CN113340036B

CN113340036B - Aquatic products are frozen machine fast for packing in advance

Info

Publication number: CN113340036B
Application number: CN202010974224.8A
Authority: CN
Inventors: 邓丽娟; 曾军; 全建华
Original assignee: Yuanling Tujiawang Food Co ltd
Current assignee: Yuanling Tujiawang Food Co ltd
Priority date: 2020-09-16
Filing date: 2020-09-16
Publication date: 2022-07-22
Anticipated expiration: 2040-09-16
Also published as: CN113340036A

Abstract

The invention discloses a quick freezer for aquatic product prepackaging, which comprises a tunnel-shaped shell, a conveying device, air curtain components arranged inside two ends of the shell, a sealing curtain arranged at the lower end of the air curtain components, a blower connected with the air curtain components, an air inlet on the shell and an electric cabinet fixedly connected on the shell, wherein rollers rotatably connected on two side walls of the shell are arranged at the bottom end inside the shell, a conveying chain is arranged on the conveying device, the lower end surface of the upper half part of the conveying chain is abutted against the rollers, a supporting rod is fixedly connected on the upper end surface of the shell, and a cross rod is hinged to the top end of the supporting rod. According to the invention, the arrangement of the baffles ensures that two ends of the shell are always in a closed state, so that the leakage of nitrogen is reduced, when a product packaging box passes through, the leakage generated by the matching of the baffles can be collected by the air pump and the air storage tank, and the air pump and the air storage tank are newly filled into the shell, so that the device effectively reduces the leakage of nitrogen under the matching of the air curtain and the sealing curtain.

Description

Aquatic products are frozen machine fast for packing in advance

Technical Field

The invention relates to the technical field of instant freezers, in particular to an instant freezer for aquatic product prepackaging.

Background

The quick freezing machine freezes the center temperature of the quick-frozen object to-18 ℃ in a short time, and quickly passes through an ice crystal production zone (between 0 and-5 ℃) within 30 minutes to achieve the purposes of reducing speed, reducing loss of nutrient components and keeping the original taste and flavor. A quick freezer is a highly efficient freezing apparatus capable of freezing a large amount of products in a short time. It is possible to efficiently and economically freeze various products such as meat, fish, shrimp, balls, vegetables, and prepared foods, dairy products, etc. in various shapes, which are placed inside the instant freezer.

The monomer tunnel type instant freezer usually uses liquid nitrogen, and the liquid nitrogen is inert, colorless, odorless, non-corrosive, non-combustible and extremely low in temperature. Nitrogen constitutes the majority of the atmosphere (78.03% by volume, 75.5% by weight). The nitrogen is inactive and does not support combustion. The frostbite is caused by a large amount of heat absorption contact during vaporization. Under normal pressure, the temperature of liquid nitrogen is-196 ℃; 1 cubic meter of liquid nitrogen can be expanded to 696 cubic meters of pure gaseous nitrogen at 21 ℃. Liquid nitrogen is a colorless, odorless, low-temperature liquid and gas at high pressure. Liquid nitrogen (often written as LN2) is a liquid form of nitrogen gas formed at low temperatures. The boiling point of nitrogen is-196 ℃, and liquid nitrogen is formed at normal atmospheric pressure if the temperature is below that; if pressurized, liquid nitrogen can be obtained at higher temperatures. In industry, liquid nitrogen is obtained by air fractionation. Air is first purified and then liquefied in pressurized and cooled environment, and the components in air are separated out based on their different boiling points. Nitrogen (78.09% of the air volume) was first bled off (and not liquefied), followed by 0.93% of the noble gas in air, and finally 20.95% of oxygen. Human skin is free of problems at the moment of direct contact with liquid nitrogen, and is frostbitten and irreversible in more than 2 seconds. The nitrogen leakage amount of the monomer tunnel quick-freezing equipment is too high, so that the oxygen content in the operation environment is reduced, and operators are suffocated in severe cases.

Therefore, the invention provides a quick freezer for aquatic product prepackaging.

Disclosure of Invention

The invention aims to: in order to solve the problems, the utility model provides a quick freezer for aquatic product prepackage.

In order to achieve the purpose, the invention adopts the following technical scheme:

a quick freezer for aquatic product prepackaging comprises a tunnel-shaped shell, a conveying device, air curtain components arranged inside two ends of the shell, a sealing curtain arranged at the lower end of the air curtain components, a blower connected with the air curtain components, an air inlet on the shell and an electric cabinet fixedly connected on the shell, wherein rollers rotatably connected to two side walls of the shell are arranged at the bottom end inside the shell, a conveying chain is arranged on the conveying device, the lower end surface of the upper half part of the conveying chain is abutted to the rollers, a supporting rod is fixedly connected to the upper end surface of the shell, a cross rod is hinged to the top end of the supporting rod, a sliding groove parallel to the cross rod is arranged on the cross rod, sliding sleeves are arranged inside the shell on two sides of the supporting rod, a baffle is slidably connected inside the sliding sleeves, the top end of the baffle penetrates through the shell, and a first cylindrical pin inserted in the sliding groove is fixedly connected to the top end of the baffle, the utility model discloses a pneumatic air conditioner, including shell, sliding sleeve, air curtain subassembly, air pump, air storage tank, air inlet, air storage tank, air pump two, the inside fixedly connected with electric jar of shell, and the extension end of electric jar runs through the shell, the tip fixedly connected with mounting of electric jar, have on the mounting to insert and establish the inside cylindric lock two of spout, the bottom fixedly connected with shrouding of sliding sleeve, and the bottom of baffle runs through the shrouding, the lower terminal surface fixedly connected with gyro wheel of baffle, touch switch and sealing strip are installed respectively to the both sides of baffle, are close to the outsidely be fixed with the air intake of installing on the shrouding between baffle and the air curtain subassembly, air intake connection has pipeline one, pipeline one crosses the connection together, and is connected with the air reservoir, install air pump two on pipeline between the intersection of air reservoir and pipeline one.

As a further description of the above technical solution:

sealed curtain comprises first curtain cloth and second curtain cloth, the length of first curtain cloth is greater than the length of second curtain cloth, first curtain cloth is the rectangle piece of cloth amalgamation with the second curtain cloth and forms, the concatenation seam dislocation set of first curtain cloth and second curtain cloth, the piece of cloth lower extreme fixedly connected with balancing weight of first curtain cloth and second curtain cloth, the balancing weight is the sheetmetal of clamp closure on the piece of cloth.

As a further description of the above technical solution:

the touch switch, the electric cylinder, the first air pump and the second air pump are electrically connected with the electric cabinet, and the touch switch is fixedly connected to the same side of the baffle.

As a further description of the above technical solution:

the air curtain component, the blower and the sealing curtain are symmetrically arranged at two ends of the shell.

As a further description of the above technical solution:

the supporting rod, the cross rod, the baffle, the electric cylinder, the sliding sleeve and the sealing plate are symmetrically arranged on the shell.

As a further description of the above technical solution:

the electric cylinder is located between one of the baffles and the air curtain assembly.

As a further description of the above technical solution:

the rollers are horizontally arranged in a row on the end face of the inner portion of the shell, and the distance between the rollers is 50 MM.

As a further description of the above technical solution:

the air curtain component is fixedly connected inside the shell and communicated with the blower, and the inner side wall of the air curtain component is fixedly connected with the sealing curtain.

As a further description of the above technical solution:

one side of the electric cabinet is the inlet side of the device, and one side of the touch switch which is fixedly connected to the baffle is positioned at the same side as the inlet side.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

1. according to the invention, the arrangement of the baffles ensures that two ends of the shell are always in a closed state, so that the leakage of nitrogen is reduced, when a product packaging box passes through, the leakage generated by the matching of the baffles can be collected by the air pump and the air storage tank, and the air pump and the air storage tank are newly filled into the shell, so that the device effectively reduces the leakage of nitrogen under the matching of the air curtain and the sealing curtain.

2. According to the invention, the arrangement of the touch switch is matched with the action of the electric cylinder and the cross bar, so that the baffle plate can react rapidly, the influence on the conveying of the product packaging box on a conveying chain is avoided, and the arrangement of the roller column avoids the water in the packaging box from being scattered and frozen.

3. According to the invention, the sealing plates are arranged, so that the space at the two ends of the shell is reduced, the overflow of air and the suction amount of the first air pump are reduced, the air inlet is formed in each sealing plate, nitrogen is sucked in time, the overflow of nitrogen from the air curtain is reduced, and the nitrogen in the operation environment meets the requirement.

Drawings

FIG. 1 is a schematic diagram of a front view internal structure of a quick freezer for aquatic product prepackaging, which is provided by the invention;

FIG. 2 is a schematic structural diagram of a front view of the instant freezer for aquatic product prepackaging, which is provided by the invention;

FIG. 3 is an enlarged schematic structural diagram of a part B of the instant freezer for aquatic product prepackaging, which is provided by the invention;

FIG. 4 is an enlarged schematic structural diagram of part C of the instant freezer for aquatic product prepackaging according to the present invention;

fig. 5 is a schematic structural view of a sealing curtain of the instant freezer for aquatic product prepackaging provided by the invention.

Illustration of the drawings:

1. a housing; 2. a conveying device; 201. a conveyor chain; 3. a roller; 4. a support bar; 5. a cross bar; 501. a chute; 6. a baffle plate; 601. a first cylindrical pin; 7. an electric cylinder; 8. a sliding sleeve; 9. closing the plate; 10. an air curtain assembly; 11. a blower; 12. a sealing curtain; 1201. a first cloth curtain; 1202. a second curtain; 13. a counterweight block; 14. an air inlet; 15. a first pipeline; 16. a first air pump; 17. a gas storage tank; 18. a second air pump; 19. a second pipeline; 20. an air inlet; 21. an electric cabinet; 22. a touch switch; 23. a roller; 24. a seal strip; 25. a fixing member; 2501. and a second cylindrical pin.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

Referring to fig. 1-5, a freezer for pre-packaging aquatic products includes a tunnel-shaped housing 1, a conveyor 2, an air curtain assembly 10 installed inside two ends of the housing 1, a sealing curtain 12 installed at a lower end of the air curtain assembly 10, a blower 11 connected to the air curtain assembly 10, an air inlet 20 on the housing 1, and an electric cabinet 21 fixedly connected to the housing 1, wherein the conveyor 2 mainly feeds the aquatic products to the inside of the housing 1. Tunnel type's frozen machine carries out the quick freezing with the product of prepackage, effectually advance fresh-keeping to the product, air curtain subassembly 10 forms a slice air curtain with 11 air supplys of hair-dryer, the effectual inside nitrogen gas that prevents shell 1 overflows, perhaps outside air admission shell 1's inside, among the prior art, set up the air curtain also in order to reduce nitrogen gas's among the operational environment content, reduce leaking of the inside nitrogen gas of device, electric cabinet 21 is for having control circuit, circuit processing system, and operating panel. The roller columns 3 rotatably connected to two side walls of the shell 1 are arranged at the bottom end inside the shell 1, the conveying device 2 is provided with the conveying chain 201, the lower end face of the upper half part of the conveying chain 201 is abutted against the roller columns 3, the roller columns 3 are arranged to avoid vibration and abrasion caused by friction between the conveying chain 201 and the bottom wall of the shell 1, the more the roller columns 3 in a single row are arranged, the more stable the conveying process of products on the conveying chain 201 is, the supporting rod 4 is fixedly connected to the upper end face of the shell 1, the top end of the supporting rod 4 is hinged to the cross rod 5, the cross rod 5 is provided with a sliding groove 501 parallel to the cross rod 5, sliding sleeves 8 are arranged on two sides of the supporting rod 4 inside the shell 1, the sliding sleeves 8 are the same as the baffle 6 and the width inside the shell 1, the vertical movement effect of the baffle 6 is realized, the baffle 6 is connected inside the sliding sleeve 8, and the top end of the baffle 6 penetrates through the shell 1, the top end of the baffle 6 is fixedly connected with a first cylindrical pin 601 inserted in the sliding groove 501, the interior of the shell 1 is fixedly connected with an electric cylinder 7, the extending end of the electric cylinder 7 penetrates through the shell 1, the end part of the electric cylinder 7 is fixedly connected with a fixing piece 25, the fixing piece 25 is provided with a second cylindrical pin 2501 inserted in the sliding groove 501, the bottom end of the sliding sleeve 8 is fixedly connected with a sealing plate 9, the bottom end of the baffle 6 penetrates through the sealing plate 9, the sealing plate 9 is arranged to isolate the space above the sliding sleeve 8 from the interior space of the shell 1, the space at the two ends of the shell 1 is reduced, the lower end surface of the baffle 6 is fixedly connected with a roller 23, the roller 23 is abutted against the conveying chain 201, two sides of the baffle 6 are respectively provided with a touch switch 22 and a sealing strip 24, an air inlet 14 arranged on the sealing plate 9 is fixedly arranged between the baffle 6 close to the outside and the air curtain component 10, the air inlet 14 is connected with a first pipeline 15, and the first pipeline 15 is connected together in an intersecting way, and is connected with an air storage tank 17, a first air pump 16 is arranged on the first pipeline 15 between the intersection of the air storage tank 17 and the first pipeline 15, the air storage tank 17 is connected with an air inlet 20 through a second pipeline 19, and a second air pump 18 is arranged on the second pipeline 19.

The sealing curtain 12 is composed of a first cloth curtain 1201 and a second cloth curtain 1202, the length of the first cloth curtain 1201 is larger than that of the second cloth curtain 1202, the first cloth curtain 1201 and the second cloth curtain 1202 are formed by splicing rectangular cloth pieces, the splicing seams of the first cloth curtain 1201 and the second cloth curtain 1202 are arranged in a staggered mode, the lower ends of the cloth pieces of the first cloth curtain 1201 and the second cloth curtain 1202 are fixedly connected with a balancing weight 13, and the balancing weight 13 is a metal sheet clamped on the cloth pieces.

The touch switch 22, the electric cylinder 7, the first air pump 16 and the second air pump 18 are electrically connected with the electric cabinet 21, and the touch switch 22 is fixedly connected to the same side of the baffle 6.

The air curtain assembly 10, the blower 11, and the sealing curtain 12 are symmetrically disposed at both ends of the housing 1.

The supporting rod 4, the cross rod 5, the baffle 6, the electric cylinder 7, the sliding sleeve 8 and the sealing plate 9 are symmetrically arranged on the shell 1.

An electric cylinder 7 is located between one of the baffles 6 and the air curtain assembly 10.

The rollers 3 are horizontally arranged in a row on the end surface of the inner part of the shell 1, and the distance between the rollers 3 is 50 MM.

The blower 11 is fixedly connected to the upper end of the housing 1, the air curtain assembly 10 is fixedly connected to the inside of the housing 1 and communicated with the blower 11, and the sealing curtain 12 is fixedly connected to the inner side wall of the air curtain assembly 10.

One side of the electric cabinet 21 is the inlet side of the device, and one side of the touch switch 22 fixedly connected to the baffle 6 is the same side as the inlet side.

The working principle is as follows: when the device is used, aquatic product prepackaged products needing quick freezing enter the tunnel type quick freezer, the products are conveyed by the conveying chain 201 of the conveying device 2, the row of rollers 3 in the shell 1 enables the products to vibrate slightly, so that water in a container for containing the products is prevented from spilling, severe icing in the device is avoided, the use of the device is influenced, the air curtain formed by matching the air curtain assemblies 10 at the two ends of the shell 1 with the blower 11 enables the nitrogen leakage to be greatly reduced, the sealing curtain 12 is provided with the first cloth curtain 1201 and the second cloth curtain 1202, the cloth splicing seams of the first cloth curtain 1201 and the second cloth curtain 1202 are arranged in a staggered mode, the purpose of reducing the internal gas leakage is achieved, the bottom ends of the first cloth curtain 1201 and the second cloth curtain 1202 are fixedly connected with the balancing weight 13, the balancing weight 13 enables the cloth sealing curtain 12 to be in a vertically stretched state, the electric cylinder 7 pulls or pushes the cross rod 5, the fixing piece 2501 on the fixing piece 25 enables one end of the cross rod 5 to move, horizontal pole 5 articulates on bracing piece 4, and the setting of spout 501 can make baffle 6 take place the ascending motion of vertical side, and the condition that is located baffle 6 of tunnel import side is: baffle 6 that is close to electric jar 7, its bottom can be with the conveying chain 201 butt, and baffle 6 that is far away from electric jar 7 upward movement, and the distance of baffle 6 and conveying chain 201 allows product and packing carton to pass through here, and the condition of baffle 6 that is located the tunnel exit side is: the electric cylinder 7 is extended, the baffle 6 close to the electric cylinder 7 moves upward, and the bottom end of the baffle 6 far from the electric cylinder 7 abuts against the conveying chain 201. In the conveying process of a product packaging box, a sealing curtain 12 is extruded to enter a region between the sealing curtain 12 and a baffle 6, when the product packaging box touches a touch switch 22, an electric cabinet 21 receives an instruction to control an electric cylinder 7 to extend, the positions of two quick baffles 6 in the vertical direction are exchanged, the product packaging box continues to move to touch the touch switch 22 of a second baffle 6, the electric cabinet 21 controls the electric cylinder 7 to enable the baffles 6 to exchange positions again, the distance between the baffles 6 is set to meet the size of a product, the region in the middle of a shell 1 is a nitrogen filling region of liquid nitrogen to realize quick freezing of the product, when the baffle 6 close to the outer side on the device is abutted against a conveying chain 201, the electric cabinet 21 controls an air pump I16 to suck air between the baffles 6 and the sealing curtain 12 and recycle the air into an air storage tank 17, and the air in the air storage tank 17 is supplemented into the shell 1 through an air inlet 20 by an air pump II, when liquid nitrogen is supplemented into the shell 1, the internal pressure is increased, the intermittent pumping of the air pump I16 enables the leakage amount of the nitrogen in the shell to be reduced, and the content of the nitrogen in the working environment is effectively controlled.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. A quick freezer for aquatic product prepackaging comprises a tunnel-shaped shell (1), a conveyor (2), an air curtain component (10) arranged inside two ends of the shell (1), a sealing curtain (12) arranged at the lower end of the air curtain component (10), a blower (11) connected with the air curtain component (10), an air inlet (20) on the shell (1) and an electric cabinet (21) fixedly connected on the shell (1), and is characterized in that the bottom end inside the shell (1) is provided with rollers (3) rotatably connected on two side walls of the shell (1), the conveyor (2) is provided with a conveyor chain (201), the lower end face of the upper half part of the conveyor chain (201) is abutted against the rollers (3), the upper end face of the shell (1) is fixedly connected with a support rod (4), and the top end of the support rod (4) is hinged with a cross rod (5), the cross bar (5) is provided with a sliding groove (501) which is parallel to the cross bar (5), two sides of the support bar (4) are provided with a sliding sleeve (8) in the shell (1), the sliding sleeve (8) is connected with a baffle (6) in a sliding manner, the top end of the baffle (6) penetrates through the shell (1), the top end of the baffle (6) is fixedly connected with a first cylindrical pin (601) which is inserted in the sliding groove (501), the shell (1) is fixedly connected with an electric cylinder (7), the extension end of the electric cylinder (7) penetrates through the shell (1), the end part of the electric cylinder (7) is fixedly connected with a fixing part (25), the fixing part (25) is provided with a second cylindrical pin (2501) which is inserted in the sliding groove (501), the bottom end of the sliding sleeve (8) is fixedly connected with a sealing plate (9), the bottom end of the baffle (6) penetrates through the sealing plate (9), and the lower end surface of the baffle (6) is fixedly connected with a roller (23), a touch switch (22) and a sealing strip (24) are respectively installed on two sides of the baffle (6), an air inlet (14) installed on the sealing plate (9) is fixedly arranged between the baffle (6) close to the outside and the air curtain assembly (10), the air inlet (14) is connected with a first pipeline (15), the first pipeline (15) is connected with a first air storage tank (17) in an intersecting mode, a first air pump (16) is installed on the first pipeline (15) between the first air storage tank (17) and the first pipeline (15) in an intersecting mode, the first air storage tank (17) is connected with an air inlet (20) through a second pipeline (19), and a second air pump (18) is installed on the second pipeline (19);

one side of the electric cabinet (21) is the inlet side of the device, and the touch switch (22) is fixedly connected to the baffle (6) at the same side as the inlet side;

product packaging box is in transportation process, the sealed curtain of extrusion (12) gets into the region between sealed curtain (12) and baffle (6), when product packaging box touches touch switch (22), electric cabinet (21) received the instruction, control electric jar (7) extension, the interchange takes place for the position in the vertical side of two fast baffles (6), product packaging box continues the motion and touches touch switch (22) of second baffle (6), electric cabinet (21) control electric jar (7) make baffle (6) the position interchange once more.

2. The quick freezer for the pre-packaging of aquatic products according to claim 1, characterized in that the sealing curtain (12) is composed of a first cloth curtain (1201) and a second cloth curtain (1202), the length of the first cloth curtain (1201) is greater than that of the second cloth curtain (1202), the first cloth curtain (1201) and the second cloth curtain (1202) are formed by splicing rectangular cloth pieces, the splicing seams of the first cloth curtain (1201) and the second cloth curtain (1202) are arranged in a staggered manner, the lower ends of the cloth pieces of the first cloth curtain (1201) and the second cloth curtain (1202) are fixedly connected with a balancing weight (13), and the balancing weight (13) is a metal sheet clamped on the cloth pieces.

3. The instant freezer for the aquatic product prepackaging according to claim 1, characterized in that the touch switch (22), the electric cylinder (7), the first air pump (16) and the second air pump (18) are electrically connected with the electric cabinet (21), and the touch switch (22) is fixedly connected with the same side of the baffle (6).

4. A freezer for prepackaging aquatic products according to claim 1, characterized in that said air curtain assembly (10), blower (11) and sealing curtain (12) are symmetrically arranged at both ends of the casing (1).

5. The instant freezer for aquatic product prepackaging according to claim 1, characterized in that the support bar (4), cross bar (5), baffle (6), electric cylinder (7), sliding sleeve (8) and closing plate (9) are symmetrically arranged on the housing (1).

6. An instant freezer for prepackaging of aquatic products according to claim 1, characterized in that the electric cylinder (7) is located between one of the baffles (6) and the air curtain assembly (10).

7. A quick freezer for prepackaging aquatic products according to claim 1, characterized in that said rollers (3) are arranged in a row horizontally on the end surface of the inside of the casing (1), and the distance between the rollers (3) is 50 MM.

8. A quick freezer for prepackaging aquatic products according to claim 1, characterized in that said air blower (11) is fixedly connected to the upper end of the housing (1), said air curtain assembly (10) is fixedly connected to the inside of the housing (1) and is in communication with the air blower (11), and said air curtain assembly (10) has a sealing curtain (12) fixedly connected to the inner side wall.