold to form a code disk. The code disk has N poles and S poles arranged alternately along the circumference of the rotor housing. The number of magnetic pole pairs of the code disk is greater than the number of magnetic pole pairs of the rotor magnet.

2. The method for preparing the rotor assembly as described in claim 1, characterized in that, The code disk formed by the second magnet part includes an outer ring code track and an inner ring code track arranged radially. The outer ring code track is located radially outside the inner ring code track, and there is a radial gap between the outer ring code track and the inner ring code track. The width of the radial gap is 0.5mm to 3mm.

3. The method for preparing the rotor assembly as described in claim 2, characterized in that, The outer ring code track and the inner ring code track are offset from each other in the circumferential direction, and the circumferential angle between the magnetic poles of the outer ring code track and the magnetic poles of the inner ring code track is 0.5°~10°.

4. The method for preparing the rotor assembly as described in claim 1, characterized in that, After the second magnetization is completed, each sensing magnetic pole of the code disk is detected point by point. The point-by-point detection steps include: The integrated structural component is rotated relative to the single-point detection head. For each preset angle, the magnetic induction intensity of a sensing magnetic pole corresponding to that angle is detected by the single-point detection head. The preset angle is 360° / N, where N is the total number of sensing magnetic poles of the code disk. If the test is qualified, the test continues to the next angle; if the test is unqualified, the unqualified sensing magnetic pole is magnetized by the single-point detection head until the magnetic induction intensity of the sensing magnetic pole reaches the preset threshold. The detection of all sensing magnetic poles of the code disk is completed sequentially.

5. The method for preparing the rotor assembly as described in claim 1, characterized in that, After the first magnetization is completed, the integrated structural component is transferred from the magnetization device to the encoder magnetization mold. During the transfer, the positioning angle of the integrated structural component along its circumference remains unchanged, and the deviation of the positioning angle does not exceed ±0.5°.

6. The method for preparing the rotor assembly as described in claim 1, characterized in that, The first shielding groove and the second shielding groove are made of ferromagnetic material, and the relative permeability of the ferromagnetic material is ≥1000; The wall thickness of the first shielding groove is H1, and the wall thickness of the second shielding groove is H2, satisfying: 1mm≤H1≤4mm, 5mm≤H2≤12mm, and H2≥1.5H1.

7. The method for preparing the rotor assembly as described in claim 1, characterized in that, Before the first magnetization, a pre-magnetization alignment is performed. The pre-magnetization alignment step includes: placing the integrated structural component in the magnetization device, pre-magnetizing the first magnet part, and using the magnetic field generated by the pre-magnetization to rotate the integrated structural component to a preset circumferential alignment position, wherein the angular deviation of the circumferential alignment position does not exceed ±0.3°; after the integrated structural component is aligned, the first magnet part is then magnetized for the first time.

8. The method for preparing the rotor assembly according to any one of claims 1 to 7, characterized in that, During the first and / or second magnetization process, the temperature of the magnetization environment is monitored. When the temperature of the magnetization environment exceeds the preset temperature range, the magnetization environment is cooled down. Magnetization continues after the temperature of the magnetization environment returns to the preset temperature range. The preset temperature range is 20℃~40℃.

9. The method for preparing the rotor assembly according to any one of claims 1 to 7, characterized in that, During the second magnetization, the magnetic poles of the second magnet are arranged in a Halebeck array, so that the magnetic induction intensity on the side of the second magnet facing the encoder detection element is greater than the magnetic induction intensity on the side away from the encoder detection element.

10. A rotor assembly, characterized in that, The rotor assembly is prepared using the method described in any one of claims 1 to 9.

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