Oil-cooled motor stator lamination and optimized design method thereof

Abstract

The application belongs to the technical field of electric drive of new energy vehicles, and discloses an oil-cooled motor stator lamination and an optimization design method thereof. The stator lamination comprises an annular lamination base body, a plurality of cooling structures are arranged on the outer circumferential side of the annular lamination base body, and a plurality of electromagnetic structures are arranged on the inner circumferential side of the annular lamination base body. Each cooling structure comprises a rhomboid structure and a circular structure. The long axis of the rhomboid structure is arranged in the circumferential direction, the short axis of the rhomboid structure is arranged in the radial direction, and the rhomboid structure has a first chamfer R1 in the long axis direction and a second chamfer R2 in the short axis direction. The cooling structure composed of the rhomboid structure and the circular structure is arranged on the outer circumferential side, the non-circular geometric shape of the rhomboid structure generates turbulent disturbance when the cooling liquid flows through, the thermal boundary layer is destroyed, the convective heat transfer efficiency is enhanced, and the heat dissipation requirement of the high-power-density motor is effectively met. The application also provides an optimization design method. The optimal chamfer ratio is determined by establishing a plurality of comparative models with different chamfer ratios and performing finite element simulation.

Description

Technical Field

[0001] This invention belongs to the field of electric drive technology for new energy vehicles, and specifically relates to an oil-cooled motor stator lamination and its optimized design method. Background Technology

[0002] As the market share of new energy vehicles increases year by year, clearer development requirements have been put forward for the environmentally friendly and energy-saving technology roadmap of new energy vehicles. From the initial air-cooled motors to water-cooled motors, and now to oil-cooled motors, the market and various OEMs have increasingly higher requirements for the speed, efficiency and continuous output capability of drive motors, posing a huge challenge to the cooling of drive motors.

[0003] The stator core of existing oil-cooled motors is made of laminations, and the oil grooves are mostly square with rounded corners distributed around the perimeter. The main shortcomings are as follows: First, the cooling efficiency is low. The flow channels of the square rounded corners are straight, and the coolant is difficult to form turbulence, resulting in insufficient heat exchange and difficulty in meeting the heat dissipation requirements of high power density motors. Second, the stress concentration is serious. The square corners are prone to stress concentration. When the interference fit is used, the stress is deeply transmitted radially, which can easily lead to core deformation or cracking.

[0004] Therefore, those skilled in the art urgently need to develop an oil-cooled motor stator lamination with both high cooling efficiency and low stress transmission, as well as its optimized design method. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides an oil-cooled motor stator lamination and its optimized design method.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The present invention provides an oil-cooled motor stator lamination, comprising an annular lamination base, wherein the outer periphery of the lamination base is provided with multiple sets of cooling structures distributed circumferentially, and the inner periphery of the lamination base is provided with multiple sets of electromagnetic structures distributed circumferentially. Each group of cooling structures includes a rhomboid structure and a circular structure; The major axis of the rhombic structure is arranged along the circumference of the lamination substrate, and the minor axis of the rhombic structure is arranged along the radial direction of the lamination substrate; The rhomboid structure has a first chamfer R1 and a second chamfer R2, wherein the first chamfer R1 is set along the major axis of the rhomboid structure and the second chamfer R2 is set along the minor axis of the rhomboid structure.

[0007] A further provision is provided that a partition bridge is provided between the rhomboid structure and the circular structure to block the stress transmission path, thereby forcing stress concentration and dispersing it by the rhomboid structure.

[0008] Further configured such that the two adjacent sets of partition bridges are symmetrically arranged about the line connecting the center of the circular structure and the center of the lamination substrate, and / or that the two adjacent sets of partition bridges are symmetrically arranged about the line connecting the center of the rhomboid structure and the center of the lamination substrate.

[0009] Further configured, the width of the partition bridge is in the range of 0.8mm to 1.5mm.

[0010] Further configured, each group of electromagnetic structures includes structural teeth, structural grooves and structural yokes, the structural teeth are evenly distributed circumferentially, and structural grooves with inward openings are provided between adjacent groups of structural teeth.

[0011] A further configuration is that the width of the root of the structural tooth is greater than the width of its tip.

[0012] This invention also provides an optimized design method for stator laminations of oil-cooled motors, applied to the stator laminations of oil-cooled motors as described above, comprising the following steps: Multiple sets of chamfered ratio oil-cooled drive motor stator lamination 3D comparison models were created using 3D modeling software. At the same time, a traditional square rounded corner oil groove stator lamination 3D model was created as a reference model. The three-dimensional comparison models and the reference model are stacked to form the corresponding stator core models; Preset boundary conditions and loads are applied to each of the stator core models to simulate the interference fit between the motor housing and the stator core. Finite element simulation calculations were performed on each of the stator core models, and the equivalent stress cloud diagrams of each model in the radial direction of the stator core were extracted. By comparing the stress cloud diagrams of each of the three-dimensional comparison models with the reference model, the stress transfer characteristics under different chamfer ratios are analyzed. Based on the comparison results of stress transfer characteristics, the optimal chamfer ratio is determined.

[0013] Further configured, the three-dimensional model of the traditional square rounded corner oil groove stator lamination and the three-dimensional model of the oil-cooled drive motor stator lamination have the same overall external dimensions and electromagnetic structure parameters.

[0014] Further, the establishment of multiple sets of three-dimensional comparison models of oil-cooled drive motor stator laminations with different chamfer ratios includes: Using the first chamfer R1 of a fixed rhomboid structure as a reference value, the ratio of the second chamfer R2 to the first chamfer R1 is changed to establish multiple sets of three-dimensional comparison models with different chamfer ratios.

[0015] Further configured, the step of applying preset boundary conditions and loads to each of the stator core models to simulate the interference fit between the motor housing and the stator core includes: Cylindrical support boundary conditions are set on the inner surface of each stator core model to simulate housing clamping, and the preset interference fit between the housing and the stator core is input.

[0016] A further step is to apply preset boundary conditions and loads to each of the stator core models to simulate the interference fit between the motor housing and the stator core, which also includes: A preset inward uniform pressure is applied to the outer diameter surface of each stator core model to equivalently simulate the radial compressive stress generated by the interference fit.

[0017] Compared with the prior art, the present invention has the following advantages: 1. This invention provides a cooling structure composed of a combination of rhomboid and circular structures on the outer periphery of the lamination substrate. The non-circular geometry of the rhomboid structure causes turbulence disturbance when the coolant flows through it, which disrupts the thermal boundary layer, enhances convective heat transfer efficiency, and effectively meets the heat dissipation requirements of high power density motors.

[0018] 2. The first chamfer R1 and the second chamfer R2 in the rhomboid structure of the present invention work together to cause the interference stress to deflect circumferentially and release radial gradient. At the same time, a partition bridge is provided between the rhomboid structure and the circular structure to block the continuous stress transmission path, forcing the stress to concentrate in the rhomboid structure area and disperse it through the chamfer, significantly reducing the radial stress transmission depth and avoiding core deformation or cracking.

[0019] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0020] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A schematic diagram of the stator lamination structure of the present invention is shown; Figure 2 A three-dimensional structural schematic diagram of the present invention is shown; Figure 3 A partial structural schematic diagram of the stator lamination of the present invention is shown; Figure 4 A flowchart of the stator lamination optimization design method of the present invention is shown; Figure 5 The stress cloud diagram of the stator lamination with a conventional square rounded corner oil groove is shown; Figure 6 The stress cloud diagram of the stator lamination of the oil-cooled motor with R2=0.5R1 according to the present invention is shown; Figure 7 The stress cloud diagram of the stator lamination of the oil-cooled motor with R2=R1 according to the present invention is shown; Figure 8 The stress cloud diagram of the stator lamination of the oil-cooled motor with R2=2R1 according to the present invention is shown; Figure 9 The stress cloud diagram of the stator lamination of the oil-cooled motor with R2=4R1 of the present invention is shown.

[0022] In the diagram: a) Cooling structure; b) Electromagnetic structure; 1) Rhomboid structure; 2) Circular structure; 3) Structural teeth; 4) Structural groove; 5) Structural yoke; 6) Partition bridge; 7) Lamination substrate. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The solution provided by this invention is mainly applied to the field of electric drive for new energy vehicles. Specifically, it relates to a stator lamination of an oil-cooled drive motor and its optimized design method. By setting a cooling structure with a specific chamfer ratio on the outer periphery of the lamination and setting an electromagnetic structure on the inner periphery, cooling enhancement, stress dispersion and electromagnetic optimization are achieved. The optimal chamfer ratio is determined by comparison through finite element simulation, thereby improving the cooling efficiency, mechanical reliability and electromagnetic performance of the motor.

[0025] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0026] This invention provides a stator lamination for an oil-cooled motor.

[0027] like Figure 1 As shown, the stator lamination of the oil-cooled motor includes an annular lamination base 7. The outer periphery of the lamination base 7 is provided with multiple sets of cooling structures a distributed along the circumferential direction, and the inner periphery of the lamination base 7 is provided with multiple sets of electromagnetic structures b distributed along the circumferential direction. In this embodiment, the annular lamination substrate 7 serves as the mounting base for the cooling structure a and the electromagnetic structure b, ensuring the overall rigidity and structural integrity of the lamination. Through the circumferentially uniformly distributed structure, electromagnetic symmetry and uniform heat flow are achieved.

[0028] Furthermore, each group of electromagnetic structures b includes structural teeth 3, structural grooves 4 and structural yokes 5. The structural teeth 3 are evenly distributed circumferentially, and the width of the root of the structural teeth 3 is greater than the width of its top. A structural groove 4 with an inward opening is provided between two adjacent groups of structural teeth 3. In this embodiment, the structural teeth 3 in the electromagnetic structure b are the main components of the motor magnetic circuit, used to carry the winding and generate electromagnetic torque. The structural slots 4 are used to embed the stator winding to form an armature reaction magnetic field. The structural yoke 5 connects adjacent structural teeth to form a closed magnetic circuit, transmits magnetic flux, and ensures the continuity and mechanical rigidity of the magnetic circuit. Specifically, the design of the root width of the structural tooth 3 being greater than the width of its tip width conforms to the principle of wide root and narrow tip in electromagnetic design, which is used to balance magnetic flux density and mechanical strength, avoid magnetic flux density saturation at the tip of the tooth, improve electromagnetic efficiency, and the widened root can resist electromagnetic force and centrifugal force, reducing mechanical vibration and deformation; the inward opening design of the structural slot 4 helps to reduce slot leakage magnetic flux and facilitates winding winding operation; the structural yoke 5, as the medium for transferring winding heat from the tooth to the cooling structure a, is integrally formed with the lamination base 7, which enhances the overall rigidity of the lamination base 7 and can resist electromagnetic vibration.

[0029] Compared to traditional stator laminations, which typically have rectangular or simple trapezoidal tooth profiles that can lead to uneven magnetic flux distribution, and whose slots are usually outward-facing or straight-edged, resulting in difficulties in winding and high magnetic leakage, the tooth profile of structure 3 in this embodiment is a T-shaped structure. By adopting the electromagnetic structure b in this embodiment, the optimized slot and tooth profiles can optimize the magnetic circuit distribution, reduce magnetic saturation, and decrease magnetic leakage, thereby improving electromagnetic performance and increasing motor efficiency and power density.

[0030] It should be noted that the pole-slot ratio of 8 poles and 48 slots (6 slots per pole) is a mature solution that has been proven over a long period of time in the field of new energy vehicle drive motors. In this embodiment, 48 sets of electromagnetic structures b are evenly distributed along the circumference. Therefore, the central angle between two adjacent sets of structural teeth 3 is... It is 7.5°.

[0031] like Figure 3 As shown, each cooling structure a includes a rhomboid structure 1 and a circular structure 2. The major axis of the rhomboid structure 1 is arranged along the circumference of the lamination substrate 7, and the minor axis of the rhomboid structure 1 is arranged along the radial direction of the lamination substrate 7. The rhomboid structure 1 has a first chamfer R1 and a second chamfer R2. The first chamfer R1 is arranged along the major axis of the rhomboid structure 1, and the second chamfer R2 is arranged along the minor axis of the rhomboid structure 2. In this embodiment, the rhomboid structure 1 in the cooling structure a is not a standard rhombus, but an irregularly shaped hole that approximates a rhombus. The four corners of the rhomboid structure 1 are all rounded (i.e., chamfered), namely the first chamfer R1 and the second chamfer R2. The longer axis of the rhomboid structure 1, that is, the straight line that passes through the center of the rhomboid structure 1 and connects the two farthest vertices (or the chamfered center), is the major axis of the rhomboid structure 1. Similarly, the shorter axis of the rhomboid structure 1, that is, the straight line that passes through the center of the rhomboid structure 1 and connects the two closest vertices (or the chamfered center), is the minor axis of the rhomboid structure 1. Furthermore, the long axis direction corresponds to the length direction of the rhomboid structure 1, which is the span occupied by the rhomboid structure 1 in the circumferential direction of the lamination substrate 7. The short axis direction corresponds to the width direction of the rhomboid structure 1, which is the span occupied by the rhomboid structure 1 in the radial direction of the lamination substrate 7. The rhomboid structure 1, through its special shape with its long axis along the circumferential direction and its short axis along the radial direction, guides the coolant to flow in the circumferential direction and enhances local heat transfer. Moreover, the first chamfer R1 set along the long axis direction and the second chamfer R2 set along the short axis direction work together to cause the interference stress to undergo "stress deflection" and "gradient release" at the chamfer, thus avoiding stress concentration. In this embodiment, the circular structure 2 in cooling structure a is a standard circle and does not participate in stress dispersion. It mainly undertakes the hydrodynamic function. The circular structure 2 serves as the main channel inlet / outlet or buffer chamber for the coolant and forms a cooling path with the rhomboid structure 1. The rhomboid structure 1 is used to increase the turbulence of the coolant and improve the heat transfer coefficient. The circular structure 2 ensures that the cooling path of the coolant is unobstructed and avoids dead zones. The circular structure 2 and the rhomboid structure 1 form an efficient cooling network, which improves the heat dissipation capacity of the overall cooling structure a.

[0032] In cooling structure a, a circular structure 2 is set as the main channel inlet / outlet or buffer chamber for the coolant, guiding the coolant into or out of the cooling area. Combined with the rhomboid structure 1, its non-circular, chamfered geometry causes turbulence when the coolant flows through, disrupting the thermal boundary layer and enhancing convective heat transfer efficiency.

[0033] It should be noted that setting too many cooling structures a will reduce the strength of the stator lamination structure, thereby affecting the interference stress, while setting too few cooling structures a means reducing the flow path of the coolant, thereby reducing the cooling effect. Therefore, in this embodiment, setting 44 sets of cooling structures a is a relatively balanced choice. like Figure 3As shown, 44 cooling structures a are arranged on the entire circumference of the lamination substrate 7, that is, the entire circumference is evenly divided into 44 structures. The central angle of the sector occupied by each cooling structure a is approximately 8.18°. Taking each cooling structure a as a reference, the central angle of the sector occupied by the center of the rhomboid structure 1 to the center of the circular structure 2 is... At approximately 4.09°, it achieves a reasonable spatial distribution that is neither too crowded nor too sparse, while ensuring both cooling and stress dispersion effects.

[0034] like Figure 2 As shown, a partition bridge 6 is provided between the rhomboid structure 1 and the circular structure 2 to block the stress transmission path, forcing the stress to concentrate and be dispersed by the rhomboid structure 1. The width of the partition bridge 6 ranges from 0.8mm to 1.5mm. Adjacent sets of partition bridges 6 are symmetrically arranged about the line connecting the center of the circular structure 2 and the center of the lamination base 7, and / or adjacent sets of partition bridges 6 are symmetrically arranged about the line connecting the center of the rhomboid structure 1 and the center of the lamination base 7. In this embodiment, the partition bridge 6 is a narrow solid region connecting the rhomboid structure 1 and the circular structure 2. It is used to physically isolate the rhomboid structure 1 and the circular structure 2 in the cooling structure a. It can block the continuous transmission of interference stress from the rhomboid structure 1 to the circular structure 2, force the stress to concentrate in the area of ​​the rhomboid structure 1, and locally disperse it through the first chamfer R1 and the second chamfer R2 of the rhomboid structure 1. If the width of the partition bridge 6 is too small (e.g., <0.8mm), the cross-section of that area will be too thin, making it prone to breakage or plastic deformation during stamping or interference fitting, thus losing its function of isolating and blocking stress. If the width is larger (e.g., >1.5mm), it will occupy more cooling channel space, squeezing the flow cross-sectional area of ​​the coolant, increasing flow resistance, and reducing cooling efficiency. Therefore, in this embodiment, the width of the partition bridge 6 is in the range of 0.8mm to 1.5mm, which can form an effective stress blocking barrier without excessively encroaching on the effective space of the cooling channel, ensuring that the coolant can flow smoothly through the rhomboid and circular structures and maintain good heat exchange performance.

[0035] In this embodiment, the rhomboid structure 1 has the function of stress dispersion. The first chamfer R1 and the second chamfer R2 in the rhomboid structure 1 work together. The first chamfer R1 causes the stress to deflect along the circumferential direction, avoiding the concentration of interference stress at the corners of the rhomboid structure 1. The second chamfer R2 causes the stress to be released along the radial gradient, reducing the stress peak transmitted to the housing. By combining the chamfer in the rhomboid structure 1 with the partition bridge 6, stress can be concentrated in the designable area (rhomboid structure area) and locally dispersed through the chamfer, thus making the stress path controllable. This facilitates the optimization of the stress structure, avoids stress transmission to critical mating surfaces (such as the housing), reduces the risk of deformation or cracking caused by interference stress, and improves assembly reliability.

[0036] Working principle: The stator lamination of the oil-cooled motor of the present invention uses an annular lamination base 7 as the main bearing body. The outer peripheral side of the lamination base 7 is provided with a cooling structure a (including a rhomboid structure 1, a circular structure 2 and a partition bridge 6), and the inner peripheral side of the lamination base 7 is provided with an electromagnetic structure b (including structural teeth 3, structural grooves 4 and structural yokes 5). The two work together. Specifically, during operation, after the stator winding is energized, a rotating magnetic field is generated in the structural teeth 3 and the structural yoke 5, which interacts with the rotor permanent magnet to generate electromagnetic torque, driving the motor to run. The structural teeth 3 are designed with a root width greater than the tip width, conforming to the principle of wide root and narrow tip in electromagnetic design. This balances magnetic flux density and mechanical strength, prevents tip magnetic flux saturation, and improves electromagnetic efficiency. The structural slots 4 have inward-facing openings, which helps reduce slot leakage flux and facilitates winding insertion. The structural yoke 5 connects two adjacent sets of structural teeth 3, forming a closed magnetic circuit to transmit magnetic flux, ensuring the continuity of the magnetic circuit and mechanical rigidity. It also serves as an intermediary for heat transfer from the teeth to the cooling structure.

[0037] During motor operation, the heat generated by the winding is conducted to the cooling structure a on the outer periphery through the structural teeth 3 and the structural yoke 5. The coolant is injected into the circular structure 2 from the oil injection ring. The circular structure 2 serves as the main channel inlet / outlet or buffer chamber for the coolant, guiding the coolant into or out of the cooling area. When the coolant flows through the rhomboid structure 1, due to its non-circular and chamfered geometry, turbulent disturbances are generated, which destroy the thermal boundary layer, enhance the convective heat transfer efficiency, and carry away the heat transferred from the electromagnetic structure b, thereby achieving the cooling of the stator core. Meanwhile, the radial compressive stress generated by the interference fit between the housing and the stator core is blocked by the isolation bridge 6 when it is transmitted to the rhomboid structure 1. The isolation bridge 6 physically isolates the rhomboid structure 1 from the circular structure 2, blocking the continuous transmission of interference stress from the rhomboid structure 1 to the circular structure 2, forcing the stress to concentrate in the area of ​​the rhomboid structure 1. Subsequently, the first chamfer R1 of the rhomboid structure 1 causes the stress to deflect circumferentially, avoiding stress concentration at the corners, and the second chamfer R2 causes the stress to be released radially, reducing the stress peak transmitted to the housing. Through the combined effect of the chamfer and the isolation bridge 6, the stress path can be controlled, reducing the transmission of stress to the inner periphery of the lamination and preventing stress from being transmitted to the critical mating surfaces.

[0038] In summary, the oil-cooled motor stator lamination of the present invention achieves enhanced cooling and stress dispersion by setting a cooling mechanism a on the outer peripheral side, and achieves electromagnetic optimization and structural reinforcement by setting an electromagnetic structure b on the inner peripheral side. The two work together to construct a high-performance oil-cooled motor stator lamination, which effectively improves the motor's cooling efficiency, electromagnetic performance and mechanical reliability.

[0039] The present invention also provides an optimized design method for stator laminations of oil-cooled motors, which is applied to the stator laminations of oil-cooled motors as described above.

[0040] like Figure 4 As shown, the optimization design method includes the following steps: S1: Establish a three-dimensional comparison model and a benchmark model Multiple sets of three-dimensional comparison models of stator laminations for oil-cooled drive motors with different chamfer ratios were established using 3D modeling software. At the same time, a three-dimensional model of a traditional square rounded corner oil groove stator lamination was established as a reference model. Specifically, taking the first chamfer R1 of the fixed rhomboid structure 1 as the benchmark value, the ratio of the second chamfer R2 to the first chamfer R1 is changed to establish multiple sets of three-dimensional comparison models with different chamfer ratios; at the same time, a three-dimensional model of a traditional square rounded corner oil groove stator lamination is established as a reference model for comparison to quantify the improvement effect.

[0041] It should be noted that the traditional square rounded corner oil groove stator lamination three-dimensional model adopts a square rounded corner cooling structure, which has the same overall external dimensions and electromagnetic structure parameters as the oil-cooled drive motor stator lamination three-dimensional model. That is, the stator laminations in the reference model and the three-dimensional comparison model all adopt the same outer diameter, inner diameter, number of tooth slots and yoke dimensions. Introducing the traditional structure as a reference can intuitively demonstrate the effect of the cooling structure a in stress blocking of this application. Meanwhile, by using the controlled variable method, only the setting of the cooling structure a in the stator lamination of the oil-cooled drive motor in this embodiment is changed (specifically, only the R2 / R1 ratio is changed, while the other parameters remain the same), ensuring that the difference in subsequent simulation results only comes from the change in the chamfer ratio.

[0042] S2: Stator core model composed of laminated components The three-dimensional comparison models and the reference model are stacked to form the corresponding stator core models; Specifically, single three-dimensional laminations are stacked along the axial direction according to the actual stacking coefficient (such as a stacking coefficient of 0.95) to form a stator core assembly of a certain length, making it closer to the stress state of a real motor stator core. Among them, each comparison group and the control group are stacked independently to ensure that the number of laminations and the total length are consistent, avoiding calculation deviations caused by the number of single laminations and improving the reliability of the simulation.

[0043] S3: Apply boundary conditions and loads Preset boundary conditions and loads are applied to each of the stator core models to simulate the interference fit between the motor housing and the stator core, specifically including: S3-1: Set cylindrical support boundary conditions on the inner surface of each stator core model to simulate housing clamping, and input the preset interference fit between the housing and the stator core. Specifically, the same cylindrical support boundary conditions are set on the inner surface of each stator core model to constrain the radial degree of freedom of the inner surface of the stator core, allowing it to move slightly in the axial direction, simulating the clamping effect of the motor housing, and the interference fit between the housing and the stator core is input. In this embodiment, the interference fit is 0.058mm (0.058mm is a common interference fit value in engineering and has high reliability in actual production). The same interference fit is applied to all three-dimensional comparison models and the reference model.

[0044] S3-2: Apply a preset inward uniform pressure to the outer diameter surface of each stator core model to equivalently simulate the radial compressive stress generated by the interference fit. Specifically, a pressure load (i.e., uniformly distributed pressure) of constant magnitude and directed towards the center is applied to the outer diameter surface of each stator core model. In this embodiment, the pressure load is set to 5.4 MPa, and the same uniformly distributed pressure is applied to all three-dimensional comparison models and reference models.

[0045] It should be noted that in actual interference fit assembly, on the one hand, the clamping force of the housing on the stator core is a complex nonlinear contact pressure transmitted through the contact surface. However, in finite element simulation, directly simulating the contact pair and solving the interference contact requires a lot of computational resources. By applying a uniformly distributed pressure to the outer diameter curved surface, this contact pressure can be equivalently replaced, simplifying the calculation model and ensuring that the calculation cost and time are greatly reduced without losing accuracy, thereby improving the simulation efficiency. On the other hand, the interference input in step S3-1 will generate some radial pressure, but this stress is mainly concentrated near the contact area. Applying additional uniform pressure can supplement and strengthen the radial compressive stress field, making it evenly distributed on the entire outer diameter of the core, which is closer to the stress state in the actual press-fitting process, ensuring that the stress field is more uniform and stable, and facilitating subsequent comparison of stress transmission characteristics under different chamfer ratios. Furthermore, the stress generated solely by interference may be relatively weak, and the stress difference between different chamfer ratios is not obvious enough. After applying uniform pressure, the overall radial compressive stress level is improved, and the stress blocking and dispersion effect of the rhomboid structure 1 will be more significant. The difference between different R2 / R1 ratios will also be more easily highlighted, thus improving the sensitivity and resolution of the simulation comparison.

[0046] S4: Finite Element Simulation and Stress Cloud Map Extraction Finite element simulation calculations were performed on each of the stator core models, and the equivalent stress cloud diagrams of each model in the radial direction of the stator core were extracted. Specifically, static finite element simulation calculations are performed on each stator core model (comparison models with different chamfer ratios and traditional square rounded corner oil groove comparison models) after loading in step S3. After the solution is completed, the equivalent stress cloud diagram (stress transfer diagram) of each model in the radial direction of the stator core is extracted.

[0047] Through the finite element simulation calculation in step S4, the continuous physical field can be discretized into numerical solutions of nodes and elements, and these values ​​are presented in the form of color gradients in the equivalent stress cloud map. That is, the abstract stress state is transformed into a visual image. In this embodiment, four sets of three-dimensional comparison models with different chamfer ratios and one set of traditional square rounded corner reference models are set. Based on the set models, five different stress cloud maps are obtained. Engineers can directly observe and compare specific information such as the stress transmission path from the outer periphery to the inner periphery of the lamination, the location of the stress concentration area, and the stress amplitude through the cloud map.

[0048] S5: Comparison of stress transfer characteristics By comparing the stress cloud diagrams of each of the three-dimensional comparison models with the reference model, the stress transfer characteristics under different chamfer ratios are analyzed. Specifically, the equivalent stress cloud maps of each three-dimensional comparison model (with different R2 / R1 ratios) extracted in step S4 are compared with the equivalent stress cloud map of the reference model (traditional square rounded corner oil groove) group by group to analyze the differences in stress transmission characteristics in the radial direction of the stator core under different cooling structures and chamfer ratios.

[0049] S6: Determine the optimal chamfer ratio Based on the comparison results of stress transfer characteristics, the optimal chamfer ratio is determined; Specifically, based on the stress transmission characteristics of multiple sets of data (traditional square rounded corners, multiple sets of different R2 / R1 ratios) obtained in step S5, these data are compared laterally. With the goal of "minimum transmission depth" and "lowest amplitude", the ratio point that makes the radial stress transmission depth and equivalent stress amplitude reach the minimum value at the same time is found. Then, this ratio value is determined to be the only extreme point that makes the target reach the optimal value.

[0050] The following will provide a more detailed explanation of the optimized design of the stator laminations for an oil-cooled motor using the method described in this embodiment.

[0051] Step 1: Establish a three-dimensional comparison model and a reference model Four sets of three-dimensional comparison models of stator laminations of oil-cooled drive motors with different chamfer ratios were established. Except for the chamfer ratio, all other parameters of the four comparison models were set the same, and the chamfer ratios of the four sets were set to R2=0.5R1, 1.0R1, 2.0R1, and 4.0R1, respectively. A three-dimensional model of a traditional square rounded corner oil groove stator lamination was established as a reference model. Except for the cooling structure, the other parameters were completely consistent with the comparison model.

[0052] Step 2: Stacking to form the stator core model Each model consists of 100 laminations stacked axially with a stacking factor of 0.95 to form a stator core assembly. This simulates the clamping stress state of a real motor stator and avoids calculation errors caused by differences in the number of laminations.

[0053] Step 3: Apply boundary conditions and loads Step 3-1: Set cylindrical support boundary conditions on the inner surface of the above 5 sets of stator core models, constrain the radial degree of freedom (simulate the housing clamping), allow axial micro-movement, and input an interference of 0.058mm; Step 3-2: Apply an inward uniform pressure to the outer diameter surface of all 5 sets of stator core models. The uniform pressure is set to 5.4 MPa, which is equivalent to replacing the complex nonlinear pressure of the interference contact, simplifying the calculation and strengthening the radial compressive stress field to simulate the radial compressive stress generated by the interference fit.

[0054] Step 4: Finite element simulation and stress cloud map extraction Static finite element simulation was performed on the above five sets of stator core models to extract the equivalent stress cloud diagram of each model in the radial direction of the stator core.

[0055] Step 5: Compare stress transfer characteristics The stress transfer characteristics of the five different stress cloud maps obtained in step 4 are compared, and information such as stress transfer depth, amplitude, and concentration area are analyzed.

[0056] The specific analysis based on the stress contour plot is as follows: like Figure 5 The figure shows a schematic diagram of stress transmission in a stator lamination with a traditional square rounded corner oil groove. As can be seen from the figure, the stress (colored area) penetrates the deepest from the outer periphery of the lamination inward, almost extending to the tooth root / yoke area. The high stress area (green / yellow) is widely distributed, and the high stress is concentrated near the square rounded corner. There is no obvious obstruction to radial transmission. like Figure 6The figure shows a schematic diagram of stress transmission in the stator lamination of an oil-cooled motor with R2=0.5R1. As can be seen from the figure, the stress transmission depth is slightly shallower than that of the traditional square rounded corner oil groove, but it is still relatively deep (the colored area extends inward obviously), and there is still a high stress area (green / yellow). At this time, the second chamfer R2 is much smaller than the first chamfer R1, and the stress is still concentrated at the edge of the chamfer, resulting in a weak blocking effect. like Figure 7 The figure shows a schematic diagram of stress transmission in the stator lamination of an oil-cooled motor with R2=R1. As can be seen from the figure, the stress transmission depth is further reduced (the distance of the colored area extending inward is shortened). At this time, the second chamfer R2 is equal to the first chamfer R1, and the stress concentration is somewhat relieved, but there is still local high stress at the chamfer. like Figure 8 The diagram shows the stress transmission of the stator lamination of an oil-cooled motor with R2=2R1. As can be seen from the diagram, the stress transmission depth is the shallowest (the colored area is only concentrated on the outer surface of the lamination, extending very short inward), the high stress area (green / yellow) is the smallest, and the color is the lightest (indicating that its equivalent stress amplitude is lower). At this time, the second chamfer R2 is equal to twice the first chamfer R1, and the stress is effectively blocked near the rhomboid structure, with almost no radial deep transmission. like Figure 9 The diagram shows the stress transmission of the stator lamination of an oil-cooled motor with R2=4R1. As can be seen from the diagram, compared with the stress transmission diagram of the stator lamination of an oil-cooled motor with R2=2R1, the stress transmission depth is deeper (the colored area extends further inward), the range of the high-stress area (green / yellow) is larger, and the color is slightly darker (indicating that the equivalent stress amplitude has rebounded). At this time, the second chamfer R2 is much larger than the first chamfer R1, the stress blocking and dispersion function of the structure is weakened, and the stress rebounds in a concentrated manner.

[0057] Step 6: Determine the optimal chamfer ratio Based on the comparison data from step 5, with the objectives of "minimum radial stress transmission depth" and "lowest equivalent stress amplitude", the extreme points that enable the objectives to reach their optimal values ​​are selected.

[0058] By comparing and analyzing four sets of different chamfer ratios and a set of traditional control models, it can be seen that in terms of stress transfer depth, the ratio of R2=2R1 in the cooling structure has the smallest stress transfer depth, the lowest equivalent stress amplitude, and the stress concentration area is very slight. Other ratios either have a high stress transfer depth / amplitude or the stress structure shows weakening and rebound. Compared with the comparative model using the cooling structure of this embodiment, the traditional square rounded corner oil groove stator lamination has a deep stress transmission depth, a high equivalent stress amplitude, a wide stress concentration area, and poor stress distribution uniformity. Using the traditional square rounded corner oil groove stator lamination will result in large residual stress inside the iron core (tooth root, yoke), which is prone to fatigue cracking, magnetic circuit distortion, and reduced motor reliability.

[0059] In summary, through simulation optimization of the above process, and by using controlled variables, equivalent loads, and multiple comparisons, the chamfer ratio with the optimal stress-blocking effect was determined, providing a quantitative basis for the design of motor stator laminations.

[0060] It should be noted that, as an optional embodiment of the present invention, in order to systematically explore the influence of the chamfer ratio in cooling structure a on interference stress transmission, a parametric modeling method can be adopted. The second chamfer R2 is set as a variable, and the first chamfer R1 is used as the reference. The proportional coefficient k = R2 / R1 is defined. By setting multiple sets of k values ​​(such as k = 0.3, 0.5, 0.8, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0), finite element simulation calculations are performed under the premise of keeping other geometric and boundary conditions unchanged. The stress radial transmission depth and the maximum equivalent stress amplitude corresponding to each set of k are extracted, and the corresponding trend curves are plotted. Through analysis, it is found that the stress radial transmission depth and the maximum equivalent stress amplitude both show a U-shaped change trend of first decreasing and then increasing, and reach the minimum value at k = 2.0. After verification by the second derivative and comparison with neighboring points, this point is confirmed as the unique extreme point. Therefore, the optimal chamfer ratio is determined to be R2 = 2R1, providing solid data support and theoretical basis for engineering design.

[0061] As a typical embodiment of the present invention, this embodiment provides an electric motor, including a housing, in which a stator assembly is installed, the stator assembly including a stator winding and a motor stator, the motor stator being sleeved on the outside of the stator winding, and a rotor being installed inside the motor stator; wherein, the motor stator includes oil-cooled motor stator laminations as described above, and a plurality of oil-cooled motor stator laminations are stacked axially to form a stator core; Specifically, the motor is an oil-cooled drive motor, applied in the power system of new energy vehicles. The motor stator is formed by stacking multiple oil-cooled motor stator laminations as described above, forming a stator core with 44 cooling structures a and 48 electromagnetic structures b. In the rhomboid structure 1 of cooling structure a, a chamfer ratio of R2=2R1 is adopted. In the oil-cooled drive motor, the application of this stator lamination achieves a comprehensive effect of improved cooling efficiency, reduced stress damage, stable electromagnetic performance, and extended motor life, providing a more efficient, reliable, and durable power solution for new energy vehicles.

[0062] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A stator lamination for an oil-cooled motor, comprising an annular lamination base, characterized in that, The outer periphery of the lamination substrate is provided with multiple sets of cooling structures distributed circumferentially, and the inner periphery of the lamination substrate is provided with multiple sets of electromagnetic structures distributed circumferentially. Each group of cooling structures includes a rhomboid structure and a circular structure; The major axis of the rhombic structure is arranged along the circumference of the lamination substrate, and the minor axis of the rhombic structure is arranged along the radial direction of the lamination substrate; The rhomboid structure has a first chamfer R1 and a second chamfer R2, wherein the first chamfer R1 is set along the major axis of the rhomboid structure and the second chamfer R2 is set along the minor axis of the rhomboid structure.

2. The oil-cooled motor stator lamination according to claim 1, characterized in that, A partition bridge is provided between the rhomboid structure and the circular structure to block the stress transmission path, forcing the stress to concentrate and be dispersed by the rhomboid structure.

3. The stator lamination of the oil-cooled motor according to claim 2, characterized in that, The two adjacent sets of partition bridges are symmetrically arranged about the line connecting the center of the circular structure and the center of the lamination base, and / or the two adjacent sets of partition bridges are symmetrically arranged about the line connecting the center of the rhomboid structure and the center of the lamination base.

4. The stator lamination of the oil-cooled motor according to claim 2, characterized in that, The width of the partition bridge ranges from 0.8mm to 1.5mm.

5. The oil-cooled motor stator lamination according to claim 1, characterized in that, Each set of electromagnetic structures includes structural teeth, structural grooves, and structural yokes. The structural teeth are evenly distributed along the inner circumferential side of the lamination substrate. The structural yokes connect the roots of two adjacent sets of structural teeth. A structural groove with an inward opening is provided between two adjacent sets of structural teeth.

6. The stator lamination of the oil-cooled motor according to claim 5, characterized in that, The width of the root of the tooth is greater than the width of its tip.

7. An optimized design method for stator laminations of an oil-cooled motor, applied to the stator laminations of an oil-cooled motor as described in any one of claims 1 to 6, characterized in that, Includes the following steps: Using the first chamfer R1 of the fixed rhomboid structure as the reference value, the ratio of the second chamfer R2 to the first chamfer R1 is changed to establish multiple sets of three-dimensional comparison models of oil-cooled motor stator laminations with different chamfer ratios. At the same time, a three-dimensional model of a traditional square rounded corner oil groove stator lamination is established as a reference model. The three-dimensional comparison models and the reference model are stacked to form the corresponding stator core models; Preset boundary conditions and loads are applied to each of the stator core models to simulate the interference fit between the motor housing and the stator core. Finite element simulation calculations were performed on each of the stator core models, and the equivalent stress cloud diagrams of each model in the radial direction of the stator core were extracted. By comparing the stress cloud diagrams of each of the three-dimensional comparison models with the reference model, the stress transfer characteristics under different chamfer ratios are analyzed. Based on the comparison results of stress transfer characteristics, the final chamfer ratio is determined.

8. The optimization design method according to claim 7, characterized in that, The three-dimensional model of the traditional square rounded corner oil groove stator lamination has the same overall external dimensions and electromagnetic structure parameters as the three-dimensional model of the oil-cooled drive motor stator lamination.

9. The optimization design method according to claim 7, characterized in that, The process of applying preset boundary conditions and loads to each of the stator core models to simulate the interference fit between the motor housing and the stator core includes: Cylindrical support boundary conditions are set on the inner surface of each stator core model to simulate housing clamping, and the preset interference fit between the housing and the stator core is input.

10. The optimization design method according to claim 7, characterized in that, The step of applying preset boundary conditions and loads to each of the stator core models to simulate the interference fit between the motor housing and the stator core also includes: A preset inward uniform pressure is applied to the outer diameter surface of each stator core model to equivalently simulate the radial compressive stress generated by interference fit.

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