CN112845485A

CN112845485A - Ventilation cabinet

Info

Publication number: CN112845485A
Application number: CN202110075523.2A
Authority: CN
Inventors: 杨光友; 王培成; 沈志扬
Original assignee: Pudong New Area Zhouqiao Occupational Safety And Health Office Shanghai
Current assignee: Pudong New Area Zhouqiao Occupational Safety And Health Office Shanghai
Priority date: 2021-01-20
Filing date: 2021-01-20
Publication date: 2021-05-28
Anticipated expiration: 2041-01-20
Also published as: CN112845485B

Abstract

The utility model relates to a fume chamber, the intelligent cabinet temperature adjusting device comprises a cabinet body, the internal rotation of working chamber is connected with two axis of rotation that are parallel to each other, all set up drive gear on the both ends outer wall of axis of rotation, be equipped with the gear area on the door plant, the cabinet body is equipped with the balancing weight on keeping away from one side of door plant, the gear area is around establishing two drive gear and connecting in the balancing weight, be equipped with the convex seat on the relative inner wall of working chamber, the cover is equipped with the slide cartridge on the lateral wall of convex seat, the convex seat is close to one of the inner wall of working chamber and serves and is equipped with the electromagnetic block, the one end setting that the slide cartridge is close to the electromagnetic block can adsorb in the magnetic ring of electromagnetic block, be equipped with limit structure between axis of rotation and the slide cartridge and make the. This application has the effect that just can slide the door plant after opening the exhaust fan.

Description

Ventilation cabinet

Technical Field

The application relates to the field of test equipment, in particular to a fume hood.

Background

Currently, fume hoods are an integral part of laboratory ventilation settings, and such experiments are often conducted in fume hoods to prevent laboratory workers from inhaling or swallowing toxic, potentially pathogenic or non-toxic chemicals and organisms.

The utility model discloses a chinese utility model patent document that has a current bulletin number CN206168921U discloses a novel fume chamber is used in chemistry experiment room, including last cabinet and lower cabinet, the junction of going up cabinet and lower cabinet is the operation mesa, it includes the steel frame to go up the cabinet, the fire prevention welt is installed to the upper portion and the lateral part of steel frame, thereby form the space of operation, the glass sliding door is installed in the front of going up the cabinet, the back mounted of going up the cabinet has the balancing weight, the sprocket is installed at the top of going up the cabinet, connect the transmission through the chain between glass sliding door and the balancing weight and connect, thereby realize sliding from top to bottom of glass sliding door, the gas collecting channel is still installed at the top of going up the cabinet, the gas collecting channel is connected in exhaust duct, the air discharge fan can all be installed usually in the gas collecting channel, under the effect of air discharge fan.

In view of the above-mentioned related technologies, the inventor believes that some workers or students may directly slide the glass sliding door away and forget to turn on the exhaust fan during the experiment, so that some gases in the experiment process cannot be discharged in time and enter the laboratory, which affects the laboratory environment.

Disclosure of Invention

In order to reduce among the test process staff and forget the condition of opening the exhaust fan, this application provides a fume chamber.

The application provides a fume chamber adopts following technical scheme:

a ventilation cabinet comprises a cabinet body, wherein a working cavity is arranged on the cabinet body, an air suction cover is arranged at the top of the cabinet body, an exhaust fan is arranged in the air suction cover, an opening is formed in one side of the cabinet body, a door plate for covering the opening is connected to the cabinet body in a vertical sliding manner, two rotating shafts which are parallel to each other are connected to the rotating shaft in the working cavity in a rotating manner, driving gears are arranged on the outer walls of the two ends of each rotating shaft, a gear belt is arranged on the door plate, a balancing weight is arranged on one side of the cabinet body away from the door plate, the gear belt is wound by the two driving gears and connected to the balancing weight, convex seats are arranged on the opposite inner walls of the working cavity, the rotating shafts are rotatably connected between the two convex seats, a sliding cylinder is sleeved on the side wall of each convex seat, an electromagnetic block is arranged at one, the electromagnetic block switch comprises a sliding cylinder, a convex seat and a limiting structure, wherein the sliding cylinder is connected with the convex seat through a convex seat, the magnetic ring is arranged at one end, close to the electromagnetic block, of the sliding cylinder and can be adsorbed on the electromagnetic block, the magnetic ring is connected to the end face of the sliding cylinder in a rotating mode, the limiting structure is arranged between the rotating shaft and the sliding cylinder, so that the rotating shaft can rotate to drive the sliding cylinder to rotate synchronously, a collision structure is arranged between the sliding cylinder and the convex seat and used for limiting the rotation of.

Through adopting above-mentioned technical scheme, can be in order to open and shut the opening through the door plant that slides from top to bottom, carry out experimental reaction in the working chamber, need open the exhaust fan, the exhaust fan can make the electromagnetic block have magnetism after opening, thereby make the sliding cylinder that has the magnetic ring can be adsorbed by the electromagnetic block, this in-process sliding cylinder slides to the direction of electromagnetic block, until the magnetic ring adsorbs on the electromagnetic block, the magnetic ring rotates and connects on the terminal surface of sliding cylinder, and conflict state between sliding cylinder and the boss is relieved, thereby make the sliding cylinder rotate, and when the exhaust fan did not open, can not rotate under the conflict state again between sliding cylinder and the boss, thereby make the axis of rotation can not rotate, thereby realize just can carrying out gliding effect opening the door plant behind the exhaust fan.

Optionally, the one end of a sliding barrel extends to the direction of keeping away from the boss, and the one end of axis of rotation is located the inside of a sliding barrel, limit structure is including locating the axis of rotation outer wall and along the spacing post of the radial extension of axis of rotation, limit structure is still including seting up the spacing groove in the sliding barrel outer wall, the extending direction in spacing groove is on a parallel with the axial direction of a sliding barrel, spacing post extends into the spacing inslot.

Through adopting above-mentioned technical scheme, spacing post extends into the spacing inslot to make the sliding barrel can be along the axial motion of axis of rotation, and the axis of rotation rotates and can drive the sliding barrel and rotate under the effect of spacing post.

Optionally, the conflict structure is including locating the first conflict piece on the one end outer wall of electromagnetism piece is kept away from to the convex seat, the one end that first conflict piece is close to the electromagnetism piece is most advanced structure, leaves the space between the adjacent first conflict piece, the conflict structure is still including the second conflict piece of locating the sliding cylinder inner wall, the one end that the second conflict piece is close to the axis of rotation sets up to most advanced structure, when the sliding cylinder slides to the direction of keeping away from the electromagnetism piece, the second conflict piece can be pegged graft in the clearance between the first conflict piece, be equipped with on the electromagnetism piece and be used for driving the second to conflict piece to the driving piece of first conflict piece motion.

Through adopting above-mentioned technical scheme, conflict when the second conflicts the piece and contradict in the space between the first conflict piece to make between sliding cylinder and the convex seat spacing, the sliding cylinder can not rotate on the convex seat, thereby makes the axis of rotation can not rotate, realizes that the door plant can not carry out gliding effect.

Optionally, a mounting groove coaxial with the boss is formed in the electromagnetic block, the driving member includes a spring disposed on an outer wall of the boss, one end of the spring is located in the mounting groove, the other end of the spring has a portion extending out of the surface of the electromagnetic block, and when the magnetic ring is attached to the electromagnetic block, the spring is compressed in the mounting groove by the magnetic ring.

Through adopting above-mentioned technical scheme, when the magnetic ring adsorbs on the electromagnetic block, the spring is in the state of compressed, and after the electromagnetic block lost magnetism, the drive sliding barrel slided to the direction of keeping away from the electromagnetic block under the spring action of spring to make first conflict piece and second conflict piece contradict each other, make the sliding barrel can not continue to rotate again.

Optionally, an annular groove is formed in one end face, close to the electromagnetic block, of the sliding cylinder, a ring protrusion is arranged at one end of the magnetic ring, and the ring protrusion can rotate in the annular groove.

Through adopting above-mentioned technical scheme, realize the rotation of magnetic ring and slide cartridge through annular and ring arch and be connected, simple structure connects conveniently.

Optionally, the opposite side walls of the working cavity are provided with strip seats, the strip seats are vertically arranged and internally provided with sliding grooves, the sliding grooves are internally and vertically connected with sliding plates in a sliding manner, the lower ends of the sliding plates are provided with elastic blocks, the elastic blocks are abutted with the inner walls of the sliding grooves, one sides of the sliding plates, which are close to the sliding cylinder, are provided with saw-shaped racks, one sides of the saw-shaped racks, which are far away from the electromagnetic blocks, are provided with tip structures, the outer walls of the sliding cylinders are uniformly provided with meshing teeth along the circumferential direction of the sliding cylinders, one ends of the meshing teeth, which face the saw-shaped racks, are provided with tip structures, when the sliding cylinders slide towards the direction of the electromagnetic blocks, the meshing teeth can be meshed with the saw-shaped racks, when the door plate covers the opening of the cabinet body, the saw-shaped racks and the meshing teeth of the lower side walls, the upper end of the sliding plate can be inserted into the yielding seat, and the side wall of the lower end of the strip seat is provided with an air blowing hole which is inclined towards the working cavity.

Through adopting above-mentioned technical scheme, when the sliding cylinder slides to the direction of electromagnetic block, the meshing tooth can mesh with the saw-shaped rack mutually, thereby make the in-process sliding cylinder rotation at the slip door plant slide from top to bottom driving the slide, and the door plant lid fits when the opening, the lower extreme and the meshing tooth meshing of slide, thereby make when the door plant that upwards slides, thereby the sliding cylinder rotates the drive slide and slides downwards, the slide slides downwards and can compress the air in the spout and blow to the working chamber from the hole of blowing, thereby gaseous possibility of running out from the working chamber when reducing and opening the door plant.

Optionally, the sliding plate is provided with a limiting groove penetrating through the surface of the sliding plate, a limiting plate is connected in the limiting groove in a vertical sliding manner, and the saw-shaped rack is arranged on one side of the limiting plate extending out of the limiting groove.

Through adopting above-mentioned technical scheme, the in-process of meshing tooth to the motion of saw-shaped rack, the limiting plate can slide from top to bottom to when making meshing tooth and saw-shaped rack position have the deviation, also can mesh mutually.

Optionally, the cross section of the limiting groove is of a T-shaped structure.

Through adopting above-mentioned technical scheme, the limiting plate is more stable at the spacing inslot.

In summary, the present application includes at least one of the following beneficial technical effects:

1. under the condition of opening the exhaust fan, the electromagnetic block can be electrified, so that the magnetic ring is adsorbed on the electromagnetic block, the sliding door plate can rotate, and when the fan is not opened, the rotating shaft cannot rotate, so that the door plate cannot slide;

2. when the door plate slides upwards, the air blowing holes can blow air into the working cavity, so that air is prevented from escaping out of the working cavity when the door plate is opened.

Drawings

FIG. 1 is a schematic structural diagram of an embodiment of the present application;

FIG. 2 is a rear schematic view of a cabinet according to an embodiment of the present application;

FIG. 3 is a schematic view of the internal structure of the cabinet in the embodiment of the present application;

FIG. 4 is a schematic view of a connection structure between a door plate and a weight member in an embodiment of the present application;

FIG. 5 is a schematic view of the boss and shuttle and explosion configuration of an embodiment of the present application;

fig. 6 is an enlarged schematic view at a in fig. 3.

Description of reference numerals: 1. a cabinet body; 2. a working chamber; 3. an air intake cover; 4. an exhaust fan; 5. an opening; 6. a door panel; 7. a rotating shaft; 8. a gear belt; 9. a drive gear; 10. a balancing weight; 11. a boss; 12. a sliding cylinder; 13. an electromagnetic block; 14. a magnetic ring; 15. a limiting structure; 151. a limiting column; 152. a limiting groove; 16. a contact structure; 161. a first contact block; 162. a second contact block; 17. a drive member; 171. a spring; 18. mounting grooves; 19. the ring is convex; 20. a ring groove; 21. a strip seat; 22. a chute; 23. a slide plate; 24. an elastic block; 25. a saw-shaped rack; 26. meshing teeth; 27. a relief seat; 28. a gas blowing hole; 29. a long groove; 30. and a limiting plate.

Detailed Description

The present application is described in further detail below with reference to figures 1-6.

The embodiment of the application discloses fume chamber. Referring to fig. 1 and 2, the fume chamber includes a cabinet body 1, a working chamber 2 is provided in the cabinet body 1, and the reaction process of the test is performed in the working chamber 2. The opening 5 of intercommunication working chamber 2 is seted up to the lateral wall of the cabinet body 1 to sliding connection has a door plant 6 that is used for coveing opening 5 about the lateral wall, runs out with the gas in the reduction test procedure, and door plant 6 can partial installation glass, is convenient for conveniently observe working chamber 2. The cabinet body 1 is provided with a groove for the door panel 6 to slide up and down. The top of the cabinet body 1 is provided with an air suction cover 3, an exhaust fan 4 is arranged in the air suction cover 3, some gases generated in the working cavity 2 can be discharged under the action of the exhaust fan 4, and the air suction cover 3 is connected to an exhaust pipeline.

Referring to fig. 3 and 4, two parallel rotating shafts 7 are rotatably connected in the working chamber 2, and driving gears 9 are coaxially fixed on both side walls of the rotating shafts 7. Door plant 6 is fixed with gear belt 8 on the one side towards working chamber 2, and two and gear belt 8 are installed to gear belt 8 and are fixed in the lower extreme position of door plant 6. The gear belt 8 is engaged with a drive gear 9 and passes around the drive gear 9 provided on the two rotation shafts 7. One end fixedly connected with balancing weight 10 that door plant 6 was kept away from to gear belt 8 to make promotion door plant 6 can drive axis of rotation 7 and rotate, thereby control door plant 6's position.

Referring to fig. 3 and 5, a boss 11 is fixed in the working chamber 2 at a position close to the door panel 6, two bosses 11 are arranged on the opposite inner walls of the working chamber 2 and at positions close to the door panel 6, and the boss 11 is of a cylindrical structure. One of the rotary shafts 7 is rotatably connected between the two bosses 11 through a bearing, and the other rotary shaft 7 is rotatably connected to the inner wall of the working chamber 2 through a bearing.

Referring to fig. 4 and 5, a sliding cylinder 12 is sleeved on an outer wall of the boss 11, and the sliding cylinder 12 can slide along an axial direction of the boss 11. An electromagnetic block 13 is further fixed on the outer wall of the boss 11, and the electromagnetic block 13 is fixed on the outer wall of one end of the boss 11 close to the inner wall of the working chamber 2. The electromagnetic block 13 is electrically connected with the exhaust fan 4, and when the exhaust fan 4 is turned on, the electromagnetic block 13 can be electrified and has magnetism. One end of the sliding cylinder 12 close to the electromagnetic block 13 is rotatably connected with a magnetic ring 14, when the electromagnetic block 13 has magnetism, the magnetic ring 14 can be adsorbed on the electromagnetic block 13, so as to drive the sliding cylinder 12 to slide towards the electromagnetic block 13, the magnetic ring 14 is rotatably connected with the sliding cylinder 12, so that after the magnetic ring 14 is adsorbed on the electromagnetic block 13, the sliding cylinder 12 can still rotate. A limiting structure 15 is arranged between the sliding cylinder 12 and the rotating shaft 7, so that the rotating shaft 7 can drive the sliding cylinder 12 to rotate together. Install conflict structure 16 between slide cartridge 12 and the boss 11, under conflict structure 16's effect, slide cartridge 12 can not rotate on the outer wall of boss 11 to make under conflict structure 16's effect rotating shaft 7 also can not rotate, and when electromagnetism piece 13 circular telegram and when magnetic, magnetic ring 14 adsorbs back on electromagnetism piece 13, can remove the conflict effect between boss 11 and the slide cartridge 12, thereby make slide cartridge 12 can rotate, door plant 6 can slide from top to bottom this moment.

Referring to fig. 5, an annular groove 20 is formed in an end surface of the sliding cylinder 12 close to the electromagnetic block 13, an annular protrusion 19 is disposed at an end of the magnetic ring 14 close to the sliding cylinder 12, the annular protrusion 19 can rotate in the annular groove 20, so that the magnetic ring 14 and the sliding cylinder 12 are rotatably connected, and the magnetic ring 14 and the sliding cylinder 12 cannot be separated under the limiting action of the annular groove 20 of the annular protrusion 19. To facilitate the connection of the magnetic ring 14 and the sliding cylinder 12, the sliding cylinder 12 may be a half-split structure.

Referring to fig. 5, one end of the sliding cylinder 12 away from the electromagnetic block 13 extends toward the rotation shaft 7, the limiting structure 15 includes a limiting groove 152 formed on an outer wall of the sliding cylinder 12, and a length direction of the limiting groove 152 is parallel to a length direction of the sliding cylinder 12. The limiting structure 15 further includes a limiting column 151 fixed on the outer wall of the rotating shaft 7, and the limiting column 151 extends along the radial direction of the rotating shaft 7 and extends into the limiting groove 152. Under the effect of spacing post 151 and spacing groove 152, axis of rotation 7 rotates and can drive slide cartridge 12 synchronous rotation to when slide cartridge 12 slided along the axial of boss 11, spacing post 151 can slide in spacing groove 152.

Referring to fig. 5, the collision structure 16 includes a plurality of first contact blocks 161 fixed on an outer wall of an end of the boss 11 far away from the electromagnetic block 13, and the first contact blocks 161 are uniformly distributed along a circumferential direction of the boss 11, and the end of the first contact block 161 facing the electromagnetic block 13 is set to be a tip structure, so that the first contact blocks 161 are distributed in a zigzag manner and leave a certain space. The interference structure 16 further includes a second contact block 162 fixed on the inner wall of the sliding cylinder 12, the structure of the second contact block 162 is the same as that of the first contact block 161, and the tip of the second contact block 162 is opposite to that of the first contact block 161, so that the first contact block 161 can be engaged with the second contact block 162. When the first abutting block 161 and the second abutting block 162 are engaged, the sliding cylinder 12 cannot rotate; when the first contact block 161 and the second contact block 162 are away from each other without engagement, the spool 12 can rotate on the boss 11.

Referring to fig. 5, the electromagnet block 13 is further provided with a driving member 17 for driving the sliding cylinder 12 to slide away from the electromagnet block 13, so that when the electromagnet block 13 is not magnetic, the second contact block 162 is driven to move towards the first contact block 161, and the second contact block 162 can be engaged with the first contact block 161. The electromagnetic block 13 is provided with an installation groove 18 coaxial with the boss 11, the driving part 17 comprises a spring 171 arranged in the installation groove 18, one end of the spring 171 is fixed in the installation groove 18, the other end of the spring 171 is provided with a surface extending out of the electromagnetic block 13, when the magnetic ring 14 is adsorbed on the electromagnetic block 13, the magnetic ring 14 can firstly abut against one end of the spring 171 and compress the spring 171, and the compressed spring 171 is accommodated in the installation groove 18; when the electromagnet block 13 is not magnetic, the slide cylinder 12 is driven to slide in a direction away from the electromagnet block 13 by the elastic force of the spring 171.

Referring to fig. 5 and 6, a bar seat 21 is fixed to opposite inner walls of the working chamber 2, and the bar seat 21 is vertically disposed and disposed at a position close to the door panel 6. The strip seat 21 is provided with a sliding groove 22 therein, and the sliding groove 22 extends along the length direction of the strip seat 21. Sliding plate 23 is connected to the interior of rectangular seat 21 in a sliding manner from top to bottom, elastic block 24 is welded or bonded to the lower end of sliding plate 23, elastic block 24 can be a rubber block or a silica gel block, and elastic block 24 is abutted to the inner wall of sliding groove 22, so that sliding plate 23 cannot slide in sliding groove 22 under the action of friction force between elastic block 24 and sliding groove 22. The sliding plate 23 has a portion extending out of the upper end of the elongated seat 21, and a saw-shaped rack 25 is mounted on an end of the sliding plate 23 close to the sliding cylinder 12, and a meshing tooth 26 is fixed on the outer wall of the sliding cylinder 12, and the meshing tooth 26 can mesh with the saw-shaped rack 25, so that the sliding cylinder 12 rotates to drive the sliding plate 23 to slide up and down in the sliding chute 22. The side wall of the lower end of the long seat 21 is provided with a plurality of air blowing holes 28 penetrating through the sliding chute 22, the air blowing holes 28 are obliquely arranged towards the working cavity 2, and when the sliding plate 23 slides downwards, air in the sliding chute 22 can be compressed and flows into the working cavity 2 from the air blowing holes 28.

Referring to fig. 5 and 6, one end of the saw-shaped rack 25 away from the electromagnetic block 13 is provided with a tip structure, and one end of the meshing tooth 26 facing the electromagnetic block 13 is provided with a tip structure, when the electromagnetic block 13 is magnetic after being powered on, the magnetic ring 14 slides towards the direction of the electromagnetic block 13, so that the meshing tooth 26 can move towards the saw-shaped rack 25, and the meshing tooth 26 and the saw-shaped rack 25 can be meshed easily. And when the door panel 6 is in a position on the cabinet 1 to close the opening 5, the saw-shaped rack 25 and the engaging tooth 26 at the lower end of the sliding plate 23 are engaged. When the door panel 6 slides upwards, the rotating shaft 7 is driven to rotate, the rotating shaft 7 rotates to drive the sliding cylinder 12 to rotate together, the meshing teeth 26 on the outer wall of the sliding cylinder 12 are meshed with the saw-shaped rack 25, so that the sliding plate 23 slides downwards, air in the compression sliding chute 22 is blown to the working cavity 2 from the air blowing hole 28, and therefore air can be prevented from leaking out of the working cavity 2 when the door panel 6 is opened. Referring to fig. 2, when the door panel 6 slides downwards, the sliding plate 23 can slide upwards, the hollow abdicating seat 27 inside is fixed on the upper end surface of the cabinet body 1, and the upper end of the sliding plate 23 can be inserted into the abdicating seat 27 in the upwards sliding process, so as to provide a movement space at the upper end of the sliding plate 23.

Referring to fig. 5 and 6, the sliding plate 23 is provided with a long groove 29 penetrating through the surface of the sliding plate 23, the cross section of the long groove 29 is a T-shaped structure, a limiting plate 30 is connected in the long groove 29, the structure of the limiting plate 30 is matched with the long groove 29, and the length of the long groove 29 is slightly greater than that of the limiting plate 30, so that the limiting plate 30 can slide up and down in the long groove 29 to a certain extent. One side of the limit plate 30 extends out of the surface of the sliding plate 23, the saw-shaped rack 25 is fixed on one side of the limit plate 30 extending out of the elongated slot 29, and the saw-shaped racks 25 are uniformly arranged along the length direction of the limit plate 30. The limiting plate 30 can slide up and down to a certain degree in the limiting plate 30, so that the meshing teeth 26 can be better meshed when moving towards the saw-shaped rack 25, and then the sliding cylinder 12 rotates to drive the limiting plate 30 to move and then drive the sliding plate 23 to slide.

The implementation principle of the fume chamber in the embodiment of the application is as follows: when the exhaust fan 4 is opened, the electromagnetic block 13 is powered on and has magnetism, the magnetic ring 14 can slide towards the direction of the electromagnetic block 13 and is adsorbed on the electromagnetic block 13, at the moment, the spring 171 is compressed, the magnetic ring 14 slides to drive the sliding cylinder 12 to slide towards the direction of the electromagnetic block 13, at the moment, the first contact block 161 and the second contact block 162 are separated from the contact effect, the sliding cylinder 12 can rotate on the outer wall of the convex seat 11, at the moment, the door panel 6 can slide downwards, a certain gap is left between the lower end of the door panel 6 and the cabinet body 1, so that the exhaust fan 4 can suck the gas in the working chamber 2 away, when the door panel 6 is slid upward to open the opening 5 of the cabinet 1, the sliding cylinder 12 is rotated to drive the sliding plate 23 to slide downward in the sliding slot 22, the elastic blocks 24 are thus able to compress the air inside the chute 22 and blow from the blow holes 28 towards the inside of the working chamber 2, thus reducing the escape of air from the inside of the working chamber 2.

The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.

Claims

1. The utility model provides a fume chamber, includes the cabinet body (1), the cabinet body (1) is equipped with working chamber (2), the top of the cabinet body (1) is equipped with suction hood (3), be equipped with exhaust fan (4), its characterized in that in suction hood (3): the improved cabinet is characterized in that one side of the cabinet body (1) is provided with an opening (5), the cabinet body (1) is vertically and slidably connected with a door plate (6) used for covering the opening (5), the working chamber (2) is rotatably connected with two rotating shafts (7) which are parallel to each other, the outer walls of the two ends of each rotating shaft (7) are respectively provided with a driving gear (9), the door plate (6) is provided with a gear belt (8), one side of the cabinet body (1) far away from the door plate (6) is provided with a balancing weight (10), the gear belt (8) is wound around the two driving gears (9) and is connected with the balancing weight (10), the opposite inner wall of the working chamber (2) is provided with a convex seat (11), the rotating shaft (7) is rotatably connected between the two convex seats (11), the side wall of the convex seat (11) is sleeved with a sliding cylinder (12), one end of the convex seat (11, when exhaust fan (4) are opened, electromagnetism piece (13) circular telegram and have magnetism, the one end setting that slide cylinder (12) are close to electromagnetism piece (13) can adsorb in magnetic ring (14) of electromagnetism piece (13), magnetic ring (14) rotate to be connected on the terminal surface of slide cylinder (12), be equipped with limit structure (15) between axis of rotation (7) and slide cylinder (12) and make axis of rotation (7) rotate and can drive slide cylinder (12) synchronous rotation, be equipped with conflict structure (16) between slide cylinder (12) and boss (11) for restriction slide cylinder (12) rotate, work as can drive slide cylinder (12) when electromagnetism piece (13) circular telegram and move to the direction that is close to electromagnetism piece (13), can remove the conflict state of slide cylinder (12) and boss (11).

2. A fumehood according to claim 1 wherein: the one end of a sliding cylinder (12) is extended to the direction of keeping away from boss (11), and the one end of axis of rotation (7) is located the inside of a sliding cylinder (12), limit structure (15) are including locating axis of rotation (7) outer wall and along axis of rotation (7) radial extension's spacing post (151), limit structure (15) are still including offering spacing groove (152) of a sliding cylinder (12) outer wall, the extending direction of spacing groove (152) is on a parallel with the axial direction of a sliding cylinder (12), spacing post (151) extend into in spacing groove (152).

3. A fumehood according to claim 2 wherein: conflict structure (16) are including locating first conflict piece (161) on the one end outer wall of electromagnetism piece (13) is kept away from in convex seat (11), the one end that first conflict piece (161) is close to electromagnetism piece (13) is most advanced structure, leaves the space between the adjacent first conflict piece (161), conflict structure (16) are still including second conflict piece (162) of locating slide cartridge (12) inner wall, the one end that second conflict piece (162) are close to axis of rotation (7) sets up to most advanced structure, when slide cartridge (12) slided to the direction of keeping away from electromagnetism piece (13), second conflict piece (162) can be pegged graft in the clearance between first conflict piece (161), be equipped with driving piece (17) that are used for driving second conflict piece (162) to first conflict piece (161) motion on electromagnetism piece (13).

4. A fumehood according to claim 3 wherein: the electromagnetic block (13) is provided with an installation groove (18) coaxial with the boss (11), the driving piece (17) comprises a spring (171) arranged on the outer wall of the boss (11), one end of the spring (171) is located in the installation groove (18), the other end of the spring (171) is provided with a part extending out of the surface of the electromagnetic block (13), and when the magnetic ring (14) is adsorbed on the electromagnetic block (13), the spring (171) is compressed in the installation groove (18) by the magnetic ring (14).

5. A fumehood according to claim 4 wherein: an annular groove (20) is formed in one end face, close to the electromagnetic block (13), of the sliding cylinder (12), a ring protrusion (19) is arranged at one end of the magnetic ring (14), and the ring protrusion (19) can rotate in the annular groove (20).

6. A fumehood according to claim 4 wherein: the long strip seat (21) is arranged on the opposite side wall in the working cavity (2), a sliding groove (22) is vertically arranged and is formed inside the long strip seat (21), a sliding plate (23) is vertically and slidably connected in the sliding groove (22), an elastic block (24) is arranged at the lower end of the sliding plate (23), the elastic block (24) is abutted to the inner wall of the sliding groove (22), a saw-shaped rack (25) is arranged on one side, close to the sliding cylinder (12), of the sliding plate (23), one side, away from the electromagnetic block (13), of the saw-shaped rack (25) is arranged to be a tip structure, meshing teeth (26) are uniformly arranged on the outer wall of the sliding cylinder (12) along the circumferential direction of the sliding cylinder (12), one end, facing the saw-shaped rack (25), of the meshing teeth (26) is arranged to be the tip structure, when the sliding cylinder (12) slides towards the direction of the electromagnetic block (13), the meshing teeth (26) can be meshed with the saw-, when door plant (6) lid fits opening (5) of the cabinet body (1), the saw-shaped rack (25) and the meshing tooth (26) of the lower extreme lateral wall of slide (23) mesh mutually, the top of the cabinet body (1) sets up inside hollow seat of stepping down (27), the upper end of slide (23) can be pegged graft in seat of stepping down (27), set up the gas hole (28) of slope towards working chamber (2) on the lower extreme lateral wall of rectangular seat (21).

7. A fumehood according to claim 6 wherein: the sliding plate (23) is provided with a long groove (29) penetrating through the surface of the sliding plate (23), a limiting plate (30) is connected in the long groove (29) in a vertical sliding mode, and the saw-shaped rack (25) is arranged on one side, extending out of the long groove (29), of the limiting plate (30).

8. A fumehood according to claim 7 wherein: the cross section of the long groove (29) is of a T-shaped structure.