Wind turbine cooling system and wind turbine

Abstract

The present invention relates to the field of wind power generation technology, and in particular, to a wind turbine cooling system and a wind turbine. The wind turbine cooling system includes an air guide structure and a throttling structure; the air guide structure is located between the hub inner cavity and the blade inner cavity, and the air guide structure includes a first air guide channel and a second air guide channel; the first air guide channel is used to guide the airflow in the hub inner cavity to flow toward the blade inner cavity, and the second air guide channel is used to guide the airflow in the blade inner cavity to flow toward the hub inner cavity; the throttling structure is connected to the first air guide channel and is used to reduce the pressure of the airflow flowing from the hub inner cavity to the blade inner cavity; or, the throttling structure is connected to the second air guide channel and is used to reduce the pressure of the airflow flowing from the blade inner cavity to the hub inner cavity. The wind turbine cooling system can form a circulating airflow between the hub inner cavity and the blade inner cavity based on the throttling effect, thereby reducing the temperature of the wind turbine, thereby ensuring the safe operation of the wind turbine.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation, and in particular to a wind turbine cooling system and a wind turbine. Background Art

[0002] The current wind turbine impeller system has gradually adopted a design without hub cover protection. The hub casting serves as the outer shell of the system, and the pitch system, safety system and other related electronic equipment are integrated inside. Since the hub is mainly used as a transmission component for the impeller torque, the internal space is limited, and the internally integrated electronic control system has the highest level of safe operation for the unit. It is difficult for the impeller system to form a recyclable natural air duct with the outside world. Therefore, the blade cavity and the hub cavity form a closed environment. When the unit is in operation, the heat generated by the electrical system is difficult to discharge. At the same time, the casting itself is a heat recipient, affected by the external ambient temperature and light, which aggravates the increase in the closed environment temperature, and seriously reduces the reliability and life of the electrical system. Summary of the Invention

[0003] The objects of the present invention include, for example, providing a wind turbine cooling system and a wind turbine, which can form a circulating airflow between the hub cavity and the blade cavity based on the throttling effect, thereby reducing the temperature of the wind turbine, thereby ensuring the safe operation of the wind turbine.

[0004] The embodiments of the present invention can be implemented as follows:

[0005] In a first aspect, the present invention provides a wind turbine cooling system, the wind turbine cooling system comprising an air guide structure and a throttling structure;

[0006] The air guide structure is located between the hub inner cavity and the blade inner cavity, and the air guide structure includes a first air guide channel and a second air guide channel; the first air guide channel is used to guide the airflow in the hub inner cavity to flow toward the blade inner cavity, and the second air guide channel is used to guide the airflow in the blade inner cavity to flow toward the hub inner cavity;

[0007] The throttling structure is connected to the first air guide channel and is used to reduce the pressure of the airflow flowing from the hub inner cavity to the blade inner cavity; or, the throttling structure is connected to the second air guide channel and is used to reduce the pressure of the airflow flowing from the blade inner cavity to the hub inner cavity.

[0008] In an optional embodiment, the throttling structure includes a first throttling unit and a second throttling unit;

[0009] The first throttling unit is in communication with the first air guide channel and is used to reduce the pressure of the airflow flowing from the hub inner cavity to the blade inner cavity;

[0010] The second throttling unit is communicated with the second air guiding channel and is used to reduce the pressure of the airflow flowing from the inner cavity of the blade to the inner cavity of the hub.

[0011] In an optional embodiment, the first throttling unit includes a conical air cylinder, the conical air cylinder is connected to the first air guide channel, and the inner diameter of the conical air cylinder gradually decreases from the inner cavity of the hub to the inner cavity of the blade;

[0012] The second throttling unit includes an air outlet tube, one end of the air outlet tube is connected to the second air guide channel, and the other end of the air outlet tube is connected to the inner cavity of the hub, and the opening area of ​​the end of the air outlet tube connected to the inner cavity of the hub is smaller than the opening area of ​​the end of the air outlet tube connected to the second air guide channel.

[0013] In an optional embodiment, the conical air cylinder is accommodated in the inner cavity of the blade and is communicated with an end of the first air guide channel close to the inner cavity of the blade;

[0014] The air outlet tube is accommodated in the inner cavity of the wheel hub and is communicated with one end of the second air guide channel close to the inner cavity of the wheel hub.

[0015] In an optional embodiment, the wind turbine cooling system further includes a blade support plate connected to the wind turbine blade and separating the hub inner cavity and the blade inner cavity;

[0016] The first air guiding channel and the second air guiding channel are both opened on the blade supporting plate.

[0017] In an optional embodiment, the throttling structure further includes a centrifugal fan and a fan mounting frame;

[0018] The fan mounting frame is connected to the blade support plate, and the centrifugal fan is connected to the fan mounting frame;

[0019] The centrifugal fan is used to guide the airflow in the inner cavity of the hub to flow toward the inner cavity of the blade, or to guide the airflow in the inner cavity of the blade to flow toward the inner cavity of the hub.

[0020] In an optional embodiment, the centrifugal fan is used to guide the airflow in the hub cavity to flow toward the blade cavity, and the air outlet of the centrifugal fan is opposite to one end of the first air guide channel connected to the hub cavity.

[0021] In an optional embodiment, the centrifugal fan is accommodated in the inner cavity of the hub.

[0022] In an optional embodiment, one end of the air outlet tube communicating with the inner cavity of the hub faces the air inlet of the centrifugal fan.

[0023] In a second aspect, the present invention provides a wind turbine generator set, comprising a wind turbine hub, wind turbine blades, and the above-mentioned wind turbine generator set cooling system;

[0024] The fan blades are connected to the fan hub, and the fan hub has a hub inner cavity, and the fan blades have a blade inner cavity; the air guide structure is located between the hub inner cavity and the blade inner cavity.

[0025] The beneficial effects of the embodiments of the present invention include:

[0026] The wind turbine cooling system includes an air guide structure and a throttling structure. The air guide structure is located between the hub inner cavity and the blade inner cavity, and includes a first air guide channel and a second air guide channel. The first air guide channel is used to guide the airflow in the hub inner cavity to flow toward the blade inner cavity, and the second air guide channel is used to guide the airflow in the blade inner cavity to flow toward the hub inner cavity. The throttling structure is connected to the first air guide channel and is used to reduce the pressure of the airflow flowing from the hub inner cavity to the blade inner cavity. Alternatively, the throttling structure is connected to the second air guide channel and is used to reduce the pressure of the airflow flowing from the blade inner cavity to the hub inner cavity. Based on the throttling effect, the wind turbine cooling system can form a circulating airflow between the hub inner cavity and the blade inner cavity, thereby reducing the temperature of the wind turbine, thereby ensuring the safe operation of the wind turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 A schematic structural diagram of a wind turbine generator system according to an embodiment of the present invention;

[0029] Figure 2 for Figure 1 A partial schematic diagram of the middle part;

[0030] Figure 3 is a cross-sectional view of a blade according to an embodiment of the present invention;

[0031] Figure 4 Schematic diagram of a portion of a blade in an embodiment of the present invention.

[0032] Icons: 100-wind turbine; 110-fan hub; 120-fan blades; 111-hub inner cavity; 121-blade inner cavity; 200-wind turbine cooling system; 210-air guide structure; 220-throttling structure; 211-first air guide channel; 212-second air guide channel; 221-first throttling unit; 222-second throttling unit; 223-conical air duct; 224-air outlet duct; 230-blade support plate; 240-centrifugal fan; 250-fan mounting frame. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0035] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0036] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the invention is usually placed when in use. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.

[0037] In addition, the terms "first", "second", etc., if used, are merely used to distinguish and describe, and should not be understood as indicating or implying relative importance.

[0038] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.

[0039] The impeller system of the current wind turbine 100 has gradually adopted a design without hub cover protection. The hub casting serves as the system shell, and the pitch system and safety system and other related electronic equipment are integrated inside. Since the hub is mainly used as a transmission component for the impeller torque, the internal space is limited, and the internally integrated electronic control system has the highest level of safety for the unit operation. It is difficult for the impeller system to consider forming a recyclable natural air duct with the outside world. Based on this, the existing impeller system without hub cover structure mainly reduces the ambient temperature in the hub casting cavity from two aspects. On the one hand, it starts from the unit control and reduces the unit operating power, thereby directly reducing the heat generated by the operation of the electronic control system in the hub casting. On the other hand, a blower device is added at the manhole position.

[0040] If the control method is used, the power generation efficiency of the unit will be directly reduced, which will cause significant losses to the owner. From a hardware perspective, the enlarged air blower will make it difficult to form a natural circulation system in the hub, resulting in excessive internal pressure. At the same time, external moisture and dust will enter the hub and be difficult to clean. They will easily be absorbed by the control cabinet, resulting in poor heat dissipation of the electrical system.

[0041] For the reasons above, please refer to Figures 1-4 The present invention provides a wind turbine cooling system 200, which can make full use of the abundant space inside the blade without introducing natural wind from the external environment. Considering that the blade cavity 121 and the hub cavity 111 form a completely closed airflow environment, based on the throttling effect, the ambient temperature inside the hub is reduced through heat transfer between the hub cavity 111 and the blade cavity 121.

[0042] It should be noted that the throttling effect is also called the Joule-Thomson effect, which refers to the thermodynamic process in which the pressure is reduced due to the sudden reduction of the channel cross-section (such as orifice plates, valves, etc.) when the fluid flows.

[0043] For details, please refer to Figures 1-4 , this embodiment provides a wind turbine 100, the wind turbine 100 including a wind turbine hub 110, wind turbine blades 120 and a wind turbine cooling system 200;

[0044] The fan blades 120 are connected to the fan hub 110 , and the fan hub 110 has a hub inner cavity 111 , and the fan blades 120 have a blade inner cavity 121 ;

[0045] The wind turbine cooling system 200 includes an air guide structure 210 and a throttling structure 220;

[0046] The air guide structure 210 is located between the hub inner cavity 111 and the blade inner cavity 121 and includes a first air guide channel 211 and a second air guide channel 212. The first air guide channel 211 is used to guide the airflow in the hub inner cavity 111 to flow toward the blade inner cavity 121, and the second air guide channel 212 is used to guide the airflow in the blade inner cavity 121 to flow toward the hub inner cavity 111.

[0047] The throttling structure 220 is connected to the first air guide channel 211 and is used to reduce the pressure of the airflow flowing from the hub inner cavity 111 to the blade inner cavity 121; or, the throttling structure 220 is connected to the second air guide channel 212 and is used to reduce the pressure of the airflow flowing from the blade inner cavity 121 to the hub inner cavity 111.

[0048] In summary, please refer to Figures 1-4 , the working principle of the wind turbine 100 is:

[0049] During the operation of the wind turbine generator set 100, its blades are connected to the hub, and the blade cavity 121 and the hub cavity 111 are connected through the wind guide structure 210. Under the action of the wind guide structure 210, the airflow can circulate in the hub cavity 111 and the blade cavity 121. In addition, during the airflow circulation, the throttling structure 220 is used to reduce the pressure of the airflow flowing from the hub cavity 111 to the blade cavity 121 or reduce the pressure of the airflow flowing from the blade cavity 121 to the hub cavity 111. Under the action of the throttling structure 220, that is, the circulating airflow can form a throttling effect, and then the temperature of the airflow can be reduced by throttling less than 1 / 4, thereby cooling the airflow in the hub cavity 111, thereby ensuring the normal operation of the electronic control system integrated in the hub cavity 111, and thus ensuring the safe operation of the wind turbine generator set 100.

[0050] Moreover, based on the above content, it can be known that during the operation of the wind turbine 100, since the airflow circulates in the hub cavity 111 and the blade cavity 121, and forms a throttling effect to cool down, during the cooling process, the hub cavity 111 and the blade cavity 121 can be relatively isolated from the outside world, that is, a closed airflow environment relative to the outside world is formed, thereby preventing external moisture and dust from entering the hub, thereby affecting the normal operation of the wind turbine 100.

[0051] It should be noted that when the blades and hub are provided, the blades are connected to the hub via a pitch bearing, and the blades are connected to the inner ring of the pitch bearing, while the outer ring of the pitch bearing is connected to the hub, thereby transmitting the torque generated by the blades to the hub. Two blade inner webs are located inside the blades, supporting the entire internal cavity of the blades and primarily bearing the various bending moments generated by the blades. Therefore, the blade inner webs separate the blades to form a blade inner cavity 121. The blade inner cavity 121 and the hub inner cavity 111 form a sealed environment within the entire impeller system. All electrical control systems and related electronic components of the impeller system are installed in the hub inner cavity 111. Furthermore, the wind turbine cooling system 200 also includes a blade support plate 230 connected to the wind turbine blades 120 and separating the hub inner cavity 111 from the blade inner cavity 121. Both the first air guide channel 211 and the second air guide channel 212 are provided in the blade support plate 230.

[0052] For further information, please refer to Figures 1-4In this embodiment, when the throttling structure 220 is set, the throttling structure 220 includes a first throttling unit 221 and a second throttling unit 222; the first throttling unit 221 is connected to the first air guide channel 211, and is used to reduce the pressure of the airflow flowing from the hub inner cavity 111 to the blade inner cavity 121; the second throttling unit 222 is connected to the second air guide channel 212, and is used to reduce the pressure of the airflow flowing from the blade inner cavity 121 to the hub inner cavity 111.

[0053] Therefore, through such an arrangement, a throttling effect can be formed when the airflow flows from the hub inner cavity 111 to the blade inner cavity 121. At the same time, a throttling effect can be formed when the airflow flows from the blade inner cavity 121 to the hub inner cavity 111; that is, a two-stage throttling effect can be formed by the first throttling unit 221 and the second throttling unit 222, so that the temperature of the airflow circulating in the hub inner cavity 111 and the blade inner cavity 121 can be reduced through such an arrangement.

[0054] For further information, please refer to Figures 1-4 In this embodiment, when the first throttling unit 221 is provided, the first throttling unit 221 includes a tapered air tube 223, which is connected to the first air guide channel 211. The inner diameter of the tapered air tube 223 gradually decreases from the hub inner cavity 111 to the blade inner cavity 121. When the second throttling unit 222 is provided, the second throttling unit 222 includes an air outlet tube 224, one end of which is connected to the second air guide channel 212, and the other end of which is connected to the hub inner cavity 111. The opening area of ​​the end of the air outlet tube 224 connected to the hub inner cavity 111 is smaller than the opening area of ​​the end of the air outlet tube 224 connected to the second air guide channel 212. Therefore, through this arrangement, a two-stage throttling effect can be formed during the airflow circulation process.

[0055] Among them, the conical air duct 223 is accommodated in the blade cavity 121 and is connected to one end of the first air guide channel 211 close to the blade cavity 121; the air outlet duct 224 is accommodated in the hub cavity 111 and is connected to one end of the second air guide channel 212 close to the hub cavity 111.

[0056] In order to allow the air flow to circulate, the throttling structure 220 also includes a centrifugal fan 240 and a fan mounting frame 250; the fan mounting frame 250 is connected to the blade support plate 230, and the centrifugal fan 240 is connected to the fan mounting frame 250; the centrifugal fan 240 is used to guide the air flow in the hub cavity 111 to flow to the blade cavity 121, or to guide the air flow in the blade cavity 121 to flow to the hub cavity 111.

[0057] In this embodiment, the centrifugal fan 240 is used to guide the airflow in the hub cavity 111 to flow toward the blade cavity 121. The air outlet of the centrifugal fan 240 is opposite to one end of the first air guide channel 211 connected to the hub cavity 111, and the centrifugal fan 240 is accommodated in the hub cavity 111.

[0058] Since the air outlet 224 and the centrifugal fan 240 are both accommodated in the hub inner cavity 111 , when the air outlet 224 is arranged, the end of the air outlet 224 communicating with the hub inner cavity 111 is aligned with the air inlet of the centrifugal fan 240 .

[0059] In summary, please refer to Figures 1-4 Since the space inside the hub is small, the temperature in the hub cavity 111 will rise under the irradiation of external ultraviolet rays or sunlight. At the same time, the heat generated by the operation of the internal electronic components will greatly reduce the service life and reliability of the components. Therefore, by setting the wind turbine cooling system 200 mentioned above in the wind turbine 100, self-circulating air convection can be established in the hub cavity 111 and the blade cavity 121 to achieve heat transfer, which makes full use of the existing blade cavity 121, and as the blade becomes longer, the blade cavity 121 extends longer. When the blade is rotating, the effect on the internal airflow temperature is small. Therefore, by opening a first air guide channel 211 and a second air guide channel 212 on the blade support plate 230 at the root of the blade, and setting a throttling structure 220 at its corresponding position, the airflow in the blade cavity 121 can be transferred from The air outlet duct 224 guides the air to the air inlet of the centrifugal fan 240, and flows back to the blade inner cavity 121 through the conical air duct 223, forming a self-circulation of the air flow; and after the air flow in the blade inner cavity 121 enters the hub inner cavity 111 through the air outlet duct 224, it can be mixed with the air flow in the hub inner cavity 111, and after mixing, it flows into the conical air duct 223. Since the temperature of the self-circulating air flow is lower than the temperature of the air flow in the hub inner cavity 111, the temperature transfer of the air flow is realized during the air flow circulation process. At the same time, part of the hot air flow in the hub inner cavity 111 can also be directly introduced into the blade inner cavity 121 by the centrifugal fan 240, and then mixed with the air flow introduced into the hub inner cavity 111 from the blade inner cavity 121 in the conical air duct 223, thereby also reducing the temperature; thereby, it plays a role in taking away the heat in the hub inner cavity 111 and reducing the temperature in the hub inner cavity 111.

[0060] Specifically, based on the throttling effect of compressed air and the temperature reduction phenomenon caused by the positive Joule-Thomson theory, under the action of the conical air duct 223 and the air outlet duct 224, two-stage air throttling can be formed at the first air guide channel 211 and the second air guide channel 212, thereby reducing the temperature of the circulating air flow and forming heat transfer with the hub inner cavity 111.

[0061] When the conical air duct 223 is provided, its height is preferably such as to interfere with the centrifugal fan 240 so as to form a stable airflow inside the conical air duct 223. Furthermore, under the action of the centrifugal fan 240, the airflow is compressed and enters the conical air duct 223. After being mixed and formed into a stable airflow inside the conical air duct 223, the airflow is introduced into the blade cavity 121 through the conical tube to form the first low-temperature airflow.

[0062] When the air outlet 224 is set, since one end of the air outlet 224 connected to the hub inner cavity 111 is facing the air inlet of the centrifugal fan 240, under the action of the centrifugal fan 240, the air flow introduced into the hub inner cavity 111 by the air outlet 224 or entering the air inlet of the centrifugal fan 240 is compressed to form a second low-temperature air flow, thereby forming a self-circulating cooling air flow to fully transfer heat with the hub inner cavity 111.

[0063] Therefore, the wind turbine 100 makes full use of the abundant space inside the blade, considers that the blade cavity 121 and the hub cavity 111 form a completely closed airflow environment, and based on the throttling effect, forms a secondary throttling cooling at the root of the blade, forming better airflow cooling, and forms heat convection with the self-circulating cold airflow in the blade cavity 121 and the airflow in the hub cavity 111, thereby reducing the temperature inside the hub. Moreover, in the cooling process, there is no need to introduce natural wind from the external environment, which isolates external dust, water vapor and other substances from entering the hub, thereby protecting the safe and reliable operation of the electronic control system in the hub.

[0064] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A wind turbine cooling system, characterized in that: The wind turbine cooling system includes an air guide structure and a throttling structure; The air guide structure is located between the hub inner cavity and the blade inner cavity, and the air guide structure includes a first air guide channel and a second air guide channel; the first air guide channel is used to guide the airflow in the hub inner cavity to flow toward the blade inner cavity, and the second air guide channel is used to guide the airflow in the blade inner cavity to flow toward the hub inner cavity; The throttling structure is in communication with the first air guide channel and is used to reduce the pressure of the airflow flowing from the hub inner cavity to the blade inner cavity; or the throttling structure is in communication with the second air guide channel and is used to reduce the pressure of the airflow flowing from the blade inner cavity to the hub inner cavity; The throttling structure includes a first throttling unit and a second throttling unit; The first throttling unit is in communication with the first air guide channel and is used to reduce the pressure of the airflow flowing from the hub inner cavity to the blade inner cavity; The second throttling unit is in communication with the second air guide channel and is used to reduce the pressure of the airflow flowing from the inner cavity of the blade to the inner cavity of the hub; The first throttling unit includes a conical air cylinder, the conical air cylinder is communicated with the first air guide channel, and the inner diameter of the conical air cylinder gradually decreases from the inner cavity of the hub to the inner cavity of the blade; The second throttling unit includes an air outlet tube, one end of the air outlet tube is connected to the second air guide channel, and the other end of the air outlet tube is connected to the inner cavity of the hub, and the opening area of ​​the end of the air outlet tube connected to the inner cavity of the hub is smaller than the opening area of ​​the end of the air outlet tube connected to the second air guide channel.

2. The wind turbine cooling system according to claim 1, characterized in that: The conical air cylinder is accommodated in the inner cavity of the blade and is communicated with one end of the first air guide channel close to the inner cavity of the blade; The air outlet tube is accommodated in the inner cavity of the wheel hub and is communicated with one end of the second air guide channel close to the inner cavity of the wheel hub.

3. The wind turbine cooling system according to claim 2, characterized in that: The wind turbine cooling system further includes a blade support plate connected to the fan blade and separating the hub inner cavity and the blade inner cavity; The first air guiding channel and the second air guiding channel are both opened on the blade supporting plate.

4. The wind turbine cooling system according to claim 3, characterized in that: The throttling structure also includes a centrifugal fan and a fan mounting frame; The fan mounting frame is connected to the blade support plate, and the centrifugal fan is connected to the fan mounting frame; The centrifugal fan is used to guide the airflow in the inner cavity of the hub to flow toward the inner cavity of the blade, or to guide the airflow in the inner cavity of the blade to flow toward the inner cavity of the hub.

5. The wind turbine cooling system according to claim 4, characterized in that: The centrifugal fan is used to guide the airflow in the hub inner cavity to flow toward the blade inner cavity, and the air outlet of the centrifugal fan is directly opposite to one end of the first air guide channel connected to the hub inner cavity.

6. The wind turbine cooling system according to claim 5, characterized in that: The centrifugal fan is accommodated in the inner cavity of the hub.

7. The wind turbine cooling system according to claim 6, characterized in that: One end of the air outlet tube communicating with the inner cavity of the hub is directly opposite to the air inlet of the centrifugal fan.

8. A wind turbine generator set, characterized in that: The wind turbine generator set comprises a wind turbine hub, wind turbine blades, and a wind turbine generator set cooling system according to any one of claims 1 to 7; The fan blades are connected to the fan hub, and the fan hub has a hub inner cavity, and the fan blades have a blade inner cavity; the air guide structure is located between the hub inner cavity and the blade inner cavity.

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