Centrifugal fan and extractor hood

Abstract

The present application relates to the technical field of household appliances, and provides a centrifugal fan and an extractor hood. The centrifugal fan comprises a volute, and a flow channel formed in the volute. The volute comprises: a volute-shaped side arc plate part; cover plate parts located at two sides of the side arc plate part, at least one of the cover plate parts at the two sides being provided with an air inlet, and the air inlet being suitable for connecting a flow channel with the outside; and an arc-shaped transition part, disposed at a connection point of the side arc plate part and the cover plate part. By means of providing a transition part, when gas flows along a surface of the volute or through the interior of the flow channel, there is no position at which the geometric shape suddenly changes between the cover plate parts and the side arc plate part of the volute, thus the size of the gas flow path gradually changes, thereby avoiding rapid changes in flow speed and gas pressure caused by corners, reducing the occurrence of flow separation phenomena, and effectively reducing noise generated during operation of the centrifugal fan.

Description

Centrifugal fans and range hoods

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the priority of Chinese patent application No. 2024102609501 filed on March 7, 2024, entitled “Centrifugal fan and range hood”, the priority of Chinese patent application No. 2024204491069 filed on March 7, 2024, entitled “Centrifugal fan and range hood”, the priority of Chinese patent application No. 2024102609431 filed on March 7, 2024, entitled “Centrifugal fan and range hood”, and the priority of Chinese patent application No. 2024204491069 filed on March 7, 2024, entitled “Centrifugal fan and range hood”. The application claims priority to Chinese patent application No. 2024204490973, filed on March 7, 2024, entitled “Centrifugal fan and range hood”, the application claims priority to Chinese patent application No. 2024204490865, filed on March 7, 2024, entitled “Centrifugal fan and range hood”, and the application claims priority to Chinese patent application No. 2024204492983, filed on March 7, 2024, entitled “Centrifugal fan and range hood”, all of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the technical field of household appliances, and in particular to centrifugal fans and range hoods. Background Art

[0004] Centrifugal fans are a common core power component in range hoods due to their high suction power, low noise, and compact structure. The performance of the centrifugal fan itself directly determines the noise level of the range hood.

[0005] Summary of the Invention

[0006] The present application aims to solve at least one of the technical problems existing in the related art. To this end, the present application proposes a centrifugal fan that, by providing a transition portion, ensures that the size of the gas flow path changes gradually, avoids sudden changes in gas flow rate and pressure caused by corners, reduces the occurrence of flow separation, and effectively reduces the noise generated during the operation of the centrifugal fan.

[0007] The present application also proposes another centrifugal fan, which, by setting a smooth transition on the inner wall of the air outlet, avoids rapid changes in the flow rate and pressure of the gas on the inner wall surface of the air outlet with a non-smooth transition, thereby reducing the occurrence of flow separation, effectively reducing the noise generated when the gas flows out of the air outlet, and the problem of unstable air outlet from the air outlet.

[0008] The present application also proposes another centrifugal fan, in which the guide inlet of the guide part increases the air inlet area corresponding to the high flow velocity area, effectively improving the air intake uniformity of the secondary air inlet; and increases the overall air intake volume of the guide inlet, thereby increasing the overall air intake volume of the centrifugal fan and effectively improving the working efficiency of the centrifugal fan.

[0009] The present application also proposes another centrifugal fan, which avoids the rapid changes in gas flow rate and pressure caused by corners by setting a guide block, and forming an arc transition between the side edge of the guide block and the side arc plate of the volute, thereby reducing the occurrence of flow separation and effectively reducing the noise generated during the operation of the centrifugal fan.

[0010] The present application also provides a range hood.

[0011] The centrifugal fan provided in an embodiment of the present application includes:

[0012] A volute having a flow passage formed therein, the volute comprising a spiral-shaped side arc plate portion and cover plate portions located on both sides of the side arc plate portion, at least one of the cover plate portions on both sides being provided with an air inlet, the air inlet being adapted to connect the flow passage with the outside world;

[0013] An arc-shaped transition portion is provided at the connection between the side arc plate portion and the cover plate portion.

[0014] According to the centrifugal fan of the embodiment of the present application, external gas flows through the surface of the volute, enters the flow channel inside the volute from the air inlet, and flows out of the volute through the flow channel to achieve gas discharge.

[0015] By setting the transition portion, when the gas flows through the surface of the volute or inside the flow channel, the size of the gas flow path changes gradually because there is no position with a sudden change in geometric shape between the cover plate portion and the side arc plate portion of the volute, thereby avoiding the rapid changes in gas flow rate and pressure caused by corners, thereby reducing the occurrence of flow separation and effectively reducing the noise generated during the operation of the centrifugal fan.

[0016] In some embodiments, the transition portion includes at least one of the following:

[0017] A first transition surface is provided on the outer surface of the volute;

[0018] The second transition surface is provided on the inner surface of the volute.

[0019] In some embodiments, along the spiral air outlet direction of the volute, the curvature radius of the first transition surface or the second transition surface gradually increases.

[0020] In some embodiments, a radius of curvature of the first transition surface or the second transition surface is less than or equal to half of a width of the side arc plate portion.

[0021] In some embodiments, a transition portion having a uniform wall thickness is formed between the first transition surface and the second transition surface.

[0022] In some embodiments, the side arc plate portion and the cover plate portion are integrally formed.

[0023] In some embodiments, the volute includes at least two shell parts spliced ​​together.

[0024] In some embodiments, the volute is provided with an air outlet portion extending radially outward.

[0025] In some embodiments, the outlet of the air outlet is circular.

[0026] In some embodiments, the centrifugal fan further includes a check valve.

[0027] In some embodiments, the check valve is provided with an air outlet channel.

[0028] In some embodiments, the inlet of the air outlet channel is connected to the outlet of the air outlet portion.

[0029] In some embodiments, the cross-sectional area of ​​the air outlet channel gradually increases along the airflow direction.

[0030] In some embodiments, the centrifugal fan further includes an air guide ring.

[0031] In some embodiments, the air guide ring is provided with a first air inlet channel.

[0032] In some embodiments, the first air inlet channel connects the air inlet with the outside.

[0033] In some embodiments, the cross-sectional area of ​​the first air inlet channel gradually decreases along the direction from the outside to the air inlet.

[0034] The range hood provided in accordance with an embodiment of the present application includes:

[0035] Box;

[0036] The centrifugal fan as described above is placed in the box.

[0037] The beneficial effects of the range hood according to the embodiment of the present application are the same as the effective effects of the centrifugal fan provided in the embodiment of the present application, and will not be repeated here.

[0038] The centrifugal fan provided in an embodiment of the present application includes:

[0039] A volute, wherein the volute is provided with a flow channel, and the flow channel extends along the spiral air outlet direction of the volute;

[0040] The volute is provided with an air outlet portion extending radially outward, the inlet of the air outlet portion is connected to the end of the flow channel, and the inner wall of the volute corresponding to the end of the flow channel and the outlet of the air outlet portion is smoothly transitioned.

[0041] According to the centrifugal fan of the embodiment of the present application, the gas flows in the flow channel along the spiral air outlet direction, and is discharged from the volute from the outlet of the air outlet after passing through the air outlet portion.

[0042] In the centrifugal fan of the present invention, a smooth transition is formed from the end of the flow channel to the inner wall of the volute corresponding to the outlet of the air outlet. This prevents abrupt changes in gas velocity and pressure on the inner wall of the air outlet due to a non-smooth transition, thereby reducing flow separation and effectively reducing noise generated when gas flows out of the air outlet and any instability in the air outlet.

[0043] In some embodiments, the outer periphery of the outlet of the air outlet is a smooth curve.

[0044] In some embodiments, the centrifugal fan further includes a check valve.

[0045] In some embodiments, the check valve is provided with an air outlet channel.

[0046] In some embodiments, the inlet of the air outlet channel is connected to the outlet of the air outlet portion.

[0047] In some embodiments, the cross-sectional area of ​​the air outlet channel gradually increases along the airflow direction.

[0048] According to one embodiment of the present application, at least one of the outlet of the air outlet portion and the outlet of the check valve is circular.

[0049] In some embodiments, a volute tongue is provided on one side of the air outlet portion.

[0050] In some embodiments, the volute tongue is recessed toward the side away from the air outlet portion to form a recessed portion.

[0051] In some embodiments, the volute tongue is adapted to divert gas flowing out of the flow channel.

[0052] In some embodiments, the recessed portion comprises a smooth curved surface.

[0053] In some embodiments, the recessed portion and the inlet of the air outlet portion form a smooth structure.

[0054] In some embodiments, the outlet of the air outlet portion has an axis.

[0055] In some embodiments, the air inlet has a centerline parallel to the axis.

[0056] In some embodiments, the volute tongue is located on a side of the center line close to the air outlet.

[0057] In some embodiments, the volute includes at least two shell parts spliced ​​together.

[0058] In some embodiments, the volute tongue is detachably connected to the shell.

[0059] In some embodiments, the volute further includes a first connecting plate.

[0060] In some embodiments, the first connecting plate is provided at an end portion of the outlet of the air outlet portion and extends along a radial direction of the air outlet portion.

[0061] In some embodiments, a second connecting plate is provided at one end of the inlet of the check valve, corresponding to the first connecting plate.

[0062] The range hood provided in accordance with an embodiment of the present application includes:

[0063] Box;

[0064] The centrifugal fan as described above is placed in the box.

[0065] The beneficial effects of the range hood according to the embodiment of the present application are the same as the effective effects of the centrifugal fan provided in the embodiment of the present application, and will not be repeated here.

[0066] The centrifugal fan provided in an embodiment of the present application includes:

[0067] A volute, the volute comprising a volute-shaped side arc plate portion and cover plate portions located on both sides of the side arc plate portion, wherein the cover plate portions on both sides are respectively provided with a main air inlet and an auxiliary air inlet, and the auxiliary air inlet has a high flow rate area;

[0068] The guide portion is coaxially arranged with the auxiliary air inlet, and the guide inlet is suitable for increasing the air inlet area corresponding to the high flow rate area.

[0069] According to the centrifugal fan of the embodiment of the present application, most of the external gas enters the volute from the main air inlet, and a small amount of gas enters the volute from the secondary air inlet and is discharged along the flow channel inside the volute.

[0070] It should be noted that the shape of the auxiliary air inlet of a traditional centrifugal fan is mostly circular, and the flow channel of the volute is arranged along the circumference of the auxiliary air inlet. Since the gas is accelerated in the flow channel, the gas flow velocity in the circumferential flow channel of the auxiliary air inlet is uneven, and the corresponding suction force generated is different, resulting in uneven intake flow velocity in the circumference of the auxiliary air inlet, and then a high flow velocity area is formed in the circumference of the auxiliary air inlet.

[0071] According to the centrifugal fan of the embodiment of the present application, a guide portion is provided on the secondary air inlet, and the guide inlet of the guide portion increases the air inlet area corresponding to the high flow rate area, so that the gas flow rate at the corresponding position of the high flow rate area is reduced, thereby effectively improving the air intake uniformity of the secondary air inlet; and increasing the air intake area is conducive to increasing the overall air intake volume of the guide inlet, thereby correspondingly increasing the overall air intake volume of the centrifugal fan, and effectively improving the working efficiency of the centrifugal fan.

[0072] In some embodiments, the diversion inlet is elliptical.

[0073] In some embodiments, the volute is provided with an air outlet portion extending radially outward.

[0074] In some embodiments, the outlet of the air outlet portion has an axis.

[0075] In some embodiments, the secondary air inlet has a centerline parallel to the axis.

[0076] In some embodiments, the angle between the major axis of the ellipse and the center line ranges from 0 degrees to 90 degrees.

[0077] In some embodiments, the centrifugal fan further includes an impeller.

[0078] In some embodiments, the impeller is arranged in a ring shape around the axis of the secondary air inlet.

[0079] In some embodiments, the inner diameter of the impeller is smaller than the length of the minor axis of the ellipse.

[0080] In some embodiments, the outer diameter of the impeller is greater than the length of the major axis of the ellipse.

[0081] In some embodiments, the air guide portion is provided with a second air inlet channel.

[0082] In some embodiments, the second air inlet channel connects the secondary air inlet with the outside.

[0083] In some embodiments, the cross-sectional area of ​​the second air inlet channel gradually decreases along the direction from the outside to the secondary air inlet.

[0084] In some embodiments, an extension direction of an end of the second air inlet channel close to the impeller is parallel to the axis of the impeller.

[0085] In some embodiments, the diversion portion is further provided with a diversion outlet.

[0086] In some embodiments, the diversion outlet is located between the two cover parts.

[0087] In some embodiments, along the axial direction of the impeller, a distance between the guide outlet and the cover plate portion where the secondary air inlet is located is H1.

[0088] In some embodiments, along the axial direction of the impeller, the distance between the impeller surface and the cover plate portion where the secondary air inlet is located is H2.

[0089] In some embodiments, H1 is greater than H2.

[0090] In some embodiments, a clearance is provided between the guide portion and the surface of the impeller.

[0091] In some embodiments, the avoidance gap ranges from 2 mm to 20 mm.

[0092] In some embodiments, the centrifugal fan further includes a motor bracket.

[0093] In some embodiments, the motor bracket extends from the air guide portion toward the interior of the volute.

[0094] In some embodiments, the motor bracket includes a plurality of support arms whose centers are symmetrical to the axis of the secondary air inlet.

[0095] In some embodiments, an air inlet gap is formed between the support arms.

[0096] The range hood provided in accordance with an embodiment of the present application includes:

[0097] Box;

[0098] The centrifugal fan as described above is placed in the box.

[0099] The beneficial effects of the range hood according to the embodiment of the present application are the same as the effective effects of the centrifugal fan provided in the embodiment of the present application, and will not be repeated here.

[0100] The centrifugal fan provided in an embodiment of the present application includes:

[0101] A volute having a flow passage formed therein, the volute comprising a spiral-shaped side arc plate portion and cover plate portions located on both sides of the side arc plate portion; at least one of the cover plate portions on both sides is provided with an air inlet, the air inlet being adapted to connect the flow passage with the outside world;

[0102] The guide assembly is arranged on the cover plate portion where the air inlet is located. The guide assembly includes a guide block. The guide block extends along the circumference of the air inlet, and one side edge of the guide block transitions to the arc of the side arc plate portion.

[0103] According to the centrifugal fan of the embodiment of the present application, external gas flows through the surface of the volute, enters the flow channel inside the volute from the air inlet, and flows out of the volute through the flow channel to achieve gas discharge. By providing a guide block, the arc transition between the side of the guide block and the side arc plate of the volute ensures that the gas flow path size gradually changes from the surface of the side arc plate to the surface of the guide block, thereby avoiding the rapid changes in gas flow rate and pressure caused by corners, thereby reducing the occurrence of flow separation and effectively reducing the noise generated during the operation of the centrifugal fan.

[0104] In some embodiments, the distance between the guide block and the cover plate portion first increases and then decreases from the side arc plate portion toward the air inlet.

[0105] In some embodiments, the cross-sectional area of ​​the guide block gradually increases from the two ends of the guide block to the middle of the guide block.

[0106] In some embodiments, the cross-sectional area of ​​the guide block passes through the center of the air inlet.

[0107] In some embodiments, the end surfaces at both ends of the guide block extend in a direction pointing toward the axis of the air inlet.

[0108] In some embodiments, the centrifugal fan is adapted to be mounted to a mounting body to form a main air inlet passage between the mounting body and the cover portion.

[0109] In some embodiments, along the axial direction of the air inlet, the maximum height of the guide block is less than half of the width of the main air inlet channel.

[0110] In some embodiments, the guide assembly further includes a guide plate.

[0111] In some embodiments, the guide plate is connected to the guide block.

[0112] In some embodiments, the guide plate extends along the axial direction of the air inlet.

[0113] In some embodiments, along the extension direction of the main air inlet channel, the guide plate gradually tilts toward the air inlet.

[0114] In some embodiments, at least two guide plates are included.

[0115] In some embodiments, the guide plates are distributed on both sides of the center line of the air inlet.

[0116] In some embodiments, at least two of the guide plates are centrally symmetrical to the center line of the air inlet.

[0117] In some embodiments, the guide plate is an airfoil.

[0118] In some embodiments, the thickness of the guide plate away from the air inlet is greater than the thickness of the guide plate close to the air inlet.

[0119] The range hood provided in accordance with an embodiment of the present application includes:

[0120] Box;

[0121] The centrifugal fan as described above is placed in the box.

[0122] The beneficial effects of the range hood according to the embodiment of the present application are the same as the effective effects of the centrifugal fan provided in the embodiment of the present application, and will not be repeated here.

[0123] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0124] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0125] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0126] FIG1 is a front view of a centrifugal fan provided in an embodiment of the present application;

[0127] FIG2 is a cross-sectional view of section B1-B2 in FIG1 ;

[0128] FIG3 is a cross-sectional view of section A1-A2 in FIG1 ;

[0129] FIG4 is an exploded view of a volute of a centrifugal fan provided in an embodiment of the present application;

[0130] FIG5 is a side view of a centrifugal fan provided in an embodiment of the present application;

[0131] FIG6 is a cross-sectional view of section CC in FIG5;

[0132] FIG7 is a top view of a centrifugal fan provided in an embodiment of the present application without a check valve installed;

[0133] FIG8 is a top view of a check valve installed in a centrifugal fan provided in an embodiment of the present application;

[0134] 9 is a cross-sectional view of a volute of a centrifugal fan provided in an embodiment of the present application, taken along the axis of the air outlet;

[0135] FIG10 is a schematic structural diagram of a centrifugal fan according to an embodiment of the present application;

[0136] FIG11 is a second structural diagram of a centrifugal fan provided in an embodiment of the present application;

[0137] FIG12 is a front view of a centrifugal fan provided in an embodiment of the present application;

[0138] FIG13 is a cross-sectional view taken along section line AA in FIG12;

[0139] FIG14 is an enlarged view of a portion BB in FIG13 ;

[0140] FIG15 is a schematic structural diagram of a centrifugal fan provided in an embodiment of the present application installed in a box;

[0141] FIG16 is a cross-sectional view of a centrifugal fan provided in an embodiment of the present application installed in a box;

[0142] FIG17 is an enlarged view of a local area AA in FIG16;

[0143] FIG18 is a front view of a centrifugal fan provided in an embodiment of the present application;

[0144] FIG19 is a schematic structural diagram of a flow guide assembly of a centrifugal fan provided in an embodiment of the present application;

[0145] FIG20 is a side view of a flow guide assembly of a centrifugal fan provided in an embodiment of the present application;

[0146] FIG21 is a front view of a flow guide assembly of a centrifugal fan provided in an embodiment of the present application; and

[0147] FIG. 22 is a cross-sectional view of section DD in FIG. 19 .

[0148] Reference numerals:

[0149] 100, volute; 110, side arc plate; 120, cover plate; 130, transition portion; 131, first transition surface; 132, second transition surface; 140, air outlet; 150, flow channel; 160, first connecting plate; 190, air inlet; 170, shell;

[0150] 300, check valve; 310, air outlet channel; 320, second connecting plate;

[0151] 400, air guide ring; 410, first air inlet channel;

[0152] 500, snail tongue; 510, recess;

[0153] 1001, volute; 1101, side arc plate; 1201, cover plate; 1401, air outlet; 1911, main air inlet; 1921, auxiliary air inlet;

[0154] 6001, air guide portion; 6101, air guide inlet; 6201, second air inlet channel; 6301, air guide outlet; 6401, avoidance gap;

[0155] 7001, impeller; 8001, motor bracket; 8101, support arm; 8201, air inlet gap;

[0156] 1002, volute; 1102, side arc plate; 1202, cover plate; 1802, guide assembly; 1812, guide block; 1822, guide plate; 1502, flow channel; 1902, air inlet; 1912, main air inlet; 1922, auxiliary air inlet;

[0157] 8302, main air intake passage;

[0158] 9102, install the main body; 9202, box. DETAILED DESCRIPTION

[0159] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0160] In the description of the embodiments of the present application, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the embodiments of the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0161] In the description of the embodiments of this application, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of this application based on the specific circumstances.

[0162] In the embodiments of the present application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," and "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0163] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0164] Centrifugal fans have become common core power components in range hoods due to their advantages such as high suction, low noise and compact structure. The performance of the centrifugal fan itself directly determines the noise level of the range hood.

[0165] The applicant has discovered that the related art has the following problems.

[0166] (1) During the suction and exhaust process of a centrifugal fan, the gas tends to form flow separation on the surface and inside of the volute, generating a lot of noise.

[0167] (2) Flow separation is prone to occur at the outlet of the centrifugal fan, resulting in large fluctuations in gas flow, uneven gas discharge, and a lot of noise.

[0168] (3) Centrifugal fans are usually equipped with a main air inlet and an auxiliary air inlet. The air intake optimization of centrifugal fans is mainly set on the main air inlet with a large air intake volume. There is a problem of uneven air intake at the auxiliary air inlet.

[0169] (4) The centrifugal fan is usually installed in the housing of the range hood. When the gas in the housing flows into the centrifugal fan, there are problems of uneven flow and loud noise.

[0170] As shown in Figures 1 to 3, the centrifugal fan provided in the present application includes a volute 100, a flow channel 150 is formed inside the volute 100, the volute 100 includes a volute-shaped side arc plate portion 110 and a cover plate portion 120 located on both sides of the side arc plate portion 110, at least one of the cover plate portions 120 on both sides is provided with an air inlet 190, and the air inlet 190 is suitable for connecting the flow channel 150 with the outside world; an arc-shaped transition portion 130 is provided at the connection between the side arc plate portion 110 and the cover plate portion 120.

[0171] According to the centrifugal fan of the embodiment of the present application, external air flows through the surface of the volute 100, enters the flow channel 150 inside the volute 100 from the air inlet 190, and flows out of the volute 100 through the flow channel 150 to achieve gas discharge.

[0172] In the related art, the volute 100 of the centrifugal fan used in household appliances is usually a two-dimensional tensile structure, that is, along the axial direction of the air inlet 190, the circumferential cross-sections along different azimuth angles are all rectangular cross-sections. The gas will produce flow separation at the corners of the rectangle, and it is very easy to form a separation vortex area, resulting in unstable gas flow, and then generating noise, and the gas flow fluctuations affect the uniform air intake of the air inlet 190.

[0173] Among them, the main reasons for flow separation at corners include two aspects: pressure gradient and viscosity effect.

[0174] Corners typically experience large pressure gradients, which translates to significant changes in gas flow velocity. When gas flows through corners, the sudden change in geometry causes a dramatic change in both velocity and pressure, leading to unstable airflow and the potential for flow separation.

[0175] At corners, due to the interaction between the gas and the surface of the volute 100, the gas molecules are affected by the surface adhesion force and slow down, forming a large velocity gradient. At corners, this velocity gradient will aggravate the instability of the gas flow, making the airflow more susceptible to interference and separation.

[0176] According to the centrifugal fan of the embodiment of the present application, by providing the transition portion 130, when the gas flows through the surface of the volute 100 or inside the flow channel 150, since there is no position where the geometric shape changes suddenly between the cover plate portion 120 and the side arc plate portion 110 of the volute 100, the size of the gas flow path changes gradually, thereby avoiding the rapid changes in the flow rate and pressure of the gas caused by the corners, thereby reducing the occurrence of flow separation and effectively reducing the noise generated during the operation of the centrifugal fan.

[0177] In this embodiment, an air inlet 190 is provided on each of the cover portions 120 on both sides of the side arc plate portion 110. In some embodiments, the number and position of the air inlets 190 can be adjusted according to actual needs, such as providing an air inlet 190 on only one cover portion 120 or providing multiple air inlets 190 on one cover portion 120.

[0178] In this embodiment, as shown in Figures 1 and 2 , the width W of the volute 100 should be less than 550 mm, and the height H1 of the volute 100 should be less than 500 mm, meeting the installation requirements of a centrifugal fan in a range hood. In some embodiments, the height and width of the volute 100 can be adaptively adjusted based on different installation spaces.

[0179] In one embodiment, as shown in FIG. 2 , the transition portion 130 includes a first transition surface 131 disposed on the outer surface of the volute 100 .

[0180] By providing a first transition surface 131 on the outer surface of the volute 100, there is no position on the outer surface of the volute 100 where the geometric shape suddenly changes, so the size of the gas flow path changes gradually, thereby avoiding sudden changes in the gas flow rate and pressure, thereby reducing the occurrence of flow separation, and effectively reducing the noise generated by the gas flowing on the outer surface of the volute 100 during the operation of the centrifugal fan.

[0181] In one embodiment, as shown in FIG2 , the transition portion 130 includes a second transition surface 132 disposed on the inner surface of the volute 100. The second transition surface 132 eliminates corners within the flow passage 150, optimizes gas flow within the volute 100, effectively avoids the generation of vortices within the flow passage 150, and thereby reduces noise generated within the flow passage 150 of the volute 100.

[0182] In one embodiment, the transition portion 130 of the volute 100 may have both a first transition surface 131 and a second transition surface 132, thereby reducing the noise generated by the gas flowing through the outer and inner surfaces of the volute 100 and effectively improving the overall noise reduction effect of the centrifugal fan.

[0183] According to one embodiment of the present application, as shown in FIG. 1 to FIG. 3 , along the spiral air outlet direction of the volute 100 , the curvature radius of the first transition surface 131 or the second transition surface 132 gradually increases.

[0184] Taking the curvature radius of the second transition surface 132 as an example, along the spiral outlet direction of the volute 100, the gas within the volute 100 sequentially passes through points A1, B1, A2, and B2. That is, the curvature radius R1 corresponding to A1, the curvature radius R2 corresponding to B1, the curvature radius R3 corresponding to A2, and the curvature radius R4 corresponding to B2 increase in sequence. The curvature radius of the first transition surface 131 is similar.

[0185] In one embodiment, in order to achieve the pressurization and deceleration effect of the centrifugal fan on the gas, the cross-sectional area of ​​the flow channel 150 gradually increases along the spiral exhaust direction. In order to adapt to the changing trend of the flow channel 150, the curvature radius of the second transition surface 132 is correspondingly increased to prevent the gas in the middle position of the flow from deviating toward the second transition surface 132 due to the expansion of the cross-sectional area of ​​the flow channel 150, while the gas flow direction and size on the surface of the second transition surface 132 remain unchanged, and then the collision between the gases forms more vortices, generating noise.

[0186] In one embodiment, the curvature radius of the first transition surface 131 is gradually increased to adapt to the connection between the side arc plate portion 110 and the cover plate portion 120 that gradually deviates toward the outside of the axis of the air inlet 190, thereby effectively improving the structural strength between the two.

[0187] According to one embodiment of the present application, as shown in FIG2 , the radius of curvature of the first transition surface 131 or the second transition surface 132 is less than or equal to half the width of the side arc plate portion 110. To prevent the radius of curvature of the first transition surface 131 or the second transition surface 132 from exceeding half the width of the side arc plate portion 110, a bulge is formed in the middle of the side arc plate portion 110. The formation of the bulge affects the outer surface (corresponding to the first transition surface 131) or the inner surface (corresponding to the second transition surface 132) of the volute 100, forming a sudden change in the geometric shape, causing a sharp change in the flow rate and pressure of the gas, increasing the occurrence of flow separation, and causing more noise to be generated during the operation of the centrifugal fan.

[0188] According to one embodiment of the present application, as shown in FIG2 , a transition portion 130 with a uniform wall thickness is formed between the first transition surface 131 and the second transition surface 132. This makes the manufacturing process of the volute 100 more convenient and efficient. For example, when forging is used, the pressing process for the position of the transition portion 130 is the same as that of the cover plate portion 120 or the side arc plate portion 110, reducing the difficulty of forging. In some embodiments, the curvature radius of the first transition surface 131 and the curvature radius of the second transition surface 132 can also be set to be unequal, so as to form a transition portion 130 with a thickness different from that of the cover plate portion 120 or the side arc plate portion 110, thereby strengthening the thickness of the transition portion 130 and improving the structural strength of the volute 100.

[0189] In one embodiment, the side arc plate portion 110 and the cover plate portion 120 are integrally formed, which can eliminate the connection between multiple parts and avoid the existence of weaknesses and looseness in the volute 100 due to welding or bolting. In this way, the overall strength and stability of the volute 100 are improved. The risk of leakage at the joints and seals can be reduced, thereby reducing the loss of airflow. Especially under high-pressure and high-speed airflow conditions, the integral molding of the volute 100 can ensure the smooth and stable airflow and avoid leakage and disturbance of the airflow. It also reduces processing procedures and manual intervention, and improves production efficiency and production quality. At the same time, since the volute 100 does not have connections between multiple parts, the time and cost required for maintenance and replacement can also be reduced.

[0190] In another embodiment, as shown in FIG4 , the volute 100 includes at least two joined shell sections 170. The size, number, and shape of the shell sections 170 can be customized according to specific needs and design requirements, providing high flexibility. Furthermore, only damaged shell sections 170 need to be repaired or replaced, rather than the entire volute 100. This reduces maintenance costs and time.

[0191] In this embodiment, the volute 100 includes two shell portions 170, and the joint gap between the two shell portions 170 is located in the middle of the side arc plate portion 110. In some embodiments, the volute 100 may further include more shell portions 170 to accommodate different installation requirements of the volute 100. For example, the cover plate portion 120 or the side arc plate portion 110 may be separately formed into different shell portions 170 for jointing, and the position of the joint gap between the multiple shell portions 170 may be changed accordingly.

[0192] According to one embodiment of the present application, in combination with Figures 7 to 7, the volute 100 of the centrifugal fan is provided with an air outlet portion 140 extending radially outward, the inlet of the air outlet portion 140 is connected to the end of the flow channel 150, and the outer periphery of the outlet of the air outlet portion 140 is a smooth curve.

[0193] The outer periphery of the outlet of the air outlet portion 140 is a smooth curve, and there are no sudden changes in corners and geometric shapes at the outlet position, which avoids the rapid changes in gas flow rate and pressure caused by corners, thereby reducing the occurrence of flow separation, effectively reducing the noise generated when the gas flows out of the air outlet portion 140, and reducing gas flow fluctuations to achieve a uniform air outlet effect of the air outlet portion 140.

[0194] According to one embodiment of the present application, as shown in Figures 5, 6, and 8, a smooth transition is formed from the end of the flow channel 150 to the inner wall of the volute 100 corresponding to the outlet of the air outlet 140. This prevents the airflow on the inner wall surface of the air outlet 140 from generating a large number of vortices during the flow process due to a non-smooth transition, which may cause unstable air discharge from the air outlet 140 and generate noise.

[0195] In this embodiment, the circumferential cross-section of the flow channel 150 along the axis of the air inlet 190 and at different azimuth angles is substantially rectangular, while the outlet of the air outlet portion 140 is circular. The inner wall of the air outlet portion 140 achieves a smooth transition from the substantially rectangular to the circular shape. In some embodiments, the circumferential cross-section of the flow channel 150 and the shape of the outlet of the air outlet portion 140 can be adjusted according to actual use requirements. For example, the circumferential cross-section of the flow channel 150 is rectangular, while the outlet of the air outlet portion 140 is substantially rectangular, so as to achieve a smooth transition from rectangular to substantially rectangular.

[0196] According to one embodiment of the present application, the centrifugal fan further includes a check valve 300 , which is provided with an air outlet channel 310 , the inlet of the air outlet channel 310 is connected to the outlet of the air outlet portion 140 , and the cross-sectional area of ​​the air outlet channel 310 gradually increases along the air flow direction.

[0197] Check valve 300 effectively prevents reverse airflow, preventing excessive energy loss. Preventing reverse airflow can cause vibration, shock, and noise within the centrifugal fan, potentially damaging the equipment. Maintaining consistent airflow direction within the centrifugal fan system ensures stable pressure during system shutdown, thereby improving overall system efficiency and performance.

[0198] By gradually increasing the cross-sectional area of ​​the air outlet passage 310, eddy currents and vibrations in the air outlet passage 310 are prevented, thereby preventing noise and damage. Furthermore, the velocity of the air flowing out of the outlet of the air outlet portion 140 is further reduced, thereby reducing the pressure loss of the air and thereby improving the efficiency of the centrifugal fan.

[0199] In this embodiment, as shown in FIG1 , the height dimension H2 of the check valve 300 should be less than 500 mm to meet the installation requirements of a centrifugal fan in a range hood. In some embodiments, the height dimension of the check valve 300 can be adaptively adjusted based on different installation spaces.

[0200] According to one embodiment of the present application, as shown in Figures 7 and 8 , at least one of the outlet of the air outlet 140 and the outlet of the check valve 300 is circular. The circular outlet (referring to the outlet of the air outlet 140 and the outlet of the check valve 300) makes the gas flow from the outlet more uniform, reduces the velocity gradient and vortex intensity of the gas flow, and thus reduces the noise generated during the gas flow. Furthermore, the circular shape of the outlet of the check valve 300 can effectively adapt to the shape of the external pipeline, reducing production costs and installation difficulty.

[0201] In some embodiments, the outlet of the air outlet 140 and the outlet of the check valve 300 are not limited to circular shapes. Other shapes may be selected based on actual needs, such as elliptical, quasi-circular, quasi-rectangular, or a combination of semicircular and semi-elliptical shapes. In some embodiments, the outlet shape of the air outlet 140 may differ from the outlet shape of the check valve 300, such as the outlet of the air outlet 140 being quasi-rectangular while the outlet of the check valve 300 being circular. In some embodiments, the inner wall of the check valve 300 may be configured to smoothly transition from the outlet of the air outlet 140 to the outlet of the check valve 300 to reduce noise generated by gas flowing within the check valve 300.

[0202] According to one embodiment of the present application, as shown in conjunction with Figures 7 and 8 , when both the outlet of the air outlet portion 140 and the outlet of the check valve 300 are circular, the outlet diameter of the air outlet channel 310 is less than or equal to twice the inlet diameter of the air outlet channel 310. Avoiding a large diameter difference between the inlet and outlet of the air outlet channel 310 can lead to large speed changes during gas flow, causing gas fluctuations and vortices, resulting in increased noise, energy loss, and vibration of the check valve 300. A large inlet and outlet diameter difference can also create significant resistance to gas flow, resulting in significant pressure loss, which increases the operating cost of the centrifugal fan and reduces efficiency. It can also easily lead to uneven force inside the check valve 300, affecting the normal opening and closing of the check valve 300 and causing damage or failure of the centrifugal fan.

[0203] According to one embodiment of the present application, in combination with Figures 1 and 2, the centrifugal fan also includes an air guide ring 400, and the air guide ring 400 is provided with a first air inlet channel 410. The first air inlet channel 410 connects the air inlet 190 with the outside world, and the cross-sectional area of ​​the first air inlet channel 410 gradually decreases along the direction of the air inlet 190 pointing from the outside world to the air inlet 190.

[0204] The setting of the first air inlet channel 410 ensures that the flow path of the gas entering the air inlet 190 from the outer surface of the volute 100 gradually shrinks without sudden changes in the size of the path, thereby avoiding sudden changes in the flow rate and pressure of the gas, thereby reducing the occurrence of flow separation and effectively reducing the noise generated during the operation of the centrifugal fan.

[0205] In this embodiment, an air guide ring 400 is provided for the main air inlet 190 of the two air inlets 190 of the centrifugal fan. In some embodiments, air guide rings 400 may also be provided on all air inlets 190 to improve the noise reduction effect of the centrifugal fan.

[0206] According to one embodiment of the present application, as shown in Figures 4 to 6 , a volute tongue 500 is provided on one side of the air outlet 140. The volute tongue 500 is recessed toward the side away from the air outlet 140 to form a recessed portion 510. The volute tongue 500 is adapted to divert gas flowing out of the flow passage 150. The volute tongue 500 allows some gas to be discharged from the volute 100 along the air outlet 140, while the remaining gas circulates into the flow passage 150 to balance the static pressure within the flow passage 150.

[0207] On the one hand, the recessed portion 510 effectively increases the area of ​​the inlet of the air outlet 140, reduces the gas flow rate, and weakens the impact of the gas on the volute 500 when flowing through the inlet of the air outlet 140. On the other hand, the concave shape of the volute 500 causes a phase difference in the incoming flow impacting the volute 500 along the width direction of the volute 500 along the axis of the air inlet 190, effectively dispersing the coupling between aerodynamic noises of different frequencies. This effectively suppresses the local high-pressure area near the volute 500, reduces the pressure gradient in the axial direction of the air inlet 190, weakens the low-order unsteady flow near the wall of the volute 100, reduces the turbulent kinetic energy near the wall, improves the uniformity of the gas flow, and thus reduces noise.

[0208] In this embodiment, the recessed portion 510 is configured to fit the outlet inlet in a circular segment shape, forming a circular whole with the inner wall of the outlet inlet. This improves the stability of airflow entering the outlet, reduces the velocity gradient and vortex intensity of the gas flow, and thus reduces noise generated during gas flow. In some embodiments, the shape of the recessed portion 510 can also be configured as a rectangular or triangular notch, or other shape suitable for increasing the area of ​​the outlet inlet.

[0209] In one embodiment, the volute tongue 500 is a separate component that is detachably connected to the housing 170. This allows for customization based on specific needs and design requirements, providing greater flexibility. Furthermore, only damaged volute tongues 500 need to be repaired or replaced, eliminating the need to replace the entire volute 100. This reduces maintenance costs and time.

[0210] According to one embodiment of the present application, as shown in FIG9 , the recessed portion 510 comprises a smooth curved surface, forming a smooth structure with the inlet of the air outlet 140. This ensures that the size of the flow path of the gas flowing at the inlet of the air outlet 140 changes gradually, avoiding sudden changes in the gas flow rate and pressure, thereby reducing the occurrence of flow separation and effectively reducing the noise generated during the operation of the centrifugal fan.

[0211] According to one embodiment of the present application, as shown in Figures 4 to 6 , the outlet of the air outlet 140 has an axis, and the air inlet 190 has a centerline parallel to the axis. As shown in Figure 6 , the dotted line at the center of the outlet of the air outlet 140 is its axis, and the dotted line on the right side parallel to the axis is the centerline of the air inlet 190. The volute tongue 500 is located on the side of the centerline close to the air outlet 140. This allows the airflow direction of the air outlet 140 to extend radially outward while reducing the obstruction of the air outlet 140 and the volute tongue 500 to the gas flow, allowing the gas to be more stably separated and returned to the reflow channel 150, reducing gas rotation and turbulence, and improving the aerodynamic performance of the fan. It can also better shield the circumferential blades of the impeller inside the volute 100, preventing large particles of impurities or foreign matter from directly hitting the impeller, reducing damage and wear to the impeller, and extending the service life of the equipment.

[0212] According to one embodiment of the present application, in combination with Figures 7 and 8, the volute 100 also includes a first connecting plate 160, which is arranged at the end of the outlet of the air outlet portion 140 and extends radially along the air outlet portion 140; corresponding to the first connecting plate 160, a second connecting plate 320 is arranged at one end of the inlet of the check valve 300.

[0213] The first connecting plate 160 and the second connecting plate 320 position the connection portion outside the flow channel 150, effectively ensuring a smooth transition between the flow channel 150 of the volute 100, the inner wall of the air outlet 140, and the air outlet passage 310 of the check valve 300. This effectively prevents sudden changes in the path size of the gas flowing within the centrifugal fan, thereby avoiding sudden changes in gas flow rate and pressure. This reduces flow separation and effectively reduces noise generated during operation of the centrifugal fan. Furthermore, the first connecting plate 160 and the second connecting plate 320 facilitate direct installation in external equipment (such as the housing of a range hood), reducing the difficulty of centrifugal fan installation.

[0214] In this embodiment, the outer peripheries of the first connecting plate 160 and the second connecting plate 320 are both rectangular. In some embodiments, the outer peripheries of the first connecting plate 160 and the second connecting plate 320 can be adaptively adjusted according to the shape and position of the actual installation space.

[0215] Experimental results show that the centrifugal fan according to the embodiments of the present application, by providing a curved volute 100 with a transition portion 130 and a smooth transition design at the outlet of the air outlet 140, can effectively improve flow separation inside the fan and at the outlet, significantly reduce the presence of separation vortices, and improve the flow uniformity of the gas at the outlet of the volute 100. Compared to a conventional volute 100 with a rectangular cross-section, the centrifugal fan volute 100 of the present application can reduce noise by 2dBA at the same air volume.

[0216] The range hood provided according to an embodiment of the present application includes a housing and a centrifugal fan as described in the above embodiment, wherein the centrifugal fan is placed in the housing.

[0217] The beneficial effects of the range hood according to the embodiment of the present application are the same as the effective effects of the centrifugal fan in the embodiment of the first aspect of the present application, and will not be repeated here.

[0218] As shown in Figures 5, 6 and 8, the centrifugal fan provided in the embodiment of the present application includes a volute 100, which is provided with a flow channel 150, and the flow channel 150 extends along the spiral air outlet direction of the volute 100; the volute 100 is provided with an air outlet portion 140 extending radially outward, and the inlet of the air outlet portion 140 is connected to the end of the flow channel 150, and the inner wall of the volute 100 corresponding to the outlet of the air outlet portion 140 smoothly transitions from the end of the flow channel 150 to the outlet of the air outlet portion 140.

[0219] According to the centrifugal fan of the embodiment of the present application, the gas flows in the flow channel 150 along the spiral air outlet direction, passes through the air outlet portion 140 , and is discharged from the volute 100 from the outlet of the air outlet portion 140 .

[0220] In the related art, the volute 100 of the centrifugal fan used in household appliances is usually a two-dimensional tensile structure, that is, along the axial direction of the air inlet 190, the circumferential cross-sections along different azimuth angles are all rectangular cross-sections. The gas will produce flow separation at the corners of the rectangle, and it is very easy to form a separation vortex area, resulting in unstable gas flow, and then generating noise, and the gas flow fluctuations affect the uniform air intake of the air inlet 190.

[0221] Among them, the main reasons for flow separation at corners include two aspects: pressure gradient and viscosity effect.

[0222] Corners typically experience large pressure gradients, which translates to significant changes in gas flow velocity. When gas flows through corners, the sudden change in geometry causes a dramatic change in both velocity and pressure, leading to unstable airflow and the potential for flow separation.

[0223] At corners, due to the interaction between the gas and the surface of the volute 100, the gas molecules are affected by the surface adhesion force and slow down, forming a large velocity gradient. At corners, this velocity gradient will aggravate the instability of the gas flow, making the airflow more susceptible to interference and separation.

[0224] In the centrifugal fan of the present embodiment, a smooth transition is formed from the end of the flow channel 150 to the inner wall of the volute 100 corresponding to the outlet of the air outlet 140. This prevents abrupt changes in the flow velocity and pressure of the gas on the inner wall surface of the air outlet 140 due to a non-smooth transition, thereby reducing the occurrence of flow separation, effectively reducing the noise generated when the gas flows out of the air outlet 140, and reducing the instability of the air outlet 140.

[0225] In this embodiment, the circumferential cross-section of the flow channel 150 along the axis of the air inlet 190 and at different azimuth angles is substantially rectangular, while the outlet of the air outlet portion 140 is circular. The inner wall of the air outlet portion 140 achieves a smooth transition from the substantially rectangular to the circular shape. In some embodiments, the circumferential cross-section of the flow channel 150 and the shape of the outlet of the air outlet portion 140 can be adjusted according to actual use requirements. For example, the circumferential cross-section of the flow channel 150 is rectangular, while the outlet of the air outlet portion 140 is substantially rectangular, so as to achieve a smooth transition from rectangular to substantially rectangular.

[0226] According to one embodiment of the present application, in combination with Figures 5, 6 and 8, by setting the outer periphery of the outlet of the air outlet portion 140 to be a smooth curve, there are no sudden changes in corners and geometric shapes at the outlet position, thereby avoiding the rapid changes in gas flow rate and pressure caused by corners, thereby reducing the occurrence of flow separation, effectively reducing the noise generated when the gas flows out of the air outlet portion 140, and reducing gas flow fluctuations to achieve a uniform air outlet effect of the air outlet portion 140.

[0227] According to one embodiment of the present application, the centrifugal fan further includes a check valve 300 , which is provided with an air outlet channel 310 , the inlet of the air outlet channel 310 is connected to the outlet of the air outlet portion 140 , and the cross-sectional area of ​​the air outlet channel 310 gradually increases along the air flow direction.

[0228] Check valve 300 effectively prevents reverse airflow, preventing excessive energy loss. Preventing reverse airflow can cause vibration, shock, and noise within the centrifugal fan, potentially damaging the equipment. Maintaining consistent airflow direction within the centrifugal fan system ensures stable pressure during system shutdown, thereby improving overall system efficiency and performance.

[0229] By gradually increasing the cross-sectional area of ​​the air outlet passage 310, eddy currents and vibrations in the air outlet passage 310 are prevented, thereby preventing noise and damage. Furthermore, the velocity of the air flowing out of the outlet of the air outlet portion 140 is further reduced, thereby reducing the pressure loss of the air and thereby improving the efficiency of the centrifugal fan.

[0230] In this embodiment, as shown in FIG1 , the height dimension H2 of the check valve 300 should be less than 500 mm to meet the installation requirements of a centrifugal fan in a range hood. In some embodiments, the height dimension of the check valve 300 can be adaptively adjusted based on different installation spaces.

[0231] According to one embodiment of the present application, as shown in Figures 7 and 8 , at least one of the outlet of the air outlet 140 and the outlet of the check valve 300 is circular. The circular outlet (referring to the outlet of the air outlet 140 and the outlet of the check valve 300) makes the gas flow from the outlet more uniform, reduces the velocity gradient and vortex intensity of the gas flow, and thus reduces the noise generated during the gas flow. Furthermore, the circular shape of the outlet of the check valve 300 can effectively adapt to the shape of the external pipeline, reducing production costs and installation difficulty.

[0232] In some embodiments, the outlet of the air outlet 140 and the outlet of the check valve 300 are not limited to circular shapes. Other shapes may be selected based on actual needs, such as elliptical, quasi-circular, quasi-rectangular, or a combination of semicircular and semi-elliptical shapes. In some embodiments, the outlet shape of the air outlet 140 may differ from the outlet shape of the check valve 300, such as the outlet of the air outlet 140 being quasi-rectangular while the outlet of the check valve 300 being circular. In some embodiments, the inner wall of the check valve 300 may be configured to smoothly transition from the outlet of the air outlet 140 to the outlet of the check valve 300 to reduce noise generated by gas flowing within the check valve 300.

[0233] According to one embodiment of the present application, as shown in conjunction with Figures 7 and 8 , when both the outlet of the air outlet portion 140 and the outlet of the check valve 300 are circular, the outlet diameter of the air outlet channel 310 is less than or equal to twice the inlet diameter of the air outlet channel 310. Avoiding a large diameter difference between the inlet and outlet of the air outlet channel 310 can lead to large speed changes during gas flow, causing gas fluctuations and vortices, resulting in increased noise, energy loss, and vibration of the check valve 300. A large inlet and outlet diameter difference can also create significant resistance to gas flow, resulting in significant pressure loss, which increases the operating cost of the centrifugal fan and reduces efficiency. It can also easily lead to uneven force inside the check valve 300, affecting the normal opening and closing of the check valve 300 and causing damage or failure of the centrifugal fan.

[0234] According to one embodiment of the present application, as shown in Figures 4 to 6 , a volute tongue 500 is provided on one side of the air outlet 140. The volute tongue 500 is recessed toward the side away from the air outlet 140 to form a recessed portion 510. The volute tongue 500 is adapted to divert gas flowing out of the flow passage 150. The volute tongue 500 allows some gas to be discharged from the volute 100 along the air outlet 140, while the remaining gas circulates into the flow passage 150 to balance the static pressure within the flow passage 150.

[0235] On the one hand, the recessed portion 510 effectively increases the area of ​​the inlet of the air outlet 140, reduces the gas flow rate, and weakens the impact of the gas on the volute 500 when flowing through the inlet of the air outlet 140. On the other hand, the concave shape of the volute 500 causes a phase difference in the incoming flow impacting the volute 500 along the width direction of the volute 500 along the axis of the air inlet 190, effectively dispersing the coupling between aerodynamic noises of different frequencies. This effectively suppresses the local high-pressure area near the volute 500, reduces the pressure gradient in the axial direction of the air inlet 190, weakens the low-order unsteady flow near the wall of the volute 100, reduces the turbulent kinetic energy near the wall, improves the uniformity of the gas flow, and thus reduces noise.

[0236] In this embodiment, the recessed portion 510 is configured to fit the outlet inlet in a circular segment shape, forming a circular whole with the inner wall of the outlet inlet. This improves the stability of airflow entering the outlet, reduces the velocity gradient and vortex intensity of the gas flow, and thus reduces noise generated during gas flow. In some embodiments, the shape of the recessed portion 510 can also be configured as a rectangular or triangular notch, or other shape suitable for increasing the area of ​​the outlet inlet.

[0237] In one embodiment, the volute tongue 500 is a separate component that is detachably connected to the housing 170. This allows for customization based on specific needs and design requirements, providing greater flexibility. Furthermore, only damaged volute tongues 500 need to be repaired or replaced, eliminating the need to replace the entire volute 100. This reduces maintenance costs and time.

[0238] According to one embodiment of the present application, as shown in FIG9 , the recessed portion 510 comprises a smooth curved surface, forming a smooth structure with the inlet of the air outlet 140. This ensures that the size of the flow path of the gas flowing at the inlet of the air outlet 140 changes gradually, avoiding sudden changes in the gas flow rate and pressure, thereby reducing the occurrence of flow separation and effectively reducing the noise generated during the operation of the centrifugal fan.

[0239] According to one embodiment of the present application, as shown in Figures 4 to 6 , the outlet of the air outlet 140 has an axis, and the air inlet 190 has a centerline parallel to the axis. As shown in Figure 6 , the dotted line at the center of the outlet of the air outlet 140 is its axis, and the dotted line on the right side parallel to the axis is the centerline of the air inlet 190. The volute tongue 500 is located on the side of the centerline close to the air outlet 140. This allows the airflow direction of the air outlet 140 to extend radially outward while reducing the obstruction of the air outlet 140 and the volute tongue 500 to the gas flow, allowing the gas to be more stably separated and returned to the reflow channel 150, reducing gas rotation and turbulence, and improving the aerodynamic performance of the fan. It can also better shield the circumferential blades of the impeller inside the volute 100, preventing large particles of impurities or foreign matter from directly hitting the impeller, reducing damage and wear to the impeller, and extending the service life of the equipment.

[0240] According to one embodiment of the present application, in combination with Figures 7 and 8, the volute 100 also includes a first connecting plate 160, which is arranged at the end of the outlet of the air outlet portion 140 and extends radially along the air outlet portion 140; corresponding to the first connecting plate 160, a second connecting plate 320 is arranged at one end of the inlet of the check valve 300.

[0241] The first connecting plate 160 and the second connecting plate 320 position the connection portion outside the flow channel 150, effectively ensuring a smooth transition between the flow channel 150 of the volute 100, the inner wall of the air outlet 140, and the air outlet passage 310 of the check valve 300. This effectively prevents sudden changes in the path size of the gas flowing within the centrifugal fan, thereby avoiding sudden changes in gas flow rate and pressure. This reduces flow separation and effectively reduces noise generated during operation of the centrifugal fan. Furthermore, the first connecting plate 160 and the second connecting plate 320 facilitate direct installation in external equipment (such as the housing of a range hood), reducing the difficulty of centrifugal fan installation.

[0242] In this embodiment, the outer peripheries of the first connecting plate 160 and the second connecting plate 320 are both rectangular. In some embodiments, the outer peripheries of the first connecting plate 160 and the second connecting plate 320 can be adaptively adjusted according to the shape and position of the actual installation space.

[0243] As shown in Figures 1 to 3, according to one embodiment of the present application, the volute 100 includes a volute-shaped side arc plate portion 110 and a cover plate portion 120 located on both sides of the side arc plate portion 110, at least one of the cover plate portions 120 on both sides is provided with an air inlet 190, and the air inlet 190 is suitable for connecting the flow channel 150 with the outside world; an arc-shaped transition portion 130 is provided at the connection between the side arc plate portion 110 and the cover plate portion 120.

[0244] By providing the transition portion 130, when the gas flows through the surface of the volute 100 or inside the flow channel 150, since there is no position where the geometric shape changes suddenly between the cover plate portion 120 and the side arc plate portion 110 of the volute 100, the size of the gas flow path changes gradually, thereby avoiding the rapid changes in gas flow rate and pressure caused by corners, thereby reducing the occurrence of flow separation and effectively reducing the noise generated during the operation of the centrifugal fan.

[0245] In this embodiment, an air inlet is provided on each of the cover portions 120 on both sides of the side arc plate portion 110. In some embodiments, the number and position of the air inlets can be adjusted according to actual needs, such as providing an air inlet on only one cover portion 120 or providing multiple air inlets on one cover portion 120.

[0246] In this embodiment, as shown in Figures 1 and 2 , the width W of the volute 100 should be less than 550 mm, and the height H1 of the volute 100 should be less than 500 mm, meeting the installation requirements of a centrifugal fan in a range hood. In some embodiments, the height and width of the volute 100 can be adaptively adjusted based on different installation spaces.

[0247] In one embodiment, as shown in FIG. 2 , the transition portion 130 includes a first transition surface 131 disposed on the outer surface of the volute 100 .

[0248] By providing a first transition surface 131 on the outer surface of the volute 100, there is no position on the outer surface of the volute 100 where the geometric shape suddenly changes, so the size of the gas flow path changes gradually, thereby avoiding sudden changes in the gas flow rate and pressure, thereby reducing the occurrence of flow separation, and effectively reducing the noise generated by the gas flowing on the outer surface of the volute 100 during the operation of the centrifugal fan.

[0249] In one embodiment, as shown in FIG2 , the transition portion 130 includes a second transition surface 132 disposed on the inner surface of the volute 100. The second transition surface 132 eliminates corners within the flow passage 150, optimizes gas flow within the volute 100, effectively avoids the generation of vortices within the flow passage 150, and thereby reduces noise generated within the flow passage 150 of the volute 100.

[0250] In one embodiment, the transition portion 130 of the volute 100 may have both a first transition surface 131 and a second transition surface 132, thereby reducing the noise generated by the gas flowing through the outer and inner surfaces of the volute 100 and effectively improving the overall noise reduction effect of the centrifugal fan.

[0251] According to one embodiment of the present application, as shown in FIG. 1 to FIG. 3 , along the spiral air outlet direction of the volute 100 , the curvature radius of the first transition surface 131 or the second transition surface 132 gradually increases.

[0252] Taking the radius of curvature of the second transition surface 132 as an example, along the spiral outlet direction of the volute 100, the air within the volute 100 sequentially passes through points A1, B1, A2, and B2. That is, the curvature radius R1 corresponding to A1, the curvature radius R2 corresponding to B1, the curvature radius R3 corresponding to A2, and the curvature radius R4 corresponding to B2 increase in that order. In some embodiments, the curvature radius of the first transition surface 131 is similarly defined.

[0253] In one embodiment, in order to achieve the pressurization and deceleration effect of the centrifugal fan on the gas, the cross-sectional area of ​​the flow channel 150 gradually increases along the spiral exhaust direction. In order to adapt to the changing trend of the flow channel 150, the curvature radius of the second transition surface 132 is correspondingly increased to prevent the gas in the middle position of the flow from deviating toward the second transition surface 132 due to the expansion of the cross-sectional area of ​​the flow channel 150, while the gas flow direction and size on the surface of the second transition surface 132 remain unchanged, and then the collision between the gases forms more vortices, generating noise.

[0254] In one embodiment, the curvature radius of the first transition surface 131 is gradually increased to adapt to the connection between the side arc plate portion 110 and the cover plate portion 120 that gradually deviates toward the outside of the axis of the air inlet 190, thereby effectively improving the structural strength between the two.

[0255] According to one embodiment of the present application, as shown in FIG2 , the radius of curvature of the first transition surface 131 or the second transition surface 132 is less than or equal to half the width of the side arc plate portion 110. To prevent the radius of curvature of the first transition surface 131 or the second transition surface 132 from exceeding half the width of the side arc plate portion 110, a bulge is formed in the middle of the side arc plate portion 110. The formation of the bulge affects the outer surface (corresponding to the first transition surface 131) or the inner surface (corresponding to the second transition surface 132) of the volute 100, forming a sudden change in the geometric shape, causing a sharp change in the flow rate and pressure of the gas, increasing the occurrence of flow separation, and causing more noise to be generated during the operation of the centrifugal fan.

[0256] According to one embodiment of the present application, as shown in FIG2 , a transition portion 130 with a uniform wall thickness is formed between the first transition surface 131 and the second transition surface 132. This makes the manufacturing process of the volute 100 more convenient and efficient. For example, when forging is used, the pressing process for the position of the transition portion 130 is the same as that of the cover plate portion 120 or the side arc plate portion 110, reducing the difficulty of forging. In some embodiments, the curvature radius of the first transition surface 131 and the curvature radius of the second transition surface 132 can also be set to be unequal, so as to form a transition portion 130 with a thickness different from that of the cover plate portion 120 or the side arc plate portion 110, thereby strengthening the thickness of the transition portion 130 and improving the structural strength of the volute 100.

[0257] In one embodiment, the side arc plate portion 110 and the cover plate portion 120 are integrally formed, which can eliminate the connection between multiple parts and avoid the existence of weaknesses and looseness in the volute 100 due to welding or bolting. In this way, the overall strength and stability of the volute 100 are improved. The risk of leakage at the joints and seals can be reduced, thereby reducing the loss of airflow. Especially under high-pressure and high-speed airflow conditions, the integral molding of the volute 100 can ensure the smooth and stable airflow and avoid leakage and disturbance of the airflow. It also reduces processing procedures and manual intervention, and improves production efficiency and production quality. At the same time, since the volute 100 does not have connections between multiple parts, the time and cost required for maintenance and replacement can also be reduced.

[0258] In another embodiment, as shown in FIG4 , the volute 100 includes at least two joined shell sections 170. The size, number, and shape of the shell sections 170 can be customized according to specific needs and design requirements, providing high flexibility. Furthermore, only damaged shell sections 170 need to be repaired or replaced, rather than the entire volute 100. This reduces maintenance costs and time.

[0259] In this embodiment, the volute 100 includes two shell portions 170, and the joint gap between the two shell portions 170 is located in the middle of the side arc plate portion 110. In some embodiments, the volute 100 may further include more shell portions 170 to accommodate different installation requirements of the volute 100. For example, the cover plate portion 120 or the side arc plate portion 110 may be separately formed into different shell portions 170 for jointing, and the position of the joint gap between the multiple shell portions 170 may be changed accordingly.

[0260] According to one embodiment of the present application, in combination with Figures 1 and 2, the centrifugal fan also includes an air guide ring 400, and the air guide ring 400 is provided with a first air inlet channel 410. The first air inlet channel 410 connects the air inlet 190 with the outside world, and the cross-sectional area of ​​the first air inlet channel 410 gradually decreases along the direction of the air inlet 190 pointing from the outside world to the air inlet 190.

[0261] The setting of the first air inlet channel 410 ensures that the flow path of the gas entering the air inlet 190 from the outer surface of the volute 100 gradually shrinks without sudden changes in the size of the path, thereby avoiding sudden changes in the flow rate and pressure of the gas, thereby reducing the occurrence of flow separation and effectively reducing the noise generated during the operation of the centrifugal fan.

[0262] In this embodiment, an air guide ring 400 is provided for the main air inlet 190 of the two air inlets 190 of the centrifugal fan. In some embodiments, air guide rings 400 may also be provided on all air inlets 190 to improve the noise reduction effect of the centrifugal fan.

[0263] Experimental results show that the centrifugal fan according to the embodiments of the present application, by providing a curved volute 100 with a transition portion 130 and a smooth transition design at the outlet of the air outlet 140, effectively improves flow separation inside the fan and at the outlet, significantly reduces the presence of separation vortices, and improves the flow uniformity of the gas at the outlet of the volute 100. Compared to a conventional volute 100 with a rectangular cross-section, the centrifugal fan volute 100 of the present application can reduce noise by 2dB at the same air volume.

[0264] The range hood provided according to an embodiment of the present application includes a housing and a centrifugal fan as described in the above embodiment, wherein the centrifugal fan is placed in the housing.

[0265] The beneficial effects of the range hood according to the embodiment of the present application are the same as the effective effects of the centrifugal fan in the embodiment of the first aspect of the present application, and will not be repeated here.

[0266] As shown in Figures 10 to 14, the centrifugal fan provided in the embodiment of the present application includes a volute 1001 and a guide portion 6001. The volute 1001 includes a volute-shaped side arc plate portion 1101 and a cover plate portion 1201 located on both sides of the side arc plate portion 1101. The cover plate portions 1201 on both sides are respectively provided with a main air inlet 1911 and an auxiliary air inlet 1921, and the auxiliary air inlet 1921 has a high flow velocity area; the guide portion 6001 is coaxially arranged with the auxiliary air inlet 1921, and the guide portion 6001 is provided with a guide inlet 6101, which is suitable for increasing the air inlet area corresponding to the high flow velocity area.

[0267] According to the centrifugal fan of the embodiment of the present application, most of the external gas enters the volute 1001 from the main air inlet 1911, and a small amount of gas enters the volute 1001 from the secondary air inlet 1921. These two parts of gas are accelerated along the flow channel inside the volute 1001 and then discharged.

[0268] It should be noted that the shape of the auxiliary air inlet 1921 of a traditional centrifugal fan is mostly circular, and the flow channel of the volute 1001 is arranged along the circumference of the auxiliary air inlet 1921. Since the gas is accelerated in the flow channel, the gas flow velocity in the circumferential flow channel of the auxiliary air inlet 1921 is uneven, and the corresponding suction force generated is different, resulting in uneven flow velocity of the circumferential air intake of the auxiliary air inlet 1921, and thus a high flow velocity area is formed in the circumference of the auxiliary air inlet 1921.

[0269] According to the centrifugal fan of the embodiment of the present application, by arranging a guide portion 6001 on the secondary air inlet 1921, the guide inlet 6101 of the guide portion increases the air inlet area corresponding to the high flow rate area, so that the gas flow rate at the corresponding position of the high flow rate area is reduced, and the air intake uniformity of the secondary air inlet 1921 is effectively improved; and the increase in the air intake area is conducive to increasing the overall air intake volume of the guide inlet 6101, which correspondingly increases the overall air intake volume of the centrifugal fan, and effectively improves the working efficiency of the centrifugal fan.

[0270] The term "high velocity zone" is a relative term, referring to an area with a higher gas velocity relative to other locations circumferentially around the secondary air inlet 1921. In this embodiment, as shown in Figures 10 and 12, the location of the secondary air inlet 1921 corresponding to the line L1 in Figure 12 is the center of the high velocity zone, with high velocity zones forming two sides of it. In some embodiments, the location of the high velocity zone can be adaptively adjusted around the circumference of the secondary air inlet 1921 based on the structural configuration of different centrifugal fans.

[0271] In this embodiment, the guide portion 6001 is integrally formed with the volute 1001 for ease of manufacture. In some embodiments, the guide portion 6001 can also be a separate component detachably connected to the secondary air inlet 1921 to allow replacement of guide portions 6001 of different specifications according to usage requirements.

[0272] In this embodiment, the guide portion 6001 is provided at the secondary air inlet 1921 to make the air intake of the secondary air inlet 1921 more uniform. In some embodiments, the guide portion 6001 can also be provided at the primary air inlet 1911 to improve the air intake uniformity of the primary air inlet 1911.

[0273] In this embodiment, a primary air inlet 1911 and a secondary air inlet 1921 are respectively provided on the cover plate portion 1201 on both sides of the side arc plate portion 1101. The number and position of the air inlets (referring to the primary air inlet 1911 and the secondary air inlet 1921) can be adjusted according to actual needs, such as providing multiple air inlets on only one cover plate portion 1201.

[0274] In one embodiment, the air guide inlet 6101 is elliptical. This elliptical shape facilitates manufacturing, effectively reducing the manufacturing cost of the air guide 6001 while meeting certain uniform air intake requirements. In some embodiments, the shape of the air guide inlet 6101 can also be a combination of a semi-ellipse and a plate circle, or a similar ellipse, and can be adjusted based on the shape of the side arc plate 1101.

[0275] 12 , the volute 1001 is provided with an air outlet 1401 extending radially outward, the outlet of the air outlet 1401 has an axis, the secondary air inlet 1921 has a center line parallel to the axis, and the angle between the major axis of the ellipse and the center line ranges from 0 degrees to 90 degrees.

[0276] In the figure, the dotted line at the center of the outlet of the air outlet 1401 is its axis, and the dotted line on the left side parallel to this axis is the center line of the secondary air inlet 1921, where the line segment with a length of L1 is the major axis of the ellipse, and the line segment with a length of L2 is the minor axis of the ellipse.

[0277] In some embodiments, the inlet position of the air outlet 1401 is connected to the end of the flow channel, which is about to be separated from the acceleration effect of the centrifugal fan. The gas flow rate is faster than other positions of the flow channel, and the suction force on the external gas is greater. Therefore, the gas flow rate entering the guide inlet 6101 at the corresponding position is also the largest. By placing the end of the major axis of the ellipse close to the inlet position of the air outlet 1401, the span of the guide inlet 6101 corresponding to the direction with fast gas flow rate is larger, and the larger the span, the larger the air intake area in this direction, thereby effectively reducing the gas flow rate to achieve a more uniform air intake effect.

[0278] In this embodiment, the angle between the major axis of the ellipse and the center line is 30 degrees. In some embodiments, the specific angle can be adaptively adjusted according to the shape of the side arc plate portion 1101 and the position of the air outlet portion 1401, and can be within the range of 0 degrees to 90 degrees.

[0279] According to one embodiment of the present application, in combination with Figures 12 to 14, the centrifugal fan also includes an impeller 7001, which is annularly arranged around the axis of the secondary air inlet 1921; the inner diameter D1 of the impeller 7001 is smaller than the length of the minor axis L2 of the ellipse, ensuring that as much gas as possible enters the impeller 7001 from the inner diameter of the impeller 7001 or the side of the impeller 7001 and is pressurized before being discharged from the volute 1001; the outer diameter D2 of the impeller 7001 is larger than the length of the major axis L1 of the ellipse, reducing the problem that the gas directly enters the gap between the impeller 7001 and the cover plate portion 1201 of the volute 1001 when entering the volute 1001, resulting in the inability to pass through the impeller 7001 for pressurization, ensuring that as much gas as possible is discharged from the volute 1001 after passing through the impeller 7001 for pressurization, thereby improving the overall performance of the centrifugal fan.

[0280] In this embodiment, D1 = 245 mm, D2 = 320 mm, L2 = 254 mm, and L1 = 264 mm. In some embodiments, based on centrifugal fans of different size requirements, the values ​​of L1, L2, D1, and D2 can be adaptively adjusted to satisfy the relationship D1 ≤ L2 < L1 < D2.

[0281] According to one embodiment of the present application, as shown in conjunction with Figures 13 and 14 , the air guide portion 6001 is provided with a second air inlet channel 6201. The second air inlet channel 6201 connects the secondary air inlet 1921 with the outside world, and the cross-sectional area of ​​the second air inlet channel 6201 gradually decreases in the direction from the outside world to the secondary air inlet 1921. The provision of the second air inlet channel 6201 ensures that the flow path of the gas entering the secondary air inlet 1921 from the outer surface of the volute 1001 gradually decreases, without a sudden change in the size of the path, thereby avoiding abrupt changes in the flow rate and pressure of the gas, thereby reducing the occurrence of flow separation and effectively reducing the noise generated during the operation of the centrifugal fan.

[0282] In this embodiment, the second air inlet channel 6201 is funnel-shaped, and the longitudinal cross-section of the inner wall of the air guide portion 6001 corresponding to the second air inlet channel 6201 is arc-shaped. In other embodiments, the line segments of the longitudinal cross-section of the inner wall of the air guide portion 6001 may also be straight lines, ellipses, quasi-ellipses, hyperbolas, or other fitted curves, etc., as long as they are suitable for forming a second air inlet channel 6201 with a desired cross-sectional area.

[0283] According to one embodiment of the present application, as shown in FIG13 and FIG14 , the extension direction of one end of the second air inlet channel 6201 close to the impeller 7001 is parallel to the axis of the impeller 7001. This minimizes the turning of the gas entering the impeller 7001 from the second air inlet channel 6201, avoids fluid turning losses, and makes the gas flow into the impeller 7001 smoother, reducing the generation of turbulence and eddies, thereby improving the energy efficiency of the centrifugal fan. Furthermore, the noise and vibration caused by asymmetric flow can be reduced, reducing the noise during operation of the centrifugal fan and reducing the vibration impact on the surrounding environment and equipment. Furthermore, unnecessary centrifugal force and eccentric load can be reduced, maintaining the balanced state of the centrifugal fan operation and reducing the vibration and stress of the equipment.

[0284] According to one embodiment of the present application, in combination with Figures 13 and 14, the guide portion 6001 is further provided with a guide outlet 6301, which is located between the two cover plate portions 1201, and along the axial direction of the impeller 7001, the distance between the guide outlet 6301 and the cover plate portion 1201 where the auxiliary air inlet 1921 is located is H1, and the distance between the surface of the impeller 7001 and the cover plate portion 1201 where the auxiliary air inlet 1921 is located is H2, and H1 is greater than H2.

[0285] Reduce the problem that the gas directly enters the gap between the impeller 7001 and the cover plate part 1201 of the volute 1001 when entering the volute 1001, resulting in the inability to be pressurized by the impeller 7001, and ensure that as much gas as possible is discharged from the volute 1001 after being pressurized by the impeller 7001, thereby improving the overall performance of the centrifugal fan.

[0286] According to one embodiment of the present application, as shown in FIG14 , a clearance gap 6401 is provided between the surfaces of the air guide 6001 and the impeller 7001. The clearance gap 6401 prevents slight displacement of the impeller 7001 due to vibration from colliding with the air guide 6001 during operation of the centrifugal fan, effectively preventing collisions between the air guide 6001 and the impeller 7001 and thereby extending the service life of the centrifugal fan.

[0287] In this embodiment, the blades on the inner diameter side of the impeller 7001 are chamfered to avoid the outlet of the guide portion 6001. In some embodiments, a notch corresponding to the shape of the outlet of the guide portion 6001 can also be provided on the blade to meet the avoidance requirement, such as a rectangular notch provided on the blade corresponding to the outlet of the guide portion 6001 with a rectangular cross-section.

[0288] In this embodiment, the range of the avoidance gap 6401 is 2 mm to 20 mm. In other embodiments, the range of the avoidance gap 6401 can be adaptively adjusted based on usage requirements and design requirements.

[0289] According to an embodiment of the present application, in combination with FIG. 10 and FIG. 13 , the centrifugal fan further includes a motor bracket 8001 , and the motor bracket 8001 extends from the air guide portion 6001 toward the interior of the volute 1001 .

[0290] In some embodiments, since the impeller 7001 of the centrifugal fan is centrifugal, the mass of the impeller 7001 will not be evenly distributed. If the motor bracket 8001 is placed on one side of the impeller 7001, the impeller 7001 may become unbalanced during operation, causing problems such as vibration and noise. The motor bracket 8001 is extended to the inside of the volute 1001 so that the connection point between the motor and the impeller 7001 is as close as possible to the middle position of the impeller 7001, balancing the weight of the impeller 7001, reducing vibration and noise, and improving the performance of the fan. At the same time, when the external gas is sucked into the volute 1001 under the drive of the impeller 7001, the gas can play a certain cooling role when flowing through the motor, effectively improving the service life of the centrifugal fan.

[0291] According to one embodiment of the present application, as shown in FIG10 , the motor bracket 8001 includes a plurality of support arms 8101 that are centrally symmetrical about the axis of the secondary air inlet 1921, with air inlet gaps 8201 formed between the support arms 8101. The air inlet gaps 8201 can form the secondary air inlet 1921, which can help improve the uniformity of the air intake of the centrifugal fan and avoid localized excess or insufficient air intake at the main air inlet 1911, thereby ensuring that the fan normally and evenly inhales air, reducing pressure fluctuations in the centrifugal fan, and improving the stability and reliability of the system.

[0292] In this embodiment, six support arms 8101 are provided around the axis of the secondary air inlet 1921, forming six air inlet gaps 8201. In some embodiments, the number of support arms 8101 and the number of air inlet gaps 8201 can be adaptively adjusted according to the actual air intake requirements of the secondary air inlet 1921.

[0293] According to the centrifugal fan of the embodiment of the present application, combined with the experimental results, it is shown that by setting the guide part 6001 at the auxiliary air inlet 1921, the air intake condition of the volute 1001 can be effectively improved. Compared with the conventional volute 1001, the air volume of the volute 1001 of the centrifugal fan of the present application can be increased by 20m at the same speed. 3 / h (up 2% year-on-year), the noise can be reduced by 1.0dBA at the same air volume.

[0294] The range hood provided according to an embodiment of the present application includes a housing and a centrifugal fan as described in the above embodiment, wherein the centrifugal fan is placed in the housing.

[0295] The beneficial effects of the range hood according to the embodiment of the present application are the same as the effective effects of the centrifugal fan provided in the embodiment of the present application, and will not be repeated here.

[0296] As shown in Figures 15 to 17, the centrifugal fan provided in the embodiment of the present application includes a volute 1002 and a guide assembly 1802, a flow channel 1502 is formed inside the volute 1002, the volute 1002 includes a volute-shaped side arc plate portion 1102 and a cover plate portion 1202 located on both sides of the side arc plate portion 1102; at least one of the cover plate portions 1202 on both sides is provided with an air inlet 1902, and the air inlet 1902 is suitable for connecting the flow channel 1502 with the outside world; the guide assembly 1802 is provided on the cover plate portion 1202 where the air inlet 1902 is located, and the guide assembly 1802 includes a guide block 1812, which extends along the circumference of the air inlet 1902, and one side edge of the guide block 1812 transitions to the arc of the side arc plate portion 1102.

[0297] According to the centrifugal fan of the embodiment of the present application, external air flows through the surface of the volute 1002, enters the flow channel 1502 inside the volute 1002 from the air inlet 1902, and flows out of the volute 1002 through the flow channel 1502, thereby achieving gas discharge.

[0298] In the related art, the volute 1002 of the centrifugal fan used in household appliances is usually a two-dimensional tensile structure, that is, along the axial direction of the air inlet 1902, the circumferential cross-sections along different azimuth angles are all rectangular cross-sections. The gas will produce flow separation at the corners of the rectangle, and it is very easy to form a separation vortex area, resulting in unstable gas flow, and then generating noise, and the gas flow fluctuations affect the uniform air intake of the air inlet 1902.

[0299] Among them, the main reasons for flow separation at corners include two aspects: pressure gradient and viscosity effect.

[0300] Corners typically experience large pressure gradients, which translates to significant changes in gas flow velocity. When gas flows through corners, the sudden change in geometry causes a dramatic change in both velocity and pressure, leading to unstable airflow and the potential for flow separation.

[0301] At corners, the interaction between the gas and the surface of volute 1002 causes the gas molecules to slow down due to surface adhesion, forming a large velocity gradient. This velocity gradient exacerbates the instability of the gas flow at corners, making the airflow more susceptible to disturbances and separation, and easily forming low-velocity areas. This occupies the area of ​​the gas passageway entering the air inlet 1902, increasing the overall exhaust resistance within the appliance.

[0302] According to the centrifugal fan of the embodiment of the present application, by setting the guide block 1812, the arc transition between the side of the guide block 1812 and the side arc plate portion 1102 of the volute 1002 is ensured to ensure that the size of the gas flow path gradually changes from the surface of the side arc plate portion 1102 to the surface of the guide block 1812, thereby avoiding the rapid changes in gas flow rate and pressure caused by the corners, thereby reducing the occurrence of flow separation phenomenon, and effectively reducing the noise generated during the operation of the centrifugal fan.

[0303] The following description will be made in conjunction with the actual use environment of the centrifugal fan, wherein the centrifugal fan is installed in a mounting body 9102, and the mounting body 9102 may be a case 9202 of a range hood, a housing of an air purifier, or the like.

[0304] Taking the box 9202 placed in the range hood as an example, as shown in Figure 15, the inlet of the box 9202 is located at the bottom. Along the gas flow direction indicated by the arrow, the external air is divided into two parts. As shown in Figure 16, the air inlet 1902 includes a main air inlet 1912 and an auxiliary air inlet 1922. A larger part enters the main air inlet 1912, and a smaller part enters the auxiliary air inlet 1922. The gas flowing to the main air inlet 1912 will flow along the surface of the side arc plate portion 1102, and flow to the surface of the cover plate portion 1202 through the arc transition between the guide plate 1822 and the side arc plate portion 1102, and then enter the main air inlet 1912.

[0305] In some embodiments, in this embodiment, the position of the guide block 1812 corresponding to the inlet of the box 9202 is set between the air inlet 1902 and the inlet of the box 9202; therefore, when the gas flow direction of the external gas relative to the centrifugal fan changes, such as setting the inlet of the box 9202 on the side (the front or rear side as shown in the figure), the guide block 1812 can be set on the side of the air inlet 1902 accordingly, ensuring that the guide block 1812 is located between the inlet of the box 9202 and the air inlet 1902.

[0306] In this embodiment, an air inlet 1902 is provided on each of the cover portions 1202 on both sides of the side arc plate portion 1102, serving as a primary air inlet 1912 and a secondary air inlet 1922, respectively. In some embodiments, the number and position of the air inlets 1902 can be adjusted based on actual needs, such as providing an air inlet 1902 on only one cover portion 1202 or providing multiple air inlets 1902 on one cover portion 1202.

[0307] In this embodiment, a guide block 1812 is provided corresponding to the main air inlet 1912. In some embodiments, a guide block 1812 may also be provided on the cover portion 1202 on one side of the auxiliary air inlet 1902 to further reduce the noise of the centrifugal fan.

[0308] 18 , the guide block 1812 is disposed partially around the circumference of the air inlet 1902. In some embodiments, to improve the uniformity of the air intake around the entire periphery of the air inlet 1902, the guide block 1812 may be annular and disposed around the air inlet 1902.

[0309] In this embodiment, the guide block 1812 is detachably connected to the cover portion 1202 , and the size and shape of the guide block 1812 can be customized according to specific needs and design requirements, with high flexibility.

[0310] In another embodiment, the guide block 1812 is integrally formed with the cover plate 1202, eliminating the need for multiple component connections and preventing weaknesses and looseness in the volute 1002 caused by welding or bolting. This improves the overall strength and stability of the volute 1002, reduces the risk of leakage at joints and seals, and thus reduces airflow loss. This also reduces processing steps and manual intervention, improving production efficiency and quality.

[0311] In this embodiment, the overall width of the guide block 1812 (along the radial direction of the air inlet 1902) is smaller than the width of the cover portion 1202, so as to prevent the guide block 1812 from exceeding the cover portion 1202 to form corners and cause flow separation.

[0312] According to one embodiment of the present application, as shown in conjunction with Figures 16 and 17 , the distance between the guide block 1812 and the cover plate portion 1202 increases first and then decreases from the side arc plate portion 1102 toward the air inlet 1902. This causes the flow path of the gas outside the air inlet 1902 to decrease first and then increase as it flows from the side arc plate portion 1102 toward the air inlet 1902. This ensures that the gas already has a component velocity along the axial direction of the air inlet 1902 before entering the air inlet 1902, making the air entering the air inlet 1902 more stable.

[0313] In this embodiment, the cross-section of the guide block 1812 is an airfoil, that is, the thickness of the end close to the side arc plate is greater than the thickness of the end close to the air inlet 1902, thereby reducing the probability of flow separation on the side where the side arc plate 1102 is connected to the guide block 1812, and reducing the noise of the centrifugal fan.

[0314] In some embodiments, the cross-section of the guide block 1812 can also be a semicircle, a circle, a partial ellipse, or other smooth fitting curve to ensure that when the gas outside the air inlet 1902 flows from the side arc plate 1102 to the air inlet 1902, the flow path of the gas first decreases and then increases.

[0315] According to one embodiment of the present application, as shown in conjunction with FIG15 and FIG18 to FIG22 , the cross-sectional area of ​​the guide block 1812 gradually increases from the ends of the guide block 1812 toward the center of the guide block 1812, and the cross-sectional area of ​​the guide block 1812 passes through the center of the air inlet 1902. That is, along the axis of the air inlet 1902, the cross-sectional area of ​​the guide block 1812 gradually changes along the circumference at different azimuth angles, and reaches the maximum cross-sectional area at the center of the guide block 1812. Because the guide block 1812 is at least partially disposed around the air inlet 1902 and is disposed between the line connecting the external inlet (such as the inlet of the housing 9202) and the air inlet 1902 in the direction of external gas flow, the center of the guide block 1812 is located on the line connecting the external inlet and the center of the air inlet 1902, and the corresponding air inlet 1902 has the largest span in the direction of gas flow, which is therefore most likely to cause uneven gas flow.

[0316] By setting the two ends of the guide block 1812 to point to the middle of the guide block 1812, the cross-sectional area of ​​the guide block 1812 gradually increases, so that in the direction of gas flow, the larger the span of the air inlet 1902, the larger the cross-sectional area of ​​the guide block 1812, thereby reducing the size of the gas flow path, making the circumferential air intake of the air inlet 1902 more uniform, which can effectively reduce the vortex and turbulence in the gas flow, and improve the operating efficiency of the centrifugal fan; reduce the turbulence and non-uniformity inside the centrifugal fan, reduce the noise generation, and improve the working environment and comfort of the centrifugal fan.

[0317] According to one embodiment of the present application, as shown in Figures 18 and 19 , the end faces of the guide block 1812 extend in the direction of the axis of the air inlet 1902. This ensures that the end face extension direction is parallel to the circumferential air intake direction of the air inlet 1902, thereby preventing excessive flow separation at the end face during gas flow, which would generate noise and reduce the uniformity of air intake at the air inlet 1902.

[0318] In other embodiments, the guide block 1812 may not be provided with an end face, that is, the surface of the guide block 1812 and the surface of the cover portion 1202 have a smooth transition, which is conducive to the integral molding of the guide block 1812 and the cover portion 1202 and can also effectively avoid the occurrence of flow separation at the end of the guide block 1812.

[0319] According to one embodiment of the present application, in combination with Figures 15 to 17, the centrifugal fan is suitable for being installed on the mounting body 9102 to form a main air inlet channel 8302 between the mounting body 9102 and the cover portion 1202. The main air inlet channel 8302 confines the external gas within a certain space, thereby improving the suction efficiency of the centrifugal fan. Along the axial direction of the air inlet 1902, the maximum height of the guide block 1812 is less than half the width of the main air inlet channel 8302. While the guide block 1812 improves the air intake uniformity of the air inlet 1902, its maximum height will not block the main air inlet channel 8302, thereby avoiding obstruction to the gas flow in the main air inlet channel 8302, avoiding the formation of a large velocity gradient, and effectively avoiding the generation of noise from the centrifugal fan.

[0320] According to one embodiment of the present application, in combination with Figures 15 to 18, the guide assembly 1802 also includes a guide plate 1822, which is connected to the guide block 1812, and the guide plate 1822 extends along the axial direction of the air inlet 1902; along the extension direction of the main air inlet channel 8302, the guide plate 1822 gradually tilts toward the air inlet 1902.

[0321] In this embodiment, combined with what is shown in FIG18 , “along the extension direction of the main air inlet channel 8302, the guide plate 1822 gradually tilts toward the air inlet 1902.” In some embodiments, as shown in the figure, the gas flows from the B21 and C21 sides to the B11 and C11 sides, and point B11 is closer to the center of the air inlet 1902 than point B21, and point C11 is closer to the center of the air inlet 1902 than point C21.

[0322] The guide plate 1822 is suitable for guiding the flow direction of the gas originally flowing along the gas flow direction to be as biased as possible towards the center of the air inlet 1902, so that more gas enters the air inlet 1902 from a position with a large span of the air inlet 1902, thereby improving the uniformity of the air intake, reducing the generation of vortices, and thus improving the operating efficiency of the centrifugal fan.

[0323] The guide plate 1822 can also protect the impeller and other internal components of the centrifugal fan, prevent debris or foreign matter from directly entering the air inlet 1902, reduce damage and wear inside the centrifugal fan, and extend the service life of the centrifugal fan.

[0324] In this embodiment, two guide plates 1822 are provided. In some embodiments, the number of guide plates 1822 can be adjusted accordingly based on actual diversion requirements, and the spacing between the guide plates 1822 can also be adaptively adjusted. For example, the guide plates 1822 can be more densely packed in locations with high gas flow to reduce the gas flow rate and flow rate.

[0325] In this embodiment, the height of the guide plate 1822 relative to the cover portion 1202 is greater than 0.1 times the width of the main air inlet channel 8302 and less than the width of the main air inlet channel 8302. While playing a guiding role, it will not significantly reduce the efficiency of gas flowing into the air inlet 1902.

[0326] In this embodiment, the thickness of the guide plate 1822 (along the circumference of the air inlet 1902) ranges from 1 mm to 10 mm. In some embodiments, the thickness of the guide plate 1822 can be adaptively adjusted according to the actual air intake demand of the air inlet 1902; and the thickness of the guide plate 1822 can be uniform and constant. In some embodiments, it can also be gradually changed, such as the thickness of one end of the guide plate 1822 is 1 mm and the thickness of the other end is 10 mm, so as to achieve the diversion effect while avoiding the flow separation of gas on the surface of the guide plate 1822. In some embodiments, the connection between the guide plate 1822 and the guide block 1812 can also be further reduced by using an arc transition to further reduce the generation of corners.

[0327] In this embodiment, along the main air inlet channel 8302 pointing to the center of the air inlet 1902, the guide plate 1822 and the guide block 1812 are of the same width, reducing the corners formed at the connection between the guide plate 1822 and the guide block 1812 and reducing the occurrence of flow separation.

[0328] According to one embodiment of the present application, in combination with Figures 18 and 19, the guide assembly 1802 includes at least two guide plates 1822, and the guide plates 1822 are distributed on both sides of the center line of the air inlet 1902. The guide plates 1822 located on both sides of the center line (the dotted line in the upper and lower directions in the figure) have a gathering effect on the gas flowing along the center line, so that the gas is gathered to the center of the air inlet 1902 in advance, and the span of the air inlet 1902 passing the center line is the largest, corresponding to taking on more gas, thereby effectively improving the air intake uniformity of the air inlet 1902.

[0329] According to one embodiment of the present application, as shown in conjunction with Figures 18 and 19 , at least two deflectors 1822 are symmetrically centered about the centerline of the air inlet 1902. As shown in Figure 18 , in this embodiment, there are two deflectors 1822, and the distance d1 between the left deflector 1822 and the centerline of the air inlet 1902 is equal to the distance between the right deflector 1822 and the centerline. Accordingly, because the deflection arcs of the deflectors 1822 are the same, the gas guided by the two deflectors 1822 necessarily flows along the centerline of the air inlet 1902, effectively ensuring uniformity of air intake at the air inlet 1902.

[0330] In some embodiments, more guide plates 1822 , such as three, may be provided. In this case, one of the guide plates 1822 is located on the center line of the air inlet 1902 to ensure that the gas after guidance flows toward the center of the air inlet 1902 .

[0331] According to one embodiment of the present application, as shown in FIG. 18 and FIG. 19 , the guide plate 1822 is an airfoil plate, and the thickness of the guide plate 1822 on the side away from the air inlet 1902 is greater than the thickness on the side close to the air inlet 1902 .

[0332] In this embodiment, the thickness at B21 and C21 corresponding to FIG18 is greater than the thickness at B11 and C11, that is, the thickness at one end close to the side arc plate is greater than the thickness at one end close to the air inlet 1902, thereby reducing the probability of flow separation near the side of the side arc plate 1102 and reducing the noise of the centrifugal fan.

[0333] In this embodiment, the cross-section of the guide plate 1822 is an airfoil. The curvature and angle of the airfoil surface will affect the flow state of the gas, avoiding the generation of vortices, separation and other phenomena, thereby affecting the flow speed and pressure distribution of the gas and avoiding the generation of noise.

[0334] According to the centrifugal fan of the embodiment of the present application, combined with experimental results, it is shown that by providing the guide component 1802, the flow separation of the gas flowing outside the volute 1002 of the centrifugal fan can be effectively improved, the presence of separation vortices can be greatly reduced, and the flow uniformity of the gas entering the air inlet 1902 can be improved. Compared with the conventional rectangular cross-section volute 1002, the volute 1002 of the centrifugal fan of the present application can increase the air volume by 30m3 at the same speed. 3 / h (up 3% year-on-year), the noise can be reduced by 1.0dBA at the same air volume;

[0335] The range hood provided according to an embodiment of the present application includes a housing 9202 and a centrifugal fan as described in the above embodiment, and the centrifugal fan is placed in the housing 9202 .

[0336] The beneficial effects of the range hood according to the embodiment of the present application are the same as the effective effects of the centrifugal fan provided in the embodiment of the application, and will not be repeated here.

[0337] Finally, it should be noted that the above embodiments are intended only to illustrate the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications, or equivalent substitutions of the technical solutions of the present application do not depart from the scope of the technical solutions of the present application and should be encompassed by the claims of the present application.

Claims

1. A centrifugal fan comprising: A volute having a flow passage formed therein, the volute comprising a spiral-shaped side arc plate portion and cover plate portions located on both sides of the side arc plate portion, at least one of the cover plate portions on both sides being provided with an air inlet, the air inlet being adapted to connect the flow passage with the outside world; An arc-shaped transition portion is provided at the connection between the side arc plate portion and the cover plate portion.

2. The centrifugal fan according to claim 1, wherein: The transition portion includes at least one of the following: A first transition surface is provided on the outer surface of the volute; The second transition surface is provided on the inner surface of the volute.

3. The centrifugal fan according to claim 2, wherein: Along the spiral air outlet direction of the volute, the curvature radius of the first transition surface or the second transition surface gradually increases.

4. The centrifugal fan according to claim 2 or 3, wherein: The curvature radius of the first transition surface or the second transition surface is less than or equal to half the width of the side arc plate portion.

5. The centrifugal fan according to any one of claims 2 to 4, wherein: The transition portion with uniform wall thickness is formed between the first transition surface and the second transition surface.

6. The centrifugal fan according to any one of claims 1 to 5, wherein: The side arc plate portion and the cover plate portion are integrally formed; or, The volute includes at least two shell parts spliced ​​together.

7. The centrifugal fan according to any one of claims 1 to 6, wherein: The volute is provided with an air outlet portion extending radially outward, and the outlet of the air outlet portion is circular.

8. The centrifugal fan according to claim 7, wherein: The centrifugal fan further includes a check valve, which is provided with an air outlet channel. The inlet of the air outlet channel is connected to the outlet of the air outlet portion, and the cross-sectional area of ​​the air outlet channel gradually increases along the airflow direction.

9. The centrifugal fan according to any one of claims 1 to 8, wherein: The centrifugal fan also includes an air guide ring, which is provided with a first air inlet channel. The first air inlet channel connects the air inlet with the outside world, and the cross-sectional area of ​​the first air inlet channel gradually decreases along the direction from the outside world to the air inlet.

10. A range hood comprising: Box; The centrifugal fan according to any one of claims 1 to 9, wherein the centrifugal fan is placed in the casing.

11. A centrifugal fan comprising: A volute, wherein the volute is provided with a flow channel, and the flow channel extends along the spiral air outlet direction of the volute; The volute is provided with an air outlet portion extending radially outward, the inlet of the air outlet portion is connected to the end of the flow channel, and the inner wall of the volute corresponding to the end of the flow channel and the outlet of the air outlet portion is smoothly transitioned.

12. The centrifugal fan according to claim 11, wherein: The outer periphery of the outlet of the air outlet portion is a smooth curve.

13. The centrifugal fan according to claim 11 or 12, wherein: The centrifugal fan further includes a check valve, which is provided with an air outlet channel. The inlet of the air outlet channel is connected to the outlet of the air outlet portion, and the cross-sectional area of ​​the air outlet channel gradually increases along the airflow direction.

14. The centrifugal fan according to claim 13, wherein: At least one of the outlet of the air outlet portion and the outlet of the check valve is circular.

15. The centrifugal fan according to any one of claims 11 to 14, wherein: A volute tongue is provided on one side of the air outlet portion. The volute tongue is recessed toward the side away from the air outlet portion to form a recessed portion. The volute tongue is suitable for diverting the gas flowing out of the flow channel.

16. The centrifugal fan according to claim 15, wherein: The recessed portion includes a smooth curved surface, and the recessed portion and the inlet of the air outlet portion form a smooth structure.

17. The centrifugal fan according to claim 15 or 16, wherein: The outlet of the air outlet has an axis, the air inlet has a center line parallel to the axis, and the volute tongue is located on a side of the center line close to the air outlet.

18. The centrifugal fan according to any one of claims 15 to 17, wherein: The volute comprises at least two shell parts spliced ​​together, and the volute tongue is detachably connected to the shell parts.

19. The centrifugal fan according to any one of claims 13 to 18, wherein: The volute further includes a first connecting plate, which is provided at the end of the outlet of the air outlet portion and extends in the radial direction of the air outlet portion; Corresponding to the first connecting plate, a second connecting plate is provided at one end of the inlet of the check valve.

20. A range hood comprising: Box; The centrifugal fan according to any one of claims 11 to 19, wherein the centrifugal fan is placed in the casing.

21. A centrifugal fan comprising: A volute, the volute comprising a volute-shaped side arc plate portion and cover plate portions located on both sides of the side arc plate portion, wherein the cover plate portions on both sides are respectively provided with a main air inlet and an auxiliary air inlet, and the auxiliary air inlet has a high flow rate area; The guide portion is coaxially arranged with the auxiliary air inlet, and the guide portion is provided with a guide inlet, which is suitable for increasing the air inlet area corresponding to the high flow rate area.

22. The centrifugal fan according to claim 21, wherein The guide inlet is an ellipse; the volute is provided with an air outlet extending radially outward, the outlet of the air outlet has an axis, the secondary air inlet has a center line parallel to the axis, and the angle between the major axis of the ellipse and the center line ranges from 0 degrees to 90 degrees.

23. The centrifugal fan according to claim 22, wherein: The centrifugal fan includes an impeller, which is annularly arranged around the axis of the secondary air inlet; The inner diameter of the impeller is smaller than the length of the minor axis of the ellipse, and the outer diameter of the impeller is larger than the length of the major axis of the ellipse.

24. The centrifugal fan according to claim 23, wherein: The guide portion is provided with a second air inlet channel, which connects the secondary air inlet with the outside world. The cross-sectional area of ​​the second air inlet channel gradually decreases along the direction from the outside world to the secondary air inlet.

25. The centrifugal fan according to claim 24, wherein: An extension direction of an end of the second air inlet channel close to the impeller is parallel to the axis of the impeller.

26. The centrifugal fan according to any one of claims 23 to 25, wherein: The guide portion is also provided with a guide outlet, which is located between the two cover plate portions. Along the axial direction of the impeller, the distance between the guide outlet and the cover plate portion where the secondary air inlet is located is H1, and the distance between the impeller surface and the cover plate portion where the secondary air inlet is located is H2, and H1 is greater than H2.

27. The centrifugal fan according to any one of claims 23 to 26, wherein: An avoidance gap is provided between the guide portion and the surface of the impeller, and the avoidance gap ranges from 2 mm to 20 mm.

28. The centrifugal fan according to any one of claims 21 to 27, wherein: The centrifugal fan further includes a motor bracket, which extends from the air guide portion toward the interior of the volute.

29. The centrifugal fan according to claim 28, wherein The motor bracket includes a plurality of support arms whose centers are symmetrical to the axis of the secondary air inlet, and air inlet gaps are formed between the support arms.

30. A range hood comprising: Box; The centrifugal fan according to any one of claims 21 to 29, wherein the centrifugal fan is placed in the casing.

31. A centrifugal fan comprising: A volute having a flow passage formed therein, the volute comprising a spiral-shaped side arc plate portion and cover plate portions located on both sides of the side arc plate portion; at least one of the cover plate portions on both sides is provided with an air inlet, the air inlet being adapted to connect the flow passage with the outside world; The guide assembly is arranged on the cover plate portion where the air inlet is located. The guide assembly includes a guide block. The guide block extends along the circumference of the air inlet, and one side edge of the guide block transitions to the arc of the side arc plate portion.

32. The centrifugal fan according to claim 31, wherein The distance between the guide block and the cover plate portion first increases and then decreases from the side arc plate portion toward the air inlet.

33. The centrifugal fan according to claim 31 or 32, wherein: The cross-sectional area of ​​the guide block gradually increases from the two ends of the guide block to the middle of the guide block, and the cross-sectional area of ​​the guide block passes through the center of the air inlet.

34. The centrifugal fan according to claim 33, wherein: The end surfaces at both ends of the guide block extend in directions pointing to the axis of the air inlet.

35. The centrifugal fan according to any one of claims 31 to 34, wherein: The centrifugal fan is adapted to be mounted on the mounting body so as to form a main air inlet passage between the mounting body and the cover portion; Along the axial direction of the air inlet, the maximum height of the guide block is less than half of the width of the main air inlet channel.

36. The centrifugal fan according to claim 35, wherein: The guide assembly further includes a guide plate, the guide plate being connected to the guide block and extending along the axis of the air inlet; Along the extension direction of the main air inlet channel, the guide plate gradually tilts toward the air inlet.

37. The centrifugal fan according to claim 36, wherein: It comprises at least two guide plates, which are distributed on both sides of the center line of the air inlet.

38. The centrifugal fan according to claim 37, wherein: At least two of the guide plates are centrally symmetrical to the center line of the air inlet.

39. The centrifugal fan according to any one of claims 36 to 38, wherein: The guide plate is an airfoil plate, and the thickness of the guide plate at a side away from the air inlet is greater than the thickness at a side close to the air inlet.

40. A range hood comprising: Box; The centrifugal fan according to any one of claims 31 to 39, wherein the centrifugal fan is placed in the casing.

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