A motor based on lavet pipe heat dissipation

Abstract

The application belongs to the technical field of motor cooling, and particularly relates to a motor based on Laval pipe heat dissipation, which comprises a shell, wherein the shell is divided into a fan shell and a heat dissipation shell as a whole; the inside of the fan shell is provided with a cooling fan; the inside of the heat dissipation shell is provided with a motor mounting frame, the circumferential inner wall of the motor mounting frame is provided with a motor stator, the inside of the motor mounting frame is provided with a motor shaft, the circumferential outer wall of the motor shaft is sleeved with a motor rotor, and the end of the motor shaft is connected with the cooling fan; a plurality of cooling cavities are formed in the body of the heat dissipation shell; the motor based on Laval pipe heat dissipation is provided, and the cooling cavities on the heat dissipation shell are arranged as a Laval pipe structure composed of an inlet section, a throat pipe and an outlet section, so that the cooling air blown by the cooling fan is accelerated through the throat pipe to form a high-speed airflow to strengthen convective heat transfer, and the problems of insufficient heat dissipation efficiency and excessively high local temperature rise of the existing motor in a limited space are solved.

Description

Technical Field

[0001] This invention belongs to the field of motor cooling technology, specifically relating to a motor based on Laval tube heat dissipation. Background Technology

[0002] As motor products continue to develop towards higher power density, lighter weight, and integration, their internal space is becoming increasingly compact. However, the copper loss, iron loss, and mechanical loss generated by components such as stator windings, rotor cores, and bearings during operation are significant, leading to heat concentration and a noticeable temperature rise. If the heat dissipation capacity is insufficient, it will directly cause a series of problems such as accelerated aging of winding insulation, increased risk of permanent magnet demagnetization, bearing lubrication failure, and decreased overall efficiency and reliability. Therefore, achieving efficient and controllable heat dissipation and temperature management within a limited volume has become a core research direction in motor structural design.

[0003] Existing motors typically employ single or combined cooling methods such as natural convection of the casing, forced air cooling by axial fans, extended surface cooling fins, or water cooling jackets. In space-constrained applications, traditional air-cooled structures often face challenges such as low airflow organization efficiency, difficulty in eliminating local hot spots, and uneven distribution of cooling airflow. While water-cooling solutions offer stronger heat dissipation capabilities, they require additional pumps, piping, and sealing structures, significantly increasing cost and complexity. Furthermore, motors of different power ratings and installation conditions exhibit significant differences in heat source distribution and fan parameters. Existing cooling structures often rely on empirical design, lacking a systematic design basis for the relationship between cooling channel geometry and aerodynamic acceleration characteristics, making it difficult to achieve an optimal match between heat dissipation performance and space utilization.

[0004] Therefore, it is necessary to propose a new type of motor heat dissipation structure. Summary of the Invention

[0005] In view of this, the present invention provides a motor based on Laval tube heat dissipation, which aims to improve convective heat transfer by setting the cooling cavity on the heat dissipation shell as a Laval tube structure consisting of an inlet section, a throat section and an outlet section. The cooling air blown in by the cooling fan is accelerated by the throat section to form a high-speed airflow. This solves the problems of insufficient heat dissipation efficiency and excessive local temperature rise in existing motors in a limited space, and achieves the effect of significantly improving heat dissipation performance and ensuring long-term reliable operation of the motor.

[0006] A motor based on Laval tube heat dissipation, comprising:

[0007] The housing is divided into a fan housing and a heat dissipation housing, and the ends of the fan housing and the heat dissipation housing are connected as an integral structure.

[0008] The fan housing is equipped with a cooling fan;

[0009] The heat dissipation housing has a motor mounting bracket inside. The motor mounting bracket is a cylindrical structure. The motor stator is provided on the inner circumference of the motor mounting bracket. The motor shaft is provided inside the motor mounting bracket. The two ends of the motor shaft are rotatably connected to the two ends of the motor mounting bracket. The motor rotor is fitted on the outer circumference of the motor shaft. The end of the motor shaft is connected to the cooling fan.

[0010] The heat dissipation shell has several cooling chambers on its main body. All cooling chambers have identical structures, and each chamber is configured to consist of an inlet section, a throat, and an outlet section. The central axis of each cooling chamber is parallel to the motor shaft. In each cooling chamber, the inlet and outlet sections are conical. The large-diameter inlet end of the inlet section communicates with the interior of the fan housing, while the small-diameter inlet end is located inside the heat dissipation shell. The large-diameter outlet end of the outlet section communicates with the outside, while the small-diameter outlet end is also located inside the heat dissipation shell. The small-diameter inlet and outlet ends of the inlet and outlet sections have equal diameters and are connected by a throat. The throat is cylindrical, with a diameter of D1 (5mm < D1 < 20mm) and a length of L (0 < L < 15mm).

[0011] Thus, the cooling chamber is composed of an inlet section, a throat section, and an outlet section, forming a Laval tubular structure. The cooling air blown into the Laval tubular structure by the cooling fan accelerates the gas and dissipates heat.

[0012] Preferably, the fan housing has ventilation holes at the end away from the heat sink housing.

[0013] Preferably, the ventilation hole is provided with a filter screen.

[0014] Preferably, the outer wall of the heat dissipation housing is also provided with a lifting ring.

[0015] Preferably, when the throat diameter D1 remains constant, the temperature inside the cooling chamber first decreases and then increases with the increase of the throat length L. There exists a unique optimal throat length that maximizes heat dissipation, and the throat length L and throat diameter D1 satisfy the following proportional relationship under the condition of optimal heat dissipation:

[0016] .

[0017] Preferably, based on the Laval tubular structure of the cooling cavity, when the throat diameter D1 is constant and the throat length L ranges from 0 to L < 15 mm, the expression for the change in temperature t1 within the cooling cavity under different throat lengths L is as follows:

[0018] t1=-0.0035L 3 +0.078L 2-0.61L +53.1

[0019] The ratio of throat length L to throat diameter D1 under optimal heat dissipation conditions When the throat diameter D1 varies within the range of 5mm < D1 < 20mm, the expression for the change in temperature t2 within the cooling chamber is:

[0020] t2=-0.015 +0.41D1+48.5.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention utilizes a Laval tubular cooling cavity, consisting of an inlet section, a throat, and an outlet section, within the heat dissipation casing. A cooling fan forces external cooling air into this cavity. Based on the aerodynamic acceleration principle of the Laval tube, the airflow velocity increases dramatically as it passes through the throat, creating a high-speed airflow at the cavity outlet. This significantly enhances the convective heat transfer efficiency for the motor mounting bracket and internal stator and rotor components. Compared to traditional straight-through air ducts or finned structures, this invention achieves significantly increased cooling airflow acceleration and temperature reduction within a limited space, effectively solving the problem of localized overheating during high-power-density motor operation and ensuring the winding insulation life and permanent magnet stability.

[0023] Furthermore, by reasonably limiting the size range of the throat diameter D1 and throat length L of the cooling cavity, this invention ensures the feasibility of cavity processing and airflow passage while avoiding the technical contradictions of increased wind resistance and reduced airflow due to an excessively small throat, and insignificant airflow acceleration effect due to an excessively large throat. This allows the cooling cavity to maintain good accelerated heat dissipation performance under different fan head conditions, and has strong adaptability to operating conditions and design redundancy.

[0024] Based on this, the cooling fan in this invention is directly driven by the motor shaft, eliminating the need for an additional independent power source. This results in a compact structure and low energy consumption. Meanwhile, ventilation holes and filters are provided at the end of the fan housing, ensuring smooth airflow and effectively preventing external debris from entering the housing, thus extending the motor's service life. The lifting rings on the outer wall of the heat dissipation housing facilitate the installation, handling, and maintenance of the entire machine, comprehensively improving the product's engineering applicability and maintainability. Attached Figure Description

[0025] 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.

[0026] Figure 1 This is a schematic diagram of the overall structure of the motor in this invention;

[0027] Figure 2 This is a schematic diagram of the internal structure of the motor in this invention;

[0028] Figure 3 This is a front view structural diagram of the three-dimensional model of the cooling cavity in this invention;

[0029] Figure 4 This is a curve showing the temperature variation of the cooling cavity with the throat length L when the throat diameter D1 remains constant in this invention.

[0030] Figure 5 In this invention, when using The curve showing the temperature variation of the cooling cavity with the throat diameter D1 under the condition of a certain length-to-diameter ratio.

[0031] In the diagram: Fan housing 1, ventilation hole 101; heat dissipation housing 2, motor mounting bracket 201, motor stator 202, motor shaft 203, motor rotor 204; cooling cavity 3, inlet section 301, throat 302, outlet section 303, inlet large diameter end 304, inlet small diameter end 305, outlet large diameter end 306, outlet small diameter end 307. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention 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, and therefore should not be construed as a limitation of the invention. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] "Laval tube" does not refer to a specific pipe fitting with a fixed specification or shape, but can be understood as a general term for a type of flow channel structure with typical geometric characteristics: that is, the flow channel has a variable cross-section configuration of "first contraction - forming a throat - then expansion" along the direction of medium flow. This structure can be made into an independent pipe fitting, or integrated into air ducts, radiator channels, or inside the shell.

[0035] The core mechanism of the Laval tube lies in the following: as the airflow passes through the contraction section, the cross-sectional area decreases, and the velocity increases under the drive of the fan; a velocity peak is formed at the throat; after entering the expansion section, the pressure and velocity are redistributed through a reasonable expansion angle and length design, thereby generating supersonic airflow. In most cases, the supersonic airflow generated by the Laval tube is used to dissipate heat from a specific area or object, achieving higher local velocities and stronger shear disturbances in the target heat exchange area. More intuitively, this structure can improve the convective heat transfer coefficient, enhance heat transfer on the surface of the heat sink, reduce the peak temperature near the heat source, and improve the efficiency of air cooling through "flow organization optimization" within a limited space.

[0036] Therefore, given the difficulty in balancing structural compactness and heat dissipation efficiency in existing motors, this application introduces a Laval tube structure that "contracts first and then expands" to accelerate airflow. This enhances convective heat transfer by increasing the local air velocity within a limited space. Furthermore, through simulation studies, this application emphasizes determining key structural dimensions of the heat sink for specific motor conditions, such as the diameter and length of the inlet section and throat of the Laval tube structure, in order to achieve a more precise and reasonable balance between temperature control and structural compactness.

[0037] The technical solution of this application will be described in detail below with reference to the accompanying drawings.

[0038] In this technical solution, a motor based on Laval tube heat dissipation includes a housing, which is divided into a fan housing 1 and a heat dissipation housing 2, and the ends of the fan housing 1 and the heat dissipation housing 2 are connected as an integral structure.

[0039] like Figures 1 to 2 As shown, a cooling fan is installed inside the fan housing 1; a motor mounting bracket 201 is installed inside the heat dissipation housing 2. The motor mounting bracket 201 is a cylindrical structure. A motor stator 202 is installed on the inner circumference of the motor mounting bracket 201. A motor shaft 203 is installed inside the motor mounting bracket 201, and both ends of the motor shaft 203 are rotatably connected to the two ends of the motor mounting bracket 201. A motor rotor 204 is fitted on the outer circumference of the motor shaft 203. The end of the motor shaft 203 is connected to the cooling fan; a ventilation hole 101 is provided at the end of the fan housing 1 away from the heat dissipation housing 2. A filter screen is provided on the ventilation hole 101. A lifting ring is also provided on the outer wall of the heat dissipation housing 2. The cooling fan, filter screen and lifting ring are not shown in the figure.

[0040] The above embodiments provide the basic structural components of this invention. In this structure, the cooling fan is directly coaxially driven by the motor shaft 203, eliminating the need for an additional independent power source. This makes the overall structure more compact and reduces manufacturing costs and energy consumption. Simultaneously, the ventilation holes 101 and filter at the end of the fan housing 1 ensure smooth entry of external cooling air while effectively preventing dust and debris from entering the housing and causing contamination or damage to the stator and rotor, thus improving the motor's protection level and long-term operational reliability. The lifting ring facilitates the installation, hoisting, and maintenance of the entire machine, enhancing the product's engineering applicability. Based on the above structure, the following will focus on a detailed description of the specific construction of the cooling cavity 3 opened on the heat dissipation housing 2 and its heat dissipation working principle.

[0041] As the core of this application, such as Figures 1 to 2 As shown, the heat dissipation shell 2 has several cooling chambers 3 on its main body. The structures of the cooling chambers 3 are all the same, such as... Figure 3 As shown, each cooling cavity 3 is configured to consist of an inlet section 301, a throat 302, and an outlet section 303. The central axis of each cooling cavity 3 is parallel to the motor shaft 203. In each cooling cavity 3, the inlet section 301 and the outlet section 303 are both conical. The large diameter end 304 of the inlet section 301 is connected to the interior of the fan housing 1, and the small diameter end 305 of the inlet section 301 is located inside the heat dissipation housing 2. The large diameter end 306 of the outlet section 303 is connected to the outside, and the small diameter end 307 of the outlet section 303 is also located inside the heat dissipation housing 2. The diameters of the small diameter end 305 of the inlet section 301 and the small diameter end 307 of the outlet section 303 are equal and are connected through the throat 302, which is cylindrical.

[0042] Based on the above structure, the cooling cavity 3 is composed of an inlet section 301, a throat 302 and an outlet section 303 forming a Laval tubular structure. The cooling air blown into the cooling cavity 3 by the cooling fan is accelerated. On this basis, the motor structure inside the heat dissipation shell 2, in which the motor stator 202 and the motor rotor 204 cooperate with each other, is the heat source.

[0043] Next, based on the specific structure of the Laval tube, this application will use simulation to investigate the influence of the specific structural parameters of the Laval tube on the airflow velocity and temperature inside the cooling cavity 3, so as to achieve cooling of the internal space of the cooling cavity 3. Specifically, since the specific cooling effect of the Laval tube depends on its placement inside the motor and its structural cooperation with the cooling cavity 3, this application will take a conventional small motor as an example for investigation. For ease of description, the cooling cavity 3 with a Laval tube structure will be uniformly referred to as the Laval tube from now on.

[0044] In a conventional small motor, the diameter of the throat tube 302 is D1, where 5mm < D1 < 20mm, and the length of the throat tube 302 is L, where 0 < L < 15mm. The diameter of the inlet large diameter end 304 is D2, and the diameter of the outlet large diameter end 306 is determined according to the structural characteristics of a conventional Laval tube, and is taken to be larger than the diameter of the inlet large diameter end 304.

[0045] Since the flow of cooling air in the Laval tube is essentially the flow of fluid in a fluid domain, i.e., the cooling air is the fluid and the internal volume of the Laval tube is the fluid domain, Fluent software is used to perform precise simulation and analysis on complex fluid problems such as hypersonic flow fields and heat transfer, thereby obtaining the influence of the specific structural parameters of the Laval tube explored in this application on the air velocity and temperature inside the cooling cavity 3.

[0046] It should be noted beforehand that the relationship between flow rate and temperature in the conventional fluid domain in the prior art is as follows:

[0047] (Formula 1)

[0048] In the formula: Q is the flow rate of the cooling air; m is the mass of the cooling air inside the Laval tube; V is the internal volume of the Laval tube; ΔT is the absolute value of the difference between the highest temperature T and the lowest temperature T0 inside the Laval tube, ΔT = T - T0; P is the pressure of the cooling air in the throat 302 of the Laval tube; A is the cross-sectional area of ​​the throat 302 of the Laval tube.

[0049] The existing formula for the relationship between flow rate and velocity of fluid in the fluid domain is:

[0050] (Formula 2)

[0051] In the formula: Q is the flow rate of the cooling air; A is the cross-sectional area of ​​the throat 302 in the Laval tube; v is the flow velocity of the cooling air when it exits the Laval tube.

[0052] Combining Equations 1 and 2 above, we can obtain the flow velocity of the cooling air output through the Laval duct:

[0053] (Formula 3)

[0054] From Formula 3, we can conclude that under normal circumstances, when the pressure of the cooling air in the throat 302 of the Laval tube and the cross-sectional area of ​​the throat 302 of the Laval tube remain unchanged, the greater the flow velocity v of the cooling air when it exits the Laval tube, the greater the difference between the highest temperature T and the lowest temperature T0 inside the Laval tube. That is, the better the cooling effect inside the Laval tube. Therefore, in conventional fluid dynamics heat dissipation analysis, the magnitude of the cooling air flow velocity has a crucial impact on heat dissipation. The greater the flow velocity, the more significant the heat dissipation effect.

[0055] However, during the gas acceleration process in the Laval tube, the cooling air will rub against the tube wall, which will generate heat. Thus, in the case of the Laval tube, the cooling air will carry away the heat inside the Laval tube when it is accelerated. However, as the cooling air velocity increases, the friction between the cooling air and the inner wall of the Laval tube intensifies, which also generates heat. Ultimately, this results in a dynamic process of heat generation and cooling inside the Laval tube.

[0056] During this dynamic process, when the cooling air is initially accelerated, it begins to carry away some of the heat inside the Laval tube. Although the cooling air also generates heat through friction with the tube wall at this time, the heat generation efficiency is significantly lower than the heat dissipation of the cooling air flow. As a result, the actual temperature inside the Laval tube decreases, meaning the temperature change is relatively large. As the cooling air velocity increases, the friction between the air and the Laval tube intensifies, the heat generation increases, and the heat generation efficiency rises and approaches the heat dissipation of the cooling air flow. At this point, the actual temperature inside the Laval tube tends to remain constant, meaning the temperature change is relatively small.

[0057] Therefore, the pipe resistance R in the existing technology is introduced. a The concept of pipeline resistance R is discussed. a The magnitude of ΔT is inversely proportional to the flow velocity v when the cooling air is output from the Laval pipe, and according to Formula 3, ΔT is directly proportional to v. Therefore:

[0058] (Formula 4)

[0059] In the formula: The friction coefficient represents the resistance of the pipeline.

[0060] Based on existing technology, pipeline resistance The general formula:

[0061] (Formula 5)

[0062] In the formula: D1 is the friction coefficient of the pipeline resistance; D2 is the diameter of the large-diameter end of the Laval pipe inlet (304). ρ ρ is the air density; v is the flow velocity of the cooling air output from the Laval pipe.

[0063] Combining equations 4 and 5 and simplifying, we get:

[0064] (Formula 6)

[0065] At this point, the conclusion of Formula 6 shows that the difference between the highest temperature T inside the Laval tube and the lowest temperature T0 inside the Laval tube is inversely proportional to the flow velocity of the cooling air when it exits the Laval tube, that is, ΔT is inversely proportional to v. This indicates that the greater the flow velocity v of the cooling air when it exits the Laval tube, the smaller ΔT is, that is, the smaller the difference between the highest temperature T inside the Laval tube and the lowest temperature T0 inside the Laval tube. This shows that the Laval tube only increases the flow velocity of the cooling air, and does not reduce the temperature of the Laval tube in the process.

[0066] Therefore, there must exist an optimal cooling airflow velocity v to minimize the temperature inside the cooling cavity 3. Since the cooling airflow velocity v output from the Laval tube is related to the specific structure of the Laval tube itself, the simulation part of this application mainly explores the relationship between the throat diameter D1, the throat length L and the internal temperature t of the cooling cavity 3.

[0067] S1. Establishing a Model

[0068] The Laval tube in this application is simulated using a three-dimensional model. The three-dimensional model is established as follows: Figure 3 As shown, the design parameters in this model are as follows:

[0069] <![CDATA[Length L1 of cooling cavity 3]]> 80 <![CDATA[large-diameter inlet end 304 with diameter D2]]> 50 <![CDATA[The diameter D1 of the throat 302]]> 5~20 302 larynx length L 0~15 <![CDATA[Diameter D3 of the large outlet end 306]]> 55

[0070] S2, Mesh Generation

[0071] This application employs a partitioned hybrid meshing strategy to ensure computational accuracy while maintaining solution efficiency. Specifically, tetrahedral meshes are used for the Laval tube region to accommodate complex geometries; hexahedral meshes are used for regular regions inside the cooling cavity 3 to improve computational efficiency. This meshing method requires ensuring complete shared nodes to achieve seamless transfer of elements at the fluid-solid interface. Furthermore, local mesh refinement is applied to the periphery of the cooling cavity 3 near the motor mounting bracket 201, with the minimum mesh size controlled to ≤1mm to ensure accurate simulation of temperature distribution and heat flux density in hotspot areas. Based on this, this application sets boundary layer meshes near the fluid domain, such as the boundary of the cooling cavity 3, with 3 to 5 layers and a growth rate of 1.2.

[0072] S3. Perform Fluent heat dissipation simulation.

[0073] To simplify the 3D model, remove non-critical features such as screws and chamfers that have minimal impact on fluid flow. Import the 3D model into Fluent Meshing, enable the energy equation, and select the k-epsilon turbulence model based on the flow state.

[0074] Under the premise that the cooling air pressure provided by the cooling fan is 150 Pa and the ambient pressure is 0 Pa, this simulation process is carried out in two steps using the controlled variable method:

[0075] Experiment 1: With the throat diameter D1 fixed, only the throat length L was changed to investigate the effect of the throat length L on the temperature inside the cooling cavity 3. After obtaining the definition and value range of the specific variables according to S1, the simulation experiment was used to obtain the cooling airflow velocity and the temperature inside the cooling cavity 3 under the above conditions, as shown in Table 1 below.

[0076] Table 1. Relationship between throat length L, cooling airflow velocity, and temperature inside the cooling chamber when throat diameter D1 is 20 mm.

[0077] <![CDATA[Cooling air flow velocity v / m·s -1 > 1.365 1.374 1.41 1.43 1.52 1.579 1.817 1.761 1.63 1.635 1.641 Temperature t / ℃ inside the cooling chamber 52.5 52.4 52.2 52.0 51.99 51.96 50.96 51.05 51.55 51.65 51.72

[0078] The simulation data of throat length L and temperature inside cooling cavity 3 in Table 1 were analyzed and the results are as follows: Figure 4 The curve shown is as follows: Figure 4 It can be seen that when the throat diameter D1 remains constant, the temperature inside the cooling cavity 3 first decreases and then increases with the increase of the throat length L. There exists a unique optimal throat length that achieves the best heat dissipation effect. By fitting the structural parameters under this optimal condition, the following proportional relationship is obtained between the optimal length of the throat 302 and the throat diameter D1:

[0079] (Formula 7)

[0080] Based on this proportional relationship, the optimal throat length L can be directly determined in subsequent simulations and designs with different throat diameters D1, without the need for repeated calculations.

[0081] Experiment 2: Using the proportional relationships obtained in Experiment 1 Simulations were performed on different throat diameters D1 to investigate the effect of throat diameter D1 on the temperature inside the cooling cavity 3. After obtaining the definition and value range of specific variables based on S1, simulation experiments were used to obtain the cooling airflow velocity and the temperature inside the cooling cavity 3 under the above conditions, as shown in Table 2 below.

[0082] Table 2 shows the relationship between throat diameter D1, cooling airflow velocity, and temperature inside the cooling chamber, based on Formula 7.

[0083] Length of the trachea (L / mm) 1.500 1.800 2.100 2.400 2.700 3.000 3.300 3.600 <![CDATA[Cooling air flow velocity v / m·s -1 > 2.175 1.954 1.694 1.511 1.700 1.814 1.75 1.702 Temperature t / ℃ inside the cooling chamber 52.55 51.58 50.19 51.65 51.3 51.11 51.2 51.24 <![CDATA[Throat pipe diameter D1 / mm]]> 13 14 15 16 17 18 19 20 Length of the trachea (L / mm) 3.900 4.200 4.500 4.800 5.100 5.400 5.700 6.000 <![CDATA[Cooling air flow velocity v / m·s -1 > 1.800 1.856 1.710 1.81 1.872 1.881 1.688 1.817 Temperature t / ℃ inside the cooling chamber 50.12 51.28 51.23 51.6 51.56 51.74 50.95 50.96

[0084] Based on the ratio of the optimal length of the larynx 302 to the diameter D1 of the larynx obtained in Experiment 1 Experiment 2 simulation was conducted, and the results were as follows: Figure 5 The graph shown indicates that, under the aforementioned aspect ratio, the temperature inside the cooling cavity 3 first decreases and then increases with the change of the throat diameter D1. There exists an optimal throat diameter D1 that results in the lowest temperature inside the cooling cavity 3 and the best heat dissipation effect.

[0085] Simulation data shows that the cooling airflow velocity is only an intermediate process parameter. Its variation corresponds to the temperature change trend within the cooling cavity 3, but a higher cooling airflow velocity does not necessarily mean better heat dissipation. When the cooling airflow velocity increases to a certain range, the frictional heat generation between the airflow and the component wall intensifies, and the heat dissipation effect no longer improves or even deteriorates. Therefore, this application uses the lowest temperature within the cooling cavity 3 as the sole optimization objective, and the cooling airflow velocity is only used to assist in characterizing the optimal operating condition, and is no longer used as a separate evaluation index.

[0086] Therefore, the multi-dimensional simulation results of the cooling airflow velocity v and the temperature t inside the cooling cavity 3, obtained using simulation methods, are expressed as follows:

[0087] ① Based on the above simulation process, when the throat diameter D1 is constant and the throat length L ranges from 0 to L < 15 mm, the temperature t1 variation curves inside the cooling cavity 3 under different throat lengths L are as follows: Figure 4 As shown, the fitting formula is expressed as:

[0088] t1=-0.0035L 3 +0.078L 2 -0.61L+53.1 (Formula 8)

[0089] ② Based on the above simulation process, when the optimal ratio between the length of the throat 302 and the diameter D1 of the throat is adopted... When the throat diameter D1 varies within the range of 5mm < D1 < 20mm, the temperature change curve t2 inside the cooling chamber 3 is as follows: Figure 5 As shown, the fitting formula is:

[0090] t2=-0.015 +0.41D1+48.5 (Formula 9)

[0091] Therefore, with the goal of achieving optimal heat dissipation, the relationship between throat length L, throat diameter D1, and heat dissipation effect was obtained by combining the control variable method with the optimal length-to-diameter ratio constraint of throat 302. The simulation results show that in the motor structure of this application, using a Laval tubular cooling cavity and according to... By determining the size of the throat tube 302, a significantly better heat dissipation effect than conventional structures can be obtained within the throat tube diameter D1 range of 5mm to 20mm, and there is a unique optimal throat tube diameter D1 that minimizes the internal temperature of the cooling chamber 3.

[0092] Meanwhile, to verify the universality of the above-mentioned optimal structural proportions and heat dissipation law, this application sets up a proportional scaling verification experiment: the proportional relationship between the throat diameter D1 and the throat length L. The throat diameter D1 and throat length L were scaled by four equal ratios of 0.5, 1, 1.5, and 2, while keeping the boundary conditions such as cooling fan pressure, ambient pressure, and cooling cavity 3 heat generation power consistent. Fluent heat dissipation simulation was then performed again, and the simulation data for each group are shown in Table 3 below.

[0093] Table 3 shows the temperature inside the cooling chamber after scaling the throat diameter D1 and throat length L proportionally.

[0094] 0.5 times 10 3 1.68 51.0 1x 20 6 1.82 50.9 1.5 times 30 9 1.79 51.1 2 times 40 12 1.75 51.3

[0095] The verification experimental data shows that, while maintaining the principles established in this application... Under the premise of keeping the optimal structural proportions unchanged, the Laval tube structure is enlarged or reduced by different multiples. The minimum temperature of the cooling cavity 3 is stable in the range of 50.9℃~51.3℃. The cooling airflow rate and heat dissipation effect are not significantly degraded. The extreme temperature value pattern is consistent with the optimal size selection method.

[0096] The above results fully demonstrate that the optimal proportions, size design methods, and heat dissipation enhancement laws of the Laval tube structure determined in this application do not change substantially with proportional scaling of the overall structure size. They can achieve stable and efficient heat dissipation effects in small motors of different volumes and power levels, and have good versatility and engineering applicability, which can meet the compact heat dissipation design requirements of multiple product models.

[0097] Based on this, according to the research on the relationship between the inlet large diameter end diameter D2 and the throat diameter D1 in "Design and Experiment of Laval Supersonic Atomizing Nozzle": D2=(3~5)D1, the parameter arrangement of the overall structure of the Laval tube can be obtained.

[0098] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A motor based on Laval tube heat dissipation, characterized in that, include: The housing is divided into a fan housing and a heat dissipation housing, and the ends of the fan housing and the heat dissipation housing are connected as an integral structure. The fan housing is equipped with a cooling fan; The heat dissipation housing has a motor mounting bracket inside. The motor mounting bracket is a cylindrical structure. The motor stator is provided on the inner circumference of the motor mounting bracket. The motor shaft is provided inside the motor mounting bracket. The two ends of the motor shaft are rotatably connected to the two ends of the motor mounting bracket. The motor rotor is fitted on the outer circumference of the motor shaft. The end of the motor shaft is connected to the cooling fan. The heat dissipation shell has several cooling chambers on its main body. All cooling chambers have identical structures, and each chamber is configured to consist of an inlet section, a throat, and an outlet section. The central axis of each cooling chamber is parallel to the motor shaft. In each cooling chamber, the inlet and outlet sections are conical. The large-diameter inlet end of the inlet section communicates with the interior of the fan housing, while the small-diameter inlet end is located inside the heat dissipation shell. The large-diameter outlet end of the outlet section communicates with the outside, while the small-diameter outlet end is also located inside the heat dissipation shell. The small-diameter inlet and outlet ends of the inlet and outlet sections have equal diameters and are connected by a throat. The throat is cylindrical, with a diameter of D1 (5mm < D1 < 20mm) and a length of L (0 < L < 15mm). Thus, the cooling chamber is composed of an inlet section, a throat section, and an outlet section, forming a Laval tubular structure. The cooling air blown into the cooling chamber by the cooling fan is accelerated and dissipated.

2. The motor based on Laval tube heat dissipation according to claim 1, characterized in that: The fan housing has ventilation holes at the end away from the heat sink housing.

3. The motor based on Laval tube heat dissipation according to claim 2, characterized in that: The ventilation holes are equipped with filters.

4. The motor based on Laval tube heat dissipation according to claim 3, characterized in that: The outer wall of the heat dissipation shell is also equipped with a lifting ring.

5. A motor based on Laval tube heat dissipation according to claim 4, characterized in that: When the throat diameter D1 remains constant, the temperature inside the cooling chamber first decreases and then increases with the increase of the throat length L. There exists a unique optimal throat length that maximizes heat dissipation. The following proportional relationship is obtained between the throat length L and the throat diameter D1 under the optimal heat dissipation condition: 。 6. A motor based on Laval tube heat dissipation according to claim 5, characterized in that: Based on the Laval tubular structure of the cooling cavity, when the throat diameter D1 is constant and the throat length L ranges from 0 to L < 15 mm, the expression for the change in temperature t1 within the cooling cavity under different throat lengths L is as follows: t1=-0.0035L 3 +0.078L 2 -0.61L+53.1 The ratio of throat length L to throat diameter D1 under optimal heat dissipation conditions When the throat diameter D1 varies within the range of 5mm < D1 < 20mm, the expression for the change in temperature t2 within the cooling chamber is: t2=-0.015 +0.41D1+48.5。

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