Trolley capable of being flatly folded

Abstract

The utility model discloses a cart capable of being flatly folded, and relates to the technical field of outdoor carts. The baby carriage comprises a front and rear main frame assembly, a side cross assembly, a bottom frame assembly, a pull rod assembly, two fast-assembly front wheel assemblies, two fast-assembly rear wheel assemblies and a cloth bag. In order to overcome the defects existing in a cart in the current market, the folding cart is novel in structure, smaller in folding size, attractive in appearance, smaller in packaging size, convenient to stamp and purchase and convenient and fast to disassemble, the wheels and the pull rod can be rapidly and stably installed and disassembled, the whole folding cart is convenient to unfold and fold, and the use is convenient. The front and rear main frames have the maximum width and height, the underframe has good bearing capacity, the length of the pull rod can be adjusted in multiple gears, and the angle can be adjusted.

Description

Technical Field

[0001] The utility model relates to the technical field of outdoor carts, in particular to a flat and foldable cart. Background Art

[0002] With the increase of outdoor sports or travel, more and more people are choosing folding carts that can better carry items as a device to carry luggage when traveling;

[0003] Referring to the “folding cart” with the publication number “CN219619145U”, it can be seen that the patent has an unfolded state and a folded state;

[0004] However, by comparing the diagrams of the patent, it can be seen that the patent has the following technical problems:

[0005] The length after folding is still relatively large, and it is mainly folded flat. The folded volume is large, and it cannot be placed upright, which is inconvenient to place and carry. The packaging size is too large to be convenient for mail order, and the component disassembly structure is complicated and inconvenient;

[0006] Therefore, a new solution to the above problems needs to be proposed. Utility Model Content

[0007] The utility model aims to provide a flat and foldable stroller to solve the technical problems raised in the background technology.

[0008] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a flat and foldable cart, comprising front and rear main frame assemblies, a side cross assembly, a bottom frame assembly, a pull rod assembly, two quick-install front wheel assemblies, two quick-install rear wheel assemblies and a cloth bag;

[0009] The cloth bag is used to be arranged between the front and rear main frame assemblies, the side cross assembly, the bottom frame assembly and the pull rod assembly;

[0010] The height of the side cross assembly after folding does not exceed the height of the front and rear main frame assemblies;

[0011] A side cross assembly and a bottom frame assembly are provided between the front and rear main frame assemblies;

[0012] Two quick-install front wheel assemblies and two quick-install rear wheel assemblies are respectively disposed at the bottom of both ends of the side cross assembly and the bottom of the bottom frame assembly;

[0013] A pull rod assembly is provided at one end of the front and rear main frame assemblies;

[0014] The quick-install front wheel assembly and the quick-install rear wheel assembly can be disassembled and placed between the folded bottom frame assemblies.

[0015] Preferably, the front and rear main frame assemblies include a front main frame part and a rear main frame part, and the front main frame part and the rear main frame part both include a main frame tube, a main frame bottom cross tube and a limiting U-shaped part, the bottom end of the main frame tube is fixedly connected to the main frame bottom cross tube, and a limiting U-shaped part is arranged at one end of the main frame bottom cross tube, and the ends of the limiting U-shaped parts at the front main frame part and the rear main frame part are opposite and symmetrically arranged.

[0016] Preferably, the chassis assembly comprises two bottom brackets and two groups of bottom bracket joints, and the bottom brackets are respectively plugged and fixed at both ends of the bottom bracket joints;

[0017] The chassis joint part includes two joint parts, and the bottom bracket is composed of two joint parts riveted together to form a joint part that can rotate at a certain angle;

[0018] The bottom bracket comprises two bottom bracket main pipes, two bottom bracket transverse pipes and a bottom bracket vertical pipe, a bottom bracket main pipe is welded on both sides of the two bottom bracket transverse pipes respectively, and a bottom bracket vertical pipe is welded between the two bottom bracket transverse pipes;

[0019] One end of the bottom support main pipe is plugged and fixedly connected with a joint piece at one end thereof, and the other end of the bottom support main pipe is connected with the inner side of the limiting U-shaped piece by a pin.

[0020] Preferably, the side cross assembly comprises two cross connecting rods, two cross tubes, two long cross tubes and a middle cross tube;

[0021] The two cross tubes are respectively cross-hinged with the two long cross tubes to form two groups of cross structures, and the upper ends of the cross tubes are connected to cross connecting rods;

[0022] Two of the middle cross tubes are cross-hinged to form a cross structure, the cross structure composed of the middle cross tubes connects the cross structure composed of the cross tube and the long cross tube, the top end of the middle cross tube is hinged to the long cross tube, and the bottom end of the middle cross tube is hinged to the cross tube;

[0023] A cross link is arranged at the top end of the cross tube, one end of the cross link away from the cross tube is rotatably hinged to the upper part of the outer side of the main frame tube, and the long cross tube is rotatably hinged to the lower part of the outer side of the main frame tube.

[0024] Preferably, the side cross assembly comprises two cross connecting rods, two cross tubes, two long cross tubes and a middle cross tube;

[0025] The two cross tubes are respectively cross-hinged with the two long cross tubes to form two groups of cross structures, and the upper ends of the cross tubes are connected to cross connecting rods;

[0026] Two of the middle cross tubes are cross-hinged to form a cross structure, the cross structure composed of the middle cross tubes connects the cross structure composed of the cross tube and the long cross tube, the top end of the middle cross tube is hinged to the cross tube, and the bottom end of the middle cross tube is hinged to the long cross tube;

[0027] A cross link is provided at the bottom end of the cross tube, one end of the cross link away from the cross tube is rotatably hinged to the lower part of the outer side of the main frame tube, and the long cross tube is rotatably hinged to the upper part of the outer side of the main frame tube.

[0028] Preferably, the pull rod assembly comprises a telescopic pull rod group and a rebound connection group;

[0029] The telescopic pull rod assembly comprises a handle, an inner pull rod, a limit plate, a pull rod locking sleeve and an outer pull rod;

[0030] The upper ends of the outer pull rod are provided with snap holes at both sides, the upper ends of the outer pull rod are provided with limit holes at both ends, and the lower end of the outer pull rod is provided with a snap hole at one side. The pull rod locking sleeve is inserted into the upper end of the outer pull rod, and the limit protrusions provided on the inner side of the pull rod locking sleeve cooperate with the limit holes at the outer pull rod to prevent separation.

[0031] An inner rod is inserted into the inner side of the outer rod, and the upper end of the inner rod is riveted and fixed to a handle, and the handle is used to prevent the upper end of the inner rod from being separated from the outer rod from the lower end;

[0032] A limit plate is installed at the lower end of the inner pull rod, and the limit plate is used to prevent the lower end of the inner pull rod from being separated from the pull rod locking sleeve at the upper end of the outer pull rod, so that the inner pull rod is restricted to slide freely up and down within a certain range inside the outer pull rod;

[0033] A double-headed marble is installed at the lower end of the inner pull rod. The double-headed marble can be exposed through the spring hole at the upper end of the outer pull rod, and the double-headed marble can be locked and unlocked by the pull rod locking sleeve.

[0034] Preferably, the rebound connection group includes a pull rod fixing sleeve, a pull rod joint pipe, a rebound spring and a pull rod iron piece;

[0035] The tie rod joint tube is formed by shrinking, and spring holes are preset on both sides of the upper end of the tie rod joint tube, and limit holes are preset on both ends of the upper end of the tie rod joint tube, and bolt holes are preset on both sides of the lower end of the tie rod joint tube;

[0036] The tie rod fixing sleeve is inserted into the upper end of the tie rod joint tube, and snap holes are preset on both sides of the tie rod fixing sleeve;

[0037] The limiting protrusion on the inner side of the tie rod fixing sleeve cooperates with the limiting hole on the tie rod joint pipe to prevent separation, and a double-headed marble is installed on the upper end of the tie rod joint pipe. The double-headed marble on the tie rod joint pipe can be exposed through the buckle hole on the tie rod fixing sleeve;

[0038] The tie rod iron piece is located at the lower end of the tie rod joint pipe, the rebound spring is installed at the lower end of the tie rod joint pipe, and the tie rod joint pipe and the rebound spring are fixed together in the rotation groove of the tie rod iron piece by bolts;

[0039] The middle section protrusion of the rebound spring is against the wall of the tie rod joint pipe, and the ears of the rebound spring are hooked on the left and right ears of the tie rod iron piece rotation groove. The rebound spring is used to provide rebound force when the tie rod joint pipe rotates forward to form a rebound connection group;

[0040] The lower end of the outer pull rod is inserted into the pull rod fixing sleeve and fixed to the spring hole at the lower end of the outer pull rod through the marble exposed at the pull rod fixing sleeve. The bottom end of the pull rod iron piece is fixedly connected to the main frame bottom cross tube of the front main frame part.

[0041] Preferably, the quick-release front wheel assembly comprises a wheel, a wheel clamp, a round wheel axle, a limit spring and a round plug sleeve;

[0042] Round plug sleeves are arranged on the inner sides of the bottom ends of both sides of the main frame tube at the front main frame part;

[0043] The round wheel axle is welded to the upper end of the wheel clamp. After the upper end of the round wheel axle passes through the inner side of the round plug sleeve, it is limited by a limiting spring so that the round wheel axle can rotate in the round plug sleeve without falling off. The wheel is installed in the wheel clamp by bolts.

[0044] Preferably, the quick-release rear wheel assembly comprises a wheel, a wheel clamp, a round wheel axle, a square wheel axle and a square plug sleeve;

[0045] The inner sides of the bottom ends of the two sides of the main frame tube at the rear main frame part are provided with square plug sleeves.

[0046] The square wheel axle is welded to the wheel card to form an integral body. After the upper end of the square wheel axle passes through the insertion hole of the square plug sleeve, it is rebounded and limited by the lift-off piece on the square plug sleeve, so that the square wheel axle will not fall out of the square plug sleeve. The wheel is installed in the wheel card by bolts.

[0047] Compared with the prior art, the beneficial effects of the utility model are:

[0048] In order to solve the above defects of the carts currently on the market, the utility model provides a novel structure, a smaller folded volume, a beautiful appearance, a smaller packaging size and convenient mail order, convenient and easy disassembly of parts, and the wheels and the pull rod can be quickly and firmly installed and disassembled, the overall opening and folding are convenient, the front and rear main frames are of maximum width and height, the bottom frame has good bearing capacity, and the pull rod length is adjustable in multiple gears and the angle is adjustable. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0050] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0051] Figure 2 It is a schematic diagram of the overall structure of the utility model;

[0052] Figure 3 It is a partial structural schematic diagram of the front main frame of the utility model;

[0053] Figure 4 It is a partial structural schematic diagram of the rear main frame of the utility model;

[0054] Figure 5 It is a structural schematic diagram of the chassis assembly of the utility model;

[0055] Figure 6 It is a structural schematic diagram of the chassis joint of the utility model;

[0056] Figure 7 This is a schematic diagram of the structure of a side cross assembly according to the first embodiment of the utility model;

[0057] Figure 8 This is a schematic diagram of the structure of a side cross assembly according to the second embodiment of the present utility model;

[0058] Fig. 9 It is a partial structural schematic diagram of the pull rod assembly of the utility model;

[0059] Fig.10 It is a partial structural schematic diagram of the quick-install front wheel assembly of the utility model;

[0060] Fig.11 It is a partial structural schematic diagram of the quick-install rear wheel assembly of the utility model.

[0061] In the figure: 1. main frame tube; 2. main frame bottom cross tube; 3. limiting U-shaped piece; 4. bottom support main tube; 5. bottom support cross tube; 6. bottom support vertical tube; 7. joint piece; 8. cross connecting rod; 9. cross tube; 10. long cross tube; 11. middle cross tube; 12. handle; 13. inner pull rod; 14. limiting piece; 15. pull rod locking sleeve; 16. outer pull rod; 17. pull rod fixing sleeve; 18. pull rod joint tube; 19. rebound spring; 20. pull rod iron piece; 21. wheel; 22. wheel clamp; 23. round wheel axle; 24. limiting retaining spring; 25. round plug sleeve; 26. square wheel axle; 27. square plug sleeve; 28. front and rear main frame assemblies; 29. ​​side cross assembly; 30. bottom frame assembly; 31. pull rod assembly; 32. quick-release front wheel assembly; 33. quick-release rear wheel assembly. DETAILED DESCRIPTION

[0062] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0063] Embodiment 1:

[0064] See also Figure 1 - Figure 7 , Fig. 9 - Fig.11 , a flat foldable stroller, comprising front and rear main frame assemblies 28, side cross assemblies 29, a bottom frame assembly 30, a pull rod assembly 31, two quick-install front wheel assemblies 32, two quick-install rear wheel assemblies 33 and a cloth bag;

[0065] The cloth bag is used to be arranged between the front and rear main frame components 28, the side cross components 29, the bottom frame component 30 and the pull rod component 31;

[0066] The height of the side cross assembly 29 after folding does not exceed the height of the front and rear main frame assemblies;

[0067] A side cross assembly 29 and a bottom frame assembly 30 are provided between the front and rear main frame assemblies 28;

[0068] Two quick-install front wheel assemblies 32 and two quick-install rear wheel assemblies 33 are respectively disposed at the bottom of both ends of the side cross assembly 29 and the bottom of the bottom frame assembly 30;

[0069] A pull rod assembly 31 is provided at one end of the front and rear main frame assembly 28;

[0070] The quick-install front wheel assembly 32 and the quick-install rear wheel assembly 33 can be disassembled and placed between the folded bottom frame assemblies 30 .

[0071] The front and rear main frame assemblies 28 include a front main frame part and a rear main frame part, both of which include a main frame tube 1, a main frame bottom cross tube 2 and a limiting U-shaped part 3. The bottom end of the main frame tube 1 is fixedly connected to the main frame bottom cross tube 2, and a limiting U-shaped part 3 is arranged at one end of the main frame bottom cross tube 2. The ends of the limiting U-shaped part 3 at the front main frame part and the rear main frame part are opposite and symmetrically arranged.

[0072] The chassis assembly 30 comprises two bottom brackets and two sets of bottom bracket joints, and the bottom brackets are respectively inserted and fixed at both ends of the bottom bracket joints;

[0073] The bottom frame joint part includes two joint parts 7, and the bottom bracket is formed by riveting the two joint parts 7 to form a joint part that can rotate at a certain angle;

[0074] The bottom bracket includes two bottom bracket main pipes 4, two bottom bracket transverse pipes 5 and a bottom bracket vertical pipe 6. A bottom bracket main pipe 4 is welded to both sides of the two bottom bracket transverse pipes 5, and a bottom bracket vertical pipe 6 is welded between the two bottom bracket transverse pipes 5.

[0075] One end of the bottom supporting main pipe 4 is plugged and fixedly connected to the joint member 7 at one end thereof, and the other end of the bottom supporting main pipe 4 is connected to the inner side of the limiting U-shaped member 3 by a pin.

[0076] The side cross assembly 29 includes two cross links 8, two cross tubes 9, two long cross tubes 10 and a middle cross tube 11;

[0077] The two cross tubes 9 are respectively cross-hinged with the two long cross tubes 10 to form two groups of cross structures, and the upper ends of the cross tubes 9 are connected to the cross connecting rods 8;

[0078] Two middle cross tubes 11 are cross-hinged to form a cross structure. The cross structure composed of the middle cross tubes 11 connects the cross structure composed of the cross tube 9 and the long cross tube 10. The top end of the middle cross tube 11 is hinged to the long cross tube 10, and the bottom end of the middle cross tube 11 is hinged to the cross tube 9.

[0079] A cross link 8 is provided at the top end of the cross tube 9 , and one end of the cross link 8 away from the cross tube 9 is rotatably hinged to the upper part of the outer side of the main frame tube 1 , and the long cross tube 10 is rotatably hinged to the lower part of the outer side of the main frame tube 1 .

[0080] The pull rod assembly 31 includes a telescopic pull rod group and a rebound connection group;

[0081] The telescopic pull rod assembly includes a handle 12, an inner pull rod 13, a limit plate 14, a pull rod locking sleeve 15 and an outer pull rod 16;

[0082] There are snap holes on both sides of the upper end of the outer pull rod 16, and limit holes are preset at both ends of the upper end of the outer pull rod 16. One side of the lower end of the outer pull rod 16 is preset with a snap hole. The pull rod locking sleeve 15 is inserted into the upper end of the outer pull rod 16, and the limit protrusions arranged on the inner side of the pull rod locking sleeve 15 cooperate with the limit holes at the outer pull rod 16 to prevent separation.

[0083] An inner rod 13 is inserted into the inner side of the outer rod 16, and the upper end of the inner rod 13 is riveted and fixed to the handle 12, and the handle 12 is used to prevent the upper end of the inner rod 13 from being separated from the outer rod 16 from the lower end;

[0084] A limit plate 14 is installed at the lower end of the inner pull rod 13, and the limit plate 14 is used to prevent the lower end of the inner pull rod 13 from being separated from the pull rod locking sleeve 15 at the upper end of the outer pull rod 16, so that the inner pull rod 13 is restricted to slide freely up and down within a certain range in the outer pull rod 16;

[0085] A double-headed marble is installed at the lower end of the inner pull rod 13. The double-headed marble can be exposed through the spring hole at the upper end of the outer pull rod 16, and the double-headed marble can be locked and unlocked by the pull rod locking sleeve 15.

[0086] The rebound connection group includes a pull rod fixing sleeve 17, a pull rod joint pipe 18, a rebound spring 19 and a pull rod iron piece 20;

[0087] The tie rod joint tube 18 is formed by shrinking, and spring holes are preset on both sides of the upper end of the tie rod joint tube 18, and limit holes are preset on both ends of the upper end of the tie rod joint tube 18, and bolt holes are preset on both sides of the lower end of the tie rod joint tube 18;

[0088] The tie rod fixing sleeve 17 is inserted into the upper end of the tie rod joint tube 18, and snap holes are preset on both sides of the tie rod fixing sleeve 17;

[0089] The limiting protrusion on the inner side of the tie rod fixing sleeve 17 cooperates with the limiting hole at the tie rod joint tube 18 to prevent separation. A double-headed marble is installed at the upper end of the tie rod joint tube 18. The double-headed marble at the tie rod joint tube 18 can be exposed through the buckle hole at the tie rod fixing sleeve 17.

[0090] The tie rod iron piece 20 is located at the lower end of the tie rod joint tube 18, and the rebound spring 19 is installed at the lower end inside the tie rod joint tube 18. The tie rod joint tube 18 and the rebound spring 19 are fixed together in the rotation groove of the tie rod iron piece 20 by bolts;

[0091] The middle section of the rebound spring 19 protrudes against the wall of the tie rod joint tube 18, and the two ears of the rebound spring 19 are hooked on the left and right ears of the rotating groove of the tie rod iron piece 20. The rebound spring 19 is used to provide a rebound force when the tie rod joint tube 18 rotates forward to form a rebound connection group;

[0092] The lower end of the outer pull rod 16 is inserted into the pull rod fixing sleeve 17, and is fixed to the spring hole at the lower end of the outer pull rod 16 through the marble exposed at the pull rod fixing sleeve 17. The bottom end of the pull rod iron piece 20 is fixedly connected to the main frame bottom cross tube 2 of the front main frame part.

[0093] The quick-install front wheel assembly 32 includes a wheel 21, a wheel clamp 22, a round wheel axle 23, a limit spring 24 and a round plug sleeve 25;

[0094] Round plug sleeves 25 are provided on the inner sides of the bottom ends of both sides of the main frame pipe 1 at the front main frame part;

[0095] The round wheel axle 23 is welded to the upper end of the wheel clamp 22. The upper end of the round wheel axle 23 passes through the inner side of the round plug sleeve 25 and is limited by the limiting spring 24, so that the round wheel axle 23 can rotate in the round plug sleeve 25 without falling off. The wheel 21 is installed in the wheel clamp 22 by bolts.

[0096] The quick-install rear wheel assembly 33 includes a wheel 21, a wheel clamp 22, a round wheel axle 23, a square wheel axle 26 and a square plug sleeve 27;

[0097] A square plug sleeve 27 is provided on the inner side of the bottom end of both sides of the main frame tube 1 at the rear main frame part.

[0098] The square wheel axle 26 is welded to the wheel card 22 to form an integral body. After the upper end of the square wheel axle 26 passes through the insertion hole of the square plug sleeve 27, it is rebounded and limited by the lift-off piece on the square plug sleeve 27, so that the square wheel axle 26 will not fall out of the square plug sleeve 27. The wheel 21 is installed in the wheel card 22 by bolts.

[0099] The front and rear corresponding fixed stamped inner protrusions preset on the wall of the main frame tube 1 cooperate with the front and rear corresponding grooves preset on the wall of the square wheel shaft 26 and the square plug sleeve 27, thereby fixing the two quick-install front wheel assemblies 32 and the two quick-install rear wheel assemblies 33 on the frame.

[0100] Embodiment 2:

[0101] See also Figure 8 , based on the above embodiment, another arrangement of the side cross assembly 29 is further disclosed;

[0102] The side cross assembly 29 includes two cross links 8, two cross tubes 9, two long cross tubes 10 and a middle cross tube 11;

[0103] The two cross tubes 9 are respectively cross-hinged with the two long cross tubes 10 to form two groups of cross structures, and the upper ends of the cross tubes 9 are connected to the cross connecting rods 8;

[0104] Two middle cross tubes 11 are cross-hinged to form a cross structure. The cross structure composed of the middle cross tubes 11 connects the cross structure composed of the cross tube 9 and the long cross tube 10. The top end of the middle cross tube 11 is hinged to the cross tube 9, and the bottom end of the middle cross tube 11 is hinged to the long cross tube 10.

[0105] A cross link 8 is provided at the bottom end of the cross tube 9 , and one end of the cross link 8 away from the cross tube 9 is rotatably hinged to the lower part of the outer side of the main frame tube 1 , and the long cross tube 10 is rotatably hinged to the upper part of the outer side of the main frame tube 1 .

[0106] In the above two embodiments, when fully folded, the two quick-install front wheel assemblies 32, the two quick-install rear wheel assemblies 33 and the telescopic pull rod assembly 31 are separated from the frame. They are stored in the main frame and do not occupy more packaging volume. When unfolded for use, the two quick-install front wheel assemblies 32 and the two quick-install rear wheel assemblies 33 can be quickly installed at the lower end of the main frame tube 1 of the front and rear main frames, and the telescopic pull rod assembly is quickly connected to the connecting assembly of the pull rod assembly through a snap.

[0107] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

Claims

1. A flat foldable cart, characterized in that: It comprises front and rear main frame assemblies (28), a side cross assembly (29), a bottom frame assembly (30), a pull rod assembly (31), two quick-install front wheel assemblies (32), two quick-install rear wheel assemblies (33) and a cloth bag; The cloth bag is used to be arranged between the front and rear main frame components (28), the side cross component (29), the bottom frame component (30) and the pull rod component (31); The height of the side cross assembly (29) after folding does not exceed the height of the front and rear main frame assemblies (28); A side cross assembly (29) and a bottom frame assembly (30) are arranged between the front and rear main frame assemblies (28); Two quick-install front wheel assemblies (32) and two quick-install rear wheel assemblies (33) are respectively arranged at the bottom of both ends of the side cross assembly (29) and the bottom of the bottom frame assembly (30); A pull rod assembly (31) is provided at one end of the front and rear main frame assemblies (28); The quick-install front wheel assembly (32) and the quick-install rear wheel assembly (33) can be disassembled and placed between the folded bottom frame assemblies (30).

2. A flat-foldable stroller according to claim 1, characterized in that: The front and rear main frame assemblies (28) include a front main frame portion and a rear main frame portion, each of which includes a main frame tube (1), a main frame bottom cross tube (2) and a limiting U-shaped member (3), the bottom end of the main frame tube (1) is fixedly connected to the main frame bottom cross tube (2), one end of the main frame bottom cross tube (2) is provided with a limiting U-shaped member (3), and the ends of the limiting U-shaped member (3) at the front main frame portion and the rear main frame portion are opposite and symmetrically arranged.

3. A flat-foldable stroller according to claim 2, characterized in that: The chassis assembly (30) comprises two bottom brackets and two groups of bottom bracket joints, and the bottom brackets are respectively inserted and fixed at both ends of the bottom bracket joints; The chassis joint part comprises two joint parts (7), and the bottom bracket is composed of two joint parts (7) riveted together to form a joint part that can rotate at a certain angle; One end of the bottom supporting main pipe (4) is plugged and fixedly connected to a joint piece (7) at one end thereof, and the other end of the bottom supporting main pipe (4) is connected to the inner side of the limiting U-shaped piece (3) by means of a pin.

4. A flat-foldable stroller according to claim 3, characterized in that: The side cross assembly (29) comprises two cross connecting rods (8), two cross tubes (9), two long cross tubes (10) and a middle cross tube (11); The two cross tubes (9) are respectively cross-hinged with the two long cross tubes (10) to form two groups of cross structures, and the upper ends of the cross tubes (9) are connected to the cross connecting rods (8); Two of the middle cross tubes (11) are cross-hinged to form a cross structure, the cross structure composed of the middle cross tubes (11) connects the cross structure composed of the cross tube (9) and the long cross tube (10), the top end of the middle cross tube (11) is hinged to the long cross tube (10), and the bottom end of the middle cross tube (11) is hinged to the cross tube (9); A cross link (8) is provided at the top end of the cross tube (9), and one end of the cross link (8) away from the cross tube (9) is rotatably hinged to the upper part of the outer side of the main frame tube (1), and the long cross tube (10) is rotatably hinged to the lower part of the outer side of the main frame tube (1).

5. A flat-foldable stroller according to claim 3, characterized in that: The side cross assembly (29) comprises two cross connecting rods (8), two cross tubes (9), two long cross tubes (10) and a middle cross tube (11); The two cross tubes (9) are respectively cross-hinged with the two long cross tubes (10) to form two groups of cross structures, and the upper ends of the cross tubes (9) are connected to the cross connecting rods (8); Two of the middle cross tubes (11) are cross-hinged to form a cross structure, the cross structure composed of the middle cross tubes (11) connects the cross structure composed of the cross tube (9) and the long cross tube (10), the top end of the middle cross tube (11) is hinged to the cross tube (9), and the bottom end of the middle cross tube (11) is hinged to the long cross tube (10); A cross link (8) is provided at the bottom end of the cross tube (9), and one end of the cross link (8) away from the cross tube (9) is rotatably hinged to the lower part of the outer side of the main frame tube (1), and the long cross tube (10) is rotatably hinged to the upper part of the outer side of the main frame tube (1).

6. A flat-foldable stroller according to claim 1, characterized in that: The pull rod assembly (31) comprises a telescopic pull rod group and a rebound connection group; The telescopic pull rod assembly comprises a handle (12), an inner pull rod (13), a limiting plate (14), a pull rod locking sleeve (15) and an outer pull rod (16); The pull rod locking sleeve (15) is inserted into the upper end of the outer pull rod (16); An inner pull rod (13) is inserted into the inner side of the outer pull rod (16), and the upper end of the inner pull rod (13) is riveted and fixed to the handle (12); A limiting plate (14) is installed at the lower end of the inner pull rod (13); A double-headed marble is installed at the lower end of the inner pull rod (13), and the double-headed marble can be exposed through the snap hole at the upper end of the outer pull rod (16), and the double-headed marble can be locked and unlocked by the pull rod locking sleeve (15).

7. A flat-foldable stroller according to claim 6, characterized in that: The rebound connection group comprises a pull rod fixing sleeve (17), a pull rod joint pipe (18), a rebound spring (19) and a pull rod iron piece (20); The pull rod fixing sleeve (17) is inserted into the upper end of the pull rod joint tube (18); The tie rod iron piece (20) is located at the lower end of the tie rod joint tube (18), and the rebound spring (19) is installed at the lower end inside the tie rod joint tube (18). The tie rod joint tube (18) and the rebound spring (19) are fixed together in the rotation groove of the tie rod iron piece (20) by bolts.

8. A flat-foldable stroller according to claim 2, characterized in that: The quick-install front wheel assembly (32) comprises a wheel (21), a wheel clamp (22), a round wheel axle (23), a limit spring (24) and a round plug sleeve (25); Round plug sleeves (25) are arranged on the inner sides of the bottom ends of both sides of the main frame tube (1) at the front main frame part; The round wheel axle (23) is welded to the upper end of the wheel clamp (22); the upper end of the round wheel axle (23) passes through the inner side of the round plug sleeve (25) and is limited by a limit spring (24), so that the round wheel axle (23) can rotate in the round plug sleeve (25) and will not fall off; the wheel (21) is installed in the wheel clamp (22) by bolts.

9. A flat-foldable stroller according to claim 2, characterized in that: The quick-install rear wheel assembly (33) comprises a wheel (21), a wheel clamp (22), a round wheel axle (23), a square wheel axle (26) and a square plug sleeve (27); A square plug sleeve (27) is provided on the inner side of the bottom end of both sides of the main frame tube (1) at the rear main frame part. The square wheel axle (26) is welded to the wheel clamp (22) to form an integral body. After the upper end of the square wheel axle (26) passes through the insertion hole of the square plug sleeve (27), it is rebounded and limited by the flap on the square plug sleeve (27), so that the square wheel axle (26) will not fall out of the square plug sleeve (27). The wheel (21) is installed in the wheel clamp (22) by bolts.

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