A housing for a permanent magnet synchronous motor

Abstract

This utility model discloses a housing for a permanent magnet synchronous motor, including a housing body and cooling water channels disposed inside the housing body. The cooling water channels include multiple circumferential water channels arranged circumferentially along the housing body and multiple axial straight channel sections extending axially. The multiple circumferential water channels and the multiple axial straight channel sections are alternately connected and interconnected, forming a continuous cooling flow channel that reciprocates in a Z-shape in the axial direction. The axial straight channel sections are quadratic curves. This utility model achieves a good balance in terms of temperature rise control, flow resistance, temperature uniformity, flow uniformity, and manufacturability, exhibiting excellent overall performance and effectively meeting the cooling requirements of permanent magnet synchronous motors.

Description

Technical Field

[0001] This utility model belongs to the field of motor technology, specifically a housing for a permanent magnet synchronous motor. Background Technology

[0002] During operation, key components of a permanent magnet synchronous motor, such as the stator windings, stator core, and permanent magnets, generate losses and convert them into heat. If this heat cannot be dissipated in time, the temperature rise of these key components will exceed the allowable range, affecting not only the motor's efficient operation but also its service life and reducing operational reliability. The windings have the highest heat generation rate and are the primary focus for cooling; the stator core, as an intermediate link in heat transfer, directly impacts the winding's heat dissipation; while the permanent magnets have a lower heat generation rate, their location on the rotor surface and poor heat dissipation conditions also require close attention. Therefore, an efficient cooling system needs to be designed for permanent magnet synchronous motors.

[0003] However, existing cooling channel structures struggle to achieve a good balance between temperature rise control, temperature distribution uniformity, flow resistance, and manufacturability. For example, in a circumferential spiral channel, the coolant travels a long path along the spiral, causing the water temperature to gradually increase along the flow direction. This results in a significant decrease in cooling capacity in the latter half of the channel, a higher temperature at the outlet, and uneven temperature distribution across the motor. Furthermore, while some existing composite channel structures offer some effectiveness in temperature rise control, their numerous channels, long flow paths, numerous turns, and complex structure lead to extremely high pressure differences between the inlet and outlet, far exceeding those of other structures. This places excessive demands on the pump head, reducing their practical engineering value. Utility Model Content

[0004] In view of the problems existing in the prior art, the purpose of this utility model is to provide a housing for a permanent magnet synchronous motor, which aims to solve the technical problem that the existing housing structure is difficult to balance temperature rise control, flow resistance and processability.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0006] A housing for a permanent magnet synchronous motor includes a housing body and cooling water channels disposed inside the housing body. The cooling water channels include multiple circumferential water channels arranged circumferentially along the housing body and multiple axial straight water channels extending axially. The multiple circumferential water channels and the multiple axial straight water channels are alternately connected and interconnected to form a continuous cooling flow channel that reciprocates in a Z-shape in the axial direction. The axial straight water channels are in the shape of a quadratic curve.

[0007] As a further improvement to the above technical solution:

[0008] The cooling water channel is located inside the wall of the housing body and close to the inner wall surface of the housing body. There is a gap between the housing body and the outer wall of the stator core located inside the housing body.

[0009] The cooling water channel is sandwiched between the inner wall of the housing body and the outer wall of the stator core, and is in direct contact with the outer wall of the stator core.

[0010] The cooling water channel is a cylindrical tubular structure coaxially arranged with the main body of the casing.

[0011] The entire axial straight section has a quadratic curve arc profile on the developed surface of the cylindrical surface where the cooling channel is located, and its two ends are smoothly connected to the ends of the circumferential water channel, forming a U-shaped channel together.

[0012] Along the coolant flow direction, the radius of curvature of the quadratic curve first decreases and then increases, with the radius of curvature varying from 8mm to 15mm. The ratio of chord height to chord length is 0.1 to 0.25. The quadratic curve is a parabolic arc, and its equation is: The chord length is the straight-line distance between the two ends of the axial straight section, and the chord height is the maximum offset of the axial straight section relative to the chord.

[0013] The circumferential water channel has a width of 20mm, a height of 6mm, and a number of 5 channels. The total axial length of the cooling channel is 120mm. The inner diameter of the housing body is 185mm, the outer diameter is 220mm, and the total axial length is 126mm.

[0014] Both the circumferential water channel and the axial straight channel section have rectangular cross sections. The inlet and outlet diameters of the cooling water channel are both 10 mm. A partition is provided between adjacent circumferential water channels, and the width of the partition is 5 mm.

[0015] The cooling water channel is located in the axial middle region of the casing body.

[0016] The housing body includes an inner shell and an outer shell that are coaxially fitted together. The inner wall surface of the outer shell is provided with multiple grooves, and the outer wall surface of the inner shell is provided with corresponding multiple grooves. The inner diameter of the outer shell is adapted to the outer diameter of the inner shell, so that after the inner shell and the outer shell are fitted together, the grooves on the inner wall surface of the outer shell and the grooves on the outer wall surface of the inner shell are aligned and spliced ​​together to form the cooling water channel.

[0017] The beneficial effects of this utility model are:

[0018] (1) Excellent temperature rise control: The cooling water channel adopts a structure that alternates between circumferential water channels and axial straight sections. The circumferential water channels are evenly arranged along the stator circumference, which can simultaneously cool the windings and core in all directions; the axial straight sections effectively extend the heat exchange path. Simulation verification shows that the highest overall temperature of the motor using this utility model structure is only 34.77℃, which can control the temperature rise of key components of the motor within a safe range and effectively ensure the reliable operation of permanent magnets and insulation materials.

[0019] (2) The circumferential water channel is evenly arranged along the stator circumference, and the temperature area is relatively uniformly distributed. No significant temperature difference was detected along the circumferential direction, which avoids local overheating and thermal stress concentration problems. It can effectively prevent thermal problems such as thermal stress deformation, uneven winding resistance and permanent demagnetization of permanent magnets caused by excessive temperature gradient, and improve the operating reliability and service life of the motor.

[0020] (3) The axial straight section adopts a quadratic curve shape, guiding the coolant to transition at a gentler angle in the turning area. This allows the coolant to enter the circumferential channels farther from the inlet more effectively, resulting in a more uniform velocity distribution of the coolant as it flows through each circumferential channel. This avoids the uneven velocity distribution caused by flow separation in traditional right-angle turning structures, significantly reducing the velocity difference between each channel segment. The coolant achieves a more balanced flow throughout the Z-shaped channel. Simulation comparison shows that, compared to a straight channel, the quadratic curve channel significantly reduces the velocity difference of the coolant in each circumferential channel segment, resulting in a more balanced flow distribution. It avoids the formation of local low-velocity dead zones and backflow zones, verifying the positive effect of the curved axial straight section on improving flow uniformity.

[0021] (4) Excellent overall performance with 5 waterways: Through simulation optimization of the number of waterways (based on a straight axial straight section), in the comparison of 3, 4, 5, and 6 waterways, the highest motor temperature (32.69℃) with 5 waterways is significantly better than that with 3 (34.37℃) and 4 (35.23℃), and is basically equivalent to that with 6 (32.46℃). Considering the uniformity of flow and pressure drop level, the average flow velocity with 5 waterways is 2.32m / s, which is higher than that with 3 (1.95m / s) and 6 (2.19m / s), and the pressure difference between the inlet and outlet (10785.9Pa) is much lower than that with 6 waterways (14592.2Pa). Based on this, the geometry of the axial straight section is further optimized with 5 waterways as the benchmark, and the quadratic curve axial straight section is determined to be the optimal solution. Since the number of waterways mainly affects the cross-sectional area and flow distribution of the flow channels, while the geometry of the axial straight section mainly affects the local flow characteristics of the turning area, the two are design parameters of different dimensions in physics. The scheme of 5 waterways + quadratic curve axial straight section obtained by optimizing them separately is the comprehensive optimal scheme.

[0022] (5) The flow resistance is moderate, the pressure difference between the inlet and outlet is only 11465.1 Pa, the pump load is small, which is conducive to reducing system energy consumption. Under the premise of ensuring excellent heat dissipation effect, the pressure difference increases only slightly, thus balancing heat dissipation performance and energy consumption.

[0023] (6) It has a simple structure, good processability, regular cooling water channel structure, moderate number of bends, facilitates casing casting and machining, has low manufacturing cost, controllable scrap rate, and good engineering practical value.

[0024] (7) The cooling water channel is formed by the groove on the outer wall of the inner shell and the groove on the inner wall of the outer shell. The inner shell and the outer shell can be processed independently, which reduces the casting difficulty and machining cost of complex water channel structure and improves the yield. It is especially suitable for Z-shaped reciprocating structure with complex water channel shape. Attached Figure Description

[0025] Figure 1 A perspective view of the cooling water channels of the housing of the permanent magnet synchronous motor provided in Embodiment 1 of this utility model;

[0026] Figure 2 A schematic diagram of the cooling water channels of the housing of the permanent magnet synchronous motor provided in Embodiment 1 of this utility model;

[0027] Figure 3 A schematic diagram of the inner shell of the permanent magnet synchronous motor housing provided in Embodiment 1 of this utility model;

[0028] Figure 4 A schematic diagram of the outer shell of the permanent magnet synchronous motor housing provided in Embodiment 1 of this utility model;

[0029] Figure 5 A diagram showing the overall temperature field distribution of a motor including cooling water channels, provided for Embodiment 1 of this utility model;

[0030] Figure 6 This is a flow velocity field distribution diagram within the cooling water channel provided in Embodiment 1 of the present invention;

[0031] Figure 7 This is a pressure field distribution diagram within the cooling water channel provided in Embodiment 1 of this utility model.

[0032] Reference numerals: 1—Main body of the casing; 11—Inner shell; 111—Third groove; 112—Fourth groove; 113—Outer flange; 12—Outer shell; 121—First groove; 122—Inner flange; 123—Through hole; 2—Cooling water channel; 21—Circumferential water channel; 22—Axial straight section; 23—Baffle plate; 3—Water inlet; 4—Water outlet. Detailed Implementation

[0033] The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of this utility model.

[0034] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0035] Example 1:

[0036] like Figure 1 As shown, this embodiment provides a housing for a permanent magnet synchronous motor, including a housing body 1 and a cooling water channel 2 disposed inside the housing body 1.

[0037] The housing body 1 has a cylindrical structure with an inner diameter of 185 mm, an outer diameter of 220 mm, and a total axial length of 126 mm. The space enclosed by the inner wall of the housing body 1 is used to accommodate the stator core (not shown in the figure) and the rotor assembly (not shown in the figure).

[0038] The cooling channel 2 has an overall cylindrical shape coaxial with the housing body 1, and is located inside the wall thickness of the housing body 1 and close to the inner wall surface of the housing body 1. A small gap is maintained between the cooling channel 2 and the outer wall of the stator core according to the needs of manufacturing tolerances, insulating coating, or assembly process, that is, the cooling channel 2 is adjacent to the stator core. In this embodiment, the small gap is less than or equal to 0.5 mm.

[0039] like Figure 2 As shown, the cooling channel 2 includes multiple circumferential channels 21 arranged circumferentially along the casing body 1 and multiple axial straight channel sections 22 extending axially. The multiple circumferential channels 21 and the multiple axial straight channel sections 22 are alternately connected and interconnected to form a continuous cooling flow channel that zigzags back and forth in the axial direction.

[0040] Specifically, in this embodiment, there are 5 circumferential water channels 21 and 4 axial straight sections 22. The 5 circumferential water channels 21 are arranged at intervals along the axial direction, and adjacent circumferential water channels 21 are connected by an axial straight section 22. The axial straight sections 22 are arranged alternately at the ends of adjacent circumferential water channels 21 in the circumferential direction. Specifically: one end of the first circumferential water channel is connected to the inlet 3, and the other end is connected to one end of the second circumferential water channel through the first axial straight section; the other end of the second circumferential water channel is connected to one end of the third circumferential water channel through the second axial straight section; and so on, with the other end of the last circumferential water channel connected to the outlet 4. In this way, the multiple circumferential water channels 21 and the multiple axial straight sections 22 together form a continuous cooling flow channel that zigzags back and forth in the axial direction.

[0041] In the simulation for optimizing the number of water channels, comparative analyses were conducted on schemes with 3, 4, 5, and 6 water channels (based on straight axial sections). Simulation results show that when the number of water channels increases from 3 to 4, the maximum motor temperature rises from 34.37℃ to 35.23℃; when increasing from 4 to 5, the maximum temperature drops to 32.69℃; and when increasing from 5 to 6, the maximum temperature further decreases to 32.46℃. With the increase in the number of water channels, the inlet and outlet pressure difference continuously rises from 5792.4 Pa (3 channels) to 14592.2 Pa (6 channels), and the average flow velocity first increases from 1.95 m / s (3 channels) to 2.32 m / s (5 channels), then decreases to 2.19 m / s (6 channels). Considering temperature rise control, flow uniformity, and pressure drop, 5 water channels are the optimal choice.

[0042] The circumferential water channel 21 has a width of 20mm, a height of 6mm, and a total axial length of 120mm. It should be noted that the above-mentioned parameters, such as the number, width, height, and total axial length of the circumferential water channel, are preferred embodiments of this invention for a housing body with an inner diameter of 185mm, an outer diameter of 220mm, and a total axial length of 126mm, and do not constitute a limitation on the scope of protection of this invention. Both the circumferential water channel 21 and the axial straight section 22 have rectangular cross-sections. A partition 23, with a width of 5mm, is provided between adjacent circumferential water channels 21. The relation, in which The total axial length of the cooling channel is 120mm. The width of the circumferential waterway 21 is 20mm. Given 5 waterways, the width of the partition is calculated. The thickness is 5mm. The baffle 23 separates adjacent circumferential water channels 21 into independent flow paths, preventing direct lateral flow of coolant between adjacent channels. It forces the coolant to flow in an orderly Z-shaped path: circumferential water channel 21, axial straight section 22, next circumferential water channel 21, axial straight section 22, ensuring uniform flow of coolant across all heat-generating areas. Simultaneously, the baffle 23, as a solid metal wall, provides radial and axial structural support for the housing body 1, enhancing its rigidity and strength when subjected to internal motor pressure and external vibrations.

[0043] Based on the above optimization of the number of water channels, taking a cooling water channel 2 with 5 circumferential water channels 21 and a straight axial straight section 22 as a benchmark, the shape of the axial straight section 22 is further optimized. Since the number of water channels affects the cross-sectional area of ​​the flow channel and the macroscopic flow distribution, while the shape of the axial straight section 22 affects the local flow characteristics of the turning area, the two belong to different design dimensions and can be optimized separately and then combined.

[0044] The axial straight section 22 has a quadratic curve arc profile on the developed surface of the cylindrical surface where the cooling water channel 2 is located. Its two ends smoothly connect to the ends of the circumferential water channels 21, forming a U-shaped flow channel. Along the coolant flow direction, the radius of curvature of the quadratic curve arc gradually decreases and then gradually increases. In this embodiment, the radius of curvature varies from 8mm to 15mm, and the ratio of chord height to chord length is 0.1 to 0.25. The quadratic curve arc is a parabolic arc, with its inlet end tangent to one circumferential water channel 21 at the connection point, and its outlet end tangent to another circumferential water channel 21 at the connection point. The chord length is the straight-line distance between the two ends of the axial straight section 22, and the chord height is the maximum offset of the axial straight section 22 relative to the chord. The quadratic curve flow channel guides the coolant to transition at a gentler angle in the turning area, allowing the coolant to more effectively enter the circumferential water channels farther from the inlet, reducing flow separation and the formation of backflow zones, lowering local flow resistance, and improving overall heat exchange efficiency.

[0045] In this embodiment, the parabola equation corresponding to the axial straight section 22 is: .

[0046] To verify the optimization effect of the quadratic curve axial straight channel section 22, a simulation comparison was conducted between the straight channel with 5 channels as the benchmark and the optimized quadratic curve channel. The results show that the highest motor temperature in the straight channel (benchmark scheme) is 32.69℃, the maximum flow velocity is 2.33 m / s, and the inlet-outlet pressure difference is 10785.9 Pa; while the highest motor temperature in the quadratic curve channel (optimized scheme) is 34.77℃, the maximum flow velocity is 3.61 m / s, and the inlet-outlet pressure difference is 11465.1 Pa. Although the highest temperature and pressure difference are slightly higher after optimization, the difference in coolant velocity in each circumferential channel 21 is significantly reduced, the flow distribution is more balanced, the formation of local low-velocity dead zones and backflow zones is avoided, and the overall heat exchange is more efficient.

[0047] Cooling water channel 2 is located in the axial middle area of ​​the housing body 1. One end of the housing body 1 is provided with a water inlet 3 that communicates with the cooling water channel 2, and the other end is provided with a water outlet 4 that communicates with the cooling water channel 2. The diameter of both the water inlet 3 and the water outlet 4 is 10mm.

[0048] In this embodiment, the cooling water channel 2 is configured as follows: the housing body 1 includes an inner shell 11 and an outer shell 12 that are coaxially sleeved. The inner diameter of the outer shell 12 is adapted to the outer diameter of the inner shell 11, so that after the inner shell 11 and the outer shell 12 are sleeved, they can form a tight fit.

[0049] like Figure 3 As shown, the inner wall surface of the outer casing 12 is provided with multiple grooves, specifically including multiple first grooves 121 extending circumferentially and multiple second grooves extending axially. The multiple first grooves 121 and multiple second grooves are alternately connected and interconnected. The water inlet 3 and the water outlet 4 are opened on the outer casing 12. Figure 4 As shown, the outer wall surface of the inner shell 11 is provided with multiple grooves, specifically including multiple third grooves 111 extending circumferentially and multiple fourth grooves 112 extending axially. The multiple third grooves 111 and multiple fourth grooves 112 are alternately connected and interconnected. The grooves on the inner wall surface of the outer shell 12 correspond one-to-one with the grooves on the outer wall surface of the inner shell 11 in the circumferential direction.

[0050] After the inner shell 11 and the outer shell 12 are fitted together, each of the first grooves 121 is aligned and joined with each of the third grooves 111 to form circumferential water channels 21; each of the second grooves is aligned and joined with each of the fourth grooves 112 to form axial straight channel sections 22. The multiple circumferential water channels 21 and the multiple axial straight channel sections 22 are interconnected to form a complete continuous cooling flow channel.

[0051] To achieve precise alignment of the aforementioned grooves, a positioning structure is provided between the inner shell 11 and the outer shell 12. Specifically:

[0052] One end of the inner shell 11 is provided with an outer flange 113, and the outer diameter of the outer flange 113 is larger than the outer diameter of the inner shell 11. Multiple axial blind holes are provided on the end face of the inner shell 11 away from the outer flange 113.

[0053] One end of the outer shell 12 is provided with an inner flange 122, the inner diameter of which is smaller than the outer diameter of the inner shell 11. Multiple axial through holes 123 are provided on the inner flange 122 along the circumference of the outer shell 12.

[0054] During assembly, insert the end of the inner shell 11 furthest from the outer flange 113 into the outer shell 12 until the end face of the inner shell 11 furthest from the outer flange 113 abuts against the inner flange 122, and the end face of the outer shell 12 furthest from the inner flange 122 abuts against the outer flange 113. At this point, the axial positions of the inner shell 11 and the outer shell 12 are in place. Then, rotate the inner shell 11 or the outer shell 12 circumferentially for fine-tuning, aligning the through holes 123 on the inner flange 122 with the blind holes on the inner shell 11. Then, pass screws through the through holes 123 and screw them into the corresponding blind holes to fix the inner shell 11 and the outer shell 12 relative to each other. Preferably, rubber sealing rings are provided between the outer flange 113 and the outer shell 12, and between the inner shell 11 and the inner flange 122, and sealant is applied.

[0055] After fixing, the first groove 121 and the second groove on the inner wall of the outer shell 12 are precisely aligned and joined with the third groove 111 and the fourth groove 112 on the outer wall of the inner shell 11 to form a complete cooling water channel 2.

[0056] The cooling water channel 2 is sealed between the inner shell 11 and the outer shell 12 by the contact between the outer wall of the inner shell 11 and the inner wall of the outer shell 12. Within the allowable range of machining and assembly errors, minor leakage that may exist at the contact surface will not affect the normal operation of the cooling water channel 2.

[0057] like Figures 5 to 7 As shown in the simulation, the housing in this embodiment works as follows:

[0058] After entering through the inlet 3, the coolant flows sequentially through the circumferential channels 21 and the axial straight channel section 22 along the Z-shaped cooling channel 2. During the flow, the coolant exchanges heat with the casing body 1 and the stator core through the channel wall, carrying away the heat generated by the stator windings, stator core and other components, and finally exits through the outlet 4.

[0059] Regarding temperature field distribution (see) Figure 5The highest overall temperature of the motor using the structure of this embodiment is 34.77℃. The high-temperature area is relatively evenly distributed with no obvious temperature concentration. The temperature distribution of the stator core is relatively uniform, with the tooth temperature slightly higher than the yoke temperature. The cooling effect along the stator circumference is relatively uniform, and the temperature difference between different areas is small. The temperature distribution of the windings along the circumference is relatively even, with the temperature inside the slots significantly lower than outside the slots, and there are no obvious high-temperature concentration areas. The temperature distribution of the casing body 1 is relatively uniform, and no significant temperature difference change was detected along the circumference.

[0060] Regarding the velocity field distribution (see...) Figure 6 In this embodiment, the quadratic curve-shaped flow channel structure makes the flow velocity distribution of the coolant more uniform as it flows through each circumferential channel section. This avoids the local high-speed zones and low-speed stagnation zones formed by flow separation in traditional right-angle bend structures. The velocity difference between each channel section is significantly reduced, and the coolant achieves a more balanced flow throughout the entire Z-shaped flow channel. The maximum flow velocity occurs on the inner side of the bend, at approximately 3.61 m / s, with good flow uniformity and no obvious low-speed dead zones or flow stagnation.

[0061] Regarding the pressure field distribution (see...) Figure 7 In this embodiment, the pressure difference between the inlet and outlet is 11465.1 Pa. The high-pressure zone is concentrated in the first half of the inlet channel, and the low-pressure zone is near the outlet 4. The pressure difference is at a moderate level, which is beneficial to reduce the power consumption of the water pump and avoid impact on the sealing structure.

[0062] Example 2:

[0063] This embodiment provides a housing for a permanent magnet synchronous motor, which differs from Embodiment 1 in the specific arrangement of the cooling water channel 2 within the housing body 1.

[0064] In this embodiment, the cooling water channel 2 is a separate component sandwiched between the inner wall of the housing body 1 and the outer wall of the stator core, and in direct contact with the outer wall of the stator core. Specifically, the inner wall surface of the cylindrical structure of the cooling water channel 2 fits snugly against the outer wall surface of the stator core without any gap between them, in order to maximize heat conduction efficiency.

[0065] The other structures, working principles, and technical effects of this embodiment are the same as those of Embodiment 1, and will not be repeated here.

[0066] Finally, it is necessary to state that the above embodiments are only used to further illustrate the technical solution of this utility model in detail, and should not be construed as limiting the scope of protection of this utility model. Any non-essential improvements and adjustments made by those skilled in the art based on the above content of this utility model shall fall within the scope of protection of this utility model.

Claims

1. A housing for a permanent magnet synchronous motor, characterized in that: The device includes a housing body and a cooling water channel disposed inside the housing body. The cooling water channel includes multiple circumferential water channels arranged around the circumference of the housing body and multiple axial straight water channels extending along the axial direction. The multiple circumferential water channels and the multiple axial straight water channels are alternately connected and interconnected to form a continuous cooling flow channel that zigzags back and forth in the axial direction. The axial straight water channels are quadratic curves.

2. The housing according to claim 1, characterized in that: The cooling water channel is located inside the wall of the housing body and close to the inner wall surface of the housing body. There is a gap between the housing body and the outer wall of the stator core located inside the housing body.

3. The housing according to claim 1, characterized in that: The cooling water channel is sandwiched between the inner wall of the housing body and the outer wall of the stator core, and is in direct contact with the outer wall of the stator core.

4. The housing according to claim 1, characterized in that: The cooling water channel is a cylindrical tubular structure coaxially arranged with the main body of the casing.

5. The housing according to claim 4, characterized in that: The entire axial straight section has a quadratic curve arc profile on the developed surface of the cylindrical surface where the cooling channel is located, and its two ends are smoothly connected to the ends of the circumferential water channel, forming a U-shaped channel together.

6. The housing according to claim 5, characterized in that: Along the coolant flow direction, the radius of curvature of the quadratic curve first decreases and then increases, with the radius of curvature varying from 8mm to 15mm. The ratio of chord height to chord length is 0.1 to 0.

25. The quadratic curve is a parabolic arc, and its equation is: The chord length is the straight-line distance between the two ends of the axial straight section, and the chord height is the maximum offset of the axial straight section relative to the chord.

7. The housing according to claim 1, characterized in that: The circumferential water channel has a width of 20mm, a height of 6mm, and a number of 5 channels. The total axial length of the cooling channel is 120mm. The inner diameter of the housing body is 185mm, the outer diameter is 220mm, and the total axial length is 126mm.

8. The housing according to claim 1, characterized in that: Both the circumferential water channel and the axial straight channel section have rectangular cross sections. The inlet and outlet diameters of the cooling water channel are both 10 mm. A partition is provided between adjacent circumferential water channels, and the width of the partition is 5 mm.

9. The housing according to claim 1, characterized in that: The cooling water channel is located in the axial middle region of the casing body.

10. The housing according to claim 2, characterized in that: The housing body includes an inner shell and an outer shell that are coaxially fitted together. The inner wall surface of the outer shell is provided with multiple grooves, and the outer wall surface of the inner shell is provided with corresponding multiple grooves. The inner diameter of the outer shell is adapted to the outer diameter of the inner shell, so that after the inner shell and the outer shell are fitted together, the grooves on the inner wall surface of the outer shell and the grooves on the outer wall surface of the inner shell are aligned and spliced ​​together to form the cooling water channel.

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