Blade for centrifugal fan, double-suction centrifugal impeller using the same, and fan

Abstract

The application provides a blade for a centrifugal fan, a double-suction centrifugal impeller using the blade and a fan, wherein the blade comprises a suction surface wall, a pressure surface wall, a leading edge, a trailing edge, a convex air inlet portion and a concave air outlet portion; the suction surface wall and the pressure surface wall are oppositely arranged and extend firstly along the length direction of the blade and secondly between the leading edge and the trailing edge; the convex air inlet portion is protrusively formed towards the side of the suction surface wall at the leading edge part of the blade, the concave air outlet portion is protrusively formed towards the side of the pressure surface wall at the trailing edge part of the blade, and in the direction from the leading edge to the trailing edge, the convex air inlet portion and the concave air outlet portion are connected; in the length direction of the blade, the convex air inlet portion presents a structure of high in the middle and low at both sides, and the concave air outlet portion presents a structure of low in the middle and high at both sides; in the direction from the leading edge to the trailing edge, the middle height of the convex air inlet portion presents a decreasing trend; in the direction from the trailing edge to the leading edge, the middle height of the concave air outlet portion presents a decreasing trend.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of centrifugal fan, in particular to a blade for centrifugal fan, a double-suction centrifugal impeller and a fan applying the blade. BACKGROUND

[0002] The centrifugal fan is a machine that relies on input mechanical energy to increase gas pressure and discharge gas, and it is a driven fluid machine. The working principle is that the relative rotation of the impeller in the fan volute produces centrifugal force to compress and transport gas, and converts the mechanical energy of the fan into kinetic energy and potential energy of the gas.

[0003] The centrifugal fan can be divided into single-suction and double-suction types according to the number of suction inlets of the impeller. Among them, the double-suction centrifugal fan adopts a single-shaft double-support structure. Since it has two separate air inlet boxes and a double-sided suction impeller structure, it can not only offset the axial force of the impeller, but also evenly wear the bearings at both ends, and run stably and reliably. The flow coefficient of the double-suction fan is larger, and it can provide larger gas flow than the single-suction fan, and is suitable for many industries that require large gas flow. By controlling the rotation speed of the impeller and designing the shape of the blade, the performance of the centrifugal fan and the pressure of the output airflow can be adjusted.

[0004] When the impeller of the traditional centrifugal fan rotates, the airflow between the blades is easily affected by fluid viscosity effect, adverse pressure gradient and Coriolis force, which can cause flow separation and form secondary vortex, resulting in low efficiency of the fan.

[0005] The information disclosed in this BACKGROUND section is only intended to increase an understanding of the general context in which the present application can be practiced. It should not be taken as an acknowledgement that this information is prior art that is widely known as being relevant to the present application. SUMMARY

[0006] The present application aims to solve the technical problems of the prior art, and provides a blade for centrifugal fan, a double-suction centrifugal impeller and a fan applying the blade. The blade is applied to the double-suction centrifugal impeller, which can improve the operating efficiency of the fan.

[0007] To solve the above technical problems, the application discloses a blade for a centrifugal fan, which comprises a suction surface wall, a pressure surface wall, a leading edge, a trailing edge, a convex air inlet portion and a concave air outlet portion. The suction surface wall and the pressure surface wall are oppositely arranged, and both extend along the length direction of the blade firstly and then between the leading edge and the trailing edge. The convex air inlet portion is protrusively formed towards the suction surface wall side at the leading edge part of the blade, and the concave air outlet portion is protrusively formed towards the pressure surface wall side at the trailing edge part of the blade. In the direction from the leading edge to the trailing edge, the convex air inlet portion and the concave air outlet portion are connected.

[0008] In the length direction of the blade, the convex air inlet portion has a structure of high in the middle and low on both sides, and the concave air outlet portion has a structure of low in the middle and high on both sides. In the direction from the leading edge to the trailing edge, the middle height of the convex air inlet portion has a decreasing trend. In the direction from the trailing edge to the leading edge, the middle height of the concave air outlet portion has a decreasing trend.

[0009] Preferably, the shape of any cross-sectional profile of the blade perpendicular to the length direction of the blade is a circular arc shape, the inner arc surface of the blade is the pressure surface wall, the outer arc surface of the blade is the suction surface wall, and the leading edge and the trailing edge are oppositely arranged in the arc length direction of the blade.

[0010] Specifically, the blade is a double-section reverse torsion blade structure, comprising a first torsion blade section and a second torsion blade section connected in sequence along the length direction of the blade, and the torsion direction of the first torsion blade section is opposite to that of the second torsion blade section.

[0011] Specifically, the blade comprises a first end and a second end oppositely arranged along the length direction of the blade, and a junction end between the first end and the second end along the length direction of the blade, wherein the first end is used for connecting with the center disc of the impeller, and the second end is used for connecting with the disc of the impeller.

[0012] The first torsion blade section is formed by torsion of the first end relative to the junction end in a direction opposite to the rotation direction of the blade, and the second torsion blade section is formed by torsion of the second end relative to the junction end in the opposite direction, so that the leading edge part of the first torsion blade section and the leading edge part of the second torsion blade section are gradually protruded towards the outer arc surface of the blade from the first end and the second end respectively towards the junction end to form the convex air inlet portion, and the trailing edge part of the first torsion blade section and the trailing edge part of the second torsion blade section are gradually protruded towards the inner arc surface of the blade from the first end and the second end respectively towards the junction end to form the concave air outlet portion.

[0013] Specifically, the first twisted blade segment comprises a first inner-arc twisted surface and a first outer-arc twisted surface, the second twisted blade segment comprises a second inner-arc twisted surface and a second outer-arc twisted surface, the first inner-arc twisted surface of the first twisted blade segment and the second inner-arc twisted surface of the second twisted blade segment are connected to form a pressure surface wall of the blade, and the first outer-arc twisted surface of the first twisted blade segment and the second outer-arc twisted surface of the second twisted blade segment are connected to form a suction surface wall of the blade.

[0014] Preferably, the first twisted blade segment and the second twisted blade segment have a common twisted axis, and the common twisted axis is parallel to the length direction of the blade.

[0015] Preferably, the first twisted blade segment and the second twisted blade segment have the same size of cross-sectional profile perpendicular to the length direction of the blade.

[0016] Preferably, the cross-sectional profile of the blade perpendicular to the length direction of the blade has a midpoint, and the common twisted axis passes through the midpoint.

[0017] Preferably, the twisted angle of the first twisted blade segment and the second twisted blade segment ranges from 5° to 15°. More preferably, the twisted angle of the first twisted blade segment and the second twisted blade segment is 10°.

[0018] Preferably, the length ratio of the first twisted blade segment and the second twisted blade segment ranges from 0.25 to 1.5. More preferably, the length ratio of the first twisted blade segment and the second twisted blade segment is 1.

[0019] Further, the blade further comprises a notch, the notch is arranged at the trailing edge of the blade and is arranged at the connection between the first twisted blade segment and the second twisted blade segment, and the notch is arranged in the shape of a right-angled triangle.

[0020] The second aspect of the present application discloses a double-suction centrifugal impeller, which comprises a rotation axis, a center disc and a blade for centrifugal fan as described above, wherein a plurality of the blades are arranged, the plurality of the blades are divided into two groups, the two groups of the blades are symmetrically arranged on two sides of the center disc and take the center disc as a symmetric surface. The plurality of the blades in each group are uniformly and spacedly arranged along the circumferential direction of the rotation axis. The length direction of each blade is parallel to the rotation axis, and the leading edge of each blade is closer to the rotation axis of the double-suction centrifugal impeller than the trailing edge.

[0021] Specifically, the impeller comprises a wheel disc, and each group of the blades is respectively connected with a wheel disc on the side away from the center disc along the direction of the rotation axis. Each wheel disc is provided with a wheel disc air inlet.

[0022] The third aspect of the present application discloses a fan, which comprises:

[0023] The double-suction centrifugal impeller as described above;

[0024] The support chassis;

[0025] The driving motor fixedly installed on the top surface of one end of the support chassis;

[0026] The volute fixedly installed on the top surface of the other end of the support chassis, wherein the double-suction centrifugal impeller is arranged in the volute; and the middle disc of the double-suction centrifugal impeller is connected with the impeller rotating shaft;

[0027] The transmission mechanism, wherein the driving motor is connected with the impeller rotating shaft through the transmission mechanism, and the impeller rotating shaft rotates to drive the double-suction centrifugal impeller to rotate around the rotation axis of the double-suction centrifugal impeller.

[0028] Specifically, the volute comprises two oppositely arranged air inlet end plates, an annular plate connected between the two air inlet end plates, and a hollow cavity for accommodating the impeller formed by the two air inlet end plates and the annular plate; the annular plate is provided with a volute air outlet, and the two air inlet end plates are each provided with a volute air inlet, and the volute air outlet and the volute air inlets are each in communication with the hollow cavity.

[0029] Further, the fan further comprises an outer shell, wherein the outer shell covers the volute.

[0030] Specifically, the fan comprises a rotating shaft through hole and a bearing base, wherein the side wall of the outer shell is provided with a rotating shaft through hole, and one end of the impeller rotating shaft that extends out of the outer shell through the rotating shaft through hole is rotatably connected to the outer shell through the bearing base.

[0031] Specifically, the transmission mechanism adopts a transmission belt.

[0032] Advantages:

[0033] 1) The blade for centrifugal fan of the present application, when applied to a double-suction centrifugal impeller, a convex air inlet part is arranged at the front edge part of the blade, which can realize a larger air inlet at the same speed, reduce the separation and vortex of airflow at the front edge of the blade, reduce the flow loss, and improve the efficiency; on the other hand, the convex air inlet part can guide the airflow, so that the airflow enters the working area of the blade more smoothly, and improve the working efficiency and working capacity of the fan; a concave air outlet part is arranged at the rear edge part of the blade, which can increase the air outlet, cooperate with the convex air inlet part, and further improve the efficiency; on the other hand, the concave air outlet part can make the separation point of the airflow move backward, reduce the separation area, reduce the influence of vortex, and at the same time, can guide the airflow to pass through better, reduce the turbulence and energy loss.

[0034] 2) In an embodiment of the present application, a notch structure is arranged at the middle sharp part of the concave air outlet part, which can realize the separation of the accumulated vortex, which is beneficial to reduce the flow resistance, and further improve the efficiency and reduce the noise.

[0035] 3) Compared with the existing centrifugal fan, the fan provided by the present application has the advantages that the driving motor is arranged outside the outer shell, the inner machine including the impeller and the volute is stably arranged inside the outer shell, and the stable cushioning effect is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0036] The above and / or other aspects of the present application will become apparent and more readily appreciated from the following description, taken in conjunction with the accompanying drawings, in which:

[0037] Figure 1 A perspective structural diagram of the impeller provided for the first embodiment of the present application Figure 1 .

[0038] Figure 2 A perspective structural diagram of the impeller provided for the first embodiment of the present application Figure 2 .

[0039] Figure 3 A side view of the impeller shown in Figure 1 along the rotation axis direction after removing the disc.

[0040] Figure 4 A local enlarged view of the A area in Figure 3 .

[0041] Figure 5 A perspective structural diagram of the blade provided for the first embodiment of the present application Figure 1 .

[0042] Figure 6 A perspective structural diagram of the blade provided for the first embodiment of the present application Figure 2 .

[0043] Figure 7 An external structure schematic view of a fan to which the impeller of the first embodiment of the present application is applied is shown.

[0044] Figure 8 A structure schematic view of the impeller provided in the first embodiment of the present application being arranged in a volute is shown.

[0045] Figure 9 A volute profile schematic view of the present application is shown, in which the impeller provided in the first embodiment of the present application is shown.

[0046] Figure 10 A three-dimensional structure schematic view of the impeller provided in the second embodiment of the present application is shown.

[0047] Figure 11 A three-dimensional structure schematic view of the blade provided in the second embodiment of the present application is shown Figure 1 .

[0048] Figure 12 A three-dimensional structure schematic view of the blade provided in the second embodiment of the present application is shown Figure 2 .

[0049] Figure 13 A three-dimensional structure schematic view of the conventional impeller in the first comparative example of the present application is shown.

[0050] Figure 14 A three-dimensional structure schematic view of the single-segment twisted blade impeller provided in the second comparative example of the present application is shown.

[0051] Figure 15 (A) is a velocity vector nephogram of numerical simulation of the impeller provided in the first embodiment of the present application.

[0052] Figure 15 (B) is a velocity vector nephogram of numerical simulation of the impeller provided in the second embodiment of the present application.

[0053] Figure 15 (C) is a velocity vector nephogram of numerical simulation of the impeller provided in the first comparative example of the present application.

[0054] Figure 15 (D) is a velocity vector nephogram of numerical simulation of the impeller provided in the second comparative example of the present application.

[0055] Figure 16 (A) is a local vorticity nephogram of the impeller air inlet end when the blade end portion corresponding to the impeller air inlet end is not chamfered.

[0056] Figure 16 (B) is a local vorticity nephogram of the impeller air inlet end when the blade end portion corresponding to the impeller air inlet end is chamfered.

[0057] Figure 17(A) is a cloud chart of impeller surface vorticity distribution provided for the second embodiment of the present application.

[0058] Figure 17 (B) is a cloud chart of impeller surface vorticity distribution provided for the first comparative example of the present application.

[0059] Figure 18 A photograph of a double suction centrifugal impeller provided for the first embodiment of the present application.

[0060] Figure 19 A photograph of a double suction centrifugal impeller provided for the second embodiment of the present application.

[0061] Figure 20 A photograph of a double suction centrifugal impeller provided for the second embodiment of the present application. Figure 1 .

[0062] Figure 21 A photograph of a double suction centrifugal impeller provided for the second embodiment of the present application. Figure 2 .

[0063] Figure 22 A comparative graph of the relationship between fan efficiency and volumetric flow rate of a centrifugal fan provided for the first embodiment, the second embodiment, the first comparative example and the second comparative example of the present application.

[0064] Figure 23 A comparative graph of the relationship between shaft power and volumetric flow rate of a centrifugal fan provided for the first embodiment, the second embodiment, the first comparative example and the second comparative example of the present application.

[0065] Figure 24 A comparative graph of the relationship between pressure and volumetric flow rate of a centrifugal fan provided for the first embodiment, the second embodiment, the first comparative example and the second comparative example of the present application.

[0066] BRIEF DESCRIPTION OF REFERENCE NUMERALS

[0067] 10. Blade; 101. Suction side wall; 102. Pressure side wall; 103. Leading edge; 104. Trailing edge; 105. Convex inlet portion; 106. Concave outlet portion; 107. First twisted blade segment; 1071. First inner arc twist surface; 1072. First outer arc twist surface; 108. Second twisted blade segment; 1081. Second inner arc twist surface; 1082. Second outer arc twist surface; 109. Intersection end; 110. Shared twist axis; 20. Flow passage; 30. Double-suction centrifugal impeller; 112. First end; 113. Second end; 40. Rotation axis; 50. Disc; 60. Wheel disc; 601. Wheel disc inlet; 70. Fan; 71. Support chassis; 72. Driving motor; 73. Volute; 731. Inlet end plate; 732. Annular plate; 733. Hollow chamber; 734. Volute outlet; 735. Volute inlet; 74. Outer housing; 771. First pulley; 772. Second pulley; 773. Conveyor belt; 111. Notch; 11. Circular-arc straight blade; 12. Single-segment twisted blade. DETAILED DESCRIPTION

[0068] Impeller flow separation and air cross accumulation are two common phenomena in the internal flow process of the impeller. Among them, impeller flow separation refers to the separation of airflow from the surface of the blade in some areas due to changes in airflow velocity or the influence of blade shape, forming vortex or backflow phenomenon. This separation will cause energy loss of airflow, reducing the efficiency of the fan, while air cross accumulation refers to the meeting and accumulation of airflow in different directions in a certain area due to the complex motion of airflow. This phenomenon usually occurs at the outlet of the impeller or in some specific areas inside the impeller. Air cross accumulation may cause uneven airflow, affecting the normal operation of the impeller, and even may cause airflow backflow, affecting the stability of the entire system. There is a close relationship between impeller flow separation and air cross accumulation. Flow separation may cause local airflow velocity to decrease, forming a low-pressure area, which in turn attracts the surrounding airflow to accumulate, forming a cross-accumulation phenomenon. Conversely, air cross accumulation may also cause mutual interference of airflow, exacerbating the degree of flow separation.

[0069] At the same time, flow separation will cause non-uniform velocity and pressure distribution of fluid at the outlet of the impeller, thereby affecting the uniform outflow of airflow. For example, if the airflow separates severely at the outlet of the impeller, high-speed and low-speed regions may be formed at the outlet, causing airflow to flow out unevenly, forming a so-called "jet-wake" flow structure, which reduces the effective flow area and increases the unevenness of the velocity distribution, affecting the flow state at the outlet of the impeller.

[0070] The impeller of the traditional centrifugal fan is prone to flow separation between the blades when rotating, forming secondary vortex and thus leading to low efficiency of the double-suction centrifugal fan.

[0071] Embodiment 1

[0072] Based on this, referring to Figures 1 to 6 The present embodiment discloses a blade for a centrifugal fan, which can be applied to a forward-inclined double-suction centrifugal impeller 30.

[0073] Referring to Figure 4 and Figure 5 The blade 10 comprises a suction surface wall 101, a pressure surface wall 102, a leading edge 103, a trailing edge 104, a convex air inlet portion 105 and a concave air outlet portion 106. The suction surface wall 101 and the pressure surface wall 102 are oppositely arranged and extend along the length direction of the blade 10 firstly and then between the leading edge 103 and the trailing edge 104. The convex air inlet portion 105 is protrusively formed at the leading edge part of the blade 10 towards the side of the suction surface wall 101, and the concave air outlet portion 106 is protrusively formed at the trailing edge part of the blade 10 towards the side of the pressure surface wall 102, and in the direction from the leading edge to the trailing edge, the convex air inlet portion 105 is connected with the concave air outlet portion 106.

[0074] In the length direction of the blade 10, the convex air inlet portion 105 presents a structure of high in the middle and low at both sides, and the concave air outlet portion 106 presents a structure of low in the middle and high at both sides. In the direction from the leading edge to the trailing edge, the middle height of the convex air inlet portion 105 presents a decreasing trend. In the direction from the trailing edge to the leading edge, the middle height of the concave air outlet portion 106 presents a decreasing trend.

[0075] The blade 10 can reduce vortex and turbulence near both sides of the blade 10 close to the disc 60, so that the airflow flows into the convex air inlet portion 105 uniformly, then flows out from the concave air outlet portion 106 through the flow channel 20 between two adjacent blades 10. In this process, the convex air inlet portion 105 can increase the air inlet amount, reduce the separation and vortex of the airflow at the leading edge of the blade 10, reduce the flow loss and improve the efficiency. Meanwhile, the convex air inlet portion 105 can also guide the airflow to enter the working area of the blade 10 more smoothly, thereby improving the working efficiency and working capacity of the fan. The concave air outlet portion 106 can make the separation point of the airflow move backward, reduce the separation area, reduce the influence of the vortex, guide the airflow to pass through better, reduce the turbulence and energy loss, and the convex air inlet portion 105 can increase the air outlet amount, which can greatly improve the efficiency of the fan.

[0076] In an embodiment, referring to Figure 4, the shape of any cross-sectional profile of the blade 10 perpendicular to its own length direction is circular arc shape, the inner arc surface of the blade 10 is the pressure surface wall 102, the outer arc surface of the blade 10 is the suction surface wall 101, and the leading edge 103 and the trailing edge 104 are oppositely arranged in the arc length direction of the blade 10.

[0077] In an embodiment, referring to Figure 5 and Figure 6 , the blade 10 is a double-section reverse torsion blade structure, comprising a first torsion blade section 107 and a second torsion blade section 108 connected in sequence along the length direction of the blade 10, and the torsion direction of the first torsion blade section 107 is opposite to the torsion direction of the second torsion blade section 108.

[0078] Specifically, referring to Figure 5 and Figure 6 , the blade 10 has a first end 112 and a second end 113 oppositely arranged along the length direction of the blade 10, and a junction end 109 between the first end 112 and the second end 113 along the length direction of the blade 10. The first end 112 is used to connect with the hub 50 of the impeller, and the second end 113 is used to connect with the disc 60 of the impeller. The suction surface wall 101 and the pressure surface wall 102 of the blade 10 both extend between the first end 112 and the second end 113, so as to realize the extension of the suction surface wall 101 and the pressure surface wall 102 along the length direction of the blade 10.

[0079] Referring to Figure 5 and Figure 6 , the first end 112 is twisted relative to the junction end 109 in a direction opposite to the rotation direction of the blade, so as to form the above-mentioned first torsion blade section 107 between the first end 112 and the junction end 109. The second end 113 is twisted relative to the junction end 109 in the opposite direction, so as to form the above-mentioned second torsion blade section 108 between the second end 113 and the junction end 109. And thereby realize that the first torsion blade section 107 and the second torsion blade section 108 are connected in sequence along the length direction of the blade 10, and the torsion direction of the first torsion blade section 107 is opposite to the torsion direction of the second torsion blade section 108.

[0080] The leading edge part of the first torsion blade section 107 and the leading edge part of the second torsion blade section 108 respectively protrude from the first end 112 and the second end 113 to the outer arc surface of the blade 10 to form a convex air inlet part 105 towards the junction end 109. The trailing edge part of the first torsion blade section 107 and the trailing edge part of the second torsion blade section 108 respectively protrude from the first end 112 and the second end 113 to the inner arc surface of the blade 10 to form a concave air outlet part 106 towards the junction end 109.

[0081] More specifically, referring to Figure 5 and Figure 6, the first twisted blade segment 107 comprises a first inner-arc twisted surface 1071 and a first outer-arc twisted surface 1072, the second twisted blade segment 108 comprises a second inner-arc twisted surface 1081 and a second outer-arc twisted surface 1082, the first inner-arc twisted surface 1071 of the first twisted blade segment 107 and the second inner-arc twisted surface 1081 of the second twisted blade segment 108 are connected to form a pressure surface wall 102 of the blade 10, and the first outer-arc twisted surface 1072 of the first twisted blade segment 107 and the second outer-arc twisted surface 1082 of the second twisted blade segment 108 are connected to form a suction surface wall 101 of the blade 10.

[0082] In the embodiment, referring to Figure 4 and Figure 5 , the blade 10 comprises a common twisted axis 110, and the first twisted blade segment 107 and the second twisted blade segment 108 have the common twisted axis 110, i.e., are twisted around the common twisted axis 110. The common twisted axis 110 is parallel to the length direction of the blade 10.

[0083] It should be understood that, referring to Figure 4 , in the embodiment, the cross-sectional shape of the first twisted blade segment 107 and the second twisted blade segment 108 perpendicular to the length direction of the blade 10 is circular arc-shaped, so as to realize that the shape of any cross-sectional profile of the blade 10 perpendicular to the length direction of the blade 10 is circular arc-shaped.

[0084] In the embodiment, the cross-sectional size of the first twisted blade segment 107 and the second twisted blade segment 108 perpendicular to the length direction of the blade 10 is consistent. In other words, in the embodiment, the blade 10 is a double-segment reverse twisted blade structure with an invariable cross-section.

[0085] In the embodiment, any cross-sectional profile of the blade 10 perpendicular to the length direction of the blade 10 has a midpoint M, and the common twisted axis 110 passes through the midpoint M.

[0086] Preferably, the twist angle of the first twisted blade segment 107 and the second twisted blade segment 108 is in the range of 5° to 15°. More preferably, referring to Figure 6 , the twist angle of the first twisted blade segment 107 and the second twisted blade segment 108 is 10°.

[0087] Preferably, in the length direction of the blade 10, the length ratio of the first twisted blade segment 107 and the second twisted blade segment 108 is in the range of 0.25 to 1.5. More preferably, referring to Figure 6 , the length ratio of the first twisted blade segment 107 and the second twisted blade segment 108 is 1.

[0088] Optionally, the blade 10 of the embodiment can be formed by stamping and twisting a straight-plate single-circular-arc sheet metal structure.

[0089] Referring to Figure 1 and Figure 2 The embodiment also provides a double-suction centrifugal impeller 30, comprising the blade 10, the rotation axis 40 and the middle disc 50 as described above, and the middle disc 50 is used for being connected with an external driving motor 72. The blade 10 is provided with a plurality of blades 10, and the plurality of blades 10 are divided into two groups and symmetrically arranged with the middle disc 50 as a symmetric surface. The plurality of blades 10 in each group are uniformly and spacedly arranged along the circumferential direction of the rotation axis 40, and the length direction of each blade 10 is parallel to the rotation axis 40. The leading edge 103 of each blade 10 is closer to the rotation axis 40 of the double-suction centrifugal impeller than the trailing edge 104.

[0090] The embodiment is connected with the output end of the external driving motor 72 through the middle disc 50, so that the driving force applied to the impeller by the driving motor 72 is located at the middle part of the impeller in the axial direction, thereby making the rotation process of the impeller have better overall balance.

[0091] In the embodiment, referring to Figure 1 The double-suction centrifugal impeller 30 comprises a wheel disc 60, and each group of blades 10 is connected with a wheel disc 60 on the side away from the middle disc 50 along the direction of the rotation axis 40. Each wheel disc 60 is provided with a wheel disc air inlet 601. External airflow flows to the leading edge 103 of each blade 10 through the wheel disc air inlet 601. Each wheel disc air inlet 601 corresponds to the air inlet end of the double-suction centrifugal impeller.

[0092] In the embodiment, each group of blades 10 is stably supported by the corresponding side wheel disc 60 and the middle disc 50, so that the impeller has high structural strength.

[0093] Referring to Figure 7 The embodiment also provides a fan 70, which comprises the double-suction centrifugal impeller 30, the support base 71, the driving motor 72, the volute 73 and the transmission mechanism as described above. The driving motor 72 is fixedly installed on the top surface of one end of the support base 71. The volute 73 is fixedly installed on the top surface of the other end of the support base 71, and the impeller is arranged in the volute 73. The middle disc 50 of the impeller is fixedly connected with an impeller rotating shaft 501. The power of the driving motor 72 is transmitted to the impeller rotating shaft 501 through the transmission mechanism, and the impeller rotating shaft 501 rotates to drive the impeller to rotate around the rotation axis 40 of the impeller.

[0094] Specifically, the support base 71 is positioned and connected by a shared connecting block.

[0095] Specifically, referring to Figure 8The volute 73 comprises two air inlet end plates 731 arranged oppositely, an annular plate 732 connected between the two air inlet end plates 731, and a hollow cavity 733 formed by the two air inlet end plates 731 and the annular plate 732 for accommodating the impeller. The annular plate 732 is provided with a volute air outlet 734, and each of the two air inlet end plates 731 is provided with a volute air inlet 735. The volute air outlet 734 and each volute air inlet 735 are in communication with the hollow cavity 733.

[0096] Specifically, referring to Figure 7 , the fan 70 further comprises an outer shell 74 covering the volute 73.

[0097] Specifically, the outer shell 74 is fixed on the support base 71 by screwing. The top surface of the support base 71 is provided with a 28-type steel motor foot, and the driving motor 72 is stably fixed on the 28-type steel motor foot by a hexagonal bolt and a hexagonal nut. A 25GB / T95-2002 flat washer and a 25GB / T93-1987 standard elastic washer are arranged between the hexagonal bolt and the hexagonal nut.

[0098] Specifically, referring to Figure 7 , the fan 70 comprises a rotating shaft through hole and a bearing base. The side wall of the outer shell 74 is provided with the rotating shaft through hole, and one end of the impeller rotating shaft 501 extends out of the outer shell 74 through the rotating shaft through hole and is rotatably connected to the outer shell 74 through the bearing base.

[0099] Specifically, the transmission mechanism adopts a belt transmission.

[0100] Specifically, referring to Figure 7 , the transmission mechanism comprises a first pulley 771, a second pulley 772 and a transmission belt 773. The first pulley 771 is connected to the output shaft of the driving motor 72, the second pulley 772 is connected to the impeller rotating shaft 501, and the first pulley 771 and the second pulley 772 are connected by the transmission belt 773. When the driving motor 72 is turned on, the driving motor 72 drives the first pulley 771, and then drives the transmission belt and the second pulley. The second pulley 772 drives the impeller rotating shaft 501 to rotate, and finally drives the impeller to rotate, achieving the effect of air extraction.

[0101] Embodiment 2

[0102] Based on the embodiment 1, referring to Figure 11 and Figure 12 , the blade 10 in the embodiment further comprises a notch 111 arranged at the trailing edge 104 of the blade 10 and provided at the connection between the first twisted blade segment 107 and the second twisted blade segment 108.

[0103] In this embodiment, a notch 111 is provided at the position of the trailing edge 104 of the blade 10 at the connection between the first twisted blade segment 107 and the second twisted blade segment 108. The notch 111 can reduce the accumulation of airflow at the middle tip of the recessed air outlet 106 of the blade 10. The notch 111 disperses the airflow and realizes the separation of the accumulated vortex, which is beneficial to reduce flow resistance, improve the efficiency of the fan, and reduce noise.

[0104] In this embodiment, the notch 111 is arranged in the form of a right-angled triangle. Specifically, the side lengths of this right-angled triangle are as follows: And 4mm. The vertex angle of the right triangle is located at the intersection point 109.

[0105] See Figure 10 This embodiment also provides a fan 70 that uses a double-suction centrifugal impeller 30 with blades 10 applied in this embodiment.

[0106] In this embodiment, see Figure 10 The leading edge of blade 10 has a rounded corner at the end corresponding to the impeller inlet. Preferably, the rounded corner radius is 10mm. This structure can increase the inlet flow of the air inlet, eliminate the vortex generated by the blade tip, and reduce inlet energy loss and noise. Figure 16 The image shows the local vorticity cloud map of the impeller with and without chamfering at the leading edge side of blade 10 corresponding to the impeller inlet. It can be seen that continuous vorticity appears near the impeller without chamfering, and the effect of vorticity dispersion is not achieved. However, after rounding, there is no continuous vorticity, but rather a dispersed state.

[0107] Comparative Example 1

[0108] Unlike Example 1, the prototype fan 70 of this comparative example uses a conventional impeller, the shape of which is shown in [reference needed]. Figure 13 The blades in this conventional impeller are straight, untwisted, arc-shaped blades 11. Apart from the blades, the other structural parameters of the fan 70 in this embodiment are the same as those in the fan of Embodiment 1.

[0109] Comparative Example 2

[0110] The fan 70 in this comparative example uses a single-stage torsion blade impeller, the shape of which is shown in [reference needed]. Figure 14 The single-segment torsion blade 12 is formed by twisting the end of the arc-shaped straight blade 11 used to connect the middle disk 50 relative to the other end of the single-segment torsion blade 12 used to connect the wheel disk 60. The torsion axis of the single-segment torsion blade 12 passes through the midpoint of the cross-sectional profile of the arc-shaped straight blade 11 perpendicular to the length direction and is parallel to the length direction of the arc-shaped straight blade 11.

[0111] See Figure 14The front edge portion of the single-stage twisted blade 12 gradually protrudes to the outer camber of the single-stage twisted blade 12 from the other end portion for connecting the wheel disc 60 to the end portion for connecting the middle disc 50.

[0112] In addition to the blade, the other structural parameters of the fan 70 of the embodiment are the same as the corresponding structural parameters of the fan of Embodiment 1. Figure 9 A schematic view of the volute profile adopted by the present application is shown, showing the impeller provided by the first embodiment. The volute profile is prior art, and thus is not described here. The main structural parameters of the volute profile are: R1 is 354.44 mm, R2 is 414.06 mm, R3 is 473.69 mm, R4 is 299.2 mm, H is 621.24 mm, and the axial length of the volute is 633 mm.

[0113] The other main structural parameters of the fan provided by Embodiments 1 and 2, Comparative Example 1 and Comparative Example 2 of the present application, except for the volute, are shown in Table 1.

[0114] Table 1 Other main structural parameters of the fan provided by Embodiments 1 and 2, Comparative Example 1 and Comparative Example 2 of the present application, except for the volute

[0115]

[0116] The model is constructed and assembled by Solidworks software, and after the construction is completed, the simulation is performed by using Ansys Fluent software. The rotating speed of the impeller is set to 935 r / min, the inlet volume flow is set to 21678.77 m 3 / h, and the airflow uniformly flows into the inlet of the wheel disc 60.

[0117] Figure 15 (A) to Figure 15 (D) respectively show the velocity vector cloud diagram of the numerical simulation of the impeller provided by the first embodiment, the second embodiment, the first comparative example and the second comparative example of the present application.

[0118] Comparing Figure 15 (C) and Figure 15 (D) can be seen that, compared with the outlet of Comparative Example 1, the outlet of Comparative Example 2 presents an obvious airflow crossing and gathering phenomenon, the flow rate near the middle disc 50 is obviously larger than that on both sides, the air crossing and gathering in the volute 73 of the fan 70 leads to an increase in the air vortex around the impeller, in addition, the air crossing and gathering affects the normal work of the impeller, and even can cause airflow backflow, affecting the stability of the entire system, and is not conducive to improving the comprehensive performance of the fan 70.

[0119] The following compares Embodiment 1 of the present application with Comparative Example 1. Comparing Figure 15 (A) and Figure 15(C)It can be seen that the impeller airflow velocity vector cloud chart of the embodiment 1 of the present application and the impeller airflow velocity vector cloud chart of the conventional fan 70 in the comparative example 1 both have more airflow aggregation near the middle disc 50, but the airflow velocity of the impeller of the embodiment 1 of the present application is larger than that of the impeller in the comparative example 1 in the blade 10 area, which has a certain improvement effect on the instantaneous state pressure difference stability of the airflow, at the same time, can reduce the aerodynamic friction vibration of the impeller, reduce the power of the impeller, reduce the energy loss of the motor, relatively improve the efficiency of the fan, according to the momentum theorem, the outlet dynamic pressure is improved, combined with the calculation formula of the fan total pressure which is the pressure difference between the inlet and the outlet, the efficiency of the fan is further improved.

[0120] Comparative example 1 Figure 15 (A), Figure 15 (B) and Figure 16 (C)It can be seen that compared with the embodiment 1, the embodiment 2 of the present application adds the notch 111, so that the airflow velocity distribution of the impeller is more uniform, and the airflow near the middle disc 50 does not appear aggregation phenomenon, and the airflow velocity is mainly concentrated near the blade 10 located on both sides of the middle disc 50, which makes the running effect of the impeller of the embodiment 2 of the present application better than the previous several structures, and the system stability and the efficiency of the fan are better.

[0121] Specifically, the embodiment 1 has no notch structure, the intersection end 109 on one side close to the trailing edge is in the form of a protruding spike, and the spike point is the airflow aggregation point on both sides. From the theoretical stress analysis of the velocity vector and the wind resistance reaction force, it is not difficult to find that the aerodynamic intersection at this place pushes the blade in the opposite direction, increases the opposite moment, increases the power of the impeller, and thus increases the energy consumption of the motor. The embodiment 2 adds the notch 111 in the form of a sharp angle on the basis of the embodiment 1, and utilizes the rotor vortex theory to analyze that the structure is easy to form a tip vortex in the flow guiding process. The tip vortex at this place weakens the energy loss caused by the collision of the velocity vectors, and the notch structure at this place does not exist the stress transmission between solids. At the same time, the side wall surface of the notch 111 is a flat surface, so that part of the airflow moves in a straight line direction, without the uniform flow guiding effect of the circular curved surface, and the energy loss caused by the mutual collision of the airflow is weakened. Therefore, compared with the embodiment 1 without notch structure, the power of the impeller of the embodiment 2 will be relatively reduced, and the efficiency of the fan will be relatively improved.

[0122] Figure 16 (A) and Figure 16 (B) respectively show the local vorticity cloud chart of the blade end of the impeller inlet end when the blade end of the corresponding impeller inlet end is not chamfered and the local vorticity cloud chart of the blade end of the corresponding impeller inlet end when the blade end of the corresponding impeller inlet end is provided with a chamfer structure. Figure 16 (A) and Figure 17 (B), for the unchamfered blade, continuous vorticity appears near the disc, and for the chamfered blade, continuous vorticity does not appear near the disc, which shows that the chamfer structure plays a role in dispersing vorticity, which helps to reduce noise.

[0123] Figure 17 (A) and Figure 17 (B) respectively show the vortex distribution cloud maps of the impeller surfaces of the second embodiment and the first comparative example of the present application. Referring to Figure 17 (B), it can be seen that a large range of vortex aggregation appears in the middle region of the impeller surface of the comparative example 1, and the large range of vortex aggregation leads to a large fan noise of the comparative example 1. Comparing Figure 17 (A) and Figure 18 (B), it can be seen that the vortex of the impeller surface of the embodiment 2 is more uniformly distributed than that of the comparative example 1, thereby playing a noise reduction effect.

[0124] Figure 19 and Figure 20 respectively show the actual photos of the double-suction centrifugal impellers provided by the first embodiment and the second embodiment of the present application. Figure 21 and Figure 22 are two partial actual photos of the centrifugal fan provided by the second embodiment of the present application.

[0125] The following describes the actual measurement results of the main performance parameters of the four fans 70 respectively using the above four impellers. The present application tests the main performance parameters of the structures of the above four fans 70 under the environmental conditions of 1 standard atmosphere, 25℃ ambient temperature and 1.2kg / m 3 The above four fans 70 are tested under the environmental conditions of 1 standard atmosphere, 25℃ ambient temperature and 1.2kg / m

[0126] Figure 23 shows the comparison diagram of the relationship curves between the fan efficiency and the volume flow rate of the embodiment 1, the embodiment 2, the comparative example 1 and the comparative example 2 of the present application. Figure 24 shows the comparison diagram of the relationship curves between the shaft power of the centrifugal fan 70 and the volume flow rate of the embodiment 1, the embodiment 2, the comparative example 1 and the comparative example 2 of the present application. Figure 22 shows the comparison diagram of the relationship curves between the pressure of the centrifugal fan 70 and the volume flow rate of the embodiment 1, the embodiment 2, the comparative example 1 and the comparative example 2 of the present application.

[0127] In terms of fan efficiency, referring to Figure 22It can be seen that the fan efficiency of Comparative Example 2 is slightly improved compared with Comparative Example 1, and the overall difference is not large, and the improvement effect is not obvious. The efficiency corresponding to the highest improvement point of Example 1 is 34.28% compared with Comparative Example 1, while the efficiency at this position of Comparative Example 1 is 22.48%. According to the two values, the growth percentage is calculated to be 52.49%. Specifically, compared with Comparative Example 1, Example 1 sets the convex air inlet part 105, which increases the air inlet amount, reduces the separation and vortex of airflow at the leading edge of the blade 10, reduces the flow loss, and improves the fan efficiency. At the same time, the convex air inlet part 105 plays a role in guiding the airflow, so that the airflow enters the working area of the blade 10 more smoothly, improving the working efficiency and working capacity of the fan.

[0128] In terms of fan efficiency, see Figure 23 It can be seen that the efficiency corresponding to the highest improvement point of Example 2 is 29.9% compared with Comparative Example 1, while the efficiency at this position of Comparative Example 1 is 10.62%. According to the two values, the growth percentage is calculated to be 181.54%. Specifically, on the basis of Example 1, Example 2 increases the notch 111, which reduces the aggregation of airflow at the sharp part in the middle of the concave air outlet part 106 of the blade 10, disperses the airflow at this position, realizes the separation of aggregated vortex, thereby reducing the flow resistance and improving the efficiency.

[0129] Therefore, it can be seen that the efficiency of the centrifugal fan 70 provided by Example 2 is greatly improved, and is better than the other three structures as a whole.

[0130] In terms of shaft power, see Figure 24 It can be seen that the shaft power of Example 1 and Example 2 is basically the same, and the shaft power corresponding to the highest reduction point of Example 1 and Example 2 is 13.135kW compared with Comparative Example 1, while the shaft power at this position of Comparative Example 1 is 16.23kW. According to the two values, the reduction percentage is calculated to be 23.56%. Therefore, it can be seen that the shaft power of the centrifugal fan 70 provided by Example 1 and Example 2 is significantly reduced, and the effect is good.

[0131] In terms of fan pressure, see Figure 24It can be seen that the highest lifting point horizontal coordinate corresponding to the fan pressure of Example 1 is 550.6 Pa, while the fan pressure at this position of Comparative Example 1 is 450 Pa, and the growth percentage calculated from the two values is 22.35%. Specifically, the airflow in Comparative Example 1 produces a large angle change from the shell inlet to the impeller interior, and because Comparative Example 1 uses a straight blade 11 that is not twisted and is in the shape of a circular arc, the straight blade 11 has no flow guide structure, resulting in uneven airflow at each position of the blade. The double-section twisted blade of Example 1 increases the air inlet area, and the twisting surface in the double-section twisted blade has a flow guiding effect on the incoming air, which reduces the kinetic energy loss of the airflow redirection, and on this basis, reduces the energy loss of the cross-flow collection in the middle disc, thereby improving the fan pressure of Example 1.

[0132] Referring to ​ It can be seen that the highest lifting point horizontal coordinate corresponding to the fan pressure of Example 2 is 520.1 Pa, while the fan pressure at this position of Comparative Example 1 is 229.6 Pa, and the growth percentage calculated from the two values is 126.52%, which is much higher than the growth percentage of the highest lifting point horizontal coordinate corresponding to the fan pressure of Example 1 compared to Comparative Example 1, which is 22.35%.

[0133] Specifically, Example 2 increases the notch structure 111 based on Example 1, the notch is in the shape of a sharp angle division, and the analysis of the rotor vortex theory shows that this structure is prone to form a tip vortex during flow guiding. The tip vortex at this position weakens the energy loss of the speed vector collision, and because of the notch structure at this position, there is no force transmission between solids. At the same time, the side wall of the notch is a flat surface, which makes part of the airflow move in a straight line, without the uniform flow guiding effect of a circular surface, thereby weakening the energy loss caused by airflow impact. In addition, the front edge side of the blade 10 corresponding to the end of the impeller air inlet end adopts a rounded corner structure, which can increase the inlet flow of the wheel disc air inlet, eliminate the vortex generated by the tip, and reduce the inlet energy loss and noise. For all the above reasons, compared with Example 1, the highest lifting point corresponding to the fan pressure of Example 2 is further improved.

[0134] From the above, it can be seen that in terms of fan efficiency, shaft power and fan pressure, Example 1 of the present application is superior to Comparative Examples 1 and 2, and the overall centrifugal fan 70 provided by Example 2 is superior to Example 1.

[0135] The application provides a kind of centrifugal fan blade, the thought and method of double suction centrifugal impeller and fan using the blade, the method and approach of the specific implementation of the technical scheme are many, above is only the preferred embodiment of the present application, it should be pointed out that, for the ordinary skilled person in the art, without departing from the principle of the present application, a number of improvements and refinements can be made, these improvements and refinements should also be considered as the protection scope of the present application. The components not explicitly described in the embodiments can be implemented using existing technology.

Claims

1. A blade for a centrifugal fan, characterized by, The blade (10) comprises a suction surface wall (101), a pressure surface wall (102), a leading edge (103), a trailing edge (104), a convex air inlet portion (105) and a concave air outlet portion (106); the suction surface wall (101) and the pressure surface wall (102) are oppositely arranged, and both extend along the length direction of the blade (10) and between the leading edge (103) and the trailing edge (104); the convex air inlet portion (105) is protrusively formed on the leading edge portion of the blade (10) towards the side of the suction surface wall (101), and the concave air outlet portion (106) is protrusively formed on the trailing edge portion of the blade (10) towards the side of the pressure surface wall (102), and in the direction from the leading edge to the trailing edge, the convex air inlet portion (105) and the concave air outlet portion (106) are connected; In the length direction of the blade (10), the convex air inlet portion (105) has a structure of high in the middle and low on both sides, and the concave air outlet portion (106) has a structure of low in the middle and high on both sides; in the direction from the leading edge to the trailing edge, the middle height of the convex air inlet portion (105) has a decreasing trend; in the direction from the trailing edge to the leading edge, the middle height of the concave air outlet portion (106) has a decreasing trend; The blade (10) is a double-section reverse torsion blade structure, comprising a first torsion blade section (107) and a second torsion blade section (108) connected in sequence along the length direction of the blade (10), and the torsion direction of the first torsion blade section (107) is opposite to that of the second torsion blade section (108).

2. The blade for a centrifugal fan according to claim 1, characterized by The shape of any cross-sectional profile of the blade (10) perpendicular to the length direction thereof is a circular arc shape, the inner arc surface of the blade (10) is the pressure surface wall (102), the outer arc surface of the blade (10) is the suction surface wall (101), and the leading edge (103) and the trailing edge (104) are oppositely arranged in the arc length direction of the blade (10).

3. The blade for a centrifugal fan according to claim 2, characterized by The blade (10) comprises a first end (112) and a second end (113) oppositely arranged along the length direction of the blade (10), and a junction end (109) located between the first end (112) and the second end (113) along the length direction of the blade (10), wherein the first end (112) is used for connecting with the hub of an impeller, and the second end (113) is used for connecting with the disc of the impeller; The first twisted blade segment (107) is twisted by the first end (112) relative to the intersection end (109) in a direction opposite to the rotating direction of the blade, and the second twisted blade segment (108) is twisted by the second end (113) relative to the intersection end (109) in the opposite direction, so that the leading edge portions of the first twisted blade segment (107) and the second twisted blade segment (108) respectively protrude from the first end (112) and the second end (113) towards the intersection end (109) to form the convex air inlet portion (105) on the outer camber surface of the blade (10), and the trailing edge portions of the first twisted blade segment (107) and the second twisted blade segment (108) respectively protrude from the first end (112) and the second end (113) towards the intersection end (109) to form the concave air outlet portion (106) on the inner camber surface of the blade (10).

4. The blade for a centrifugal fan according to claim 3, characterized by The first twisted blade segment (107) comprises a first inner camber twisted surface (1071) and a first outer camber twisted surface (1072), and the second twisted blade segment (108) comprises a second inner camber twisted surface (1081) and a second outer camber twisted surface (1082), the first inner camber twisted surface (1071) of the first twisted blade segment (107) and the second inner camber twisted surface (1081) of the second twisted blade segment (108) are connected to form the pressure surface wall (102) of the blade (10), and the first outer camber twisted surface (1072) of the first twisted blade segment (107) and the second outer camber twisted surface (1082) of the second twisted blade segment (108) are connected to form the suction surface wall (101) of the blade (10).

5. The blade for a centrifugal fan according to claim 4, characterized by The first twisted blade segment (107) and the second twisted blade segment (108) have a common twisted axis (110), and the common twisted axis (110) is parallel to the length direction of the blade (10).

6. The blade for a centrifugal fan according to claim 5, wherein The first twisted blade segment (107) and the second twisted blade segment (108) have the same size in the cross-sectional profile perpendicular to the length direction of the blade (10).

7. The blade for a centrifugal fan according to claim 6, characterized by The cross-sectional profile of the blade (10) perpendicular to the length direction thereof has a midpoint (M), and the common twisted axis (110) passes through the midpoint (M).

8. The blade for a centrifugal fan according to claim 1, wherein The twisted angle of the first twisted blade segment (107) and the second twisted blade segment (108) ranges from 5° to 15°.

9. The blade for a centrifugal fan according to claim 8, characterized by The twisted angle of the first twisted blade segment (107) and the second twisted blade segment (108) is 10°.

10. The blade for a centrifugal fan according to claim 1, characterized by The length ratio of the first twisted blade segment (107) to the second twisted blade segment (108) ranges from 0.25 to 1.

5.

11. The blade for a centrifugal fan according to claim 10, wherein The length ratio of the first twisted blade segment (107) to the second twisted blade segment (108) is 1.

12. The blade for a centrifugal fan according to claim 1, characterized by Further comprising a notch (111) arranged at the trailing edge (104) of the blade (10) and at the joint of the first twisted blade segment (107) and the second twisted blade segment (108), the notch (111) is arranged in a right triangle shape.

13. A double suction centrifugal impeller characterized by The centrifugal fan blade according to any one of claims 1 to 12, wherein the centrifugal fan blade (10) is arranged in a plurality of, and the plurality of blades (10) are divided into two groups, and the two groups of blades (10) are symmetrically arranged on both sides of the hub (50) with the hub (50) as the symmetric plane; the plurality of blades (10) in each group are uniformly and spacedly arranged along the circumferential direction of the rotation axis (40); the length direction of each blade (10) is parallel to the rotation axis (40), and the leading edge (103) of each blade (10) is closer to the rotation axis (40) of the double-suction centrifugal impeller than the trailing edge (104).

14. The double suction centrifugal impeller of claim 13, wherein, The centrifugal fan blade according to any one of claims 1 to 12, wherein the centrifugal fan blade (10) is arranged in a plurality of, and the plurality of blades (10) are divided into two groups, and the two groups of blades (10) are symmetrically arranged on both sides of the hub (50) with the hub (50) as the symmetric plane; the plurality of blades (10) in each group are uniformly and spacedly arranged along the circumferential direction of the rotation axis (40); the length direction of each blade (10) is parallel to the rotation axis (40), and the leading edge (103) of each blade (10) is closer to the rotation axis (40) of the double-suction centrifugal impeller than the trailing edge (104).

15. A fan, comprising: The centrifugal fan blade according to any one of claims 1 to 12, wherein the centrifugal fan blade (10) is arranged in a plurality of, and the plurality of blades (10) are divided into two groups, and the two groups of blades (10) are symmetrically arranged on both sides of the hub (50) with the hub (50) as the symmetric plane; the plurality of blades (10) in each group are uniformly and spacedly arranged along the circumferential direction of the rotation axis (40); the length direction of each blade (10) is parallel to the rotation axis (40), and the leading edge (103) of each blade (10) is closer to the rotation axis (40) of the double-suction centrifugal impeller than the trailing edge (104). The double-suction centrifugal impeller (30) according to any one of claims 13 to 14; A support base (71); A driving motor (72) fixedly installed on one end of the top surface of the support base (71); A volute (73) fixedly installed on the other end of the top surface of the support base (71), and the double-suction centrifugal impeller (30) is arranged in the volute (73); an impeller rotating shaft (501) is connected to the hub (50) of the double-suction centrifugal impeller (30); And a transmission mechanism, the power of the driving motor (72) is transmitted to the impeller rotating shaft (501) through the transmission mechanism, and the rotation of the impeller rotating shaft (501) drives the double-suction centrifugal impeller (30) to rotate around the rotation axis (40) of the double-suction centrifugal impeller (30).

16. The fan of claim 15, wherein, The volute (73) comprises: Two oppositely arranged air inlet end plates (731); An annular plate (732) connected between the two air inlet end plates (731), And a hollow cavity (733) for accommodating the impeller formed by the two air inlet end plates (731) and the annular plate (732); The annular plate (732) is provided with a volute air outlet (734), and the two air inlet end plates (731) are each provided with a volute air inlet (735), and the volute air outlet (734) and each volute air inlet (735) are in communication with the hollow cavity (733).

17. The fan of claim 16, wherein, Further comprising an outer shell (74) covering the volute (73).

18. The fan of claim 17, wherein, The outer shell (74) is provided with a rotating shaft through hole, and one end of the impeller rotating shaft (501) that extends out of the outer shell (74) through the rotating shaft through hole is rotatably connected to the outer shell (74) through a bearing base.

19. The fan of claim 18, wherein, The transmission mechanism adopts a belt transmission. The transmission mechanism adopts a belt transmission.

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