WO2023020200A1

WO2023020200A1 - Fan base, air duct assembly and cooking appliance

Info

Publication number: WO2023020200A1
Application number: PCT/CN2022/107399
Authority: WO
Inventors: 胡杰; 张乐东; 刘存
Original assignee: 广东美的厨房电器制造有限公司; 美的集团股份有限公司
Priority date: 2021-08-18
Filing date: 2022-07-22
Publication date: 2023-02-23
Also published as: CN113543608A; CN113543608B

Abstract

Disclosed are a fan base, an air duct assembly and a cooking appliance. The air duct assembly (300) comprises a fan base (310) and a blower (320). The fan base (310) has a base body, a blower cavity (312) being provided at one side of the base body, a first air channel (315) in communication with the blower cavity (312) being provided at one end of the base body, and a second air channel (316) in communication with the wind wheel cavity (312) being provided at the other end of the base body, the second air channel (316) having at least two output ports (3161). A mounting cavity (311) is disposed at the other side of the base body, the mounting cavity (311) being in communication with at least one output port (3161). A through hole (314) is disposed at the bottom of the blower cavity (312), a motor support (313) being disposed in the through hole (314). The blower (320) is disposed in the blower cavity (312), the blower (320) being connected to a motor (330) fixed to the motor support (313).

Description

Fan base, air duct assembly and cooking utensils

Cross References to Related Applications

This application claims the priority of the Chinese patent application with application number 202110950411.7 and titled "Fan Base, Air Duct Assembly and Cooking Appliance" filed on August 18, 2021, the entire contents of which are incorporated in this application by reference.

technical field

The invention relates to the technical field of microwave ovens, in particular to a fan seat, an air duct assembly and a cooking utensil.

Background technique

In related technologies, cooking utensils, such as micro-steamers and microwave ovens, have multiple heat-generating components, and the fan assembly for cooling microwave ovens can only dissipate heat for a single component, so the cooling is weak and the heat dissipation efficiency is low. Usually, multiple groups of fan assemblies are required to cope with the heat dissipation requirements of multiple components, resulting in a complex structure and high manufacturing cost of the microwave oven.

Contents of the invention

The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, an embodiment of the present invention proposes a fan seat, which can simultaneously dissipate heat from multiple components and improve heat dissipation efficiency.

The embodiment of the present invention also proposes an air duct assembly including the above-mentioned fan base.

Embodiments of the present invention also provide a cooking appliance including the above-mentioned air duct assembly.

The fan seat according to the embodiment of the first aspect of the present invention includes a seat body, the seat body is provided with a wind wheel chamber, and one end of the seat body is provided with a first air duct communicating with the wind wheel chamber, and the seat body The other end of the other end is provided with a second air duct communicating with the wind wheel chamber, and the second air duct has at least two output ports; the motor bracket is arranged in the through hole at the bottom of the wind wheel chamber.

According to the fan seat of the embodiment of the first aspect of the present invention, it has at least the following beneficial effects: the cooling air flow is output from the wind wheel chamber to the first air duct and the second air duct, the first air duct can dissipate heat to at least one part of the microwave oven, and The second air duct has at least two output ports capable of dissipating heat from at least two components of the microwave oven, has multiple outputs, and can simultaneously dissipate heat from multiple components, thereby improving heat dissipation efficiency, reducing the number of fans, and helping to simplify the structure of the cooking appliance , to reduce manufacturing costs.

According to some embodiments of the first aspect of the present invention, the seat body is provided with a first deflector located in the first air passage, and the first deflector divides the first air passage into two passages .

According to some embodiments of the first aspect of the present invention, the seat body is provided with a second deflector located in the second air passage, and the number of the second deflectors is two and separates the second air passage for three channels.

According to some embodiments of the first aspect of the present invention, the wind wheel cavity is located on one side of the base body, and an installation cavity is provided on the other side of the base body, and the installation cavity communicates with at least one of the output ports.

According to the second aspect of the present invention, the air duct assembly includes a fan base, the fan base has a base body, one side of the base body is provided with a wind wheel cavity, and one end of the base body is provided with a The first air duct of the wheel chamber, the other end of the base body is provided with a second air duct communicating with the wind wheel chamber, the second air duct has at least two output ports, the other side of the base body An installation cavity is provided, and the installation cavity communicates with at least one of the output ports, and the bottom of the wind wheel cavity is provided with a through hole, and a motor bracket is arranged in the through hole; a wind wheel is arranged in the wind wheel cavity, The wind wheel is connected with a motor fixed to the motor bracket.

The air duct assembly according to the second embodiment of the present invention has at least the following beneficial effects: the motor drives the wind wheel to rotate to generate heat-dissipating airflow, the heat-dissipating airflow is output from the first air duct and the second air duct, and the heat dissipation output from the first air duct The air flow can dissipate heat to at least one component of the microwave oven, and the second air duct has at least two output ports capable of dissipating heat to at least two components of the microwave oven. Multiple components perform heat dissipation, improve heat dissipation efficiency, reduce the number of fans, help simplify the structure of the cooking appliance, and reduce manufacturing costs.

According to some embodiments of the second aspect of the present invention, the seat body is provided with a second deflector located in the second air passage, and the number of the second deflectors is two and separates the second air passage It is the first air guide channel, the second air guide channel and the third air guide channel, the fan seat is connected with the first air guide cover and the third air guide cover, and the first air guide channel communicates with the first air guide channel. The wind cover, the second air guide channel communicates with the installation cavity, and the third air guide channel communicates with the third air guide cover.

According to some embodiments of the second aspect of the present invention, the fan base is connected with a second air guide cover, and a gap communicating with the second air guide cover is provided on the side wall of the installation cavity.

According to some embodiments of the second aspect of the present invention, the fan base is connected with a fourth air guide cover, the fourth air guide cover communicates with the first air duct, and the interior of the fourth air guide cover is provided with a reverse Transformer installation position.

The cooking appliance according to the embodiment of the third aspect of the present invention includes the air duct assembly as described in the embodiment of the second aspect, and has all the technical effects of the air duct assembly, which will not be repeated here.

According to some embodiments of the third aspect of the present invention, the cooking appliance further includes a bottom plate, the bottom plate covers the air duct assembly, and the bottom plate is provided with a plurality of air inlet holes.

Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

Additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments when taken in conjunction with the following drawings, in which:

Fig. 1 is a first structural schematic diagram of the fan seat of the embodiment of the first aspect of the present invention;

Fig. 2 is a second structural schematic diagram of the fan seat of the first embodiment of the present invention;

Fig. 3 is a schematic structural view of the fan assembly of the second embodiment of the present invention

Fig. 4 is a schematic structural diagram of an air duct assembly according to a second embodiment of the present invention;

Fig. 5 is an exploded schematic diagram 1 of the air duct assembly according to the second embodiment of the present invention;

Fig. 6 is an exploded schematic diagram II of the air duct assembly according to the second embodiment of the present invention;

Fig. 7 is an exploded schematic diagram of a cooking appliance according to a third embodiment of the present invention;

Fig. 8 is a partial exploded schematic diagram 1 of the cooking utensil in Fig. 7;

Fig. 9 is a partial exploded schematic diagram II of the cooking utensil in Fig. 7;

Fig. 10 is a schematic diagram of the connection between the fourth air guide cover and the magnetron in the embodiment of the third aspect of the present invention; and

FIG. 11 is an exploded schematic view of the fourth air guide cover and the magnetron in FIG. 10 .

The attached reference numbers are as follows:

Magnetron 101, inverter component 102, transformer 1021, heat sink 1022, power board component 103, filter component 104, hot air component 105, infrared sensor component 106, base plate 110, air inlet hole 111, back plate 120;

cavity 200;

Fan assembly 300, fan seat 310, installation cavity 311, notch 3111, wind wheel cavity 312, motor bracket 313, through hole 314, first air duct 315, second air duct 316, output port 3161, first air guide channel 3162 , the second air guide channel 3163, the third air guide channel 3164, the first guide plate 317, the second guide plate 318, the wind wheel 320, the motor 330;

The first wind deflector 410 , the wind deflector 4101 , the second wind deflector 420 , the third wind deflector 430 , the fourth wind deflector 440 , the auxiliary deflector 4401 , and the guide plate 4402 .

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

In the description of the embodiments of the present invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, It is only for the convenience of describing the present invention and simplifying the description, but 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, and thus should not be construed as limiting the present invention.

In the description of the embodiments of the present invention, if the first and the second are described only for the purpose of distinguishing technical features, it cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly Contains the order of the indicated technical features.

In the description of the embodiments of the present invention, unless otherwise clearly defined, words such as setting, installation, and connection should be understood in a broad sense, and those skilled in the art can reasonably determine the meaning of the above words in the embodiments of the present invention in combination with the specific content of the technical solution Concrete meaning.

Currently, there are various types of cooking utensils used in the kitchen, among which microwave ovens and micro-steamers with microwave functions are more and more widely used. Microwave ovens are modern cooking utensils that use microwaves to heat food. A microwave oven is composed of a power supply, a magnetron, a control circuit, and a cooking cavity. The power supply provides a high voltage of about 4000 volts to the magnetron. Under the excitation of the power supply, the magnetron continuously generates microwaves, and then couples into the cooking cavity through the waveguide system. There is a rotatable stirrer at the entrance of the cooking cavity, because the stirrer is a fan-shaped metal, which can reflect the microwave in all directions after rotating, so it can evenly disperse the microwave energy into the cooking cavity, thereby heating food.

A microwave oven is a cooking appliance that uses food to absorb microwave energy in a microwave field to heat itself. The microwave generated by the microwave generator in the microwave oven establishes a microwave electric field in the cavity of the microwave oven, and certain measures are taken to make the microwave electric field evenly distributed in the cavity as much as possible, and the food is put into the microwave electric field, and the cooking time is controlled by the control center And microwave electric field strength, to carry out various cooking processes. The principle of microwave heating is: the microwave generated by the magnetron is a kind of electromagnetic wave, and the microwave rotates more than two billion times per second. Water and other polar molecules are driven by the microwave and follow the rotation at the same speed. The rotation and friction cause the temperature of water and other polar molecules to rise sharply in a short period of time, thereby heating the food.

In related technologies, microwave ovens have multiple heating components such as magnetrons, inverter components, power components, filter components, etc., and usually use air-cooled dispersion to dissipate heat. Since the fan component can only dissipate heat for a single component, the heat dissipation efficiency is low. , in order to meet the heat dissipation requirements, the microwave oven needs to be equipped with multiple fan assemblies, resulting in a complex structure and a large volume of the microwave oven, which is not conducive to the miniaturization of the microwave oven, and is also not conducive to the layout of intelligent components. The manufacturing cost is high and needs to be improved.

Embodiments of the present invention propose a cooking appliance that solves the above problems, and the cooking appliance is described by taking an integrated micro-steamer and oven as an example.

Referring to FIG. 6 , an embodiment of the present invention proposes a micro-steaming and roasting machine, which includes a casing and a cavity 200 inside the casing. The casing includes a bottom plate 110 and a back plate 120. The cavity 200 forms a space for placing ingredients. The cooking cavity defines an inner wall cavity between the shell and the cavity body 200, and the components of the integrated micro-steamer and oven are arranged in the inner wall cavity.

As shown in Figure 8, it can be understood that the components of the micro-steaming and roasting machine include a magnetron 101, an inverter assembly 102, a power board assembly 103, a filter assembly 104, a hot air assembly 105, an infrared sensor assembly 106 and a fan Assemblies 300, etc., magnetron 101, inverter assembly 102, power board assembly 103 and fan assembly 300 are arranged on the bottom surface of cavity 200, hot air assembly 105 is arranged on the back of cavity 200 (where the furnace door is located on the front side), infrared The sensor assembly 106 is arranged on the side of the cavity 200 .

As shown in Figure 8, the fan seat 310 of the fan assembly 300 is provided with an installation cavity 311, the filter assembly 104 is installed in the installation cavity 311, and the bottom plate 110 covers the magnetron 101, the inverter assembly 102, the power board assembly 103 and the fan assembly 300, the base plate 110 is provided with a plurality of air intake holes 111 for air intake, and the back plate 120 is also provided with a plurality of air intake holes 111, and when the fan assembly 300 is running, micro steam is drawn from the plurality of air intake holes 111. For the air outside the oven, the air inlet holes 111 on the bottom plate 110 are distributed in positions corresponding to the magnetron 101, the inverter assembly 102, and the power board assembly 103, and the air drawn in flows through the magnetron 101 and the inverter assembly. 102. The location of the power board assembly 103 is helpful for heat dissipation.

1 and 2, it can be understood that the fan base 310 is the base of the fan assembly 300 and is also the structure where the fan assembly 300 is connected to the cavity 200. One side of the fan base 310 is provided with a wind wheel for accommodating the wind wheel 320 Cavity 312, the bottom of the wind wheel cavity is provided with a motor bracket 313 for installing the motor 330, considering the suction airflow when the wind wheel 320 is running, the bottom of the wind wheel cavity 312 is provided with a through hole 314 for air circulation, and the motor bracket 313 is in the In the through hole 314 and without closing the through hole 314 , the wind wheel 320 and the motor 330 are located on two sides of the motor bracket 313 .

One end of the fan base 310 is provided with a first air duct 315, and the other end of the fan base 310 is provided with a second air duct 316, both of the first air duct 315 and the second air duct 316 are located on the side of the wind wheel cavity 312 and connected to the ventilation system. The wheel cavity 312 and the wind wheel 320 adopt centrifugal wind wheels, so the first air duct 315 and the second air duct 316 are at least partially arranged along the tangent of the wind wheel cavity 312 to match the heat dissipation airflow output by the wind wheel 320 and reduce flow resistance, which is beneficial Increase the flow rate and accelerate heat dissipation. Wherein, the second air channel 316 is provided with two or more output ports 3161 to dissipate heat from multiple components.

The wind wheel 320 drives the airflow to output from the wind wheel chamber 312 to the first air duct 315 and the second air duct 316, and the heat dissipation air flow output by the first air duct 315 can dissipate heat to at least one component of the micro-steamer, while the second The air duct 316 can dissipate heat to at least two components of the integrated micro-steaming and roasting machine through at least two output ports 3161. It has multiple outputs and can dissipate heat to multiple components at the same time, improving heat dissipation efficiency and helping to simplify micro-steaming. The structure of the all-in-one roasting machine is convenient for assembly and reduces manufacturing cost.

It can be understood that the installation cavity 311 is located on the side where the motor 330 is located, and there is a partition between the installation cavity 311 and the second air duct 316, and the two communicate through one or more output ports 3161, and the cooling air enters through the output ports 3161 The cavity 311 is installed to dissipate heat from the filter assembly 104 in the cavity 311 .

Referring to FIG. 4, it can be understood that the outlet of the first air channel 315 is connected to the fourth air guide cover 440. As shown in FIG. The four wind guides 440 flow through to dissipate heat from the inverter assembly 102 . As shown in FIG. 10 , the outlet of the fourth air guide cover 440 is connected to the magnetron 101 , and the output heat dissipation airflow is used to dissipate heat from the magnetron 101 to reduce the temperature of the magnetron 101 and ensure the stable operation of the magnetron 101 .

Referring to FIG. 10 and FIG. 11 , it can be understood that the inverter assembly 102 has a transformer 1021 and a heat sink 1022 , for the transformer 1021 and the heat sink 1022 , the cooling airflow output by the first air duct 315 can be divided into two streams. As shown in Figure 1, the fan base 310 is provided with a first deflector 317, the first deflector 317 is located in the first air duct 315 and arranged along the airflow direction, and the first deflector 317 is used to divide the heat dissipation airflow into two parts. The air blows to the transformer 1021 and the heat sink 1022 respectively, which is more targeted and has a better heat dissipation effect.

Referring to FIG. 10 and FIG. 11 , correspondingly, the inside of the fourth wind deflector 440 is provided with installation positions for installing the inverter assembly 102 , and the fourth wind deflector 440 is also provided with an auxiliary deflector that cooperates with the first deflector 317 The plate 4401 and the auxiliary deflector 4401 are located between the transformer 1021 and the heat sink 1022 to separate the heat dissipation airflow. In addition, since the inner space of the fourth air guide 440 is larger, the transformer 1021 is located in the middle of the inner space of the fourth air guide 440, and the entrance of the fourth air guide 440 is provided with an inclined guide plate 4402, and the guide plate 4402 will The cooling airflow is guided to the transformer 1021 to improve the cooling effect.

As shown in FIG. 10 , the magnetron 101 basically covers the outlet of the fourth air guide cover 440 , and the heat dissipation airflow all flows through the magnetron 101 to take away the heat of the magnetron 101 .

1, it can be understood that the fan base 310 is also provided with two second deflectors 318, and the two second deflectors 318 are arranged in the second air duct 316 to divide the second air duct 316 into the second air duct 316. One air guide channel 3162 , the second air guide channel 3163 and the third air guide channel 3164 correspond to three output ports 3161 .

6 and FIG. 9, the first air guide channel 3162 is connected to the first air guide cover 410, the infrared sensor assembly 106 is installed on the first air guide cover 410, and the first air guide channel 3162 and the first air guide cover 410 dissipate heat The air flow is led to the infrared sensor assembly 106 for heat dissipation. The first air guide cover 410 is provided with an air deflector 4101 to limit the heat dissipation air flow, and guide the heat dissipation air flow to the infrared sensor assembly 106 accurately; the second air guide channel 3163 passes through an output port 3161 communicates with the installation cavity 311, and introduces the cooling air flow into the installation cavity 311 to dissipate heat to the filter assembly 104 in the installation cavity 311; the third air guide channel 3164 is connected to the third air guide cover 430, and the third air guide cover 430 is connected to the hot air assembly 105 , the third air guide cover 430 is attached to the cavity 200, and guides part of the airflow to the hot air assembly 105. It can be understood that the function of the hot air assembly 105 is to produce hot air to roast the food in the cooking cavity.

5 and 8, the fan base 310 is connected to the second wind guide 420, the side wall of the installation cavity 311 is provided with a gap 3111 communicating with the second wind guide 420, and the power board assembly 103 is installed on the second wind guide 420. Inside, the heat dissipation airflow flowing through the installation cavity 311 enters the second air guide cover 420 to dissipate heat to the power board assembly 103. One side of the air channel 3164 is provided with an air outlet for exhausting the cooling air. On the side wall of the installation cavity 311, there is also a heat dissipation port 3112, which is arranged opposite to the notch 3111. The motor 330 drives the wind wheel 320 to rotate, and the air is sucked in from the heat dissipation port 3112, so that the filter assembly 104 can be dissipated for the first time.

Referring to FIG. 4 , the second embodiment of the present invention proposes an air duct assembly, including a fan base 310 , a first air guide 410 , a second air guide 420 , a third air guide 430 and a fourth air guide 440 , The fan base 310 has a wind wheel chamber 312, a first air duct 315 and a second air duct 316, the wind wheel chamber 312 is provided with a wind wheel 320, the wind wheel 320 is connected with a motor 330, the first air duct 315 and the second air duct 316 are located on the side of the wind wheel cavity 312 and connected to the wind wheel cavity 312, the wind wheel 320 adopts a centrifugal wind wheel, and the first air duct 315 and the second air duct 316 are at least partially arranged along the tangent of the wind wheel cavity 312.

The outlet of the first air duct 315 is connected to the fourth air guide cover 440, as shown in Figure 8 and Figure 10, the inside of the fourth air guide cover 440 can be used to install the inverter assembly 102, and the heat dissipation air flow from the fourth air guide cover 440 The medium flows through to dissipate heat from the inverter assembly 102 . The outlet of the fourth air guide cover 440 can also dissipate heat from another component such as the magnetron 101 , and use the output heat dissipation airflow to dissipate heat from the magnetron 101 to reduce the temperature of the magnetron 101 .

The fan base 310 is also provided with two second baffles 318 in the second air duct 316, and the two second baffles 318 divide the second air duct 316 into a first air guide channel 3162, a second air guide channel 3163 and the third air guide channel 3164, corresponding to three output ports 3161.

6 and FIG. 9, the first air guide channel 3162 is connected to the first air guide cover 410, the infrared sensor assembly 106 is installed on the first air guide cover 410, and the first air guide channel 3162 and the first air guide cover 410 dissipate heat The air flow is led to the infrared sensor assembly 106 for heat dissipation. The first air guide cover 410 is provided with an air deflector 4101 to limit the heat dissipation air flow and accurately guide the heat dissipation air flow to the infrared sensor assembly 106; the second air guide channel 3163 communicates with the installation cavity 311 , introduce the heat dissipation airflow into the installation cavity 311 to dissipate heat to the filter assembly 104 in the installation cavity 311; the third air guide channel 3164 is connected to the third air guide cover 430, the third air guide cover 430 is connected to the hot air assembly 105, and the third air guide channel The cover 430 is attached to the cavity 200 and guides part of the airflow to the hot air assembly 105. It can be understood that the function of the hot air assembly 105 is to generate hot air to heat the food in the cooking cavity.

Referring to FIG. 5 and FIG. 8 , the fan base 310 is connected to the second air guide 420 , the side wall of the installation cavity 311 has a gap 3111 communicating with the second air guide 420 , and the power board assembly 103 is installed inside the second air guide 420 , the heat dissipation airflow flowing through the installation cavity 311 enters the second air guide 420 to dissipate heat on the power board assembly 103, the second air guide 420 completely wraps the power board assembly 103, and the second air guide 420 faces away from the third air guide One side of the channel 3164 is provided with an air outlet for exhausting the cooling air.

The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned embodiments. Within the scope of knowledge of those of ordinary skill in the art, various modifications can be made without departing from the gist of the present invention. kind of change.

Claims

Fan base, including:

A seat body, the seat body is provided with a wind wheel chamber, one end of the seat body is provided with a first air duct communicating with the wind wheel chamber, and the other end of the seat body is provided with a first wind channel communicating with the wind wheel chamber. two air passages, the second air passage has at least two outlets; and

The motor bracket is arranged in the through hole at the bottom of the wind wheel cavity.
The fan seat according to claim 1, wherein the seat body is provided with a first deflector located in the first air passage, and the first deflector divides the first air passage into two aisle.
The fan seat according to claim 1, wherein the seat body is provided with a second deflector located in the second air passage, and the number of the second deflectors is two and separates the second air passage Divided into three channels.
The fan base according to any one of claims 1 to 3, wherein the wind wheel cavity is located on one side of the base body, and an installation cavity is provided on the other side of the base body, and the installation cavity communicates with at least one said outlet.
Duct components, including:

The fan seat has a seat body, one side of the seat body is provided with a wind wheel chamber, one end of the seat body is provided with a first air duct communicating with the wind wheel chamber, and the other end of the seat body is provided with a communication channel The second air channel of the wind wheel chamber has at least two output ports, and the other side of the base is provided with an installation cavity, and the installation cavity communicates with at least one of the output ports. The bottom of the wind wheel cavity is provided with a through hole, and a motor bracket is arranged in the through hole; and

The wind wheel is arranged in the wind wheel cavity, and the wind wheel is connected with a motor fixed to the motor bracket.
The air duct assembly according to claim 5, wherein the seat body is provided with a second deflector located in the second air duct, the number of the second deflectors is two and the second air guide The air duct is divided into a first air guide channel, a second air guide channel and a third air guide channel, the fan seat is connected with a first air guide cover and a third air guide cover, and the first air guide channel communicates with the first air guide channel. An air guide cover, the second air guide channel communicates with the installation cavity, and the third air guide channel communicates with the third air guide cover.
The air duct assembly according to claim 6, wherein a second air guide cover is connected to the fan base, and a notch communicating with the second air guide cover is provided on the side wall of the installation cavity.
The air duct assembly according to claim 5, wherein a fourth air guide cover is connected to the fan base, the fourth air guide cover communicates with the first air duct, and the inside of the fourth air guide cover is arranged There are installation bits.
A cooking appliance comprising the air duct assembly according to any one of claims 5-8.
The cooking appliance according to claim 9, further comprising a bottom plate, the bottom plate covers the air duct assembly, and the bottom plate is provided with a plurality of air inlet holes.