WO2019071864A1

WO2019071864A1 - Fume hood

Info

Publication number: WO2019071864A1
Application number: PCT/CN2018/071359
Authority: WO
Inventors: 阮红正; 唐光野; 卢丙利
Original assignee: 倚世节能科技（上海）有限公司
Priority date: 2017-10-11
Filing date: 2018-01-04
Publication date: 2019-04-18
Also published as: CN107497815B; CN107497815A

Abstract

A fume hood, comprising a hood body (100) having an opening (101) at a front side, and further comprising an air exhaust outlet (201), an air supply channel (301), and a guide plate (400). The air exhaust outlet (201) is provided at a rear side of an upper portion of the hood body (100). The air supply channel (301) comprises an air supply opening (302) provided at the periphery of a lower portion of the opening (101) of the hood body. The guide plate (400) is vertically provided at a rear side of an inner cavity of the hood body (100). Multiple through holes (401) are provided on the guide plate (400). A side wall of the hood body (100) is a hollow structure. The air supply channel (301) extends along the side wall, and is in communication with an air supply inlet (303) and the air supply opening (302).

Description

Fume hood

Technical field

The present invention relates to equipment, and more particularly to a fume hood.

Background technique

Fume hoods (also known as fume hoods or fume hoods) are used to capture, contain, and remove exhaust gases and harmful gases, creating a safe working environment that prevents people from inhaling exhaust gases or harmful gases that can be life-threatening and healthy. The traditional fume hood connects the exhaust fan to the exhaust vent or connects the exhaust vent to the exhaust vent of the large exhaust fan of the building, and uses the suction of the exhaust fan to drive the gas in the working chamber of the fume hood. Exhaust, and introduce ambient air from the front opening of the fume hood, while exhausting air in the working chamber with a high-powered fan to carry out the handling and treatment of harmful substances in the air. Under the design concept of the traditional fume hood, the higher the air volume sent from the front opening, the more effective the fume hood is to control and discharge the harmful substances in the air, so it is necessary to pass the HVAC system of the building to the space using the fume hood. For example, in the laboratory, a large amount of air is added to replace the ambient air that is drawn into the working chamber of the fume hood. Since the air supplied to the laboratory is part of the ambient air supply to the laboratory, it must be treated to the same ambient air level to ensure the comfort and safety of the laboratory work environment, so the use of conventional fume hoods generally results in Buildings such as laboratories generate significant energy consumption. In addition, the above air flow pattern often results in the generation of vortex-type air tissue near the exhaust vent and front opening of the fume hood. In this case, regardless of the speed of the air sucked from the front opening, if there is turbulent flow and vortex in the air fluid structure in the working chamber, the air in the working chamber overflows from the working chamber of the fume hood to the front opening. The risks pose a threat to the health and safety of the experimenter.

The patent document published as CN106140769A discloses a fume hood which can reduce the energy consumption of the air conditioner, suppress the overflow of harmful substances in the working chamber, and has low installation cost and high consistency of product quality. Wherein, the air supplement system is disclosed, and the air supplement system is connected with the air supply passage of the building to supplement the working chamber of the fume hood, and the air supply system has at least one air supply port at the upper and lower portions of the cabinet body. The article also specifically discloses three air inlets and corresponding positions. As shown in FIG. 1 , a first air inlet A1 is disposed above the front opening of the fume hood, a second air inlet A2 is disposed below the front opening, and a third portion is disposed at an upper portion of the cabinet and at a front side of the front wall. Air inlet A3.

Although the fume hood has better energy-saving effect, it also finds the following defects: when the fume hood is working, the exhaust system performs suction, the gas in the fume hood flows along the hollow arrow shown, and the air supply system passes through the air supply port. The supply air provides supplemental air; at the same time, the indoor air near the front opening outside the fume hood is sucked and sucked into the working chamber through the front opening to become supplementary air. At this time, when the upper two air supply ports or one of them provides the supplementary air, the air supply is guided by the suction of the air exhaust system, and the air supply of the air supply system guides the air flow, and the air flow is supplemented at the upper side. A small vortex is formed between the front opening replenishing air (as shown by the circle in Fig. 1), and there is a possibility that a small amount of gas in the cabinet is caught in the small vortex without being sucked into the exhaust system. If there is an external disturbance airflow at this time, such as someone walking through, or the operator's arm coming in and out, destroying the balance of the small eddy current, may cause a small amount of harmful gas caught in the small eddy. In addition, since the fume hood is provided with three air inlets, the production process is complicated and the manufacturing cost is high; at the same time, the fume hood needs to accurately control the air volume of the three air inlets to achieve the safety and energy saving effect described above, which is also High requirements are placed on the control accuracy of the air supply system.

Le Youfen and others are in the "Research and Application of Air Curtain Ventilation Cabinets" (Journal of Nanhua University (Technology and Engineering): March 2002, Vol. 16 No. 1: 44-49). Based on the introduction of blown air curtain technology, a new type of blown air curtain type air exhaust cabinet (shown in Figure 2) was developed, and it is considered that this new type of air exhaust cabinet has the advantages of energy saving, comfortable operation and good control effect. . In fact, the structure that relies on the air curtain to cut off the internal and external environment has very high requirements on the environment in which the air exhaust cabinet is located, the movement of the personnel, the heat convection, the direction of the air-conditioner, the cross-flow generated by the indoor air supply and exhaust system, etc. A large impact can cause air curtain rupture to fail. Since the air curtain is close to the operator, once the air curtain is broken, the air curtain carrying the gas in the cabinet is likely to cause serious health and serious consequences to the operator. In addition, when the operator uses the air curtain type air exhaust cabinet, the airflow sent by the air outlet is simultaneously formed by the push of the air supply port and the suction of the air outlet to form a gas curtain. When the operator uses the fume hood, the arm must pass through the air curtain. At this time, the air flow from the bottom to the top is likely to overflow to the operator's position along the lower side of the operator's arm. That is to say, the wind sent by the air supply port may overflow from the air exhaust cabinet after being polluted by the gas in the cabinet, and since the wind direction is sent from the bottom to the front of the operator, the fume hood is once The air curtain ruptures and the air containing contaminants is sent directly to the operator's respiratory tract, causing a very serious safety hazard.

Summary of the invention

The embodiment of the invention can provide a fume hood, which can eliminate safety hazards and prevent harmful gas from overflowing in the cabinet, and has the characteristics of simple structure and low production cost.

The embodiment of the invention provides a fume hood, which comprises a cabinet with an opening on the front side, and further comprises:

Connecting the air outlet of the cabinet body, the air outlet is located at the back side of the cabinet body;

Including the air supply passage of the air inlet; and,

a baffle standing on the rear side of the cabinet body, the deflector includes a substrate and an inclined portion, and a gap is left between the lower end of the substrate and the bottom of the cabinet, and between the lower end of the inclined portion and the substrate.

among them,

The air inlet is located below the opening, and the inclined portion is disposed such that the front end covers the air outlet when viewed from below.

Preferably, from the front side, the center of the air outlet is located in the middle of the left and right sides of the cabinet; when viewed from the left or right side, the center of the air outlet is located on the rear side of the cabinet.

Preferably, viewed from the left or right side, the center of the vent is located between the front and rear sides of the cabinet and one quarter of the rear side.

Preferably, when viewed from the front side, the width of the air supply opening is greater than or equal to the width of the cabinet, so that the air supply opening extends to the left and right ends of the opening and covers the opening.

Preferably, when viewed from the left or the right side, the top side and the rear side of the air supply port are connected in an arc shape or a chamfered connection, so that the air supply port is blown upward and backward.

Further, the arc is a quarter arc.

Preferably, the outside of the air supply opening is located in the same vertical plane as the inner side of the front part of the cabinet, so that the upward air supply flow sent through the air supply opening covers the opening of the cabinet body.

Preferably, the air supply port is provided with a guide plate, and the guide plate divides the air supply port into an outer air supply port directed upward and an inner air supply port directed to the inner side of the cabinet body.

Further, the cross section of the guide plate is curved to guide the direction of the supplemental airflow sent through the inner air supply port.

Further, the lower end portion of the guide plate is located in the air supply passage, and the lower end portion is configured to distribute the air supply air volume of the outer air supply port and the inner air supply port.

Preferably, the deflector substrate is provided with a through hole, and the through hole is evenly distributed in the horizontal width direction, and the proportion of the hole area from the bottom to the top is gradually reduced with respect to the unit area.

Preferably, the through holes are gradually increased from bottom to top with each other, or the hole areas of the through holes are gradually reduced.

Further, as seen from the front side, the through holes provided in the deflector substrate are narrow and wide, and are radially arranged.

Further, the deflector substrate further includes a lower portion of the deflector and a lower portion of the deflector, and a gap is left between the lower portion of the deflector and the upper portion of the deflector.

Preferably, an inclined plate is disposed above the front side of the cabinet body; the upward extending direction of the inclined plate forms an angle with the upward extending direction of the inclined portion.

Preferably, the air blower is connected to the air supply passage, and the air supplement fan is a power adjustable fan.

Further, the air blower is disposed in the air supply passage.

Preferably, the air supply valve is further connected to the air supply passage, and the air supply valve is an open degree variable valve.

Preferably, the side wall and/or the lower wall of the fume hood is a hollow structure, and the air supply passage is provided on the side wall and/or the lower wall of the cabinet.

Preferably, the method further comprises:

a sliding door provided at the opening, the sliding door being slidable along the opening for adjusting the open area of the opening;

The top passage, the top passage connects the cabinet body to the outside of the cabinet, and the top passage outlet is located in the cabinet body.

Wherein, the fume hood is arranged such that when the exhaust vent is exhausted, 40% to 69% of the exhaust air volume is supplemented by the airflow sent by the air supply port.

Preferably, the outer side wall of the air supply opening is located in the same vertical plane as the outer side wall of the sliding door, so that the upward air supply flow sent through the air supply opening covers the opening of the cabinet.

Further, it also includes:

a position sensor for detecting the position of the sliding door; and,

a control unit connected to the position sensor,

The guide plate further includes an adjustment plate, the adjustment plate is hinged with the guide plate, and the control unit controls the rotation of the adjustment plate according to the detection information of the position sensor, and is used for adjusting the air volume distribution of the inner air supply port and the outer air supply port separated by the guide plate.

The embodiment of the invention further provides a control method for the above fume hood, comprising:

When the movement of the sliding door causes the opening degree of the opening to be 0% to 4%, the free end of the adjusting plate is set to be in contact with the bottom plate of the air supply passage, that is, the outer air supply opening is closed;

When the movement of the sliding door causes the opening degree of the opening to be 5% to 60%, the free end of the adjusting plate is set to be less than or equal to 40% of the height of the supplementary air passage;

When the sliding door moves to cause the opening degree to be 61% to 100%, the free end of the adjusting plate is set to be less than or equal to 70% of the height of the supplementary air passage.

Further, when the fume hood is exhausted, 40% to 69% of the exhaust air volume is replenished by the airflow sent from the air supply port.

The fume hood provided according to the embodiment of the present invention excludes all the exhaust airflow discharged to the fume hood from the active replenishing airflow of the air supply system or all the safety replenishment supplemented by the passive replenishing airflow outside the cabinet, through the cabinet only The air inlet is arranged below the body opening, and the air volume, the active air volume and the passive air volume are controlled (refer to when the air exhaust system exhausts air from the fume hood, the ambient air outside the fume hood is affected by the negative pressure formed by the exhaust air. The ratio of the airflow to the fume hood is such that the opening of the fume hood forms a unidirectional airflow always facing the venting opening in the cabinet, thereby ensuring the safety of the user and effectively preventing the harmful gas in the cabinet from overflowing. In addition, compared with the prior art, when three air supply ports are provided, it is necessary to precisely control the air supply volume of the three air supply ports, otherwise there is a risk of loss once the balance effect and safety are lost. The structure of the multiple air inlets is simpler, the production cost is lower, and the safety factor is increased.

DRAWINGS

Figure 1 shows a fume hood of the prior art;

Figure 2 shows another fume hood of the prior art;

3 is a schematic structural view of a fume hood provided by an embodiment of the present invention;

Figure 4 is a plan view showing the structure of Figure 3;

Figure 5 is a schematic cross-sectional view of the air inlet;

6 is a schematic cross-sectional view of a air inlet of a fume hood according to another embodiment of the present invention;

7 is a schematic structural view of a deflector of a fume hood according to an embodiment of the present invention;

FIG. 8 is a schematic structural diagram of a fume hood provided by another embodiment of the present invention; FIG.

FIG. 9 is a schematic perspective structural view of a fume hood according to another embodiment of the present invention; FIG.

10-1 to 10-3 are schematic diagrams showing the air volume control state of the fume hood provided by an embodiment of the present invention;

FIGS. 11-1 and 11-2 according to an embodiment of the present invention the fume hood leak rate Q = detected _complement a perspective view and a side view of FIG. 40% × Q _rows;

11-3 and FIG. 11-4 are flow diagrams and flow velocity diagrams of a gas flow rate when a fume hood is _{supplemented by} 40%×Q _{rows according to an} embodiment of the present invention;

FIGS. 12-1 and 12-2 according to an embodiment of the present invention the fume hood leak rate Q = detected _complement a perspective view and a side view of FIG. 45% × Q _rows;

FIG. 12-3 and FIG. 12-4 are flow diagrams and flow velocity diagrams of a gas flow rate when the fume hood is _{supplemented by} 45%×Q _{rows according to an} embodiment of the present invention;

FIG. 13-1 and FIG. 13-2 are a perspective view and a side view of a leakage rate detection diagram of a fume hood with a Q _compensation =60%×Q _{row according to an} embodiment of the present invention;

13-3 and FIG. 13-4 are flow diagrams and flow velocity diagrams of a gas flow rate when a fume hood is _{supplemented by} 60%×Q _{rows according to an} embodiment of the present invention;

FIGS. 14-1 and 14-2 according to an embodiment of the present invention the fume hood leak rate Q = detected _complement a perspective view and a side view of FIG. 69% × Q _rows;

Figure 14-3 and 14-4 provided in the fume hood Q = 69% × Q _complement the _exhaust gas flow rate and gas flow velocity flow diagram embodiment of the present invention, FIG cut;

FIGS. 15-1 and 15-2 according to an embodiment of the present invention the fume hood leak rate Q = detected _complement a perspective view and a side view of FIG. 70% × Q _rows;

FIGS. 15-3 and 15-4 provided in the embodiment of the fume hood _complement Q = _exhaust flow velocity and the gas flow velocity flow diagram of FIG 70% × Q section of the present invention.

Detailed ways

Preferred embodiments of the present invention will now be described in detail in conjunction with the drawings. Although the description of the present invention will be described in conjunction with the preferred embodiments, it is not intended that the features of the invention are limited to the embodiments. Rather, the invention is described in connection with the embodiments so as to cover other alternatives or modifications that are possible in the embodiments of the invention. In order to provide a thorough understanding of the present invention, many specific details are included in the following description. The invention may also be practiced without these details. In addition, some specific details are omitted in the description in order to avoid obscuring or obscuring the present invention.

In addition, "upper", "lower", "left", "right", "top", "bottom", "front", "back", "inside", "outside", etc., used in the following description The orientation word is defined based on the spatial position of the fume hood when used by laboratory personnel, and should not be construed as limiting the invention.

FIG. 3 is a schematic structural diagram of a fume hood according to an embodiment of the present invention. As shown in FIG. 3, the fume hood may include a cabinet 100 having an opening 101 on the front side, an air outlet 201, a supplemental air passage 301, and a deflector 400. The air outlet 201 in the communication cabinet 100 is disposed on the back side of the top of the cabinet 100. The air supply passage 301 may include a air supply port 302, wherein the air supply port 302 is disposed below the cabinet opening 101, and the air supply channel 301 is disposed at the bottom of the cabinet 100. The deflector 400 stands on the rear side of the cabinet 100, and includes a substrate and an inclined portion 404, wherein the substrate is vertically set, the inclined portion 404 is located above the substrate, and is inclined from the bottom to the direction of the exhaust port 201. The upper end of the inclined portion 404 is close to the top of the cabinet 100, the lower end is close to the substrate, and the inclined portion 404 is close to the top of the top of the cabinet 100 and the top of the cabinet 100 is left with a gap 405; as shown in FIG. 3, the inclined portion 404 is provided. When the front end covers the air discharge opening 201 when viewed from below, that is, when viewed from the lower side of the inclined portion 404, the front end of the inclined portion 404 is further forward with respect to the side wall on the front side of the air discharge opening 201. Moreover, a gap 405 or an aperture is provided between the deflector substrate and the bottom of the cabinet 100, between the inclined portion 404 and the substrate to allow airflow to pass from the void 405 or the aperture. In other embodiments, the inclined portion 404 covers the vent 201 in a bottom view.

Exhaust air refers to the discharge of gas from the cabinet inside the fume hood. In the embodiment of the present invention, all the gases in the fume hood are discharged through the exhaust port 201. When the fume hood provided by the embodiment of the present invention is exhausted, the supplementary gas is replenished into the cabinet through two ways: one is active air supply, that is, the supplementary gas is actively sent into the cabinet by the air supplement system; the other is Passive air supply, that is, the negative pressure caused by the exhaust gas being exhausted or drawn into the cabinet. In the working state, the exhaust air volume and the air volume are in equilibrium, that is, the exhaust air volume (Q _row ) = air volume = active air volume (Q _compensation ) + passive air volume (Q _suction ).

In the fume hood provided by the embodiment, the air outlet 201 can be externally connected to the exhaust system of the laboratory where the fume hood is located, or the exhaust system of the building where the fume hood is located, to finally discharge the gas in the fume hood outside the laboratory or Outside the building; similarly, the air supply passage 301 can be connected to the air supply system of the laboratory where the fume hood is located, or the air supply system of the building where the external fume hood is located. When the fume hood is in operation, under the action of the above exhaust system, the gas in the fume hood is discharged through the exhaust vent 201, thereby generating a negative pressure in the cabinet 100 of the fume hood; meanwhile, under the action of the above-mentioned air supply system The outside fresh air is sent to the cabinet through the air supply port 302 located below the opening 101 of the cabinet 100 along the air supply passage 301 to form a supplemental air flow. A portion of the supplemental airflow is sucked by the exhaust system, and the gas or particulate matter in the portable cabinet passes between the gap between the substrate disposed on the deflector 400 and the bottom of the cabinet 100, between the inclined portion 404 and the substrate of the deflector 400. The gap 405, along the passage between the deflector 400 and the rear side wall of the cabinet 100, reaches the exhaust vent 201, and is finally discharged to the exhaust system through the exhaust vent 201; the other part of the supplemental airflow is affected by the exhaust negative pressure After the air supply port 302 is sent out, the gas or particulate matter in the carrying cabinet directly flows upward and backward to the air outlet 201, and is discharged to the fume hood. At this time, the air volume of the supplement airflow is set to be smaller than the air volume of the exhaust air, and the airflow of the air supplemented by the active supplement is insufficient to fill the space left by the gas in the original cabinet, so that the air outside the cabinet outside the opening 101 of the cabinet 100 is also exhausted. The effect of the system suction is again wrapped by the supplemental airflow sent from the air inlet 302 and passively flows toward the exhaust port 201 together with the supplemental airflow. Under the above arrangement, the passive air supply flow from the outside of the cabinet 100 into the cabinet 100 forms a unidirectional airflow from the outside to the inside at the opening 101, thereby ensuring that no gas in the cabinet overflows from the opening 101 of the cabinet 100. Outside the cabinet 100.

Therefore, the fume hood provided in the embodiment provides only the air supply port 302 for actively supplementing the air in the cabinet 100, so that the active air volume and the exhaust air volume form Q _compensation = (40% - 69%) × Q _row relationship; wherein, Q is the _{make up} air damper automatically fill up via the outlet 302, Q 201 to _discharge exhaust air flow discharged through the exhaust port.

When the fume hood is working, the working area in the cabinet 100 as a laboratory experiment for chemical experiments, there will be particulate matter, which is likely to be harmful to the human body. When the exhaust system is working, suction is formed in the cabinet 100 to form a traction effect on the particulate matter, which may be referred to as “pull” as an image; when the air supplement system is working, the supplemental airflow sent from the air inlet 302 may Pushing the particles moving in the direction of airflow can be aptly called "push".

Figure 4 is a plan view showing the structure of Figure 3; Wherein 510 represents the width direction; 520 represents the length direction. As shown in FIG. 4, in the present embodiment, the air outlet 201 is cylindrical and is mounted on the side of the top of the cabinet 100 away from the opening 101, that is, from the left or the right side, the center of the air outlet 201 is located. The center of the cabinet 100 is located on the rear side; and its central axis is located in the width direction 510 or in the middle of the cabinet 100, that is, the center of the air outlet 201 is located at an intermediate position on the left and right sides of the cabinet 100 as viewed from the front side. As shown in FIG. 4, A is the width of the fume hood cabinet 100, and the distance from the center of the air outlet 201 to the left and right sides of the fume hood is one-half of the width of the fume hood cabinet 100, that is, A/2. . In other embodiments, in order to better fit the space in the cabinet 100, the air outlet 201 may be disposed in the middle of the cabinet 100, that is, from the center of the air outlet 201 to either side of the cabinet 100. The distance is one-half the width of the fume hood cabinet 100. With such an arrangement, the air outlet 201 can efficiently perform the air exhausting action.

In another embodiment of the present invention, the central axis of the air vent 201 is spaced from the rear wall of the cabinet 100 in the longitudinal direction 520 by a quarter of the length of the cabinet 100, that is, viewed from the left or right side. The center of the tuyere 201 is located between the front and rear sides of the cabinet 100 and a quarter of the rear side. Such positioning facilitates the effect of "pulling" of the exhaust fan, and can stabilize the airflow without turbulence.

As shown in FIG. 3, the outside of the air supply port 302 is located in the same vertical plane as the inner side of the front portion of the cabinet 100. Such an arrangement allows the supplemental airflow sent through the air supply port 302, in particular the upward supplemental airflow, to cover the cabinet opening 101. In the present embodiment, the air supply opening 302 extends along the cabinet 100 in the width direction. When viewed from the front side, the width is equal to or larger than the width between the left and right sides of the cabinet 100, so that the air supply air sent by the air supply port 302 is directed to the opening 101. Both ends extend and cover the opening 101. As shown in FIG. 3, the cross section of the air supply opening 302 perpendicular to the width direction is curved, that is, the arc side connection between the top side and the rear side of the air supply port 302 is seen from the left or right side; the air supply port 302 faces upward and At the rear, the wind supplied from the air supply port 302 is directed upward and inside the cabinet 100. In other embodiments, the air inlet 302 may also have a quarter arc shape in cross section.

Figure 5 is a schematic cross-sectional view of the air inlet. As shown in FIG. 5, in the present embodiment, a guide plate 310 is disposed in the air supply port 302, and the guide plate 310 divides the air supply port 302 into an outer air supply port 311 and an inner air supply port 312. In addition, the cross section of the guide plate 310 perpendicular to the width direction is curved to guide the direction of the air supply flow from the inner air supply port 312. In other embodiments, the guide plate 310 may also have an inverted L shape or a sickle shape. Preferably, the guide plate 310 substantially divides the air supply port 302 into two portions having the same area in the horizontal direction. The lower end portion 313 of the guide plate 310 is located in the supplemental air passage 301. It will be understood by those skilled in the art that adjusting the position of the lower end portion 313 can control the distribution of the supplemental air volume of the outer air supply port 311 and the inner air supply port 312. Therefore, the function of the guide plate 310 is to change the wind direction and distribute the air volume.

When the ventilating cabinet provided in this embodiment is operated, the air supply airflow passes through the air supply passage 301, and is divided into two airflows by the guide plate 310 to flow to the inner air supply port 312 and the outer air supply port 311, respectively. The proportion of the air distribution of the inner and outer air inlets is determined by the distance between the lower end of the guide plate 310 and the bottom plate of the air supply passage 301. The greater the distance, the greater the outside air flow 311 of air tuyere (Q _{up outside),} the inner air flow outlet 312 of the complement (Q _{within complement)} smaller; contrary, the smaller the distance, the outer outlet 311 up air volume (Q _{complement The} smaller the _outer ), the larger the air volume of the inner air inlet 312 ( _within Q); the wind volume Q _complement = Q _complement + Q _complement . The outer air-filling port 311 forms an upward air curtain, which reduces the influence of disturbances in the laboratory on the airflow organization in the cabinet 100; the air supply from the inner air-filling port 312 is "pushed", and the air-discharging system is "pushed", and the two form together. "Pushing and pulling", the harmful gas is sent between the deflector 400 and the rear wall of the cabinet 100, and finally is taken away by the exhaust system. Due to the suction function of the exhaust system, a "flow guide groove" is formed between the deflector 400 and the rear wall of the cabinet 100, and it is impossible for the air to flow in the direction of the opening 101 after being trapped in the "flow guide groove". Therefore, it is completely discharged from the exhaust vent to ensure safety.

The guide plate 310 in this embodiment forms a restriction on the flow of the airflow in some directions due to the guiding action, and causes a certain loss to the airflow pressure. When the arc is designed, the pressure loss caused by the flow of the airflow is small.

FIG. 6 is a cross-sectional view of a supplemental air inlet 302 of a fume hood according to another embodiment of the present invention. As shown, the cross section of the air inlet 302 perpendicular to the width direction may also be chamfered, that is, viewed from the left or right side, the top side and the rear side of the air supply port 302 are chamfered.

FIG. 7 is a schematic structural diagram of a deflector of a fume hood according to an embodiment of the present invention. As shown in FIG. 7 , preferably, the deflector 400 is provided with a plurality of through holes 401 , and the through holes 401 located in the lower portion 402 of the baffle are uniformly distributed in the horizontal width direction; the through holes 401 located on the deflector upper portion 403 are The proportion of the area of the hole to the upper area is gradually reduced with respect to the area per unit area.

In other embodiments, the through holes 401 disposed on the deflector upper portion 403 are gradually increased from bottom to top, and the arrangement is gradually thinned, or the hole area of the single through hole 401 is gradually reduced. In another embodiment, the through hole 401 provided in the deflector upper portion 403 is radially radiated from the top to the bottom in the width direction, that is, the arrangement of the through hole 401 is narrowed from the center as viewed from the front side. width.

In this embodiment, the lower portion 402 of the deflector and the upper portion 403 of the deflector are integrally disposed to form a deflector substrate; the arrangement of the through holes 401 on the deflector substrate is the same as the deflector upper portion 403 and the deflector The arrangement on the lower portion 402. In other embodiments, the deflector upper portion 403 and the baffle lower portion 402 can also be provided separately. Regardless of whether the deflector upper portion 403 and the deflector lower portion 402 are separately disposed, a gap 405 is preferably left between the deflector lower portion 402 and the deflector upper portion 403 to allow airflow to be received by the exhaust vent 201 at the deflector 400 The negative pressure formed between the rear walls of the cabinet 100 passes through the baffles 400 along the gaps 405 or through holes 401 to control the flow of the air. When the fume hood provided in this embodiment is in operation, the inner air supply port 312 relies on the positive static pressure and kinetic energy of the air supply to push the higher concentration pollutants to the lower portion 402 of the deflector, and the pollutant passes through the lower portion 402 of the baffle and is followed by the rear. The negative pressure passage is sucked away; the outer air supply opening 311 generates a vertical upward air curtain, which blocks the air flow inside and outside the opening 101, preventing the disturbance outside the cabinet or the "cylinder flow effect" generated by the human body in front of the cabinet, thereby affecting the internal airflow of the cabinet 100. .

The so-called "cylinder flow around" means that when the fluid flows around the cylinder, the flow cross section shrinks, the flow velocity increases along the path, and the pressure decreases along the path. Due to the viscous force, the boundary layer separation occurs around the cylinder. Form a flow around the cylinder.

In some prior art, the fume hood is designed to supplement the wind only in a passive manner during exhaust, and all of the exhaust gas is passively replenished by air from outside the cabinet and through the opening, that is, all the supplemental airflow Both need to be sucked into the cabinet through the opening from the outside to the inside. At this time, any physical obstruction and interference at the opening section or before the opening, such as the person walking in front of the opening, the operator blocking the opening or the instrument placed in front of the opening, will result in the destruction of the stability of the airflow in the cabinet. Causes "cylinder flow around". If the stability of the airflow in the cabinet is destroyed, turbulence will occur, which will cause the risk of gas in the cabinet spilling out of the cabinet.

FIG. 8 is a schematic structural diagram of a fume hood provided by another embodiment of the present invention. As shown in FIG. 3 and FIG. 8 , an inclined portion 404 connected to the deflector upper portion 403 is further disposed on the deflector 400 near the top wall of the cabinet 100, and a gap is left between the inclined portion 404 and the deflector upper portion 403. 405. As shown in FIG. 8, an inclined plate 104 is disposed above the opening 101 of the fume hood; the upward extending direction of the inclined plate 104 forms an angle (not shown) with the upward extending direction of the inclined portion 404.

Generally speaking, in the working cabinet, the pollution source is generally placed on the bottom end surface of the cabinet 100, such as a beaker, a heating magnetic stirrer, etc., so the concentration of the pollutants in the cabinet 100 in the height direction of the fume hood is The closer the concentration is to the bottom of the cabinet 100, the lower the concentration from the bottom of the cabinet 100 (such as the top of the cabinet 100). The airflow organization design concept in the fume hood provided by this embodiment is:

1. By appropriately setting the size of the gap between the lower portion 402 of the deflector and the bottom of the cabinet 100 and the sum of the areas of the holes of the plurality of through holes 401 provided in the lower portion 402 of the deflector, through the air outlet The air volume discharged by 201 accounts for 60% of the exhaust air volume;

2. By appropriately setting the size of the gap between the deflector upper portion 403 and the deflector lower portion 402 and the sum of the hole areas of the plurality of through holes 401 provided on the deflector upper portion 403, the exhaust air is exhausted there. The air volume discharged by the port 201 accounts for 25% to 30% of the exhaust air volume;

3. By appropriately arranging the size of the gap between the inclined portion 404 of the deflector 400 and the deflector upper portion 403 and the size of the gap between the inclined portion 404 and the top of the cabinet 100, it is discharged to the exhaust port 201 therethrough. The air volume accounts for 10% to 15% of the exhaust air volume;

Due to the principle of fluid mechanics, the closer to the exhaust port 201, the greater the negative pressure. The lower portion 402 of the deflector away from the exhaust port 201 has a relatively small negative pressure due to pressure loss along the path resistance.

The design of the deflector 400 needs to comply with the above requirements and meet the following characteristics:

1. The through hole 401 on the lower portion 402 of the deflector has a large or dense opening, which satisfies the requirement of airflow of 60% of the exhaust air. At the same time, the opening position thereof can ensure that the surface wind speed passing through the lower portion 402 of the deflector in the width direction is uniform.

2. The through hole 401 on the deflector upper portion 403 is opened from bottom to top, the area of a single opening is getting smaller and smaller, the arrangement between rows and rows is more and more sparse, and the number of openings per row is less and less, The requirement that the amount of air entering the baffle 400 is reduced from bottom to top is ensured.

3. The inclined portion 404 of the deflector 400 and the top portion of the cabinet 100 and the deflector upper portion 403 are left with a gap 405. The size of the void 405 can be derived from fluid analysis of CFD (Computational Fluid Dynamics). Excessive clearance can cause contaminants to escape from the deflector upper portion 403 and the baffle lower portion 402 directly to the top, creating turbulence at the top, increasing the risk of spilling out of the cabinet 100.

In another embodiment of the present invention, the supplemental air passage 301 is further connected with a supplemental air blower, and the supplemental air blower is a power adjustable wind turbine. In other embodiments, the supplemental fan may also be disposed in the supplemental air passage 301. Further, the supplemental air passage 301 can also be connected to the supplemental air valve, and the supplemental air valve can be a variable opening valve.

In another embodiment of the present invention, the lower wall of the fume hood is a hollow structure, and the air supply passage 301 is disposed at a lower wall of the cabinet 100. In addition, the top wall of the cabinet 100 may also be a hollow structure. Therefore, the air supply passage 301 can also pass through the top wall and the lower wall of the cabinet 100. In other embodiments, the effectively sealed top, bottom, and side walls of the hollow structure may themselves be used as the supplemental passage 301.

FIG. 9 is a schematic perspective structural view of a fume hood according to another embodiment of the present invention. As shown in FIG. 9, the fume hood provided by this embodiment further includes a sliding door 106 disposed at the opening 101. The sliding door 106 can slide along the opening 101 for adjusting the open area of the opening 101. The fume hood further includes a top passage. 105. The top passage 105 communicates with the external environment in the cabinet 100. One end of the top passage 105 is disposed outside the cabinet 100, and may be disposed at the top of the cabinet 100 as an inlet. The other end is disposed in the cabinet 100 as an outlet. In addition, the outer side wall of the air supply port 302 and the outer side wall of the sliding door 106 are located in the same vertical plane, so that the air supply air sent through the air supply port 302, especially the upward air supply airflow, covers the cabinet opening 101. In other embodiments, in order to smooth the sliding of the sliding door 106 relative to the cabinet 100, a large gap is often left between the sliding door 106 and the cabinet 100. Therefore, controlling the gap to function as the top passage 105 is also one of the optional technical means, which has the advantage that it is not necessary to separately provide the top passage 105, which simplifies the structure.

When the fume hood provided in this embodiment is in operation, the gas of the top passage 105 located near the outer end of the cabinet 100 is affected by the suction of the exhaust port 201, and enters the cabinet from the outside of the fume hood through the top passage 105 or the area corresponding to the top passage. Inside, it is used to eliminate the polluting gas that may exist on the front side in the upper part of the cabinet 100. At this time, the top passage 105 is controlled to provide a small proportion of passive air volume corresponding to 5% to 10% of the exhaust air volume in the cabinet, thereby ensuring a large intercepting capability of the polluting gas and eliminating the polluting gas in the cabinet. The risk of spilling out of the cabinet and without the need for an additional fan to blow air through the top passage 105 into the cabinet.

From another perspective, the top passage 105 is configured as a means of stabilizing the airflow within the cabinet. The internal physical structure of the fume hood determines that a vortex is generally generated at the top of the cabinet 100 near the opening 101, and the air located in the vortex is difficult to be discharged. The top passage 105 is disposed such that air drawn into the cabinet 100 through the top passage 105 breaks the vortex and "pushes" the vortex-forming gas "toward" the deflector 400 and the vent 201, thereby preventing gas in the cabinet from The opening 101 overflows to make the fume hood safer. It will be understood by those skilled in the art that the above-described vortex is located just near the mouth and nose of the operator standing in front of the cabinet opening 101, so that the presence of eddy currents at this location is the most dangerous, especially when the sliding door 106 is in the open state.

By intentionally designing the structure of the fume hood, such as adjusting the position of the lower end portion 313 of the guide plate 310 in the air supply passage 301, or adjusting the height of the sliding door 106, when the fume hood provided in this embodiment is operated, the amount of replenishing air is 40. % to 69% is provided by the air supply port 302, and the remaining 31% to 60% is provided by other means. For example, in the present embodiment, 31% to 60% of the amount of replenishing air is provided by the door opening 101 and the top passage 105. The best condition is that the air volume distribution ratio is:

Q _complement = 60% × Q _row ;

Q _gate = 30% × Q _row ;

Q _side = 10% × Q _row ;

Q _suction = Q _door + Q _side .

The Q _row is the exhaust air volume, the Q _compensation is the active air supply volume sent through the air supply port 302, and the Q _door is the passive air supply volume that is drawn into the cabinet 100 from the outside of the cabinet 100 through the opening 101, _{next to the} Q The amount of passive air charge that is drawn into the cabinet 100 from the outside of the cabinet 100 via the top passage 105.

Thus, the contaminants generated by the experiment are evacuated from the exhaust port 201 through the negative pressure passage formed by the deflector 400 and the deflector 400 and the rear side wall of the cabinet 100.

1. When the amount of pollutants is small or medium, the pollutants are directly withdrawn from the lower portion 402 of the deflector;

2. When the volume of the contaminant is large, the contaminants are removed from the lower portion 402 of the baffle and the upper portion 403 of the deflector

3. When the volume of the contaminant is extremely large, the contaminants that have not been evacuated through the lower baffle plate 402 and the deflector upper portion 403 rise to the top, and are drawn away through the upper and lower slits of the inclined portion 404 of the baffle 400.

In the above embodiment, the distribution of the supplemental air volume can be controlled by the position of the lower end portion 313 of the guide plate 310. In other embodiments, an adjustment plate 314 can also be hinged on the guide plate 310. The adjustment plate 314 can be rotated about the hinge. The adjustment plate 314 is a fixed end near the hinge and the other end is a free end. Thus, by controlling the position of the free end of the adjustment plate 314, the function of controlling the distribution of the supplemental air volume can also be achieved. In addition, the adjustment plate 314 and the sliding door 106 may be connected by other mechanical structures, such as the elastic bead structure, to realize the positional change of the sliding door 106 to trigger the position adjustment of the adjustment plate 314.

10-1 to 10-3 are schematic diagrams showing the air volume control state of the fume hood according to an embodiment of the present invention. As shown, C is the distance between the free end of the adjustment plate 314 and the lower floor of the supplemental passage 301; D is the distance between the lower end of the sliding door 106 and the air inlet 302. The three working conditions used by the fume hood are generally:

1. Sliding door 106 is closed, experimental non-operating state or no supervision experiment is required. At this time, the movement of the sliding door 106 causes the opening degree of the opening 101 of the cabinet 100 to be 0% to 4%, and the free end of the adjusting plate 314 is set to be in contact with the bottom plate of the supplementary air passage 301, that is, the outer air filling port 311 is closed, and Q _complement = Q is _filled. ;

2. The opening degree of the sliding door 106 is 5% to 60%, and the experimenter needs to carry out an experimental operation in the cabinet. At this time, the free end of the adjusting plate 314 is set to be 40% of the height of the air supply passage 301, and in this state, Q _{complements the outer} = 40% × Q _complement , Q _{fills the inner} = 60% × Q _supplement

3. The sliding door 106 is fully open, usually there is an experiment where the experimenter performs the experimental operation at this height, and the free end of the adjusting plate 314 is set to be 70% of the height of the supplementary air channel 301 from the bottom of the supplementary air channel 301, In this state, Q _{complements the outside} = 70% × Q _complement , Q _complement = 30% × Q _complement .

10-1 to 10-3, a control method of a fume hood provided by an embodiment of the present invention can be used. The fume hood provided by this embodiment can further ensure safety by precise automatic control and prevent harmful gas from overflowing in the cabinet.

In this embodiment, the fume hood further includes:

a position sensor for detecting a position of the sliding door 106;

a control unit electrically connected to the position sensor,

The guide plate 310 further includes an adjustment plate 314, and the adjustment plate 314 is hinged with the guide plate 310. During operation of the embodiment, the control unit controls the adjustment plate 314 to rotate by a certain angle according to the detection information of the position sensor for adjusting the air volume distribution of the inner and outer air supply ports separated by the guide plate 310.

As shown in FIG. 10-2 to FIG. 10-3, C is the distance between the free end of the adjusting plate 314 and the lower bottom plate of the supplementary air passage 301; D is the distance between the lower end portion of the sliding door 106 and the air filling port 302.

The control method of this embodiment is separately controlled according to the following working states, and the three working states used by the fume hood are generally:

2. The opening degree of the sliding door 106 is 5% to 60%, and the experimenter needs to carry out an experimental operation in the cabinet. At this time, the free end of the regulating plate 314 is set to the base plate 301 and the distance from the auxiliary gas passage 301 of the auxiliary gas passage is 40% of the height of the _outer Q = 40% × Q _fill _up, _{the complement} Q = 60% × Q _fill;

3. The sliding door 106 is fully open, usually there is an experiment where the experimenter performs the experimental operation at this height, and the free end of the adjusting plate 314 is set to be 70% of the height of the supplementary air channel 301 from the bottom of the supplementary air channel 301, Q _{complement outside} = 70% × Q _complement , Q _{fill within} = 30% × Q _complement .

In the present embodiment, when the fume hood is exhausted, according to the sensing unit's perception of the position of the sliding door 106, the control of the rotation angle of the adjusting plate 314 can achieve the following effects: 40% to 69% of the replenishing air volume is provided by the air supply port 302. Provided that 31% to 50% of the air volume is provided by the cabinet door opening 101, and the remaining air volume is provided by the top passage 105.

The beneficial effects of the embodiments provided by the present invention are explained below based on experimental data. According to the ANSI/ASHRAE 110-2016 standard requirements, “the leakage of the exhaust cabinet does not exceed AM0.05PPM (5e-08PPM)”. Among them, ANSI is the American National Standards Institute, which sets standards; ASHRAE is the American Society of HVAC Engineers, which sets standards for testing based on standards.

CFD fluid partition physical model and boundary conditions description: SF6 tracer gas generator according to ANSI/ASHRAE 110-2016 standard injection flow rate is 4L / min, the experimental parameters and results are as follows:

Set _up experimental parameters Q = 480CMH, Q _row = 1200CMH, Q = _{the complement} of Q _rows × 40%, an amount of leakage -5.4396e-011PPM;

The experimental parameters are set to Q _complement = 540 CMH, Q _row = 1200 CMH, Q _complement = Q _row × 45%, the leakage amount is 8.8284e-011PPM;

Set _up experimental parameters Q = 720CMH, Q _row = 1200CMH, when Q _rows × 60% Q = _up, an amount of leakage -1.7025e-010PPM;

Set _up experimental parameters Q = 828CMH, Q _row = 1200CMH, when Q _rows × 69% Q = _up, an amount of leakage 1.4958e-009PPM;

The experimental parameters are set to Q _compensation = 840 CMH, Q _row = 1200 CMH, and Q _compensation = Q _row × 70%, the leakage amount is 4.0223e-008PPM.

It can be seen that, in the fume hood provided by the embodiment of the present invention, when the replenishing air volume is 40% to 69% of the exhaust air volume, the leakage amount is far lower than the standard requirement of 5e-08 PPM, and the safety requirement is completely satisfied. However, once Q _complement = Q _row × 70%, the leakage amount begins to approach the standard value, which means there is a safety hazard.

FIG. 11-1, 11-2 provided in the embodiment of the fume hood Q = leak rate _up perspective view of the detector and the _exhaust side 40% × Q of the present invention; FIGS. 11-3 and 11-4 embodiment of the invention FIG. The provided fume hood Q _complement = 40% × Q _row flow velocity flow diagram and air velocity cutaway view.

FIGS. 12-1 and 12-2 provided in the embodiment of the fume hood Q = leak rate _up perspective view of the detector and the _exhaust side 45% × Q of the present invention; FIGS. 12-3 and 12-4 embodiment of the invention FIG. The provided fume hood Q _complement = 45% × Q _row flow rate flow line diagram and air flow velocity cutaway view.

FIGS. 13-1 and 13-2 provided in the embodiment of the fume hood Q = leak rate _up perspective view of the detector and the _exhaust side 60% × Q of the present invention; FIGS. 13-3 and 13-4 embodiment of the invention FIG. The provided fume hood Q _complement = 60% × Q _row flow velocity diagram and airflow velocity cutaway.

FIGS. 14-1 and 14-2 provided in the embodiment of the fume hood Q = leak rate _up perspective view of the detector and the _exhaust side 69% × Q of the present invention; FIGS. 14-3 and 14-4 embodiment of the invention FIG. The provided fume hood Q _complement = 69% × Q _row flow velocity diagram and airflow velocity cutaway.

From the above Q _complement = (40% to 69%) × Q _row , each leak rate detection map is a perspective view and a side view showing the range of the tracer gas concentration volume component at 0.01 PPM. The tracer gas leakage rate required by the ANSI/ASHRAE110-2016 standard is not more than 0.05 PPM. The figure shows the position of the boundary surface when the concentration of the tracer gas (SF6 sulfur hexafluoride) is 0.01 PPM. It can be seen that The tracer gas is discharged without being diffused to both sides, and its boundary is always not overflowed in the working chamber of the exhaust cabinet. The fume hood has strong interception capability and no leakage on both sides, achieving "no leakage" safety performance.

From the above Q _complement = (40% ~ 69%) × Q _row flow velocity diagram, the internal airflow is organized into a laminar flow state, which is good to prevent the overflow of internal pollutants. Fill up air outlet 302 away from the lower main deflector 402 rows, an outer opening up air damper passive Q cabinet _door down mainly by the spoiler discharge portion 403, top up air damper 105 via a passive Q is mainly composed of _side guide The inclined portion 404 of the flow plate 400 is drained away, which fully meets the safety design requirements. At this time, the air discharge amount of the gap between the inclined portion 404 of the deflector 400 and the deflector upper portion 403 is 10%, the exhaust air amount of the deflector upper portion 403 is 30%, and the air discharge amount of the lower portion 402 of the deflector is 30%. 60%.

It is worth noting that for the fume hood, the most important thing is not only that there is no overflow at the opening of the sliding door. In the optimal state, the air moving inside the cabinet can not be disturbed or any reverse movement.

From the above Q _compensation = (40% to 69%) × Q _row , the airflow velocity cutaway diagram shows that the airflow jet of the air inlet 302 is a fan-shaped laminar flow structure without any spoiler or reverse air flow. The importance here is that if the air inlet, the air volume, the arrangement of the interior space of the cabinet and the design of the deflector are insufficient, the arrows in the figure will be vertically pointed or pointed in the opposite direction. In addition to the air close to the air outlet 201 or the air between the deflector 400 and the rear wall of the cabinet 100, if there is an arrow in the cabinet 100 that is vertically pointed upward or downward, or an arrow pointing in the reverse direction, the cabinet 100 is indicated. The fluid structure inside is turbulent, and there are eddy currents, counterflows and spillage risks during operation, which destroy the most basic safety performance requirements of the fume hood.

FIGS. 15-1 and 15-2 provided in the embodiment of the fume hood _complement Q = detected FIGS perspective view and a side leak rate of the _exhaust 70% × Q of the present invention; FIGS. 15-3 and 15-4 embodiment of the invention FIG. The provided fume hood Q _complement = 70% × Q _row flow velocity diagram and airflow velocity cutaway.

As can be seen from Fig. 15-2, the tracer gas (represented by the black portion in the cabinet) has overflowed from the opening 101 to the outside of the cabinet 100, and the ventilation cannot be satisfied when the fume hood is set to Q=70%×Q row. The safety performance requirements of the cabinet.

As can be seen from Figure 15-1, the boundary surface of the tracer gas with a concentration of 0.01 PPM extends to the left and right sides of the fume hood. At this time, the flow rate of the passive supplementary airflow entering the cabinet 100 via the opening 101 is low, and since the left and right sides of the cabinet are far from the air outlet 201, the tracer gas is difficult to be pushed by the supplementary airflow to the air outlet 201, so the pollution There is a risk that the object will overflow outside the opening 101.

In the embodiment of the present invention, the air supply port 302 is divided into the outer air supply port 311 and the inner air supply port 312 by the guide plate 310. However, those skilled in the art can understand that the air supply port 302 can be divided into multiple guide plates 310. Since the outer air supply port 311 and the plurality of inner air supply ports 312 are provided, the number of the guide plates 310 and the number of the inner side air supply opening 312 and the outer side air supply opening 311 are not limited in the present invention.

The fume hood provided by each embodiment of the present invention breaks the prior knowledge that the fume hood must pass through the air supply or must isolate the inner cavity of the fume hood from the external environment to prevent the harmful gas inside the fume hood from overflowing. For example, Le Youfen and others in the "Research and Application of Air Curtain Ventilation Cabinets" (Journal of Nanhua University (Technology Edition): March 2002, Vol. 16 No. 1: 44-49) pointed out that The type of exhaust cabinet is because the compensation wind provided by 1) easily interferes with the surface wind speed and destroys the sealing effect of the exhaust cabinet. Obviously, the author believes that there is a “closed effect of easily damaging the exhaust cabinet” in the air-filled exhaust cabinet, resulting in a row. The problem of gas overflow in the wind cabinet.

The fume hood provided by the embodiments of the present invention is not imprisoned in the original understanding of the fume hood, and creatively guides the external environment of the fume hood to make the external airflow originally considered to be interference closed into a passive The “beneficial” airflow that works together with the active supplemental airflow and cooperates with each other.

The fume hood provided according to the embodiment of the present invention excludes all the exhaust airflow discharged to the fume hood from the active replenishing airflow of the air supply system or all the safety replenishment supplemented by the passive replenishing airflow outside the cabinet, through the cabinet only The air inlet 302 is disposed below the opening 101 of the body 100, and the ratio between the exhaust air volume, the active air volume, and the passive air volume is controlled to form a unidirectional airflow always facing the air outlet of the cabinet at the opening 101 of the fume hood. Therefore, the safety of the user can be ensured, and the harmful gas in the cabinet can be effectively prevented from overflowing. In addition, compared with the prior art, when three air supply ports are provided, it is necessary to precisely control the air supply volume of the three air supply ports, otherwise, if the balance is lost, the effect and safety may be lost. Therefore, since only one air supply port is provided in the present invention, Compared with a plurality of air inlets, the structure is simpler, the production cost is lower, and the safety factor is increased.

Claims

A fume hood includes a cabinet having an opening on the front side, and further comprising:

Connecting the air outlet of the cabinet body, the air outlet is disposed at the back side of the cabinet body;

Including the air supply passage of the air inlet; and,

a baffle standing on the rear side of the cabinet body, the baffle comprising a substrate and an inclined portion, and a gap between the lower end of the substrate and the bottom of the cabinet, between the lower end of the inclined portion and the substrate ,

The air inlet is located below the opening, and the inclined portion is disposed such that the front end covers the air outlet when viewed from below.
A fume hood according to claim 1, wherein the center of the exhaust vent is located in the middle of the left and right sides of the cabinet as viewed from the front side; the vent is viewed from the left or the right side The center is located on the back side of the cabinet.
A fume hood according to claim 1, wherein the center of the exhaust vent is located between the front and rear sides of the cabinet and one quarter of the rear side as viewed from the left or right side.
A fume hood according to claim 1, wherein the width of the air supply opening is greater than or equal to the width of the cabinet when viewed from the front side, so that the air supply opening extends to the left and right ends of the opening and covers the Said opening.
A fume hood according to claim 1, wherein, viewed from the left or the right side, the top side and the rear side of the air supply opening are connected in an arc or a chamfer, so that the air supply opening is upward And send the wind backwards.
A fume hood according to claim 5, wherein said arc is a quarter arc.
A fume hood according to claim 1, wherein the outer side of the air supply opening is located in the same vertical plane as the inner side of the front part of the cabinet body, so that the upward air supply flow sent through the air supply port is covered. The opening of the cabinet.
A fume hood according to claim 1, wherein a guide plate is disposed in the air supply opening, and the guide plate divides the air supply opening into an outer air supply port pointing upward and pointing into the cabinet body. Inner air inlet.
A fume hood according to claim 8, wherein said guide plate has an arc shape in cross section for guiding the direction of the supplemental airflow sent through said inner air supply port.
A fume hood according to claim 8, wherein a lower end portion of the guide plate is located in the air supply passage, and a lower end portion is used for distributing the outer air supply port and the inner air supply port. Wind and wind volume.
A fume hood according to claim 1, wherein said baffle substrate is provided with a through hole, said through hole being evenly distributed in a horizontal width direction, and a hole area from a bottom to a top with respect to a unit area The proportion of the gradual decrease.
A fume hood according to claim 11, wherein said through holes are gradually increased in distance from bottom to top, or the hole areas of said through holes are gradually reduced.
A fume hood according to claim 11, wherein, viewed from the front side, the through holes provided in the deflector substrate are narrow and wide, and are radially arranged.
A fume hood according to claim 11, wherein the baffle substrate further comprises a lower portion of the deflector and a lower portion of the baffle, and a portion between the lower portion of the baffle and the upper portion of the deflector There are gaps.
A fume hood according to claim 1, wherein an inclined plate is disposed above the front side of the cabinet body; an upward extending direction of the inclined plate forms an angle with an upward extending direction of the inclined portion.
A fume hood according to claim 1, further comprising a supplemental fan connected to the supplemental air passage, wherein the supplemental fan is a power adjustable fan.
A fume hood according to claim 16, wherein said supplemental fan is disposed in said supplemental air passage.
A fume hood according to claim 1, further comprising a supplemental air valve in communication with the supplemental air passage, the replenishing valve being a variable opening valve.
A fume hood according to claim 1, wherein the side wall and/or the lower wall of the fume hood is a hollow structure, and the air supply passage is provided on a side wall and/or a lower wall of the cabinet body. .
A fume hood according to claim 1, further comprising:

a sliding door disposed at the opening, the sliding door is slidable along the opening for adjusting an open area of the opening; and a top passage connecting the cabinet to the outside of the cabinet The top passage outlet is located in the cabinet body.

Wherein, the fume hood is arranged such that when the exhaust vent is exhausted, 40% to 69% of the exhaust air volume is supplemented by the airflow sent by the air supply port.
A fume hood according to claim 20, wherein the outer side wall of the air supply opening is located in the same vertical plane as the outer side wall of the sliding door, so that the upward supplemental airflow sent through the air supply port is covered. The opening of the cabinet.
A fume hood according to claim 20, further comprising:

a position sensor for detecting a position of the sliding door; and

a control unit connected to the position sensor,

Wherein, the guiding plate further comprises an adjusting plate, the adjusting plate is hinged with the guiding plate, and the control unit controls the adjusting plate to rotate an angle according to the detecting information of the position sensor, and is used for adjusting the guiding plate The air distribution of the inner air inlet and the outer air inlet are separated.
A method of controlling a fume hood according to claim 22, comprising:

When the moving of the sliding door causes the opening degree of the opening to be 0% to 4%, the free end of the adjusting plate is set to be in contact with the bottom plate of the air supply passage, that is, the outer air supply opening is closed;

When the moving of the sliding door causes the opening degree of the opening to be 5% to 60%, the free end of the adjusting plate is set to be less than or equal to 40% of the height of the supplementary air channel. ;

When the moving of the sliding door causes the opening degree of the opening to be 61% to 100%, the free end of the adjusting plate is set to be less than or equal to 70% of the height of the supplementary air channel .
A control method for a fume hood according to claim 1 or 22, wherein when the fume hood is exhausted, 40% to 69% of the exhaust air volume is replenished by the air flow sent from the air supply port.