A seat bow under type bicycle seat pad fixing device

Abstract

The application provides a seat-bow-under type bicycle saddle fixing device, and relates to the technical field of bicycles. The device comprises a U-shaped support arranged at the top of a seat tube and clamping mechanisms symmetrically arranged on both sides of the U-shaped support. The clamping mechanisms are composed of inner clamping plates and outer clamping plates. The first clamping groove and the second clamping groove on the lower part are oppositely arranged to form a ring-shaped accommodating cavity for clamping the seat bow. The upper part is lockably connected with the U-shaped support through a locking assembly composed of a locking bolt and a connecting piece, and serves as a seat cushion angle adjusting pivot. The seat bow clamping position is arranged below the first connecting part and the second connecting part as a whole, and is matched with an obliquely arranged locking channel and a V-shaped nut structure. The seat cushion can be adjusted to a lower height under the premise of ensuring clamping stability, installation space is reserved for the internal motor and electric control elements of the seat tube, the height adjusting stroke of the electric lifting seat is increased, and the convenience of assembly and disassembly is improved.

Description

Technical Field

[0001] This application relates to the field of bicycle technology, and more particularly to a bicycle seat fixing device with the seat arch positioned below the seat. Background Technology

[0002] With the development of bicycles, especially e-bikes, more and more bicycles are being equipped with power dropper seatposts, allowing riders to adjust the saddle height in real time according to road conditions or posture. Existing power dropper seatposts generally use a built-in motor, screw drive, or hydraulic auxiliary structure, and usually have a saddle securing device at the top to reliably mount the saddle to the top of the dropper post.

[0003] In existing technologies, seat cushion fixing methods mainly fall into two categories: One type is an upper and lower clamping structure, in which clamping blocks are set on the upper and lower sides of the seat bow, and the upper and lower clamping blocks are locked relative to each other by bolts to clamp the seat bow. Another type is the horizontal clamping structure, in which the clamping blocks are set horizontally and the seat bow is clamped by bolts on both sides.

[0004] The former has a stable structure and is easy to adjust, but its upper and lower clamps occupy a large vertical space. When used in combination with an electric lifting mechanism, it will significantly compress the installation space of modules such as motors, reduction gears, and control circuits. The latter has a relatively compact structure, but because the clamps and bolts are located under the seat and extend laterally, it will raise the lowest position of the seat, resulting in a higher riding posture and a shortened effective lifting stroke.

[0005] Especially in wireless automatic height-adjustable seats, the overall space is extremely limited because the interior needs to accommodate the motor, transmission screw, drive battery, and wireless communication module. If the upper and lower clamps or horizontal clamps are used, it will not only occupy the vertical space at the top of the lifting mechanism, forcing the seat cushion to be installed at a higher height, but may also interfere with internal components such as the motor housing and control board, affecting the layout and heat dissipation performance of the lifting mechanism, and even causing problems such as insufficient structural strength or obstructed lifting.

[0006] Therefore, there is an urgent need for a fixing device that is more compact, occupies less space, and does not affect the minimum height of the seat cushion, so as to achieve stable clamping and angle adjustment in a limited space, thereby meeting the structural integration requirements of wireless automatic lifting seats. Utility Model Content

[0007] To address the aforementioned issues, this application provides a bicycle saddle fixing device with an under-saddle design, offering a more compact structure, smaller footprint, and without affecting the minimum height of the saddle.

[0008] The technical solution of the under-arch bicycle seat fixing device provided in this application is as follows: A bicycle saddle fixing device with under-arm mounting includes: A U-shaped bracket is installed at the top of the seat post with its opening facing the seat cushion; A clamping mechanism is provided on each side of the U-shaped bracket for clamping the seat bow; The clamping mechanism includes: An inner clamping plate located on one side of the U-shaped bracket and an outer clamping plate located outside the inner clamping plate, wherein the lower part of the inner clamping plate is provided with a first slot and the upper part is provided with a first connecting part, and the lower part of the outer clamping plate is provided with a second slot opposite to the first slot and the upper part is provided with a second connecting part; A connecting assembly connects the inner clamping plate to the outer clamping plate, so that the first slot and the second slot form an encircling receiving cavity that matches the outer diameter of the seat bow, in order to clamp the seat bow; A locking component is disposed on the upper part of the outer clamping plate for locking or unlocking the connection between the first connecting part, the second connecting part and the U-shaped bracket.

[0009] Furthermore, the locking assembly includes a locking bolt, a connector, and a connecting boss disposed on the inner side of the first connecting portion. The first connecting part has a first locking hole that passes through the connecting boss, and the second connecting part has a second locking hole. The first locking hole and the second locking hole are coaxially arranged and form a locking channel through which the threaded section of the locking bolt passes. Both wings of the U-shaped bracket have a third locking hole through which the connecting boss passes. The connector is located between the two wings of the U-shaped bracket, and its side is provided with a locking thread hole for threaded connection with the locking bolt. The locking bolt passes through the locking channel and is threadedly connected to the locking thread hole on the connector, so that the first connecting part and the second connecting part are clamped and locked on the U-shaped bracket.

[0010] Furthermore, the connecting boss is a frustum-shaped structure that tapers from the outside to the inside, and the inner wall of the third locking hole tapers from the outside to the inside to form a frustum-shaped surface with the same taper as the outer frustum-shaped surface of the connecting boss, so that the outer frustum-shaped surface of the connecting boss and the inner frustum-shaped surface of the third locking hole fit together in the locked state, and the major diameter of the third locking hole is smaller than the major diameter of the connecting boss.

[0011] Furthermore, the locking bolts on both sets of locking components share the same connector, and the connector has locking threaded holes on both sides.

[0012] Furthermore, the locking channel is inclined upwards along the direction from the outside to the inside, and the locking threaded holes on both sides of the connector are coaxial with the locking channels on both sides, so that the connector as a whole forms a V-shaped nut structure.

[0013] Furthermore, a locking groove is provided on the outer side of the second connecting part, and the bottom surface of the locking groove is perpendicular to the locking channel so that the bolt head of the locking bolt can fit into it.

[0014] Furthermore, a first inclined surface is provided on the outer side of the first connecting part, and the first inclined surface slopes inward from bottom to top. A second inclined surface parallel to the first inclined surface is provided on the inner side of the second connecting part, so that when the inner clamping plate and the outer clamping plate are locked, the second inclined surface engages with the first inclined surface to generate a downward component force pointing towards the inner clamping plate.

[0015] Furthermore, the first card slot and the second card slot are offset vertically, with the second card slot located below the first card slot.

[0016] Furthermore, the connecting assembly includes a connecting bolt, a connecting threaded hole, and a connecting through hole. The connecting threaded hole is located on the inner clamping plate and below the first slot, and the connecting through hole is located on the outer clamping plate and below the second slot. The threaded section of the connecting bolt passes through the connecting through hole and engages with the connecting threaded hole.

[0017] Furthermore, the connecting through hole is an oblong hole with its long axis arranged in the vertical direction.

[0018] In summary, this application includes at least one of the following beneficial technical effects: 1. By setting a first slot and a second slot below the first and second connecting parts of the inner and outer clamping plates, the clamping position of the clamp and seat arch is moved down to below the pivot. On the one hand, when the seat is adjusted to the lowest position, the seat can be lowered, effectively increasing the height adjustment range of the electric lift seat. On the other hand, in conjunction with the locking bolts arranged from bottom to top, interference between the seat and the disassembly tools is avoided after the pivot is moved up, making the disassembly and assembly operations smoother. At the same time, the lower clamp frees up a lot of effective space above the seat arch and inside the seat tube, which is convenient for arranging the motor, transmission and control components, thereby improving space utilization without increasing the overall vehicle size. 2. By using the inner and outer clamping plates to cooperate with the first and second slots and the relatively inclined mating surfaces, the seat bow is clamped in a ring-like manner and a downward pressing force is superimposed when the locking bolt is tightened. This significantly improves the clamping stability of the seat bow and avoids slippage or angular loosening of the seat bow during riding impact and seat post lifting, ensuring the reliable posture of the seat. 3. By integrating the locking bolt, connecting boss, locking hole, and V-nut into a single angle adjustment and locking mechanism, only a slight loosening of the locking bolt is needed during use. This allows the connecting boss to disengage from its limit position, thereby rotating the entire connecting mechanism to adjust the seat angle. After adjustment, tightening the bolt again ensures reliable repositioning. This solves the problem of multiple tightening and loosening points and cumbersome operation required for seat angle adjustment in existing technologies, achieving continuous and convenient seat angle adjustment with reliable locking. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram illustrating the usage state of an embodiment of this application.

[0021] Figure 2 This is a schematic diagram of the overall structure of an embodiment of this application.

[0022] Figure 3 This is an exploded structural diagram of an embodiment of this application.

[0023] Reference numerals: 1. Seat cushion; 11. Seat arch; 2. Seat tube; 3. U-shaped bracket; 31. Third locking hole; 4. Clamping mechanism; 41. Inner clamping plate; 411. First connecting part; 412. First slot; 413. First locking hole; 414. First inclined surface; 42. Outer clamping plate; 421. Second connecting part; 422. Second slot; 423. Second locking hole; 424. Second inclined surface; 425. Locking groove; 43. Locking assembly; 431. Locking bolt; 432. Connecting boss; 433. V-nut; 44. Connecting assembly; 441. Connecting bolt; 442. Connecting threaded hole; 443. Connecting through hole. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0025] This application discloses a mounting device for a bicycle seat cushion 1 with the seat arch 11 positioned below it. Specifically, as shown in the embodiments... Figure 1As shown, the seat cushion 1 fixing device is installed on the top of the seat tube 2 to fix the seat cushion 1 to the seat tube 2. Below the seat cushion 1 is a seat arch 11 extending in the left-right direction, and the seat arch 11 is arranged symmetrically from left to right. In this embodiment, the clamp structure of the seat cushion 1 fixing device is located below the seat arch 11, allowing the area above the seat arch 11 to be as open as possible, so that electric lifting components such as motors, transmission mechanisms, and control circuits can be arranged inside the seat tube 2. This balances seat cushion 1 height adjustment and structural compactness within a limited structural space.

[0026] Specifically, such as Figure 2 and Figure 3 As shown, the under-mount bicycle saddle 1 fixing device for the seat arch 11 includes a U-shaped bracket 3 located at the top of the seat post 2 and clamping mechanisms 4 symmetrically arranged on both sides of the U-shaped bracket 3. The U-shaped bracket 3 has an overall U-shaped structure with its opening facing upwards. Its bottom is fixedly connected to the top of the seat post 2, and its two sides extend upwards to form a pair of spaced-apart wing plates. Each wing plate has a third locking hole 31 that runs through it in the left-right direction, which is used to cooperate with the locking assembly 43 described later to lock the clamping mechanism 4 and adjust its angle. The U-shaped bracket 3 provides a stable mounting base for the saddle 1 fixing device and the seat post 2, providing reliable support for the subsequent clamping and angle locking of the seat arch 11.

[0027] Furthermore, each clamping mechanism 4 includes an inner clamping plate 41 and an outer clamping plate 42 arranged on the corresponding side of the U-shaped bracket 3. The inner clamping plate 41 is located on the side of the U-shaped bracket 3 closer to the seat arch 11, and the outer clamping plate 42 is located on the side of the inner clamping plate 41 away from the U-shaped bracket 3, and the two are arranged opposite to each other. The upper part of the inner clamping plate 41 integrally forms a first connecting part 411, and the lower part integrally forms a first slot 412; the upper part of the outer clamping plate 42 integrally forms a second connecting part 421, and the lower part integrally forms a second slot 422 opposite to the first slot 412. The inner clamping plate 41 and the outer clamping plate 42 are connected by a connecting component 44, so that the first slot 412 and the second slot 422 together form a ring-shaped receiving cavity. The cross-section of the receiving cavity is preferably an arc-shaped or approximately circular arc-shaped structure that matches the outer diameter of the seat arch 11. Thus, in the locked state, the seat arch 11 can be circumferentially clamped, ensuring that the seat arch 11 is not prone to slippage during riding impact and lifting.

[0028] Based on the above, preferably, the first slot 412 and the second slot 422 are staggered in the vertical direction, and the second slot 422 is located below the first slot 412. Specifically, the first slot 412 at the lower part of the inner clamping plate 41 is arranged slightly higher on the side near the first connecting part 411, and the second slot 422 at the lower part of the outer clamping plate 42 is arranged relatively slightly lower, forming a height difference in the vertical direction. This makes the encircling cavity formed by the first slot 412 and the second slot 422 located entirely below the first connecting part 411 and the second connecting part 421. Thus, while ensuring reliable clamping of the seat arch 11, the clamping position of the seat arch 11 is moved down to below the pivot of the clamping mechanism 4. On the one hand, this allows the seat cushion 1 to be closer to the top of the seat tube 2 when adjusted to the lowest position, thereby effectively increasing the height adjustment range of the electric lifting seat. On the other hand, it also frees up more effective space above the seat arch 11 and inside the seat tube 2, facilitating the installation of the motor, reduction mechanism, and control components, and improving the overall space utilization of the vehicle.

[0029] To facilitate the assembly and disassembly of the inner clamping plate 41 and the outer clamping plate 42, a connecting assembly 44 is provided in the clamping mechanism 4. Specifically, as shown in... Figure 3 As shown, the connecting assembly 44 includes a connecting bolt 441, a connecting threaded hole 442 provided on the inner clamping plate 41, and a connecting through hole 443 provided on the outer clamping plate 42. The connecting threaded hole 442 is located below the first slot 412 and is opened in the left-right direction; the connecting through hole 443 is also located below the second slot 422.

[0030] During assembly, the connecting bolt 441 passes through the connecting through hole 443 from the outside and engages with the connecting threaded hole 442. By tightening the connecting bolt 441, the inner clamping plate 41 and the outer clamping plate 42 can be reliably tightened.

[0031] For locking and angle adjustment, the clamping mechanism 4 is equipped with a locking component 43. Specifically, the locking component 43 includes a through-hole locking bolt 431, a connecting boss 432 arranged inside the first connecting part 411, and a connector located between the two wings of the U-shaped bracket 3. The first connecting part 411 has a first locking hole 413 for accommodating the connecting boss 432, and the second connecting part 421 has a second locking hole 423. The first locking hole 413 and the second locking hole 423 are arranged coaxially from the outside to the inside, forming a locking channel through which the threaded section of the locking bolt 431 passes. The two wings of the U-shaped bracket 3 each have a third locking hole 31 through which the connecting boss 432 passes. The connector is located between the two wings of the U-shaped bracket 3, and each side of it has a locking threaded hole, which is coaxially arranged with the locking channel on the corresponding side. During assembly, the locking bolt 431 passes through the second locking hole 423 and the first locking hole 413 from the outside in sequence, and is threadedly connected to the locking threaded hole on the connector. After tightening, the first connecting part 411 and the second connecting part 421 can be firmly clamped on the corresponding wing plate of the U-shaped bracket 3, thereby completing the locking connection between the clamping mechanism 4 and the U-shaped bracket 3.

[0032] Furthermore, the connecting boss 432 is preferably a frustum-shaped structure that tapers from the outside to the inside. The inner wall of the third locking hole 31 tapers from the outside to the inside, forming a frustum surface with the same taper as the outer frustum surface of the connecting boss 432. The large-diameter end of the third locking hole faces outward and its large-diameter dimension is smaller than that of the connecting boss 432. In the locked state, the small-diameter end of the connecting boss 432 extends into the third locking hole 31 and fits against the hole wall of the third locking hole 31. When the locking bolt 431 is tightened further, the large-diameter end abuts against the inner side of the first connecting part 411. Through the wedge-tight fit between the outer surface of the frustum and the third locking hole 31, the radial clearance in the locking channel can be effectively reduced, improving the positioning accuracy and anti-sway capability of the clamping mechanism 4 relative to the U-shaped bracket 3. Therefore, when the seat cushion 1 is subjected to riding impact or the seat post 2 is frequently raised and lowered, the clamping mechanism 4 will not shake around the locking bolt 431, thereby ensuring the stability of the seat cushion 1.

[0033] Preferably, the locking bolts 431 of the two clamping mechanisms 4 share the same connector, that is, both sides of the connector are provided with locking threaded holes, and the two locking threaded holes are respectively coaxially arranged with the locking channels on both sides, so that the connector as a whole forms a V-shaped nut 433 structure. Specifically, the locking channels on both sides are arranged upwardly from the outside to the inside, so that the two locking bolts 431 form a V-shaped angle with each other. When the locking bolts 431 are tightened, the V-shaped nut 433 applies tension force to the two clamping mechanisms 4 in two different directions at the same time. This not only makes the inner clamping plate 41 and the outer clamping plate 42 reliably fit against the two wings of the U-shaped bracket 3, but also uses the inclined arrangement of the locking channels to decompose part of the tension force into a downward component force, further lowering the position of the entire clamping mechanism 4. Thus, while satisfying the locking reliability, the clamping area of ​​the clamp and seat arch 11 is moved down as a whole, so that the seat cushion 1 is closer to the top of the seat post 2 when it is at its lowest position. This is beneficial to obtain a lower riding posture and a larger height adjustment range under the same seat post 2 stroke.

[0034] To facilitate user assembly and disassembly, a locking groove 425 is preferably provided on the outer side of the second connecting part 421. The bottom surface of the locking groove 425 is perpendicular to the axis of the locking channel and is used to accommodate the bolt head of the locking bolt 431. The locking groove 425 can be a flat-bottomed groove or a stepped groove structure with slightly rounded corners. When the locking bolt 431 is tightened, the bolt head fits against the bottom surface of the locking groove 425 over a large area, which can effectively prevent the locking bolt 431 from deflecting during the tightening process and ensure that the tightening force is transmitted along the direction of the locking channel. At the same time, the locking groove 425 allows the bolt head to be partially embedded in the second connecting part 421, which not only reduces the exposed height of the bolt and the risk of interference with the rider's legs and external obstacles, but also makes the overall structure more compact and aesthetically pleasing.

[0035] In this embodiment, the locking component 43 serves the dual functions of pivot and locking. During use, the user only needs to slightly loosen the locking bolts 431 on both sides to release the wedge-tight fit between the connecting boss 432 and the third locking hole 31. The clamping mechanism 4 can then rotate relative to the U-shaped bracket 3 in the circumferential direction of the connecting boss 432 axis, thereby driving the seat arch 11 and seat cushion 1 to rotate around the locking bolts 431 to achieve angle adjustment. After the seat cushion 1 is adjusted to the desired comfortable angle, the locking bolts 431 are tightened again, the connecting boss 432 is pressed back into the third locking hole 31, and the clamping mechanisms 4 on both sides are simultaneously clamped by the V-nut 433, thus locking the angle of the seat cushion 1. Therefore, compared to the traditional structure that requires loosening multiple bolts or disassembling parts simultaneously, this embodiment only requires operating two locking bolts 431 to achieve continuous adjustment and reliable locking of the seat cushion 1 angle, significantly improving adjustment efficiency and ease of use.

[0036] In addition, to ensure a stable clamping force between the inner clamping plate 41 and the outer clamping plate 42 in the locked state, the connecting portion of the inner clamping plate 41 and the outer clamping plate 42 is provided with a mutually cooperating inclined surface structure. Specifically, the outer side of the first connecting portion 411 forms a first inclined surface 414 that slopes inward from bottom to top, and the inner side of the second connecting portion 421 forms a second inclined surface 424 that is parallel to the first inclined surface 414. When the locking assembly 43 drives the inner clamping plate 41 and the outer clamping plate 42 to lock towards the U-shaped bracket 3, the second inclined surface 424 slides along the first inclined surface 414 and fits against it, thereby generating a downward component force towards the inner clamping plate 41. This downward component force is transmitted to the lower area where the first slot 412 and the second slot 422 are located, which is equivalent to applying an additional clamping force to the seat bow 11. This inclined engagement significantly improves the clamping stability of the seat arch 11 without adding extra parts, preventing the seat arch 11 from loosening or the seat cushion 1 from shifting angle during vigorous riding or frequent lifting and lowering.

[0037] Furthermore, the hole shape of the connecting through hole 443 is preferably an oblong hole with its long axis arranged in the vertical direction. Thus, during the clamping or loosening process of the first inclined surface 414 and the second inclined surface 424, the outer clamping plate 42, guided and constrained by the connecting bolt 441 along the long axis of the connecting through hole 443, can adaptably move relative to the inner clamping plate 41 in the vertical direction. This allows the first slot 412 and the second slot 422 to reliably clamp the seat bow 11 within different clamping strokes. Moreover, when the seat bow 11 has different cross-sectional shapes such as a circular or elliptical cross-section, the vertical oblong connecting through hole 443 allows the outer clamping plate 42 to automatically adjust its clamping height, thereby reducing interference between the seat bow 11 and the bottom surface of the slot, improving clamping fit and force uniformity, and enhancing adaptability.

[0038] In summary, by setting the first slot 412 and the second slot 422 with vertical offset below the connection between the inner clamping plate 41 and the outer clamping plate 42, and cooperating with the inclined locking channel and the V-shaped nut 433 structure, the overall downward movement of the clamping area of ​​the clamping hoop and the seat arch 11 is achieved. While ensuring the clamping stability of the seat arch 11, the seat cushion 1 can be adjusted to a lower position, effectively increasing the height adjustment range of the electric lifting seat, and reserving more space for installing motors and control components for the wireless automatic lifting seat with limited space. At the same time, by utilizing the meshing of the first inclined surface 414 and the second inclined surface 424 and the wedge-tight fit between the connecting boss 432 and the third locking hole 31, the locking strength and positioning accuracy between the clamping mechanism 4 and the U-shaped bracket 3 are further improved, so that the seat cushion 1 can still maintain a stable posture under complex working conditions. It has the comprehensive benefits of compact structure, convenient adjustment and reliable locking.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A bicycle seat fixing device with a lower seat arch, characterized in that, include: A U-shaped bracket is installed at the top of the seat post with its opening facing the seat cushion; A clamping mechanism is provided on each side of the U-shaped bracket for clamping the seat bow; The clamping mechanism includes: An inner clamping plate located on one side of the U-shaped bracket and an outer clamping plate located outside the inner clamping plate, wherein the lower part of the inner clamping plate is provided with a first slot and the upper part is provided with a first connecting part, and the lower part of the outer clamping plate is provided with a second slot opposite to the first slot and the upper part is provided with a second connecting part; A connecting assembly connects the inner clamping plate to the outer clamping plate, so that the first slot and the second slot form an encircling receiving cavity that matches the outer diameter of the seat bow, in order to clamp the seat bow; A locking component is disposed on the upper part of the outer clamping plate for locking or unlocking the connection between the first connecting part, the second connecting part and the U-shaped bracket.

2. The under-seat bicycle saddle fixing device according to claim 1, characterized in that, The locking assembly includes a locking bolt, a connector, and a connecting boss disposed on the inner side of the first connecting portion. The first connecting part has a first locking hole that passes through the connecting boss, and the second connecting part has a second locking hole. The first locking hole and the second locking hole are coaxially arranged and form a locking channel through which the threaded section of the locking bolt passes. Both wings of the U-shaped bracket have a third locking hole through which the connecting boss passes. The connector is located between the two wings of the U-shaped bracket, and its side is provided with a locking thread hole for threaded connection with the locking bolt. The locking bolt passes through the locking channel and is threadedly connected to the locking thread hole on the connector, so that the first connecting part and the second connecting part are clamped and locked on the U-shaped bracket.

3. The under-arch bicycle seat fixing device according to claim 2, characterized in that, The connecting boss is a frustum-shaped structure that tapers from the outside to the inside. The inner wall of the third locking hole tapers from the outside to the inside and forms a frustum-shaped surface with the same taper as the outer frustum-shaped surface of the connecting boss. This allows the outer frustum-shaped surface of the connecting boss and the inner frustum-shaped surface of the third locking hole to fit together in the locked state. The major diameter of the third locking hole is smaller than the major diameter of the connecting boss.

4. The under-arch bicycle seat fixing device according to claim 3, characterized in that, The locking bolts on both sets of locking components share the same connector, and the connector has locking threaded holes on both sides.

5. A bicycle seat fixing device with under-arch design according to claim 4, characterized in that, The locking channel is inclined upward along the direction from the outside to the inside, and the locking threaded holes on both sides of the connector are coaxial with the locking channel on both sides, so that the connector as a whole forms a V-shaped nut structure.

6. A bicycle seat fixing device with under-arch design according to claim 5, characterized in that, A locking groove is provided on the outer side of the second connecting part, and the bottom surface of the locking groove is perpendicular to the locking channel so that the bolt head of the locking bolt can fit into it.

7. A bicycle seat fixing device with under-arch design according to claim 2, characterized in that, The outer side of the first connecting part is provided with a first inclined surface, which slopes inward from bottom to top. The inner side of the second connecting part is provided with a second inclined surface parallel to the first inclined surface, so that when the inner clamping plate and the outer clamping plate are locked, the second inclined surface engages with the first inclined surface to generate a downward component force pointing towards the inner clamping plate.

8. A bicycle seat fixing device with under-arch design according to claim 7, characterized in that, The first card slot and the second card slot are offset vertically, with the second card slot located below the first card slot.

9. A bicycle seat fixing device with under-arch design according to claim 1, characterized in that, The connecting assembly includes a connecting bolt, a connecting threaded hole, and a connecting through hole. The connecting threaded hole is located on the inner clamping plate and below the first slot, and the connecting through hole is located on the outer clamping plate and below the second slot. The threaded section of the connecting bolt passes through the connecting through hole and engages with the connecting threaded hole.

10. A bicycle seat fixing device with a lower seat arch as described in claim 9, characterized in that, The connecting through hole is an oblong hole with its long axis set in the vertical direction.

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