High-efficiency hybrid copper-aluminum rotor motor

Abstract

The invention discloses a high-efficiency hybrid copper-aluminum rotor motor, which belongs to the technical field of motors and comprises a stator and a rotor, and a shell with radiating fins and an end cover are arranged on the outer side of the stator. The core improvement of the rotor is that the conducting bars are formed by mixing copper conducting bars and aluminum conducting bars and are arranged in a specific layered mode, the copper conducting bars are arranged on the upper layer and the lower layer of a rotor groove, the aluminum conducting bars are arranged on the middle layer, the skin effect is actively utilized, a high-frequency current path is optimized, and the copper conducting bars and the aluminum conducting bars are reliably and electrically connected at the end of the rotor through a conductive connecting ring. The connection process adopts a step-by-step different process method of firstly welding the copper conducting bar at a high temperature and then welding or crimping the aluminum conducting bar at a low temperature, and plating treatment can be selectively carried out on the end part of the aluminum conducting bar, so that the problems of reliability and durability of dissimilar metal connection are effectively solved. According to the invention, through collaborative design of materials and structures, the cost is greatly reduced while the efficiency of the motor is remarkably improved (the efficiency level can reach IE4 and above), and the process is stable and suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and specifically to a high-efficiency hybrid copper-aluminum rotor motor. Background Technology

[0002] Squirrel-cage induction motors are widely used due to their simple structure and reliable operation. Traditional rotor bar materials are mainly pure aluminum or pure copper, each with its own advantages and disadvantages. Pure aluminum rotors (such as cast aluminum rotors) are low in cost and simple to manufacture, but aluminum has a high resistivity, resulting in high rotor losses (I²R losses) and low efficiency during motor operation. Pure copper rotors have excellent conductivity and low losses, but the raw material cost is high, and the high-temperature welding process between the copper end rings and the bars is complex, significantly increasing manufacturing costs.

[0003] To balance performance and cost, existing technologies have explored various approaches. For example, patent CN102044940A proposes mixing copper powder with liquid aluminum and then casting it into a mold, aiming to combine the advantages of both materials. However, in this approach, the copper and aluminum are merely physically mixed, making it impossible to precisely control the distribution of conductive paths within the rotor slots and failing to fully utilize the skin effect of the motor to optimize high-frequency performance. Another patent, CN106787554A, proposes an inner and outer double-cage structure, with the outer layer using a high-resistivity material to improve starting performance. However, this design still relies primarily on a single material (such as aluminum) and fails to fundamentally improve efficiency across all operating conditions through material combination. Furthermore, patent CN107659100B employs a copper sleeve with an aluminum core, but the copper sleeve and aluminum core have a simple inner and outer layer wrapping relationship, and their structure and process are fundamentally different from the layered parallel arrangement and step-by-step different process connection of this invention.

[0004] Therefore, how to optimize the spatial arrangement and electrical connection of copper and aluminum, two conductors with very different properties, in the rotor while ensuring connection reliability, so as to effectively control costs while significantly improving motor efficiency, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a high-efficiency hybrid copper-aluminum rotor motor. By arranging copper and aluminum conductor bars in layers according to specific rules within the rotor slots and employing an innovative end-connection process, the skin effect of the motor is actively utilized, thereby reducing rotor losses and significantly improving motor efficiency. Another purpose of this invention is to provide a method for manufacturing this motor to solve the technical bottleneck of reliable connection between dissimilar metals such as copper and aluminum, ensuring product consistency and long-term operational stability.

[0006] Technical Solution: This invention provides a high-efficiency hybrid copper-aluminum rotor motor, comprising: a stator and a rotor. The stator is wound with stator windings, and a motor housing is fitted around the outside of the stator. Bearings are provided at both the output end and the tail end. A pulley is connected to the output end bearing, and a cooling fan is connected to the tail end bearing. The motor housing includes a shell, a front end cover, and an inner end cover. The shell is located outside the stator, and a heat sink is provided on the outside of the shell. The front end cover and the inner end cover are respectively located at the input end and the tail end bearing position of the stator. A fan cover is also provided outside the inner end cover to cover the cooling fan. The rotor includes a rotor core and guide bars embedded in its slots. The guide bars are composed of a mixture of copper and aluminum guide bars. The copper guide bars are located in the upper and lower layers of the rotor slots, and the aluminum guide bars are located in the middle layer of the rotor slots. The copper and aluminum guide bars are reliably electrically connected at the ends of the rotor through conductive connecting rings, forming a complete rotor guide bar circuit.

[0007] Furthermore, in the aforementioned high-efficiency hybrid copper-aluminum rotor motor, the rotor slots have a multi-layered slot structure, with the ratio of slot depth H to slot width W being 2.5 to 5.0, and the copper and aluminum guide bars are arranged in layers along the slot depth direction.

[0008] Furthermore, in the aforementioned high-efficiency hybrid copper-aluminum rotor motor, the total cross-sectional area S_cu_top of the upper copper conductor bar and the total cross-sectional area S_cu_bottom of the lower copper conductor bar satisfy the following condition: 0.8 ≤ S_cu_top / S_cu_bottom ≤ 1.2.

[0009] Furthermore, in the aforementioned high-efficiency hybrid copper-aluminum rotor motor, the conductive connecting ring is made of copper or a copper alloy, and its inner side has a fitting groove that matches the shape of the end of the guide bar; the conductive connecting ring and the end of the copper guide bar are welded to form a first connection area, and the conductive connecting ring and the end of the aluminum guide bar are welded or pressed to form a second connection area.

[0010] Furthermore, in the aforementioned high-efficiency hybrid copper-aluminum rotor motor, a metal plating layer for improving connection performance is provided on the end surface of the aluminum conductor bar, wherein the metal plating layer is a nickel, zinc, or tin layer.

[0011] Furthermore, in the aforementioned high-efficiency hybrid copper-aluminum rotor motor, the total cross-sectional area of ​​the copper conductor bars accounts for 35%-65% of the total cross-sectional area of ​​all conductor bars, and the resistivity of the copper conductor bars is not greater than 1.8×10⁻⁻⁻⁶. 8 Ω·m.

[0012] Furthermore, in the aforementioned high-efficiency hybrid copper-aluminum rotor motor, the outer side of the conductive connecting ring is provided with heat dissipation fins or protrusions.

[0013] Furthermore, in the aforementioned high-efficiency hybrid copper-aluminum rotor motor, the rotor end is also provided with an adjustment ring for balancing or an insulating binding strip for fixing the end of the guide bar.

[0014] Furthermore, the aforementioned high-efficiency hybrid copper-aluminum rotor motor also provides a method for manufacturing the high-efficiency hybrid copper-aluminum rotor motor, comprising the following steps: S1: Prepare the rotor core, copper and aluminum conductor bars of predetermined shape, and perform surface treatment on the ends of the aluminum conductor bars; S2: The copper and aluminum conductor bars are inserted into the slots of the rotor core in sequence according to a preset positional relationship to form a layered conductor bar structure; S3: Assemble conductive connecting rings at both ends of the rotor core, so that the fitting grooves of the conductive connecting rings correspond to the ends of the copper and aluminum conductor bars; S4: Using segmented or synchronous heating, the conductive connecting ring is first welded to the ends of all copper conductors to form a strong first connection area; S5: Then, using a welding or pressing process different from that in step S4, the conductive connecting ring is connected to the surface-treated ends of all the aluminum conductors to form a second connection area. S6: Perform stress-relief annealing on the connected rotor assembly, and then assemble other accessories to complete the rotor manufacturing; S7: Assemble the rotor and stator, and perform overall impregnation insulation treatment to form the motor.

[0015] Furthermore, in the aforementioned high-efficiency hybrid copper-aluminum rotor motor, the welding in step S4 is high-frequency induction brazing or laser welding, using copper-based brazing filler metal; the welding in step S5 is low-temperature brazing or friction welding. When it is a press-fit process, the fitting groove of the conductive connecting ring forms a mechanical and electrical interlock with the end of the aluminum guide bar after press-fitting through cold forging deformation.

[0016] As can be seen from the above technical solution, the present invention has the following beneficial effects: The high-efficiency hybrid copper-aluminum rotor motor of the present invention arranges the high-conductivity copper conductors in the upper and lower layers where the current skin effect is most significant, while placing the lower-cost aluminum conductors in the middle layer. This structure actively guides current through a low-resistance copper path during motor startup and high-frequency operation, significantly reducing the rotor's equivalent AC resistance and copper loss, resulting in a significant improvement in overall motor efficiency (measured to IE4 and above). By optimizing the cross-sectional area ratio of copper conductors (35%-65%), it maximizes the use of low-cost aluminum materials while ensuring excellent electromagnetic performance, achieving near-all-copper rotor performance at a much lower cost, resulting in extremely high cost-effectiveness. The process of first welding copper at high temperature and then welding or pressing aluminum at low temperature fundamentally avoids problems such as thermal stress cracking and incomplete welding caused by the significant differences in melting point and thermal expansion coefficient when welding copper and aluminum simultaneously. The plating treatment at the ends of the aluminum conductors further inhibits electrochemical corrosion, ensuring the long-term stability and mechanical strength of the end electrical connections. The standardized process requires minimal modification to existing production lines, facilitating automated production and strict quality control. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a high-efficiency hybrid copper-aluminum rotor motor according to the present invention; Figure 2 This is a schematic diagram of the rotor of the present invention.

[0018] Reference numerals: 1: Stator; 11: Stator winding assembly; 12: Motor housing; 13: Bearing; 14: Pulley; 15: Cooling fan; 16: Fan cover; 121: Housing; 122: Front end cover; 123: Inner end cover; 1211: Frame heat sink; 2: Rotor; 21: Rotor core; 22: Conductor bar; 221: Copper conductor bar; 222: Aluminum conductor bar; 23: Conductive connecting ring. Detailed Implementation

[0019] Example 1 like Figure 1-2The high-efficiency hybrid copper-aluminum rotor motor shown includes: a stator 1 and a rotor 2; the structure of the stator 1 is similar to that of a conventional asynchronous motor, with a stator winding group 11 wound on it, and a motor housing 12 sleeved on the outside of the stator 1. The motor housing 12 is composed of a shell 121, a front end cover 122, and an inner end cover 123; wherein, the shell 121 covers the stator 1, and its outer side is cast with a base heat sink 1211 for enhancing heat dissipation; the front end cover 122 and the inner end cover 123 are respectively fixed to the two ends of the shell 121 by bolts to support the bearing 13; at the output end of the motor (i.e., the shaft extension end), a pulley 14 is installed on the outside of the bearing 13 for power output; at the tail end of the motor (non-shaft extension end), a cooling fan 15 is installed at the bearing 13, and the cooling fan 15 is covered with a fan cover 16 to guide the cooling airflow and ensure safety.

[0020] like Figure 2 The diagram shows a high-efficiency hybrid copper-aluminum rotor motor. The rotor 2 includes a rotor core 21 made of stacked silicon steel sheets and guide bars 22 embedded in its slots. The guide bars 22 are composed of a mixture of copper guide bars 221 and aluminum guide bars 222. Specifically, the slots on the rotor core 21 are deep slot structures with a slot depth H to slot width W ratio of 3.8, which is a multi-layer slot structure. The guide bars are arranged in layers along the slot depth direction: copper guide bars 221 are located in the upper and lower layers of the rotor slots, while the lower-cost aluminum guide bars 222 are located in the middle layer of the rotor slots.

[0021] In this embodiment, the total cross-sectional area (S_cu_top) of the upper copper conductor 221 is designed to be equal to the total cross-sectional area (S_cu_bottom) of the lower copper conductor 221, i.e., the ratio is 1.0. The total cross-sectional area of ​​all copper conductors 221 accounts for 55% of the total cross-sectional area of ​​all conductors 22 (the sum of copper and aluminum conductors). The resistivity of the copper conductors used is 1.7 × 10⁻ 8 Ω•m.

[0022] In this embodiment, at both ends of the rotor core 21, the copper conductor bar 221 and the aluminum conductor bar 222 are reliably electrically connected through an integral conductive connecting ring 23, thereby forming a complete rotor conductor bar circuit (squirrel cage); the conductive connecting ring 23 is made of T2 copper, and its inner side is precisely machined with fitting grooves that perfectly match the cross-sectional shape and arrangement of all the conductor bar 22 ends; in order to enhance end heat dissipation, a series of axial heat dissipation fins are machined on the outer circumference of the conductive connecting ring 23.

[0023] In this embodiment, the conductive connecting ring 23 is first connected to the ends of all copper conductors 221 via high-frequency induction brazing using copper-phosphorus brazing filler metal to form a strong first connection area. Then, the ends of the aluminum conductors 222 are nickel-plated to form a metallic coating, improving their solderability and corrosion resistance. Subsequently, a low-temperature tin-based brazing process is used to weld the conductive connecting ring 23 to the nickel-plated ends of all the aluminum conductors 222, forming a second connection area. This step-by-step connection method, which involves high-temperature copper welding followed by low-temperature aluminum welding, effectively avoids connection defects caused by differences in the melting points and thermal expansion coefficients of copper and aluminum.

[0024] In this embodiment, after the rotor 2 is assembled, an insulating binding tape is added to its end (outside the conductive connecting ring 23) to further strengthen the mechanical fixation of the guide bar end.

[0025] This embodiment also provides a method for manufacturing the above-mentioned motor, including the following steps: S1: Prepare laminations and stack them into rotor core 21, and simultaneously prepare copper conductor bars 221 and aluminum conductor bars 222 with predetermined cross-sectional shapes. Clean, activate, and electroplate nickel at both ends of the aluminum conductor bars 222; S2: The copper conductor bar 221 and the aluminum conductor bar 222 are inserted into the slots of the rotor core 21 in a preset order of "upper copper layer - middle aluminum layer - lower copper layer" to form a layered conductor bar structure. S3: Install conductive connecting rings 23 at both ends of the rotor core 21 to ensure that the fitting grooves on the inner side of the conductive connecting rings 23 are precisely aligned with the ends of all copper conductor bars 221 and aluminum conductor bars 222. S4: Using a segmented high-frequency induction heating method, the conductive connecting ring 23 is simultaneously brazed to the ends of all copper conductor bars 221. After the brazing filler fills the gaps, a dense and high-strength first connection area is formed. S5: A low-temperature flame brazing process, different from S4, is used, with tin-based brazing filler metal and special flux, to weld the conductive connecting ring 23 to the nickel-plated ends of all aluminum conductors 222 to form a second connection area; S6: Perform overall stress-relief annealing on the welded rotor assembly to eliminate welding stress. Then install accessories such as insulating straps and balance rings to complete the manufacturing of rotor 2; S7: The rotor 2 is assembled with the assembled stator 1, the air gap is adjusted, and then the entire motor stator (including the winding) is subjected to vacuum pressure impregnation (VPI) insulation treatment. After drying and curing, the front end cover, bearing, fan and other components are assembled to finally form the high-efficiency hybrid copper-aluminum rotor motor. Tests have shown that the motor using the structure of this embodiment has a rotor equivalent AC resistance that is about 40% lower than that of an all-aluminum rotor of the same specification when running at 50Hz. The overall efficiency of the motor meets the requirements of IE4 energy efficiency level, while the manufacturing cost is significantly lower than that of an all-copper rotor motor.

[0026] Example 2 Based on Example 1, in this example, the depth-to-width ratio (H / W) of the rotor slot is designed to be 4.5, the total cross-sectional area ratio of the copper conductor 221 is adjusted to 40%, and the cross-sectional area ratio of the upper copper conductor to the lower copper conductor is 0.9; the conductive connecting ring 23 is made of copper alloy (such as chromium zirconium copper) to improve its strength and heat resistance.

[0027] In this embodiment, the surface treatment of the end of the aluminum guide bar 222 is changed to hot-dip tin plating. In terms of connection process, the first connection area (copper-copper connection) adopts laser welding to achieve fast and precise deep penetration welding. For the second connection area (copper ring-aluminum guide bar connection), a pressing process is adopted. Specifically, in the area of ​​the interlocking groove of the conductive connecting ring 23 corresponding to the aluminum guide bar 222, a slight interference is designed. After the conductive connecting ring 23 is pressed onto the end of the guide bar, a special mold is used to cold forge (local radial forging) the position of the outer side of the connecting ring corresponding to the aluminum guide bar, so that the copper ring material undergoes plastic deformation, tightly wraps and bites the end of the aluminum guide bar, forming a mechanical and electrical double interlocking connection, completely avoiding the heat effect of welding.

[0028] In this embodiment, the manufacturing method is adjusted accordingly: in step S4, the copper guide strip is laser-welded; in step S5, after the connecting ring is pressed in using a hydraulic press, it is then cold-forged to form an interlocking connection with the aluminum guide strip. The remaining steps are similar to those in Embodiment 1. This method is particularly suitable for applications requiring extremely high connection reliability or where complex welding processes are not suitable for the production site. The contact resistance of this press-fit connection is low and stable, the motor also exhibits high efficiency characteristics, and the process is easier to automate production control.

[0029] It should be noted that the above description is merely a technical solution of the invention and not a limitation. Although the invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the invention without departing from the scope of the invention, and all such modifications and substitutions should be covered within the scope of the claims of the invention.

Claims

1. A high-efficiency hybrid copper-aluminum rotor motor, characterized in that: include A stator (1) is provided with a stator winding assembly (11) and a motor housing (12) is provided on the outside of the stator (1). Bearings (13) are provided at the output end and the tail end. A pulley (14) is connected to the output end bearing (13), and a cooling fan (15) is connected to the tail end bearing (13). The motor housing (12) includes a housing (121), a front end cover (122), and an inner end cover (123). The housing (121) is provided outside the stator (1), and a heat sink (1211) is provided on the outside of the housing (121). The front end cover (122) and the inner end cover (123) are respectively provided at the input end and the tail end bearing (13) of the stator (1). A fan cover (16) is also provided on the outside of the inner end cover (123) to cover the cooling fan (15). The rotor (2) includes a rotor core (21) and guide bars (22) embedded in its slots. The guide bars (22) are composed of a mixture of copper guide bars (221) and aluminum guide bars (222). The copper guide bars (221) are located in the upper and lower layers of the rotor slots, and the aluminum guide bars (222) are located in the middle layer of the rotor slots. The copper guide bars (221) and the aluminum guide bars (222) are reliably electrically connected at the ends of the rotor through conductive connecting rings (23) to form a complete rotor guide bar circuit.

2. The high-efficiency hybrid copper-aluminum rotor motor according to claim 1, characterized in that: The rotor slot has a multi-layered slot structure, with a slot depth (H) to slot width (W) ratio of 2.5 to 5.

0. The copper guide bar (221) and aluminum guide bar (222) are arranged in layers along the slot depth direction.

3. The high-efficiency hybrid copper-aluminum rotor motor according to claim 2, characterized in that: The total cross-sectional area (S_cu_top) of the upper copper conductor (221) and the total cross-sectional area (S_cu_bottom) of the lower copper conductor (221) satisfy: 0.8 ≤ S_cu_top / S_cu_bottom ≤ 1.

2.

4. The high-efficiency hybrid copper-aluminum rotor motor according to claim 1, characterized in that: The conductive connecting ring (23) is made of copper or copper alloy, and its inner side is provided with a fitting groove that matches the shape of the end of the guide bar (22). The conductive connecting ring (23) and the end of the copper guide bar (221) are welded to form a first connection area, and the conductive connecting ring (23) and the end of the aluminum guide bar (222) are welded or pressed to form a second connection area.

5. The high-efficiency hybrid copper-aluminum rotor motor according to claim 4, characterized in that: On the end surface of the aluminum guide strip (222), there is a metal plating layer for improving the connection performance, the metal plating layer being a nickel, zinc, or tin layer.

6. The high-efficiency hybrid copper-aluminum rotor motor according to claim 1, characterized in that: The total cross-sectional area of ​​the copper conductor (221) accounts for 35%-65% of the total cross-sectional area of ​​all conductors (22), and the resistivity of the copper conductor (221) is not greater than 1.8×10⁻ 8 Ω·m.

7. The high-efficiency hybrid copper-aluminum rotor motor according to claim 1, characterized in that: The conductive connecting ring (23) has heat dissipation fins or protrusions on its outer side.

8. The high-efficiency hybrid copper-aluminum rotor motor according to claim 1, characterized in that: The rotor (2) is also provided with an adjustment ring for balancing or an insulating binding strip for fixing the end of the guide bar.

9. A method for manufacturing a high-efficiency hybrid copper-aluminum rotor motor as described in any one of claims 1-8, characterized in that, Includes the following steps: S1: Prepare rotor core (21), copper conductor bar (221) and aluminum conductor bar (222) of predetermined shape, and perform surface treatment on the end of aluminum conductor bar (222); S2: The copper guide bar (221) and aluminum guide bar (222) are inserted into the slots of the rotor core (21) in sequence according to a preset positional relationship to form a layered guide bar structure; S3: Assemble conductive connecting rings (23) at both ends of the rotor core (21) so that the fitting groove of the conductive connecting ring (23) corresponds to the ends of the copper conductor (221) and the aluminum conductor (222); S4: Using segmented or synchronous heating, the conductive connecting ring (23) is first welded to the ends of all copper conductors (221) to form a solid first connection area; S5: Then, using a welding or pressing process different from step S4, the conductive connecting ring (23) is connected to the surface-treated ends of all aluminum conductors (222) to form a second connection area; S6: Perform stress-relief annealing on the connected rotor assembly, and then assemble other accessories to complete the manufacturing of rotor (2); S7: Assemble the rotor (2) and stator (1) and perform overall impregnation insulation treatment to form the motor.

10. The manufacturing method according to claim 9, characterized in that: The welding in step S4 is high-frequency induction brazing or laser welding, using copper-based brazing filler metal; the welding in step S5 is low-temperature brazing or friction welding. When it is a press-fit process, the fitting groove of the conductive connecting ring (23) forms a mechanical and electrical interlock with the end of the aluminum guide strip (222) through cold forging deformation after press fitting.

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