Patent Publication Number: US-2022235785-A1

Title: Neck fan

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation application of U.S. patent application Ser. No. 17/585,594 filed on Jan. 27, 2022. The U.S. patent application Ser. No. 17/585,594 is a continuation of U.S. patent application Ser. No. 17/471,178 filed on Sep. 10, 2021, which is a continuation of International Application No. PCT/CN2020/128564 filed on Nov. 13, 2020 under 35 U.S.C. § 371. The U.S. patent application Ser. No. 17/585,594 claims the priority of Chinese patent application No. 201921815938.3 filed on Oct. 25, 2019, and the International Application claims the priority of Chinese patent application No. 202022210032.8, filed on Sep. 30, 2020. All applications are incorporated herein by reference in their entireties. 
    
    
     FIELD 
     The subject matter herein generally relates to fans, and particularly relates to a fan hanging around a neck. 
     BACKGROUND 
     In recent years, people are increasingly pursuing a more convenient life. In order to meet needs of practical fans for outdoor activities or other life scenes, there are a variety of portable fans in the market, such as neck fans. The emergence of neck fans solves limited activity due to handheld fans. The neck fan can free users&#39; hands and realize cooling anytime and anywhere without holding it, whether during sports, outdoor activities or in office. 
     Existing neck fan generally has a fan assembly with two fan blades exposed at both ends of the neck fan. Such fan assembly not only has low safety that hair is easy to get involved in the fan blades, but also has problems such as outputted air being uncomfortable due to too concentrated air outlets, which needs to be improved. 
     SUMMARY OF THE INVENTION 
     In a first aspect, a neck fan includes an arc-shaped shell and at least two fan assemblies. The arc-shaped shell is configured to be worn around a neck of a user. The arc-shaped shell comprises a first portion configured to be worn around a side of the neck and a second portion configured to be worn around another side of the neck. Each of the first portion and the second portion includes a wall defining a receiving space, and the wall comprises a first side wall close to the neck and a second side wall connected to and opposite to the first side wall. Each of the first side wall and the second side wall defines a plurality of air inlets, at least one of the first side wall and the second side wall defines a plurality of air outlets, and the plurality of air inlets and the plurality of air outlets are communicating with the receiving space. At least two fan assemblies are received in the receiving space of the first portion and the receiving space of the second portion, wherein each of the at least two fan assemblies is configured to guide air from the plurality of air inlets of the first side wall and the second side wall of a respective portion to the plurality of air outlets of the respective portion. Each of the at least two fan assemblies comprises a driving shaft and a fan blade assembly mounted on the driving shaft. The fan blade assembly is a turbine blade assembly. The turbine blade assembly includes a turbine fan, and the turbine fan defines two inlet windows corresponding to the air inlets of the first side wall and the second side wall respectively. 
     In a second aspect, a neck fan includes an arc-shaped shell, at least one partition, and at least two fan assemblies. The arc-shaped shell is configured to be worn around a neck of a user. The arc-shaped shell comprises a first portion configured to be worn around a side of the neck and a second portion configured to be worn around another side of the neck. Each of the first portion and the second portion comprises a wall, the wall defines a receiving space, a plurality of air inlets communicating with the receiving space, and a plurality of air outlets communicating with the receiving space. At least one partition is received in the receiving space and dividing the receiving space into at least two receiving sub-spaces, wherein the at least two receiving sub-spaces are distributed along an extension direction of the arc-shaped shell. The least two fan assemblies are received in the at least two receiving sub-spaces respectively and configured to guide air to flow from the plurality of air inlets to the plurality of air outlets. The at least one partition and the wall cooperatively define an air duct. A cross-sectional area of the air duct is decreased along a direction from the first portion to the second portion, and/or a cross-sectional area of the air duct of the second portion is decreased along a direction from the second portion to the first portion. Each of the at least two fan assemblies comprises a driving shaft and a fan blade assembly mounted on the driving shaft. The fan blade assembly is a turbine blade assembly. The turbine blade assembly includes a turbine fan, and the turbine fan defines two inlet windows corresponding to the air inlets of the first side wall and the second side wall respectively. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Implementations of the present disclosure will now be described, by way of embodiment, with reference to the attached figures. It should be understood, the drawings are shown for illustrative purpose only, for ordinary person skilled in the art, other drawings obtained from these drawings without paying creative labor by an ordinary person skilled in the art should be within scope of the present disclosure. 
         FIG. 1  is a schematic view of a neck fan according to an embodiment of the present application. 
         FIG. 2  is an explosive view of a neck fan according to an embodiment of the present application. 
         FIG. 3  is a schematic view of an inner shell of a neck fan according to an embodiment of the present application. 
         FIG. 4  is a schematic view of a turbo fan of a neck fan according to an embodiment of the present application. 
         FIG. 5  is a schematic view of a neck fan in according to a first embodiment of the present disclosure. 
         FIG. 6  is an exploded view of the neck fan of  FIG. 5 . 
         FIG. 7  is a schematic view of a neck fan in according to a second embodiment of the present disclosure. 
         FIG. 8  is an exploded view of the neck fan of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION 
     It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the exemplary embodiments described herein. However, it will be understood by those of ordinary skill in the art that the exemplary embodiments described herein may be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the exemplary embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts may be exaggerated to better illustrate details and features of the present disclosure. 
     The term “comprising” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series, and the like. The disclosure is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references can mean “at least one”. In addition, the terms “first” and “second” are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implying the number of indicated technical features. Thus, the features defined as “first” and “second” may explicitly or implicitly include one or more of the said features. In the description of embodiments of the invention, “a plurality of” means two or more, unless otherwise specifically defined. 
     In an embodiment, as shown in  FIGS. 1 and 2 , the present disclosure provides a neck fan including a body portion  1  and a fan assembly  2 . The body portion  1  may be worn around a neck of a user. The body portion  1  defines an air duct  11 . The body portion  1  defines a plurality of air outlets  12  communicating with the an outside of the neck fan and the air duct  11 . In this way, air in the air duct  11  may flow to the outside through the air outlets  12 . The fan assembly  2  is mounted on the body portion  1  and is configured to drive the air from the outside into the air duct  11  and blow the air to the outside through the air outlets  12 . The air driven into the air duct  11  through fan assembly  2  has a certain speed. Therefore, a wind pressure difference is present between an inside and the outside of air outlets  12 , i.e., between the air duct and the outside. In this case, while the air is being blown to the outside through the air outlets  12 , due to the wind pressure difference, some of the air in the air duct  11  may flow out of the air duct  11  through air outlets  12  to reach the neck to cool the user. In an embodiment, the plurality of air outlets  12  are evenly distributed and spaced apart from each other. Therefore, when being worn, the body portion  1  surrounds a front, a side and a back of the neck, and the air blown out from the air outlets  12  may be directed to the front, the side and the back of the neck. In this way, a range that the air may reach is expanded, and the user may be cooled from various directions. The neck fan is highly applicable and may be used conveniently. 
     As shown in  FIG. 1 , the body portion  1  may be bent and tubular and may be made of an elastic material that can be extended and retracted. When putting on the body portion, two ends of the body portion  1  may be pulled apart from each other to form a gap, and a size of the gap may be greater than a size (such as a diameter) of the neck. After the neck fan is worn to the neck, the body portion may be reset, i.e., the two ends may be reset to original positions, and the gap between the two ends of the body portion may be reduced. In some embodiments, when the two ends are at the original positions, the two ends may be spaced apart from each other, and a size of the gap therebetween may be less than the size of the neck. In some embodiments, when the two ends of the body portion are at the original positions, the two ends may be connected to each other, such that the body portion is ring-shaped (such as forming an enclosed circle). The body portion  1  may be made of plastic. The user may carry the body portion easily and may feel comfortable when wearing the body portion. The air outlets  12  are oriented towards an inside and/or a top of the bent and tubular body portion. Therefore, while being worn, the neck does not cover the air outlets  12 , allowing the air to be blown out the air outlets  12  to the neck smoothly. In detail, some of the air outlets  12  defined in the body portion  1  are oriented towards the inside of the tubular body portion, and some of the air outlets  12  are oriented towards the top of the tubular body portion  1 , increasing a range covered by the air supplied from the air outlets  12 . 
     As shown in  FIGS. 1 to 3 , each of two ends of the body portion  1  defines a mounting cavity  13 . The fan assembly  2  is received in the mounting cavity  13  to be mounted with the body portion  1 . A portion of the body portion  1  corresponding to the mounting cavity  13  defines an air inlet  131 . The fan assembly  2  is fixedly received in the mounting cavity  13 . When the fan assembly  2  is operating, the fan assembly  2  draws in the air in the outside through the air inlet  131 , and is configured to accelerate the air to drive the air to flow into the air duct  11 . In the present embodiment, two ends of the body portion  1  define two mounting cavities  13 , and two fan assemblies  2  may be received in the two mounting cavities  13 , respectively. Each of the two fan assemblies  2  may operate independently. A plate  111  may be arranged in a middle of the air duct  11  to divide the air duct  11  into two sections. One of the two sections of the air duct  11  corresponds to one of the two fan assemblies  2 . By arranging the plate  111 , a length of the air duct  11  may be reduced effectively, ensuring an air velocity at an air outlet  12 , which is further away from the fan assembly  2 . 
     As shown in  FIGS. 2 and 4 , the fan assembly  2  includes a fan blade  21 , a motor (not shown in the figures) which drives the fan blade  21  to rotate to generate an air flow, a battery  22  which provides power to the motor, a main control circuit board  23  which controls a rotation speed of the motor, and a gear switch  24  electrically connected to the main control circuit board  23 . When the neck fan needs to be initiated, the gear switch  24  may be pressed, and the main control circuit board  23  may receive a signal from the gear switch  24 . After receiving the signal, the main control circuit board  23  controls the motor to rotate to drive the fan blade  21  to rotate. Rotation of the fan blade  21  may lead the air at the outside to flow into the fan assembly  2  under the wind pressure, and the air may be guided by the fan assembly  2  to flow into the air duct  11 . When the wind speed of the air flowing out of the air outlets  12  needs to be adjusted, the gear switch  24  may be pressed to generate various gear signals. The main control circuit board  23  may receive the gear signals and control the rotation speed of the motor to further control the rotation speed of the fan blade  21  connected to the motor. Accordingly, a speed of the air driven by the fan assembly  2  to flow into the air duct  11  and a speed of the air flowing out through the air outlets  12  may change. A partition  14  may be arranged inside the body portion  1 . The partition  14  separates an inner space of the body portion  1  into a shaped cavity  15  and the air duct  11 . The battery  22  and the circuit board both are received in the shaped cavity  15 . The battery  22  may be disposed in a middle of the inner space of the body portion  1 . In this way, the fan assemblies  2  are arranged at the two ends of body portion  1 , whereas the battery  2  is arranged at the middle of the body portion  1 , the two ends of the body portion  1  may not be too heavy, and weights of the two ends of the body portion  1  may be balanced, preventing a weight center of the body portion  1  from being shifted towards one side. 
     As shown in  FIG. 2 , a cross-sectional area of the air duct  11  gradually decreases from the two ends to the middle of the body portion  1 . The air flowing from the two ends to the middle of the body portion  1  may generate a frictional force. At the same time, the cross-sectional area of the air duct  11  decreases from the two ends to the middle of the body portion  1 , i.e., the cross-sectional area that the air passes through while flowing in the air duct  11  decreases. In this way, an effect of the frictional force on slowing down the speed of the air flow in the air duct  11  may be partially or completely eliminated. The speed of the air flowing out of the air outlets  12  may be controlled within a certain range, solving a problem of a large difference between the speed of the air flowing out of an air outlet  12  at or near the two ends of the air duct  11  and the speed of the air flowing out of an air outlet  12  in the middle of the air duct  11 . 
     As shown in  FIG. 2 , the body portion  1  includes an outer shell  16  and an inner shell  17 . Compared to the body portion  1  configured as a one-piece structure, the body portion  1  of the present embodiment is assembled from the outer shell  16  and the inner shell  17 , allowing the fan assemblies to be processed and assembled more simply, and allowing later maintenance to be performed more easily. The partition  14  is arranged on the inner shell  17  and extends towards the outer shell  16 . The air duct  11  is defined cooperatively by the inner shell  17 , the outer shell  16  and the partition  14 . When the outer shell  16  is connected to the inner shell  17 , the partition  14  tightly abuts against an inner side of the outer shell  16 , preventing the air in the air duct  11  from entering the shaped cavity  15 . The air outlets  12  are defined in the inner shell  17 . A portion of the inner shell  17  that contacts the neck of the user extending upwardly to form a curved surface  171 . The curved surface  171  may be inclined at a certain angle relative to the portion that contacts the neck of the user, and the air outlets  12  are defined in the curved surface  171 , such that the air outlets  12  are oriented towards the inner side of the tubular body portion. 
     As shown in  FIGS. 2 and 4 , the fan assembly  2  includes a turbine fan  25 . The turbine fan  25  defines two inlet windows  251 , increasing a circulation area and an efficiency of the turbine fan  25  communicating with the external air. A cavity wall of the mounting cavity  13  defines two air inlets  131  corresponding to the two inlet windows  251  of the turbine fan  25 . When the turbine fan  25  is rotating, the external air may enter the inlet windows  251  through the air inlets  131 . A guide post  132  is arranged on the cavity wall of the mounting cavity  13  and extends towards the turbine fan  25 . The turbine fan  25  defines a guide hole  251  corresponding to the guide post  132 . When the turbine fan  25  is received in the mounting cavity  13 , the guide post  132  extends into the guide hole  251 , thereby securing the turbine fan  25  in the mounting cavity  13 . 
     As shown in  FIG. 4 , the turbine fan  25  defines an air outlet port  252 , which is corresponding to and communicating with the air duct  11 . An air flow generated by the turbine fan  25  enters the air duct  11  through the air outlet port  252 . A portion of a wall of the air outlet port  252  is received in the air duct  11 . The portion of the wall of the air outlet port  252  tightly abuts against a wall of the air duct  11 , reducing a loss of the air flow generated by the turbine fan  25  while the air is being guided into the air duct  11 . 
     In an embodiment, as shown in  FIGS. 5 and 6 ,  FIG. 5  is a schematic view of a neck fan according to an embodiment of the present disclosure, and  FIG. 6  is an explosive view of the neck fan of  FIG. 5 . The neck fan  30  includes an arc-shaped shell  10  and at least four fan assemblies  20 . The at least four fan assemblies  20  may be arranged inside the arc-shaped shell  10 . It shall be understood that, for illustration purposes only, in the following embodiment, the neck fan  30  including the at least four fan assemblies  20  will be taken as an example for illustration. 
     The arc-shaped shell  10  may be worn to surround the neck of the user. The arc-shaped shell  10  includes a first portion  11  and a second portion  12 . The first portion  11  and the second portion  12  are arranged around two sides of the neck, such as a left side and a right side. Each of the first portion  11  and the second portion  12  includes an inner wall  101  configured to be close to the neck, an outer wall  102  opposite to the inner wall  101 , a top wall  103  close to a head of the user and connecting between the inner wall  101  and the outer wall  102 , and a bottom wall  104  opposite to the top wall  103  and connecting between the inner wall  101  and the outer wall  102 . 
     The inner wall  101 , the outer wall  102 , the top wall  103 , and the bottom wall  104  cooperatively define a receiving space  105 . Each of the first portion  11  and the second portion  102  defines air inlets  106  and air outlets  107  communicating with the receiving space  105 . In detail, in the present embodiment, the inner wall  101 , the bottom wall  104 , and the top wall  103  may be connected into an integrated structure (such as, a one-piece structure) to serve as a first side wall. The outer wall  102  may serve as a second side wall opposite to the first side wall. The first side wall and the second side wall cooperatively define the receiving space  105 . 
     At least one partition  13  is received inside the receiving space  105  to divide the receiving space  105  into at least two receiving sub-spaces  105   a  and  150   b . The at least two receiving sub-spaces  105   a  and  150   b  are arranged successively along an extension direction of the arc-shaped shell  10 . Each of the at least two receiving sub-spaces correspond to and communicate with some of the air inlets  106  and some of the air outlets  107 . Each of the fan assemblies is received in one corresponding receiving sub-space. Each of the fan assemblies is configured to guide the air, which flows into the corresponding receiving sub-space through corresponding air inlets  106 , to flow to air outlets  107  corresponding to the receiving sub-space, allowing the air to be blown out through the corresponding air outlets  107 . The number of the air outlets  107  may be more than one. The more than one air outlets may be distributed along the extension direction of the arc-shaped shell  10 . Sizes, shapes of the air outlets  107  and/or distances between every two adjacent air outlets  107  vary gradually along the extension direction of the arc-shaped shell  10 . 
     Compared to the neck fan in the art, in the neck fan  30  illustrated in the above-mentioned embodiments, the arc-shaped shell  10  includes the first portion  11  and the second portion  12 . The first portion  11  and the second portion  12  are configured to be around two opposite sides of the neck. Each of the first portion  11  and the second portion  12  defines the receiving space  105 , the air inlets  106 , and the air outlets  107 . The air inlets  106  and the air outlets  107  communicate with the receiving space  105 . Each receiving space  105  is divided into at least two receiving sub-spaces by the partition  13 . Each of the fan assemblies  20  is arranged in one of the receiving sub-spaces and configured to guide the air at the air inlets  106  to flow to the air outlets  107  to be blown out. Since the fan assemblies  20  are received in the receiving space  105 , foreign matters, such as hair, may not be absorbed into the fan assemblies easily, allowing the neck fan to be used safely and conveniently. In the present embodiment, four receiving sub-spaces  105   a  and  105   b  are defined along the extension direction of the arc-shaped shell  10 , and four fan assemblies  20  may be arranged and received in four receiving sub-spaces respectively. Since a plurality of the receiving sub-spaces  105   a  and  105   b  are defined, a length of the air duct in each of the receiving sub-spaces may be relatively short. When the air is flowing in each of the receiving sub-spaces, a concentration of the air being output may be reduced, the user may be comfortable about the air output, wind noise may be reduced, and an air volume loss may be reduced. The applicant of the present disclosure finds that, the longer the air duct, the longer period of time that the air flows along the receiving sub-space, increasing the wind noise and the air volume loss. By dividing the receiving space  105  into the plurality of receiving sub-spaces  105   a  and  105   b , the wind noise and the air volume loss may be reduced significantly. In addition, by determining an extension direction, sizes, shapes of the air outlets  107  and distances between two adjacent air outlets  107 , the user may be more comfortable about the air output from the neck fan  30 , the air may be output from the neck fan  30  more softly, improving the user&#39;s experiences. 
     Further, each fan assembly  20  includes a driving shaft  21  and a fan blade assembly  22  mounted on the driving shaft  21 . The driving shaft  21  extends from the inner wall  101  towards the outer wall  102 . In this way, a thickness of the arc-shaped shell  10  along a direction from the inner wall  101  to the outer wall  102  may be reduced, such that the user may be comfortable when wearing the neck fan. 
     Further, the air inlets  106  are defined in the outer wall  102 , and the air outlets  107  are defined in the top wall  103 . It shall be understood that, the air inlets  106  are defined in the outer wall  102 , and the outer wall  102  faces outwardly (i.e., opposite to the neck of the user), and therefore, the air may enter the shell easily and smoothly. In addition, the air outlets  107  are defined in the top wall  103 , and the driving shaft  21  extends from the inner wall  101  to the outer wall  102 . In this way, the fan blade assemblies  20  may direct the air from the air inlets  106  to the air outlets  107  to achieve a high air guiding efficiency. Moreover, the air outlets  107  are defined in the top wall  103 , such that the air may be output towards a face and the head of the user, such that the user may be cooled rapidly. 
     Further, an end of the driving shaft  21  is fixedly arranged on the inner wall  101 . It shall be understood that, such arrangement together with the air inlets  106  defined in the outer wall  102  allows the air inlets  106  to be unblocked, achieving a better air inlet effect. 
     Further, each fan assembly  20  corresponds to a plurality of air inlets  106 . It shall be understood that, air is guided into the fan assembly  20  through the plurality of fan inlets  106 , allowing the neck fan to have a better appearance, preventing foreign matters from entering the fan assembly  20  easily, increasing usage safety. 
     Further, the number of the air inlets  106  corresponding to each fan assembly  20  may be the same. The air inlets  106  corresponding to each fan assembly  20  are distributed in a circular shape. It shall be understood that, such arrangement allows the neck fan to have a better appearance, and prevents foreign matters from entering the fan assembly  20  easily. A better air inlet effect may be achieved due to such arrangement and shapes of the fan assemblies  20 . 
     Further, a plurality of air inlets  108  are defined in the inner wall  101  corresponding to each fan assembly  20 . The fan assembly  20  can guide the air from the air inlets  108  to the air outlets  107 . Each of the plurality of air inlets  108  is arc shaped. The plurality of air inlets  108  corresponding to each fan assembly  20  are distributed in a circular shape. It shall be understood that, such arrangement allows the neck fan to have a better appearance, and prevents foreign matters from entering the fan assembly  20  easily. A better air inlet effect may be achieved due to such arrangement and shapes of the fan assemblies  20 . 
     Further, the fan blade assembly  22  is a turbine fan blade assembly. It shall be understood that the turbine fan blade assembly may reduce the wind noise and improves the usage safety. 
     Further, the neck fan  30  further includes a connecting portion  14  connected between the first portion  11  and the second portion  12 . The connecting portion  14  is configured to join the first portion  11  and the second portion  12  into an integrated structure. In the present embodiment, the connecting portion  14  may be configured as an individual element. In some embodiments, the connecting portion  14  may be integrally formed with one of the first portion  11  and the second portion  12 , and then assembled with the other of the first portion  11  and the second portion  12 . A structure of the connecting portion  14  may be various, and shall not be limited by the present disclosure. 
     The first portion  11  further includes an end plate  109  disposed at an end of the first portion  11  away from the connecting portion  14 . The second portion  12  further includes an end plate  109  disposed at an end of the second portion  12  away from the connecting portion  14 . Each end plate  109  is connected to the top wall  103 , the bottom wall  104 , the inner wall  101  and the outer wall  102 . Sizes of the air inlets  106  corresponding to the fan assembly  20  arranged near the connecting portion  14  are less than those of the air inlets  106  corresponding to the fan assembly  20  arranged near the end plate  109 . An outer diameter of the fan assembly  20  arranged near the connecting portion  14  is less that that of the fan assembly  20  arranged near the end plate  109 . In other words, an end of the first portion  11  at which the end plate  109  is disposed may serve as a free end, and an end of the second portion  12  at which the end plate  109  is disposed may serve as another free end. An end of the first portion  11  near the connecting portion  14  may serve as a connecting end, and an end of the second portion  12  near the connecting portion  14  may serve as another connecting end. In the present embodiment, the sizes of the air inlets  106  corresponding to the fan assembly  20  arranged near the connecting end are less than those of the air inlets  106  corresponding to the fan assembly  20  arranged near the free end. The outer diameter of the fan assembly  20  arranged near the connecting end is less than that of the fan assembly  20  arranged near the free end. It shall be understood that, by determining various sizes of the air inlets  106  and various outer diameters of the fan blade assemblies  20 , a size of the arc-shaped shell  10  may be gradually reduced along a direction from the end plate  109  to the connecting portion  14 , such that the shell  10  is more suitable to a curve of the neck, allowing the user to be comfortable. In the present embodiment, the end plate  109  may be arc shaped, providing a better appearance. The shape of the end plate  109  may further be suitable to shapes of the receiving sub-spaces  105   a  and shapes of the fan assemblies  20  to achieve a better air inlet and outlet effect. 
     It shall be understood that, for each of the first portion  11  or the second portion  12 , the inner wall  101 , the top wall  103 , the bottom wall  104 , the end plate  109 , and the partition  13  may be formed as a one-piece structure. The outer wall  102  may be buckled with the top wall  103 , the bottom wall  104 , and the end plate  109  through a buckle. There may be various types of buckles and various means to connect the above structure integrally, which will not be limited by the present disclosure. 
     Further, the number of the air outlets  107  may be more than one. The more than one air outlets  107  are distributed along the extension direction of the arc-shaped shell  10  and extends to a position near the connecting portion  14 . Sizes of the more than one air outlets  107  gradually decrease along a direction from the end plate  109  to the connecting portion  14 . It shall be understood that, the more than one air outlets  107  may improve the usage safety. Sizes of the more than one air outlets  107  gradually decrease along the direction from the end plate  109  to the connecting portion  14 , allowing the air to be output in a more concentrated manner, improving air outlet intensity. In addition, sizes of the receiving sub-spaces  105   a  and  105   b  gradually decrease along the extension direction of the air duct. Therefore, the air output from the overall neck fan may be more uniform, and the user may feel comfortable. In detail, the extension direction of the arc-shaped shell  10  includes a first extension direction and a second extension direction. A direction extending from the first portion  11  to the second portion  12  may be referred to as a first extension direction D 1 . The sizes of the more than one air outlets  107  defined in the first portion  11  are gradually reduced along the first extension direction D  1 . A direction extending from the second portion  12  to the first portion  11  is referred to as a second extension direction D 2 . The sizes of the more than one air outlets  107  defined in the second portion  12  are gradually reduced along the second extension direction D 2 . Furthermore, each of the air outlets  107  is a strip-shaped air outlet. An extension direction of the strip-shaped air outlet may be inclined in a preset angle relative to the extension direction of the arc-shaped shell  10 . The preset angle may be 90 degrees. It shall be understood that, by defining the air outlets  107  in the above extension direction, the air outlet of the neck fan  30  may be softer, and the user may be more comfortable, improving the user&#39;s experience. In particular, when the preset angle is 90 degrees, the air outlet efficiency of the air outlets  107  is improved. In addition, a cross-sectional area of the air duct of the first portion is gradually decreased along a direction from the first portion to the second portion; and/or a cross-sectional area of the air duct of the second portion is gradually decreased along a direction from the second portion to the first portion. 
     Further, the partition  13  is connected to a surface of the inner wall  101  facing the outer wall  102  and extends towards the outer wall  102 . The partition  13  includes a partition body  130 , a first guiding portion  131 , and a second guiding portion  132 . One end of the partition body  130  is connected to an end of the bottom wall  104  near the end plate  109 . The other end of the partition body  130  extends towards a middle of the top wall  103  to be close to a middle of the top wall  103 . The first guiding portion  131  includes a first sub-portion  131   a  and a second sub-portion  131   b . The first sub-portion  131   a  surrounds a periphery of the fan assembly  20  arranged near the end plate  109 . The second portion  131   b  is connected between the first portion  131   a  and the top wall  103 . The second guiding portion  132  is connected to the partition body  130  and surrounds a periphery of the fan assembly  20  near the connecting portion  14 . It shall be understood that, the partition body  130  is configured to divide the receiving space  105  into the two receiving sub-spaces  105   a  and  105   b . The first guiding portion  131  and the second guiding portion  132  are configured to match shapes of the fan blade assemblies  22  so as to guide the air and achieve a better air outlet effect. 
     Further, an end of the second guiding portion  132  away from the partition body  130  extends to reach the connecting portion  14 . Along a direction from the end plate  109  to the connecting portion  14 , a distance between the second guiding portion  132  and the bottom wall  103  is gradually reduced until the second guiding portion  132  is tangent to the bottom wall  103 , and then the distance between the second guiding portion  132  and the bottom wall  103  is gradually increased to a predetermined value and remains at the predetermined value. The predetermined value may be determined according to actual demands, for example, in some embodiments, the predetermined value may be a half of a distance between the top wall  103  and the bottom wall  104 . Such arrangement of the second guiding portion  132  allows the air duct to extend to reach the connecting portion  14 . In addition, some of the air outlets  107  are defined near the connecting portion  14 . In this way, a range of the air output from the neck fan  30  is larger, improving the cooling effect. 
     Further, the neck fan  30  further includes an electronic control assembly  15 . The electronic control assembly  15  includes a battery and a printed circuit board  151 . The second guiding portion  132  and the partition body  130  cooperatively define a receiving chamber  133  to receive at least part of the electronic control assembly  15 . It shall be understood, the electronic control assembly  15  are received in the receiving chamber  133 , preventing heat generated by the electronic control assembly  15  from entering the receiving sub-spaces  105   a  and  150   b , and therefore, the cooling effect may not be affected. In addition, such arrangement allows individual arrangement of heat dissipation and wiring of the electronic control assembly  15 , thereby improving the usage safety. 
     Further, the electronic control assembly  15  further includes a switch button  152  and a data port  153 . The outer wall  102  of the second portion  12  defines a first opening  102   a  corresponding to the switch button  152  and a second opening  102   b  corresponding to the data port  153 . The switch button  152  is mounted corresponding to the first opening  102   a  and connected to the printed circuit board  151 . The data port  153  is mounted corresponding to the second opening  102   b  and connected to the printed circuit board  151 . Such arrangement allows the user to operate the neck fan easily, improving user&#39;s experience. Furthermore, it shall be understood, in addition to the electronic control assembly  15 , structures and elements of the first portion  11  and the second portion  12  are symmetrically arranged to increase wearing comfort. 
     Further, the outer wall  102  includes a main plate  1021  and an auxiliary plate  1022 . A shape and a position of the auxiliary plate  1022  correspond to those of the partition  13 . The auxiliary plate  1021  is connected between the main plate  1021  and the partition  13 . It shall be understood that the auxiliary plate  1022  and the partition  13  cooperatively define the air duct of the fan assembly  20 , so as to achieve a better air guiding effect. 
     In another embodiment, as shown in  FIGS. 7 and 8 ,  FIG. 7  is a schematic view of a neck fan  30  according to an embodiment of the present disclosure, and  FIG. 8  is an explosive view of the neck fan  30  of  FIG. 7 . The neck fan  30  includes an arc-shaped shell  10  and at least four fan assemblies  20 . The at least four fan assemblies  20  are arranged inside the arc-shaped shell  10 . It shall be understood that, in the present embodiment, a neck fan having four fan assemblies  20  may be taken as an example for illustration. 
     The arc-shaped shell  10  may be hung around the neck of the user. The arc-shaped shell  10  includes a first portion  11  and a second portion  12 . The first portion  11  and the second portion  12  are arranged around two sides of the neck, such as a left side and a right side. Each of the first portion  11  and the second portion  12  includes a side wall that defines a receiving space  105 . Each of the first portion  11  and the second portion  12  defines air inlets  106  and air outlets  107  communicating with the receiving space  105 . 
     At least one partition  13  is received in the receiving space  105  to divide the receiving space  105  into at least two receiving sub-spaces  105   a  and  150   b . The at least two receiving sub-spaces  105   a  and  150   b  are arranged successively along an extension direction of the arc-shaped shell  10 . Each of the at least two receiving sub-spaces correspond to and communicate with some of the air inlets  106  and some of the air outlets  107 . Each of the fan assemblies  20  is received in one corresponding receiving sub-space. Each of the fan assemblies is configured to guide the air, which flows into the corresponding receiving sub-space through corresponding air inlets  106 , to flow to air outlets  107  corresponding to the receiving sub-space, allowing the air to be blown out through the corresponding air outlets  107 . The number of the air outlets  107  may be more than one. The more than one air outlets  107  may be distributed along the extension direction of the arc-shaped shell  10 . Sizes, shapes of the air outlets  107  and/or distances between every two adjacent air outlets  107  vary gradually along the extension direction of the arc-shaped shell  10 . 
     Compared to the neck fan in the art, in the neck fan  30  illustrated in the above-mentioned embodiments, the arc-shaped shell  10  includes the first portion  11  and the second portion  12 . The first portion  11  and the second portion  12  are configured to be around two opposite sides of the neck. Each of the first portion  11  and the second portion  12  defines the receiving space  105 , the air inlets  106 , and the air outlets  107 . The air inlets  106  and the air outlets  107  communicate with the receiving space  105 . Each receiving space  105  is divided into at least two receiving sub-spaces  105   a  and  105   b  by the partition  13 . Each of the fan assemblies  20  is arranged in one of the receiving sub-spaces and configured to guide the air at the air inlets  106  to flow to the air outlets  107  to be blown out. Since the fan assemblies  20  are received in the receiving space  105 , foreign matters, such as hair, may not be absorbed into the fan assemblies easily, allowing the neck fan to be used safely and conveniently. In the present embodiment, four receiving sub-spaces  105   a  and  105   b  are defined along the extension direction of the arc-shaped shell  10 , and four fan assemblies  20  may be arranged and received in four receiving sub-spaces respectively. Since a plurality of the receiving sub-spaces  105   a  and  105   b  are defined, a length of the air duct in each of the receiving sub-spaces may be relatively short. When the air is flowing in each of the receiving sub-spaces, a concentration of the air being output may be reduced, the user may be comfortable about the air output, wind noise may be reduced, and an air volume loss may be reduced. The applicant of the present disclosure finds that, the longer the air duct, the longer period of time that the air flows along the receiving sub-space, increasing the wind noise and the air volume loss. By dividing the receiving space  105  into the plurality of receiving sub-spaces  105   a  and  105   b , the wind noise and the air volume loss may be reduced significantly. 
     In detail, the side wall includes a first side wall  101 ′ configured to be close to the neck of the user and a second side wall  102  opposite to the first side wall  101 ′. The air inlets  106  are defined in the second side wall  102 , and the air outlets  107  are defined in a region of the first side wall  101 ′ adjacent to the second side wall  102  or defined in a region of the second side wall  102  adjacent to the first side wall  101 ′. In the present embodiment, the air outlets  107  are defined in the region of the first side wall  101 ′ adjacent to the second side wall  102  and are close to the user&#39;s head and face. 
     Further, in detail, a direction extending from the first portion  11  to the second portion  12  may be referred to as a first extension direction D 1 . The sizes of the more than one air outlets  107  defined in the first portion  11  are gradually reduced along the first extension direction D 1 . A direction extending from the second portion  12  to the first portion  11  is referred to as a second extension direction D 2 . The sizes of the more than one air outlets  107  defined in the second portion  12  are gradually reduced along the second extension direction D 2 . Furthermore, each of the air outlets  107  is a strip-shaped air outlet. An extension direction of the strip-shaped air inlet may be inclined in a preset angle relative to the extension direction of the arc-shaped shell  10 . The preset angle may be 90 degrees. It shall be understood that, by defining the air outlets  107  in the above extension direction, the air outlet of the neck fan  30  may be softer, and the user may be more comfortable, improving the user&#39;s experience. In particular, when the preset angle is 90 degrees, the air outlet efficiency of the air outlets  107  is improved. In some embodiments, the air outlets  107  may be at least one of petal-shaped and heart-shaped. It shall be understood that, both the petal-shaped air outlets  107  and the heart-shaped air outlets  107  may output the air uniformly and provides better appearance for the neck fan. 
     Further, each fan assembly  20  includes a driving shaft  21  and a fan blade assembly  22  mounted on the driving shaft  21 . The driving shaft  21  extends from the first side wall  101 ′ towards the second side wall  102 . In this way, a thickness of the arc-shaped shell  10  along a direction from the first side wall  101 ′ to the second side wall  102  may be reduced, such that the user may be comfortable when wearing the neck fan. 
     It shall be understood, the air inlets  106  are defined in the second side wall  102 , and the second side wall  102  faces outwardly (i.e., away from the user&#39;s neck) allowing the air to flow into the air inlets  106  easily, allowing the air to flow in smoothly. Such arrangement together with the driving shaft  21  extending along the direction from the first side wall  101 ′ to the second side wall  102  enables the fan blade assembly  22  to direct the air from the air inlets  106  to the air outlets  107 , thereby achieving a relatively high air guiding efficiency. Moreover, the air outlets  107  are defined at the first side wall  101 ′ close to the user&#39;s head and face, such that the air may be directed out towards the user&#39;s head and face, thereby achieving better cooling effect. 
     The first side wall  101 ′ defines a plurality of air inlets  108  corresponding to each fan assembly  20 . The fan assembly  20  can guide the air at the air inlets  108  to the air outlets  107 . Each of the plurality of air inlets  108  is arc shaped. The plurality of air inlets  108  corresponding to each fan assembly are arranged in a circular shape. It shall be understood, such arrangement provides a better appearance of the neck fan  30 , and prevents the foreign matters from entering the fan assembly  20 . Such arrangement together with shapes of the fan assemblies  20  achieves a better air guiding effect. 
     In an embodiment, the first side wall defines the plurality of air inlets  108 , and the second side wall defines the plurality of air inlets  106 . The first side wall faces the neck of the user, and the second side wall is connected to the first side wall and faces away from the neck. Further, at least one of a region of the first side wall close to the second side wall and a region of the second side wall close to the first side wall defines the plurality of air outlets  107 . In addition, the plurality of air outlets  107  are located between the plurality of air inlets  108  of the first side wall and the plurality of air inlets  106  of the second side wall along an extension direction of the driving shaft  21 . 
     Further, the first portion  11  has a connecting end  10   a  connected to the second portion  12  and a free end  10   b  away from the connecting end  10   a ; and the second portion  12  also has a connecting end  10   a  connected to the first portion  11  and a free end  10   b  away from the connecting end  10   a . Sizes of the air outlets  107  corresponding to the fan assembly  20  adjacent to the connecting end  10   a  are less than those of the air outlets  107  corresponding to the fan assembly  20  adjacent to the free end  10   b . An outer diameter of the fan blade assembly  22  adjacent to the connecting end  10   a  is less than that of the fan blade assembly  22  adjacent to the free end  10   b . It shall be understood, the sizes of the air inlets  106  and the diameter of the fan blade assembly  22  enables a size of the arc-shaped shell  10  to be reduced gradually along a direction from the free end  10   b  to the connecting end  10   a , such that the shape of the neck fan may fit a curve of the neck more appropriately, increasing wearing comfort. 
     In the present embodiment, each of the first portion  11  and the second portion  12  includes a cover  16 . The cover  16  is disposed on a side of the second side wall  102  away from the first side wall  101 ′ and corresponds to (such as covers) the air inlets  106 . A gap  161  communicated with the air inlets  106  is defined between an edge of the cover  16  and the second side wall  102  to allow air to flow into the air inlets  106 . 
     Further, the second side wall  102  includes a main body  102   c  and defines a recess  102   d . A wall of the recess  102   d  is connected to the main body  102   c . In other words, the side of the second side wall  102  away from the first side wall  101 ′ is recessed inwardly towards the first side wall  101 ′ to define the recess  102   d . The air inlets  106  are defined at the recess  102   d , such as defined in the bottom wall of the recess  102   d . The cover  16  covers the recess  102   d . The cover  16  is partially connected to the main body  102   c  connected to wall of the recess  102   d  to define the gap  161 . It shall be understood, the cover  16  covers the air inlets  106 , and air enters through the gap  161  and the air inlets  106 . In this way, a better appearance is provided, and the foreign matters may be prevented from entering the fan assembly  20 , increasing the usage safety. Defining the recess  102   d  further reduces an overall size of the neck fan  30  and provides the appearance aesthetics. 
     Further, the cover  16  includes a cover body  162  and a first mounting portion  163  arranged at a side of the cover body  162  adjacent to the second side wall  102 . A side of the second side wall  102  close to the cover  16  is arranged with a second mounting portion  102   e . In detail, the second mounting portion  102   e  may be arranged on the wall of the recess  102   d  and is located between the plurality of air inlets  106 . 
     Further, the cover  16  further includes the cover body  162  and the first mounting portion  163  arranged on the cover body  162 . The second mounting portion  102   e  is arranged on the second side wall  102  and is engaged with the first mounting portion  163 . Engagement between the second mounting portion  102   e  and the first mounting portion  163  enables the cover  16  to be mounted (such as detachably or movably mounted) on the side of the second side wall  102  away from the first side wall  101 ′. It shall be understood, engagement between the first mounting portion  163  and the second mounting portion  102   e  enables the cover  16  to be detachably or movably mounted onto the second side wall  102 , allowing the neck fan to be used or disassembled easily. 
     Further, the first mounting portion  163  and the second mounting portion  102   e  may be engaged in a first mounting state or in a second mounting state. In the first mounting state, the gap  161  is defined between the edge of the cover  16  and the second side wall  102 . In the second mounting state, the edge of the cover  16  abuts against the second side wall  102  so as to cover the air inlets  106 . It shall be understood, the first mounting portion  163  and the second mounting portion  102   e  may be engaged in the first mounting state or in the second mounting state. Therefore, in the first mounting state, the air can enter the fan assembly through the gap  161  and the air inlets  106 ; and in the second mounting state, the gap  161  and the air inlets  106  are covered, and dust may be prevented from entering the arc-shaped shell through the air inlets  106  when the neck fan  30  is not in use, achieving the dustproof effect. 
     It shall be understood, the first mounting state and the second mounting state may be switched from one to the other. In some embodiments, elastic fasteners may be configured, serving as the first mounting portion and the second mounting portion. In this way, the first mounting state and the second mounting state may be switched by pressing the cover  16  along a direction facing the second side wall  102 . For example, a first press is made to switch from the first mounting state to the second mounting state, and a next press is made to switch from the second mounting state to the first mounting state. There are various structures for implementing the above-mentioned press switch control, which will not be described specifically hereinafter. 
     In the present embodiment, the first mounting portion  163  may be a mounting shaft connected to the cover body  162 , and the second mounting portion  102   e  may be a mounting hole corresponding to the mounting shaft. In other embodiments, the first mounting portion  163  may be a mounting hole defined in the cover body  162 , and the second mounting portion  102   e  may be a mounting shaft corresponding to the mounting hole. It shall be understood, the mounting shaft may be received in the mounting hole to engage the cover  16  to the second side wall  102 , achieving an easy mounting operation. 
     In the present embodiment, the partition  13  includes a partition body  131  and a guiding portion  132 . A shape of the partition body  131  at least partially fits to a shape of the fan assembly  20 , and the partition body  131  surrounds a periphery of the fan assembly  20 . The guiding portion  132  is connected to the partition body  131 . The guiding portion  132  and the side wall cooperatively define the air duct communicated to the air outlets  107 . It shall be understood that by adapting the partition part  131  to the shape of the fan assembly  20  and by configuring the guiding portion  132  and the side wall to cooperatively define the air duct  17  communicated to the air outlets  107 , a better air guiding effect may be achieved, and an air inlet and outlet efficiency may be improved. 
     Further, for each of the first portion  11  and the second portion  12 , the guiding portion  132  includes a first guiding sub-portion  132   a  located between two fan assemblies  20  and a second guiding sub-portion  132   b  arranged at a side of one of the two fan assemblies  20  away from the other of the two fan assemblies. The second guiding sub-part  132   b  extends from one of the first portion  11  and the second portion  12  to the other of the first portion  11  and the second portion  12 . A side of the second guiding sub-portion  132   b  and the side wall cooperatively define an accommodating space  18 . The neck fan  30  further includes an electronic control assembly  15 . The electronic control assembly  15  includes a battery and a printed circuit board. The accommodating space  18  is defined to receive at least one of the battery and the printed circuit board. It shall be understood, by receiving the electronic control assembly  15  in the accommodating space  18 , configuration of the neck fan  30  may be effectively balanced, providing wearing comfort for the user. In addition, the fan blade assembly  20  may be a turbine fan blade assembly. It shall be understood that the turbine fan blade assembly may achieve lower noise and higher safety. 
     In an embodiment, as shown in  FIG. 4 , the present disclosure provides a turbine blade assembly  22  for a neck fan. The turbine blade assembly  22  has a first side and a second side opposite to the first side. The turbine blade assembly  22  includes a first side blade disposed at the first side, a second side blade disposed at the second side, and a separation plate disposed between the first side and the second side. The first side defines a first inlet window, and the second side defines a second inlet window. The first inlet window and the second inlet window are defined to allow air to flow in from an outside of the neck fan. A bottom wall of the first inlet window is recessed from a plane where the first side blade is disposed. A bottom wall of the second inlet window is recessed from a plane where the second side blade is disposed. 
     The above description only describes embodiments of the present disclosure, and is not intended to limit the present disclosure, various modifications and changes can be made to the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present disclosure are intended to be included within the scope of the present disclosure.