A chute foldable trolley

Abstract

The application discloses a chute type foldable handcart, which comprises a first platform with a front face and a back face arranged oppositely, a handrail rod and an adjusting mechanism; the handrail rod is rotationally connected to the end of the first platform, the adjusting mechanism is arranged on the first platform and acts on the handrail rod to limit the rotation of the handrail rod, the back face is provided with a pair of first pulleys and a pair of second pulleys, the midpoint connecting line of the two edges in the width direction of the back face is used as a reference axis, the pair of second pulleys are symmetrically arranged and rotationally connected to the first platform through a connecting body, and the pair of second pulleys correspond to the handrail rod, and the axis of the second pulley and the axis of the connecting body have a set interval; in the application, the handcart can be quickly converted among the four-wheel standing state, the two-wheel standing state and the four-wheel storage state through the cooperation of the handrail rod, the first pulley, the second pulley, the telescopic beam and the locking mechanism.

Description

Technical Field

[0001] This invention relates to the field of handcart technology, and more specifically to a foldable handcart with a sliding groove. Background Technology

[0002] Handcarts, as a short-distance transport tool primarily driven by human power, offer advantages such as low cost, easy maintenance, light weight, and flexible operation, making them widely used in confined spaces like warehouses, supermarkets, and homes. Their basic structure includes a platform, frame, wheels, and handles, and they come in various types based on the number of wheels, including one-wheeled, two-wheeled, three-wheeled, and four-wheeled. Different types of carts are suitable for different scenarios; for example, one-wheeled carts are easier to maneuver on rough terrain, two-wheeled carts are suitable for transporting packaged goods, while four-wheeled carts offer better maneuverability due to their casters. With the diversification of usage needs, specialized handcarts such as silent, anti-static, and foldable models have also emerged to adapt to different environments such as libraries, hotels, or homes.

[0003] Currently, the most common handcarts on the market are two-wheeled and four-wheeled. Four-wheeled handcarts, due to the symmetrical distribution of the wheels, ensure that the carrying platform remains level at any angle, thus providing more stable support for large or easily tipped-over goods. Therefore, they are more widely used in warehousing and logistics scenarios.

[0004] However, due to its large overall structure, it is not very flexible when used in small spaces such as homes.

[0005] For example, trolleys usually need to be folded for storage, but common four-wheeled trolleys use fixed swivel wheels. Even after folding, the wheel assembly still protrudes from the trolley, resulting in a still relatively large overall size. Furthermore, they cannot be effectively fitted into cabinets or corners. Additionally, the protruding swivel wheels shift the center of gravity to the side, causing the folded trolley to tilt, affecting proper storage and placement.

[0006] Secondly, in existing technologies, such as Chinese patent literature, application number CN202512054552.1 describes a two-wheeled to four-wheel convertible handcart. This handcart can be configured with a second roller to allow for two-wheeled, four-wheeled, and folded-down states. This allows the handcart to accommodate larger items and automatically adjust its state according to the size of the goods. However, this operation requires ensuring the first roller does not automatically reset. In other words, the positions of the first and second linkages must be constantly controlled. Since the entire handcart is operated via a sliding button, improper operation can cause the button to fail to reset promptly, easily resulting in the first and second linkages sliding linearly with a slight turn of the handlebar. This prevents the handcart from functioning properly in all three states: two-wheeled, four-wheeled, and folded-down.

[0007] Therefore, how to overcome the shortcomings of the existing technology is the subject of this invention. Summary of the Invention

[0008] The purpose of this invention is to provide a foldable trolley with a sliding groove, which aims to solve the problem mentioned in the background art that the two-wheel and four-wheel convertible trolley is controlled by a single sliding button. If the button is not reset in time due to improper operation, the first link and the second link will slide linearly, which will cause the trolley mechanism to be unable to be used normally in the two-wheel, four-wheel and folded storage states.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A chute-type foldable handcart includes a first platform having a front and a back arranged opposite to each other, a handrail, an adjustment mechanism, a linear guide mechanism, and a connecting body. The handrail is rotatably connected to the end of the first platform. The adjustment mechanism is mounted on the first platform and acts on the handrail to restrict its rotation. The back is provided with a pair of first pulleys and a pair of second pulleys. The line connecting the midpoints of the two sides in the width direction of the back is used as the reference axis. The pair of second pulleys are symmetrically arranged and rotatably connected to the first platform through a connector. The pair of second pulleys are arranged corresponding to the handrail. There is a set distance between the axis of the second pulley and the axis of the connector. When the handrail is driven to rotate, the connector is configured to drive the second pulleys to revolve around the rotation center of the handrail. The set distance is the distance that allows the second pulleys to achieve ground support or retract to the outer end of the first platform when revolving around the rotation center of the handrail. The roller seats of the pair of first pulleys are symmetrically arranged and each is rotatably connected to the first platform in a direction from approaching to moving away from the handrail, so that the first pulleys have an upright state and a flipped state; The adjustment mechanism includes a telescopic beam and a locking mechanism; The telescopic beam is disposed on the back side, and the telescopic beam is slidably disposed relative to the first platform via a linear guide mechanism. The sliding direction of the telescopic beam relative to the first platform is parallel to the direction on the first platform from near the handrail to away from the handrail, so that the telescopic beam has a first working position near the second pulley side and a second working position away from the second pulley side. The end of the telescopic beam away from the first pulley is hinged to the connecting body, while the end closer to the first pulley acts on the two first pulleys; The telescopic beam is configured such that when the telescopic beam is in the first working position, the first pulley is in an upright state, and when the telescopic beam is in the second working position, the first pulley is in a flipped state. The telescopic beam can extend and retract along its own length to form an elongated state and a shortened state; The locking mechanism includes a movable locking mechanism and a telescopic locking mechanism. The movable locking mechanism is used to limit the relative sliding between the telescopic beam and the first platform, and the telescopic locking mechanism is used to lock the telescopic beam in an extended or retracted state. The movable locking mechanism consists of an elastic fastener and a mating component. One of the elastic fastener and the mating component is located at the end of the second beam, and the other is located on the back side. The handcart has a four-wheel upright state, a two-wheel upright state, and a four-wheel folded-down state. When the trolley is in the four-wheel upright state, the telescopic locking mechanism locks the telescopic beam in the extended state, and the elastic fastener in the movable locking mechanism engages with the mating part to lock the telescopic beam in the first working position, which is used to position it between the first pulley and the second pulley so that both the first pulley and the second pulley support the first platform on the ground. When the handcart is switched from a four-wheel upright state to a two-wheel upright state, the telescopic beam is locked in the first working position by the movable locking mechanism, and the telescopic locking mechanism is released from the telescopic locking mechanism. The handrail is flipped and flattened towards the outside of the first platform end by external force, so that the telescopic beam is shortened to the shortened state and locked by the telescopic locking mechanism. At this time, the second pulley is moved towards the back and retracted, while the first pulley remains in the ground support state, achieving the two-wheel upright state. When the trolley changes from a four-wheel upright state to a four-wheel folded state, an external force flips the handrail against the front of the first platform, causing the second pulley to rotate to the outer end of the first platform to fold up. During this process, the telescopic beam moves, causing the mating parts to overcome the elastic force and disengage from the elastic fastener, thereby moving the telescopic beam to the second working position, and causing the first pulley to switch from an upright state to a flipped state, achieving the four-wheel folded state.

[0010] In the above solution, the handcart can be quickly switched between a four-wheel upright state, a two-wheel upright state, and a four-wheel folded state through the cooperation of the handrail, the first pulley, the second pulley, the telescopic beam, and the locking mechanism.

[0011] Unlike existing technologies, this invention achieves the switching of the trolley's state through the cooperation of the handrail, the first pulley, the second pulley, the telescopic beam, and the telescopic locking mechanism. The switching operation only requires a single action trigger, that is, a single rotation of the handrail can simultaneously complete the displacement of the telescopic beam and the flipping of the pulley. The entire operation process is simple and efficient, without the need for additional force or step-by-step adjustments. Moreover, in the four-wheel storage state, the first and second pulleys are retracted, and there is no phenomenon where the first and second pulleys still protrude from the vehicle body, causing the trolley's center of gravity to shift to the side.

[0012] In the above solution, the telescopic beam can be limited by the elastic fasteners and mating parts in the movable locking mechanism, so that the telescopic beam can only move as a whole when it is changed from the four-wheel upright state to the four-wheel folded state, and will not move arbitrarily in other situations.

[0013] Unlike existing technologies that use a sliding control button for operation, this invention uses a moving locking mechanism to limit the telescopic beam, creating a closer connection between the movement of the telescopic beam and the rotation of the handrail, as well as an error correction mechanism in case of operational errors. This not only improves the reliability of operation but also reduces the learning cost and error rate for users.

[0014] In the above scheme, the handrail is flipped and laid flat towards the outer side of the end of the first platform by external force. The outer side of the first platform corresponds to the inner side, and the outer side is away from the first platform.

[0015] In a further technical solution, the telescopic beam is composed of a first beam and a second beam nested together, and the first beam and the second beam slide relative to each other along the length direction of the telescopic beam to form an elongated state and a shortened state; The mating component includes two symmetrically spaced clamping posts disposed on the back side, with the axis of the clamping posts perpendicular to the back side. The elastic fastener includes a pair of clamping springs. The pair of clamping springs is provided at the end of the second beam away from the first beam. The pair of clamping springs is set at a distance corresponding to the interval between the two clamped columns. The pair of clamping springs is symmetrical and spaced apart with reference to the line connecting the midpoints of the two sides in the width direction of the telescopic beam. The opposite surfaces of the pair of clamping springs are provided with bending surfaces. The distance between the two bending surfaces is smaller than the interval between the two clamped columns. Through the cooperation of the bending surfaces with the clamped columns, the clamping springs are inserted between the two clamped columns and achieve snap-fit ​​limiting. In use, the elastic force on the clamping spring is overcome, causing the bent surface to disengage from the clamped post, thereby allowing the clamping spring to slide out from between the two clamped posts.

[0016] The above design allows the second beam to move relative to the back at any time.

[0017] In a further technical solution, the end of the second beam away from the first beam is hinged relative to the back side and slidably connected to the back side through the linear guide mechanism. The direction of this sliding connection is along the direction from the first platform toward the handrail. The end of the first beam away from the second beam is hinged to a pull arm through a hinge shaft. The end of the pull arm is hinged to the connecting body to achieve the positioning connection between the first beam and the handrail.

[0018] With the above design, the telescopic beam can switch between the first working position and the second working position, as well as between the extended state and the shortened state, by cooperating with the handrail.

[0019] In a further technical solution, the telescopic locking mechanism consists of a locking pin and a first limiting hole and a second limiting hole disposed on the first beam; On the first beam, the first limiting hole and the second limiting hole are spaced apart along the length direction of the first beam. The line connecting the centers of the first limiting hole and the second limiting hole is parallel to the extension line of the length direction of the first beam. The axes of the first limiting hole and the second limiting hole are both parallel to the axis of the locking pin. By selectively engaging the locking pin with the first limiting hole or the second limiting hole, the telescopic beam can be switched between the extended state and the shortened state. When the trolley is switched from a four-wheel upright state to a two-wheel upright state, the telescopic beam is in the first working position, and the locking pin cooperates with the second limiting hole to make the telescopic beam in the shortened state.

[0020] The above design allows for the switching of the telescopic beam's working position and status.

[0021] In a further technical solution, the locking post is arranged perpendicular to the length direction of the second beam in the vertical direction. The locking post is located in the overlapping area of ​​the second beam and the first beam. The upper end of the locking post is defined as the upper protruding end, which passes through the second beam and the first beam and limits the relative sliding of the two. A first elastic element acts on the locking post, so that the upper protruding end of the locking post always tends to extend upward.

[0022] The above design allows the locking pin to automatically disengage from or enter one of the first and second limiting holes.

[0023] A further technical solution is to provide an anti-detachment mechanism on the telescopic beam; The anti-detachment mechanism includes a sliding stop and an L-shaped hook that cooperates with it; The sliding stop is provided on the outer circumferential wall of the second beam near the first beam; An L-shaped hook block is provided on the outer periphery of one end of the first beam near the second beam. The hook part of the L-shaped hook block is positioned facing the second beam. The second beam is prevented from sliding away from the first beam by the cooperation of the sliding stop block and the L-shaped hook block.

[0024] The above design ensures that the second beam in the telescopic beam will not detach from the first beam when they slide relative to each other.

[0025] In a further technical solution, the locking mechanism also includes a protective mechanism; The protective mechanism includes a fixing frame set on the back, the fixing frame being set corresponding to the locking post, the fixing frame being provided with a long through groove, one end of the long through groove being open and the other end being closed, the open end of the long through groove being set towards the handrail, and the line connecting the midpoint of the open end of the long through groove to the midpoint of the closed end being parallel to the length direction of the second beam and the first beam. The lower end of the locking pin is defined as the lower through end, and the open end of the elongated through groove is provided corresponding to the lower through end; In both the four-wheel upright state and the two-wheel upright state, the lower protruding end remains embedded in the elongated through groove; In order to enter the four-wheel storage state, the lower protruding end slides away from the long strip groove along the length direction of the second beam and the first beam, and the upper protruding end on the locking post passes through the first limiting hole.

[0026] With the above design, the locking post can restrict the position of the first beam and the second beam, preventing the first beam and the second beam from continuing to move away from the handrail in the shortened state.

[0027] In a further technical solution, the locking mechanism also includes a side limiting mechanism; The side limiting mechanism includes a limiter and a locking shaft mating hole; The limiter is positioned and connected to the back side; The limiter includes a support frame, a limiting pin, a second elastic element, and a pushing part; The support frame is fixedly installed on the back, and the limiting pin is provided through the support frame. The axis of the limiting pin is perpendicular to the extension line of the telescopic beam. The limiting pin is disposed on the periphery of the first beam of the telescopic beam and corresponds to the locking post. A fixing block is positioned and connected to the periphery of the limiting pin, and the fixing block has a first inclined surface. The second elastic element acts on the limiting pin to ensure that the limiting pin always has a tendency to slide axially toward the telescopic beam; The pushing part is movably disposed on the back side and corresponding to the fixing block. The moving direction of the pushing part is along the direction perpendicular to the back side, and the pushing part abuts against the first inclined surface. The pushing part is configured to slide along the first inclined surface and push the fixing block and the limiting pin shaft to move along the axis of the limiting pin shaft. In the four-wheel upright state and the four-wheel retracted state, the first beam and the second beam move relative to each other to the extended state, preventing the end of the locking shaft from approaching the periphery of the second beam of the telescopic beam; With both wheels upright, the first beam and the second beam move relative to each other to a shortened state, restricting the insertion of the end of the retaining shaft into the retaining shaft mating hole, thereby limiting the relative sliding between the first beam and the second beam.

[0028] The above design can prevent the telescopic beam from sliding relative to the first platform when both wheels are upright.

[0029] A further technical solution is that the linear guide mechanism includes a linear guide rail connected to the rear positioning, wherein the length extension direction of the linear guide rail is parallel to the direction of approaching to and away from the handrail on the first platform; The telescopic beam is slidably connected within the linear guide rail. The locking mechanism includes a locking pin that passes through the linear guide rail to limit the sliding of the telescopic beam. The linear guide rail is provided with a structural limiting hole through which the locking pin passes.

[0030] A linear guide can be a long strip with a U-shaped cross-section, and the cross-sections of the first beam and the second beam can also be U-shaped.

[0031] With the above design, the telescopic beam can be restricted to moving only along the linear guide rail.

[0032] In a further technical solution, an operating hole is provided on the first platform corresponding to the locking post, and a button is movably disposed in the operating hole; The button is provided with a push part; The back is provided with a third elastic element, which acts on the button to make the button tend to extend out of the operating hole.

[0033] The above design enables the locking column to move up and down repeatedly.

[0034] Due to the application of the above-mentioned solution, the technical solution of this application has the following advantages and effects compared with the prior art: In this invention, the handcart can be quickly switched between a four-wheel upright state, a two-wheel upright state, and a four-wheel folded state through the cooperation of the handrail, the first pulley, the second pulley, the telescopic beam, and the locking mechanism.

[0035] Specifically, during use, the handcart is in a four-wheel upright state. At this time, the telescopic beam is locked in the extended state and the first working position by the locking mechanism, and positioned between the first pulley and the second pulley, so that both the first pulley and the second pulley support the first platform on the ground. Once it is necessary to put the handcart in a two-wheel upright state, the telescopic beam can be locked in the first position by the locking mechanism, and the locking mechanism can be released to extend and retract the telescopic beam. External force is used to flip the handrail to the outside of the end of the first platform and flatten it, so that the telescopic beam is shortened to the shortened state and locked by the locking mechanism. At this time, the second pulley is moved to the back and retracted, while the first pulley remains in the ground support state, achieving the two-wheel upright state. When it is necessary to put the trolley in a four-wheel folded state, the locking mechanism is released from the first working position of the telescopic beam. External force is used to flip the handrail against the front of the first platform, causing the second pulley to rotate to the outer end of the first platform to fold up. At the same time, the telescopic beam is moved from the first working position to the second working position, so that the first pulley switches from the upright state to the flipped state, achieving the four-wheel folded state.

[0036] Unlike existing technologies, this invention achieves the switching of the trolley's state through the cooperation of the handrail, the first pulley, the second pulley, the telescopic beam, and the telescopic locking mechanism. The switching operation only requires a single action trigger, that is, a single rotation of the handrail can simultaneously complete the displacement of the telescopic beam and the flipping of the pulley. The entire operation process is simple and efficient, without the need for additional force or step-by-step adjustments. Moreover, in the four-wheel storage state, the first and second pulleys are retracted, and there is no phenomenon where the first and second pulleys still protrude from the vehicle body, causing the trolley's center of gravity to shift to the side.

[0037] The present invention can limit the telescopic beam by moving the elastic fastener and the cooperating part in the locking mechanism, so that the telescopic beam can only move as a whole when it is changed from the four-wheel upright state to the four-wheel folded state, and will not move arbitrarily in other situations.

[0038] Unlike existing technologies that use a sliding control button for operation, this invention uses a moving locking mechanism to limit the telescopic beam, creating a closer connection between the movement of the telescopic beam and the rotation of the handrail, as well as an error correction mechanism in case of operational errors. This not only improves the reliability of operation but also reduces the learning cost and error rate for users. Attached Figure Description

[0039] Appendix Figure 1 This is a schematic diagram of the exploded structure of the handcart in the four-wheel upright state in an embodiment of the present invention; Appendix Figure 2 This is a schematic diagram of the linear guide rail structure when the handcart is in a four-wheel upright state according to an embodiment of the present invention. Appendix Figure 3 This is a schematic diagram of the connection between the first beam and the second beam when the handcart is in a four-wheel upright state according to an embodiment of the present invention. Appendix Figure 4 This is a schematic diagram of the elongated through-slot structure of a handcart in the four-wheel upright state according to an embodiment of the present invention; Appendix Figure 5 This is a schematic diagram of the handrail of the handcart in the four-wheel upright state in an embodiment of the present invention; Appendix Figure 6 This is a schematic diagram of the fixing frame structure of the handcart in the four-wheel upright state in an embodiment of the present invention; Appendix Figure 7This is a schematic diagram of the pull arm structure of the handcart in the four-wheel upright state in an embodiment of the present invention; Appendix Figure 8 This is a schematic diagram of the structure of the handcart in the embodiment of the present invention when the L-shaped hook block is connected to the sliding block in the state of the four wheels being raised. Appendix Figure 9 This is a schematic diagram of the handcart in the two-wheeled upright state in an embodiment of the present invention; Appendix Figure 10 This is a schematic diagram of the linear guide rail structure of the handcart in the two-wheeled upright state in an embodiment of the present invention. Appendix Figure 11 This is a schematic diagram of the connection between the first beam and the second beam when the handcart is in the state of having two wheels upright, according to an embodiment of the present invention. Appendix Figure 12 This is a schematic diagram of the elongated through-slot structure of a handcart in the two-wheeled upright state in an embodiment of the present invention. Appendix Figure 13 This is a schematic diagram of the storage space structure of the handcart in the two-wheeled upright state in an embodiment of the present invention. Appendix Figure 14 This is a schematic diagram of the fixing block structure of the handcart in the two-wheeled upright state in an embodiment of the present invention. Appendix Figure 15 This is a schematic diagram of the locking post structure of the handcart in the two-wheeled upright state in an embodiment of the present invention. Appendix Figure 16 This is a schematic diagram of the cross-sectional structure of the first beam of the handcart in the two-wheeled upright state in an embodiment of the present invention; Appendix Figure 17 This is a perspective view of the handcart in a four-wheel folded-down state according to an embodiment of the present invention; Appendix Figure 18 This is a schematic diagram of the elongated slot structure of the handcart in the four-wheel storage state in an embodiment of the present invention. Figure 18 Only one of the middle roller seats is shown). Appendix Figure 19 This is a partial sectional view of the first and second beams of the handcart in the four-wheel storage state in an embodiment of the present invention; Appendix Figure 20 This is a schematic diagram of the linear guide rail structure of the handcart in the four-wheel storage state in an embodiment of the present invention; Appendix Figure 21 This is a schematic diagram of the connection between the first beam and the second beam when the handcart is in a four-wheel folded-down state according to an embodiment of the present invention. Appendix Figure 22 This is a schematic diagram of the clamping spring structure of the handcart in the four-wheel storage state in an embodiment of the present invention; Appendix Figure 23This is a schematic diagram of the locking post structure of the handcart in the four-wheel storage state in an embodiment of the present invention; Appendix Figure 24 This is a schematic diagram of the structure of the handcart in the four-wheel storage state of the present invention, showing the pushing part in contact with the fixing block.

[0040] In the attached diagrams above: 1. First platform; 11. Front; 12. Back; 13. First pulley; 14. Second pulley; 15. Connecting body; 16. Operating hole; 17. Square hole; 18. Flip plate; 19. Mounting notch; 111. Second platform; 112. Rotating part; 121. Linear guide rail; 122. Fixing frame; 123. Limiter; 124. Movable connecting rod; 125. First connecting rod; 1211, Structural limiting hole; 1212, Clamped column; 1221. Accommodation space; 1222. Long through slot; 1223. Third elastic element; 1231. Support frame; 1232. Restricting pin; 1233. Second elastic element; 1234. Fixing block; 12341, First inclined plane; 131. Inclined block; 132. Protrusion; 133. Torsion spring sleeve; 134. Roller seat; 135. Front pulley body; 136. Limiting surface; 151. Shaft body; 152. Mounting part; 161. Button; 1611. Pushing part; 181. Push the sliding surface; 2. Handrails; 3. Adjustment mechanism; 31. First beam; 32. Second beam; 33. Telescopic locking mechanism; 311. Pulling arm; 312. Rotating sleeve; 313. First limiting hole; 314. Second limiting hole; 315. Pin engagement hole; 316. Hinge shaft; 317. L-shaped hook block; 321. Clamping spring; 322. Sliding stop; 331. Locking post; 3311. Upper protrusion end; 3312. Lower protrusion end; 3313. First elastic element. Detailed Implementation

[0041] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0042] The terms "first," "second," etc., used in this article do not specifically refer to order or sequence, nor are they intended to limit this case; they are merely used to distinguish components or operations described using the same technical terms.

[0043] The terms "connection" or "positioning" as used in this article can refer to two or more components or devices making direct physical contact with each other, or making indirect physical contact with each other, or to two or more components or devices operating or moving with each other.

[0044] The terms “include,” “including,” and “have” used in this article are all open-ended, meaning they include but are not limited to.

[0045] Unless otherwise specified, the terms used herein generally have their ordinary meaning in the context of the art, the subject matter, and the specific context. Certain terms used to describe this case will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing this case.

[0046] The terms “front,” “back,” “up,” “down,” “left,” and “right” used in this article are directional terms. In this case, they are only used to describe the positional relationship between the structures and are not intended to limit the specific direction of the protection scheme or its actual implementation.

[0047] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of this work. Singular forms such as “a,” “this,” “this,” “the,” and “the” as used herein also include plural forms.

[0048] like Figures 1-24 As shown, a chute-type foldable handcart includes a first platform 1 having a front 11 and a back 12 arranged opposite to each other, a handrail 2, and an adjustment mechanism 3. The handrail 2 is rotatably connected to the end of the first platform 1. The adjustment mechanism 3 is disposed on the first platform 1 and acts on the handrail 2 to restrict the rotation of the handrail 2. The back 12 is provided with a pair of first pulleys 13 and a pair of second pulleys 14. The line connecting the midpoints of the two sides in the width direction of the back 12 is used as the reference axis. The pair of second pulleys 14 are symmetrically arranged and rotatably connected to the first platform 1 through a connector 15. The pair of second pulleys 14 are arranged corresponding to the handrail 2. There is a set distance between the axis of the second pulley 14 and the axis of the connector 15. When the handrail 2 is driven to rotate, the connector 15 is configured to drive the second pulleys 14 to revolve around the rotation center of the handrail 2. The set distance is the distance at which the second pulleys 14 can achieve ground support or retract to the outer end of the first platform 1 when revolving around the rotation center of the handrail 2. The roller seats 134 of the pair of first pulleys 13 are symmetrically arranged and each is rotatably connected to the first platform 1 in a direction from approaching to moving away from the handrail 2, so that the first pulleys 13 have an upright state and a flipped state; The adjustment mechanism 3 includes a telescopic beam and a locking mechanism; The telescopic beam is disposed on the back side 12, and the telescopic beam is slidably disposed relative to the first platform 1 via a linear guide mechanism. The sliding direction of the telescopic beam relative to the first platform 1 is parallel to the direction on the first platform 1 from near the handrail 2 to away from the handrail 2, so that the telescopic beam has a first working position near the second pulley 14 and a second working position away from the second pulley 14. The end of the telescopic beam away from the first pulley 13 is hinged to the connecting body 15, while the end closer to the first pulley 13 acts on the two first pulleys 13. The telescopic beam is configured such that when the telescopic beam is in the first working position, the first pulley 13 is in an upright state, and when the telescopic beam is in the second working position, the first pulley 13 is in a flipped state. The telescopic beam can extend and retract along its own length to form an elongated state and a shortened state; The locking mechanism acts on the first platform 1 and the telescopic beam to limit the relative sliding between the telescopic beam and the first platform 1, and the locking mechanism is also used to lock the telescopic beam in the extended or shortened state. The handcart has a four-wheel upright state, a two-wheel upright state, and a four-wheel folded-down state. When the trolley is in the four-wheel upright state, the telescopic beam is locked in the extended state and the first working position by the locking mechanism, so as to be positioned between the first pulley 13 and the second pulley 14, so that the first pulley 13 and the second pulley 14 both support the first platform 1 on the ground; The locking mechanism includes a movable locking mechanism, which is composed of an elastic fastener and a mating component. One of the elastic fastener and the mating component is located at the end of the second beam 32, and the other is located on the back side 12. When the handcart is in the four-wheel upright position, the elastic fastener and the mating parts cooperate to put the telescopic beam in the first working position and the telescopic beam is in the extended state. When the trolley is switched from the four-wheel upright state to the four-wheel folded state, the mating parts overcome the elastic force and disengage from the elastic fasteners, so that the telescopic beam is in the second working position, and the telescopic beam is in the extended state. When the trolley changes from a four-wheel upright state to a two-wheel upright state, the telescopic beam is locked in the first working position by the locking mechanism, and the locking mechanism is released from the telescopic beam. The handrail 2 is flipped and flattened towards the outside of the end of the first platform 1 by external force, so that the telescopic beam is shortened to the shortened state and locked by the locking mechanism. At this time, the second pulley 14 is moved towards the back 12 and retracted, while the first pulley 13 remains in the ground support state, achieving the two-wheel upright state. When the trolley changes from a four-wheel upright state to a four-wheel folded state, the locking mechanism releases the locking of the telescopic beam at the first working position. External force flips the handrail 2 against the front 11 of the first platform 1, causing the second pulley 14 to rotate to the outer end of the first platform 1 to fold up the second pulley 14. At the same time, the telescopic beam moves from the first working position to the second working position, causing the first pulley 13 to switch from an upright state to a flipped state, achieving the four-wheel folded state.

[0049] In this invention, the telescopic beam can be a rod-shaped structure that can push the two first pulleys 13 to stand up. Therefore, as long as a spreading rod is provided at the end of the rod-shaped structure, the first pulleys 13 can be flipped when the telescopic beam is in the second working position. At this time, the rod-shaped structure and the spreading rod are combined to form a T-shape.

[0050] In this invention, the rotation direction of the first pulley 13 is based on the direction of approaching to moving away from the handrail 2, rotating towards or away from the back 12, and the rotation range of the first pulley 13 is between standing up and approaching the back 12.

[0051] In this invention, the function of the connecting body 15 is to enable the first pulley 13 and the second pulley 14 to perform standing and flipping operations simultaneously, that is, to pull and drive the telescopic beam through the connecting body 15.

[0052] In this invention, the linear guide mechanism can be selected from existing technologies, and components such as grooves and tracks can be selected. The first pulley 13 and the second pulley 14 are arranged sequentially along the direction from near the handrail 2 to away from the handrail 2.

[0053] In this invention, the handcart can be quickly switched between a four-wheel upright state, a two-wheel upright state, and a four-wheel folded state through the cooperation of the handrail 2, the first pulley 13, the second pulley 14, the telescopic beam, and the locking mechanism.

[0054] Specifically, during use, the handcart is in a four-wheel upright state. At this time, the telescopic beam is locked in the extended state and the first working position by the locking mechanism, which is used to position it between the first pulley 13 and the second pulley 14 so that both the first pulley 13 and the second pulley 14 support the first platform 1 on the ground. Once it is necessary to put the handcart in a two-wheel upright state, the telescopic beam can be locked in the first working position by the locking mechanism, and the locking mechanism can be released to extend and retract the telescopic beam. The handrail 2 is flipped and flattened towards the outside of the end of the first platform 1 by external force, so that the telescopic beam is shortened to the shortened state and locked by the locking mechanism. At this time, the second pulley 14 is retracted towards the back 12, while the first pulley 13 remains in the ground support state, achieving the two-wheel upright state. When it is necessary to put the trolley in a four-wheel storage state, the locking mechanism is released from the first working position of the telescopic beam. The handrail 2 is flipped and brought closer to the front 11 of the first platform 1 by external force, which drives the second pulley 14 to rotate to the outer end of the first platform 1 to realize the retraction of the second pulley 14. At the same time, the telescopic beam is moved from the first working position to the second working position, so that the first pulley 13 switches from the upright state to the flipped state, thus achieving the four-wheel storage state.

[0055] Unlike existing technologies, this invention achieves the switching of the trolley's state through the cooperation of the handlebar 2, the first pulley 13, the second pulley 14, the telescopic beam, and the telescopic locking mechanism 33. The switching operation only requires a single action trigger, that is, a single rotation of the handlebar 2 can simultaneously complete the displacement of the telescopic beam and the flipping of the pulley. The entire operation process is simple and efficient, without the need for additional force or step-by-step adjustments. Moreover, in the four-wheel storage state, the first pulley 13 and the second pulley 14 are retracted, and there will be no phenomenon where the first pulley 13 and the second pulley 14 still protrude from the vehicle body, causing the center of gravity of the trolley to shift to the side.

[0056] The present invention can limit the telescopic beam by moving the elastic fastener and the cooperating part in the locking mechanism, so that the telescopic beam can only move as a whole when it is changed from the four-wheel upright state to the four-wheel folded state, and will not move arbitrarily in other situations.

[0057] Unlike existing technologies that use a sliding control button for operation, this invention uses a moving locking mechanism to limit the telescopic beam, creating a closer connection between the movement of the telescopic beam and the flipping of the handrail 2, as well as an error correction mechanism in case of operational errors. This not only improves the reliability of operation but also reduces the learning cost and error rate for users.

[0058] It should be noted that when the handcart is in the four-wheel upright position, the angle between the handlebar 2 and the front face 11 of the first platform 1 is a right angle or an obtuse angle, and is an obtuse angle less than 120 degrees; when the handcart is in the two-wheel upright position, the handlebar 2 and the front face 11 of the first platform 1 are parallel or have an obtuse angle greater than 120 degrees.

[0059] Preferably, the telescopic beam is composed of a first beam 31 and a second beam 32 nested together, wherein the first beam 31 and the second beam 32 slide relative to each other along the length direction of the telescopic beam to form an elongated state and a shortened state; The end of the second beam 32 away from the first beam 31 is hinged relative to the back surface 12 and is slidably connected to the back surface 12 through the linear guide mechanism. The direction of this slidable connection is along the direction from the first platform 1 toward the handrail 2. The end of the first beam 31 away from the second beam 32 is hinged to a pull arm 311 through a hinge shaft 316. The end of the pull arm 311 is hinged relative to the connecting body 15 to achieve the positioning connection between the first beam 31 and the handrail 2.

[0060] With the above design, the telescopic beam can switch between the first working position and the second working position, as well as between the extended state and the shortened state, by cooperating with the handrail 2.

[0061] The principle behind the switching between elongated and shortened states: In the initial state, the telescopic beam is in the extended state and the trolley is in the four-wheel upright state. Once the handrail 2 is rotated to be nearly parallel to the front 11, the handrail 2 will push the pull arm 311 and the first beam 31 in sequence through the connecting body 15, so that the first beam 31 slides toward the second beam 32 until the two overlap and are in the shortened state.

[0062] Once the extended state is needed, simply rotate the handrail 2 in the opposite direction. Then, the handrail 2 will pull the pull arm 311 and the first beam 31 in sequence through the connecting body 15, so that the first beam 31 and the second beam 32 are extended.

[0063] It is important to note that the telescopic beam is in its first working position when both wheels are upright and when both wheels are upright. If the beam is then folded into its second working position, it will be in the fourth working position. In other words, when the four wheels are upright, continuing to rotate the handrail 2 towards the front 11 will cause the handrail 2 to pull the pull arm 311 and the first beam 31 sequentially via the connecting body 15 until the handrail 2 is nearly parallel to the front 11 of the first platform 1, at which point the telescopic beam will be in its second working position.

[0064] Preferably, the locking mechanism includes a telescopic locking mechanism 33 and a movable locking mechanism. The telescopic locking mechanism 33 is composed of a locking pin 331 and a first limiting hole 313 and a second limiting hole 314 provided on the first beam 31.

[0065] On the first beam 31, the first limiting hole 313 and the second limiting hole 314 are spaced apart along the length direction of the first beam 31. The line connecting the centers of the first limiting hole 313 and the second limiting hole 314 is parallel to the extension line of the length direction of the first beam 31. The axes of the first limiting hole 313 and the second limiting hole 314 are both parallel to the axis of the locking pin 331. By selectively engaging the locking pin 331 with either the first limiting hole 313 or the second limiting hole 314, the telescopic beam can be switched between the extended state and the shortened state. The movable locking mechanism consists of an elastic fastener and a mating component. One of the elastic fastener and the mating component is located at the end of the second beam 32, and the other is located on the back side 12. When the trolley is in the four-wheel upright state, the elastic fastener and the mating part cooperate to put the telescopic beam in the first working position, and the locking pin 331 cooperates with the first limiting hole 313 to put the telescopic beam in the extended state. When the trolley is switched from a four-wheel upright state to a two-wheel upright state, the telescopic beam is in the first working position, and the locking pin 331 cooperates with the second limiting hole 314 to make the telescopic beam in the shortened state. When the trolley changes from a four-wheel upright state to a four-wheel folded state, the mating parts overcome the elastic force and disengage from the elastic fasteners, so that the telescopic beam is in the second working position, and the telescopic beam is in the extended state.

[0066] The above design demonstrates how to switch the working position and status of the telescopic beam.

[0067] Specifically, the process for switching the telescopic beam between its extended and shortened states is as follows: When the telescopic beam is in its extended state, the locking pin 331 engages with the first limiting hole 313; When the trolley is switched from a four-wheel upright state to a two-wheel upright state, the telescopic beam is in the first working position, and the locking pin 331 cooperates with the second limiting hole 314 to make the telescopic beam in the shortened state. When the trolley is switched from the four-wheel upright state to the four-wheel folded state, the locking pin 331 engages with the first limiting hole 313, and at the same time the engaging part overcomes the elastic force and disengages from the elastic fastener, so that the telescopic beam is in the second working position, and the telescopic beam is in the extended state.

[0068] It should be noted that the telescopic locking mechanism 33 in the locking mechanism can also be a screw and a clamping block set on the screw. The clamping block consists of a fixed part in the middle and two movable parts on both sides of the fixed part. Rotating the screw drives the two movable parts to move closer to each other or further away from the first and second slots set around the first beam 31. During operation, rotating the screw drives the two movable parts to move closer to each other, thereby embedding them into the first or second slot. Through the cooperation of the movable part, the fixed part and the first slot, the telescopic beam can also switch between the extended state and the shortened state.

[0069] The movable locking mechanism can also be a screw and screw hole, or an elastic pin and a pin hole that cooperates with the elastic pin. By manually inserting or removing the screw or elastic pin, the telescopic beam can be switched between the extended state and the shortened state, that is, the position of the first beam 31 and the second beam 32 can be released or fixed.

[0070] Preferably, the locking post 331 is arranged perpendicular to the length direction of the second beam 32 in the vertical direction. The locking post 331 is located in the overlapping area of ​​the second beam 32 and the first beam 31. The upper end of the locking post 331 is defined as the upper protruding end 3311, which passes through the second beam 32 and the first beam 31 and limits the relative sliding of the two. A first elastic element 3313 acts on the locking post 331, so that the upper protruding end 3311 on the locking post 331 always has an upward tendency.

[0071] The first elastic element 3313 can be a spring.

[0072] With the above design, the locking pin 331 can automatically disengage from or enter one of the first limiting hole 313 and the second limiting hole 314.

[0073] Specifically, when the telescopic beam needs to be changed from an extended state to a shortened state, the locking pin 331 can be pressed down directly so that the upper protruding end 3311 of the locking pin 331 gradually disengages from the first limiting hole 313. Then, the first beam 31 slides toward the second beam 32 until the two overlap to the shortened state. At this time, the second limiting hole 314 is aligned with the upper protruding end 3311 of the locking pin 331, and the first elastic element 3313 works to push the upper protruding end 3311 of the locking pin 331 out of the second limiting hole 314.

[0074] Preferably, the mating component includes two symmetrically arranged and spaced-apart clamping posts 1212 disposed on the back surface 12, the axis of the clamping posts 1212 being perpendicular to the back surface 12; The elastic fastener includes a pair of clamping springs 321. The pair of clamping springs 321 is provided at the end of the second beam 32 away from the first beam 31. The pair of clamping springs 321 are arranged at intervals corresponding to the two clamped posts 1212. The pair of clamping springs 321 are symmetrically arranged with reference to the line connecting the midpoints of the two sides in the width direction of the telescopic beam and are spaced apart. The opposite surfaces of the pair of clamping springs 321 are provided with bending surfaces. The distance between the two bending surfaces is smaller than the distance between the two clamped posts 1212. Through the cooperation of the bending surfaces with the clamped posts 1212, the clamping springs 321 are inserted between the two clamped posts 1212 and achieve snap-fit ​​limiting. In use, the elastic force on the clamping spring 321 is overcome, causing the bent surface to disengage from the clamped post 1212, thereby allowing the clamping spring 321 to slide out between the two clamped posts 1212.

[0075] The above design allows the second beam 32 to move relative to the back surface 12 when needed.

[0076] Specifically, when the telescopic beam is in the first working position, the bending surface cooperates with the clamped column 1212 to allow the clamping spring 321 to be inserted between the two clamped columns 1212 and achieve a locking limit. At this time, the pulling arm 311 will only pull the first beam 31 to move.

[0077] Once the telescopic beam needs to be moved to the second working position, first control the upper protruding end 3311 of the locking pin 331 to enter the first limiting hole 313. Then, rotate the handle bar 2, and pull the pulling arm 311 and the first beam 31 in sequence through the connecting body 15. Subsequently, the first beam 31 will apply a pulling force to the second beam 32, causing the second beam 32 to pull the clamping spring 321. Then, overcome the elastic force on the clamping spring 321, so that the bending surface is disengaged from the clamped pin 1212, and the clamping spring 321 slides out from between the two clamped pins 1212, thereby moving the telescopic beam to the second working position.

[0078] Preferably, the telescopic beam is also equipped with an anti-detachment mechanism; The anti-detachment mechanism includes a sliding stop 322 and an L-shaped hook 317 that cooperates with it; The sliding stop 322 is provided on the outer peripheral wall of the second beam 32 near the first beam 31; An L-shaped hook block 317 is provided on the outer periphery of one end of the first beam 31 near the second beam 32. The hook part of the L-shaped hook block 317 is positioned facing the second beam 32. The cooperation between the sliding stop block 322 and the L-shaped hook block 317 restricts the second beam 32 from sliding away from the first beam 31.

[0079] The above design ensures that the second beam 32 and the first beam 31 in the telescopic beam will not detach from each other when they slide relative to each other.

[0080] Specifically, during operation, if the second beam 32 and the first beam 31 slide too fast relative to each other, the upper protruding end 3311 of the locking post 331 may not be able to properly engage with the second limiting hole 314, causing them to detach. However, by cooperating with the sliding stop 322 and the L-shaped hook block 317, the sliding of the second beam 32 away from the first beam 31 can be restricted, thus improving the relative sliding stability between the second beam 32 and the first beam 31.

[0081] The anti-detachment mechanism can also be a long groove and a limiting post that is inserted into the long groove.

[0082] Preferably, the locking mechanism further includes a protective mechanism; The protective mechanism includes a fixing frame 122 disposed on the back 12, the fixing frame 122 being disposed corresponding to the locking post 331, the fixing frame 122 being provided with a long through groove 1222, one end of the long through groove 1222 being open and the other end being closed, the open end of the long through groove 1222 being disposed towards the handrail 2, and the line connecting the midpoint of the open end of the long through groove 1222 to the midpoint of the closed end being parallel to the length direction of the second beam 32 and the first beam 31; The lower end of the locking post 331 is defined as the lower through end 3312, and the open end of the elongated through groove 1222 is provided corresponding to the lower through end 3312; In both the four-wheel upright state and the two-wheel upright state, the lower protruding end 3312 remains embedded in the elongated through groove 1222; In order to enter the four-wheel storage state, the lower protruding end 3312 slides away from the long strip through groove 1222 along the length direction of the second beam 32 and the first beam 31, and the upper protruding end 3311 on the locking post 331 passes through the first limiting hole 313.

[0083] With the above design, the locking post 331 can restrict the position of the first beam 31 and the second beam 32, preventing the first beam 31 and the second beam 32 from continuing to move away from the handrail 2 in the shortened state.

[0084] Specifically, when the trolley is in the four-wheel upright state and the two-wheel upright state, the lower protruding end 3312 of the locking post 331 remains embedded in the long through groove 1222. At this time, even if the first beam 31 applies a pushing force to the second beam 32, the first beam 31 and the second beam 32 will not move arbitrarily because the lower protruding end 3312 abuts against the long through groove 1222.

[0085] In order to enter the four-wheel storage state, the upper protruding end 3311 on the locking post 331 protrudes through the first limiting hole 313. Then, the first beam 31 pulls the second beam 32 (that is, a corresponding pulling force is applied), so that the lower protruding end 3312 slides away from the long through groove 1222 along the length direction of the second beam 32 and the first beam 31.

[0086] Preferably, the locking mechanism further includes a side limiting mechanism; The side limiting mechanism includes a limiter 123 and a locking shaft mating hole 315; The limiter 123 is positioned and connected to the back side 12; The limiter 123 includes a support frame 1231, a limiting pin 1232, a second elastic element 1233, and a pushing part 1611; The support frame 1231 is fixedly installed on the back side 12, and the limiting pin 1232 is provided through the support frame 1231. The axial direction of the limiting pin 1232 is perpendicular to the extension line of the telescopic beam. The limiting pin 1232 is disposed on the periphery of the first beam 31 of the telescopic beam and corresponds to the locking post 331. A fixing block 1234 is positioned and connected on the periphery of the limiting pin 1232. The fixing block 1234 has a first inclined surface 12341. The second elastic element 1233 acts on the limiting pin 1232 so that the limiting pin 1232 always has the tendency to slide axially toward the telescopic beam; The pushing part 1611 is movably disposed on the back surface 12 and is disposed corresponding to the fixing block 1234. The moving direction of the pushing part 1611 is along a direction perpendicular to the back surface 12, and the pushing part 1611 abuts against the first inclined surface 12341. The pushing part 1611 is configured to slide along the first inclined surface 12341 and push the fixing block 1234 and the limiting pin 1232 to move along the axis of the limiting pin 1232. In the four-wheel upright state and the four-wheel retracted state, the first beam 31 and the second beam 32 move relative to each other to the extended state, restricting the end of the locking shaft 1232 from approaching the periphery of the second beam 32 of the telescopic beam; With both wheels upright, the first beam 31 and the second beam 32 move relative to each other to a shortened state, restricting the insertion of the end of the retaining shaft 1232 into the retaining shaft mating hole 315, thereby restricting the relative sliding of the first beam 31 and the second beam 32.

[0087] The above design can prevent the telescopic beam from sliding relative to the first platform 1 when both wheels are upright.

[0088] Specifically, in the four-wheel upright state and the four-wheel retracted state, the first beam 31 and the second beam 32 move relative to each other to the extended state, restricting the end of the retaining shaft 1232 to approach the periphery of the second beam 32 of the telescopic beam. In other words, the end of the retaining shaft 1232 will not jam the second beam 32.

[0089] When the handrail 2 is in the two-wheel upright state, the first beam 31 and the second beam 32 move relative to each other to the shortened state, restricting the insertion of the end of the retaining shaft 1232 into the retaining shaft mating hole 315, so as to restrict the relative sliding of the first beam 31 and the second beam 32.

[0090] Once it is necessary to disengage the end of the limiting pin 1232 from the pin engagement hole 315, the pushing part 1611 is pressed directly. Then, the pushing part 1611 slides along the first inclined surface 12341 and pushes the fixing block 1234 and the limiting pin 1232 to move along the axis of the limiting pin 1232, thereby disengaging the limiting pin 1232 from the pin engagement hole 315. After that, the telescopic beam can slide normally relative to the first platform 1.

[0091] The second elastic element 1233 can be a spring.

[0092] Preferably, the linear guide mechanism includes a linear guide rail 121 positioned and connected to the back surface 12, the linear guide rail 121 extending in a direction parallel to the direction on the first platform 1 from approaching to moving away from the handrail 2; The telescopic beam is slidably connected within the linear guide rail 121. The locking mechanism includes a locking pin 331, which passes through the linear guide rail 121 to limit the sliding of the telescopic beam. The linear guide rail 121 is provided with a structural limiting hole 1211 through which the locking pin 331 passes.

[0093] The linear guide 121 can be a long strip with a cross-section in the shape of a "U". The cross-sections of the first beam 31 and the second beam 32 can also be in the shape of a "U".

[0094] With the above design, the telescopic beam can be restricted to moving only along the linear guide rail 121.

[0095] Preferably, an operation hole 16 is provided on the first platform 1 corresponding to the locking post 331, and a button 161 is movably disposed in the operation hole 16; The button 161 is provided with a push part 1611; The back surface 12 is provided with a third elastic element 1223, which acts on the button 161 to make the button 161 tend to extend out of the operation hole 16.

[0096] The above design enables the locking pin 331 to move up and down repeatedly.

[0097] The third elastic element 1223 can be a spring.

[0098] Specifically, pressing button 161 will push the pusher 1611 down. During this process, the third elastic element 1223 will also lower its position, so that button 161 and pusher 1611 have a tendency to reset. Once button 161 is released, button 161 will quickly reset.

[0099] Preferably, a flap 18 is provided at the end of the first platform 1 away from the handrail 2. The flap 18 is provided on one side of the first pulley 13 and is rotatably connected to the first platform 1. The other side of the flap 18 relative to the first pulley 13 extends as a free end toward the second pulley 14. The back side 12 is provided with a pulley drive mechanism; The pulley drive mechanism includes a linkage mechanism and an elastic reset mechanism. One end of the linkage mechanism is hinged to the end of the telescopic beam near the first pulley 13, and the other end is hinged to the free end of the flap 18. The elastic reset mechanism includes a rotary elastic element disposed on the first platform, the rotary elastic element acting on the first pulley 13 to cause the first pulley 13 to have a tendency to flip to the back side 12; When the handcart is in the four-wheel upright state and the two-wheel upright state, the telescopic beam is in the first working position, and the flap 18 is between the two first pulleys 13 and overcomes the elastic force of the elastic reset mechanism so that the first pulleys 13 are in the upright state. In order to enter the four-wheel storage state, the telescopic beam slides relative to the first platform 1 to the second working position, and pulls the flip plate 18 away from the two first pulleys 13 through the linkage mechanism. The first pulleys 13 flip to the back side 12 under the elastic force of the elastic reset mechanism to enter the flip state.

[0100] Preferably, the rotary elastic element includes a torsion spring sleeve 133 positioned and connected to one end of the first platform 1 away from the handrail 2. The torsion spring sleeve 133 is positioned and connected to the roller seat 134. The torsion spring sleeve 133 acts on the roller seat 134 of the first pulley 13 to give the first pulley 13 a tendency to flip to the back side 12.

[0101] With the above design, the two first pulleys 13 can freely switch between the upright state and the flipped state.

[0102] Specifically, when the handcart is in a four-wheel upright state and a two-wheel upright state, the telescopic beam is in the first working position, and the flap 18 is between the two first pulleys 13 and overcomes the elastic force of the elastic reset mechanism so that the first pulleys 13 are in an upright state. In order to enter the four-wheel storage state, the telescopic beam slides relative to the first platform 1 to the second working position, and pulls the flip plate 18 away from the two first pulleys 13 through the linkage mechanism. The first pulleys 13 flip to the back side 12 under the elastic force of the elastic reset mechanism to enter the flip state.

[0103] When the torsion spring sleeve 133 is working, the torsion spring inside it performs the torsion operation.

[0104] Preferably, the linkage mechanism includes a movable link 124 and a first connecting link 125; The back 12 is provided with the movable connecting rod 124. One end of the movable connecting rod 124 is rotatably connected to the second beam 32 of the telescopic beam through the first connecting rod 125. The first connecting rod 125 passes through the end of the second beam 32 away from the first beam 31, so as to realize the hinge of the second beam 32 relative to the back 12. The other end of the movable connecting rod 124 is hinged to the free end of the flap 18; The first platform 1 is provided with a rotating part 112 at the end away from the handrail 2. The axis of the rotating part 112 is parallel to the length direction of the first platform 1, and the circumference of the rotating part 112 has a plane parallel to the back surface 12. The torsion spring sleeve 133 is positioned and connected to the rotating part 112. The torsion spring sleeve 133 is positioned and connected to the roller seat 134. The roller seat 134 has an approximately U-shaped structure. The opening of the U-shaped structure of the roller seat 134 is positioned and connected to the front pulley body 135. The outer wall of the bottom of the U-shaped structure of the roller seat 134 is provided with a limiting surface 136. In both the four-wheel upright state and the two-wheel upright state, the limiting surface 136 abuts against the peripheral plane of the rotating part 112 to restrict the roller seat 134 to rotate only toward the back side 12.

[0105] With the above design, the flap 18 can be rotated quickly.

[0106] Specifically, when the handcart is in the four-wheel upright state and the two-wheel upright state, the telescopic beam is in the first working position. At this time, the second beam 32 of the telescopic beam will push the flip plate 18 to tilt through the movable connecting rod 124 and be positioned between the two first pulleys 13. At this time, the two first pulleys 13 overcome the elastic force of the elastic reset mechanism under the action of the flip plate 18, so that the first pulleys 13 are in the upright state.

[0107] At this time, the limiting surface 136 of the roller seat 134 abuts against the peripheral plane of the rotating part 112 to restrict the roller seat 134 to rotate only towards the back side 12.

[0108] Once the telescopic beam slides relative to the first platform 1 to the second working position, the second beam 32 of the telescopic beam will gradually level the flip plate 18 through the movable connecting rod 124, and the roller seat 134 will flip to the back side 12 under the elastic force of the torsion spring sleeve 133 to enter the flipped state.

[0109] Preferably, the flap 18 has a pushing surface 181 on the edge corresponding to the first pulley 13; An inclined block 131 is provided on each of the two first pulleys 13 facing each other; In both the four-wheel upright state and the two-wheel upright state, the inclined surface of the inclined block 131 abuts against the pushing sliding surface 181.

[0110] The above design allows the first pulley 13 to quickly enter the upright position.

[0111] When the first pulley 13 is in the flipped state, the pushing sliding surface 181 contacts the inclined surface of the inclined block 131. Once the flip plate 18 is tilted, the pushing sliding surface 181 on the flip plate 18 will push the first pulley 13 into the upright state through the inclined surface of the inclined block 131.

[0112] Preferably, the front end 11 away from the handrail 2 is rotatably connected to a second platform 111, and a protrusion 132 is provided on the side of the two first pulleys 13 facing each other. In the four-wheel storage state, the second platform 111 flips up to be close to the front 11, and the protrusion 132 passes through the hollow hole on the flip plate 18 and out of the second platform 111. The protrusion 132 is configured to limit the handrail 2 that has been flipped up to be close to the front 11.

[0113] The above design allows the position of the second platform 111 to be restricted.

[0114] Specifically, in the four-wheel storage state, the second platform 111 flips up to be close to the front 11, and the protrusion 132 passes through the hollow hole on the flip plate 18 and out of the second platform 111. The protrusion 132 is configured to limit the armrest 2 that has flipped up to be close to the front 11.

[0115] Preferably, the connecting body 15 includes a shaft 151 fixedly mounted on the handrail 2. The axis of the shaft 151 is parallel to the direction on the first platform 1 from near to far from the handrail 2. Two mounting parts 152 are provided around the shaft 151. These two mounting parts 152 are symmetrically and spaced apart with the line connecting the midpoints of the two sides in the width direction of the back surface 12 as the reference axis. Each mounting part 152 is configured to rotate about the rotational connection center axis between the handrail 2 and the first platform 1; The two mounting parts 152 are respectively positioned and connected to the roller seats 134 of the two second pulleys 14.

[0116] With the above design, the connecting body 15 can move together with the two second pulleys 14 when it rotates with the handrail 2, so as to achieve the purpose of the two second pulleys 14 working synchronously with the two first pulleys 13.

[0117] Specifically, when the handrail 2 rotates, the handrail 2 will rotate along with the two mounting parts 152 via the shaft 151.

[0118] In the above scheme, such as Figure 6 , Figure 8 and Figure 9 As shown, a square hole 17 is provided on the surface of the first platform 1 away from the handrail 2. The flap 18 is disposed inside the square hole 17 and is rotatably connected to the inner wall of the square hole 17. The square hole 17 is defined by the end of the first platform 1 away from the handrail 2, the two rotating parts 112, and the rotating end of the flap 18. With the above design, when the flap 18 is flipped to be nearly parallel to the first platform 1, it can be accommodated through the square hole 17, thereby ensuring that the flap 18 is completely embedded inside the first platform 1 in the stored state, without protruding from the surface, and maintaining the overall flat outline.

[0119] In the above scheme, the first platform 1 is provided with an installation notch 19 at its end, and the handrail 2 is rotatably connected in the installation notch 19. With the help of the above design, a structural basis is provided for setting the spacing, so that the handrail 2 always rotates smoothly around the fixed axis during the unfolding and folding process.

[0120] In the above scheme, during actual operation, an approximately elongated receiving space 1221 is formed between the fixing frame 122 and the opposite side surface of the back 12, and the length direction of the receiving space 1221 is perpendicular to the length direction of the second beam 32 and the first beam 31. Two limiters 123 are provided in the accommodating space 1221. These two limiters 123 are symmetrically arranged with the linear guide rail 121 as the center of symmetry to limit the relative sliding between the first beam 31 and the second beam 32. An operation hole 16 is provided on the first platform 1 corresponding to the accommodating space 1221. A button 161 is movably disposed in the operation hole 16. A third elastic element 1223 is provided in the accommodating space 1221, which is positioned and connected to the fixing frame 122 and acts on the button 161, so that the button 161 tends to protrude out of the operation hole 16. The design of the mounting notch 19 provides mounting space for the limiter 123 and the third elastic element 1223.

[0121] In the above scheme, the end of the pull arm 311 is hinged to the rotating sleeve 312 sleeved on the connecting body 15 to realize the positioning connection between the first beam 31 and the handrail 2. With the help of the design of the rotating sleeve 312, the pull arm 311 will not swing.

[0122] In the above scheme, the mounting part 152 in the connecting body 15 is there to make the axis of the second pulley 14 and the axis of the shaft 151 have a gap, so that the lowest point of the wheel surface of the first pulley 13 and the second pulley 14 are coplanar with the same horizontal plane.

[0123] Working principle: With all four wheels upright: like Figure 1 - Figure 8 At this time, both the first pulley 13 and the second pulley 14 are erected, as is the handrail 2. Simultaneously, the first beam 31 and the second beam 32 are in an extended state, and the entire telescopic beam is in the first working position. The flip plate 18 is tilted, and its length extension line, together with the length extension line of the movable connecting rod 124 and the back surface 12, forms a triangular structure. At the same time, the two ends of the flip plate 18 in the length direction respectively approach the roller seat 134 of the two first pulleys 13. At this time, the inclined block 131 will abut against the inclined pushing surface 181, so that the two first pulleys 13 will not move.

[0124] At this time, the positioning of the entire telescopic beam is mainly achieved by the locking post 331. Specifically, the upper protruding end 3311 of the locking post 331 passes through the first limiting hole 313 and extends out of the structural limiting hole 1211 on the linear guide rail 121 to achieve locking in the extended state. The lower protruding end 3312 is located in the elongated through groove 1222 and is at the closed end of the elongated through groove 1222. At the same time, the front pulley body 135 is erected, and the limiting surface 136 abuts against the peripheral outer surface of the rotating part 112 (e.g., Figure 1 and Figure 3 ).

[0125] At the same time, the position of the retaining shaft mating hole 315 is far away from the retaining shaft 1232, so the retaining shaft 1232 will not restrict the first beam 31 and the second beam 32 (e.g. Figure 3 ).

[0126] In other words, the positions of the first beam 31 and the second beam 32 are restricted by the locking post 331, and the two cannot move relative to each other. At the same time, the locking post 331 also ensures that the telescopic beam and the first platform 1 will not move relative to each other by cooperating with the structural limiting hole 1211 and the elongated through groove 1222 on the linear guide rail 121.

[0127] This prevents the handrail 2 from rotating clockwise or counterclockwise.

[0128] When the handrail 2 is pushed to move, due to the insertion and engagement of the structural limiting hole 1211 and the upper through end 3311, the first beam 31 and the second beam 32 cannot be shortened or moved. Therefore, pushing the handrail 2 can move the first platform 1, the first pulley 13 and the second pulley 14 together.

[0129] To enter the two-wheel standing position: like Figures 9-16 Press button 161 directly (at this time, the third elastic element 1223 is compressed, which facilitates the subsequent reset of button 161). Then, button 161 will descend, pushing the upper protruding end 3311 down and gradually disengaging from the structural limiting hole 1211 and the first limiting hole 313. Meanwhile, the lower protruding end 3312 will descend along the elongated through groove 1222 and compress the first elastic element 3313. Subsequently, the operator can release button 161 and rotate the handrail 2 so that the handrail 2 faces the end of the first platform 1. When the outer side is flipped flat, during the rotation of the handrail 2, the upper protruding end 3311 descends and disengages from the structural limiting hole 1211 and the first limiting hole 313, allowing the telescopic beam to shorten. Therefore, the rotating handrail 2 will sequentially push the pull arm 311 and the first beam 31 via the rotating sleeve 312. When the handrail 2 rotates to near horizontal, the second pulley 14 flips to the side of the first platform 1, and the first beam 31 and the second beam 32 move relative to each other to a shortened state, with the entire telescopic beam in the first working position. At this time, the upper protruding end 3311 on the locking post 331 correspondingly protrudes through the second limiting hole 314 (e.g., ...). Figure 11 However, since the second beam 32 did not move, the upper protruding end 3311 of the locking post 331 remained aligned with the structural limiting hole 1211 and protruded from the structural limiting hole 1211.

[0130] Simultaneously, the locking shaft mating hole 315 moves to align with the limiting locking shaft 1232. Then, the second elastic element 1233 pushes the limiting locking shaft 1232 into the locking shaft mating hole 315, further limiting the first beam 31 and the second beam 32 in their shortened state (e.g., ...). Figure 16 ).

[0131] It should be noted that when both wheels are upright, the hinge shaft 316 at the end of the first beam 31 will abut against the second beam 32, so that the relative movement between the second beam 32 and the first beam 31 will not continue.

[0132] To enter the four-wheel storage state: (like Figure 17 - Figure 24 This can be done with both wheels upright. At this time, press button 161 directly. Then, button 161 will descend, pushing the upper protruding end 3311 down and gradually disengaging from the structural limiting hole 1211 and the second limiting hole 314.

[0133] At the same time, the descending button 161 can guide the pushing part 1611 on it to slide along the first inclined surface 12341, so that the fixing block 1234 and the limiting pin 1232 move together away from the pin engagement hole 315 (as long as the button 161 is pressed, the fixing block 1234 and the limiting pin 1232 will move, and at the same time the second elastic element 1233, i.e. the spring, will be compressed), until it disengages from the pin engagement hole 315.

[0134] The handrail 2 can then be flipped to face forward 11. The rotating handrail 2, along with the rotating sleeve 312, the pulling arm 311, and the first beam 31, will move linearly towards the second pulley 14. When the first beam 31 moves to the point where the first limiting hole 313 aligns with the upper protruding end 3311, the first elastic element 3313 will lift the locking pin 331, causing the upper protruding end 3311 of the locking pin 331 to re-enter the structural limiting hole 1211. At this point, the first beam 31 and the second beam 32 reach their extended state. Subsequently, the first beam 31 will apply a pulling force to the second beam 32, causing the second beam 32 to pull. After clamping the spring piece 321, the elastic force on the clamping spring piece 321 is overcome, causing the bent surface to disengage from the clamped column 1212, thereby allowing the clamping spring piece 321 to slide out between the two clamped columns 1212. This causes the telescopic beam to move to the second working position. During this process, the moving second beam 32 will move together with the first connecting rod 125, causing the movable connecting rod 124 to lift the free end of the flap 18, so that the flap 18 gradually enters the square hole 17. At this time, the lower through end 3312 slides out of the elongated through groove 1222, and the upper through end 3311 also moves away from the structural limiting hole 1211 (e.g., Figure 18 ).

[0135] As the flap 18 gradually enters the square hole 17, the pushing surface 181 on the flap 18 will gradually move away from the inclined block 131, causing the torsion spring sleeve 133 to flip towards the back side 12 with the roller seat 134 and the front pulley body 135 until the roller seat 134 approaches the back side 12. Then, the guide second platform 111 presses against the front side 11, and the protrusion 132 passes through the hollow hole on the flap 18 and out of the second platform 111. At this time, the handrail 2 will move until its length extension line is parallel to the front side 11, and the protrusion 132 will limit the handrail 2 that has flipped to approach the front side 11.

[0136] To achieve the four-wheel upright position: Once it is necessary to enter the four-wheel standing state (transition from the four-wheel folding state), the handrail 2 is directly flipped up to stand up. At this time, the flipped handrail 2 will move in a straight line towards the first pulley 13 along with the rotating sleeve 312, the pulling arm 311, the first beam 31 and the second beam 32. When the second beam 32 moves, it will push the movable connecting rod 124 through the first connecting rod 125, so that the movable connecting rod 124 moves the flip plate 18 away from the back 12, and at the same time flips the second platform 111 to stand up.

[0137] When the flip plate 18 moves, it pushes the inclined surface of the inclined block 131 by pushing the sliding surface 181, so that the inclined block 131 carries the roller seat 134 to rotate around the rotating part 112, while the torsion spring sleeve 133 stores power.

[0138] After that, it can enter the four-wheel upright state.

[0139] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A foldable trolley with a sliding groove, characterized in that: The trolley includes a first platform (1) having a front (11) and a back (12) arranged opposite to each other, a handrail (2), an adjustment mechanism (3), a linear guide mechanism, and a connector (15). The handrail (2) is rotatably connected to the end of the first platform (1). The adjustment mechanism (3) is set on the first platform (1) and acts on the handrail (2) to restrict the rotation of the handrail (2). The back (12) is provided with a pair of first pulleys (13) and a pair of second pulleys (14). The line connecting the midpoints of the two sides in the width direction of the back (12) is used as the reference axis. The pair of second pulleys (14) are symmetrically arranged and rotatably connected to the first platform (1) through a connector (15). The pair of second pulleys (14) are set corresponding to the handrail (2). There is a set distance between the axis of the second pulley (14) and the axis of the connector (15). When the handrail (2) is driven to rotate, the connector (15) is configured to drive the second pulley (14) to revolve around the rotation center of the handrail (2). The set distance is the distance that enables the second pulley (14) to achieve ground support or retract to the outer side of the end of the first platform (1) when revolving around the rotation center of the handrail (2). The roller seats (134) of the pair of first pulleys (13) are symmetrically arranged and each is rotatably connected to the first platform (1) in a direction from approaching to moving away from the handrail (2), so that the first pulleys (13) have an upright state and a flipped state; The adjustment mechanism (3) includes a telescopic beam and a locking mechanism; The telescopic beam is disposed on the back (12) and is slidably disposed relative to the first platform (1) by means of a linear guide mechanism. The sliding direction of the telescopic beam relative to the first platform (1) is parallel to the direction on the first platform (1) from near the handrail (2) to away from the handrail (2), so that the telescopic beam has a first working position near the second pulley (14) and a second working position away from the second pulley (14). The end of the telescopic beam away from the first pulley (13) is hinged to the connecting body (15), while the end near the first pulley (13) acts on the two first pulleys (13). The telescopic beam is configured such that when the telescopic beam is in the first working position, the first pulley (13) is in an upright state, and when the telescopic beam is in the second working position, the first pulley (13) is in a flipped state. The telescopic beam can extend and retract along its own length to form an elongated state and a shortened state; The locking mechanism includes a movable locking mechanism and a telescopic locking mechanism. The movable locking mechanism is used to limit the relative sliding between the telescopic beam and the first platform (1), and the telescopic locking mechanism is used to lock the telescopic beam in an extended state or a shortened state. The movable locking mechanism consists of an elastic fastener and a mating component. One of the elastic fastener and the mating component is located at the end of the second beam (32), and the other is located on the back side (12). The handcart has a four-wheel upright state, a two-wheel upright state, and a four-wheel folded-down state. When the trolley is in the four-wheel upright state, the telescopic locking mechanism locks the telescopic beam in the extended state, and the elastic fastener in the movable locking mechanism engages with the mating part to lock the telescopic beam in the first working position, which is used to position it between the first pulley (13) and the second pulley (14) so ​​that the first pulley (13) and the second pulley (14) both support the first platform (1) on the ground. When the handcart changes from a four-wheel upright state to a two-wheel upright state, the telescopic beam is locked in the first working position by the moving locking mechanism, and the telescopic locking mechanism is released from the telescopic locking mechanism to extend the telescopic beam. The handrail (2) is flipped and flattened towards the outside of the end of the first platform (1) by external force, so that the telescopic beam is shortened to the shortened state and locked by the telescopic locking mechanism. At this time, the second pulley (14) moves towards the back (12) and retracts, while the first pulley (13) remains in the ground support state, thus achieving the two-wheel upright state. When the trolley changes from the four-wheel upright state to the four-wheel folded state, the handrail (2) is flipped and brought closer to the front (11) of the first platform (1) by external force, which drives the second pulley (14) to rotate to the outer side of the end of the first platform (1) to realize the folding of the second pulley (14). During this process, the telescopic beam is moved, so that the mating parts overcome the elastic force and disengage from the elastic fastener to unlock, thereby moving the telescopic beam to the second working position, so that the first pulley (13) changes from the upright state to the flipped state, and the four-wheel folded state is achieved.

2. The foldable trolley with a sliding groove according to claim 1, characterized in that: The telescopic beam is composed of a first beam (31) and a second beam (32) nested together. The first beam (31) and the second beam (32) slide relative to each other along the length direction of the telescopic beam to form an elongated state and a shortened state. The mating component includes two symmetrical and spaced clamping posts (1212) disposed on the back side (12), with the axis of the clamping posts (1212) perpendicular to the back side (12). The elastic fastener includes a pair of clamping springs (321). The pair of clamping springs (321) is provided at the end of the second beam (32) away from the first beam (31). The pair of clamping springs (321) is provided at a distance between the two clamped columns (1212). The pair of clamping springs (321) is symmetrical about the line connecting the midpoints of the two sides in the width direction of the telescopic beam and is provided at a distance. The opposite surfaces of the pair of clamping springs (321) are provided with bending surfaces. The distance between the two bending surfaces is smaller than the distance between the two clamped columns (1212). Through the cooperation of the bending surfaces with the clamped columns (1212), the clamping springs (321) are inserted between the two clamped columns (1212) and the clamping is limited. When in use, overcome the elastic force on the clamping spring (321) to disengage the bent surface from the clamped post (1212), thereby allowing the clamping spring (321) to slide out between the two clamped posts (1212).

3. The foldable trolley with a sliding groove according to claim 2, characterized in that: The second beam (32) is hinged to the back side (12) at one end away from the first beam (31) and is slidably connected to the back side (12) via the linear guide mechanism. The direction of the slidable connection is along the direction from the first platform (1) toward the handrail (2). The first beam (31) is hinged to a pull arm (311) at one end away from the second beam (32) via a hinge shaft (316). The end of the pull arm (311) is hinged to the connecting body (15) to achieve the positioning connection between the first beam (31) and the handrail (2).

4. The foldable trolley with a sliding groove according to claim 2 or 3, characterized in that: The telescopic locking mechanism (33) consists of a locking pin (331) and a first limiting hole (313) and a second limiting hole (314) provided on the first beam (31); On the first beam (31), the first limiting hole (313) and the second limiting hole (314) are spaced apart along the length direction of the first beam (31). The line connecting the centers of the first limiting hole (313) and the second limiting hole (314) is parallel to the extension line of the length direction of the first beam (31). The axes of the first limiting hole (313) and the second limiting hole (314) are both parallel to the axis of the locking pin (331). By selectively engaging the locking pin (331) with either the first limiting hole (313) or the second limiting hole (314), the telescopic beam can be switched between the extended state and the shortened state. When the trolley is switched from a four-wheel upright state to a two-wheel upright state, the telescopic beam is in the first working position, and the locking pin (331) cooperates with the second limiting hole (314) to make the telescopic beam in a shortened state.

5. The foldable trolley with a sliding groove according to claim 4, characterized in that: The locking post (331) is set perpendicular to the length direction of the second beam (32) in the vertical direction. The locking post (331) is located in the overlapping area of ​​the second beam (32) and the first beam (31). The upper end of the locking post (331) is defined as the upper through end (3311). The upper through end (3311) passes through the second beam (32) and the first beam (31) and limits the relative sliding of the two. A first elastic element (3313) acts on the locking post (331), so that the upper protruding end (3311) on the locking post (331) always has an upward tendency.

6. The foldable trolley with a sliding groove according to claim 3, characterized in that: The telescopic beam is also equipped with an anti-detachment mechanism; The anti-detachment mechanism includes a sliding stop (322) and an L-shaped hook (317) that cooperates with it. The second beam (32) has a sliding stop (322) on the outer wall of its periphery near the first beam (31); The first beam (31) is provided with an L-shaped hook block (317) on the outer wall of one end near the second beam (32). The hook part of the L-shaped hook block (317) is provided on the side facing the second beam (32). The second beam (32) is restricted from sliding away from the first beam (31) by the cooperation of the sliding stop block (322) and the L-shaped hook block (317).

7. The foldable trolley with a sliding groove according to claim 4, characterized in that: The locking mechanism also includes a protective mechanism; The protective mechanism includes a fixing frame (122) set on the back (12), the fixing frame (122) is set corresponding to the locking post (331), the fixing frame (122) is provided with a long through groove (1222), one end of the long through groove (1222) is open and the other end is closed, the open end of the long through groove (1222) is set towards the handrail (2), and the line connecting the midpoint of the open end of the long through groove (1222) to the midpoint of the closed end is parallel to the length direction of the second beam (32) and the first beam (31); The lower end of the locking post (331) is defined as the lower through end (3312), and the open end of the elongated through groove (1222) is provided corresponding to the lower through end (3312). In both the four-wheel upright state and the two-wheel upright state, the lower protruding end (3312) remains embedded in the elongated through groove (1222); In order to enter the four-wheel storage state, the lower protruding end (3312) slides away from the long strip through groove (1222) along the length direction of the second beam (32) and the first beam (31), and the upper protruding end (3311) on the locking post (331) passes through the first limiting hole (313).

8. The foldable trolley with a sliding groove according to claim 2, characterized in that: The locking mechanism also includes a side limiting mechanism; The side limiting mechanism includes a limiter (123) and a retaining shaft mating hole (315). The limiter (123) is positioned and connected to the back (12). The limiter (123) includes a support frame (1231), a limiting pin (1232), a second elastic element (1233), and a pushing part (1611). The support frame (1231) is fixedly installed on the back (12), and the limiting pin (1232) is provided through the support frame (1231). The axis of the limiting pin (1232) is perpendicular to the extension line of the telescopic beam. The limiting pin (1232) is disposed on the periphery of the first beam (31) of the telescopic beam and corresponds to the locking post (331). A fixing block (1234) is positioned and connected on the periphery of the limiting pin (1232). The fixing block (1234) has a first inclined surface (12341). The second elastic element (1233) acts on the limiting pin (1232) so that the limiting pin (1232) always has the tendency to slide axially toward the telescopic beam; The pushing part (1611) is movably disposed on the back side (12) and is disposed corresponding to the fixing block (1234). The moving direction of the pushing part (1611) is along the direction perpendicular to the back side (12), and the pushing part (1611) abuts against the first inclined surface (12341). The pushing part (1611) is configured to slide along the first inclined surface (12341) and push the fixing block (1234) and the limiting pin (1232) to move along the axis of the limiting pin (1232). In the four-wheel upright state and the four-wheel retracted state, the first beam (31) and the second beam (32) move relative to each other to the extended state, restricting the end of the locking shaft (1232) from approaching the periphery of the second beam (32) of the telescopic beam; When both wheels are in the upright position, the first beam (31) and the second beam (32) move relative to each other to the shortened state, restricting the insertion of the end of the retaining shaft (1232) into the retaining shaft mating hole (315) to restrict the relative sliding of the first beam (31) and the second beam (32).

9. The foldable trolley with a sliding groove according to claim 1 or 3, characterized in that: The linear guide mechanism includes a linear guide rail (121) positioned and connected to the back side (12), the length of the linear guide rail (121) extending parallel to the direction on the first platform (1) from near to far from the handrail (2); The telescopic beam is slidably connected in the linear guide rail (121). The locking mechanism includes a locking post (331), which passes through the linear guide rail (121) to limit the sliding of the telescopic beam. The linear guide rail (121) is provided with a structural limiting hole (1211) through which the locking post (331) passes.

10. The foldable trolley with a sliding groove according to claim 9, characterized in that: An operation hole (16) is provided on the first platform (1) corresponding to the locking post (331), and a button (161) is movably disposed in the operation hole (16). The button (161) is provided with a push part (1611). The back side (12) is provided with a third elastic element (1223), which acts on the button (161) to make the button (161) tend to extend out of the operating hole (16).

Images