CN222046165U

CN222046165U - Centrifugal fans and range hoods

Info

Publication number: CN222046165U
Application number: CN202420449086.5U
Authority: CN
Inventors: 吴金鑫; 李业强; 胡小文; 胡斯特; 陈鹏; 汪耀东; 郑志伟; 李书奇; 蔡茫; 陈建伟
Original assignee: GD Midea Air Conditioning Equipment Co Ltd; Foshan Shunde Midea Washing Appliances Manufacturing Co Ltd
Current assignee: GD Midea Air Conditioning Equipment Co Ltd; Foshan Shunde Midea Washing Appliances Manufacturing Co Ltd
Priority date: 2024-03-07
Filing date: 2024-03-07
Publication date: 2024-11-22
Anticipated expiration: 2034-03-07

Abstract

The utility model relates to the technical field of household appliances, and provides a centrifugal fan and a range hood, wherein the centrifugal fan comprises a volute and a flow guide part, the volute comprises a volute side arc plate part and cover plate parts positioned at two sides of the side arc plate part, the cover plate parts at two sides are respectively provided with a main air inlet and an auxiliary air inlet, and the auxiliary air inlet is provided with a high flow velocity zone; the flow guiding part and the auxiliary air inlet are coaxially arranged, the flow guiding part is provided with a flow guiding inlet, and the flow guiding inlet is suitable for increasing the air inlet area corresponding to the high flow velocity area. The flow guide part is arranged on the auxiliary air inlet, and the flow guide inlet of the flow guide part increases the air inlet area corresponding to the high flow velocity region, so that the air flow velocity at the position corresponding to the high flow velocity region is reduced, and the air inlet uniformity of the auxiliary air inlet is effectively improved; and the increase of the air inlet area is beneficial to improving the integral air inlet quantity of the diversion inlet, correspondingly improves the integral air inlet quantity of the centrifugal fan, and effectively improves the working efficiency of the centrifugal fan.

Description

Centrifugal fan and range hood

Technical Field

The utility model relates to the technical field of household appliances, in particular to a centrifugal fan and a range hood.

Background

The centrifugal fan has the advantages of large suction force, low noise, compact structure and the like, and is a common core power component in the range hood, and the performance of the centrifugal fan directly determines the noise level of the range hood.

In the related art, a centrifugal fan is generally provided with a main air inlet and an auxiliary air inlet, and air inlet optimization aiming at the centrifugal fan is mainly arranged on the main air inlet with large air inflow, and the problem of uneven air inlet exists at the auxiliary air inlet.

Disclosure of utility model

The present utility model is directed to solving at least one of the technical problems existing in the related art. Therefore, the utility model provides the centrifugal fan, the flow guide inlet of the flow guide part increases the air inlet area corresponding to the high flow velocity zone, and the air inlet uniformity of the auxiliary air inlet is effectively improved; and the whole air intake of the diversion inlet is increased, so that the whole air intake of the centrifugal fan is improved, and the working efficiency of the centrifugal fan is effectively improved.

The utility model also provides a range hood.

An embodiment of the centrifugal fan according to the first aspect of the utility model comprises:

The spiral case comprises a spiral case side arc plate part and cover plate parts positioned at two sides of the side arc plate part, wherein a main air inlet and an auxiliary air inlet are respectively arranged on the cover plate parts at two sides, and the auxiliary air inlet is provided with a high flow velocity zone;

The flow guiding part and the auxiliary air inlet are coaxially arranged, and the flow guiding inlet is suitable for increasing the air inlet area corresponding to the high flow velocity area.

According to the centrifugal fan provided by the embodiment of the utility model, most of external gas enters the volute from the main air inlet, and a small part of gas enters the volute from the auxiliary air inlet and is discharged along a flow passage in the volute.

It should be noted that, the shape of the auxiliary air inlet of the conventional centrifugal fan is mostly circular, the flow channel of the volute is arranged along the circumference of the auxiliary air inlet, and because the air is accelerated in the flow channel, the flow velocity of the air in the circumferential flow channel of the auxiliary air inlet is uneven, and the correspondingly generated suction force is different, so that the flow velocity of the air in the circumference of the auxiliary air inlet is uneven, and a high flow velocity area is formed in the circumference of the auxiliary air inlet.

According to the centrifugal fan provided by the embodiment of the utility model, the flow guide part is arranged on the auxiliary air inlet, and the flow guide inlet of the flow guide part increases the air inlet area corresponding to the high flow velocity region, so that the air flow velocity at the position corresponding to the high flow velocity region is reduced, and the air inlet uniformity of the auxiliary air inlet is effectively improved; and the increase of the air inlet area is beneficial to improving the integral air inlet quantity of the diversion inlet, correspondingly improves the integral air inlet quantity of the centrifugal fan, and effectively improves the working efficiency of the centrifugal fan.

According to one embodiment of the utility model, the diversion inlet is elliptical; the spiral case is provided with the air-out portion that radially extends outward, the export of air-out portion has the axis, the vice air inlet has the parallel to the central line of axis, oval major axis with the contained angle scope of central line is 0 degrees to 90 degrees.

According to one embodiment of the utility model, the centrifugal fan further comprises an impeller which is annularly arranged around the axis of the auxiliary air inlet;

The inner diameter of the impeller is smaller than the length of the short axis of the ellipse, and the outer diameter of the impeller is larger than the length of the long axis of the ellipse.

According to one embodiment of the utility model, the flow guiding part is provided with a second air inlet channel, the second air inlet channel is communicated with the auxiliary air inlet and the outside, and the sectional area of the second air inlet channel is gradually reduced along the direction of the outside pointing to the auxiliary air inlet.

According to one embodiment of the utility model, the direction of extension of the end of the second air intake channel near the impeller is parallel to the axis of the impeller.

According to one embodiment of the present utility model, the flow guiding portion is further provided with a flow guiding outlet, the flow guiding outlet is located between the two cover plate portions, and along the axial direction of the impeller, the distance between the flow guiding outlet and the cover plate portion where the auxiliary air inlet is located is H1, the distance between the surface of the impeller and the cover plate portion where the auxiliary air inlet is located is H2, and H1 is greater than H2.

According to one embodiment of the utility model, the surface of the flow guiding part and the surface of the impeller are provided with an avoidance gap, and the range of the avoidance gap is 2-20 mm.

According to one embodiment of the utility model, the centrifugal fan further comprises a motor support extending from the flow guiding portion towards the interior of the volute.

According to one embodiment of the utility model, the motor bracket comprises a plurality of supporting arms which are symmetrical to the axis of the auxiliary air inlet in the center, and an air inlet gap is formed between the supporting arms.

According to a second aspect of the present utility model, a range hood includes:

A case;

a centrifugal fan as described above, the centrifugal fan being disposed within the housing.

The range hood according to the embodiment of the present utility model has the same beneficial effects as the centrifugal fan according to the embodiment of the first aspect, and will not be described here again.

Additional aspects and advantages of the utility model will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the utility model.

Drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the related art, the drawings that are required to be used in the embodiments or the related technical descriptions will be briefly described, and it is apparent that the drawings in the following description are only some embodiments of the present utility model, and other drawings may be obtained according to the drawings without inventive effort for those skilled in the art.

FIG. 1 is a schematic diagram of a centrifugal fan according to an embodiment of the present utility model;

FIG. 2 is a second schematic diagram of a centrifugal fan according to an embodiment of the present utility model;

FIG. 3 is a front view of a centrifugal fan provided by an embodiment of the present utility model;

FIG. 4 is a cross-sectional view taken along section line A-A of FIG. 3;

Fig. 5 is an enlarged view of a portion B in fig. 4.

Reference numerals:

100. A volute; 110. a side arc plate portion; 120. a cover plate portion; 140. an air outlet part; 191. a primary air inlet; 192. an auxiliary air inlet;

600. A flow guiding part; 610. a diversion inlet; 620. a second air inlet channel; 630. a diversion outlet; 640. avoidance gap;

700. An impeller; 800. a motor bracket; 810. a support arm; 820. and (5) an air inlet gap.

Detailed Description

Embodiments of the present utility model are described in further detail below with reference to the accompanying drawings and examples. The following examples are illustrative of the utility model but are not intended to limit the scope of the utility model.

In the description of the embodiments of the present utility model, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the embodiments of the present utility model and simplifying the description, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the embodiments of the present utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In describing embodiments of the present utility model, it should be noted that, unless explicitly stated and limited otherwise, the terms "coupled," "coupled," and "connected" should be construed broadly, and may be either a fixed connection, a removable connection, or an integral connection, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium. The specific meaning of the above terms in embodiments of the present utility model will be understood in detail by those of ordinary skill in the art.

In embodiments of the utility model, unless expressly specified and limited otherwise, a first feature "up" or "down" on a second feature may be that the first and second features are in direct contact, or that the first and second features are in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the embodiments of the present utility model. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

As shown in fig. 1 to 5, the centrifugal fan according to the embodiment of the first aspect of the present utility model includes a scroll casing 100 and a flow guiding part 600, the scroll casing 100 includes a side arc plate part 110 of the scroll shape and cover plate parts 120 located at both sides of the side arc plate part 110, a main air inlet 191 and a sub air inlet 192 are respectively provided on the cover plate parts 120 at both sides, and the sub air inlet 192 has a high flow rate region; the flow guiding part 600 is coaxially arranged with the auxiliary air inlet 192, the flow guiding part 600 is provided with a flow guiding inlet 610, and the flow guiding inlet 610 is suitable for increasing the air inlet area corresponding to the high flow velocity area.

According to the centrifugal fan of the embodiment of the utility model, most of external air enters the volute 100 from the main air inlet 191, and a small part of air enters the volute 100 from the auxiliary air inlet 192, and the two parts of air are discharged after being accelerated along the flow passage inside the volute 100.

It should be noted that, the shape of the auxiliary air inlet 192 of the conventional centrifugal fan is mostly circular, the flow passage of the volute 100 is circumferentially arranged along the auxiliary air inlet 192, and the flow velocity of the air in the circumferential flow passage of the auxiliary air inlet 192 is uneven because the air is accelerated in the flow passage, and the suction force generated correspondingly is different, so that the flow velocity of the air in the circumferential direction of the auxiliary air inlet 192 is uneven, and a high flow velocity region is formed in the circumferential direction of the auxiliary air inlet 192.

According to the centrifugal fan provided by the embodiment of the utility model, the flow guide part 600 is arranged on the auxiliary air inlet 192, and the flow guide inlet 610 of the flow guide part increases the air inlet area corresponding to the high flow velocity region, so that the air flow velocity at the position corresponding to the high flow velocity region is reduced, and the air inlet uniformity of the auxiliary air inlet 192 is effectively improved; and the increase of the air inlet area is beneficial to improving the integral air inlet quantity of the diversion inlet 610, correspondingly improving the integral air inlet quantity of the centrifugal fan and effectively improving the working efficiency of the centrifugal fan.

In this embodiment, as shown in fig. 1 and fig. 3, the position of the auxiliary gas inlet 192 corresponding to the straight line where L1 is shown in fig. 3 is the center of the high flow rate region, and the high flow rate region is formed on both sides of the position; of course, the location of the high flow area may be adaptively adjusted in the circumferential direction of the secondary air intake 192 based on the structural configuration of the various centrifugal fans.

In this embodiment, the flow guiding portion 600 and the volute 100 are integrally formed for easy manufacture, however, the flow guiding portion 600 may also be detachably connected to the auxiliary air inlet 192 as a separate component to replace the flow guiding portion 600 with different specifications according to the use requirement.

The flow guiding portion 600 in the present embodiment is disposed at the auxiliary air inlet 192, so that the air intake of the auxiliary air inlet 192 is more uniform. Of course, the guide part 600 may be disposed at the main air inlet 191 to improve the air intake uniformity of the main air inlet 191.

In this embodiment, a main air inlet 191 and a sub air inlet 192 are respectively provided on the cover plate portion 120 on both sides of the side arc plate portion 110; of course, the number and positions of the air inlets (referring to the main air inlet 191 and the sub air inlet 192) may be adjusted according to actual needs, such as providing a plurality of air inlets on only one cover plate portion 120.

In one embodiment, the flow directing inlet 610 is elliptical. The oval shape facilitates manufacturing, and effectively reduces the manufacturing cost of the flow guide 600 while meeting certain uniform air intake requirements. Of course, the shape of the diversion inlet 610 may also be a combination of semi-ellipse and plate circle, ellipse, etc., and may be specifically adjusted according to the shape of the side arc plate 110.

Further, as shown in fig. 3, the scroll casing 100 is provided with an air outlet portion 140 extending radially outward, an outlet of the air outlet portion 140 has an axis, the auxiliary air inlet 192 has a center line parallel to the axis, and an included angle between a major axis of the ellipse and the center line ranges from 0 degrees to 90 degrees.

In the drawing, a dash-dot line located at the center of the outlet of the air outlet portion 140 is an axis thereof, and a dash-dot line parallel to the axis on the left side is a center line of the sub air intake 192, wherein a line segment having a length L1 is a major axis of an ellipse, and a line segment of L2 is a minor axis of the ellipse.

It can be understood that the inlet position of the air outlet 140 is communicated with the end of the flow channel, so that the acceleration of the centrifugal fan is separated, the gas flow rate is faster than that of other positions of the flow channel, and the suction force generated by external gas is larger, so that the gas flow rate entering the diversion inlet 610 at the corresponding position is also maximum, and the span of the diversion inlet 610 corresponding to the direction of the fast gas flow rate is larger by approaching the end of the long axis of the ellipse to the inlet position of the air outlet 140, the larger the span is corresponding to the larger the air inlet area in the direction, and the gas flow rate is effectively reduced, so as to realize the effect of more uniform air inlet.

In this embodiment, the included angle between the major axis of the ellipse and the center line is 30 degrees, and of course, the specific included angle can be adjusted according to the shape of the side arc plate portion 110 and the position adaptability of the air outlet portion 140, so that the included angle can be satisfied within the range of 0 degrees to 90 degrees.

According to one embodiment of the present utility model, as shown in connection with fig. 3 to 5, the centrifugal fan further includes an impeller 700, the impeller 700 being annularly disposed around the axis of the auxiliary air intake 192; the inner diameter D1 of the impeller 700 is smaller than the length of the minor axis L2 of the ellipse, so that as much gas as possible is ensured to enter the impeller 700 from the inner diameter of the impeller 700 or the side of the impeller 700 to be pressurized and then discharged out of the volute 100; the outer diameter D2 of the impeller 700 is larger than the length of the long axis L1 of the ellipse, so that when gas enters the volute 100, the gas is reduced to directly enter a gap between the impeller 700 and the cover plate part 120 of the volute 100, the problem that the gas cannot be pressurized through the impeller 700 is caused, the fact that as much gas as possible is discharged out of the volute 100 after being pressurized through the impeller 700 is ensured, and the overall performance of the centrifugal fan is improved.

In this example, d1=248 mm, d2=320 mm, l2=254 mm, l1=264 mm; of course, based on centrifugal fans with different size requirements, the numerical values of L1, L2, D1 and D2 can be adaptively adjusted, and the relation that D1 is less than or equal to L2 and less than L1 and less than D2 can be satisfied.

According to an embodiment of the present utility model, as shown in fig. 4 and 5, the flow guiding part 600 is provided with a second air inlet channel 620, the second air inlet channel 620 communicates the secondary air inlet 192 with the outside, and the sectional area of the second air inlet channel 620 gradually decreases along the direction of the outside toward the secondary air inlet 192. The second air inlet channel 620 ensures that the flow path of the air entering the auxiliary air inlet 192 from the outer surface of the volute 100 is gradually reduced, no abrupt change of the size of the path occurs, and abrupt change of the flow speed and the pressure of the air is avoided, so that the occurrence of flow separation phenomenon is reduced, and noise generated in the working process of the centrifugal fan is effectively reduced.

In this embodiment, the second air inlet channel 620 is funnel-shaped, and the longitudinal section of the inner wall of the flow guiding portion 600 corresponding to the second air inlet channel 620 is arc-shaped; of course, in other embodiments, the line segment of the longitudinal section of the inner wall of the flow guiding portion 600 may be a straight line, an ellipse-like, a hyperbola, or other fitting curves, etc., which are suitable for forming the second air inlet channel 620 with a gradually required cross-sectional area.

According to an embodiment of the present utility model, as shown in conjunction with fig. 4 and 5, the second air intake passage 620 extends in a direction parallel to the axis of the impeller 700 near one end of the impeller 700. The gas entering the impeller 700 from the second air inlet channel 620 is reduced in turning as much as possible, so that the turning loss of the fluid is avoided, the gas entering the impeller 700 flows more smoothly, the turbulence and vortex are reduced, and the energy efficiency of the centrifugal fan is improved; noise and vibration caused by asymmetric flow can be reduced, noise generated when the centrifugal fan operates can be reduced, and vibration influence on surrounding environment and equipment can be reduced; unnecessary centrifugal force and eccentric load can be reduced, the running balance state of the centrifugal fan can be maintained, and the vibration and stress conditions of the equipment can be reduced.

According to an embodiment of the present utility model, as shown in fig. 4 and 5, the flow guiding portion 600 is further provided with a flow guiding outlet 630, the flow guiding outlet 630 is located between the two cover plate portions 120, and along the axial direction of the impeller 700, the distance between the flow guiding outlet 630 and the cover plate portion 120 where the auxiliary air inlet 192 is located is H1, and the distance between the surface of the impeller 700 and the cover plate portion 120 where the auxiliary air inlet 192 is located is H2, where H1 is greater than H2.

The problem that gas cannot be pressurized through the impeller 700 due to the fact that the gas directly enters a gap between the impeller 700 and the cover plate portion 120 of the volute 100 when entering the volute 100 is solved, the fact that as much gas as possible is discharged out of the volute 100 after being pressurized through the impeller 700 is guaranteed, and the overall performance of the centrifugal fan is improved.

According to an embodiment of the present utility model, as shown in fig. 5, the surface of the flow guiding part 600 and the impeller 700 is provided with a relief gap 640. The avoidance gap 640 prevents the flow guiding part 600 from being collided by slight displacement caused by vibration of the impeller 700 in the operation process of the centrifugal fan, so that the collision between the flow guiding part 600 and the impeller 700 is effectively avoided, and the service life of the centrifugal fan is prolonged.

In this embodiment, a chamfer is provided on the vane on the inner diameter side of the impeller 700 to avoid the outlet of the flow guiding portion 600, however, a notch corresponding to the shape of the outlet of the flow guiding portion 600 may be provided on the vane to meet the avoidance requirement, for example, a rectangular notch is provided on the vane corresponding to the outlet of the flow guiding portion 600 with a rectangular cross section.

In this embodiment, the relief gap 640 ranges from 2 millimeters to 20 millimeters. In other embodiments, the range of the back-off gap 640 may be adaptively adjusted based on the use requirements and design requirements.

According to an embodiment of the present utility model, as shown in connection with fig. 1 and 4, the centrifugal fan further includes a motor bracket 800, and the motor bracket 800 extends from the flow guide 600 toward the inside of the scroll case 100.

It will be appreciated that since the impeller 700 of the centrifugal fan is centrifugal, the mass of the impeller 700 is not evenly distributed. If the motor bracket 800 is placed on one side of the impeller 700, unbalance may be generated in the operation of the impeller 700, causing problems such as vibration and noise. The motor bracket 800 is extended to the inside of the scroll case 100, so that the connection point of the motor and the impeller 700 is as close to the middle position of the impeller 700 as possible, the weight of the impeller 700 is balanced, vibration and noise are reduced, and the performance of the fan is improved. Meanwhile, in the process that external gas is sucked into the volute 100 under the drive of the impeller 700, the gas can have a certain cooling effect when flowing through the motor, and the service life of the centrifugal fan is effectively prolonged.

According to one embodiment of the present utility model, as shown in connection with fig. 1, the motor bracket 800 includes a plurality of support arms 810 having centers symmetrical to the axis of the auxiliary air inlet 192, and an air inlet gap 820 is formed between the support arms 810. The air intake gap 820 can form the auxiliary air intake 192, which can help to improve the uniformity of the air intake of the centrifugal fan, and avoid the generation of local surplus or insufficient air intake at the main air intake 191, thereby ensuring that the fan normally and uniformly sucks air, reducing the pressure fluctuation in the centrifugal fan, and improving the stability and reliability of the system.

In this embodiment, six support arms 810 are provided around the axis of the auxiliary air inlet 192, and six air inlet gaps 820 are formed; of course, the number of support arms 810 and the number of intake gaps 820 may be adaptively adjusted according to the actual intake requirements of the secondary intake 192.

According to the centrifugal fan of the embodiment of the application, the experimental result shows that by arranging the flow guide part 600 at the auxiliary air inlet 192, the air inlet condition of the volute 100 can be effectively improved, and compared with the conventional volute 100, the volute 100 of the centrifugal fan of the application can improve the air quantity by 20m3/h (rise by 2% in the same ratio) at the same rotation speed, and the noise can be reduced by 1.0dBA at the same air quantity.

The range hood according to the second aspect of the embodiment of the utility model comprises a box body and the centrifugal fan of the embodiment, wherein the centrifugal fan is arranged in the box body.

Finally, it should be noted that the above-mentioned embodiments are merely illustrative of the utility model, and not limiting. While the utility model has been described in detail with reference to the embodiments, those skilled in the art will appreciate that various combinations, modifications, or equivalent substitutions can be made to the technical solutions of the present utility model without departing from the spirit and scope of the technical solutions of the present utility model, and it is intended to be covered by the scope of the claims of the present utility model.

Claims

1. A centrifugal fan, comprising:

the flow guiding part and the auxiliary air inlet are coaxially arranged, the flow guiding part is provided with a flow guiding inlet, and the flow guiding inlet is suitable for increasing the air inlet area corresponding to the high flow velocity area.

2. The centrifugal fan of claim 1, wherein the flow-directing inlet is elliptical; the spiral case is provided with the air-out portion that radially extends outward, the export of air-out portion has the axis, the vice air inlet has the parallel to the central line of axis, oval major axis with the contained angle scope of central line is 0 degrees to 90 degrees.

3. The centrifugal fan according to claim 2, wherein the centrifugal fan includes an impeller disposed annularly about an axis of the secondary air intake;

4. A centrifugal fan according to claim 3, wherein the flow guiding portion is provided with a second air inlet channel, the second air inlet channel communicates the auxiliary air inlet with the outside, and the sectional area of the second air inlet channel gradually decreases along the direction of the outside toward the auxiliary air inlet.

5. The centrifugal fan of claim 4, wherein the direction of extension of the end of the second air intake passage near the impeller is parallel to the axis of the impeller.

6. A centrifugal fan according to claim 3, wherein the flow guiding portion is further provided with a flow guiding outlet, the flow guiding outlet is located between the two cover plate portions, and along the axial direction of the impeller, the distance between the flow guiding outlet and the cover plate portion where the auxiliary air inlet is located is H1, the distance between the surface of the impeller and the cover plate portion where the auxiliary air inlet is located is H2, and H1 is greater than H2.

7. A centrifugal fan according to claim 3, wherein the surface of the flow guiding part and the impeller is provided with an avoiding gap, and the range of the avoiding gap is 2-20 mm.

8. The centrifugal fan according to any one of claims 1 to 7, further comprising a motor bracket extending from the flow guide portion toward the inside of the scroll case.

9. The centrifugal fan of claim 8, wherein the motor bracket comprises a plurality of support arms which are symmetrical to the axis of the auxiliary air inlet at the center, and an air inlet gap is formed between the support arms.

10. A range hood, comprising:

A case;

a centrifugal fan according to any one of claims 1 to 9, said centrifugal fan being disposed within said housing.