CN112710055B - Ventilation device with overwind channel - Google Patents

Abstract

A ventilation device with an air passage comprises a test support platform, a cabinet cavity arranged above the support platform, and a cavity wall body constructed as the cabinet cavity, the cavity wall body comprising a left cavity side wall and a right cavity side wall which are arranged on the left and right sides, and a cavity back wall located therebetween; the device is characterized in that it also comprises a lower air supply device arranged at the door sill position of the operating window, the lower air supply device comprises an air passage through which air supply air can flow, an air outlet of the air passage extends along the edge direction x of the support platform and its head and tail ends are respectively close to the left cavity side wall and the right cavity side wall of the cabinet cavity, the air passage is used to supply air from the outside of the cabinet cavity to the nearby area on the support platform surface, the air outlet comprises a head end air outlet expansion port, a tail end air outlet expansion port and a middle air outlet narrowing port located therebetween, the heights of the head end air outlet expansion port and the tail end air outlet expansion port relative to the support platform are respectively greater than the height of the middle air outlet narrowing port relative to the support platform.

Description

Ventilation equipment with air passage

Technical Field

The invention relates to a ventilation device for a laboratory, in particular to a ventilation device with an air passage.

Background Art

Various harmful gases will be generated during chemical experiments. In order to be able to immediately discharge the harmful gases nearby, fume hoods are often used. Fume hoods are common local exhaust systems in chemical laboratories. They can exhaust a large amount of harmful gases with a small air volume, control the diffusion of harmful gases, and ensure the health and safety of experimenters. As shown in Figure 10, the first more common fume hood structure, the common fume hood mainly includes a test support table 2, a cabinet cavity 3 arranged above the support table 2 for experimental operations, and an exhaust fan (not shown in the figure) connected to the cabinet cavity 3. When the exhaust fan is working, a negative pressure is formed in the cabinet cavity 3, thereby reducing the amount of harmful gases leaking out from the cabinet cavity 3 and extracting the harmful gases from the cabinet cavity 3. An operation window 30 is provided on the cabinet inner cavity 3, and a lower air supply channel 10 and a channel upper shell 1 for forming an upper channel wall of the lower air supply channel 10 are provided at the threshold position of the operation window 30. The channel upper shell 1 includes a front shell 11, an intermediate shell 12 and a rear shell 13, which are respectively in the shape of a flat plate. The front shell 11 is arranged horizontally, and the rear shell 13 is arranged vertically. The intermediate shell 12 is obliquely connected between the front shell 11 and the rear shell 13. An air outlet 15 of the lower air supply channel 10 is formed between the front shell 11 and the support platform 2, and an air inlet 14 of the lower air supply channel 10 is formed between the rear shell 13 and the support platform 2. When the exhaust fan is working, the air outside the cabinet inner cavity 3 enters the lower air supply channel 10 through the air inlet 14, and then enters the cabinet inner cavity 3 through the air outlet 15. A water blocking boss 21 is also provided on the support platform 2. In addition, as shown in FIG11, a second more common fume hood structure is shown. The channel upper shell 1a shown in the figure includes a front shell 11a and a rear shell 12a connected together front and back. The front shell 11a is a flat plate, and the rear shell 12a is an arc plate. The other structures are similar to those shown in FIG1 and will not be repeated. However, the air supply effects of the above two existing lower air supply structures can be further improved.

Summary of the invention

There are many factors that affect the fume hood's ability to clean harmful gases deposited in the vicinity of the support table. Technical personnel can easily associate these factors with insufficient exhaust fan power, poor guide structure of the guide back plate, etc. A particularly common technical solution is to solve the above technical problems by increasing the excess air volume of the lower guide groove of the guide back plate, but the air supply mechanism of the fume hood is often ignored, thinking that as long as sufficient air volume can be supplied to the fume hood, it will be sufficient. The supply air volume is certainly important, but the flow path of the supply air will also affect the fume hood's ability to capture harmful gases. An analysis of the first and second more common fume hood structures disclosed in the above background technology section found that the airflow blown out from the lower air supply channel they are set up is quite dispersed, resulting in the airflow's ability to capture and clean harmful gases in the vicinity of the support table. A large amount of harmful gases remain. In addition, the airflow blown out from the left and right ends of the air outlet often flows close to the left and right side walls of the cabinet cavity, and the resistance it encounters is greater than the resistance encountered by the airflow blown out from the middle area of the air outlet, thereby affecting the air supply effect on the left and right sides.

In view of the deficiencies in the prior art, the present invention first proposes a ventilation device with an air passage, comprising a test support platform, a cabinet cavity arranged above the support platform, and a cavity wall body configured as the cabinet cavity, wherein the cavity wall body comprises a left cavity side wall and a right cavity side wall separated on the left and right sides and a cavity back wall located therebetween, and further comprises an operation window constructed opposite to the cavity back wall, wherein the operation window is used to form an inlet and outlet passage for conducting experiments on the support platform; the characteristic is that it also comprises a lower air supply device arranged at the door sill position of the operation window, wherein the lower air supply device comprises The invention discloses a wind passage capable of circulating supply air, wherein the air outlet of the wind passage extends along the edge direction x of the support platform and the head and tail ends are respectively close to the left cavity side wall and the right cavity side wall of the cabinet inner cavity, and the wind passage is used to supply air from the outside of the cabinet inner cavity to the nearby area on the support platform surface, and the air outlet comprises a head end air outlet expansion port, a tail end air outlet expansion port and a middle air outlet narrowing port located therebetween, and the heights of the head end air outlet expansion port and the tail end air outlet expansion port relative to the support platform are respectively greater than the height of the middle air outlet narrowing port relative to the support platform.

The inner cavity of the cabinet is an operating space for conducting various experimental activities. With the help of the inner cavity of the cabinet, harmful gases generated during the experiment can be temporarily collected therein to prevent them from running around.

The air passage is used to allow the external airflow of the cabinet cavity to replenish air to the nearby area on the support table surface, that is, the air passage is an air replenishment passage connecting the cabinet cavity with the external space, and the air passage is used to introduce the external air of the cabinet cavity into the cabinet cavity, so as to replenish gas for the cabinet cavity. In another embodiment, the air passage of the present invention can also be applied to a structure in which a blower is installed at its inlet or a pipe connected to its inlet.

Among them, the head and tail ends of the air outlet are respectively close to the left cavity side wall and the right cavity side wall of the cabinet cavity, which can be interpreted as a certain gap can be reserved between the head and tail ends of the air outlet and the left cavity side wall and the right cavity side wall of the cabinet cavity, for example, it can be 1mm~10mm; of course, the smaller the gap between the head and tail ends of the air outlet and the left cavity side wall and the right cavity side wall of the cabinet cavity, the wider the blowing range of the air outlet in the left and right directions will be, so the head and tail ends of the air outlet and the left cavity side wall and the right cavity side wall of the cabinet cavity can also be close together.

The door sill position of the operation window refers to the bottom position of the operation window, and the same meaning is used below unless otherwise specified. The operation window is a passage connecting the external space with the inner cavity of the cabinet, and the hands of the experimenter can pass through the operation window and reach into the inner cavity of the cabinet to perform various experimental operations.

According to the above technical scheme, compared with the prior art, the beneficial technical effect of the present invention is that: since the height of the front end air outlet expansion port and the rear end air outlet expansion port relative to the support platform is respectively greater than the height of the middle air outlet narrowing port relative to the support platform, in this way, within the unit length range in the direction x, the air flow rate blown out from the front end air outlet expansion port and the rear end air outlet expansion port is greater than the air flow rate blown out from the middle air outlet narrowing port, thereby utilizing the strong airflow at the front and rear ends to regulate the airflow flow in the middle area, so that the airflow blown out from the air outlet is more stable and concentrated as a whole, effectively improving the airflow's ability to capture and clean harmful gases in the vicinity of the support platform surface. In addition, the airflow blown out from the front end air outlet expansion port and the rear end air outlet expansion port relative to the middle air outlet narrowing port has a larger flow range in the up and down directions and a relatively larger flow rate, thereby being able to more quickly blow away the heavy molecular gases corresponding to the front and rear ends of the air outlet that are located at the corners on both sides of the inner cavity of the cabinet.

Secondly, in the process of supplying air through the operating window of the fume hood, relevant technical standards generally require that the operating window have a uniform and stable surface wind speed (about 0.5 m/s). Since the middle air outlet narrowing port roughly corresponds to the central area of the operating window, and the central area of the operating window itself has the largest air supply volume, and the front end air outlet expansion port and the rear end air outlet expansion port roughly correspond to the left and right sides of the operating window, the air supply volume of the left and right sides relative to the central area of the operating window is relatively small. In the above-mentioned layout structure, it is possible to further utilize the characteristics that the height of the front end air outlet expansion port and the rear end air outlet expansion port relative to the support platform is respectively greater than the height of the middle air outlet narrowing port relative to the support platform, to make up for the problem of insufficient air supply at the left and right sides of the operating window and excessive air supply in the central area of the operating window, thereby greatly improving the uniformity and stability of the surface wind speed of the operating window.

A further technical solution may be that, in direction x, the widths of the front end air outlet expansion port and the rear end air outlet expansion port are smaller than the width of the middle air outlet narrowing port.

A further technical solution may also include a guide back plate arranged above the support platform and close to the support platform, the guide back plate is located in front of the cavity back wall and there is a spacing between them to form an exhaust duct, the left and right side edges of the guide back plate are respectively close to the left cavity side wall and the right cavity side wall, wherein there are enlarged air openings between the lower area of the guide back plate and the left cavity side wall and the right cavity side wall, respectively, and the width of the spacing between the upper area of the guide back plate and the left cavity side wall and the right cavity side wall in the left and right directions is smaller than the width of the enlarged air opening. According to the above technical solution, the head end air outlet expansion port and the tail end air outlet expansion port can provide a suitable air volume for the enlarged air opening, which is conducive to maintaining a balanced surface wind speed. Among them, the deflector back plate is close to the support platform, and the lower area of the deflector back plate is actually located in the lower area of the cabinet cavity. It includes that the bottom end surface of the deflector back plate can stand on the support platform, and can also be separated from the support platform by a certain appropriate spacing in the up and down directions. The general spacing is set to 30mm~150mm, such as 30mm, 68mm, 88mm or 150mm. The left and right sides of the deflector back plate are respectively close to the left cavity side wall and the right cavity side wall. The above characteristics define that it includes that the left and right sides of the deflector back plate (excluding the part used to form the enlarged air opening) can be close to the left cavity side wall and the right cavity side wall respectively, and can also be separated from the left cavity side wall and the right cavity side wall by a certain appropriate spacing in the left and right directions. The width of the spacing is generally 1mm~20mm. The size of the above spacing is specifically determined according to other specific air inlet structures of the fume hood, the exhaust power of the exhaust fan, the applicable scope of the fume hood and other factors. Secondly, the maximum width of the enlarged air opening can be 35 mm to 45 mm. In addition, the guide back plate and the cavity back wall can be arranged substantially parallel to each other, or the guide back plate can be arranged obliquely relative to the cavity back wall to form an exhaust air duct therebetween.

A further technical solution may be that the lower air supply device further includes an upper shell body that forms a part of the channel wall of the air passage and is located above the air passage, and a movable cabinet door is provided on the operation window, and the cabinet door abuts against the upper shell body when it falls. In this way, when the cabinet door completely closes the operation window, the air outside the cabinet cavity can still be guided to the nearby area on the support table surface through the air passage for air supply.

A further technical solution may be that the lower air replenisher further includes plugs located at the front and rear ends of the upper shell, the plugs include a plug body for blocking the end of the air passage and a plug connection portion for fixing the plug body to the upper shell, and the plug bodies of the plugs located at the front and rear ends of the upper shell are respectively fixed to the left cavity side wall and the right cavity side wall. In this way, the plugs can not only block the end of the air passage, but also be used to fix the lower air replenisher.

A further technical solution may be that the lower air supply device further includes an air guide vane extending along the flow path of the supply air, and the air guide vane is arranged in the air passage. In this way, the air flow in the air passage is guided by the air guide vane, so that the number and intensity of vortices formed in the air passage can be reduced.

A further technical solution may also include a wing connector, one end of which is connected to the air guide wing, and the other end is connected to the upper shell, wherein the wing connector and the air guide wing may be a separate structure or an integrated structure.

Since the present invention has the above characteristics and advantages, it can be applied to ventilation equipment with an air passage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the three-dimensional structure of a fume hood to which the technical solution of the present invention is applied;

FIG2 is a schematic structural diagram of a fume hood in a main view to which the technical solution of the present invention is applied;

Fig. 3 is a schematic cross-sectional view of the structure along the A-A direction in Fig. 2;

FIG4 is an enlarged view of portion C in FIG3 ;

FIG5 is a schematic structural diagram of the guide back plate in the main view direction, wherein the left and right dotted line parts respectively represent the left cavity side wall 31 and the right cavity side wall 32, and the dotted line part below represents the support platform 2;

FIG6 is an enlarged view of portion B in FIG3 ;

FIG7 is a schematic diagram of the three-dimensional structure of the fixing seat 8;

FIG8 is a schematic structural diagram of the lower air supply device in the main view direction;

FIG9 is a schematic diagram of the three-dimensional structure of the lower air supply device after being turned over to the back;

Figure 10 is a schematic diagram of the first common fume hood structure;

Figure 11 is a schematic diagram of the second more common fume hood structure.

DETAILED DESCRIPTION

The structure of the fume hood using the technical solution of the present invention is further described below in conjunction with the accompanying drawings.

As shown in Fig. 1 to Fig. 3 and Fig. 5, the present invention relates to a fume hood, comprising a test support platform 2, a cabinet cavity 3 arranged above the support platform 2, and a cavity wall body configured as the cabinet cavity 3, wherein the cavity wall body comprises a left cavity side wall 31, a right cavity side wall 32, and a cavity back wall 34 and a cavity top wall 33 arranged between the left cavity side wall 31 and the right cavity side wall 32. It also comprises an operation window 30 constructed opposite to the cavity back wall 34, the operation window 30 extends left and right along the front side edge 22 of the support platform 2, and the operation window 30 is used to form an inlet and outlet passage for conducting experiments on the support platform 2, and the hands of the experimenter can extend through the operation window 30 into the cabinet cavity 3 to conduct various experimental operations, and the harmful gases generated during the experiment will be temporarily collected in the cabinet cavity 3 to avoid running around. A total exhaust port 330 is also provided on the cavity top wall 33, and the total exhaust port 330 is used to exhaust the air in the cabinet cavity 3; in other embodiments, the total exhaust port 330 can also be provided at a suitable place on the left cavity side wall 31, the right cavity side wall 32 or the cavity back wall 34, and the specific setting position can be reasonably determined according to the flow field design of the entire airflow of the fume hood.

An exhaust passage 6 connected to the main exhaust port 330 is provided in the cabinet inner cavity 3. An exhaust fan (not shown in the figure) connected to the main exhaust port 330 is also installed above the fume hood, and the exhaust fan is used to form a negative pressure in the cabinet inner cavity 3. When the exhaust fan is running, the harmful gas accumulated in the cabinet inner cavity 3 is sucked into the exhaust passage 6 and then discharged through the main exhaust port 330.

The basic goal of safe use of fume hoods is that, under the suction force of the exhaust fan, the design of the airflow field in the entire cabinet should ensure that the surface wind speed at the position of the operating window 30 is stable and uniform, the gas in the cabinet cavity 3 will not flow back from the position of the operating window 30, and the large molecular harmful gases deposited at the bottom of the cabinet cavity 3 can be removed in time and cannot flow back. Of course, there are many specific schemes to achieve the above basic goals, and the scheme proposed in the present invention is not the only one; secondly, to achieve the above basic goals, it is necessary to improve various local structures so that they can play their role in a fume hood product. For this reason, the present invention also mainly improves the local structure of the fume hood in order to achieve the corresponding technical effect. The corresponding local improvement schemes will be explained one by one in the following statements.

In order to achieve the above basic objectives, the present invention first improves the wind passing structure at the bottom of the guide back plate 5. As shown in FIG3 , the guide back plate 5 is disposed in the cabinet inner cavity 3, and the guide back plate 5 and the cavity wall of the cabinet inner cavity 3 are separated structures. The guide back plate 5 is located in front of the cavity back wall 34 and there is a distance between them to form the exhaust duct 6. Therefore, the guide back plate 5 actually faces the operation window 30.

As shown in FIG5 , the guide back plate 5 includes a first guide back plate 51 disposed above the support platform 2 and close to the support platform 2. The first guide back plate 51 and the cavity back wall 34 are arranged substantially parallel to each other. Of course, in other embodiments, the first guide back plate 51 may be arranged obliquely relative to the cavity back wall 34. The first guide back plate 51 is located in front of the cavity back wall 34 and there is a distance between them to form a first exhaust duct 61 extending up and down, and the first exhaust duct 61 forms a partial channel of the exhaust duct 6. The left and right side edges of the first air guide back plate 51 extend close to the left cavity side wall 31 and the right cavity side wall 32 in the left and right directions, respectively. However, the two side edges of the first air guide back plate 51 located in the lower area of the cabinet inner cavity 3 and the left cavity side wall 31 and the right cavity side wall 32 respectively have a gradually expanding air opening 71 and a gradually expanding air opening 71a, that is, the gradually expanding air opening 71 and the gradually expanding air opening 71a are located on the left and right sides of the lower area of the cabinet inner cavity 3, and the gradually expanding air opening 71 and the gradually expanding air opening 71a are expanding air openings. The gradually expanding air opening 71 and the gradually expanding air opening 71a are in a geometric shape that gradually increases from the top to the bottom. In one preferred embodiment, the maximum width W of the gradually expanding air opening 71 and the gradually expanding air opening 71a in the left-right direction is 35 mm to 45 mm, for example, 35 mm, 40 mm or 45 mm. In addition, the two sides of the upper area of the first air guide back plate 51 are spaced from the left cavity side wall 31 and the right cavity side wall 32 by a suitable spacing that does not need to be too large, specifically including an upper side gap 76 and an upper side gap 76a with uniform gap width, the upper side gap 76 is located above the gradually expanding air opening 71, and the upper side gap 76a is located above the gradually expanding air opening 71a. The gap width W4 of the upper side gap 76 and the upper side gap 76a is smaller than the width of the gradually expanding air opening 71 and the gradually expanding air opening 71a. The gap width W4 of the upper side gap 76 and the upper side gap 76a is also smaller than the gap height H of the bottom spacing 7 to be discussed below. The gap width W4 is generally 1mm to 20mm, for example, 1mm, 10mm, 20mm. The specific gap size is determined according to other specific air inlet structures of the fume hood, the exhaust power of the exhaust fan, the applicable scope of the fume hood, etc. The gaps with uniform width in the left and right directions between the two sides of the second guide back plate 52 and the third guide back plate 53 to be discussed below and the left cavity side wall 31 and the right cavity side wall 32 are also of the same width W4.

According to the above technical scheme, compared with the prior art, the beneficial technical effects are: first, since the two side edges of the first guide back plate 51 located in the lower area of the cabinet cavity 3 and the left cavity side wall 31 and the right cavity side wall 32 respectively have gradually expanding air openings 71 and gradually expanding air openings 71a, that is, relatively large air guide gaps arranged continuously from top to bottom are formed on the left and right sides of the first guide back plate 51, respectively, so that a flow channel can be provided for the relatively heavy macromolecular gases deposited in the left and right corners of the lower area of the cabinet cavity 3 to be discharged into the first exhaust duct 61 in time, and it is also beneficial to reduce the resistance of airflow and the formation of vortices, thereby increasing the airflow speed. Secondly, when the fume hood is configured with an inhaled airflow as the control airflow and a pressure gradient that gradually increases from bottom to top is formed in the cabinet cavity 3, there will be a certain inhaled air velocity gradient between the highest point and the lowest point of the gradually expanding air opening 71. The shape change of the gradually expanding air opening 71, that is, the geometric shape that gradually increases from the top to the bottom, is conducive to forming a basically uniform inhaled air volume (air volume) on the gradually expanding air opening 71, so that the distribution state of the airflow field at the left and right corners of the lower area of the cabinet cavity 3 can be optimized, and the generation of eddy currents can be further reduced. In addition, compared with the gaps with uniform widths from top to bottom in the prior art, the lower part of the gradually expanding air opening 71 has a relatively larger air flow area, so that the lower part of the gradually expanding air opening 71 has a relatively larger air flow volume, so that more relatively heavy macromolecular gases deposited in the left corner of the lower area of the cabinet cavity 3 can be captured. The gradually expanding air opening 71a can achieve the same technical effect as the gradually expanding air opening 71, and will not be discussed again here.

As shown in FIG5 , the first guide back plate 51 is close to the support platform 2 and is provided with a spacing, so that there is a bottom spacing 7 between the first guide back plate 51 and the support platform 2 for passing wind, and the gap width W4 of the upper side gap 76 and the upper side gap 76a are respectively smaller than the gap height H of the bottom spacing 7. In one preferred embodiment, the gap height H is generally 30 mm to 150 mm, such as 30 mm, 68 mm, 88 mm or 150 mm, and the specific gap height is determined according to other specific air inlet structures of the fume hood, the exhaust power of the exhaust fan, the applicable scope of the fume hood, and other factors. According to the above technical solution, the bottom air guide passage is formed by the bottom spacing 7, which is conducive to capturing the heavier macromolecular gas that sinks into the lower area of the cabinet cavity 3. In other embodiments, the bottom spacing 7 can be set to be close to zero, that is, the bottom end surface of the first guide back plate 51 stands on the support platform 2. Furthermore, the gradually enlarged air opening 71 and the gradually enlarged air opening 71a respectively extend downward through the bottom end surface of the first guide back plate 51 and are combined with the bottom spacing 7. In this way, the gradually enlarged air opening 71 and the gradually enlarged air opening 71a and the bottom spacing 7 form a U-shaped bottom total air space, which can better capture the relatively heavy macromolecular gas deposited in the lower area of the cabinet inner cavity 3. In addition, it is also convenient to process the gradually enlarged air opening 71 and the gradually enlarged air opening 71a on the first guide back plate 51.

In order to form the gradually expanding air opening 71 and the gradually expanding air opening 71a, the following technical solutions can be further selected. The first technical solution: as shown in FIG5 , the two sides of the first air guide back plate 51 located in the lower area of the cabinet inner cavity 3 are inclined and narrowed towards each other, and the left cavity side wall 31 and the right cavity side wall 32 are upright. In this embodiment, the first technical solution is adopted, and the gradually expanding air opening 71 and the gradually expanding air opening 71a are right-angled triangles, and their vertex angle Q is 3°~13°, for example, 3°, 6°, 13°. The second technical solution (not shown in the figure): the lower areas of the left cavity side wall 31 and the right cavity side wall 32 are respectively in a shape that is gradually concave from top to bottom, and the two sides of the first air guide back plate 51 located in the lower area of the cabinet inner cavity 3 are upright.

In order to achieve the above basic objectives, the present invention proposes another improved scheme for the structure of the guide back plate 5, which can be used alone or in combination with the gradually enlarged air opening 71 and the gradually enlarged air opening 71a in the fume hood product. Specifically, as shown in FIG5 , a guide structure capable of guiding the airflow in the front space 35 into the exhaust passage 6 is provided on the guide back plate 5, that is, a lower air guide passage 72 extending left and right is provided on the plate body located only in the lower area of the cabinet inner cavity 3 on the first guide back plate 51, and the air passing area of the lower air guide passage 72 is not greater than the air passing area of the bottom spacing 7, that is, the air passing area of the lower air guide passage 72 can be equal to or less than the air passing area of the bottom spacing 7. In this way, the lower air guide passage 72 is also located in the lower area of the cabinet inner cavity 3, so that the relatively heavy macromolecular gas deposited in the lower area of the cabinet inner cavity 3 can be discharged in time. In addition, compared with the case where multiple rows of air guide slots are provided on the lower area of the first air guide back plate 51, the air flow rate of the lower air guide passage 72 is relatively stronger, which can not only better capture the harmful gases that drift to the vicinity thereof, but also provide conditions for configuring the appropriate air flow rate of the gradually expanding air flow opening, and can greatly simplify the air guide structure of the first air guide back plate 51, reduce the damage to the original structural strength of the first air guide back plate 51, and facilitate the processing of the first air guide back plate 51. Further, the lower air guide passage 72 includes at least three first sub-aisles, that is, there can be 3, 4 or other multiple first sub-aisles. In this embodiment, three first sub-aisles are provided, namely, the first sub-aisle 72a, the first sub-aisle 72b, and the first sub-aisle 72c, the three first sub-aisles are arranged left and right, and each of the first sub-aisles is in the shape of a long strip extending in the left-right direction. According to the above technical solution, the first guide plate 51 can still maintain a suitable structural strength when the lower air guide passage 72 is formed.

In order to achieve the above basic objectives, the present invention proposes another improvement scheme for the structure of the guide back plate 5, which can be used alone or in combination with the gradually expanding air opening 71 and the gradually expanding air opening 71a in the fume hood product. Specifically, as shown in Figures 3 and 5, the guide back plate 5 also includes a second guide back plate 52 which is separated from the first guide back plate 51, the second guide back plate 52 is located above the first guide back plate 51 and arranged close to the first guide back plate 51, the second guide back plate 52 is located in front of the cavity back wall 34 and is arranged roughly parallel to each other and there is a spacing between them to form a second exhaust duct 62 extending up and down, and the second exhaust duct 62 also forms a partial channel of the exhaust duct 6 (in other embodiments, the second guide back plate 52 can also be arranged obliquely relative to the cavity back wall 34). It also includes a middle air guide aisle 73 extending left and right, and the middle air guide aisle 73 is composed of the inter-plate spacing 73 between the first guide back plate 51 and the second guide back plate 52. In the up and down directions, the middle air guide aisle 73 is roughly located in the central area of the cabinet cavity 3 viewed in the up and down directions, and the wind flow area of the middle air guide aisle 73 is smaller than the wind flow area of the lower air guide aisle 72. Compared with the prior art, the beneficial technical effects of the above technical solution are: first, since there is a bottom spacing 7 between the first guide back plate 51 and the support platform 2 for air to pass through, the bottom spacing 7 can be used to timely discharge the heavier macromolecular gases deposited in the lower area of the cabinet cavity; secondly, since the lower air guide passage 72 is located in the lower area of the cabinet cavity 3 and above the bottom spacing 7, the heavier macromolecular gases that escape from the bottom spacing 7 and continue to drift upward can be captured by the airflow flowing through the lower air guide passage 72 and brought into the air duct behind the guide back plate 5; furthermore, since only one lower air guide passage 72 is provided on the first guide back plate 51, and the lower air guide passage 72 The wind passing area of 72 is not greater than the wind passing area of the bottom spacing 7. Thus, compared with the case where multiple rows of air guides are arranged on the first guide back plate 51, the wind passing volume of the lower air guide passage 72 is relatively stronger, and can better capture the harmful gases that drift to its vicinity, and can make the bottom spacing 7 have a suitable wind passing volume; again, the middle air guide passage 73 is composed of the inter-plate spacing between the first guide back plate 51 and the second guide back plate 5. Thus, it is very convenient to control the size of the inter-plate spacing to make the middle air guide passage 73 have a suitable wind passing area, especially to form a narrow air guide gap in a very simple way. The ventilation area of the middle air guide passage 73 is not limited by the size specifications of the milling tool and can be flexibly configured. The relatively light harmful gases that escape from the lower air guide passage 72 and continue to drift upward can be captured by the airflow flowing through the middle air guide passage 73 and brought into the air duct behind the guide back plate 5. Based on this, it can be found that by setting the bottom spacing 7, the lower air guide aisle 72, and the middle air guide aisle 73 in sequence from bottom to top, and configuring them with appropriate ventilation areas, quantities and layout positions, not only can the harmful gases of different weights be effectively captured, but the guide structure of the guide back plate 5 can also be greatly simplified, reducing the damage to the original structural strength of the guide back plate 5, and facilitating the processing of the guide back plate 5.

As shown in FIG5 , the guide back plate 5 also includes a third guide back plate 53 located above the second guide back plate 52. The third guide back plate 53 is located in front of the cavity back wall 34 and can be arranged substantially parallel to each other between the cavity back wall 34. In other embodiments, the third guide back plate 53 can also be arranged obliquely relative to the cavity back wall 34. There is a spacing between the third guide back plate 53 and the cavity back wall 34 to form a third exhaust duct 63 extending up and down. The first exhaust duct 61, the second exhaust duct 62 and the third exhaust duct 63 are connected front and back to form an exhaust channel 6 leading to the total exhaust port 330. The lower end of the third guide back plate 53 is connected to the upper part of the second guide back plate 52. The third guide back plate 53 is arranged below the total exhaust port 330 in an inclined upward structure so that the third exhaust duct 63 is connected to the total exhaust port 330. A joint seam 74 is provided between the second guide back plate 52 and the third guide back plate 53, and the wind passing area of the joint seam 74 is not greater than the wind passing area of the inter-plate spacing 73, and no wind hole groove is provided on the second guide back plate 52 and the third guide back plate 53. According to the above technical scheme, compared with the scheme of providing wind hole grooves on both the second guide back plate 52 and the third guide back plate 53, it is beneficial to increase the wind passing volume of the bottom spacing 7, the lower guide channel 72, the middle guide channel 73 and the gradually expanding wind opening, so that the ability to capture harmful gases deposited in the lower area and the central area of the cabinet cavity 3 can be maintained while simplifying the guide structure on the guide back plate 5. Among them, the wind passing area of the splicing seam 74 is not greater than the wind passing area of the middle air guide passage 73, that is, the wind passing area of the splicing seam 74 is less than or equal to the wind passing area of the middle air guide passage 73, and the wind passing area of the splicing seam 74 can even be zero, for example, when sealed with the aid of a seal. In addition, a top spacing 75 is formed between the upper end of the third air guide back plate 53 and the cavity top wall 33 of the cabinet cavity 3. According to the above technical solution, the top spacing 75 is actually located in the upper area of the cabinet cavity 3, so that the harmful gases that escape from the bottom spacing 7, the lower air guide passage 75, and the middle air guide passage 73 in sequence and continue to drift upward can be captured by the airflow flowing through the top spacing 75 and brought into the third exhaust duct 63 and then discharged from the cabinet cavity 3.

As shown in Fig. 3, Fig. 6 and Fig. 7, in order to fix the guide back plate 5, a fixing seat 8, a fixing seat 8a and a fixing seat 8b are arranged between the guide back plate 5 and the cavity back wall 34. The structures of the fixing seats 8, 8a and 8b are the same, and the fixing seat 8 is taken as an example for description below. The fixing seat 8 is U-shaped, including a top support wall 83 and a left support wall 81 and a right support wall 82 arranged on the left and right sides of the top support wall 83. An interlayer cavity 80 is formed between the top support wall 83 and the left support wall 81 and the right support wall 82. A connecting column 85 is arranged on the top support wall 83, and the tail of the connecting column 85 extends into the interlayer cavity 80. The fixing seat 8 is locked on the cavity back wall 34 by screws. The fixing seat 8 is located between the second guide back plate 52 and the cavity back wall 34, the second guide back plate 52 is pressed against the top support wall 83, and the fastener 86 passes through the second guide back plate 52 and is connected to the connecting column 85 to fix the second guide back plate 52 to the fixing seat 8; an oblique slot 84 is provided on the top support wall 83, and the lower end of the third guide back plate 53 is inserted into the oblique slot 84 to connect to the upper part of the second guide back plate 52. The fixing seat 8a is provided between the first guide back plate 51 and the cavity back wall 34, the first guide back plate 51 is pressed against the top support wall of the fixing seat 8a, and the fastener passes through the first guide back plate 51 and is connected to the connecting column of the fixing seat 8a to fix the first guide back plate 51 to the fixing seat 8a. In this way, the installation, disassembly and replacement of the first guide back plate 51, the second guide back plate 52 and the third guide back plate 53 are simplified.

As shown in Figures 2, 3 and 4, a lower air supply device is also provided on the cabinet, and the lower air supply device includes an air passage 10 that can circulate supply air, and an air outlet 15 of the air passage 10 is arranged to extend along the edge 22 of the support platform 2 in the direction x (wherein the direction X is the direction of the X-axis in Figure 2), and the air passage 10 is used to supply air from the outside of the cabinet inner cavity 3 to the nearby area on the surface of the support platform 2, and the lower air supply device also includes an upper shell 1 that forms a partial channel wall of the air passage 10 and is located above the air passage 10, and on the flow path of the supply air, the upper shell 1 includes a first shell portion 11, an intermediate transition shell portion 13 and a second shell portion 12 that are arranged in sequence so that the air passage 10 is also correspondingly divided into a first section 101, an intermediate section 103 and a second section 102 corresponding to the first shell part 11, the intermediate transition shell part 13 and the second shell part 12 and connected, wherein the external air enters from the first section 101 and flows through the intermediate section 103 and then flows out from the second section 102; viewed from the cross-sectional direction perpendicular to the direction x (i.e. as shown in FIG. 4 ), the inner side wall 11a of the first shell part 11 is a plane wall extending in an upward direction inclined along the airflow direction, the inner side wall 13a of the intermediate transition shell part 13 is an arc wall, and the inner side wall 11a of the first shell part 11 and the inner side wall 12a of the second shell part 12 are smoothly transitioned and connected through the inner side wall 13a of the intermediate transition shell part 13.

Among them, the air outlet 15 of the air passage 10 is arranged to extend along the direction x of the edge 22 of the support platform 2. The above characteristics define that the extension direction of the air outlet 15 of the air passage 10 is substantially consistent with the extension direction of the edge 22 of the support platform 2. Secondly, the air passage 10 is used to guide the air outside the cabinet cavity 3 to the nearby area on the surface of the support platform 2 to replenish air, that is, the air passage 10 is an air replenishment channel connecting the cabinet cavity 3 with the external space, and the air passage 10 is used to introduce the external air of the cabinet cavity 3 into the cabinet cavity 3, so as to replenish the gas for the cabinet cavity 3. In addition, the inner side wall 11a of the first shell part 11 is a plane wall extending in an inclined upward direction along the air flow direction, that is, the inner side wall 11a of the first shell part 11 is not a curved wall, and the inner side wall 11a of the first shell part 11 not only extends straightly from bottom to top, but also extends from outside to inside (from the outside direction of the cabinet cavity 3 to the inside direction of the cabinet cavity 3). The plane wall can not only guide the flow but also easily form a stable flow. The inner side wall 11a of the first shell 11 and the inner side wall 12a of the second shell 12 are smoothly transitioned and connected through the inner side wall 13a of the intermediate transition shell 13, so that the intermediate transition shell 13 can minimize the damage to the flat and stable flow formed by the plane wall.

Compared with the prior art, the beneficial technical effects of the above technical solution adopted by the lower air replenisher are: first, since the air passage 10 is used to replenish air from the outside of the cabinet cavity 3 to the nearby area on the surface of the support platform 2, it is beneficial to blow the harmful gases deposited in the nearby area on the surface of the support platform 2 toward the inside of the cabinet cavity 3, thereby reducing the amount of harmful gases leaking outward. Second, since the inner wall 11a of the first shell 11 is a plane wall extending upwardly along the direction of the airflow, at least part of the airflow entering the first section 101 can flow not only from bottom to top but also from outside to inside under the guidance of the inner wall 11a of the first shell 11, that is, at least part of the airflow under the guidance of the inner wall 11a of the first shell 11 has not only the kinetic energy of the movement trend flowing from bottom to top but also the kinetic energy of the movement trend flowing from outside to inside; secondly, the inner wall 11a of the first shell 11 is a plane wall, which is easy to form a steady flow; In addition, since the inner side wall 13a of the intermediate transition shell 13 is an arc wall, the inner side wall 11a of the first shell 11 and the inner side wall 12a of the second shell 12 are smoothly transitioned and connected through the inner side wall 13a of the intermediate transition shell 13, so that on the flow path from the first section 101 to the middle section 103, at least part of the gas can smoothly enter the second section 102 from the first section 101 under the guidance of the inner side wall 13a of the intermediate transition shell 13, effectively improving the undesirable phenomenon of a large number of vortices formed in the middle section 103. Because the inner side wall of the upper shell 1 has the above-mentioned structural improvement, the external airflow can enter the air passage 10 relatively more, so that more airflow can be added to the cabinet cavity 3, reducing the formation of a large number of vortices near the air outlet 15.

As for the structural form of the inner side wall 12a of the second shell part 12, it can be various, and can be selected from the following three technical solutions according to actual needs: The first technical solution of the second shell part 12: As shown in Figure 4, the height position of the edge 22 of the support platform 2 is lower than the height position of the second shell part 12, and the inner side wall 12a of the second shell part 12 extends downward along the air flow direction, so as to force at least part of the airflow entering the second section 102 to flow from top to bottom and then pass through the air outlet 15 and dive onto the support platform 2. In this way, the amount of air blown out from the air outlet 15 and diving from top to bottom and the impact force of the airflow can be relatively increased. The diving airflow can relatively strongly flush and clean the harmful gases deposited on the surface of the support platform 2, and use the board surface guide effect of the support platform 2 to push the harmful gases toward the inner direction of the cabinet cavity 3 and away from the lower air replenisher. Furthermore, the rebound effect of the support platform 2 on the airflow can be used to expand the flow range of the airflow, and the harmful gases scattered within a certain height range from the support platform 2 are pushed toward the inner direction of the cabinet cavity 3. It can be seen that the structure of the inner side wall 12a of the second shell 12 extending downward along the airflow direction effectively and in a very simple structure optimizes the fume hood's ability to capture harmful gases and reduces the amount of harmful gases leaking out. Further, a water-blocking boss 21 extending along the direction x is provided on the support platform 2, and a reference line A extending along the inclined direction of the inner side wall 12a of the second shell 12 enters the inner space of the water-blocking boss 21. In this way, under the guidance of the inner side wall 12a of the second shell 12, at least part of the airflow in the air passage 10 can enter the inner space of the water-blocking boss 21 in a way of diving from top to bottom, flushing and pushing the harmful gases deposited on the support platform 2. In addition, the water blocking boss 21 can prevent the liquid spilled on the support platform 2 from dripping onto the ground. In order to simplify the processing of the second shell 12 and optimize the smoothness of the airflow in the air passage 10, the inner side wall 12a of the second shell 12 is a plane wall. This is more conducive to strengthening the impact of the diving airflow and further improving the fume hood's ability to capture harmful gases.

The other two technical solutions of the second shell 12 are: the inner side wall 12a of the second shell 12 extends upward along the direction of the airflow so that the airflow blown out from the air outlet 15 can be blown from bottom to top. In this way, even if the water blocking boss 21 is higher than the inner side wall 12a of the second shell 12, the airflow blown out from the air passage 10 can still enter the vicinity of the surface of the support platform 2 under the guidance of the inner side wall 12a of the second shell 12. Alternatively, the inner side wall 12a of the second shell 12 extends horizontally, so that the airflow blown out from the air outlet 15 can be blown horizontally.

As shown in FIG4 , the outer side wall 12b of the second shell 12 is a plane wall extending in an oblique downward direction along the airflow direction. In this way, part of the external air dives from top to bottom onto the support platform 2 under the guidance of the outer side wall 12b of the second shell 12 to form a second airflow, which can then merge with the airflow blown out from the air outlet 15 and dives from top to bottom onto the support platform 2 to coordinately push the harmful gas deposited on the surface of the support platform 2, thereby enhancing the cleaning ability of the harmful gas deposited on the surface of the support platform 2. Moreover, the outer side wall 12b of the second shell 12 is a plane wall, which is more conducive to strengthening the impact force of the second airflow and further improving the fume hood's ability to capture harmful gases. In addition, the outer side wall 11b of the first shell 11 is a plane wall extending in an oblique upward direction along the airflow direction, and the outer side wall 13b of the intermediate transition shell 13 is an arc wall, and the outer side wall 11b of the first shell 11 and the outer side wall 12b of the second shell 12 are smoothly transitioned and connected through the outer side wall 13b of the intermediate transition shell 13. In this way, part of the external air is blown from bottom to top under the guidance of the outer wall 11b of the first shell 11, so that the harmful gas floating at a certain height from the surface of the support platform 2 can be pushed forward away from the lower air replenishment device. Accordingly, under the guidance of the outer wall of the upper shell 1, the external air flow can be divided into tributaries flowing upward and downward, increasing the cleaning range of the air flow for harmful gases. In this embodiment, in order to simplify the structure and manufacturing process of the upper shell 1, the upper shell 1 can be made of a thin plate.

As shown in Figure 4, the upper shell 1 covers at least a portion of the edge 22 of the support platform 2, and the support platform 2 becomes at least a portion of the lower wall of the air passage 10. This simplifies the lower air supply structure of the fume hood. The upper shell 1 also includes a tail plate 16 connected to the lower end of the first shell 11, and the tail plate 16 extends vertically in the up and down directions. An air inlet 14 of the air passage 10 is formed between the tail plate 16 and the edge 22 of the support platform 2, and the air inlet 14 is connected to the external space of the cabinet cavity 3. According to the above technical solution, the air inlet 14 is arranged downward, and when the experimenter stands beside the lower air supply device for experiment, the air inlet 14 will not be easily blocked by the experimenter's body to destroy the air supply effect.

In order to reduce the formation of vortices in the wind passage 10, as shown in FIG9 , the lower air supply device further includes an air guide vane 17 extending along the flow path of the supply air, and the air guide vane 17 is arranged in the wind passage 10. In this way, the air flow in the wind passage 10 is guided by the air guide vane 17 to reduce the generation of vortices. It also includes a wing connector 171, one end of which is connected to the air guide vane 17, and the other end is connected to the upper shell 1. The wing connector 171 and the air guide vane 17 can be a split structure or an integrated structure.

As shown in Fig. 1, Fig. 8 and Fig. 9, the lower air supply device is arranged at the door threshold position of the operating window 30 (the door threshold position of the operating window 30 refers to the bottom position of the operating window 30), and the front and rear ends of the air outlet 15 of the lower air supply device are respectively close to the left cavity side wall 31 and the right cavity side wall 32 of the cabinet inner cavity 3. The air outlet 15 includes a front end air outlet expansion port 151, a rear end air outlet expansion port 152 and a middle air outlet narrowing port 153 located therebetween, and the height H2 of the front end air outlet expansion port 151 relative to the support platform 2 and the height H3 of the rear end air outlet expansion port 152 relative to the support platform 2 are respectively greater than the height H4 of the middle air outlet narrowing port 153 relative to the support platform 2. In the direction x, the width W1 of the front end air outlet expansion port 151 and the width W2 of the rear end air outlet expansion port 152 are smaller than the width W3 of the middle air outlet narrowing port 153. In this way, within the unit length range in the direction x, the amount of air blown out from the front end air outlet expansion port 151 and the rear end air outlet expansion port 152 is greater than the amount of air blown out from the middle air outlet narrowing port 153, so that the strong airflow on both sides is used to regulate the airflow in the middle area, so that the airflow blown out from the air outlet 15 flows smoothly and concentratedly as a whole, effectively improving the airflow's ability to capture and clean harmful gases in the vicinity of the surface of the support platform 2. In addition, the airflow blown out from the front end air outlet expansion port 151 and the rear end air outlet expansion port 152 has a larger flow range in the up and down directions and a relatively larger flow rate than the middle air outlet narrowing port 153, so that the heavy molecular gases corresponding to the front and rear ends of the air outlet 15 that are located at the corners on both sides of the cabinet cavity 3 can be blown away more quickly. The head end wind outlet expansion port 151 and the tail end wind outlet expansion port 152 can provide appropriate air volume for the gradually expanding wind opening 71 and the gradually expanding wind opening 71a respectively, so as to help maintain a uniform surface wind speed.

Secondly, in the process of supplying air through the operation window 30 of the fume hood, the relevant technical standards generally require that the operation window 30 has a uniform and stable surface wind speed (about 0.5 m/s). Since the middle air outlet narrowing port 153 roughly corresponds to the central area of the operation window 30, and the central area of the operation window 30 itself has the largest air supply volume, and the head end air outlet expansion port 151 and the tail end air outlet expansion port 152 roughly correspond to the left and right sides of the operation window 30, the air supply volume of the left and right sides relative to the central area of the operation window 30 is relatively small. In the above-mentioned layout structure, it is possible to further utilize the characteristics that the height of the head end air outlet expansion port 151 and the tail end air outlet expansion port 152 relative to the support platform 2 is respectively greater than the height of the middle air outlet narrowing port 153 relative to the support platform 2, to make up for the problem that the left and right sides of the operation window 30 are relatively insufficient in air supply and the central area of the operation window 30 is excessive in air supply, which greatly improves the uniformity and stability of the surface wind speed of the operation window 30.

The front and rear ends of the upper shell 1 are respectively close to the left cavity side wall 31 and the right cavity side wall 32 of the cabinet inner cavity 3. The lower air supply device also includes a plug 18 arranged at the front end of the upper shell 1 and a plug 18a arranged at the rear end of the upper shell 1. The plug 18a has a similar structure to the plug 18. The plug 18 is used as an example for introduction below. The plug 18 includes a plug body 181 for blocking the end of the air passage 10 and a plug connection part 182 for fixing the plug body 181 to the upper shell 1. The screw passes through the plug body 181 of the plug 18 to fix the plug 18 to the left cavity side wall 31, and the screw passes through the plug body of the plug 18a to fix the plug 18a to the right cavity side wall 32. In this way, the plug 18 and the plug 18a can not only block the end of the air passage 10, but also be used to fix the lower air supply device. In addition, a movable cabinet door 4 is provided on the operating window 30, and the upper shell 1 can limit the lowest limit position of the cabinet door 4, that is, the cabinet door 4 can be pressed against the upper shell 1 when it falls. In this way, when the cabinet door 4 completely closes the operating window 30, the air outside the cabinet cavity 3 can still be guided to the nearby area on the surface of the support platform 2 through the air passage 10. In another embodiment, the air passage 10 of the present invention can also be applied to a structure in which a blower is installed at its inlet or a pipe connected to its inlet, and the lower air supply device can also be directly connected to the support platform 2.

Claims (5)

1. The ventilation equipment with the air passage comprises a supporting table for test, a cabinet inner cavity arranged above the supporting table, and a cavity wall body constructed into the cabinet inner cavity, wherein the cavity wall body comprises a left cavity side wall, a right cavity side wall and a cavity back wall arranged between the left cavity side wall and the right cavity side wall, and the ventilation equipment also comprises an operation window constructed on the opposite side of the cavity back wall, and the operation window is used for forming an inlet and outlet passage for performing the test on the supporting table; the method is characterized in that: the lower air compensator comprises an air passage through which air can circulate, the air outlet of the air passage extends along the edge direction x of the supporting table, the head end and the tail end of the air passage are respectively close to the left cavity side wall and the right cavity side wall of the inner cavity of the cabinet, the air passage is used for supplying air from the outside of the inner cavity of the cabinet to the nearby area on the table top of the supporting table, the air outlet comprises a head end air outlet expansion port, a tail end air outlet expansion port and a middle air outlet narrow opening positioned between the head end air outlet expansion port and the tail end air outlet expansion port, and the heights of the head end air outlet expansion port and the tail end air outlet narrow opening relative to the supporting table are respectively larger than the heights of the middle air outlet narrow opening and the supporting table;

in the direction x, the width of the head end air outlet expansion opening and the tail end air outlet expansion opening is smaller than that of the middle air outlet narrow opening;

The air exhaust device is characterized by further comprising an air guide backboard arranged above the supporting table and close to the supporting table, wherein the air guide backboard is positioned in front of the cavity back wall and is provided with a space between the air guide backboard and the cavity back wall to form an air exhaust channel, the left side and the right side of the air guide backboard are respectively close to the left cavity side wall and the right cavity side wall, an expansion type air passing opening is respectively formed between the lower area of the air guide backboard and the left cavity side wall and between the lower area of the air guide backboard and the right cavity side wall, and the space width between the upper area of the air guide backboard and the left cavity side wall and the right cavity side wall in the left-right direction is smaller than the width of the expansion type air passing opening.

2. A ventilation device with an overwind channel according to claim 1, characterized in that the lower air compensator further comprises an upper housing forming part of the channel wall of the overwind channel and being located above the overwind channel, a movable cabinet door being provided on the operating window, which cabinet door rests against the upper housing when falling.

3. The ventilation device with the air-passing channel according to claim 2, wherein the lower air-compensating device further comprises plugs at the front and rear ends of the upper housing, the plugs comprise plug bodies for plugging the end parts of the air-passing channel and plug connecting parts for fixing the plug bodies on the upper housing, and the plug bodies of the plugs at the front and rear ends of the upper housing are respectively fixed on the left cavity side wall and the right cavity side wall.

4. A ventilation device with an overwind passage according to claim 2 or 3, wherein the lower air compensator further comprises air guiding fins extending along the flow path of the air compensator, the air guiding fins being arranged within the overwind passage.

5. The ventilation apparatus with an overwind passage of claim 4, further comprising a tab connector having one end connected to the wind-guiding tab and the other end connected to the upper housing.