CN111404344B

CN111404344B - Explosion-proof three-phase asynchronous motor suitable for mine working condition

Info

Publication number: CN111404344B
Application number: CN202010308072.8A
Authority: CN
Inventors: 吴岩
Original assignee: Jiangsu Xi'anda Explosive Proof Co ltd
Current assignee: Jiangsu Xi'anda Explosive Proof Co ltd
Priority date: 2019-10-09
Filing date: 2019-10-09
Publication date: 2022-07-08
Anticipated expiration: 2039-10-09
Also published as: CN110620485B; CN110620485A; CN111404344A; CN111404343B; CN111404343A

Abstract

The invention discloses an explosion-proof three-phase asynchronous motor suitable for mine working conditions, which comprises a main shaft assembly, a rotor, a stator, a machine shell, a front end cover and a tail end cover, wherein a front cover bearing is arranged at the position where the main shaft assembly penetrates through the front end cover, a junction box is arranged on the outer surface of the machine shell, an external power supply is connected into the motor through a power line, a sealing gasket is arranged on the contact surface of the front end cover and the machine shell, a sealing gasket is arranged on the contact surface of the tail end cover and the machine shell, a rotating shaft seal is arranged at the center of the front end cover and at one side of the front cover bearing, which faces the outside, and positive pressure safety gas is introduced into the machine shell. The wall shell of the machine shell is provided with a through hole which is connected with the inner space of the machine shell and the inner space of the junction box, and positive pressure safety gas introduced into the machine shell is introduced through a power line. The power cord includes cable and air hose, sets up the terminal in the terminal box, and the terminal is connected with the stator, and on cable junction was to the terminal, in the air hose stretched into the terminal box, the air on the earth's surface was gone into through outside fan drum to the one end that the terminal box was kept away from to the air hose.

Description

Explosion-proof three-phase asynchronous motor suitable for mine working condition

Technical Field

The invention relates to the field of motors, in particular to an explosion-proof three-phase asynchronous motor suitable for mine working conditions.

Background

Electrical appliances in mines have very high requirements on safety, and motors used in mines must have explosion-proof properties.

In the prior art, explosion-proof is mostly carried out through an explosion-proof mode, namely: even if an explosion occurs at some high-temperature point, the explosion is said to be explosion-proof as long as the explosion does not spread and does not cause the explosion of the ambient gas around the motor due to the explosion at a tiny point.

However, the components of the gas in the mine are always in the explosive characteristic, as long as the third factor of explosion, namely the temperature reaches the explosion point, explosion is caused, and the sealing additional structure is often too bulky for the explosion-proof characteristic of the motor, so that the complexity and the manufacturing cost of the motor are greatly increased, and the weight is greatly increased.

Disclosure of Invention

The invention aims to provide an explosion-proof three-phase asynchronous motor suitable for mine working conditions so as to solve the problems in the prior art.

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

the utility model provides an explosion-proof three-phase asynchronous machine suitable for mine operating mode, including main shaft assembly, a rotor, a stator, a housing, front end housing and tail-end cover, main shaft assembly passes front end housing department and is equipped with the protecgulum bearing, the casing outward appearance sets up the terminal box, external power passes through the power cord and inserts the motor, be equipped with sealed the pad on the contact surface of front end housing and casing, set up sealed the pad on the contact surface of tail-end cover and casing, front end housing central authorities, one side that the front end bearing was towards the external world is equipped with the rotation axis and seals, introduce malleation safety gas in the casing.

The explosion-proof motor is a key factor for preventing explosion, three conditions are required for explosion, the concentration of combustible gas (substance) components reaches a certain range, an oxidant (usually oxygen in air) exists, the temperature reaches an ignition point, the environment of the explosion-proof motor is already the occasion with higher explosive concentration, and the first two conditions are acquiescent, so the explosion-proof motor starts from the aspect of blocking high-temperature points and explosion gases.

The invention sets a sealing gasket between the end cover and the casing, so that the explosive gas of the surrounding environment enters into the motor through the end cover contact surface, thereby the explosion can not occur, the contact surface between the end cover and the casing belongs to static sealing, the sealing can be made very reliable, the motor shaft and the end cover are a rotating part and a static part, so a gap is inevitably existed, if the explosive gas of the surrounding environment enters into the motor along the motor shaft, the explosion is also possible, therefore, the invention sets a rotating shaft seal at the position where the motor shaft extends out of the end cover, seals the leakage gap again, prevents the explosive from leaking into the motor, the rotating shaft seal can be in the form of lip seal, and when the lip seal is set, the invention is best to be close to the end bearing and set a lubricating oil cavity for lubricating.

Although the rotary shaft seal can be matched with the static seal of the end cover and the machine shell to play a role of two-way sealing, if the interior of the motor has a thermal expansion effect due to a large amount of heat, and if the interior of the motor is a closed space, there is a pressure difference between the internal pressure and the ambient environment, although the leakage direction is from outside to inside when the pressure in the motor is high, the pressure in the motor cooled down after the shutdown is low, explosive gas in the surrounding environment may diffuse into the motor, so that the explosion happens when the machine is started next time, and the invention introduces positive pressure safety gas from the outside to fill the machine shell, therefore, the pressure of the gas in the motor is kept higher than the surrounding environment where the motor is used at any time, so that diffusion type leakage cannot occur.

Furthermore, a through hole is formed in a wall shell of the machine shell, the through hole is connected with the inner space of the machine shell and the inner space of the junction box, and positive-pressure safety gas introduced into the machine shell is introduced through a power line.

Because it is used in the mine, if the atmosphere without explosive material is used as the safety gas, the source is the air at the surface, and the gas under the mine cannot be used as the safety gas. The invention relates to a power line, in particular to a power line, which is characterized in that air is taken from the ground surface as safety gas, a pipeline is required to guide the air to a casing, most of motors need to take electric power from the ground surface, and due to the particularity of a mine, a diesel engine is used for generating electricity for supplying power in the mine, the safety is difficult to guarantee, most of the electric power enters the mine through power transmission from the ground surface through cables, so that the safety gas of the motors is arranged in the same cable along with the cables, the wiring complexity can be reduced, the space occupation is reduced, only one cable is required to be fixed all the way, and certainly, a plurality of motors are arranged in the mine.

Further, the power cord includes cable and air hose, sets up the terminal in the terminal box, and the terminal is connected with the stator, and on cable connection to terminal, in the air hose stretched into the terminal box, the air on the earth's surface was blown through outside fan to the one end that the terminal box was kept away from to the air hose.

The security gas introduced into the enclosure from the power cord passes from within the junction box into a hole in the enclosure.

Further, main shaft assembly includes the hollow shaft, and hollow shaft central authorities are equipped with the unthreaded hole that the whole axle of axial run through, and the unthreaded hole both ends carry out the shutoff, are equipped with a plurality of air distribution hole on the hollow shaft, and air distribution hole radially extends, connects hollow shaft surface and central unthreaded hole, on the axial position of hollow shaft: the front cover bearing faces to one side of the atmosphere and two sides of the rotor, and at least one air distribution hole is formed in each of the three positions.

Because the junction box is in contact with the housing only at one location, positive pressure air entering the motor from the junction box cannot be guaranteed to be well distributed to all corners in the motor, especially the rotary sealing surfaces of the spindle and the end covers. The motor shaft is made into a hollow shaft, a plurality of air distribution holes are arranged on the surface of the hollow shaft, pressure air enters the air distribution holes corresponding to the air inlet position on the wall surface of the shell in the axial direction, then positive pressure air is axially distributed and diffused along a central hole in the hollow shaft and is sprayed out of the hollow shaft at certain positions, the positions of the air distribution holes are required to be arranged at two sides of the sealing contact surface of all main shafts and the rotating shaft, when the motor has no other better surface heat dissipation conditions and fins and a tail fan are required to be arranged, the number of the air distribution holes is at least 4, and when the fan is arranged, a fan shell is preferably arranged at the same time, so that the danger of mechanical injury is prevented.

Further, the spindle assembly further comprises a gas distribution pipe, a pressure reduction hole plate and a compensation pipe, the gas distribution pipe is inserted into the hollow shaft, an annular groove is formed in the outer surface of the gas distribution pipe, a through hole is formed in the bottom of the annular groove and connected with the gas distribution pipe, the annular groove is located at one end of the gas distribution hole, the length and the size of the adjacent two gas distribution pipes are compensated through the compensation pipe, the pressure reduction hole plate is padded between the gas distribution pipe and the compensation pipe, and the gas distribution pipes located at two ends of the hollow shaft are compressed through a plugging piece.

If only one unthreaded hole is arranged in the hollow shaft, the pressure distribution in the hollow shaft is almost equal, and because a plurality of air distribution holes are directed to the external environment of the use position of the motor, the flow can be generated, the pressure in the shell needs to be higher in order to fully ensure the explosion-proof performance of the motor, the flow is larger when the pressure difference is larger, the flow discharged from the air distribution holes to the use position of the motor is more, the air flow sent into a mine from the ground surface is more, the explosion-proof performance of the motor is not influenced, but the increase of the flow not only increases the fan load for supplying air at the ground surface, but also the flow is larger, so that a power line needs to be thicker, and the wiring is influenced; therefore, when the supply pressure of the safety gas is higher, the flow of the positive pressure gas in the motor discharged from the gas distribution hole needs to be reduced by a certain means, and the invention adopts the mode that the gas distribution pipe, the pressure reduction pore plate and the compensating pipe are added into the hollow shaft, so that the pressure distribution of the gas in the hollow shaft is changed, the gas can be subjected to primary pressure reduction through the primary pressure reduction pore plate, but the pressure higher than the ambient environment needs to be ensured.

Furthermore, the main shaft assembly further comprises an end pad and a plug, wherein C-shaped center holes are formed in two ends of the hollow shaft, and the plug is screwed into the center holes and tightly presses the end pad on the end portion of the air distribution pipe. The invention designs the center holes at the two ends of the hollow shaft into C-shaped, is convenient to screw in the part to tightly support the end part of the gas distribution pipe after being provided with threads, and is provided with end gaskets towards the outer ends of the gas distribution pipes at the two ends for sealing the end part, thereby preventing the gas in the gas distribution pipe from leaking out from the two ends of the hollow shaft.

As optimization, the air pipe wraps the cable, the metal braided hose is used on the outer surface of the power line, and the explosion-proof flexible joint is used at the joint of the power line connected to the junction box. After the air pipe wraps the cable, the heat productivity of the cable can be taken away by air, even if some parts of the cable possibly generate heat seriously when current passes due to large resistance caused by manufacturing and the like, if the parts are directly contacted with the surroundings, the parts can be an explosion point, and the air pipe wraps the cable to play an isolation role, so that the cable and explosive gas in a mine are isolated. The explosion-proof flexible joint is a common explosion-proof cable joint and is convenient to connect.

Preferably, the junction box comprises a box body and a box cover, a gasket is arranged between the box body and the box cover, and two sides of the gasket are glued. The junction box is internally provided with a metal contact, and the space in the junction box is communicated with the interior of the machine shell, so that a sealing cover surface for sealing the junction box by static seal is arranged. The sealing performance of the glued gasket is fully guaranteed.

As optimization, the circumferential angles of the air distribution holes on the hollow shaft are staggered. The circumferential distribution of the air distribution holes is more uniform.

Compared with the prior art, the invention has the beneficial effects that: according to the invention, the sealing gasket is arranged on the contact surface of the end cover and the shell to form static seal, and the rotating shaft seal is arranged at the position where the main shaft penetrates through the end cover, so that the space in the motor is isolated from external explosive gas, and the explosion condition cannot be achieved; positive pressure gas is filled into the motor, comes from the ground surface and is non-explosive gas, and further prevents the diffusion and leakage of the environmental gas at the use position of the motor into the motor; the positive pressure gas is distributed in position and pressure in the motor through the hollow shaft, the internal pressure is high, the outward pressure is slightly lower but higher than the ambient pressure, and therefore the explosion-proof isolation performance is guaranteed, and the situation that the power line is too thick due to the fact that too much positive pressure gas is discharged from the gas distribution hole is avoided.

Drawings

In order that the present invention may be more readily and clearly understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings.

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic view of a portion of the junction box of the present invention;

FIG. 3 is a schematic structural view of the spindle assembly of the present invention;

FIG. 4 is view A of FIG. 3;

FIG. 5 is view B of FIG. 3;

FIG. 6 is a schematic diagram of the pressure distribution in the enclosure and at the gas distribution holes of the present invention.

In the figure: 1-main shaft assembly, 2-rotor, 3-stator, 4-machine shell, 5-front end cover, 6-front cover bearing, 7-tail end cover, 8-tail cover bearing, 9-fan shell, 10-fan, 11-fin, 12-junction box, 13-power line, 14-binding post, 15-cable, 16-air tube, 17-gasket, 1001-hollow shaft, 1002-central hole, 1003-air distribution hole, 1004-air distribution tube, 10041-annular groove, 1005-decompression orifice plate, 1006-compensation tube, 1007-end pad and 1008-plug.

Detailed Description

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.

As shown in fig. 1, an explosion-proof three-phase asynchronous motor suitable for mine working conditions, including main shaft assembly 1, rotor 2, stator 3, casing 4, front end housing 5 and tail end cover 7, main shaft assembly 1 passes front end housing 5 department and is equipped with protecgulum bearing 6, casing 4 outward appearance sets up terminal box 12, external power passes through power cord 13 and inserts the motor, be equipped with sealed the pad on the contact surface of front end housing 5 and casing 4, set up sealed the pad on the contact surface of tail end cover 7 and casing 4, front end housing 5 central authorities, one side that front end housing bearing 6 is towards the external world is equipped with the rotation axis and seals, introduce malleation safety gas in the casing 4.

The sealing gasket is arranged between the end cover and the shell 4, so that explosive gas in the surrounding environment enters the motor through the contact surface of the end cover, explosion cannot occur, the contact surface between the end cover and the shell 4 belongs to static sealing, the sealing arrangement can be very reliable, a gap is inevitably formed between the motor shaft and the end cover because one rotating part and the other rotating part are static parts, and explosion is very likely to occur if the explosive gas in the surrounding environment enters the motor along the motor shaft, so that the rotating shaft sealing is arranged at the position of the motor shaft extending out of the end cover, the leakage gap is sealed again, explosive is prevented from leaking into the motor, the rotating shaft sealing can be in the form of lip sealing and the like, and when the lip sealing is arranged, a lubricating oil cavity is preferably arranged close to the end bearing and used for lubricating.

Although the rotating shaft seal can be matched with the static seal of the end cover and the machine shell 4 to play a role of two-way sealing, the rotating shaft seal can also play a role of two-way sealing, if the interior of the motor has a thermal expansion effect due to a large amount of heat, and if the interior of the motor is a closed space, there is a pressure difference between the internal pressure and the ambient environment, although the leakage direction is from outside to inside when the pressure in the motor is high, the pressure in the motor cooled down after the shutdown is low, explosive gas in the surrounding environment may diffuse into the motor, so that explosion occurs when the machine is started next time, and the invention introduces positive pressure safety gas from the outside to fill the machine shell 4, therefore, the pressure of the gas in the motor is kept higher than the surrounding environment where the motor is used at any time, so that diffusion type leakage cannot occur.

As shown in fig. 2, the wall of the casing 4 is provided with a through hole, the through hole connects the inside of the casing 4 with the space in the junction box 12, and the positive pressure safety gas introduced into the casing 4 is introduced through the power line 13.

Because it is used in the mine, if the atmosphere without explosive material is used as the safety gas, the source is the air at the surface, and the gas under the mine cannot be used as the safety gas. When air is taken from the ground surface as safety gas, pipelines are needed to guide the air to the shell, most of motors need to take power from the ground surface, and due to the particularity of mines, when a diesel engine is used for generating electricity for supplying power in a mine, the safety is difficult to guarantee, most of the electricity is transmitted from the earth surface through a cable and enters the mine, therefore, the safety gas of the motor is arranged in the same cable along with the cable, which can reduce the wiring complexity and the space occupation, only one cable needs to be fixed, of course, a plurality of motors are arranged in a mine, the power line 13 is actually a structural design of an electric bus in the mine, the bus is arranged in a 'one-cable double-core' mode, one motor is branched into a plurality of motors, and each motor is not required to be directly connected to a power supply on the ground, so that the power line of each motor is too long.

As shown in fig. 2, the power line 13 includes a cable 15 and an air tube 16, a terminal 14 is disposed in the terminal box 12, the terminal 14 is connected to the stator 3, the cable 15 is connected to the terminal 14, the air tube 16 extends into the terminal box 12, and one end of the air tube 16 away from the terminal box 12 is blown into the air on the ground surface by an external blower.

The safety gas introduced into the cabinet 4 from the power supply line 13 passes through a hole leading from the inside of the terminal box 12 to the cabinet 4.

As shown in fig. 1, the main shaft assembly 1 includes a hollow shaft 1001, the center of the hollow shaft 1001 is provided with a light hole axially penetrating through the whole shaft, two ends of the light hole are blocked, the hollow shaft 1001 is provided with a plurality of air distribution holes 1003, the air distribution holes 1003 radially extend, the outer surface of the hollow shaft 1001 and the central light hole are connected, and the axial position of the hollow shaft 1001 is: the front cover bearing 6 faces one side of the atmosphere and two sides of the rotor 2, and at least one air distribution hole 1003 is formed in each of the three positions.

Because terminal block 12 is in contact with housing 4 at only one location, positive pressure air entering the motor from terminal block 12 cannot be guaranteed to be well distributed to the corners of the motor, especially the rotary sealing surfaces of the spindle and end caps. The invention makes the motor shaft become the hollow shaft 1001, and set up several air distribution holes 1003 on the surface of the hollow shaft 1001, the axial, air distribution hole 1003 corresponding to air intake place of the wall of the chassis 4 enters the pressurized air at first, then the positive pressure air distributes and spreads axially along the central hole in the hollow shaft 1003, and squirt outside the hollow shaft 1003 in some positions, the position to set up air distribution hole 1003 is, both sides of the sealed contact surface of all basic shafts and rotating shafts, when the motor does not have other better exterior heat dissipation conditions but also needs to set up fin 11 and tail fan 10, the quantity of air distribution hole 1003 is 4 at least, it is shown in fig. 1, 5 black point separately, when setting up the fan 10, preferably set up the fan shell 9 together, prevent causing the danger of mechanical injury.

As shown in fig. 3 to 5, the spindle assembly 1 further includes a gas distribution pipe 1004, a pressure reducing hole plate 1005 and a compensation pipe 1006, the gas distribution pipe 1004 is inserted into the hollow shaft 1001, a ring groove 10041 is formed on an outer surface of the gas distribution pipe 1004, a through hole is formed from a bottom of the ring groove 10041 to the gas distribution pipe 1004 for connection, the ring groove 10041 is located at one end of the gas distribution hole 1003, length and size are compensated between two adjacent gas distribution pipes 1004 through the compensation pipe 1006, the pressure reducing hole plate 1005 is padded between the gas distribution pipe 1004 and the compensation pipe 1006, and the gas distribution pipes 1004 at two ends in the hollow shaft 1001 are compressed through a plugging member.

If only one unthreaded hole is arranged in the hollow shaft 1001, the pressure distribution in the hollow shaft 1001 is almost equal, and because a plurality of air distribution holes 1003 point to the external environment where the motor is used, flow can be generated, the pressure in the shell 4 needs to be higher in order to fully guarantee the explosion-proof performance of the motor, the flow is larger when the pressure difference is larger, the flow discharged from the air distribution holes 1003 to the use of the motor is more, the air flow sent to a mine from the ground surface is more, although the explosion-proof performance of the motor is not influenced, the increase of the flow not only increases the fan load for supplying air at the ground surface, but also has larger flow, so that the power line 13 needs to be thicker and the wiring is influenced; therefore, when the supply pressure of the safety gas is high, the flow rate of the positive pressure gas in the motor discharged from the gas distribution hole 1003 needs to be reduced by a certain means, and the invention uses a mode that the gas distribution pipe 1004, the pressure reduction pore plate 1005 and the compensating pipe 1006 are added into the hollow shaft 1001, so that the pressure distribution of the gas in the hollow shaft 1001 is changed, as shown in fig. 6, the gas is subjected to pressure reduction once through the pressure reduction pore plate 1005, but the pressure higher than the surrounding environment needs to be ensured.

As shown in fig. 4, the spindle assembly 1 further includes an end pad 1007 and a plug 1008, wherein a C-shaped central hole 1002 is formed at each end of the hollow shaft 1001, and the plug 1008 is screwed into the central hole 1002 to press the end pad 1007 against the end of the air distribution pipe 1004. The invention designs the center holes at the two ends of the hollow shaft 1001 into C shape, after the center holes are provided with threads, the hollow shaft 1001 can be conveniently screwed in to tightly abut against the end part of the gas distribution pipe 1004, and the gas distribution pipe 1004 at the two ends is provided with end pads 1007 towards the outer ends for end sealing, thereby preventing the gas in the gas distribution pipe 1004 from leaking out from the two ends of the hollow shaft 1001.

The air tube 16 wraps the cable 15, the outer surface of the power line 13 uses a metal braided hose, and the joint of the power line 13 connected to the junction box 12 uses an explosion-proof flexible joint. After the air pipe 16 wraps the cable 15, the heat generated by the cable can be carried away by air, even if some parts of the cable 15 may generate heat seriously when current passes due to high resistance caused by manufacturing and the like, if the parts are in direct contact with the surrounding, the parts may be an explosion point, and the air pipe 16 wraps the cable 15 to play a role in isolating the cable 15 from explosive gas in a mine. The explosion-proof flexible joint is a common explosion-proof cable joint and is convenient to connect.

As shown in fig. 2, the junction box 12 includes a box body and a box cover, a gasket 17 is provided between the box body and the box cover, and both sides of the gasket 17 are glued. There are metal contacts in terminal box 12 and the space in terminal box 12 is in communication with the interior of cabinet 4, so that a static seal is provided to seal the cover side of terminal box 12. The sealing performance of the glued gasket 17 is fully guaranteed.

The air distribution holes 1003 are offset from each other in circumferential angle on the hollow shaft 1001. The circumferential distribution of the gas distribution holes 1003 is more uniform.

The use process of the device is as follows: positive pressure air is introduced into the air pipe 16 from the earth surface by using a fan, enters the machine shell 4 along the power line 13, is full of the space where the stator and the rotor are located, then enters the hollow shaft 1001 from the air distribution hole 1003 on the surface of the hollow shaft 1001 in the motor, and then is subjected to pressure reduction through the air distribution pipe 1004 and the pressure reduction pore plate 1005 to form air areas at a plurality of positions of the shaft surface of the spindle assembly 1 respectively, so that explosive gas in the environment of the use place of the motor is driven away, and the explosive gas is far away from a high-temperature point.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Claims

1. The utility model provides an explosion-proof three-phase asynchronous machine suitable for mine operating mode, includes main shaft assembly (1), rotor (2), stator (3), casing (4), front end housing (5) and tail end lid (7), and main shaft assembly (1) passes front end housing (5) department and is equipped with protecgulum bearing (6), and casing (4) outward appearance sets up terminal box (12), and external power passes through power cord (13) and inserts the motor, its characterized in that: a sealing gasket is arranged on the contact surface of the front end cover (5) and the shell (4), a sealing gasket is arranged on the contact surface of the tail end cover (7) and the shell (4), a rotating shaft seal is arranged at the center of the front end cover (5) and on one side of the front cover bearing (6) facing the outside, and positive pressure safety gas is introduced into the shell (4);

the wall shell of the machine shell (4) is provided with a through hole, the through hole is connected with the interior of the machine shell (4) and the space in the junction box (12), and positive-pressure safety gas introduced into the machine shell (4) is introduced through a power line (13);

the power line (13) comprises a cable (15) and an air pipe (16), a binding post (14) is arranged in the junction box (12), the binding post (14) is connected with the stator (3), the cable (15) is connected to the binding post (14), the air pipe (16) extends into the junction box (12), and one end, far away from the junction box (12), of the air pipe (16) is blown into air on the ground surface through an external fan;

main shaft assembly (1) includes hollow shaft (1001), hollow shaft (1001) central authorities are equipped with the unthreaded hole that the whole axle of axial run through, and the unthreaded hole both ends are sealed, are equipped with a plurality of air distribution hole (1003) on hollow shaft (1001), air distribution hole (1003) radially extends, connects hollow shaft (1001) surface and central unthreaded hole, on the axial position of hollow shaft (1001): one side of the front cover bearing (6) facing the atmosphere and two sides of the rotor (2) in the motor are respectively provided with at least one air distribution hole (1003);

the spindle assembly (1) further comprises air distribution pipes (1004), a pressure reducing pore plate (1005) and a compensating pipe (1006), wherein the air distribution pipes (1004) are inserted into the hollow shaft (1001), annular grooves (10041) are formed in the outer surfaces of the air distribution pipes (1004), through holes are formed in the bottoms of the annular grooves (10041) and the air distribution pipes (1004) and connected with each other, the annular grooves (10041) are located at one ends of the air distribution holes (1003), the length and the size of the adjacent air distribution pipes (1004) are compensated through the compensating pipe (1006), the pressure reducing pore plate (1005) is filled between the air distribution pipes (1004) and the compensating pipe (1006), and the air distribution pipes (1004) located at two ends of the hollow shaft (1001) are compressed through a sealing part;

the air pipe (16) wraps the cable (15), a metal braided hose is used on the outer surface of the power line (13), and an explosion-proof flexible joint is used at the joint of the power line (13) connected to the junction box (12); the circumferential angles of the air distribution holes (1003) on the hollow shaft (1001) are staggered.