Ammonia oxidation furnace waste heat utilization equipment

Abstract

The ammoxidation furnace waste heat utilization equipment comprises an internal pipeline and an external pipeline which are arranged inside and outside an ammoxidation furnace, the external pipeline is divided into a liquid inlet pipeline and a liquid outlet pipeline, electromagnetic valves are arranged on the liquid inlet pipeline and the liquid outlet pipeline, and the liquid inlet pipeline and the liquid outlet pipeline of the external pipeline are spirally wound with each other. An on-off adjusting assembly used for adjusting the on-off time interval of the electromagnetic valve is arranged at the position of a discharging pipe of the ammoxidation furnace and comprises a rotating disc and a fixing base, energizing pins are arranged on the rotating disc, a disc making contact with the energizing pins is arranged on the fixing base, and the disc is divided into a conducting sector and an insulating sector. When the electrifying pin is in contact with the conducting sector, the electromagnetic valve is electrified, and a power assembly is arranged in the discharging pipe of the ammoxidation furnace and drives the rotating disc to rotate. The problem that in the prior art, when fluid in a pipeline flows into an ammoxidation furnace, the pipeline is damaged due to the fact that fluid exchange with the large temperature difference is conducted on the pipeline within a short time is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of ammonia oxidation furnace equipment, and in particular relates to a waste heat utilization device for an ammonia oxidation furnace. Background Art

[0002] Ammonia oxidation furnace will generate a large amount of high-temperature waste heat during operation. Reasonable use of the waste heat of the ammonia oxidation furnace can reduce energy consumption. For example, the waste heat of the ammonia oxidation furnace can be used to heat other process fluids, such as hot water. This type of waste heat utilization system sets up pipelines in the ammonia oxidation furnace, so that the waste heat generated by the internal reaction of the ammonia oxidation furnace heats the fluid in the pipeline, and the heated fluid is used for heating.

[0003] However, the operating conditions of the ammonia oxidation furnace are unstable, resulting in unstable waste heat generation and temperature. This makes the temperature of the pipes in the ammonia oxidation furnace in the waste heat utilization system unstable. Normally, the heat absorption of the fluid in the pipe is also a protection for the pipe, but the fluid is always in a flowing state, and the low-temperature fluid flows into the ammonia oxidation furnace, which causes a large temperature difference between the inside and outside of the pipe. When the temperature difference is large, the pipe expands thermally, generating stress that may cause deformation, rupture, or leakage at the connection. Summary of the invention

[0004] The purpose of the present invention is to solve the problem in the prior art that when the fluid inside the pipeline flows into the ammonia oxidation furnace, the pipeline undergoes fluid exchange with a large temperature difference in a short period of time, which affects the pipeline, and to propose an ammonia oxidation furnace waste heat utilization device.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: an ammonia oxidation furnace waste heat utilization device, comprising an internal pipeline arranged in the ammonia oxidation furnace and an external pipeline arranged outside the ammonia oxidation furnace, the internal pipeline is spirally arranged around the inner wall of the main body of the ammonia oxidation furnace, the external pipeline is divided into an inlet pipeline and an outlet pipeline, the inlet pipeline and the outlet pipeline are provided with electromagnetic valves, the external pipeline is provided with a preheating section, the preheating section is located between the electromagnetic valve and the side wall of the ammonia oxidation furnace, and the inlet pipeline and the outlet pipeline of the preheating section are mutually connected. Spiral winding, an on-off adjustment component is provided at the discharge pipe of the ammonia oxidation furnace, the on-off adjustment component is used to adjust the on-off time interval of the solenoid valve, the on-off adjustment component includes a rotating disk and a fixed seat, the rotating disk is provided with an energized pin, the fixed seat is provided with a conductive sector and an insulating sector, the conductive sector and the insulating sector form a disk corresponding to the rotating disk, the energized pin contacts the disk, and when the energized pin contacts the conductive sector, the solenoid valve is energized, and a power component is provided in the discharge pipe of the ammonia oxidation furnace, and the power component drives the rotating disk to rotate.

[0006] As a further description of the above technical solution: the preheating section is provided with an insulation pipe.

[0007] As a further description of the above technical solution: the power component includes a wind fan blade arranged in a discharge pipe, a first sprocket is arranged on the rotating shaft of the wind fan blade, a second sprocket is arranged outside the discharge pipe, the first sprocket and the second sprocket are driven by a chain, a mounting shell is arranged on the discharge pipe, the second sprocket is rotatably arranged in the mounting shell, a first driving bevel gear is rotatably sleeved on the rotating shaft of the second sprocket, a first pawl disk is coaxially arranged on the rotating shaft of the second sprocket, a first inner gear ring groove adapted to the first pawl disk is arranged on the first driving bevel gear, a transmission assembly is arranged between the first driving bevel gear and the rotating disk, the transmission assembly is arranged on the mounting shell, under the action of the transmission assembly, the first driving bevel gear rotates forward or reversely, and the rotating disk keeps rotating in the same direction.

[0008] As a further description of the above technical solution: a reducer is arranged between the power assembly and the rotating disk, a rotating shaft is coaxially arranged on the rotating disk, and the rotating shaft is connected to the output shaft of the reducer.

[0009] As a further description of the above technical solution: the transmission assembly includes a second driving bevel gear meshing with the first driving bevel gear for transmission, a rotating seat is provided on the mounting shell, a third driving bevel gear coaxial with the second driving bevel gear is rotatably provided on the rotating seat, an intermediate bevel gear is also provided on the rotating seat, the intermediate bevel gear meshes with the third driving bevel gear, the rotating shaft of the intermediate bevel gear is perpendicular to the rotating shaft of the second bevel gear, a driving shaft is rotatably provided on the rotating seat, the driving shaft is coaxial with the third driving bevel gear, and a fourth driving bevel gear is rotatably sleeved on the driving shaft Gear, the rotating shaft of the middle bevel gear is perpendicular to the rotating shaft of the second bevel gear, the end face of the third driving bevel gear opposite to the fourth driving bevel gear is provided with a second inner ring groove, the end face of the fourth driving bevel gear opposite to the third driving bevel gear is provided with a third inner ring groove, a second pawl plate is coaxially fixed to the end of the driving shaft facing the third driving bevel gear, a third pawl plate is coaxially fixed to the middle part of the driving shaft, the second pawl plate is adapted to the second inner ring groove, the third pawl plate is adapted to the third inner ring groove, and the end of the driving shaft away from the third driving bevel gear is connected to the rotating plate.

[0010] As a further description of the above technical solution: a filter plate is arranged in the discharge pipe, and the filter plate is located above the wind fan blades.

[0011] As a further description of the above technical solution: a scraper is arranged on the filter plate, and the scraper is a three-stage telescopic type. The front end of the scraper abuts against the inner wall of the discharge pipe, and the rear end of the scraper extends to the outside of the discharge pipe. A connecting shaft is arranged at the rear end of the scraper, and the connecting shaft is rotatably arranged on the mounting shell. The axis of the connecting shaft is parallel to the rotation axis of the second sprocket, and a non-full-tooth bevel gear is coaxially fixed on the connecting shaft. A fifth drive bevel gear meshing with the first drive bevel gear is rotatably arranged on the mounting shell, and a sixth drive bevel gear is coaxially fixed on the rotating shaft of the fifth drive bevel gear. The sixth drive bevel gear meshes with the non-full-tooth bevel gear, and a torsion spring is arranged on the connecting shaft.

[0012] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0013] (1) The preheating section located outside the ammonia oxidation furnace preheats the fluid entering the ammonia oxidation furnace in advance, so that the temperature difference of the fluid entering the ammonia oxidation furnace before and after heating is reduced, reducing the impact on the pipeline. The fluid in the liquid inlet pipeline is preheated by spirally winding the liquid outlet pipeline and the liquid inlet pipeline to reduce heat waste.

[0014] (2) The gas flow in the discharge pipe provides power to the power component to drive the rotating disk of the on-off adjustment component to rotate, and the on-off time interval of the solenoid valve is adaptively adjusted according to the internal working conditions of the ammonia oxidation furnace, so that the heating time of the fluid in the ammonia oxidation furnace can be adjusted according to the working state of the ammonia oxidation furnace. In addition, the fluid in the liquid inlet pipeline has sufficient preheating time.

[0015] (3) The filter plate can isolate the impurities generated by the internal reaction of the ammonia oxidation furnace to prevent them from adhering to the wind fan blades. When the ammonia oxidation furnace stops working, the scraper scrapes the impurities on the filter plate and moves the impurities to the edge to prevent the accumulation of a large amount of impurities from clogging the filter plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a side view of the present invention;

[0017] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0018] Figure 3 It is a partial structural schematic diagram of the discharge pipe of the present invention;

[0019] Figure 4 This is a partial exploded view of the discharge pipe of the present invention;

[0020] Figure 5 It is a partial cross-sectional view of the discharge pipe of the present invention;

[0021] Figure 6 for Figure 5Enlarged view of point B in the middle;

[0022] Figure 7 This is an exploded view of the on-off adjustment component of the present invention;

[0023] Figure 8 An exploded view of the transmission assembly and the drive assembly of the present invention;

[0024] Fig. 9 This is an exploded view of the transmission assembly and the drive assembly of the present invention from another angle.

[0025] Legend: 1. Ammonia oxidation furnace; 2. Liquid inlet pipeline; 3. Liquid outlet pipeline; 4. Solenoid valve; 5. Preheating section; 6. Insulation pipe; 7. Mounting port; 8. Mounting plate; 9. Mounting shell; 10. Discharge pipe; 11. Wind fan blade; 12. Second sprocket; 13. Chain; 14. First drive bevel gear; 15. First ratchet plate; 16. First inner gear ring groove; 17. Sealing cover; 18. Second drive bevel gear; 19. Rotating seat; 20. Third drive bevel gear; 21. Second Ratchet plate; 22, second inner gear ring groove; 23, intermediate bevel gear; 24, drive shaft; 25, fourth drive bevel gear; 26, third ratchet plate; 27, third inner gear ring groove; 28, reducer; 29, rotating plate; 30, fixed seat; 31, power pin; 32, conduction sector; 33, insulating sector; 34, filter plate; 35, scraper; 36, connecting shaft; 37, non-full-tooth bevel gear; 38, fifth drive bevel gear; 39, sixth drive bevel gear; 40, torsion spring. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0027] See also Figure 1-9 The present invention provides a technical solution for ammonia oxidation furnace waste heat utilization equipment:

[0028] A waste heat utilization device for an ammonia oxidation furnace comprises an internal pipeline arranged in the ammonia oxidation furnace 1 and an external pipeline arranged outside the ammonia oxidation furnace 1, wherein the internal pipeline is spirally arranged around the inner wall of the main body of the ammonia oxidation furnace 1, and the external pipeline is divided into an inlet pipeline 2 and an outlet pipeline 3, and the positions where the inlet pipeline 2 and the outlet pipeline 3 enter and discharge the ammonia oxidation furnace 1 are arranged closely, and the inlet pipeline 2 and the outlet pipeline 3 are provided with a solenoid valve 4, and the solenoid valve 4 is a two-position four-way valve, which controls the on-off of the inlet pipeline 2 and the outlet pipeline 3 at the same time, and the external pipeline is provided with a preheating section 5, and the preheating section 5 is located between the solenoid valve 4 and the side wall of the ammonia oxidation furnace 1, and the inlet pipeline 2 and the outlet pipeline 3 of the preheating section 5 are spirally wound with each other, and the preheating section 5 is sleeved with an insulation pipe 6.

[0029] A mounting opening 7 is provided on the discharge pipe 10 of the ammonia oxidation furnace 1, and a mounting plate 8 is provided at a position corresponding to the mounting opening 7. The mounting plate 8 is a semicircular arc plate, and a mounting shell 9 is provided on the mounting plate 8. One end of the mounting shell 9 is located in the discharge pipe 10, and the other end is located outside the discharge pipe 10. A wind fan blade 11 is provided in the discharge pipe 10, and a first sprocket is provided on the rotating shaft of the wind fan blade 11. The first sprocket is located in the mounting shell 9, and a second sprocket 12 is provided outside the discharge pipe 10. The second sprocket 12 is provided in the mounting shell 9, and the first sprocket and the second sprocket 12 are driven by a chain 13. A first driving bevel gear 14 is rotatably sleeved on the rotating shaft of the second sprocket 12, and a first ratchet disc 15 is coaxially provided on the rotating shaft of the second sprocket 12. The first driving bevel gear 14 is provided with a first inner gear ring groove 16 adapted to the first ratchet disc 15. The gas passing through the working discharge port of the ammonia oxidation furnace 1 drives the wind fan blade 11 to rotate, driving the first driving bevel gear 14 to rotate, but only one-way rotation can be achieved under the action of the first pawl plate 15 and the first inner gear ring groove 16.

[0030] The mounting shell 9 is provided with a sealing cover 17, and a transmission assembly is arranged in the sealing cover 17. The transmission assembly includes a second driving bevel gear 18 meshing with the first driving bevel gear 14 for transmission. The mounting shell 9 is provided with a rotating seat 19, and a third driving bevel gear 20 coaxial with the second driving bevel gear 18 is rotatably arranged on the rotating seat 19. An intermediate bevel gear 23 is also arranged on the rotating seat 19, and the intermediate bevel gear 23 meshes with the third driving bevel gear 20. The rotation axis of the intermediate bevel gear 23 is perpendicular to the rotation axis of the second bevel gear. A driving shaft 24 is rotatably arranged on the rotating seat 19, and the driving shaft 24 is coaxial with the third driving bevel gear 20. A fourth driving bevel gear 2 is rotatably sleeved on the driving shaft 24. 5. The intermediate bevel gear 23 is meshed with the fourth driving bevel gear 25. The end faces of the third driving bevel gear 20 and the fourth driving bevel gear 25 opposite to each other are provided with a second inner gear ring groove 22. The end faces of the fourth driving bevel gear 25 and the third driving bevel gear 20 opposite to each other are provided with a third inner gear ring groove 27. A second pawl plate 21 is coaxially fixed to the end of the driving shaft 24 facing the third driving bevel gear 20. A third pawl plate 26 is coaxially fixed to the middle of the driving shaft 24. The second pawl plate 21 is matched with the second inner gear ring groove 22. The third pawl plate 26 is matched with the third inner gear ring groove 27. Under the action of the transmission assembly, the first driving bevel gear 14 rotates forward or reversely, and the driving shaft 24 keeps rotating in the same direction.

[0031] One end of the drive shaft 24 away from the third drive bevel gear 20 is connected to the input shaft of the reducer 28. The output shaft of the reducer 28 is provided with an on-off adjustment component, which is used to adjust the on-off time interval of the solenoid valve 4. The on-off adjustment component includes a rotating disk 29 and a fixed seat 30. The rotating disk 29 is provided with an energized pin 31, and the fixed seat 30 is provided with a conductive sector 32 and an insulating sector 33. The conductive sector 32 and the insulating sector 33 form a circular disk corresponding to the rotating disk 29. The energized pin 31 contacts the circular disk. When the energized pin 31 contacts the conductive sector 32, the solenoid valve 4 is energized, and the rotating disk 29 is connected to the output shaft of the reducer 28.

[0032] A filter plate 34 is provided in the discharge pipe 10, and the filter plate 34 is located above the wind fan blades 11. A scraper 35 is provided on the filter plate 34. The scraper 35 is a three-stage telescopic type. The front end of the scraper 35 abuts against the inner wall of the discharge pipe 10, and the rear end of the scraper 35 extends to the outside of the discharge pipe 10 and is located in the sealing cover 17. A connecting shaft 36 is provided at the rear end of the scraper 35. The connecting shaft 36 is rotatably set on the mounting shell 9. The axis of the connecting shaft 36 is parallel to the rotation axis of the second sprocket 12. A non-full-tooth bevel gear 37 is coaxially fixed on the connecting shaft 36. A fifth drive bevel gear 38 meshing with the first drive bevel gear 14 is rotatably set on the mounting shell 9. A sixth drive bevel gear 39 is coaxially fixed on the rotating shaft of the fifth drive bevel gear 38. The sixth drive bevel gear 39 meshes with the non-full-tooth bevel gear 37, and a torsion spring 40 is provided on the connecting shaft 36.

[0033] Working principle: When the ammonia oxidation furnace 1 is working, the raw materials entering the feed port are discharged from the discharge port after high-temperature catalytic reaction. During this process, the wind fan blade 11 rotates, causing the first driving bevel gear 14 to rotate forward, and the first driving bevel gear 14 rotates to drive the fifth driving bevel gear 38 to rotate, and the sixth driving bevel gear 39 rotates to drive the non-full-tooth bevel gear 37, so that the scraper 35 rotates to scrape the surface of the filter plate 34, so that the impurities on the surface of the filter plate 34 are scraped to the edge of the filter plate 34. During this process, the torsion spring 40 accumulates force, and the scraper 35 moves from one side of the filter plate 34 to the other side, and then the sixth driving bevel gear 39 is no longer engaged with the non-full-tooth bevel gear 37. When the wind fan blade 11 stops rotating, the scraper 35 rotates and resets under the action of the torsion spring 40, and the non-full-tooth bevel gear 37 is engaged with the sixth driving bevel gear 39 again, and drives the first driving bevel gear 14 to rotate in the opposite direction.

[0034] When the first driving bevel gear 14 rotates forward, the third driving bevel gear 20 rotates backward and the fourth driving bevel gear rotates forward, so the third driving bevel gear 20 drives the driving shaft 24 to rotate backward under the action of the second pawl plate 21 and the second inner gear ring groove 22, so that the driving shaft 24 rotates backward. When the wind fan blade 11 stops rotating, the first driving bevel gear 14 rotates forward to a certain angle under the action of the torsion spring 40, at which time the third driving bevel gear 20 rotates forward and the fourth driving bevel gear rotates backward, so the driving shaft 24 rotates backward under the action of the third pawl plate 26 and the third inner gear ring groove 27.

[0035] During the above process, the energized pin 31 always rotates in the opposite direction. When the energized pin 31 contacts the conductive sector 32, the solenoid valve 4 is energized, and the fluids in the inlet pipeline 2 and the outlet pipeline 3 are cut off. When the energized pin 31 contacts the insulating sector 33, the solenoid valve 4 is de-energized, and the inlet pipeline 2 and the outlet pipeline 3 are normally conductive. The intermittent conductive state allows the fluid to have heating time, and also provides a time interval for mutual heat conduction of the preheating section 5, which can protect the pipeline and allow the fluid to have sufficient heating time.

[0036] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Within the technical scope disclosed by the present invention, technicians familiar with the technical field can make equivalent replacements or changes based on the technical scheme and inventive concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An ammonia oxidation furnace waste heat utilization device, characterized in that The invention comprises an internal pipeline arranged in an ammonia oxidation furnace (1) and an external pipeline arranged outside the ammonia oxidation furnace (1), wherein the internal pipeline is spirally arranged around the inner wall of the main body of the ammonia oxidation furnace (1), and the external pipeline is divided into a liquid inlet pipeline (2) and a liquid outlet pipeline (3), and the liquid inlet pipeline (2) and the liquid outlet pipeline (3) are provided with electromagnetic valves (4), and the external pipeline is provided with a preheating section (5), and the preheating section (5) is located between the electromagnetic valve (4) and the side wall of the ammonia oxidation furnace (1), and the liquid inlet pipeline (2) and the liquid outlet pipeline (3) of the preheating section (5) are spirally wound with each other, and an on-off adjustment component is provided at the discharge pipe (10) of the ammonia oxidation furnace (1), and the on-off adjustment component is provided at the discharge pipe (10) of the ammonia oxidation furnace (1). The regulating component is used to regulate the on-off time interval of the electromagnetic valve (4). The on-off regulating component comprises a rotating disk (29) and a fixed seat (30). The rotating disk (29) is provided with an energizing pin (31). The fixed seat (30) is provided with a conducting sector (32) and an insulating sector (33). The conducting sector (32) and the insulating sector (33) form a disk corresponding to the rotating disk (29). The energizing pin (31) contacts the disk. When the energizing pin (31) contacts the conducting sector (32), the electromagnetic valve (4) is energized. A power component is provided in the discharge pipe (10) of the ammonia oxidation furnace (1). The power component drives the rotating disk (29) to rotate.

2. The ammonia oxidation furnace waste heat utilization device according to claim 1, characterized in that: The preheating section (5) is sleeved with a heat preservation pipe (6).

3. The ammonia oxidation furnace waste heat utilization device according to claim 1, characterized in that: The power assembly comprises a wind blade (11) arranged in a discharge pipe (10), a first sprocket is arranged on the rotating shaft of the wind blade (11), a second sprocket (12) is arranged outside the discharge pipe (10), the first sprocket and the second sprocket (12) are driven by a chain (13), a mounting shell (9) is arranged on the discharge pipe (10), the second sprocket (12) is rotatably arranged in the mounting shell (9), and a first driving bevel gear (13) is rotatably sleeved on the rotating shaft of the second sprocket (12). 4), a first pawl plate (15) is coaxially arranged on the rotating shaft of the second sprocket (12), a first inner gear ring groove (16) adapted to the first pawl plate (15) is arranged on the first driving bevel gear (14), a transmission assembly is arranged between the first driving bevel gear (14) and the rotating disk (29), and the transmission assembly is arranged on the mounting shell (9), under the action of the transmission assembly, the first driving bevel gear (14) rotates forward or reversely, and the rotating disk (29) keeps rotating in the same direction.

4. The ammonia oxidation furnace waste heat utilization device according to claim 3, characterized in that: A reducer (28) is arranged between the power assembly and the rotating disk (29), and a rotating shaft is coaxially arranged on the rotating disk (29), and the rotating shaft is connected to the output shaft of the reducer (28).

5. The ammonia oxidation furnace waste heat utilization device according to claim 3, characterized in that: The transmission assembly comprises a second driving bevel gear (18) meshing with the first driving bevel gear (14) for transmission; a rotating seat (19) is provided on the mounting shell (9); a third driving bevel gear (20) coaxial with the second driving bevel gear (18) is rotatably provided on the rotating seat (19); an intermediate bevel gear (23) is also provided on the rotating seat (19); the intermediate bevel gear (23) meshes with the third driving bevel gear (20); the rotating shaft of the intermediate bevel gear (23) is perpendicular to the rotating shaft of the second bevel gear; a driving shaft (24) is rotatably provided on the rotating seat (19); the driving shaft (24) is coaxial with the third driving bevel gear (20); a fourth driving bevel gear (25) is rotatably sleeved on the driving shaft (24); the intermediate bevel gear (23) meshes with the third driving bevel gear (20); the rotating shaft of the intermediate bevel gear (23) is perpendicular to the rotating shaft of the second bevel gear; The rotating shaft of the third bevel gear (3) is perpendicular to the rotating shaft of the second bevel gear, the end surface of the third driving bevel gear (20) opposite to the fourth driving bevel gear (25) is provided with a second inner gear ring groove (22), the end surface of the fourth driving bevel gear (25) opposite to the third driving bevel gear (20) is provided with a third inner gear ring groove (27), a second ratchet plate (21) is coaxially fixed to the end of the driving shaft (24) facing the third driving bevel gear (20), a third ratchet plate (26) is coaxially fixed to the middle of the driving shaft (24), the second ratchet plate (21) is adapted to the second inner gear ring groove (22), the third ratchet plate (26) is adapted to the third inner gear ring groove (27), and the end of the driving shaft (24) away from the third driving bevel gear (20) is connected to the rotating plate (29).

6. The ammonia oxidation furnace waste heat utilization device according to claim 5, characterized in that: A filter plate (34) is arranged in the discharge pipe (10), and the filter plate (34) is located above the wind fan blade (11).

7. The ammonia oxidation furnace waste heat utilization device according to claim 6, characterized in that: The filter plate (34) is provided with a scraper (35), which is a three-stage telescopic type. The front end of the scraper (35) abuts against the inner wall of the discharge pipe (10), and the rear end of the scraper (35) extends to the outside of the discharge pipe (10). The rear end of the scraper (35) is provided with a connecting shaft (36), which is rotatably arranged on the mounting shell (9), the axis of the connecting shaft (36) is parallel to the rotation axis of the second sprocket (12), a non-full-tooth bevel gear (37) is coaxially fixed on the connecting shaft (36), a fifth driving bevel gear (38) meshing with the first driving bevel gear (14) is rotatably arranged on the mounting shell (9), a sixth driving bevel gear (39) is coaxially fixed on the rotating shaft of the fifth driving bevel gear (38), the sixth driving bevel gear (39) meshing with the non-full-tooth bevel gear (37), and a torsion spring (40) is arranged on the connecting shaft (36).

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