A nested self-planting pile driven by gas expansion

Abstract

The present invention discloses a nested self-planting pile driven by gas expansion, comprising an outer pile, an inner pile, an expansion cylinder, and a driving cylinder. The driving cylinder, the expansion cylinder, and the inner pile are sequentially arranged inside the outer pile from top to bottom. An expansion chamber upper plate is installed at the upper end of the expansion cylinder, which is connected to the driving cylinder. A lower expansion chamber plate is embedded in the expansion cylinder, which can move along the expansion cylinder. The lower end of the lower expansion chamber plate extends out of the expansion cylinder and connects to the inner pile. A gas storage cylinder is installed in the driving cylinder. The gas in the gas storage cylinder is transported to the space formed by the expansion chamber upper plate, the expansion cylinder, and the expansion chamber lower plate, driving the expansion chamber lower plate to move downward. The driving force generated by gas expansion drives the inner pile to move, thereby quickly completing the pile planting process. The structural design is ingenious, and the pile planting operation cycle is short.

Description

Technical Field

[0001] The invention relates to a nested self-planting pile driven by gas expansion, belonging to the technical field of self-planting piles. Background Art

[0002] Elevated trestles are an important component of constructing shore-connecting access channels. Due to cost-effectiveness, most elevated trestle modules do not have the ability to cross the sea on their own. Elevated trestle modules generally require other transport ships to cross the sea for transportation. However, transport ships have certain restrictions on the structural dimensions of elevated trestles. Therefore, the previous elevated trestle integral pile leg solution cannot meet the needs of elevated trestle module crossing the sea.

[0003] Elevated trestles are usually constructed in shallow waters near the coast. Piling is the main method to quickly and steadily stabilize elevated trestles. However, due to the high time limit for trestle erection and the high self-protection requirements for erection equipment, general pile-planting machinery has a large structure, is difficult to carry, and has a long pile-planting operation cycle, which cannot meet the requirements for nested piles of elevated trestles.

[0004] The information disclosed in this background section is only intended to enhance understanding of the overall background of the invention and should not be considered as an admission or any form of suggestion that the information constitutes the prior art already known to a person of ordinary skill in the art. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a nested self-planting pile driven by gas expansion. The driving force generated by gas expansion drives the inner pile to move to quickly complete the pile planting process. The structural design is ingenious and the pile planting operation cycle is short.

[0006] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0007] The present invention discloses a nested self-planting pile driven by gas expansion, comprising an outer pile, an inner pile, an expansion cylinder and a driving cylinder.

[0008] The driving cylinder, the expansion cylinder and the inner pile are sequentially arranged inside the outer pile from top to bottom;

[0009] The upper end of the expansion cylinder is equipped with an expansion chamber upper plate, which is connected to the driving cylinder. The expansion cylinder is embedded with an expansion chamber lower plate, which can move along the expansion cylinder. The lower end of the expansion chamber lower plate extends out of the expansion cylinder and is connected to the inner pile.

[0010] A gas storage cylinder is installed in the driving cylinder, and the gas in the gas storage cylinder is transported to the space formed by the upper plate of the expansion chamber, the expansion cylinder and the lower plate of the expansion chamber, driving the lower plate of the expansion chamber to move downward.

[0011] Furthermore, a gas pipeline is provided in the driving cylinder, and a gas inlet is provided on the upper plate of the expansion chamber;

[0012] One end of the gas pipeline is connected to the gas storage cylinder, and the other end is connected to the gas inlet.

[0013] Furthermore, a pipeline valve is installed on the gas pipeline.

[0014] Furthermore, a positioning rack is fixed axially on the inner side of the outer pile, and the side walls of the driving cylinder, the expansion cylinder and the inner pile are all provided with rack guide grooves corresponding to the positioning rack; a gear meshing with the positioning rack is also installed in the driving cylinder.

[0015] Furthermore, the driving cylinder and the inner pile are both provided with a locking mechanism cooperating with the positioning rack;

[0016] The locking mechanism includes a second locking tooth block and a second fixed plate, wherein the second locking tooth block is movably mounted on the second fixed plate through a rotating spring and a stop iron;

[0017] The second locking tooth block is provided with a sliding surface and a locking surface that cooperate with the positioning rack.

[0018] Furthermore, the stop iron is provided with a rotation limiting surface that cooperates with the second locking tooth block.

[0019] Furthermore, an air release channel is provided on the inner wall of the expansion cylinder, a second air release channel groove connected to the air release channel is provided on the outer wall of the lower plate of the expansion chamber, and a first air release channel groove connected to the air release channel is provided on the outer wall of the upper plate of the expansion chamber, and the first air release channel groove is connected to the inner cavity of the outer pile.

[0020] Furthermore, a lower expansion chamber is provided on the lower plate of the expansion chamber, and a first air leakage hole is provided at the bottom end of the lower expansion chamber;

[0021] A second air leakage hole cooperating with the first air leakage hole is provided on the side wall of the air leakage channel, and the first air leakage hole is connected to the air leakage channel through the second air leakage hole.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The invention provides a nested self-planting pile driven by gas expansion, which utilizes the driving force of gas expansion to drive the movement of piles within the nested piles to realize the pile planting process.

[0024] The present invention can realize automatic planting of nested piles. The overall structure of the nested piles is compact, which is convenient for arrangement on the elevated trestle module, thereby improving the transportability of the elevated trestle module.

[0025] The gas expansion driven nested self-planting piles of the present invention have an integrated pile planting mechanism and nested piles, which can self-protect and realize self-planting pile operations. Compared with existing pile planting methods, the pile planting operation cycle is extremely short, which can meet the requirements of rapid positioning and fixing of elevated trestles. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of a nested self-planting pile driven by gas expansion;

[0027] Figure 2 It is a schematic diagram of the structure of the outer pile;

[0028] Figure 3 It is a structural diagram of the driving cylinder;

[0029] Figure 4 It is a structural diagram of the upper plate of the expansion chamber;

[0030] Figure 5 It is a structural diagram of the expansion cylinder;

[0031] Figure 6 Schematic diagram of the structure of the second retaining ring;

[0032] Figure 7 It is a structural diagram of the expansion chamber bottom plate;

[0033] Figure 8 It is a schematic diagram of the structure of the inner pile;

[0034] Figure 9 It is a schematic diagram of the locking structure of the inner pile and the outer pile;

[0035] Figure 10 It is a structural diagram of the connecting disk;

[0036] Figure 11 It is a structural diagram of the positioning ring;

[0037] Figure 12 2 is a schematic structural diagram of the second locking tooth block;

[0038] Figure 13 1 is a diagram of the unlocked state of the second locking tooth block and the positioning rack;

[0039] Figure 14 1 is a diagram showing the locked state of the second locking tooth block and the positioning rack;

[0040] In the figure: 1. Outer pile; 2. Inner pile; 3. Upper plate of expansion chamber; 4. Lower plate of expansion chamber; 5. Expansion cylinder; 6. Driving cylinder; 11. Positioning rack; 12. Positioning guide bar; 13. Retaining ring; 21. Connecting plate; 22. Second locking tooth block; 23. Positioning ring; 24. Second fixing plate; 211. Second connecting joint; 212. Sixth rack guide groove; 213. Second guide bar guide groove; 221. Rotating shaft; 222. Stop iron; 223. Rotation limiting surface; 224. Rotation spring; 225. Sliding surface; 226. Locking surface; 231. Seventh rack guide groove; 232. Third guide bar guide groove; 31. Upper expansion chamber; 32. Gas inlet; 33. Second rack guide groove; 34. First air release channel groove; 41. Lower expansion chamber; 42. First air bleed hole; 43. Second air bleed channel groove; 44. Fourth rack guide groove; 45. Stake barrel; 46. First connecting joint; 51. Air bleed channel; 52. Third rack guide groove; 53. Retaining ring of expansion chamber lower plate; 54. Second air bleed hole; 531. First guide bar guide groove; 532. Fifth rack guide groove; 61. Gas storage cylinder; 62. Gas pipeline; 63. Pipeline valve; 64. First locking gear block; 65. Drive gear; 66. First rack guide groove; 67. First fixed plate. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Example

[0042] This embodiment provides a nested self-planting pile driven by gas expansion, such as Figure 1 As shown, it includes an outer pile 1, an inner pile 2, an expansion cylinder 5 and a driving cylinder 6.

[0043] The driving cylinder 6, the expansion cylinder 5 and the inner pile 2 are sequentially arranged inside the outer pile 1 from top to bottom;

[0044] The upper end of the expansion cylinder 5 is equipped with an expansion chamber upper plate 3, which is connected to the driving cylinder 6. The expansion cylinder 5 is embedded with an expansion chamber lower plate 4, which can move along the expansion cylinder 5. The lower end of the expansion chamber lower plate 4 extends out of the expansion cylinder 5 and is connected to the inner pile 2.

[0045] A gas storage cylinder 61 is installed in the driving cylinder 6. The gas in the gas storage cylinder 61 is transported to the space formed by the expansion chamber upper plate 3, the expansion cylinder 5 and the expansion chamber lower plate 4, driving the expansion chamber lower plate 4 to move downward.

[0046] Specifically, such as Figure 2As shown, a positioning rack 11 and a positioning guide bar 12 are fixedly mounted axially on the inner side of the stud 1. In this embodiment, there are two positioning racks 11, symmetrically positioned on the inner side of the stud 1. There are also two positioning guide bars 12, symmetrically positioned on the inner side of the stud 1. The plane formed by the two positioning racks 11 and the plane formed by the two positioning guide bars 12 are perpendicular to each other. A first retaining ring 13 is also provided at the bottom end of the stud 1 to limit the movement of the stud 2.

[0047] like Figure 3 and Figure 4 As shown, the driving cylinder 6 is provided with a first rack guide groove 66 that cooperates with the positioning rack 11 .

[0048] A gas storage cylinder 61 and a gas pipeline 62 are provided in the driving cylinder 6, and a gas inlet 32 ​​is provided on the upper plate 3 of the expansion chamber; one end of the gas pipeline 62 is connected to the gas storage cylinder 61, and the other end is connected to the gas inlet 32;

[0049] A pipeline valve 63 is installed on the gas pipeline 62.

[0050] Specifically, an upper expansion chamber 31 is further provided at the lower end of the expansion chamber upper plate 3.

[0051] The operator controls the opening and closing of the pipeline valve 63 so that the gas from the gas storage cylinder 61 passes through the gas pipeline 62 and the gas inlet 32 ​​and enters the upper expansion chamber 31. The gas storage cylinder 61 of this embodiment is filled with carbon dioxide gas and an expansion auxiliary agent.

[0052] A first locking mechanism cooperating with the positioning rack 11 and a driving gear 65 meshing with the positioning rack 11 are provided in the driving cylinder; the first locking mechanism includes a first fixed plate 67 and a first locking tooth block 64, the first locking tooth block 64 is elastically mounted on the first fixed plate 67, and the driving gear 65 is movably mounted on the first fixed plate 67, and the first locking tooth block 64 and the driving gear 65 are both movably connected to the positioning rack 11; the first fixed plate 67 is mounted on the upper plate 3 of the expansion chamber.

[0053] It should be noted that the side end of the first fixing plate 67 extends through the first rack guide groove 66, thereby allowing the first locking tooth block 64 and the driving gear 65 to be movably connected to the positioning rack 11 of the external pile 1. In this embodiment, the driving gear 65 is hydraulically or electrically controlled, and the engagement of the driving gear 65 with the positioning rack 11 realizes the up and down movement of the pile driver; the engagement of the first locking tooth block 64 with the positioning rack 11 realizes the locking between the pile driver and the external pile 1.

[0054] In this embodiment, there are two sets of first locking mechanisms, which are symmetrically arranged in the driving cylinder 6 . Each set of locking mechanisms includes a first fixing plate 67 and three first locking tooth blocks 64 .

[0055] like Figure 4 、 5 and Figure 7 As shown, an air leakage channel 51 is provided on the inner wall of the expansion cylinder 5, and a second air leakage channel groove 43 communicating with the air leakage channel 51 is provided on the outer wall of the expansion chamber lower plate 4. The second air leakage channel groove 43 communicates with the space formed by the expansion chamber upper plate 3, the expansion cylinder 5 and the expansion chamber lower plate 4.

[0056] A first air leakage channel groove 34 communicating with the air leakage channel 51 is provided on the outer wall of the upper plate 3 of the expansion chamber. The first air leakage channel groove 34 communicates with the inner cavity of the outer pile.

[0057] A third rack guide groove 52 cooperating with the positioning rack 11 is provided on the outer wall of the expansion cylinder 5 , and a second rack guide groove 33 cooperating with the positioning rack 11 is further provided on the periphery of the expansion chamber upper plate 3 .

[0058] The upper end of the expansion cylinder 5 is fixedly mounted with the expansion chamber upper plate 3, the lower portion is fixedly mounted with a second retaining ring 53, and the internal portion is movably mounted with the expansion chamber lower plate 4. The purpose of the second retaining ring 53 is to limit the downward end position of the expansion chamber lower plate 4.

[0059] like Figure 6 As shown, the second retaining ring 53 is provided with a first guide bar guide groove 531 that cooperates with the positioning guide bar 12, and a fifth rack guide groove 532 that cooperates with the positioning rack 11. The outer periphery of the second retaining ring 53 is in close contact with the inner side of the outer pile 1.

[0060] like Figure 7 As shown, the outer periphery of the expansion chamber lower plate 4 is in close contact with the inner side of the expansion cylinder 5. The expansion chamber lower plate 4 is provided with a fourth rack guide groove 44 that cooperates with the positioning rack 11.

[0061] A lower expansion chamber 41 is provided on the expansion chamber lower plate 4 , and a first air leakage hole 42 is provided at the bottom end of the lower expansion chamber 41 ; a second air leakage hole 54 cooperating with the first air leakage hole 42 is provided on the air leakage channel 51 .

[0062] A stake tube 45 is provided at the lower end of the expansion chamber lower plate 4 , and a first connecting joint 46 is provided at the lower end of the stake tube 45 .

[0063] It should be noted that the positioning rack 11 is located in the third rack guide groove 52 of the expansion cylinder 5 , and the third rack guide groove 52 is respectively connected to the second rack guide groove 33 and the fourth rack guide groove 44 .

[0064] like Figure 8-11 As shown, the inner pile 2 is a circular steel pipe pile with a smaller diameter than the outer pile 1. A connecting plate 21 is fixed to the top of the inner pile 2. A second connecting joint 211 is provided on the connecting plate 21 to cooperate with the first connecting joint 46 for the purpose of connecting to the lower plate 4 of the expansion chamber.

[0065] The connecting plate 21 is provided with a sixth rack guide groove 212 that cooperates with the positioning rack 11 , and a second guide bar guide groove 213 that cooperates with the positioning guide bar 12 .

[0066] A positioning ring 23 is also provided around the inner pile 2, positioned a certain distance from the top of the inner pile 2. This positioning ring 23 defines a seventh rack guide groove 231 that engages with the positioning rack 11, and a third guide bar guide groove 232 that engages with the positioning guide bar 12. The outer periphery of the positioning ring 23 of the inner pile 2 is in close contact with the inner side of the outer pile 1. The connecting plate 21 of the inner pile 2 and the positioning ring 23 of the inner pile 2 together form the fixed support end of the inner pile 2.

[0067] A second locking mechanism cooperating with the positioning rack 11 is provided in the inner pile 2. The second locking mechanism includes a second fixing plate 24 and a second locking tooth block 22. The second locking tooth block 22 is elastically mounted on the second fixing plate 24 and movably connected to the positioning rack 11.

[0068] The upper end of the second fixing plate 24 is fixedly connected to the connecting plate 21 of the inner pile 2 .

[0069] In this embodiment, the locking between the inner pile 2 and the outer pile 1 is achieved by the engagement of the second locking tooth block 22 and the positioning rack 11 .

[0070] It should be emphasized that the specific structure and working principle of the first locking tooth block 64 and the second locking tooth block 22 are the same, so only the second locking tooth block 22 is described in detail in this embodiment.

[0071] like Figure 12-14 As shown, the second locking tooth block 22 is mounted on the second fixed plate 24 through a rotation spring 224 and a stop iron 222 , wherein a rotation shaft 221 is provided at the connection between the second locking tooth block 22 and the stop iron 222 , and the rotation shaft 221 is mounted on the second fixed plate 24 .

[0072] The stop iron 222 is provided with a rotation limiting surface 223 for limiting the rotation position of the second locking tooth block 22. The second locking tooth block 22 is provided with a sliding surface 225 and a locking surface 226.

[0073] like Figure 13 As shown, during operation, the outer pile 1 is fixed to the external platform. When the inner pile 2 is inserted downward, the positioning rack 11 presses down the second locking tooth block 22. The second locking tooth block 22 rotates around the rotation axis 221 until the sliding surface 225 is flush with the top of the positioning rack 11. The rotation spring 224 is compressed, the second locking tooth block 22 is unlocked from the positioning rack 11, and the inner pile 2 can be inserted downward along the inner wall of the outer pile 1.

[0074] like Figure 14As shown, once the sliding surface 225 slides over the tooth top of the positioning rack 11, the second locking tooth block 22, under the action of the rotation spring 224, immediately rotates about the rotation axis 221 to the rotation limiting surface 223 of the stop iron 222. At this time, the locking surface 226 of the second locking tooth block 22 engages the surface of the positioning rack 11, locking the positioning rack 11. Because the normal line of the meshing working center of the locking surface 226 and the surface of the positioning rack 11 passes below the rotation axis 221, the rotation of the second locking tooth block 22 is blocked. The force from the outer pile 1 is transmitted to the second locking tooth block 22 through the positioning rack 11, and then through the stop iron 222 to the second fixing plate 24 and then to the inner pile 2, achieving a follow-up locking between the inner pile 2 and the outer pile 1. The combination of the spring and pawl structure achieves real-time follow-up locking of the inner pile 2 of the self-expanding nested pile when it is inserted into the soil.

[0075] To sum up, the working principle is:

[0076] After the pile is assembled, the outer pile 1 is secured to the elevated platform, the first and second locking mechanisms are locked, and the upper expansion chamber 31 and lower expansion chamber 41 are connected, forming the initial gas expansion chamber of the pile. A control valve 63 allows carbon dioxide gas and an expansion aid to enter the initial gas expansion chamber from the storage cylinder through the gas pipeline 62, increasing internal pressure. The upper plate 3 of the expansion chamber is locked by the first locking mechanism, and the lower plate 4 of the expansion chamber is pressed downward. The pile driving cylinder 45 drives the inner pile 2 downward. The second locking mechanism is unlocked, and the initial expansion chamber continues to expand into the internal space of the expansion cylinder 5 between the upper plate 3 and the lower plate 4. The pile driving cylinder 45 continues to push the inner pile 2 downward until the lower plate 4 contacts the second retaining ring 53, and the first vent hole 42 of the lower plate 4 communicates with the second vent hole 54 of the expansion cylinder 5. The carbon dioxide gas that has completed its work is discharged through the vent channel 51 toward the top of the pile driver. At this time, the pressure in the expansion cylinder 5 drops, and the upper part of the pile driver is pushed forward by the deflated air ejected through the deflated air channel 51, and the upper part of the pile driver is pressed downward by gravity, or driven downward by the driving gear 65. The first locking mechanism is unlocked, and the upper plate 3 of the expansion chamber descends to the lower plate 4 of the expansion chamber and stops. The first locking mechanism is locked, and the second locking mechanism is locked at the same time, and the second pile planting cycle begins until the positioning ring 23 of the inner pile 2 is tightly pressed against the first retaining ring 13 of the outer pile 1, and the second locking mechanism on the inner pile 2 is locked, and the self-pile planting process is completed.

[0077] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0078] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0079] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A nested self-planting pile driven by gas expansion, characterized by: It comprises an outer pile (1), an inner pile (2), an expansion cylinder (5) and a driving cylinder (6), The driving cylinder (6), the expansion cylinder (5) and the inner pile (2) are sequentially arranged inside the outer pile (1) from top to bottom; The upper end of the expansion cylinder (5) is provided with an expansion chamber upper plate (3), the expansion chamber upper plate (3) is connected to the driving cylinder (6), the expansion cylinder (5) is embedded with an expansion chamber lower plate (4), the expansion chamber lower plate (4) can move along the expansion cylinder (5), and the lower end of the expansion chamber lower plate (4) extends out of the expansion cylinder (5) to connect to the inner pile (2); A gas storage cylinder (61) is installed in the driving cylinder (6), and the gas in the gas storage cylinder (61) is transported to the space formed by the upper plate (3) of the expansion chamber, the expansion cylinder (5) and the lower plate (4) of the expansion chamber, thereby driving the lower plate (4) of the expansion chamber to move downward.

2. The gas expansion driven nested self-planting pile according to claim 1, characterized in that: A gas pipeline (62) is further provided in the driving cylinder (6), and a gas inlet (32) is provided on the upper plate (3) of the expansion chamber; One end of the gas pipeline (62) is connected to the gas storage cylinder (61), and the other end is connected to the gas inlet (32).

3. The gas expansion driven nested self-planting pile according to claim 2, characterized in that: A pipeline valve (63) is installed on the gas pipeline (62).

4. The gas expansion driven nested self-planting pile according to claim 1, wherein: A positioning rack (11) is fixedly provided on the inner side of the outer pile (1) along the axial direction, and the side walls of the driving cylinder (6), the expansion cylinder (5) and the inner pile (2) are all provided with rack guide grooves corresponding to the positioning rack (11); and a driving gear (65) meshing with the positioning rack (11) is also installed in the driving cylinder (6).

5. The gas expansion driven nested self-planting pile according to claim 4, characterized in that: The driving cylinder (6) and the inner pile (2) are both provided with a locking mechanism that cooperates with the positioning rack (11); The locking mechanism comprises a second locking tooth block (22) and a second fixed plate (24); the second locking tooth block (22) is movably mounted on the second fixed plate (24) via a rotating spring (224) and a stop iron (222); the upper end of the second fixed plate (24) is fixedly connected to the connecting plate (21) of the inner pile (2); The second locking tooth block (22) is provided with a sliding surface (225) and a locking surface (226) that cooperate with the positioning rack (11).

6. The gas expansion driven nested self-planting pile according to claim 5, characterized in that: The stop iron (222) is provided with a rotation limiting surface (223) that cooperates with the second locking tooth block (22).

7. The gas expansion driven nested self-planting pile according to claim 1, wherein: An air leakage channel (51) is provided on the inner wall of the expansion cylinder (5), and a second air leakage channel groove (43) communicating with the air leakage channel (51) is provided on the outer wall of the expansion chamber lower plate (4). A first air leakage channel groove (34) communicating with the air leakage channel (51) is provided on the outer wall of the upper plate (3) of the expansion chamber, and the first air leakage channel groove (34) is connected to the inner cavity of the outer pile.

8. The gas expansion driven nested self-planting pile according to claim 7, wherein: A lower expansion chamber (41) is provided on the lower plate (4) of the expansion chamber, and a first air leakage hole (42) is provided at the bottom end of the lower expansion chamber (41); A second air leakage hole (54) cooperating with the first air leakage hole (42) is provided on the side wall of the air leakage channel (51), and the first air leakage hole (42) is connected to the air leakage channel (51) through the second air leakage hole (54).

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