Sediment isolation type protection assembly for gearbox of farming rotary cultivator
By designing the sediment isolation protection components of the agricultural rotary tiller gearbox, the airbag and return spring structure of the flange cover, spline sleeve and sealing components, the damage problem caused by the sediment entry of the rotary tiller gearbox is solved, and the spline shaft protection and grass cutting are achieved to ensure the normal operation of the rotary tiller.
Patent Information
- Application Number
- CN202510569776.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-05
- Publication Date
- 2025-07-04
AI Technical Summary
In use, the rotary tiller gearbox will enter between the spline sleeves through the gap, resulting in spline shaft damage and oil seal bearing wear.
A sediment isolation protection component of the gearbox of the farm rotary tiller is designed, including a flange cover, a spline sleeve, a sealing assembly and a straw protection plate. Through the cooperation of the airbag and the return spring, the sealing of the spline shaft and the gearbox connection is achieved to prevent the sediment and sand from entering, and to cut off the grass wrapped around the spline sleeve when needed.
Effectively prevents silt and sand from entering the spline sleeve, protects the spline shaft and oil seal bearings, prevents wear, and can cut off the grass wrapped around the spline sleeve to ensure the normal operation of the rotary tiller.
Smart Images
Figure CN120240022A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of agricultural rotary tillers, and in particular to a silt isolation protection component for a gearbox of an agricultural rotary tiller. Background Art
[0002] Rotary tillers are tilling machines that work with tractors to complete ploughing and harrowing operations. They are widely used because of their strong soil crushing ability and flat surface after ploughing. They can also chop up the root stubble buried below the surface, making it easier for seeders to operate and providing a good seed bed for later sowing. When the rotary tiller is in use, the gearbox of the rotary tiller will come into contact with the mud and sand during rotation. At this time, the mud and sand will enter between the spline shaft sleeves through the gap, thereby damaging the spline shaft and causing wear of the oil seal bearing. Summary of the invention
[0003] The object of the present invention is to provide a silt isolation protection component for a gearbox of an agricultural rotary tiller to solve the problems raised by the above-mentioned background technology.
[0004] To achieve the above object, the present invention provides the following technical solutions: A silt isolation protection assembly for a gearbox of an agricultural rotary tiller, comprising a traction frame, a gearbox mounted on the traction frame, a spline shaft connected to the output of the gearbox, both ends of the spline shaft connected to a knife shaft, and each knife shaft is mounted with multiple sets of spaced knife magazines: characterized in that it also includes: A flange cover is sleeved on the spline shaft, and the flange cover is fixedly connected to the side wall of the gearbox by bolts, and the side of the flange cover away from the gearbox is rotatably connected to a spline sleeve, and at the same time, the end of the spline shaft passes through the flange cover and is clamped with the inside of the spline sleeve; A sealing assembly is arranged between the flange cover and the spline sleeve and is used for sealing the connection between the flange cover and the spline sleeve.
[0005] Preferably, one end of the knife shaft close to the spline sleeve is connected with a connecting flange, and the spline sleeve and the connecting flange are connected by bolts; The flange cover is provided with a connection groove at a position corresponding to the side wall of the spline sleeve, a connection block is rotatably arranged inside the connection groove, and one end of the connection block away from the flange cover is connected to the spline sleeve; Two groups of grass-proof plates in a semi-annular structure are sleeved on the outer surface of the connecting block, and the two groups of grass-proof plates are connected to the flange cover by bolts.
[0006] Preferably, the sealing assembly includes a first receiving groove formed in the connecting block near the inner side wall of the connecting groove. The first receiving groove is annular in structure, and a first abutting block is arranged inside the first receiving groove. A first airbag is arranged between the end of the first abutting block and the inner side wall of the first receiving groove; The sealing assembly further includes a second receiving groove formed in the outer surface of the connecting block. A second airbag is arranged inside the second receiving groove, and a plurality of second return springs distributed at intervals are arranged inside the second airbag; A first exhaust pipe is formed between the second airbag and the first airbag, and the second airbag is communicated with the first airbag through the first exhaust pipe.
[0007] Preferably, a sealing groove is formed in the inner side wall of the connecting groove corresponding to the position of the second airbag, and a plurality of anti-friction sleeves distributed at intervals are arranged at the end of the second airbag corresponding to the position of the sealing groove; Third receiving grooves are formed in the sealing groove corresponding to the positions of the anti-friction sleeves respectively. Second abutting blocks are arranged inside the third receiving grooves respectively. A third return spring is arranged between the upper end of the third receiving groove and the inner top end of the second abutting block. The second abutting block is elastically arranged inside the third receiving groove through the corresponding third return spring.
[0008] Preferably, sinking grooves are formed in the side wall of the flange cover corresponding to the positions of the second abutting blocks respectively. Trigger blocks are arranged inside the sinking grooves respectively; First through holes are formed between the sinking grooves and the corresponding third receiving grooves respectively. First pull ropes are arranged inside the first through holes respectively. Two ends of each first pull rope are respectively connected to the upper end of the corresponding second abutting block and the side wall of the corresponding trigger block.
[0009] Preferably, air storage cavities are formed in the connecting block corresponding to the positions of the first airbags respectively. Sealing plates are slidably arranged inside the air storage cavities respectively. A first return spring is arranged between the lower end of the sealing plate and the inner bottom end of the air storage cavity. The sealing plate is elastically arranged inside the air storage cavity through the first return spring; A second exhaust pipe is formed between the top of the air storage cavity and the corresponding first exhaust pipe. The elastic force of the first return spring is greater than that of the second return spring, and the elastic force of the third return spring is greater than that of the first return spring.
[0010] Preferably, grooves are formed in the outer surface of the spline sleeve. There are a plurality of the grooves, and the plurality of grooves are distributed in a circumferential manner; A tool rest is disposed inside each of the grooves, and a plurality of groups of fourth return springs are disposed at intervals between the lower end of each tool rest and the inner bottom end of the corresponding groove; A cutting tool is disposed at the upper end of each tool rest.
[0011] Preferably, a relief groove is formed in the outer surface of the spline sleeve at the end corresponding to each groove, and a plurality of groups of fixing blocks are fixedly disposed at intervals inside the relief groove; An adjusting ring is rotatably sleeved inside the relief groove, an extrusion block is installed on the inner wall of the adjusting ring at the position corresponding to each fixing block, and a fifth airbag is disposed between the extrusion block and the adjacent fixing block.
[0012] Preferably, a fourth airbag is disposed between the lower end of each tool rest and the inner bottom end of the corresponding groove, a third exhaust pipe is formed between the fourth airbag and the corresponding fifth airbag, and the fifth airbag is communicated with the corresponding fourth airbag through the third exhaust pipe.
[0013] Compared with the prior art, the beneficial effects of the present invention are: Through the cooperation of the first return spring and the sealing plate, air is injected into the first airbag and the second airbag, so that the first airbag and the second airbag expand, and the first abutting block and the anti-friction plate on the surface of the second airbag are abutted against the inner wall of the connecting groove, thereby sealing the connection between the connecting block and the connecting groove and preventing sediment from entering; The setting of the weed-proof plate prevents weeds from winding around the connection between the connecting groove and the connecting block, and at the same time limits the connecting block; When the adjusting ring is rotated, the extrusion block will be driven to extrude one side of the fifth airbag, and the air inside the fifth airbag is discharged into the fourth airbag through the third exhaust pipe, and the fourth airbag expands to push the cutting tool on the tool rest to move upward, cutting off the weeds wound around the spline sleeve. Description of the Drawings
[0014] Figure 1 Schematic diagram of the connection structure between the transmission and the tool shaft of the present invention; Figure 2 is Figure 1 Enlarged schematic diagram of the structure at A in Figure 3 Schematic cross-sectional view of the connection between the spline shaft and the spline sleeve of the present invention; Figure 4 is Figure 3 Enlarged schematic diagram of the structure at B in Figure 5 is Figure 4 Enlarged schematic diagram of the structure at C in Figure 6 is Figure 4 Enlarged schematic diagram of the structure at D in Figure 7 Schematic diagram of the spline sleeve structure of the present invention; Figure 8 is Figure 7 Enlarged schematic diagram of the structure at position E in Figure 9 Schematic cross-sectional view of the connection between the adjusting ring and the spline sleeve structure of the present invention; Figure 10 is Figure 9 Enlarged schematic diagram of the structure at position F in
[0015] In the figure: 1. Tractor frame; 2. Gearbox; 3. Spline shaft; 4. Cutter shaft; 5. Tool magazine; 6. Flange cover; 7. Weed guard; 8. Spline sleeve; 9. Connecting flange; 10. Connecting groove; 11. Connecting block; 13. First storage groove; 14. First airbag; 15. First abutting block; 16. First exhaust pipe; 17. Second exhaust pipe; 18. Air storage cavity; 19. First return spring; 20. Sealing plate; 21. Second storage groove; 22. Second return spring; 23. Second airbag; 24. Sealing groove; 25. Third storage groove; 26. Second abutting block; 27. Third return spring; 28. First through hole; 29. First pull rope; 30. Sunk groove; 31. Trigger block; 32. Adjusting ring; 33. Groove; 34. Cutting knife; 35. Tool holder; 36. Fourth airbag; 37. Relief groove; 38. Fixed block; 39. Extrusion block; 40. Fifth airbag; 41. Third exhaust pipe; 42. Fourth return spring. Detailed implementation manners
[0016] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The following will refer to the drawings and combine the embodiments to elaborate on the present application in detail.
[0017] In order to enable those skilled in the art to better understand the solution of the present application, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.
[0018] As Figure 1 shown, the present application provides a sediment isolation type protection component for a farming rotary tiller gearbox, including a tractor frame 1, a gearbox 2 is installed on the tractor frame 1, a spline shaft 3 is connected to the output of the gearbox 2, and the spline shaft 3 rotates through the gearbox 2; In this embodiment: A flange cover 6 is sleeved on the spline shaft 3, and the flange cover 6 is fixedly connected to the side wall of the gearbox 2 by bolts, and the connection between the gearbox 2 and the spline shaft 3 is protected by the flange cover 6.
[0019] Specifically, as Figure 2 and Figure 3 shown, a spline sleeve 8 is rotatably connected to the side of the flange cover 6 away from the gearbox 2. At the same time, the end of the spline shaft 3 passes through the flange cover 6 and is snap-fitted with the inside of the spline sleeve 8; In this embodiment: The spline shaft 3 drives the spline sleeve 8 to rotate relative to the flange cover 6.
[0020] Specifically, as Figure 2 - Figure 3 shown, one end of the spline sleeve 8 is connected with a connecting flange 9 by bolts, the connecting flange 9 is connected with a cutter shaft 4, and a tool magazine 5 is arranged on the cutter shaft 4 at intervals; In this embodiment: Rotary tillage knives are arranged on each of the tool magazines 5, and the spline shaft 3 drives a plurality of groups of rotary tillage knives to rotate through the spline sleeve 8.
[0021] Specifically, as Figure 3 - Figure 6 shown, a connecting groove 10 is formed at the side wall position of the flange cover 6 corresponding to the spline sleeve 8, a connecting block 11 is rotatably arranged inside the connecting groove 10, and one end of the connecting block 11 away from the flange cover 6 is connected with the spline sleeve 8; Two semi-circular anti-weed plates 7 are sleeved on the outer surface of the connecting block 11, and the two anti-weed plates 7 are connected to the flange cover 6 by bolts.
[0022] A sealing assembly is arranged between the connecting groove 10 and the connecting block 11. The sealing assembly includes a first receiving groove 13 formed in the inner side wall of the connecting block 11 close to the connecting groove 10. The first receiving groove 13 is annular, and a first abutting block 15 is arranged inside the first receiving groove 13. A first airbag 14 is arranged between the end of the first abutting block 15 and the inner side wall of the first receiving groove 13; The sealing assembly further includes a second receiving groove 21 formed in the outer surface of the connecting block 11. A second airbag 23 is arranged inside the second receiving groove 21, and a plurality of second return springs 22 are arranged at intervals inside the second airbag 23; A first exhaust pipe 16 is formed between the second airbag 23 and the first airbag 14, and the second airbag 23 is communicated with the first airbag 14 through the first exhaust pipe 16; At a position on the inner side wall of the connecting groove 10 corresponding to the second airbag 23, a sealing groove 24 is formed, and at a position on the end of the second airbag 23 corresponding to the sealing groove 24, a plurality of anti-friction sleeves are arranged at intervals; In this embodiment: Through the cooperation of the first return spring 19 and the sealing plate 20, air is injected into the first airbag 14 and the second airbag 23, so that the first airbag 14 and the second airbag 23 expand, and the anti-friction plates on the surfaces of the first abutting block 15 and the second airbag 23 are abutted against the inner wall of the connecting groove 10, thereby sealing the connection between the connecting block 11 and the connecting groove 10 and preventing sediment from entering.
[0023] Specifically, as Figure 6 shown, at a position in the sealing groove 24 corresponding to each anti-friction sleeve, a third receiving groove 25 is formed. In each of the third receiving grooves 25, a second abutting block 26 is arranged, and a third return spring 27 is arranged between the upper end of the third receiving groove 25 and the inner top end of the second abutting block 26. The second abutting block 26 is elastically arranged in the third receiving groove 25 through the corresponding third return spring 27; At a position on the side wall of the flange cover 6 corresponding to each of the second abutting blocks 26, a counterbore 30 is formed, and a trigger block 31 is arranged in each of the counterbores 30; A first through hole 28 is formed between each of the counterbores 30 and the corresponding third receiving groove 25. A first pull rope 29 is arranged in each of the first through holes 28. Two ends of each of the first pull ropes 29 are respectively connected to the upper end of the corresponding second abutting block 26 and the side wall of the corresponding trigger block 31; In this embodiment: When it is necessary to disassemble the connecting block 11, first disassemble the anti-weed plate 7. After the anti-weed plate 7 is disassembled, the connecting block 11 is no longer limited, and at the same time, the trigger block 31 is no longer abutted. At this time, the elastically arranged second abutting block 26 pops out without being limited by the first pull rope 29, extruding the elastically arranged second airbag 23 out of the sealing groove 24. The gas inside the second airbag 23 is discharged into the air storage cavity 18 through the cooperation of the first exhaust pipe 16 and the second exhaust pipe 17, and then the connecting block 11 is disassembled.
[0024] Specifically, as Figure 7 - Figure 10 shown, at a position in the connecting block 11 corresponding to each of the first airbags 14, an air storage cavity 18 is formed. A sealing plate 20 is slidably arranged in each of the air storage cavities 18, and a first return spring 19 is arranged between the lower end of the sealing plate 20 and the inner bottom end of the air storage cavity 18. The sealing plate 20 is elastically arranged in the air storage cavity 18 through the first return spring 19; A second exhaust duct 17 is provided between the top of the gas storage cavity 18 and the corresponding first exhaust duct 16, and the elastic force of the first return spring 19 is greater than the elastic force of the second return spring 22, and the elastic force of the third return spring 27 is greater than the elastic force of the first return spring 19; A groove 33 is provided on the outer surface of the spline sleeve 8, and multiple groups of the grooves 33 are provided, and the multiple groups of grooves 33 are circumferentially distributed; A tool holder 35 is provided inside each of the grooves 33, and multiple groups of fourth return springs 42 are provided at intervals between the lower end of each tool holder 35 and the inner bottom end of the corresponding groove 33; A cutting tool 34 is provided at the upper end of each tool holder 35; A relief groove 37 is provided at the end position of the outer surface of the spline sleeve 8 corresponding to each of the grooves 33, and multiple groups of fixed blocks 38 are fixedly provided at intervals inside the relief groove 37; An adjusting ring 32 is rotatably sleeved inside the relief groove 37, an extrusion block 39 is installed on the inner wall of the adjusting ring 32 corresponding to the position of each fixed block 38, and a fifth airbag 40 is provided between the extrusion block 39 and the adjacent fixed block 38; A fourth airbag 36 is provided at intervals between the lower end of each tool holder 35 and the inner bottom end of the corresponding groove 33, a third exhaust duct 41 is provided between the fourth airbag 36 and the corresponding fifth airbag 40, and the fifth airbag 40 is communicated with the corresponding fourth airbag 36 through the third exhaust duct 41; In this embodiment: when the adjusting ring 32 is rotated, the extrusion block 39 will be driven to extrude the fifth airbag 40 on one side, and the air inside the fifth airbag 40 is discharged into the fourth airbag 36 through the third exhaust duct 41. The fourth airbag 36 expands and pushes the cutting tool 34 on the tool holder 35 to move upward, cutting off the grass wound around the spline sleeve 8.
[0025] Specifically, the front end of the connecting block 11 is inserted into the connecting groove 10. At this time, the first abutting block 15 contacts and is abutted against the inner wall of the connecting groove 10, and the first airbag 14 is extruded. At this time, the gas inside the first airbag 14 enters the gas storage cavity 18 through the first exhaust duct 16 and the second exhaust duct 17. When the second airbag 23 coincides with the sealing groove 24, the gas inside the gas storage cavity 18 is discharged into the second airbag 23 through the first exhaust duct 16 and the second exhaust duct 17. The second airbag 23 expands and is inserted into the sealing groove 24 to complete the sealing. Then, the two anti-weed plates 7 are snap-fitted onto the outer surface of the connecting block 11 and connected to the flange cover 6 by bolts; The setting of the weed-proof plate 7 prevents weeds from winding around the connection between the connection groove 10 and the connection block 11. When it is necessary to remove the weeds wound around the surface of the spline sleeve 8, rotate the adjusting ring 32. At this time, it will drive the extrusion block 39 to extrude the fifth airbag 40 on one side. The air inside the fifth airbag 40 is discharged through the third exhaust pipe 41 into the fourth airbag 36. The fourth airbag 36 expands and pushes the cutting knife 34 on the tool holder 35 to move upward, cutting off the weeds wound around the spline sleeve 8.
[0026] Those of ordinary skill in the art should understand that the discussion of any of the above embodiments is merely exemplary; under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above. For the sake of brevity, they are not provided in detail.
[0027] The present invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A sediment isolation type protection component for a gearbox of an agricultural rotary tiller, comprising a traction frame (1), a gearbox (2) is installed on the traction frame (1), a spline shaft (3) is connected to the output of the gearbox (2), both ends of the spline shaft (3) are connected to cutter shafts (4), and a plurality of groups of cutter libraries (5) distributed at intervals are installed on each of the cutter shafts (4): It is characterized in that, It further includes: A flange cover (6) sleeved on the spline shaft (3), and the flange cover (6) is fixedly connected to the side wall of the gearbox (2) by bolts. A spline sleeve (8) is rotatably connected to the side of the flange cover (6) away from the gearbox (2). At the same time, the end of the spline shaft (3) passes through the flange cover (6) and is clamped inside the spline sleeve (8); A sealing assembly is arranged between the flange cover (6) and the spline sleeve (8) for sealing the connection between the flange cover (6) and the spline sleeve (8).
2. The sediment isolation type protection component of a farming rotary tiller gearbox according to claim 1, characterized in that, One end of the cutter shaft (4) close to the spline sleeve (8) is connected with a connecting flange (9), and the spline sleeve (8) and the connecting flange (9) are connected by bolts; A connecting groove (10) is formed in the side wall of the flange cover (6) corresponding to the position of the spline sleeve (8). A connecting block (11) is rotatably arranged inside the connecting groove (10), and one end of the connecting block (11) away from the flange cover (6) is connected to the spline sleeve (8); Two groups of semi-circular anti-weed plates (7) are sleeved on the outer surface of the connecting block (11), and the two groups of anti-weed plates (7) are connected to the flange cover (6) by bolts.
3. A sediment isolation type protection component for the gearbox of an agricultural rotary tiller according to claim 2, characterized in that, The sealing assembly includes a first receiving groove (13) formed in the inner side wall of the connecting block (11) close to the inner side wall of the connecting groove (10). The first receiving groove (13) is annular in structure, and a first abutting block (15) is arranged inside the first receiving groove (13). A first airbag (14) is arranged between the end of the first abutting block (15) and the inner side wall of the first receiving groove (13); The sealing assembly further includes a second receiving groove (21) formed in the outer surface of the connecting block (11). A second airbag (23) is arranged inside the second receiving groove (21), and a plurality of second return springs (22) are arranged at intervals inside the second airbag (23); A first exhaust pipe (16) is formed between the second airbag (23) and the first airbag (14), and the second airbag (23) is communicated with the first airbag (14) through the first exhaust pipe (16).
4. A sediment isolation type protection component for a farming rotary tiller gearbox according to claim 3, characterized in that, A sealing groove (24) is formed in the inner side wall of the connecting groove (10) corresponding to the position of the second airbag (23), and a plurality of anti-friction sleeves are arranged at intervals at the end of the second airbag (23) corresponding to the position of the sealing groove (24); Third receiving grooves (25) are formed in the sealing groove (24) corresponding to the positions of the anti-friction sleeves. Second abutting blocks (26) are arranged inside the third receiving grooves (25). A third return spring (27) is arranged between the upper end of the third receiving groove (25) and the inner top of the second abutting block (26). The second abutting block (26) is elastically arranged inside the third receiving groove (25) through the corresponding third return spring (27).
5. The sediment isolation type protection component of a farming rotary tiller gearbox according to claim 4, characterized in that At positions corresponding to the second abutting blocks (26) on the side wall of the flange cover (6), a counterbore (30) is provided, and a trigger block (31) is arranged inside each counterbore (30); A first through hole (28) is provided between each counterbore (30) and the corresponding third receiving groove (25), a first pull rope (29) is arranged inside each first through hole (28), and two ends of each first pull rope (29) are respectively connected to the upper end of the corresponding second abutting block (26) and the side wall of the corresponding trigger block (31).
6. The sediment isolation type protection component of a farming rotary tiller gearbox according to claim 4, characterized in that At positions corresponding to the first air bags (14) inside the connecting block (11), an air storage cavity (18) is provided, a sealing plate (20) is slidably arranged inside each air storage cavity (18), and a first return spring (19) is arranged between the lower end of the sealing plate (20) and the inner bottom end of the air storage cavity (18), and the sealing plate (20) is elastically arranged inside the air storage cavity (18) through the first return spring (19); A second exhaust pipe (17) is provided between the top of the air storage cavity (18) and the corresponding first exhaust pipe (16), and the elastic force of the first return spring (19) is greater than the elastic force of the second return spring (22), and the elastic force of the third return spring (27) is greater than the elastic force of the first return spring (19).
7. A sediment isolation type protection component for the gearbox of an agricultural rotary tiller according to claim 1, characterized in that, A groove (33) is provided on the outer surface of the spline sleeve (8), and multiple groups of grooves (33) are provided, and the multiple groups of grooves (33) are distributed in a circumferential manner; A tool holder (35) is arranged inside each groove (33), and multiple groups of fourth return springs (42) distributed at intervals are arranged between the lower end of each tool holder (35) and the inner bottom end of the corresponding groove (33); A cutting tool (34) is arranged at the upper end of each tool holder (35).
8. A sediment isolation type protection component for a farming rotary tiller gearbox according to claim 7, characterized in that, At the end positions corresponding to the grooves (33) on the outer surface of the spline sleeve (8), a relief groove (37) is provided, and multiple groups of fixing blocks (38) distributed at intervals are fixedly arranged inside the relief groove (37); An adjusting ring (32) is rotatably sleeved inside the relief groove (37), an extrusion block (39) is installed at the position corresponding to each fixing block (38) on the inner wall of the adjusting ring (32), and a fifth air bag (40) is arranged between the extrusion block (39) and the adjacent fixing block (38).
9. The sediment isolation type protection component of a farming rotary tiller gearbox according to claim 8, characterized in that, A fourth air bag (36) is arranged between the lower end of each tool holder (35) and the inner bottom end of the corresponding groove (33), a third exhaust pipe (41) is provided between the fourth air bag (36) and the corresponding fifth air bag (40), and the fifth air bag (40) is communicated with the corresponding fourth air bag (36) through the third exhaust pipe (41).