Flow guide device of air inlet of centrifugal fan and centrifugal fan

Abstract

The utility model provides a flow guiding device of an air inlet of a centrifugal fan and the centrifugal fan, the flow guiding device is defined by a side wall rotating around the axis of the flow guiding device, and the side wall comprises a plane wall, a first curved surface wall, a second curved surface wall and a third curved surface wall which are sequentially connected in the axial direction; the plane wall is perpendicular to the axis of the flow guide device, the second end of the plane wall is tangentially connected with the first end of the first curved wall, the second end of the first curved wall is tangentially connected with the first end of the second curved wall, and the second end of the second curved wall is tangentially connected with the first end of the third curved wall; the position, with the minimum vertical distance from the axis of the flow guiding device, of the flow guiding device is located on the second curved surface wall or the third curved surface wall, and the minimum vertical distance is the throat diameter of the flow guiding device. According to the flow guiding device, the flowing state of the front disc of the impeller can be improved, the separation loss of airflow on the back faces of the blades at the front disc is obviously reduced, and the effects of reducing pneumatic loss and reducing noise are achieved.

Description

Technical Field

[0001] The present application belongs to the technical field of centrifugal fans, and further relates to a structure optimization technology for a centrifugal fan without a volute. Specifically, a flow guide device for an air inlet of a centrifugal fan and a centrifugal fan using the flow guide device are provided. Background Art

[0002] Casingless centrifugal fans are widely used in workshops, mines, pipelines, vehicles, ships, buildings and other places to achieve functions such as ventilation, dust removal and cooling. Improving fan efficiency while reducing noise has always been the main goal of design optimization of voluteless centrifugal fans.

[0003] The guide device set at the air inlet of the centrifugal fan is an important component that cooperates with the impeller of the centrifugal fan. It is mainly used to guide the airflow into the impeller. Its structural form is directly related to the air flow and direction entering the impeller, and has an important impact on the air pulsation, vortex and noise at the air inlet. If there are problems with the structural design, it will inevitably fail to fully correct the angle of the airflow entering the impeller and improve the separation loss of the airflow at the front disc. It may even cause airflow disturbance due to improper setting of the gap between the end of the air inlet and the front end of the front disc, further causing aerodynamic losses and increased noise. Utility Model Content

[0004] In order to solve the problems existing in the above-mentioned prior art, the first aspect of the present application provides a flow guide device for an air inlet of a centrifugal fan, wherein the flow guide device is surrounded by a side wall rotatably around the axis of the flow guide device; the side wall comprises a plane wall, a first curved wall, a second curved wall and a third curved wall connected in sequence along the axial direction;

[0005] The plane wall is perpendicular to the axis of the flow guiding device, and the distance between the first end of the plane wall and the axis of the flow guiding device is greater than the distance between the second end of the plane wall and the axis of the flow guiding device;

[0006] The second end of the planar wall is tangentially connected to the first end of the first curved wall, the second end of the first curved wall is tangentially connected to the first end of the second curved wall, and the second end of the second curved wall is tangentially connected to the first end of the third curved wall;

[0007] The point on the flow guide device where the vertical distance to its axis is the smallest is located on the second curved wall or the third curved wall, and the smallest vertical distance is the throat diameter of the flow guide device.

[0008] Furthermore, the cross-sectional profiles of the inner walls of the first curved wall, the second curved wall and the third curved wall are all arcs and their radii are different from each other.

[0009] Furthermore, the center angle of the cross-sectional profile of the inner wall of the first curved wall is 50° to 75°, the center angle of the cross-sectional profile of the inner wall of the second curved wall is 15° to 35°, and the center angle of the cross-sectional profile of the inner wall of the third curved wall is 28° to 53°.

[0010] Furthermore, the height of the guide device along the axial direction is L1, and the radii of the cross-sectional profiles of the inner walls of the first curved wall, the second curved wall, and the third curved wall are R1, R2, and R3, respectively; the ratio of R1 to L1 ranges from 0.35 to 0.69, the ratio of R2 to L1 ranges from 0.68 to 0.93, and the ratio of R3 to L1 ranges from 0.63 to 0.92.

[0011] Preferably, the plane wall, the first curved wall, the second curved wall and the third curved wall have the same thickness.

[0012] Preferably, the ratio of the throat diameter to the radius of the flow guide device is in a range of 0.88 to 0.97, wherein the radius of the flow guide device is the vertical distance between the second end of the third curved wall and the axis of the flow guide device.

[0013] Preferably, the distance between the plane where the throat diameter of the flow guide device is located and the plane where the second end of the third curved wall is located is L3, and the ratio of L3 to L1 ranges from 0.25 to 0.45.

[0014] The present application also provides a centrifugal fan that uses the above-mentioned guide device to guide the air inlet.

[0015] The guide device for the air inlet of a centrifugal fan provided in an embodiment of the present application comprises a smoothly transitioned air inlet structure composed of multiple sections of tangentially connected plane walls and curved walls, and the structure gradually shrinks from the front end of the air inlet position to the throat, and gradually bends and diffuses toward the front disk of the impeller after passing through the throat. This structure that first shrinks and then diffuses can effectively correct the angle of the airflow entering the inside of the impeller of the centrifugal fan, reduce the speed fluctuation of the airflow from the air inlet to the front of the impeller, and the high-pressure air volume leaked from the overlap of the impeller and the air inlet is guided by the third curved wall of the air inlet to replenish air at the front disk of the impeller, thereby improving the flow state at the front disk of the impeller and significantly reducing the separation loss of the airflow on the back of the blades at the front disk, thereby reducing aerodynamic losses and aerodynamic noise; in addition, it can also widen the working area of ​​the fan and make the pressure curve of the fan change more smoothly. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the three-dimensional structure of the flow guide device of the air inlet of the centrifugal fan provided according to the embodiment of the present application;

[0017] Figure 2 A side view of a flow guide device for an air inlet of a centrifugal fan provided according to an embodiment of the present application;

[0018] Figure 3 A top view of a flow guide device for an air inlet of a centrifugal fan provided according to an embodiment of the present application;

[0019] Figure 4 A cross-sectional view of a flow guide device for an air inlet of a centrifugal fan provided according to an embodiment of the present application;

[0020] Figure 5 for Figure 4 A partial enlarged view of the middle circle II;

[0021] Figure 6 It is a structural schematic diagram of a volute-free centrifugal fan provided according to an embodiment of the present application;

[0022] Figure 7 It is a cross-sectional view of a volute-free centrifugal fan provided according to an embodiment of the present application.

[0023] Numbers in the figure

[0024] The guide device 1 , the plane wall 10 , the first curved wall 11 , the second curved wall 12 , the third curved wall 13 , the impeller 2 , the front disc 210 , the fan blades 220 , the rear disc 230 , the cylinder 231 , and the motor 3 . DETAILED DESCRIPTION

[0025] Hereinafter, the present application will be further described based on preferred embodiments with reference to the accompanying drawings.

[0026] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the products of the embodiments of the present application are usually placed when in use, it is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, in the description of the present application, in order to distinguish different units, the words first, second, etc. are used in this specification, but these are not limited by the order of manufacture, nor can they be understood as indicating or implying relative importance. Their names may be different in the detailed description and claims of the present application; in addition, in order to facilitate understanding, various components on the drawings are enlarged or reduced, but this practice is not intended to limit the scope of protection of the present application.

[0027] The vocabulary in this specification is used to illustrate the embodiments of the present application, but is not intended to limit the present application. It should also be noted that, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, an indirect connection through an intermediate medium, or a connection between the two elements. For those skilled in the art, the specific meanings of the above terms in this application can be specifically understood.

[0028] The embodiment of the present application provides a flow guide device 1 for an air inlet of a centrifugal fan. Figures 1 to 3 The three-dimensional structure, side view and top view of the flow guide device 1 are shown respectively. Figure 4 is a cross-sectional view of the flow guide device 1 (the section line is Figure 3 Middle AA line), Figure 5 right Figure 4 The middle circle II portion is shown enlarged.

[0029] like Figures 1 to 5 As shown, the flow guide device 1 is formed by rotating the side wall 360° around the axis L_axis to form a closed structure, wherein the side wall comprises a plane wall 10, a first curved wall 11, a second curved wall 12 and a third curved wall 13 connected in sequence along the axial direction.

[0030] Specifically, as shown in the figure, the plane wall 10 is perpendicular to the axis L_axis of the flow guide device 1 and extends radially, and the radial distance between the first end of the plane wall 10 and the axis L_axis is greater than the distance between the second end of the plane wall 10 and the axis L_axis. Further, the second end of the plane wall 10 is tangentially connected to the first end of the first curved wall 11, the second end of the first curved wall 11 is tangentially connected to the first end of the second curved wall 12, and the second end of the second curved wall 12 is tangentially connected to the first end of the third curved wall 13.

[0031] The throat is formed at the point where the vertical distance between the guide device 1 and its axis L_axis is the smallest. The vertical distance between this point and the axis is the throat diameter D00. Figure 4 As shown, in some embodiments of the present application, the throat of the flow guide device 1 is located on the second curved wall 12. In other optional embodiments, the throat of the flow guide device may also be located on the third curved wall.

[0032] In some preferred embodiments, the ratio of D00 to the radius D01 of the flow guiding device 1 (ie, the vertical distance between the second end of the third curved wall 13 and the axis) ranges from 0.88 to 0.97.

[0033] The above-mentioned air inlet structure composed of multiple sections of tangentially connected plane walls 10 and curved walls gradually shrinks from the front end of the air inlet position to the throat, and bends and diffuses toward the impeller front disk after passing through the throat. This structure that first shrinks and then diffuses can effectively correct the angle of the airflow entering the impeller of the centrifugal fan, reduce the speed fluctuation of the airflow from the air inlet to the front of the impeller, and the high-pressure air volume leaked from the overlap of the impeller and the air inlet is guided by the third curved wall of the air inlet to replenish air at the impeller front disk, thereby improving the flow state at the impeller front disk and significantly reducing the separation loss of the airflow on the back of the blades at the front disk, thereby reducing aerodynamic losses and reducing aerodynamic noise.

[0034] In the embodiments of the present application, Figure 5 As shown, the cross-sectional profiles of the inner walls of the first curved wall 11 , the second curved wall 12 and the third curved wall 13 are all arcs, and the arc radii are R1 , R2 and R3 respectively, and R1 , R2 and R3 are different from each other.

[0035] In some preferred embodiments, the ratio of R1 to L1 ranges from 0.35 to 0.69, the ratio of R2 to L1 ranges from 0.68 to 0.93, and the ratio of R3 to L1 ranges from 0.63 to 0.92, wherein, Figure 4 As shown, L1 is the height of the flow guiding device 1 along the axial direction.

[0036] In some preferred embodiments, the center angle of the cross-sectional profile of the inner wall of the first curved wall is 50° to 75°, the center angle of the cross-sectional profile of the inner wall of the second curved wall is 15° to 35°, and the center angle of the cross-sectional profile of the inner wall of the third curved wall is 28° to 53°.

[0037] The annular wall of the flow guide device 1 can be made of high-strength metal or polymer material, and the production process can be selected according to the manufacturing material, for example, it can be made by molding, casting, forging, sheet metal bending or 3D printing and other processing techniques. In some preferred embodiments, Figure 5 As shown, the plane wall 10, the first curved wall 11, the second curved wall 12 and the third curved wall 13 have the same thickness, and thus, the outer sides of the side walls of each section are also tangentially connected in sequence, and the cross-sectional profiles of the outer walls of the first curved wall 11, the second curved wall 12 and the third curved wall 13 are all arcs, and the relationship between their radius and central angle is similar to that of the inner wall.

[0038] like Figure 4 As shown, the distance between the plane where the throat diameter of the flow guide device 1 is located and the plane where the second end of the third curved wall 13 is located is L3. In some preferred embodiments, the ratio of L3 to L1 ranges from 0.25 to 0.45.

[0039] The present application also provides a centrifugal fan that uses the guide device 1 to guide the air inlet. Figure 6 is the structural schematic diagram of the centrifugal fan. Figure 7 is a cross-sectional view of the centrifugal fan (the section line is Figure 3 AA line), such as Figure 6 , Figure 7 As shown, the centrifugal fan is a high-efficiency, low-noise, volute-free centrifugal fan, which includes a flow guide device 1, an impeller 2 and a motor 3 coaxially arranged in sequence along the axial direction.

[0040] Among them, the guide device 1 is located at the inlet of the impeller 2, and its straight wall can be used as a mounting flange of the supporting structure (not shown in the figure) when the centrifugal fan is installed. The impeller 2 includes a front disk 210, a rear disk 230, and a plurality of fan blades 220 fixedly connected between the front disk 210 and the rear disk 230 and arranged at intervals along the circumferential direction. The second end of the third curved wall 13 of the guide device 1 extends into one end of the front disk 210 facing the air inlet.

[0041] Furthermore, the motor 3 is an outer rotor motor, whose outer rotor is fixedly connected to the cylinder 231 inside the rear disk 230 through a connecting piece, and the motor body is fixedly connected to the supporting structure, and the impeller 2 is driven to rotate by the rotation of the outer rotor relative to the motor body.

[0042] In some preferred embodiments, Figure 5 As shown, the depth of the second end of the third curved wall 13 entering the front end of the front disk 210 is a, and the radial distance from the front end of the front disk 210 is b. In some preferred embodiments, a is in the range of 5 mm to 10 mm, and b is in the range of 3 mm to 5 mm. In some preferred embodiments, Figure 5 As shown, the tangential extension line L_tangent of the inner wall cross-sectional profile of the third curved wall 13 from the second end thereof is tangent to the cross-sectional profile of the inner wall of the front disk 210. Through the above preferred embodiments, the air inlet structure formed by the guide device 1 can be matched with the structure of the impeller 2, further reducing turbulence and separation losses, so that the overall static pressure efficiency of the fan is improved by about 2%.

[0043] It should be known that the flow guiding device 1 can be used in addition to Figure 6 and Figure 7 The volute-free centrifugal fan shown can also be applied to centrifugal fans of other structures to optimize the airflow condition at the air inlet.

[0044] The above is a detailed introduction to the specific implementation methods of the present application. For those skilled in the art, several improvements and modifications may be made to the present application without departing from the principles of the present application. These improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A flow guide device for an air inlet of a centrifugal fan, formed by rotating side walls around the axis of the flow guide device, characterized in that: The side wall comprises a plane wall, a first curved wall, a second curved wall and a third curved wall which are sequentially connected along the axial direction; The plane wall is perpendicular to the axis of the flow guiding device, and the distance between the first end of the plane wall and the axis of the flow guiding device is greater than the distance between the second end of the plane wall and the axis of the flow guiding device; The second end of the planar wall is tangentially connected to the first end of the first curved wall, the second end of the first curved wall is tangentially connected to the first end of the second curved wall, and the second end of the second curved wall is tangentially connected to the first end of the third curved wall; The point on the flow guide device where the vertical distance to its axis is the smallest is located on the second curved wall or the third curved wall, and the smallest vertical distance is the throat diameter of the flow guide device.

2. The flow guide device for the air inlet of a centrifugal fan according to claim 1, characterized in that: The cross-sectional profiles of the inner walls of the first curved wall, the second curved wall and the third curved wall are all arcs, and the radii thereof are different from each other.

3. The flow guide device for the air inlet of a centrifugal fan according to claim 2, characterized in that: The center angle of the cross-sectional profile of the inner wall of the first curved wall is 50° to 75°, the center angle of the cross-sectional profile of the inner wall of the second curved wall is 15° to 35°, and the center angle of the cross-sectional profile of the inner wall of the third curved wall is 28° to 53°.

4. The flow guide device for the air inlet of a centrifugal fan according to claim 2, characterized in that: The height of the flow guide device along the axial direction is L1, and the radii of the cross-sectional profiles of the inner walls of the first curved wall, the second curved wall, and the third curved wall are R1, R2, and R3 respectively; The ratio of R1 to L1 ranges from 0.35 to 0.69, the ratio of R2 to L1 ranges from 0.68 to 0.93, and the ratio of R3 to L1 ranges from 0.63 to 0.

92.

5. The flow guide device for the air inlet of a centrifugal fan according to claim 4, characterized in that: The thicknesses of the plane wall, the first curved wall, the second curved wall and the third curved wall are the same.

6. The flow guide device for the air inlet of a centrifugal fan according to claim 4, characterized in that: The ratio of the throat diameter to the radius of the flow guide device ranges from 0.88 to 0.97, wherein the radius of the flow guide device is the vertical distance between the second end of the third curved wall and the axis of the flow guide device.

7. The flow guide device for the air inlet of a centrifugal fan according to claim 4, characterized in that: The distance between the plane where the throat diameter of the flow guide device is located and the plane where the second end of the third curved wall is located is L3, and the ratio of L3 to L1 ranges from 0.25 to 0.

45.

8. A centrifugal fan, characterized in that: The guide device described in claim 1 is used to guide the air inlet.

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