Foldable cargo conversion frame with magnetic attraction guiding lock and cargo bicycle

Abstract

The utility model discloses a kind of foldable goods conversion frame and cargo carrying two-wheeled vehicle with magnetic attraction guiding locking, belong to bicycle cargo carrying device technical field.The foldable goods conversion frame includes: two symmetrical folding arms of symmetrical arrangement, central folding hinge being arranged in the middle position of two symmetrical folding arms as folding rotating pivot point, and magnetic attraction guiding locking mechanism being arranged in the key position of symmetrical folding arm for locking folding state.In folding process, magnetic attraction force is generated between magnetic spherical guide head and magnetic response sheet on symmetrical folding arm, provides automatic guiding function, guides folding arm accurate alignment;In locking state, magnetic attraction force and the mechanical compression force of compression spring form double locking mechanism, ensure locking reliability.The utility model is through magnetic attraction guiding design, effectively solved the technical problems, such as high operation precision requirement of traditional mechanical locking structure, poor anti-vibration performance, easy to wear etc.

Description

Technical Field

[0001] This utility model relates to the technical field of bicycle cargo carriers, specifically to a foldable cargo conversion frame with magnetic guide locking and a cargo two-wheeler, which is particularly suitable for cargo carrying systems for cargo bicycles or electric vehicles. Background Technology

[0002] Cargo bicycles and electric bikes, as environmentally friendly and convenient short-distance cargo transportation tools, have been widely used in urban logistics distribution, household shopping, and other scenarios. To improve the practicality and portability of cargo bicycles, foldable cargo frames have become an important design direction, allowing users to fold and store the cargo frame when not in use, reducing the space occupied by the vehicle and facilitating storage and passage.

[0003] However, existing foldable cargo conversion frames have many technical flaws in their locking mechanism design. For example, US Patent 6135478A discloses a foldable bicycle frame that uses a quick-release clamping device as its folding locking mechanism. This quick-release device generates clamping force through a lever-cam mechanism to fix the front and rear frames in the unfolded position. The operator needs to adjust the clamping force by rotating the quick-release lever and then move the lever to the locked position to complete the locking.

[0004] While this traditional, purely mechanical quick-release locking mechanism is widely used in the bicycle industry, its application in the foldable cargo frame of cargo bicycles has revealed significant technical problems: First, high operational precision is required. The quick-release lever mechanism requires the operator to precisely align the folding arm to the locking position for the lever to engage smoothly. In actual use, due to frame manufacturing tolerances, wear and tear from long-term use, and deformation caused by load, alignment is difficult. Especially after prolonged use with loaded goods, the structural deformation of the rack and the increased gaps in the moving parts often require repeated adjustments to achieve accurate locking, making the operation cumbersome and time-consuming.

[0005] Secondly, it has poor vibration resistance. During operation, especially on bumpy roads or when carrying heavy loads, cargo bicycles are subjected to continuous vibration and impact. Traditional quick-release locking structures have rigid contact between the lever and the locking surface, lacking an effective cushioning mechanism. Under prolonged vibration, slight relative displacement and loosening can easily occur between the locking components, reducing the reliability and safety of the lock, and potentially causing the cargo frame to accidentally come loose during operation, creating a safety hazard.

[0006] Third, it is prone to wear. The locking mechanism of the quick-release mechanism relies on the mechanical fit between metals. Under frequent locking and unlocking operations, as well as vibration and impact, the contact surfaces are prone to wear. Wear leads to an increase in the fit clearance, further reducing locking accuracy and stability, creating a vicious cycle. After long-term use, the locking mechanism may fail, requiring frequent maintenance or replacement of parts, increasing operating costs.

[0007] Furthermore, traditional mechanical locking structures lack a guiding function. During folding operations, the operator needs to rely on experience and feel to guide the folding arm to the correct position. The absence of an automatic centering or guiding mechanism increases the difficulty of operation and reduces the user experience.

[0008] Therefore, a new type of folding locking mechanism needs to be developed that can reduce the operational precision requirements, improve vibration resistance, reduce wear, and have an automatic guiding function while ensuring locking reliability and security, so as to meet the needs of foldable cargo frames for cargo bicycles in practical applications. Summary of the Invention

[0009] The purpose of this utility model is to provide a foldable cargo conversion frame and a cargo bicycle or electric vehicle with magnetic attraction and locking function, so as to solve the technical problems of high operational precision requirements, poor vibration resistance and easy wear of the existing folding locking mechanism.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: This utility model provides a foldable cargo conversion frame with magnetic attraction and locking function for use on cargo bicycles or electric vehicles. It includes: two symmetrically arranged folding arms that form a cargo carrying space when unfolded and fold into a compact state when folded; a central folding hinge connecting the two symmetrical folding arms, allowing them to rotate relative to each other; and a magnetic fixing device for the folding arms, mounted on the main frame, for providing magnetic attraction and stable fixing to the symmetrical folding arms when the foldable cargo conversion frame is in the folded state.

[0011] The folding arm magnetic fixing device includes: a mounting base, fixedly mounted on the main frame; a magnetic adsorption head, disposed within the mounting base; an elastic support spring, located between the magnetic adsorption head and the mounting base, elastically supporting the magnetic adsorption head so that the magnetic adsorption head can generate elastic displacement within the mounting base; and magnetically responsive iron elements, respectively disposed on the two symmetrical folding arms, wherein when the symmetrical folding arms are in the folded state, the magnetically responsive iron elements align and contact with the magnetic adsorption head and generate a magnetic attraction force.

[0012] Furthermore, it also includes a magnetic attraction guide locking mechanism, disposed on the main frame, for locking the folded state of the symmetrical folding arms. The magnetic attraction guide locking mechanism includes: a knob fixing seat, fixedly mounted on the main frame; an adjustment knob, rotatably mounted on the knob fixing seat, including a knob body and a screw; a compression spring, sleeved on the screw of the adjustment knob; a locking seat, sleeved below the compression spring and sleeved on the screw; two magnetic guide rods, fixedly disposed on both sides of the locking seat, extending respectively along the opening and closing direction of the two symmetrical folding arms; the ends of the magnetic guide rods are spherical structures, and magnetic materials are embedded inside or on the surface of the spherical structures to form magnetic spherical guide heads; magnetic response plates or magnetic metal plates are embedded in the symmetrical folding arms at the positions that contact the spherical ends of the magnetic guide rods, for generating magnetic attraction with the magnetic spherical guide heads.

[0013] Furthermore, the magnetic spherical guide head includes a magnetic core and an elastic buffer layer wrapped around the outer surface of the magnetic core, the elastic buffer layer being made of elastic polyurethane or silicone material.

[0014] Furthermore, the magnetic core of the magnetic spherical guide head is provided with an adjustable magnetic force adjustment device, which is a rotatable magnetic adjustment ring or a sliding magnetic shielding sleeve.

[0015] Furthermore, it also includes a support and stabilizing rod, one end of which is rotatably connected to the symmetrical folding arm via a hinged connector, and the other end is provided with a locking mechanism.

[0016] Furthermore, the locking mechanism includes a magnetic locking device, which includes a magnetic locking head disposed at the end of the support stabilizing rod and a magnetic locking receiver disposed on the symmetrical folding arm. The magnetic locking head and the magnetic locking receiver are locked together by magnetic attraction.

[0017] Furthermore, the magnetic locking device also includes an elastic support mechanism, which is disposed between the magnetic locking head or the magnetic locking receiver and its mounting base, so that the magnetic locking head or the magnetic locking receiver can generate elastic displacement.

[0018] Furthermore, the outer surface of the magnetic adsorption head is covered with a protective layer.

[0019] This utility model also provides a cargo bicycle or electric vehicle, including: a main frame; a foldable cargo conversion frame installed on the main frame, including: two symmetrically arranged folding arms that form a cargo carrying space in the unfolded state and are folded into a compact state in the folded state; a central folding hinge connecting the two symmetrical folding arms, allowing the two symmetrical folding arms to rotate relative to each other; and a magnetic attraction device installed on the main frame for stable fixation by magnetic attraction when the symmetrical folding arms are in the folded state.

[0020] Furthermore, the magnetic attraction device includes a magnetic adsorption head and a magnetically responsive iron component disposed on the symmetrical folding arm. The magnetic adsorption head and the magnetically responsive iron component achieve stable fixation of the symmetrical folding arm through magnetic attraction.

[0021] The beneficial effects of this utility model are as follows: By incorporating a magnetic adsorption device into the folding locking mechanism, the automatic guiding and locking functions are achieved through magnetic attraction, significantly reducing the precision requirements for operation and improving operational convenience. The design of the magnetic spherical guide head can provide smooth guidance and precise positioning during the convergence of the symmetrical folding arms, avoiding the jamming phenomenon that may occur in traditional mechanical locking structures; The combination of elastic support spring and magnetic attraction forms a dual locking mechanism, which has both the adjustable mechanical force provided by the spring and the continuous attraction force provided by the magnet, greatly improving the reliability and security of locking. The design of the elastic buffer layer gives the entire locking system adaptive buffering characteristics, which can absorb vibration energy during driving bumps, effectively solving the problem of poor vibration resistance of traditional mechanical locking structures; Magnetic attraction, as a non-contact attraction method, does not wear out with long-term use, ensuring the long-term stability of the locking mechanism and reducing maintenance costs. The magnetic force adjustment device allows for flexible adjustment of the magnetic attraction force according to the load and road conditions, improving the product's applicability and user experience. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of a foldable cargo conversion frame with magnetic guide locking function on a cargo bicycle in the folded state, according to this utility model. Figure 2 for Figure 1 The enlarged view at point A shows a partially enlarged structural schematic diagram of the magnetic attraction guide locking mechanism of this utility model; Figure 3 This is a side view of the cargo bicycle frame of this utility model, showing the installation position of the folding arm magnetic fixing device; Figure 4for Figure 2 The enlarged view at point B shows an exploded structural diagram of the folding arm magnetic fixing device of this utility model; Figure 5 This is a partial structural diagram of the magnetic fixing device for the folding arm of this utility model, showing the internal structure of the magnetic adsorption head and the elastic support spring; Figure 6 This is a partial structural diagram of the foldable cargo conversion frame of this utility model in its folded state; Figure 7 for Figure 6 The enlarged view at point C is a schematic diagram of the working state of the magnetic attraction fixing device for the folding arm of this utility model, showing the cooperation relationship between the magnetic attraction head and the magnetically responsive iron part; Figure 8 This is a schematic diagram of the installation of the support and stabilizing rod of this utility model in its unfolded state; Figure 9 This is a partial structural schematic diagram of the support and stabilizing bar locking mechanism of this utility model.

[0023] Explanation of reference numerals in the attached figures: 01-Main frame; 011-Front fork; 012-Handlebars; 013-Seatpost; 014-Head tube; 015-Down tube; 100 - Foldable cargo conversion frame; 110 - Symmetrical folding arm; 120 - Central folding hinge; 121 - Unfolding limit support; 130 - Magnetic guide locking mechanism; 131 - Compression spring; 132 - Locking seat; 133 - Magnetic guide rod; 134 - Knob fixing seat; 135 - Adjustment knob; 140 - Support stabilizer bar; 141 - Hinge connector; 142 - Locking mechanism; 150 - Folding arm magnetic fixing device; 151 - Mounting base; 152 - Magnetic adsorption head; 153 - Elastic support spring; 154 - Magnetic responsive iron part. Detailed Implementation Example

[0024] like Figure 1 As shown, this embodiment provides a foldable cargo conversion frame with magnetic guide locking function for use with cargo bicycles or electric vehicles.

[0025] The main frame 01 includes components such as wheels, front fork 011, handlebars 012, seat post 013, head tube 014, and down tube 015, forming a cargo bicycle similar to the one in prior patent publication US11260928B2. The core of this embodiment lies in solving the technical problems of high operational precision requirements, poor vibration resistance, and easy wear of traditional mechanical locking structures by setting magnetic adsorption devices at the end of the guide rod and the contact position of the folding arm in the folding locking mechanism.

[0026] The foldable cargo conversion frame 100 includes: two symmetrically arranged folding arms 110, a central folding hinge 120 located at the middle of the two symmetrical folding arms 110 as a folding rotation pivot point, and a magnetic guide locking mechanism 130 located at a key position of the symmetrical folding arms 110 for locking the folded state.

[0027] The two symmetrical folding arms 110 are interconnected by a central folding hinge 120 to form a foldable load-bearing structure. The symmetrical folding arms 110 extend longitudinally along the frame, forming a U-shaped or rectangular cargo carrying space in the unfolded state, and can be folded into a compact state to reduce space occupation in the folded state. The central folding hinge 120 includes a hinge body and an unfolding limiting support 121. The hinge body is a pivot connection structure, and the middle ends of the two symmetrical folding arms 110 are rotatably connected to both sides of the hinge body via pins or bearings. The unfolding limiting support 121 is provided on the central folding hinge 120 to provide structural support and limiting function when the foldable cargo conversion frame 100 is unfolded to the working state, preventing the frame from over-expanding or deforming.

[0028] The magnetic attraction guide locking mechanism 130 of this embodiment. For example... Figures 2 to 7 As shown, the structure is mounted on the main frame 01 and supported by, for example, a cantilever. It mainly includes: a knob mounting base 134 fixedly mounted on the structural support; an adjustment knob 135 rotatably mounted on the knob mounting base 134; a compression spring 131 and a locking seat 132 sleeved from top to bottom on the screw of the adjustment knob 135; and two magnetic guide rods 133 located on both sides of the locking seat 132 and extending to both sides along the opening and closing direction of the two symmetrical folding arms 110.

[0029] Specifically, the end of the magnetic guide rod 133 is a spherical structure, with magnetic material embedded inside or on its surface to form a magnetic spherical guide head. The magnetic core can be made of permanent magnet materials such as neodymium iron boron (NdFeB), ferrite, or AlNiCo, and is fixed to the center of the spherical end by injection molding, press-fit installation, or bonding. The outer surface of the magnetic core is covered with an elastic polyurethane layer or silicone buffer layer with a thickness of 1-3 mm. This elastic layer can both conduct magnetic force and provide a buffering effect during adsorption, absorbing impact energy.

[0030] Correspondingly, a magnetic response sheet or magnetic metal sheet is embedded in the symmetrical folding arm 110 at the position where it contacts the spherical end of the magnetic guide rod 133. This magnetic response sheet can be made of soft magnetic materials such as silicon steel sheets or permalloy, or it can also use a permanent magnet material but with opposite polarity to generate a magnetic attraction. The magnetic response sheet is installed on the surface or inside the symmetrical folding arm 110 by riveting, bolting, or embedding in grooves. A thin layer of elastic material can also be provided on its surface as a protective and buffering layer.

[0031] The knob fixing seat 134 has a threaded hole at its center for engaging with the screw of the adjusting knob 135. The adjusting knob 135 includes a knob body and a screw. The knob body is a disc-shaped or cylindrical structure that can be held and rotated by the operator. The central axis of the knob body is fixedly connected to or integrally formed with the screw. The screw extends downward and passes through the threaded hole of the knob fixing seat 134, and continues downward through the compression spring 131 and the locking seat 132. By rotating the knob body, the screw can move up and down under the action of the threaded engagement, thereby adjusting the compression amount of the compression spring 131, and thus changing the clamping force of the locking seat 132 on the symmetrical folding arm 110.

[0032] A compression spring 131 is sleeved on the upper part of the screw of the adjusting knob 135. Its upper end presses against the bottom surface of the knob body or the support surface of the knob fixing seat 134, and its lower end presses against the top surface of the locking seat 132. In its natural state, it is in a pre-compressed state and can continuously provide downward elastic pressure. The locking seat 132 is sleeved below the compression spring 131 and is also sleeved on the screw of the adjusting knob 135. The locking seat 132 can slide up and down along the screw, but is pressed against the symmetrical folding arm 110 by the elastic force of the compression spring 131, thereby achieving clamping and locking.

[0033] The base of the magnetic guide rod 133 is fixed to the two side walls of the locking seat 132, and its extension direction is consistent with the opening and closing movement direction of the two symmetrical folding arms 110. The spherical structure at the end of the magnetic guide rod 133 has a dual function: on the one hand, the arc surface of the sphere can form a progressive contact with the arm surface of the symmetrical folding arms 110 during the closing process, playing a role in smooth guidance and precise positioning; on the other hand, the magnetic core embedded in the sphere generates a magnetic attraction between itself and the magnetic response plate on the symmetrical folding arm 110, providing automatic guidance during the closing process of the folding arms and providing additional magnetic locking force in the locked state.

[0034] In a further specific implementation, such as Figure 6 and Figure 7 As shown, the magnetic attraction structure employs an adjustable magnetic force design. The magnetic core at the spherical end of the magnetic guide rod 133 is equipped with a rotatable magnetic adjustment ring or a sliding magnetic shielding sleeve. The operator can change the effective magnetic flux by rotating the adjustment ring or sliding the sleeve, thereby adjusting the magnitude of the magnetic attraction force. This design allows for flexible adjustment of the magnetic attraction force according to load conditions and road conditions: when driving under light load or on a flat road, the magnetic attraction force can be appropriately reduced to facilitate folding operations; under heavy load or bumpy road conditions, the magnetic attraction force can be increased to provide stronger locking stability.

[0035] In a further specific implementation, such as Figure 3 , Figure 4 and Figure 5 As shown, the main frame 01 is also equipped with a folding arm magnetic fixing device 150, which provides magnetic attraction and stable fixing function for the symmetrical folding arms 110 when the foldable cargo conversion frame 100 is in the folded state. This folding arm magnetic fixing device 150 is fixedly connected to the vertical axis of the handlebar 012 via a fixing base, and is located in the center of the frame, as shown. Figure 3 As shown at point B in the middle.

[0036] Specifically, such as Figure 4 and Figure 5 As shown in the exploded structural diagram, which facilitates observation of its internal structure, the folding arm magnetic fixing device 150 mainly includes: a mounting base 151 fixedly mounted on a vertical shaft, a magnetic adsorption head 152 disposed within the mounting base 151, and an elastic support spring 153 located between the magnetic adsorption head 152 and the mounting base 151. The magnetic adsorption head 152 is made of permanent magnet material, such as neodymium iron boron or ferrite, and its outer surface is covered with a protective layer. The elastic support spring 153 is sleeved on the rear of the magnetic adsorption head 152, with one end pressing against the back of the magnetic adsorption head 152 and the other end pressing against the bottom of the mounting base 151, so that the magnetic adsorption head 152 can elastically displace within the mounting base 151 in the front-to-back direction.

[0037] Correspondingly, each of the two symmetrical folding arms 110 has a magnetically responsive iron element 154 embedded near its hinge end. This iron element is made of a soft magnetic material such as silicon steel sheet or pure iron, and is installed on the outer surface of the symmetrical folding arm 110 by riveting, bolting, or embedding in a groove. The position is designed so that when the symmetrical folding arm 110 is fully folded to the vertical position, the magnetically responsive iron element 154 is exactly aligned and in contact with the magnetic adsorption head 152.

[0038] When the foldable cargo conversion frame 100 is folded from its unfolded state, the two symmetrical folding arms 110 rotate inward and converge around the central folding hinge 120. As the symmetrical folding arms 110 rotate to a near-vertical position, the magnetically responsive iron parts 154 on the symmetrical folding arms 110 gradually approach the magnetic adsorption head 152. When the distance between them decreases to within the effective range of magnetic force (typically 5-15 mm), the magnetic adsorption head 152 begins to generate a magnetic attraction force on the magnetically responsive iron parts 154. This magnetic attraction force automatically guides the symmetrical folding arms 110 toward the magnetic adsorption head 152, assisting in precisely positioning the folding arms to the vertical folding position.

[0039] When the iron piece on the symmetrical folding arm 110 comes into contact with the magnetic adsorption head 152, the magnetic attraction reaches its maximum value, firmly adsorbing the symmetrical folding arm 110 into a vertical position. At this time, due to the weight of the folding arm and the goods, the iron piece exerts a certain pressure on the magnetic adsorption head 152. Under this pressure, the magnetic adsorption head 152 overcomes the elastic force of the elastic support spring 153 and slightly retracts into the mounting base 151, compressing the spring. This elastic buffering mechanism can absorb the impact energy when the folding arm comes into contact with the magnetic adsorption head 152, avoiding rigid collisions. At the same time, the continuous elastic pressure of the spring keeps the magnetic adsorption head 152 pushing forward, enhancing the stability of the magnetic adsorption.

[0040] like Figure 4 The annotations indicate that the magnetic structure has elastic characteristics, enabling it to remain stable even under vibrations during operation. When a cargo bicycle is pushed or parked in its folded state, uneven ground or minor external impacts can cause the frame to vibrate. In conventional non-magnetic fixing structures, the folding arm may wobble or shift due to vibration. However, the folding arm magnetic fixing device 150 of this embodiment uses magnetic force to stably attach the folding arm to a vertical position, and even in the event of vibration, the magnetic force can counteract the tendency to separate due to vibration.

[0041] More importantly, the design of the elastic support spring 153 gives the entire magnetic attraction system an adaptive buffering characteristic: when the vibration amplitude is small, the magnetic attraction force is sufficient to offset the vibration effect, and the folding arm and the magnetic adsorption head 152 maintain a basically stable contact; when the vibration amplitude is large or the folding arm is subjected to a strong impact, the magnetic adsorption head 152 generates elastic displacement under the support of the spring, absorbing the impact energy and preventing damage to the magnetic adsorption head 152 or iron parts due to rigid impact. After the vibration, the elastic restoring force of the spring returns the magnetic adsorption head 152 to its original position, the magnetic attraction force is quickly restored, and the folding arm is re-stabilized. This elastic magnetic attraction mechanism ensures the stability and reliability of the folding arm in the folded state, prevents the folding arm from being accidentally unfolded or wobbling, and facilitates the storage and pushing of vehicles.

[0042] When the foldable cargo conversion frame 100 needs to be unfolded from its folded state, the operator only needs to apply a certain pulling force to overcome the magnetic attraction, which will separate the symmetrical folding arm 110 from the magnetic adsorption head 152. The magnetic attraction force is carefully designed to provide sufficient force to stably fix the folding arm without being too strong to cause unfolding difficulties. After the folding arm is separated, the magnetic adsorption head 152 automatically returns to its initial position under the action of a spring, ready for magnetic fixation during the next fold.

[0043] In a further embodiment, a support and stabilizing bar 140 may also be provided on the symmetrical folding arm 110 to provide additional structural reinforcement and stable support when the foldable cargo conversion frame 100 is in the unfolded state. One end of the support and stabilizing bar 140 is rotatably connected to the symmetrical folding arm 110 via a hinged connector 141, and the other end is fixed by a locking mechanism 142. The support and stabilizing bar 140 can be stored by either a flip-up, attaching type or a detachable storage type.

[0044] In a further specific embodiment, the locking mechanism 142 of the support stabilizer bar 140 employs a magnetic locking device to achieve fast and reliable locking and unlocking operations. This magnetic locking device mainly includes: a magnetic locking head disposed at the end of the support stabilizer bar 140 and a magnetic locking receiver disposed on the symmetrical folding arm 110 or the main frame 01.

[0045] Specifically, the magnetic locking head is made of permanent magnet materials, such as neodymium iron boron, ferrite, or AlNiCo, and is installed at the end of the support and stabilizing rod 140 by embedding, covering, or integral molding. The outer surface of the magnetic locking head is covered with an elastic buffer layer, which is made of elastic polyurethane or silicone material with a thickness of 1-3 mm. This elastic buffer layer can both conduct magnetic force and provide a buffering effect when locking contact, absorbing impact energy and avoiding damage or noise caused by rigid collisions.

[0046] See Figures 1-9 The working principle is as follows: As the foldable cargo conversion frame 100 rotates from the unfolded state to the folded state, the two symmetrical folding arms 110 rotate toward each other around the central folding hinge 120, gradually approaching each other. Before the symmetrical folding arms 110 contact the spherical end of the magnetic guide rod 133, when the distance between them decreases to within the effective range of magnetic force (typically 5-20 mm), a magnetic attraction begins to be generated between the magnetic spherical guide head and the magnetic response plate on the symmetrical folding arm 110. Due to the long-range effect of the magnetic field, this magnetic attraction can guide the movement trajectory of the symmetrical folding arms 110 before physical contact occurs.

[0047] When the symmetrical folding arm 110 deviates slightly from its approach angle due to operational deviations or structural tolerances, the magnetic attraction generates a component force pointing towards the center of the magnetic spherical guide head. This component force automatically corrects the movement direction of the folding arm, guiding it towards the correct alignment position. This magnetic automatic guidance effect significantly reduces the requirements for operational precision. Even if the direction of the force applied by the operator is not precise enough, the folding arm can accurately enter the receiving space of the locking seat 132 under the guidance of the magnetic force. During the approach process, the arc surface of the spherical structure forms line contact or small-area contact with the surface of the symmetrical folding arm 110. The frictional resistance between the contact surfaces is small, and the symmetrical folding arm 110 experiences less resistance during the approach process, allowing the operator to complete the folding action relatively easily.

[0048] When the two symmetrical folding arms 110 are fully brought together and enter the receiving space of the locking seat 132 under magnetic guidance, the distance between the magnetic spherical guide head and the magnetic response plate on the symmetrical folding arm 110 reaches its minimum, and the magnetic attraction reaches its maximum. This magnetic attraction, combined with the mechanical clamping force provided by the compression spring 131, creates a superimposed effect, acting together on the symmetrical folding arm 110 to produce a dual locking mechanism. The compression spring 131 is in a pre-compressed state, generating a downward elastic pressure on the locking seat 132. This pressure is transmitted through the locking seat 132 and the magnetic guide rod 133 to the ends of the symmetrical folding arms 110 that have entered their receiving space, keeping the two symmetrical folding arms 110 in a mutually pressing state under the combined action of elastic force and magnetic attraction, achieving initial locking and preventing the foldable cargo conversion frame 100 from accidentally unfolding due to slight vibration or external force during normal use.

[0049] If a stronger locking effect is needed to support heavier loads or handle more complex road conditions, the operator can rotate the tightening adjustment knob 135 downwards. The screw moves downwards under the action of the threaded engagement, further compressing the compression spring 131 fitted onto the screw. This increases the compression of the spring 131, significantly increasing the downward pressure of the spring on the locking seat 132. As the adjustment knob 135 continues to rotate, the locking seat 132, under greater elastic pressure, generates a stronger clamping force on the ends of the symmetrical folding arms 110 that have entered its receiving space, making the connection between the two symmetrical folding arms 110 more secure. Simultaneously, the magnetic attraction remains constant and continuously acts as a passive additional locking force, providing basic anti-loosening functionality even when the spring force is adjusted to a lower level.

[0050] like Figures 4 to 7As shown, the magnetic structure has elastic characteristics, enabling it to remain stable even under vibrations during operation. When the cargo bicycle travels on bumpy roads, the frame and cargo transfer frame are subjected to periodic impacts and vibrations from the road surface. These vibrations are transmitted through the main frame 01 to the foldable cargo transfer frame 100, and then act on the magnetic guide locking mechanism 130. In traditional purely mechanical locking structures, vibration impacts may cause slight relative displacements between the locking components, which may lead to loosening of the lock over time.

[0051] The magnetic attraction and locking mechanism 130 of this embodiment effectively solves this problem through its elastic magnetic attraction mechanism: when vibration causes a sudden increase in the contact pressure between the symmetrical folding arm 110 and the magnetic spherical guide head, the elastic buffer layer undergoes compression deformation to absorb the impact energy and avoid rigid collision; after the vibration impact, the elastic buffer layer returns to its original shape due to its own elasticity, while the magnetic attraction continues to act, firmly adhering the symmetrical folding arm 110 to the spherical end of the magnetic guide rod, offsetting the separation tendency caused by vibration. This elastic magnetic attraction mechanism has adaptive characteristics: when the vibration amplitude is small, the magnetic attraction force is sufficient to offset the vibration effect, and the contact interface remains basically stable and adhered; when the vibration amplitude is large, the elastic buffer layer absorbs energy through deformation to prevent rigid impact from damaging the structure, and the magnetic attraction force quickly returns to the locked state after the vibration. Throughout the process, the magnetic attraction force, as a non-contact attraction force, will not decrease due to wear and can maintain a stable locking effect even after long-term use.

[0052] The design of the magnetic spherical guide head has multiple advantages: First, the remote effect of the magnetic field can begin guiding the folding arm before contact, achieving automatic centering and significantly reducing operational difficulty; second, the arc shape of the spherical surface can form a progressive guiding contact with the surface of the symmetrical folding arm 110 at different stages of approach, and the spherical surface can smoothly guide it into the correct position regardless of the angle at which the symmetrical folding arm 110 approaches, avoiding jamming that may occur due to sharp corners or planar structures; third, the superposition effect of magnetic attraction and mechanical clamping force forms a dual locking mechanism, with both adjustable mechanical force provided by the spring and continuous attraction force provided by the magnetism, improving the reliability and safety of locking; in addition, the smooth surface of the spherical structure does not easily accumulate dirt, and can maintain good guiding performance and magnetic attraction effect even when used in dusty or slightly polluted environments, reducing maintenance frequency.

[0053] In the locked state, the safety of the magnetic guide locking mechanism 130 is reflected in several aspects: First, the continuous elastic pressure provided by the compression spring 131 forms a passive anti-loosening mechanism. Even when encountering vibrations and impacts from bumpy roads during riding, the elastic force of the spring can always keep the symmetrical folding arm 110 pressed tightly. Second, the magnetic attraction force, as an additional locking force, continuously attracts the symmetrical folding arm 110 in a direction perpendicular to the contact surface, further enhancing the anti-loosening effect. Third, the design of the elastic buffer layer gives the entire locking system an adaptive buffering characteristic, which can absorb vibration energy without causing the lock to loosen. Fourth, the adjustable locking force of the adjustment knob 135 provides an active safety guarantee. The operator can actively increase the locking force according to the weight of the goods and road conditions. Fifth, the mechanical locking structure does not rely on electricity or other energy sources, eliminating the risk of locking failure due to power failure or energy depletion, and has high reliability.

[0054] When the foldable cargo conversion frame 100 needs to be unfolded from its folded state, the operator first rotates the adjusting knob 135 upwards in the opposite direction. The screw moves upwards under the action of the threaded engagement, reducing the compression of the spring 131 and decreasing the clamping force of the locking seat 132 on the symmetrical folding arms 110. Then, the symmetrical folding arms 110 are pulled in the opposite direction to overcome the remaining spring force and magnetic attraction. Because the magnetic attraction is relatively small and its direction is perpendicular to the separation direction, the lateral separation force applied by the operator can relatively easily overcome the magnetic attraction, causing the ends of the symmetrical folding arms 110 to disengage from the receiving space of the locking seat 132 and the positioning of the magnetic guide rod 133, thus releasing the locking state between the two symmetrical folding arms 110. During the process of the ends of the symmetrical folding arms 110 disengaging from the magnetic spherical guide head, the arc shape of the spherical surface also plays a guiding role, allowing the symmetrical folding arms 110 to smoothly exit the locked position, avoiding jamming or requiring excessive operating force during unlocking. After the lock is released, the symmetrical folding arm 110 can be rotated in the unfolding direction around the central folding hinge 120 to unfold the foldable cargo conversion frame 100 into the working state.

[0055] The above description is merely a specific example of this utility model and does not constitute any limitation on this utility model. Obviously, those skilled in the art, after understanding the content and principle of this utility model, may make various modifications and changes in form and details without departing from the principle and structure of this utility model. However, these modifications and changes based on the concept of this utility model are still within the protection scope of the claims of this utility model.

Claims

1. A foldable cargo conversion frame with magnetic guide locking function for use with cargo bicycles or electric vehicles, characterized in that, include: Two symmetrically arranged folding arms (110) form a cargo carrying space when unfolded and are folded into a compact state when folded. A central folding hinge (120) connects the two symmetrical folding arms (110), allowing the two symmetrical folding arms (110) to rotate relative to each other; a folding arm magnetic fixing device (150) is provided on the main frame (01) to provide magnetic adsorption and stable fixing function for the symmetrical folding arms (110) when the foldable cargo conversion frame is in the folded state. The folding arm magnetic fixing device (150) includes: a mounting base (151), which is fixedly installed on the main frame (01); A magnetic adsorption head (152) is disposed inside the mounting base (151); an elastic support spring (153) is located between the magnetic adsorption head (152) and the mounting base (151) to elastically support the magnetic adsorption head (152) so that the magnetic adsorption head (152) can generate elastic displacement within the mounting base (151). Magnetic responsive iron parts (154) are respectively disposed on the two symmetrical folding arms (110). When the symmetrical folding arms (110) are in a folded state, the magnetic responsive iron parts (154) are aligned and contacted with the magnetic adsorption head (152) and generate magnetic attraction.

2. The foldable cargo conversion frame with magnetic guide locking function according to claim 1, characterized in that, It also includes a magnetic guide locking mechanism (130), disposed on the main frame (01), for locking the folded state of the symmetrical folding arm (110), the magnetic guide locking mechanism (130) comprising: A knob mounting base (134) is fixedly installed on the main frame (01); An adjustment knob (135) is rotatably mounted on the knob mounting base (134) and includes a knob body and a screw. A compression spring (131) is fitted onto the screw of the adjusting knob (135); A locking seat (132) is fitted below the compression spring (131) and onto the screw; Two magnetic guide rods (133) are fixedly installed on both sides of the locking seat (132) and extend along the opening and closing direction of the two symmetrical folding arms (110); The end of the magnetic guide rod (133) is a spherical structure, and magnetic material is embedded inside or on the surface of the spherical structure to form a magnetic spherical guide head; The symmetrical folding arm (110) has a magnetic response sheet or magnetic metal sheet embedded in the position where it contacts the spherical end of the magnetic guide rod (133) to generate a magnetic attraction with the magnetic spherical guide head.

3. The foldable cargo conversion frame with magnetic guide locking function according to claim 2, characterized in that, The magnetic spherical guide head includes a magnetic core and an elastic buffer layer wrapped around the outer surface of the magnetic core. The elastic buffer layer is made of elastic polyurethane or silicone material.

4. The foldable cargo conversion frame with magnetic guide locking function according to claim 2, characterized in that, The magnetic core of the magnetic spherical guide head is provided with an adjustable magnetic force adjustment device, which is a rotatable magnetic adjustment ring or a sliding magnetic shielding sleeve.

5. The foldable cargo conversion frame with magnetic guide locking function according to claim 1, characterized in that, It also includes a support and stabilizing bar (140), one end of which is rotatably connected to the symmetrical folding arm (110) via a hinged connector (141), and the other end is provided with a locking mechanism (142).

6. The foldable cargo conversion frame with magnetic guide locking function according to claim 5, characterized in that, The locking mechanism (142) includes a magnetic locking device, which includes a magnetic locking head disposed at the end of the support stabilizing rod (140) and a magnetic locking receiver disposed on the symmetrical folding arm (110). The magnetic locking head and the magnetic locking receiver are locked together by magnetic attraction.

7. The foldable cargo conversion frame with magnetic guiding and locking function according to claim 6, characterized in that, The magnetic locking device further includes an elastic support mechanism, which is disposed between the magnetic locking head or the magnetic locking receiver and its mounting base, so that the magnetic locking head or the magnetic locking receiver can generate elastic displacement.

8. The foldable cargo conversion frame with magnetic guide locking function according to claim 1, characterized in that, The outer surface of the magnetic adsorption head (152) is covered with a protective layer.

9. A two-wheeled cargo vehicle, characterized in that, include: Main frame (01); A foldable cargo conversion frame (100), mounted on the main frame (01), includes: Two symmetrically arranged folding arms (110) form a cargo carrying space when unfolded and are folded into a compact state when folded. A central folding hinge (120) connects the two symmetrical folding arms (110), allowing the two symmetrical folding arms (110) to rotate relative to each other; A magnetic attraction device is provided on the main frame (01) for stable fixation by magnetic attraction when the symmetrical folding arm (110) is in the folded state.

10. The two-wheeled cargo vehicle according to claim 9, characterized in that, The magnetic attraction device includes a magnetic adsorption head (152) and a magnetically responsive iron piece (154) disposed on the symmetrical folding arm (110). The magnetic adsorption head (152) and the magnetically responsive iron piece (154) achieve stable fixation of the symmetrical folding arm (110) through magnetic attraction.

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