Lightweight, three-stage folding bicycle with multi-speed interlocking mechanism

Abstract

We offer a lightweight, three-stage folding bicycle with a multi-speed linked structure. [Solution] The bicycle comprises a frame body, a front upright tube 4, a rear fork 6, and a wheelset. The frame employs a three-stage interlocking folding mechanism, including a central folding section of the main frame, a front upright tube folding section, and a rear fork folding section, and the folding operation is performed smoothly without interference. The central folding section of the main frame is located in the middle of the main frame and includes a central folding rotation axis 2 and a central folding rotation axis lock screw 3. The central folding section of the main frame, the front upright tube folding section, and the rear fork folding section form spatial interlocking through the cooperation of structural positional restrictions and motion trajectories, so that when any one folding section operates, the other folding sections retract or enter the folding path synchronously, thereby achieving continuous folding without interference. After folding, both wheels are close together and the upright tubes are in close contact with the main frame, resulting in a compact volume.

Description

[[Technical Field]]

[0001] The present invention relates to the technical field of bicycle manufacturing, in particular to the technical field of structural design of lightweight folding bicycles for urban commuting and portable storage, and specifically relates to a lightweight three-stage folding multi-stage linked structure bicycle. [[Background Art]]

[0002] In recent years, with the continuous progress of urbanization in our country, the urban population and the number of car ownership have been increasing, and the problem of road traffic congestion in urban areas has become increasingly prominent. Short-distance commuting, transit travel, and lightweight eco-friendly means of transportation have become important components of urban transportation systems. At the same time, with the continuous improvement of public transportation networks such as subways, buses, and ride-sharing, residents are putting forward higher requirements for the portability, flexibility, and usability of transportation means. Folding bicycles, with the remarkable advantages of small volume, easy storage, capability of being carried onto public transport such as subways and buses, and taking up little space for storage at home, have been gradually recognized as a mainstream option for urban residents for short-distance travel, leisure activities, and transit transfer, and have been widely popularized and applied in scenarios such as daily commuting, movement on campus, and use in tourist attractions.

[0003] At present, most folding bicycles commonly found on the market adopt a single folding joint or a split simple folding structure, which mainly includes typical forms such as hinge folding at the center of the frame, vertical folding of the seat tube, lateral folding of the handlebar, and expansion and contraction of the seat post. Such a structure realizes the basic function of reducing the volume of the bicycle within a certain range to enable portable storage, and can meet the basic travel needs of general users. However, as users' requirements for folding efficiency, portability convenience, riding comfort, and structural durability continue to increase, many insurmountable defects of the existing folding bicycle technology have been exposed in actual use, and it can no longer meet the travel needs of high quality, high efficiency, and high stability. The specific problems are as follows.

[0004] Firstly, the folding procedure is complicated and difficult to operate, making it impossible to fold and unfold quickly. Conventional folding bicycles typically require the sequential release of multiple mechanisms, such as frame locks, tube locks, and handlebar locks, and must be operated in a fixed sequence. The numerous steps and cumbersome operation make one-handed operation difficult, especially for the elderly, women, and users carrying luggage. Some models also require manual adjustment of wheel positions and cable management during the folding process, often taking tens of seconds or more to complete a full fold, making them unsuitable for emergency travel, quick storage, and efficient transfers.

[0005] Secondly, the folded volume is large and the shape is not compact, resulting in insufficient portability and storage. Many existing folding structures only allow for partial angle reversal, and after folding, the front and rear sections of the frame do not fit together tightly. As a result, the distance between the wheels is large, the overall external dimensions are wide, and the space occupied horizontally and vertically is also large, making it difficult to store in narrow spaces such as small trunks, storage lockers, or under desks. Some models cannot stand on their own after folding and require leaning against something for support, making them prone to bumping into things when carrying and inconvenient to drag, significantly negatively impacting the user's carrying experience and storage efficiency at home.

[0006] Thirdly, the connection rigidity of the folding parts is insufficient, resulting in poor driving stability and a safety risk. To achieve the folding function, existing structures generally incorporate hinges or split interfaces at the main load-bearing parts of the frame, which compromises the overall continuity of the frame. In scenarios such as long-distance riding, riding on rough roads, and riding under heavy loads, problems such as increased gaps in the folding joints, loosening of locks, and deformation of the joints are likely to occur. This results in noticeable phenomena such as the handlebars shaking while riding, the frame becoming softer, and a decrease in the efficiency of force transmission. At high speeds and during sharp turns, stability is greatly reduced, affecting the riding feel and potentially leading to safety accidents due to joint failure.

[0007] Fourthly, the cable layout is inadequate, making it prone to tension, wear, and entanglement during the folding process. The control cables of folding bicycles, such as brake cables, gear cables, and shift cables, are mostly exposed and lack any follow-through or cushioning structures. During the repeated folding and unfolding of the frame, tubes, and handlebars, the cables are repeatedly bent, stretched, and compressed due to the rotation of the joints. Over time, this can easily lead to problems such as wear of the outer sheath, loosening of the internal cables, and malfunction. In mild cases, this can reduce the responsiveness of the brakes and gears, while in severe cases, it can lead to cable breakage or complete loss of control, directly threatening riding safety. At the same time, exposed cables are prone to getting caught on foreign objects, further increasing the risk of failure.

[0008] Fifth, it is difficult to balance the versatility and durability of the structure, resulting in high maintenance costs. Many existing folding structures involve complex hinges combined with multiple sets of springs, latches, and pins, resulting in a large number of parts and high assembly precision requirements. This makes them prone to wear, rust, and malfunctions over time, leading to insufficient locking or uneven folding. Furthermore, many structures lack modular design and standardized interfaces, making repairs and parts replacement difficult and resulting in high user operating and maintenance costs.

[0009] Based on the above, existing folding bicycle structures suffer from a series of technical deficiencies, including complicated folding procedures, large size after folding, insufficient structural rigidity, poor riding stability, and cable wear. Therefore, it is difficult to simultaneously meet comprehensive user needs such as quick folding, compact storage, high strength and rigidity, and safety and durability. [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] In light of this, the objective of the present invention is to provide a lightweight, three-stage folding bicycle with a multi-stage interlocking structure. [Means for solving the problem]

[0011] Unlike conventional single-hinge or multi-stage folding structures, this invention utilizes a three-stage spatially interlocking folding structure to achieve a continuous folding path that does not require a fixed folding sequence. The three-stage interlocking folding frame, lightweight high-carbon steel frame, concealed cable guide, and quick folding lock system overcome the drawbacks of conventional technologies, such as the complexity of the folding procedure, the large size after folding, insufficient structural rigidity, cable tension and wear, and excessive overall vehicle weight. This simplifies the folding operation flow, reduces the number of folding steps, enables quick folding and unfolding, and lowers the difficulty of operation. The folding structure design is optimized to minimize the vehicle's volume after folding, and the front and rear wheels are stacked parallel to each other, creating a flattened overall shape that improves storage portability. The structural rigidity and torsional strength of the frame after multi-stage folding are increased, reducing vibration and noise during driving, and ensuring driving stability and safety. By adopting a concealed cable routing and guide structure, the cables are prevented from being pulled or worn during the folding process, improving the service life and functional reliability of the cables. Optimized material selection and frame structure design achieve a balance between lightweight and high strength, reducing the overall weight of the vehicle while ensuring sufficient load-bearing capacity and impact resistance.

[0012] This invention provides a lightweight, three-stage folding bicycle with a multi-stage interlocking structure, comprising a frame body, a front riser assembly, a rear fork assembly, and a wheelset. The frame body is provided with a three-stage multi-stage interlocking folding structure, which includes a main frame central folding section, a front riser folding section, and a rear fork folding section arranged sequentially from front to rear. The main frame central folding section, the front riser folding section, and the rear fork folding section are each connected to the frame body via a pivoting connection structure, and the interlocking structure is formed by the cooperation of spatial positional relationships and motion trajectories, with the three folding nodes working together to form a continuous and interference-free folding path. The aforementioned main frame central folding section, front riser folding section, and rear fork folding section form spatial linkage through the cooperation of structural positional restrictions and motion trajectories. When any one folding section operates, the other folding sections retract or move synchronously into their corresponding folding paths. The motion trajectories of the main frame central folding section, front riser folding section, and rear fork folding section are all located within the same folding space defined by the chassis body, and by spatial positional restrictions, they form folding paths that do not interfere with each other, thereby realizing a continuous and structurally interference-free folding process.

[0013] The aforementioned three-stage multi-stage interlocking folding structure has no constraints on a fixed folding order, and each folding section can complete its folding operation independently. Any folding section can perform the folding operation as the starting folding section, and when any folding section performs the folding operation, the other folding sections enter the corresponding folding path through structural retraction or synchronous movement, thereby forming a continuous and structurally interference-free folding process. After folding is complete, the front and rear wheels of the wheelset come into close proximity to each other, forming an overlapping or partially overlapping structure, and the front riser tubes are tightly attached to the top of the main frame, creating a compact storage state.

[0014] Specifically, the structural positioning is controlled by a folding lock system, which includes a rotary central folding lock mechanism, a press-type vertical tube folding lock mechanism, and a rear fork folding positioning structure. All locking mechanisms can be operated quickly without the need for tools, enabling rapid folding and unfolding of the entire vehicle.

[0015] Preferably, the chassis body, front forks, front risers, and rear forks are all made of metal or composite materials (e.g., high-carbon steel, aluminum alloy, or carbon fiber composite material) and have high strength, impact resistance, and fatigue resistance. The cross-section of the high-carbon steel frame is optimized for mechanical cross-sectional shape, and the main load-bearing parts are thickened, while the non-load-bearing parts are given a lightweight structure with cutouts, thereby significantly reducing the overall weight of the vehicle, achieving both lightness and high rigidity, and realizing a balance between weight and strength. The folding lock system employs a tool-free, quick-operation structure (operable with one hand without tools), and the folding and unfolding of the entire vehicle can be completed within a few seconds, greatly improving ease of use. After folding is complete, the entire vehicle takes on a flat and compact form, the front and rear wheels are close together, and the front risers are tightly attached to the main frame, minimizing the storage volume.

[0016] This invention features a three-stage, multi-stage interlocking folding structure in which the main frame, front riser, and rear fork can fold synchronously and in conjunction. This eliminates the need to follow a strict fixed folding sequence, resulting in smooth operation without interference in the folding order and enabling rapid folding. The three-stage folding structure forms a stable structure that restrains itself after folding is complete, allowing it to maintain the folded state without the need for additional fixing parts.

[0017] Furthermore, the central folding section of the main frame is equipped with a central folding rotation axis and a rotary central folding lock mechanism, and is foldable in the horizontal plane within a range of 0° to 135°, with the front wheels converging toward the inside of the chassis after folding. After folding, the front and rear wheels are close together, the front uprights are in close contact with the main frame, and the whole takes on a flat and compact form, resulting in a tight folded form and minimizing storage volume. The front upright folding section is equipped with a quick-locking folding joint mechanism, and the front upright folding section is connected to the chassis via the folding joint mechanism, and when folded, the front uprights rotate downward and reverse to be in close contact with the top of the main frame of the chassis, reducing the overall folded height of the vehicle. The rear fork folding section employs a folding rear fork structure, in which the rear wheel rotates forward and reverses when folded, moving to an intermediate position on the chassis, forming a structure that is parallel to or partially overlaps with the front wheel, thereby reducing the folded volume to the maximum extent possible.

[0018] Furthermore, the folding joint mechanism of the front riser section is equipped with a quick-lock structure and a positioning structure, ensuring that the front riser stably adheres to the upper part of the main frame after folding, and that it is securely locked after unfolding to maintain stable support.

[0019] Furthermore, the central folding pivot is equipped with a central folding pivot lock screw, which allows the main frame to be folded by loosening the lock screw, and after locking, the rigidity and stability of the main frame are ensured.

[0020] Furthermore, the folding angle of the central folding rotation axis includes three positions: 45°, 90°, and 135°, of which 45° and 90° are intermediate positions, and 135° is the fully folded position. The folding operation is smooth and free from malfunctions or structural interference.

[0021] Specifically, the motion trajectory of the rear fork folding section is located within the folding space formed by the central folding section of the main frame, and the front riser folding section is located above the main frame after folding, forming a close-fitting structure with the main frame, and after the entire vehicle is folded, the front and rear wheels are stacked together and a compact structure is formed in which the risers are stored above the main frame. The position between each folding angle position of the central folding rotation axis can be restricted by a positioning structure.

[0022] Furthermore, the rear fork folding portion is connected to the main frame via a folding connection structure, and when folded, the rear wheels move toward the middle of the frame along a predetermined trajectory, forming a structure in which they are parallel to or partially overlapping with the front wheels.

[0023] Furthermore, the rear fork folding portion is equipped with a positioning engagement structure, and after the rear fork folding portion reaches the folded position, positioning and locking are achieved by engagement, locking, or structural interference, and locking and engagement are also possible after unfolding, ensuring the strength of the rear fork.

[0024] Furthermore, the rear fork assembly is equipped with auxiliary rollers, which are used to support the entire vehicle in the folded state and to enable dragging, and in the folded state, it can be dragged via the auxiliary rollers, improving portability.

[0025] Further, the lightweight three-fold multi-stage interlocking bicycle further comprises a cable guide structure, wherein the cable guide structure is provided inside or on a side of the main frame body; preferably, a curved guide structure and an expansion allowance are provided at the folding joint portion to prevent the cable from being excessively pulled or interfered during the folding process. A brake cable and a speed change cable are routed along the inside or the side of the main frame body via fixing rings and guide members, so that an orderly concealed cable guide is realized, phenomena such as pulling and interference during the folding process are prevented, and the cable will not be excessively bent, pulled or worn during the folding process. The cable guide structure is provided with an arc-shaped guide groove at the folding joint portion, and an expansion allowance for the cable is ensured, so that the bending radius of the cable is reasonably guaranteed, and the service life is prolonged.

[0026] Further, a locking screw is provided on the central folding rotating shaft, and the locking screw is used for axially locking the central folding rotating shaft in an unfolded state.

Effects of the Invention

[0027] The beneficial effects of the present invention are as follows. The lightweight, three-stage folding bicycle with a multi-stage interlocking structure according to this invention has a simple and highly integrated structure. Unlike conventional single-hinge or multi-stage folding structures, its three-stage spatial interlocking folding structure enables a continuous folding path that does not require a fixed folding sequence. By combining the three-stage folding structure with a quick-locking mechanism, the entire vehicle can be folded and unfolded in a few seconds, and the operation is simple and can be done with one hand. After folding, both wheels are stacked in parallel, the front tube is in close contact with the main frame, and the overall width is small, the thickness is thin, the height is low, and the folded volume is significantly reduced, making it highly portable and suitable for travel on subways, storage at home, and loading into automobiles. The high-carbon steel frame has an optimized mechanical structure and a reliable locking mechanism, and the rigidity of the folding joint is sufficient, there is no vibration or loss of force during riding, and structural stability is high. The high-carbon steel frame has a weight-reducing structure due to its optimized design, the overall weight of the vehicle is light, the burden of carrying it is small, and it is suitable for carrying and traveling for long periods of time. After folding, it can stand on its own and can also be dragged, making it suitable for use in a variety of situations such as urban commuting, elevators, subways, offices, and homes, and offering high practicality. The cable guide structure, designed with guide grooves, fixing rings, and slack, prevents brake and gear cables from being pulled, worn, or interfered with during the folding process, improving safety and durability. This bicycle has a simple structure, high folding efficiency, small storage volume, strong connection rigidity, and rational cable routing, resulting in excellent riding stability and reliability. The concealed wiring and compact folding form meet the needs of urban high-quality mobility and are applicable to a variety of users such as urban commuters, students, and short-distance travel enthusiasts. It can meet the needs of use in various situations such as transferring to public transportation such as subways and buses, storage in small spaces at home, and short-distance outdoor riding, and has the potential for a wide range of applications. [Brief explanation of the drawing]

[0028] By reading the detailed description of the preferred embodiments described below, various other advantages and beneficial effects will become apparent to those skilled in the art. The accompanying drawings are for illustrative purposes only and do not limit the invention. [Figure 1] Figure 1 is a drawing of a lightweight, three-stage folding, multi-stage linked bicycle according to an embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram showing the loosened state of the central folding rotation shaft according to an embodiment of the present invention. [Figure 3] Figure 3 is a schematic diagram showing the central folding rotation axis of an embodiment of the present invention rotated by 45°. [Figure 4] Figure 4 is a schematic diagram showing the central folding rotation axis of an embodiment of the present invention rotated by 90°. [Figure 5] Figure 5 is a schematic diagram showing the central folding rotation axis of an embodiment of the present invention rotated by 135°. [Figure 6] Figure 6 is a schematic diagram showing the state in which the three folding nodes according to an embodiment of the present invention are interconnected and the folding process is completed. [Figure 7] Figure 7 is a schematic diagram showing the cable wiring of a cable guide structure according to an embodiment of the present invention. [Figure 8] Figure 8 is a schematic diagram showing the structure of a folding joint mechanism according to an embodiment of the present invention. [Figure 9] Figure 9 is a diagram of the actual structure of the rear fork folding section according to an embodiment of the present invention. [Figure 10] Figure 10 is a diagram of the actual structure of the central folding section of the main frame according to an embodiment of the present invention. [Figure 11] Figure 11 is a diagram showing the actual state of a bicycle after it has been fully folded, according to an embodiment of the present invention. [Figure 12] Figure 12 is a front frame drawing of a lightweight, three-stage folding, multi-stage interlocking bicycle structure according to an embodiment of the present invention. [Figure 13] Figure 13 is an enlarged view of the local structure of a central folding rotating shaft lock screw according to an embodiment of the present invention. [Figure 14]Figure 14 is a structural axial line drawing of a lightweight, three-stage folding, multi-stage interlocking bicycle according to an embodiment of the present invention. [Figure 15] Figure 15 is a structural frame diagram showing the central folding rotation axis of an embodiment of the present invention rotated by 90°. [Figure 16] Figure 16 is a structural frame diagram showing the central folding rotation axis of an embodiment of the present invention rotated by 135°. [Figure 17] Figure 17 is a structural frame diagram showing the state in which the three folding nodes according to an embodiment of the present invention are interconnected and the folding process is completed. [Modes for carrying out the invention]

[0029] The following describes exemplary embodiments in detail. These embodiments are shown in the accompanying drawings. Where drawings are referred to in the following description, unless otherwise specified, the same numbers in different drawings indicate the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the present disclosure detailed in the accompanying claims.

[0030] The terms used in this disclosure are for illustrative purposes only and are not intended to limit the disclosure. The singular forms “one,” “the said,” and “the said” as used in this disclosure and the appended claims are intended to include the plural form unless the context clearly indicates otherwise. Furthermore, the term “and / or” as used herein should be understood to refer to and include any and all possible combinations of one or more related enumerated items.

[0031] In this disclosure, terms such as "First," "Second," and "Third" may be used to describe various types of information, but it should be understood that this information should not be limited to these terms. These terms are simply used to distinguish information of the same kind from one another. For example, without departing the scope of this disclosure, the first type of information may be called the second type of information, and similarly, the second type of information may be called the first type of information. Depending on the context, the word "if" as used herein may be interpreted as "in the case of," "when," or "as determined." [Examples]

[0032] An embodiment of the present invention provides a lightweight, three-stage folding, multi-stage linked bicycle (shown in Figure 1), comprising a frame body, a front riser assembly, a rear fork assembly, a front wheel 7, a rear wheel 8, a folding lock system, and a cable guide structure 9. The main frame structure is a three-stage multi-stage interlocking folding structure, divided into a main frame central folding section (shown in Figure 10), a front riser folding section, and a rear fork folding section 15 (shown in Figures 9 and 11). The three folding sections are interconnected, ensuring smooth operation without interference during the folding process. After folding is complete, a self-stabilizing structure is formed by structural contact, engagement, or cooperation between the main frame, front riser, and rear fork, and the folded state is maintained without the need for additional fixing means.

[0033] The frame body, front fork, front riser 4, and rear fork 6 are all made of lightweight high-carbon steel (HCS), possessing high strength, toughness, impact resistance, and fatigue resistance, making them suitable for use in multi-stage folding structures. The frame cross-section is mechanically optimized, with major load areas reinforced and non-major areas lightened by hollowing out, achieving a balance between lightness and high strength.

[0034] High-carbon steel (HCS) material offers high strength and excellent load-bearing capacity, making it suitable for daily commuting and heavy load use. Its impact resistance is superior to ordinary low-carbon steel, providing good stability when riding on rough roads. The folding hinge area has high fatigue resistance, making it less susceptible to damage from repeated folding over long periods. Combined with an optimized cross-section and weight-reducing design, it achieves a lightweight design, making it convenient to carry.

[0035] The aforementioned main frame central folding section is located at an intermediate position of the main frame 1 that constitutes the vehicle chassis, and is equipped with a central folding rotation shaft 2 (shown in Figure 14) and a central folding rotation shaft lock screw 3 (shown in Figures 1, 12, and 13).

[0036] The folding process of the lightweight, three-stage folding multi-stage linked bicycle according to this embodiment proceeds through three positions sequentially: 45°, 90°, and 135°. The 45° position is shown in Figure 3, where the central folding rotation axis 2 rotates 45°, and the entire structure, indicated by the red frame, moves in the direction of the arrow. The 90° position is shown in Figure 4, where the central folding rotation axis 2 rotates 90°, and the entire structure, indicated by the red frame, moves in the direction of the arrow. The 135° position is shown in Figure 5, where the central folding rotation axis 2 rotates 135°, and the entire front wheel 7 moves in the direction of the arrow. Finally, it reaches a fully folded state (shown in Figure 11). As shown in Figures 6 and 17, after fully folding, the front wheel 7 is brought into the inside of the frame, forming a compact layout parallel to the rear wheel 8.

[0037] After the central folding rotation axis lock screw 3 is locked, the main frame 1 is configured as a rigid whole, and no loosening, shaking, or deformation occurs. By loosening the central folding rotation axis lock screw 3 (as shown in Figure 2), the central folding rotation axis 2 can be rotated in the horizontal plane.

[0038] A folding joint mechanism 5 and a press-type riser pipe folding lock mechanism 11 are provided at the lower part of the front riser pipe 4 (as shown in Figures 3, 8, and 12). In the unfolded state, the press-type riser pipe folding lock mechanism 11 is pressed and locked, and the front riser pipe 4 maintains an upright rigid state. When folding, the press-type riser pipe folding lock mechanism 11 is released, and the front riser pipe 4 is rotated downward and reversed via the folding joint mechanism 5 (as shown in Figure 8), finally being brought into close contact with the upper part of the main frame 1 of the vehicle chassis, significantly reducing the overall folded height of the vehicle. The folding joint mechanism 5 is equipped with a quick-locking structure and a positioning structure, ensuring stability in the folded position and secure locking after unfolding, thereby improving driving safety.

[0039] The rear fork 6 employs a folding structure and is provided with a rear fork folding positioning structure 12 and folding auxiliary rollers. When folded, the rear fork 6 rotates forward and reverses along with the rear wheels 8, moving to the intermediate region of the chassis. This causes the rear wheels 8 to come into close proximity with the front wheels 7, forming a parallel overlapping structure and reducing the lateral and longitudinal dimensions to the maximum extent possible. The rear fork folding positioning structure 12 engages and positions the fork after it reaches the folded position, preventing loosening, and is securely locked in the extended state, thereby ensuring the structural strength of the rear fork 6.

[0040] The folding auxiliary roller is attached to the lower part of the rear fork 6, allowing the bike to be dragged directly when folded, eliminating the need to carry it by hand at all times and improving portability.

[0041] As shown in Figure 7, the brake cable 13 and the gear shift cable 14 are routed via a cable guide structure 9, and the cables extend along the inside or side of the chassis body and are neatly restrained by a fixing ring, guide member, and arc-shaped guide groove. The cables have a reasonable allowance for expansion and contraction at the folding joint portion, preventing them from being excessively pulled, bent, or compressed during the folding process. The internal or side-by-side neat routing method avoids snagging due to exposed cables, improving the neat appearance and safety of use, and extending the service life of the cables.

[0042] The folding lock system consists of three parts: a rotary central folding lock mechanism 10, a push-type riser tube folding lock mechanism 11, and a rear fork folding positioning structure 12. The rotary central folding lock mechanism 10 controls the folding and locking of the main frame 1, providing quick operation and reliable locking. The push-type riser tube folding lock mechanism 11 controls the folding and unfolding of the front riser tube 4 and can be operated with one hand. The rear fork folding positioning structure 12 enables the folding positioning and unfolding lock of the rear fork 6. All locking mechanisms can be operated with one hand without tools, and both folding and unfolding can be completed within 3 to 5 seconds, making it significantly more efficient than conventional folding bikes that require sequential operation of multiple locks.

[0043] The operation to switch this bicycle from a rideable state to a folded state mainly involves the following steps. Loosen the central folding rotation axis lock screw 3 and the rotary central folding lock mechanism 10 (as shown in Figures 15 and 16). The main frame 1, which is the main body of the vehicle chassis, is rotated around the central folding rotation axis 2 to a fully folded position of 135°. The aforementioned press-type riser pipe folding lock mechanism 11 is released, and the front riser pipe 4 is folded downwards and brought into close contact with the vehicle frame. The handle stem is then lowered. Lower the seatpost (as shown in Figure 11) and retract the rear section of the main frame. The rear fork 6 is folded forward, the rear wheel 8 is brought close to the front wheel 7, and the rear fork folding positioning structure 12 is automatically engaged. Once folded, the entire vehicle becomes flat and compact, making it possible to carry it by hand, drag it, or store it away.

[0044] The process of unfolding this bicycle from its folded state to its ready-to-ride state mainly involves the following operations. The rear fork 6 is extended, and the rear fork folding positioning structure 12 is locked. The front riser pipe 4 is rotated and reversed to an upright position, and the press-type riser pipe folding lock mechanism 11 is locked. The main frame 1, which is the main body of the vehicle chassis, is returned to its extended state, and the rotary central folding lock mechanism 10 and the central folding rotation shaft lock screw 3 are locked. The entire vehicle returns to a rigid, stable driving state, making it possible to use it for normal driving.

[0045] When folded, this bicycle has a flat, compact form with a small volume. The front wheel 7 and rear wheel 8 are parallel and close together, resulting in an extremely small width. The front upright tube 4 is in close contact with the main frame 1, significantly reducing the height. The overall thickness is thin, making it easy to store in a car trunk, storage locker, under a bed, or under a desk. It can be left upright without the need for support, making it suitable for indoor storage. The cables, such as the brake cable 13 and gear shift cable 14, are either internally routed or have side guides to prevent tension, excessive bending, or compression during the folding process, thus preventing interference, malfunctions, and abnormal noises. This results in high responsiveness for both braking and shifting, ensuring safe and reliable use, and significantly extending the service life of the cables by reducing wear and deterioration.

[0046] The embodiment of this invention features a rational and reliable structural design, excellent practicality, and fast folding speed in actual application. The three-stage interlocking mechanism and three locking mechanisms allow for folding or unfolding within seconds, resulting in significant efficiency improvements. The wheels are close together, the vertical tubes are tightly fitted to the main frame, and the folded volume is small, flat, and compact, greatly improving portability and storage. High-carbon steel material, optimized structure, and reliable locking design provide strong frame rigidity, eliminating vibration and force loss during riding, resulting in high stability. Concealed and neat wiring ensures neat wiring, a compact folded form, no tension or wear during folding, safe and durable cables, and safe braking and shifting. The overall weight of the vehicle is light, making it easy to carry by hand or drag, and convenient to transport. This folding bicycle effectively solves the problems of existing folding bicycles, such as complexity of folding, bulkiness, insufficient rigidity, and cable damage. Its simple and streamlined folding structure makes both storage and portability smooth, making it ideal for use in car trunks, office spaces, and public transportation. It is particularly suitable for short-distance urban commutes, transfers on public transport, and lightweight travel, achieving comprehensive technical advantages such as high folding efficiency, compact volume, sufficient rigidity, cable safety, and lightweight portability. Suitable for a variety of scenarios including urban commuting, subways, elevators, offices, homes, and in cars, it possesses high market value and potential for widespread adoption.

[0047] The scope of protection of this invention is not limited to the embodiments described above, and any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention are all included within the scope of protection. For example, the material of the chassis components can be substituted with high-strength aluminum alloy or carbon fiber composite material depending on actual needs, and all such modifications fall within the scope of protection of this invention.

[0048] Although the technical solutions of the present invention have been described above with reference to preferred embodiments shown in the attached drawings, it will be readily apparent to those skilled in the art that the scope of protection of the present invention is not limited to these specific embodiments. Those skilled in the art can make equivalent modifications or substitutions to the relevant technical features without departing from the principles of the present invention, and all such modified or substituted technical solutions will be included within the scope of protection of the present invention.

[0049] The above descriptions are merely preferred embodiments of the present invention and do not limit it. Those skilled in the art will know that the present invention can be modified in various ways. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention shall all be covered by the protection of the present invention. [Explanation of Symbols]

[0050] 1. Main frame 2. Central folding pivot 3. Central folding pivot lock screw 4. Front riser 5. Folding joint mechanism 6. Rear fork 7. Front wheel 8. Rear wheel 9. Cable guide structure 10. Rotary central folding lock mechanism 11. Press-type riser folding lock mechanism 12. Rear fork folding positioning structure 13. Brake cable 14. Gear cable 15. Rear fork folding section

Claims

1. A lightweight, three-stage folding bicycle with a multi-stage interlocking structure, comprising a frame body, a front riser assembly, a rear fork assembly, and a wheelset, wherein the frame body has a three-stage multi-stage interlocking folding structure, and this three-stage multi-stage interlocking folding structure includes a main frame central folding section, a front riser folding section, and a rear fork folding section, which are arranged sequentially from front to rear. The aforementioned main frame central folding section, front riser folding section, and rear fork folding section are each connected to the vehicle chassis main body via a rotating connection structure. A lightweight, three-stage folding bicycle with a multi-stage interlocking structure, characterized in that the movement trajectories of the central folding section of the main frame, the front tube folding section, and the rear fork folding section are located within the same folding space and form a continuous folding path that does not interfere with each other due to spatial position limitations, thereby forming a continuous folding process free from structural interference.

2. A lightweight three-stage folding multi-stage linked bicycle as described in claim 1, wherein the central folding section of the main frame is equipped with a central folding rotation axis and a rotary central folding lock mechanism, and is foldable in a range of 0° to 135° in the horizontal plane, and after folding the front wheel converges toward the inside of the main frame; the front riser folding section is equipped with a quickly lockable folding joint mechanism, and when folded the front riser rotates and reverses downward to be in close contact with the upper part of the main frame of the main frame; and the rear fork folding section employs a folding rear fork structure, and when folded the rear wheel rotates and reverses forward to move to an intermediate position on the frame, forming a structure in which it is superimposed parallel to or partially superimposed with the front wheel.

3. A lightweight three-stage folding multi-stage linked bicycle as described in claim 1, wherein the folding angle of the central folding rotation axis includes three positions: 45°, 90°, and 135°, of which 45° and 90° are intermediate positions and 135° is a fully folded position, and the folding operation is smooth and interference-free.

4. A lightweight three-stage folding multi-stage linked bicycle according to claim 1, wherein the rear fork assembly is equipped with an auxiliary roller, and the auxiliary roller is used to support the entire vehicle in the folded state and to enable dragging movement.

5. A lightweight three-stage folding multi-stage linked bicycle according to claim 1, wherein the folding joint mechanism of the front pipe folding section is equipped with a quick locking structure and a positioning structure, and the front pipe is stably attached to the upper part of the main frame after folding, and is securely locked after unfolding to maintain stability, characterized in that a lightweight three-stage folding multi-stage linked bicycle.

6. A lightweight three-stage folding multi-stage linked bicycle according to claim 1, wherein the rear fork folding portion is connected to the main frame via a folding connection structure, and when folded, the rear wheel moves toward the middle of the frame along a predetermined trajectory, forming a structure in which it is superimposed parallel to or partially superimposed with the front wheel.

7. A lightweight three-stage folding multi-stage linked bicycle according to claim 1, wherein the rear fork folding portion is provided with a positioning engagement structure, and after the rear fork folding portion reaches the folding position, positioning and locking are achieved by engagement, locking, or structural interference, characterized in that the lightweight three-stage folding multi-stage linked bicycle.

8. A lightweight three-stage folding multi-stage linked bicycle according to claim 1, wherein the frame body is made of a metal material or a composite material, and the material includes high carbon steel, aluminum alloy, or carbon fiber composite material.

9. A lightweight three-stage folding multi-speed linked bicycle according to claim 1, further comprising a cable guide structure, wherein the cable guide structure is provided inside or on the side of the frame body, and the brake cable and gear cable are routed along the inside or on the side of the frame body via a fixing ring and a guide member; the cable guide structure is provided with an arc-shaped guide groove at the folding joint portion, and a cable expansion and contraction allowance is secured, characterized in that a lightweight three-stage folding multi-speed linked bicycle.

10. A lightweight three-stage folding multi-stage linked bicycle according to claim 2, characterized in that a locking screw is provided on the central folding rotation shaft, and the locking screw is used to lock the central folding rotation shaft in the axial direction when unfolded.

Images