Adjustable Adaptive Seat Chassis

Abstract

The present invention discloses an adjustable adaptive seat chassis, which comprises a chassis, a movable tail wing, a tray, a central shaft, a tray shaft and a central shaft spring. The movable tail wing is rotatably mounted on the chassis through the central shaft. The tray is connected to the movable tail wing through the tray shaft and the tray shaft is placed on the chassis. The central shaft spring is sleeved on the central shaft, one end of which abuts against the chassis and the other end abuts against the tray shaft. A multifunctional handle, a lock rod, a first spring and a second spring are also provided. A lock rod pushing part is arranged on the multifunctional handle. The multifunctional handle is inserted into the chassis from one side of the chassis. The lock rod is movably mounted on the chassis. The first spring and the second spring are respectively sleeved on the lock rod. A plurality of lock holes are formed at one end of the movable tail wing, and the lock holes correspond to the direction of the lock rod. This adjustable adaptive seat chassis has the advantages of few accessories, simple structure and convenient operation. The unlocking process of the seat chassis is convenient and stable, improving the comfort of users during use.

Description

Technical Field

[0001] The present invention relates to the technical field of seats, and in particular to an adjustable adaptive seat chassis. Background Art

[0002] A seat tray, also known as a seat chassis, is an important component installed under the seat of a chair, and can realize functions such as the lifting of the seat and the adjustment of the reclining angle of the backrest; for the existing seat chassis, refer to the Chinese invention patent applied by the applicant before, with the patent number: 20151510117850X, the name: Seat Chassis and a Seat with the Seat Chassis, and the authorization announcement date: August 24, 2016. It includes a tray main base, a seat support plate, a movable support member, and a pair of movable support plates. The seat support plate is arranged above the tray main base. The front end of the movable support member is pivotally connected to the seat support plate, and the lower end is pivotally connected to the tray main base. The rear end is used to connect the seat backrest. The front end and the rear end of the movable support member can pivot with the lower end as a fulcrum. The pair of movable support plates are located in front of the movable support member. The upper and lower ends of each movable support plate are respectively pivotally connected to the seat support plate and the tray main base, so that the seat support plate is evenly supported when moving with the movable support member. An elastic member for resisting the backward rotation of the movable support member is installed on the pivot connecting the movable support member and the tray main base. This seat chassis can allow the user to feel an appropriate sense of pressure when reclining the backrest and reduce the friction between the backrest and the user's back.

[0003] However, the above seat chassis still has the following deficiencies: (1) The above seat chassis is also provided with a locking mechanism for locking the seat support plate and the movable support member. The locking mechanism includes a screw, a nut, and a wire control assembly; the wire control assembly includes a wire control, a movable dial, a movable shaft, a torsion spring, and a nut kit. The entire locking mechanism involves many accessories, has a complex structure, a large installation process difficulty, is troublesome to install and disassemble, has a high cost, and is not suitable for popularization and use. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art, and to provide an adjustable adaptive seat chassis with fewer accessories, a simple structure, easy installation and disassembly, and a low cost.

[0005] The purpose of the present invention is achieved as follows:

[0006] An adjustable adaptive seat chassis, comprising a chassis, a movable tail wing, a tray, a central shaft, a tray shaft and a central shaft spring. The movable tail wing is rotatably mounted on the chassis through the central shaft. The tray is connected to the movable tail wing through the tray shaft, and the tray shaft is placed on the chassis. The central shaft spring is sleeved on the central shaft, with one end abutted against the chassis and the other end abutted against the tray shaft. It is characterized in that: a multifunctional handle, a lock rod, a first spring and a second spring are further provided. A lock rod pushing part is provided on the multifunctional handle. The multifunctional handle is inserted into the chassis from one side of the chassis. The lock rod is movably mounted on the chassis. The first spring and the second spring are respectively sleeved on the lock rod. One end of the first spring is abutted against the chassis and the other end is abutted against the lock rod. One end of the second spring is abutted against the lock rod and the other end is abutted against the lock rod pushing part. A plurality of lock holes are opened at one end of the movable tail wing, and the lock holes correspond to the direction of the lock rod.

[0007] The present invention can further adopt the following technical solutions:

[0008] Specifically further, a lock rod mounting part is provided on the chassis. A through hole is opened on the lock rod mounting part, and the through hole corresponds to the position of the lock hole. The lock rod passes through the through hole.

[0009] Specifically further, an annular limiting protrusion is provided on the lock rod. The two ends of the first spring are respectively abutted against the lock rod mounting part of the chassis and one side of the limiting protrusion. The two ends of the second spring are respectively abutted against the other side of the limiting protrusion and the lock rod pushing part.

[0010] Specifically further, two limiting grooves are provided on the lock rod pushing part, and corresponding elastic protrusions are provided on the chassis. The elastic protrusions are clamped into the limiting grooves.

[0011] Specifically further, a spring groove is opened on one side of the chassis. The central shaft spring is placed on the spring groove. One end of the central shaft spring is abutted against the side wall of the spring groove and the other end is abutted against the tray shaft.

[0012] Specifically further, a partition plate is provided in the middle of the spring groove. A central shaft through hole is opened on the partition plate, and the central shaft passes through the central shaft through hole.

[0013] Specifically further, the central shaft springs are provided on both sides of the partition plate in the spring groove.

[0014] Specifically further, an explosion-proof steel plate is further provided on the tray.

[0015] Specifically further, the upper part of the tray is connected to the seat, and the two ends of the movable tail wing are respectively connected to the backrest and the tray.

[0016] Specifically, the movable tail wing is provided with a central axis hole and a tray axis hole, the central axis passes through the central axis hole and is rotatably connected to the chassis, the tray axis passes through the tray axis hole and is connected to the tray, the tray axis hole and the backrest are respectively provided at both ends of the movable tail wing, and the central axis hole is located in the middle of the movable tail wing.

[0017] The beneficial effects of the present invention are as follows:

[0018] (1) This type of adjustable adaptive seat chassis presses down one end of the movable tail wing, causing the movable tail wing to rotate around the central axis, driving the tray shaft located at the other end of the movable tail wing to move, and then driving the tray to move up through the tray shaft, so as to achieve adaptive linkage between the movable tail wing and the tray; at the same time, by adding a multi-function handle, a lock rod, a first spring and a second spring, the multi-function handle is pushed to drive the lock rod to be inserted into the lock hole of the movable tail wing or to be disengaged from the lock hole of the movable tail wing, so as to achieve locking or unlocking between the chassis and the movable tail wing. The entire seat chassis has few accessories, a simple structure and is easy to operate because the locking part includes the multi-function handle, the lock rod, the first spring and the second spring. The advantage of convenience; in addition, when the locking rod is inserted into the locking hole of the movable tail wing to lock the movable tail wing, the locking hole of the movable tail wing also locks the locking rod under the influence of the central axis spring. Therefore, when the multi-function handle is pushed to release the lock between the chassis and the movable tail wing, the locking rod will not be reset immediately due to the locking effect of the locking hole, that is, the movable tail wing will not be reset immediately. At this time, it is necessary to press down one end of the movable tail wing in the opposite direction of the resetting direction of the movable tail wing to release the lock of the lock hole on the movable tail wing on the locking rod, so that the locking rod can be reset under the action of the first spring. Therefore, the entire unlocking process is convenient and stable, which improves the comfort of users when using it.

[0019] (2) The lock rod mounting portion plays a positioning role in the installation of the lock rod on the chassis, facilitating the installation of the lock rod on the chassis. At the same time, the through hole on the lock rod mounting portion plays a limiting role in the movement of the lock rod on the lock rod mounting portion, preventing the lock rod from escaping from the lock rod mounting portion.

[0020] (3) The multi-function handle is locked on the chassis by inserting the elastic protrusion on the chassis into the limiting groove on the locking rod pushing part. The operation is simple and the locking is reliable.

[0021] (4) The spring slot provides space for the installation of the center axis spring on the chassis. When the spring is reset, the tray shaft will be driven by the center axis spring to drive the movable tail wing to rotate, so as to realize the automatic reset of the tray shaft and the movable tail wing.

[0022] (5) An explosion-proof steel plate is also installed on the tray to prevent the gas pressure rod on the seat from exploding and rushing out, thereby improving the safety of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1It is a perspective view of the adjustable adaptive seat chassis of the present invention.

[0024] Figure 2 is Figure 1 a perspective view from another angle.

[0025] Figure 3 It is a sectional view of the adjustable adaptive seat chassis of the present invention.

[0026] Figure 4 It is a schematic diagram of the seat chassis after removing the tray of the present invention.

[0027] Figure 5 It is an exploded view of the adjustable adaptive seat chassis of the present invention.

[0028] Figure 6 It is an initial state diagram of the adjustable adaptive seat chassis of the present invention.

[0029] Figure 7 It is a reclined state diagram of the adjustable adaptive seat chassis of the present invention.

[0030] Figure 8 It is an enlarged perspective view of the multifunctional handle of the present invention.

[0031] Figure 9 It is an exploded view of the elastic adjustment device of the present invention.

[0032] Figure 10 is Figure 9 a schematic diagram from another angle. Detailed implementation manners

[0033] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0034] Embodiment: As Figures 1 to 10As shown in the figure, an adjustable adaptive seat chassis includes a chassis 1, a movable tail wing 2, a tray 3, a central shaft 4, a tray shaft 5 and a central shaft spring 6. The upper part of the tray 3 is connected to the seat. Both ends of the movable tail wing 2 are respectively connected to the backrest and the tray 3. The movable tail wing 2 is rotatably mounted on the chassis 1 through the central shaft 4. The tray 3 is connected to the movable tail wing 2 through the tray shaft 5 and the tray shaft 5 is placed on the chassis 1. The central shaft spring 6 is sleeved on the central shaft 4, one end of which abuts against the chassis 1 and the other end abuts against the tray shaft 5. It is characterized in that: there are also provided a multifunctional handle 7, a locking rod 8, a first spring 9 and a second spring 10. There is a locking rod pushing part 71 on the multifunctional handle 7. The multifunctional handle 7 is inserted into the chassis 1 from one side of the chassis 1. The locking rod 8 is movably mounted on the chassis 1. The first spring 9 and the second spring 10 are respectively sleeved on the locking rod 8. One end of the first spring 9 abuts against the chassis 1 and the other end abuts against the locking rod 8. One end of the second spring 10 abuts against the locking rod 8 and the other end abuts against the locking rod pushing part 71. There are several locking holes 21 opened at one end of the movable tail wing 2, and the locking holes 21 correspond to the direction of the locking rod 8. For this adjustable adaptive seat chassis, by adding a multifunctional handle 7, a locking rod 8, a first spring 9 and a second spring 10, pushing the multifunctional handle 7 drives the locking rod 8 to be inserted into or disengaged from the locking hole 21 of the movable tail wing 2, so as to realize the locking or unlocking between the chassis 1 and the movable tail wing 2. For the whole seat chassis, since the locking part includes a multifunctional handle 7, a locking rod 8, a first spring 9 and a second spring 10, it has the advantages of few accessories, simple structure and convenient operation. Moreover, when the locking rod 8 is inserted into the locking hole 21 of the movable tail wing 2 to lock the movable tail wing 2, affected by the central shaft spring 6, the locking hole 21 of the movable tail wing 2 also plays a role in locking the locking rod 8. Therefore, when pushing the multifunctional handle 7 to release the locking between the chassis 1 and the movable tail wing 2, the locking rod 8 will not reset immediately under the locking action of the locking hole 21, that is, the movable tail wing 2 will not reset immediately. Therefore, the backrest connected to the movable tail wing 2 will not reset immediately, which will not cause an impact on the human back and affect the comfort of the user. At this time, a force needs to be applied in the opposite direction of the reset direction of the movable tail wing 2, that is, press the backrest backward to drive the movable tail wing 2 to rotate downward to release the locking of the locking hole 21 on the movable tail wing 2 to the locking rod 8, so that the locking rod 8 can be reset under the action of the first spring 9, making the whole unlocking process convenient and stable, and improving the comfort of the user when using.

[0035] As a specific solution, a lock rod mounting portion 100 is provided on the chassis 1. A through hole 101 is formed in the lock rod mounting portion 100. The through hole 101 corresponds to the position of the lock hole 21. The lock rod 8 passes through the through hole 101. The lock rod mounting portion 100 plays a positioning role in the installation of the lock rod 8 on the chassis 1, facilitating the installation of the lock rod 8 on the chassis 1. At the same time, the through hole 101 on the lock rod mounting portion 100 plays a limiting role in the movement of the lock rod 8 on the lock rod mounting portion 100, preventing the lock rod 8 from disengaging from the lock rod mounting portion 100. An annular limiting protrusion 81 is provided on the lock rod 8. Two ends of the first spring 9 respectively abut against the lock rod mounting portion 100 of the chassis 1 and one side of the limiting protrusion 81. Two ends of the second spring 10 respectively abut against the other side of the limiting protrusion 81 and the lock rod pushing portion 71. The limiting protrusion 81 divides the lock rod 8 into two parts, facilitating the installation of the first spring 9 and the second spring 10 on the lock rod 8 and enabling the first spring 9 and the second spring 10 not to interfere with each other. Moreover, the lock rod pushing portion 71 pushes the limiting protrusion 81 through the second spring 10, thereby realizing the movement of the lock rod 8 on the lock rod mounting portion 100, so that the lock rod 8 can be inserted into or disengaged from the lock hole 21 of the movable tail wing 2.

[0036] In this embodiment, two limiting grooves 711 are provided on the lock rod pushing portion 71. Corresponding elastic protrusions 102 are provided on the chassis 1. The elastic protrusions 102 are inserted into the limiting grooves 711. The locking of the multifunctional handle 7 on the chassis 1 is realized by inserting the elastic protrusions 102 on the chassis 1 into the limiting grooves 711 on the lock rod pushing portion of the lock rod 8. Its operation is simple and the locking is reliable.

[0037] In this embodiment, a spring groove 103 is formed on one side of the chassis 1. The central shaft spring 6 is placed on the spring groove 103. One end of the central shaft spring 6 abuts against the side wall of the spring groove 103, and the other end abuts against the tray shaft 5. The spring groove 103 provides a space for the installation of the central shaft spring 6 on the chassis 1. When the central shaft spring 6 resets, the tray shaft 5 will drive the movable tail wing 2 to rotate under the action of the central shaft spring 6, so as to realize the automatic reset of the tray shaft 5 and the movable tail wing 2. A partition plate 104 is provided in the middle of the spring groove 103. A central shaft through hole 105 is formed in the partition plate 104. The central shaft 4 passes through the central shaft through hole 105. Through the partition plate 104 and the central shaft through hole 105 on the partition plate 104, the connection of the central shaft 4 on the chassis 1 is more stable.

[0038] As a better implementation scheme, the central shaft springs 6 are provided on both sides of the partition plate 104 in the spring groove 103. Its setting is reasonable, and the two central shaft springs 6 can better realize the automatic reset of the tray shaft 5 and the movable tail wing 2.

[0039] In this embodiment, an explosion-proof steel plate 31 is further provided on the tray 3 to prevent the gas spring on the seat from exploding and shooting out, thus enhancing the safety of the seat during use.

[0040] In this embodiment, a central axis hole 22 and a tray axis hole 23 are provided on the movable tail fin 2. The central axis 4 passes through the central axis hole 22 and is rotatably connected to the chassis 1. The tray axis 5 passes through the tray axis hole 23 and is connected to the tray 3. The tray axis hole 23 and the backrest are respectively arranged at both ends of the movable tail fin 2, and the central axis hole 22 is located in the middle of the movable tail fin 2. The positions of the central axis hole 22 and the tray axis hole 23 are reasonably arranged, facilitating the rotation of the movable tail fin 2.

[0041] As a better solution, it further includes a chassis linkage 11, a second central axis 12, a second central axis spring 13, a second tray axis 14 and an elastic force adjusting device 15. One end of the chassis linkage 11 is rotatably installed on the chassis 1 through the second central axis 12, and the other end is connected to the tray 3 through the second tray axis 14. The second central axis spring 13 is sleeved on the second central axis 12, and both ends of the second central axis spring 13 are respectively abutted against the chassis 1 and the elastic force adjusting device 15. The elastic force adjusting device 15 is fixed on the chassis linkage 11. Through the cooperation of the chassis linkage 11 and the movable tail fin 2, they jointly play a role in supporting the tray 3, enabling the tray 3 to bear a greater weight and meet more usage requirements of users. Moreover, by adding the elastic force adjusting device 15 on the chassis linkage 11, the elastic force of the second central axis spring 13 can be adjusted. Users can adjust the second central axis spring 13 according to their own body weight. For example, users can increase the elastic force of the second central axis spring 13 through the elastic force adjusting device 15. At this time, the acting force of the second central axis spring 13 on the chassis linkage 11 is greater. Therefore, users need to apply more force to press down one end of the movable tail fin 2 in order to make the chassis linkage 11 and the tray 3 have corresponding linkages. This type of seat chassis has the advantages of simple structure, convenient operation and wide applicability, and can meet different usage requirements of users.

[0042] As a specific solution, the elastic force adjusting device 15 includes an adjusting member 16 and an operating handle 17. One end of the adjusting member 16 passes through the chassis linkage member 11 and is snapped into the operating handle 17. One end of the adjusting member 16 is provided with a helically rising inclined surface 161. One end of the second central shaft spring 13 abuts against the inclined surface 161. By driving the adjusting member 16 to rotate with the operating handle 17, the operation is simple and labor-saving, which is convenient for the user to operate. At the same time, the rotating adjusting member 16 changes the initial elastic force of the second central shaft spring 13 through the helically rising inclined surface 161. A limiting protrusion 162 is provided on the inclined surface 161. The highest point and the lowest point of the inclined surface 161 are respectively located on both sides of the limiting protrusion 162. The setting is reasonable. The position of the highest point and the lowest point on the inclined surface 161 is limited by the limiting protrusion 162, so as to determine the elastic force adjustment range of the second central shaft spring 13. Two or more clamping grooves 163 are provided on the inclined surface 161. One end of the second central shaft spring 13 is snapped into the clamping groove 163, so that the connection between the second central shaft spring 13 and the adjusting member 16 is more stable, and the second central shaft spring 13 is prevented from disengaging from the adjusting member 16.

[0043] In this embodiment, an installation portion 164 extends from one end of the adjusting member 16. The operating handle 17 is correspondingly provided with an installation groove 171. The installation portion 164 passes through the installation hole 111 on the chassis linkage member 11 and is inserted into the installation groove 171. This connection method is simple and stable, easy to implement, and convenient for the operating handle 17 to drive the adjusting member 16 to rotate. The installation portion 164 is a "convex"-shaped installation column, and the installation groove 171 is a "convex"-shaped installation groove 171. The installation column is inserted into the installation groove 171. The "convex"-shaped installation column and the "convex"-shaped installation groove 171 have a simple structure and are easy to manufacture. A fixing hole 165 is opened on the bottom surface of the installation portion 164, and a corresponding installation through hole 172 is opened on the bottom surface of the installation groove 171. The fixing hole 165 and the installation through hole 172 are connected and fixed by screws. The locking between the installation portion 164 and the installation groove 171 is realized through the screws, so as to well ensure the stable connection between the adjusting member 16 and the operating handle 17.

[0044] As a specific solution, a second central shaft hole 112 and a second tray shaft hole 113 are provided on the chassis linkage member 11. The second central shaft 12 passes through the second central shaft hole 112 and is connected to the chassis 1. The second tray shaft 14 passes through the second tray shaft hole 113 and is connected to the tray 3. The second tray shaft hole 113 and the second central shaft hole 112 are respectively arranged at both ends of the chassis linkage member 11. The positions of the second central shaft hole 112 and the second tray shaft hole 113 are set reasonably, which is convenient for the rotation of the chassis linkage member 11.

[0045] Working principle: Press one end of the movable tail fin 2 downwards, causing the movable tail fin 2 to rotate around the central axis 4, driving the movement of the tray shaft 5 located at the other end of the movable tail fin 2, and then driving one end of the tray 3 to move upwards through the tray shaft 5. At the same time, the upward movement of one end of the tray 3 drives the chassis linkage 11 to rotate around the second central axis 12 through the second tray shaft 14, causing the chassis linkage 11 to support the upward movement of the other end of the tray 3, achieving the adaptive linkage of the movable tail fin 2, the chassis linkage 11, and the tray 3.

[0046] When locking the movable tail fin 2, push the multifunctional handle 7 to drive the lock rod 8 to be inserted into the lock hole 21 of the movable tail fin 2 to achieve the locking between the chassis 1 and the movable tail fin 2. At this time, the elastic protrusion 102 on the chassis 1 is snapped into one of the limit grooves 711 of the multifunctional handle 7 to achieve the locking of the multifunctional handle on the chassis; when unlocking, push the multifunctional handle 7, causing the elastic protrusion 102 on the chassis 1 to be snapped into another limit groove 711 of the multifunctional handle 7, and then press the backrest backwards to drive the movable tail fin 2 to rotate downwards to release the locking of the lock hole 21 on the movable tail fin 2 on the lock rod 8, so that the lock rod 8 is realized under the action of the first spring 9 and the second spring 10, achieving the unlocking of the movable tail fin.

[0047] When adjusting the elastic force, rotate the operating handle 17 to drive the adjusting member 16 to rotate. At this time, the rotating adjusting member 16 changes the initial elastic force of the second central axis spring 13 through the helically rising inclined surface 161, causing the acting force of the second central axis spring 13 on the chassis linkage 11 to change, achieving the adjustment of the force for the user to press the backrest backwards.

Claims

1. An adjustable adaptive seat chassis, comprising a chassis (1), a movable tail wing (2), a tray (3), a central shaft (4), a tray shaft (5) and a central shaft spring (6). The movable tail wing (2) is rotatably mounted on the chassis (1) through the central shaft (4). The tray (3) is connected to the movable tail wing (2) through the tray shaft (5), and the tray shaft (5) is placed on the chassis (1). The central shaft spring (6) is sleeved on the central shaft (4), one end of which abuts against the chassis (1), and the other end abuts against the tray shaft (5), and is characterized in that: A multi-functional handle (7), a lock rod (8), a first spring (9) and a second spring (10) are also provided. A lock rod pushing part (71) is arranged on the multi-functional handle (7). The multi-functional handle (7) is inserted into the chassis (1) from one side of the chassis (1). The lock rod (8) is movably installed on the chassis (1). The first spring (9) and the second spring (10) are respectively sleeved on the lock rod (8). One end of the first spring (9) abuts against the chassis (1), and the other end abuts against the lock rod (8). One end of the second spring (10) abuts against the lock rod (8), and the other end abuts against the lock rod pushing part (71). A plurality of lock holes (21) are formed at one end of the movable tail fin (2), and the lock holes (21) are in the direction corresponding to the lock rod (8). A lock rod installation part (100) is arranged on the chassis (1). A through hole (101) is formed in the lock rod installation part (100), and the through hole (101) corresponds to the position of the lock hole (21). The lock rod (8) passes through the through hole (101). An annular limit protrusion (81) is arranged on the lock rod (8). Two ends of the first spring (9) respectively abut against the lock rod installation part (100) of the chassis (1) and one side of the limit protrusion (81). Two ends of the second spring (10) respectively abut against the other side of the limit protrusion (81) and the lock rod pushing part (71). Two limit grooves (711) are arranged on the lock rod pushing part (71). Corresponding elastic protrusions (102) are arranged on the chassis (1), and the elastic protrusions (102) are clamped into the limit grooves (711). A spring groove (103) is formed on one side of the chassis (1). The central axis spring (6) is placed on the spring groove (103). One end of the central axis spring (6) abuts against the side wall of the spring groove (103), and the other end abuts against the tray shaft (5). A partition plate (104) is arranged in the middle of the spring groove (103). A central axis through hole (105) is formed in the partition plate (104), and the central axis (4) passes through the central axis through hole (105). The central axis springs (6) are arranged on both sides of the partition plate (104) in the spring groove (103).

2. The adjustable adaptive seat chassis according to claim 1, characterized in that, An explosion-proof steel plate (31) is also arranged on the tray (3).

3. The adjustable adaptive seat chassis according to claim 1, wherein The upper part of the tray (3) is connected to the seat. Two ends of the movable tail fin (2) are respectively connected to the backrest and the tray (3).

4. The adjustable adaptive seat chassis according to claim 1, characterized in that, A central axis hole (22) and a tray shaft hole (23) are arranged on the movable tail fin (2). The central axis (4) passes through the central axis hole (22) and is rotatably connected to the chassis (1). The tray shaft (5) passes through the tray shaft hole (23) and is connected to the tray (3). The tray shaft hole (23) and the backrest are respectively arranged at two ends of the movable tail fin (2), and the central axis hole (22) is located in the middle of the movable tail fin (2).

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