A stator cooling structure and method

Abstract

This invention discloses a stator cooling structure and method, belonging to the field of motor technology. The structure includes a stator core and a motor housing arranged coaxially. The stator core is formed by stacking multiple laminations, including a first lamination, a second lamination, and a third lamination. The yoke of the first lamination has an axially penetrating oil groove. The third lamination is arranged at both ends of the stator core and has an oil spray hole. The second lamination is positioned between the first and third laminations, and its yoke has a transition oil groove. One end of the transition oil groove communicates with the axially penetrating oil groove, and the other end communicates with the oil spray hole. The inner wall of the motor housing has an annular oil distribution groove. This invention embeds the cooling oil path within the laminations, achieving directional delivery and precise spraying of the cooling oil, effectively solving the heat dissipation problem of the winding intermediate layer, and featuring a compact structure and high cooling efficiency.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a stator cooling structure and method. Background Technology

[0002] With the increasing demand for electric vehicles, the requirements for motor efficiency and heat dissipation are becoming increasingly stringent. Traditional oil-cooled motors typically use oil grooves or holes in the stator yoke to spray cooling oil onto the outer layer of the stator winding ends. However, the middle layer of the windings suffers from poor heat dissipation due to its smaller gaps, leading to higher temperatures. This not only affects the insulation life of the windings but can also cause problems such as decreased motor efficiency and output torque fluctuations, and in severe cases, even overheating protection or damage. Therefore, achieving efficient and uniform cooling of the stator windings, especially the middle layer, within a limited space has become a key challenge in motor heat dissipation design.

[0003] Furthermore, existing stator cores are mostly made of single laminations, resulting in a simple oil circuit structure that makes it difficult to achieve precise guidance and spray positioning of cooling oil. This is especially true under high-speed motor operation, where the oil cooling effect is limited. Some solutions attempt to add complex oil channels to the housing or end cover, but these often lead to structural complexity, assembly difficulties, and reduced sealing reliability. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the above-mentioned shortcomings of the prior art by providing a stator cooling structure and method that is compact, highly reliable, and allows for precise guidance of cooling oil, effectively improving the cooling effect. It has the characteristics of wide applicability and strong practicality.

[0005] The technical solution adopted in this invention is: a stator cooling structure, including a stator core and a motor housing arranged coaxially. The stator core is formed by stacking multiple laminations, including a first lamination, a second lamination, and a third lamination. The yoke of the first lamination is provided with an axial oil passage groove that runs through the axis. The third lamination is arranged at both ends of the stator core and has an oil spray hole. The second lamination is disposed between the first and third laminations, and the yoke of the second lamination is provided with a transition oil groove. One end of the transition oil groove is connected to the axial oil passage groove, and the other end is connected to the oil spray hole. The inner wall of the motor housing is provided with an annular oil inlet distribution groove. The motor housing has an oil inlet that communicates with the oil inlet distribution groove. The oil inlet distribution groove is connected to the axial oil passage groove, so that the cooling oil entering from the oil inlet can be guided sequentially through the axial oil passage groove and the transition oil groove to the oil spray hole and sprayed out.

[0006] As a further improvement, the cross-sectional area of ​​the axial oil groove and the transition oil groove is larger than the cross-sectional area of ​​the injection hole.

[0007] Furthermore, the outer edges of the yokes of the first, second, and third laminations are provided with welding grooves for welding and fixing.

[0008] Furthermore, the welding groove is located on one side of the axial oil groove or transition oil groove along the circumferential direction.

[0009] Furthermore, a sealing ring is provided at the axial end of the stator core between the third lamination and the motor housing.

[0010] Furthermore, the first, second, and third laminations are respectively provided with marking grooves for alignment during stacking.

[0011] Furthermore, the oil injection hole is located in the middle position along the axial direction on the toothed part of the third lamination.

[0012] Furthermore, the number of the oil injection holes and the axial oil passage grooves is one or more.

[0013] A cooling method based on the above stator cooling structure includes the following steps:

[0014] S1. Inject cooling oil into the oil distribution tank from the oil inlet of the motor housing; S2. Cooling oil flows from the oil inlet distribution groove into the axial oil groove of the first lamination, and flows axially to both ends of the stator core. S3. Cooling oil is guided through the transition oil groove of the second lamination to the oil injection hole of the third lamination. The cooling oil is sprayed out from the oil injection hole and directly acts on the intermediate layer area at the end of the stator winding to cool it.

[0015] Beneficial effects Compared with the prior art, the present invention has the following advantages: 1. This invention creatively integrates the oil injection hole into the teeth of the third lamination and utilizes the transition oil groove of the second lamination in the middle position to achieve precise redirection and distribution of the oil flow. This embedded oil circuit design allows the cooling oil to directly act on the intermediate layer of the winding end, which is difficult to reach by traditional cooling methods, significantly reducing the temperature peak in this area and the overall temperature difference of the winding, and improving the uniformity and efficiency of heat dissipation.

[0016] 2. The axial oil passages, transition oil passages, and oil injection holes of the cooling system are all implemented through the structural design of the laminations themselves and integrated inside the stator core. This maximizes the use of existing space, eliminating the need for complex and precise oil channels and external nozzles on the motor housing or end cover. This simplifies the overall structure, reduces the number of parts and potential leakage points, and improves the inherent reliability of the system.

[0017] 3. The ingenious offset design of the welding groove allows the conventional iron core welding process to be retained without affecting the function of the internal cooling oil circuit. The design of the marking groove ensures the rapid and accurate stacking of three different functional laminations. The overall solution is highly compatible with existing motor manufacturing processes, requiring no special or expensive processing equipment and facilitating large-scale production. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the main cross-sectional structure of the present invention; Figure 2 This is a schematic diagram of the stator core structure in this invention; Figure 3 This is a schematic diagram of the structure of the first lamination in this invention; Figure 4 This is an enlarged schematic diagram of the structure of the first lamination in this invention; Figure 5 This is a schematic diagram of the structure of the second lamination in this invention; Figure 6 This is an enlarged schematic diagram of the structure of the second lamination in this invention; Figure 7 This is a schematic diagram of the structure of the third lamination in this invention; Figure 8 This is an enlarged schematic diagram of the structure of the third lamination in this invention; Figure 9 This is a cross-sectional view of the motor housing in this invention.

[0019] Wherein: 1-Stator core, 2-First lamination, 3-Second lamination, 4-Third lamination, 5-Motor housing, 6-Oil injection hole, 7-Sealing ring, 8-Marking groove, 9-Welding groove, 10-Transition oil groove, 11-Oil inlet, 12-Oil distribution groove, 13-Axial oil passage groove. Detailed Implementation

[0020] The present invention will be further described below with reference to specific embodiments shown in the accompanying drawings.

[0021] See Figure 1-9As shown, a stator cooling structure of the present invention includes a stator core 1 and a motor housing 5 arranged coaxially. The stator core 1 is formed by stacking multiple laminations, including a first lamination 2, a second lamination 3, and a third lamination 4. The yoke of the first lamination 2 is provided with an axially penetrating oil groove 13. The third lamination 4 is arranged at both ends of the stator core 1, and an oil spray hole 6 is provided on the third lamination 4. The second lamination 3 is disposed between the first lamination 2 and the third lamination 4. The yoke of the two-stroke lamination 3 is provided with a transition oil groove 10. One end of the transition oil groove 10 is connected to the axial oil passage groove 13, and the other end is connected to the oil injection hole 6. The inner wall of the motor housing 5 is provided with an annular oil inlet distribution groove 12. An oil inlet 11 is opened on the motor housing 5 and is connected to the oil inlet distribution groove 12. The oil inlet distribution groove 12 is connected to the axial oil passage groove 13, so that the cooling oil entering from the oil inlet 11 can be guided to the oil injection hole 6 and sprayed out in sequence through the axial oil passage groove 13 and the transition oil groove 10.

[0022] In this embodiment, the first lamination 2 constitutes the main body of the stator core 1. Multiple axial oil grooves 13 are spaced circumferentially on the yoke portion of the lamination, i.e., the annular area between the outer circle of the lamination and the tooth root. When multiple first laminations 2 are aligned and stacked, these grooves together form the main oil guiding channel that runs through the axial length of the main body of the core. The third lamination 4, as an end functional piece, is arranged at the two axial ends of the stator core 1. The inlet of the oil injection hole 6 of the third lamination 4 is located near the tooth root, and the outlet faces the space occupied by the stator winding end. The yoke of the second lamination 3 has a transition oil groove 10. The design of the transition oil groove 10 needs to meet two key spatial connection relationships: firstly, in the axial direction, its position is precisely aligned with the axial oil groove 13 of the first lamination 2, ensuring that the oil flow can flow in unobstructed from the axial main oil passage; secondly, in terms of shape and radial direction, it provides a flow channel to smoothly guide the axial oil flow to the radially inward side, thereby forming a complete cooling oil circuit as defined in claim 1. The cooling oil is pumped in from the oil inlet 11 and first achieves circumferential uniform distribution in the annular oil distribution groove 12. Subsequently, the oil enters each axial oil groove 13 almost synchronously and flows axially towards the end of the iron core. When the oil flows to the transition area formed by the second lamination 3, it flows from the axial oil groove 13 into the transition oil groove 10. Under the guidance of the special structure of the transition oil groove 10, the oil flow direction changes by 90 degrees, from axial flow to radial inward flow, and converges and is guided to the inlet of the oil injection hole 6 of the third lamination 4 (flow direction conversion and convergence). Finally, under the action of system oil pressure, cooling oil is sprayed radially from the oil injection hole 6 at a certain speed and flow rate, forming a cooling oil jet or oil mist. This achieves a dedicated, directional cooling oil path that runs directly from the oil inlet of the housing to the core area of ​​the winding heat generation, without relying on complex housing oil channels and external nozzles, by optimizing the structure of the stator laminations themselves. This greatly improves the cooling efficiency of this hot spot area and fundamentally improves the uniformity of the winding temperature.

[0023] Specifically, the cross-sectional areas of the axial oil groove 13 and the transition oil groove 10 are larger than the cross-sectional area of ​​the injection hole 6. According to the fluid continuity equation (Q = A... V, where Q is the flow rate, A is the cross-sectional area, and V is the velocity, indicates that under stable flow conditions and neglecting leakage, the flow rate Q is equal across all cross-sections. When the cross-sectional area A of the axial oil groove 13 and the transition oil groove 10 is large, the fluid velocity V at that location is relatively low. However, when the fluid reaches the oil injection hole 6, where the cross-sectional area suddenly decreases, the injection hole velocity V must increase significantly in order to achieve the same flow rate. This sharp increase in velocity at the oil injection hole not only improves the injection speed of the cooling oil and enhances its ability to penetrate the winding gap, but also potentially improves the atomization effect of the oil jet, increases the contact area with the winding conductors, and improves the heat exchange efficiency.

[0024] Preferably, the outer edges of the yokes of the first lamination, the second lamination 3, and the third lamination 4 are provided with welding grooves 9 for welding and fixing. The welding grooves 9 are located on one side of the axial oil groove 13 or the transition oil groove 10 along the circumferential direction. When the second lamination 3 is welded, the weld is located on the side of the welding groove away from the oil groove, and the weld corresponds to the side of the first lamination oil groove. Since the welding groove 9 is spatially separated from the functional oil groove, the high temperature and molten metal generated by welding are confined within the welding groove area and will not flow into or block the adjacent oil groove. Oil can still pass through after welding. During assembly, the stator core 1 is pressed into the motor housing 5 without interference.

[0025] Furthermore, at the axial end of the stator core 1, a sealing ring 7 is provided between the third lamination 4 and the motor housing 5. The sealing ring 7 is compressed and installed in this gap, forming an effective axial dynamic or static sealing barrier. It blocks the path of cooling oil leakage from the oil inlet distribution groove 12 or the outer circle of the core directly to the outside of the motor or non-target areas through this assembly gap. All the valuable cooling oil is used for effective cooling, avoiding flow and pressure losses caused by ineffective leakage, and ensuring the flow and injection force of the oil injection hole. Even if there are minor dimensional tolerances or shape errors in the assembly gap between the core and the housing, the sealing ring can effectively compensate, preventing oil leakage and improving product quality and consistency.

[0026] Furthermore, the first, second, and third laminations are respectively provided with marking slots 8 for alignment during stacking. In the automated lamination stacking production line, vision sensors or mechanical positioning pins can identify or align these marking slots 8. Operators or robots only need to align the marking slots 8 of all laminations in the same position for stacking, which can ensure that the axial oil passages 13 of all first laminations 2 are automatically aligned to form straight oil channels, the transition oil passages 10 of all second laminations 3 are precisely connected to the axial oil passages 13, and the oil spray holes 6 of all third laminations 4 are located in the expected circumferential positions. This greatly reduces the skill requirements for operators, improves production efficiency and stacking accuracy, and ensures that the internal oil passages of each stator core are unobstructed and effective in mass production. It is an indispensable design for realizing industrial applications.

[0027] Furthermore, the oil injection hole 6 is located in the middle of the axial direction on the teeth of the third lamination. The winding of the middle layer is wrapped by the inner and outer layers, resulting in the worst heat dissipation conditions and making it a blind spot for traditional cooling methods. By placing the oil injection hole 6 in the middle of the axial direction of the teeth, the center line of the sprayed oil jet can be roughly aligned with the middle layer area at the end of the winding, ensuring that the cooling oil energy acts directly and to the maximum extent on the hottest and most heat-requiring hot spot area.

[0028] Furthermore, the number of oil injection holes 6 and axial oil passages 13 can be one or more. Designers can determine the cooling intensity requirements based on the results of electromagnetic and thermal simulation analysis of the motor. For motors with high heat generation and high heat dissipation requirements, a "full-slot configuration" can be adopted, that is, each stator slot has an oil injection hole 6, and each axial oil passage 13 corresponds to one oil injection hole 6, achieving the most uniform and full-coverage spray cooling. For applications with relatively low heat generation or cost sensitivity, an intermittent or zoned configuration can be adopted, for example, an oil injection hole can be set every one or two teeth, correspondingly reducing the number of axial oil passages.

[0029] A cooling method based on the above stator cooling structure includes the following steps: S1. Inject cooling oil into the oil distribution tank from the oil inlet 11 of the motor housing 5; S2. Cooling oil flows from the oil inlet distribution groove 12 into the axial oil passage groove 13 of the first lamination 2, and flows axially to both ends of the stator core. S3. Cooling oil is guided through the transition oil groove 10 of the second lamination 3 to the oil spray hole 6 of the third lamination. The cooling oil is sprayed out from the oil spray hole 6 and directly acts on the intermediate layer area at the end of the stator winding to cool it.

[0030] In this embodiment, in actual use, cooling oil is pumped into the oil distribution groove 12 through the oil inlet 11. Since the distribution groove 12 is annular, the cooling oil is evenly distributed circumferentially within it. Subsequently, the oil simultaneously enters each axial oil passage groove 13 and flows axially towards both ends of the iron core. When the oil reaches the transition area formed by the second lamination 3, it flows into the transition oil groove 10. Guided by the transition oil groove 10, the oil flow direction gradually changes from axial to radial inward and converges at the inlet of the oil spray hole 6 on the third lamination 4. Finally, under the action of system oil pressure, the cooling oil is sprayed out at high speed from the oil spray hole 6, forming one or more oil jets, which are directly sprayed onto the intermediate layer surface of the stator winding end, achieving efficient heat exchange. To prevent cooling oil leakage from the iron core end, a sealing ring 7 can be installed at this gap to form an axial seal. This stator cooling structure and method of the present invention has a compact structure, high reliability, and allows for precise guidance of cooling oil, effectively improving the cooling effect. It has the characteristics of wide applicability and strong practicality.

[0031] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A stator cooling structure, comprising a stator core (1) and a motor housing (5) coaxially arranged, wherein the stator core (1) is formed by stacking multiple laminations, characterized in that, The stator core (1) includes a first lamination (2), a second lamination (3), and a third lamination (4). The yoke of the first lamination (2) is provided with an axially penetrating oil groove (13). The third lamination (4) is arranged at both ends of the stator core (1) and is provided with an oil spray hole (6). The second lamination (3) is located between the first lamination (2) and the third lamination (4). The yoke of the second lamination (3) is provided with a transition oil groove (10). (10) One end is connected to the axial oil passage groove (13), and the other end is connected to the oil injection hole (6). The inner wall of the motor housing (5) is provided with an annular oil inlet distribution groove (12). The motor housing (5) is provided with an oil inlet (11) connected to the oil inlet distribution groove (12). The oil inlet distribution groove (12) is connected to the axial oil passage groove (13), so that the cooling oil entering from the oil inlet (11) can be guided to the oil injection hole (6) and sprayed out in sequence through the axial oil passage groove (13) and the transition oil groove (10).

2. The stator cooling structure according to claim 1, characterized in that, The cross-sectional area of ​​the axial oil groove (13) and the transition oil groove (10) is larger than the cross-sectional area of ​​the oil injection hole (6).

3. The stator cooling structure according to claim 1, characterized in that, The outer edges of the yokes of the first, second (3) and third (4) are provided with welding grooves (9) for welding and fixing.

4. A stator cooling structure according to claim 3, characterized in that, The welding groove (9) is located on one side of the axial oil groove (13) or transition oil groove (10) along the circumferential direction.

5. A stator cooling structure according to claim 1, characterized in that, At the axial end of the stator core (1), a sealing ring (7) is provided between the third lamination (4) and the motor housing (5).

6. A stator cooling structure according to claim 1, characterized in that, The first, second, and third laminations are respectively provided with marking grooves (8) for alignment during stacking.

7. A stator cooling structure according to claim 1, characterized in that, The oil injection hole (6) is located in the middle position along the axial direction on the toothed part of the third punch.

8. A stator cooling structure according to claim 1, characterized in that, The number of the oil injection hole (6) and the axial oil passage groove (13) is one or more.

9. A cooling method based on the stator cooling structure according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Inject cooling oil into the oil distribution tank from the oil inlet (11) of the motor housing (5); S2. Cooling oil flows from the oil inlet distribution groove (12) into the axial oil passage groove (13) of the first lamination (2) and flows axially to both ends of the stator core. S3. Cooling oil is guided through the transition oil groove (10) of the second lamination (3) to the oil spray hole (6) of the third lamination. The cooling oil is sprayed out from the oil spray hole (6) and directly acts on the intermediate layer area of ​​the stator winding end to cool it.

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