Air duct structure, motor and air duct structure design method

Abstract

The present application relates to an air duct structure, a motor and an air duct structure design method. The air duct structure includes a fan-shaped groove plate, on which an air duct is arranged; the air duct includes an air inlet section, an expansion chamber and an air outlet section that are connected in sequence; along the circumference of the groove plate, the air inlet section and the air outlet section are staggered; one end of the air inlet section extends into the expansion chamber and defines a first interpolated section between the air inlet section and the expansion chamber; one end of the air outlet section extends into the expansion chamber and defines a second interpolated section between the air inlet section and the expansion chamber. Through the above scheme, the present application makes part of the sound waves entering the expansion chamber reflect back to the sound source or reflect back and forth and interfere inside the muffler to attenuate the sound waves, reduce the sound wave capacity, and thus hinder the sound waves from propagating downstream. While guiding the airflow, the first interpolated section and the second interpolated section can also increase the internal area of ​​the expansion chamber, thereby increasing the number of reflections and scatterings of the sound waves in the chamber, and the sound wave attenuation effect is better. In this way, the noise of the generator during operation can be reduced.

Description

Technical Field

[0001] The present application relates to the field of motor technology, and in particular to an air duct structure, a motor, and an air duct structure design method. Background Art

[0002] A motor is an electromagnetic device that converts electrical energy into mechanical energy based on the law of electromagnetic induction. A generator is a type of motor that converts other forms of energy into electrical energy. A generator primarily comprises a housing, a stator assembly secured within the housing, and a rotor assembly rotatably disposed within the housing. The rotor assembly comprises a main shaft, a stator core sleeved on the main shaft, and rotor windings wound around the rotor core. The stator assembly comprises a stator core and wire rods wound around the teeth of the stator core laminations. The stator core comprises a plurality of stacked silicon steel sheets.

[0003] Generators generate considerable heat due to mechanical losses and resistive heating during operation. To maintain generator performance and improve operating temperature, heat dissipation is necessary. In related art, to improve the operating temperature of the stator assembly, an air duct is provided on the stator assembly. A fan drives airflow within the duct, removing heat from the stator assembly and cooling it.

[0004] When air flows over structural surfaces, it creates turbulence, which in turn generates noise. Noise pollution is a sensory hazard. Long-term exposure to high noise levels exceeding 90 dB(A) can lead to deafness, neurasthenia, and cardiovascular disease. Furthermore, the near-field noise level of large AC-excited generators can reach 105 dB(A) to 120 dB(A). Therefore, it is necessary to reduce generator noise during operation and improve the working environment of power plants to protect the physical and mental health of those involved. Summary of the Invention

[0005] The embodiment of the present application provides an air duct structure that can reduce the noise during operation of the generator, so as to at least solve the above-mentioned technical problems.

[0006] In order to achieve the above-mentioned purpose, according to the first aspect of the present application, a duct structure is provided, which includes a fan-shaped trough plate, the two ends of the trough plate are the inner diameter end and the outer diameter end respectively, and multiple ducts are arranged on one side plate surface of the trough plate, and the multiple ducts are arranged at intervals along the circumference of the trough plate; from the inner diameter end to the outer diameter end, the duct includes an air inlet section, an expansion chamber and an air outlet section that are connected in sequence; along the circumference of the trough plate, the air inlet section and the air outlet section are staggered; wherein, one end of the air inlet section extends into the expansion chamber, and defines a first interpolated section between the air inlet section and the expansion chamber; one end of the air outlet section extends into the expansion chamber, and defines a second interpolated section between the air inlet section and the expansion chamber.

[0007] Optionally, the air inlet section includes a necking portion and an inner extension portion, the two ends of the necking portion are respectively connected to the expansion chamber and the inner extension portion, and the cross-sectional dimension of the end of the necking portion facing the expansion chamber is smaller than the cross-sectional dimension of the end of the necking portion facing away from the expansion chamber.

[0008] Optionally, an inner guide strip is provided in the inner extension portion, and an extension direction of the inner guide strip is parallel to an extension direction of the inner extension portion.

[0009] Optionally, a communication port is provided between two adjacent air ducts, and both ends of the communication port are respectively communicated with the inner extension portions of the two adjacent air ducts.

[0010] Optionally, the air duct structure further includes a plurality of tooth plates connected to the inner diameter end, the plurality of tooth plates are arranged at intervals along the circumference of the slot plate, and partial inner extensions of two adjacent air ducts extend to the same tooth plate.

[0011] Optionally, the air outlet section includes a flared portion and an outer extension portion, the two ends of the flared portion are respectively connected to the expansion cavity and the outer extension portion, and the cross-sectional dimension of the end of the flared portion facing the expansion cavity is smaller than the cross-sectional dimension of the end of the flared portion facing away from the expansion cavity.

[0012] Optionally, an outer guide strip is provided in the outer extension portion, and an extension direction of the outer guide strip is parallel to an extension direction of the outer extension portion.

[0013] Optionally, a partition strip is defined between two adjacent air ducts, and the widths of any two parts of the partition strip are consistent.

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

[0015] According to a third aspect of the present application, a method for designing an air duct structure of a motor is provided. The motor is the aforementioned motor, and the design method includes:

[0016] Obtain the sound velocity design value c and the expansion cavity width design value b in the expansion cavity, and determine the maximum sound absorption frequency f of the expansion cavity at order N based on the sound velocity design value c, the expansion cavity width design value b and the expansion cavity length l setting value. Nmax and failure frequency f cut ;

[0017] According to the maximum anechoic frequency f Nmax The frequency f1 is equal to the fundamental frequency of the aerodynamic noise of the motor, and the maximum silencing frequency f Nmax Less than the failure frequency f cut , obtain the series of proposed values ​​of the length l of the expansion cavity;

[0018] Obtain the proposed value of the length l1 of the first interpolation segment, the proposed value of the length l2 of the second interpolation segment, and the cross-sectional expansion ratio m of the air duct, and determine the acoustic transmission loss L of the expansion cavity based on these three and the proposed value of the length l of the expansion cavity. TL ;

[0019] Acoustic transmission loss L TL If the values ​​are not less than the target values, the proposed values ​​of the length l of the expansion cavity, the proposed values ​​of the length l1 of the first interpolation segment, and the proposed values ​​of the length l2 of the second interpolation segment are determined as target setting values;

[0020] Acoustic transmission loss L TL When the acoustic transmission loss L is less than the target value, at least one of the proposed value of the expansion cavity length l, the proposed value of the first interpolation section length l1, and the proposed value of the second interpolation section length l2 is adjusted until the acoustic transmission loss L TL Not less than the target value.

[0021] 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, suddenly changes, resulting in an acoustic impedance mismatch, causing part of the sound waves entering the expansion chamber to reflect back to the sound source or reflect back and forth inside the muffler, interfering with each other, thereby attenuating the sound waves and reducing the sound wave capacity, thereby hindering the sound waves from propagating downstream. The provision of the first interpolated section and the second interpolated section can not only guide the airflow, but also increase the internal area of ​​the expansion chamber, thereby increasing the number of reflections and scatterings of the sound waves in the chamber, making the sound wave energy more dispersed and the sound wave attenuation effect better. In this way, the noise of the generator during operation can be reduced.

[0022] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] To more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present application. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0024] In order to more completely understand the present application and its beneficial effects, the following description will be given in conjunction with the accompanying drawings, wherein the same drawing numbers represent the same parts in the following description.

[0025] Figure 1 is a structural schematic diagram of an air duct structure provided in an exemplary embodiment of the present disclosure;

[0026] Figure 2 is a side view of an air duct structure provided in an exemplary embodiment of the present disclosure;

[0027] Figure 3 is a schematic diagram of a partial structure of an air duct structure provided in an exemplary embodiment of the present disclosure;

[0028] Figure 4 is a schematic diagram of a partial structure of a motor provided in an exemplary embodiment of the present disclosure;

[0029] Figure 5 is a partial side view of a motor provided in an exemplary embodiment of the present disclosure;

[0030] Figure 6 is a flowchart of a design method provided in an exemplary embodiment of the present disclosure;

[0031] Figure 7 A comparison chart of acoustic transmission loss analysis provided in an exemplary embodiment of the present disclosure;

[0032] Figure 8 A comparison diagram of aerodynamic noise spectra of a generator provided in an exemplary embodiment of the present disclosure.

[0033] Description of reference numerals:

[0034] 100- air duct structure;

[0035] 10-slot plate; 101-inner diameter end; 102-outer diameter end; 103-separator strip; 104-plate body;

[0036] 10a-air duct;

[0037] 11-air inlet section; 111-narrowing portion; 112-inner extension portion; 113-inner guide strip;

[0038] 12- expansion cavity; 121- first interpolated section; 122- second interpolated section; 123- sharp corner; 124- inflection point;

[0039] 13-air outlet section; 131-expansion portion; 132-external extension portion; 133-external guide strip;

[0040] 14- communication port;

[0041] 15-tooth plate; 151-threading groove;

[0042] 200-motor; 20-stator core; 201-silicon steel sheet group; 202-winding slot; 21-stator wire rod; 22-slot wedge. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0044] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or mutual communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0045] The terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that products and methods comprising a list of elements include not only those elements but also other elements not explicitly listed or inherent to such products and methods. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the product and method comprising the element.

[0046] Before introducing an air duct structure, a motor, and an air duct structure design method thereof provided in the embodiments of the present application, the relevant technologies of the present application are first introduced.

[0047] In related technologies, generator noise sources are composed of vibration noise and aerodynamic noise. Vibration noise includes electromagnetic noise generated by alternating electromagnetic forces in the air gap and mechanical noise caused by frictional vibrations of moving parts. Aerodynamic noise is generated by the turbulence of airflow flowing over the structural surface inside the generator. Its generation and propagation occur within the gas medium and are not necessarily related to structural vibration. The magnitude of aerodynamic noise is determined by the Mach number of the airflow, and its spectrum is composed of both broadband and discrete noise.

[0048] Currently, methods for suppressing electromagnetic noise include installing skewed slots, skewing poles, reducing slot size, and using magnetic slot wedges. Mechanical noise is also suppressed by improving rotor dynamic balance, increasing structural rigidity, avoiding modal natural frequencies, and increasing vibration damping. Research on the mechanisms and applied technologies for these vibration and noise reduction technologies is relatively mature, and practice has proven that appropriate electromagnetic and structural optimization can control generator near-field vibration noise to no more than 90dB(A), meeting noise control requirements.

[0049] However, the rotor linear speed of large AC-excited generators can reach over 100 meters per second, resulting in an airflow Mach number close to 0.4, causing the generator's near-field aerodynamic noise to exceed 105dB(A). This makes aerodynamic noise a significant factor in determining the noise level of this type of generator.

[0050] At present, the main ways to suppress generator aerodynamic noise are as follows:

[0051] (1) Reducing the number of sound-generating components on the sound source side, including eliminating the rotor fan, eliminating the external ventilator, and reducing the cooling air duct. These measures reduce the ventilation and heat dissipation performance of the generator, resulting in an increase in the temperature rise of the generator;

[0052] (2) Optimizing the air flow pattern in the noise source area, including developing low-noise fans and improving the rotor duct structure, so as to achieve noise reduction by weakening the unsteady airflow disturbance in the noise source area. However, under the premise that the electromagnetic power of the generator is high and the radial size of the generator remains unchanged, the Mach number of the airflow before and after the implementation of such measures does not change much, and the reduction in aerodynamic noise is small, usually not exceeding 3dB(A);

[0053] (3) Increasing the acoustic impedance on the propagation side, for example, using a soundproof chamber to completely cover the generator, installing sound-absorbing materials and perforated plates on the surface of the generator chamber, etc. By increasing the acoustic radiation impedance outside the generator, a better noise reduction effect can be achieved. This is a common noise reduction measure for large generators, but it will increase the equipment manufacturing and maintenance costs, and have an adverse effect on the heat dissipation of the generator.

[0054] Based on the above situation, in order to solve the aerodynamic noise problem of generators, especially the aerodynamic noise problem of large AC excitation generators, the embodiments of the present application provide a duct structure, a motor and a duct structure design method thereof. The duct structure provided by the embodiments of the present application can significantly suppress the fundamental frequency aerodynamic noise in the medium and low frequency bands (<3000Hz) (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 duct structure provided by the embodiments of the present application can reduce the noise of the generator while taking into account the ventilation and heat dissipation performance of the generator and reducing the manufacturing cost of the generator.

[0055] The following combination Figures 1 to 8 , a duct structure, a motor and a duct structure design method thereof provided in the embodiments of the present application are described in detail respectively.

[0056] See also Figure 1 and Figure 2 , Figure 1 is a structural schematic diagram of an air duct structure 100 provided in an 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 trough plate 10. The two ends of the trough plate 10 are an inner diameter end 101 and an outer diameter end 102, respectively. A plurality of air ducts 10a are provided on a side plate surface of the trough plate 10. The plurality of air ducts 10a are arranged at intervals along the circumference of the trough 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 trough 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 interleaved 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 interleaved section 122 between the air outlet section 13 and the expansion chamber 12.

[0057] 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 facing away from the air duct 10a is connected to one stator core 20 of the motor 200, and the plate surface of the slot plate 10 provided with the air duct 10a is in contact with the other 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.

[0058] It can be understood that one end of the first inserted section 121 is integrally connected to the surface of the slot plate 10 that defines the air inlet section 11 , and the other end of the first inserted section 121 is inserted into the expansion cavity 12 and extends radially along the slot plate 10 .

[0059] It can be understood that one end of the second inserted section 122 is integrally connected to the surface of the slot plate 10 that defines the air outlet section 13 , and the other end of the second inserted section 122 is inserted into the expansion cavity 12 and extends radially along the slot plate 10 .

[0060] It can be understood that the length of the expansion cavity 12 is l, the length of the first inserting section 121 is l1, and the length of the second inserting section 122 is l2. Figure 3 As shown, Figure 31 is a partial structural diagram of the air duct structure 100 provided in an exemplary embodiment of the present disclosure. The length dimension l of the expansion cavity 12 is greater than the sum of the length dimension l1 of the first inserting section 121 and the length dimension l2 of the second inserting section 122, so as to ensure that the airflow entering the expansion cavity 12 from the air inlet section 11 can flow out smoothly from the air outlet section 13. The length dimension l can be the longest dimension of the expansion cavity 12, or the dimension between the inflection point 124 on the outer circumference side and the inflection point 124 on the inner circumference side of the expansion cavity 12, or Figure 3 As shown, the dimension is located between the midpoint between the sharp corner 123 and the inflection point 124 of the expansion chamber 12.

[0061] It can be understood that the cross section of the air duct 10a perpendicular to the airflow direction is the cross section of the air duct 10a. Specifically, the cross-sectional area S1 of the portion of the air inlet section 11 near 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 portion of the air outlet section 13 near the expansion chamber 12 is smaller than the cross-sectional area S2 of the expansion chamber 12. Specifically, S1 = S3.

[0062] Exemplarily, the trough plate 10 is a steel plate.

[0063] In this embodiment, by providing an air inlet section 11, an expansion chamber 12, and an air outlet section 13 that are interconnected in sequence, the cross-sectional area between the air inlet section 11 and the expansion chamber 12, and between the air outlet section 13 and the expansion chamber 12, suddenly changes. This creates an acoustic impedance mismatch, causing some sound waves entering the expansion chamber 12 to reflect back to the source or reflect back and forth within the muffler, interfering with each other. This attenuates the sound waves, reduces their power, and thus hinders their propagation downstream (i.e., to the air outlet section 13). The provision of a first interpolated section 121 and a second interpolated section 122 not only guides the airflow but also increases the internal area of ​​the expansion chamber 12, thereby increasing the number of reflections and scatterings of sound waves within the chamber, further dispersing the sound wave energy and achieving enhanced sound attenuation. This reduces generator noise during operation, improves the working environment of the power plant, and protects the physical and mental health of relevant personnel.

[0064] Moreover, compared with the noise reduction measures in the related art such as reducing the sound-emitting 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 caused by arranging a soundproof room and installing sound-absorbing materials.

[0065] It is understood that the expansion chamber 12 has a fixed size, and accordingly, the impedance of the air duct structure 100 is fixed. However, the impedance of sound waves of different frequencies is different, and the size of the air duct 10a needs to be set accordingly for different types of motors 200 to achieve noise reduction processing for sound waves of the target frequency.

[0066] 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.

[0067] In addition, each expansion cavity 12 is provided with an air inlet section 11 on both sides near the inner diameter end 101. To avoid the need for air inlet sections 11 and to ensure that they can smoothly direct airflow into the expansion cavity 12, the width of the end of each expansion cavity 12 near the inner diameter end 101 gradually decreases as it approaches the inner diameter end 101, resulting in a sharp corner 123 at the portion of the expansion cavity 12 near the inner diameter end 101. This not only improves the smoothness of airflow in the air inlet section 11, but also allows the expansion cavity 12 to have more surfaces arranged at angles to each other, thereby increasing the number of reflections and scatterings of sound waves within the cavity, further dispersing the sound wave energy and achieving better sound wave attenuation.

[0068] Correspondingly, each expansion cavity 12 is provided with an air outlet section 13 on both sides near the outer diameter end 102. To avoid the need for air outlet sections 13 and enable them to smoothly direct the airflow, the width of each expansion cavity 12 near the outer diameter end gradually decreases as it approaches the outer diameter end, resulting in a sharp corner 123 at the portion of the expansion cavity 12 near the outer diameter end. This not only improves the smoothness of airflow, but also allows the expansion cavity 12 to have more surfaces arranged at angles to each other, thereby increasing the number of reflections and scatterings of sound waves within the cavity, further dispersing the sound wave energy and achieving better sound wave attenuation.

[0069] 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 the end of the constricted portion 111 facing the expansion chamber 12 is smaller than the cross-sectional dimension of the end of the constricted portion 111 facing 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.

[0070] Specifically, the inner extension portion 112 smoothly transitions to the expansion cavity 12 through the necked portion 111 .

[0071] 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 .

[0072] Exemplarily, the inner guide strip 113 and the slot plate 10 are integrally formed.

[0073] In this embodiment, by providing an inner guide bar 113 in the inner extension portion 112, a structure with a multi-path converging effect can be formed between the inner extension portion 112 and the necked portion 111, thereby reducing the flow resistance loss of the cooling air, thereby improving the effectiveness of the cooling air blowing on the side edges of the wire rods and the surface of the core, and achieving the function of fully cooling the stator assembly.

[0074] In addition, by providing an inner guide strip 113 in the inner extension portion 112, on the one hand, the contact area between the air duct structure 100 and the airflow can be increased, so as to improve the heat dissipation efficiency of the air duct structure 100; on the other hand, the airflow in the inner extension portion 112 can be guided by the inner guide strip 113, so that the airflow flows more smoothly, so as to reduce the airflow loss.

[0075] See also Figure 2 In some embodiments, a communication port 14 is provided between two adjacent air ducts 10a. The two ends of the communication port 14 communicate with the inner extensions 112 of the two adjacent air ducts 10a. This allows the airflow within one air duct 10a to be directed into the other air duct 10a through the communication port 14, allowing the airflow to flow along the circumference of the slot plate 10. This helps optimize the air flow pattern, thereby reducing flow resistance and improving airflow efficiency.

[0076] See also 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 spaced apart along the circumference of the slot plate 10 . Partial inner extensions 112 of two adjacent air ducts 10 a extend to the same tooth plate 15 .

[0077] It can be understood that a wire threading groove 151 is formed between two adjacent tooth plates 15 , and the stator bars 21 of the generator are wound in the wire threading groove 151 .

[0078] It can be understood that the tooth plate 15 is arranged opposite to the tooth portion of the stator core 20 , and the slot plate 10 is arranged opposite to the yoke portion of the stator core 20 .

[0079] Exemplarily, the tooth plate 15 is integrally provided with the groove plate 10 .

[0080] In this embodiment, by providing the tooth plate 15, on the one hand, the contact area between the air duct structure 100 and the stator core 20 can be increased, thereby improving the heat dissipation efficiency of the air duct 10a component to the stator core 20; on the other hand, the airflow located on the inner peripheral side of the stator component can be guided, thereby improving the smoothness of the airflow flow, which is conducive to improving the heat dissipation efficiency of the motor 200.

[0081] See also Figure 1 and Figure 2 In some embodiments, the air outlet section 13 includes a flared portion 131 and an outer extension portion 132. The two ends of the flared portion 131 are respectively connected to the expansion chamber 12 and the outer extension portion 132. The cross-sectional dimension of the end of the flared portion 131 facing the expansion chamber 12 is smaller than the cross-sectional dimension of the end of the flared portion 131 facing away from the expansion chamber 12. In this way, the airflow can be smoothly introduced into the outer extension portion 132 through the flared portion 131, 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.

[0082] Specifically, the outer extension portion 132 smoothly transitions to the expansion cavity 12 through the flared portion 131 .

[0083] In some embodiments, 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 .

[0084] Exemplarily, the outer guide strip 133 is integrally formed with the slot plate 10 .

[0085] In this embodiment, by providing an 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 airflow can be increased, so as to improve the heat dissipation efficiency of the air duct structure 100; on the other hand, the airflow in the outer extension portion 132 can be guided by the outer guide strip 133, so that the airflow flows more smoothly, so as to reduce the airflow loss.

[0086] See also Figure 1 and Figure 2 In some embodiments, a dividing strip 103 is defined between two adjacent air ducts 10a. The width of the dividing strip 103 remains constant along its extension direction. This allows for a uniform structure in the portion of the trough plate 10 located between the two air ducts 10a, thereby improving the stress response of the trough plate 10 and avoiding stress concentration. This improves the strength of the air duct structure 100.

[0087] It can be understood that the width dimension of the dividing strip 103 refers to the distance between the inner wall of one air duct 10a formed by the dividing strip 103 and the inner wall of another air duct 10a formed by the dividing strip 103 .

[0088] Exemplarily, the width of the separator 103 is 0.5 mm to 4 mm. The width of the separator 103 includes but is not limited to 0.5 mm, 1.5 mm, 2 mm, 3 mm, and 4 mm.

[0089] Exemplarily, the separator bar 103 may be a channel steel.

[0090] Illustratively, the trough plate 10 includes a plate body 104 and a plurality of dividing bars 103 disposed on the plate body 104. The dividing bars 103 are spaced circumferentially, with adjacent dividing bars 103 defining an air duct 10a between them. The plate body 104 and the dividing bars 103 may be integrally formed, or the dividing bars 103 may be welded to the plate body 104. When the dividing bars 103 are channel steel, the portion of the dividing bars 103 facing the teeth of the stator core 20 is the tooth channel steel, and the portion facing the yoke of the stator core 20 is the yoke channel steel.

[0091] See also Figure 4 and Figure 5 , Figure 4 is a partial structural diagram of a motor 200 provided in an 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. In the second aspect, the embodiment of the present application also provides a motor 200. The motor 200 includes a stator core 20 and the aforementioned air duct structure 100. There are multiple stator cores 20. The multiple stator cores 20 are arranged in sequence along the axial direction of the motor 200. An air duct structure 100 is provided between each adjacent stator core 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.

[0092] 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 on the rotating shaft.

[0093] It is understood that the motor 200 further includes stator bars 21, which are wound around the stator core 20, ie, the air duct structure 100, to form a stator assembly. An air gap is provided between the stator assembly and the rotor assembly.

[0094] As will be understood, the stator core 20 includes multiple silicon steel sheet groups 201, which are arranged sequentially along the circumferential direction, with adjacent silicon steel sheet groups 201 contacting each other. Each silicon steel sheet group 201 includes multiple silicon steel sheets stacked sequentially along the axial direction of the motor 200. Each stator core 20 has multiple air duct structures 100, each corresponding to one of the multiple silicon steel sheet groups 201.

[0095] Specifically, winding slots 202 are defined between the teeth of the stator core 20 , and slot wedges 22 are provided on a side of the winding slots 202 away from the yoke of the stator core 20 . The slot wedges 22 press the wire rods into the winding slots 202 .

[0096] It can be understood that the motor 200 includes the above-mentioned air duct structure 100, and the motor 200 has all the beneficial effects of the above-mentioned air duct structure 100, which will not be described in detail in this disclosure.

[0097] See also Figure 6 , Figure 6 is a flow chart of a 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 an air duct structure 100 of a motor 200, wherein the motor 200 is the aforementioned motor 200, and the design method includes:

[0098] Obtain the sound velocity design value c in the expansion cavity 12 and the expansion cavity width design value b, and determine the Nth-order maximum sound absorption frequency f of the expansion cavity 12 based on the sound velocity design value c, the expansion cavity width design value b and the expansion cavity length l setting value. Nmax and failure frequency f cut ;

[0099] According to the maximum anechoic frequency f Nmax The frequency f1 is equal to the fundamental frequency of the aerodynamic noise of the motor, and the maximum silencing frequency f Nmax Less than the failure frequency f cut , obtaining a series of proposed values ​​of the length l of the expansion chamber 12;

[0100] Obtain the proposed value of the length l1 of the first interpolation segment 121, the proposed 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 acoustic transmission loss L of the expansion cavity 12 based on these three and the proposed value of the length l of the expansion cavity 12 TL ;

[0101] Acoustic transmission loss L TL If the values ​​are not less than the target values, the proposed values ​​of the length l of the expansion cavity 12, the proposed values ​​of the length l1 of the first interpolation section 121, and the proposed values ​​of the length l2 of the second interpolation section 122 are determined as target setting values.

[0102] Acoustic transmission loss L TL When the acoustic transmission loss L is less than the target value, at least one of the proposed value of the length l of the expansion cavity 12, the proposed value of the length l1 of the first interpolation section 121, and the proposed value of the length l2 of the second interpolation section 122 is adjusted until the acoustic transmission loss L is less than the target value. TL Not less than the target value.

[0103] It is understood that the proposed value of the length l of the expansion chamber 12 must satisfy f Nmax = f1,f Nmax <f cut The proposed value of the length l1 of the first interpolation section 121, the proposed value of the length l2 of the second interpolation section 122 and the proposed value of the length l of the expansion cavity 12 must satisfy L TL Not less than the target value.

[0104] Specifically, the design method includes the following steps.

[0105] S100, obtaining the cross-sectional expansion ratio m of the air duct 10a;

[0106] Specifically, a generator ventilation calculation program (e.g., Fluent, Flowmaster) is used to calculate the generator ventilation temperature rise. Based on the cross-sectional area s1 of the air inlet section 11 in the stator core 20 air duct 10a near the expansion cavity 12 and the cross-sectional area s2 of the expansion cavity 12, the cross-sectional expansion ratio m of the air duct 10a is:

[0107] Formula (1);

[0108] In the above description, the cross-sectional area of ​​the air inlet section 11 close to the expansion chamber 12 and the cross-sectional area of ​​the air outlet section 13 close to the expansion chamber 12 are both S1.

[0109] S200 , obtaining a near-field noise spectrum of the motor 200 , and determining a frequency f1 of a fundamental aerodynamic noise of the motor 200 according to the near-field noise spectrum;

[0110] Specifically, the aeroacoustic time domain analysis method is used to calculate the aerodynamic noise of the generator and obtain the near-field noise spectrum of the generator. According to the near-field noise spectrum, the frequency f1 of the fundamental frequency aerodynamic noise of the generator is determined as:

[0111] Formula (2);

[0112] in,

[0113] z2 is the number of rotor slots of large AC excitation generator;

[0114] n is the operating speed.

[0115] 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 noise source's sound frequency and the corresponding sound pressure level. By analyzing the near-field noise spectrum, we can obtain the noise frequency and sound pressure level with the highest weight, which are the two characteristics of the fundamental aerodynamic noise. The noise frequency is the frequency of the fundamental noise.

[0116] S300, obtaining a proposed value of the length l of the expansion cavity 12;

[0117] Determine the maximum muffler frequency f of the Nth order of the expansion chamber 12 Nmax ,in,

[0118] Formula (3);

[0119] Wherein, c is the design value of the speed of sound in the expansion chamber 12 .

[0120] Determine the failure frequency f of the expansion chamber 12cut ,in:

[0121] Formula (4);

[0122] Here, b is the width of the expansion chamber 12 .

[0123] Select N from 0 to 4, and according to f Nmax = f1, and f Nmax <f cut , a series of lengths l of the expansion chamber 12 is obtained, where each value in the series is a proposed value of the length l of the expansion chamber 12.

[0124] S400 , obtaining a proposed value of the length l1 of the first interpolation segment 121 and a proposed value of the length l2 of the second interpolation segment 122 , where 0<l1+l2<l;

[0125] S500: Determine the acoustic transmission loss L of the expansion chamber 12 based on the estimated value of the length l of the expansion chamber 12, the estimated value of the length l1 of the first interpolation section 121, the estimated value of the length l2 of the second interpolation section 122, and the cross-sectional expansion ratio m of the air duct 10a. TL ;

[0126] Specifically, based on the plane wave theory frequency domain analysis method, the transfer matrix method is used to calculate the acoustic transmission loss of the expansion cavity 12 as follows:

[0127] Formula (5);

[0128] in,

[0129] k is the wave number;

[0130] represents the incident wave sound pressure, i.e., the pressure of the sound wave entering the expansion chamber 12;

[0131] It represents the sound pressure of the transmitted wave, which is the pressure of the sound wave that continues to propagate forward after passing through the expansion cavity 12.

[0132] S600, determine L TL Is it not less than the target value? If so, the proposed value of the length l of the expansion cavity 12, the proposed value of the length l1 of the first interpolation section 121, and the proposed value of the length l2 of the second interpolation section 122 are determined as the target set value. If not, at least one of the proposed value of the length l of the expansion cavity 12, the proposed value of the length l1 of the first interpolation section 121, and the proposed value of the length l2 of the second interpolation section 122 is adjusted until the target value is satisfied. Nmax = f1, and f Nmax <f cut When L TL Not less than the target value.

[0133] The target value can be set according to the requirements of the motor's application environment. For example, the target value can be 30dB (A). Correspondingly, the following conditions need to be met: L TL ≥30dB(A).

[0134] It can be understood that the Nth order passing frequency f of the expansion chamber 12 Nmin It can be determined based on the modal order N, the sound velocity design value c and the target setting value of the length l of the expansion cavity 12. Specifically,

[0135] Formula (6).

[0136] It can be understood that the noise reduction capability of the expansion chamber 12 has an applicable frequency range. nmax When f cut Therefore, the fundamental frequency aerodynamic noise f1 of the motor 200 needs to be exactly equal to f Nmax , while f Nmax Cannot exceed f cut In this way, the expansion chamber 12 has the best silencing effect on the fundamental frequency aerodynamic noise with a frequency of f1.

[0137] Understandably, if Nmax = f1, and f Nmax <f cut When L TL If the value is less than the target value, at least one of the set value of the length l of the expansion cavity 12, the proposed value of the length l1 of the first interpolation segment 121, and the proposed value of the length l2 of the second interpolation segment 122 is adjusted, and the next round of iterative calculation is performed until f is satisfied. Nmax = f1, and f Nmax <f cut When L TL Not less than the target value.

[0138] Among them, because the one-dimensional acoustic impedance derived from plane wave theory ignores the influence of high-order acoustic modes and the calculation accuracy is limited, it is necessary to use aeroacoustic time domain analysis to perform a detailed calculation of the aerodynamic noise spectrum of the generator (e.g., a large AC excitation generator) using the air duct structure 100, and compare it with the aerodynamic noise spectrum of the original generator of the air duct structure 100 provided in the embodiment of the present application to determine whether the noise suppression effect meets expectations. If it does not meet expectations, it is necessary to adjust at least one of the dimensions l, l1, and l2 of the expansion chamber 12, and iterate this calculation until L TL If the value meets expectations, the effective size of the air duct structure 100 can be determined.

[0139] The embodiments of the present application are based on the principle of noise reduction of the expansion chamber 12 and combined with frequency domain and time domain analysis methods to achieve the function of accurately predicting and suppressing the fundamental frequency aerodynamic noise of the generator (for example, large AC excitation).

[0140] As can be seen from the above, the embodiments of the present application have at least the following beneficial effects:

[0141] First, the embodiment of the present application uses the expansion chamber 12, the first inserted section 121 and the second inserted section 122 to guide the airflow on the basis of expansion silencer, and can increase the internal area of ​​the expansion chamber 12, thereby increasing the number of reflections and scattering of sound waves in the cavity, making the sound wave energy more dispersed and the sound wave attenuation effect better.

[0142] Secondly, by controlling the wind resistance of duct 10a and optimizing the dimensional parameters of duct structure 100, the generator's fundamental frequency aerodynamic noise can be significantly suppressed. Compared to related art noise reduction measures such as reducing sound-emitting components on the sound source side and optimizing airflow patterns in the sound source area, the embodiments of this application are simple to implement and achieve superior noise reduction results.

[0143] Third, through CFD fluid property analysis, the drag coefficient of the duct structure 100 is optimized, ensuring that the overall wind resistance of the generator ventilation system does not increase significantly compared to related technologies, thereby preventing a significant negative impact on the cooling of the motor 200. Thus, the rational design of the dimensional parameters of the duct structure 100 reduces the flow resistance loss of air flowing through the duct 10a, ensuring proper ventilation and heat dissipation of the generator. Compared to noise reduction measures such as eliminating the rotor fan and reducing the number of cooling ducts 10a, the embodiment of the present application has a minimal impact on the ventilation and heat dissipation performance of the generator.

[0144] Fourthly, the additional equipment manufacturing and maintenance costs caused by arranging a soundproof room and installing sound-absorbing materials can be avoided, and the embodiment of the present application has good economic efficiency.

[0145] The technical solutions provided by the embodiments of the present application are further described in detail below in combination with specific examples and data. It should be understood that the following examples are only used to explain the present application and are not used to limit the present application.

[0146] Example 1

[0147] The acoustic transmission loss of the wind duct 10a of the prior art generator and the acoustic transmission loss of the wind duct structure 100 of the generator provided in the embodiment of the present application are analyzed by simulation software (eg, COMSOL Multiphysics, Ansys series software), and the following is obtained: Figure 7 A comparison chart of acoustic transmission loss analysis is shown. Figure 7Figure (a) shows an analysis of the sound transmission loss of a conventional generator duct 10a, while Figure (b) shows an analysis of the sound transmission loss of a generator duct structure 100 according to an embodiment of the present application. The sound transmission loss analysis diagrams reflect the reduction in sound at the outlet of each duct 10a relative to the inlet of the duct 10a after propagation through the respective ducts 10a. Compared to Figure (a), Figure (b) shows a greater reduction in sound at specific frequencies (primarily between 400Hz and 3000Hz). This demonstrates that the duct structure 100 according to the embodiment of the present application has superior sound attenuation.

[0148] Example 2

[0149] The aerodynamic noise spectrum of the generator in the prior art and the aerodynamic noise spectrum of the generator provided by the embodiment of the present application are analyzed by simulation software (for example, COMSOL Multiphysics, Ansys series software), and the following is obtained: Figure 8 The comparison chart of the generator aerodynamic noise spectrum is shown. Figure 8 Figure (c) shows the aerodynamic noise spectrum of a generator in the prior art, and Figure (d) shows the aerodynamic noise spectrum of a generator provided in an embodiment of the present application. Specifically, Figures (c) and (d) are the far-field noise spectra of the generator. In Figure (d), the SPL (sound pressure level) at the fundamental frequency of 2100 Hz is effectively suppressed, and the total noise (total noise refers to the sum of the weighted sound pressure levels for each frequency band in the spectrum) is also lower than in Figure (c). This shows that the air duct structure 100 provided in the embodiment of the present application has a better noise reduction capability.

[0150] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0151] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0152] The embodiments, implementation methods and related technical features of the present application can be combined and replaced with each other without conflict.

[0153] The above are merely preferred embodiments of the present application and do not constitute any form of limitation to the present application. However, any simple modifications, equivalent changes, and modifications 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 are still within the scope of the technical solution of the present application.

Claims

1. A method for designing an air duct structure of a motor, characterized in that: The motor has an air duct structure. From the radial outward direction of the motor, the air duct (10a) of the air duct structure includes an air inlet section (11), an expansion chamber (12), and an air outlet section (13) that are connected in sequence. 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 inlet section (11) and the expansion chamber (12). Wherein, the design method includes: Obtaining a sound velocity design value c in the expansion cavity (12) and a width design value b of the expansion cavity (12), and determining an N-order maximum sound absorption frequency f of the expansion cavity (12) based on the sound velocity design value c and the expansion cavity width design value b. Nmax and failure frequency f cut ; According to the maximum sound absorption frequency f Nmax is equal to the frequency f1 of the fundamental frequency aerodynamic noise of the motor, and the maximum muffler frequency f Nmax Less than the failure frequency f cut , obtaining a series of proposed values ​​of the length l of the expansion chamber (12); Obtaining a proposed value of the length l1 of the first interpolation section (121), a proposed value of the length l2 of the second interpolation section (122), and a cross-sectional expansion ratio m of the air duct (10a), and determining the acoustic transmission loss L of the expansion chamber (12) based on these three values ​​and the proposed value of the length l of the expansion chamber (12) TL ; The acoustic transmission loss L TL When the values ​​are not less than the target values, the proposed value of the length l of the expansion cavity (12), the proposed value of the length l1 of the first interpolation section (121), and the proposed value of the length l2 of the second interpolation section (122) are determined as target setting values; The acoustic transmission loss L TL When the acoustic transmission loss L is less than the target value, at least one of the proposed value of the length l of the expansion cavity (12), the proposed value of the length l1 of the first interpolation section (121), and the proposed value of the length l2 of the second interpolation section (122) is adjusted until the acoustic transmission loss L TL Not less than the target value.

2. The method for designing the air duct structure of a motor according to claim 1, characterized in that: The air duct structure comprises a fan-shaped trough plate (10), a plurality of air ducts (10a) are provided on a side plate surface of the trough plate (10), and the plurality of air ducts (10a) are arranged at intervals along the circumference of the trough 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 the air inlet section (11), the expansion chamber (12) and the 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 staggered.

3. The method for designing the air duct structure of the motor according to claim 2, characterized in that: The air inlet section (11) comprises a constricted portion (111) and an inner extension portion (112), the two ends of the constricted portion (111) being in communication with the expansion chamber (12) and the inner extension portion (112), respectively, and the cross-sectional dimension of the end of the constricted portion (111) facing the expansion chamber (12) is smaller than the cross-sectional dimension of the end of the constricted portion (111) facing away from the expansion chamber (12).

4. The method for designing the air duct structure of the motor according to claim 3, characterized in that: 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).

5. The method for designing the air duct structure of a motor according to claim 3, characterized in that: A communication port (14) is provided between two adjacent air ducts (10a), and both ends of the communication port (14) are respectively communicated with the inner extension portions (112) of the two adjacent air ducts (10a).

6. The method for designing the air duct structure of a motor according to claim 3, characterized in that: 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 the inner extension portions (112) of two adjacent air ducts (10a) extending to the same tooth plate (15).

7. The method for designing the air duct structure of a motor according to claim 2, wherein: The air outlet section (13) comprises a flared portion (131) and an outer extension portion (132), wherein both ends of the flared portion (131) are respectively connected to the expansion cavity (12) and the outer extension portion (132), and the cross-sectional dimension of the end of the flared portion (131) facing the expansion cavity (12) is smaller than the cross-sectional dimension of the end of the flared portion (131) facing away from the expansion cavity (12).

8. The method for designing the air duct structure of a motor according to claim 7, characterized in that: 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).

9. The method for designing an air duct structure of a motor according to any one of claims 2 to 8, characterized in that: A partition bar (103) is defined between two adjacent air ducts (10a), and the partition bar (103) has a width dimension, which is the distance between the inner wall of one air duct (10a) formed by the partition bar (103) and the inner wall of the other air duct (10a) formed by the partition bar (103). In the extension direction of the partition bar (103), the width dimension of the partition bar (103) remains unchanged.

10. The method for designing an air duct structure of a motor according to any one of claims 2 to 8, characterized in that: The motor further comprises: A plurality of stator cores (20) are sequentially arranged along the axial direction of the motor; the air duct structure 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 one stator core (20); and the plate surface of the slot plate (10) provided with the air duct (10a) abuts against the other stator core (20).

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