Folding tricycle

Abstract

Three-wheeled bicycles, which absorb shocks from the road surface and utilize the moment of inertia of the wheels, are not practical unless the wheels are at least 20 inches in diameter. However, conventional folding technology involves connecting the front frame that supports the front wheel and the rear frame that supports the two rear wheels with a single frame, and then folding it horizontally or crossing it vertically near the center. This results in a thicker frame and does not allow for very compact folding. [Solution] The rear two wheels are of the splayed type, with a basically triangular frame structure, and a combination of a foldable round handle and a top tube that is rotatably mounted on the head tube, and a hinge mechanism reinforced with an inner pipe is provided at or near the point on the down tube where the distance to the front wheel axle and the rear wheel axle is the same, providing a folding method that allows the front wheel to be compactly stored between the rear two wheels in just three steps.

Description

Technical Field

[0001] The present invention relates to a folding method for a tricycle.

Background Art

[0002] A typical two-wheeled bicycle basically has a triangular frame structure consisting of a top tube, a down tube and a seat tube, while small-diameter two-wheeled and three-wheeled bicycles with a wheel size of about 20 inches or smaller have a structure in which the frame supporting the front wheel (front frame) and the frame supporting the rear wheel (rear frame) are supported by a single pipe (main pipe), with a hinge mechanism, a four-bar linkage or the like provided at the intermediate portion thereof to be folded horizontally, or simply crossed in an X-shape to be folded vertically.

[0003] Regarding folding methods for tricycles for infants and children and other tricycles of similar small diameter, there are multiple patent cases related to vertical folding, but they are not suitable for tricycles of 20 inches or larger.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

[0005] In order to allow a bicycle to travel stably, the wheel diameter needs to be at least about 20 inches to reduce impacts from road surface unevenness and make use of the moment of inertia, and in addition, the distance between the front and rear wheels (wheelbase) also needs to be lengthened to a certain extent to make use of the restoring force of the handlebar.

[0006] In this case, if there is only one pipe supporting the front and rear frames, the load will be concentrated only on the bent section in the middle. To withstand this load, the pipe must be made thicker, increasing the weight and making it unsightly. Furthermore, when folding a three-wheeled bicycle horizontally, the folding point must be closer to the handlebars rather than the center of the main pipe to prevent the front wheel from overlapping with the rear wheel. As a result, even when folded, the overall length cannot be reduced to half, the width remains wide, and the handlebars get in the way. Means to solve the problem

[0007] This invention, even for a three-wheeled bicycle, reduces the load on the folding part by using a frame with the original triangular frame structure of a bicycle, and assuming a wheel diameter of about 20 inches, features a combination of a handle section that can fold a round handle downwards and a top tube that can rotatably fold, and a hinge mechanism provided on the down tube that allows the front wheel to be compactly folded between the two rear wheels with minimal effort.

[0008] A three-wheeled bicycle with a wheel diameter of around 20 inches and a reasonable wheelbase, which can easily travel by utilizing the moment of inertia of the wheels and does not experience significant shocks from the difference in road surface between sidewalks and roads at intersections, can be folded compactly in just three steps, making it easy to carry onto trains and buses or store in lockers at stations. Bicycle parking facilities around stations can be made into multi-story structures to accommodate many bicycles. If the bicycle is not often brought onto trains, the tripod configuration shown in Example 2 can be used as a shopping cart in supermarkets. In any case, in apartment buildings where there is no open space, it can be folded and taken into one's room, and it also helps prevent theft of the batteries attached to the bicycle. Furthermore, in rural areas where there are few trains or buses, it is convenient for children to commute long distances to school, and it is a comfortable and safe means of transportation for the elderly.

[0009] Furthermore, since there will be no need to drive a car just to go shopping nearby, energy will be saved and it will contribute to mitigating global warming, so its social benefits are immense. [Brief explanation of the drawing]

[0010] [Figure 1] This is an image illustrating the folding mechanism of the three-wheeled bicycle in question, where the front wheel is stored between the rear wheels, which are positioned in a splayed configuration. [Figure 2] This is a three-dimensional diagram illustrating the three-wheeled bicycle in motion. A drive shaft passes through the upper part of the splayed left and right seat stays, with a gear in the middle that transmits propulsion from the front gear. Gears are provided at both ends of this shaft, through which a chain that transmits propulsion to a gear on the hub that supports the rear wheel is attached. [Figure 3] This is a front view of the three-wheeled bicycle in motion (cranks and pedals are omitted). After folding the round handlebars, the top tube is rotated around axis 2 as shown by the dotted line, and the handle 10 attached to the hinge 9 on the down tube is lifted, causing the front frame to be stored inside the rear frame as shown by the dotted line, with axis 9 being the same distance from the front and rear wheel axles. [Figure 4] This is a front view (illustration) of the rear frame, which connects to the front frame at the folding hinge 9 on the downtube. The seatpost is housed inside the seat tube. [Figure 5] This is a front view (illustration) of the front frame, which connects to the rear frame in Figure 4 via the folding hinge 9 on the downtube. The round handlebars are folded. [Figure 6] This is a front view (image) of the tricycle after it has been folded. The angle of inclination with respect to the road surface (dotted line) in this figure represents the image of moving the vehicle by rolling it while pulling it. The angle of inclination is constrained by the length of the mudguards on the two rear wheels and the rear cargo rack. Note that if the folding section on the down tube is positioned slightly off-center from the center of the rotation axis of the front and rear wheels, the folded tricycle will stand upright and can be moved by pushing it. (Example 2) [Figure 7] This is a plan view (image) of the rear frame when the tricycle is folded. Power transmitted from the crank pedal via the chain is transmitted to the gears of the two rear wheels via gears on both sides that are directly connected to the gears of the drive shaft. [Figure 8]This is a front view (illustration) of the rear frame of the tricycle in question when it is folded. [Figure 9] This is a plan view of a round handle that can be folded using hinges 15 (left and right). The handle section 14 other than the folding section is fixed to the handle stem 13, and the round handle of the folding section 16 is supported by the rotating bracket 17 shown in Figure 12 when riding. [Figure 10] This is a plan view of the handle section after it has been folded. [Figure 11] This is a front view of the handle section after it has been folded. [Figure 12] This is a front view of a rotating bracket that supports a foldable round handle. [Figure 13] This is a plan view of pipe 5, which makes up the top tube. The distance between the two pipes is such that when the support pipe 4 is rotated around axis 2, it does not interfere with the folded handlebars, handlebar post, head tube, and front wheel tire. [Figure 14] This is a plan view of the bracket 1 on the head tube into which the top tube's pivot point 2 is fitted. [Figure 15] This is a plan view of the stopper 3, which is mounted on the seat tube to receive the support pipe 4 at the tip of the rotating top tube during riding, and the L-shaped lever 20, which is mounted on the seat tube to capture and fix 4. Inside the support pipe 4 at the tip of the top tube, an inner pipe connected to a compression spring 18 is inserted, and an L-shaped lever 19 is welded to its head (cap) in a position that allows it to capture the seat tube when the compression spring is pulled. This lever is also used to fix the tip of the top tube, which is left dangling when the three-wheeled bicycle is folded, to the front wheel tire. Lever 20 is a safety valve in case of an impact strong enough to break lever 19. [Figure 16]This is an exploded view of the folding part provided on the down tube. When the knob 22 attached to the inner pipe 21 is moved along the L-shaped guide hole 23 provided in the upper down tube 5, the inner pipe can be dropped downward, so the flange 24 welded to 5 and the flange 25 welded to the lower down tube 6 are separated at the hinge 9, and the front frame is received inside the rear frame. [Mode for Carrying Out the Invention]

[0011] When folding the present three-wheeled bicycle, after folding the round handle, as shown in Fig. 3, lift and rotate the top tube (Fig. 13) at 4 around the rotation shaft 1 provided on the head tube, and it will stop at the position where it contacts the front wheel tire. As shown in Fig. 16, when the knurled screw 22 of the inner pipe 21 inserted into the corresponding part is rotated along the L-shaped hole 23 provided in the upper pipe 5 of the hinge mechanism 9 of the down tube, the inner pipe can be dropped downward, the hinge mechanism is released, the front frame (Fig. 5) is folded at the hinge 9 on the down tube, and as shown in Fig. 6, the front wheel is received inside the spread-leg type rear frame that pivotally supports the two rear wheels.

[0012] To fold the three-wheeled bicycle vertically, it is essential that the two rear wheels are of the spread-leg type, and for bicycles with small-diameter wheels and a short wheelbase, it is necessary to ride in a somewhat forward-leaning posture, so a round handle that combines the stability of a semi-upright handle and the running performance of a flat handle is indispensable.

[0013] Although the present invention utilizes known techniques for the folding method of each pipe and the like itself, it is characterized in that the tricycle can be compactly folded vertically to half of its total length by the combination of a unique top tube that can rotate across the folded handlebar and a hinge mechanism reinforced by an inner pipe on the down tube, and further, the conventional triangular front frame and rear frame of a two-wheeled bicycle can be used as they are by only subjecting the down tube to a simple processing. In addition, compared with two-wheeled bicycles, tricycles have smaller wheels, which requires the saddle to be raised accordingly, making them prone to tipping sideways when pedaling, but by using electric assist, the number of pedaling strokes can be reduced, and the feet can reach the ground when starting off, so the width of the two rear wheels is safe as long as it is approximately the width of a stand for a normal adult two-wheeled bicycle, and when folded, the tricycle can be stored in a coin locker at a station or the like. [Examples]

[0014] Figure 6 shows a case where the hinge on the down tube is provided at a position equidistant from the front wheel axle and the rear wheel axle, and the front wheel and the rear wheel overlap on the same axis, which is suitable for rolling and moving the vehicle body while holding the handle portion and pulling it. (The positional relationship between the rear wheel fender carrier and the rear wheel tire results in the inclination angle as shown in Figure 6.) [Examples]

[0015] If the position of the hinge on the down tube is not set to be equidistant from the front and rear wheels but is slightly shifted, the folded tricycle can stand on its own, so it can be moved by pushing as it is. [Industrial Applicability]

[0016] The present invention is a tricycle based on the triangular frame structure of two-wheeled bicycles currently used worldwide, wherein the top tube thereof is modified to a structure that is rotatable on the head tube, the handle is simply made a foldable round handle, a hinge mechanism reinforced with an inner pipe is provided on the down tube to fold the front wheel between the two rear wheels, and the existing pipes of current two-wheeled bicycles can be used as they are for the frame members. [Description of Reference Signs]

[0017] 1. Bracket with rotating bearing 2. Top tube rotation axis (support pipe) 3. Top tube support stopper 4. Top tube support pipe 5 Top tube 6. Top of the downtube 7. Lower part of the downtube 8. Connection point of the downtube to the crank axle 9. Downtube hinge mechanism 10 Handle attached to the flange of the hinge labeled 9 11 Rear wheel suspension 12. Intermediate drive shaft that transmits the propulsive force from the pedals to the two rear wheels. 13. Handle stem axis 14. Central fixing part of the round handle 15. Hinges (left and right) for folding the round handle downwards. 16. Foldable handle section 17. Rotating bracket supporting the foldable round handle. 18 Compression spring fixed inside the support pipe of reference numeral 4 19 An L-shaped lever provided on the head (lid) of the inner pipe welded to the compression spring of reference numeral 18. 20 An L-shaped lever that secures the support pipe indicated by reference numeral 4, which is mounted on the seat tube. 21. Inner pipe to reinforce the folding section of the downtube. 22. Knob that slides on the inner pipe 23 L-shaped hole for guiding the knob labeled 22 24. Flange to be welded to the upper part of the bent downtube 5. 25 A flange welded to the lower part 6 of the bent downtube, opposite to the flange of reference numeral 24.

Claims

[Claim 1] This adult three-wheeled bicycle features a frame consisting of a rear frame comprising a splayed seat stay, seat tube, and chain stay that pivotally support the two rear wheels, and a front frame comprising a fork, head tube, top tube, and down tube that pivotally support the front wheel. It is characterized by a foldable handle lever and a top tube that rotates freely around a single point on the head tube without interference from the handlebars, etc., and a hinge mechanism reinforced with an inner pipe is provided on the down tube at or near a point where the rotation axes of the front wheel and the rear wheel are the same distance apart, allowing the front wheel to be compactly folded between the two splayed rear wheels.

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