Axial flow fan and range hood comprising same

Abstract

The utility model relates to the field of range hoods, and discloses an axial flow fan and a range hood comprising the axial flow fan, the axial flow fan comprises two rows of moving blades and stationary blades, the two rows of moving blades are respectively front-row moving blades and rear-row moving blades, the front-row moving blades, the rear-row moving blades and the stationary blades are sequentially arranged along the flowing direction of fluid, the number and chord length of the front-row moving blades are less than those of the rear-row moving blades, and the chord length of the rear-row moving blades is longer than that of the rear-row moving blades. And the rear row of movable blades share pressure rise, and meanwhile, fluid can flow out more uniformly, so that the noise of fluid flowing can be reduced. Compared with a single-stage axial flow fan, the two rows of movable blades are arranged, under the condition that the same pressure rise needs to be achieved, the rotating speed can be smaller, and therefore noise is smaller; and under the condition of the same noise, larger pressure rise can be realized. Compared with a multi-stage axial flow fan, the two rows of movable blades are arranged on the upstream of the fixed blades, the movable blades and the fixed blades are not alternately arranged, and therefore the axial flow fan is simple in structure. Therefore, the axial flow fan can give consideration to both power and noise.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of range hood, especially to a axial flow fan. BACKGROUND

[0002] Forward intake multi-blade centrifugal fan (referred to as "centrifugal fan") is commonly used in range hood, the inlet and outlet paths of centrifugal fan are vertical, the airflow is forced to bend at right angles, which leads to the airflow passage being not smooth, reduces the energy efficiency of the range hood, and also increases the noise. By placing the centrifugal fan on top, installing it on the ceiling, the vertical characteristics of the inlet and outlet paths can be utilized, but the centrifugal fan has a volute, and the structure size is large, so the installation is limited.

[0003] In the range hood, axial flow fan is used, the axial flow fan does not have a volute, and the airflow enters and exits along the axial direction, so the volume is much smaller than that of the conventional centrifugal fan, and the layout freedom in the whole machine air duct is high, but the axial flow fan itself has the characteristics of large flow and small pressure rise, and under the same conditions, the pressure boosting capacity is not as good as that of the centrifugal fan. By using multi-stage axial flow fan, the pressure rise of the axial flow fan can be improved, but the multi-stage axial flow fan has a structure of alternating multiple dynamic blades and static blades, which makes the structure design complex and increases the processing and assembly costs.

[0004] In summary, the existing range hood has poor comprehensive performance, and it is difficult to balance the needs of compact fan structure, good aerodynamic performance, low noise, easy installation and the like. INVENTION CONTENTS

[0005] The technical problem to be solved by the utility model is to overcome the defect of poor comprehensive performance of the range hood in the prior art, and to provide an axial flow fan and a range hood comprising the same.

[0006] The utility model solves the above technical problem by the following technical scheme:

[0007] An axial flow fan comprises two kinds of blades, dynamic blades and static blades, the dynamic blades have two rows, which are front-row dynamic blades and rear-row dynamic blades, and the front-row dynamic blades, the rear-row dynamic blades and the static blades are sequentially arranged along the fluid flow direction, and the number and chord length of the front-row dynamic blades are less and longer than those of the rear-row dynamic blades.

[0008] In the scheme, the two rows of dynamic blades are arranged, and the rear-row dynamic blades can share the pressure rise, so that the first aspect can reduce the manufacturing and load requirements of the single-row dynamic blades, the second aspect can achieve smaller rotation speed and smaller noise compared with the single-stage axial flow fan under the condition of achieving the same pressure rise, and the third aspect can achieve larger pressure rise under the condition of the same noise compared with the multi-stage axial flow fan with alternating arrangement of dynamic blades and static blades, the two rows of dynamic blades are arranged upstream of the static blades, and the dynamic blades and the static blades are not arranged alternately, so that the axial flow fan has a simple structure.

[0009] By setting the chord length ratio of the front row of moving blades to the rear row of moving blades, sufficient chord length is provided for the front row of moving blades to be set to achieve a larger pressure rise; compared with the case of the same or similar chord length and number of the two rows of moving blades, the rear row of moving blades is set to be shorter, and the axial length of the axial flow fan is also reduced. The number of the rear row of moving blades is set to be more than that of the front row of moving blades, so that the rear row of moving blades can share the pressure rise and make the fluid flow out more uniformly, thereby reducing the noise of fluid flow; at the same time, the chord length of the rear row of moving blades is set to be shorter than that of the front row of moving blades, so that the density at the front row of moving blades and the density at the rear row of moving blades are close, and the stability of flow is improved.

[0010] In addition, the axial flow fan itself has the advantages of compact structure and convenient installation, so that the axial flow fan can meet the requirements of large power, small noise, compact structure, convenient installation and the like.

[0011] Preferably, the number of the stationary blades is two rows, i.e., a front row of stationary blades and a rear row of stationary blades, and the front row of moving blades, the rear row of moving blades, the front row of stationary blades and the rear row of stationary blades are sequentially arranged along the fluid flow direction, and the number and chord length of the front row of stationary blades are less and longer than those of the rear row of stationary blades, respectively.

[0012] In the present scheme, by setting the chord length of the front row of stationary blades to be longer than that of the rear row of stationary blades, sufficient chord length is provided for the front row of stationary blades to be set to achieve a good effect of guiding and deflecting fluid. The number of the rear row of stationary blades is set to be more than that of the front row of stationary blades, so that the rear row of stationary blades can continue to guide and deflect fluid, and make the fluid flow out more uniformly, thereby reducing the noise of fluid flow; at the same time, the chord length of the rear row of stationary blades is set to be shorter than that of the front row of stationary blades, so that the density at the front row of stationary blades and the density at the rear row of stationary blades are close, and the stability of flow is improved.

[0013] Preferably, in the same kind of two rows of blades, the ratio of the number of the rear row of blades to the front row of blades is between 2 and 4.

[0014] In the present scheme, by setting the number of the rear row of blades to be sufficient, the uniformity of fluid flow out is good, and the noise is small; and by setting the number of the rear row of blades to be sufficient, the difficulty and cost of processing and manufacturing the axial flow fan are reduced.

[0015] Preferably, in the same kind of two rows of blades, the number of the rear row of blades is an integer multiple of the number of the front row of blades.

[0016] In the present scheme, by setting the circumferential distance between the front row of blades and the rear row of blades of the same kind to be constant, the uniformity of flow field along the circumferential direction is improved.

[0017] Preferably, in the same kind of two rows of blades, the ratio of the average density of the front row of blades to the rear row of blades is between 0.9 and 1.3.

[0018] In the scheme, the flow field between the same blades and between the front and rear rows of blades is relatively uniform in the axial direction, so that the stability of fluid flow is improved, and the pressure rise performance is improved and the noise is reduced.

[0019] Preferably, the ratio of the average solidity of the front row of blades to the average solidity of the rear row of blades is between 1 and 1.2.

[0020] Preferably, in the two rows of the same blades, the tail end of the front row of blades is close to the front end of the rear row of blades in the circumferential direction and / or the axial direction of the axial flow fan.

[0021] In the scheme, the fluid is smoothly transitioned from the front row of blades to the rear row of blades, and the fluid is inhibited from separating from the surface of the rear row of blades.

[0022] Preferably, the distance between the two rows of the same blades in the axial direction of the axial flow fan is between -10mm and 10mm.

[0023] In the scheme, the distance between the two rows of blades in the axial direction is small enough to smoothly transition the fluid from the front row of blades to the rear row of blades and inhibit the fluid from separating from the surface of the rear row of blades, and the distance between the two rows of blades in the axial direction is large enough to facilitate processing and manufacturing.

[0024] Preferably, the distance between the two rows of the same blades in the axial direction of the axial flow fan is between -5mm and 5mm.

[0025] Preferably, in the two rows of the same blades, the circumferential distance between the tail end of the pressure surface of the front row of blades and the front end of the suction surface of the rear row of blades is between 0 and 10mm.

[0026] In the scheme, the distance between the two rows of blades in the circumferential direction is small enough to smoothly transition the fluid from the front row of blades to the rear row of blades and inhibit the fluid from separating from the surface of the rear row of blades.

[0027] Preferably, in the two rows of the same blades, the circumferential distance between the tail end of the pressure surface of the front row of blades and the front end of the suction surface of the rear row of blades is between 0 and 5mm.

[0028] Preferably, the outlet angle of the blade root of the rear row of moving blades is smaller than the outlet angle of the blade root of the front row of moving blades.

[0029] In the scheme, the rear row of moving blades further works on the fluid.

[0030] Preferably, in the two rows of the same blades, the absolute value of the deflection angle of the front row of blades is greater than the absolute value of the deflection angle of the rear row of blades.

[0031] In the scheme, the front row of vanes is arranged to generate a pressure rise or a fluid guiding and deflecting effect greater than that of the rear row of vanes, so that the load of the rear row of vanes can be reduced, and the complexity of the rear row of vane profiles can be reduced to facilitate processing and manufacturing.

[0032] Preferably, the number of the front row of vanes is less than or equal to 0.5 times the number of the rear row of vanes.

[0033] In the scheme, the number of the front row of vanes is reduced to reduce the resistance of the front row of vanes to fluid flow and reduce noise.

[0034] Preferably, the minimum axial distance between the rear row of vanes and the vanes along the axial flow fan is 0.5-1.5 times the axial distance between the front end of the front row of vanes and the tail end of the rear row of vanes.

[0035] In the scheme, the axial distance between the tail end of the rear row of vanes and the front end of the vanes is long enough to make the fluid mixed uniformly before flowing to the vanes, reducing the noise of the moving and static interference; on the other hand, the axial distance between the vanes and the vanes is small enough to make the axial size of the axial flow fan small enough and the structure compact.

[0036] Preferably, the minimum axial distance between the rear row of vanes and the vanes along the axial flow fan is 0.75 times the axial distance between the front end of the front row of vanes and the tail end of the rear row of vanes.

[0037] Preferably, the axial flow fan further comprises a rotating shaft, a support, a motor, and a housing, a flow channel is formed between the inner surface of the housing and the outer surface of the rotating shaft and the support, the vanes are arranged in the flow channel, the moving vanes are fixed on the rotating shaft and form a gap with the inner surface of the housing, the support is fixed on the housing through the vanes, and the motor is installed in the support to drive the rotating shaft to rotate.

[0038] In the scheme, the rotating shaft and the motor are supported by the vanes, and the structure is simple. In addition, when two rows of vanes are arranged, multi-point support can be formed, and the axial support length can be increased, thereby improving the stability of the support.

[0039] An oil smoke machine comprises the axial flow fan according to any one of the above technical schemes, and the inlet of the axial flow fan is the air inlet of the oil smoke machine or communicates with the air inlet of the oil smoke machine, and the outlet of the axial flow fan is the air outlet of the oil smoke machine or communicates with the air outlet of the oil smoke machine.

[0040] In the scheme, the axial flow fan of the utility model is applied to the oil smoke machine, which can meet the requirements of large power, small noise, compact structure, easy installation and the like, and improve the comprehensive performance of the oil smoke machine.

[0041] The positive progress effect of the utility model lies in that:

[0042] The two rows of dynamic blades are arranged, and the rear row of dynamic blades can share the pressure rise, so that the requirements for manufacturing and load of the single row of dynamic blades are reduced, and the rotation speed is smaller than that of the single-stage axial flow fan under the same pressure rise, so that the noise is smaller, and a larger pressure rise can be achieved under the same noise.

[0043] The chord length of the front row of dynamic blades is longer than that of the rear row of dynamic blades, so that there is enough chord length for the front row of dynamic blades to set the blade shape to achieve a larger pressure rise; compared with the case that the chord lengths and the number of the two rows of dynamic blades are the same or close, the rear row of dynamic blades is set to be shorter, which is also convenient for reducing the axial length of the axial flow fan.

[0044] In addition, the axial flow fan itself has the advantages of compact structure and convenient installation, so that the axial flow fan can meet the requirements of large power, small noise, compact structure, convenient installation and the like.

[0045] The axial flow fan with good comprehensive performance is used in the range hood, so that the comprehensive performance of the range hood can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 It is a schematic view of the axial flow fan.

[0047] Figure 2 It is a schematic view of the blade.

[0048] Figure 3 It is a schematic view of the flow rate comparison.

[0049] Figure 4 It is a schematic view of the distance marking.

[0050] Figure 5 It is a schematic view of the speed marking.

[0051] Figure 6 It is a schematic view of the axial flow fan section.

[0052] Explanation of reference signs:

[0053] The axial flow fan 1000;

[0054] The blade 1;

[0055] Moving blades 11, front row moving blades 111, rear row moving blades 112;

[0056] Stationary blades 12, front row stationary blades 121, rear row stationary blades 122;

[0057] Housing 2;

[0058] Rotating shaft 3;

[0059] Support 4;

[0060] Flow channel 5. DETAILED DESCRIPTION

[0061] The utility model will be further illustrated by way of examples below, but the utility model is not limited to the scope of the examples described.

[0062] The oil fume machine provided in the embodiment adopts an axial flow fan, the axial flow fan is arranged in the air duct of the oil fume machine, the inlet of the axial flow fan is communicated with the air inlet of the oil fume machine, and the outlet of the axial flow fan is communicated with the air outlet of the oil fume machine. Figures 1-2 , Figures 4-6 The axial flow fan 1000 in the embodiment is shown in the figure.

[0063] As Figure 1 , Figure 2 The axial flow fan 1000 includes moving blades 11 and stationary blades 12, and each of the two kinds of blades 1 has two rows. Figure 1 The axis of the axial flow fan 1000 is shown by L in the figure, the arrow points to the direction from the inlet to the outlet of the axial flow fan 1000, and the fluid flows along the direction L in the axial flow fan 1000. Along the direction L, the front row moving blades 111, the rear row moving blades 112, the front row stationary blades 121 and the rear row stationary blades 122 are arranged in sequence, the front row moving blades 111 are fewer in number and longer in chord length than the rear row moving blades 112, and the front row stationary blades 121 are also fewer in number and longer in chord length than the rear row stationary blades 122, that is, in the same kind of blades 1, the front row blades 1 are long and few, and the rear row blades 1 are short and many.

[0064] The same kind of blade 1 is provided with two rows, the performance requirement of the front row of blades 1 can be shared by the rear row of blades 1, the rear row of moving blades 112 can share the pressure rise, the rear row of stationary blades 122 can further guide and deflect the airflow, and the manufacturing, load and other requirements of the single row of blades 1 can be reduced. The two rows of moving blades 11 are provided, compared with the single-stage axial flow fan, the rotating speed can be smaller under the same pressure rise, so that the noise is smaller, and under the same noise, a larger pressure rise can be realized; meanwhile, the two rows of stationary blades 12 are provided, compared with the two-stage axial flow fan with the moving blades 11 and the stationary blades 12 arranged alternately, the two rows of moving blades 11 are all arranged on the upstream of the stationary blades 12, and the moving blades 11 and the stationary blades 12 are not arranged alternately, so that the axial flow fan 1000 is simple in structure.

[0065] The chord length of the front row of blades 1 in the same kind of blade 1 is longer than that of the rear row of blades 1, so that there is sufficient chord length for the front row of blades 1 to be provided with a blade shape to realize a larger pressure rise or a sufficient good airflow deflection guiding effect; compared with the case that the chord length and the number of the two rows of blades 1 are the same or close, the rear row of blades 1 is shorter, and the axial length of the axial flow fan 1000 can be further reduced.

[0066] The number of the rear row of blades 1 in the same kind of blade 1 is more than that of the front row of blades 1, the rear row of blades 1 can make the fluid flow out more uniformly while sharing the pressure rise or the airflow deflection requirement, so that the noise of the fluid flow can be reduced; meanwhile, the chord length of the rear row of blades 1 in the same kind of blade 1 is shorter than that of the front row of blades 1, and the solidity at the front row of blades 1 and the solidity at the rear row of blades 1 can be close, so that the stability of the flow can be improved.

[0067] In addition, the axial flow fan 1000 itself has the advantages of compact structure and convenient installation, and the axial flow fan 1000 is applied in the range hood, so that the range hood can meet the requirements of large power, small noise, compact structure, convenient installation and the like.

[0068] As Figure 1 , the axial flow fan 1000 further includes a rotating shaft 3, a support piece 4, a motor, a shell 2, a flow channel 5 is formed between the inner surface of the shell 2 and the outer surface of the rotating shaft 3 and the support piece 4, the blade 1 is arranged in the flow channel 5, the two rows of moving blades 11 are fixed on the rotating shaft 3 and form a gap with the inner surface of the shell 2, one end of the two rows of stationary blades 12 in the radial direction is fixed on the support piece 4, and the other end is fixed on the shell 2, the motor is installed in the support piece 4 and is power-connected with the rotating shaft 3 to drive the rotating shaft 3 to rotate. The support is realized by the stationary blades 12, and the structure is simple. In addition, the two rows of stationary blades 12 can form multi-point support, and the support length of the two rows of stationary blades 12 in the axial direction is usually longer than that of the single row of stationary blades 12, so that the stability of the support of the rotating shaft 3 and the motor can be improved.

[0069] In a preferred embodiment, the number ratio of the rear row of moving blades 112 and the front row of moving blades 111 is set to be between 2 and 4, and / or the number ratio of the rear row of stationary blades 122 and the front row of stationary blades 121 is set to be between 2 and 4, so that the number of the rear row of blades 1 is enough, thereby the fluid flow uniformity is good and the noise is small; and so that the number of the rear row of blades 1 is enough small, thereby the difficulty and cost of manufacturing the axial flow fan 1000 are reduced.

[0070] In a preferred embodiment, the number ratio of the rear row of moving blades 112 and the front row of moving blades 111 is set to be an integer, and / or the number ratio of the rear row of stationary blades 122 and the front row of stationary blades 121 is set to be an integer, so that the circumferential distance between the same kind of blades 1 and between the front row of blades 1 and the rear row of blades 1 is constant, thereby improving the uniformity of the flow field along the circumferential direction. In the embodiment, the number of the rear row of moving blades 112 is set to be twice the number of the front row of moving blades 111, and the number of the rear row of stationary blades 122 is set to be twice the number of the front row of stationary blades 121.

[0071] In a preferred embodiment, the average solidity ratio of the front row of moving blades 111 and the rear row of moving blades 112 is set to be between 0.9 and 1.3, and / or the average solidity ratio of the front row of stationary blades 121 and the rear row of stationary blades 122 is set to be between 0.9 and 1.3, so that the flow field between the same kind of blades 1 and between the front row of blades 1 and the rear row of blades 1 is relatively uniform along the axial direction, thereby improving the stability of the fluid flow, and further improving the pressure rise performance and reducing the noise. When the average solidity ratio of the front row of moving blades 111 and the rear row of moving blades 112 is set to be between 1 and 1.2, and / or the average solidity ratio of the front row of stationary blades 121 and the rear row of stationary blades 122 is set to be between 1 and 1.2, the effect is better. In the embodiment, the chord length of the front row of moving blades 111 is set to be twice the chord length of the rear row of moving blades 112, and the chord length of the front row of stationary blades 121 is set to be twice the chord length of the rear row of stationary blades 122, so that the solidity ratio of the two rows of moving blades 11 is 1, and the solidity ratio of the two rows of stationary blades 12 is also 1. The chord length and the solidity are both well-known concepts, the chord length is the length from the front end to the rear end of the blade 1, and the solidity can be understood as the chord length of the blade 1 / the distance between two adjacent blades 1 in a single row of blades 1, and the average solidity is the average value of the solidity at different heights of the blade 1.

[0072] Figure 3 In the embodiment, the front row of moving blades 111 and the rear row of moving blades 112 are separately used for comparative analysis, and the static pressure profile change of the airflow after the airflow flows out of the tail end of the blade 1 by the same distance D is compared, and it is concluded that in the case of the same solidity, the static pressure profile of the airflow flowing out of the row of blades 1 with more number and shorter chord length becomes uniform along the flow direction quickly, and the mixing of the airflow flowing out of the row of blades 1 with less number and longer chord length along the flow direction is slower. It is verified that in the utility model, the rear row of blades 1 is shorter and more than the front row of blades 1 in the same kind of blades 1, so that the airflow flow is more uniform, thereby the effect of reducing the noise can be achieved.

[0073] In a preferred embodiment, the tail end of the front row of moving blades 111 and the front end of the rear row of moving blades 112 are arranged to be close to each other in the axial direction and / or the circumferential direction of the axial flow fan 1000, and / or the tail end of the front row of stationary blades 121 and the front end of the rear row of stationary blades 122 are arranged to be close to each other in the axial direction and / or the circumferential direction of the axial flow fan 1000, so as to facilitate the smooth transition of the fluid from the front row of blades 1 to the rear row of blades 1 when the fluid transitions between the same two rows of blades 1, and inhibit the fluid from separating from the surface of the rear row of blades 1.

[0074] Figure 4 The axial and circumferential distances between the tail end of the front row of moving blades 111 and the front end of the rear row of moving blades 112 are marked as L1 and W1 respectively, and the axial and circumferential distances between the tail end of the front row of stationary blades 121 and the front end of the rear row of stationary blades 122 are marked as L2 and W2 respectively.

[0075] In a preferred embodiment, L1 and / or L2 can be arranged to be in the range of -10mm to 10mm, so that the axial distance between the same two rows of blades 1 is small enough to facilitate the smooth transition of the fluid from the front row of blades 1 to the rear row of blades 1, and inhibit the fluid from separating from the surface of the rear row of blades 1; and so that the axial distance between the same two rows of blades 1 is large enough to facilitate processing and manufacturing. Further, when L1 and / or L2 are arranged to be in the range of -5mm to 5mm, the effect is better. Figure 4 In the figure, L1 and L2 are both positive, L1 is negative when the two rows of moving blades 11 have a range of overlap in the axial direction, and L2 is negative when the two rows of stationary blades 12 have a range of overlap in the axial direction.

[0076] In a preferred embodiment, W1 and / or W2 can be arranged to be in the range of 0~10mm, so that the circumferential distance between the two rows of blades 1 is small enough to facilitate the smooth transition of the fluid from the front row of blades 1 to the rear row of blades 1, and inhibit the fluid from separating from the surface of the rear row of blades 1. Further, when W1 and / or W2 are arranged to be in the range of 0~5mm, the effect is better.

[0077] As shown in Figure 5 , the front end and the tail end of the front row of moving blades 111 are marked as P1 and P3 respectively, the front end and the tail end of the rear row of moving blades 112 are marked as P2 and P4 respectively, the inlet angle of the front row of moving blades 111, the outlet angle of the front row of moving blades 111, and the outlet angle of the rear row of moving blades 112 are marked as β1, β2, and β4 respectively, and the direction of rotation of the moving blades 11 is marked as W. The inlet angle and the outlet angle are positive if they are in the same direction as W, and negative if they are in the opposite direction as W. Figure 5 In the figure, β4 is negative, and positive if it is in the opposite direction as W. Figure 5 In the figure, β2 is positive. The relationship between the inlet angle and the outlet angle of the blades 1 satisfies the speed triangle, i.e.

[0078]

[0079] Wherein cn is the tangential velocity of the Pn point along the surface of the blade 1, u is the rotating speed of the moving blade 11, parallel to the W direction, and cn is the velocity of the fluid. Figure 5 The letter representing the velocity is simplified and the vector sign is omitted.

[0080] As Figure 5 , by setting the blade root outlet angle of the rear row of moving blades 112 smaller than the blade root outlet angle of the front row of stationary vanes 121, the rear row of moving blades 112 further works on the fluid, so that the velocity of the fluid is increased from c2 at the tail end of the front row of moving blades 111 to c4 at the tail end of the rear row of moving blades 112. The deflection angle of the blade 1 is the difference between the inlet angle and the outlet angle. In a preferred embodiment, by setting the absolute value of the deflection angle of the front row of moving blades 111 larger than the absolute value of the deflection angle of the rear row of moving blades 112, the pressure rise generated by the front row of moving blades 111 is larger than the pressure rise generated by the rear row of moving blades 112, so that the load of the rear row of moving blades 112 is reduced, and the complexity of the profile of the rear row of moving blades 112 is reduced to facilitate the machining and manufacturing. Similarly, the absolute value of the deflection angle of the front row of stationary vanes 121 can be set larger than the absolute value of the deflection angle of the rear row of stationary vanes 122, so that the guiding and deflection effect of the front row of stationary vanes 121 on the fluid is larger than the guiding and deflection effect of the rear row of stationary vanes 122 on the fluid.

[0081] In a preferred embodiment, the number of the front row of stationary vanes 121 can be set to be no more than half of the number of the rear row of moving blades 112, i.e. no more than 0.5 times, so that the number of the front row of stationary vanes 121 is small enough to reduce the resistance of the front row of stationary vanes 121 to the fluid flow and reduce the noise.

[0082] As Figure 4 , the axial distance between the front end of the front row of moving blades 111 and the tail end of the rear row of moving blades 112 is L3, and the axial distance between the tail end of the rear row of moving blades 112 and the front end of the front row of stationary vanes 121 is L4. In a preferred embodiment, L4 can be set to be 0.5-1.5 times of L3, on the one hand, so that the axial distance between the tail end of the rear row of moving blades 112 and the front end of the stationary vanes 12 is long enough to make the fluid flow out of the rear row of moving blades 112 mixed uniformly before flowing to the stationary vanes 12, so as to reduce the noise of the moving and stationary interference; on the other hand, the axial distance between the moving blades 11 and the stationary vanes 12 is small enough to make the axial size of the axial flow fan 1000 small enough and the structure compact. Preferably, L4 is set to be 0.75 times of L3.

[0083] In a preferred embodiment, the moving blades 11 can be set to be forward inclined, so that the fluid flow is more stable; in this embodiment, both rows of moving blades 11 are set to be forward inclined, i.e. the inclination direction from the blade root to the blade top is the same as the rotating direction W, Figure 6 The left side of the figure shows the inclination of a row of moving blades 11.

[0084] In a preferred embodiment, the stationary blades 12 can be tilted backward to reduce the tendency of fluid to be thrown outward and accumulate on the blade tip side, while the flow velocity on the blade root side is too slow, thus making the fluid flow out more smoothly. In this embodiment, both rows of stationary blades 12 are tilted backward, that is, the tilting direction from the blade root to the blade tip is opposite to the rotation direction W. Figure 6 The right side shows the tilt of a row of still blades 12.

[0085] In other embodiments, the stationary blade 12 and / or the moving blade 11 may be set to not tilt.

[0086] In a preferred embodiment, such as Figure 1 The outlet inner diameter 2r2 of the axial flow fan 1000 can be set between 160mm and 220mm, making it close to the inner diameter of commonly used general-purpose flue pipes, thus facilitating the connection between the outlet of the axial flow fan 1000 and the general-purpose flue pipe. Furthermore, setting the outlet inner diameter of the axial flow fan 1000 between 175mm and 185mm makes it close to the inner diameter of most general-purpose flue pipes, further improving the convenience of connecting the axial flow fan 1000 and the flue pipe.

[0087] In a preferred embodiment, the moving blade 11 and the stationary blade 12 are made of soft plastic or aluminum alloy, which can reduce the wear on the mold when manufacturing the blades 1 by casting; plastic or aluminum alloy materials are lighter and can reduce the weight of the axial flow fan 1000 when used in the axial flow fan 1000.

[0088] In a preferred embodiment, the maximum consistency of a single row of blades 1 can be set to be less than or equal to 2.2, so that the blades 1 in the single row of blades 1 are arranged sparsely enough to facilitate demolding of the blades 1 during casting. Setting the maximum consistency of a single row of blades 1 to be less than or equal to 1.5 yields even better results.

[0089] like Figure 1 In a preferred embodiment, the flow channel 5, located axially between the front end of the front row of moving blades 111 and the rear end of the rear row of stationary blades 122, has a constant inner diameter 2r1 and outer diameter 2r2 to improve flow stability.

[0090] In a preferred embodiment, the hub ratio of the flow channel, r1 / r2, is between 0.4 and 0.8. This ensures a sufficiently large hub ratio, resulting in a sufficiently small blade height, which facilitates a smaller tip and root camber on blade 1, leading to smoother fluid flow and lower noise. Conversely, a sufficiently small hub ratio ensures a sufficiently large blade height, resulting in a sufficiently large flow channel and a sufficiently high flow rate. Setting r1 / r2 between 0.6 and 0.7 yields even better results.

[0091] Overall, the axial flow fan provided by this utility model has the following advantages:

[0092] 1. The advantages of axial flow fan are reserved, and the volume is small, and the layout is free and flexible in the flow channel, thereby facilitating the design of noise reduction; on the basis of single-stage axial flow fan, further adopting the structure of double-row moving blades and double-row stationary blades in series, the disadvantage of small pressure rise of axial flow fan is improved, and the overall structure is still similar to that of single-stage axial flow fan, and the structural complexity is much lower than that of double-stage axial flow fan. The advantage is applied to the oil smoke field in the utility model, and the load and pressure rise are shared by multiple blade rows, so that the noise is greatly reduced.

[0093] 2. The distance between the moving blade row and the stationary blade row, the number of blades, and the moving blade profile are reasonably designed, and the optimization of moving and stationary interference noise, flow stability, and moving blade power are improved.

[0094] 3. The processing cost of the multiple-blade-row axial flow fan is controlled in the following multiple ways:

[0095] The rotating part and the stationary part are separated, and the structural complexity is small relative to the multiple-stage axial flow fan, thereby reducing the processing cost;

[0096] Plastic or aluminum alloy or other soft materials are used to form the blades, thereby reducing mold wear;

[0097] The solidity and other parameters of the blades are properly selected to ensure that the fan blades can rotate and demold in two directions;

[0098] All the moving blades are designed to have equal inner diameters and equal outer diameters, and all the stationary blades are designed to have equal inner diameters and equal outer diameters;

[0099] Since multiple blade rows are used to achieve the target pressure rise, the load of each blade row is relatively light, and the degree of blade distortion is low, which also reduces the processing difficulty.

[0100] Although the specific embodiments of the utility model are described above, those skilled in the art should understand that this is only an example, and the protection scope of the utility model is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the utility model, and these changes and modifications all fall within the protection scope of the utility model.

Claims

1. An axial flow fan comprising two kinds of blades, a moving blade and a stationary blade, the moving blade having two rows, a front row moving blade and a rear row moving blade, arranged in sequence in the direction of fluid flow, the front row moving blade, the rear row moving blade and the stationary blade being characterized in that, The number and chord length of the front row of moving vanes are less and longer than those of the rear row of moving vanes, respectively.

2. The axial fan as set forth in claim 1, wherein The number of the stationary vanes is two, i.e., a front row of stationary vanes and a rear row of stationary vanes, which are arranged in sequence along the fluid flow direction, and the number and chord length of the front row of stationary vanes are less and longer than those of the rear row of stationary vanes, respectively.

3. The axial fan according to claim 1 or 2, wherein In the same kind of two rows of vanes, the ratio of the number of the rear row of vanes to the front row of vanes is between 2 and 4. And / or, in the same kind of two rows of vanes, the ratio of the average solidity of the front row of vanes to the rear row of vanes is between 0.9 and 1.

3.

4. The axial fan as set forth in any one of claims 1 or 2, wherein In the same kind of two rows of vanes, the number of the rear row of vanes is an integer multiple of the front row of vanes. And / or, in the same kind of two rows of vanes, the tail end of the front row of vanes is close to the front end of the rear row of vanes in the circumferential direction and / or axial direction of the axial flow fan.

5. The axial fan as set forth in any one of claims 1 or 2, wherein The axial spacing between the two rows of vanes of the same kind is between -10 mm and 10 mm. And / or, in the same kind of two rows of vanes, the circumferential spacing between the tail end of the pressure surface of the front row of vanes and the front end of the suction surface of the rear row of vanes is between 0 and 10 mm.

6. The axial fan as set forth in any one of claims 1 or 2, wherein The outlet angle of the blade root of the rear row of moving vanes is smaller than that of the front row of moving vanes. And / or, in the same kind of two rows of vanes, the absolute value of the deflection angle of the front row of vanes is greater than that of the rear row of vanes.

7. The axial fan of claim 2 wherein, The number of the front row of stationary vanes is less than or equal to 0.5 times the number of the rear row of moving vanes.

8. The axial fan of claim 1 wherein, The minimum axial spacing between the rear row of moving vanes and the stationary vanes is 0.5 to 1.5 times the axial spacing between the front end of the front row of moving vanes and the tail end of the rear row of moving vanes.

9. The axial fan according to claim 1 or 2, wherein The axial flow fan further comprises a rotating shaft, a support, a motor, and a housing, a flow channel is formed between the inner surface of the housing and the outer surface of the rotating shaft and the support, the vanes are arranged in the flow channel, the moving vanes are fixed on the rotating shaft and form a gap with the inner surface of the housing, the support is fixed on the housing through the stationary vanes, and the motor is installed in the support to drive the rotating shaft to rotate.

10. A range hood characterized by, It comprises the axial flow fan according to any one of claims 1 to 9, the inlet of the axial flow fan is the air inlet of the range hood or communicates with the air inlet of the range hood, and the outlet of the axial flow fan is the air outlet of the range hood or communicates with the air outlet of the range hood.

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