WO2021218994A1

WO2021218994A1 - Protective instrument for aerial infection source

Info

Publication number: WO2021218994A1
Application number: PCT/CN2021/090506
Authority: WO
Inventors: 刘延兵
Original assignee: 刘延兵
Priority date: 2020-04-30
Filing date: 2021-04-28
Publication date: 2021-11-04
Also published as: CN212997586U

Abstract

Disclosed in the utility model is a protective instrument for aerial infection sources, comprising a casing. An air inlet and an air outlet are provided on the casing. A charged particle emission unit and an airflow control unit are provided in the casing between the air inlet and the air outlet. The charged particle emission unit comprises a charged particle emission electrode. The charged particle emission electrode is electrically connected to a high voltage power supply for emitting charged particles from the charged particle emitting electrode. The airflow control unit is used for sucking an airflow from the air inlet and discharging the airflow from the air outlet. The protective instrument for aerial infection sources can continuously generate charged particles and disperse same in an indoor environment to effectively protect against pathogenic microorganisms, and can be used in places such as hospitals, schools, offices, restaurants, waiting halls where people gather for dynamically and effectively protect against pathogenic microorganisms, so as to block and reduce airborne transmission of infection sources such as viruses and bacteria.

Description

Air infection source protection machine

Technical field

The utility model relates to an air infection source protection machine.

Background technique

In the high-incidence season of various diseases such as influenza, atypical pneumonia, avian flu, etc., in various scenarios such as hospital consultation, general ward or ICU treatment, isolation observation, examination and sampling, or ward treatment, the source of infection continues to produce Aerosols and droplets of diseased microorganisms suspended in the air for a long time cannot be eliminated in time. Even with passive protective measures such as masks, goggles, and isolation gowns, doctors and patients still have the risk of cross-infection and transmission. Therefore, actively blocking the source of microbial infections and constantly eliminating microbial pollution in the diagnosis and treatment environment is an effective and feasible method to reduce hospital infections.

The working methods of existing air purification or disinfection equipment on the market mainly include chemical disinfection, catalytic decomposition, physical filtration, electrostatic dust collection, adsorption, ultraviolet rays, and so on. Among them, chemical disinfection, ultraviolet disinfection, ozone disinfection and other disinfection methods cannot be used indoors when there are people, so that they cannot be disinfected at any time; plasma, photocatalyst, and built-in ultraviolet rays can be used when people are used, but they are still passive disinfection and cannot be done. Disinfect the space at any time. In particular, the current air disinfection equipment can only suck air into the equipment for processing when performing germ killing, which has low killing efficiency, especially incapable of killing germs on the surface of the object. When responding to public health emergencies, there is an urgent need for a device that can continuously inactivate the floating microorganisms in the air, block the spread and spread of microorganisms in the air from the source, and prevent the outbreak of infectious diseases.

In recent years, charged particles have been proven to have bactericidal effects. For example, Marie Hagbom, Johan Nordgren, and others published in Scientific Reports on June 23, 2015, entitled Ionizing air affects influenza virus infectivity and preventions airborne-transmission. The electrostatic attraction affects the infectivity of influenza virus and prevents the virus from spreading through the air between animals. If a charged particle emission unit capable of emitting charged particles can be integrated in the air purification equipment, it will help produce a certain concentration of charged particles in the indoor environment and effectively control the amount of harmful microorganisms in the indoor environment. At present, the emission units used to generate charged particles on the market, such as the negative oxygen ion emission unit set in the negative oxygen ion generator, are mostly auxiliary functions, which cannot achieve sufficient amount of charged particles, and the detection result of the concentration of charged particles outside the device is not ideal , It is also unable to form a certain range of charged particle coverage area. Some equipment can only detect a small amount of ions at the air outlet or even basically no charged particles.

It should be noted that the above content belongs to the technical cognition category of the inventor and does not necessarily constitute the prior art.

Utility model content

The purpose of the utility model is to solve the problems existing in the prior art and provide an air infection source protection machine that can continuously generate charged particles and disperse them in the indoor environment to effectively kill pathogenic microorganisms.

The utility model achieves the above-mentioned purpose by adopting the following technical solutions:

An air infection source protection machine, comprising a casing, an air inlet and an air outlet are arranged on the casing, a charged particle emission unit and an airflow control unit are arranged in the casing between the air inlet and the air outlet, and the charged The particle emission unit includes a charged particle emission electrode that is electrically connected to a high-voltage power supply for emitting charged particles from the charged particle emission electrode, and the airflow control unit is used to draw airflow from the air inlet and from the air outlet discharge.

In a preferred embodiment, the charged particle emitting unit is arranged at the air outlet, the charged particle emitting electrode includes a conductive fiber bundle and a conductive seat, one end of the conductive fiber bundle is electrically connected to the conductive seat, The conductive base is electrically connected with a high-voltage power supply.

In a preferred embodiment, the conductive fiber bundle is composed of micron-sized conductive fibers arranged in parallel, the conductive fibers are carbon fibers or fullerene fibers, and the length direction of the conductive fibers is arranged along the airflow direction and the conductive fibers are arranged in parallel. The end faces downstream in the direction of airflow.

In a preferred embodiment, the charged particle emission unit further includes a protective cover, the conductive seat is fixed in the protective cover, and a side wall of the protective cover is provided with ventilation holes.

In a preferred embodiment, a plurality of wind deflectors are arranged side by side at the air outlet, and the outer ends of the wind deflectors are arranged obliquely toward the front side of the casing.

In a preferred embodiment, the airflow control unit is a centrifugal fan, the centrifugal fan has two air outlets, the two air outlets are respectively located on the left and right sides of the centrifugal fan, the two air outlets of the centrifugal fan are respectively The two air outlets facing the casing are arranged.

In a preferred embodiment, a filter screen, a charging unit and an electrostatic collection unit are further provided in the casing between the air inlet and the air outlet, and the filter screen, the charging unit and the electrostatic collection unit are arranged in the charged particle emission Upstream of the unit.

In a preferred embodiment, the charging unit includes a needle-shaped electrode group and a mesh electrode that are arranged oppositely, and the needle-shaped electrode group and the mesh electrode are electrically connected to the positive electrode and the negative electrode of the power supply, respectively;

In a preferred embodiment, the positive electrode sheet and the negative electrode sheet are electrically connected to the positive electrode and the negative electrode of the power supply, respectively.

In a preferred embodiment, an ultraviolet lamp is further arranged in the casing, and the ultraviolet lamp is arranged between the filter screen and the charging unit.

In a preferred embodiment, the number of centrifugal fans is two, the two centrifugal fans are arranged one above the other, the air outlet of each centrifugal fan is arranged corresponding to the air outlet on the casing, and each air outlet is provided with a live line. Particle emission unit.

The beneficial effects of this application include but are not limited to:

When the air infection source protection machine provided in the present application is working, the charged particles continuously emitted by the charged particle emission unit are blown into the indoor air by the fan, so that a certain concentration of charged particles is dispersed in the air. Among them, the charged particle emitting electrode of the charged particle emitting unit adopts micron-sized carbon fiber or fullerene fiber to increase the curvature of the tip of the emitting electrode, enhance the local field strength of the tip, and increase the yield of charged particles; On the one hand, the number of carbon fibers or fullerene fibers is greatly increased compared to the number of emitter electrodes based on metal wires or needle electrodes, which enhances the emission ability of charged particles and increases the yield of charged particles. The combined effect of the two aspects is improved. The concentration of charged particles in space.

There is a certain potential difference between the inside and outside of the cell membrane of bacteria, viruses and other microorganisms. When the indoor air is dispersed with a certain concentration of charged particles, the microorganisms attached to the air and on the surface of the object will be affected by the action of the charged particles to increase the potential difference between the inside and outside of the cell membrane and be inactivated Or die, block the spread of germs, and achieve the purpose of active, continuous, and comprehensive protection of germs. The protective effect is higher than that of traditional air disinfection and sterilization equipment that requires air to be sucked into the casing for treatment. It can be used in hospitals, schools, and offices. , Restaurants, waiting halls and other places where people gather, dynamic and effective protection of pathogenic microorganisms, blocking and reducing the air transmission of infection sources such as viruses and bacteria. The inactivated germs enter the casing along with the air circulation, and are killed and collected a second time in the electric field process of the charging unit and the electrostatic collection unit, which improves the protection effect.

Description of the drawings

The drawings described here are used to provide a further understanding of the application and constitute a part of the application. The exemplary embodiments and descriptions of the application are used to explain the application, and do not constitute an improper limitation of the application. In the attached picture:

Figure 1 is a schematic diagram of a longitudinal cross-sectional structure of the air infection source protection machine involved in this application;

Fig. 2 is a schematic diagram of the longitudinal section structure of the air infection source protection machine involved in this application;

Figure 3 is a schematic diagram of the external structure of the air infection source protection machine involved in this application

4 is an enlarged schematic diagram of the cross-sectional structure of the charged particle emission unit in the air infection source protection machine involved in this application;

FIG. 5 is a schematic diagram of the structure of the charged unit in the air infection source protection machine involved in this application;

Fig. 6 (a) is a schematic diagram of the longitudinal cross-sectional structure of Fig. 5, and (b) is a schematic diagram of the cross-sectional structure of Fig. 5;

FIG. 7 is a schematic structural diagram of an electrostatic collection unit in the air infection source protection machine involved in this application;

(A) in FIG. 8 is a schematic diagram of the longitudinal cross-sectional structure of FIG. 7, and (b) is a schematic diagram of the cross-sectional structure of FIG. 7;

9 is a schematic diagram of the structure of the centrifugal fan and the charged particle emission unit in the air infection source protection machine involved in this application;

10 is a schematic diagram of an enlarged structure of a charged particle emission unit (with a protective cover) in the air infection source protection machine involved in this application;

FIG. 11 is a schematic diagram of the structure of the protective cover in the air infection source protection machine involved in this application;

FIG. 12 is a schematic structural diagram of a charged particle emission unit in the air infection source protection machine involved in this application;

Figure 13 is a schematic diagram of air flow when the number of centrifugal fans is two.

In the figure, 100, housing; 110, air inlet; 120, air outlet; 200, filter; 300, charging unit; 310, needle electrode group; 320, mesh electrode; 400, electrostatic collection unit; 410, Positive electrode sheet; 420, negative electrode sheet; 500, charged particle emission unit; 510, conductive fiber bundle; 520, conductive seat; 530, protective cover; 531, ventilation hole; 600, centrifugal fan; 700, ultraviolet lamp; 800, Baffle.

Detailed ways

In order to clearly illustrate the technical characteristics of this solution, the following describes the utility model in detail through specific implementations and in conjunction with the accompanying drawings.

It should be noted that in the following description, many specific details are explained in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

As shown in Figures 1 to 3, the air infection source protection machine provided by the present application includes a casing 100. The casing 100 is provided with an air inlet 110 and an air outlet 120, and the machine between the air inlet 110 and the air outlet 120 The housing 100 is provided with a charged particle emission unit and an airflow control unit, and the airflow control unit is used to draw the airflow from the air inlet 110 and discharge it from the air outlet 120.

The charged particle emission unit 500 includes a charged particle emission electrode. The charged particle emission electrode is electrically connected to a high-voltage power supply for emitting charged particles from the charged particle emission electrode. The charged particle emission unit 500 is discharged with the airflow during the process of being discharged from the air outlet 120 into the casing 100 In the indoor environment, a certain concentration of charged particles will be dispersed in the air. The charged particles act on the microorganisms to increase the potential difference between the inside and outside of the cell membrane of the microorganisms, increase the permeability of the cell membrane, and cause the rupture of the microorganisms and lead to death.

Specifically, as shown in FIG. 4, the charged particle emitter electrode shown in the present application includes a conductive fiber bundle 510 and a conductive seat 520. One end of the conductive fiber bundle 510 is electrically connected to the conductive seat 520, and the conductive seat 520 is connected to the high-voltage power supply. Electric connection. Furthermore, one end of the conductive fiber bundle 510 is connected to the conductive base 520 by conductive glue.

Further, the high-voltage power supply may be a positive high-voltage power supply or a negative high-voltage power supply. When it is a positive high voltage, the positive pole of the power supply is connected to the conductive base 520, and the negative pole is grounded.

Further, as shown in FIGS. 9-12, the charged particle emission unit 500 is arranged at the air outlet 120, the conductive fiber bundle 510 is composed of micron-sized conductive fibers arranged in parallel, and the conductive fibers are carbon fibers or fullerene fibers. , The length direction of the conductive fiber is arranged along the airflow direction, and the end of the conductive fiber faces the downstream of the airflow direction.

The conductive seat 520 is strip-shaped, the cross-section of the conductive seat 520 along the length of the fiber bundle is U-shaped, and the conductive fiber bundle 510 is fixed at the bottom of the U-shaped cavity of the conductive seat 520. The conductive base 520 is connected to the high-voltage output end of the high-voltage circuit, and the high voltage on the high-voltage electrode continuously strips the charged particles from the end of the conductive fiber.

The ends of the conductive fibers face the outside of the casing 100, and the generated charged particles are smoothly blown into the indoor environment by the airflow. Further, the charged particle emission unit 500 further includes a protective cover 530, the conductive seat is fixed in the protective cover 530, and a side wall of the protective cover 530 is provided with a ventilation hole 531.

The protective cover 530 is made of plastic material and has an inner cavity that can accommodate the conductive seat 520. Generally, the cross-section of the protective cover 530 is U-shaped, and the ends of the conductive fibers are set toward the opening of the protective cover.

A filter screen 200, a charging unit 300 and an electrostatic collection unit 400 are also arranged in the casing between the air inlet 110 and the air outlet 120. The filter screen 200, the charging unit 300 and the electrostatic collection unit 400 are arranged in the charged particle emission unit. Upstream.

In a preferred embodiment, the charging unit includes a needle-shaped electrode group 310 and a mesh electrode 320 disposed oppositely, and the needle-shaped electrode group 310 and the mesh electrode 320 are electrically connected to the positive electrode and the negative electrode of the power supply, respectively.

As shown in Figures 5 and 6, the needle-shaped electrode group 310 is composed of a plurality of needle-shaped electrodes arranged in a row, and is electrically connected to the positive electrode of the power supply; the mesh electrode 320 is made of a metal grid and is connected to the negative electrode Electric connection. In actual production, one conductor is arranged in a square frame made of insulating material, each conductor is provided with multiple needle-shaped electrodes, the outside of each conductor is wrapped with an insulating shell, and the conductors are connected together and then connected to the power supply. . The mesh electrode 320 has a grid shape to facilitate air flow.

The radius of curvature of the needle electrode group 310 and the mesh electrode 320 is quite different. A high voltage direct current is applied between the needle electrode and the mesh electrode 320 to form an extremely uneven electric field. The electric field intensity in the space near the needle electrode with a small radius of curvature The ionization strength is reached first, and the gas is ionized. The anions and cations produced after gas ionization are adsorbed on the suspended matter passing through the electric field, and the suspended matter is charged. Further, the needle-shaped electrodes are arranged facing the direction of the airflow. The microorganisms are further inactivated and collected during the electric field process of the charging unit and the electrostatic collection unit, which improves the effect of protecting the bacteria.

As shown in FIG. 7 and FIG. 8, in a preferred embodiment, the static electricity collection unit includes alternately arranged positive electrode sheets 410 and negative electrode sheets 420. The positive electrode sheets 410 and the negative electrode sheets 420 are connected to the positive and negative electrodes of the power supply, respectively. Electric connection. The positive electrode sheet 410 and the negative electrode sheet 420 are arranged in parallel in a square frame made of insulating material. All the positive electrode sheets 410 are connected to one conductor, and all the negative electrode sheets 420 are connected to the other conductor. Connect to the power supply.

Further, the positive electrode sheet 410 and the negative electrode sheet 420 are arranged parallel to the airflow direction to reduce wind resistance.

After the high voltage direct current is applied between the positive electrode sheet 410 and the negative electrode sheet 420, a high voltage electrostatic field is formed between the positive electrode sheet 410 and the negative electrode sheet 420. The electrode plates of different polarities move directionally, and are deposited on the electrode plates after discharge to achieve the purpose of separating suspended matter and airflow, and effectively remove dust, particles, and smoke particles.

The charging unit and the electrostatic collection unit are modularly arranged, which is convenient for disassembly and maintenance. The electric control unit for supplying power to each module is arranged in the lower part of the casing 100.

1 again, in a preferred embodiment, an ultraviolet lamp 700 is also provided in the casing 100. The ultraviolet lamp 700 is arranged between the filter 200 and the charging unit, and the equipment in the casing 100 is killed by the emitted ultraviolet light. Bacteria attached to and entering the airflow in the casing 100. The setting of the UV lamp 700 enables the device to realize the sterilization and self-cleaning function. For example, the device turns on the UV lamp 700 for a certain period of time, such as 20 minutes for internal sterilization, and then turns on the UV lamp 700 for 10 minutes at intervals of 4 hours, and continues after shutdown Turn on for 20 minutes to sterilize and clean the inside of the equipment.

Further, the air flow control unit is a centrifugal fan 600. The centrifugal fan 600 has two air outlets, and the two air outlets are respectively located on the left and right sides of the centrifugal fan 600, and the two air outlets of the centrifugal fan 600 are respectively facing the casing 100 The two air outlets 120 are set. The charged particle emission unit 500 is arranged in a strip shape at the air outlet 120, and the length of the protective cover 530 is close to the height of the air outlet 120, and is just stuck at the air outlet. It can be understood that the width of the charged particle emission unit 500 is smaller than the width of the air outlet of the centrifugal fan 600, so that the airflow smoothly blows the charged particles into the indoor environment during the process of smoothly flowing from the centrifugal fan 600 to the air outlet 120 of the device.

Furthermore, the air outlet 120 is provided with an air deflector 800, and the outer end of the air deflector 800 is inclined to the front side of the casing 100 to guide the direction of the air, and to match the direction of the air on both sides of the centrifugal fan 600, The airflow on one side of the casing 100 is blown obliquely upward, and the airflow on the other side is blown obliquely downward to form a wheel-shaped airflow, so that the indoor air is sufficiently disturbed, and the charged particles are fully contacted with germs.

As shown in FIG. 13, the number of centrifugal fans 600 can be set to two, two centrifugal fans 600 are arranged up and down in the casing 100, and the air outlet of each centrifugal fan 600 is respectively connected to the air outlet 120 on the casing 100. Correspondingly, each air outlet 120 is provided with a charged particle emission unit 500 respectively. The air flow is blown out from the casing 100 and then flows in a wheel shape, which improves the disturbance effect of the air flow, and makes the charged particles fully dispersed in the air. Further, the device can be set to a wall-mounted structure to improve the effect of air disturbance.

Furthermore, the filter 200 is a HEPA filter 200, which is used to intercept large particles in the airflow, protect and improve the efficiency of the suspended particle charging unit and the electrostatic collection unit. It can be selected according to actual conditions, and is usually a HEPA filter.

When working, when the airflow is discharged from the air outlet, it blows out the charged particles emitted by the charged particle emission unit, so that a certain concentration of charged particles is dispersed in the air. When the indoor air is dispersed with a certain concentration of charged particles, the microorganisms in the air and on the surface of the object will be affected by the action of the charged particles to increase the potential difference between the inside and outside of the cell membrane to inactivate or die, block the spread of germs, and protect the germs. Purpose. The inactivated germs enter the cabinet along with the air circulation, and are further killed in the electric field process of the charging unit and the electrostatic collection unit, so that the microorganisms in the indoor air and the surface of the object are dynamically killed and blocked. The spread of germs has an effective protective effect.

Table 1 below shows the parameters of a certain type of equipment in the air infection source protection machine provided by this application.

Table 1

序号Serial number	名称name	参数parameter
11	额定电压Rated voltage	220VAC220VAC
22	额定功率rated power	75W75W
33	过滤网Filter	HEPA高效过滤网HEPA high efficiency filter
44	带电粒子发射量Emission of charged particles	3.1x10 ⁶/cm ³,200cm处 3.1x10 ⁶ /cm ³ , at 200cm
55	出风口数量Number of air outlets	22
66	带电粒子发射单元的高压电源电压High voltage power supply voltage of charged particle emission unit	8000V-15000V8000V-15000V
77	荷电单元场强Field Strength of Charged Unit	+9000V+9000V
88	静电收集单元场强Electrostatic collecting unit field strength	-3000V-3000V
99	风量Air volume	600m ³/h 600m ³ /h
1010	紫外灯功率UV lamp power	6W6W
1111	臭氧浓度Ozone concentration	＜0.01mg/m ³ ＜0.01mg/m ³

1212	产品尺寸Product Size	1460440400mm1460440400mm
1313	产品重量product weight	36kg36kg

Among them, an Air Ion Counter (Air Ion Counter) is used to detect the emission of charged particles.

In the description of the present utility model, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal" The orientation or positional relationship indicated by "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. are based on the orientation or positional relationship shown in the drawings, It is only for the convenience of describing and simplifying the description of the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

In the present invention, unless otherwise clearly defined and defined, the terms "installation", "connected", "connected", "fixed" and other terms should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected or integrated; it can be a mechanical connection, an electrical connection, or a communication; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal communication of two components or the interaction of two components relation. For those of ordinary skill in the art, the specific meaning of the above-mentioned terms in the present utility model can be understood according to specific circumstances.

The above-mentioned specific implementations should not be used as a limitation to the protection scope of the present utility model. For those skilled in the art, any alternative improvements or changes made to the implementations of the present utility model fall within the protection scope of the utility model.

Anything not described in detail in the present utility model is the well-known technology of those skilled in the art.

Claims

An air infection source protection machine, which is characterized by comprising a casing, an air inlet and an air outlet are arranged on the casing, and a charged particle emission unit and an air flow control unit are arranged in the casing between the air inlet and the air outlet , The charged particle emission unit includes a charged particle emission electrode, the charged particle emission electrode is electrically connected to a high-voltage power supply for emitting charged particles from the charged particle emission electrode, and the airflow control unit is used to draw the airflow from the air inlet And discharged from the air outlet.
The air infection source protection device according to claim 1, wherein the charged particle emission unit is arranged at the air outlet, the charged particle emission electrode includes a conductive fiber bundle and a conductive seat, and the conductive fiber bundle One end is electrically connected to the conductive seat, and the conductive seat is electrically connected to the high-voltage power supply.
The air infection source protection device according to claim 2, wherein the conductive fiber bundles are composed of micron-sized conductive fibers arranged in parallel, the conductive fibers are carbon fibers or fullerene fibers, and the conductive fibers The length direction of the conductive fiber is arranged along the airflow direction and the end of the conductive fiber faces the downstream of the airflow direction.
The air infection source protection device according to claim 2, wherein the charged particle emission unit further comprises a protective cover, the conductive seat is fixed in the protective cover, and the side wall of the protective cover is provided with Vents.
The air infection source protection device according to claim 1, wherein a plurality of air guide plates are arranged side by side at the air outlet, and the outer end of the air guide plate is inclined to the front side of the casing.
The air infection source protection machine according to claim 1, wherein the air flow control unit is a centrifugal fan, the centrifugal fan has two air outlets, and the two air outlets are respectively located on the left and right sides of the centrifugal fan , The two air outlets of the centrifugal fan are respectively arranged toward the two air outlets of the casing, and each air outlet is respectively provided with a charged particle emission unit.
The air infection source protection device according to claim 1, wherein a filter, a charging unit, and an electrostatic collection unit are further provided in the casing between the air inlet and the air outlet, and the filter, the charging unit The unit and the electrostatic collection unit are arranged upstream of the charged particle emission unit.
The air infection source protection device according to claim 7, wherein the charging unit comprises a needle electrode group and a mesh electrode disposed oppositely, and the needle electrode group and the mesh electrode are respectively connected to the positive electrode of the power supply. Electrically connected to the negative electrode;

The static electricity collection unit includes alternately arranged positive electrode sheets and negative electrode sheets, and the positive electrode sheets and the negative electrode sheets are electrically connected to the positive electrode and the negative electrode of the power supply, respectively.
The air infection source protection device according to claim 7, wherein an ultraviolet lamp is further provided in the casing, and the ultraviolet lamp is arranged between the filter screen and the charging unit.
The air infection source protection machine according to claim 6, characterized in that the number of centrifugal fans is two, the two centrifugal fans are arranged one above the other, and the air outlet of each centrifugal fan is respectively arranged corresponding to the air outlet on the casing .