Centrifugal fan

Abstract

A centrifugal fan comprises a volute assembly which comprises a front cover and a shell, the front cover is provided with a main air inlet and is arranged on the front side of the centrifugal fan, and the shell is provided with an air outlet; the motor assembly comprises a motor and an output shaft, the motor is fixed to the shell and arranged on the rear side of the centrifugal fan, and the output shaft extends into the volute assembly; the impeller assembly comprises a front plate, a back plate and main blades, the front plate is arranged on the front side relative to the back plate, the back plate is provided with an auxiliary air inlet, the main blades are located between the front plate and the back plate, the main blades are configured to suck air from the main air inlet, and the impeller assembly is configured to rotate under the action of the output shaft; the impeller assembly comprises a main flow channel and an auxiliary flow channel, the main flow channel communicates with the main air inlet and the air outlet, the auxiliary flow channel communicates with the auxiliary air inlet and the air outlet, and the main flow channel and the auxiliary flow channel are at least partially spaced.

Description

TECHNICAL FIELD

[0001] The utility model relates to a centrifugal fan more particularly, relate to a kind of anti-leakage centrifugal fan. BACKGROUND

[0002] Centrifugal fan inhales airflow by impeller and does work to airflow to generate high-pressure airflow, because the output shaft of motor drives impeller to rotate, so there is gap between the output shaft of motor and shell in general case. Although sealing member can be arranged between the output shaft of motor and shell, but sealing member can be caused to be poor in sealing effect after long-term operation due to aging abrasion, so that part of airflow leaks. Gas at the rear side of centrifugal fan is communicated with the gas at the outer periphery of impeller which is worked by impeller, so that the rear side of centrifugal fan is in positive pressure state, and positive pressure state is easy to cause gas to leak to the outside of centrifugal fan through motor shaft, causing certain security risk.

[0003] In prior art, in order to solve the technical problem caused by airflow leakage, secondary blades are arranged at the rear side of impeller, the secondary blades inhale leakage airflow at the rear side of centrifugal fan, so that the rear side of centrifugal fan is in negative pressure state, to improve the problem of airflow leakage. However, the airflow generated by primary blades and secondary blades interferes with each other, on the one hand, the primary airflow generated by primary blades can weaken the negative pressure effect at the rear side of impeller, on the other hand, the secondary airflow generated by secondary blades can also weaken the high-pressure airflow generated by primary blades, thereby adversely affecting the performance of centrifugal fan.

[0004] Therefore, it is desirable to provide a centrifugal fan to improve the defects in prior art. SUMMARY

[0005] According to an aspect of the utility model, a kind of centrifugal fan is provided, comprising: volute assembly, comprising front cover and shell, front cover has primary air inlet and is arranged at the front side of centrifugal fan, volute assembly has air outlet;Motor assembly, comprising motor and output shaft, motor is fixed to shell and is arranged at the rear side of centrifugal fan, output shaft extends to the inside of volute assembly;Impeller assembly, comprising front plate, back plate and primary blade, front plate is arranged at front side relative to back plate, back plate has secondary air inlet, primary blade is located between front plate and back plate, primary blade is configured to inhale gas from primary air inlet, impeller assembly is configured to rotate under the action of output shaft;Wherein, impeller assembly includes primary flow channel and secondary flow channel, primary flow channel is communicated with primary air inlet and air outlet, secondary flow channel is communicated with secondary air inlet and air outlet, primary flow channel and secondary flow channel are at least partially spaced apart.

[0006] According to the scheme, by primary flow channel and secondary flow channel are at least partially spaced apart, the interference between the primary airflow generated by primary blade and the secondary airflow generated by secondary blade is avoided, so that the performance of centrifugal fan is improved.

[0007] In some embodiments, the impeller assembly can further include a baffle plate arranged between the main flow channel and the secondary flow channel to at least partially separate the main flow channel and the secondary flow channel.

[0008] According to this embodiment, the baffle plate can separate the main airflow generated by the main blades from the secondary airflow generated by the secondary blades, thereby avoiding the main airflow and the secondary airflow from interfering with each other.

[0009] In some embodiments, the baffle plate can have a disc shape and extend outwardly from the central axis in a radial direction to the main blades, the main flow channel being located at a front side of the baffle plate, and the secondary flow channel being located at a rear side of the baffle plate.

[0010] In some embodiments, the back plate can be formed with a recess recessed toward the front side, the recess having a recess bottom plate facing the back plate and a recess side plate extending from the recess bottom plate to the back plate, a plurality of through slots being formed in the recess side plate, and the through slots forming the secondary flow channel.

[0011] According to this embodiment, the recessed structure forming the secondary flow channel can be manufactured by a process without increasing materials, thereby reducing the cost of the centrifugal fan.

[0012] In some embodiments, the recess side plate can extend in a direction perpendicular to the back plate.

[0013] In some embodiments, the recess bottom plate can be provided with secondary blades configured to draw in air from the secondary air inlet.

[0014] In some embodiments, the secondary blades can extend from the recess bottom plate to the inner side of the back plate.

[0015] According to this embodiment, the height of the secondary blades does not exceed the back plate, which is conducive to the miniaturization of the centrifugal fan.

[0016] In some embodiments, the secondary blades can be flipped out from the recess bottom plate through the material at the through slots.

[0017] In some embodiments, the recess side plate can extend from the recess bottom plate to the back plate in a direction radially outward.

[0018] According to this embodiment, the inclined recess side plate facilitates the formation of the air inlet at the opening of the recess side plate, and the recessed shape facilitates the gathering of the airflow from the rear side of the back plate, so that the secondary blades can no longer be additionally arranged, making the structure of the centrifugal fan simpler and reducing the cost.

[0019] In some embodiments, the recess side plate can be configured to draw in air from the secondary air inlet.

[0020] In some embodiments, the through slots can penetrate through the recess side plate to the inner side of the back plate.

[0021] In some embodiments, the baffle plate can be attached to the recessed bottom plate.

[0022] In some embodiments, the baffle plate, the recessed bottom plate, and the back plate can each have an axial hole aligned with each other, and the axial hole can be aligned with the output shaft.

[0023] In some embodiments, the baffle plate can be fixed to the output shaft by a nut.

[0024] In some embodiments, the impeller assembly can include a main impeller configured to draw air from a main air inlet, a front plate formed as a front side housing of the main impeller, and a main flow passage located in the main impeller; a sub-impeller arranged at a rear side of the main impeller and configured to draw air from a sub-air inlet, a sub-flow passage located in the sub-impeller, and a back plate formed as a rear side housing of the sub-impeller.

[0025] According to the embodiments, the flow passage of the main impeller and the flow passage of the sub-impeller are isolated from each other, preventing mutual interference between the air flow generated by the main impeller and the air flow generated by the sub-impeller.

[0026] In some embodiments, the rear side housing of the main impeller can be attached to the front side housing of the sub-impeller.

[0027] In some embodiments, the centrifugal fan can further include a sealing gasket arranged between the output shaft and the housing.

[0028] In some embodiments, the main impeller and the sub-impeller can be closed impellers such that the main flow passage and the sub-flow passage are spaced apart.

[0029] In some embodiments, the height of the sub-impeller in the axial direction can be between 1 / 4 and 1 / 2 of the height of the main impeller in the axial direction.

[0030] In some embodiments, the height of the sub-impeller in the axial direction can be 1 / 3 of the height of the main impeller in the axial direction.

[0031] In some embodiments, the air outlet can be located at a radial outer periphery of the housing.

[0032] In some embodiments, the impeller assembly can be manufactured by any one of sheet metal, casting, or welding.

[0033] In some embodiments, the centrifugal fan can further include a sealing groove arranged on an outer peripheral surface of the housing facing the front cover, and a sealing strip placed in the sealing groove for sealing between the housing and the front cover.

[0034] In some embodiments, the sealing groove can be coated with a sealant.

[0035] According to the scheme, the sealing strip is placed in the groove to prevent gas from leaking through the contact surface, and can also assist in filling and sealing the sealant, and through the sealing strip and the sealant, the long-term sealing requirement can be met. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 An external schematic view of a centrifugal fan according to an embodiment of the present application is shown;

[0037] Figure 2 A cross-sectional view of a centrifugal fan according to a first embodiment of the present application is shown;

[0038] Figure 3 A schematic view of an impeller assembly according to the first embodiment of the present application is shown;

[0039] Figure 4 A cross-sectional view of an impeller assembly according to the first embodiment of the present application is shown;

[0040] Figure 5 A cross-sectional view of a centrifugal fan according to a second embodiment of the present application is shown;

[0041] Figure 6 A schematic view of an impeller assembly according to the second embodiment of the present application is shown;

[0042] Figure 7 A cross-sectional view of an impeller assembly according to the second embodiment of the present application is shown;

[0043] Figure 8 A cross-sectional view of a centrifugal fan according to a third embodiment of the present application is shown.

[0044] REFERENCE NUMERALS:

[0045] 100 centrifugal fan

[0046] 110 volute assembly

[0047] 112 front cover

[0048] 114 housing

[0049] 116 main air inlet

[0050] 118 air outlet

[0051] 120 motor assembly

[0052] 122 motor

[0053] 124 output shaft

[0054] 130 impeller assembly

[0055] 131 front plate

[0056] 132 back plate

[0057] 133 secondary air inlet

[0058] 134 primary blade

[0059] 135 secondary blade

[0060] 136 baffle

[0061] 137 recess

[0062] 137-B recess bottom plate

[0063] 137-S recess side plate

[0064] 138 through slot

[0065] 142 nut

[0066] 144 gasket

[0067] 152 seal strip

[0068] 154 seal groove

[0069] 156 seal pad

[0070] 200 centrifugal fan

[0071] 212 front cover

[0072] 214 housing

[0073] 216 primary air inlet

[0074] 222 motor

[0075] 224 output shaft

[0076] 230 impeller assembly

[0077] 231 front plate

[0078] 232 back plate

[0079] 233 secondary air inlet

[0080] 234 primary blade

[0081] 236 baffle

[0082] 237 recess

[0083] 237-B recess bottom plate

[0084] 237-S recess side plate

[0085] 238 through slot

[0086] 242 nut

[0087] 244 gasket

[0088] 252 seal bar

[0089] 254 seal groove

[0090] 256 seal pad

[0091] 300 centrifugal fan

[0092] 312 front cover

[0093] 314 housing

[0094] 316 main inlet

[0095] 318 outlet

[0096] 322 motor

[0097] 324 output shaft

[0098] 331 main impeller

[0099] 332 front side housing of main impeller

[0100] 333 rear side housing of main impeller

[0101] 336 secondary impeller

[0102] 337 front side housing of secondary impeller

[0103] 338 rear side housing of secondary impeller

[0104] 339 secondary inlet

[0105] 352 seal bar

[0106] 354 seal groove

[0107] 356 seal pad

[0108] A1 main airflow

[0109] A2 secondary airflow

[0110] H1 impeller height

[0111] H2 recess depth

[0112] H3 main impeller height

[0113] H4 secondary impeller height

[0114] D1 main inlet diameter

[0115] D2 groove diameter DETAILED DESCRIPTION

[0116] In order to make the purpose, scheme and advantages of the technical scheme of the utility model clearer, the technical scheme of the utility model embodiments will be described clearly and completely below in combination with the drawings of specific embodiments of the utility model. Unless otherwise specified, the terms used herein have the meanings commonly understood in the art. Identical reference numerals in the drawings represent identical components.

[0117] For a clearer description, unless otherwise explicitly stated, the orientation terms appearing in this text have the following meanings: the front side refers to the side close to the main air inlet, and the back side refers to the side opposite to the front side.

[0118] Figure 1 An external schematic view of a centrifugal fan 100 according to an embodiment of the utility model is shown, which mainly comprises a volute assembly 110, a motor assembly 120 and an impeller assembly 130 (as shown in Figure 2 and Figure 3 shown). The volute assembly 110 forms the outer shell of the centrifugal fan 100, and the impeller assembly 130 is accommodated inside the volute assembly 110. The motor assembly 120 provides power for the centrifugal fan 100, and the impeller assembly 130 rotates under the action of the motor assembly 120. The impeller assembly 130 inhales airflow from the outside and does work on the airflow to generate high-speed high-pressure airflow.

[0119] The volute assembly 110 mainly comprises a front cover 112 and a shell 114, the front cover 112 is arranged at the front side of the centrifugal fan 100, and the shell 114 is arranged at the back side of the centrifugal fan 100 relative to the front cover 112. The front cover 112 and the shell 114 are cooperatively installed to form an internal space for accommodating the impeller assembly 130. Specifically, a sealing groove 154 can be provided on the mating surface of the front cover 112 and the shell 114 on the side of the shell 114, a sealing strip 152 is placed in the sealing groove 154, and sealing glue can be applied in the sealing groove 154 for sealing connection between the front cover 112 and the shell 114.

[0120] The volute assembly 110 further comprises a main air inlet 116 and an air outlet 118, the main air inlet 116 is located at the front side of the front cover 112 (for example, the left side as Figure 1 shown), and the air outlet 118 is located at the radial outer periphery of the shell 114 (for example, the upper side as Figure 1 shown). Alternatively, the air outlet can also be jointly formed by the front cover and the shell. The impeller assembly 130 inhales airflow from the main air inlet 116, does work on the airflow, and then discharges high-pressure high-speed airflow from the air outlet 118 out of the centrifugal fan 100.

[0121] Motor assembly 120 includes a motor 122 and an output shaft 124. The motor 122 is arranged on the rear side of the centrifugal fan 100 (e.g., as shown in the image). Figure 1 (As shown on the right) and fixed to the housing 114, the output shaft 124 extends through the housing 114 into the volute assembly 110. The rotation output by the motor 122 is transmitted to the impeller assembly 130 via the output shaft 124, thereby driving the impeller assembly 130 to rotate. A sealing gasket 156 is arranged between the output shaft 124 and the housing 114 to seal the gap between the output shaft 124 and the housing 114.

[0122] The impeller assembly 130 mainly includes a front plate 131, a back plate 132, and main blades 134. The front plate 131 is arranged at the front relative to the back plate 132, and a space for accommodating the blades is formed between the front plate 131 and the back plate 132. The main blades 134 are fixed to the front plate 131 and the back plate 132. When the output shaft 124 of the motor assembly 120 drives the main blades 134 to rotate, the main blades 134 draw in airflow from the main air inlet 116. In this document, the airflow drawn in by the main blades 134 from the main air inlet 116 is referred to as the main airflow A1. While the main airflow A1 flows through the impeller assembly 130, a portion of the airflow enters the rear side of the impeller assembly 130 (i.e., the area between the back plate 132 and the housing 114). To prevent this airflow from damaging the motor assembly 120, a secondary air inlet 133 is provided on the back plate 132. Airflow leaking from the rear of the impeller assembly 130 can flow back into the impeller assembly 130 through the secondary air inlet 133, and then be discharged from the centrifugal fan 100 through the outlet 118 under the action of the blades. In other words, without the secondary air inlet 133, the leaking airflow behind the impeller assembly 130 is under positive pressure. With the secondary air inlet 133, the leaking airflow behind the impeller assembly 130 is under negative pressure, thus preventing the transported gas (e.g., flammable and explosive gases such as fuel gas) from leaking to the outside of the centrifugal fan 100 via the output shaft 124. Furthermore, it also prevents potential damage to the motor assembly 120 from corrosive gas leaks. In this document, the airflow drawn in from the secondary air inlet 133 is referred to as secondary airflow A2. The main air inlet 116 plays the main role in air intake, while the secondary air inlet 133 plays an auxiliary role in air intake. Therefore, the diameter D1 of the main air inlet 116 is larger than the diameter D2 of the secondary air inlet 133.

[0123] The back plate 132 of the impeller assembly 130 is formed with a recess 137 recessed towards the front side, the recess 137 having a recess bottom plate 137-B and a recess side plate 137-S. The recess bottom plate 137-B faces the back plate 132, and the recess side plate 137-S extends from the recess bottom plate 137-B to the back plate 132, and can extend to the back plate 132 in a direction perpendicular to the back plate 132. The recess bottom plate 137-B is arranged with the secondary blades 135, and the recess side plate 137-S is arranged with through openings 138 penetrating through the recess side plate 137-S to the inner side of the back plate 132. When the output shaft 124 of the motor assembly 120 drives the secondary blades 135 to rotate, the secondary blades 135 suck in the air flow from the secondary air inlet 133. Optionally, as shown in Figure 4 The depth H2 of the recess 137 can be between 1 / 4 and 1 / 2 of the total height H1 of the impeller assembly 130, and preferably, the depth H2 of the recess 137 can be 1 / 3 of the total height H1 of the impeller assembly 130. In addition, in order to ensure the exhaust function and structural strength of the secondary blades 135, the number of the through openings 138 and the secondary blades 135 should be set to 3 to 7, and preferably, 5.

[0124] In order to prevent the mutual interference between the primary air flow Al sucked in by the primary blades 134 from the primary air inlet 116 and the secondary air flow A2 sucked in by the secondary blades 135 from the secondary air inlet 133, a circular air baffle 136 is arranged on the recess bottom plate 137-B, and the air baffle 136 at least partially separates the primary air flow Al and the secondary air flow A2. The air baffle 136, the recess bottom plate 137-B and the back plate 132 are respectively arranged with shaft holes aligned with each other, and the shaft holes are aligned with the output shaft 124. When the centrifugal fan 100 is assembled, the output shaft 124 sequentially passes through the back plate 132, the recess bottom plate 137-B and the air baffle 136 from the rear side to the front side, and the air baffle 136 is flatly attached to the recess bottom plate 137-B, and the air baffle 136 is installed to the output shaft 124 through the nut 142 and the washer 144, and the air baffle 136 extends outwardly to the primary blades 134 in the radial direction. By arranging the air baffle 136, the mutual interference between the primary air flow Al and the secondary air flow A2 is avoided, thereby improving the performance of the centrifugal fan 100.

[0125] Optionally, the primary blades 134 can adopt a backward leaning blade structure, the primary blades 134 extend to the outer periphery in the radial direction of the impeller assembly 130, and one side of the primary blades 134 extends to the primary air inlet 116 at the front plate 131 side, and the other side of the primary blades 134 extends to the recess side plate 137-S at the back plate 132 side.

[0126] Optionally, the impeller assembly 130 can be manufactured by sheet metal, casting, welding, etc. Preferably, the impeller assembly 130 is manufactured by sheet metal, the grooves 137 are formed by pressing grooves on the back plate 132, and the secondary blades 135 are flipped out from the groove bottom plate 137-B through the material at the through slot opening 138. The height of the secondary blades 135 increases linearly from the minimum diameter to the maximum diameter, and the highest part does not exceed the inner side of the back plate 132. Preferably, the secondary blades 135 can be straight blades. Alternatively, the shape of the through slot opening 138 can be adjusted to flip out the secondary blades 135 in a forward, backward or radial direction.

[0127] Figure 5 A cross-sectional view of a centrifugal fan 200 according to a second embodiment of the present application is shown, which mainly comprises a volute assembly, a motor assembly and an impeller assembly 230 (as shown in Figure 6 and Figure 7 ). The volute assembly forms the outer shell of the centrifugal fan 200, and the impeller assembly 230 is contained inside the volute assembly. The motor assembly provides power for the centrifugal fan 200, and the impeller assembly 230 rotates under the action of the motor assembly. The impeller assembly 230 inhales airflow from the outside and does work on the airflow to generate high-speed high-pressure airflow.

[0128] The volute assembly mainly comprises a front cover 212 and a shell 214, the front cover 212 is arranged at the front side of the centrifugal fan 200, and the shell 214 is arranged at the rear side of the centrifugal fan 200 relative to the front cover 212. The front cover 212 and the shell 214 are cooperatively installed to form an internal space containing the impeller assembly 230. Specifically, a sealing groove 254 can be provided on the mating surface of the front cover 212 and the shell 214 on the side of the shell 214, a sealing strip 252 is placed in the sealing groove 254, and sealing glue can be applied in the sealing groove 254 for sealing connection between the front cover 212 and the shell 214.

[0129] The volute assembly further comprises a main air inlet 216 and an air outlet 218, the main air inlet 216 is located at the front side of the front cover 212, and the air outlet 218 is located at the radial outer periphery of the shell 214. The impeller assembly 230 inhales airflow from the main air inlet 216, and high-pressure high-speed airflow is discharged from the air outlet after the impeller assembly 230 does work on the airflow.

[0130] The motor assembly comprises a motor 222 and an output shaft 224, the motor 222 is arranged at the rear side of the centrifugal fan 200 and fixed to the shell 214, and the output shaft 224 extends through the shell 214 to the inside of the volute assembly. The rotation output by the motor 222 is transmitted to the impeller assembly 230 via the output shaft 224, thereby driving the impeller assembly 230 to rotate. A sealing pad 256 is arranged between the output shaft 224 and the shell 214 to seal the gap between the output shaft 224 and the shell 214.

[0131] The impeller assembly 230 mainly comprises a front plate 231, a back plate 232 and main blades 234, the front plate 231 is arranged at the front side relative to the back plate 232, a space accommodating the main blades 234 is formed between the front plate 231 and the back plate 232, the main blades 234 are fixed to the front plate 231 and the back plate 232, and the main blades 234 inhale the air flow from the main air inlet 216 when the output shaft 124 of the motor assembly drives the main blades 234 to rotate. While the main air flow A1 flows through the impeller assembly 230, a part of the air flow will enter the rear side of the impeller assembly 230 (i.e. the area between the back plate 232 and the shell 214). In order to prevent this part of the air flow from damaging the motor assembly, the back plate 232 is provided with a secondary air inlet 233, and the air flow leaked at the rear side of the impeller assembly 230 can re-enter the impeller assembly 230 from the secondary air inlet 233, and then be discharged from the air outlet under the action of the blades.

[0132] The back plate 232 of the impeller assembly 230 is formed with a recess 237 recessed towards the front side, the recess 237 has a recess bottom plate 237-B and a recess side plate 237-S. The recess bottom plate 237-B faces the back plate 232, and the recess side plate 237-S extends from the recess bottom plate 237-B to the back plate 232. The recess side plate 237-S is provided with a through slot 238, and the through slot 238 penetrates the inner side of the back plate 232 on the recess side plate 237-S.

[0133] Unlike the centrifugal fan 100 of the first embodiment, in the centrifugal fan 200 of the second embodiment, the recess side plate 237-S extends to the back plate 232 in a direction inclined to the back plate 232. Specifically, in the direction towards the back plate 232, the recess side plate 237-S extends in a radially outward direction. In this way, when the recess side plate 237-S rotates with the impeller assembly 230, the inclined recess side plate 237-S facilitates the formation of an air inlet at the opening of the recess side plate 237-S, and the recessed shape facilitates the gathering of the air flow from the rear side of the back plate 232, so that the centrifugal fan 200 can no longer be additionally provided with a secondary blade, the structure of the centrifugal fan 200 is simpler, and the cost is reduced.

[0134] To prevent mutual interference between the main air flow A1 sucked by the main blade 234 from the main air inlet 216 and the secondary air flow A2 sucked by the groove side plate 237-S from the secondary air inlet 233, a circular air baffle plate 236 is arranged on the groove bottom plate 237-B, which at least partially separates the main air flow A1 and the secondary air flow A2. When the centrifugal fan 200 is assembled, the output shaft 224 passes through the back plate 232, the groove bottom plate 237-B and the air baffle plate 236 from back to front in sequence, and the air baffle plate 236 is flatly attached to the groove bottom plate 237-B. The air baffle plate 236 is installed to the output shaft 224 through the nut 242 and the gasket 244, and extends outward in the radial direction to the main blade 234. By arranging the air baffle plate 236, mutual interference between the main air flow A1 and the secondary air flow A2 is avoided, thereby improving the performance of the centrifugal fan 200.

[0135] Figure 8 A cross-sectional view of a centrifugal fan 300 according to a third embodiment of the present application is shown, which mainly comprises a volute assembly, a motor assembly and an impeller assembly. The volute assembly forms the shell of the centrifugal fan 300, and the impeller assembly is contained inside the volute assembly. The motor assembly provides power for the centrifugal fan 300, and the impeller assembly rotates under the action of the motor assembly. The impeller assembly sucks air flow from outside and does work on the air flow to generate high-speed and high-pressure air flow.

[0136] The volute assembly mainly comprises a front cover 312 and a shell 314, the front cover 312 is arranged at the front side of the centrifugal fan 300, and the shell 314 is arranged at the back side of the centrifugal fan 300 relative to the front cover 312. The front cover 312 and the shell 314 are cooperatively installed to form an internal space containing the impeller assembly. Specifically, a sealing groove 354 can be provided on the mating surface of the front cover 312 and the shell 314 on the side of the shell 314, a sealing strip 352 is placed in the sealing groove 354, and sealing glue can be applied in the sealing groove 354 for sealing connection between the front cover 312 and the shell 314.

[0137] The volute assembly further comprises a main air inlet 316 and an air outlet, the main air inlet 316 is located at the front side of the front cover 312, and the air outlet is located at the radial outer periphery of the shell 314. The impeller assembly sucks air flow from the main air inlet 316, and high-pressure and high-speed air flow is discharged from the air outlet out of the centrifugal fan 300 after doing work on the air flow.

[0138] The motor assembly comprises a motor 322 and an output shaft 324, the motor 322 is arranged at the back side of the centrifugal fan 300 and fixed to the shell 314, and the output shaft 324 extends to the inside of the volute assembly through the shell 314. The rotation output by the motor 322 is transmitted to the impeller assembly via the output shaft 324, thereby driving the impeller assembly to rotate. A sealing pad 356 is arranged between the output shaft 324 and the shell 314 to seal the gap between the output shaft 324 and the shell 314.

[0139] The impeller assembly includes a primary impeller 331 and a secondary impeller 336, which are placed back to back together and fixed to the output shaft 324, the primary impeller 331 inhales the primary airflow A1 from the primary air inlet 316 and discharges the primary airflow A1 from the air outlet centrifugal fan 300, and the secondary impeller 336 inhales the secondary airflow A2 from the secondary air inlet 339 and discharges the secondary airflow A2 from the air outlet centrifugal fan 300. Wherein, the secondary air inlet 339 is located at the rear side of the impeller assembly (i.e. the side close to the motor 322). The primary impeller 331 has a front side shell 332 of the primary impeller and a rear side shell 333 of the primary impeller, which form the boundary of the primary impeller 331, and the secondary impeller 336 has a front side shell 337 of the secondary impeller and a rear side shell 338 of the secondary impeller, which form the boundary of the secondary impeller 336, and the rear side shell 333 of the primary impeller can be attached together with the front side shell 337 of the secondary impeller. The flow channel of the primary impeller 331 and the flow channel of the secondary impeller 336 are both closed impellers, and the flow channels of the primary impeller 331 and the secondary impeller 336 are isolated from each other, preventing the mutual interference between the primary airflow A1 generated by the primary impeller 331 and the secondary airflow A2 generated by the secondary impeller 336. Optionally, the height H4 of the secondary impeller 336 can be 1 / 3 of the height of the primary impeller 331.

[0140] The various exemplary embodiments of the utility model are described in detail herein with reference to preferred embodiments, however, those skilled in the art can understand that various modifications and modifications can be made to the above specific embodiments without departing from the concept of the utility model, and various technical features and structures proposed by the utility model can be combined without exceeding the protection scope of the utility model, and the protection scope of the utility model is determined by the appended claims.

Claims

1. A centrifugal fan characterized by comprising: Comprising: a volute assembly including a front cover and a housing, the front cover having a main air inlet and being arranged at a front side of the centrifugal fan, the volute assembly having an air outlet; a motor assembly including a motor and an output shaft, the motor being fixed to the housing and being arranged at a rear side of the centrifugal fan, the output shaft extending into the volute assembly; an impeller assembly including a front plate, a back plate and main vanes, the front plate being arranged at a front side relative to the back plate, the back plate having a secondary air inlet, the main vanes being located between the front plate and the back plate, the main vanes being configured to suck in air from the main air inlet, the impeller assembly being configured to rotate under the action of the output shaft; wherein the impeller assembly includes a main flow channel and a secondary flow channel, the main flow channel being in communication with the main air inlet and the air outlet, the secondary flow channel being in communication with the secondary air inlet and the air outlet, the main flow channel being at least partially spaced apart from the secondary flow channel, and wherein the impeller assembly further includes: a main impeller including the main vanes and being configured to suck in air from the main air inlet to form the main flow channel, the front plate forming a front side housing of the main impeller; a secondary impeller being arranged at a rear side of the main impeller and being configured to suck in air from the secondary air inlet to form the secondary flow channel, the back plate forming a rear side housing of the secondary impeller.

2. The centrifugal fan of claim 1, wherein The main impeller and the secondary impeller are closed impellers, such that the main flow channel and the secondary flow channel are spaced apart.

3. The centrifugal fan of claim 2, wherein The rear side housing of the main impeller and the front side housing of the secondary impeller are fitted together.

4. The centrifugal fan of claim 3, wherein The height of the secondary impeller in the axial direction is between 1 / 4 and 1 / 2 of the height of the main impeller in the axial direction.

5. The centrifugal fan of claim 4, wherein The height of the secondary impeller in the axial direction is 1 / 3 of the height of the main impeller in the axial direction.

6. The centrifugal fan of claim 1, wherein The impeller assembly further includes a wind separation plate arranged between the main flow channel and the secondary flow channel to at least partially space apart the main flow channel and the secondary flow channel.

7. The centrifugal fan of claim 6, wherein The wind separation plate has a disc shape and extends outward from a center axis in a radial direction to the main vanes, the main flow channel being located at a front side of the wind separation plate, the secondary flow channel being located at a rear side of the wind separation plate.

8. The centrifugal fan of claim 7, wherein The back plate has a groove formed thereon, the groove being recessed towards the front side, the groove having a groove bottom plate facing the back plate and a groove side plate extending from the groove bottom plate to the back plate, a plurality of through slots being formed in the groove side plate, the through slots forming the secondary flow channel.

9. The centrifugal fan of claim 8, wherein The groove bottom plate is provided with secondary vanes configured to suck in air from the secondary air inlet.

10. The centrifugal fan of claim 8, wherein The groove side plate extends from the groove bottom plate to the back plate in a direction radially outward.

11. The centrifugal fan of claim 10, wherein The groove side plate is configured to suck in air from the secondary air inlet.

12. The centrifugal fan of claim 1, wherein Further comprising a sealing gasket arranged between the output shaft and the housing.

13. The centrifugal fan of claim 1, wherein Further comprising a sealing groove arranged on an outer peripheral surface of the housing facing the front cover, a sealing strip being placed in the sealing groove for sealing between the housing and the front cover.

14. The centrifugal fan of claim 13, wherein The sealing groove is coated with a sealing glue.

15. The centrifugal fan of claim 1, wherein The air outlet is located at a radial periphery of the housing.

16. The centrifugal fan of claim 1, wherein The impeller assembly is manufactured by any one of sheet metal, casting or welding.

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