Electric roller

Abstract

The utility model provides an electric roller. The electric roller comprises a roller body, a planetary gear speed reducer and an explosion-proof permanent magnet motor, the planetary gear speed reducer is located on one side of the flame-proof permanent magnet motor, an input part of a rotating part of the speed reducer is connected with the motor rotor part, and the inner end of a fixed part of the speed reducer is fixedly connected to a motor shell; the first end of the roller body is fixedly connected to the output part of the rotating part of the speed reducer, and the second end is connected with a roller end cover; the outer end of the speed reducer fixing part is rotationally connected to the first fixing base, and the outer end of the fixing shaft frame is rotationally connected to the second fixing base. According to the utility model, the roller body is in transmission connection with the flame-proof permanent magnet motor through the planetary gear speed reducer, the roller body does not serve as a part of the flame-proof permanent magnet motor any more, flame-proof safety certification is easy to meet, and only the motor needs to be subjected to flame-proof design; the flame-proof permanent magnet motor outputs lifting torque through the planetary gear speed reducer, the torque of the motor can be relatively reduced, the size of the motor can be correspondingly reduced, and therefore the power density of the whole machine is increased.

Description

Technical Field

[0001] The utility model relates to the technical field of electric rollers, in particular to electric rollers. Background Art

[0002] Regarding the built-in electric rollers for driving belt conveyors, there are mainly the following two product structures on the market.

[0003] One is the oil-immersed electric roller, whose structure is a common asynchronous motor + reducer + roller body. The roller body and other supporting parts form a closed structure, and the inside is filled with cooling oil. It began to be used in China in the 1940s. However, due to the contradiction between the size of the roller body and the size of the motor, the power of this kind of roller can currently be achieved below 100kW and can be used on small-power belt conveyors. And when this kind of product is used, the inside is filled with cooling oil. When disassembling, it is necessary to first drain the internal cooling oil, and the disassembly site is dirty, and the maintenance is very cumbersome.

[0004] The other is the emerging outer-rotor permanent magnet direct-drive electric roller in recent two years. The roller body is the shell for installing permanent magnets, that is, the inside of the roller is the stator and rotor structure. It is the ultimate mode of belt conveyor transmission and has been maturely applied on the market. The power of the existing outer-rotor permanent magnet direct-drive electric roller can reach 710kW in an explosion-proof environment. However, according to national regulations, for outer-rotor permanent magnet direct-drive electric rollers with a power above 315kW, they need to meet the explosion-proof safety certification and must have one certificate for each machine. And affected by the motor power density, the greater the power, the larger the required roller diameter and bandwidth, which will be inconsistent with the relatively small roller diameter and bandwidth in actual application requirements. The greater the power, the more prominent this contradiction. Summary of the Invention

[0005] Aiming at the technical problems existing in the prior art, the utility model proposes an electric roller, which can increase the power density of the electric roller and easily meet the explosion-proof safety certification.

[0006] To achieve the purpose of solving the above technical problems, the utility model adopts the following technical solutions: an electric roller, comprising:

[0007] A roller body, a planetary gear reducer and an explosion-proof permanent magnet motor arranged coaxially, and the planetary gear reducer and the explosion-proof permanent magnet motor are arranged inside the roller body;

[0008] The explosion-proof permanent magnet motor includes a machine shell, a rotor part and a stator part located outside the rotor part. The rotor part and the stator part are located inside the machine shell. The machine shell includes a front end cover, a machine shell body and a rear end cover, and a fixed shaft frame is externally connected to the rear end cover;

[0009] The planetary gear reducer is located on one side of the explosion-proof permanent magnet motor, and it includes a rotating part and a fixed part. The input part of the rotating part is connected to the rotor part, and the inner end of the fixed part is fixedly connected to the housing;

[0010] The first end of the drum body is fixedly connected to the output part of the rotating part, and the second end is connected with a drum end cover;

[0011] The outer end of the fixed part passes through the output part of the rotating part and is connected to the first fixed seat, and the outer end of the fixed part is rotationally matched with the output part of the rotating part; the fixed shaft bracket passes through the drum end cover and is connected to the second fixed seat, and the drum end cover is rotationally matched with the fixed shaft bracket.

[0012] The planetary gear reducer includes a first planetary assembly and a second planetary assembly;

[0013] The first planetary assembly includes a first-stage sun gear, first-stage planetary gears, a first-stage planetary carrier, and a first-stage internal gear ring; the first-stage sun gear is the input part of the rotating part; the first-stage planetary gears are respectively meshed with the first-stage sun gear and the first-stage internal gear ring; the first-stage planetary carrier is integrally connected with the first-stage planetary gears; the first-stage internal gear ring is fixedly connected with the housing;

[0014] The second planetary assembly includes a second-stage sun gear, second-stage planetary gears, a second-stage planetary carrier, and a second-stage internal gear ring; the second-stage sun gear is arranged on the first-stage planetary carrier; the second-stage planetary gears are respectively meshed with the second-stage sun gear and the second-stage internal gear ring; the second-stage planetary carrier is integrally connected with the first-stage internal gear ring, the second-stage internal gear ring is the output part of the rotating part, and the outer end of the second-stage planetary carrier passes through the second-stage internal gear ring and is connected to the first fixed seat.

[0015] The first-stage internal gear ring is in close contact and fixedly connected with the front end face of the housing, the first-stage internal gear ring is located between the second-stage internal gear ring and the front end face of the housing, and the second-stage planetary carrier extends into the internal space surrounded by the second-stage internal gear ring.

[0016] A first central through hole is formed on the end plate of the second-stage internal gear ring. The second-stage planetary carrier has a first extension section extending axially outward along the drum body. The first extension section passes through the first central through hole and a bearing is arranged between the first extension section and the first central through hole.

[0017] An annular positioning flange is formed on the outer wall of the second-stage internal gear ring. The outer wall of the second-stage internal gear ring is in close contact with the inner wall of the drum body, and the first end face of the drum body abuts against the positioning flange.

[0018] A second center through portion is formed on the end plate of the primary inner gear ring, and the primary sun gear has a second extension section extending axially along the drum body toward the side where the rotor part is located, and the second extension section passes through the second center through portion and is key-connected to the rotor part.

[0019] A third central through-portion is formed on the drum end cover, the fixed shaft frame passes through the third central through-portion and a bearing is arranged between the fixed shaft frame and the third central through-portion.

[0020] A through wire hole is formed on the fixed shaft frame, one end of the wire hole is connected to the internal space of the motor, and the other end is connected to the internal space of the junction box.

[0021] The second fixing seat is formed with a cylindrical mounting portion which is inserted and matched with the fixing shaft frame and has two ends through it. The junction box is arranged on one end of the cylindrical mounting portion which is away from the flameproof permanent magnet motor.

[0022] The outer surface of the drum body is coated with a coating layer.

[0023] Compared with the prior art, the utility model has the following advantages and positive effects:

[0024] 1. In the utility model electric drum, the drum body and the flameproof permanent magnet motor are connected through a planetary gear reducer. The drum body is no longer a part of the flameproof permanent magnet motor. Therefore, the connection between the drum body and the reducer and the connection between the drum body and the drum end cover do not need to be flameproof. The bearing surface of the drum body is no longer a flameproof surface, so that the utility model electric drum can easily meet the flameproof safety certification. It only needs to be flameproof designed for the internal flameproof permanent magnet motor.

[0025] 2. The explosion-proof permanent magnet motor can increase the torque through the output of the planetary gear reducer, which can relatively reduce the torque of the motor itself. The size of the motor is directly proportional to its torque, so the size of the motor can be reduced accordingly, making the whole machine more compact and effectively increasing the power density of the whole machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A three-dimensional diagram of the electric drum in the embodiment of the utility model;

[0027] Figure 2 This is an exploded view of the electric drum in the embodiment of the utility model;

[0028] Figure 3 It is a schematic cross-sectional structural diagram of the electric drum in the embodiment of the utility model.

[0029] Reference numerals:

[0030] 100, drum body;

[0031] 200, Planetary gear speed reducer; 210, Rotating part; 211, First-stage sun gear; 2111, Second extension section; 212, First-stage planet gear; 213, First-stage planet carrier; 214, Second-stage sun gear; 215, Second-stage planet gear; 216, Second-stage internal gear ring; 2161, First central through hole; 2162, Positioning flange; 217, First bearing; 218, Second bearing; 220, Fixed part; 221, First-stage internal gear ring; 2211, Second central through hole; 222, Second-stage planet carrier; 2221, First extension section

[0032] 300, Flameproof permanent magnet motor; 310, Motor housing; 311, Front end cover; 312, Motor housing body; 313, Rear end cover; 320, Rotor part; 330, Stator part; 340, Fixed shaft bracket; 341, Wire passing hole

[0033] 400, Coating layer

[0034] 500, Drum end cover; 510, Third central through hole

[0035] 600, First fixing seat

[0036] 700, Second fixing seat; 710, Cylindrical mounting part

[0037] 800, Third bearing

[0038] 900, Junction box Detailed implementation manners

[0039] The technical solutions of the present utility model will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners

[0040] Refer to Figures 1 to 3 , in some embodiments of the present utility model, an electric drum includes a drum body 100, a planetary gear speed reducer 200 and a flameproof permanent magnet motor 300. The planetary gear speed reducer 200 and the flameproof permanent magnet motor 300 are arranged inside the drum body 100, and the drum body 100, the planetary gear speed reducer 200 and the flameproof permanent magnet motor 300 are coaxially arranged

[0041] The outer surface of the drum body 100 is coated with a coating layer 400 to increase the friction force and make the power output more stable

[0042] The coating layer 400 can be a rubber coating layer, or a rubber plate coating layer with ceramic chips, a polyurethane coating layer, etc., and no specific limitation is made here

[0043] The flameproof permanent magnet motor 300 includes a casing 310, a rotor part 320 and a stator part 330. The rotor part 320 and the stator part 330 are located inside the casing 310, the stator part 330 is sleeved on the outer periphery of the rotor part 320, and the casing 310 is sleeved on the outer periphery of the stator part 330; the casing 310 includes a front end cover 311, a cylindrical casing body 312 and a rear end cover 313, and the two ends of the rotor shaft are rotatably connected to the front end cover 311 and the rear end cover 313 respectively, and the rear end cover 313 is connected to a fixed shaft frame 340, that is, the fixed shaft frame 340 is located outside the casing 310.

[0044] The planetary gear reducer 200 is located on one side of the flameproof permanent magnet motor 300, specifically on the side where the front end cover 311 is located, and includes a rotating part 210 and a fixed part 220. The input part of the rotating part 210 (specifically located on the inner end of the reducer, i.e., the end adjacent to the flameproof permanent magnet motor 300) is connected to the rotor part 320, and the output part of the rotating part 210 is located at the outer end of the reducer (i.e., the end away from the flameproof permanent magnet motor 300); the inner end of the fixed part 220 (i.e., the end adjacent to the flameproof permanent magnet motor 300) is fixedly connected to the housing 310 of the flameproof permanent magnet motor 300.

[0045] The first end of the drum body 100 is fixedly connected to the output portion of the rotating part 210 , and the second end is connected to the drum end cover 500 .

[0046] The outer end of the fixed part 220 (i.e., the end opposite to the flameproof permanent magnet motor 300) passes through the output part of the rotating part 210 and is connected to the first fixed seat 600. The outer end of the fixed part 220 is rotatably matched with the output part of the rotating part 210. The fixed shaft frame 340 passes through the roller end cover 500 and is connected to the second fixed seat 700. The roller end cover 500 is rotatably matched with the fixed shaft frame 340. The first fixed seat 600 and the second fixed seat 700 are the supporting parts of the entire electric roller.

[0047] In the electric drum in the embodiment of the utility model, the drum body 100 and the flameproof permanent magnet motor 300 are connected through the planetary gear reducer 200, and the drum body 100 is no longer a part of the flameproof permanent magnet motor 300. The connection between the drum body 100 and the reducer and the connection between the drum body 100 and the drum end cover 500 do not need to be flameproof, and the stress-bearing surface of the drum body 100 is no longer a flameproof surface, so that the electric drum of the utility model can easily meet the flameproof safety certification, and only the internal flameproof permanent magnet motor 300 needs to be flameproof.

[0048] In addition, the explosion-proof permanent magnet motor 300 can increase the torque through the planetary gear reducer 200, which can relatively reduce the torque of the motor itself. Since the volume of the motor is directly proportional to its torque, the volume of the motor can be reduced accordingly, making the whole machine more compact and effectively increasing the power density of the whole machine.

[0049] In some embodiments of the present utility model, the planetary gear reducer 200 is a two-stage planetary gear reducer, including a first planetary assembly and a second planetary assembly.

[0050] The first planetary assembly includes a first-stage sun gear 211, first-stage planetary gears 212, a first-stage planetary carrier 213, and a first-stage internal gear ring 221; the first-stage sun gear 211 is the input part of the rotating part 210; the first-stage planetary gears 212 are located between the first-stage sun gear 211 and the first-stage internal gear ring 221, and the first-stage planetary gears 212 are respectively meshed with the first-stage sun gear 211 and the first-stage internal gear ring 221; the first-stage planetary carrier 213 is integrally connected with the first-stage planetary gears 212; the first-stage internal gear ring 221 is fixedly connected to the machine housing 310;

[0051] The second planetary assembly includes a second-stage sun gear 214, second-stage planetary gears 215, a second-stage planetary carrier 222, and a second-stage internal gear ring 216; the second-stage sun gear 214 is arranged on the first-stage planetary carrier 213; the second-stage planetary gears 215 are located between the second-stage sun gear 214 and the second-stage internal gear ring 216, and the second-stage planetary gears 215 are respectively meshed with the second-stage sun gear 214 and the second-stage internal gear ring 216; the second-stage planetary carrier 222 is integrally connected with the first-stage internal gear ring 221, the second-stage internal gear ring 216 is the output part of the rotating part 210, and the outer end of the second-stage planetary carrier 222 passes through the second-stage internal gear ring 216 and is connected to the first fixing seat 600.

[0052] Among them, the first-stage sun gear 211, the first-stage planetary gears 212, the first-stage planetary carrier 213, the second-stage sun gear 214, the second-stage planetary gears 215, and the second-stage internal gear ring 216 are the rotating part 210 of the planetary gear reducer 200, the first-stage sun gear 211 is the input part of the rotating part 210, and the second-stage internal gear ring 216 is the output part of the rotating part 210; the first-stage internal gear ring 221 and the second-stage planetary carrier 222 are the fixed part 220 of the planetary gear reducer 200.

[0053] The explosion-proof permanent magnet motor 300 rotates, driving the first-stage sun gear 211 to rotate, and then driving the first-stage planetary gears 212 and the first-stage planetary carrier 213 to rotate. The first-stage planetary carrier 213 drives the second-stage sun gear 214 to rotate, the second-stage sun gear 214 drives the second-stage planetary gears 215 to rotate, and then drives the second-stage internal gear ring 216 to rotate. The second-stage internal gear ring 216 is fixedly connected to the first end of the drum body 100, so the second-stage internal gear ring 216 drives the drum body 100 to rotate, realizing that the explosion-proof permanent magnet motor 300 drives the electric drum to rotate through the planetary gear reducer 200.

[0054] The planetary gear reducer 200 adopting the above two-stage planetary gear reducer 200 has a compact structure, which is beneficial to further reducing the overall volume of the machine and increasing the overall power density.

[0055] In some embodiments of the present utility model, as Figure 3 shown, the first-stage internal gear ring 221 is fixedly connected in contact with the front end face of the housing 310. The first-stage internal gear ring 221 is located between the second-stage internal gear ring 216 and the front end face of the housing 310. The second-stage planet carrier 222 extends into the internal space enclosed by the second-stage internal gear ring 216, so that the axial dimension of the planetary gear reducer 200 can be reduced, making the structure of the reducer more compact.

[0056] Regarding the rotational fit between the second-stage internal gear ring 216 and the outer end of the fixed part 220, specifically, as Figure 3 shown, the second-stage internal gear ring 216 is a cylindrical structure with an end plate at one end. A first central through portion 2161 is formed on the end plate. The second-stage planet carrier 222 has a first extension section 2221 extending axially outward along the drum body 100. The first extension section 2221 passes through the first central through portion 2161, and a first bearing 217 is provided between the first extension section 2221 and the first central through portion 2161. That is, the first extension section 2221 serves as the outer end of the fixed part 220, and the rotational fit connection is realized by providing the first bearing 217 between it and the first central through portion 2161 of the second-stage internal gear ring 216.

[0057] In some embodiments of the present utility model, an annular positioning flange 2162 is formed on the outer wall of the second-stage internal gear ring 216. The outer wall of the second-stage internal gear ring 216 is in contact with the inner wall of the drum body 100, and the first end face of the drum body 100 abuts against the positioning flange 2162.

[0058] The positioning flange 2162 can play a positioning role in the installation of the planetary gear reducer 200 relative to the drum body 100. When it is inserted into the drum body 100 from the first end of the drum body 100 until the positioning flange 2162 abuts against the first end face of the drum body 100, the reducer is installed in place, and then it is fixedly connected to the first end face of the drum body 100 through a plurality of screws arranged at intervals along the circumferential direction of the positioning flange 2162. The contact between the outer wall of the second-stage internal gear ring 216 and the inner wall of the drum body 100 also plays a guiding and positioning role in the installation of the planetary gear reducer 200 relative to the drum body 100, improving the installation accuracy and installation efficiency.

[0059] Regarding the connection between the first-stage sun gear 211 and the rotor part 320 of the explosion-proof permanent magnet motor 300, specifically, as Figure 3 shown, a second central through portion 2211 is formed on the end plate of the first-stage internal gear ring 221. The first-stage sun gear 211 has a second extension section 2111 extending axially toward the side where the rotor part 320 is located along the drum body 100. The second extension section 2111 passes through the second central through portion 2211 and is key-connected to the rotor part 320. A second bearing 218 is provided between the second extension section 2111 and the second central through portion 2211.

[0060] Correspondingly, the teeth of the first-stage sun gear 211 extend into the internal space surrounded by the first-stage inner gear ring 221 and the second-stage planet carrier 222 , and the first-stage planet gear 212 , the first-stage planet carrier 213 and the second-stage sun gear 214 are also located in the internal space surrounded by the first-stage inner gear ring 221 and the second-stage planet carrier 222 .

[0061] Of course, the second extension section 2111 of the first-stage sun gear 211 and the rotor part 320 may also be connected in other ways, such as interference connection or screw connection, etc., and no specific limitation is made here.

[0062] Regarding the rotation connection between the drum end cover 500 and the fixed shaft frame 340, specifically, the same Figure 3 As shown, a third central through-portion 510 is formed on the drum end cover 500 , the fixed shaft frame 340 passes through the third central through-portion 510 , and a third bearing 800 is arranged between the fixed shaft frame 340 and the third central through-portion 510 .

[0063] In order to facilitate the connection and power-on of the flameproof permanent magnet motor 300 inside the drum, in some embodiments of the utility model, a through wire hole 341 is formed on the fixed shaft frame 340, one end of the wire hole 341 is connected to the internal space of the motor, and the other end is connected to the internal space of the terminal box 900. The lead wire of the flameproof permanent magnet motor 300 inside the drum is led outward through the wire hole 341 of the fixed shaft frame 340 to connect the external terminal box 900 to realize power-on. After the motor is powered on, the internal rotor part 320 and the stator part 330 undergo electromagnetic exchange, and the rotor rotates, and the rated speed of the drum is reached through the planetary gear reducer 200. The secondary gear ring of the planetary gear reducer 200 outputs energy for the output part of the rotating part 210.

[0064] Furthermore, a cylindrical mounting portion 710 is formed on the second fixing seat 700, which is inserted and matched with the fixed shaft frame 340 and has two ends through it. The terminal box 900 is arranged on one end of the cylindrical mounting portion 710, and this end is away from the side where the flameproof permanent magnet motor 300 is located. In this way, the lead wires of the flameproof permanent magnet motor 300 inside the drum can be smoothly connected to the terminal box 900 through the wire holes 341 of the fixed shaft frame 340, and the lead wire length is reduced; and the terminal box 900 is externally placed, does not occupy the radial space inside the drum, and does not affect the internal structure layout of the drum.

[0065] For the cooling of the electric roller in the embodiments of the present utility model, a water cooling system can be specifically adopted. Specifically, a water inlet and a water outlet are provided on the end face of the first extension section 2221 of the secondary planet carrier 222, and cooling water channels are arranged inside the secondary planet carrier 222 and the primary internal gear ring 221. A water channel is correspondingly arranged inside the end face of the machine housing 310 that is in contact with the primary internal gear ring 221, and a spiral water channel is arranged inside the circumferential side wall of the machine housing 310. After the cooling water cools the inside of the electric roller through the internal cooling water channel of the water inlet, the secondary planet carrier 222, the internal cooling water channel of the primary internal gear ring 221, and the internal spiral water channel of the machine housing 310, it is finally led outwards from the water outlet.

[0066] The water cooling system is connected to the water channels through the shaft end of the planetary gear reducer 200 and the end face where the reducer contacts the motor housing 310, without occupying any internal radial space, so that the internal structural space can be more fully utilized.

[0067] The above embodiments are only used to illustrate the technical solutions of the present utility model, rather than to limit them; although the present utility model has been described in detail with reference to the foregoing embodiments, for those of ordinary skill in the art, it is still possible to modify the technical solutions described in the foregoing embodiments, or to equivalently replace some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions required to be protected by the present utility model.

Claims

1. An electric drum, characterized in that: include: A coaxially arranged drum body, a planetary gear reducer and a flameproof permanent magnet motor, wherein the planetary gear reducer and the flameproof permanent magnet motor are arranged inside the drum body; The flameproof permanent magnet motor comprises a casing, a rotor part and a stator part located outside the rotor part, the rotor part and the stator part are located inside the casing, the casing comprises a front cover, a casing body and a rear cover, and the rear cover is externally connected to a fixed shaft frame; The planetary gear reducer is located on one side of the flameproof permanent magnet motor, and includes a rotating part and a fixed part, the input part of the rotating part is connected to the rotor part, and the inner end of the fixed part is fixedly connected to the housing; The first end of the drum body is fixedly connected to the output portion of the rotating part, and the second end is connected to the drum end cover; The outer end of the fixed part passes through the output part of the rotating part and is connected to the first fixed seat, and the outer end of the fixed part is rotatably matched with the output part of the rotating part; the fixed shaft frame passes through the roller end cover and is connected to the second fixed seat, and the roller end cover is rotatably matched with the fixed shaft frame.

2. The electric drum according to claim 1, characterized in that: The planetary gear reducer includes a first planetary assembly and a second planetary assembly; The first planetary assembly comprises a primary sun gear, a primary planetary gear, a primary planetary carrier and a primary inner gear ring; the primary sun gear is the input part of the rotating part; the primary planetary gear is meshed with the primary sun gear and the primary inner gear ring respectively; the primary planetary carrier is connected with the primary planetary gear as a whole; the primary inner gear ring is fixedly connected with the casing; The second planetary assembly includes a secondary sun gear, a secondary planetary gear, a secondary planet carrier and a secondary inner gear ring; The secondary sun gear is formed on the primary planet carrier; the secondary planet gears are respectively meshed with the secondary sun gear and the secondary inner gear ring; The secondary planet carrier is connected to the primary inner gear ring as a whole, the secondary inner gear ring is the output part of the rotating part, and the outer end of the secondary planet carrier passes through the secondary inner gear ring and is connected to the first fixed seat.

3. The electric drum according to claim 2, characterized in that: The primary internal gear ring is fitted and fixedly connected to the front end surface of the casing, the primary internal gear ring is located between the secondary internal gear ring and the front end surface of the casing, and the secondary planet carrier extends into the internal space surrounded by the secondary internal gear ring.

4. The electric drum according to claim 2, characterized in that: A first central through-portion is formed on the end plate of the secondary inner gear ring, and the secondary planetary carrier has a first extension section extending outwardly along the axial direction of the drum body. The first extension section passes through the first central through-portion and a bearing is arranged between the first central through-portion.

5. The electric drum according to claim 4, characterized in that: An annular positioning flange is formed on the outer wall of the secondary inner gear ring, the outer wall of the secondary inner gear ring is in contact with the inner wall of the drum body, and the first end surface of the drum body abuts against the positioning flange.

6. The electric drum according to claim 2, characterized in that: A second center through portion is formed on the end plate of the primary internal gear ring, and the primary sun gear has a second extension section extending axially along the drum body toward the side where the rotor part is located, and the second extension section passes through the second center through portion and is key-connected to the rotor part.

7. The electric drum according to claim 1, characterized in that: A third central through-portion is formed on the drum end cover, the fixed shaft frame passes through the third central through-portion and a bearing is arranged between the fixed shaft frame and the third central through-portion.

8. The electric drum according to claim 7, characterized in that: A through wire hole is formed on the fixed shaft frame, one end of the wire hole is connected to the internal space of the motor, and the other end is connected to the internal space of the junction box.

9. The electric drum according to claim 8, characterized in that: The second fixing seat is formed with a cylindrical mounting portion which is inserted and matched with the fixing shaft frame and has two ends through it. The junction box is arranged on one end of the cylindrical mounting portion which is away from the flameproof permanent magnet motor.

10. The electric drum according to claim 1, characterized in that: The outer surface of the drum body is coated with a coating layer.

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