Centrifugal fan

Abstract

A centrifugal fan comprises a volute, an impeller and a volute tongue, an air inlet is formed in the annular wall of the volute, an air guide piece is installed at the air inlet, the root of the air guide piece is arranged at the starting position of the air inlet, the air guide piece extends from the root to the interior of the volute, the length of the air guide piece is a, and the arc length corresponding to the air inlet is L, namely 0 lt; a < lt >; on a plane which is perpendicular to the central axis of the impeller and passes through the center of the impeller, the straight line passing through the position between the tongue tip of the volute tongue and the center of the impeller is M, the straight line passing through the position between the initial position of the air inlet and the center of the impeller is N, and the included angle alpha between the straight line M and the straight line N is larger than or equal to 1 degree and smaller than or equal to 350 degrees. According to the centrifugal fan, the air guide piece is installed at the air inlet of the volute annular wall, the length of the air guide piece and the corresponding arc length of the air inlet meet the set relation, the air inlet can be formed in different positions in the circumferential direction of the volute annular wall, and the closer the air inlet is to the volute tongue, the larger the air inlet amount of the air inlet is. According to the structure, the efficiency of the fan can be improved on the basis of reducing the cost.

Description

Technical Field

[0001] The present invention relates to a fan, and more particularly to a centrifugal fan. Background Art

[0002] Centrifugal fans have been widely used in range hoods due to their advantages such as large suction force, low noise, and compact structure. The volute is one of the core components of a centrifugal fan, and its function is to concentrate the gas leaving the impeller, lead it to the volute outlet, and convert the dynamic pressure into static pressure. The fans of range hoods generally use centrifugal fans. In order to improve efficiency, it is usually necessary to be equipped with a high-efficiency DC motor, which has a high cost. In addition, the existing centrifugal fan has a single air inlet, which has certain limitations. In order to improve the oil fume suction effect and the performance of the range hood, the air inlet can be increased. For example, the "Air Inlet Structure of the Guide Vane in the Middle Plate of the Fan Volute of a Range Hood" disclosed in the Chinese utility model patent with the patent number CN201220666311.8 (the authorized announcement number is CN 203051230 U) includes an annular middle plate connected to the front cover plate and the rear cover plate of the volute. The volute tongue angle 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 again at an optimal angle. An air inlet is opened at the rear end of the volute tongue, and an air inlet is opened at the rear end of the volute tongue of the annular middle plate. After the blades of the impeller pass through the volute tongue, the air flow is immediately introduced through the air inlet by 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 fume suction, there may be a backflow phenomenon, and the improvement of the fan efficiency is relatively limited. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a centrifugal fan that improves the fan efficiency by arranging guide vanes at the opening of the volute ring wall in view of the above-mentioned prior art status.

[0004] The technical solution adopted by the present invention to solve the above technical problem is as follows: The centrifugal fan includes a volute, an impeller disposed inside the volute, and a volute tongue disposed at the volute outlet. An air inlet is opened on the volute ring wall. It is characterized in that: guide vanes are installed at the air inlet, the root of the guide vanes is disposed at the starting position of the air inlet, the guide vanes extend from the root into the volute interior, the length of the guide vanes is a, and the arc length corresponding to the air inlet is L, then 0 < a < 5L. In a plane perpendicular to the impeller central axis and passing through the impeller center, taking the straight line passing through the tip of the volute tongue and the impeller center as M, and the straight line passing through the starting position of the air inlet and the impeller center as N, the included angle α between the straight line M and the straight line N satisfies 1° ≤ α ≤ 350°.

[0005] Preferably, the angle between the guide vanes and the volute tangent at the starting position of the air inlet on the volute ring wall is β, 0 < β ≤ 120°. When the guide vanes are designed at the above inclination angle, the air inlet effect is better, and the effect of improving the fan performance is obvious.

[0006] As another preferred solution, the air guide includes a first air guide and a second air guide that are bent to each other, the root of the first air guide is arranged at the starting position of the air inlet, and the second air guide is bent upward and extended from the head of the first air guide. In this way, the two air guides are arranged relative to the one air guide, and the second air guide is close to the direction of the fluid track line, the fluid is smoother, backflow is not easy to occur, the air intake is larger, and the fan efficiency is higher.

[0007] The first air guide vane and the second air guide vane may have different included angles. Preferably, the included angle between the first air guide vane and the second air guide vane is 90<γ≤180°.

[0008] Further preferably, the angle α satisfies 1°≤α≤180°. Through research and testing, it is found that the closer the position of the volute opening is to the position of the volute tongue, the greater the air intake of the air inlet is, and the higher the fan efficiency is.

[0009] In order to ensure the air volume 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 starting position of the air inlet and the center of the impeller is P, and the straight line between the end position of the air inlet and the center of the impeller is Q. The angle between the straight line P and the straight line Q is θ, then 5°<θ≤60°

[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 head of the air guide blade and the center of the impeller is R, and the straight line between the end position of the air inlet and the center of the impeller is Q, then the angle between the straight line R and the straight line Q is δ, then 1°<δ≤30°. The angle δ is limited to the above range, that is, the length of the air guide blade is not much different from the arc length of the air inlet, the airflow outside the volute can enter the inside of the volute more smoothly, and the air intake effect is better.

[0011] In order to reduce the noise at the air inlet, the head edge of the air guide piece is formed with a wave structure or a sawtooth structure.

[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] In order to increase the total amount of air intake, there are at least two air inlets, which are circumferentially spaced and distributed along the volute ring wall.

[0014] Compared with the prior art, the advantages of the present invention are: the centrifugal fan is equipped with an air guide vane at the air inlet of the volute ring wall, the length of the air guide vane satisfies a set relationship with the corresponding arc length of the air inlet, 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 this air inlet. This structure can improve the fan efficiency on the basis of reducing costs. The range hood using this centrifugal fan is beneficial to improving the performance of the range hood and has a better fume extraction effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic structural diagram of a range hood according to Embodiment 1 of the present invention;

[0016] Figure 2 This is a schematic structural diagram of a centrifugal fan according to Embodiment 1 of the present invention;

[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 2 A top view of the centrifugal fan shown;

[0020] Figure 6 This is a schematic structural diagram of a centrifugal fan according to Embodiment 2 of the present invention;

[0021] Figure 7 for Figure 6 A structural cross-sectional view of a centrifugal fan shown;

[0022] Figure 8 for Figure 7 A magnified schematic diagram of part B;

[0023] Fig. 9 This is a schematic structural diagram of a centrifugal fan according to Embodiment 3 of the present invention;

[0024] Fig.10 for Fig. 9 A top view of a centrifugal fan is shown. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below with reference to the accompanying drawings.

[0026] Embodiment 1:

[0027] like Figures 1 to 5As shown in the figure, the centrifugal fan of this embodiment includes a volute 1, an impeller 2 disposed inside the volute 1, and a volute tongue 3 disposed at the outlet of the volute 1. An air inlet 4 is formed on the annular wall 11 of the volute, and a guide vane 5 is installed at the air inlet 4. The root of the guide vane 5 is disposed at the starting position of the air inlet 4, and the guide vane 5 extends from the root into the volute 1. As Figure 4 shown, let the length of the guide vane 5 be a, and the arc length corresponding to the air inlet 4 be L, then 0 < a < 5L is satisfied. As Figure 3 shown, in a 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 starting position 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 larger the air intake volume of the air inlet 4, and the higher the fan efficiency.

[0028] As Figure 3 shown, in a 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 starting position of the air inlet 4 and the center of the impeller 2 as N, and the straight line passing through the ending position of the air inlet 4 and the center of the impeller 2 as Q, then the included angle between the straight line N and the straight line Q 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. If it is too large or too small, a good air intake effect cannot be achieved. Taking the straight line passing through the head of the guide vane 5 and the center of the impeller 2 as P, and the straight line passing through the ending position of the air inlet 4 and the center of the impeller 2 as Q, then the included angle between the straight line P and the straight line Q is δ, then 1° < δ ≤ 30°. The angle δ reflects that the length of the guide vane 5 is not much different from the arc length of the air inlet 3, and the external air flow of the volute can enter the volute interior more smoothly, and the air intake effect is better. The guide vane 5 can be longer than the arc length of the air inlet 4 or shorter than the arc length of the air inlet 4. In this embodiment, the guide vane 5 is shorter than the arc length of the air inlet 4.

[0029] As Figure 4 shown, the angle between the guide vane 5 and the tangent of the volute 1 at the starting position of the air inlet 4 on the annular wall 11 of the volute is β, 0 < β ≤ 120°. The larger the angle β, the greater the bending angle of the guide vane 5, and the more obvious the flow guiding effect, but generally it does not exceed 120° at most, otherwise a good flow guiding effect cannot be achieved.

[0030] As Figure 5 shown, the thickness of the volute 1 is b, and the maximum width of the air inlet 4 is b1, then b1 ≤ b is satisfied.

[0031] In this embodiment, there is one air inlet 4, and a structure of multiple air inlets 4 can also be adopted, and the air inlets 4 are distributed at intervals along the circumferential direction of the volute ring wall 11. The shape of the opening can be square, diamond, triangle, trapezoid, polygon, circle, ellipse, irregular shape, etc. The number of air guide blades 5 can also be multiple, which can be equal to the number of air inlets 4, or less or more than the number of air inlets 4.

[0032] Embodiment 2:

[0033] like Figures 6 to 8 As shown, the air guide piece 5 of this embodiment includes a first air guide piece 51 and a second air guide piece 52 that are bent to each other. The root of the first air guide piece 51 is arranged at the starting position of the air inlet 4, and the second air guide piece 52 is bent upward and extended from the head of the first air guide piece 51. In this way, the two sections of air guide pieces are arranged relative to one section of air guide piece. The second air guide piece is close to the direction of the fluid track line, the fluid is smoother, it is not easy to generate backflow, the air intake is larger, and the fan efficiency is higher. In this embodiment, the angle between the first air guide piece 51 and the second air guide piece 52 is 90<γ≤180°.

[0034] Embodiment three:

[0035] like Fig. 9 and Fig.10 As shown, in this embodiment, the head edge of the air guide piece 5 is formed with a wave structure or a sawtooth structure. After the wave structure or the sawtooth structure is set at the head of the air guide piece 5, the noise there can be effectively reduced.

[0036] 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), an air inlet (4) being opened on the volute ring wall (11), characterized in that: A wind guiding vane (5) is installed at the air inlet (4). The root of the wind guiding vane (5) is located at the starting position of the air inlet (4). The wind guiding vane (5) extends from the root into the volute (1). The length of the wind guiding vane (5) is a, and the arc length corresponding to the air inlet (4) is L. Then 0 < a < 5L. 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 starting position 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°.

2. The centrifugal fan according to claim 1, characterized in that: The angle between the wind guiding vane (5) and the tangent of the volute (1) at the starting position of the air inlet (4) of the volute wall (11) is β, and 0 < β ≤ 120°.

3. The centrifugal fan according to claim 2, characterized in that: The wind guiding vane (5) includes a first wind guiding vane (51) and a second wind guiding vane (52) which are bent with each other. The root of the first wind guiding vane (51) is located at the starting position of the air inlet (4). The second wind guiding vane (52) extends upward and bends from the head of the first wind guiding vane (51).

4. The centrifugal fan according to claim 3, characterized in that: The included angle γ between the first wind guiding vane (51) and the second wind guiding vane (52) satisfies 90 < γ ≤ 180°.

5. The centrifugal fan according to claim 1, characterized in that: The included angle α satisfies 1° ≤ α ≤ 180°.

6. The centrifugal fan according to claim 1, characterized in that: 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 starting position of the air inlet (4) and the center of the impeller (2) as N, and the straight line passing through the ending position of the air inlet (4) and the center of the impeller (2) as Q, the included angle between the straight line N and the straight line Q is θ. Then 5° < θ ≤ 60°.

7. The centrifugal fan according to claim 6, characterized in that: 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 head of the wind guiding vane (5) and the center of the impeller (2) as P, and the straight line passing through the ending position of the air inlet (4) and the center of the impeller (2) as Q, the included angle δ between the straight line P and the straight line Q satisfies 1° < δ ≤ 30°.

8. The centrifugal fan according to claim 1, characterized in that: The head edge of the wind guiding vane (5) is formed with a wave structure or a sawtooth structure.

9. The centrifugal fan according to claim 1, 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.

10. The centrifugal fan according to claim 1, characterized in that: There are at least 2 air inlets (4), which are circumferentially and spacedly distributed along the volute wall (11).

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