A straight-through screw pump

Abstract

The present invention discloses a straight-through screw pump, which belongs to the field of liquid variable displacement machinery with a rotary piston or a swing piston; the straight-through screw pump has an axially through medium flow channel, and when used for medium transportation, the medium flows along the axial direction of the screw pump. The straight-through screw pump includes: a stator, a rotor, a flow barrel, a universal joint, a transmission assembly and a motor; the flow barrel is rotatably arranged, the output end of the motor and the flow barrel are connected through the transmission assembly, the motor drives the flow barrel to rotate through the transmission assembly, and a universal joint that rotates with the flow barrel is arranged in the flow barrel; the stator is arranged at one end of the flow barrel, and the rotor is helically meshed in the stator, one end of the rotor is connected to the universal joint, and the other end is freely placed in the stator; the inlet and outlet of the screw pump of the present invention are on the same axis, and compared with the traditional single screw pump, the length of the pump body is greatly reduced, and the applicable scenes are wider.

Description

Technical Field

[0001] The invention relates to the field of liquid variable displacement machinery of a rotary piston or a swing piston, and in particular to a straight-through screw pump. Background Art

[0002] Screw pumps are rotary pumps that rely on the volume change and movement of the meshing space formed by the pump body and the screw to transport liquid or increase its pressure. Screw pumps are divided into single screw pumps, double screw pumps and three screw pumps according to the number of screws. Its working principle is that when the motor drives the pump shaft to rotate, the screw rotates around its own axis on the one hand, and rolls along the inner surface of the bushing on the other hand, thus forming a sealed chamber of the pump. For each rotation of the screw, the liquid in the sealed chamber is pushed forward by one pitch. With the continuous rotation of the screw, the liquid is spirally pressed from one sealed chamber to another, and finally squeezed out of the pump body. Screw pumps have the advantages of simple structure, safe and reliable operation, easy use and maintenance, and continuous and uniform liquid discharge, so they are widely used in the market.

[0003] Among them, the single screw pump has a series of advantages such as strong adaptability to the medium, stable flow, small pressure pulsation, and high self-priming ability. It is widely used in environmental protection, shipbuilding industry, petroleum industry, medicine, daily chemicals, brewing industry, construction industry, mining industry, chemical industry, printing, papermaking industry and other industries. In these application fields, sometimes due to installation space limitations, in order to meet the needs of on-site use, the installation position of the single screw pump is limited. The traditional single screw pump is driven by a motor, coupling, transmission shaft, universal joint, etc. that is directly connected to the rotor, and a suction chamber is required to be set up to transport the medium vertically in an L shape, resulting in a lengthy structure and a large number of components, which is greatly restricted by the installation space. The Chinese utility model patent with application number 2016203504137 discloses a U-shaped transmission structure of a single screw pump, the Chinese utility model patent with application number 202322747594X discloses a screw pump device, and the attachment mentioned in the Chinese utility model patent with application number 2023230117517 Figure 3The existing belt-type reduction pumps all adopt a U-shaped layout structure, which objectively reduces the length of the single-screw pump and solves the problem of limited installation space to a certain extent. However, since the transmission direction is limited by the drive device, it is still an L-shaped vertical transmission. Therefore, a suction chamber must be added between the rotor drive structure and the stator (bushing). The addition of the suction chamber is bound to increase the total length of the pump body. Chinese utility model patent with application number 2019206104549 discloses a novel coalbed methane direct-drive motor submersible device, which essentially also adopts an L-shaped medium conveying method, and the entire device has the same disadvantage of being too long as a traditional screw pump; Chinese utility model patent with application number 2018207367674 discloses an externally driven single-screw pump, which eliminates the suction chamber of a traditional screw pump and the universal joint required for a traditional rotor transmission, and the overall structural length of the pump body is greatly shortened. However, the two ends of the rotor are fixedly connected to two rotating connecting pieces respectively, and the rotor is driven to rotate by the rotation of the stator. The volume change and movement speed of the meshing space formed by the rotor and the stator are relatively slow, and the two even rotate at the same speed, affecting the medium conveying efficiency. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] The technical problem to be solved by the present invention is to solve the problems of the existing screw pump having a long structure, a limited installation environment and inconvenient use.

[0006] (II) Technical solution

[0007] In order to solve the above technical problems, the present invention provides a straight-through screw pump, which has an axially through medium flow channel, and when used for medium transportation, the medium flows along the axial direction of the screw pump; the straight-through screw pump includes: a stator, a rotor, a flow barrel, a universal joint, a transmission assembly and a motor; the flow barrel is rotatably arranged, the output end of the motor and the flow barrel are connected through the transmission assembly, the motor drives the flow barrel to rotate through the transmission assembly, and a universal joint that rotates with the flow barrel is arranged in the flow barrel; the stator is arranged at one end of the flow barrel, and the rotor is helically meshed in the stator, one end of the rotor is connected to the universal joint, and the other end is freely placed in the stator. A spiral groove is arranged in the stator, and a third flow channel is arranged in the flow barrel, the spiral groove is connected to the third flow channel, and the medium flows axially along the third flow channel and the spiral groove.

[0008] Furthermore, the design also includes a bearing seat and a base, two bearing seats are installed on the base, a rotating bearing is arranged in the bearing seat, and the two ends of the flow barrel are respectively rotatably connected to the bearing seats.

[0009] Furthermore, the present design also includes a pull rod, which is arranged between the two bearing seats, and the pull rods are respectively arranged at the four corners of the bearing seat, and the connection between the pull rod and the bearing seat is locked by two nuts.

[0010] Furthermore, the present design also includes a first rotating seat and a second rotating seat, which are respectively rotatably arranged in bearing seats at both ends of the flow barrel, and the two ends of the flow barrel are respectively connected to the first rotating seat and the second rotating seat, and the first rotating seat and the second rotating seat are respectively provided with a first flow channel and a second flow channel, and the first flow channel, the second flow channel, the third flow channel and the spiral groove are connected, and the medium flows axially along the first flow channel, the second flow channel, the third flow channel and the spiral groove.

[0011] Furthermore, in the present design, the first rotating seat is installed on a bearing seat at one end of the flow barrel away from the stator, and the universal joint is installed in the middle of the first rotating seat.

[0012] Furthermore, the present design also includes a mounting seat and a feed body. The mounting seat is mounted on a bearing seat at one end of the flow barrel close to the stator, and the feed body is mounted on a bearing seat at one end of the flow barrel away from the stator. One end of the stator is connected to the mounting seat, and the other end is supported on the base. The fourth flow channel and the fifth flow channel are respectively provided on the mounting seat and the feed body, and the first flow channel, the second flow channel, the third flow channel, the fourth flow channel, the fifth flow channel and the spiral through groove are connected.

[0013] Furthermore, the present design also includes a connecting sleeve and a mechanical seal. A connecting sleeve and a mechanical seal are respectively arranged between the mounting seat and the second rotating seat, and between the feed body and the first rotating seat. A mechanical seal is arranged outside the connecting sleeve.

[0014] Furthermore, the universal joint described in the present design includes a universal swing shaft and a connecting head connected to both ends of the universal swing shaft, the connecting head is connected to the universal swing shaft by a pin, the two ends of the universal swing shaft can swing in different directions along the connection, and the two ends of the universal swing shaft are respectively connected to the first rotating seat and the rotor through the connecting head.

[0015] Furthermore, the transmission assembly of the present design is a belt drive or a chain drive, and a discharge body is provided at one end of the stator away from the flow barrel, and a sixth flow channel is provided on the discharge body to connect the spiral groove of the stator with the outside world.

[0016] Furthermore, the transmission assembly described in the present design is a belt drive, including a large pulley, a small pulley and a transmission belt connecting the two, the large pulley is arranged on the outer wall of the flow barrel, and the small pulley is arranged at the output end of the motor.

[0017] (III) Beneficial effects

[0018] The above technical solution of the present invention has the following advantages:

[0019] The present invention arranges the flow channel of the screw pump into a straight-through structure, and the inlet and outlet of the screw pump are on the same axis. Compared with the L-shaped vertical conveying of the traditional screw pump, the arrangement of the traditional transmission shaft, reducer, coupling and other structures is reduced, the length of the pump body is greatly shortened, and the flow barrel is driven to rotate through the transmission component, thereby driving the universal joint and the rotor to rotate to transport the medium, and the conveying efficiency is stable and reliable.

[0020] The invention simplifies the transmission structure, improves the transmission efficiency, has a simple structure, is not easy to damage, and reduces the manufacturing cost. In addition, the components and volume of the screw pump transmission device are reduced during use, the volume of the equipment is reduced, and the adaptability of the equipment is improved. It is particularly suitable for field operations with small and limited ground space. The equipment runs more smoothly, is not easy to be damaged, the medium transmission efficiency is higher, and the service life of the equipment is extended.

[0021] In addition to the technical problems solved by the present invention, the technical features of the technical solutions constituted by the present invention, and the advantages brought about by the technical features of these technical solutions described above, other technical features of the present invention and the advantages brought about by these technical features will be further explained in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a schematic diagram of the axonometric view of the present invention.

[0024] Figure 2 It is a schematic cross-sectional view of the present invention.

[0025] Figure 3 It is a schematic top view of the present invention.

[0026] Figure 4 It is a schematic side view of the present invention.

[0027] In the figure: 1. stator; 2. rotor; 3. flow barrel; 4. universal joint; 5. motor; 6. spiral groove; 7. third flow channel; 8. bearing seat; 9. base; 10. rotating bearing; 11. pull rod; 12. first rotating seat; 13. second rotating seat; 14. first flow channel; 15. second flow channel; 16. mounting seat; 17. feed body; 18. fourth flow channel; 19. fifth flow channel; 20. connecting sleeve; 21. mechanical seal; 22. discharge body; 23. sixth flow channel; 24. large pulley; 25. small pulley; 26. transmission belt. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] Example 1: Figure 1-Figure 4 As shown, a straight-through screw pump has an axially through medium flow channel. When used for medium transportation, the medium flows along the axial direction of the screw pump, eliminating the setting of the traditional transmission shaft of the traditional screw pump, and reducing the overall structural length of the screw pump. The straight-through screw pump includes: a stator 1, a rotor 2, a flow barrel 3, a universal joint 4, a transmission assembly and a motor 5; the flow barrel 3 is rotatably arranged, that is, the flow barrel 3 can rotate, the output end of the motor 5 and the flow barrel 3 are connected through the transmission assembly, and the motor 5 drives the flow barrel 3 to rotate through the transmission assembly, and the flow barrel 3 is provided with a universal joint 4 that can rotate with the flow barrel 3. The stator 1 is arranged at one end of the flow barrel 3, and the rotor 2 is spirally meshed in the stator 1. One end of the rotor 2 is connected to the universal joint 4, and the other end is freely placed in the stator 1. The flow barrel 3 rotates to drive the universal joint 4 to rotate, and the universal joint 4 rotates to drive the stator 1 to rotate and swing, thereby realizing the transportation of the medium. The stator 1 is provided with a spiral groove 6 for cooperating with the screw rotor 2, the flow barrel 3 is provided with a third flow channel 7, the spiral groove 6 is connected with the third flow channel 7, and the medium flows axially along the third flow channel 7 and the spiral groove 6. This embodiment not only effectively shortens the length of the screw pump, simplifies the structural setting of the screw pump (no need for traditional transmission shafts, reducers and couplings, etc., and the traditional suction chamber becomes a part of the transmission structure), but also has stable and reliable transmission and delivery efficiency, and even better than the traditional screw pump structure.

[0031] It can be understood that in this embodiment, the flow barrel 3 can also be fixed, the stator 1 (containing a spiral bushing) can be rotatably set, the transmission assembly is connected to the stator 1, and the other structures remain unchanged. At this time, the rotation of the stator 1 is used to realize the change and movement of the screw pump cavity, thereby conveying the medium. In this structure, the stator 1 drives the rotor 2 to swing. Compared with an externally driven single-screw pump disclosed in the Chinese utility model patent with application number 2018207367674, there is no situation in which the rotor 2 and the stator 1 rotate at the same time, which can better ensure the conveying efficiency, and can also shorten the structural length of the screw pump and simplify the structural setting of the screw pump.

[0032] Embodiment 2: This embodiment is based on Embodiment 1, and further optimizes and refines the structure of the screw pump, specifically, refines the rotation setting structure of the flow barrel 3. The straight-through screw pump described in this embodiment also includes a bearing seat 8 and a base 9, the base 9 is welded by channel steel, etc., the motor 5 and two bearing seats 8 are installed on the base 9, and the bearing seat 8 is provided with a rotating bearing 10. The two ends of the flow barrel 3 are respectively connected to the bearing seat 8 for rotation. The structure is simple and easy to implement. The setting of the bearing seat 8 improves the reliability of the equipment.

[0033] It is understandable that if the stator 1 is set as a rotating structure and the flow barrel 3 is set as a fixed structure, it is only necessary to set two bearing seats 8 at both ends of the stator 1, and then the two ends of the stator 1 are respectively rotatably connected to the corresponding bearing seats 8. The same applies to the following, so it will not be repeated.

[0034] Embodiment 3: This embodiment is based on Embodiment 2, and further optimizes and refines the structure of the screw pump, specifically: the straight-through screw pump described in this embodiment also includes a tie rod 11, which is arranged between the two bearing seats 8, and the four corners of the bearing seat 8 are respectively arranged with tie rods 11, and the connection between the tie rod 11 and the bearing seat 8 is locked by two nuts (not shown in the drawings), specifically, nuts are respectively arranged on both sides of the bearing seat 8 at the connection, and the existing technical means can be used. By setting the tie rod 11, the tightness of the bearing can be locked and adjusted.

[0035] Embodiment 4: This embodiment is based on Embodiment 3 and further optimizes and refines the structure of the screw pump. Specifically, the straight-through screw pump described in this embodiment also includes a first rotating seat 12 and a second rotating seat 13. The first rotating seat 12 and the second rotating seat 13 are respectively rotatably arranged in the bearing seats 8 at the two ends of the flow barrel 3. The two ends of the flow barrel 3 are respectively connected to the first rotating seat 12 and the second rotating seat 13, so that the disassembly and rotation of the flow barrel 3 are more convenient. The first rotating seat 12 and the second rotating seat 13 are respectively provided with a first flow channel 14 and a second flow channel 15. A plurality of first flow channels 14 are arranged in a circumferential array around the first rotating seat 12. The second flow channel 15 is a circular hole that passes through the middle of the second rotating seat 13. The first flow channel 14, the second flow channel 15, the third flow channel 7 and the spiral groove 6 are connected, and the medium flows axially along the first flow channel 14, the second flow channel 15, the third flow channel 7 and the spiral groove 6.

[0036] In this embodiment, the first rotating seat 12 is installed on the bearing seat 8 at one end of the flow barrel 3 away from the stator 1, and the universal joint 4 is installed in the middle of the first rotating seat 12 to facilitate the connection between the universal joint 4 and the rotor 2.

[0037] Example 5: This example is a further optimization and refinement of the screw pump structure based on Example 4. Specifically, the straight-through screw pump described in this example also includes a mounting seat 16 and a feed body 17. The mounting seat 16 is installed on the bearing seat 8 at one end of the flow barrel 3 close to the stator 1, and the feed body 17 is installed on the bearing seat 8 at one end of the flow barrel 3 away from the stator 1. One end of the stator 1 is connected to the mounting seat 16, and the other end is supported on the base 9. The mounting seat 16 and the feed body 17 are respectively provided with a fourth flow channel 18 and a fifth flow channel 19, and the fifth flow channel 19 is connected to the outside, and the first flow channel 14, the second flow channel 15, the third flow channel 7, the fourth flow channel 18, the fifth flow channel 19 and the spiral through groove 6 are connected.

[0038] Embodiment 6: This embodiment is based on Embodiment 5, and further optimizes and refines the structure of the screw pump, specifically:

[0039] The straight-through screw pump described in this embodiment further includes a connecting sleeve 20 and a mechanical seal 21. The mounting seat 16 and the second rotating seat 13, the feed body 17 and the first rotating seat 12 are arranged relatively on their respective bearing seats 8. The connecting sleeve 20 and the mechanical seal 21 are respectively arranged between the mounting seat 16 and the second rotating seat 13, and between the feed body 17 and the first rotating seat 12. The mechanical seal 21 is arranged outside the connecting sleeve 20 to ensure the sealing performance of the entire pump body.

[0040] Example 7: This example is a further optimization and refinement of the screw pump structure based on Example 6. Specifically, the straight-through screw pump described in this example has a universal joint 4 including a universal swing shaft and a connector connected to both ends of the universal swing shaft. The connector is connected to the universal swing shaft by a pin. The two ends of the universal swing shaft can swing in different directions along the connection. The two ends of the universal swing shaft are respectively connected to the first rotating seat 12 and the rotor 2 through the connector. The structure is simple and the connection is reliable.

[0041] In this embodiment, the transmission assembly is a belt drive or a chain drive, and can also be a gear drive or a worm gear drive. A discharge body 22 is provided at one end of the stator 1 away from the flow barrel 3, and a sixth flow channel 23 is provided on the discharge body 22 for connecting the spiral groove 6 of the stator 1 with the outside world.

[0042] More preferably, the transmission assembly is defined as a belt drive in this embodiment, including a large pulley 24, a small pulley 25 and a transmission belt 26 connecting the large pulley 24 and the small pulley 25, wherein the large pulley 24 is arranged on the outer wall of the flow barrel 3, and the small pulley 25 is arranged on the output end of the motor 5. The belt drive has the characteristics of simple structure, stable transmission, buffering and vibration absorption, low cost, no need for lubrication, easy maintenance, etc.

[0043] When the present invention is used, the motor 5 drives the transmission component to work, the transmission component drives the flow barrel 3 to rotate, and the flow barrel 3 drives the rotor 2 to rotate and swing, thereby conveying the medium. The medium enters the pump body through the fifth flow channel 19 of the feed body 17, and then passes through the connecting sleeve 20, the first flow channel 14, the third flow channel 7, the second flow channel 15, the connecting sleeve 20, the fourth flow channel 18, the spiral groove 6 and the sixth flow channel 23 in sequence before being discharged.

[0044] In addition, in the description of the invention, unless otherwise specified, the terms "multiple", "multiple roots", "multiple groups" are used to mean two or more than two, and "several", "several roots", "several groups" are used to mean one or more than one. In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", and "third" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0045] The specific implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A straight-through screw pump, characterized in that: The straight-through screw pump has an axially penetrating medium flow channel, and when used for medium transportation, the medium flows along the axial direction of the screw pump. The straight-through screw pump comprises: a stator (1), a rotor (2), a flow barrel (3), a universal joint (4), a transmission assembly and a motor (5); The flow barrel (3) is rotatably arranged, the output end of the motor (5) and the flow barrel (3) are connected via a transmission assembly, the motor (5) drives the flow barrel (3) to rotate via the transmission assembly, and a universal joint (4) is arranged in the flow barrel (3) to rotate with the flow barrel (3); the stator (1) is arranged at one end of the flow barrel (3), the rotor (2) is helically meshed in the stator (1), one end of the rotor (2) is connected to the universal joint (4), and the other end is freely placed in the stator (1); The stator (1) is provided with a spiral groove (6), the flow barrel (3) is provided with a third flow channel (7), the spiral groove (6) is connected to the third flow channel (7), and the medium flows axially along the third flow channel (7) and the spiral groove (6).

2. The straight-through screw pump according to claim 1, characterized in that: It also comprises a bearing seat (8) and a base (9), wherein two bearing seats (8) are mounted on the base (9), a rotating bearing (10) is arranged in the bearing seat (8), and the two ends of the flow barrel (3) are respectively rotatably connected to the bearing seats (8).

3. The straight-through screw pump according to claim 2, characterized in that: It also includes a pull rod (11), which is arranged between the two bearing seats (8), and the pull rods (11) are respectively arranged at the four corners of the bearing seat (8), and the connection between the pull rod (11) and the bearing seat (8) is locked by two nuts.

4. The straight-through screw pump according to claim 3, characterized in that: The invention also comprises a first rotating seat (12) and a second rotating seat (13), wherein the first rotating seat (12) and the second rotating seat (13) are rotatably arranged in bearing seats (8) at two ends of the flow barrel (3), respectively, and the two ends of the flow barrel (3) are respectively connected to the first rotating seat (12) and the second rotating seat (13), and the first flow channel (14) and the second flow channel (15) are respectively arranged on the first rotating seat (12) and the second rotating seat (13), and the first flow channel (14), the second flow channel (15), the third flow channel (7) and the spiral groove (6) are connected, and the medium flows axially along the first flow channel (14), the second flow channel (15), the third flow channel (7) and the spiral groove (6).

5. The straight-through screw pump according to claim 4, characterized in that: The first rotating seat (12) is mounted on a bearing seat (8) at one end of the flow barrel (3) away from the stator (1), and the universal joint (4) is mounted in the middle of the first rotating seat (12).

6. The straight-through screw pump according to claim 5, characterized in that: The invention also comprises a mounting seat (16) and a feed body (17), wherein the mounting seat (16) is mounted on a bearing seat (8) at one end of the flow barrel (3) close to the stator (1), and the feed body (17) is mounted on a bearing seat (8) at one end of the flow barrel (3) away from the stator (1), one end of the stator (1) is connected to the mounting seat (16), and the other end is supported on a base (9), and a fourth flow channel (18) and a fifth flow channel (19) are respectively arranged on the mounting seat (16) and the feed body (17), and the first flow channel (14), the second flow channel (15), the third flow channel (7), the fourth flow channel (18), the fifth flow channel (19) and the spiral through groove (6) are connected.

7. The straight-through screw pump according to claim 6, characterized in that: It also includes a connecting sleeve (20) and a mechanical seal (21). The connecting sleeve (20) and the mechanical seal (21) are respectively arranged between the mounting seat (16) and the second rotating seat (13), and between the feed body (17) and the first rotating seat (12). The mechanical seal (21) is arranged outside the connecting sleeve (20).

8. The straight-through screw pump according to any one of claims 1 to 7, characterized in that: The universal joint (4) comprises a universal swing shaft and a connector connected to both ends of the universal swing shaft, the connector and the universal swing shaft are connected via a latch, the two ends of the universal swing shaft can swing in different directions along the connection, and the two ends of the universal swing shaft are respectively connected to the first rotating seat (12) and the rotor (2) via the connector.

9. The straight-through screw pump according to claim 8, characterized in that: The transmission assembly is a belt drive or a chain drive, and a discharge body (22) is provided at one end of the stator (1) away from the flow barrel (3), and a sixth flow channel (23) is provided on the discharge body (22) for connecting the spiral groove (6) of the stator (1) with the outside.

10. The straight-through screw pump according to claim 9, characterized in that: The transmission assembly is a belt drive, comprising a large pulley (24), a small pulley (25) and a transmission belt (26) connecting the large pulley (24) and the small pulley (25), wherein the large pulley (24) is arranged on the outer wall of the flow barrel (3), and the small pulley (25) is arranged at the output end of the motor (5).

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