EP2980304A1

EP2980304A1 - Centrifugal fan and clothes dryer having same

Info

Publication number: EP2980304A1
Application number: EP13880416.6A
Authority: EP
Inventors: Pengfei LU; Hua Huang; Fuchang ZHOU
Original assignee: Wuxi Little Swan Co Ltd
Current assignee: Wuxi Little Swan Co Ltd
Priority date: 2013-03-28
Filing date: 2013-03-28
Publication date: 2016-02-03
Anticipated expiration: 2033-03-28
Also published as: EP2980304B1; EP2980304A4; WO2014153748A1

Abstract

Disclosed are a centrifugal fan and a clothes dryer having same. The centrifugal fan (100) comprises: a plurality of primary blades (3) arranged on the periphery thereof, and a plurality of secondary blades (4) distributed in radial directions and arranged on a mask of the centrifugal fan facing the air intake direction. The centrifugal fan further comprises a wheel rim (1) and a wheel disc (2). The central zone of the wheel disc is constructed into an electrical motor shield (21), the plurality of primary blades are circumferentially arranged between the wheel rim and the wheel disc at intervals, a first airflow channel (31) is defined between two adjacent primary blades, the plurality of secondary blades are provided on the electrical motor shield around a connecting shaft sleeve, a second airflow channel (41) is defined between two adjacent secondary blades, and the first airflow channels, the second airflow channels and air inlets are in communication with one another. The centrifugal fan can effectively reduce the impeding effect of the electrical motor shield, so as to enable the flow state of the airflow at the air inlets of the centrifugal fan to be better, and achieve the two-stage boost and acceleration of the secondary blades and the primary blades, thereby significantly increasing the pressure of the airflow at outlets of the centrifugal fan, and improving the efficiency of the ventilator.

Description

Field

The present disclosure relates to a field of household appliances, and more particularly to a centrifugal fan and a clothes dryer having the same.

Background

Ventilators are roughly divided into an axial flow ventilator and a centrifugal ventilator according to different directions of air flowing. A centrifugal ventilator enables air to enter a centrifugal fan in axial directions by rotating the centrifugal fan at high speed and enables air to be exhausted from intervals between blades of the centrifugal fan in radial directions under an effect of a centrifugal force. The centrifugal fan of the centrifugal ventilator is generally powered by a motor, and is driven by the rotation of an output shaft of the motor to rotate at high-speed.
A centrifugal fan in the related art generally is provided with an electrical motor shield in the central zone thereof, however the electrical motor shield with large volume becomes a main obstacle for airflow entering the center negative pressure zone of the centrifugal fan, and the airflow turns into backflow after striking the surface of the electrical motor shield during flowing, such that the flow state at the air inlets of the centrifugal ventilator is poor, and the performance of the ventilator decreases.

Summary

The present disclosure seeks to solve at least one of the problems in the related art, for this, the present disclosure provides a centrifugal fan which enables the flow state of the airflow at the air inlets thereof to be better, and increases the pressure of the airflow at outlets of the ventilator and improves the efficiency of the ventilator.
The present disclosure further provides a clothes dryer including the centrifugal fan.
A centrifugal fan according to a first aspect of the present disclosure includes a plurality of primary blades arranged on a periphery thereof, wherein a plurality of secondary blades distributed in radial directions of the centrifugal fan are arranged on a mask of the centrifugal fan facing an air intake direction.
The centrifugal fan according to the present disclosure can effectively reduce the impeding effect of the mask or an electrical motor shield, so as to enable the flow state of the airflow at the air inlets of the centrifugal fan to be better, and achieve the two-stage boost and acceleration of the secondary blades and the primary blades, thereby significantly increasing the pressure of the airflow at outlets of the centrifugal fan, and improving the efficiency of the ventilator.
According to embodiments of the present disclosure, the mask of the centrifugal fan is an electrical motor shield.
According to embodiments of the present disclosure, the centrifugal fan further includes: a wheel rim having an air inlet for the air intake; and a wheel disc arranged below the wheel rim, wherein a central zone of the wheel disc is constructed into the electrical motor shield, and the electrical motor shield protrudes upward and is provided with a connecting shaft sleeve on a top thereof; wherein the plurality of primary blades are circumferentially arranged between the wheel rim and the wheel disc at intervals, and a first airflow channel is defined between two adjacent primary blades; wherein the plurality of secondary blades are provided on the electrical motor shield around the connecting shaft sleeve, a second airflow channel is defined between two adjacent secondary blades, and the first airflow channel, the second airflow channel and the air inlet are in communication with one another.
When the centrifugal fan rotates, a portion of the airflow entering the centrifugal fan from the air inlets may flow to the gaps between the electrical motor shield and the primary blades, and is boosted and accelerated by the primary blades during high speed rotation of the centrifugal fan, then is exhausted from the first airflow channels; the other portion of which may flow along the second airflow channels first under the guidance of the secondary blades during flowing in axial directions, then flows into the first airflow channels and is exhausted therefrom. Therefore, turbulent flow formed by airflow rebounding and refluxing after striking the top surface of the electrical motor shield is avoided, the flow state at the air inlets of the centrifugal fan can be better adjusted, and the ventilation efficiency is improved greatly. Moreover, the airflow entering the centrifugal fan can be boosted and accelerated by the secondary blades first, and then be boosted and accelerated again by the primary blades and be exhausted therefrom, such that the pressure at outlets and the flow rate of the ventilator are further improved.
In summary, the centrifugal fan according to the present disclosure can enable the flow state of the airflow at the air inlets thereof to be better, avoid turbulence flow, increase the airflow pressure and the flow rate and improve the efficiency of the ventilator.
In addition, the centrifugal fan according to the present disclosure further has following additional technical features.
The plurality of secondary blades comprise a plurality of groups of secondary blades, and the plurality of groups of secondary blades are evenly arranged around the connecting shaft sleeve. In this way, the quality uniformity of the entire centrifugal fan is guaranteed, thereby avoiding the centrifugal fan shaking during a rotation process.
Preferably, the plurality of secondary blades are evenly arranged around the connecting shaft sleeve. In this way, the quality uniformity of the entire centrifugal fan is guaranteed, thereby avoiding the centrifugal fan shaking during the rotation process.
Preferably, an upper surface of the secondary blade is flush with that of the wheel rim. In this way, the stability of the airflow state can be further increased, and the turbulence flow can be further decreased.
Preferably, a thickness of the secondary blade is same with that of the primary blade. In this way, the airflow direction tends to be more reasonable.
Preferably, a shape of the secondary blade is configured codirectionally with that of the primary blade. In this way, the airflow directions tend to be uniform, and the air flows more stable, thus ensuring the stability of the airflow.
Preferably, an inflow angle of the secondary blade is same with that of the primary blade.
Preferably, an outflow angle of each secondary blade is slightly less than that of each primary blade.
Therefore, an impact loss can be effectively reduced when the airflow flows from the second airflow channels to the first airflow channels, thus ensuring air flows more stable.
The wheel rim, the wheel disc, the plurality of primary blades and the plurality of secondary blades are formed integrally. Therefore, the steadiness degree of connections between the wheel rim, the wheel disc, the plurality of primary blades and the plurality of secondary blades can be guaranteed.
A top surface of the electrical motor shield is formed as a curved surface or a plane surface. The connecting shaft sleeve is arranged coaxially with the electrical motor shield.
A clothes dryer according to a second aspect of the present disclosure includes an air channel and a centrifugal fan according to the first aspect of the present disclosure, wherein the centrifugal fan is arranged within the air channel.
As the centrifugal fan can enable the flow state of the airflow at the air inlets thereof to be better, reduce the turbulence flow, increase the airflow pressure and the flow rate, and improve the efficiency of the ventilator, the clothes dryer provided with the centrifugal fan has advantages of high working efficiency and good performance.
Additional aspects and advantages of embodiments of present disclosure will be given in part in the following descriptions, become apparent in part from the following descriptions, or be learned from the practice of the embodiments of the present disclosure.

Brief description of the drawings

These and other aspects and advantages of embodiments of the present disclosure will become apparent and more readily appreciated from the following descriptions made with reference to the drawings, in which:

Fig. 1 is a top view of a centrifugal fan according to an embodiment of the present disclosure.
Fig. 2 is a side view of a centrifugal fan according to an embodiment of the present disclosure.
Fig. 3 is a perspective view of a centrifugal fan according to an embodiment of the present disclosure.
Fig. 4 is a schematic diagram of a clothes dryer including a centrifugal fan according to an embodiment of the present disclosure.

Detailed description

Reference will be made in detail to embodiments of the present disclosure. The embodiments described herein with reference to drawings are explanatory, illustrative, and used to generally understand the present disclosure. The embodiments shall not be construed to limit the present disclosure. The same or similar elements and the elements having same or similar functions are denoted by like reference numerals throughout the descriptions.
In the specification, it is to be understood that terms such as "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise" should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the present invention be constructed or operated in a particular orientation. In addition, terms such as "first" and "second" are used herein for purposes of description and are not intended to indicate or imply relative importance or significance or to imply the number of indicated technical features. Thus, the feature defined with "first" and "second" may comprise one or more of this feature. In the description of the present invention, "a plurality of" means two or more than two, unless specified otherwise.
In the description of the present disclosure, it should be understood that, unless specified or limited otherwise, the terms "mounted," "connected," "coupled," and the like are used broadly, and may be, for example, fixed connections, detachable connections, or integral connections; may also be mechanical or electrical connections; may also be direct connections or indirect connections via intervening structures; may also be inner communications of two elements, which can be understood by those skilled in the art according to specific situations.
The centrifugal fan 100 according to embodiments of the present disclosure will be described blow with referring to Fig. 1 to Fig. 4. The centrifugal fan 100 is an important part of a clothes dryer 200 or a clothes washer and dryer, and is driven to rotate by an electrical motor. The clothes dryer 200 includes an air channel 10 and the centrifugal fan 100 arranged within the air channel 10. Certainly, the clothes dryer 200 further includes an accommodating cylinder for receiving clothes, an electrical system and a shell, which is well known to those skilled in the art and will not be elaborated here.
According to embodiments of the present disclosure, the centrifugal fan 100 includes a plurality of primary blades 3 arranged on a periphery thereof, and a plurality of secondary blades 4 distributed in radial directions of the centrifugal fan and arranged on a mask of the centrifugal fan 100 facing an air intake direction. In a specific embodiment, the mask of the centrifugal fan is an electrical motor shield 21, the electrical motor for driving the centrifugal fan 100 can be arranged back the electrical motor shield 21.
According to embodiments of the present disclosure, as shown in Fig. 1 to Fig. 3, the centrifugal fan 100 further includes a wheel rim 1 and a wheel disc 2.
For convenience of description, in the following embodiments of the present disclosure, the structure of the centrifugal fan 100 will be described based on an example that the wheel rim 1 and the wheel disc 2 are positioned in an up-down direction. In the description of embodiments of the present disclosure: "the up-down direction" is indicated by arrows shown in Fig. 2 and Fig. 3. But it should be noted that, the direction indicated is used for purposes of description and is not intended to limit the present disclosure.
In a perspective view as shown in Fig. 3, the wheel rim 1 defines a plurality of air inlets for the air intake. The wheel rim 1 is configured as an annulus, an inner ring of the annular defines the plurality of air inlets, when the centrifugal fan 100 operates, the air can enter the centrifugal fan 100 via the air inlets to form an inlet airflow.
The wheel disc 2 can be arranged blow the wheel rim 1, a central zone of the wheel disc 2 is constructed into the electrical motor shield 21 protruding upwards, the electrical motor shield 21 is provided with a connecting shaft sleeve 22 on a top thereof, an output shaft of the electrical motor can be provided on the connecting shaft sleeve 22 so as to enable the centrifugal fan 100 to rotate under the driving by the electrical motor.
The plurality of primary blades 3 are circumferentially arranged between the wheel rim 1 and the wheel disc 2 at intervals, and a first airflow channel 31 is defined between two adjacent primary blades 3. The airflow entering the centrifugal fan 100 from the air inlets is exhausted from the first airflow channel 31 in radial directions of the centrifugal fan 100 under the effect of a centrifugal force generated by high speed rotation of the centrifugal fan 100.
The plurality of secondary blades 4 are arranged on the wheel disc 2, specifically, on the electrical motor shield 21 positioned on the central zone of the wheel disc 2, and are circumferentially arranged around the connecting shaft sleeve 22, wherein a second airflow channel 41 is defined between two adjacent secondary blades 4. The first airflow channels 31, the second airflow channels 41 and the air inlets are in communication with one another. After entering the centrifugal fan 100 from the air inlets, the air not only can be exhausted directly from the first airflow channels 31, but also can be exhausted from the first airflow channels 31 after passing through the second airflow channels 41.
Specifically, When the centrifugal fan 100 rotates, a portion of the airflow entering the centrifugal fan 100 from the air inlets flows to the gaps between the electrical motor shield 21 and the primary blades 3, and is boosted and accelerated by the primary blades 3 during the high speed rotation of the centrifugal fan 100, then is exhausted from the first airflow channels 31; the other portion of which flows along the second airflow channels 41 first under the guidance of the secondary blades 4 during flowing in axial directions, then flows into the first airflow channels 31 and is exhausted therefrom. Therefore, turbulent flow formed by airflow rebounding and refluxing after striking the top surface of the electrical motor shield 21 is avoided, the flow state at the air inlets is better improved, and the ventilation efficiency is improved greatly. Moreover, the airflow entering the centrifugal fan 100 can be boosted and accelerated by the secondary blades 4 first, and then be boosted and accelerated again by the primary blades 31 and be exhausted therefrom, such that the pressure of airflow is further improved, thus increasing the flow rate to a certain extent.
In summary, the centrifugal fan 100 according to the present disclosure can enable the flow state of the airflow at the air inlets thereof to be better, reduce the turbulence flow, increase airflow pressure and the flow rate, and improve the ventilation efficiency of the fan.
As shown in Fig. 3, in an embodiment of the present disclosure, when the top of the electrical motor is configured as an arc, then the top surface of the electrical motor shield 21 may be configured as an arc-shaped surface, the connecting shaft sleeve 22 is arranged coaxially with the electrical motor shield 21, i.e. the axis of the connection shaft sleeve 22 coincides with that of the electrical motor shield 21. Thereby the structure of the centrifugal fan 100 is more reasonable, and the rotation of the electrical motor while driving the centrifugal fan 100 is more stable.
In another embodiment of the present disclosure, when the top of the electrical motor is configured as a plane surface, then the top surface of the electrical motor shield 21 may be configured as a plane surface, the connecting shaft sleeve 22 is arranged coaxially with the electrical motor shield 21, i.e. the connection shaft sleeve 22 is arranged at the center of the electrical motor shield 21. Thereby the electrical motor shield 21 can better adapt to the shape of the electrical motor, and the rotation of the electrical motor while driving the centrifugal fan 100 is more stable.
Certainly, the present disclosure is not limited to this, the electrical motor shield 21 may be configured as different shapes based on the different structures of the electrical motor, the description herein is just used for purposes of example and is not intended to limit the present disclosure.
In a preferred embodiment of the present disclosure, the plurality of secondary blades 4 may be divided into a plurality of groups of secondary blades which are evenly arranged around the connecting shaft sleeve 22. In this way, the quality uniformity of the entire centrifugal fan 100 is guaranteed, thereby avoiding the centrifugal fan 100 shaking during the rotation process, further avoiding a chaos of the airflow entering the centrifugal fan 100.
Specifically, provided that there are twenty-four secondary blades 4 totally which are divided into six groups of secondary blades, then each group of secondary blades includes four secondary blades 4, the six groups of secondary blades 4 are evenly arranged around the connecting shaft sleeve 22, it could be appreciated that, the intervals between each two adjacent groups of secondary blades 4 are uniform, and each group among the six groups of secondary blades 4 has a same structure, shape and size, thus enabling the structure and the quality of the centrifugal fan 100 to be distributed more evenly. The four secondary blades 4 in each group of secondary blades 4 may be designed and arranged accordingly depending on the actual ventilation needs.
In a more preferred embodiment of the present disclosure, as shown in Fig. 1, the plurality of secondary blades 4 are evenly arranged around the connecting shaft sleeve 22. That is, the twenty-four secondary blades 4 described above are evenly arranged around the connecting shaft sleeve 22, thus further improving the quality uniformity of the centrifugal fan 100, thereby further avoiding the centrifugal fan 100 shaking during the rotation process, and further enabling the airflow entering the centrifugal fan 100 to be more orderly.
In some embodiments of the present disclosure, both the primary blades 3 and the secondary blades 4 are configured as forward blades or backward blades. As described hereinbefore, the outflow angle of each secondary blade is close to that of each primary blade which basically confirms the shapes of the secondary blade 4 and the primary blade 3 having same directions, if the angle of the outflow angle is greater than 90 °, thus considering the primary blades 3 and the secondary blades 4 being configured as forward blades shape; if the angle of the outflow angle is less than 90 °, thus considering the primary blades 3 and the secondary blades 4 being configured as backward blades shape. Specifically, the primary blades 3 and the secondary blades 4 have same bending directions. For example, if the primary blades 3 bend inward and clockwise around the connecting shaft sleeve 22, the secondary blades 4 may also bend inward and clockwise around the connecting shaft sleeve 22. Therefore, the airflow entering the second airflow channels 41 can enter the first airflow channels 31 in accordance with the original flow directions, in this way, the airflow directions tend to be uniform, and the air flows more stable, thus ensuring the stability of the airflow.
In some embodiments of the present disclosure, the inflow angle of each secondary blade 4 may be same with that of each primary blade 3, thus further ensuring the uniformity of the airflow directions, and the airflow is more stable during flowing from the second airflow channels 41 to the first airflow channels 31, thereby reducing the impact loss of the airflow at the air inlets.
Further, the outflow angle of each secondary blade 4 is slightly less than that of each primary blade 3 so as to further ensuring the stability of the airflow and the flow state to be more uniform when the airflow flows from the second airflow channels 41 to the first airflow channels 31.
In some embodiments of the present disclosure, the thickness of each secondary blade 41 is same with that of each primary blade 31. In this way, the airflow is distributed more evenly when flowing from the second airflow channels 41 to the first airflow channels 31, thus ensuring the airflow more stable among the centrifugal fan.
In some preferred embodiments of the present disclosure, the upper surface of each secondary blade 4 shall not exceed that of the wheel rim 1, thus enabling the flow state of the airflow to be more stable, and reducing the turbulence flow.
Further, the upper surface of each secondary blade 4 is flush with that of the wheel rim 1, thus further improving the stability of the flow state of the airflow, and further reducing the turbulence flow.
In an embodiment of the present disclosure, the wheel rim 1, the wheel disc 2, the plurality of primary blades 3 and the plurality of secondary blades 4 are formed integrally. Specifically, each secondary blade 4 is formed integrally on the electrical motor shield 21 of the wheel disc 2, and the upper and lower ends of each primary blade 3 are integrally connected with the wheel rim 1 and the wheel disc 2, respectively. Optionally, the wheel rim 1, the wheel disc 2, the primary blades 3 and the secondary blades 4 may be plastic articles and molded integrally by an injection method. Therefore, not only the steadiness degree of connections among the wheel rim 1, the wheel disc 2, the plurality of primary blades 3 and the plurality of secondary blades 4 can be guaranteed, but both the manufacturing cost of materials and the weight of the centrifugal fan 100 can be reduced by using plastic articles to produce the centrifugal fan 100.
The present disclosure further relates to a centrifugal ventilator including a centrifugal fan 100 according to above embodiments of the present disclosure. As the centrifugal fan 100 has a plurality of advantages, such as enabling the flow state of the airflow at the air inlets thereof to be better, inducing the turbulence flow, increasing the airflow pressure and the flow rate, and improving the ventilation efficiency, Therefore, the centrifugal ventilator provided with the centrifugal fan 100 has advantages of high ventilation efficiency and good performance.
The centrifugal ventilator according to embodiments of the present disclosure further includes an electrical motor and a volute shell, and both the electrical motor and the centrifugal fan 100 can be arranged within the volute shell.
Specifically, the volute shell may define an upper end plate, a lower end plate and a sidewall plate arranged circumferentially. The upper end plate, the lower end plate and the sidewall plate of the volute shell together define an accommodating space, and both the electrical motor and the centrifugal fan 100 are arranged within the accommodating space.
The upper end plate may define a second air inlet for the air intake, the first air inlet is concentric with the second air inlet when the centrifugal fan 100 is arranged within the volute shell. The lower end plate may be provided with an accommodating groove for accommodating the electrical motor, and the electrical motor is arranged within the accommodating groove, when the centrifugal fan 100 is arranged within the volute shell, the electrical motor shield 21 can shield the electrical motor, i.e. the electrical motor shield 21 and the accommodating groove can define an installation space, and the electrical motor is arranged within the installation space, and the output shaft of the electrical motor is connected with the connecting shaft sleeve 22. The sidewall plate defines an air outlet for the air outtake, thus the entered airflow via the second air inlet and the first air inlet is finally exhausted out of the centrifugal fan from the air outlet. As this is well known to those skilled in the art and will not be elaborated here.
The operation process of the centrifugal fan will be described briefly in the following.
Starting the electrical motor, the output shaft of the electrical motor can drive the centrifugal fan 100 to rotate. The air around the centrifugal ventilator enters the centrifugal ventilator via the second and first air inlets in turn to form an inlet airflow. A portion of the inlet airflow can enter the first airflow channels 31 directly from the gaps between the electrical motor shield 21 and the primary blades 3 and then is exhausted out of the centrifugal fan 100; the other portion of the inlet airflow can first enter the second airflow channels 41 and achieve a boost and acceleration on there, then enters the first airflow channels 31 and is exhausted out of the centrifugal fan 100 therefrom. The high speed airflow exhausted from the centrifugal fan 100 enters the volute shell and is exhausted from the air outlet after gathering in the volute shell, so as to complete a carriage of the airflow via the centrifugal ventilator.
According to embodiments of the present disclosure, the clothes dryer 200 provided with the centrifugal fan 100 promotes the air circulation as playing a driving effect to the airflow in the air channel 10, so as to enabling the clothes to dry faster and more uniform. As the centrifugal fan 100 has a plurality of advantages, such as enabling the flow state of the airflow at the air inlets thereof to be better, including the turbulence flow, increasing airflow pressure and the flow rate, and improving the efficiency of the fan, Therefore, the clothes dryer 200 provided with the centrifugal fan 100 has advantages of high working efficiency and good performance.
Reference throughout this specification to "an embodiment," "some embodiments," "one embodiment", "another example," "an example," "a specific example," or "some examples," means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. Thus, the appearances of the phrases such as "in some embodiments," "in one embodiment", "in an embodiment", "in another example," "in an example," "in a specific example," or "in some examples," in various places throughout this specification are not necessarily referring to the same embodiment or example of the present disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.
Although explanatory embodiments have been shown and described, it would be appreciated by those skilled in the art that the above embodiments cannot be construed to limit the present disclosure, and changes, alternatives, and modifications can be made in the embodiments without departing from spirit, principles and scope of the present disclosure.

Claims

A centrifugal fan comprising a plurality of primary blades arranged on a periphery thereof, wherein a plurality of secondary blades distributed in radial directions of the centrifugal fan are arranged on a mask of the centrifugal fan facing an air intake direction.
The centrifugal fan for a clothes dryer according to claim 1, wherein the mask of the centrifugal fan is an electrical motor shield.
The centrifugal fan for a clothes dryer according to claim 2, wherein the centrifugal fan further comprises:
a wheel rim having an air inlet for the air intake; and

a wheel disc arranged below the wheel rim, wherein a central zone of the wheel disc is constructed into the electrical motor shield, and the electrical motor shield protrudes upward and is provided with a connecting shaft sleeve on a top thereof,

wherein the plurality of primary blades are circumferentially arranged between the wheel rim and the wheel disc at intervals, and a first airflow channel is defined between two adjacent primary blades,

wherein the plurality of secondary blades are provided on the electrical motor shield around the connecting shaft sleeve, a second airflow channel is defined between two adjacent secondary blades, and the first airflow channel, the second airflow channel and the air inlet are in communication with one another.
The centrifugal fan according to claim 3, wherein the plurality of secondary blades comprises a plurality of groups of secondary blades, and the plurality of groups of secondary blades are evenly arranged around the connecting shaft sleeve.
The centrifugal fan according to claim 4, wherein the plurality of secondary blades are evenly arranged around the connecting shaft sleeve.
The centrifugal fan according to claim 3, wherein an upper surface of the secondary blade is flush with that of the wheel rim.
The centrifugal fan according to claim 3, wherein a thickness of the secondary blade is same with that of the primary blade.
The centrifugal fan according to claim 3, wherein a shape of the secondary blade is configured codirectionally with that of the primary blade.
The centrifugal fan according to claim 3, wherein an inflow angle of the secondary blade is same with that of the primary blade.
The centrifugal fan according to claim 3, wherein an outflow angle of the secondary blade is slightly less than that of the primary blade.
The centrifugal fan according to claim 3, wherein the wheel rim, the wheel disc, the plurality of primary blades and the plurality of secondary blades are formed integrally.
The centrifugal fan according to claim 3, wherein a top surface of the electrical motor shield is formed as a curved surface or a plane surface.
The centrifugal fan according to claim 12, wherein the connecting shaft sleeve is arranged coaxially with the electrical motor shield.
A clothes dryer comprising an air channel and the centrifugal fan according to any one of claims 1-13, wherein the centrifugal fan is arranged inside the air channel.