Centrifugal fan

Abstract

The utility model discloses a centrifugal fan which 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 the volute ring wall is provided with an air inlet for air flow outside the volute to enter the flow channel. The volute is characterized in that at least three air inlets are distributed in the circumferential direction of the volute annular wall at intervals. Compared with the prior art, the centrifugal fan has the advantages that the air inlets are formed in the volute annular wall, the number of the air inlets is at least three, the air inlets are distributed in the circumferential direction of the volute annular wall at intervals, after the multiple air inlets are adopted, when the fan operates, airflow outside the fan enters a flow channel in the volute through the air inlets, the air inlet amount is increased, and the efficiency of the fan is improved.

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. The efficiency of the range hoods on the market is low, and sometimes they cannot meet the standard requirements. They need to be matched with high-efficiency DC motors to improve the efficiency, which is costly. In order to improve the efficiency of the fan, some centrifugal fans are equipped with air inlets on the volute ring wall. When the fan is working, the airflow outside the fan can enter the fan through the air inlet. For example, the "Fan volute middle plate guide vane air inlet structure of range hood" disclosed in the Chinese utility model patent with patent number CN201220666311.8 (authorization announcement number CN 203051230U) includes an annular middle plate connected to the front cover plate and the rear cover plate of the volute. The angle of the volute tongue at the front end of the annular middle plate is designed to prevent the air volume from not entering the outlet and flowing back to the volute at the optimal angle. An air inlet is provided at the rear end of the volute tongue, and an air inlet is provided at the rear end of the annular middle plate volute tongue. 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, thereby improving the fan efficiency and increasing the air volume at the outlet. Although this structure has a certain effect on improving the absorption of oil smoke, since only one air inlet is set near the volute tongue, the air inlet volume is effectively increased, but the fan effect is not significantly improved. Utility Model Content

[0003] The technical problem to be solved by the utility model is to provide a centrifugal fan with large air intake volume and high fan efficiency in view of the above-mentioned existing technical status.

[0004] The technical solution adopted by the utility model to solve the above technical problems is: a centrifugal fan, including a volute, an impeller arranged inside the volute and a volute tongue arranged at the volute outlet, the volute having a volute ring wall, a flow channel formed between the volute ring wall and the impeller, an air inlet for the airflow outside the volute to enter the flow channel is opened on the volute ring wall, and the utility model is characterized in that: there are at least three air inlets and they are distributed at intervals along the circumference of the volute ring wall.

[0005] As a preferred solution, the air inlets are evenly spaced.

[0006] As another preferred solution, along the flow direction of the airflow in the flow channel, the distance between adjacent air inlets increases gradually.

[0007] Further preferably, the opening diameters of the air inlets are gradually increased along the airflow direction in the flow channel. Since the airflow velocity gradually increases along the airflow direction of the flow channel, increasing the diameter of the air inlet along the airflow direction can also achieve a better air intake effect.

[0008] Preferably, the air inlets have the same shape and the same opening diameter.

[0009] The air inlet can have a variety of different shapes, preferably, the air inlet is square or circular. In addition, the air inlet can also adopt other different shapes such as diamond, triangle, polygon, etc.

[0010] The most upstream air inlet can be set at multiple different positions of the circumference of the volute ring wall. 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, and the straight line passing through the upstream edge of the air inlet closest to the volute tongue and the center of the impeller is N. The angle α between the straight line M and the straight line N satisfies 1°≤α≤50°. 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 while reducing costs.

[0011] 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, for the same air inlet, the straight line between the upstream edge of the air inlet and the center of the impeller is P, and the straight line between the downstream edge of the air inlet and the center of the impeller is Q, then the angle between the straight line P and the straight line Q is θ, and 5°<θ≤60°.

[0012] Further preferably, the thickness of the volute is b, and the maximum width of the air inlet is b1, then b1≤b is satisfied.

[0013] Compared with the prior art, the advantages of the utility model are that the centrifugal fan is provided with an air inlet on the volute ring wall, and there are at least three air inlets which are distributed at intervals along the circumference of the volute ring wall. After adopting multiple air inlets, when the fan is running, the airflow outside the fan enters the flow channel inside the volute through the air inlet, thereby increasing the air intake volume and helping to improve the efficiency of the fan. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic structural diagram of a centrifugal fan according to an embodiment of the utility model (without the impeller);

[0015] Figure 2 This is a structural cross-sectional view of a centrifugal fan according to an embodiment of the utility model;

[0016] Figure 3 A structural cross-sectional view of a volute of an embodiment of the utility model;

[0017] Figure 4 It is a top view of the centrifugal fan according to an embodiment of the utility model. DETAILED DESCRIPTION

[0018] The present invention will be described in further detail below in conjunction with the accompanying drawings.

[0019] like Figures 1 to 4 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 5 is formed between the volute ring wall 11 and the impeller 2. An air inlet 4 is opened on the volute ring wall 11. When the impeller 2 rotates, the airflow outside the volute 1 enters the flow channel 5 through the air inlet 4, and then is discharged out of the fan together with the airflow sucked from the main air inlet of the fan.

[0020] In this embodiment, there are multiple air inlets 4 that are evenly spaced along the circumference of the volute ring wall 11. The air inlets 4 are square and have equal opening diameters. The shape of the air inlet 4 is not limited to square. In addition to square, other different shapes such as circle, diamond, triangle, polygon, etc. can also be used.

[0021] Since the air flow velocity gradually increases along the air flow direction in the flow channel, the spacing between adjacent air inlets 4 can also be gradually increased along the air flow direction, and the opening diameter of each air inlet 4 can also be increased one by one. Therefore, each air inlet 4 can obtain a better air intake effect, which is beneficial to improving the overall efficiency of the fan.

[0022] like Figure 2 As shown, on a plane perpendicular to the central axis of the impeller 2 and passing through the center of the impeller 2, the straight line passing through the tip of the volute tongue 3 and the center of the impeller 2 is M, the straight line passing through the upstream edge of the air inlet 4 closest to the volute tongue and the center of the impeller 2 is N, and the angle α between the straight line M and the straight line N satisfies 1°≤α≤50°. The smaller the angle α, the closer the opening position of the air inlet 4 is to the volute tongue 3, the greater the air intake of the air inlet 4, and the higher the fan efficiency.

[0023] On a plane perpendicular to the central axis of the impeller 2 and passing through the center of the impeller 2, for the same air inlet 4, the straight line between the upstream edge of the air inlet 4 and the center of the impeller 2 is P, and the straight line between the downstream edge of the air inlet 4 and the center of the impeller 2 is Q, then the angle between the straight line P and the straight line Q is θ, then 5°<θ≤60°. The angle θ reflects the opening size of the air inlet 4, which needs to be limited to a suitable range. If it is too large or too small, it will not have a good air intake effect.

[0024] like Figure 4 As shown, the thickness b of the volute 1 and the maximum width b1 of the air inlet 4 satisfy b1≤b.

[0025] 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 an outlet of the volute (1), the volute (1) having a volute ring wall (11), a flow channel (5) formed between the volute ring wall (11) and the impeller (2), an air inlet (4) for allowing airflow outside the volute to enter the flow channel is opened on the volute ring wall (11), and the characteristics are: There are at least three air inlets (4) which are distributed at intervals along the circumference of the volute ring wall.

2. The centrifugal fan according to claim 1, characterized in that: The air inlets (4) are evenly spaced.

3. The centrifugal fan according to claim 1, characterized in that: Along the flow direction of the airflow in the flow channel, the distance between adjacent air inlets (4) gradually increases.

4. The centrifugal fan according to claim 1, characterized in that: Along the flow direction of the airflow in the flow channel, the opening diameters of the air inlets (4) increase one by one.

5. The centrifugal fan according to claim 1, characterized in that: The air inlets (4) have the same shape and the same opening diameter.

6. The centrifugal fan according to claim 5, characterized in that: The air inlets (4) are all square or circular.

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) closest to the volute tongue 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≤50°.

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), for the same air inlet (4), the straight line between the upstream edge of the air inlet (4) and the center of the impeller (2) is P, and the straight line between the downstream edge of the air inlet (4) and the center of the impeller (2) is Q, then the angle between the straight line P and the straight line Q 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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