Stator structure and method for shielding motor

Abstract

The invention discloses a stator structure and method for a shielded motor. The stator structure for the shielded motor comprises an integral stator iron core which is formed by laminating and fixedly connecting a plurality of split punching sheets; and the mould pressing ring type coil is embedded in the wire slot of the stator iron core. According to the scheme, stator inserting is carried out by adopting a structure that the mould pressing ring type coil and the split stator punching sheets are matched, the inner circle of the stator can be reduced to any size theoretically, the medium friction loss of a rotor can be greatly reduced, the motor efficiency is improved, and the weight of the whole machine is reduced.

Description

Technical Field

[0001] This invention relates to the field of shielded motor technology, and specifically to a stator structure and method for a shielded motor. Background Technology

[0002] Shielded motors, due to their unique advantages such as zero leakage and high reliability, are widely used in nuclear power, petroleum, chemical, and coal-fired power industries, and have become core equipment in energy and mechanical drive scenarios. At the same power rating, high-voltage (6kV and above), 2-pole or higher speed shielded motors have significant advantages over low-voltage, multi-pole shielded motors in terms of unit weight and overall efficiency. However, the stator manufacturing process of shielded motors is constrained by factors such as the large span of the coiled coils, the small inner diameter of the motor, and the compact internal structure, encountering many operational bottlenecks and severely restricting large-scale mass production.

[0003] In existing technologies, the coil turns of shielded motors with high voltage, two poles, or higher speeds often reach 20 or more. Figure 1 As shown: The span between the upper and lower edges of the coil is large (GAMA1+GAMA2), generally exceeding 120°, and the span distance is large (A3B1 value), which exceeds the inner diameter of the stator core (2RI). A single coil can no longer pass through the bore smoothly, and the traditional stator manufacturing method is no longer feasible.

[0004] Currently, there are no industrial applications of shielded motors exceeding 6kV-2 pole speed or higher. High-voltage 4-pole shielded motors have already seen large-scale industrial applications. Their stator cores are made by stacking whole round stator laminations, and the motors are then manufactured within the stator core. The specific technical solution is as follows: Because the rotor of a shielded motor rotates in a medium, it generates significant frictional losses. To ensure motor efficiency, the inner diameter of the stator is generally small. Currently, the stators of high-voltage 4-pole shielded motors are made using pre-formed half-coil coils or strip-shaped wire bars. The ends of the coils are manually bent (for pre-formed half-coil coils) and welded together to form a coil. While this method offers advantages such as "convenient production" and "high winding efficiency," as the number of coil turns increases, length control after end welding becomes difficult, the amount of end welding increases dramatically, the risk of welding defects intensifies, and the thermal shock from high-frequency, high-temperature welding accelerates coil insulation aging, leading to a high risk of localized insulation damage.

[0005] In summary, existing technical solutions have problems such as high cost and high quality risk when applied to shielded motors with high voltage -2 poles or higher speeds, making them difficult to mass-produce. Summary of the Invention

[0006] In view of this, the object of the present invention is to provide a stator structure and method for a shielded electric motor, which aims to overcome at least one related technical problem existing in the background art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, this application provides a stator structure for a shielded electric motor, comprising: An integral stator core composed of multiple stacked and fixedly connected segmented laminations; and A molded coil embedded in the slot of the stator core.

[0008] The stator structure provided by this application is characterized by its stator core being an integral structure formed by stacking multiple segmented laminations and then fixing them together; the molded coil is directly embedded in the groove formed by the core.

[0009] Specifically, during assembly, the coil is first positioned, and then the segmented laminations are assembled and stacked one by one from their radial outer sides. Finally, all the segmented laminations are fixed into a rigid, integral iron core through a joining process. The coil is then encased and secured inside the finally formed integral iron core.

[0010] This invention innovatively transforms the traditional integral iron core into a structure composed of segmented laminations. This design alters the assembly path—changing from the traditional "coil passing through the inner circle of the iron core" to "the iron core wrapping around the coil from the outside"—thus overcoming the limitation imposed by the stator's inner diameter on the coil span. This, in turn, solves the fundamental technical problem that large-span, high-rigidity molded coils cannot pass through a small-inner-diameter integral iron core.

[0011] To achieve optimal assembly roundness, structural symmetry, and process maturity, in one optional embodiment, the segmented lamination is a fan-shaped lamination.

[0012] In order to achieve the integration of segmented iron cores in a simple, reliable and low-cost manner, in one optional embodiment, the segmented laminations are provided with connecting grooves, and the stator iron core is fixed by welding with tie rods passing through the connecting grooves to form the integral structure.

[0013] To ensure precise and accurate positioning of each lamination layer and segment during the stacking process, thereby guaranteeing the coaxiality and dimensional accuracy of the final stator's inner and outer circles and grooves, in one optional embodiment, the segmented laminations are provided with positioning holes for interlayer positioning during stacking. Precise circumferential and radial positioning of each lamination can be provided by passing positioning pins (or positioning rods) through these positioning holes.

[0014] For example, the positioning hole can be a round hole, a square hole, or other irregularly shaped hole, and the positioning element can also be a positioning pin, a positioning key, etc.

[0015] In order to maximize the mechanical strength and stiffness of the overall core and eliminate magnetic circuit inhomogeneities that may be caused by the segmented joints, in an optional embodiment, the segmented laminations are stacked in an alternating manner between adjacent layers.

[0016] To prevent the sharp edges of the metal laminations from scratching or abrading the fragile insulation layer on the coil surface during assembly, in one optional embodiment, a protective groove liner is provided between the straight section surface of the molded coil and the inner wall of the slot. The groove liner acts as a separator, filling the space between the coil and the laminations. This groove liner provides cushioning and protection during assembly and is a key measure to ensure insulation reliability after the coil is finished.

[0017] The liner can be a conductive material (such as carbon-containing polyimide) to discharge static electricity, or it can be an insulating material (such as DMD insulating paper); the form can be a pre-formed liner or a wrapped insulating tape.

[0018] Secondly, this application also provides a method for forming a shielded motor stator, comprising the following steps: Multiple molded coils are pre-fixed as a whole according to their final positions in the wire groove; From the radially outer side of the molded coil, the segmented stator laminations and pressure rings are assembled; The segmented laminations are pressed together to form a stator core; The stacked segmented structures are fixedly connected and driven into slot wedges to form an integral stator structure.

[0019] In order to achieve precise positioning and stable maintenance of the coil group in space, in an optional embodiment, the step of pre-fixing the molded coil as a whole is as follows: using a sling to suspend the molded coil on a rotatable bracket, and adjusting the spatial position of the molded coil by adjusting the rotatable bracket and the sling, that is, adjusting the molded coil so that the bottom of the inclined side is located on the upper surface of the bottom bracket.

[0020] In an alternative embodiment, after pre-fixing the molded coil and before assembling the segmented laminations, the step further includes wrapping a protective groove liner around the surface of the straight segment of the molded coil.

[0021] In order to obtain a connection method with high connection strength, good reliability and suitable for large metal structures such as motor cores, in an optional embodiment, the step of fixing the segmented structure is achieved by welding.

[0022] The beneficial effects that the stator structure and method for a shielded electric motor disclosed in this application may bring include, but are not limited to: 1. Overcoming the limitation of stator inner diameter on coil span: By using the reverse assembly method of "coil first, core later", the problem of large-span molded coils being unable to be installed in small-diameter stators is fundamentally solved, making it possible to use higher-performance molded coils in high-voltage, 2-pole or higher-speed shielded motors.

[0023] 2. Significantly improved motor efficiency and power density: Because the stator inner circle can be designed to be smaller, the rotor diameter is correspondingly reduced, thereby significantly decreasing frictional losses generated when the rotor rotates in the medium. Simultaneously, the precise dimensions and uniform spacing of the molded coil ends help reduce end leakage reactance and stray losses. These two factors work together to effectively improve overall machine efficiency, reduce unit weight, and achieve higher power density.

[0024] 3. Eliminates quality risks associated with end welding: Compared to existing half-coil or strip-type coil solutions, the molded coil used in this invention has an integral structure. No welding is required at the coil ends during or after stator winding. This completely avoids the risks of defects such as incomplete welds and slag inclusions caused by welding, and also eliminates the aging and damage to the coil insulation caused by high-temperature welding thermal shock, greatly improving the insulation reliability and long-term lifespan of the product.

[0025] 4. Ensures insulation reliability during manufacturing: By pre-setting protective slots in the straight sections of the coils and fixing all coils before assembly, it effectively prevents hard metal laminations from scratching or squeezing the coil insulation during the stacking process. This allows for maintaining an extremely high first-pass yield and insulation consistency even for high-voltage motors with many turns and high insulation requirements in mass production.

[0026] 5. Improved production efficiency, suitable for mass production: This method transforms the complex internal coil embedding process into a standardized external lamination and welding process. The process steps are clear and easy to mechanize and automate. Compared with traditional manual bending and welding processes, the production cycle is shortened, consistency is better, and quality is controllable, laying the foundation for the mass production of high-voltage, high-speed shielded motors. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a coil in the prior art of this invention.

[0028] Figure 2 This is a schematic diagram of the hoisting and arrangement of the coil of the present invention.

[0029] Figure 3 This is a schematic diagram of the segmented punching sheet of the present invention.

[0030] Figure 4 This is a schematic diagram of the straight section of the coil of the present invention.

[0031] Figure 5 This is a general outline drawing of the stator of the present invention.

[0032] The labels in the diagram are as follows: 1-Rotating bracket, 2-Hanging rope, 3-Molded coil, 4-Segmented punch, 5-Bottom bracket, 6-Stretcher groove, 7-Positioning hole, 8-Coil groove, 9-Wedge groove. Detailed Implementation

[0033] Various exemplary embodiments, features, and aspects of this application will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0034] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0035] like Figure 2 As shown, in a first aspect, this application provides a stator structure for a shielded electric motor, comprising: An integral stator core consisting of multiple segmented laminations 4 stacked and fixedly connected; and a molded coil 3 embedded in the slot of the stator core.

[0036] The stator structure provided by this application is characterized by its stator core being an integral structure formed by stacking multiple segmented laminations 4 and then fixing them together; the molded coil 3 is directly embedded in the groove formed by the stator core.

[0037] Specifically, during assembly, the coil is positioned first, and then the segmented laminations 4 are assembled and stacked one by one from their radial outer sides. Finally, all the segmented laminations 4 are fixed into a rigid integral iron core through a connection process. The coil is wrapped and secured inside the finally formed integral iron core.

[0038] This invention innovatively transforms the traditional integral iron core into a structure composed of segmented laminations 4. This design alters the assembly path—changing from the traditional "coil passing through the inner circle of the iron core" to "the iron core wrapping around the coil from the outside"—thus overcoming the limitation imposed by the stator's inner diameter on the coil span. This, in turn, solves the fundamental technical problem that large-span, high-hardness molded coils 3 cannot pass through a small-inner-diameter integral iron core.

[0039] like Figure 3As shown, in order to obtain optimal assembly roundness, structural symmetry, and process maturity, the segmented lamination 4 in some embodiments is a fan-shaped lamination. Fan-shaped laminations experience uniform stress during stacking, are easy to process on industry-standard stamping dies, and can most effectively assemble into a near-perfect circle, ensuring the roundness of the stator's inner circle.

[0040] The stator cross-section composed of sector-shaped laminations is as follows Figure 4 As shown, the multi-lobed fan-shaped laminations are assembled into a complete circle. To ensure overall rigidity, the lobed laminations 4 are stacked in 1 / 2 layers.

[0041] It should be noted that the specific shape of the segmented punch 4 is not limited to a fan shape. Theoretically, any shape that can be pieced together to form a ring, such as polygonal segments, is an equivalent alternative of the present invention.

[0042] In order to achieve the integration of the segmented iron core in a simple, reliable and low-cost manner, in some embodiments the segmented lamination 4 is provided with a connecting groove, and the stator iron core is fixed by welding the tie rods inserted in the connecting groove to form the integral structure.

[0043] Specifically, after the stacking is completed, the tie rods (usually round or flat steel) are inserted into the connecting grooves at the corresponding positions of all the stampings. Then, multi-point welding is performed at the contact points between the tie rods and the stampings, and the shrinkage stress of the weld is used to firmly pull the segmented stampings 4 together as one.

[0044] A "stirring and welding" solution was adopted. This method not only provides strong connection strength to prevent the laminations from springing back or loosening during operation, but also effectively transmits magnetic vibration and thermal stress in the core.

[0045] To ensure precise and accurate positioning of each lamination layer and segment during the stacking process, thereby guaranteeing the coaxiality and dimensional accuracy of the final stator's inner and outer circles and grooves, some embodiments provide positioning holes 7 on the segmented laminations 4 for interlayer positioning during stacking. Precise circumferential and radial positioning of each lamination can be provided by passing positioning pins (or positioning rods) through these positioning holes 7.

[0046] For example, the positioning hole 7 can be a round hole, a square hole, or other irregularly shaped hole, and the positioning element can also be a positioning pin, a positioning key, etc.

[0047] In addition, the segmented punch 4 has a coil groove 8 on the side facing the central corner, which is used to place the straight section of the molded coil 3. The surface of the molded coil 3 is covered with a conductive groove liner to prevent the fan-shaped segmented punch 4 from damaging the molded coil 3.

[0048] Meanwhile, a slot wedge 9 is also provided at the opening of the coil slot 8. After the stator is finished, a slot wedge is installed at this location to ensure that there are no sharp points on the inner diameter of the stator. Figure 3As shown.

[0049] To maximize the overall mechanical strength and stiffness of the core and eliminate magnetic circuit inhomogeneities that may result from the segmented joints, in some embodiments the segmented laminations 4 are stacked in an alternating manner between adjacent layers. This structure effectively homogenizes the magnetic circuit, reduces iron losses and noise, and makes the core a more isotropic whole.

[0050] During the stacking process, each sheet of the second layer overlaps the seam between the two sheets of the first layer, just like laying bricks, thus staggering the seams between the layers.

[0051] Optionally, the staggered ratio can be 1 / 2, 1 / 3, or other fractions; the key is to stagger the seams between different layers.

[0052] To prevent the hard metal lamination edges from scratching or abrading the fragile insulation layer on the coil surface during assembly, in some embodiments, a protective groove liner is provided between the straight section surface of the molded coil 3 and the inner wall of the slot. The groove liner acts as a separator, filling the space between the molded coil 3 and the lamination. This groove liner plays a buffering and protective role during assembly and is a key measure to ensure insulation reliability after the coil is finished.

[0053] The liner can be a conductive material (such as carbon-containing polyimide) to discharge static electricity, or it can be an insulating material (such as DMD insulating paper); the form can be a pre-formed liner or a wrapped insulating tape.

[0054] Secondly, this application also provides a method for forming a shielded motor stator, comprising the following steps: Multiple molded coils 3 are pre-fixed as a whole according to their final positions in the wire groove; From the radially outer side of the molded coil 3, the segmented stator laminations and pressure rings are assembled; The segmented laminations 4 are pressed together to form a stator core; The stacked segmented structures are fixedly connected and driven into slot wedges to form an integral stator structure.

[0055] To ensure the coaxiality of the stator's inner circle during the lamination process, locating pins are used for segmented positioning of the interlayer laminations, preventing stator winding misalignment or positioning interference during lamination. After stator lamination is completed, tie rods are welded to the back of the laminations to form a complete stator. See [link / reference]. Figure 5 .

[0056] Then, in accordance with the requirements of the insulation specifications, withstand voltage tests and coil turn-to-turn insulation withstand voltage tests are conducted, and the insulation resistance and polarization index of the windings are measured to check whether the coil insulation is damaged or destroyed during the stacking process.

[0057] To solve the assembly challenge of fitting pre-formed, large-span coils into a small space, this invention innovatively sets the assembly process as a reverse assembly logic from the inside out: first fixing the coil, then constructing the core. This method bypasses the physical limitation of the coil passing through the core, making it possible to use large-span molded coils within a small stator. The core of this method lies in the process sequence, and various options are available for the specific fixing and connection methods.

[0058] To achieve precise positioning and stable maintenance of the coil group in space, in some embodiments, the step of pre-fixing the molded coil 3 as a whole involves: suspending the molded coil 3 on a rotatable bracket 1 using a suspension rope 2; adjusting the spatial position of the molded coil 3 by adjusting the rotatable bracket 1 and the suspension rope 2, specifically adjusting the molded coil 3 so that the bottom of its inclined side is located on the upper surface of the bottom bracket 5. This method provides flexible multi-degree-of-freedom adjustment capabilities, ensuring that the positional relationship of all coils is consistent with the design.

[0059] Specifically, by adjusting the angle of the rotatable bracket 1 and the length of the suspension rope 2, the straight section and end of each coil can be adjusted to the designed position, laying the foundation for the smooth assembly of subsequent laminations.

[0060] It should be noted that the lifting rope 2 will be removed before the slot wedge is driven in, because at this time, the split punch 4 has already been fixed.

[0061] In some embodiments, after pre-fixing the molded coil 3 and before assembling the segmented laminations 4, the method further includes the step of wrapping a protective groove liner around the surface of the straight section of the molded coil 3. This step is to proactively protect the coil insulation during the lamination assembly stage, making it an essential pre-process to fundamentally avoid quality risks caused by insulation damage.

[0062] To achieve a connection method with high strength, reliability, and suitability for large metal structures such as motor cores, in some embodiments, the step of fixing the segmented structure is achieved through welding. Welding can form a permanent rigid connection, effectively resisting electromagnetic forces and thermal stress.

[0063] The core of the working principle of this invention lies in resolving the physical contradiction between the "large-span molded coil 3" and the "small-sized stator inner circle" in high-voltage, high-speed shielded motors through the synergistic effect of structural and technological innovation. Its working principle can be understood from the following two perspectives: 1. The principle of reverse assembly from the inside out: Traditional stator manufacturing follows a "core first, coil later" approach, meaning the stator core is manufactured as a single unit, and then the coil is inserted into the slot through the inner circumference of the core. This method is not feasible for large-sized molded coils with a span exceeding the stator's inner diameter. This invention overturns this sequence, employing a reverse assembly logic of "fixing the coil first, then constructing the core."

[0064] Specifically, firstly, all the molded coils 3 are precisely hoisted and fixed in space according to their final electrical positions, forming a virtual "stator winding skeleton". Then, the segmented laminations are assembled like assembling... Figure 1 Generally, the laminations are inserted and stacked one by one from the radial outside of the fixed winding frame. Finally, the segmented laminations are solidified into a rigid, integral stator core through connection methods such as welding tie rods. This method perfectly avoids the step of "passing through the bore" of the coil, eliminating the assembly bottleneck from a physical perspective.

[0065] 2. The structural formation principle of "segmented integration": The stator structure of this invention is not a pre-existing whole, but rather integrates from a decomposable, segmented state into a high-strength whole. The segmented laminations 4 are a prerequisite for reverse assembly, allowing the core assembly path to proceed from outside the coils. The positioning holes 7 and the staggered laminations ensure that the segments and layers of laminations maintain precise relative positions during the dispersed assembly process, thereby guaranteeing the geometric accuracy and coaxiality of the final stator's inner circle, outer circle, and slot shape. This is fundamental to ensuring uniform electromagnetic performance and smooth operation of the motor.

[0066] Tie welding is a key step in realizing the transformation from "separation" to "integration". By applying strong mechanical constraints to the back of the laminations, it makes the dispersed laminations into a whole that will not loosen under electromagnetic force and mechanical vibration, thus ensuring the rigidity of the stator structure and long-term operational reliability.

[0067] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A stator structure for a shielded electric motor, characterized in that, include: An integral stator core consisting of multiple segmented laminations (4) stacked and fixedly connected; as well as A molded coil (3) is embedded in the slot of the stator core.

2. The stator structure as described in claim 1, characterized in that, The segmented punch (4) is a fan-shaped punch.

3. The stator structure as described in claim 1 or 2, characterized in that, The segmented lamination (4) is provided with a connecting groove, and the stator core is fixed by welding the tie rods inserted in the connecting groove to form the integral structure.

4. The stator structure as described in claim 1 or 2, characterized in that, The segmented punch (4) is provided with positioning holes (7) for interlayer positioning during stacking.

5. The stator structure as described in claim 4, characterized in that, The segmented punches (4) are stacked in an alternating manner between adjacent layers.

6. The stator structure as described in claim 1, characterized in that, A protective groove liner is provided between the straight section surface of the molded coil (3) and the inner wall of the groove.

7. A method for forming a shielded motor stator, used to manufacture the stator structure according to any one of claims 1-6, characterized in that, Includes the following steps: Multiple molded coils (3) are pre-fixed as a whole according to their final positions in the wire groove; From the radial outside of the molded coil (3), the segmented stator laminations and pressure rings are assembled; The segmented laminations (4) are pressed together to form a stator core; The stacked segmented structures are fixedly connected and driven into slot wedges to form an integral stator structure.

8. The molding method as described in claim 7, characterized in that, The step of pre-fixing the molded coil (3) as a whole is as follows: use a rope (2) to suspend the molded coil (3) on a rotatable bracket (1), and adjust the spatial position of the molded coil (3) by adjusting the rotatable bracket (1) and the rope (2), that is, adjust the molded coil (3) so that the bottom of the inclined side is located on the upper surface of the bottom bracket (5).

9. The molding method as described in claim 7 or 8, characterized in that, After the pre-fixed molded coil (3) and before the assembly of the split lamination (4), the step of wrapping a protective groove liner on the surface of the straight section of the molded coil (3) is also included.

10. The molding method as described in claim 7, characterized in that, The step of fixing the segmented structure together is achieved by welding.

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