Small-sized folding bicycle, carrying device thereof and multifunctional small-sized folding bicycle comprising small-sized folding bicycle and carrying device

Abstract

The utility model discloses a small-sized folding bicycle, a carrying device thereof and a multifunctional small-sized folding bicycle comprising the small-sized folding bicycle and the carrying device, and solves the problems that in the prior art, old people cannot ride the bicycle conveniently, the bicycle is inconvenient to drag after being folded, more objects cannot be carried when the bicycle is dragged and ridden, and the bicycle is inconvenient to enter places such as subways, buses, shopping centers and the like. A small folding bicycle is characterized by comprising a folding bicycle frame, a guiding system, a braking system, a pedal chain wheel transmission assembly and a seat cushion. The small folding bicycle carrying device comprises a carrying vehicle and a carrying vehicle quick connecting and fixing device, the carrying vehicle comprises a carrying vehicle frame and a carrying bag, and a folded small folding bicycle can be loaded into the small folding bicycle carrying device; a multifunctional small folding bicycle comprises a small folding bicycle body, a small folding bicycle carrying device and auxiliary wheels. The method has high economic value and social value.

Description

Technical Field

[0001] The utility model belongs to the field of bicycles, and particularly relates to a small folding bicycle, a carrying device thereof, and a multifunctional small folding bicycle including both of them. Background Art

[0002] The existing folding bicycles in current life have the following problems: 1. When people go from their residences and workplaces to take the subway or bus, there is still a long way to go. Subways everywhere have strict requirements on the length, width, height, volume, and weight of objects that can enter. Many need to be packaged before entering the subway. For example, the Hangzhou Subway stipulates that the sum of the length, width, and height shall not exceed 1.8 meters, and it must have safety packaging to enter the subway. This requires a folding bicycle that can enter the subway to facilitate people's travel. Few existing folding bicycles can meet the conditions for entering subways everywhere and are also convenient to carry; either the volume and weight after folding are too large and not small enough, or they cannot be easily towed and carried after folding, or the packaging is inconvenient. 2. In many new communities now, since the shopping places are far away, when many people buy a large amount of groceries or do shopping, they often need to walk to the supermarket with a shopping cart, which brings inconvenience; generally, the existing folding bicycles can only be carried by hand after folding, cannot be towed using wheels or are inconvenient to tow, or cannot carry many items when towing or are inconvenient to carry items when riding, and the amount of items that can be carried when riding is very small and the fixation of the carried items is inconvenient, still unable to meet people's needs. 3. Now there are more and more elderly people, and cities are getting bigger and bigger. They need to go out for activities, travel, and shopping frequently. How to travel and shop safely and conveniently for the elderly is a problem. For the existing two-wheel folding bicycles, due to the unstable center of gravity when encountering situations during riding and the slow reaction of the elderly, they are more likely to fall and get injured. 4. When parents take their children to shopping and entertainment centers, since children are inconvenient to move, they often need to be carried by adults. Some use baby carriages, but they always need to walk back and forth. Those who are far from the shopping and entertainment centers will be more tired. The existing folding bicycles still cannot meet the needs of taking children to shopping and entertainment centers. If the problems existing in the above-mentioned folding bicycles can be solved simultaneously, it will bring great convenience to people's going out for activities, travel, and shopping. Summary of the Invention

[0003] To solve the above problems, a small folding bicycle, its load-carrying device, and a multifunctional small folding bicycle incorporating both are invented herein. The small folding bicycle has a small volume after folding, can be conveniently placed in the load-carrying vehicle carried along with the bicycle for quick packaging, and can enter places such as subways, buses, etc. The multifunctional small folding bicycle is convenient to fold, has a small volume after folding, is easy to store, can be towed with less effort and is convenient to carry. When towing and riding, it can carry a relatively large number of items and can be used as a shopping cart for grocery shopping. As a load-carrying tool and means of transportation for people going out or for grocery shopping, when adopting a double-rear-wheel structure, it is especially suitable for the elderly. When needed, it can also carry children, especially when entering shopping centers. The technical problems solved by the present utility model are: the problem that the existing small folding bicycles are inconvenient to enter subways and buses, the problem that they are not suitable for the elderly to ride and are inconvenient to tow and carry after folding, the problem that they cannot carry a large amount of load when towing, pushing, and riding and are inconvenient to enter and exit shopping and entertainment centers, and the problem that it is inconvenient to take children into shopping centers.

[0004] Without special instructions, the directional descriptions in the present utility model, such as front, rear, left, right, up, down, etc., are all referenced with a person sitting on the small folding bicycle facing directly forward.

[0005] The technical solution adopted by the present utility model to solve its technical problems is: a folding frame, which includes a main bracket, a seat bracket, hinge A, hinge B, and a head tube. The main bracket and the seat bracket are in a tubular form.

[0006] There are two solutions for the main bracket. Solution one is that it is a main bracket A; solution two is that it is composed of a first part of the main bracket and a second part of the main bracket. The first part of the main bracket can slide telescopically relative to the second part of the main bracket. Specifically, the first part of the main bracket can telescopically enter and exit the second part of the main bracket. A locking device A is provided at the connection between the second part of the main bracket and the first part of the main bracket. Specifically, the locking device A is a seat tube clamp A, which is used to lock the state after the first part of the main bracket is telescoped.

[0007] The seat bracket is composed of a seat post, a seat tube, and a locking device B. The seat post can telescopically enter and exit the seat tube. A locking device B is provided at the connection between the seat tube and the seat post. The locking device B is a seat tube clamp B, which is used to lock the state after the seat post is telescoped.

[0008] One end of hinge A is connected to the head tube or connected to the head tube through a connecting piece, and the other end of hinge A is connected to the head of main bracket A or connected to the head of main bracket A through a connecting piece; or the other end of hinge A is connected to the head of the first part of the main bracket or connected to the head of the first part of the main bracket through a connecting piece. The head tube can be folded backward or unfolded forward relative to the main bracket through hinge A. Hinge A is a self-locking hinge with a limiting and locking device at the maximum unfolding angle to ensure that the bicycle steering system is in the best position during riding when it is fully unfolded again after folding. The maximum unfolding angle of hinge A is the state during riding; hinge A also has a folding position limiting and locking device after folding in place backward. Specifically, when the front wheel of the bicycle steering system in the folding frame application is folded to be close to or adjacent to the tail of the main bracket, hinge A is locked. This is to prevent the front wheel from sagging under the action of gravity when dragging the small folding bicycle with the rear wheel by holding the bicycle handlebar or seat cushion after the small folding bicycle with this folding frame is fully folded, which affects the dragging, and can minimize the size of the small folding bicycle in the front-rear direction after folding;

[0009] The lower end of hinge B is connected to the tail of main bracket A or connected to the tail of main bracket A through a connecting piece, or the lower end of hinge B is connected to the second part of the main bracket or connected to the second part of the main bracket through a connecting piece. The upper end of hinge B is connected to the lower end of the seat tube. Hinge B is a self-locking hinge with a folding position limiting and locking device after folding in place backward. After hinge B is locked, the seat post bracket cannot be folded. At this time, the seat post bracket is equivalent to a straight tube connected to the main bracket. After hinge B is unlocked, the seat post bracket can be folded forward through hinge B. After the seat post bracket is folded forward, it is above the main bracket; the seat post bracket connected to hinge B has a position limit and lock when folded in place backward, so that the seat post bracket can quickly return to the best riding state when the small folding bicycle is unfolded after folding.

[0010] When the folding frame is applied, the upper end of the seat post is connected to the seat cushion, and the tail of the main bracket A or the tail of the second part of the main bracket is connected and fixed to the rear wheel assembly, and the head tube is connected to the bicycle steering system.

[0011] Hinge A has the following solutions: Solution 1 of Hinge A is a hinge with the same structure as a commercially available 0-180° fishing chair backrest gear regulator; it includes two gear folding components A and B with the same structure. Gear folding component A has a gear disk A provided at the head of rotating arm A, and gear folding component B has a gear disk B provided at the head of rotating arm B. Two objects are connected by rotating arm A and rotating arm B, allowing folding rotation between the two. The concave and convex teeth on the outer circumference of gear disk A and gear disk B are mutually embedded, and a fixing screw passes through the central holes of gear disk A and gear disk B, and cooperates with a fixing nut to connect and fix gear disk A and gear disk B. When it is necessary to adjust the folding angle between gear folding component A and gear folding component B, the fixing screw can be loosened, rotating arm A or rotating arm B can be rotated, and then locked by the fixing screw. The locking and unlocking connectors are connected to the head of the fixing screw, facilitating manual locking and unlocking.

[0012] The second solution of hinge A is a hinge with the same principle as the commercially available hinge with locking and unlocking operations on the side of the hinge and a 90-degree foldable self-locking hinge, and a slight modification is made on this basis; it includes two rotating shafts, rotating shaft A and rotating shaft B connect the left and right sides of two U-shaped groove objects A and B of different sizes, forming a hinge. Rotating shaft A and rotating shaft B are coaxial, and the folding angle and locking of the hinge are changed by a locking and unlocking shaft that can slide along an arc-shaped sliding groove. The locking and unlocking shaft is composed of two shafts, locking and unlocking shaft A and locking and unlocking shaft B. Locking and unlocking shaft B consists of three sections. There is a left-end round hole of locking and unlocking shaft B in the center of the left-section shaft of locking and unlocking shaft B. An annular snap ring groove A is provided in the middle of the left-section shaft of locking and unlocking shaft B. The right-section shaft of locking and unlocking shaft B is the thickest at the operating end, like a small disc, and the middle-section shaft of locking and unlocking shaft B is the thinnest. One end of locking and unlocking shaft A is connected to the left end of U-shaped groove object A. The left-section shaft of locking and unlocking shaft B can just pass through the 90-degree folding locking hole on U-shaped groove object B and at the same time pass through the through hole on U-shaped groove object A with the same size as the 90-degree folding locking hole, and the outside of the other end of locking and unlocking shaft A can just be sleeved with a spring A and then inserted into the left-end round hole of locking and unlocking shaft B. The right end of spring A abuts against the left end of locking and unlocking shaft B. The locking and unlocking shaft is installed by snapping a snap ring into the annular snap ring groove A of locking and unlocking shaft B on the inner side of the right end of U-shaped groove object A. The 90-degree folding locking hole is connected to the arc-shaped sliding groove. The width of the arc-shaped sliding groove is smaller than the diameter of the left-section shaft of locking and unlocking shaft B and larger than the diameter of the middle-section shaft of locking and unlocking shaft B; when the hinge is folded 90 degrees, a 90-degree folding locking hole is provided on U-shaped groove object B on one side of the two U-shaped groove objects. The left-section shaft of locking and unlocking shaft B can just pass through the 90-degree folding locking hole to lock the hinge when it is folded 90 degrees. The left-section shaft of locking and unlocking shaft B is larger than the width of the arc-shaped sliding groove and cannot slide along the arc-shaped sliding groove. If unlocking is required, then by pressing the right-section shaft of locking and unlocking shaft B, the right-section shaft of locking and unlocking shaft B retracts. At this time, the middle-section shaft of locking and unlocking shaft B, which is the thin shaft, is located in the arc-shaped sliding groove, so that the locking and unlocking shaft can slide in the arc-shaped sliding groove to change the folding angle; now a slight modification is made on this basis. As long as when the hinge is folded to the angle that needs to be locked, the position in the arc-shaped sliding groove where the locking and unlocking shaft is located is provided with a locking hole of the same size as the 90-degree folding locking hole, then it can be locked. If locking is required at a position greater than 90 degrees, as long as the arc-shaped sliding groove is lengthened, the original 90-degree folding locking hole set at 90 degrees of folding is changed to a locking hole of the same size at the end of the lengthened arc-shaped sliding groove. This position is also the position of the maximum unfolding angle of the hinge. The end of the arc-shaped sliding groove limits the maximum unfolding angle; two objects are connected through the bottom of U-shaped groove object A and the bottom of U-shaped groove object B and allow folding rotation between the two.

[0013] Hinge A, Solution 3: The unlocking operating handle on the market is in the middle of the hinge. It is a hinge with the same structure as the 0-90-180 degree folding self-locking hinge, with slight modifications on this basis. It is connected by two rotating shafts, Rotating Shaft C and Rotating Shaft D, on the left and right sides of two U-shaped groove objects C and U-shaped groove object D, one large and one small, to form a hinge. Rotating Shaft C and Rotating Shaft D are coaxial. On the left and right sides of U-shaped groove object C, there is a sliding groove respectively. A locking rod passes through the left and right sliding grooves. The two ends of the locking rod are connected to the two ends of a U-shaped connecting piece. The bottom of the U-shaped connecting piece is connected to a rectangular unlocking operating handle. The locking rod is also connected to the bottom of U-shaped groove object C through two locking rod tension springs on the left and right. On the left and right sides of U-shaped groove object D, according to the folding angle requirements, there are symmetrically arranged a folding 0-degree groove, a folding 90-degree locking groove, and a folding 180-degree locking groove. Now the folding 0-degree groove is not as large as the folding 90-degree locking groove and the folding 180-degree locking groove. Therefore, the hinge cannot be locked by the locking rod like when folding at 90 degrees and 180 degrees. When the folding angle between U-shaped groove object C and U-shaped groove object D is 180 degrees, the locking rod is stuck in the folding 180-degree locking groove under the action of the locking rod tension spring and is locked, and the hinge cannot be folded. At this time, only by pressing the unlocking operating handle, the locking rod slides along the sliding groove and leaves the folding 180-degree locking groove, and then the hinge can be folded. The locking principle when the hinge is folded to 90 degrees is the same. Now, as long as slight modifications are made on the basis of this self-locking hinge: when folding to the angle that needs to be locked, locking grooves as large as the folding 90-degree locking groove are arranged on the left and right sides of U-shaped groove object D, and the hinge can be locked at this folding angle; the bottom of U-shaped groove object C and the bottom of U-shaped groove object D are used to connect two objects and allow folding rotation between them.

[0014] Hinge B has the following solutions: Hinge B, Solution 1: It is a self-locking hinge with the same folding structure as the folding handlebar of a folding electric vehicle or a folding bicycle; Hinge B, Solution 2: It is a self-locking hinge with the same structure as Hinge A, Solution 1; Hinge B, Solution 3: It is a self-locking hinge with the same structure as Hinge A, Solution 2; Hinge B, Solution 4: It is a self-locking hinge with the same structure as Hinge A, Solution 3; Hinge B, Solution 5: There are two identical square plates, the front edges of the upper plate A and the lower plate A are axially hinged between the upper plate A and the lower plate A, which is the hinge axis A; at the rear edges of the upper plate A and the lower plate A, the upper plate A and the lower plate A are connected and locked by a connecting piece G with a structure of a luggage spring duckbill buckle; the sizes of the upper plate A and the lower plate A are equivalent to the thickness of the seat tube of the seat bracket. When the connecting piece G is loosened, the rear edges of the upper plate A and the lower plate A are disengaged, and the seat bracket can be folded forward; when the connecting piece G is fastened, the rear edges of the upper plate A and the lower plate A are connected by the connecting piece G, and the seat bracket and the main bracket are connected as a whole and cannot be folded forward; the upper surface of the upper plate A and the lower surface of the lower plate A are used to connect two objects and allow folding rotation between them.

[0015] A small folding bicycle, which includes a rear wheel assembly, a steering system, a braking system, a pedal sprocket transmission assembly, a seat, and further includes the above-mentioned folding frame; the rear wheel assembly is a single-rear-wheel structure rear wheel assembly or a double-rear-wheel structure rear wheel assembly. When the rear wheel of the small folding bicycle is of a single-rear-wheel structure, the rear wheel assembly is the single-rear-wheel structure rear wheel assembly, which includes a rear wheel, a rear wheel axle, a rear fork, and a flywheel A. The rear wheel axle connects the rear wheel and the flywheel A, and both ends of the rear wheel axle are connected to the tail of the rear fork; when the rear wheel of the small folding bicycle is of a double-rear-wheel structure, the rear wheel assembly is the double-rear-wheel structure rear wheel assembly, which includes a left rear wheel, a rear wheel axle, a right rear wheel, a rear wheel bearing assembly B, and a flywheel A. The rear wheel bearing assembly B includes two identical rear wheel bearings, two bearing sleeves B, and a fixing frame B. The two identical rear wheel bearings are respectively installed inside the two identical bearing sleeves B. The fixing frame B is an inverted U-shaped fixing frame. Both ends of the fixing frame B are connected to the two bearing sleeves B, and the upper surface of the fixing frame B is a rectangular plane.

[0016] The tail of the main bracket A or the tail of the second part of the main bracket of the folding frame is connected and fixed to the rear wheel assembly; specifically, when the rear wheel of the small folding bicycle is of a single-rear-wheel structure, the rear wheel assembly is the single-rear-wheel structure rear wheel assembly, and the small folding bicycle is a small two-wheel folding bicycle. The tail of the main bracket A or the tail of the second part of the main bracket of the folding frame is connected and fixed to the head of the rear fork of the single-rear-wheel structure rear wheel assembly; when the rear wheel of the small folding bicycle is of a double-rear-wheel structure, the rear wheel assembly is the double-rear-wheel structure rear wheel assembly. The tail of the main bracket A or the tail of the second part of the main bracket of the folding frame is connected and fixed to the fixing frame B of the double-rear-wheel structure rear wheel assembly. The small folding bicycle is a small three-wheel folding bicycle, which is especially suitable for the elderly to ride; the seat is connected to the upper end of the seat post of the seat bracket of the folding frame; further, the rear wheel axle of the double-rear-wheel structure is telescopic and is provided with a locking device in the retracted state. In this way, when riding, the rear wheel axle stretches out, making the body more stable, and after the rear wheel axle retracts, the distance is smaller, which is convenient for carrying and entering public places.

[0017] The pedal sprocket transmission assembly includes a bottom bracket assembly, a crank, a pedal, a large sprocket, an endless chain, and a flywheel A. Their assembly and connection relationship is the same as that of a traditional bicycle. The flywheel A is the flywheel A in the rear wheel assembly. The large sprocket and the flywheel A are connected by an endless chain. The large sprocket, the endless chain, and the flywheel A are arranged on the same side and kept consistent. The pedal is a foldable pedal; further, the single-group sprocket transmission can be changed to a two-group sprocket front-and-back relay transmission. The flywheel of the front group and the large sprocket of the rear group are coaxial and are respectively arranged on the left and right sides of the main bracket. The two sprocket mechanisms can increase the gear ratio, thereby increasing the riding speed, which is suitable for the small-diameter drive wheel of the small folding bicycle; the pedal sprocket transmission assembly can also be replaced by a shaft transmission assembly, and it can also be a toothed belt transmission assembly.

[0018] The steering system includes a front wheel, a front fork, a headset assembly, handlebars, a stem, and a front wheel axle. The stem is a telescopic stem. The lower tube of the stem can telescopically extend in and out of the upper tube of the front fork, and a telescopic locking device C, which is a seat post clamp C, is provided at the connection. Or the stem is a foldable stem with a folding locking device. Or the stem is a foldable stem with a folding locking device C, and at the same time, the handlebar tube of the stem is telescopic. When the main bracket is a main bracket A, the handlebar tube of the stem is a gooseneck handlebar tube, which can increase the distance from the seat to the handlebars. After the small folding bicycle is folded, it meets the volume limit conditions for entering transportation equipment such as subways and can also meet the riding needs of users of different heights. The handlebars are foldable handlebars;

[0019] The assembly and connection relationship between the steering system and the head tube is the same as that of a traditional bicycle. The front fork of the steering system is connected to the head tube of the folding frame through a headset assembly. Specifically, after the front fork and the head tube are assembled, when the head tube is in the position of the front fork, after the front fork is folded backward, when the small folding bicycle is folded and the main bracket is erected, the front wheel is located above the rear wheel and in front, and the front wheel is close to or abuts against the tail of the main bracket A, or the front wheel is close to or abuts against the second part of the main bracket, and can be locked through the hinge A of the folding frame. This can minimize the front and rear dimensions of the small folding bicycle after folding, making it convenient to place or move in crowded or narrow environments. After an auxiliary wheel is installed on a small folding bicycle with a single rear wheel structure, it can be towed with the rear wheel in the same way as a small folding bicycle with a double rear wheel structure. The front wheel and the front fork of the steering system are folded backward or unfolded forward through the hinge A of the folding frame. The hinge A has a limit and locking when it is unfolded to the maximum angle to ensure that the bicycle steering system is in the best position during riding when it is fully unfolded again after folding. The maximum unfolding angle of the hinge A is the riding state. After the front fork is folded backward to the end and locked through the hinge A, at this time, the front wheel is close to or abuts against the tail of the main bracket A, or the front wheel is close to or abuts against the second part of the main bracket. This can prevent the front wheel from sagging under the action of gravity when the front wheel is under the main bracket and the rear wheel is towed, affecting stable towing, and it is convenient to tow with the rear wheel in places with crowded people and small areas such as supermarkets and to get on and off escalators;

[0020] A bottom bracket assembly is provided below the front of the seat. The bottom bracket assembly is perpendicular to the main bracket and is connected to the main bracket below the main bracket. After the seat bracket is folded forward, the seat is located above the head of the main bracket A or above the top of the first part of the main bracket after retracting into the first part of the main bracket. The small folding bicycle is close to the N-shaped form after unfolding and close to the III-shaped form after being fully folded, with small height and volume, simple structure, less overall material used, and thus lighter weight.

[0021] The main bracket of this application has different names in other small folding bicycle patents, such as: rear frame, rear beam, second support, rear bracket, etc.

[0022] In order for small folding bicycles to carry and tow more items, and to be quickly packaged and smoothly enter subways and other buses, a small folding bicycle loading device is invented here. It can be quickly installed and fixed at the tail of the main bracket. It includes a loading cart and a quick connection and fixing device for the loading cart. The loading cart includes a loading cart frame and a loading bag. The loading cart frame is provided with a loading cart support plate vertically at the tails of the two vertical rods of the H-shaped frame and perpendicular to the H-shaped frame. Pulley C is provided at the left and right ends of the horizontal bar at the bottom of the H-shaped frame. The loading bag is a rectangular pocket, similar to the shopping bag on a shopping cart for buying groceries, and is installed on the loading cart frame; further, the loading cart frame is designed to be vertically telescopic, and the loading cart support plate can be folded back and forth. Support feet B or pulleys are provided at both ends of the tail of the loading cart support plate;

[0023] Through the quick connection and fixing device for the loading cart, the loading cart can be quickly fixed at the tail of the small folding bicycle, above the rear wheel of the small folding bicycle; there are two solutions for the quick connection and fixing device for the loading cart:

[0024] Solution 1 of the quick connection and fixing device for the loading cart includes a fixing block A and a self-locking hinge E. The fixing block A is provided with a fixing hole B on a rectangular body A. The bottom of the fixing block A is connected to one end of a self-locking hinge E. The other end of the self-locking hinge E can be fixed at the tail of the main bracket of the small folding bicycle. The fixing block A can be folded back and forth and the folding angle can be locked through the self-locking hinge E. A clamping block A is fixed in the middle of the horizontal bar at the bottom of the H-shaped frame of the loading cart frame. The clamping block A is provided with a fixing shaft B at the bottom of a rectangular body B. The fixing shaft B is matched with the fixing hole B and can just be inserted into the fixing hole B. The fixing shaft B is a square shaft and the fixing hole B is a square hole. In this way, the horizontal bar at the bottom of the H-shaped frame cannot move in the front-back, left-right directions, so that the loading cart connected to the clamping block A can be fixed at the tail of the main bracket of the small folding bicycle; further, the dimensions of the rectangular body A and the rectangular body B are the same in the front-back or left-right directions. A locking device is provided in the up-down direction between the fixing block A and the clamping block A to ensure that the loading cart is firmly fixed. The locking device can be a spring duckbill buckle for luggage; the placement angle of the loading cart can be changed by changing the folding angle of the self-locking hinge E;

[0025] The second solution for the quick connection and fixing device of the carrier vehicle includes a carrier support plate made of a rectangular iron plate and a self-locking hinge C. The bottom of the head of the carrier support plate is connected to the tail of the main bracket of the small folding bicycle through the self-locking hinge C. The self-locking hinge C has the functions of folding and locking the folding angle. At this time, a number of magnets are arranged at the bottom of the carrier vehicle support plate. As long as the carrier vehicle is placed on the carrier support plate, the magnets at the bottom of the carrier vehicle support plate will attract the carrier support plate, so that the carrier vehicle and the small folding bicycle can be connected and fixed. By changing the folding angle of the self-locking hinge C, the placement angle of the carrier vehicle can be changed;

[0026] When the small folding bicycle is folded and towed or placed vertically, the main bracket and the square groove A or the carrier support plate are folded at about 90 degrees. When the small folding bicycle is unfolded, the main bracket and the square groove A or the carrier support plate are folded horizontally.

[0027] The self-locking hinge C and the self-locking hinge E have the following solutions: Solution 1. It is a self-locking hinge with the structure of a common hinge plus hinge A. Specifically, after connecting the carrier support plate and the tail of the main bracket through a common hinge, a hinge with the structure of hinge A is set on the left or right side of the carrier support plate; Solution 2. It is a self-locking hinge with the structure of Solution 2 of hinge A; Solution 3. It is a self-locking hinge with the structure of Solution 3 of hinge A.

[0028] The size and height of the carrier bag on the carrier vehicle can hold the folded small folding bicycle. An opening is provided from top to bottom on the back of the carrier bag, and a zipper A or a magic tape is provided at the opening. If taking the subway, the carrier vehicle can be quickly removed during inspection, and then the fully folded small folding bicycle can be put in. After passing the inspection, it can be directly towed with the carrier vehicle; further, in order to reduce the height of the carrier bag during normal use, an extended bag mouth is also provided at the bag mouth of the carrier bag. It is turned inside out usually, and when the folded small folding bicycle needs to be loaded, the extended bag mouth is opened to extend the height of the carrier bag.

[0029] Further, in order to make the carrier vehicle stable when the small folding bicycle is towed and ridden, a carrier vehicle fixing part is provided at the top of the carrier vehicle frame for connecting and fixing with the seat cushion bracket and the main bracket; the carrier vehicle fixing part is one of the following solutions: 1. It is a buckle part A with the structure of a bicycle lamp holder clip. One end of the buckle part A is a buckle A that can buckle the top of the carrier vehicle frame, and the other end is a buckle B that can buckle the seat cushion bracket and the main bracket. Both the buckle A and the buckle B are equipped with locking devices; 2. It is a rubber band with a fixed hook at the head; 3. It is a strip-shaped magic tape.

[0030] After the carrier vehicle fixing part is provided at the top of the carrier vehicle frame, the self-locking hinge C and the self-locking hinge E can use ordinary hinges.

[0031] Further, a folding seat A is provided on the H-shaped frame.

[0032] In order to enable the small folding bicycle described above to play a greater role in people's lives and solve some practical problems in life, in addition to the advantages of being convenient to carry, having a small volume and light weight after folding, a multifunctional small folding bicycle is invented. Its characteristics are that it includes the small folding bicycle described above, and a small folding bicycle cargo-carrying device is also installed at the tail of the small folding bicycle. In this way, the small folding bicycle can carry more goods and ride, and can be quickly put into a cargo-carrying vehicle and smoothly enter the subway or other buses after folding. A folding seat can also be set on the day-shaped frame of the cargo-carrying vehicle. In this way, there is no need to worry about not having a seat when taking the subway or bus. Since the rear wheel assembly of this small folding bicycle can also adopt a double-rear-wheel structure, the riding is safer and it is especially suitable for the elderly to ride;

[0033] Furthermore, in order to make the small folding bicycle equipped with a small folding bicycle cargo-carrying device stable and labor-saving when being towed or pushed by the rear wheel after folding, and can enter a shopping mall and be used as a shopping cart for shopping, two auxiliary wheels with the same structure are arranged on the left and right sides of the tail of the main bracket of the small folding bicycle. The left auxiliary wheel and the right auxiliary wheel. Specifically, there are two technical solutions for the auxiliary wheel:

[0034] Auxiliary wheel solution one: pulleys are installed at the tails of two telescopic and lockable telescopic rods A. A cross bar A is horizontally arranged in the left-right direction at the tail of the main bracket A or the second part of the main bracket of the small folding bicycle. The cross bar A is perpendicular to the main bracket. The heads of the two telescopic rods A are perpendicular to the head of the cross bar A and are respectively connected to the two ends of the cross bar A through two hinges F. The hinge F is a self-locking hinge with a folding angle locking function. The plane formed by the rotation of the telescopic rod A through the hinge F is parallel to the rear wheel of the small folding bicycle. The length of the cross bar A should ensure that the telescopic rod A will not touch the rear wheel assembly when rotating forward and backward through the hinge F. After the telescopic rod A rotates forward to the limited maximum angle position, the hinge F has a position limiting and locking device. After the telescopic rod A rotates backward to the limited maximum angle position, the hinge F has a position limiting and locking device; when the small folding bicycle is folded and towed by holding the bicycle handlebar, the two telescopic rods A rotate forward to the limited maximum angle position and are locked. The two telescopic rods A are pulled out. When pushing by holding the bicycle handlebar, the two support rods A rotate backward to the limited maximum angle position and are locked. The two telescopic rods A are pulled out. The set maximum angle of forward or backward rotation should make the center of gravity of the entire folded small folding bicycle located between the rear wheel of the small folding bicycle and the two small folding bicycle auxiliary wheels when placed vertically. Towing and pushing are both very easy. In this way, it can be placed vertically. When riding, the telescopic rod A retracts and then rotates backward to be approximately parallel to the main bracket and is locked.

[0035] Auxiliary wheel solution two: There is a support rod B, which includes the first section of support rod B and the second section of support rod B. The connection between the first section of support rod B and the second section of support rod B is connected by a self-locking hinge D. The first section of support rod B can be rotated and folded through the self-locking hinge D. The self-locking hinge D has folding locking devices at 0 degrees and 180 degrees. Then, replace the telescopic rod A in the auxiliary wheel solution one with the support rod B, and the others are the same as those in the auxiliary wheel solution one. When it is necessary to tow and push with the auxiliary wheel, unfold the support rod B. When riding, rotate the first section of support rod B through the self-locking hinge D and fold it with the second section of support rod B, and lock it when the support rod B rotates backward to be roughly parallel to the main bracket.

[0036] The hinge F and the self-locking hinge D can be the self-locking hinge with the structure of hinge A solution one, or the self-locking hinge with the structure of hinge A solution two, or the self-locking hinge with the structure of hinge A solution three.

[0037] In order to prevent the bicycle handlebar from shaking when towing the rear wheel of a small folding bicycle with one hand while holding the bicycle handlebar and enable stable towing, a bicycle handlebar locking device is also provided between the head tube and the upper part of the front fork. The bicycle handlebar locking device can be a locking device with the structure of a luggage spring duckbill buckle. After the bicycle handlebar locking device is locked, the bicycle handlebar cannot rotate. In this way, after two auxiliary wheels are installed on both sides of the small folding bicycle, the small folding bicycle can carry more items after folding, and can be pushed and towed stably and labor-savingly. It can enter the supermarket for shopping, and can also be placed upright and carried with you when entering a restaurant for a meal.

[0038] Furthermore, a rear wheel support plate A is provided above the rear wheel of the rear wheel assembly with a single rear wheel structure. The rear wheel support plate A is a rectangular plate, and its left and right sides are fixed to the rear fork through connecting pieces. The head of the rear wheel support plate A is connected to the tail of the main bracket. A rear wheel support plate B is also provided above the rear wheel of the rear wheel assembly with a double rear wheel structure. The rear wheel support plate B is a rectangular plate, and the head of the rear wheel support plate B is connected to the tail of the main bracket. After the folding frame is unfolded, the rear wheel support plate A and the rear wheel support plate B are horizontal. Furthermore, an expansion mechanism is also provided on the rear wheel support plate A or the load support plate to make larger items such as travel suitcases placed on it more stable. There are three technical solutions for the expansion mechanism:

[0039] Expansion mechanism solution one: On the rear wheel support plate A or the load support plate, there are a left folding frame and a right folding frame. They are square frames. The left side rod of the left folding frame is fixed by two front and rear saddle clips. The left folding frame rotates and unfolds or folds around the left side rod. The right folding frame is set in the same way, except that the right side rod of the right folding frame is fixed by the right saddle clip. The two frames are of different sizes. After the two frames are folded, they are nested with each other to form a square shape. In the middle of the rear wheel support plate A or the load support plate, there is also a square boss A. The height of the square boss A is the same as the height of the saddle clip. On the tail edges of the two folding frames after unfolding, there are two rubber sleeves A each. The thickness of the rubber sleeve A is the same as or slightly larger than the thickness of the saddle clip. In this way, after the two folding frames are unfolded, they and the boss A jointly support the heavy objects placed on them, and the area of the rear wheel support plate A or the load support plate can be increased.

[0040] Expansion mechanism solution two: It includes a box A, a left expansion part, and a right expansion part; the rear wheel support plate A or the load support plate is just the right size to cover the opening of the box A and is connected and fixed to each other. At the bottom of the box A, there is a left expansion part. The left expansion part includes a U-shaped part A, two round tubes, and two limit caps. At the front and rear ends of the left side of the box A, there is a round hole A each. On the right side of the round hole A, there is a round tube fixed. The round tube is fixed in the left-right direction on the bottom plate of the box A. The two ends of the head of the U-shaped part A can freely pass through the round holes A at the front and rear of the left side of the box A and the round tube on the right side. There is a limit cap at the head of the U-shaped part A. There is a rubber sleeve B on the left side of the U-shaped part A, so that the top of the rubber sleeve B and the plane of the rear wheel support plate A or the load support plate are on the same plane. Similarly, there is a right expansion part on the right side of the box A, except that the width of the right U-shaped part B is slightly smaller, so that it will not touch the U-shaped part A when retracted, or the right expansion part and the left expansion part are of the same size, but they are installed in a staggered manner. When the left expansion part and the right expansion part are all pulled out, the supporting area of the rear wheel support plate A or the load support plate can be expanded, and when all are retracted, they are hidden in the box A.

[0041] Expansion mechanism solution three: Fix the left expansion part and the right expansion part of expansion mechanism solution two at the bottom of the rear wheel support plate A or the load support plate. The structure is the same as that of expansion mechanism solution two. When the left expansion part and the right expansion part are all pulled out, the supporting area of the rear wheel support plate A or the load support plate can be expanded. For aesthetics, the left expansion part and the right expansion part can be packaged with a box, but there should be through holes on both the left and right sides that can pass through the U-shaped part A;

[0042] At least one fixing hole A or fixing ring is provided at the tail of the rear wheel support plate A, the rear wheel support plate B or the load support plate. In this way, the small folding bicycle can fix relatively large items such as travel suitcases with a rubber strap and carry them when traveling;

[0043] Further, when the small folding bicycle does not need to install the carrier, a child seat can be selectively installed. One end of a seat seat post is connected to the child seat, and the other end is connected to a block B. The block B has the same structure as the block A in the first solution of the quick connection fixing device for the carrier. And the quick connection fixing device for the carrier adopts the first solution of the quick connection fixing device for the carrier. Further, a locking device is provided on the cuboid A and the block B to ensure the firm fixed connection of the child seat. The child seat can also be installed on the rear wheel support plate A or the rear wheel support plate B through the child seat tube. In this way, when needed, the user can take the child out together with the small folding bicycle.

[0044] Further, the front wheel or the rear wheel of the small folding bicycle is a motor front wheel or a motor rear wheel containing a motor. A power battery and a controller are added, and the length and volume of the head tube housing are increased. The power battery and the controller are installed inside the head tube or the power battery and the controller are installed at the tail of the small folding bicycle. In this way, the small folding bicycle can be turned into an electric bicycle that can be ridden.

[0045] The beneficial effects of the present utility model are as follows: 1. The structure design of the folding frame is simple and clear. After the small folding bicycle is fully folded, it is close to the shape of III. Its height and volume are very small. The overall material used is less, the cost is low, and the weight is also light.

[0046] 2. Since the small folding bicycle is provided with a rear wheel support plate, a quick connection fixing device for the carrier is provided at the tail of the main bracket, and a carrier that is convenient for disassembly and fixation is designed. In this way, when towing and riding the present utility model, larger objects such as travel suitcases can be placed and fixed, and the problem that a small personal transportation tool cannot carry more items when riding is solved. The child seat can also be installed at the tail of the main bracket when needed. Thus, the small folding bicycle can meet different needs, such as traveling, supermarket shopping, and taking the baby out, which greatly improves the practicality.

[0047] 3. Due to the uniqueness of the folding frame structure of this small folding bicycle, after being fully folded, the front wheel should be located above the rear wheel and in front, and the front wheel is located below the main bracket and can be in a locked state. Above it is the seat bracket, and the cargo carrier is on the top, and auxiliary wheels are provided. This enables both single-rear-wheel and double-rear-wheel structures to be towed or pushed with less effort when carrying goods, solving the problem that small folding bicycles cannot carry much when being towed or pushed. Also, due to its small size, it can easily enter supermarkets and escalators and other places where other small folding bicycles are inconvenient to enter. Since auxiliary wheels are provided, after the auxiliary wheels are unfolded, the present utility model can be placed vertically after folding, occupying little space. The center of gravity of the small folding bicycle is located between the rear wheel of the small folding bicycle and the two auxiliary wheels of the small folding bicycle, making towing and pushing very labor-saving. The cargo carrier can be easily removed, and the folded small folding bicycle can be put into the cargo carrier for quick packaging, which can meet the entry regulations of subways in various places. After passing the security check, the cargo carrier can be towed into the subway, solving the problem that personal transportation means are inconvenient to enter subways and buses. There is a folding seat on the day-shaped frame of the cargo carrier, so there is no need to worry about not having a seat when taking the subway and bus.

[0048] 4. Since the rear wheel assembly of this small folding bicycle can also adopt a double-rear-wheel structure, the riding is safer and it is especially suitable for the elderly to ride. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic diagram of the folding frame when the seat is installed at the upper end of the seat bracket and the main bracket is the second solution, and hinge A is unfolded to the maximum angle.

[0050] Figure 2 It is a schematic diagram of the riding state of a small folding bicycle with a single-rear-wheel structure when the main bracket is the second solution and hinge A is unfolded to the maximum angle.

[0051] Figure 3 It is a schematic diagram of the towing state when a small folding bicycle with a single-rear-wheel structure is folded, the main bracket is the second solution, two auxiliary wheels are installed and unfolded forward, and a rear-wheel support plate A, a cargo support plate and a cargo carrier are installed.

[0052] Figure 4 It is a schematic diagram of a small folding bicycle with a single-rear-wheel structure and the main bracket being the second solution when the cargo carrier is in the unfolded state.

[0053] Figure 5 It is a schematic diagram when a small folding bicycle with a single-rear-wheel structure and the main bracket being the second solution is folded, two auxiliary wheels are installed and unfolded backward, and it is placed vertically.

[0054] Figure 6 It is a schematic diagram of the unfolded state of a small folding bicycle using the double-rear-wheel structure of this folding frame and the main bracket being the second solution.

[0055] Figure 7 It is a double rear wheel structure. The main bracket is a schematic diagram of the towing state when the small folding bicycle of Solution 2 is folded and equipped with a load-carrying support plate and a cargo cart.

[0056] Figure 8 From left to right, it is a schematic diagram of the fixed block A, which is connected to the tail of the main bracket of the folding frame and the block A through the self-locking hinge E.

[0057] Figure 9 It is a schematic diagram of the connection of the rear wheel assembly of the double rear wheel structure without the fixed frame B.

[0058] Figure 10 It is a schematic diagram of the connection of the rear wheel assembly of the double rear wheel structure with the fixed frame B.

[0059] Figure 11 It is a schematic diagram of the load-carrying support plate connected to the tail of the main bracket of the folding frame through the hinge C.

[0060] Figure 12 From left to right, it is Schematic Diagram 1 of the expansion mechanism, showing the expansion mechanism when it is folded and unfolded.

[0061] Figure 13 From left to right, it is Schematic Diagram 2 of the expansion mechanism, showing the left expansion part and the right expansion part arranged on a bottom plate and installed in box A.

[0062] Figure 14 It is a schematic diagram of the cargo cart frame.

[0063] Figure 15 It is a schematic diagram of the cargo cart.

[0064] Figure 16 It is a schematic diagram of Hinge B, Solution 5.

[0065] Figure 17 It is a schematic diagram of a commercially available 0-180° fishing chair backrest gear adjuster.

[0066] Figure 18 From left to right, it is a schematic diagram of a commercially available 90° foldable self-locking hinge in the fully folded state and when folded 90°.

[0067] Figure 19 From left to right, it is a schematic diagram of a commercially available 0-90-180° self-locking hinge when folded 90° and when folded 180°.

[0068] Figure 20 From left to right, it is a schematic diagram of Hinge A, Solution 2, when the locking and unlocking shaft is not assembled, when Hinge A is folded 90° and locked, and when the middle section of the locking and unlocking shaft B is located at the position of the arc-shaped sliding groove and the locking and unlocking shaft can slide.

[0069] Figure 21 It is a small folding bicycle with a single rear wheel structure. The main bracket is Solution 1, which is a main bracket A. The head tube is a foldable head tube, and the handlebar tube of the head tube is telescopic. The handlebar tube of the head tube is a gooseneck handlebar tube. When hinge A is unfolded to the maximum angle, it is a schematic diagram of the riding state.

[0070] In the figure: 1. Left rear wheel, 2. Right rear wheel, 3. Rear wheel axle, 4. Flywheel A, 5. Fixed bracket B, 6. Bearing sleeve B, 7. Front wheel, 8. Main bracket A, 9. Head tube, 10. Front fork, 11. Handlebar, 12. Large sprocket, 13. Bottom bracket assembly, 14. Pedal, 15. Second part of the main bracket, 16. Hinge B, 17. Seat post, 18. Ring chain, 19. Seat cushion, 20. Hinge A, 21. Stem, 22. Rear wheel, 23. Fixed block A, 24. Self-locking hinge E, 25. Rear wheel support plate A, 26. Pulley C, 27. Locking device A, 28. First part of the main bracket, 29. Locking device B, 30. Telescopic locking device C, 31. Rear fork, 32. Seat rod, 33. Saddle clamp, 34. Left side rod, 35. Right side rod, 36. Telescopic rod A, 37. Boss A, 38. Round tube, 39. U-shaped part A, 40. Limit cap, 41. Rubber sleeve B, 42. U-shaped part B, 43. Round hole A, 44. Box A, 45. Child seat, 46. Cargo support plate, 47. Fixed hole B, 48. Self-locking hinge C, 49. Child seat post, 50. Cargo bag, 51. Gooseneck stem, 521. Left auxiliary wheel, 522. Right auxiliary wheel, 53. Rubber sleeve A, 54. Hinge shaft A, 55. Support foot B, 56. Connecting piece G, 57. Tube A, 58. Day-shaped frame, 59. Zipper A, 60. Cargo cart support plate, 61. Top of the cargo cart frame, 62. Upper plate A, 63. Lower plate A, 64. Rotating shaft A, 65. Rotating shaft B, 66. Arc-shaped sliding groove, 67. Locking and unlocking shaft, 68. Position of the locking and unlocking shaft in the arc-shaped sliding groove when the hinge is at the minimum folding angle, 69. 90-degree folding locking hole, 70. U-shaped groove part A, 71. U-shaped groove part B, 72. Unlocking operation handle, 73. Rotating shaft C, 74. Rotating shaft D, 75. Locking rod, 76. Sliding groove, 77. Locking rod tension spring, 78. 90-degree folding locking groove, 79. 0-degree folding groove, 80. 180-degree folding locking groove, 81. U-shaped connecting piece, 82. U-shaped groove part D, 83. U-shaped groove part C, 84. Rotating arm A, 85. Rotating arm B, 86. Locking and unlocking connecting piece, 87. Folding locking device C, 88. Foldable stem, 89. Fixed nut hole, 90. Gear disk B, 91. Gear disk A, 94. Below the U-shaped groove part A, 95. Cargo cart, 96. Cross bar at the bottom of the day-shaped frame, 97. Block A, 98. Fixed shaft B, 99. Spring A, 100. Locking and unlocking shaft A, 101.Lock and unlock the circular hole at the left end of shaft B, 102. Annular snap ring groove A, 103. A section of shaft at the left end of lock and unlock shaft B, 104. A section of shaft in the middle of lock and unlock shaft B, 105. A section of shaft at the right end of lock and unlock shaft B, 106. The right end of U-shaped groove object A, 107. The right end of U-shaped groove object B, 108. Snap ring. Detailed implementation mode

[0071] The present utility model will be further described below in conjunction with the drawings and embodiments. Embodiment 1, Figures 1 to 20 As shown; this embodiment includes: a folding frame, which includes a main bracket, a seat bracket, hinge A 20, hinge B 16, and head tube 9. The main bracket and the seat bracket are in a tubular form;

[0072] The main bracket selects the main bracket solution two, which is composed of two parts: the first part 28 of the main bracket and the second part 15 of the main bracket. The first part 28 of the main bracket can slide telescopically relative to the second part 15 of the main bracket. Specifically, the first part 28 of the main bracket can telescopically enter and exit the second part 15 of the main bracket. A locking device A 27 is provided at the connection between the second part 15 of the main bracket and the first part 28 of the main bracket. Specifically, the locking device A 27 is a seat tube clamp A, which is used to lock the state after the first part 28 of the main bracket is telescoped;

[0073] The seat bracket is composed of a seat post 32, a seat tube 17, and a locking device B 29. The seat post 32 can telescopically enter and exit the seat tube 17. A locking device B 29 is provided at the connection between the seat tube 17 and the seat post 32. The locking device B 29 is a seat tube clamp B, which is used to lock the state after the seat post 32 is telescoped;

[0074] One end of hinge A 20 is connected to head tube 9 or connected to head tube 9 through a connecting piece. The other end of hinge A 20 is connected to the head of the first part 28 of the main bracket or connected to the head of the first part 28 of the main bracket through a connecting piece. The head tube 9 can be folded backward or unfolded forward relative to the main bracket through hinge A 20. Hinge A 20 is a self-locking hinge, which has a limiting and locking device at the maximum unfolding angle to ensure that the bicycle steering system is in the best position during riding after being fully unfolded again after folding. The maximum unfolding angle of hinge A 20 is the state during riding; Hinge A 20 also has a folding position limiting and locking device after folding in place. Specifically, when the front wheel of the bicycle steering system in the application of the folding frame is folded to be close to or close to the tail of the main bracket, hinge A 20 is locked. This is to prevent the front wheel from sagging under the action of gravity and affecting towing when dragging a small folding bicycle using the folding frame with the rear wheel while holding the bicycle handlebar, and can minimize the size of the small folding bicycle in the front-rear direction after folding;

[0075] The lower end of the hinge B 16 is connected to the second part 15 of the main bracket or connected to the second part 15 of the main bracket through a connecting member. The upper end of the hinge B 16 is connected to the lower end of the seat tube 17. The hinge B 16 is a self-locking hinge with a locking device that limits the folding position when folded backward in place. After the hinge B 16 is locked, the seat cushion bracket cannot be folded. At this time, the seat cushion bracket is equivalent to a straight tube connected to the main bracket. After the hinge B 16 is unlocked, the seat cushion bracket can be folded forward through the hinge B 16. After the seat cushion bracket is folded forward, it is above the main bracket; when the seat cushion bracket connected to the hinge B 16 is folded backward in place, there is a position limit lock, so that the seat cushion bracket can quickly return to the best riding state when the small folding bicycle is unfolded after folding.

[0076] When the folding frame is applied, the upper end of the seat post 32 is connected to the seat cushion 19, the tail of the second part 15 of the main bracket is connected and fixed to the rear wheel assembly, and the head tube 9 is connected to the bicycle steering system.

[0077] The hinge A 20 has the following solutions: Hinge A solution one is a hinge with the same structure as a commercially available 0-180 degree fishing chair backrest gear regulator; it includes two gear folding parts A and gear folding parts B with the same structure. The gear folding part A is provided with a gear disk A 91 at the head of the rotating arm A 84, and the gear folding part B is provided with a gear disk B 90 at the head of the rotating arm B 85. The two objects are connected through the rotating arm A 84 and the rotating arm B 85 and allowed to perform folding rotation between them. The concave and convex teeth on the outer circumference of the gear disk A 91 and the gear disk B 90 are embedded in each other, and fixing screws are passed through the central holes of the gear disk A 91 and the gear disk B 90, and the gear disk A 91 and the gear disk B 90 are connected and fixed with a fixing nut. When it is necessary to adjust the folding angle between the gear folding part A and the gear folding part B, the fixing screws can be loosened, the rotating arm A 84 or the rotating arm B 85 can be rotated, and then locked through the fixing screws. The locking and unlocking connecting piece 86 is connected to the head of the fixing screw, which is convenient for manual locking and unlocking.

[0078] Hinge A Solution 2 is a hinge with the same principle as a 90-degree foldable self-locking hinge, where the locking and unlocking operations are on the side of the hinge and are commercially available, and a slight modification is made on this basis. It includes two rotating shafts. Rotating shaft A 64 and rotating shaft B 65 connect the left and right sides of two U-shaped groove objects A 70 and B 71, one large and one small, to form a hinge. Rotating shaft A 64 and rotating shaft B 65 are coaxial, and the folding angle and locking of the hinge are changed by a locking and unlocking shaft 67 that can slide along an arc-shaped sliding groove 66. The locking and unlocking shaft 67 is composed of two shafts, namely locking and unlocking shaft A 100 and locking and unlocking shaft B. Locking and unlocking shaft B consists of three sections. There is a left-end round hole 101 in the center of the left-end section 103 of locking and unlocking shaft B. An annular snap ring groove A 102 is provided in the middle of the left-end section 103 of locking and unlocking shaft B. The right-end section 105 of locking and unlocking shaft B is the thickest at the operating end, like a small disc, and the middle section 104 of locking and unlocking shaft B is the thinnest. One end of locking and unlocking shaft A 100 is connected to the left end of U-shaped groove object A 70. The left end of locking and unlocking shaft B can just pass through the 90-degree fold locking hole 69 on U-shaped groove object B 71 and at the same time pass through a through hole on U-shaped groove object A 70 with the same size as the 90-degree fold locking hole, and the outer part of the other end of locking and unlocking shaft A 100 can just be sleeved with a spring A 99 and then inserted into the left-end round hole 101 of locking and unlocking shaft B. The right end of spring A 99 abuts against the left end of locking and unlocking shaft B. The locking and unlocking shaft 67 is installed by clamping the snap ring 108 into the annular snap ring groove A 102 of locking and unlocking shaft B on the inner side of the right end of U-shaped groove object A 70. The 90-degree fold locking hole 69 is connected to the arc-shaped sliding groove 66. The width of the arc-shaped sliding groove 66 is smaller than the diameter of the left-end section 103 of locking and unlocking shaft B and larger than the diameter of the middle section 104 of locking and unlocking shaft B. When the hinge is folded 90 degrees, a 90-degree fold locking hole 69 is provided on U-shaped groove object B 71 on one side of the two U-shaped groove objects. The left-end section 103 of locking and unlocking shaft B can just pass through the 90-degree fold locking hole 69 to lock the hinge when it is folded 90 degrees. The left-end section 103 of locking and unlocking shaft B is larger than the width of the arc-shaped sliding groove 66 and cannot slide along the arc-shaped sliding groove 66. If unlocking is needed, by pressing the right-end section 105 of locking and unlocking shaft B, the right-end section 105 of locking and unlocking shaft B retracts. At this time, the middle section 104 of locking and unlocking shaft B, which is the thin section, is located in the arc-shaped sliding groove 66, so that the locking and unlocking shaft 67 can slide in the arc-shaped sliding groove 66 to change the folding angle;Now make a slight modification on this basis. As long as when the hinge is folded to the angle that needs to be locked, similar to when it is folded 90 degrees and can be locked, set a locking hole of the same size as the 90-degree folding locking hole 69 at the position of the arc-shaped sliding groove 66 where the locking and unlocking shaft 67 is located, and then it can be locked. If it needs to be locked at a position greater than 90 degrees, just lengthen the arc-shaped sliding groove 66, and change the original 90-degree folding locking hole 69 set at 90-degree folding to a locking hole of the same size at the end of the lengthened arc-shaped sliding groove 66. This position is also the position of the maximum unfolding angle of the hinge. The end of the arc-shaped sliding groove 66 limits the maximum unfolding angle; connect two objects through the bottom of the U-shaped groove object A 70 and the bottom of the U-shaped groove object B 71 and allow folding rotation between the two.

[0079] Hinge A, Plan Three, is a hinge with the same structure as a commercially available unlocking operation handle in the middle of the hinge, a 0 - 90 - 180-degree folding self-locking hinge. Make a slight modification on this basis; it is connected by two rotating shafts, the rotating shaft C 73 and the rotating shaft D 74, on the left and right sides of two U-shaped groove objects C 83 and U-shaped groove object D 82, one large and one small, to form a hinge. The rotating shaft C 73 and the rotating shaft D 74 are coaxial. On the left and right sides of the U-shaped groove object C 83, a sliding groove 76 is set respectively. A locking rod 75 passes through the left and right sliding grooves 76. The two ends of the locking rod 75 are connected to the two ends of a U-shaped connecting piece 81. The bottom of the U-shaped connecting piece 81 is connected to the rectangular unlocking operation handle 72. The locking rod 75 is also connected to the bottom of the U-shaped groove object C83 through two left and right locking rod tension springs 77. On the left and right sides of the U-shaped groove object D 82, according to the folding angle requirements, a 0-degree folding groove 79, a 90-degree folding locking groove 78, and an 180-degree folding locking groove 80 are symmetrically set. Now the 0-degree folding groove 79 is not as large as the 90-degree folding locking groove 78 and the 180-degree folding locking groove 80, so the hinge cannot be locked by the locking rod like when folded 90 degrees and 180 degrees. When the folding angle between the U-shaped groove object C 83 and the U-shaped groove object D 82 is 180 degrees, the locking rod 75 is stuck in the 180-degree folding locking groove 80 under the action of the locking rod tension spring 77 and is locked, and the hinge cannot be folded. At this time, only by pressing the unlocking operation handle 72, the locking rod 75 slides along the sliding groove 76 and leaves the 180-degree folding locking groove 80, and then the hinge can be folded. The locking principle when the hinge is folded to 90 degrees is the same; now as long as make a slight modification on this self-locking hinge: when folded to the angle that needs to be locked, set locking grooves of the same size as the 90-degree folding locking groove 78 on the left and right sides of the U-shaped groove object D 82, and the hinge can be locked at this folding angle; connect two objects through the bottom of the U-shaped groove object C 83 and the bottom of the U-shaped groove object D 82 and allow folding rotation between the two.

[0080] Hinge B has the following solutions: Solution 1 of Hinge B is a self-locking hinge with the same folding structure as the folding handlebar of a folding electric vehicle or a folding bicycle; Solution 2 of Hinge B is a self-locking hinge with the same structure as Solution 1 of Hinge A; Solution 3 of Hinge B is a self-locking hinge with the same structure as Solution 2 of Hinge A; Solution 4 of Hinge B is a self-locking hinge with the same structure as Solution 3 of Hinge A; Solution 5 of Hinge B is that between the front edges of two identical square plates, namely the upper plate A 62 and the lower plate A 63, there is a shaft hinge, which is the hinge shaft A 54; between the rear edges of the upper plate A 62 and the lower plate A 63, a connecting piece G 56 with the structure of a luggage spring duckbill buckle is used for connection and locking; the sizes of the upper plate A 62 and the lower plate A 63 are equivalent to the thickness of the seat tube of the seat bracket. When the connecting piece G 56 is loosened, the rear edges of the upper plate A 62 and the lower plate A 63 are disengaged, and the seat bracket can be folded forward; when the connecting piece G 56 is fastened, the rear edges of the upper plate A 62 and the lower plate A 63 are connected by the connecting piece G 56, and the seat bracket and the main bracket are connected into one body and cannot be folded forward; two objects are connected through the upper surface of the upper plate A 62 and the lower surface of the lower plate A 63, and folding rotation between the two is allowed.

[0081] A small folding bicycle includes a rear wheel assembly, a steering system, a braking system, a pedal sprocket drive assembly, a seat 19, and also includes the above-mentioned folding frame; the rear wheel assembly is a single-rear-wheel structure rear wheel assembly or a double-rear-wheel structure rear wheel assembly. When the rear wheel of the small folding bicycle is of a single-rear-wheel structure, the rear wheel assembly is a single-rear-wheel structure rear wheel assembly, which includes a rear wheel 22, a rear wheel axle, a rear fork 31, and a flywheel A 4. The rear wheel axle connects the rear wheel 22 and the flywheel A 4, and both ends of the rear wheel axle are connected to the tail of the rear fork 31; when the rear wheel of the small folding bicycle is of a double-rear-wheel structure, the rear wheel assembly is a double-rear-wheel structure rear wheel assembly, which includes a left rear wheel 1, a rear wheel axle 3, a right rear wheel 2, a rear wheel bearing assembly B, and a flywheel A 4. The rear wheel bearing assembly B includes two identical rear wheel bearings, two bearing sleeves B 6, and a fixing frame B 5. The two identical rear wheel bearings are respectively installed in the two identical bearing sleeves B 6. The fixing frame B 5 is an inverted U-shaped fixing frame. Both ends of the fixing frame B 5 are connected to the two bearing sleeves B6, and the upper surface of the fixing frame B 5 is a rectangular plane.

[0082] The tail of the second part 15 of the main bracket of the folding frame is connected and fixed to the rear wheel assembly. Specifically, when the rear wheel of the small folding bicycle is a single rear wheel structure, the rear wheel assembly is a single rear wheel structure rear wheel assembly, and the small folding bicycle is a small two-wheel folding bicycle. The tail of the second part 15 of the main bracket of the folding frame is connected and fixed to the head of the rear fork 31 of the single rear wheel structure rear wheel assembly. When the rear wheel of the small folding bicycle is a double rear wheel structure, the rear wheel assembly is a double rear wheel structure rear wheel assembly. The tail of the second part 15 of the main bracket of the folding frame is connected and fixed to the fixing bracket B 5 of the double rear wheel structure rear wheel assembly, and the small folding bicycle is a small three-wheel folding bicycle, which is especially suitable for the elderly to ride.

[0083] The seat cushion 19 is connected to the upper end of the seat post 32 of the seat cushion bracket of the folding frame.

[0084] The pedal sprocket drive assembly includes a bottom bracket assembly 13, a crank, a pedal 14, a large sprocket 12, an endless chain 18, and a flywheel A 4. Their assembly and connection relationship is the same as that of a traditional bicycle. The flywheel A 4 is the flywheel A in the rear wheel assembly. The large sprocket 12 and the flywheel A 4 are connected by the endless chain 18. The large sprocket 12, the endless chain 18, and the flywheel A 4 are arranged on the same side to be consistent. The pedal 14 is a foldable pedal.

[0085] The guiding system includes a front wheel 7, a front fork 10, a headset assembly, a handlebar 11, a stem 21, and a front wheel axle. The stem 21 is a telescopic stem. The lower tube of the stem 21 can be telescopically inserted into and out of the upper tube of the front fork 10, and a telescopic locking device C 30 is provided at the connection. The locking device C 30 is a seat post clamp C, or the stem 21 is a foldable stem, and the foldable stem is provided with a folding locking device. The handlebar 11 is a foldable handlebar.

[0086] The assembly and connection relationship between the described guiding system and the head tube 9 is the same as that of a traditional bicycle. The front fork 10 of the guiding system is connected to the head tube 9 of the folding frame through a headset assembly. Specifically, after the front fork 10 and the head tube 9 are assembled, in the position of the head tube 9 relative to the front fork 10, when the front fork 10 is folded backward, after the small folding bicycle is folded and the main bracket is erected, the front wheel 7 is located above and in contact with or close to the second part 15 of the main bracket in front of the rear wheel 22, and can be locked through the hinge A 20 of the folding frame. This can minimize the front-back dimension of the small folding bicycle after folding, facilitating placement and movement in crowded or narrow environments. After installing an auxiliary wheel on the small folding bicycle with a single rear-wheel structure, it can be towed with the rear wheel in the same way as a small folding bicycle with a double-rear-wheel structure; the front wheel 7 of the guiding system and the front fork 10 are folded backward or unfolded forward through the hinge A 20 of the folding frame. The hinge A 20 has a limit and locking when unfolded to the maximum angle to ensure that the bicycle guiding system is in the best position during riding after being fully unfolded again after folding. The maximum unfolding angle of the hinge A 20 is the riding state; after the front fork 10 is folded backward to the position and locked through the hinge A20, at this time the front wheel 7 is in contact with or close to the second part 15 of the main bracket. This can prevent the front wheel 7 from sagging under the action of gravity when the front wheel 7 is under the main bracket and towed with the rear wheel, affecting stable towing, and facilitating towing with the rear wheel in places with a small area and crowded people such as supermarkets and facilitating getting on and off escalators;

[0087] A bottom bracket assembly 13 is provided below and in front of the seat 19. The bottom bracket assembly 13 is perpendicular to the main bracket and is connected to the main bracket below the main bracket. After the seat bracket is folded forward, the seat 19 is located above the top of the first part 28 of the main bracket after retracting into the first part 28 of the main bracket; The unfolded form of this small folding bicycle is close to the shape of the letter N, and after being fully folded, it is close to the shape of the Roman numeral III. Its height and volume are very small, the structure is simple, the overall material used is less, and the weight is also light.

[0088] In order for the small folding bicycle to be able to carry more goods during riding and towing, and to be quickly packaged and smoothly enter subways and other public transportation, here an invention is made on a small folding bicycle cargo-carrying device, which can be quickly installed and fixed at the tail of the main bracket. It includes a cargo-carrying vehicle 95 and a quick connection and fixing device for the cargo-carrying vehicle. The described cargo-carrying vehicle 95 includes a cargo-carrying vehicle frame and a cargo bag 50. The cargo-carrying vehicle frame is provided with a cargo-carrying vehicle support plate 60 perpendicular to the two vertical bars at the tails of the two vertical bars of the "day" - shaped frame 58. At the left and right ends of the cross bar 96 at the bottom of the "day" - shaped frame 58, pulley C 26 is provided. The cargo bag 50 is a rectangular pocket, similar to the shopping bag on a shopping cart for buying groceries, and is installed on the cargo-carrying vehicle frame; furthermore, the cargo-carrying vehicle frame is designed to be telescopable up and down, and the cargo-carrying vehicle support plate can be folded forward and backward. At both ends of the tail of the cargo-carrying vehicle support plate 60, support feet B 55 or pulleys are provided;

[0089] With the quick connection and fixing device for the carrier vehicle, the carrier vehicle 95 can be quickly fixed to the rear of the small folding bicycle, above the rear wheel of the small folding bicycle. There are two solutions for the quick connection and fixing device of the carrier vehicle:

[0090] For the first solution of the quick connection and fixing device of the carrier vehicle, it includes a fixing block A 23 and a self-locking hinge E 24. The fixing block A 23 is provided with a fixing hole B 47 in a cuboid A. The bottom of the fixing block A 23 is connected to one end of a self-locking hinge E 24, and the other end of the self-locking hinge E 24 can be fixed to the tail of the main bracket of the small folding bicycle. The fixing block A 23 can be folded back and forth and the folding angle can be locked through the self-locking hinge E 24. In the middle of the cross bar 96 at the bottom of the frame of the matching carrier vehicle in the shape of a Chinese character "ri", a block A 97 is fixed. The block A 97 is provided with a fixing shaft B 98 at the bottom of a cuboid B. The fixing shaft B 98 is matched with the fixing hole B 47 and can just be inserted into the fixing hole B 47. The fixing shaft B 98 is a square shaft and the fixing hole B 47 is a square hole. In this way, the cross bar 96 at the bottom of the frame in the shape of a Chinese character "ri" cannot move in the front-back, left-right directions, so that the carrier vehicle connected to the block A can be fixed to the tail of the main bracket of the small folding bicycle. Further, the dimensions of the cuboid A and the cuboid B are the same in the front-back or left-right directions, and a locking device is provided in the up-down direction between the fixing block A 23 and the block A 97. By changing the folding angle of the self-locking hinge E 24, the placement angle of the carrier vehicle 95 can be changed;

[0091] For the second solution of the quick connection and fixing device of the carrier vehicle, it includes a carrier support plate 46 made of a rectangular iron plate and a self-locking hinge C 48. The bottom of the head of the carrier support plate 46 is connected to the tail of the main bracket of the small folding bicycle through the self-locking hinge C 48. The self-locking hinge C 48 has the functions of folding and locking the folding angle. At this time, a plurality of magnets are provided at the bottom of the carrier support plate 60 of the carrier vehicle. As long as the carrier vehicle 95 is placed on the carrier support plate 46, the magnets at the bottom of the carrier support plate 60 suck the carrier support plate 46, so that the carrier vehicle 95 and the small folding bicycle can be connected and fixed. By changing the folding angle of the self-locking hinge C 48, the placement angle of the carrier vehicle 95 can be changed;

[0092] When the small folding bicycle is folded and towed or placed upright, the angle between the main bracket and the square groove A or the carrier support plate 46 is folded to about 90 degrees. When the small folding bicycle is unfolded, the main bracket and the square groove A or the carrier support plate 46 are folded horizontally.

[0093] The self-locking hinge C and the self-locking hinge E have the following solutions: Solution 1. It is a hinge with the structure of a common hinge plus the hinge A in Solution 1. Specifically, after connecting the load-bearing support plate and the tail of the main bracket through a common hinge, a hinge with the structure of the hinge A in Solution 1 is set on the left or right side of the load-bearing support plate; Solution 2. It is a self-locking hinge with the structure of Solution 2 of the hinge A; Solution 3. It is a self-locking hinge with the structure of Solution 3 of the hinge A.

[0094] The size and height of the load bag 50 on the carrier 95 are such that the small folding bicycle can be folded and put into the load bag 50. An opening is provided from top to bottom on the back of the load bag 50, and a zipper A 59 or a magic tape is provided at the opening. If taking the subway, the carrier 95 can be quickly unloaded during inspection, and then the completely folded small folding bicycle can be put in. After passing the inspection, it can be directly towed with the carrier 95; further, in order to reduce the height of the load bag 50 during normal use, an extended bag mouth is also provided at the bag mouth of the load bag 50. Usually, it is turned inside out, and when it is necessary to load the folded small folding bicycle, the extended bag mouth is opened, which can extend the height of the load bag 50.

[0095] Further, in order to ensure the stability of the carrier 95 when the small folding bicycle is being towed and ridden, a carrier fixing part is provided at the top 61 of the carrier frame, which is used to connect with the seat post bracket; the carrier fixing part is one of the following solutions: 1. It is a buckle part A with the structure of a bicycle lamp holder clip. One end of the buckle part A is a buckle A that can buckle the top of the carrier frame, and the other end is a buckle B that can buckle the seat post bracket. Both the buckle A and the buckle B are equipped with locking devices; 2. It is a rubber strap with a fixed hook at the head; 3. It is a strip-shaped magic tape.

[0096] After the carrier fixing part is provided at the top of the carrier frame, the self-locking hinge C 48 and the self-locking hinge E 24 can use common hinges. Further, a folding seat A is provided on the rectangular frame 58.

[0097] In order to enable the small folding bicycle described above to play a greater role in people's lives in addition to the advantages of being convenient to carry, having a small volume and light weight after folding, a multi-functional small folding bicycle is invented here. Its characteristic is that a small folding bicycle carrier device is also installed at the tail of the small folding bicycle described above. In this way, the small folding bicycle can carry goods and ride, and can be quickly packaged and smoothly enter the subway and other public transports. A folding seat is provided on the rectangular frame 58 of the carrier 95. In this way, there is no need to worry about not having a seat when taking the subway and the bus. Since the rear wheel assembly of this small folding bicycle can also adopt a double rear wheel structure, the riding is safer, and it is especially suitable for the elderly to ride.

[0098] Further, in order to make the small folding bicycle with the small folding bicycle carrier device stable and labor-saving when being towed or pushed with the rear wheel after folding, and can enter the shopping mall for shopping, two auxiliary wheels with the same structure are arranged on the left and right sides of the tail of the main bracket of the small folding bicycle, the left auxiliary wheel 521 and the right auxiliary wheel 522. Specifically, there are two technical solutions for the auxiliary wheels:

[0099] For the first auxiliary wheel solution, pulleys are installed at the tails of two telescopic and lockable telescopic rods A 36. A cross bar A is horizontally arranged in the left-right direction at the tail of the second part 15 of the main bracket of the small folding bicycle. The cross bar A is perpendicular to the main bracket. The heads of the two telescopic rods A 36 are perpendicular to the head of the cross bar A and are respectively connected to the two ends of the cross bar A through two hinges F. The hinge F is a self-locking hinge with a folding angle locking function. The plane formed by the rotation of the telescopic rod A 36 through the hinge F is parallel to the rear wheel of the small folding bicycle. The length of the cross bar A should ensure that the telescopic rod A 36 will not touch the rear wheel assembly when rotating forward and backward through the hinge F. After the telescopic rod A 36 rotates forward to the maximum limited angle position, the hinge F has a position limiting and locking device. After the telescopic rod A 36 rotates backward to the maximum limited angle position, the hinge F has a position limiting and locking device; after the small folding bicycle is folded, when holding the bicycle handlebar and towing, the two telescopic rods A 36 rotate forward to the maximum limited angle position and are locked. The two telescopic rods A 36 are pulled out. When holding the bicycle handlebar and pushing, the two support rods A 36 rotate backward to the maximum limited angle position and are locked. The two telescopic rods A 36 are pulled out. The set maximum forward or backward rotation angle should make the center of gravity of the whole folded small folding bicycle located between the rear wheel of the small folding bicycle and the two auxiliary wheels of the small folding bicycle when placed vertically, so that towing and pushing are very easy. In this way, it can be placed vertically. When riding, the telescopic rod A 36 retracts and then rotates backward to be roughly parallel to the main bracket and is locked.

[0100] For the second auxiliary wheel solution, there is a support rod B including a first section of the support rod B and a second section of the support rod B. The connection between the first section of the support rod B and the second section of the support rod B is connected through a self-locking hinge D. The first section of the support rod B can be rotated and folded through the self-locking hinge D. The self-locking hinge D has folding 0-degree and 180-degree locking devices. Then, replace the telescopic rod A in the first auxiliary wheel solution with the support rod B, and the others are the same as those in the first auxiliary wheel solution. When it is necessary to use the auxiliary wheels for towing and pushing, the support rod B is unfolded. When it is necessary to ride, the first section of the support rod B rotates through the self-locking hinge D and then folds with the second section of the support rod B, and the support rod B rotates backward to be roughly parallel to the main bracket and is locked.

[0101] The hinge F and the self-locking hinge D can be the self-locking hinge with the structure of the first hinge A solution or the self-locking hinge with the structure of the second hinge A solution or the self-locking hinge with the structure of the third hinge A solution.

[0102] In order to prevent the bicycle handlebar from shaking when dragging the rear wheel of a small folding bicycle with the handlebar in hand and enable stable dragging, a bicycle handlebar locking device is also provided between the head tube and the upper part of the front fork. The bicycle handlebar locking device can be a locking device with a structure of a luggage spring duckbill buckle. After the bicycle handlebar locking device is locked, the bicycle handlebar cannot rotate. In this way, after two auxiliary wheels are arranged on both the left and right sides of the small folding bicycle, the small folding bicycle can carry more items after being folded, be pushed and dragged stably and labor-savingly, can enter a supermarket for shopping, and can be placed upright and carried with you when entering a restaurant for a meal.

[0103] Further, a rear wheel support plate A 25 is provided above the rear wheel of the rear wheel assembly with a single rear wheel structure. The rear wheel support plate A 25 is a rectangular plate, and its left and right sides are fixed to the rear fork through connecting pieces. The head of the rear wheel support plate A 25 is connected to the tail of the main bracket. A rear wheel support plate B is also provided above the rear wheel of the rear wheel assembly with a double rear wheel structure. The rear wheel support plate B is a rectangular plate, and the head of the rear wheel support plate B is connected to the tail of the main bracket. After the folding frame is unfolded, the rear wheel support plate A 25 and the rear wheel support plate B are horizontal.

[0104] Furthermore, an expansion mechanism is also provided on the rear wheel support plate A 25 or the load support plate 46 to make larger items such as travel suitcases placed on it more stable. There are two technical solutions for the expansion mechanism:

[0105] Expansion mechanism solution one: A left folding frame and a right folding frame are provided on the rear wheel support plate A 25 or the load support plate 46. They are U-shaped frames. The left side rod 34 of the left folding frame is fixed by two front and rear saddle clamps 33. The left folding frame rotates and unfolds or folds around the left side rod 34. The right folding frame is also arranged in the same way, except that the right side rod 35 of the right folding frame is fixed by the saddle clamp 33 of the right folding frame. The two frames are of different sizes. After the two frames are folded, they are nested with each other to form a square shape. A square boss A 37 is also provided in the middle of the rear wheel support plate A 25 or the load support plate 46. The height of the square boss A 37 is the same as the height of the saddle clamp 33. Two rubber sleeves A 53 are sleeved on the tail edges of the two unfolded folding frames respectively. The thickness of the rubber sleeve A 53 is the same as or slightly larger than the thickness of the saddle clamp. In this way, after the two folding frames are unfolded, they and the boss A 37 jointly support the heavy objects placed on them, and the area of the rear wheel support plate A 25 or the load support plate 46 can be increased.

[0106] Expansion mechanism solution two: It includes a box A 44, a left expansion part, and a right expansion part; the rear wheel support plate A 25 or the load support plate 46 is just the right size to cover the opening of the box A 44 and is connected and fixed to each other. At the bottom of the box A 44, a left expansion part is provided. The left expansion part includes a U-shaped part A 39, two round tubes 38, and two limit caps 40. At the front and rear ends on the left side of the box A 44, there is a round hole A 43 each. On the right side of the round hole A 43, a round tube 38 is fixed. The round tube 38 is fixed in the left-right direction on the bottom plate of the box A 44. The two ends of the head of the U-shaped part A 39 can freely pass through the round holes A 43 at the front and rear on the left side of the box A 44 and the round tube 38 on the right side. A limit cap is provided at the head of the U-shaped part A 39. A rubber sleeve B 41 is provided on the left side of the U-shaped part A 39, so that the top of the rubber sleeve B 41 and the plane of the rear wheel support plate A 25 or the load support plate 46 are on the same plane. Similarly, a right expansion part is provided on the right side of the box A 44, only the width of the U-shaped part B 42 on the right side is slightly smaller, so that it will not touch the U-shaped part A 39 when retracted, or the right expansion part and the left expansion part are of the same size, but are installed in a staggered manner with the left expansion part. When the left expansion part and the right expansion part are all pulled out, the support area of the rear wheel support plate A 25 or the load support plate 46 can be enlarged, and when all are retracted, they are hidden in the box A.

[0107] At least one fixing hole A or fixing ring is provided at the tail of the rear wheel support plate A 25, the rear wheel support plate B or the load support plate 46. In this way, the small folding bicycle can fix large items such as travel suitcases through a rubber band and carry them when traveling.

[0108] Furthermore, when the small folding bicycle does not need to install a load carrier, a child seat can be selectively installed. One end of a seat seat post is connected to the child seat, and the other end is connected to a block B. The block B has the same structure as the block A of the load carrier quick connection fixing device solution one, and the load carrier quick connection fixing device adopts the load carrier quick connection fixing device solution one. Furthermore, a locking device is provided on the cuboid A and the block B to ensure the firm fixed connection of the child seat; the child seat can also be installed on the rear wheel support plate A 25 or the rear wheel support plate B through the child seat seat tube; in this way, users can take their children out together with the small folding bicycle when needed.

[0109] Example two, see Figure 21and other attached drawings. This embodiment is Option 1 for the main bracket. The main bracket is a main bracket A 8, which is equivalent to connecting the first part 28 and the second part 15 of the main bracket in Option 2 of the main bracket. The head tube 9 in the attached drawing is at the position of the front fork. After the front fork is folded backward and the small folding bicycle is folded, when the main bracket stands up, the front wheel 7 is located above and in front of the rear wheel 22 and is close to or adjacent to the tail of the main bracket A 8. This can minimize the size of the small folding bicycle in the front-rear direction after folding. Here, it is similar to Embodiment 1 and can be referred to Figure 5 One end of the hinge A 20 is connected to the head tube 9 or connected to the head tube 9 through a connecting piece, and the other end of the hinge A 20 is connected to the head of the main bracket A 8 or connected to the head of the main bracket A 8 through a connecting piece; the tail of the main bracket A 8 is fixedly connected to the rear wheel assembly; the lower end of the hinge B 16 is connected to the tail of the main bracket A 8 or connected to the tail of the main bracket A 8 through a connecting piece; the handlebar stem is a foldable handlebar stem 88, and the foldable handlebar stem 88 is provided with a folding locking device C 87. At the same time, the handlebar tube of the handlebar stem is telescopic. The foldable handlebar stem 88 is a foldable handlebar stem with the same folding structure as the folding handlebar stem of a folding electric vehicle or a folding bicycle; the handlebar tube of the handlebar stem is a gooseneck handlebar tube 51; the other parts of Embodiment 2 are the same as those of Embodiment 1.

[0110] Through the above embodiments, the principle and design features of the present utility model can be understood, and those skilled in the art can manufacture it according to the embodiments. The present utility model has the characteristics of being practical and reliable, and having relatively high economic and social benefits after mass production.

[0111] Of course, the above embodiments are only for explaining the technical concept and features of the present utility model, and their purpose is to enable those who are familiar with this technology to understand the content of the present utility model and implement it accordingly, and cannot be used to limit the protection scope of the present utility model. Any modification made according to the spirit and essence of the main technical solution of the present utility model should be covered within the protection scope of the present utility model.

Claims

1. A small folding bicycle, characterized in that It includes a folding frame, a guiding system, a braking system, a pedal sprocket drive assembly, and a seat cushion; The folding frame includes a main bracket, a seat cushion bracket, hinge A, hinge B, and a head tube; There are two solutions for the main bracket. Solution 1: It is a main bracket A. Solution 2: It consists of a first part of the main bracket and a second part of the main bracket. The first part of the main bracket can telescopically slide relative to the second part of the main bracket. A locking device A is provided at the connection between the second part of the main bracket and the first part of the main bracket for locking the state after the first part of the main bracket is telescoped; The seat cushion bracket consists of a seat post, a seat tube, and a locking device B. The seat post can telescopically enter and exit the seat tube. A locking device B is provided at the connection between the seat tube and the seat post for locking the state after the seat post is telescoped; One end of hinge A is connected to the head tube or connected to the head tube through a connecting piece. The other end of hinge A is connected to the head of main bracket A or connected to the head of main bracket A through a connecting piece; or the other end of hinge A is connected to the head of the first part of the main bracket or connected to the head of the first part of the main bracket through a connecting piece. The head tube can be folded backward or unfolded forward relative to the main bracket through hinge A. Hinge A is a self-locking hinge with a limiting and locking device at the maximum unfolding angle; The lower end of hinge B at the bottom is connected to the tail of main bracket A or connected to the tail of main bracket A through a connecting piece, or the lower end of hinge B at the bottom is connected to the second part of the main bracket or connected to the second part of the main bracket through a connecting piece. The upper end of hinge B is connected to the lower end of the seat tube. Hinge B is a self-locking hinge with a folding position limiting and locking device when folded backward in place. After hinge B is locked, the seat cushion bracket cannot be folded. After hinge B is unlocked, the seat cushion bracket can be folded forward through hinge B; The guiding system includes a front wheel, a front fork, a headset assembly, a handlebar, a stem, and a front wheel axle. The front fork of the guiding system is connected to the head tube of the folding frame through the headset assembly; the front wheel of the guiding system and the front fork can be folded backward or unfolded forward through hinge A of the folding frame; The pedal sprocket drive assembly includes a bottom bracket assembly, a crank, a pedal, a large sprocket, an endless chain, and a flywheel A; The tail of the main bracket A or the tail of the second part of the main bracket of the folding frame is fixedly connected to the rear wheel assembly; the upper end of the seat post of the folding frame is connected to the seat cushion; The stem is a telescopic stem. The lower tube of the stem can telescopically enter and exit the upper tube of the front fork, and a telescopic locking device C is provided at the connection; or the stem is a foldable stem with a folding locking device; or the stem is a foldable stem with a folding locking device C, and at the same time, the handlebar tube of the stem is telescopic; The bottom bracket assembly is arranged directly below the front of the seat cushion. The bottom bracket assembly is perpendicular to the main bracket and is connected to the main bracket below the main bracket.

2. The small folding bicycle according to claim 1, wherein: The main bracket and the seat cushion bracket are in a tubular form. The first part of the main bracket can telescopically enter and exit the second part of the main bracket; hinge A also has a folding position limiting and locking device after folding backward in place; the locking device A is specifically a seat tube clamp A; the locking device B is specifically a seat tube clamp B; The specific solution of the hinge B is as follows: between two identical square plates, namely the upper plate A and the lower plate A, the front edges of the upper plate A and the lower plate A are pivotally connected by a hinge shaft A; between the rear edges of the upper plate A and the lower plate A, the upper plate A and the lower plate A are connected and locked by a connecting member G with a structure of a luggage metal spring duckbill buckle; the upper surface of the upper plate A is connected to the tail end of the seat cushion bracket, and a pipe A is connected to the lower surface of the lower plate A and can be connected to the main bracket; two objects are connected through the upper surface of the upper plate A and the lower surface of the lower plate A, and folding rotation between the two is allowed.

3. The small folding bicycle according to claim 1 or claim 2, characterized in that: At the position of the head tube on the front fork, after the front fork is folded backward, when the small folding bicycle is folded and the main bracket stands upright, the front wheel is located above the rear wheel, the front wheel is close to or adjacent to the tail of the main bracket A, or the front wheel is close to or adjacent to the second part of the main bracket, and is locked by the hinge A of the folding frame, so that the front and rear dimensions of the small folding bicycle after folding are minimized, facilitating placement or movement in a crowded or narrow environment. The telescopic locking device C is a seat post clamp C. The rear wheel assembly includes a single-rear-wheel structure rear wheel assembly and a double-rear-wheel structure rear wheel assembly; when the rear wheel assembly is a single-rear-wheel structure rear wheel assembly, the small folding bicycle is a small two-wheel folding bicycle, and when the rear wheel assembly is a double-rear-wheel structure rear wheel assembly, the small folding bicycle is a small three-wheel folding bicycle. Further, the rear axle of the double-rear-wheel structure is telescopic and is provided with a locking device in the telescoped state. The handlebar is a foldable handlebar; the footrest is a foldable footrest. When the main bracket is a single main bracket A, the handlebar tube of the upright head tube is a gooseneck handlebar tube.

4. A small folding bicycle carrier device that can be quickly installed on the small folding bicycle described in claim 1 or claim 2 or claim 3 and can be loaded into the small folding bicycle described in claim 1 or claim 2 or claim 3, characterized in that: It includes a carrier vehicle and a quick connection and fixing device for the carrier vehicle. The carrier vehicle includes a carrier vehicle frame and a carrier bag. The carrier vehicle frame is provided with a carrier vehicle support plate vertically at the tails of the two vertical bars of the H-shaped frame, and pulleys C are provided at the left and right ends of the cross bar at the bottom of the H-shaped frame; the carrier bag is a rectangular pocket that can hold the folded small folding bicycle, and the carrier bag is installed on the carrier vehicle frame; through the quick connection and fixing device for the carrier vehicle, the carrier vehicle is quickly fixed at the tail of the small folding bicycle according to claim 1 or claim 2 or claim 3, above the rear wheel of the small folding bicycle.

5. The small folding bicycle carrier device according to claim 4, wherein: The carrier vehicle frame is telescopable up and down, and support feet B or pulleys are provided at both ends of the tail of the carrier vehicle support plate; the size and height of the carrier bag can hold the folded small folding bicycle. An opening is provided from top to bottom on the back of the carrier bag, and a zipper A or a magic tape is provided at the opening. An extended bag mouth is also provided at the bag mouth of the carrier bag, which is usually turned inward and is turned open when the folded small folding bicycle needs to be loaded to extend the height of the carrier bag; a folding seat A is provided on the H-shaped frame. There are two solutions for the quick connection and fixing device of the carrier vehicle: Solution 1 of the quick connection fixing device for the cargo vehicle: it comprises a fixing block A and a self-locking hinge E. The fixing block A is provided with a fixing hole B on a rectangular parallelepiped A. The bottom of the fixing block A is connected to one end of a self-locking hinge E. The other end of the self-locking hinge E is fixed to the tail of the main bracket of the small folding bicycle. The fixing block A can be folded forward and backward and the folding angle can be locked through the self-locking hinge E. A clamping block A is fixed to the middle part of the crossbar at the bottom of the Japanese-shaped frame of the matching cargo vehicle frame. The clamping block A is provided with a fixing shaft B at the bottom of a rectangular parallelepiped B. The fixing shaft B is matched with the fixing hole B and can be just inserted into the fixing hole B. Furthermore, the rectangular parallelepiped A and the rectangular parallelepiped B have the same size in the front-to-back direction or the left-to-right direction. A locking device is provided in the upper and lower directions of the fixing block A and the clamping block A. Solution 2 of the cargo trolley quick connection fixing device: it includes a cargo support plate made of a rectangular iron plate and a self-locking hinge C. The bottom of the cargo support plate head is connected to the tail of the small folding bicycle main bracket through the self-locking hinge C. The self-locking hinge C has the functions of folding and folding angle locking. A plurality of magnets are arranged at the bottom of the cargo support plate. A cargo vehicle fixing part is also provided on the top of the cargo vehicle frame for connecting with the seat support; the cargo vehicle fixing part is one of the following solutions:

1. a buckle part A of a bicycle light stand clamp structure, one end of the buckle part A is buckled to the top of the cargo vehicle frame, and the other end is buckle B buckled to the seat support, and both buckle A and buckle B are provided with locking devices; 2. a cow tendon strap with a fixing hook on the head; 3. a strip of Velcro; After the cargo vehicle fixing parts are arranged on the top of the cargo vehicle frame, the self-locking hinge C and the self-locking hinge E are ordinary hinges.

6. A multi-functional small folding bicycle comprising the small folding bicycle described in claim 1 or claim 2 or claim 3, characterized in that: At the same time, the small folding bicycle carrying device according to claim 4 or claim 5 is installed at the tail of the small folding bicycle according to claim 1 or claim 2 or claim 3.

7. The multifunctional small folding bicycle according to claim 6, characterized in that: Two auxiliary wheels with the same structure are arranged on the left and right sides of the tail of the main support of the small folding bicycle, namely, a left auxiliary wheel and a right auxiliary wheel, so that the multifunctional small folding bicycle can be dragged or pushed labor-savingly after being folded.

8. The multifunctional small folding bicycle according to claim 7, characterized in that: There are two technical solutions for the training wheels: Auxiliary wheel scheme 1 is that pulleys are installed at the tail of two telescopic rods A with telescopic locking function, a cross bar A is horizontally arranged in the left and right directions of the tail of the main frame of the small folding bicycle, the cross bar A is perpendicular to the main frame, the heads of the two telescopic rods A are perpendicular to the heads of the cross bar A, and are respectively connected to the heads at both ends of the cross bar A through two hinges F, the hinge F is a self-locking hinge with a folding angle locking function, the plane formed by the rotation of the telescopic rod A through the hinge F is parallel to the rear wheel of the small folding bicycle, the length of the cross bar A is such that the telescopic rod A will not touch the rear wheel assembly when rotating forward and backward through the hinge F, the two telescopic rods A are rotated forward or backward to a limited maximum angle position and locked, and after the two telescopic rods A are pulled out, the maximum angle is set so that the center of gravity of the entire folded small folding bicycle when placed upright is located between the rear wheel of the small folding bicycle and the two small folding bicycle auxiliary wheels; Auxiliary wheel solution two: There is a support rod B including the first section of support rod B, the second section of support rod B. The connection between the first section of support rod B and the second section of support rod B is connected by a self-locking hinge D. The first section of support rod B can be rotated and folded through the self-locking hinge D. The self-locking hinge D has folding locking devices at 0 degrees and 180 degrees. Then, replace the telescopic rod A in the auxiliary wheel A solution one with the support rod B, and the others are the same as those in the auxiliary wheel solution one; A bicycle head locking device is provided between the head tube of the small folding bicycle and the upper part of the front fork.

9. The multi-functional small folding bicycle according to claim 8, characterized in that: The bicycle head locking device is a locking device with a structure of a luggage spring duckbill buckle; Above the rear wheel of the rear wheel assembly of the single rear wheel structure of the small folding bicycle, there is a rectangular rear wheel support plate A; above the rear wheel of the rear wheel assembly of the double rear wheel structure, there is a rectangular rear wheel support plate B. After the folding frame is unfolded, the rear wheel support plate A and the rear wheel support plate B are horizontal. At least one fixing hole A or fixing ring is provided at the tail of the rear wheel support plate A, the rear wheel support plate B or the load support plate; further, an expansion mechanism is also provided on the rear wheel support plate A or the load support plate. There are three technical solutions for the expansion mechanism: Expansion mechanism solution one: On the rear wheel support plate A or the load support plate, there are a left folding frame and a right folding frame. They are square frames. The left side rod of the left folding frame is fixed by two front and rear saddle clamps. The left folding frame rotates and unfolds or folds with the left side as the axis. The right folding frame is also arranged in the same way, except that the right saddle clamp fixes the right side rod of the right folding frame. The two frames are of different sizes. After the two frames are folded, they are nested with each other to form a square shape. In the middle of the rear wheel support plate A or the load support plate, there is also a square boss A. The height of the square boss A is the same as the height of the saddle clamp. On the tail edges of the two folding frames after unfolding, there are two rubber sleeves A each. The thickness of the rubber sleeve A is the same as or slightly larger than the thickness of the saddle clamp; Expansion mechanism solution two: It includes a box A, a left expansion part, and a right expansion part; the rear wheel support plate A or the load support plate is just the right size to cover the opening of the box A and is connected and fixed to each other. At the bottom of the box A, a left expansion part is provided. The left expansion part includes a U-shaped part A, two round tubes, and two limit caps. At the front and rear ends of the left side of the box A, there is a round hole A each. On the right side of the round hole A, a round tube is fixed. The round tube is fixed in the left-right direction on the bottom plate of the box A. The two ends of the head of the U-shaped part A can freely pass through the round holes A at the front and rear of the left side of the box A and the round tube on the right side. A limit cap is provided at the head of the U-shaped part A. A rubber sleeve B is provided on the left side of the U-shaped part A so that the top of the rubber sleeve B and the plane of the rear wheel support plate A or the load support plate are in the same plane. Similarly, a right expansion part is provided on the right side of the box A, except that the width of the right U-shaped part B is slightly smaller, or the right expansion part is the same size as the left expansion part, but is installed in a staggered manner with the left expansion part. When the left expansion part and the right expansion part are all pulled out, the supporting area of the rear wheel support plate A or the load support plate can be enlarged, and when all are retracted, they are hidden in the box A; Expansion mechanism solution three: Fix the left and right expansion parts of the expansion mechanism solution two at the bottom of the rear wheel support plate A. The structure is the same as that of the expansion mechanism solution two. When the left and right expansion parts are fully pulled out, the support area of the rear wheel support plate A can be enlarged. For aesthetics, the left and right expansion parts can be packaged with a box, but there should be through holes on both sides that can pass through the U-shaped part A.

10. The multifunctional small folding bicycle according to claim 9, characterized in that: It also includes a child seat. One end of the child seat rod is connected to the child seat, and the other end is connected to a block B. The block B has the same structure as the block A of the quick connection and fixing device for the carrier vehicle solution one. And the quick connection and fixing device for the carrier vehicle adopts the quick connection and fixing device for the carrier vehicle solution one. Further, a locking device is provided in the up and down directions of the cuboid A and the block B to ensure the firm fixed connection of the child seat; or the child seat is installed on the rear wheel support plate A or the rear wheel support plate B through the child seat tube.

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