Centrifugal fan

Abstract

A centrifugal fan (100), comprising: a volute assembly (110) comprising a front cover (112) and a housing (114), wherein the front cover (112) is provided with a main air inlet (116) and is arranged on the front side of the centrifugal fan (100), and the housing (114) is provided with an air outlet (118); an electric motor assembly (120) comprising an electric motor (122) and an output shaft (124), wherein the electric motor (122) is fixed to the housing (114) and is arranged on the rear side of the centrifugal fan (100), and the output shaft (124) extends into the volute assembly (110); and an impeller assembly (130) comprising a front plate (131), a back plate (132) and main blades (134), wherein the front plate (131) is arranged on a front side relative to the back plate (132), the back plate (132) is provided with an auxiliary air inlet (133), the main blades (134) are located between the front plate (131) and the back plate (132), and the main blades (134) are configured to draw air from the main air inlet (116). The impeller assembly (130) is configured to rotate under the action of the output shaft (124), and the impeller assembly (130) comprises a main flow channel and an auxiliary flow channel, wherein the main flow channel brings the main air inlet (116) into communication with the air outlet (118), the auxiliary flow channel brings the auxiliary air inlet (133) into communication with the air outlet (118), and the main flow channel and the auxiliary flow channel are at least partially spaced apart from each other. The centrifugal fan can reduce the mutual interference between a main airflow and an auxiliary airflow, thereby improving the performance of the centrifugal fan.

Description

A centrifugal fan

[0001] This application claims priority to Chinese Patent Application No. 202510460096.8, filed on April 14, 2025, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] This invention relates to a centrifugal fan, and more specifically, to a leak-proof centrifugal fan. Background Technology

[0003] Centrifugal fans draw in airflow through an impeller and perform work on it to generate high-pressure airflow. Because the motor's output shaft drives the impeller to rotate, there is typically a gap between the motor's output shaft and the housing. Although seals can be installed between the output shaft and the housing, after long-term operation, the seals may age and wear, leading to a decrease in sealing effectiveness and causing some airflow leakage. The gas at the rear of the centrifugal fan is connected to the gas that has undergone work by the impeller at the outer circumference, resulting in a positive pressure state at the rear of the centrifugal fan. This positive pressure state can easily cause gas to leak out of the centrifugal fan through the motor's output shaft, creating a certain safety hazard.

[0004] In existing technology, to address the technical problem caused by airflow leakage, auxiliary blades are installed on the rear side of the impeller. These auxiliary blades draw in the leaked airflow from the rear of the centrifugal fan, creating a negative pressure environment and thus improving the airflow leakage. However, the airflow generated by the main blades and auxiliary blades interferes with each other. On one hand, the main airflow generated by the main blades weakens the negative pressure effect at the rear of the impeller; on the other hand, the auxiliary airflow generated by the auxiliary blades weakens the high-pressure airflow generated by the main blades, thereby adversely affecting the performance of the centrifugal fan.

[0005] Therefore, it is hoped that a centrifugal fan can be proposed to improve the shortcomings of the above-mentioned existing technology. Summary of the Invention

[0006] According to one aspect of the present invention, a centrifugal fan is provided, comprising: a volute assembly including a front cover and a housing, the front cover having a main air inlet and disposed on the 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 disposed on the rear side of the centrifugal fan, the output shaft extending into the volute assembly; and an impeller assembly including a front plate, a back plate, and main blades, the front plate being disposed on the front side relative to the back plate, the back plate having a secondary air inlet, the main blades being located between the front plate and the back plate, the main blades being configured to draw in gas from the main air inlet, and 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 connecting the main air inlet and the air outlet, the secondary flow channel connecting the secondary air inlet and the air outlet, and the main flow channel and the secondary flow channel being at least partially spaced apart.

[0007] According to this scheme, by separating the main flow path and the secondary flow path at least partially, the mutual interference between the main airflow generated by the main blades and the secondary airflow generated by the secondary blades is avoided, thereby improving the performance of the centrifugal fan.

[0008] In some designs, the impeller assembly may also 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.

[0009] According to this scheme, the baffle can separate the main airflow generated by the main blade from the secondary airflow generated by the secondary blade, thereby avoiding the main airflow and secondary airflow from colliding and interfering with each other.

[0010] In some designs, the baffle plate can be disc-shaped and extend radially outward from the central axis to the main blades, with the main flow channel located on the front side of the baffle plate and the secondary flow channel located on the rear side of the baffle plate.

[0011] In some designs, a recessed groove can be formed on the back plate, the groove having a bottom plate and a side plate, the bottom plate facing the back plate, the side plate extending from the bottom plate to the back plate, and multiple through slots forming secondary flow channels.

[0012] According to this scheme, the concave structure can be manufactured through a process without increasing the amount of material. The concave structure forms a secondary flow channel, which reduces the cost of the centrifugal fan.

[0013] In some designs, the recessed sideplates can extend in a direction perpendicular to the backplate.

[0014] In some designs, a secondary blade may be provided on the recessed bottom plate, and the secondary blade is configured to draw in gas from the secondary air inlet.

[0015] In some designs, the secondary blades can extend from the grooved bottom plate to the inside of the back plate.

[0016] According to this design, the height of the secondary blades does not exceed the back plate, which is beneficial for the miniaturization of the centrifugal fan.

[0017] In some designs, the secondary blades can be flipped out of the groove bottom plate through the material at the through slot opening.

[0018] In some designs, the grooved sideplate can extend from the grooved bottom plate to the back plate in a radially outward direction.

[0019] According to the design, the inclined grooved side plate facilitates the formation of an air inlet at the opening of the grooved side plate, and the concave shape facilitates the collection of airflow from the rear side of the back plate, thus eliminating the need for additional auxiliary blades, making the centrifugal fan structure simpler and reducing costs.

[0020] In some designs, the recessed side plate can be configured to draw in gas from the secondary air inlet.

[0021] In some designs, the through slot can extend from the grooved side plate to the inside of the back plate.

[0022] In some designs, the baffle plate can be fitted with the recessed bottom plate.

[0023] In some designs, the baffle plate, the recessed bottom plate, and the back plate may each have mutually aligned shaft holes, which are aligned with the output shaft.

[0024] In some designs, the baffle plate can be fixed to the output shaft with nuts.

[0025] In some embodiments, the impeller assembly may include: a main impeller configured to draw in gas from a main air inlet, with a front plate forming the front housing of the main impeller and a main flow channel located in the main impeller; and an auxiliary impeller arranged behind the main impeller and configured to draw in gas from an auxiliary air inlet, with an auxiliary flow channel located in the auxiliary impeller and a back plate forming the rear housing of the auxiliary impeller.

[0026] According to this scheme, the flow channels of the main impeller and the secondary impeller are isolated from each other, preventing mutual interference between the airflow generated by the main impeller and the airflow generated by the secondary impeller.

[0027] In some designs, the rear casing of the main impeller can be fitted together with the front casing of the auxiliary impeller.

[0028] In some designs, the main impeller and the auxiliary impeller can be closed impellers.

[0029] In some designs, the height of the secondary impeller along the axial direction can be between 1 / 4 and 1 / 2 of the height of the main impeller along the axial direction.

[0030] In some designs, the height of the secondary impeller along the axial direction can be one-third of the height of the main impeller along the axial direction.

[0031] In some designs, the centrifugal fan may also include a gasket positioned between the output shaft and the housing.

[0032] In some designs, the centrifugal fan may also include a sealing groove arranged on the outer peripheral surface of the housing facing the front cover, with a sealing strip placed inside the sealing groove for sealing between the housing and the front cover.

[0033] According to the solution, a sealing strip is placed in the groove to prevent gas from leaking through the contact surface, and it can also be used to assist in filling with sealant for sealing. The sealing strip and sealant can meet the requirements for long-term sealing. Attached Figure Description

[0034] Figure 1 shows an external schematic diagram of a centrifugal fan according to an embodiment of the present invention;

[0035] Figure 2 shows a cross-sectional view of a centrifugal fan according to a first embodiment of the present invention;

[0036] Figure 3 shows a schematic diagram of an impeller assembly according to a first embodiment of the present invention;

[0037] Figure 4 shows a cross-sectional view of the impeller assembly according to a first embodiment of the present invention;

[0038] Figure 5 shows a cross-sectional view of a centrifugal fan according to a second embodiment of the present invention;

[0039] Figure 6 shows a schematic diagram of an impeller assembly according to a second embodiment of the present invention;

[0040] Figure 7 shows a cross-sectional view of an impeller assembly according to a second embodiment of the present invention;

[0041] Figure 8 shows a cross-sectional view of a centrifugal fan according to a third embodiment of the present invention.

[0042] Reference numerals: 100 Centrifugal fan; 110 Volute assembly; 112 Front cover; 114 Housing; 116 Main air inlet; 118 Air outlet; 120 Motor assembly; 122 Motor; 124 Output shaft; 130 Impeller assembly; 131 Front plate; 132 Back plate; 133 Secondary air inlet; 134 Main blade; 135 Secondary blade; 136 Air baffle; 137 Groove; 137-B Groove bottom plate; 137-S Groove side plate; 138 Through slot; 142 Nut; 144 Washer; 152 Sealing strip; 154 Sealing groove; 156 Sealing gasket; 200 Centrifugal fan; 212 Front cover; 214 Housing; 216 Main air inlet; 222 Motor; 224 Output shaft; 230 Impeller assembly; 231 Front plate; 232 Back plate; 233 Secondary air inlet; 234 Main blade; 236 237 Air baffle plate; 237-B groove; 237-S groove bottom plate; 238 groove side plate; 242 through slot; 244 nut; 252 gasket; 254 sealing strip; 256 sealing groove; 300 sealing gasket; 312 centrifugal fan; 314 front cover; 316 housing; 318 main air inlet; 322 air outlet; 324 motor; 331 output shaft; 332 main impeller; 333 front housing of main impeller; 336 rear housing of main impeller; 337 auxiliary impeller; 338 front housing of auxiliary impeller; 339 rear housing of auxiliary impeller; 352 auxiliary air inlet; 354 ​​sealing strip; 356 sealing groove; A1 sealing gasket; A2 main airflow; H1 auxiliary airflow; H2 impeller height; H3 groove depth; H4 main impeller height; D1 auxiliary impeller height; D2 main air inlet diameter; D1 groove diameter. Detailed Implementation

[0043] To make the objectives, solutions, and advantages of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Unless otherwise stated, the terms used herein have their ordinary meanings in the art. The same reference numerals in the drawings represent the same parts.

[0044] For clarity, unless otherwise explicitly stated, the directional terms used in this document are defined as follows: front side refers to the side closer to the main air intake, and rear side refers to the side opposite to the front side.

[0045] Figure 1 shows an external schematic diagram of a centrifugal fan 100 according to an embodiment of the present invention. The centrifugal fan 100 mainly includes a volute assembly 110, a motor assembly 120, and an impeller assembly 130 (as shown in Figures 2 and 3). The volute assembly 110 forms the outer casing of the centrifugal fan 100, and the impeller assembly 130 is housed inside the volute assembly 110. The motor assembly 120 provides power to the centrifugal fan 100, and the impeller assembly 130 rotates under the action of the motor assembly 120. The impeller assembly 130 draws in airflow from the outside and performs work on the airflow to generate a high-speed, high-pressure airflow.

[0046] The volute assembly 110 mainly includes a front cover 112 and a housing 114. The front cover 112 is located on the front side of the centrifugal fan 100, and the housing 114 is located on the rear side of the centrifugal fan 100 relative to the front cover 112. The front cover 112 and the housing 114 are fitted together to form an internal space for accommodating the impeller assembly 130. Specifically, a sealing groove 154 may be provided on the mating surfaces of the front cover 112 and the housing 114 on the side of the housing 114. A sealing strip 152 is placed in the sealing groove 154, and sealant can be applied to the sealing groove 154 for a sealed connection between the front cover 112 and the housing 114.

[0047] The volute assembly 110 also includes a main air inlet 116 and an air outlet 118. The main air inlet 116 is located on the front side of the front cover 112 (e.g., on the left side as shown in Figure 1), and the air outlet 118 is located on the side of the housing 114 (e.g., on the upper side as shown in Figure 1). Alternatively, the air outlet can also be formed by the front cover and the housing together. The impeller assembly 130 draws in airflow from the main air inlet 116, performs work on the airflow, and then discharges the high-pressure, high-speed airflow from the centrifugal fan 100 through the air outlet 118.

[0048] The motor assembly 120 includes a motor 122 and an output shaft 124. The motor 122 is located on the rear side of the centrifugal fan 100 (e.g., the right side as shown in FIG. 1) and is fixed to the housing 114. The output shaft 124 extends through the housing 114 into the volute assembly 110. The rotation output from 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.

[0049] 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.

[0050] The impeller assembly 130 has a recessed groove 137 formed on its back plate 132, which has a bottom plate 137-B and a side plate 137-S. The bottom plate 137-B faces the back plate 132, and the side plate 137-S extends from the bottom plate 137-B to the back plate 132, extending in a direction perpendicular to the back plate 132. A secondary blade 135 is arranged on the bottom plate 137-B, and a through slot 138 is formed on the side plate 137-S, extending through the 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 blade 135 to rotate, the secondary blade 135 draws in airflow from the secondary air inlet 133. Optionally, as shown in Figure 4, the depth H2 of the groove 137 can be between 1 / 4 and 1 / 2 of the total height H1 of the impeller assembly 130. Preferably, the depth H2 of the groove 137 can be 1 / 3 of the total height H1 of the impeller assembly 130. Furthermore, to ensure the exhaust function and structural strength of the auxiliary blades 135, the number of through slots 138 and auxiliary blades 135 should be set to 3 to 7, preferably 5.

[0051] To prevent interference between the main airflow A1 drawn in by the main blade 134 from the main air inlet 116 and the secondary airflow A2 drawn in by the secondary blade 135 from the secondary air inlet 133, a circular baffle plate 136 is provided on the recessed bottom plate 137-B. The baffle plate 136 at least partially separates the main airflow A1 and the secondary airflow A2. Aligned shaft holes are provided on the baffle plate 136, the recessed bottom plate 137-B, and the back plate 132, respectively, and these shaft holes are aligned with the output shaft 124. During the assembly of the centrifugal fan 100, the output shaft 124 passes sequentially from the rear to the front through the back plate 132, the recessed bottom plate 137-B, and the baffle plate 136, with the plane of the baffle plate 136 fitting against the recessed bottom plate 137-B. The baffle plate 136 is installed onto the output shaft 124 using nuts 142 and washers 144, and extends radially outward to the main blade 134. By setting up the baffle plate 136, the mutual interference between the main airflow A1 and the secondary airflow A2 is avoided, thereby improving the performance of the centrifugal fan 100.

[0052] Optionally, the main blade 134 may adopt a backward-curved blade structure. The main blade 134 extends to the outer periphery in the radial direction of the impeller assembly 130. One side of the inner side of the main blade 134 extends to the main air inlet 116 on the front plate 131 side, and the other side extends to the grooved side plate 137-S on the back plate 132 side.

[0053] Optionally, the impeller assembly 130 can be manufactured by sheet metal, casting, welding, or other methods. Preferably, the impeller assembly 130 is manufactured by sheet metal, with the groove 137 formed by pressing a recess into the back plate 132, and the secondary blade 135 protruding from the groove bottom plate 137-B through the material at the through slot 138. The height of the secondary blade 135 increases linearly from the minimum diameter to the maximum diameter, with the highest point not exceeding the inner side of the back plate 132. Preferably, the secondary blade 135 can be a straight blade. Alternatively, the shape of the through slot 138 can be adjusted to protrude forward-tilted, backward-tilted, or radially inclined secondary blades 135.

[0054] Figure 5 shows a cross-sectional view of a centrifugal fan 200 according to a second embodiment of the present invention. The centrifugal fan 200 mainly includes a volute assembly, a motor assembly, and an impeller assembly 230 (as shown in Figures 6 and 7). The volute assembly forms the outer casing of the centrifugal fan 200, and the impeller assembly 230 is housed inside the volute assembly. The motor assembly provides power to the centrifugal fan 200, and the impeller assembly 230 rotates under the action of the motor assembly. The impeller assembly 230 draws in airflow from the outside and performs work on the airflow to generate a high-speed, high-pressure airflow.

[0055] The volute assembly mainly includes a front cover 212 and a housing 214. The front cover 212 is located on the front side of the centrifugal fan 200, and the housing 214 is located on the rear side of the centrifugal fan 200 relative to the front cover 212. The front cover 212 and the housing 214 are fitted together to form an internal space for accommodating the impeller assembly 230. Specifically, a sealing groove 254 can be provided on the mating surfaces of the front cover 212 and the housing 214 on the side of the housing 214. A sealing strip 252 is placed in the sealing groove 254, and sealant can be applied to the sealing groove 254 for a sealed connection between the front cover 212 and the housing 214.

[0056] The volute assembly also includes a main air inlet 216 and an air outlet. The main air inlet 216 is located on the front side of the front cover 212, and the air outlet 218 is located on the side of the housing 214. The impeller assembly 230 draws in airflow through the main air inlet 216, performs work on the airflow, and then discharges the high-pressure, high-speed airflow from the air outlet to the centrifugal fan 200.

[0057] The motor assembly includes a motor 222 and an output shaft 224. The motor 222 is located behind the centrifugal fan 200 and is fixed to the housing 214. The output shaft 224 extends through the housing 214 into the volute assembly. The rotation output from 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 gasket 256 is arranged between the output shaft 224 and the housing 214 to seal the gap between the output shaft 224 and the housing 214.

[0058] The impeller assembly 230 mainly includes a front plate 231, a back plate 232, and main blades 234. The front plate 231 is arranged at the front relative to the back plate 232, and a space is formed between the front plate 231 and the back plate 232 to accommodate the main blades 234. The main blades 234 are fixed to the front plate 231 and the back plate 232. When the output shaft 124 of the motor assembly drives the main blades 234 to rotate, the main blades 234 draw in airflow from the main air inlet 216. While the main airflow A1 flows through the impeller assembly 230, a portion of the airflow enters the rear side of the impeller assembly 230 (i.e., the area between the back plate 232 and the housing 214). To prevent this portion of the airflow from damaging the motor assembly, the back plate 232 is provided with a secondary air inlet 233. The airflow leaking from the rear side of the impeller assembly 230 can flow back into the impeller assembly 230 from the secondary air inlet 233, and then be discharged from the centrifugal fan 200 from the outlet under the action of the blades.

[0059] The impeller assembly 230 has a recessed groove 237 formed on its back plate 232, which is recessed to the front. The groove 237 has a groove bottom plate 237-B and a groove side plate 237-S. The groove bottom plate 237-B faces the back plate 232, and the groove side plate 237-S extends from the groove bottom plate 237-B to the back plate 232. A through slot 238 is formed on the groove side plate 237-S, which extends through the groove side plate 237-S to the inside of the back plate 232.

[0060] Unlike the centrifugal fan 100 of the first embodiment, in the centrifugal fan 200 of the second embodiment, the recessed side plate 237-S extends to the back plate 232 in a direction inclined to the back plate 232. Specifically, in the direction toward the back plate 232, the recessed side plate 237-S extends radially outward. Thus, when the recessed side plate 237-S rotates with the impeller assembly 230, the inclined recessed side plate 237-S facilitates the formation of an air inlet at the opening of the recessed side plate 237-S, and the concave shape facilitates the collection of airflow from the rear side of the back plate 232, thereby eliminating the need for additional auxiliary blades, simplifying the structure of the centrifugal fan 200 and reducing costs.

[0061] To prevent interference between the main airflow A1 drawn into the main air inlet 216 by the main blades 234 and the secondary airflow A2 drawn into the secondary air inlet 233 by the recessed side plate 237-S, a circular baffle plate 236 is provided on the recessed bottom plate 237-B. The baffle plate 236 at least partially separates the main airflow A1 from the secondary airflow A2. During the assembly of the centrifugal fan 200, the output shaft 224 passes sequentially from the rear to the front through the back plate 232, the recessed bottom plate 237-B, and the baffle plate 236. The plane of the baffle plate 236 is flush with the recessed bottom plate 237-B. The baffle plate 236 is installed onto the output shaft 224 using nuts 242 and washers 244. The baffle plate 236 extends radially outward to the main blades 234. By providing the baffle plate 236, interference between the main airflow A1 and the secondary airflow A2 is avoided, thereby improving the performance of the centrifugal fan 200.

[0062] Figure 8 shows a cross-sectional view of a centrifugal fan 300 according to a third embodiment of the present invention. The centrifugal fan 300 mainly includes a volute assembly, a motor assembly, and an impeller assembly. The volute assembly forms the outer casing of the centrifugal fan 300, and the impeller assembly is housed inside the volute assembly. The motor assembly provides power to the centrifugal fan 300, and the impeller assembly rotates under the action of the motor assembly. The impeller assembly draws in airflow from the outside and performs work on the airflow to generate a high-speed, high-pressure airflow.

[0063] The volute assembly mainly includes a front cover 312 and a housing 314. The front cover 312 is located on the front side of the centrifugal fan 300, and the housing 314 is located on the rear side of the centrifugal fan 300 relative to the front cover 312. The front cover 312 and the housing 314 are fitted together to form an internal space for accommodating the impeller assembly. Specifically, a sealing groove 354 may be provided on the mating surfaces of the front cover 312 and the housing 314 on the side of the housing 314. A sealing strip 352 is placed in the sealing groove 354, and sealant can be applied to the sealing groove 354 for a sealing connection between the front cover 312 and the housing 314.

[0064] The volute assembly also includes a main air inlet 316 and an air outlet. The main air inlet 316 is located on the front side of the front cover 312, and the air outlet is located on the side of the housing 314. The impeller assembly draws in airflow through the main air inlet 316, performs work on the airflow, and then discharges the high-pressure, high-speed airflow from the air outlet of the centrifugal fan 300.

[0065] The motor assembly includes a motor 322 and an output shaft 324. The motor 322 is located at the rear of the centrifugal fan 300 and is fixed to the housing 314. The output shaft 324 extends through the housing 314 into the volute assembly. 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 gasket 356 is arranged between the output shaft 324 and the housing 314 to seal the gap between the output shaft 324 and the housing 314.

[0066] The impeller assembly includes a main impeller 331 and an auxiliary impeller 336, which are placed back-to-back and fixed to the output shaft 324. The main impeller 331 draws in the main airflow A1 through the main air inlet 316 and discharges the main airflow A1 from the air outlet of the centrifugal fan 300. The auxiliary impeller 336 draws in the auxiliary airflow A2 through the auxiliary air inlet 339 and discharges the auxiliary airflow A2 from the air outlet of the centrifugal fan 300. The auxiliary air inlet 339 is located on the rear side of the impeller assembly (i.e., the side closer to the motor 322). The main impeller 331 has a front casing 332 and a rear casing 333, which form the boundary of the main impeller 331. The auxiliary impeller 336 has a front casing 337 and a rear casing 338, which form the boundary of the auxiliary impeller 336. The rear casing 333 of the main impeller can be fitted together with the front casing 337 of the auxiliary impeller. Both the flow channels of the main impeller 331 and the auxiliary impeller 336 are closed impellers, and their flow channels are isolated from each other, preventing mutual interference between the main airflow A1 generated by the main impeller 331 and the auxiliary airflow A2 generated by the auxiliary impeller 336. Optionally, the height H4 of the auxiliary impeller 336 can be 1 / 3 of the height of the main impeller 331.

[0067] This document describes in detail several exemplary embodiments of the present invention with reference to preferred embodiments. However, those skilled in the art will understand that various modifications and alterations can be made to the above specific embodiments without departing from the concept of the present invention, and various technical features and structures proposed in the present invention can be combined without exceeding the protection scope of the present invention, which is determined by the appended claims.

Claims

1. A centrifugal fan, comprising: The volute assembly includes a front cover and a housing, the front cover having a main air inlet and being disposed on the front side of the centrifugal fan, and the volute assembly having an air outlet; A motor assembly, including a motor and an output shaft, wherein the motor is fixed to the housing and arranged on the rear side of the centrifugal fan, and the output shaft extends into the volute assembly; An impeller assembly includes a front plate, a back plate, and main blades. The front plate is arranged at the front relative to the back plate, the back plate has a secondary air inlet, the main blades are located between the front plate and the back plate, the main blades are configured to draw in gas from the main air inlet, and the impeller assembly is configured to rotate under the action of the output shaft. The impeller assembly includes a main flow channel and a secondary flow channel. The main flow channel connects the main air inlet and the air outlet, and the secondary flow channel connects the secondary air inlet and the air outlet. The main flow channel and the secondary flow channel are at least partially spaced apart. Furthermore, the impeller assembly also includes a baffle plate, which is 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.

2. The centrifugal fan according to claim 1, wherein the baffle plate has a disc shape and extends radially outward from the central axis to the main blade, the main flow channel is located on the front side of the baffle plate, and the secondary flow channel is located on the rear side of the baffle plate.

3. The centrifugal fan according to claim 2, wherein a recessed groove is formed on the back plate, the groove having a bottom plate and a side plate, the bottom plate facing the back plate, the side plate extending from the bottom plate to the back plate, and a plurality of through slots forming the secondary flow channel.

4. The centrifugal fan according to claim 3, wherein the grooved side plate extends in a direction perpendicular to the back plate.

5. The centrifugal fan according to claim 4, wherein the groove bottom plate is provided with auxiliary blades, the auxiliary blades being configured to draw in gas from the auxiliary air inlet.

6. The centrifugal fan according to claim 4, wherein the auxiliary blades extend from the grooved bottom plate to the inside of the back plate.

7. The centrifugal fan according to claim 4, wherein the auxiliary blades are turned out from the bottom plate of the groove through the material at the through slot.

8. The centrifugal fan according to claim 3, wherein the grooved side plate extends from the grooved bottom plate in a radially outward direction to the back plate.

9. The centrifugal fan of claim 8, wherein the recessed side plate is configured to draw in gas from the secondary air inlet.

10. The centrifugal fan according to any one of claims 3 to 8, wherein the through slot extends through the groove side plate to the inside of the back plate.

11. The centrifugal fan according to any one of claims 3 to 8, wherein the baffle plate is fitted with the grooved bottom plate.

12. The centrifugal fan according to any one of claims 3 to 8, wherein the baffle plate, the grooved bottom plate and the back plate are respectively provided with mutually aligned shaft holes, and the shaft holes are aligned with the output shaft. 13.The centrifugal blower of claim 1, wherein the damper plate is fixed to the output shaft by a nut. 14.The centrifugal blower of claim 1, further comprising a sealing gasket arranged between the output shaft and the housing. 15.The centrifugal blower of claim 1, further comprising a sealing groove arranged on an outer circumferential 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.

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