Air duct structure, motor and air duct structure design method

Abstract

The invention relates to an air duct structure, a motor and an air duct structure design method, the air duct structure comprises a fan-ring-shaped groove plate, and an air duct is arranged on the groove plate; the air duct comprises an air inlet section, an expansion cavity and an air outlet section which are sequentially communicated; the air inlet section and the air outlet section are arranged in a staggered mode in the circumferential direction of the groove plate. One end of the air inlet section extends into the expansion cavity, and a first inner insertion section is defined between the air inlet section and the expansion cavity; one end of the air outlet section extends into the expansion cavity, and a second inner insertion section is defined between the air outlet section and the expansion cavity. According to the scheme, part of sound waves entering the expansion cavity are reflected to the echo source or reflected and interfered back and forth in the silencer, so that the sound waves are attenuated, the sound wave capacity is reduced, and the sound waves are prevented from being propagated to the downstream. And the first inner insertion section and the second inner insertion section can guide the air flow and can also increase the internal area of the expansion cavity, so that the reflection times and scattering times of sound waves in the cavity can be increased, and the sound wave attenuation effect is better. Therefore, the noise generated when the generator works can be reduced.

Description

Technical Field

[0001] The present application relates to the technical field of motors, and particularly to an air duct structure, a motor, and a design method for an air duct structure. Background Art

[0002] A motor refers to an electromagnetic device that realizes the conversion between electrical energy and mechanical energy based on the law of electromagnetic induction. A generator is a type of motor that can convert other forms of energy into electrical energy. The generator mainly includes a housing, a stator assembly fixed inside the housing, and a rotor assembly rotatably arranged inside the housing. The rotor assembly includes a main shaft, a stator core sleeved on the main shaft, and a rotor winding wound around the rotor stator core. The stator assembly includes a stator core and a wire bar wound around the tooth parts of the stator core laminations. The stator core includes a plurality of silicon steel sheets stacked together.

[0003] Since mechanical losses and resistance heat exist when the generator is working, a large amount of heat will be generated when the generator is working. In order to ensure the working performance of the generator and improve the working temperature of the generator, heat dissipation of the generator is required. In the related art, in order to improve the working temperature of the stator assembly, an air duct is provided on the stator assembly. The fan drives the air flow, so that the air in the air duct flows, so as to take away the heat of the stator assembly and realize the cooling of the stator assembly.

[0004] When the air flow passes through the surface of the structure, air flow disturbance will be generated, and thus noise will be generated. Noise pollution belongs to sensory public nuisance. Working in a strong noise environment above 90 dB(A) for a long time will cause deafness, neurasthenia, and cardiovascular diseases. Moreover, the near-field noise of a large AC excitation generator can reach 105 dB(A) - 120 dB(A). Therefore, it is necessary to reduce the noise generated when the generator is working and improve the working environment of the power station to protect the physical and mental health of relevant staff. Summary of the Invention

[0005] An embodiment of the present application provides an air duct structure, which can reduce the noise generated when the generator is working, so as to solve at least the above technical problems.

[0006] To achieve the above object, according to the first aspect of the present application, an air duct structure is provided. The air duct structure includes a fan-shaped groove plate. The two ends of the groove plate are respectively an inner diameter end and an outer diameter end. A plurality of air ducts are arranged on one side surface of the groove plate at intervals along the circumferential direction of the groove plate. In the direction from the inner diameter end to the outer diameter end, the air duct includes an air inlet section, an expansion chamber, and an air outlet section that are sequentially communicated. Along the circumferential direction of the groove plate, the air inlet section and the air outlet section are arranged in a staggered manner. Among them, one end of the air inlet section extends into the expansion chamber and defines a first inserted section with the expansion chamber; one end of the air outlet section extends into the expansion chamber and defines a second inserted section with the expansion chamber.

[0007] Optionally, the air inlet section includes a necking section and an inner extension section. The two ends of the necking section are respectively communicated with the expansion cavity and the inner extension section. The cross-sectional dimension of the end of the necking section facing the expansion cavity is smaller than that of the end of the necking section facing away from the expansion cavity.

[0008] Optionally, inner flow guiding bars are arranged in the inner extension section, and the extending direction of the inner flow guiding bars is parallel to the extending direction of the inner extension section.

[0009] Optionally, communication ports are arranged between two adjacent air ducts. The two ends of each communication port are respectively communicated with the inner extension sections of the two adjacent air ducts.

[0010] Optionally, the air duct structure further includes a plurality of toothed plates. The plurality of toothed plates are connected to the inner diameter end. The plurality of toothed plates are arranged at intervals along the circumferential direction of the channel plate. Part of the inner extension sections of two adjacent air ducts extend to the same toothed plate.

[0011] Optionally, the air outlet section includes a flaring section and an outer extension section. The two ends of the flaring section are respectively communicated with the expansion cavity and the outer extension section. The cross-sectional dimension of the end of the flaring section facing the expansion cavity is smaller than that of the end of the flaring section facing away from the expansion cavity.

[0012] Optionally, outer flow guiding bars are arranged in the outer extension section, and the extending direction of the outer flow guiding bars is parallel to the extending direction of the outer extension section.

[0013] Optionally, a partition bar is defined between two adjacent air ducts, and the width dimensions of any two parts of the partition bar are the same.

[0014] According to a second aspect of the present application, there is provided an electric motor, which includes a stator core and the aforementioned air duct structure. There are a plurality of stator cores, and the plurality of stator cores are arranged in sequence along the axial direction of the electric motor; an air duct structure is arranged between two adjacent stator cores. The plate surface of the channel plate facing away from the air duct is connected to one stator core, and the plate surface of the channel plate provided with the air duct abuts against another stator core.

[0015] According to a third aspect of the present application, there is provided a design method for the air duct structure of an electric motor. The electric motor is the aforementioned electric motor, and the design method includes: Obtain the designed value c of the sound velocity in the expansion cavity and the designed value b of the width of the expansion cavity, and determine the maximum sound absorption frequency f of the Nth order of the expansion cavity based on the designed value c of the sound velocity, the designed value b of the width of the expansion cavity, and the set value l of the length of the expansion cavity Nmax and the failure frequency f cut ; According to the maximum sound absorption frequency f Nmax being equal to the frequency f1 of the fundamental frequency aerodynamic noise of the electric motor, and the maximum sound absorption frequency f Nmax being less than the failure frequency f cut , obtain a sequence of tentative values of the length l of the expansion cavity; Obtain the tentative values of the length l1 of the first interpolation section, the length l2 of the second interpolation section, and the cross-sectional expansion ratio m of the air duct, and determine the acoustic transmission loss L of the expansion chamber based on these three values and the tentative value of the length l of the expansion chamber. TL ; Acoustic transmission loss L TL When the acoustic transmission loss L is not less than the target value, determine the tentative value of the length l of the expansion chamber, the tentative value of the length l1 of the first interpolation section, and the tentative value of the length l2 of the second interpolation section as the target setting values; Acoustic transmission loss L TL When it is less than the target value, adjust at least one of the tentative value of the length l of the expansion chamber, the tentative value of the length l1 of the first interpolation section, and the tentative value of the length l2 of the second interpolation section until the acoustic transmission loss L TL is not less than the target value.

[0016] In the air duct structure of the embodiment of the present application, by providing an air inlet section, an expansion chamber, and an air outlet section that are connected in sequence, the cross-sectional area between the air inlet section and the expansion chamber and between the air outlet section and the expansion chamber changes suddenly, resulting in a mismatch of acoustic impedance, causing part of the sound waves entering the expansion chamber to be reflected back to the sound source or to reflect and interfere inside the muffler, so as to attenuate the sound waves, reduce the sound wave energy, and thus prevent the sound waves from propagating downstream. By providing the first interpolation section and the second interpolation section, while guiding the air flow, the internal area of the expansion chamber can be increased, so that the number of reflections and scattering times of the sound waves in the chamber can be increased, making the sound wave energy more dispersed and the sound wave attenuation effect better. In this way, the noise during the operation of the generator can be reduced.

[0017] Other features and advantages of the present application will be described in detail in the subsequent specific implementation section. Brief Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] In order to more comprehensively understand the present application and its beneficial effects, the following will be described in conjunction with the drawings, where the same reference numerals in the following description represent the same parts.

[0020] Figure 1 is a schematic structural diagram of the air duct structure provided in the exemplary embodiment of the present disclosure; Figure 2 is a side view of the air duct structure provided in the exemplary embodiment of the present disclosure; Figure 3It is a partial structural schematic diagram of the air duct structure provided in the exemplary embodiment of the present disclosure; Figure 4 It is a partial structural schematic diagram of the motor provided in the exemplary embodiment of the present disclosure; Figure 5 It is a partial side view of the motor provided in the exemplary embodiment of the present disclosure; Figure 6 It is a schematic flowchart of the design method provided in the exemplary embodiment of the present disclosure; Figure 7 The sound transmission loss analysis and comparison diagram provided in the exemplary embodiment of the present disclosure; Figure 8 The generator aerodynamic noise spectrum comparison diagram provided in the exemplary embodiment of the present disclosure.

[0021] Explanation of reference numerals: 100 - air duct structure; 10 - slot plate; 101 - inner diameter end; 102 - outer diameter end; 103 - partition strip; 104 - plate body; 10a - air duct; 11 - air inlet section; 111 - constriction part; 112 - inner extension part; 113 - inner guide strip; 12 - expansion cavity; 121 - first inner insertion section; 122 - second inner insertion section; 123 - sharp corner; 124 - inflection point; 13 - air outlet section; 131 - flared part; 132 - outer extension part; 133 - outer guide strip; 14 - communication port; 15 - tooth plate; 151 - wire threading groove; 200 - motor; 20 - stator core; 201 - silicon steel sheet group; 202 - winding slot; 21 - stator bar; 22 - slot wedge. Detailed implementation manners

[0022] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present application.

[0023] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a connection that allows mutual communication; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0024] The term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a product or method including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent in such a product or method. Without further limitation, the element defined by the statement "including one..." does not exclude the existence of additional identical elements in the product or method including the said element.

[0025] Before introducing a duct structure, a motor and a design method for its duct structure provided by the embodiments of the present application, the related technologies of the present application will be introduced first.

[0026] In the related technologies, the noise sources of a generator are composed of vibration noise sources and aerodynamic noise sources. Among them, the vibration noise includes electromagnetic noise generated by the air-gap alternating electromagnetic force and mechanical noise generated by the friction vibration of moving components. The aerodynamic noise is generated by the airflow disturbance flowing over the structure surface inside the generator. Its generation and propagation are both in the gas medium and have no necessary connection with the structure vibration. The magnitude of the aerodynamic noise is determined by the airflow Mach number, and the frequency spectrum of the aerodynamic noise is composed of broadband noise and discrete noise.

[0027] At the present stage, the main ways to suppress electromagnetic noise include setting skew slots, skew poles, reducing the slot opening size, using magnetic slot wedges, etc. The ways to suppress mechanical noise include improving the rotor dynamic balance, increasing the structural stiffness, avoiding the modal natural frequency, increasing the vibration damping, etc. The research on the above vibration reduction and noise reduction mechanisms and application technologies is relatively mature. Practice has proved that reasonable electromagnetic and structural optimization can control the near-field vibration noise of the generator not exceeding 90 dB(A), meeting the requirements of noise control.

[0028] However, since the rotor linear velocity of a large-scale AC excitation generator is as high as more than one hundred meters per second, the airflow Mach number is close to 0.4, resulting in the near-field aerodynamic noise of the generator being greater than 105 dB(A). Thus, the aerodynamic noise becomes an important component determining the noise level of this type of generator.

[0029] At the present stage, the main ways to suppress the aerodynamic noise of a generator are as follows: (1) Reduce the sound source side sound generating components, including canceling the rotor fan, canceling the external ventilator, reducing the cooling air duct, etc. Such measures reduce the ventilation and heat dissipation performance of the generator, resulting in an increase in the generator temperature rise; (2) Optimize the air flow pattern in the sound source area, including developing low-noise fans, improving the rotor air duct structure, etc., to achieve noise reduction by weakening the unsteady air flow disturbance in the sound source area; However, on the premise that the electromagnetic power of the generator is high and the radial size of the generator remains unchanged, the change in the air flow Mach number before and after the implementation of such measures is small, and the reduction of the aerodynamic noise is small, usually not exceeding 3 dB(A); (3) Increase the acoustic impedance on the propagation side. For example, use a sound insulation chamber to wrap the generator as a whole, install sound absorption materials and perforated plates on the surface of the generator room, etc.; By increasing the acoustic radiation impedance outside the generator, a better noise reduction effect can be achieved, which is a common noise reduction measure for large generators, but this will increase the equipment manufacturing and maintenance costs and have an adverse impact on the heat dissipation of the generator.

[0030] Based on the above situation, for the aerodynamic noise problem of the generator, especially the aerodynamic noise problem of large AC excitation generators, an air duct structure, a motor and a design method of its air duct structure provided by the embodiments of the present application are provided. The air duct structure provided by the embodiments of the present application can significantly suppress the fundamental frequency aerodynamic noise in the medium and low frequency band (<3000 Hz) (that is, the specific frequency aerodynamic noise generated when the motor rotates at high speed, which can also be called discrete noise, has a large weight and is the main component of the motor aerodynamic noise). The air duct structure provided by the embodiments of the present application can not only reduce the noise of the generator, but also take into account the ventilation and heat dissipation performance of the generator, and can reduce the manufacturing cost of the generator.

[0031] The following will be combined with Figures 1 to 8 to explain in detail an air duct structure, a motor and a design method of its air duct structure provided by the embodiments of the present application respectively.

[0032] Please refer to Figure 1 and Figure 2 Figure 1 is a schematic structural diagram of the air duct structure 100 provided in the exemplary embodiment of the present disclosure, Figure 2It is a side view of the air duct structure 100 provided in an exemplary embodiment of the present disclosure. In the first aspect, an embodiment of the present application provides an air duct structure 100. The air duct structure 100 includes a fan-shaped slot plate 10. The two ends of the slot plate 10 are an inner diameter end 101 and an outer diameter end 102, respectively. A plurality of air ducts 10a are arranged on a side plate surface of the slot plate 10. The plurality of air ducts 10a are arranged at intervals along the circumference of the slot plate 10. From the inner diameter end 101 to the outer diameter end 102, the air duct 10a includes an air inlet section 11, an expansion chamber 12 and an air outlet section 13 that are connected in sequence. Along the circumference of the slot plate 10, the air inlet section 11 and the air outlet section 13 are staggered. Among them, one end of the air inlet section 11 extends into the expansion chamber 12, and defines a first interpolated section 121 between the air inlet section 11 and the expansion chamber 12. One end of the air outlet section 13 extends into the expansion chamber 12, and defines a second interpolated section 122 between the air outlet section 13 and the expansion chamber 12.

[0033] It can be understood that the slot plate 10 is applied to the motor 200. Specifically, the slot plate 10 is arranged around the rotating shaft of the motor 200. The inner diameter end 101 is the end of the slot plate 10 facing the rotating shaft, and the outer diameter end 102 is the end of the slot plate 10 away from the rotating shaft. Specifically, the plate surface of the slot plate 10 away from the air duct 10a is connected to a stator core 20 of the motor 200, and the plate surface of the slot plate 10 provided with the air duct 10a is abutted against another stator core 20 of the motor 200 to close the opening of the air duct 10a extending along the length direction thereof, so that the airflow flowing into the air duct 10a from the inner peripheral side of the stator core 20 flows along the air duct 10a to the outer periphery of the stator core 20.

[0034] It can be understood that one end of the first inserted section 121 is integrally connected to the surface of the slot plate 10 defining the air inlet section 11 , and the other end of the first inserted section 121 is inserted into the expansion chamber 12 and extends radially along the slot plate 10 .

[0035] It can be understood that one end of the second inserted section 122 is integrally connected to the surface of the slot plate 10 defining the air outlet section 13 , and the other end of the second inserted section 122 is inserted into the expansion chamber 12 and extends radially along the slot plate 10 .

[0036] It can be understood that the length of the expansion cavity 12 is l, the length of the first insert section 121 is l1, and the length of the second insert section 122 is l2. Figure 3 As shown, Figure 3It is a partial structural schematic diagram of the air duct structure 100 provided in an exemplary embodiment of the present disclosure. Among them, the length dimension l of the expansion chamber 12 is greater than the sum of the length dimension l1 of the first interpolation section 121 and the length dimension l2 of the second interpolation section 122, so as to ensure that the air flow entering the expansion chamber 12 from the air inlet section 11 can smoothly flow out from the air outlet section 13. The length dimension l can be the longest dimension of the expansion chamber 12, or the dimension between the inflection point 124 on the outer peripheral side and the inflection point 124 on the inner peripheral side of the expansion chamber 12, or Figure 3 such as shown, the dimension between the intermediate positions between the sharp corner 123 and the inflection point 124 of the expansion chamber 12.

[0037] It can be understood that the cross-section perpendicular to the air flow direction of the air duct 10a is the cross-section of the air duct 10a. Among them, the cross-sectional area S1 of the part of the air inlet section 11 close to the expansion chamber 12 is smaller than the cross-sectional area S2 of the expansion chamber 12, and the cross-sectional area S3 of the part of the air outlet section 13 close to the expansion chamber 12 is smaller than the cross-sectional area S2 of the expansion chamber 12. Specifically, S1 = S3.

[0038] Exemplarily, the groove plate 10 is made of steel plate.

[0039] In this embodiment, by providing the air inlet section 11, the expansion chamber 12 and the air outlet section 13 that are sequentially connected, the cross-sectional area mutation occurs between the air inlet section 11 and the expansion chamber 12 and between the air outlet section 13 and the expansion chamber 12, resulting in acoustic impedance mismatch, so that part of the sound waves entering the expansion chamber 12 are reflected back to the sound source or reflected and interfered back and forth inside the muffler to attenuate the sound waves, reduce the sound wave energy, and thus hinder the sound waves from propagating downstream (i.e., the air outlet section 13). By providing the first interpolation section 121 and the second interpolation section 122, while guiding the air flow, the internal area of the expansion chamber 12 can be increased, so that the number of reflections and scattering times of the sound waves in the cavity can be increased, the sound wave energy can be more dispersed, and the sound wave attenuation effect is better. In this way, the noise during the operation of the generator can be reduced, the working environment of the power station can be improved, and the physical and mental health of relevant staff can be protected.

[0040] Moreover, compared with the noise reduction measures in the related art, such as reducing the sound-generating components on the sound source side, optimizing the air flow pattern in the sound source area, and configuring sound-absorbing materials, the air duct structure 100 provided in this embodiment has a simple structure, good noise reduction effect, and low noise reduction cost on the basis of ensuring the heat dissipation of the motor 200, and can avoid the additional equipment manufacturing and maintenance costs brought by arranging sound insulation rooms and installing sound-absorbing materials.

[0041] It can be understood that the size of the expansion chamber 12 is fixed, and correspondingly, the impedance of the air duct structure 100 is fixed. Since the impedances of sound waves with different frequencies are different, it is necessary to set the corresponding size of the air duct 10a for different models of the motor 200 to achieve the noise reduction treatment of the sound waves of the target frequency.

[0042] Therefore, when reducing the noise of a large AC excitation generator, since the fundamental frequency aerodynamic noise is the most important discrete noise component of the large AC excitation generator, a corresponding air duct structure 100 can be set for the frequency of the fundamental frequency aerodynamic noise of the large AC excitation generator to reduce the fundamental frequency aerodynamic noise of the large AC excitation generator, thereby reducing the total noise of the large AC excitation generator.

[0043] In addition, each expansion cavity 12 is provided with an air inlet section 11 on both sides close to the inner diameter end 101. In order to avoid the setting of the air inlet section 11, so that the air inlet section 11 can smoothly guide the airflow into the expansion cavity 12, the width dimension of one end of each expansion cavity 12 close to the inner diameter end 101 gradually decreases as it approaches the inner diameter end 101, so that the part of the expansion cavity 12 close to the inner diameter end 101 is a sharp corner 123. In this way, on the basis of improving the smoothness of the airflow in the air inlet section 11, the expansion cavity 12 can also have more surfaces arranged at angles to each other, so as to increase the number of reflections and scatterings of sound waves in the cavity, so that the sound wave energy is more dispersed and the sound wave attenuation effect is better.

[0044] Correspondingly, each expansion cavity 12 is provided with an air outlet section 13 on both sides close to the outer diameter end 102. In order to avoid the setting of the air outlet section 13, so that the air outlet section 13 can smoothly guide the airflow, the width dimension of one end of each expansion cavity 12 close to the outlet end gradually decreases as it approaches the outlet end, so that the part of the expansion cavity 12 close to the outlet end is a sharp corner 123. In this way, on the basis of improving the smoothness of the airflow, the expansion cavity 12 can also have more surfaces arranged at angles to each other, so as to increase the number of reflections and scatterings of the sound wave in the cavity, so that the sound wave energy is more dispersed and the sound wave attenuation effect is better.

[0045] See also Figure 2 In some embodiments, the air inlet section 11 includes a constricted portion 111 and an inner extension portion 112. The two ends of the constricted portion 111 are respectively connected to the expansion chamber 12 and the inner extension portion 112. The cross-sectional dimension of one end of the constricted portion 111 facing the expansion chamber 12 is smaller than the cross-sectional dimension of one end of the constricted portion 111 away from the expansion chamber 12. In this way, the airflow of the inner extension portion 112 can be smoothly introduced into the expansion chamber 12 through the constricted portion 111, thereby reducing the flow resistance of the air duct 10a, which is conducive to reducing the airflow loss and ensuring the air volume flowing in the air duct 10a. In this way, the heat dissipation efficiency of the motor 200 can be improved.

[0046] Specifically, the inner extension portion 112 smoothly transitions to the expansion cavity 12 through the necking portion 111 .

[0047] See also Figure 2 In some embodiments, an inner guide bar 113 is provided in the inner extension portion 112 , and an extension direction of the inner guide bar 113 is parallel to an extension direction of the inner extension portion 112 .

[0048] Exemplarily, the inner flow guiding strip 113 is integrally formed with the groove plate 10.

[0049] In this embodiment, by arranging the inner flow guiding strip 113 in the inner extension part 112, a structure with a multi-way confluence effect can be formed between the inner extension part 112 and the necking part 111, which can reduce the flow resistance loss of the cooling air, so as to improve the effectiveness of the cooling air blowing on the side of the wire bar and the surface of the iron core, and realize the function of fully cooling the stator assembly.

[0050] In addition, by arranging the inner flow guiding strip 113 in the inner extension part 112, on the one hand, the contact area between the air duct structure 100 and the air flow can be increased, which is beneficial to improving the heat dissipation efficiency of the air duct structure 100; on the other hand, the air flow in the inner extension part 112 can be guided by the inner flow guiding strip 113, so that the air flow is more smooth, which is beneficial to reducing the air flow loss.

[0051] Please refer to Figure 2 , in some embodiments, a communication port 14 is arranged between two adjacent air ducts 10a, and both ends of the communication port 14 are respectively communicated with the inner extension parts 112 of the two adjacent air ducts 10a. In this way, the air flow in one air duct 10a can be introduced into the other air duct 10a through the communication port 14, so that the air flow flows along the circumferential direction of the groove plate 10. In this way, it is beneficial to optimize the air flow pattern, thereby reducing the flow resistance and improving the air flow efficiency.

[0052] Please refer to Figure 1 and Figure 2 , in some embodiments, the air duct structure 100 further includes a plurality of tooth plates 15. The plurality of tooth plates 15 are connected to the inner diameter end 101. The plurality of tooth plates 15 are arranged at intervals along the circumferential direction of the groove plate 10. Part of the inner extension parts 112 of two adjacent air ducts 10a extend to the same tooth plate 15.

[0053] It can be understood that a wire threading groove 151 is formed between two adjacent tooth plates 15, and the stator wire bar 21 of the generator is wound in the wire threading groove 151.

[0054] It can be understood that the tooth plate 15 is arranged opposite to the tooth part of the stator iron core 20, and the groove plate 10 is arranged opposite to the yoke part of the stator iron core 20.

[0055] Exemplarily, the tooth plate 15 is integrally arranged with the groove plate 10.

[0056] In this embodiment, by arranging the tooth plate 15, on the one hand, the contact area between the air duct structure 100 and the stator iron core 20 can be increased, so as to improve the heat dissipation efficiency of the air duct 10a assembly to the stator iron core 20; on the other hand, the air flow on the inner circumferential side of the stator assembly can be guided, so as to improve the smoothness of the air flow, which is beneficial to improving the heat dissipation efficiency of the motor 200.

[0057] Please refer to Figure 1 and Figure 2 In some embodiments, the air outlet section 13 includes a flaring portion 131 and an outer extension portion 132. Both ends of the flaring portion 131 are respectively communicated with the expansion cavity 12 and the outer extension portion 132. The cross-sectional dimension of the end of the flaring portion 131 facing the expansion cavity 12 is smaller than the cross-sectional dimension of the end of the flaring portion 131 facing away from the expansion cavity 12. In this way, the air flow can be introduced into the outer extension portion 132 relatively gently through the flaring portion 131, thereby reducing the flow resistance of the air duct 10a, facilitating the reduction of air flow loss, and ensuring the air volume flowing in the air duct 10a. In this way, the heat dissipation efficiency of the motor 200 can be improved.

[0058] Specifically, the outer extension portion 132 smoothly transitions to the expansion cavity 12 through the flaring portion 131.

[0059] In some embodiments, an outer guide strip 133 is provided in the outer extension portion 132, and the extending direction of the outer guide strip 133 is parallel to the extending direction of the outer extension portion 132.

[0060] Exemplarily, the outer guide strip 133 is integrally formed with the groove plate 10.

[0061] In this embodiment, by providing the outer guide strip 133 in the outer extension portion 132, on the one hand, the contact area between the air duct structure 100 and the air flow can be increased, which is conducive to improving the heat dissipation efficiency of the air duct structure 100; on the other hand, the air flow in the outer extension portion 132 can be guided by the outer guide strip 133, so that the air flow is more smooth, which is conducive to reducing the air flow loss.

[0062] Please refer to Figure 1 and Figure 2 In some embodiments, a partition strip 103 is defined between two adjacent air ducts 10a. In the extending direction of the partition strip 103, the width dimension of the partition strip 103 remains unchanged. In this way, the structure of the portion of the groove plate 10 located between the two air ducts 10a can be made uniform, thereby improving the stress condition of the groove plate 10 and avoiding stress concentration. In this way, it is beneficial to improve the strength of the air duct structure 100.

[0063] It can be understood that the width dimension of the partition strip 103 refers to the distance between the inner wall of the formed air duct 10a and the inner wall of the formed other air duct 10a of the partition strip 103.

[0064] Exemplarily, the width dimension of the partition strip 103 is 0.5 mm to 4 mm. The width of the partition strip 103 includes but is not limited to 0.5 mm, 1.5 mm, 2 mm, 3 mm, and 4 mm.

[0065] Exemplarily, the partition strip 103 can be a channel steel.

[0066] Exemplarily, the slot plate 10 includes a plate body 104 and a plurality of partition bars 103 disposed on the plate body 104. The plurality of partition bars 103 are circumferentially spaced apart and define an air duct 10a between two adjacent partition bars 103. The plate body 104 and the partition bars 103 may be integrally provided, or the partition bars 103 may be welded to the plate body 104. When the partition bar 103 is a channel steel, the part of the partition bar 103 opposite to the tooth part of the stator core 20 is the tooth part channel steel, and the part opposite to the yoke part of the stator core 20 is the yoke part channel steel.

[0067] Please refer to Figure 4 and Figure 5 , Figure 4 which is a partial structural schematic diagram of the motor 200 provided in an exemplary embodiment of the present disclosure. Figure 5 which is a partial side view of the motor provided in an exemplary embodiment of the present disclosure. In a second aspect, an embodiment of the present application further provides a motor 200. The motor 200 includes a stator core 20 and the aforementioned air duct structure 100. There are a plurality of stator cores 20. The plurality of stator cores 20 are sequentially arranged along the axial direction of the motor 200. An air duct structure 100 is provided between two adjacent stator cores 20. The plate surface of the slot plate 10 facing away from the air duct 10a is connected to a stator core 20. The plate surface of the slot plate 10 provided with the air duct 10a abuts against another stator core 20.

[0068] It can be understood that the motor 200 further includes a housing, a rotating shaft rotatably disposed in the housing, and a rotor assembly fixed to the rotating shaft.

[0069] It can be understood that the motor 200 further includes stator bars 21, and the stator bars 21 are wound around the stator core 20, i.e., the air duct structure 100, to form a stator assembly. There is an air gap between the stator assembly and the rotor assembly.

[0070] It can be understood that the stator core 20 includes a plurality of silicon steel sheet groups 201, the plurality of silicon steel sheet groups 201 are sequentially arranged along the circumference, and two adjacent silicon steel sheet groups 201 are in contact with each other. Each silicon steel sheet group 201 includes a plurality of silicon steel sheets stacked in sequence along the axial direction of the motor 200. Each stator core 20 has a plurality of air duct structures 100, and the plurality of air duct structures 100 are respectively arranged in one-to-one correspondence with the plurality of silicon steel sheet groups 201.

[0071] Specifically, winding grooves 202 are defined between the tooth parts of the stator core 20, and a slot wedge 22 is provided on one side of the winding groove 202 away from the yoke part of the stator core 20. The slot wedge 22 presses the bar tightly in the winding groove 202.

[0072] It can be understood that the motor 200 includes the aforementioned air duct structure 100, and the motor 200 has all the beneficial effects of the aforementioned air duct structure 100, which will not be elaborated herein by the present disclosure.

[0073] Please refer to Figure 6 , Figure 6 which is a schematic flow chart of the design method provided in an exemplary embodiment of the present disclosure. In a third aspect, an embodiment of the present application provides a design method for the air duct structure 100 of the motor 200, where the motor 200 is the aforementioned motor 200, and the design method includes: Obtain the designed sound speed value c in the expansion chamber 12 and the designed width value b of the expansion chamber 12, and determine the maximum sound absorption frequency f of the Nth order of the expansion chamber 12 based on the designed sound speed value c, the designed width value b of the expansion chamber, and the set value of the length l of the expansion chamber Nmax and the failure frequency f cut ; According to the maximum sound absorption frequency f Nmax being equal to the frequency f1 of the fundamental frequency aerodynamic noise of the motor, and the maximum sound absorption frequency f Nmax being less than the failure frequency f cut , obtain a sequence of tentative values of the length l of the expansion chamber 12; Obtain the tentative value of the length l1 of the first interpolation section 121, the tentative value of the length l2 of the second interpolation section 122, and the cross-sectional expansion ratio m of the air duct 10a, and determine the sound transmission loss L of the expansion chamber 12 based on these three values and the tentative value of the length l of the expansion chamber 12 TL ; When the sound transmission loss L TL is not less than the target value, determine the tentative value of the length l of the expansion chamber 12, the tentative value of the length l1 of the first interpolation section 121, and the tentative value of the length l2 of the second interpolation section 122 as the target set values; When the sound transmission loss L TL is less than the target value, adjust at least one of the tentative value of the length l of the expansion chamber 12, the tentative value of the length l1 of the first interpolation section 121, and the tentative value of the length l2 of the second interpolation section 122 until the sound transmission loss L TL is not less than the target value.

[0074] It can be understood that the tentative value of the length l of the expansion chamber 12 needs to satisfy f Nmax = f1, f Nmax <f cut . The tentative value of the length l1 of the first interpolation section 121, the tentative value of the length l2 of the second interpolation section 122, and the tentative value of the length l of the expansion chamber 12 need to satisfy L TL not less than the target value.

[0075] Specifically, the design method includes the following steps.

[0076] S100. Obtain the cross-sectional expansion ratio m of the air duct 10a; Specifically, a generator ventilation calculation program (e.g., Fluent, Flowmaster) is used to calculate the ventilation temperature rise of the generator. According to the cross-sectional area s1 of the air inlet section 11 near the expansion chamber 12 and the cross-sectional area s2 of the expansion chamber 12 in the air duct 10a of the stator core 20, the cross-sectional area expansion ratio m of the air duct 10a is: Formula (1); Among the above, the cross-sectional area of the air inlet section 11 near the expansion chamber 12 and the cross-sectional area of the air outlet section 13 near the expansion chamber 12 are both S1.

[0077] S200. Obtain the near-field noise spectrum of the motor 200, and determine the frequency f1 of the fundamental frequency aerodynamic noise of the motor 200 according to the near-field noise spectrum; Specifically, the time-domain analysis method of aerodynamic acoustics is used to calculate the aerodynamic noise of the generator, obtain the near-field noise spectrum of the generator, and determine the frequency f1 of the fundamental frequency aerodynamic noise of the generator as: Formula (2); Among them, z2 is the number of rotor slots of the large AC excitation generator; n is the operating speed.

[0078] It can be understood that the near-field noise spectrum refers to the noise spectrum measured in the area near the noise source. The near-field noise spectrum refers to the sound spectrum level of the noise source, which includes the sound frequency of the noise source and the sound pressure level corresponding to the sound frequency. By analyzing the near-field noise spectrum, the noise frequency and sound pressure level with the largest weight can be obtained, which are the two characteristics of the fundamental frequency aerodynamic noise. Among them, the noise frequency is the frequency of the fundamental frequency noise.

[0079] S300. Obtain the tentative value of the length l of the expansion chamber 12; Determine the maximum sound absorption frequency f of the Nth order of the expansion chamber 12 Nmax , among which, Formula (3); Among them, c is the designed sound speed value in the expansion chamber 12.

[0080] Determine the failure frequency f of the expansion chamber 12 cut , among which: Formula (4); Among them, b is the width of the expansion chamber 12.

[0081] Select N as 0 to 4, and according to f Nmax = f1, and f Nmax < f cut, a sequence of values of the length l of the expansion chamber 12 is obtained, and each value in the sequence is a tentative value of the length l of the expansion chamber 12.

[0082] S400. Obtain the tentative value of the length l1 of the first interpolation segment 121 and the tentative value of the length l2 of the second interpolation segment 122, where 0 < l1 + l2 < l; S500. Determine the acoustic transmission loss L of the expansion chamber 12 according to the tentative value of the length l of the expansion chamber 12, the tentative value of the length l1 of the first interpolation segment 121, the tentative value of the length l2 of the second interpolation segment 122, and the cross-sectional expansion ratio m of the air duct 10a TL ; Specifically, based on the frequency-domain analysis method of plane wave theory, the transfer matrix method is used to calculate the acoustic transmission loss of the expansion chamber 12 as: Formula (5); where k is the wave number; represents the incident wave sound pressure, that is, the pressure of the sound wave entering the expansion chamber 12; represents the transmitted wave sound pressure, which is the pressure of the sound wave that continues to propagate forward after passing through the expansion chamber 12.

[0083] S600. Determine whether L TL is not less than the target value. If so, determine the tentative value of the length l of the expansion chamber 12, the tentative value of the length l1 of the first interpolation segment 121, and the tentative value of the length l2 of the second interpolation segment 122 as the target setting values. If not, adjust at least one of the tentative value of the length l of the expansion chamber 12, the tentative value of the length l1 of the first interpolation segment 121, and the tentative value of the length l2 of the second interpolation segment 122 until, when satisfying f Nmax = f1, and f Nmax < f cut , L TL is not less than the target value.

[0084] Among them, the target value can be set according to the requirements of the application environment of the motor. For example, the target value can be 30 dB(A). Correspondingly, it is necessary to satisfy: L TL ≥ 30 dB(A).

[0085] It can be understood that the Nth-order passing frequency f Nmin of the expansion chamber 12 can be determined according to the modal order N, the designed value c of the sound speed, and the target setting value of the length l of the expansion chamber 12. Specifically, Formula (6).

[0086] It can be understood that the noise reduction ability of the expansion chamber 12 has an applicable frequency range. Among them, when f nmax is satisfied, the expansion chamber 12 has the maximum noise reduction ability, and the noise reduction ability is lost at f cut . Therefore, it is necessary that the fundamental frequency pneumatic noise f1 of the motor 200 is exactly equal to f Nmax , and at the same time f Nmax should not exceed f cut . In this way, the expansion chamber 12 has the best noise reduction effect on the noise with the frequency of f1 of the fundamental frequency pneumatic noise.

[0087] It can be understood that if f Nmax = f1, and f Nmax <f cut , when L TL is less than the target value, at least one of the set value of the length l of the expansion chamber 12, the tentative value of the length l1 of the first interpolation section 121, and the tentative value of the length l2 of the second interpolation section 122 is adjusted, and the next round of iterative calculation is performed until f Nmax = f1, and f Nmax <f cut , and L TL is not less than the target value.

[0088] Among them, since the one-dimensional acoustic impedance derived from the plane wave theory ignores the influence of higher-order acoustic modes and the calculation accuracy is limited, it is necessary to use the time-domain analysis method of aeroacoustics to calculate the aeroacoustic noise spectrum of the generator (such as, a large AC excitation generator) adopting the air duct structure 100 in detail, and compare it with the aeroacoustic noise spectrum of the original generator of the air duct structure 100 provided in the embodiment of the present application to judge whether the noise suppression effect meets the expectation. If it does not meet the expectation, at least one of the dimensions l, l1, and l2 of the expansion chamber 12 needs to be adjusted, and this calculation is iterated until L TL is not less than the target value. If it meets the expectation, the dimensions of the effective air duct structure 100 can be determined.

[0089] The embodiment of the present application is based on the noise reduction principle of the expansion chamber 12 and combines the frequency-domain and time-domain analysis methods, and can realize the function of accurately predicting and suppressing the fundamental frequency pneumatic noise of the generator (for example, large AC excitation).

[0090] As can be seen from the above, the embodiment of the present application has at least the following beneficial effects: First, through the expansion chamber 12, the first interpolation section 121, and the second interpolation section 122 in the embodiment of the present application, on the basis of expansion noise reduction, the air flow is guided, and the internal area of the expansion chamber 12 can be increased, so that the number of reflections and scattering points of the sound wave in the cavity can be increased, the sound wave energy is more dispersed, and the sound wave attenuation effect is better.

[0091] Second, on the basis of controlling the wind resistance of the air duct 10a, optimizing the dimensional parameters of the air duct structure 100 can significantly suppress the fundamental frequency aerodynamic noise of the generator. Compared with the noise reduction measures such as reducing the sound-generating components on the sound source side and optimizing the air flow pattern in the sound source area in the related art, the implementation of the embodiments of the present application is simple and has a good noise reduction effect.

[0092] Third, through CFD fluid characteristic analysis, optimizing the wind resistance coefficient of the air duct structure 100 can ensure that the overall wind resistance of the generator ventilation system will not increase significantly compared with the related art, thus not having a great negative impact on the cooling of the motor 200. In this way, reasonably designing the dimensional parameters of the air duct structure 100 can reduce the flow resistance loss of the air flowing through the air duct 10a, and can ensure the ventilation and heat dissipation conditions of the generator. Compared with the noise reduction measures such as canceling the rotor fan and reducing the cooling air duct 10a, the embodiments of the present application have little impact on the ventilation and heat dissipation performance of the generator.

[0093] Fourth, it is possible to avoid the additional equipment manufacturing and maintenance costs brought about by arranging the sound insulation chamber and installing the sound absorption material, and the embodiments of the present application have good economy.

[0094] The following further details the technical solutions provided by the embodiments of the present application in conjunction with specific embodiments and data. It should be understood that the following embodiments are only used to explain the present application and are not used to limit the present application.

[0095] Embodiment 1 Through simulation software (for example, COMSOL Multiphysics, Ansys series software), the sound transmission loss of the air duct 10a of the generator in the prior art and the sound transmission loss of the air duct structure 100 of the generator provided by the embodiments of the present application are analyzed, and the Figure 7 obtained sound transmission loss analysis and comparison diagram is as shown. Figure 7 Among them, the diagram (a) shows the sound transmission loss analysis diagram of the air duct 10a of the generator in the prior art, and the diagram (b) shows the sound transmission loss analysis diagram of the air duct structure 100 of the generator provided by the embodiments of the present application. The sound transmission loss analysis diagram reflects the reduction amount of the sound at the outlet of the air duct 10a relative to the inlet of the air duct 10a after the sound propagates through the respective air ducts 10a. Compared with the diagram (a), the diagram (b) has a larger reduction amount in a specific frequency band (mainly in the range of 400 Hz to 3000 Hz). It can be seen from this that the sound absorption ability of the air duct structure 100 provided by the embodiments of the present application is better.

[0096] Embodiment 2 Through simulation software (for example, COMSOL Multiphysics, Ansys series software), the aerodynamic noise spectrum of the generator in the prior art and the aerodynamic noise spectrum of the generator provided by the embodiments of the present application are analyzed, and the Figure 8 obtained generator aerodynamic noise spectrum comparison diagram is as shown.Figure 8 Among them, Figure (c) shows the aerodynamic noise spectrum of a generator in the prior art, and Figure (d) shows the aerodynamic noise spectrum of the generator provided by the embodiment of the present application. Specifically, Figures (c) and (d) are the noise spectra in the far field of the generator. The SPL (Sound Pressure Level) at the fundamental frequency of 2100 hz in Figure (d) is effectively suppressed, and the total noise (the total noise refers to the sum of the weighted values of the sound pressure levels of each frequency segment in the sound spectrum) is also smaller than that in Figure (c). It can be seen from this that the noise reduction ability of the air duct structure 100 provided by the embodiment of the present application is better.

[0097] In the description of the present application, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, the meaning of "a plurality" is two or more, unless otherwise specifically defined.

[0098] In the above embodiments, the descriptions of the respective embodiments have their own emphases. For the parts not detailed in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0099] The embodiments, implementation manners and related technical features of the present application can be combined and replaced with each other without conflict.

[0100] The above are only the preferred embodiments of the present application and do not impose any form of limitation on the present application. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application still fall within the scope of the technical solution of the present application.

Claims

1. An air duct structure, characterized in that, It comprises a fan-shaped slot plate (10), a plurality of air ducts (10a) are arranged on a side plate surface of the slot plate (10), and the plurality of air ducts (10a) are arranged at intervals along the circumference of the slot plate (10); The slot plate (10) comprises an inner diameter end (101) and an outer diameter end (102); in a direction from the inner diameter end (101) to the outer diameter end (102), the air duct (10a) comprises an air inlet section (11), an expansion chamber (12) and an air outlet section (13) which are connected in sequence; along the circumference of the slot plate (10), the air inlet section (11) and the air outlet section (13) are arranged in a staggered manner; One end of the air inlet section (11) extends into the expansion chamber (12) and defines a first inserted section (121) between the air inlet section (11) and the expansion chamber (12); one end of the air outlet section (13) extends into the expansion chamber (12) and defines a second inserted section (122) between the air inlet section (11) and the expansion chamber (12).

2. The air duct structure according to claim 1, characterized in that, The air inlet section (11) comprises a constricted portion (111) and an inner extension portion (112); two ends of the constricted portion (111) are respectively connected to the expansion chamber (12) and the inner extension portion (112); and a cross-sectional dimension of an end of the constricted portion (111) facing the expansion chamber (12) is smaller than a cross-sectional dimension of an end of the constricted portion (111) facing away from the expansion chamber (12).

3. The air duct structure according to claim 2, wherein, An inner guide strip (113) is provided in the inner extension portion (112), and an extension direction of the inner guide strip (113) is parallel to an extension direction of the inner extension portion (112).

4. The air duct structure according to claim 2, characterized in that, A communication port (14) is provided between two adjacent air ducts (10a), and two ends of the communication port (14) are respectively connected to the inner extension portions (112) of the two adjacent air ducts (10a).

5. The air duct structure according to claim 2, wherein The air duct structure further comprises a plurality of tooth plates (15), the plurality of tooth plates (15) being connected to the inner diameter end (101), the plurality of tooth plates (15) being arranged at intervals along the circumference of the slot plate (10), and parts of the inner extension portions (112) of two adjacent air ducts (10a) extending to the same tooth plate (15).

6. The air duct structure according to claim 1, characterized in that The air outlet section (13) comprises a flared portion (131) and an outer extension portion (132); two ends of the flared portion (131) are respectively connected to the expansion chamber (12) and the outer extension portion (132); and a cross-sectional dimension of an end of the flared portion (131) facing the expansion chamber (12) is smaller than a cross-sectional dimension of an end of the flared portion (131) facing away from the expansion chamber (12).

7. The air duct structure according to claim 6, wherein, An outer guide bar (133) is provided in the outer extension portion (132), and an extension direction of the outer guide bar (133) is parallel to an extension direction of the outer extension portion (132).

8. The air duct structure according to any one of claims 1-7, characterized in that, A partition strip (103) is defined between two adjacent air ducts (10a). The partition strip (103) has a width dimension, and the width dimension is the distance between the inner wall of the air duct (10a) formed by the partition strip (103) and the inner wall of another air duct (10a). In the extending direction of the partition strip (103), the width dimension of the partition strip (103) remains unchanged.

9. A motor, characterized in that, Comprising: A plurality of stator cores (20) arranged in sequence along the axial direction of the motor; and A plurality of air duct structures as described in any one of claims 1-8, and the air duct structures are arranged between two adjacent stator cores (20). The plate surface of the slot plate (10) facing away from the air duct (10a) is connected to one stator core (20), and the plate surface of the slot plate (10) provided with the air duct (10a) abuts against another stator core (20).

10. A design method for the air duct structure of a motor, characterized in that, The motor is the motor as described in claim 9, and the design method includes: Obtain the designed value c of the sound velocity in the expansion chamber (12) and the designed value b of the width of the expansion chamber (12), and determine the maximum sound absorption frequency f of the Nth order of the expansion chamber (12) based on the designed value c of the sound velocity and the designed value b of the width of the expansion chamber Nmax and the failure frequency f cut ; According to the maximum noise cancellation frequency f Nmax being equal to the frequency f1 of the fundamental frequency pneumatic noise of the motor, and the maximum noise cancellation frequency f Nmax being less than the failure frequency f cut , a sequence of tentative values of the length l of the expansion chamber (12) is obtained; Obtain a tentative value of the length l1 of the first interpolation segment (121), a tentative value of the length l2 of the second interpolation segment (122), and the cross-sectional expansion ratio m of the air duct (10a), and determine the sound transmission loss L of the expansion chamber (12) based on these three values and the tentative value of the length l of the expansion chamber (12). TL ; The sound transmission loss L TL When it is not less than the target value, the tentative values of the length l of the expansion chamber (12), the tentative value of the length l1 of the first interpolation section (121), and the tentative value of the length l2 of the second interpolation section (122) are determined as the target setting values; The sound transmission loss L TL When it is less than the target value, at least one of the planned value of the length l of the expansion chamber (12), the planned value of the length l1 of the first interpolation section (121), and the planned value of the length l2 of the second interpolation section (122) is adjusted until the sound transmission loss L TL is not less than the target value.

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