A variable volume collapsible handcart and method of operation thereof

Abstract

A variable-volume folding handcart and its operating method are disclosed. The handcart includes a symmetrically arranged left and right frame assembly, a horizontal folding mechanism connecting the two, a base plate assembly, a traveling assembly, and a traction assembly. The handcart has an unfolded state and a folded state: in the unfolded state, the horizontal folding mechanism unfolds to form a transport device; in the folded state, the horizontal folding mechanism folds, and the left, right, and base plate assemblies together enclose a storage box with internal storage space. A preferred embodiment further includes a vertical lifting mechanism connected to the base plate assembly, which drives the base plate assembly to rise and fall vertically when the horizontal folding mechanism unfolds or folds, achieving a linked operation. Simultaneously, in the folded state, the traveling assembly is at least partially located within the bottom contour of the box, achieving concealed storage of the traveling assembly. This invention also provides an operating method for the handcart. In the folded state, this invention can be directly used as a storage box without repeated loading and unloading of items, has a simple structural linkage, and combines transportation and storage functions.

Description

Technical Field

[0001] This invention relates to the field of transportation technology, and more specifically, to a variable-volume folding handcart that can switch between an unfolded state and a folded state, and forms a storage box when folded, as well as a method for operating the handcart. Background Technology

[0002] Handcarts, as portable transportation tools, are widely used in outdoor activities, camping, shopping, and cargo handling. Traditional handcarts typically consist of a frame, wheels, and a handle, allowing them to be loaded with items and pulled when unfolded. To facilitate storage and transportation, various foldable handcarts have emerged in the present technology, which can reduce their size when not in use through a folding mechanism.

[0003] However, existing folding carts typically only have two states: an unfolded transport state and a folded storage state. In scenarios such as camping, users need to move their equipment from home to the trunk of their car, and then from the trunk to the campsite upon arrival. Traditional carts are too bulky when unfolded to fit in the trunk along with their contents; while in the folded state, although smaller, the internal space becomes unusable for storage, making the cart itself a storage item. Users must unload all items from the cart before loading, fold it up, put it in the trunk, and then reassemble and reload upon arrival – a cumbersome process with a poor user experience.

[0004] Research indicates that existing folding trolleys are designed to reduce size when folded, leaving no internal space for storage, and all items must be removed before folding. When folded, the internal space of existing folding trolleys is completely compressed or disappears, rendering them unusable as containers and requiring repeated loading and unloading. Currently, there is no solution for a folding trolley that automatically forms an internal storage compartment when folded, eliminating the need for repeated loading and unloading.

[0005] Therefore, there is an urgent need for a handcart that can still store items after being folded and does not require repeated loading and unloading of items. Summary of the Invention

[0006] This invention provides a variable-volume folding handcart and its operation method, aiming to solve the technical problem that existing folding handcarts cannot be used as storage containers in the folded state, resulting in the need for repeated loading and unloading of items. Technical solution

[0007] To achieve the above objectives, the present invention provides the following technical solution: A variable-volume folding handcart, comprising: The left and right frame components are symmetrically arranged and constitute the main support structure on the left and right sides of the vehicle body, respectively. A horizontal folding mechanism is connected between the left frame assembly and the right frame assembly to enable the vehicle body to unfold and fold in the width direction. A floor assembly is located at the bottom of the vehicle body; the floor assembly and the left frame assembly and / or the right frame assembly can be connected by a fixed connection, integral molding, sliding connection or a lifting mechanism to adapt to different usage requirements; A walking assembly, installed at the bottom of the left frame assembly and / or the right frame assembly, is used to enable the movement of the vehicle body; The traction assembly, located at one end of the vehicle body, is used to apply traction or thrust.

[0008] The handcart has an unfolded state and a folded state. In the unfolded state, the horizontal folding mechanism unfolds to form a transport device; in the folded state, the horizontal folding mechanism folds up, and the left frame assembly, right frame assembly and base plate assembly together enclose to form a storage box with internal storage space.

[0009] In this invention, the folding process of the handcart not only reduces its size but also fundamentally transforms its function: in the unfolded state, the cart serves as a transport tool, with items loaded on top of the base; in the folded state, the cart automatically transforms into a storage box with internal storage space, where items can be placed directly without needing to be moved. This linkage between "volume retention" and "functional transformation" distinguishes it from existing folding handcarts where the internal space disappears after folding and needs to be stored separately.

[0010] Horizontal folding mechanism The horizontal folding mechanism includes: A bottom folding unit is connected between the bottom of the left frame assembly and the bottom of the right frame assembly; A side folding unit is connected between the front side panel and / or the rear side panel of the left frame assembly and the right frame assembly; The bottom folding unit and the side folding unit fold or unfold synchronously during operation.

[0011] The bottom folding unit can adopt one or more combinations of cross-link hinge structure, multi-link hinge structure, scissor structure, and folding frame structure. In the unfolded state, the bottom folding unit constitutes the bottom load-bearing support structure of the vehicle body, used to support the weight of the floor assembly and items.

[0012] The side folding unit can adopt one or more combinations of cross-link hinge structure, multi-link hinge structure, and scissor structure.

[0013] Optionally, at least one link of the bottom folding unit is provided with a sliding connection structure between it and the left frame assembly or the right frame assembly, such as the cooperation of a slide groove and a slider, the cooperation of a guide rail and a slider, or the cooperation of a sleeve and a slide rod, to guide the movement trajectory during the folding process.

[0014] Vertical lifting mechanism As a further optimization, the variable-volume folding handcart may also include a vertical lifting mechanism, which is connected to the base plate assembly and is used to drive the base plate assembly to move up and down in the vertical direction when the horizontal folding mechanism is unfolded or retracted.

[0015] When a vertical lifting mechanism is provided, in the retracted state, the vertical lifting mechanism drives the base plate assembly to move downwards, lowering it to a position that is basically level with or slightly higher than the walking assembly. At this time, the walking assembly is at least partially located within the bottom outline of the box defined by the base plate assembly, achieving a "storage" effect for the walking assembly in the retracted state. This makes the vehicle body appear as a complete box shape, avoiding space occupation or collision risks caused by exposed walking components.

[0016] The vertical lifting mechanism includes: At least one telescopic rod is provided, which is arranged in a vertical direction and whose telescopic movement is driven by the folding or unfolding action of the horizontal folding mechanism; A transmission unit connects the telescopic rod and the base plate assembly, and is used to convert the telescopic movement of the telescopic rod into the lifting movement of the base plate assembly.

[0017] The telescopic movement of the telescopic rod is achieved in the following way: during the folding or unfolding process, the projected length of the connecting rod in the horizontal folding mechanism changes in the vertical direction. This change is transmitted to the telescopic rod through the connecting structure, causing the telescopic rod to extend or retract accordingly. Specifically, when the horizontal folding mechanism unfolds, the projected length of the connecting rod in the vertical direction shortens, causing the telescopic rod to retract; when the horizontal folding mechanism closes, the projected length of the connecting rod in the vertical direction increases, causing the telescopic rod to extend.

[0018] The telescopic rod may be installed on the left frame assembly and / or the right frame assembly.

[0019] The number of telescopic rods can be one or more, and their cross-sectional shape can be circular, square, polygonal or other irregular cross-section.

[0020] The transmission unit can be implemented in any one or more of the following ways: Suspension cable connection: The telescopic rod and the base plate assembly are connected by ropes, steel wires, chains or strip flexible components. When the telescopic rod rises, it pulls the base plate upward, and when the telescopic rod descends, it pushes the base plate downward. Rigid linkage connection: The telescopic rod and the base plate assembly are hinged by a rigid linkage to form a linkage mechanism; Rack and pinion drive: A rack is installed on the telescopic rod, and a gear that meshes with it is installed on the base plate assembly; Cam mechanism: Motion transmission is achieved through the cooperation of a cam and a follower; Hydraulic or pneumatic transmission: The telescopic rod is connected to the base plate assembly via a hydraulic cylinder or a pneumatic cylinder.

[0021] Optionally, the vertical lifting mechanism further includes a guide unit for guiding the base plate assembly to move in the vertical direction. The guide unit may be a combination of a slide groove and a slider, a guide rail and a pulley, or a sleeve and a slide rod.

[0022] Locking device The variable-volume folding trolley may also include a state locking device for locking the position of the horizontal folding mechanism and / or the vertical lifting mechanism in the unfolded and / or folded state to maintain a stable state.

[0023] The state locking device may adopt any one or more of the following structures: The fit between the elastic buckle and the slot; The fit between the spring clip and the positioning hole; Rotary lock; The fit between the pin and the pin hole; Ratchet and pawl mechanism; Threaded locking structure.

[0024] The state locking device may be installed on the telescopic rod, the horizontal folding mechanism, or between the left frame assembly and the right frame assembly.

[0025] Optionally, the state locking device automatically locks when the device reaches the unfolded or retracted position.

[0026] Traction components The traction assembly includes a hand lever, which is mounted at one end of the left frame assembly or the right frame assembly.

[0027] Optionally, the frame assembly on which the pull rod is mounted is provided with a storage groove, the bottom of the pull rod is hinged to the bottom of the storage groove, and the top of the storage groove is provided with an unlockable fastener for fixing the upper end of the pull rod in the storage groove or releasing the pull rod so that it can swing around the bottom hinge point.

[0028] The lever has at least two usage modes: First mode: The lever is fixed in a vertical or near-vertical position, suitable for pushing and pulling on flat surfaces; Second mode: The lever is released and can be tilted around the bottom hinge point to a preset angle, suitable for applying force at an angle on uneven surfaces.

[0029] The hand lever can be a telescopic lever or a lever of fixed length.

[0030] Framework component structure The left frame component and the right frame component can each independently adopt any of the following structural forms: Plate frame structure; A frame structure consisting of connecting rods and fabric; A frame structure made of welded or assembled metal tubing or profiles; A frame structure integrally molded or assembled from plastic or composite materials.

[0031] Folding pad Optionally, the variable-volume folding handcart also includes a folding pad, which can be unfolded to cover the bottom of the cart body and can be used as a partition for the interior space when folded.

[0032] The folding pad can adopt a multi-segment hinged structure, a flexible folding structure, or a roller shutter structure.

[0033] Walking components The walking assembly includes at least two casters, which may be swivel wheels, fixed wheels, or a combination of both.

[0034] When a vertical lifting mechanism is provided, in the retracted state, the telescopic rod of the vertical lifting mechanism extends downward to be basically level with or slightly higher than the casters, so as to utilize the space between the casters and the ground to form the bottom volume of the box.

[0035] Operating method The present invention also provides an operating method for the above-mentioned variable-volume folding handcart, including an unfolding method for switching the handcart from a folded state to an unfolded state, the unfolding method comprising: Unlocked state lock; Applying outward force to pull apart the left frame assembly and the right frame assembly causes the horizontal folding mechanism to unfold, increasing the width of the vehicle body; During the unfolding of the horizontal folding mechanism, the base plate assembly is driven to rise vertically via a linkage mechanism. Once the trolley reaches the unfolded position, it is automatically or manually locked by a status locking device.

[0036] Furthermore, the operation method also includes a folding method for switching the handcart from an unfolded state to a folded state, the folding method comprising: Unlocked state lock; Applying inward force merges the left frame assembly and the right frame assembly, causing the horizontal folding mechanism to fold up and reducing the width of the vehicle body. During the retraction process of the horizontal folding mechanism, the base plate assembly is driven to descend vertically via a linkage mechanism; Once the trolley reaches the folding position, it can be automatically or manually locked using a status locking device. In the folded state, the left frame assembly, the right frame assembly, and the base plate assembly together form a storage box with internal storage space.

[0037] Furthermore, in the retraction method, when the base plate assembly descends in the vertical direction, the walking assembly is at least partially located within the bottom contour of the box enclosed by the base plate assembly. Beneficial effects

[0038] Compared with the prior art, the present invention has the following beneficial effects: 1. Variable volume, multi-purpose: Through the cooperation of the horizontal folding mechanism and the base plate assembly, this handcart can be used as a transportation tool when unfolded, and automatically forms a storage box with internal storage space when folded. No additional disassembly or conversion operation is required, realizing two uses in one.

[0039] 2. No need for repeated loading and unloading, improving convenience: When folded up, the interior space of the vehicle can be used to store items directly. Users can leave items in the vehicle and put them in the trunk with the car. There is no need to unload the items before loading. After arriving at the destination, the items can be unfolded and used directly, simplifying the operation process.

[0040] 3. Structural linkage and simple operation: When the vertical lifting mechanism is used, the horizontal folding mechanism works in conjunction with the vertical lifting mechanism. Users only need to apply force to pull open or close the left and right frame components to simultaneously complete the change of vehicle width and the lifting of the floor. The operation is intuitive and requires no additional steps.

[0041] 4. Multiple modes to adapt to different road conditions: The hand lever has a flat road mode and an off-road mode, and the fixing method can be switched according to the road conditions to improve the comfort and control of use.

[0042] 5. Modular structural design allows for flexible configuration of each functional unit according to usage scenarios, adapting to different load-bearing and storage needs.

[0043] 6. Functional conversion and volume retention are integrated: The invention retains complete internal storage space after being folded up, realizing the functional conversion from a means of transportation to a storage container. Users do not need to repeatedly load and unload items, which significantly improves the convenience of use.

[0044] 7. Concealed storage of the walking components: In the folded state, the vertical lifting mechanism drives the base plate to descend, so that the walking components are at least partially located within the bottom outline of the box, achieving the "storage" effect of the wheels. The vehicle body presents a complete box shape, which is convenient for stacking and storage, and avoids space waste or bump damage caused by exposed casters. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention; Figure 2 This is a schematic diagram of the traction component installation in flat road mode according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the traction component installation in off-road mode according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the unfolded folding pad according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the collapsed state according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the bottom vertical lifting structure of the left frame component according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the suspension cable connection method according to an embodiment of the present invention. Detailed Implementation

[0046] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0047] It should be noted that in the description of this invention, the terms "left", "right", "front", "back", "up", "down", "vertical", "horizontal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Example

[0048] In the attached diagram, the structural names represented by each label are as follows: 1---Left frame; 2---Right frame; 3---Horizontal folding mechanism; 31---Bottom folding unit; 311---Slide groove; 32---Side folding unit; 4---Base plate assembly; 5---Vertical lifting mechanism; 51---Upper telescopic rod; 52---Lower telescopic rod; 53---Scissor linkage structure; 54---Suspension cable; 6---Traveling assembly; 7---Traction assembly; 71---Hand lever; 72---Vertical groove; 73---Lock; 9---Folding pad.

[0049] like Figure 1 As shown, this embodiment provides a variable-volume folding handcart, including a left frame 1, a right frame 2, a horizontal folding mechanism 3, a base plate assembly 4, a walking assembly 6, and a traction assembly 7. In this embodiment, the base plate assembly 4 is connected to the left frame 1 and the right frame 2 via a vertical lifting mechanism 5, achieving a height-adjustable function. It should be noted that in other embodiments, the base plate assembly 4 can also be fixedly connected to the left frame 1 and the right frame 2 or be integrally formed. In this case, the handcart can still form a storage box by the left frame 1, the right frame 2, and the base plate assembly 4 when folded, but the depth of the box is a fixed value. When the vertical lifting mechanism 5 is used, the base plate assembly 4 can be driven to descend during the folding process, further increasing the depth of the box, effectively utilizing the space between the casters and the ground, and expanding the storage volume.

[0050] To balance structural strength and lightweight requirements, the left frame assembly, right frame assembly, horizontal folding mechanism, and base plate assembly can be made of aluminum alloy, carbon fiber, reinforced nylon, or engineering plastics. The cross links and hinged parts are preferably made of high-strength aluminum alloy or stainless steel to ensure wear resistance and structural stability during long-term use.

[0051] Left frame and right frame The left frame 1 and right frame 2 are symmetrically arranged, forming the main support structures for the left and right sides of the vehicle body, respectively. In this embodiment, the left frame 1 and right frame 2 adopt a plate structure, including side plates and a bottom plate. In other implementations, the left frame 1 and right frame 2 may also adopt a connecting rod and fabric structure, a welded metal tube structure, or a one-piece molded plastic structure.

[0052] Horizontal folding mechanism The horizontal folding mechanism 3 is connected between the left frame 1 and the right frame 2, and includes a bottom folding unit 31 and a side folding unit 32.

[0053] The bottom folding unit 31 is located at the bottom of the vehicle body and is constructed by hinged cross links. A groove 311 is provided on the bottom side of the left frame 1 near the horizontal folding mechanism 3. One end of the connecting rod of the bottom folding unit 31 is slidably connected to the groove 311, and the other end is hinged to the right frame 2. When the left frame 1 and the right frame 2 move closer or further apart, the connecting rod of the bottom folding unit 31 slides within the groove 311, achieving synchronous deformation of the bottom structure. In this embodiment, the bottom folding unit 31, in its unfolded state, constitutes the bottom load-bearing support structure of the vehicle body. The cross links form a cross-support configuration, creating a stable bottom load-bearing frame that bears the main load of the floor assembly and the carried items. The cross links are made of high-strength aluminum alloy to ensure load-bearing capacity and durability.

[0054] The side folding units 32 are located on the front and rear sides of the vehicle body and are also constructed by cross-link hinges, connecting the front and rear side panels of the left frame 1 and the right frame 2 respectively. When the left frame 1 and the right frame 2 move closer or further apart, the bottom folding unit 31 and the side folding unit 32 deform synchronously, without the need for additional linkage mechanisms, ensuring the overall structural stability of the vehicle body during width changes.

[0055] Vertical lifting mechanism like Figure 6 As shown, the vertical lifting mechanism 5 includes an upper telescopic rod 51, a lower telescopic rod 52, a scissor-type linkage structure 53, and a suspension cable 54.

[0056] The upper telescopic rod 51 is connected between the front and rear side plates of the left frame 1, and the lower telescopic rod 52 is connected between the bottom plate of the left frame 1 and the bottom structure. One end of the scissor-type linkage structure 53 is hinged to the front and rear side plates of the left frame 1, and the other end is hinged to the bottom plate assembly 4.

[0057] The driving principle of the telescopic rod: During the folding or unfolding process, the projected length of the cross link in the horizontal folding mechanism 3 changes in the vertical direction. Specifically, when the left frame 1 and the right frame 2 move away from each other (unfold), the tilt angle of the cross link increases, and its projected length in the vertical direction shortens, causing the upper telescopic rod 51 and the lower telescopic rod 52 to retract upwards through the connecting structure; when the left frame 1 and the right frame 2 move closer to each other (close), the tilt angle of the cross link decreases, and its projected length in the vertical direction increases, causing the upper telescopic rod 51 and the lower telescopic rod 52 to extend downwards. This linkage mechanism ensures that the telescopic rod's extension and retraction movements are precisely synchronized with the actions of the horizontal folding mechanism.

[0058] The base plate assembly 4 and the lower telescopic rod 52 are connected by a suspension cable 54. For example... Figure 7 As shown, when the lower telescopic rod 52 rises, the suspension cable 54 is tightened, thereby pulling the base plate assembly 4 upward; when the lower telescopic rod 52 descends, its bottom abuts against the base plate assembly 4, pushing the base plate assembly 4 downward.

[0059] In this embodiment, the telescopic rod (lower telescopic rod 52) is only located on one side of the left frame assembly and serves as the input end for the driving force. To achieve synchronous lifting and lowering of the base plate assembly on both sides, the scissor-type linkage structure 53 connects the left frame assembly and the base plate assembly 4, and is hinged to both the left and right sides of the base plate assembly 4 respectively. When the telescopic rod drives one side of the base plate assembly to lift or lower, the scissor-type linkage structure transmits this motion to the other side of the base plate assembly, ensuring that the base plate assembly maintains a horizontal posture throughout the lifting and lowering process, avoiding jamming or tilting.

[0060] To avoid the walking assembly 6, the base plate assembly 4 is provided with an avoidance structure at the position corresponding to the walking assembly, so that the base plate assembly is structurally divided into at least two separate parts (e.g., left and right parts or front and back parts). The scissor-type linkage structure 53 connects these at least two parts simultaneously, and is used to transmit the unilateral driving force of the telescopic rod to each separate part of the base plate assembly, so as to realize the overall synchronous lifting and lowering of the base plate assembly. It can be understood that the avoidance structure of the base plate assembly can be a slot, notch, segmented base plate or other form that does not interfere with the walking assembly, and the connection points of the scissor-type linkage structure can also be adjusted accordingly according to the division method of the base plate assembly.

[0061] It should be noted that the scissor linkage structure is only a preferred method for achieving synchronous lifting. Those skilled in the art can also use other forms of synchronous transmission mechanisms, such as synchronous belts, gear rack pairs, or double telescopic rod structures arranged symmetrically on the left and right, all of which do not depart from the protection scope of this invention.

[0062] In other implementations, the base plate assembly 4 and the lower telescopic rod 52 can also be connected by a rigid connecting rod, gear rack, cam, or hydraulic transmission.

[0063] In this embodiment, the vertical lifting mechanism 5 drives the base plate assembly 4 to descend to a position roughly flush with the casters when it is in the retracted state. At this time, the casters are located within the bottom outline of the box enclosed by the base plate assembly 4. From the outside, the vehicle body presents a complete box shape, and the casters are not exposed. This design not only expands the effective volume inside the box but also achieves "hidden storage" of the walking components when retracted. This allows the handcart to be placed directly in the trunk of a car or on the indoor floor as an independent storage box after being retracted, without having to consider the space occupied by the casters or the instability they may cause.

[0064] Status locking device In this embodiment, the state locking device is located on the lower telescopic rod 52 and adopts a structure in which a V-shaped spring engages with a positioning hole. When the vehicle body reaches the unfolded or retracted position, the V-shaped spring engages with the corresponding positioning hole to achieve automatic locking. The user can unlock the device by pressing the spring.

[0065] In other implementations, the state locking device can also take the form of a ring, pin, rotary lock, or ratchet mechanism, and can be set on the horizontal folding mechanism 3 or between the left and right frames.

[0066] Traction components like Figure 2 , Figure 3 As shown, the traction assembly 7 includes a hand lever 71. A vertical groove 72 is provided at the end of the left frame 1, the bottom of the hand lever 71 is hinged to the bottom of the vertical groove 72, and a latch 73 is provided at the top of the vertical groove 72.

[0067] In flat road mode (such as) Figure 2 As shown), the handle 71 is pulled out and extended from the vertical groove 72, and the top is fixed by the buckle 73. The handle 71 is in a vertical state, which makes it easy to push and pull on a flat surface.

[0068] In off-road mode (such as) Figure 3 As shown), the latch 73 is unlocked, and the pull rod 71 can be tilted around the bottom hinge point to a preset angle, which is convenient for applying force at an angle on uneven surfaces.

[0069] The handle 71 is a telescopic handle, and its length can be adjusted as needed. In other implementations, the handle 71 can also be of a fixed length.

[0070] Walking components The walking assembly 6 includes four casters, mounted at the bottom four corners of the left frame 1 and the right frame 2. Two casters on the side closest to the traction assembly 7 are swivel casters, while the other is a fixed caster. In other implementations, the type and number of casters can be adjusted as needed.

[0071] Folding pad like Figure 4 As shown, this embodiment also includes a folding mat 9, which can be unfolded to cover the bottom of the vehicle body. In the folded state, the folding mat 9 can be used as a partition for the interior space, facilitating the categorization and storage of items. The folding mat 9 adopts a multi-segment hinged structure; in other implementations, a flexible folding structure or a roller shutter structure can also be used.

[0072] Operation process When switching from the collapsed state to the expanded state: Unlocked state lock; Apply outward force to pull apart the left frame 1 and the right frame 2; The horizontal folding mechanism 3 unfolds simultaneously, increasing the width of the vehicle body; The projected length of the cross link in the vertical direction of the horizontal folding mechanism 3 is shortened, which causes the upper telescopic rod 51 and the lower telescopic rod 52 to retract upward; The lower telescopic rod 52 rises, pulling the base plate assembly 4 upwards via the suspension cable 54; Once the deployment position is reached, the status lock will automatically engage.

[0073] At this time, the vehicle body is in the unfolded state and can be used as a handcart.

[0074] When switching from the expanded state to the collapsed state: Unlocked state lock; Apply inward force to merge the left frame 1 and the right frame 2; The horizontal folding mechanism 3 folds down synchronously, reducing the width of the vehicle body; The increased projection length of the cross link in the horizontal folding mechanism 3 in the vertical direction causes the upper telescopic rod 51 and the lower telescopic rod 52 to extend downwards. The lower telescopic rod 52 extends, and its bottom pushes the base plate assembly 4 downward; Once the desired position is reached, the status lock will automatically engage.

[0075] At this time, the vehicle body is in a folded-down state, forming a box-like space inside, such as Figure 5 As shown.

[0076] Space utilization in the collapsed state like Figure 5 As shown, in the folded state, the vertical lifting mechanism 5 drives the base plate assembly 4 to descend, placing the casters within the bottom contour of the box, thus achieving the "storage" effect of the walking components. The base plate assembly, through avoidance structures or reserved space, prevents interference with the casters, allowing the vehicle body to appear as a complete box, avoiding space occupation or collision risks caused by exposed casters, while simultaneously increasing the effective internal volume of the box. Users can directly place beverages, food, tea sets, and other small items inside the box and store them in the car's trunk without needing to remove them separately.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Those skilled in the art can make various improvements and equivalent substitutions without departing from the spirit and principles of the invention, and these improvements and equivalent substitutions should also be considered within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A folding handcart with variable volume, characterized in that, include: The left and right frame components are symmetrically arranged and constitute the main support structure on the left and right sides of the vehicle body, respectively. A horizontal folding mechanism is connected between the left frame assembly and the right frame assembly to enable the vehicle body to unfold and fold in the width direction. A floor assembly is disposed at the bottom of the vehicle body, and the floor assembly is directly connected to the left frame assembly and / or the right frame assembly or connected through an intermediate component; A walking assembly is installed at the bottom of the left frame assembly and / or the right frame assembly; The traction assembly is located at one end of the vehicle body; The handcart has an unfolded state and a folded state. In the unfolded state, the horizontal folding mechanism unfolds to form a transport device; in the folded state, the horizontal folding mechanism folds up, and the left frame assembly, right frame assembly and base plate assembly together enclose a storage box with internal storage space.

2. The variable-volume folding handcart according to claim 1, characterized in that, The horizontal folding mechanism includes: A bottom folding unit is connected between the bottom of the left frame assembly and the bottom of the right frame assembly; A side folding unit is connected between the front side panel and / or the rear side panel of the left frame assembly and the right frame assembly; The bottom folding unit and the side folding unit operate synchronously when the horizontal folding mechanism unfolds or retracts.

3. The variable-volume folding handcart according to claim 2, characterized in that, The bottom folding unit and / or the side folding unit adopt a cross-link hinge structure, a multi-link hinge structure, or a scissor structure.

4. The variable-volume folding handcart according to claim 1, characterized in that, It also includes a vertical lifting mechanism, which is connected to the base plate assembly and linked with the horizontal folding mechanism, so that the horizontal folding mechanism drives the vertical lifting mechanism to move when it is unfolded or retracted, thereby driving the base plate assembly to rise and fall in the vertical direction.

5. The variable-volume folding handcart according to claim 4, characterized in that, The vertical lifting mechanism includes: At least one telescopic bar is provided on one side of the left frame assembly or the right frame assembly; A scissor-type linkage structure, one end of which is hinged to the front and rear side plates of the frame assembly on which the telescopic rod is provided, and the other end of which is hinged to the base plate assembly; The base plate assembly is provided with an avoidance structure at the position corresponding to the walking assembly, so that the base plate assembly is structurally divided into at least two interconnected parts, and the scissor linkage structure is connected to the at least two parts at the same time. The telescopic movement of the telescopic rod is achieved in the following way: during the folding or unfolding process, the projection length of the connecting rod in the horizontal folding mechanism changes in the vertical direction. This change is transmitted to the telescopic rod through the connecting piece or sliding fit structure, causing the telescopic rod to extend or retract accordingly.

6. The variable-volume folding handcart according to claim 5, characterized in that, It also includes a transmission unit that connects the telescopic rod and the base plate assembly, for converting the telescopic movement of the telescopic rod into the lifting movement of the base plate assembly; the transmission unit is selected from any one of the following: cable connection, rigid linkage connection, gear and rack transmission, cam mechanism, hydraulic transmission or pneumatic transmission.

7. The variable-volume folding handcart according to claim 1, characterized in that, The traction assembly includes a hand lever, and a storage groove is provided on the frame assembly on which the hand lever is installed. The bottom of the hand lever is hinged to the bottom of the storage groove, and an unlockable fastener is provided on the top of the storage groove for fixing the upper end of the hand lever in the storage groove or releasing the hand lever so that it can swing around the bottom hinge point.

8. The variable-volume folding handcart according to claim 1, characterized in that, It also includes a state locking device for locking the position of the horizontal folding mechanism and / or the vertical lifting mechanism in the unfolded state and / or the retracted state; the state locking device is disposed between the telescopic rod, the horizontal folding mechanism, or the left frame assembly and the right frame assembly.

9. The variable-volume folding handcart according to claim 1, characterized in that, It also includes a folding pad, which can be unfolded to cover the bottom of the vehicle body and can be used as a partition for the interior space when folded.

10. The variable-volume folding handcart according to claim 1, characterized in that, In the folded state, the left frame assembly, the right frame assembly, and the base plate assembly together form a storage box, and the walking assembly is at least partially located within the space defined by the bottom outline of the storage box.

11. A method of operating a variable-volume folding handcart as described in any one of claims 1 to 10, characterized in that, The method includes an unfolding method for switching the handcart from a folded state to an unfolded state, the unfolding method comprising: Unlocked state lock; Applying outward force to pull apart the left frame assembly and the right frame assembly causes the horizontal folding mechanism to unfold, increasing the width of the vehicle body; During the unfolding of the horizontal folding mechanism, the base plate assembly is driven to rise vertically via a linkage mechanism. Once the trolley reaches the unfolded position, it is automatically or manually locked by a status locking device.

12. The operating method according to claim 11, characterized in that, It also includes a folding method for switching the handcart from an unfolded state to a folded state, the folding method comprising: Unlocked state lock; Applying inward force merges the left frame assembly and the right frame assembly, causing the horizontal folding mechanism to fold up and reducing the width of the vehicle body. During the retraction process of the horizontal folding mechanism, the base plate assembly is driven to descend vertically via a linkage mechanism; Once the trolley reaches the folding position, it can be automatically or manually locked using a status locking device. In the folded state, the left frame assembly, the right frame assembly, and the base plate assembly together form a storage box with internal storage space.

13. The operating method according to claim 12, characterized in that, In the retraction method, when the base plate assembly descends in the vertical direction, the walking assembly is at least partially located within the bottom contour of the box enclosed by the base plate assembly.

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