Double-air-inlet centrifugal fan

Abstract

A double-air-inlet centrifugal fan comprises a volute and an impeller rotationally arranged in the volute, a first air inlet, a second air inlet and an air outlet are formed in a front cover plate and a rear cover plate of the volute respectively in the lateral direction, and the double-air-inlet centrifugal fan is characterized in that a center shaft is arranged in the volute; the front end and the rear end of the central shaft are respectively connected to a front cover plate and a rear cover plate of the volute; the impeller comprises an outer rotor, a blade assembly, a first connecting flow guide face and a second connecting flow guide face. The first connecting flow guide face and the second connecting flow guide face are arranged between the impeller assembly and the outer rotor, in this way, after double-face air inlet, turbulent vortexes formed at the air inlets in the two ends of the impeller can be eliminated, the working capacity of the impeller is improved, and noise caused by deterioration of the turbulent vortexes at the inlet of the impeller is further lowered.

Description

Technical Field

[0001] This invention relates to a fan, and more particularly to a centrifugal fan. Background Technology

[0002] A dual-inlet centrifugal fan is a ventilation device that improves suction efficiency, enhances stability and performance through a dual-inlet design. Its structure mainly includes a volute and an impeller that can be rotatably installed inside the volute. The front cover plate, rear cover plate and side of the volute respectively form a first air inlet, a second air inlet and an air outlet.

[0003] A common impeller consists of a blade assembly and a connecting disc located in the middle of the blade assembly. The blade assembly is cylindrical, and the connecting disc is connected to the output shaft of the motor. Another improved structure connects the blade assembly to the outer rotor of the motor via a central disc. The central disc is annular, and it often uses a common flat plate structure or a small-pressed flat plate structure to improve structural strength. This type of impeller has the following drawbacks: there is a large spatial difference at the connection between the impeller assembly and the central disc, and at the connection between the central disc and the outer rotor. Under this spatial difference, there is obvious turbulent vortex at the impeller inlet, resulting in low impeller work capacity and high noise. Therefore, improvement is needed. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a dual-inlet centrifugal fan that can eliminate turbulent vortices at the air outlet, in view of the above-mentioned technical status.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a dual-inlet centrifugal fan, including a volute and an impeller rotatably disposed in the volute, wherein the front cover plate, the rear cover plate and the side of the aforementioned volute are respectively formed with a first air inlet, a second air inlet and an air outlet, characterized in that a central shaft is provided in the volute, and the front end and the rear end of the central shaft are respectively connected to the front cover plate and the rear cover plate of the aforementioned volute.

[0006] The impeller includes

[0007] The outer rotor is rotatably mounted on the aforementioned central shaft;

[0008] The blade assembly is cylindrical and arranged around the aforementioned outer rotor;

[0009] The first connecting guide surface is annular and is connected between the inner wall of the aforementioned blade assembly and the outer end of the outer rotor and is directly opposite the aforementioned first air inlet. The first connecting guide surface and the front cover plate of the volute form the main air outlet cavity, and the main air outlet cavity forms the main air outlet at the air outlet.

[0010] The second connecting guide surface is annular and is connected between the inner wall of the aforementioned blade assembly and the outer end of the outer rotor, and is directly opposite the aforementioned second air inlet. The second connecting guide surface and the volute rear cover plate form a secondary air outlet cavity, and the secondary air outlet cavity forms a secondary air outlet at the air outlet. The aforementioned main air outlet and secondary air outlet are combined to form a complete air outlet.

[0011] Furthermore, a first collector is formed concavely around the first air inlet on the inner side of the front cover plate of the volute, and the first collector is arranged in a ring. A second collector is formed concavely around the second air inlet on the inner side of the rear cover plate of the volute, and the second collector is arranged in a ring. The first collector and the second collector have the following functions:

[0012] First, guide the airflow: reduce impeller inlet vortices and drag losses;

[0013] Second, the degree of filling: the entire circumference reaching the impeller inlet is evenly filled by the airflow, without any local gaps or backflow;

[0014] The third is uniform flow velocity: the velocity and direction of the airflow at each point at the impeller inlet are as consistent as possible.

[0015] Furthermore, the area of ​​the main air outlet is larger than the area of ​​the secondary air outlet; the first connecting guide surface has a convex first curve and a concave second curve in the cross-sectional direction, one end of the first curve is connected to the outer end of the outer rotor, and the other end is connected to the second curve, the outer end of the second curve is connected to the inner wall of the impeller assembly; the second connecting guide surface has a concave third curve in the cross-sectional direction.

[0016] Preferably, both the first curve and the second curve are circular arcs, and the first curve is tangentially connected to the second curve and tangentially connected to the outer rotor end face.

[0017] Preferably, the radius of the arc corresponding to the first curve is R1, the radius of the arc corresponding to the second curve is R2, and the radius of the outer rotor is R. m It satisfies the following formula:

[0018] R1=wR m ;

[0019] w is the arc control coefficient, w=0.29~0.36.

[0020] The third curve is a logarithmic spiral. The spiral guide can ensure that the tangential velocity component of the fluid remains constant at any cross-section during the process of the fluid entering the impeller from the second collector. The constant velocity means that the fluid flows smoothly in the volute before entering the impeller, without impact, eddies and energy loss caused by sudden velocity changes.

[0021] The logarithmic spiral satisfies the following formula:

[0022]

[0023]

[0024]

[0025]

[0026] In the above formula:

[0027] Spiral growth rate (0.28~0.35);

[0028] : Proportion of spirals - Control the start and end points of the spiral;

[0029] Spiral opening radius at -mm;

[0030] : Base circle radius of the helix - mm;

[0031] : Radius of the outer rotor - mm;

[0032] : The degree of spiral expansion;

[0033] : Dimension of the helix in the Z-axis direction - mm.

[0034] The second collector is configured to meet the following conditions:

[0035] a≤5, b≤5;

[0036] a is the horizontal distance (mm) between the helical reference circle and the endpoint of the second collector;

[0037] b is the vertical distance (mm) between the helical reference circle and the endpoint of the second collector.

[0038] Compared with the prior art, the advantages of the present invention are: a first connecting guide surface and a second connecting guide surface are provided between the impeller assembly and the outer rotor. After double-sided air intake, the turbulent vortex formed at the air inlets at both ends of the impeller can be eliminated, thereby improving the working capacity of the impeller and further reducing the noise caused by the deterioration of turbulent vortex at the impeller inlet. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of an embodiment.

[0040] Figure 2 This is a schematic diagram of the structure from another perspective of the embodiment.

[0041] Figure 3 for Figure 1 The exploded diagram.

[0042] Figure 4 for Figure 3 An enlarged view of the rotor from another perspective.

[0043] Figure 5 This is an enlarged cross-sectional schematic diagram of an embodiment.

[0044] Figure 6 This is a schematic diagram showing different opening degrees of the volute in the embodiment.

[0045] Figure 7 This is a turbulent kinetic energy cloud map of Example 90-270°.

[0046] Figure 8 This is a turbulent kinetic energy cloud map of Example 180-360°.

[0047] Figure 9 This is a comparative exploded diagram.

[0048] Figure 10 This is a scaled-up sectional view.

[0049] Figure 11 This is a comparative turbulent kinetic energy cloud map at 90-270°.

[0050] Figure 12 This is a comparative turbulent kinetic energy cloud map at 180-360°. Detailed Implementation

[0051] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0052] like Figure 1 , Figure 2 and Figure 3 As shown, the dual-inlet centrifugal fan in this embodiment includes a volute 10 and an impeller 3 rotatably disposed within the volute 10. The volute 10 is assembled from a front cover plate 1, a middle shell 2, and a rear cover plate 4. The front cover plate 1, the rear cover plate 4, and the sides of the volute 10 are respectively provided with a first air inlet 11, a second air inlet 41, and an air outlet 21. A central shaft 6 is provided inside the volute 10, and the front end and the rear end of the central shaft 6 are respectively connected to the front cover plate 1 and the rear cover plate 4 of the volute 10.

[0053] A first collector 12 is recessed on the inner side of the front cover plate 1 of the volute 10 around the first air inlet 11, and the first collector 12 is arranged in a ring. A second collector 42 is recessed on the inner side of the rear cover plate 4 of the volute 10 around the second air inlet 41, and the second collector 42 is arranged in a ring. The first collector and the second collector here have the following functions:

[0054] First, guide the airflow: reduce impeller inlet vortices and drag losses;

[0055] Second, the degree of filling: the entire circumference reaching the impeller inlet is evenly filled by the airflow, without any local gaps or backflow;

[0056] The third is uniform flow velocity: the velocity and direction of the airflow at each point at the impeller inlet are as consistent as possible.

[0057] In this embodiment, the impeller 3 includes an outer rotor 32, a blade assembly 31, a first connecting guide surface 33, and a second connecting guide surface 34.

[0058] The outer rotor 32 is rotatably mounted on the central shaft 6, and has a stator inside to form a motor.

[0059] The blade assembly 31 is cylindrical and arranged around the outer rotor 32;

[0060] The first connecting guide surface 33 is annular, connected between the inner wall of the blade assembly 31 and the outer end of the outer rotor 32 and directly facing the first air inlet 11. The first connecting guide surface 33 and the front cover plate 1 of the volute 10 form the main air outlet cavity, and the main air outlet cavity forms the main air outlet 211 at the air outlet 21.

[0061] The second connecting guide surface 34 is annular, connected between the inner wall of the blade assembly 31 and the outer end of the outer rotor 32 and directly facing the second air inlet 41. The second connecting guide surface 34 and the rear cover plate 4 of the volute 10 form a secondary air outlet cavity. The secondary air outlet cavity forms a secondary air outlet 212 at the air outlet 21. The main air outlet 211 and the secondary air outlet 212 combine to form a complete air outlet 21.

[0062] Combination Figure 3 , Figure 4 and Figure 5 As shown, the area of ​​the main air outlet 211 is larger than the area of ​​the secondary air outlet 212; the first connecting guide surface 33 has a first convex curve 331 and a second concave curve 332 in the cross-sectional direction, one end of the first curve is connected to the outer end of the outer rotor 32, and the other end is connected to the second curve 332, and the outer end of the second curve 332 is connected to the inner wall of the impeller 3 assembly; the second connecting guide surface 34 has a third concave curve in the cross-sectional direction.

[0063] Combination Figure 5As shown, both the first curve 331 and the second curve 332 are circular arcs, and the first curve 331 is tangentially connected to the second curve 332, and the first curve 331 is tangentially connected to the end face of the outer rotor 32.

[0064] In this embodiment, the radius of the arc corresponding to the first curve 331 is R1, the radius of the arc corresponding to the second curve 332 is R2, the second curve 332 is a transition arc, and the radius of the outer rotor 32 is R. m It satisfies the following formula:

[0065] R1=wR m ;

[0066] w is the arc control coefficient, w=0.29~0.36.

[0067] The third curve is a logarithmic spiral, satisfying the following formula:

[0068]

[0069]

[0070]

[0071]

[0072] In the above formula:

[0073] Spiral growth rate (0.28~0.35);

[0074] : Proportion of spirals - Control the start and end points of the spiral;

[0075] Spiral opening radius at -mm;

[0076] : Base circle radius of the helix - mm;

[0077] Radius of outer rotor 32 (mm);

[0078] : The degree of spiral expansion;

[0079] : Dimension of the helix in the Z-axis direction - mm.

[0080] a≤5, b≤5;

[0081] a is the horizontal distance (mm) between the spiral reference circle and the endpoint of the second collector 42;

[0082] b is the vertical distance (mm) between the helical reference circle and the endpoint of the second collector 42.

[0083] Comparative examples, such as Figure 9 and Figure 10 As shown, the centrifugal fan in this embodiment includes a volute and an impeller rotatably disposed within the volute. The volute is assembled from a front cover plate 11c, a middle shell 12c, and a rear cover plate 13c. The front cover plate 11c, the rear cover plate 13c, and the side of the volute are respectively formed with a first air inlet 111c, a second air inlet 131c, and an air outlet 121c.

[0084] The impeller 3 includes an outer rotor 23c, a blade assembly 22c, and a central disk 21c connecting the outer rotor 23c and the blade assembly 22c. The central disk 21c adopts a small-pressure flat plate structure to improve structural strength.

[0085] Combination Figure 7 , Figure 8 , Figure 11 and Figure 12 The turbulent kinetic energy cloud diagram shows that the turbulent kinetic energy distribution at the impeller inlet position in this embodiment is relatively uniform and the energy density is low, which further indicates that it has good performance in terms of system noise; overall, it is better than the performance of the comparative model.

[0086] The above-mentioned performance of this embodiment is based on the following analysis: In this embodiment, the air intake state and flow rate of the two air inlets of the volute are different, and the main air inlet and the auxiliary air inlet are defined respectively; according to the difference between the main and auxiliary air intakes, a middle plate composed of different flow guiding structures is designed to ensure that the fluid flows smoothly in the volute before entering the impeller, without impact, eddy currents and energy loss caused by sudden speed changes, thereby improving the impeller's work capacity and reducing the noise of the whole machine.

Claims

1. A dual-inlet centrifugal fan, comprising a volute (10) and an impeller (3) rotatably disposed within the volute (10), wherein the volute (10) has a front cover plate (1), a rear cover plate (4), and a side outlet (21) respectively formed thereon, characterized in that... The volute (10) is provided with a central shaft (6), the front end and the rear end of which are respectively connected to the front cover plate (1) and the rear cover plate (4) of the aforementioned volute (10); The impeller (3) includes The outer rotor (32) is rotatably mounted on the aforementioned central shaft (6); The blade assembly (31) is arranged in a cylindrical shape around the aforementioned outer rotor (32); The first connecting guide surface (33) is annular and is connected between the inner wall of the aforementioned blade assembly (31) and the outer end of the outer rotor (32) and is directly opposite the aforementioned first air inlet (11). The first connecting guide surface (33) and the front cover plate (1) of the volute (10) form the main air outlet cavity, and the main air outlet cavity forms the main air outlet (211) at the air outlet (21). The second connecting guide surface (34) is annular and is connected between the inner wall of the aforementioned blade assembly (31) and the outer end of the outer rotor (32) and is directly opposite the aforementioned second air inlet (41). The second connecting guide surface (34) and the rear cover plate (4) of the volute (10) form a secondary air outlet cavity. The secondary air outlet cavity forms a secondary air outlet (212) at the air outlet (21). The aforementioned main air outlet (211) and secondary air outlet (212) combine to form a complete air outlet (21).

2. The dual-inlet centrifugal fan according to claim 1, characterized in that... The inner side of the front cover plate (1) of the volute (10) is recessed around the first air inlet (11) to form a first collector (12), which is arranged in a ring.

3. The dual-inlet centrifugal fan according to claim 1, characterized in that... The inner side of the rear cover plate (4) of the volute (10) is recessed around the second air inlet (41) to form a second collector (42), which is arranged in a ring.

4. The dual-inlet centrifugal fan according to claim 1, characterized in that... The area of ​​the main air outlet (211) is larger than the area of ​​the secondary air outlet (212); the first connecting guide surface (33) has a first convex curve (331) and a second concave curve (332) in the cross-sectional direction, one end of the first curve is connected to the outer end of the outer rotor (32), and the other end is connected to the second curve (332), and the outer end of the second curve (332) is connected to the inner wall of the impeller (3) assembly; the second connecting guide surface (34) has a third concave curve in the cross-sectional direction.

5. The dual-inlet centrifugal fan according to claim 4, characterized in that... Both the first curve (331) and the second curve (332) are circular arcs, and the first curve (331) and the second curve (332) are tangentially connected. The first curve (331) is tangentially connected to the end face of the outer rotor (32).

6. The dual-inlet centrifugal fan according to claim 5, characterized in that... The radius of the arc corresponding to the first curve (331) is R1, the radius of the arc corresponding to the second curve (332) is R2, and the radius of the outer rotor (32) is R. m It satisfies the following formula: R1=wR m ; w is the arc control coefficient, w=0.29~0.

36.

7. The dual-inlet centrifugal fan according to claim 4, characterized in that... The third curve is a logarithmic spiral.

8. The dual-inlet centrifugal fan according to claim 7, characterized in that... The logarithmic spiral satisfies the following formula: In the above formula: Spiral growth rate (0.28~0.35); : Proportion of spirals - Control the start and end points of the spiral; Spiral opening radius at -mm; : Base circle radius of the helix - mm; : Radius of the outer rotor (32) in mm; : The degree of spiral expansion; : Dimension of the helix in the Z-axis direction - mm.

9. The dual-inlet centrifugal fan according to claim 8, characterized in that... The inner side of the rear cover plate (4) of the volute (10) is recessed around the second air inlet (41) to form a second collector (42). The second collector (42) is annular and satisfies the following conditions: a≤5, b≤5; a is the horizontal distance in mm between the reference circle of the spiral and the endpoint of the second collector (42); b is the vertical distance - mm between the reference circle of the spiral and the endpoint of the second collector (42).

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