阅读说明：本技术 一种进风口圈组件、风机系统及吸油烟机 (Air inlet ring assembly, fan system and range hood ) 是由 马志豪 于 2020-06-28 设计创作，主要内容包括：本发明公开了一种进风口圈组件,包括具有轴线的进风口圈和预旋装置,所述进风口圈包括环绕轴线呈环状的径向延伸部分、以及轴向导流部,所述轴向导流部在径向延伸部分的径向内侧、沿轴线延伸,其特征在于：所述预旋装置包括一级预旋机构,所述一级预旋机构设置在径向延伸部分在轴向上的第一侧,所述轴向导流部设置在径向延伸部分在轴向上的、与第一侧相对的第二侧,所述一级预旋机构包括由径向延伸部分在轴向上两侧的压力差推动转动的一级拨片,所述一级拨片的转动轴与轴线平行。还公开了一种应用有所述进风口圈组件的风机系统,以及应用有所述风机系统的吸油烟机。(The invention discloses an air inlet ring assembly, which comprises an air inlet ring with an axis and a pre-screwing device, wherein the air inlet ring comprises a radial extension part and an axial flow guide part, the radial extension part is annular around the axis, the axial flow guide part extends along the axis on the radial inner side of the radial extension part, and the air inlet ring assembly is characterized in that: it revolves the mechanism in advance to include one-level, one-level revolves the mechanism setting in advance at radial extension part first side in the axial, axial water conservancy diversion portion sets up in radial extension part second side relative with first side in the axial, one-level revolves the mechanism in advance and includes that the pressure differential that is pushed the pivoted one-level plectrum by radial extension part both sides in the axial, the axis of rotation and the axis of one-level plectrum are parallel. Also discloses a fan system applying the air inlet ring assembly and a range hood applying the fan system.)

1. An air intake collar assembly comprising an air intake collar (341) having an axis (X) and a pre-swirl device, the air intake collar (341) comprising a radially extending portion annular about the axis (X), and an axial flow guide (3413), the axial flow guide (3413) extending along the axis (X) radially inward of the radially extending portion, characterized in that: the prerotation device comprises a primary prerotation mechanism (342), the primary prerotation mechanism (342) is arranged on a first side of the radial extension portion in the axial direction, the axial flow guide portion (3413) is arranged on a second side, opposite to the first side, of the radial extension portion in the axial direction, the primary prerotation mechanism (342) comprises a primary poking piece (3421) which is pushed to rotate by pressure difference of two sides of the radial extension portion in the axial direction, and a rotating shaft of the primary poking piece (3421) is parallel to the axis (X).

2. The air intake collar assembly of claim 1, wherein: the primary pre-rotation mechanism (342) further comprises a push rod (3422) and a pressure tube (3424), one end of the push rod (3422) is located in the pressure tube (3424), the other end of the push rod (3422) extends out of the pressure tube (3424) and is connected with the primary dial plate (3421), the push rod (3422) keeps the trend of moving towards the pressure tube (3424), a stop part (3426) is arranged on the end part of the push rod (3422) located in the pressure tube (3424), the stop part (3426) divides the pressure tube (3424) into a first cavity (Q1) far away from the push rod (3422) and a second cavity (Q2) provided with the push rod (3422), and the first cavity (Q1) is communicated with the part of fluid on the second side of the radial extending part and outside the axial flow guiding part (3413).

3. The air intake collar assembly of claim 2, wherein: the pressure tube (3424) is in close contact with the radially extending portion and a through hole (3425) is formed in a face of the pressure tube (3424) in close contact with the radially extending portion such that the first cavity (Q1) is in fluid communication with the second side of the radially extending portion.

4. The air intake collar assembly of claim 2, wherein: the primary pre-rotation mechanism (342) further comprises an elastic element (3423), the elastic element (3423) is sleeved on the push rod (3422), one end of the elastic element (3423) is abutted against the stopping part (3426), and the other end of the elastic element is abutted against the inner side of one end, close to the primary dial plate (3421), of the pressure pipe (3424), so that the push rod (3422) keeps the trend of moving towards the pressure pipe (3424).

5. The air intake collar assembly of claim 1, wherein: the primary paddle (3421) extends in a radial direction and is rotatably connected to the radially extending portion via a first rotating shaft (3427), the first rotating shaft (3427) constituting a rotating shaft of the primary paddle (3421).

6. The air intake collar assembly of any one of claims 1 to 5, wherein: the radial extension part comprises an annular mounting part (3411) and a radial flow guide part (3412) extending inwards from the radial inner side of the mounting part (3411), and the primary prerotation mechanism (342) is arranged on the mounting part (3411).

7. The air intake collar assembly of claim 1, wherein: the pre-rotation device further comprises a secondary pre-rotation mechanism (343), the secondary pre-rotation mechanism (343) comprises a secondary poking piece (3431) which is pushed to rotate by the pressure difference between the inner side and the outer side of the axial flow guide part (3413) in the radial direction, and the rotating shaft of the secondary poking piece (3431) extends in the radial direction of the axial flow guide part (3413).

8. The air intake collar assembly of claim 7, wherein: the secondary shifting piece (3431) is provided with a groove (3433), the axial flow guide part (3413) is clamped in the groove (3433), and the secondary shifting piece (3431) is partially positioned on the radial inner side of the axial flow guide part (3413) and partially positioned on the radial outer side of the axial flow guide part (3413).

9. The air intake collar assembly of claim 8, wherein: the second-stage pre-rotation mechanism (343) further comprises a second rotating shaft (3432) forming a rotating shaft of the second-stage shifting piece (3431), and the second rotating shaft (3432) penetrates through the axial guide part (3413) to be connected with the parts of the second-stage shifting piece (3431) located on the inner side and the outer side of the axial guide part (3413), so that the second-stage shifting piece (3431) is rotatably connected with the axial guide part (3413).

10. A fan system applying the air inlet ring assembly as claimed in any one of claims 1 to 9, comprising a volute (31) and an impeller (32) disposed in the volute (31), wherein the volute (31) is provided with a fan inlet (314), the impeller (32) is coaxial with the air inlet ring (341), and the fan system is characterized in that: the first side of the radial extending part in the axial direction faces the outside of the volute (31), the second side of the radial extending part in the axial direction faces the inside of the volute (31), and the axial flow guide part (3413) extends into the volute (31) through the fan air inlet (314).

11. A range hood, its characterized in that: use of a fan system according to claim 10.

Technical Field

The invention relates to a power system, in particular to an air inlet ring assembly, a fan system applying the air inlet ring assembly and a range hood applying the fan system.

Background

The range hood has become an indispensable kitchen appliance for people since the entrance into China in the nineties of the last century. The main functions of the kitchen ventilator are that oil smoke generated when a user cooks is sucked from the air inlet through the impeller of the fan system, the oil smoke is filtered by the filter screen of the air inlet and the impeller, and the filtered oil smoke is discharged from the air outlet, so that the kitchen environment is purified. The fan system is used as a core component of the range hood, the working state of the fan system has important influence on the oil smoke absorption effect, and the air inlet of the fan system is important for ensuring the high-efficiency operation of the system and ensuring the range hood to keep a better oil smoke absorption effect.

In order to ensure the working efficiency of a fan system and improve the oil smoke absorption effect of a range hood in the current market, an air inlet ring is additionally arranged at an air inlet of the fan system or is directly processed together with a volute. The blower disclosed in chinese patent No. 201620102790.9 of the present applicant includes a volute, an impeller, a motor, and an air inlet ring, wherein the air inlet ring is installed at an air inlet of the blower and is matched with a front cover of the volute.

Because the fan system has different installation forms in the range hood box body, the performance of the fan system not only depends on the optimal performance of the current fan system, but also is limited by the form of the range hood box body. When the fan system works, under the influence of the internal rotating impeller, airflow at the center of the air inlet of the volute moves axially to the inside of the volute firstly, then the speed direction of the airflow changes to form a certain angle with the rotating direction of the impeller to enter the impeller, the airflow at the edge of the air inlet of the volute moves radially to the air inlet firstly, and then the airflow in the volute generates tangential speed consistent with the rotating direction of the impeller together. Because the air inlet is not provided with any auxiliary structure, the change direction of the air flow is totally dependent on the rotation of the impeller, so that the performance of the fan system is limited.

For this purpose, some patents have disclosed the addition of active prerotation devices at the air intake. The centrifugal fan disclosed in the applicant's chinese patent application No. 201710629367.3 includes a volute and an impeller disposed in the volute, wherein the volute is provided with an air inlet, the air inlet is provided with an air inlet ring, the air inlet ring is provided with a grille assembly, the grille assembly includes at least two blades forming a grille shape and a driving mechanism for driving the blades to deflect, and two ends of each blade are rotatably connected to the air inlet ring respectively. The air inlet ring of the centrifugal fan is additionally provided with the grid capable of deflecting, so that air flow is guided to a main air inlet area with stronger negative pressure, the working efficiency of the fan is effectively improved, the negative pressure is enhanced, and the pneumatic noise is reduced.

Although this kind of structure can play supplementary air current and change the direction effect, all need install additional initiative structure additional, like the motor etc. has increaseed range hood's consumption, and can produce extra heat at this structure during operation for the air current temperature that gets into fan system is higher, easily produces the problem that fan system motor temperature rise exceeds standard and makes complete machine work efficiency descend. In addition, the active prerotation structure is completely independent of the fan system during working, so that the active prerotation structure can only achieve a better auxiliary effect under the specific working state of the range hood, the working state of the range hood is limited, the application range of the range hood is seriously reduced, and the functional characteristics of the range hood are reduced.

Disclosure of Invention

The first technical problem to be solved by the present invention is to provide an air inlet ring assembly, which utilizes a fully passive manner to laterally deflect the air flow, and has stable control without additional energy input, in order to overcome the disadvantages of the prior art.

The second technical problem to be solved by the invention is to provide a fan system applying the air inlet ring assembly.

The third technical problem to be solved by the invention is to provide a range hood with the fan system.

The technical scheme adopted by the invention for solving the first technical problem is as follows: the utility model provides an air inlet circle subassembly, includes the air inlet circle that has the axis and prerevolves the device, the air inlet circle is annular radial extension portion and axial water conservancy diversion portion including encircling the axis, the axial water conservancy diversion portion is at radial inboard, the axis extension of radial extension portion, its characterized in that: it revolves the mechanism in advance to include one-level, one-level revolves the mechanism setting in advance at radial extension part first side in the axial, axial water conservancy diversion portion sets up in radial extension part second side relative with first side in the axial, one-level revolves the mechanism in advance and includes that the pressure differential that is pushed the pivoted one-level plectrum by radial extension part both sides in the axial, the axis of rotation and the axis of one-level plectrum are parallel.

Further, for the convenience of pushing the one-level plectrum to rotate under the effect of pressure difference, the one-level preswirl mechanism still includes push rod and manometer pipe, the one end of push rod is located manometer pipe, the other end extends the manometer pipe and is connected with the one-level plectrum, the push rod keeps the trend of removing in the manometer pipe, the push rod is provided with backstop portion on being located the tip in the manometer pipe, backstop portion separates into the first cavity of keeping away from the push rod with the second cavity that sets up the push rod in with the manometer pipe, first cavity and radial extension part's second side, be located the partial fluid intercommunication outside the axial water conservancy diversion portion.

Further, to facilitate the use of a pressure differential, the pressure tube is in close proximity to the radially extending portion and a through hole is formed in a face of the pressure tube in close proximity to the radially extending portion such that the first cavity is in fluid communication with the second side of the radially extending portion.

Further, for the push rod resets, one-level prerotation mechanism still includes the elastic component, the elastic component cover is established on the push rod, the one end and the backstop portion butt of elastic component, the other end then with the manometer pipe be close to the inboard butt of one end of one-level plectrum to make the push rod keep the trend of removing in the manometer pipe.

Further, in order to facilitate the rotation of the primary shifting piece, the primary shifting piece extends along the radial direction and is rotatably connected with the radial extension part through a first rotating shaft, and the first rotating shaft forms a rotating shaft of the primary shifting piece.

Preferably, the radial extension part comprises an annular mounting part and a radial flow guide part which extends radially inwards from the radial inner side of the mounting part, and the primary pre-rotation mechanism is arranged on the mounting part.

Furthermore, the pre-rotation device further comprises a second-stage pre-rotation mechanism, the second-stage pre-rotation mechanism comprises a second-stage shifting piece which is pushed to rotate by pressure difference between the inner side and the outer side of the axial flow guide part in the radial direction, and a rotating shaft of the second-stage shifting piece extends in the radial direction of the axial flow guide part.

In order to facilitate the arrangement of the second-stage shifting piece, a groove is formed in the second-stage shifting piece, and the axial flow guide portion is clamped in the groove, so that the second-stage shifting piece is partially positioned on the radial inner side of the axial flow guide portion, and partially positioned on the radial outer side of the axial flow guide portion.

Preferably, for the convenience of the rotation of the second-stage shifting piece, the second-stage pre-rotation mechanism further comprises a second rotating shaft of a rotating shaft of the second-stage shifting piece, and the second rotating shaft penetrates through the axial flow guide part and is connected with the second-stage shifting piece parts located on the inner side and the outer side of the axial flow guide part, so that the second-stage shifting piece is rotatably connected with the axial flow guide part.

The technical scheme adopted by the invention for solving the second technical problem is as follows: the utility model provides an be applied as above fan system of air intake circle subassembly, includes the spiral case, sets up the impeller in the spiral case, the fan air intake has been seted up on the spiral case, the impeller is coaxial with the air intake circle, its characterized in that: the first side of the radial extension part in the axial direction faces the outer part of the volute, the second side of the radial extension part in the axial direction faces the inner part of the volute, and the axial flow guide part extends into the volute through the fan air inlet.

The technical scheme adopted by the invention for solving the third technical problem is as follows: a range hood, its characterized in that: a fan system as described above is applied.

Compared with the prior art, the invention has the advantages that: the primary pre-rotation mechanism is arranged, the purpose of primary dial plate deflection is achieved by utilizing pressure difference, the deflection angle can be changed along with the change of the current working condition, and passive control is realized; by arranging the secondary pre-rotation mechanism, the inner side is stressed more than the outer side by utilizing the difference of the wind speeds of the inner side and the outer side of the air inlet ring, so that the purpose of deflection of the secondary shifting piece is achieved, and the deflection angle is different along with the change of working conditions, so that passive control is realized; the double-stage pre-rotation mechanism is arranged, airflow at the air inlet is laterally deflected in a fully passive mode, the control is stable, additional energy input is not needed, airflow deflection control under given conditions can be achieved without a sensor, and the structure is simple; the two-stage pre-rotation mechanisms work independently, so that the structural stability is higher; when the spiral-flow-guiding mechanism is applied to a fan system, the primary prerotation mechanism can change the deflection angle along with the change of the pressure inside and outside the spiral case, the secondary prerotation mechanism can change the deflection angle along with the change of the rotating speed of the impeller, and the airflow at the air inlet can be deflected laterally before entering the fan system, so that the airflow can enter the impeller more easily after entering the fan system, and the airflow circulation is improved.

Drawings

FIG. 1 is a schematic view of a range hood according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view of a range hood in accordance with an embodiment of the present invention;

fig. 3 is a schematic view (initial state) of an air inlet ring assembly of the range hood according to the embodiment of the present invention;

FIG. 4 is a cross-sectional view of an air inlet ring assembly of the range hood according to the embodiment of the present invention;

FIG. 5 is a schematic view of a two-stage pre-rotation mechanism of an air inlet ring assembly of the range hood according to the embodiment of the present invention;

FIG. 6 is a schematic view of a first-stage pre-rotation mechanism of an air inlet ring assembly of the range hood according to the embodiment of the present invention;

FIG. 7 is a sectional view of a first-stage pre-rotation mechanism of an air inlet ring assembly of the range hood according to the embodiment of the present invention;

FIG. 8 is a schematic view of a deflection principle of a first-stage pre-rotation mechanism of an air inlet ring assembly of the range hood according to the embodiment of the present invention;

fig. 9 is a schematic view (deflection state) of an air inlet ring assembly of the range hood according to the embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar functions.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present invention and to simplify the description, but are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and that the directional terms are used for purposes of illustration and are not to be construed as limiting, for example, because the disclosed embodiments of the present invention may be oriented in different directions, "lower" is not necessarily limited to a direction opposite to or coincident with the direction of gravity. Furthermore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

Referring to fig. 1 and 2, a range hood is a side-suction range hood with an upper fan in the embodiment, but may also be any other existing range hood, such as a top-suction range hood, a side-suction range hood with a lower fan, and a low-suction range hood. The range hood comprises a shell 1, a fan frame 2 arranged above the shell 1 and a fan system 3 arranged in the fan frame 2, wherein a panel 4 is arranged on the front side of the shell 1, an air inlet 41 is formed in the panel 4, and an oil screen 42 is arranged at the air inlet. The panel 4 is also provided with a smoke barrier 5 capable of opening or closing the air inlet 41.

The fan system 3 includes a volute 31, an impeller 32 disposed in the volute 31, and a motor 33 for driving the impeller 32 to rotate. The volute 31 includes a front cover plate 311, a rear cover plate 312, and a circumferential wall 313 arranged between the front cover plate 311 and the rear cover plate 312, and the front cover plate 311 is provided with a fan inlet 314. An air inlet ring assembly 34 is disposed at the fan inlet 314.

Referring to fig. 3 and 4, the air inlet collar assembly 34 includes an air inlet collar 341 and a pre-rotation device. The air inlet ring 341 has an axis X, and includes a mounting portion 3411 annular around the axis X (which is also the axis of the impeller 32), a radial guide portion 3412 extending radially inward from a radially inner side of the mounting portion 3411, and an axial guide portion 3413 extending from the radially inner side of the radial guide portion 3412 along the axis X toward the inside of the scroll casing 31, and the radial guide portion 3412 may protrude arcuately in a direction away from the scroll casing 31. The mounting portion 3411 and the radial guide 3412 are radially extending portions of the intake collar assembly 34, and the axial guide 3413 is an axially extending portion of the intake collar assembly 34, with a point on the axis X being a center point. The mounting portion 3411 is mounted on the outer periphery of the fan inlet 314 and located on the side of the front cover plate 311 facing the outside of the scroll casing 31, and the axial guide portion 3413 extends from the fan inlet 314 into the scroll casing 31.

The pre-rotation device comprises a primary pre-rotation mechanism 342 and a secondary pre-rotation mechanism 343. Referring to fig. 6 and 7, the primary pre-rotation mechanism 342 is disposed on a radially extending portion of the air inlet ring 341 and is located on a first side of the radially extending portion in the axial direction, i.e., a side facing the volute casing 31, and the axial guide 3413 is located on a second side of the radially extending portion in the axial direction, the first side being opposite to the second side. As in the present embodiment, the primary pre-rotation mechanism 342 is disposed on the mounting portion 3411, but the primary pre-rotation mechanism 342 may also be partially disposed on the radial flow guide portion 3412. The primary pre-rotation mechanism 342 includes a primary dial 3421, a push rod 3422, an elastic member 3423 and a pressure tube 3424, and the pressure difference generated between the inside and the outside of the volute 31 when the impeller 32 rotates is utilized to push the push rod 3422 to move, so that the primary dial 3421 rotates. The pressure tube 3424 is fixedly connected to the mounting portion 3411, a through hole 3425 is formed in a surface of the pressure tube 3424, which is in close contact with the mounting portion 3411, and corresponding through holes are formed in the mounting portion 3411 and the front cover 311, so that the pressure tube 3424 is in fluid communication with a portion of the volute 31, which is located outside the axial flow guide portion 3413, and the internal pressure of the pressure tube 3424 is the same as the internal pressure of the volute 31. Pushrod 3422 has one end disposed within pressure tube 3424 and the other end extending out of pressure tube 3424 to connect with first-stage paddle 3421, which may be a fixed connection, preferably a rotatable connection. The first stage driver 3421 extends in the radial direction of the mounting portion 3411 and is rotatably connected to the mounting portion 3411 via a first rotating shaft 3427 at a position close to the radially inner side of the mounting portion 3411, the first rotating shaft 3427 of the first stage driver 3421 is parallel to the axis X, and the first stage driver 3421 abuts against the surface of the mounting portion 3411. The push rod 3422 extends at an angle to the circumferential direction of the mounting portion 3411.

The end of the push rod 3422 located in the pressure tube 3424 is provided with a stopper portion 3426, the stopper portion 3426 is larger than the push rod 3422, and the push rod 3422 and the stopper portion 3426 are integrally formed. The stop 3426 divides the interior of the pressure tube 3424 into a first cavity Q1 remote from the push rod 3422 and a second cavity Q2 in which the push rod 3422 is arranged. The through hole 3425 corresponds to the first cavity Q1, and the pressure in the first cavity Q2 is the same as the pressure inside the scroll case 31. The elastic element 3423, which is a spring in this embodiment, is disposed on the push rod 3422, and has one end abutting against the stop part 3426 and the other end abutting against the inner side of the pressure tube 3424 near the first-stage dial plate 3421. Thereby causing pushrod 3422 to maintain its tendency to move inwardly into pressure tube 3424.

When the blower system works, the pressure inside the volute 31 is higher than the outside, and at this time, under the action of the air pressure, thrust is generated on the surface of the stopping portion 3426 away from the elastic member 3423, so as to push the push rod 3422 to extend out of the pressure tube 3424, and the push rod 3422 drives the primary dial 3421 to rotate, so that the primary dial 3421 generates a radial tilt angle, and pre-rotation is performed on the air flow, as shown in fig. 9.

The radial tilt angle of the first-stage paddle 3421 is related to the pressure in the scroll case 31 as follows:

referring to fig. 8, when the range hood operates, the pressure in the volute 31 is pr1, the spring elastic coefficient is k, the limit expansion distance is h, the area of the side surface of the first-stage paddle 3421 is s1, and the area of the stopping portion 3426 is s 2. The center of the through-hole 3425 is point B, the original position of the connection between the push rod 3422 and the first-stage paddle 3421 is point C, the BC length is p0, the rotation center of the first-stage paddle 3421 is point a, and the AB length is n. Under pressure pr1, push rod 3422 moves, where it connects to primary paddle 3421 to point C ', BC ' being p1 in length and AC ' being m in length. Then:

when the spring limit expansion distance is not reached:

by the balance of the force applied by the push rod 3422, it can be obtained:

t_as₁*sinθ₁*cosθ₁+kΔx＝pr1*s₂

wherein, t_aIs the wind force that the first-stage paddle 3421 is subjected to per unit area, which is related to the wind speed, θ₁Is the rotating angle of the first-level shifting piece,

Δx＝p₁-p₀

θ₁＝β-α

the above formulas are substituted into calculation to obtain the deflection angle theta of the first-level plectrum 3421₁。

Referring to fig. 4 and 5, the secondary pre-rotation mechanism 343 includes a secondary dial 3431 and a second rotation shaft 3432, and the secondary dial 3431 is disposed on the axial guide 3413. The second-stage paddle 3431 is provided with a groove 3433, and the groove 3433 is formed by the second-stage paddle 3431 being concave towards the inside of the volute 31 from the side facing the outside of the volute 31. Axial guides 3413 snap into grooves 3433 such that secondary paddle 3431 is partially radially inward of axial guides 3413 and partially radially outward of axial guides 3413. The second rotating shaft 3432 penetrates the axial guide 3413 to connect the portions of the second stage dial 3431 located on the inner and outer sides of the axial guide 3413, so that the second stage dial 3431 is rotatably connected to the axial guide 3413, and the second rotating shaft 3432 is parallel to the radial direction of the impeller 32.

The secondary pre-rotation mechanism 343 utilizes the inconsistent wind speeds at the radially inner and outer sides of the air inlet ring 341, so that when the fan system works and the lateral force at the inner side is greater than the resistance at the outer side, the secondary dial plate 3431 is caused to deflect. If the inner wind speed is u1, the outer wind speed is u2, the self weight of the secondary paddle 3431 is m', the air density is rho, g is the gravity acceleration, and theta is₂And a second-level shift plate deflection angle is obtained:

substituting the above formula into each parameter value to obtain the deflection angle theta of the second-stage plectrum₂And two-stage pre-rotation deflection is achieved.

The primary pre-rotation mechanism 342 and the secondary pre-rotation mechanism 343 may each have at least two circumferentially spaced apart arrangements.

In the prerotation device, the primary prerotation mechanism utilizes the pressure difference generated inside and outside the volute when the impeller rotates to push the pneumatic push rod to move, so that the primary poking piece rotates to form a certain angle with the plane where the output shaft of the motor 33 is located, and when airflow passes through the position, the airflow is forced to generate tangential speed with the same rotating direction of the impeller 32; the second-stage prerotation mechanism utilizes the fact that the air flow speeds of the inner side and the outer side of the air inlet ring are not the same, so that the second-stage shifting piece is stressed by the force which is the same as the rotation direction of the impeller 32, the second-stage shifting piece further rotates by a certain angle, axial air flow is forced to generate tangential speeds which are the same as the rotation direction of the impeller 32 when passing through the shifting piece, air inlet smoothness of a fan system is guaranteed, and the oil smoke absorption effect is improved.

The term "fluid communication" as used herein refers to a spatial relationship between two components or portions (hereinafter collectively referred to as a first portion and a second portion, respectively), i.e., a fluid (gas, liquid or a mixture of both) can flow along a flow path from the first portion and/or be transported to the second portion, and may be a direct communication between the first portion and the second portion, or an indirect communication between the first portion and the second portion via at least one third element, such as a fluid channel, e.g., a pipe, a channel, a duct, a flow guide, a hole, a groove, or a chamber that allows a fluid to flow through, or a combination thereof.