Oil-cooled motor and method for designing oil-cooled motor

Abstract

An oil-cooled motor and a method for designing an oil-cooled motor. The oil-cooled motor comprises a housing (1), a rotor, a stator (2), and a cooling pipe. The rotor is rotatably mounted in the housing. The stator is fixedly mounted in the housing and is annularly arranged on an outer peripheral side of the rotor. The stator comprises a stator yoke and a plurality of tooth parts arranged on a peripheral side of the stator yoke, each tooth part having a winding (3) wound thereon, and a cooling recess (4) being formed between two adjacent windings. The cooling pipe comprises a cooling duct (5), and the cooling duct comprises a plurality of straight pipe sections (51) that are sequentially in communication and are arranged at intervals in the circumferential direction of the stator. Each straight pipe section is embedded in a corresponding cooling recess.

Description

Oil-cooled motor and its design method CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Chinese patent application No. 2023118146454 filed on December 26, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to the technical field of motor heat dissipation, and in particular to an oil-cooled motor and a design method for the oil-cooled motor. Background Art

[0003] As the power density and torque density requirements for electric vehicle drive motors become increasingly higher, motor heat dissipation has become one of the key factors limiting their performance improvement.

[0004] Due to the harsh and high ambient temperature operating environment of electric vehicles, natural cooling alone cannot meet the heat dissipation requirements, requiring forced cooling within the motor. Generally speaking, the design of the motor's electromagnetic structure determines the motor's temperature field, which in turn significantly affects the motor's electromagnetic performance. Therefore, while taking into account both power density and torque density, it is necessary to consider the balanced design of the motor's cooling system and electromagnetic structure to achieve a balance between the motor's electromagnetic performance and heat dissipation performance. Summary of the Invention

[0005] The main purpose of the present disclosure is to propose an oil-cooled motor and a design method for an oil-cooled motor, aiming to provide an oil-cooled motor with high overload capacity and significant cooling effect.

[0006] To achieve the above-mentioned purpose, the present disclosure proposes an oil-cooled motor, wherein the oil-cooled motor includes: a casing; a rotor rotatably mounted in the casing; a stator fixedly mounted in the casing and arranged in an annular manner on the outer circumference of the rotor, the stator including a stator yoke, and a plurality of teeth and a plurality of windings arranged on the circumference of the stator yoke; each of the teeth is wound with one winding, and a cooling groove is formed between two adjacent windings; and a cooling pipeline including a cooling pipe, the cooling pipe including a plurality of straight pipe sections that are connected in sequence and arranged at intervals along the circumference of the stator, and each of the straight pipe sections is embedded in the corresponding cooling groove.

[0007] In some embodiments, a plurality of cooling tubes are provided; the plurality of cooling tubes are arranged at intervals along the circumference of the stator, and the plurality of cooling tubes are arranged in parallel.

[0008] In some embodiments, four cooling pipes are provided; and / or the slot width of the cooling slot is set to a, 4mm≤a≤6mm.

[0009] In some embodiments, an annular air gap is defined between the stator and the rotor;

[0010] The oil-cooled motor also includes a heat-insulating sleeve extending along the axial direction of the stator, the heat-insulating sleeve being arranged at the air gap, the two ends of the heat-insulating sleeve being fixedly connected to the casing to enclose and form a separation chamber that separates the stator and the rotor, and the separation chamber is provided with a liquid inlet and a liquid outlet respectively connected to the liquid inlet end and the liquid outlet end of each cooling pipe.

[0011] In some embodiments, each of the straight pipe sections extends along the axial direction of the stator; each of the cooling pipes further includes a plurality of curved pipe sections, and two adjacent straight pipe sections are located at the same end in the axial direction of the stator and are connected via a curved pipe section.

[0012] In some embodiments, the straight pipe section comprises a copper pipe; and / or the curved pipe section comprises a plastic hose.

[0013] In some embodiments, an outer peripheral wall of the straight pipe section is provided with an insulating layer.

[0014] The present disclosure also provides a design method for an oil-cooled motor, wherein the oil-cooled motor includes a rotor, a stator and a cooling pipeline, wherein the rotor is rotatably mounted in the casing; the stator is fixedly mounted in the casing and annularly arranged on the outer circumference of the rotor, the stator includes a stator yoke, and a plurality of teeth arranged on the circumference of the stator yoke, each of the teeth is wound with one of the windings, and a cooling groove is formed between two adjacent windings, the cooling pipeline includes a cooling pipe, and the cooling pipe includes a plurality of straight pipe sections that are connected in sequence and arranged at intervals along the circumference of the stator, and each straight pipe section is embedded in the corresponding cooling groove; the design method of the oil-cooled motor includes the following steps: obtaining the difference between the heat dissipation of the oil circuit and the copper loss value; and obtaining the size of the cooling pipeline according to the heat dissipation of the oil circuit and the copper loss value.

[0015] In some embodiments, obtaining the size of the cooling pipeline based on the heat dissipation of the oil circuit and the copper loss value includes: determining the correspondence between the inlet and outlet pressure difference of the cooling pipeline and the size of the cooling pipeline when the difference between the heat dissipation of the oil circuit and the copper loss value meets a preset condition; determining the size of the cooling pipeline based on the correspondence between the inlet and outlet pressure difference of the cooling pipeline and the size of the cooling pipeline.

[0016] In some embodiments, determining the cooling line size based on the corresponding relationship between the inlet and outlet pressure difference of the cooling line and the cooling line size includes: determining the inlet and outlet pressure difference of the cooling line based on the kinematic viscosity coefficient of the oil, the wetted perimeter, the oil inlet flow rate, the axial length of the oil channel, and the density of the cooling oil; determining the cooling line size based on the corresponding relationship between the inlet and outlet pressure difference of the cooling line, the cooling line size, and the motor electromagnetic.

[0017] In the technical solution, the rotor is rotatably mounted in the housing, the stator is fixedly mounted in the housing and is annularly arranged on the outer circumference of the rotor, the stator comprising a stator yoke and a plurality of teeth arranged on the circumference of the stator yoke, each of the teeth being wound with a winding, and a cooling groove being formed between each adjacent two windings; the cooling pipe comprises a cooling pipe, the cooling pipe comprising a plurality of straight pipe sections that are sequentially connected and arranged at intervals along the circumference of the stator, each of the straight pipe sections being embedded in the corresponding cooling groove, and the plurality of cooling pipes being arranged at intervals along the circumference of the stator. By embedding the straight pipe sections in the cooling grooves, when the cooling oil in the cooling pipe flows from the liquid inlet to the liquid outlet, the heat on the stator can be transferred to the winding through the inner wall surface of the cooling groove, and then transferred to the cooling pipe, and the cooling oil is transferred to the cooling oil through its pipe wall to achieve the purpose of heat dissipation, thereby providing an oil-cooled motor with high overload capacity and significant cooling effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0019] FIG1 is a perspective schematic diagram of a partial structure of an oil-cooled motor according to some embodiments of the present disclosure;

[0020] FIG2 is a schematic cross-sectional view of the oil-cooled motor in FIG1 ;

[0021] FIG3 is a perspective schematic diagram of the cooling pipe in FIG1 ;

[0022] FIG4 is a schematic diagram of the thermal insulation sleeve in FIG1 ;

[0023] FIG5 is a schematic top view of the oil-cooled motor in FIG1 ;

[0024] FIG6 is a bottom view of the oil-cooled motor in FIG1 ;

[0025] FIG7 is a schematic diagram of two windings and a cooling tank;

[0026] FIG8 is a comparison diagram of the simulation results of the influence of different cooling groove widths on the temperature of the oil-cooled motor in FIG1; and

[0027] FIG9 is a flow chart of a method for designing an oil-cooled motor according to some embodiments of the present disclosure.

[0028] Description of Figure Numbers:

[0029] The realization of the objectives, functional features and advantages of the present disclosure will be further explained with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present disclosure in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present disclosure without making any creative efforts shall fall within the scope of protection of the present disclosure.

[0031] It should be noted that if the embodiments of the present disclosure involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0032] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present disclosure, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present disclosure.

[0033] Due to the harsh and high ambient temperature operating environment of electric vehicles, natural cooling alone cannot meet the heat dissipation requirements, requiring forced cooling within the motor. Generally speaking, the design of the motor's electromagnetic structure determines the motor's temperature field, which in turn significantly affects the motor's electromagnetic performance. Therefore, while taking into account both power density and torque density, it is necessary to consider the balanced design of the motor's cooling system and electromagnetic structure to achieve a balance between the motor's electromagnetic performance and heat dissipation performance.

[0034] In order to solve the above problems, the present disclosure provides an oil-cooled motor, Figure 1 is a three-dimensional schematic diagram of a partial structure of an embodiment of an oil-cooled motor of some embodiments of the present disclosure; Figure 2 is a cross-sectional schematic diagram of the oil-cooled motor in Figure 1; Figure 3 is a three-dimensional schematic diagram of the cooling pipe in Figure 1; Figure 4 is a schematic diagram of the thermal insulation sleeve in Figure 1; Figure 5 is a top view schematic diagram of the oil-cooled motor in Figure 1; Figure 6 is a bottom view schematic diagram of the oil-cooled motor in Figure 1; Figure 7 is a schematic diagram of two windings and cooling grooves; Figure 8 is a comparison diagram of simulation effects of the influence of cooling groove widths of different sizes and the temperature of the oil-cooled motor in Figure 1; Figure 9 is a flow chart of an embodiment of a design method for an oil-cooled motor.

[0035] Please refer to Figures 1 to 3. The oil-cooled motor includes a casing 1, a rotor, a stator 2 and a cooling pipeline. The rotor is rotatably mounted in the casing 1; the stator 2 can be fixedly mounted in the casing 1 and is arranged in a ring around the outer circumference of the rotor. The stator 2 includes a stator 2 yoke and a plurality of teeth arranged around the yoke of the stator 2, and a cooling groove 4 is formed between each adjacent two teeth; the cooling pipeline includes a cooling pipe 5, and the cooling pipe 5 includes a plurality of straight pipe sections 51 that are connected in sequence and arranged at intervals along the circumference of the stator 2, and each straight pipe section 51 is embedded in the corresponding cooling groove 4.

[0036] It should be noted that for motors with higher speeds, it is usually necessary to consider the additional copper loss caused by the skin effect and the proximity effect when calculating the copper loss of the motor. For high-torque density motors, the motor winding 3 usually generates a large amount of heat, causing the temperature in the motor slot to be higher. The increase in temperature and the increase in motor copper loss form a positive feedback relationship, which cannot be ignored in the study of the motor temperature field. In some embodiments, the loss on the rotor is mainly due to the presence of a large number of spatial and temporal harmonics in the air gap magnetic field. These harmonics mainly include tooth slot harmonics caused by the slots of the motor stator 2, spatial magnetomotive force harmonics caused by different distributions of the motor winding 3, magnetic field harmonics caused by uneven air gap permeability due to uneven air gap, time harmonics contained in the controller current, etc., especially when the motor is under high-frequency operating conditions, the loss caused by magnetic field harmonics in the rotor is more serious.

[0037] According to the technical solutions provided in some embodiments of the present disclosure, the rotor is rotatably mounted in the housing 1, the stator 2 is fixedly mounted in the housing 1, and is annularly arranged on the outer circumference of the rotor, the stator 2 may include a stator 2 yoke, and a plurality of teeth arranged on the circumference of the stator 2 yoke, a stator 2 slot is formed between each adjacent two teeth, each tooth is wound with a winding 3, and a cooling slot 4 is formed between each adjacent two windings 3; the cooling pipeline includes a cooling pipe 5, and the cooling pipe 5 may include a plurality of sequentially connected and spaced along the circumference of the stator 2. A straight pipe section 51 is provided, and each straight pipe section 51 is embedded in a corresponding cooling groove 4. A plurality of cooling pipes 5 are arranged at intervals along the circumference of the stator 2. By embedding the straight pipe section 51 in the cooling groove 4, when the cooling oil in the cooling pipe 5 flows from the liquid inlet 5a to the liquid outlet 5b, the heat on the stator 2 can be transferred to the winding 3 through the inner wall surface of the cooling groove 4, and then transferred to the cooling pipe 5. The cooling pipe 5 transfers the heat to the cooling oil through its pipe wall, thereby achieving the purpose of heat dissipation, thereby providing an oil-cooled motor with high overload capacity and significant cooling effect.

[0038] In some embodiments, referring to Figures 5 and 6, a plurality of cooling tubes 5 can be provided; the plurality of cooling tubes 5 can be arranged at intervals along the circumference of the stator 2, and the plurality of cooling tubes 5 can be arranged in parallel. In this way, each cooling tube 5 can dissipate heat independently without affecting each other. This can increase the heat dissipation area, allowing more heat to be dissipated through air convection. At the same time, the parallel arrangement of the plurality of cooling tubes 5 can also reduce the internal fluid resistance of each cooling tube 5, thereby improving the heat dissipation effect. At the same time, it also reduces the pressure difference between the liquid inlet 5a and the liquid outlet 5b.

[0039] To further improve the cooling effect (especially under high-speed conditions), the rational allocation of space for the windings 3 and the space for each straight pipe section 51 within the oil-cooled motor slot is particularly important for heat dissipation. Because the in-slot oil-cooling structure has a relatively poor cooling effect on the motor's high-speed operating conditions, firstly, the equivalent thermal resistance between the stator 2 core and the cooling pipes 5 is large, resulting in higher temperatures under the same heat flow conditions; secondly, ignoring the heat dissipation of the rotor through the shaft and the air at the ends, the rotor heat is mainly conducted to the stator 2 teeth through the air gap, and the in-slot oil-cooling structure has a poor cooling effect on the motor's stator 2 core, resulting in higher rotor temperatures. Therefore, to balance the temperature of the motor under overload conditions and high-speed conditions, the position of the five cooling pipes in the motor slot is optimized.

[0040] In some embodiments, please refer to Figures 7 and 8, four cooling pipes 5 can be provided; and / or the slot width of the cooling slot 4 is set to a, 4mm≤a≤6mm. For example, the value of a can be 4mm, 5mm, or 6mm. Because when the slot depth and slot width of the stator 2 are constant, when the cooling pipe 5 occupies a larger space and the winding 3 occupies a smaller space, the cooling effect is relatively good, but when the same current is passed through the winding 3, the copper loss of the motor will increase; conversely, the cooling effect will decrease, but the copper loss will be relatively small. In some embodiments, when four cooling pipes 5 are provided and the slot width of the cooling slot 4 is set to 5mm, the cooling effect and copper loss change reach an optimal balance.

[0041] In some embodiments, referring to FIG4 , an annular air gap is defined between the stator 2 and the rotor; the oil-cooled motor further includes a heat-insulating sleeve 6 extending axially along the stator 2, the heat-insulating sleeve 6 being disposed at the air gap, the two ends of the heat-insulating sleeve 6 being fixedly connected to the housing 1 to enclose and form a separation chamber separating the stator 2 from the rotor, the separation chamber being provided with a liquid inlet 5a and a liquid outlet 5b respectively connected to the liquid inlet and liquid outlet of each cooling pipe 5. Because the main heat source of the oil-cooled motor is on the stator 2 side, and the rotor is not the largest heat source, the stator 2 and the rotor are separated by the heat-insulating sleeve 6 so that the cooling system can be confined to the enclosed space between the stator 2 and the winding 3, dissipating heat through the heat dissipation structure and isolating the rotor.

[0042] In some embodiments, each straight tube segment 51 can extend axially along the stator 2. Each cooling tube 5 can also include multiple curved tube segments 52. Two adjacent straight tube segments 51 can be located at the same axial end of the stator 2 and connected by a curved tube segment 52. Because the straight tube segments 51 are connected by the curved tube segments 52 to form an S-shape, the length of the cooling tube 5 can be increased, thereby increasing the heat dissipation area and improving heat dissipation efficiency. A larger heat dissipation area can more effectively transfer heat generated by the motor to the surrounding environment, preventing motor overheating. The axial extension of each straight tube segment 51 also increases the contact area between the cooling tube 5 and the cooling oil, improving heat transfer efficiency. This allows for faster transfer of heat generated by the motor to the cooling oil, accelerating the heat dissipation process. It also allows for more even heat distribution within the cooling tube 5. By increasing the length and area of ​​the cooling tube 5, localized heat accumulation within the cooling tube 5 can be reduced, allowing heat to be dissipated more evenly into the surrounding environment. Furthermore, space utilization can be more efficient, especially where space is limited. By extending the axial length of the cooling tube 5, more cooling tubes 5 can be added to the same space, improving the heat dissipation capacity of the entire cooling system.

[0043] In some embodiments, the straight pipe section 51 can comprise a copper tube; and / or the curved pipe section 52 can comprise a plastic hose. Because copper is an excellent thermal conductor with a high thermal conductivity, using copper as the straight pipe section 51 can more effectively conduct heat generated by the motor, allowing heat to be quickly transferred from the motor to the cooling pipe 5, improving heat dissipation efficiency. Furthermore, using copper tubing can effectively resist oil corrosion and extend the service life of the cooling pipe 5. Connecting two adjacent straight pipe sections 51 with a plastic hose facilitates molding and assembly.

[0044] In some embodiments, the outer wall of the straight pipe section 51 and / or the outer wall of the curved pipe section 52 is provided with an insulating layer, and the thickness of the insulating layer is in the range of 0.2 mm to 0.4 mm, for example, the thickness of the insulating layer is 0.2 mm, 0.25 mm, 0.3 mm, or 0.4 mm. When the thickness of the insulating layer is within the above value range, for example, the thickness of the insulating layer is 0.3 mm, it can reduce the impact of the wall thickness of the straight pipe section 51 and / or the curved pipe section 52, and reduce the occurrence of short circuits or other electrical problems between electrical components and lines and the cooling pipe 5. The insulating layer can play a role in safety protection. The insulating layer can effectively isolate the cooling pipe 5 from electrical components, reduce the risk of electrical failure, and effectively prevent the flow of current, reducing the risk of leakage.

[0045] The present disclosure also provides a design method for an oil-cooled motor, which includes a rotor, a stator 2 and a cooling pipeline. The stator 2 is arranged on the outer peripheral side of the rotor. The stator 2 includes a stator 2 yoke and a plurality of teeth arranged on the peripheral side of the stator 2 yoke. A cooling groove 4 is formed between each adjacent two teeth. The cooling pipeline includes a cooling pipe 5. The cooling pipe 5 includes a plurality of straight pipe sections 51 that are connected in sequence and arranged at intervals along the circumference of the stator 2. Each straight pipe section 51 is embedded in a corresponding cooling groove 4.

[0046] Referring to FIG9 , the design method of the oil-cooled motor includes the following steps:

[0047] Step S10: Obtain the difference between the heat dissipation of the oil circuit and the copper loss value.

[0048] In some embodiments, the in-slot oil cooling structure has a relatively poor cooling effect on the motor's high-speed operating conditions. Firstly, the equivalent thermal resistance between the stator 2 core and the cooling pipe 5 is large, resulting in higher temperatures under the same heat flow conditions. Secondly, ignoring the heat dissipation of the rotor through the shaft and the air at the ends, the rotor heat is mainly transferred to the stator 2 teeth through the air gap, and the in-slot oil cooling structure has a poor cooling effect on the motor's stator 2 core, resulting in higher rotor temperatures. Therefore, to balance the temperature of the motor under overload conditions and high-speed conditions, the position of the cooling pipe 5 in the motor slot is optimized. When using a rectangular cross-sectional cooling pipe 5, the width a of the straight pipe section 51 is limited by the width of the cooling slot 4, and the height b of the straight pipe section 51 is limited by the slot depth. As the cooling cross-sectional area changes, the cross-sectional area of ​​the winding 3 will also change. To ensure the electromagnetic performance of the motor, the copper loss of the motor will also change accordingly. Therefore, from a heat dissipation perspective, the size of the cooling pipe 5 needs to be reasonably designed to maximize the difference between the oil heat dissipation P and the copper loss Pcu in the cooling pipe 5. That is, the following relationship is satisfied: ΔP(a,b)={P(a,b)-Pcu(a,b)}max, wherein P(a,b) represents the heat dissipation of the oil circuit when the width of the straight pipe section 51 is a and the height is b, Pcu(a,b) represents the copper loss of ΔP(a,b) when the width of the straight pipe section 51 is a and the height is b, and ΔP(a,b) represents the difference between the heat dissipation P of the oil circuit and the copper loss Pcu when the width of the straight pipe section 51 is a and the height is b.

[0049] Step S20: Obtain the cooling pipe size according to the oil circuit heat dissipation and copper loss value.

[0050] In some embodiments, for the aforementioned in-slot oil cooling structure, given a constant cooling oil flow rate, the smaller the width of straight pipe section 51, the better the overall cooling effect. When the width of straight pipe section 51 is larger, changes in the cooling cross-sectional dimensions have a smaller impact on the cooling effect. This is primarily because changes in the cooling cross-sectional dimensions cause the copper loss in the stator 2 slots to change in the opposite direction, resulting in a minimal difference between the two. Therefore, compared to water cooling of the housing 1 in the related art, the cross-sectional dimensions of the cooling oil in straight pipe section 51 should be selected to minimize significant changes in the area occupied by straight pipe section 51.

[0051] In one embodiment, step S20: obtaining the size of the cooling pipeline according to the heat dissipation of the oil circuit and the copper loss value includes:

[0052] Step S201: When the difference between the heat dissipation of the oil circuit and the copper loss value meets a preset condition, determine the corresponding relationship between the inlet and outlet pressure difference of the cooling pipeline and the cooling pipeline size. In this way, when the difference meets the preset condition, the corresponding relationship between the inlet and outlet pressure difference of the cooling pipeline and the cooling pipeline size can be established.

[0053] Step S202: Determine the cooling pipe size based on the corresponding relationship between the cooling pipe inlet and outlet pressure differential and the cooling pipe size. Because the inlet and outlet pressure differential is a key factor in determining the flow rate and speed of the cooling pipe, the cooling pipe size can be determined based on the established corresponding relationship library after the specific value of the cooling pipe inlet and outlet pressure differential is determined.

[0054] In one embodiment, the cooling pipe size is determined based on the corresponding relationship between the inlet and outlet pressure difference of the cooling pipe and the size of the cooling pipe, including:

[0055] Step S2021: Determine the inlet and outlet pressure difference of the cooling pipeline according to the kinematic viscosity coefficient of the oil, the wetted perimeter, the oil inlet flow rate, the axial length of the oil channel, and the density of the cooling oil.

[0056] In some embodiments, the inlet and outlet pressure difference of the cooling pipeline is expressed as:

[0057] Where τ is the kinematic viscosity of the oil (m² / s), C is the wetted perimeter, C = 2(a + b)(m), Q is the oil inlet flow rate (L / min), l is the axial length of the oil channel (m), and ρ is the density of the cooling oil. The above equation shows that, for a given depth of cooling groove 4, the greater the cross-sectional width of cooling groove 4, the smaller the inlet / outlet pressure differential, and the inlet / outlet pressure differential decreases as the groove depth increases. Therefore, for a given oil inlet flow rate, the smaller the cross-sectional area of ​​cooling groove 4, the better the cooling effect.

[0058] Step S2022: Determine the size of the cooling pipeline according to the inlet and outlet pressure difference of the cooling pipeline, the corresponding relationship between the sizes of the cooling pipeline 5 and the motor electromagnetic.

[0059] In some embodiments, when the oil inlet flow rate is constant, the smaller the cross-sectional area of ​​the cooling groove 4, the better the cooling effect. However, considering the motor performance parameters, it is also necessary to comprehensively consider the magnetic field distribution of the motor to avoid unnecessary interference with the magnetic field of the motor. Based on simulation analysis, according to the results of the space allocation analysis in the stator 2 slot, and considering the feasibility of processing, the cross-sectional width of the cooling groove 4 in the slot is determined to be 5mm, and 4 cooling pipes 5 are provided. When they are arranged in parallel, the volume occupied by the cooling pipes 5 is exactly the increment of the volume in the slot after the slot depth is increased, ensuring that the temperature field of the motor under different working conditions, the iron loss under high-speed working conditions and the eddy current loss of the permanent magnet are small. The oil-cooled motor has a good cooling effect under both overload and high-speed working conditions. For a specific simulation effect comparison diagram, please refer to Figure 8.

[0060] The above description is only a preferred embodiment of the present disclosure and does not limit the patent scope of the present disclosure. All equivalent structural transformations made by using the contents of the present disclosure and the drawings under the inventive concept of the present disclosure, or direct / indirect application in other related technical fields are included in the patent protection scope of the present disclosure.

Claims

1. An oil-cooled motor, comprising: A housing; A rotor rotatably mounted within the housing; A stator fixedly mounted within the housing and disposed annularly around the outer periphery of the rotor, the stator including a stator yoke portion and a plurality of tooth portions provided on the circumferential side of the stator yoke portion, A plurality of windings; each of the tooth portions is wound with one of the windings, and a cooling groove is formed between two adjacent windings; and, A cooling pipeline, including a cooling pipe, the cooling pipe including a plurality of straight pipe segments that are sequentially connected and spaced apart along the circumferential direction of the stator, and each of the straight pipe segments is embedded in a corresponding cooling groove.

2. The oil-cooled motor according to claim 1, wherein, A plurality of the cooling pipes are provided; the plurality of cooling pipes are arranged at intervals along the circumferential direction of the stator.

3. The oil-cooled motor according to claim 2, wherein, The plurality of cooling pipes are arranged in parallel.

4. The oil-cooled motor according to claim 2 or 3, wherein, Four of the cooling pipes are provided.

5. The oil-cooled motor according to any one of claims 1-4, wherein, The width of the notch of the cooling groove is set to a, where 4 mm ≤ a ≤ 6 mm.

6. The oil-cooled motor according to any one of claims 1-5, wherein, An annular air gap is defined between the stator and the rotor.

7. The oil-cooled motor according to any one of claims 1-6, wherein, The oil-cooled motor further includes a heat insulation sleeve extending along the axial direction of the stator, and the heat insulation sleeve is disposed at the air gap.

8. The oil-cooled motor according to claim 7, wherein, Both ends of the heat insulation sleeve are fixedly connected to the housing to enclose and form a separation chamber that separates the stator from the rotor.

9. The oil-cooled motor according to claim 8, wherein, The separation chamber is provided with a liquid inlet and a liquid outlet that are respectively communicated with the liquid inlet end and the liquid outlet end of the cooling pipe.

10. The oil-cooled motor according to any one of claims 1-9, wherein, The straight pipe segment extends along the axial direction of the stator.

11. The oil-cooled motor according to any one of claims 1-10, wherein, The cooling pipe further includes a plurality of bent pipe segments, and two adjacent straight pipe segments at the same end in the axial direction of the stator are connected through one of the bent pipe segments.

12. The oil-cooled motor according to any one of claims 1-11, wherein, The straight pipe segment includes a copper pipe.

13. The oil-cooled motor according to any one of claims 1-12, wherein, The bent pipe segment includes a plastic hose.

14. The oil-cooled motor according to any one of claims 1-13, wherein, An insulating layer is provided on the outer peripheral wall of the straight pipe segment.

15. The oil-cooled motor according to any one of claims 11-14, wherein, An insulating layer is provided on the outer peripheral wall of the bent pipe segment.

16. The oil-cooled motor according to claim 14 or 15, wherein, The thickness of the insulating layer ranges from 0.2 mm to 0.4 mm.

17. The oil-cooled motor according to claim 14 or 15, wherein, The thickness of the insulating layer is 0.3 mm.

18. A design method for an oil-cooled motor, the oil-cooled motor including a rotor, a stator, a plurality of windings, and a cooling pipeline, the rotor being rotatably mounted within the housing; the stator being fixedly mounted within the housing and disposed annularly around the outer periphery of the rotor, the stator including a stator yoke portion and a plurality of tooth portions provided on the circumferential side of the stator yoke portion, each of the tooth portions being wound with one of the windings, a cooling groove being formed between two adjacent windings, the cooling pipeline including a cooling pipe, the cooling pipe including a plurality of straight pipe segments that are sequentially connected and spaced apart along the circumferential direction of the stator, and each of the straight pipe segments being embedded in a corresponding cooling groove; The design method for the oil-cooled motor includes the following steps: Obtain the difference between the heat dissipation of the oil circuit and the copper loss value; Obtain the size of the cooling pipeline according to the heat dissipation of the oil circuit and the copper loss value.

19. The design method of the oil-cooled motor according to claim 18, wherein, The obtaining the size of the cooling pipeline according to the heat dissipation of the oil circuit and the copper loss value includes: When the difference between the heat dissipation of the oil circuit and the copper loss value meets a preset condition, determine the corresponding relationship between the inlet and outlet pressure difference of the cooling pipeline and the size of the cooling pipeline; Determine the size of the cooling pipeline according to the corresponding relationship between the inlet and outlet pressure difference of the cooling pipeline and the size of the cooling pipeline.

20. The design method of the oil-cooled motor according to claim 19, wherein, Determining the size of the cooling pipeline according to the corresponding relationship between the inlet and outlet pressure difference of the cooling pipeline and the size of the cooling pipeline includes: determining the inlet and outlet pressure difference of the cooling pipeline according to the kinematic viscosity coefficient of the oil, the wetted perimeter, the inlet oil flow rate, the axial length of the oil passage, and the density of the cooling oil; Determining the size of the cooling pipeline according to the corresponding relationship between the inlet and outlet pressure difference of the cooling pipeline, the size of the cooling pipeline, and the motor electromagnetics.

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