Centrifugal fan

Abstract

A centrifugal fan comprises a volute, an impeller arranged in the volute and a volute tongue arranged at an outlet of the volute, the volute is provided with a volute ring wall, a flow channel is formed between the volute ring wall and the impeller, and an air inlet is formed in the volute ring wall. The air guide interface comprises a mounting frame and at least two air guide blades mounted in the mounting frame, the mounting frame is fixed on the annular wall of the volute, the air guide blades are distributed at intervals along the flowing direction of the air flow, and the air guide blades are used for guiding the air flow outside the fan into the flow channel. Compared with the prior art, the centrifugal fan has the advantages that the air guide interface is arranged at the air inlet of the volute annular wall, and the air guide interface is provided with the at least two air guide sheets which are distributed at intervals along the flowing direction of the air flow, so that the air flow outside the fan can be more effectively guided into the flow channel by the air guide sheets; and therefore, the efficiency of the fan is improved, and the working noise of the fan is reduced.

Description

Technical Field

[0001] The utility model relates to a fan, in particular to a centrifugal fan. Background Art

[0002] Centrifugal fans are widely used in range hoods for their advantages such as strong suction, low noise and compact structure. The volute is one of the core components of the centrifugal fan. Its function is to collect the gas leaving the impeller, guide it to the outlet of the volute, and convert the dynamic pressure into static pressure. The fan of the range hood generally adopts a centrifugal fan. In order to improve the efficiency, it is usually necessary to match it with a high-efficiency DC motor, which is relatively expensive. In addition, the existing centrifugal fan has only one air inlet, which has certain limitations. In order to improve the oil fume extraction effect and improve the performance of the range hood, the air inlet can be increased. For example, the Chinese utility model patent with patent number CN201220666311.8 (authorization announcement number CN 203051230 U) discloses the "air inlet structure of the fan volute intermediate plate guide vane of the range hood", which includes an annular intermediate plate connected to the front cover plate and the rear cover plate of the volute, and the angle of the volute tongue at the front end of the annular intermediate plate is designed to prevent the air volume from not entering the outlet and flowing back to the volute at the best angle, and the rear end of the volute tongue is provided with an air inlet, and the rear end of the annular intermediate plate volute tongue is provided with an air inlet, so that after the impeller blades pass through the volute tongue, the air flow is immediately introduced from the air inlet through the air inlet guide plate, so that the fan efficiency is improved and the air volume at the outlet is increased. Although this structure has a certain effect on improving the oil smoke absorption, backflow may occur, and the improvement of the fan efficiency is relatively limited. In summary, further improvements need to be made to the existing centrifugal fans. Utility Model Content

[0003] The technical problem to be solved by the utility model is to provide a centrifugal fan which can effectively reduce the backflow at the air inlet and improve the efficiency of the fan in view of the above-mentioned existing technical status.

[0004] The technical solution adopted by the utility model to solve the above-mentioned technical problems is: a centrifugal fan, including a volute, an impeller arranged inside the volute and a volute tongue arranged at the outlet of the volute, the volute having a volute ring wall, a flow channel formed between the volute ring wall and the impeller, an air inlet opened on the volute ring wall, characterized in that: an air guide interface is installed at the air inlet, the air guide interface includes a mounting frame and air guide vanes installed in the mounting frame, the mounting frame is fixed on the volute ring wall, the air guide vanes have at least two pieces and are spaced apart along the flow direction of the airflow, and the air guide vanes are used to guide the airflow outside the fan into the interior of the flow channel.

[0005] Preferably, there are at least three air guides and the air guides are evenly spaced. In addition, the air guides may also be unevenly spaced.

[0006] In order to smoothly guide the airflow into the interior of the flow channel, the air guide piece extends inwardly into the interior of the flow channel.

[0007] The air guide blades may have a variety of different shapes. Preferably, the air guide blades are square, arc-shaped, wavy, triangular, trapezoidal, circular, or elliptical.

[0008] The length of the air guide plate can be selected in a variety of ways. Preferably, the length a of the air guide plate and the arc length L of the opening of the air inlet satisfy 0 <a<5L。

[0009] Preferably, the angle β between the tangent line at the intersection of the air guide vane and the volute profile and the air guide vane satisfies 0<β≤120°. When the air guide vane is designed to be inclined at the above angle, the air intake effect is better and the fan performance is significantly improved.

[0010] Further preferably, on a plane perpendicular to the central axis of the impeller and passing through the center of the impeller, the straight line passing through the tip of the volute tongue and the center of the impeller is M, the straight line passing through the upstream edge of the air inlet and the center of the impeller is N, and the angle α between the straight line M and the straight line N satisfies 1°≤α≤350°. The air inlet can be arranged at different positions along the circumference of the volute ring wall, and the closer the position of the air inlet is to the position of the volute tongue, the greater the air intake of the air inlet. This structure can improve the efficiency of the fan on the basis of reducing costs.

[0011] More preferably, 1°≤α≤180°

[0012] In order to ensure the air intake of the air inlet, on the plane perpendicular to the central axis of the impeller and passing through the center of the impeller, the straight line between the upstream edge of the air inlet and the center of the impeller is N, and the straight line between the downstream edge of the air inlet and the center of the impeller is P, then the angle between the straight line N and the straight line P is θ, and 5°<θ≤60°.

[0013] As a preferred embodiment of any of the above solutions, the thickness of the volute is b, and the maximum width of the air inlet is b1, then b1≤b is satisfied.

[0014] Compared with the prior art, the advantages of the utility model are: the centrifugal fan installs an air guide interface at the air inlet of the volute ring wall. Since the air guide interface has at least two air guide vanes spaced along the air flow direction, the air guide vanes can more effectively guide the external airflow of the fan into the interior of the flow channel, thereby reducing backflow or eliminating backflow, thereby improving the fan efficiency and reducing the fan operating noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the structure of a range hood according to an embodiment of the utility model;

[0016] Figure 2This is a schematic structural diagram of a centrifugal fan according to an embodiment of the utility model;

[0017] Figure 3 for Figure 2 A structural cross-sectional view of a centrifugal fan shown;

[0018] Figure 4 for Figure 3 A magnified schematic diagram of part A;

[0019] Figure 5 for Figure 3 Another enlarged schematic diagram of part A;

[0020] Figure 6 for Figure 2 A top view of the centrifugal fan shown;

[0021] Figure 7 This is a schematic diagram of the structure of the air guide interface of an embodiment of the utility model;

[0022] Figure 8 for Figure 7 A schematic diagram of the structure of the air guide interface from another angle is shown. DETAILED DESCRIPTION

[0023] The present invention will be described in further detail below in conjunction with the accompanying drawings.

[0024] like Figures 1 to 6 As shown, the centrifugal fan of this embodiment includes a volute 1, an impeller 2 arranged inside the volute 1, and a volute tongue 3 arranged at the outlet of the volute 1. The volute 1 has a volute ring wall 11, and a flow channel 6 is formed between the volute ring wall 11 and the impeller 2. An air inlet 4 is opened on the volute ring wall 11, and an air guide interface 5 is installed at the air inlet 4. The air guide interface 5 includes a mounting frame 51 and an air guide vane 52 installed in the mounting frame 51. The mounting frame 51 is fixed on the volute ring wall 11, and the air guide vane 52 extends inwardly to the inside of the flow channel 6, so as to guide the airflow outside the fan into the inside of the flow channel 6.

[0025] like Figure 7 and Figure 8 As shown, the air inlet 4 and the air guide piece 52 of this embodiment are both square, and there are six air guide pieces 52 and they are evenly spaced along the air flow direction. In addition, the air inlet 4 can be in various shapes such as diamond, triangle, trapezoid, polygon, circle, ellipse, etc. in addition to being square. The air guide piece 52 can also be in other shapes such as arc, wave, triangle, trapezoid, circle, ellipse, etc. in addition to being square. The number of air guide pieces 52 is not limited to six.

[0026] like Figure 4 and Figure 5As shown in the figure, the length a of the air guiding vane 52 and the arc length L of the opening section of the air inlet 4 satisfy 0 < a < 5L. The air guiding vane 5 can be longer than the arc length of the opening section of the air inlet 4 or shorter than the arc length of the opening section of the air inlet 4. In this embodiment, the length of the air guiding vane 5 is shorter than the arc length of the opening section of the air inlet 4, that is, a < L.

[0027] As Figure 3 shown, on the plane perpendicular to the central axis of the impeller 2 and passing through the center of the impeller 2, taking the straight line passing through the tip of the volute tongue 3 and the center of the impeller 2 as M, and the straight line passing through the upstream edge of the air inlet 4 and the center of the impeller 2 as N, the included angle α between the straight line M and the straight line N satisfies 1° ≤ α ≤ 350°. Preferably, the included angle α satisfies 1° ≤ α ≤ 180°. The smaller the α angle, the closer the opening position of the air inlet 4 is to the volute tongue 3, the greater the air intake volume of the air inlet 4, and the higher the fan efficiency. On the plane perpendicular to the central axis of the impeller 2 and passing through the center of the impeller 2, taking the straight line passing through the upstream edge of the air inlet 4 and the center of the impeller 2 as N, and the straight line passing through the downstream edge of the air inlet 4 and the center of the impeller 2 as P, then the included angle between the straight line N and the straight line P is θ, then 5° < θ ≤ 60°. The angle θ reflects the opening size of the air inlet 4 and needs to be limited within a suitable range. Too large or too small will not achieve a good air intake effect.

[0028] As Figure 5 shown, the angle β between the tangent line at the intersection of the air guiding vane 52 and the volute profile line and the air guiding vane 52 satisfies 0 < β ≤ 120°. Let the angle corresponding to the most upstream air guiding vane 52 be β1, and along the air flow direction, the angles corresponding to the remaining air guiding vanes 52 are β2, β3... respectively. Correspondingly, it is necessary to satisfy 0 < β1 ≤ 120°, 0 < β2 ≤ 120°, 0 < β3 ≤ 120°... Through experiments, the best preferred scheme is 0 < β ≤ 90°.

[0029] As Figure 6 shown, the thickness b of the volute 1 and the maximum width b1 of the air inlet 4 satisfy b1 ≤ b.

[0030] There is 1 air inlet 4 on the volute annular wall 11 of this embodiment, and a structure with multiple air inlets 4 can also be adopted, and the air inlets 4 are circumferentially spaced along the volute annular wall 11. For the case of multiple air inlets 4, a air guiding interface 5 can be installed at one of the air inlets 4, or a air guiding interface 5 can be installed at each air inlet. The multiple air guiding vanes of the air guiding interface 5 can more effectively introduce the external air flow of the fan into the flow channel, thereby reducing the backflow or eliminating the backflow, and further improving the fan efficiency and reducing the working noise of the fan.

[0031] In the specification and claims of the present invention, terms indicating directions, such as "front", "rear", "up", "down", "left", "right", "side", "top", "bottom", etc., are used to describe various exemplary structural parts and elements of the present invention, but these terms are used here only for the purpose of convenience of description and are determined based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed in the present invention can be arranged in different directions, these terms indicating directions are only used as explanations and should not be regarded as limitations. For example, "up" and "down" are not necessarily limited to directions opposite to or consistent with the direction of gravity.

Claims

1. A centrifugal fan, comprising a volute (1), an impeller (2) arranged inside the volute (1), and a volute tongue (3) arranged at the outlet of the volute (1), the volute (1) having a volute ring wall (11), a flow channel (6) formed between the volute ring wall (11) and the impeller (2), an air inlet (4) being opened on the volute ring wall (11), characterized in that: An air guide interface (5) is installed at the air inlet (4), the air guide interface (5) comprising a mounting frame (51) and an air guide vane (52) mounted in the mounting frame (51), the mounting frame (51) being fixed on the volute ring wall (11), the air guide vanes (52) comprising at least two pieces and being spaced apart and distributed along the air flow direction, the air guide vanes (52) being used to guide the air flow outside the fan into the interior of the flow channel (6).

2. The centrifugal fan according to claim 1, characterized in that: The air guide blades (52) are at least three and are evenly spaced.

3. The centrifugal fan according to claim 1, characterized in that: The air guide piece (52) extends inwardly to the interior of the flow channel (6).

4. The centrifugal fan according to claim 1, characterized in that: The air guide piece (52) is square, arc-shaped, wavy, triangular, trapezoidal, circular or elliptical.

5. The centrifugal fan according to claim 1, characterized in that: The length a of the air guide plate (52) and the arc length L of the opening section of the air inlet (4) satisfy 0 <a<5L。 6. The centrifugal fan according to claim 1, characterized in that: An angle β between a tangent line at an intersection of the air guide vane (52) and the volute profile line and the air guide vane (52) satisfies 0<β≤120°.

7. The centrifugal fan according to claim 1, characterized in that: On a plane perpendicular to the central axis of the impeller (2) and passing through the center of the impeller (2), a straight line passing through the tip of the volute tongue (3) and the center of the impeller (2) is denoted as M, and a straight line passing through the upstream edge of the air inlet (4) and the center of the impeller (2) is denoted as N, and an angle α between the straight lines M and N satisfies 1°≤α≤350°.

8. The centrifugal fan according to claim 1, characterized in that: On a plane perpendicular to the central axis of the impeller (2) and passing through the center of the impeller (2), the straight line between the upstream edge of the air inlet (4) and the center of the impeller (2) is N, and the straight line between the downstream edge of the air inlet (4) and the center of the impeller (2) is P, then the angle between the straight line N and the straight line P is θ, and 5°<θ≤60°.

9. The centrifugal fan according to any one of claims 1 to 8, characterized in that: The thickness of the volute (1) is b, and the maximum width of the air inlet (4) is b1, then b1≤b is satisfied.

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