A low-noise multi-stage axial flow fan

Abstract

The present invention discloses a low-noise multi-stage axial flow fan, including a low-noise multi-stage axial flow fan, including a fan housing, a drive motor, a motor main shaft, an impeller assembly and a guide vane assembly, the fan housing including an outer housing, an inner housing and a sound insulation material layer installed in one piece, the inner housing is assembled from the guide vane shells of each guide vane assembly, the drive motor and the motor main shaft are installed in the guide vane shell located in the middle, the two ends of the motor main shaft pass through each guide vane inner shell, the motor main shaft is connected to each impeller assembly, an air inlet guide cover is installed on the first-stage impeller assembly, a guide vane cover plate is installed on the last-stage guide vane assembly, a continuous airflow channel is formed between each impeller assembly and the guide vane assembly, the drive motor drives the motor main shaft and the impeller assembly to rotate synchronously, and the gas is axially discharged from the air inlet to the air outlet. Compared with conventional fans, the fan of the present invention has stable operation, low noise, long service life, safety, energy saving and high efficiency.

Description

Technical Field

[0001] The invention relates to the field of low-noise fan design, in particular to a low-noise multi-stage axial flow fan. Background Art

[0002] Fans are widely used in industrial and civil fields as a power source. The structure of a multi-stage axial flow fan mainly includes a casing, an impeller and a guide vane. At the fan outlet, the gas and the fan shaft flow in parallel, which is suitable for occasions with high gas flow requirements. Existing axial flow fan products have problems such as high operating noise, low efficiency and high maintenance cost due to imperfect size and structural design, and their performance needs to be improved urgently. Summary of the invention

[0003] In order to solve the deficiencies of the prior art, the present invention provides a low-noise multi-stage axial flow fan, which not only has stable operation and low noise, but also has the excellent performance of long service life, safety, energy saving and high efficiency.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: A low-noise multi-stage axial flow fan, comprising a fan housing, a drive motor, a motor shaft, an impeller assembly and a guide vane assembly, wherein the number of the impeller assembly and the guide vane assembly is more than two, the impeller assembly comprises an impeller housing and impeller blades, the guide vane assembly comprises a guide vane inner shell, guide vane blades and a guide vane outer shell, the fan housing comprises an outer shell, an inner shell and a sound insulation material layer which are integrally installed, the inner shell is assembled from the guide vane outer shells of each guide vane assembly, the drive motor and the motor shaft are installed in the guide vane outer shell located in the middle, both ends of the motor shaft pass through each guide vane inner shell, the motor shaft is connected to each impeller assembly, an air inlet guide cover is installed on the first-stage impeller assembly, a guide vane cover plate is installed on the last-stage guide vane assembly, a continuous airflow channel is formed between each impeller assembly and the guide vane assembly, the drive motor drives the motor shaft and the impeller assembly to rotate synchronously, so as to realize the axial outflow of gas from the air inlet to the air outlet.

[0005] There are five impeller assemblies and guide vane assemblies. The impeller assemblies are divided into a first-stage impeller, a second-stage impeller, a third-stage impeller, a fourth-stage impeller, and a fifth-stage impeller. The guide vane assemblies are divided into a first-stage guide vane, a second-stage guide vane, a third-stage guide vane, a fourth-stage guide vane, and a fifth-stage guide vane. The impeller assemblies and guide vane assemblies are arranged in sequence along the length direction of the motor main shaft.

[0006] The blades of the impeller assembly have the same structure and size, the blades of the guide vane assembly have the same structure and size, and the blades of the guide vane assembly are C-shaped.

[0007] Preferably, the maximum diameter D of the air inlet guide cover is 120-240 mm, the axial distance L of the air inlet guide cover is 30-45 mm, the outer edge diameter D of each impeller blade is 240-360 mm, the outer wall diameter d of each impeller housing is 120-240 mm, the axial distance L of each impeller housing is 35-50 mm, the number of blades of each impeller assembly is 5-20, the blade inlet angle β1 of each impeller blade is: 20°≤β1≤90°, the blade outlet angle β2 of each impeller blade is: 20°≤β2≤90°, and the blade wrap angle θ of each impeller blade is: 0°≤θ≤90°; The outer edge diameter of each guide vane blade is D=242-362mm, the outer wall diameter of each guide vane inner shell is d=120-240mm, the axial distance of the guide vane inner shell for installing the motor is L=100-130mm, the axial distance of other guide vane inner shells is L=40-60mm, the number of guide vane blades in each guide vane assembly is 10-30, the blade inlet angle β1 of each guide vane blade is: 100°≤β1≤170°, the blade outlet angle β2 of each guide vane blade is: 20°≤β2≤90°, and the blade wrap angle θ of each guide vane blade is: 0°≤θ≤90°.

[0008] A bearing assembly is installed on at least one guide vane assembly located on the left and / or right side, and the motor main shaft is movably installed in the bearing assembly. The bearing assembly includes a deep groove ball bearing, a bearing end cover and a wave spring. The deep groove ball bearing is embedded in the middle of the guide vane inner shell, and wave springs and bearing end covers are installed on both sides of the deep groove ball bearing. The bearing end cover is fixed to the guide vane inner shell by a bolt assembly.

[0009] Guide vane connecting parts are formed on both sides of the guide vane outer shell of each guide vane assembly, and adjacent guide vane outer shells are fixed together by bolt assemblies. The guide vane assembly for installing the drive motor is provided with a motor mounting part on the guide vane inner shell, and the guide vane assembly for installing the bearing assembly is provided with a bearing mounting part on the guide vane inner shell.

[0010] The motor main shaft is equipped with an end face round nut and an intermediate round nut, and a shaft sleeve group is arranged between adjacent impeller assemblies and guide vane assemblies on the motor main shaft, so that the positions of various components on the main shaft are stable and the operation efficiency of the device is improved.

[0011] An annular outer shell layer is installed on the outer shell body, and outer partitions are installed horizontally and vertically on the outer wall of the outer shell body. An outer sound insulation material layer is arranged between the outer wall of the outer shell body and the annular outer shell layer. An annular inner shell layer is installed on the inner shell body, and an inner sound insulation material layer is installed between the outer wall of the annular inner shell layer and the inner wall of the outer shell body. An inner partition is installed horizontally on the outer wall of the inner shell body, and a damping material layer is installed between the outer wall of the inner shell body and the annular inner shell layer. The sound insulation material is sound insulation cotton, and the damping material is made of rubber, resin and other materials to make the shell structure stable and enhance the sound insulation effect.

[0012] Preferably, the thickness of the annular outer shell layer is S=0.5-2mm, the main body thickness of the outer shell is S=2-8mm, the length of the outer shell is L=460-690mm, the thickness of the outer sound insulation material layer is S=10-30mm, and the length of the outer sound insulation material layer is L=455-670mm; the thickness of the inner sound insulation material layer is S=10-40mm, and the length of the inner sound insulation material layer is L=455-670mm, the thickness of the annular inner shell layer is S=0.5-2mm, the thickness of the damping material layer is 10-30mm, the main body thickness of the inner shell is S=2-8mm, the length of the inner shell is L=460-675mm, and the inner wall diameter of the inner shell is D=242-362mm.

[0013] The outer shell has a base at the bottom, two lifting rings are installed on the top of the outer shell, and a motor connection port is installed in the middle of the top, outer ring plates are arranged on both sides of the inner shell, inner connecting rings are installed above the outer ring plates, and end disks are arranged on the outer side of the outer ring plates, and the end disks are installed on the outer shell by bolt assemblies to fix the outer ring plates, the inner connecting rings and the inner shell as a whole, and two end flanges are installed on both sides of the outer shell, and the end flanges are installed on the outer shell by bolt assemblies to fix the end disks and the inner shell as a whole.

[0014] The present invention has the following beneficial effects: 1. Two sound insulation layers and a damping material layer are arranged between the inner and outer shells of the fan of the present invention, which significantly enhances the sound insulation effect. The inner and outer shells are both made of thin-walled metal plates with good heat dissipation. The inner and outer shells and the end face flange are installed as one through the end face disc, the outer annular plate and the inner connecting ring. The structure is firm, safe and reliable. 2. The fan of the present invention adopts a modular and integrated design. The inner casing is installed by assembling and fastening multiple guide vane shells. The impeller is installed in the shell of the guide vane of the same level. It is more convenient to manufacture and assemble, with a compact structure, small size, beautiful and durable. The number of guide vanes and impellers can be set as needed and the parameters can be optimized to meet different product specifications and design requirements. 3. The present invention adopts a one-motor-multiple-impeller mode, reasonably uses the best range of motor operation, is easy to control, reduces energy consumption and cost, and when the total pressure and flow of the fan remain unchanged, the total pressure shared by each stage of the multi-stage impeller is smaller, and the circumferential speed of each stage of the impeller is reduced, thereby reducing the absolute speed inside the fan and reducing the fan noise. In addition, the structure design of the guide cover, impeller and guide vane of the present invention is reasonable and has high working efficiency; 4. The drive motor of the present invention has a heat dissipation structure, there is a gap between adjacent impellers and guide vanes, there is an air flow channel or air flow hole in the inner shell of the guide vane, there is a pressure difference between the inlet and outlet sides of the guide vanes at each level, and an air flow microcirculation is formed inside the fan, which is beneficial to the heat dissipation of components such as motors and bearings, has a long service life, and has low operating noise; 5. The fan of the present invention ensures the stability of the rotation of the main shaft driven by the motor by installing bearings on the guide vanes, and reduces the axial movement of the main shaft during operation by installing wave springs and configuring multiple pairs of round nuts, thereby reducing noise and having good reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A front perspective view of a low-noise multi-stage axial flow fan according to the present invention; Figure 2 A rear perspective view of a low-noise multi-stage axial flow fan according to the present invention; Figure 3 A cross-sectional view of a low-noise multi-stage axial flow fan of the present invention; Figure 4 This is a structural diagram of the fan of the present invention without the annular outer shell layer; Figure 5 The structure diagram of the outer shell of the fan of the present invention; Figure 6 The structure diagram of the inner casing, impeller and guide vane of the fan of the present invention; Figure 7 This is a structural diagram of the inner casing of the fan of the present invention after the annular inner shell layer is removed; Figure 8 It is a cross-sectional view of the inner casing, impeller and guide vane of the fan of the present invention; Fig. 9 The structure diagram of the five-stage impeller and the driving motor of the fan of the present invention; Fig.10 It is a structural diagram of a first-stage impeller of the fan of the present invention; Fig.11 The structure diagram of the primary guide vane (bearing guide vane) of the fan of the present invention; Fig.12 It is a structural diagram of the secondary guide vanes (motor guide vanes) of the fan of the present invention; Fig.13 A comparison diagram of pressure curves of the blower of the present invention and a conventional blower; In the figure: 1-annular outer shell layer, 2-base, 3-end flange, 4-lifting ring, 5-motor wiring port, 6-impeller assembly, 7-guide vane assembly, 8-outer shell, 9-outer partition, 10-outer sound insulation material layer, 11-step mounting surface, 12-end disc, 13-outer annular plate, 14-inner shell, 15-annular inner shell layer, 16-inner partition, 17-damping material layer, 18-inner connecting ring, 19-end round nut, 20-deep groove ball bearing, 21-bearing end cover, 22-wave spring, 23-middle round nut, 24-drive Motor, 25-motor main shaft, 26-shaft sleeve assembly, 30-end face flange connection; 6a-first-stage impeller, 6b-second-stage impeller, 6c-third-stage impeller, 6d-fourth-stage impeller, 6e-fifth-stage impeller, 60-air inlet guide cover, 61-impeller blades, 7a-first-stage guide vanes, 7b-second-stage guide vanes, 7c-third-stage guide vanes, 7d-fourth-stage guide vanes, 7e-fifth-stage guide vanes, 70-guide vane housing, 71-guide vane connection, 72-guide vane blades, 73-guide vane inner housing, 74-bearing mounting portion, 75-motor mounting portion, 76-guide vane cover plate. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: like Figures 1 to 4 As shown, a low-noise multi-stage axial flow fan provided by the present invention includes a fan housing, a drive motor 24, a motor main shaft 25, an impeller assembly 6 and a guide vane assembly 7, wherein the number of the impeller assembly 6 and the guide vane assembly 7 is more than two, the number of the drive motor 24 and the motor main shaft 25 is one, the impeller assembly 6 includes an impeller housing and an impeller blade 61, the guide vane assembly 7 includes a guide vane inner shell 73, a guide vane blade 72 and a guide vane outer shell 70, the fan housing includes an outer shell 8, an inner shell 14 and a sound insulation material layer installed integrally, and the inner shell 14 is composed of each guide vane assembly 7 The guide vane housing 70 is assembled, the drive motor 24 and the motor main shaft 25 are installed in the guide vane housing 70 located in the middle, both ends of the motor main shaft 25 pass through each guide vane inner shell 73, the motor main shaft 25 is connected to each impeller assembly 6, an air inlet guide cover 60 is installed on the first-stage impeller assembly, and a guide vane cover plate 76 is installed on the last-stage guide vane assembly. A continuous airflow channel is formed between each impeller assembly 6 and the guide vane assembly 7, and the drive motor 24 drives the motor main shaft 25 and the impeller assembly 6 to rotate synchronously to realize the horizontal axial outflow of gas from the air inlet to the air outlet.

[0017] Specifically, Figures 9 to 12As shown, the impeller assembly 6 and the guide vane assembly 7 are set to five, the impeller assembly 6 is divided into a first-stage impeller 6a, a second-stage impeller 6b, a third-stage impeller 6c, a fourth-stage impeller 6d, and a fifth-stage impeller 6e, and the guide vane assembly 7 is divided into a first-stage guide vane 7a, a second-stage guide vane 7b, a third-stage guide vane 7c, a fourth-stage guide vane 7d, and a fifth-stage guide vane 7e, and each impeller assembly 6 and guide vane assembly 7 is arranged in sequence along the length direction of the motor main shaft 25.

[0018] The blades of the impeller assembly 6 have the same structure and size, and the blades of the guide vane assembly 7 have the same structure and size. The blades of the guide vane assembly 7 are of C-shaped structure. The number of blades of the impeller assembly 6 and the guide vane assembly 7 can be set as required. The blades of the impeller assembly 6 and the guide vane assembly 7 are prime numbers to each other and are staggered. There is a gap between adjacent impeller assemblies 6 and guide vane assemblies 7. An airflow channel or airflow holes are provided in the guide vane inner shell 73, so as to realize standardized production, reduce costs, and have beautiful appearance, durability and high working efficiency.

[0019] The first-stage guide vane 7a assembly 7 located on the left and the fourth-stage guide vane 7d assembly 7 located on the right are installed with bearing assemblies, and the motor main shaft 25 is movably installed in the bearing assemblies to enhance the supporting effect on the main shaft and the impeller assembly 6 installed thereon.

[0020] like Figure 3 , Figure 8 As shown, the bearing assembly includes a deep groove ball bearing 20, a bearing end cover 21 and a wave spring 22. The deep groove ball bearing 20 is embedded in the middle of the guide vane inner shell 73, and the wave spring 22 and the bearing end cover 21 are installed on both sides of the deep groove ball bearing 20. The bearing end cover 21 is fixed to the guide vane inner shell 73 by a bolt assembly, which is easy to install and stable and reliable.

[0021] like Fig.11 , Fig.12 As shown, guide vane connecting parts 71 are formed on both sides of the guide vane outer shell 70 of each guide vane assembly 7, and adjacent guide vane outer shells 70 are fixed as a whole by a bolt assembly. The guide vane assembly 7 for installing the drive motor 24 is provided with a motor mounting part 75 on the guide vane inner shell 73, and the guide vane assembly 7 for installing the bearing assembly is provided with a bearing mounting part 74 on the guide vane inner shell 73, which is easy to install and has a stable structure.

[0022] like Figures 3 to 8 As shown, the motor main shaft 25 is installed with an end round nut 19 and an intermediate round nut 23. The setting of the round nut can withstand a large axial force, improve the position stability through the locking component, and improve the operating efficiency and service life of the device. In addition, a shaft sleeve group 26 is arranged between the adjacent impeller assemblies 6 and guide vane assemblies 7 on the motor main shaft 25 to improve the axial position stability of each motor component.

[0023] An annular outer shell layer 1 is installed on the outer shell body 8, and outer partitions 9 are installed horizontally and vertically on the outer wall of the outer shell body 8. An outer sound insulation material layer 10 is arranged between the outer wall of the outer shell body 8 and the annular outer shell layer 1. An annular inner shell layer 15 is installed on the inner shell body 14, and an inner sound insulation material layer is installed between the outer wall of the annular inner shell layer 15 and the inner wall of the outer shell body 8. An inner partition 16 is installed horizontally on the outer wall of the inner shell body 14, and a damping material layer 17 is installed between the outer wall of the inner shell body 14 and the annular inner shell layer 15. The partition increases the structural strength of the shell body. The damping material layer 17 and the double-layer sound insulation cotton are arranged to ensure a good sound insulation effect of the shell body.

[0024] like Figure 1 , Figure 2 As shown, the bottom of the outer shell 8 has a base 2, the top of the outer shell 8 is equipped with two hanging rings 4, and the middle of the top is equipped with a motor connection port 5, the structure is firm, and it is convenient to install and use.

[0025] like Figures 3 to 8 As shown, outer annular plates 13 are arranged on both sides of the inner shell 14, inner connecting rings 18 are installed above the outer annular plates 13, and end discs 12 are also arranged on the outer side of the outer annular plates 13. The end discs 12 are installed on the outer shell 8 through bolt assemblies and fix the outer annular plates 13, the inner connecting rings 18 and the inner shell 14 as a whole, which is not only convenient to install and has a stable structure, but also convenient for adding and replacing damping materials and sound insulation cotton.

[0026] Two end flanges 3 are installed on both sides of the outer shell 8. The end flanges 3 are installed on the outer shell 8 through bolt assemblies and fix the end disc 12 and the inner shell 14 as a whole. The end flanges 3 have high structural strength and can improve the applicability of the fan by realizing fan combination or connection with external pipelines.

[0027] like Figure 5 As shown, the outer shell 8 has an end face flange connection part 30, the end face flange 3 is aligned with the end face flange connection part 30 and is fastened and installed by a bolt assembly, an annular step mounting surface 11 is provided on the end face flange connection part 30, and the outer peripheral edge of the end face disc 12 is embedded in the step mounting surface 11, so that the surface of the end face disc 12 is flush with the surface of the end face flange connection part 30, which has the effects of convenient installation, beautiful appearance and durability.

[0028] At the same time, in order to improve the efficiency of the fan, the parameters of the low-noise multi-stage axial flow fan of the present invention meet the following conditions: Parameters of annular outer shell layer, outer shell body, and outer sound insulation material layer: annular outer shell layer 1 thickness S=0.5-2mm, outer shell body 8 main body thickness S=2-8mm, outer shell body 8 length L=460-690mm, outer sound insulation material layer 10 thickness S=10-30mm, outer sound insulation material layer 10 length L=455-670mm; Parameters of inner sound insulation material layer, annular inner shell layer, inner shell, and damping material layer: thickness of inner sound insulation material layer S=10-40mm, length of inner sound insulation material layer L=455-670mm, thickness of annular inner shell layer 15 S=0.5-2mm, thickness of damping material layer 17 10-30mm, main body thickness of inner shell 14 S=2-8mm, length of inner shell 14 L=460-675mm, inner wall diameter of inner shell 14 D=242-362mm; Air inlet guide shield parameters: the maximum diameter D of the air inlet guide shield 60 is 120-240 mm, and the axial distance L of the air inlet guide shield 60 is 30-45 mm; Impeller parameters at each level: outer edge diameter of impeller blade 61 D=240-360mm, outer wall diameter of impeller housing d=120-240mm, axial distance of impeller housing L=35-50mm, number of blades of impeller at each level is 5-20, blade inlet angle β1 of impeller blade 61 is: 20°≤β1≤90°, blade outlet angle β2 of impeller blade 61 is: 20°≤β2≤90°, blade wrap angle θ of impeller blade 61 is: 0°≤θ≤90°; Guide vane parameters of each level: outer edge diameter D of the guide vane blade 72 = 242-362 mm, outer wall diameter d of the guide vane inner shell 73 = 120-240 mm, axial distance L of the guide vane inner shell 73 for installing the motor = 100-130 mm, axial distance L of other guide vane inner shells 73 = 40-60 mm, the number of guide vane blades 72 at each level is 10-30, the blade inlet angle β1 of the guide vane blade 72 is: 100°≤β1≤170°, the blade outlet angle β2 of the guide vane blade 72 is: 20°≤β2≤90°, and the blade wrap angle θ of the guide vane blade 72 is: 0°≤θ≤90°.

[0029] It is understandable that the design dimensions of the fan of the present invention can be calculated dimensionlessly, and the same technical effect can be achieved when the parameter values ​​are proportionally reduced or proportionally increased.

[0030] Embodiment 1: Embodiment 1 is the above-mentioned five-stage axial flow fan, the structure and size of each impeller are the same, the first and fourth stages are bearing guide vanes with the same structure, the second stage is the motor guide vane, the third and fifth stages are hollow guide vanes, the structure and size of each guide vane are basically the same, but the length of the motor guide vane is greater than that of other guide vanes, and the following parameters are further adopted: Parameters of the annular outer shell layer, outer shell body, and outer sound insulation material layer: the thickness of the annular outer shell layer 1 is S=1mm, the main body thickness of the outer shell body 8 is S=5mm, the length of the outer shell body 8 is L=567mm, the thickness of the outer sound insulation material layer 10 is S=20mm, and the length of the outer sound insulation material layer 10 is L=551mm; Parameters of the inner sound insulation material layer, annular inner shell layer, inner shell, and damping material layer: thickness of the inner sound insulation material layer S=30mm, length of the inner sound insulation material layer L=551mm, thickness of the annular inner shell layer 15 S=1mm, thickness of the damping material layer 17 16mm, main body thickness of the inner shell 14 S=6mm, length of the inner shell 14 L=553mm, inner wall diameter of the inner shell 14 D=301mm; Air inlet guide shield parameters: the maximum diameter D of the air inlet guide shield 60 is 153 mm, and the axial distance L of the air inlet guide shield 60 is 36 mm; The parameters of the first-stage impeller are as follows: the outer edge diameter of the first-stage impeller 6a is D=300mm, the outer wall diameter of the first-stage impeller 6a shell is d=153mm, the axial distance of the first-stage impeller 6a is L=43mm, the number of blades of the first-stage impeller 6a is 14, the blade inlet angle β1 of the first-stage impeller 6a is 25°, the blade outlet angle β2 of the first-stage impeller 6a is 50°, and the blade wrap angle θ of the first-stage impeller 6a is 40°; The parameters of the first-stage guide vane are as follows: the outer edge diameter D of the first-stage guide vane 7a blade 72 is 301 mm, the outer wall diameter d of the guide vane inner shell 73 of the first-stage guide vane 7a is 153 mm, the axial distance L of the guide vane inner shell 73 of the first-stage guide vane 7a is 52 mm, the number of the first-stage guide vane 7a blade 72 is 17, the blade inlet angle β1 of the first-stage guide vane 7a blade 72 is 160°, the blade outlet angle β2 of the first-stage guide vane 7a blade 72 is 80°, and the blade wrap angle θ of the first-stage guide vane 7a blade 72 is 3°; Impeller parameters for the second to fifth stages: the same as the first stage impeller 6a; Secondary guide vane parameters: The axial distance L of the guide vane inner shell 73 of the secondary guide vane 7b is 116 mm, and the other designs are the same as those of the primary guide vane 7a; Parameters of guide vanes of stages 3 to 5: same as those of stage 1 impeller 6a.

[0031] After the fan test, Fig.13 As shown, compared with conventional fans with the same flow rate, the fan of the present invention has higher pressure and better fan efficiency. The noise of the conventional fan is 82dB, while the noise of the fan of the present invention is 64dB, and the operating noise is also significantly reduced.

[0032] It should be noted that the above embodiments are merely preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. All equivalent modifications made on the basis of the above embodiments belong to the protection scope of the present invention.

Claims

1. A low-noise multi-stage axial flow fan, comprising a fan housing, a drive motor, a motor main shaft, an impeller assembly and a guide vane assembly, characterized in that: There are more than two impeller assemblies and guide vane assemblies. The impeller assembly includes an impeller housing and impeller blades. The guide vane assembly includes a guide vane inner housing, guide vane blades and a guide vane outer housing. The fan housing includes an outer housing, an inner housing and a sound insulation material layer that are integrally installed. The inner housing is assembled from the guide vane outer housings of each guide vane assembly. The drive motor and the motor main shaft are installed in the guide vane outer housing located in the middle. Both ends of the motor main shaft pass through each guide vane inner housing. The motor main shaft is connected to each impeller assembly. An air inlet guide cover is installed on the first-stage impeller assembly, and a guide vane cover plate is installed on the last-stage guide vane assembly. A continuous airflow channel is formed between each impeller assembly and the guide vane assembly. The drive motor drives the motor main shaft and the impeller assembly to rotate synchronously to achieve axial outflow of gas from the air inlet to the air outlet.

2. A low-noise multi-stage axial flow fan according to claim 1, characterized in that: There are five impeller assemblies and guide vane assemblies. The impeller assemblies are divided into a first-stage impeller, a second-stage impeller, a third-stage impeller, a fourth-stage impeller, and a fifth-stage impeller. The guide vane assemblies are divided into a first-stage guide vane, a second-stage guide vane, a third-stage guide vane, a fourth-stage guide vane, and a fifth-stage guide vane. The impeller assemblies and guide vane assemblies are arranged in sequence along the length direction of the motor main shaft.

3. A low-noise multi-stage axial flow fan according to claim 1, characterized in that: The blades of the impeller assembly have the same structure and size, the blades of the guide vane assembly have the same structure and size, and the blades of the guide vane assembly are C-shaped.

4. A low-noise multi-stage axial flow fan according to claim 1, characterized in that: The maximum diameter of the air inlet guide cover is D=120-240mm, the axial distance of the air inlet guide cover is L=30-45mm, the outer edge diameter of each impeller blade is D=240-360mm, the outer wall diameter of each impeller housing is d=120-240mm, the axial distance of each impeller housing is L=35-50mm, the number of blades of each impeller assembly is 5-20, the blade inlet angle β1 of each impeller blade is: 20°≤β1≤90°, the blade outlet angle β2 of each impeller blade is: 20°≤β2≤90°, and the blade wrap angle θ of each impeller blade is: 0°≤θ≤90°; The outer edge diameter of each guide vane blade is D=242-362mm, the outer wall diameter of each guide vane inner shell is d=120-240mm, the axial distance of the guide vane inner shell for installing the motor is L=100-130mm, the axial distance of other guide vane inner shells is L=40-60mm, the number of guide vane blades in each guide vane assembly is 10-30, the blade inlet angle β1 of each guide vane blade is: 100°≤β1≤170°, the blade outlet angle β2 of each guide vane blade is: 20°≤β2≤90°, and the blade wrap angle θ of each guide vane blade is: 0°≤θ≤90°.

5. The low-noise multi-stage axial flow fan according to claim 1, characterized in that: A bearing assembly is installed on at least one guide vane assembly located on the left and / or right side, and the motor main shaft is movably installed in the bearing assembly. The bearing assembly includes a deep groove ball bearing, a bearing end cover and a wave spring. The deep groove ball bearing is embedded in the middle of the guide vane inner shell, and wave springs and bearing end covers are installed on both sides of the deep groove ball bearing. The bearing end cover is fixed to the guide vane inner shell by a bolt assembly.

6. A low-noise multi-stage axial flow fan according to claim 5, characterized in that: Guide vane connecting parts are formed on both sides of the guide vane outer shell of each guide vane assembly, and adjacent guide vane outer shells are fixed together by bolt assemblies. The guide vane assembly for installing the drive motor is provided with a motor mounting part on the guide vane inner shell, and the guide vane assembly for installing the bearing assembly is provided with a bearing mounting part on the guide vane inner shell.

7. A low-noise multi-stage axial flow fan according to claim 1, characterized in that: The motor main shaft is provided with an end face round nut and an intermediate round nut, and a shaft sleeve group is provided between adjacent impeller assemblies and guide vane assemblies on the motor main shaft.

8. The low-noise multi-stage axial flow fan according to claim 1, characterized in that: An annular outer shell layer is installed on the outer shell body, and outer partitions are installed horizontally and vertically on the outer wall of the outer shell body. An outer sound insulation material layer is arranged between the outer wall of the outer shell body and the annular outer shell layer. An annular inner shell layer is installed on the inner shell body, and an inner sound insulation material layer is installed between the outer wall of the annular inner shell layer and the inner wall of the outer shell body. An inner partition is installed horizontally on the outer wall of the inner shell body, and a damping material layer is installed between the outer wall of the inner shell body and the annular inner shell layer.

9. A low-noise multi-stage axial flow fan according to claim 8, characterized in that: The thickness of the annular outer shell layer is S=0.5-2mm, the main body thickness of the outer shell body is S=2-8mm, the length of the outer shell body is L=460-690mm, the thickness of the outer sound insulation material layer is S=10-30mm, the length of the outer sound insulation material layer is L=455-670mm; the thickness of the inner sound insulation material layer is S=10-40mm, the length of the inner sound insulation material layer is L=455-670mm, the thickness of the annular inner shell layer is S=0.5-2mm, the thickness of the damping material layer is 10-30mm, the main body thickness of the inner shell body is S=2-8mm, the length of the inner shell body is L=460-675mm, and the inner wall diameter of the inner shell body is D=242-362mm.

10. A low-noise multi-stage axial flow fan according to any one of claims 1 to 9, characterized in that: The outer shell has a base at the bottom, two lifting rings are installed on the top of the outer shell, and a motor connection port is installed in the middle of the top, outer ring plates are arranged on both sides of the inner shell, inner connecting rings are installed above the outer ring plates, and end disks are arranged on the outer side of the outer ring plates, and the end disks are installed on the outer shell by bolt assemblies to fix the outer ring plates, the inner connecting rings and the inner shell as a whole, and two end flanges are installed on both sides of the outer shell, and the end flanges are installed on the outer shell by bolt assemblies to fix the end disks and the inner shell as a whole.

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