A centrifugal fan

Abstract

A centrifugal fan includes a volute, an impeller and a volute tongue. An air inlet is formed on the circumferential wall of the volute. A guide vane is installed at the air inlet. The root of the guide vane is located at the starting position of the air inlet. The guide vane extends from the root into the volute interior. The length of the guide vane is a, and the arc length corresponding to the air inlet is L, then 0 < a < 5L. On the plane perpendicular to the impeller axis and passing through the impeller center, taking the straight line between the tip of the volute tongue and the impeller center as M, and the straight line between 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°. This centrifugal fan installs a guide vane at the air inlet of the circumferential wall of the volute. The length of the guide vane and the arc length corresponding to the air inlet satisfy a set relationship. The air inlet can be arranged circumferentially on the circumferential wall of the volute at different positions, and the closer the position of the air inlet is to the volute tongue, the greater the air intake of this air inlet. This structure can improve the fan efficiency while reducing the cost.

Description

Technical Field

[0001] The present invention relates to a fan, particularly 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, resulting in 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 the 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 the optimal angle. An air inlet is opened at the rear end of the volute tongue, and an air inlet is also opened at the rear end of the volute tongue of the annular middle plate. After the air blades of the impeller pass through the volute tongue, the air flow is immediately introduced through the air inlet and the air inlet guide plate, improving the fan efficiency and increasing the air volume at the outlet. 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 setting 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 outlet of the volute. 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 vane is disposed at the starting position of the air inlet. The guide vane extends from the root into the volute interior. The length of the guide vane 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 included angle between the guide vane 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 vane is 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 embodiment, the air guide vane includes a first air guide vane and a second air guide vane that are bent against each other. The root of the first air guide vane is located at the beginning of the air inlet, and the second air guide vane extends upward from the head of the first air guide vane. With this arrangement, the second air guide vane is closer to the direction of the fluid trajectory than the first air guide vane, resulting in smoother fluid flow, less backflow, more air intake, and higher fan efficiency.

[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 optimization shows that the included angle α satisfies 1°≤α≤180°. Research and testing have verified that the closer the opening of the volute is to the volute tongue, the greater the air intake volume and the higher the fan efficiency.

[0009] To ensure the air intake volume, on a plane perpendicular to the impeller's central axis and passing through the impeller's center, let P be the straight line between the starting position of the air intake and the impeller center, and Q be the straight line between the ending position of the air intake and the impeller center. Then, the angle between lines P and Q is θ, where 5° < θ ≤ 60°.

[0010] Further optimization involves defining a plane perpendicular to the impeller's central axis and passing through the impeller's center. Let R be the straight line between the guide vane head and the impeller center, and Q be the straight line between the end of the air inlet and the impeller center. The angle between line R and line Q is δ, where 1° < δ ≤ 30°. This angle δ is limited to the aforementioned range, meaning the length of the guide vane and the arc length of the air inlet are not significantly different. This allows the airflow outside the volute to enter the volute more smoothly, resulting in better air intake.

[0011] To reduce noise at the air inlet, the head edge of the air guide vane is formed with a wave structure or a sawtooth structure.

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

[0013] To increase the total air intake, there are at least two air inlets, which are spaced apart along the circumferential wall of the volute.

[0014] Compared with the prior art, the advantages of the present invention are as follows: the centrifugal fan has an air guide plate installed at the air inlet of the volute ring wall. The length of the air guide plate and the corresponding arc length of the air inlet satisfy a set relationship. The air inlet can be arranged at different positions along the circumference of the volute ring wall. The closer the air inlet is to the volute tongue, the greater the air volume of the air inlet. This structure can improve the efficiency of the fan while reducing costs. The range hood using this centrifugal fan is conducive to improving the performance of the range hood and has a better smoke extraction effect. Attached Figure Description

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

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

[0017] Figure 3 for Figure 2 The diagram shows a cross-sectional view of the centrifugal fan.

[0018] Figure 4 for Figure 3 An enlarged schematic diagram of part A in the middle;

[0019] Figure 5 for Figure 2 A top view of the centrifugal fan shown;

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

[0021] Figure 7 for Figure 6 The diagram shows a cross-sectional view of the centrifugal fan.

[0022] Figure 8 for Figure 7 Enlarged schematic diagram of part B in the middle;

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

[0024] Figure 10 for Figure 9 The image shows a top view of the centrifugal fan. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0026] Example 1:

[0027] like Figures 1 to 5As shown in the figure, the centrifugal fan of the present 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 provided on the circumferential wall 11 of the volute. 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, 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°, 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, 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, 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 included angle between the guide vane 5 and the tangent of the volute 1 at the starting position of the air inlet 4 on the circumferential 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 guiding effect, but generally it does not exceed 120° at most, otherwise a good 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, but multiple air inlets 4 can also be used, and the air inlets 4 are distributed circumferentially along the volute annular wall 11. The shape of the opening can be square, rhomboid, triangular, trapezoidal, polygonal, circular, elliptical, irregular, etc. The number of air guide vanes 5 can also be multiple, which can be equal to, fewer than or more than the number of air inlets 4.

[0032] Example 2:

[0033] like Figures 6 to 8 As shown, the air guide 5 in this embodiment includes a first air guide 51 and a second air guide 52 that are bent towards each other. The root of the first air guide 51 is located at the starting position of the air inlet 4, and the second air guide 52 extends upward from the head of the first air guide 51. With this arrangement, the second air guide is closer to the fluid trajectory than the first air guide, resulting in smoother fluid flow, less backflow, more air intake, and higher fan efficiency. In this embodiment, the included angle between the first air guide 51 and the second air guide 52 is 90° < γ ≤ 180°.

[0034] Example 3:

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

[0036] The specification and claims of this invention use terms indicating direction, such as "front," "rear," "upper," "lower," "left," "right," "side," "top," and "bottom," to describe various exemplary structural parts and elements of the invention. However, these terms are used herein merely for ease of explanation and are determined based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed in this invention can be arranged in different orientations, these terms indicating direction are for illustrative purposes only and should not be considered as limitations. For example, "upper" and "lower" 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), a wind inlet (4) being formed in the ring wall (11) of the volute, characterized in that: The air guide vane (5) is arranged at the starting position of the air inlet (4), and the air guide vane (5) extends from the root to the inside of the volute (1). The length of the air guide vane (5) is a, the corresponding arc length of the air inlet (4) is L, and 0 < a < 5L. In the 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 tongue tip of the volute tongue (3) and the center of the impeller (2) is M, a straight line passing through the starting position of the air inlet (4) and the center of the impeller (2) is N, and the included angle α between the straight line M and the straight line N satisfies 1° ≤ α ≤ 350°. The angle β between the air guide vane (5) and the tangent of the volute (1) at the starting position of the air inlet (4) of the volute ring wall (11) satisfies 0 < β ≤ 120°. The air guide vane (5) comprises a first air guide vane (51) and a second air guide vane (52) which are bent relative to each other. The root of the first air guide vane (51) is arranged at the starting position of the air inlet (4), and the second air guide vane (52) is arranged by bending and extending upwards from the head of the first air guide vane (51). The included angle between the first air guide vane (51) and the second air guide vane (52) satisfies 90° < γ ≤ 180°.

2. The centrifugal fan of claim 1, wherein: The included angle α satisfies 1° ≤ α ≤ 180°.

3. The centrifugal fan of claim 1, wherein: In the 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 starting position of the air inlet (4) and the center of the impeller (2) is N, and a straight line passing through the end position of the air inlet (4) and the center of the impeller (2) is Q. The included angle θ between the straight line N and the straight line Q satisfies 5° < θ ≤ 60°.

4. The centrifugal fan of claim 3, wherein: In the 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 head of the air guide vane (5) and the center of the impeller (2) is P, and a straight line passing through the end position of the air inlet (4) and the center of the impeller (2) is Q. The included angle δ between the straight line P and the straight line Q satisfies 1° < δ ≤ 30°.

5. The centrifugal fan of claim 1, wherein: The head edge of the air guide vane (5) is shaped as a wave structure or a sawtooth structure.

6. The centrifugal fan of claim 1, wherein: The thickness of the volute (1) is b, and the maximum width of the air inlet (4) is b1, and b1 ≤ b is satisfied.

7. The centrifugal fan of claim 1, wherein: The air inlets (4) are at least two and are distributed along the volute ring wall (11) in a circumferential direction.

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