CN116892606A - Centrifugal ventilator with small running resistance - Google Patents

Abstract

The invention relates to the field of ventilators, in particular to a centrifugal ventilator with small running resistance, which comprises a fixed base, a fan, a servo motor, a transmission belt and a protective shell, wherein the protective shell comprises a fixed shell, a transmission gear, a movable shaft, a movable ring and a tensioning assembly, the fixed shell is fixedly arranged on the fixed base, an alarm is fixedly arranged at the bottom of the fixed shell, the transmission gear is coaxially and rotatably connected with the movable shaft, the diameter of the movable shaft is larger than that of the transmission gear, the movable ring is coaxially and slidably sleeved on the movable shaft, and the tensioning assembly is movably arranged in the fixed shell. The invention ensures that the centrifugal ventilator in the unmanned working environment can quickly resume working after the transmission belt is broken, thereby not affecting the normal working of the integral ventilation and dust removal system, avoiding the damage to personnel, environment and equipment caused by that the transmission belt is not thrown out of the integral equipment when the transmission belt is broken, and improving certain safety.

Description

Centrifugal ventilator with small running resistance

Technical Field

The invention relates to the field of ventilators, in particular to a centrifugal ventilator with small running resistance.

Background

The ventilator is an important device of the ventilation and dust removal system, and is used for conveying air, providing the required air quantity for the system and overcoming the resistance loss generated when the air flows in the system. According to the working principle, there are two types of centrifugal ventilators and axial ventilators, wherein the running resistance of the centrifugal ventilators is small, so that the centrifugal ventilators are mainly used at present, and the centrifugal ventilators can be divided into a belt type, a shaft type and a direct-connection type.

Belt formula centrifugal fan passes through belt pulley cooperation belt and carries out the transmission, have that the performance is adjusted extensively, easy maintenance, the heat dissipation nature number, advantage such as noise low, but current belt formula centrifugal fan will not work when the belt breaks, if discovery in time and be equipped with reserve belt this moment then can very fast make belt formula centrifugal fan resume work, but if can't discover the cracked condition of belt in time, thereby can lead to the unable normal circulation of whole ventilation dust pelletizing system to appear great problem, in order to guarantee simultaneously to resume belt formula centrifugal fan's work in time, still need be equipped with the reserve belt that is used for the change in addition.

Disclosure of Invention

To above-mentioned problem, provide a centrifugal fan that running resistance is little, make through loose axle and expansion ring and store on the epaxial driving belt of loose can remove to the driving gear when the epaxial driving belt of driving breaks, make through tensioning assembly and store on epaxial driving belt of loose can adapt to the gear of driving gear fast and carry out work, send the warning signal through the siren.

For solving prior art problem, provide a centrifugal fan that running resistance is little, including unable adjustment base, the fan, servo motor, driving belt and cage driving belt's protecting sheathing, protecting sheathing includes the fixed shell, the drive gear, the loose axle, loose ring and tensioning assembly, the fixed set up on unable adjustment base, fan and servo motor's transmission shaft all extends to the inside of protecting sheathing and is connected with the drive gear transmission, the fixed siren that is provided with in bottom of fixed shell, the siren sends out when having the object to pile up in the fixed shell bottom, driving gear and the coaxial swivelling joint of loose axle, the loose axle is in driving gear one end of keeping away from servo motor, the cover is equipped with a driving belt on two driving gears, the diameter of loose axle is greater than driving gear's diameter, the coaxial slip cap of loose ring is established on the loose axle, two driving belts are in the same side of loose ring, tensioning assembly activity sets up in the inside of fixed shell, tensioning assembly makes the driving belt that the cover was established on driving gear be in the tight state all the time, when driving gear's driving belt fracture on driving gear, the loose ring promotes driving belt on the loose axle to move to the last driving gear of a driving belt and take place to take place the contact with the transmission assembly and move to the back with the driving belt on the transmission shaft.

Preferably, the fixed shell is including first fixed plate, fly leaf and torsional spring, the fixed one side that is close to servo motor on the fixed shell that the fixed setting that first fixed plate can dismantle, first fixed plate is fixed to be provided with fixed axle bed towards the inside one side of fixed shell, fly leaf and fixed axle bed swivelling joint, the rotation axis of fly leaf is parallel with the line of two drive gear, the fixed setting of torsional spring is between fixed axle bed and fly leaf, the fly leaf contacts with epaxial drive belt of fly leaf, when the drive belt fracture on the drive gear, the fly leaf rotates.

Preferably, tensioning assembly is including movable shell, movable block, first spring and take-up pulley, fixed being provided with first dead lever on the first fixed plate, the axis of first dead lever is parallel with drive gear's axis, movable shell slip cap is established on first dead lever, movable block and movable shell sliding connection, the slip direction of movable block is perpendicular with drive gear's axis, the slip direction of movable block is perpendicular with the line of two drive gears, first spring is fixed to be set up between movable shell and movable block, fixed being provided with on the movable block towards the extension board that extends far away from the movable shell direction, the take-up pulley rotation sets up on the extension board, the extension board can be contacted with drive belt, the axis of take-up pulley is parallel with drive gear's axis.

Preferably, the fixed shell further comprises a fixed gear, the fixed gear is rotatably arranged on one surface, far away from the servo motor, of the first fixed plate, the axis of the fixed gear is parallel to the axis of the transmission gear, a rack which can be meshed with the fixed gear is fixedly arranged on the extension plate, the length direction of the rack is parallel to the sliding direction of the movable block, one end of a steel rope is fixedly arranged on the fixed gear, the other end of the steel rope is fixedly connected with the movable plate, and the movable plate can be pulled to rotate through the steel rope when the fixed gear rotates.

Preferably, the number of the fixed shaft seats is four, two adjacent fixed shaft seats in the four fixed shaft seats are in mirror image distribution by taking the center of the first fixed plate as a middle line, the number of the fixed gears is two, and the two fixed gears are in mirror image distribution by taking the center of the first fixed plate as a middle line.

Preferably, the first fixing plate is fixedly provided with a fixing piece for guiding the steel rope to move, and the fixing shaft seat is provided with a channel for guiding the steel rope to move.

Preferably, the tensioning assembly further comprises a limiting plate, an extension bar extending towards the movable block is fixedly arranged on the limiting plate, a fixing hole for the extension bar to be inserted is formed in the movable block, a first limiting sliding groove in sliding fit with the extension bar is formed in the movable shell, and the length direction of the first limiting sliding groove is parallel to the sliding direction of the movable shell.

Preferably, the fixed shell further comprises a second spring, the first fixed plate is fixedly provided with a second fixed rod, the axis of the second fixed rod is parallel to the axis of the first fixed rod, the limiting plate is provided with a second limiting chute which is in sliding fit with the second fixed rod, the length direction of the second limiting chute is intersected with and not perpendicular to the sliding direction of the movable block, the second spring is sleeved on the second fixed rod, the extension rod is in sliding fit with the fixed hole, and a third spring is fixedly arranged between the extension rod and the sliding block.

Preferably, the first fixing plate is fixedly provided with a flexible fixing buckle, the movable shell is provided with a clamping groove for the fixing buckle to be inserted, the movable block is provided with a third limiting chute which can be in sliding fit with the fixing buckle, and one end of the third limiting chute, far away from the extension plate, is provided with an inclined plane.

Preferably, the fixed shell further comprises a second fixed plate and a fourth spring, the second fixed plate is detachably fixed on one surface, far away from the servo motor, of the fixed shell, the fourth spring is fixedly arranged between the movable ring and the second fixed plate, a third fixed rod in sliding fit with the movable ring is fixedly arranged on the second fixed plate, and the axis of the third fixed rod is parallel to the axis of the movable ring.

Compared with the prior art, the invention has the beneficial effects that:

according to the invention, the function that the transmission belt stored on the movable shaft can move to the transmission gear when the transmission belt on the transmission gear is broken is realized through the movable shaft and the movable ring, the function that the transmission belt stored on the movable shaft can be quickly adapted to the gear of the transmission gear and work is realized through the tensioning assembly, and the function of sending out a reminding signal is realized through the alarm, so that the centrifugal ventilator in an unmanned working environment can quickly resume work after the transmission belt is broken, the normal work of the integral ventilation and dust removal system is not influenced, meanwhile, the transmission belt is prevented from being thrown out to the outside of integral equipment when broken, thereby damaging personnel, environment and equipment, and certain safety is improved.

Drawings

Fig. 1 is a perspective view of a centrifugal fan with a small running resistance.

Fig. 2 is a perspective view of a protective housing in a centrifugal fan with a small running resistance.

Fig. 3 is a schematic perspective sectional view of a protective casing in a centrifugal fan with a small running resistance.

Fig. 4 is an enlarged partial schematic view of fig. 3 a.

Fig. 5 is an enlarged partial schematic view of B in fig. 3.

Fig. 6 is a schematic exploded perspective view of a protective housing in a centrifugal fan with a small running resistance.

Fig. 7 is a schematic exploded perspective view of a protective housing in a centrifugal fan with a small running resistance.

Fig. 8 is a schematic perspective view of the first fixing plate in the protective case.

Fig. 9 is a second perspective view of the first fixing plate in the protective case.

Fig. 10 is a schematic perspective cutaway view of a tensioning assembly in a protective housing.

Fig. 11 is an exploded isometric view of the tension assembly in the protective housing.

The reference numerals in the figures are:

1-fixing a base; 2-a fan; 3-a servo motor; 4-a transmission belt; 5-a protective housing; 51-a fixed shell; 511-a first fixing plate; 5111-fixing the shaft seat; 5112-a first fixation rod; 5113-securing member; 5114-channel; 5115-a second fixation rod; 5116-fixing clasp; 512-movable plate; 513-torsion springs; 514-fixed gear; 515-a second spring; 516-a second fixing plate; 5161-a third securing lever; 517-fourth springs; 52-a transmission gear; 53-a movable shaft; 54-a movable ring; 55-tensioning assembly; 551-movable shell; 5511-a first limit chute; 5512-a clamping groove; 552-active block; 5521-extension plates; 5522-fixing holes; 5523 a third limit chute; 553 a first spring; 554-tensioning wheel; 555-rack; 556-limiting plate; 5561-extension strips; 5562 a second limit chute; 557-third spring.

Detailed Description

The invention will be further described in detail with reference to the drawings and the detailed description below, in order to further understand the features and technical means of the invention and the specific objects and functions achieved.

Referring to fig. 1-5, a centrifugal ventilator with small running resistance comprises a fixed base 1, a blower 2, a servo motor 3, a driving belt 4 and a protective housing 5 covering the driving belt 4, wherein the protective housing 5 comprises a fixed shell 51, a driving gear 52, a movable shaft 53, a movable ring 54 and a tensioning assembly 55, the fixed shell 51 is fixedly arranged on the fixed base 1, the driving shafts of the blower 2 and the servo motor 3 are both extended to the inside of the protective housing 5 and are in transmission connection with the driving gear 52, an alarm is fixedly arranged at the bottom of the fixed shell 51, the alarm gives off an alarm when an object is piled at the bottom of the fixed shell 51, the driving gear 52 and the movable shaft 53 are coaxially and rotatably connected, the movable shaft 53 is positioned at one end of the driving gear 52 far away from the servo motor 3, one driving belt 4 is sleeved on the two driving gears 52, the other driving belt 4 is sleeved on the two movable shafts 53, the diameter of the movable shaft 53 is larger than that of the driving gear 52, the movable ring 54 is coaxially sleeved on the movable shaft 53, the two driving belts 4 are positioned at the same side of the movable ring 54, the tensioning assembly 55 is movably arranged at the same side of the fixed shell 51, the tensioning assembly is movably arranged in the inside the driving gear 52, the tensioning assembly is tightly sleeved on the driving gear 52, and the driving belt 4 is enabled to move to be in the direction of the driving belt 4 and is kept away from the driving belt 52 when the movable belt 4 is in the tensioning assembly, and moves to the driving belt 4 is in the direction of the driving shaft 52, and is in contact with the driving belt 52, and moves to the driving belt 4 is in the direction of the driving belt 52, and moves in the driving belt 4 is in the direction of the driving belt 52.

The servo motor 3 works to enable the transmission gear 52 in transmission connection with the servo motor 3 to rotate, then the fan 2 receives the transmission force output by the servo motor 3 through the cooperation of the two transmission gears 52 and the transmission belt 4 to work, at the moment, the transmission belt 4 on the two transmission gears 52 is always in a tight state under the operation of the tensioning assembly 55, the transmission belt 4 sleeved on the two movable shafts 53 is far away from the transmission gear 52 and does not move at the moment, when the transmission belt 4 on the transmission gear 52 breaks, the tensioning assembly 55 moves away from the servo motor 3, meanwhile, the movable ring 54 moves the transmission belt 4 on the movable shafts 53 towards the direction approaching the transmission gear 52, when the tensioning assembly 55 contacts the transmission belt 4 on the movable shafts 53, the tensioning assembly 55 tightens the transmission belt 4 and moves to the transmission gear 52 along with the transmission belt, the broken transmission gear 52 is stacked at the bottom of the fixed shell 51 at this time, compared with the prior art, the movable shaft 53 and the movable ring 54 of the invention enable the transmission belt 4 stored on the movable shaft 53 to move to the transmission gear 52 when the transmission belt 4 on the transmission gear 52 breaks, enable the transmission belt 4 stored on the movable shaft 53 to quickly adapt to the gear of the transmission gear 52 and work through the tensioning assembly 55, send out a reminding signal through the alarm, thereby ensuring that the centrifugal ventilator in the unmanned working environment can quickly resume work after the transmission belt 4 breaks, thereby not affecting the normal work of the whole ventilation and dust removal system, and avoiding the transmission belt 4 from being thrown out of the whole equipment when broken to cause the damage of personnel, environment and equipment, and improves certain safety.

See fig. 6-9: the fixed shell 51 comprises a first fixed plate 511, a movable plate 512 and a torsion spring 513, wherein the first fixed plate 511 is detachably fixed on the fixed shell 51 and is close to one surface of the servo motor 3, a fixed shaft seat 5111 is fixedly arranged on one surface of the first fixed plate 511 facing the inside of the fixed shell 51, the movable plate 512 is rotatably connected with the fixed shaft seat 5111, a rotating shaft of the movable plate 512 is parallel to a connecting line of two transmission gears 52, the torsion spring 513 is fixedly arranged between the fixed shaft seat 5111 and the movable plate 512, the movable plate 512 is in contact with the transmission belt 4 on the movable shaft 53, and when the transmission belt 4 on the transmission gears 52 is broken, the movable plate 512 rotates.

When the driving belt 4 on the driving gear 52 works normally, the movable plate 512 is kept parallel to the first fixed plate 511 under the operation of the torsion spring 513, the driving belt 4 on the movable shaft 53 cannot move randomly under the clamping of the movable plate 512 and the movable ring 54, and when the driving belt 4 on the driving gear 52 breaks, the movable plate 512 rotates so as not to contact with the driving belt 4 on the movable shaft 53 any more.

See fig. 6-9: the tensioning assembly 55 comprises a movable shell 551, a movable block 552, a first spring 553 and a tensioning wheel 554, wherein a first fixed rod 5112 is fixedly arranged on the first fixed plate 511, the axis of the first fixed rod 5112 is parallel to the axis of the transmission gear 52, the movable shell 551 is slidably sleeved on the first fixed rod 5112, the movable block 552 is slidably connected with the movable shell 551, the sliding direction of the movable block 552 is perpendicular to the axis of the transmission gear 52, the sliding direction of the movable block 552 is perpendicular to the connecting line of the two transmission gears 52, the first spring 553 is fixedly arranged between the movable shell 551 and the movable block 552, an extension plate 5521 extending towards the direction far away from the movable shell 551 is fixedly arranged on the movable block 552, the tensioning wheel 554 is rotatably arranged on the extension plate 5521, the extension plate 5521 can be in contact with the transmission belt 4, and the axis of the tensioning wheel 554 is parallel to the axis of the transmission gear 52.

When the driving belt 4 on the driving gear 52 works normally, the side surface of the driving belt 4 on the driving gear 52 contacts with the extension plate 5521, the tension wheel 554 contacts with the front surface of the driving belt 4 on the driving gear 52, the driving belt 4 on the driving gear 52 is in a tight state, when the driving belt 4 on the driving gear 52 breaks, the movable shell 551 drives the movable block 552 to move towards the direction close to the movable shaft 53, when the side surface of the driving belt 4 on the movable shaft 53 contacts with the extension plate 5521, the movable shell 551 moves along with the driving belt 4 on the movable shaft 53 towards the direction close to the driving gear 52, compared with the prior art, the extension plate 5521 of the invention can contact with the side surface of the driving belt 4, so that the tension assembly 55 can move along with the driving belt 4 on the movable shaft 53.

See fig. 6-9: the fixed shell 51 further comprises a fixed gear 514, the fixed gear 514 is rotatably arranged on one surface, far away from the servo motor 3, of the first fixed plate 511, the axis of the fixed gear 514 is parallel to the axis of the transmission gear 52, a rack 555 capable of being meshed with the fixed gear 514 is fixedly arranged on the extension plate 5521, the length direction of the rack 555 is parallel to the sliding direction of the movable block 552, one end of a steel rope is fixedly arranged on the fixed gear 514, the other end of the steel rope is fixedly connected with the movable plate 512, and the movable plate 512 can be pulled to rotate through the steel rope when the fixed gear 514 rotates.

When the driving belt 4 on the driving gear 52 is broken, the movable block 552 moves towards the direction approaching the center of the first fixed plate 511 under the elasticity of the first spring 553, the rack 555 drives the fixed gear 514 to rotate, the fixed gear 514 pulls the steel rope to rotate at the same time, the movable plate 512 connected to the steel rope rotates, and when the movable plate 512 rotates to be out of contact with the driving belt 4 on the movable shaft 53, the movable ring 54 pushes the driving belt 4 on the movable shaft 53 to move towards the direction approaching the driving gear 52, compared with the prior art, the fixed gear 514, the rack 555 and the steel rope cooperate to limit the rotation time of the movable plate 512, so that the driving belt 4 on the movable shaft 53 can move at the first time after the driving belt 4 on the driving belt is broken.

See fig. 6-9: the number of the fixed shaft seats 5111 is four, two adjacent fixed shaft seats 5111 in the four fixed shaft seats 5111 are in mirror image distribution by taking the center of the first fixed plate 511 as a middle line, the number of the fixed gears 514 is two, and the two fixed gears 514 are in mirror image distribution by taking the center of the first fixed plate 511 as a middle line.

When the driving belt 4 on the driving gear 52 works normally, the four movable plates 512 are contacted with the driving belt 4 on the movable shaft 53, and when the driving belt 4 on the driving gear 52 breaks, the two fixed gears 514 rotate simultaneously and enable the four movable plates 512 to be far away from the driving belt 4 on the movable shaft 53 simultaneously.

See fig. 6-9: the first fixing plate 511 is fixedly provided with a fixing member 5113 for guiding the movement of the steel rope, and the fixing shaft seat 5111 is provided with a channel 5114 for guiding the movement of the steel rope.

The steel rope always moves along one path when moving along with the rotation of the fixed gear 514, and the steel rope sequentially contacts the fixing member 5113 and the channel 5114 when moving, compared with the prior art, the fixing member 5113 and the channel 5114 limit the moving path of the steel rope, so that the four movable plates 512 can simultaneously rotate and the rotation angles are equal.

See fig. 8-11: the tensioning assembly 55 further comprises a limiting plate 556, an extension bar 5561 extending towards the movable block 552 is fixedly arranged on the limiting plate 556, a fixing hole 5522 for the extension bar 5561 to be inserted is formed in the movable block 552, a first limiting chute 5511 in sliding fit with the extension bar 5561 is formed in the movable shell 551, and the length direction of the first limiting chute 5511 is parallel to the sliding direction of the movable shell 551.

When the transmission belt 4 on the transmission gear 52 breaks, the first spring 553 provides elastic force to push the movable block 552 to move towards the center of the first fixed plate 511, the movable block 552 drives the limiting plate 556 to move simultaneously when moving, the limiting plate 556 moves a certain distance and then contacts with the end part of the first limiting chute 5511, at the moment, the movable block 552 and the limiting plate 556 stop moving simultaneously, and compared with the prior art, the limit plate 556, the first limiting chute 5511, the extension bar 5561 and the fixed hole 5522 cooperate to limit the moving distance of the movable block 552, so that the movable block 552 is ensured not to separate from the movable shell 551 under the elastic force of the first spring 553.

See fig. 8-11: the fixed shell 51 further comprises a second spring 515, the first fixed plate 511 is fixedly provided with a second fixed rod 5115, the axis of the second fixed rod 5115 is parallel to the axis of the first fixed rod 5112, the limiting plate 556 is provided with a second limiting chute 5562 in sliding fit with the second fixed rod 5115, the length direction of the second limiting chute 5562 is intersected with and not perpendicular to the sliding direction of the movable block 552, the second spring 515 is sleeved on the second fixed rod 5115, the extension rod is in sliding fit with the fixed hole 5522, and a third spring 557 is fixedly arranged between the extension rod and the sliding block.

When the fixed housing 51 is between the connection lines of the two transmission gears 52 and the transmission belt 4 on the transmission gears 52 works normally, the second spring 515 is in a compressed state, the third spring 557 is in a normal state, when the transmission belt 4 on the transmission gears 52 breaks, the first spring 553 pushes the movable block 552 to move towards the center of the first fixed plate 511, the third spring 557 is compressed, when the transmission belt 4 on the movable shaft 53 starts to move, the second spring 515 is deformed to restore to push the fixed housing 51 to approach the transmission belt 4 on the movable shaft 53, the third spring 557 is deformed to restore, the second fixed rod 5115 and the second limiting sliding groove 5562 cooperate to enable the movable block 552 to shrink into the movable housing 551, and compared with the prior art, when the second spring 515, the third spring 557, the second fixed rod 5115 and the second limiting sliding groove 5562 enable the movable block 552 to shrink into the movable housing 551 to be located outside the tensioning belt 4 on the movable shaft 53 when the movable housing 551 approaches the transmission belt 4 on the movable shaft 53.

See fig. 8-11: the first fixing plate 511 is fixedly provided with a flexible fixing buckle 5116, the movable shell 551 is provided with a clamping groove 5512 for the fixing buckle 5116 to be inserted, the movable block 552 is provided with a third limiting chute 5523 which can be in sliding fit with the fixing buckle 5116, and one end of the third limiting chute 5523, far away from the extension plate 5521, is provided with an inclined plane.

When the movable case 551 contacts with the first fixing plate 511, the fixing buckle 5116 is inserted into the clamping groove 5512, the second spring 515 is in a compressed state, the movable block 552 is far away from the movable case 551 under the pushing of the first spring 553, when the movable block 552 moves a certain distance, the inclined surface of the third limit chute 5523 contacts with the fixing buckle 5116, so that the fixing buckle 5116 is separated from the clamping groove 5512, and the second spring 515 is restored to deform to push the movable case 551 to move.

See fig. 6-7: the fixed housing 51 further includes a second fixed plate 516 and a fourth spring 517, where the second fixed plate 516 is detachably fixed on a surface of the fixed housing 51 far away from the servo motor 3, the fourth spring 517 is fixedly disposed between the movable ring 54 and the second fixed plate 516, and a third fixed rod 5161 slidably engaged with the movable ring 54 is fixedly disposed on the second fixed plate 516, and an axis of the third fixed rod 5161 is parallel to an axis of the movable ring 54.

When the movable plate 512 rotates to a position not contacted with the transmission belt 4 on the movable shaft 53, the fourth spring 517 pushes the movable ring 54 to move, so that the transmission belt 4 on the movable shaft 53 moves onto the transmission gear 52, the second fixed plate 516 is removed when maintenance is performed, the movable ring 54 is separated from the fixed shell 51, and then a new transmission belt 4 is placed on the transmission belt, and the second fixed plate 516 is installed.

The foregoing examples merely illustrate one or more embodiments of the invention, which are described in greater detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims (10)

1. The centrifugal ventilator with small running resistance comprises a fixed base (1), a fan (2), a servo motor (3), a transmission belt (4) and a protective shell (5) covering the transmission belt (4), and is characterized in that the protective shell (5) comprises a fixed shell (51), a transmission gear (52), a movable shaft (53), a movable ring (54) and a tensioning assembly (55);

the fixed shell (51) is fixedly arranged on the fixed base (1), the transmission shafts of the fan (2) and the servo motor (3) extend to the inside of the protective shell (5) and are in transmission connection with the transmission gear (52), an alarm is fixedly arranged at the bottom of the fixed shell (51), and when objects are accumulated at the bottom of the fixed shell (51), the alarm gives an alarm;

the transmission gears (52) are coaxially and rotatably connected with the movable shafts (53), the movable shafts (53) are positioned at one ends of the transmission gears (52) far away from the servo motor (3), one transmission belt (4) is sleeved on the two transmission gears (52), the other transmission belt (4) is sleeved on the two movable shafts (53), and the diameter of each movable shaft (53) is larger than that of each transmission gear (52);

the movable ring (54) is coaxially sleeved on the movable shaft (53) in a sliding way, and the two transmission belts (4) are positioned on the same side of the movable ring (54);

the tensioning assembly (55) is movably arranged in the fixed shell (51), the tensioning assembly (55) enables the transmission belt (4) sleeved on the transmission gear (52) to be in a tightening state all the time, when the transmission belt (4) on the transmission gear (52) is broken, the movable ring (54) pushes the transmission belt (4) on the movable shaft (53) to move to the transmission gear (52), and meanwhile the tensioning assembly (55) moves in a direction away from the servo motor (3) and moves along with the transmission belt (4) after contacting with the transmission belt (4) on the transmission shaft.

2. A centrifugal fan with a small running resistance according to claim 1, characterized in that the stationary casing (51) comprises a first stationary plate (511), a movable plate (512) and a torsion spring (513);

the utility model discloses a fixed setting that first fixed plate (511) can dismantle is close to one side of servo motor (3) on fixed shell (51), fixed axle bed (5111) that is provided with on the one side of first fixed plate (511) towards fixed shell (51) inside, fly leaf (512) and fixed axle bed (5111) swivelling joint, the rotation axis of fly leaf (512) is parallel with the line of two drive gear (52), torsional spring (513) are fixed to be set up between fixed axle bed (5111) and fly leaf (512), fly leaf (512) contact with driving belt (4) on the loose axle (53), when driving belt (4) on driving gear (52) fracture, fly leaf (512) rotate.

3. A centrifugal fan with low running resistance according to claim 2, characterized in that the tensioning assembly (55) comprises a movable housing (551), a movable block (552), a first spring (553) and a tensioning wheel (554);

the utility model provides a fixed first dead lever (5112) that is provided with on first fixed plate (511), the axis of first dead lever (5112) is parallel with the axis of drive gear (52), movable shell (551) slip cap is established on first dead lever (5112), movable block (552) and movable shell (551) sliding connection, the slip direction of movable block (552) is perpendicular with the axis of drive gear (52), the slip direction of movable block (552) is perpendicular with the line of two drive gears (52), first spring (553) are fixed to be set up between movable shell (551) and movable block (552), fixed extension board (5521) that the orientation was kept away from movable shell (551) direction on movable block (552) are provided with, extension board (5521) rotation sets up on extension board (5521), extension board (5521) can be in contact with driving belt (4), the axis of idler (554) is parallel with the axis of drive gear (52).

4. A centrifugal fan with a low running resistance according to claim 3, characterized in that the stationary casing (51) further comprises a stationary gear (514);

the fixed gear (514) is rotationally arranged on one surface, far away from the servo motor (3), of the first fixed plate (511), the axis of the fixed gear (514) is parallel to the axis of the transmission gear (52), a rack (555) which can be meshed with the fixed gear (514) is fixedly arranged on the extension plate (5521), the length direction of the rack (555) is parallel to the sliding direction of the movable block (552), one end of a steel rope is fixedly arranged on the fixed gear (514), the other end of the steel rope is fixedly connected with the movable plate (512), and the fixed gear (514) can rotate by pulling the movable plate (512) through the steel rope when rotating.

5. The centrifugal fan with small running resistance according to claim 4, wherein the number of the fixing shaft seats (5111) is four, two adjacent fixing shaft seats (5111) in the four fixing shaft seats (5111) are in mirror image distribution by taking the center of the first fixing plate (511) as a middle line, the number of the fixing gears (514) is two, and the two fixing gears (514) are in mirror image distribution by taking the center of the first fixing plate (511) as a middle line.

6. The centrifugal fan with small running resistance according to claim 5, wherein a fixing piece (5113) for guiding the movement of the steel rope is fixedly arranged on the first fixing plate (511), and a channel (5114) for guiding the movement of the steel rope is formed on the fixing shaft seat (5111).

7. A centrifugal fan with a low running resistance according to claim 6, characterized in that the tensioning assembly (55) further comprises a limiting plate (556);

an extension strip (5561) extending towards the movable block (552) is fixedly arranged on the limiting plate (556), a fixing hole (5522) for the extension strip (5561) to be inserted is formed in the movable block (552), a first limiting sliding groove (5511) in sliding fit with the extension strip (5561) is formed in the movable shell (551), and the length direction of the first limiting sliding groove (5511) is parallel to the sliding direction of the movable shell (551).

8. A centrifugal fan with a low running resistance according to claim 7, characterized in that the stationary casing (51) further comprises a second spring (515);

the first fixing plate (511) is fixedly provided with a second fixing rod (5115), the axis of the second fixing rod (5115) is parallel to the axis of the first fixing rod (5112), the limiting plate (556) is provided with a second limiting chute (5562) which is in sliding fit with the second fixing rod (5115), the length direction of the second limiting chute (5562) is intersected with the sliding direction of the movable block (552) and is not perpendicular, the second spring (515) is sleeved on the second fixing rod (5115), the extending rod is in sliding fit with the fixing hole (5522), and a third spring (557) is fixedly arranged between the extending rod and the sliding block.

9. The centrifugal ventilator with small running resistance according to claim 8, wherein a flexible fixing buckle (5116) is fixedly arranged on the first fixing plate (511), a clamping groove (5512) for inserting the fixing buckle (5116) is formed in the movable shell (551), a third limiting sliding groove (5523) which can be in sliding fit with the fixing buckle (5116) is formed in the movable block (552), and an inclined surface is arranged at one end, far away from the extending plate (5521), of the third limiting sliding groove (5523).

10. A centrifugal fan with a low running resistance according to claim 9, wherein the stationary casing (51) further comprises a second stationary plate (516) and a fourth spring (517);

the second fixing plate (516) can be detached and fixedly arranged on one surface, far away from the servo motor (3), of the fixing shell (51), the fourth spring (517) is fixedly arranged between the movable ring (54) and the second fixing plate (516), the second fixing plate (516) is fixedly provided with a third fixing rod (5161) which is in sliding fit with the movable ring (54), and the axis of the third fixing rod (5161) is parallel to the axis of the movable ring (54).