A motor stator full immersion cooling system and in-wheel motor

Abstract

This invention provides a fully immersion cooling system for a motor stator and a hub motor, relating to the field of hub motor technology. The fully immersion cooling system for the motor stator includes a stator housing, a stator assembly, and a liquid cooling device. The inner cavity of the stator housing is configured as a cooling chamber. The stator assembly is disposed within the cooling chamber. The liquid cooling device includes an inlet pipe and a return pipe. The outlet end of the inlet pipe is connected to the cooling chamber, and the return end of the return pipe is disposed within the cooling chamber. The height of the return end is greater than the height of the stator assembly. This invention achieves stator cooling through full immersion, which not only effectively eliminates cooling dead zones and achieves uniform heat dissipation of the stator assembly, but also prevents the coolant from contacting the rotor, effectively reducing air gap oil churning losses and improving motor operating efficiency. Furthermore, it offers high heat dissipation efficiency, a simple and reliable structure, and low operating and maintenance costs.

Description

Technical Field

[0001] This invention relates to the field of hub motor technology, specifically to a motor stator full-immersion cooling system and a hub motor. Background Technology

[0002] As a core drive component in new energy vehicles and special vehicles, hub motors offer advantages such as compact structure, high power transmission efficiency, and high space utilization. Their operational stability and service life directly determine the overall performance of the machine. Because hub motor stator assemblies generate a large amount of heat during operation, especially under high-power, long-term continuous operation, heat can easily accumulate. If this heat cannot be dissipated efficiently and promptly, it can lead to increased stator winding temperature, decreased insulation performance, and in severe cases, winding burnout, demagnetization of permanent magnets, and other malfunctions, significantly shortening the motor's lifespan and even affecting the normal operation of the equipment. Therefore, the design of the cooling system is a crucial aspect of hub motor development.

[0003] Currently, most existing hub motor stator cooling systems use spray cooling, which involves atomizing or directionally spraying coolant onto the stator surface using a spray device, relying on the evaporation and flow of the coolant to remove the heat generated by the stator. However, this traditional spray cooling method has many inherent defects and cannot meet the high-efficiency heat dissipation requirements of hub motors: First, spray cooling is limited by the nozzle arrangement, spray angle, and coolant flow distribution, which easily creates cooling dead zones in areas such as the winding gaps of the stator assembly. The heat in these areas cannot be carried away in time, resulting in excessively high local stator temperatures and affecting the overall operational stability of the motor. Second, the distribution of coolant during spraying is difficult to achieve completely uniformity, and the heat dissipation rate varies greatly in different areas of the stator, easily generating significant temperature gradients. This not only reduces heat dissipation efficiency but may also cause stator structural deformation due to thermal stress, affecting the assembly accuracy and operational reliability of the motor. Finally, during spray cooling, some coolant enters the air gap between the stator and rotor, and the oil mist or droplets formed by the spray will collide and rub violently with the high-speed rotating rotor, generating significant air gap churning losses, increasing the motor's energy consumption, and reducing motor operating efficiency. Experiments have shown that the presence of churning losses can significantly reduce motor operating efficiency, thereby affecting the overall range of the motor.

[0004] Therefore, developing a hub motor stator cooling system that can overcome the above-mentioned defects, achieve uniform heat dissipation of the stator, reduce cooling dead zones, and reduce oil churning losses has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a fully immersed cooling system for motor stators and a hub motor to solve the aforementioned technical problems in the prior art; the preferred technical solutions among the various technical solutions provided by this invention can produce numerous technical effects, as detailed below.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The present invention provides a fully immersed cooling system for a motor stator, comprising a stator housing, a stator assembly, and a liquid cooling device, wherein: the inner cavity of the stator housing is configured as a cooling chamber; the stator assembly is disposed within the cooling chamber; the liquid cooling device includes an inlet pipe and a return pipe, the outlet end of the inlet pipe is connected to the cooling chamber, and the return end of the return pipe is disposed within the cooling chamber, the height of the return end being greater than the height of the stator assembly.

[0008] Preferably, the top side of the stator housing is provided with an exhaust hole; the height of the exhaust hole is greater than the height of the return end.

[0009] Preferably, the motor stator full-immersion cooling system includes a central shaft, wherein: the stator housing is fixedly sleeved on the central shaft; and the stator assembly is fixedly sleeved on the central shaft.

[0010] Preferably, the central shaft is provided with a receiving channel running through it axially, wherein: the liquid outlet end of the liquid inlet pipe is inserted into the receiving channel and passes through the bottom shaft wall of the receiving channel to communicate with the cooling cavity; the return end of the liquid return pipe runs along the receiving channel and passes through the top shaft wall of the receiving channel to be inserted into the cooling cavity.

[0011] The present invention provides a hub motor, including any of the aforementioned motor stator full-immersion cooling systems.

[0012] Preferably, the stator assembly includes a stator core and a stator winding, wherein: the stator core includes stator teeth evenly arranged circumferentially; the stator winding is wound on the winding section of the stator teeth, and the tooth body section of the stator teeth passes through the stator housing and is located outside the stator housing.

[0013] Preferably, the hub motor includes a rotor assembly, which includes a plurality of permanent magnets uniformly arranged circumferentially. Each permanent magnet includes an integrally formed axial magnetic pole segment, a first transition segment, and a radial magnetic pole segment. The stator tooth segment includes an integrally formed axial tooth segment, a second transition segment, and a radial tooth segment. The axial tooth segment is arranged radially along the stator core, and the radial tooth segment is arranged axially along the stator core. The second transition segment connects the axial tooth segment and the radial tooth segment. The axial tooth segment, the second transition segment, and the radial tooth segment correspond to the axial magnetic pole segment, the first transition segment, and the radial magnetic pole segment, respectively.

[0014] Preferably, the second transition segment is adapted to the first transition segment; both the first transition segment and the second transition segment are configured as arc shapes.

[0015] Preferably, the number of rotor assemblies is set to one, and the rotor assembly is disposed on one side of the stator assembly.

[0016] Preferably, the number of rotor assemblies is set to two, and the two rotor assemblies are respectively disposed on both sides of the stator assembly.

[0017] The stator full-immersion cooling system and hub motor provided by the present invention have at least the following beneficial effects: 1. Eliminate cooling dead zones and achieve uniform heat dissipation of stator components: This invention places the stator assembly entirely within the cooling chamber of the stator housing. Coolant continuously flows into the cooling chamber through the inlet pipe, gradually raising the liquid level until it completely submerges the stator assembly. This ensures that all parts of the stator assembly (including winding gaps and the stator core) are in full contact with the coolant, completely solving the cooling dead zone problem caused by nozzle arrangement limitations in traditional spray cooling. This ensures uniform heat dissipation in all areas of the stator assembly, effectively reducing the stator temperature gradient, avoiding local overheating, and significantly improving the uniformity and comprehensiveness of stator heat dissipation. In turn, it protects the insulation performance of the stator windings and prevents winding damage or permanent magnet demagnetization failures caused by local high temperatures.

[0018] II. Reduce oil churning losses in the air gap and improve motor operating efficiency: This invention places the return end of the return pipe inside the cooling chamber and at a height higher than the stator assembly, so that the coolant maintains a stable liquid level in the cooling chamber and is always in a static or slow flow state. This avoids the situation in traditional spray cooling where the coolant atomizes and enters the air gap, colliding and rubbing against the high-speed rotating rotor. This significantly reduces the oil churning loss in the air gap, reduces motor energy consumption, effectively improves motor operating efficiency, and also reduces the noise generated by oil churning, improves motor operating stability, and indirectly improves the overall range of the machine.

[0019] III. Improved heat dissipation efficiency to meet the demands of high-power operating conditions: The coolant makes full contact with the stator assembly, which significantly increases the heat dissipation contact area compared to the partial contact of traditional spray cooling. The coolant can absorb the heat generated by the stator assembly more efficiently and then overflow through the return pipe, forming a continuous and stable cooling cycle. This significantly improves heat dissipation efficiency and can effectively remove the large amount of heat accumulated in the stator under high power and long-term operation. It effectively controls the stator temperature, ensures stable operation of the hub motor under harsh conditions, and extends the motor's service life.

[0020] IV. Simple and reliable structure, reducing usage and maintenance costs: This invention achieves full stator immersion cooling through a simple combination of the stator housing, inlet pipe, and return pipe, eliminating the need for complex spray devices, nozzle adjustment mechanisms, and other components. Its simple structure and convenient assembly reduce the manufacturing cost of the cooling system. At the same time, the coolant circulation process is stable, reducing the problems of easy clogging and damage of the spray device, lowering the difficulty and cost of system maintenance, and improving the overall reliability and service life of the cooling system. Attached Figure Description

[0021] 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 and Figure 2 This is a schematic diagram of the structure of the motor stator full-immersion cooling system of the present invention; Figure 3 This is a structural schematic diagram of the motor stator full immersion cooling system of the present invention from the end face perspective (partial cross-section); Figure 4 This is a schematic diagram of the structure of the central shaft and stator assembly of the present invention; Figure 5 This is a schematic diagram of the structure of the single-stator single-rotor hub motor of the present invention; Figure 6 This is a schematic diagram of the structure of the central shaft and rotor assembly of the present invention; Figure 7 This is a schematic diagram of the structure of the single-stator dual-rotor hub motor of the present invention.

[0023] Figure Labels 1. Stator housing; 11. Cooling chamber; 12. Exhaust vent; 2. Stator assembly; 21. Stator core; 211. Stator teeth; 2111. Winding section; 2112. Axial tooth section; 2113. Second transition section; 2114. Radial tooth section; 22. Stator winding; 3. Liquid cooling device; 31. Liquid inlet pipe; 32. Liquid return pipe; 4. Central shaft; 41. Receiving channel; 5. Rotor assembly; 51. Rotor disk; 52. Permanent magnet; 521. Axial pole section; 522. First transition section; 523. Radial pole section. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] Example 1: This invention provides a fully immersed cooling system for motor stators, referenced in [reference]. Figures 1 to 4 As shown, the motor stator fully immersed cooling system includes a stator housing 1, a stator assembly 2, and a liquid cooling device 3.

[0026] The inner cavity of the stator housing 1 is configured as a cooling chamber 11; the cooling chamber 11 is an independent chamber, and the stator assembly 2 is disposed in the cooling chamber 11; the liquid cooling device 3 includes an inlet pipe 31 and a return pipe 32, the outlet end of the inlet pipe 31 is connected to the cooling chamber 11, and the return end of the return pipe 32 is disposed in the cooling chamber 11, and the height of the return end is greater than the height of the top of the stator assembly 2.

[0027] In use, the inlet pipe 31 is connected to a cooling oil pump and a radiator, and the return pipe 32 is connected to the radiator. The oil pump, the inlet pipe 31, the cooling chamber 11, the return pipe 32, and the radiator form a coolant circulation loop.

[0028] Specifically, during cooling, the coolant enters the cooling chamber 11 through the inlet pipe 31. As the coolant continues to flow in, the liquid level gradually decreases and rises, completely immersing the stator assembly 2 (including all stator windings 22). When the liquid level reaches the return end, the coolant enters the return pipe 32 from the return end and flows out from the return pipe 32.

[0029] The stator housing 1, stator assembly 2, and liquid cooling device 3 of this invention work together to achieve stator cooling through full immersion. This not only effectively eliminates cooling dead zones and achieves uniform heat dissipation of the stator assembly, but also ensures that the coolant does not contact the rotor, effectively reducing air gap oil churning losses and improving motor operating efficiency. At the same time, it has high heat dissipation efficiency, simple and reliable structure, and low use and maintenance costs.

[0030] Example 2: Example 2 is based on Example 1: like Figures 1 to 4 As shown, an exhaust port 12 is provided on the top side of the stator housing 1; the height of the exhaust port 12 is greater than the height of the return end.

[0031] During the process of injecting coolant into the cooling chamber 11, air inside the chamber is compressed to the top. If this air is not expelled in time, it will form an air resistance, hindering the flow of coolant and the rise of the liquid level. This will prevent the stator assembly 2 from being completely and quickly submerged. At the same time, the presence of air will reduce the contact area between the coolant and the stator assembly 2, thus reducing heat dissipation efficiency. This invention provides an exhaust port 12 on the top side of the stator housing 1, with the exhaust port 12 being higher than the return end. This allows the air inside the cooling chamber 11 to be naturally expelled from the exhaust port 12 as the coolant level rises, completely eliminating air resistance interference. This ensures that the coolant can smoothly fill the cooling chamber and completely submerge the stator assembly, guaranteeing the stable realization of full immersion cooling and further improving the uniformity and efficiency of heat dissipation. Meanwhile, the coolant will expand slightly due to heat absorption during the cooling process. The temperature rise in the cooling chamber 11 during motor operation will also cause the gas in the chamber to expand. If the pressure cannot be released in time, it will put additional pressure on the sealing structure of the stator housing 1. Long-term use will easily lead to aging of the seals and coolant leakage. The exhaust port 12 can release the expansion pressure in the cooling chamber 11 in time, so that the pressure in the chamber is balanced with the outside, effectively protecting the sealing performance of the stator housing 1, avoiding coolant leakage, reducing the probability of system failure, and improving the operational reliability and service life of the cooling system.

[0032] Furthermore, an oil-gas separation device, such as an oil-gas separation valve, is connected to the exhaust port 12.

[0033] As an optional implementation, the motor stator full immersion cooling system includes a central shaft 4, with the stator housing 1 fixedly sleeved on the central shaft 4; the stator assembly 2 is fixedly sleeved on the central shaft 4, and the stator housing 1 and the stator assembly 2 are coaxially arranged, which can effectively ensure assembly accuracy. At the same time, coaxial assembly can reduce the vibration of the stator assembly 2 during motor operation, thereby ensuring the stability of motor operation.

[0034] As an optional implementation, the central shaft 4 is provided with a receiving channel 41 running through it along the axial direction. The liquid outlet end of the liquid inlet pipe 31 is inserted into the receiving channel 41 and passes through the bottom shaft wall of the receiving channel 41 to connect with the cooling chamber 11. The return end of the liquid return pipe 32 runs along the receiving channel 41 and passes through the top shaft wall of the receiving channel 41 to be inserted into the cooling chamber 11.

[0035] The inlet pipe 31 and the return pipe 32 are both set in the accommodating channel 41 of the central shaft 4, realizing the built-in arrangement of the pipeline. This eliminates the need to occupy additional space outside or inside the motor, effectively saving installation space and adapting to the compact design requirements of the hub motor. At the same time, it avoids interference between the pipeline and other components, improving the rationality of the overall structure of the motor.

[0036] Example 3 Example 3 is based on Example 2: This invention provides a hub motor, such as Figures 1 to 6 As shown, the hub motor includes the motor stator fully immersed cooling system.

[0037] The stator assembly 2 includes a stator core 21 and a stator winding 22. The stator core 21 includes stator teeth 211 evenly arranged in the circumferential direction. The stator teeth 211 include a winding section 2111 and a tooth body section integrally arranged in the axial direction of the stator core 21. The stator winding 22 is wound on the winding section 2111. The tooth body section passes through the stator housing 1 and is located outside the stator housing 1. The gap between the stator housing 1 and the tooth body section is sealed.

[0038] The hub motor includes a rotor assembly 5, which includes a rotor disk 51 and permanent magnets 52. The rotor disk 51 is rotatably mounted on a central shaft 4 via bearings. The number of permanent magnets 52 is set to multiple, and all permanent magnets 52 are evenly arranged on the rotor disk 51 circumferentially. Each permanent magnet 52 includes an axial magnetic pole section 521, a first transition section 522, and a radial magnetic pole section 523. The axial magnetic pole section 521, the first transition section 522, and the radial magnetic pole section 523 are integrally arranged. The axial magnetic pole section 521 is arranged radially along the rotor disk 51, and the radial magnetic pole section 523 is arranged axially along the rotor disk 51. The first transition section 522 is connected between the axial magnetic pole section 521 and the radial magnetic pole section 523.

[0039] The stator tooth 211 includes an axial tooth section 2112, a second transition section 2113, and a radial tooth section 2114. The axial tooth section 2112, the second transition section 2113, and the radial tooth section 2114 are integrally formed. The axial tooth section 2112 is arranged radially along the stator core 21, and the radial tooth section 2114 is arranged axially along the stator core 21. The second transition section 2113 is connected between the axial tooth section 2112 and the radial tooth section 2114. The axial tooth section 2112, the second transition section 2113, and the radial tooth section 2114 correspond to the axial magnetic pole section 521, the first transition section 522, and the radial magnetic pole section 523, respectively.

[0040] This setup has at least the following effects: Firstly, the rotor permanent magnet adopts an integrated axial magnetic pole section, a first transition section, and a radial magnetic pole section, while the stator teeth correspondingly adopt an integrated axial tooth body section, a second transition section, and a radial tooth body section, with each section structure corresponding one-to-one. This achieves a smooth transition between axial and radial magnetic flux, effectively reducing magnetic resistance during the flux conversion process, reducing magnetic energy loss, and significantly improving magnetic field coupling efficiency. This allows the magnetic field generated by the permanent magnet to be fully utilized by the stator windings, thereby improving the energy conversion efficiency of the motor. Secondly, the axial and radial segmented structure of the permanent magnet and stator teeth can make full use of the axial and radial space of the motor at the same time, breaking the limitation of traditional single flux motors that can only utilize space in one direction. Without increasing the overall volume of the motor, it increases the effective coupling area between the permanent magnet and the stator teeth, effectively extending the effective length of electromagnetic coupling, and significantly improving the torque density and power density of the motor. It can better meet the needs of high-load, small-volume equipment. Compared with traditional motors, the torque density can be significantly improved.

[0041] Third, the hub motor combines the advantages of both radial flux motors and axial flux motors. It has the characteristics of short axial length and compact structure of axial flux motors, as well as the advantages of strong load capacity of radial flux motors. It can be widely used in various fields such as new energy vehicles, industrial drives, and precision control. It is especially suitable for scenarios with high requirements for motor size, torque density and operation stability, and has great practical value and promotion prospects.

[0042] As an optional implementation, the second transition segment 2113 is adapted to the first transition segment 522; both the first transition segment 522 and the second transition segment 2113 are configured as arc shapes.

[0043] The arc-shaped transition section design enables seamless and smooth connection between the axial magnetic pole section 521 and the radial magnetic pole section 523, and between the axial tooth section 2112 and the radial tooth section 2114. This avoids abrupt changes in magnetic flux caused by right-angle or broken-line transitions, effectively reducing magnetic resistance during the axial and radial conversion process, further reducing magnetic energy loss, and improving magnetic field coupling efficiency. At the same time, the matching design of the second transition section 2113 and the first transition section 522 ensures that the gap between the rotor permanent magnet 52 and the stator teeth 211 is uniform, avoiding magnetic field leakage and local magnetic saturation problems caused by excessively large or small local gaps. This ensures the uniformity of the motor's magnetic field distribution, reduces torque pulsation, and makes the motor run more smoothly.

[0044] As an optional implementation, the receiving channel 41 is also a wiring channel, with a wiring port on its end wall. The wire harness of the stator winding 22 is connected to the external circuit through the wiring port and the receiving channel 41, and the wiring is neat and orderly.

[0045] As an optional implementation, the number of rotor assemblies 5 is set to one, and the rotor assembly 5 is disposed on one side of the stator assembly 2.

[0046] Example 3 forms a single-rotor composite flux permanent magnet motor.

[0047] Example 4 The difference between Example 4 and Example 3 is that: like Figure 7As shown, the number of rotor assemblies 5 is set to two, and the two rotor assemblies 5 are respectively arranged on both sides of the stator assembly 2. Stator teeth 211 and stator windings 22 are arranged on both sides of the stator core 21.

[0048] Example 4 forms a dual-rotor composite flux permanent magnet motor.

[0049] In the description of this application, it should be understood that the terms "upper", "lower", "inner", "outer", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0050] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" or "several" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0051] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0052] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A fully immersion cooling system for a motor stator, characterized in that, Includes stator housing, stator assembly, and liquid cooling system, wherein: The inner cavity of the stator housing is configured as a cooling cavity; The stator assembly is disposed within the cooling cavity; The liquid cooling device includes an inlet pipe and a return pipe. The outlet end of the inlet pipe is connected to the cooling chamber, and the return end of the return pipe is located inside the cooling chamber. The height of the return end is greater than the height of the stator assembly.

2. The motor stator full-immersion cooling system according to claim 1, characterized in that, The top side of the stator housing is provided with an exhaust hole; The height of the exhaust port is greater than the height of the return end.

3. The motor stator full-immersion cooling system according to claim 1, characterized in that, The motor stator full-immersion cooling system includes a central shaft, wherein: The stator housing is fixedly sleeved on the central shaft; The stator assembly is fixedly sleeved on the central shaft.

4. The motor stator full-immersion cooling system according to claim 3, characterized in that, The central shaft is provided with a accommodating channel running through it axially, wherein: The liquid outlet end of the inlet pipe is inserted into the accommodating channel and passes through the bottom shaft wall of the accommodating channel to communicate with the cooling cavity; The return end of the return pipe is inserted into the cooling chamber along the receiving channel and through the top shaft wall of the receiving channel.

5. A hub motor, characterized in that, Includes the motor stator full-immersion cooling system as described in any one of claims 1 to 4.

6. The hub motor according to claim 5, characterized in that, The stator assembly includes a stator core and stator windings, wherein: The stator core includes stator teeth evenly arranged circumferentially; The stator winding is wound on the winding section of the stator tooth, and the tooth body section of the stator tooth passes through the stator housing and is located outside the stator housing.

7. The hub motor according to claim 6, characterized in that, The hub motor includes a rotor assembly, which includes a plurality of permanent magnets uniformly arranged circumferentially. Each permanent magnet includes an integrally formed axial magnetic pole section, a first transition section, and a radial magnetic pole section. The stator tooth body segment includes an integrally formed axial tooth body segment, a second transition segment, and a radial tooth body segment. The axial tooth body segment is arranged radially along the stator core, and the radial tooth body segment is arranged axially along the stator core. The second transition segment is connected between the axial tooth body segment and the radial tooth body segment. The axial tooth body segment, the second transition segment, and the radial tooth body segment correspond to the axial magnetic pole segment, the first transition segment, and the radial magnetic pole segment, respectively.

8. The hub motor according to claim 7, characterized in that, The second transition segment is adapted to the first transition segment; Both the first transition segment and the second transition segment are set to be arc-shaped.

9. The hub motor according to claim 7, characterized in that, The number of rotor assemblies is set to one, and the rotor assembly is disposed on one side of the stator assembly.

10. The hub motor according to claim 7, characterized in that, The number of rotor assemblies is set to two, and the two rotor assemblies are respectively arranged on both sides of the stator assembly.

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