CN217554102U

CN217554102U - Chainless foldable tricycle

Info

Publication number: CN217554102U
Application number: CN202221394650.5U
Authority: CN
Inventors: 孔立明; 孔维来; 杨婵
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-06-07
Filing date: 2022-06-07
Publication date: 2022-10-11
Anticipated expiration: 2032-06-07

Abstract

The utility model discloses a chainless foldable tricycle, which comprises a front wheel for guiding, a middle driving wheel for driving, a rear wheel for supporting, a front rod, a handle, a beam, a driving wheel rod, a rear rod and a cushion component; the folding device is arranged on the cross beam, the front wheel and the rear wheel are consistent in size, and the front wheel and the rear wheel are overlapped after being folded by 180 degrees; the pedal assembly is directly connected with the central transmission assembly of the driving wheel to realize direct driving; the diameters of the front wheel and the rear wheel are 1/4 to 3/4 of the diameter of the driving wheel; the seat center is positioned behind the center of the driving wheel; the pedal connecting rod adopts a telescopic device and is used for speed regulation; a reinforcing rod can be additionally arranged between the driving wheel rod and the rear rod and used for increasing the firmness and the bearing property of the whole vehicle. The improvement is that the chainless coaxial transmission bicycle in the prior art is transformed into a chainless bicycle with simpler structure, more comfortable riding, more controllable production cost, more convenient folding and adjustable speed. The utility model belongs to the technical field of be the bicycle field.

Description

Chainless foldable tricycle

Technical Field

The utility model belongs to the technical field of for the bicycle field, especially, relate to a collapsible tricycle of no chain, its improvement part is that the chainless coaxial transmission double round bicycle of no chain among the prior art and tricycle reform transform into a structure more brief, ride more comfortable, manufacturing cost is more controllable, folding more convenient, the chainless bicycle of adjustable speed.

Background

The background art of the utility model includes the following prior art: "a rear-drive chainless bicycle" (see utility model patent application No. 202220154810.2), "a chainless bicycle" (see utility model patent application No. 202020087158.8), "an inflation-free maintenance chainless bicycle" (see utility model patent application No. 201720393138.1), "a chainless bicycle" (see brazilian patent application No. BRPI 9204947), "a vertical absorbing device of a chainless bicycle" (see japanese patent application No. JP 05002489U), "a chainless bicycle" (see japanese patent application No. JP 2009119990A), "a chainless bicycle" (see korean patent application No. KR 2020111840016), "a chainless tricycle" (see patent application No. 20159201.5), "a chainless transmission bicycle" (see patent application No. KR 2021940101940109.3), "a chainless transmission (see coaxial patent application No. 201727925)," a bicycle transmission mechanism "(see the prior art patent application No. wo patent application No. 20100072727262951), and" a bicycle transmission mechanism "(see the prior art on No. 20172629 31.5), and" a bicycle chain-free transmission chain (see the following patent application No. 12.31).

The prior art adopts the technical means of chainless coaxial transmission, but still has the following problems and disadvantages.

First, in the case of a two-wheeled bicycle, whether front-wheel-drive or rear-wheel-drive is used, problems of riding discomfort or safety arise.

For example: in the scheme of front wheel driving, when a rider rides in a normal posture, the gravity center of the rider is too far ahead, and the rider is easy to tilt forward and fall down during emergency braking or downhill; if the cushion moves backwards, although the gravity center also moves backwards, the leg-kicking action direction of the rider needs to be adjusted forwards, so that the rider is more strenuous to ride.

For another example: in the rear wheel driving scheme, when a rider rides in a normal posture, the gravity center of the rider is too far behind, and the rider is easy to lean backwards and fall down when suddenly accelerating or ascending a slope; if the cushion moves forward, although the center of gravity also moves forward, the pedaling direction of the rider needs to be adjusted backward, so that the rider is more strenuous to ride.

It follows that a rider, whether using front or rear wheel drive, faces a "front to rear" embarrassment. The problem is actually caused by the fact that the position relations of the hands, the feet and the buttocks are relatively fixed when the human body rides. This relatively fixed positional relationship determines that chainless coaxial drive solutions are difficult to adapt to a two-wheeled bicycle. In other words, the chainless coaxial transmission technical scheme is more suitable for the tricycle.

Secondly, as for the tricycle, a mature technical scheme does not exist in the prior art scheme, and especially, a chainless coaxial transmission bicycle which has a simpler structure, is comfortable to ride, is controllable in production cost, is convenient to fold and can adjust the speed is not available.

For example: in japanese patent application No. JP2009119990A, the driving wheel is small, has no speed regulation function, and is low in riding speed; there is no ideal folding device; the connection structure and the transmission assembly are relatively complicated.

Another example is: in the invention patent application with application number 201510359201.5, the technical scheme is very simple and rough, and a technical scheme with strong practicability is not proposed.

And the following steps: in the invention patent application with application number 202010194759.3, the bicycle is not foldable; the driving wheel in the middle and the three connecting rods are intersected on the side face, so that the connecting rods are arranged on both single side and double sides and are complex; the three-stage speed change mechanism inside the intermediate driving wheel is also complicated.

The following steps are repeated: in the utility model patent with application number 201720002751.6, the middle driving wheel and the three connecting rods all have intersection on the side surface, and the scheme of arranging the connecting rods on two sides is usually adopted, so that the driving wheel can be in the 'embracing' of the connecting rods, although the structure is simpler when viewed from the side attached drawing, the actual solid view of the driving wheel is complicated; in addition, because of the scheme that the connecting rods are arranged on the two sides of the driving wheel, the front and back folding devices are inevitably bulky, so that the folding effect is not ideal.

Disclosure of Invention

In order to solve the problem, the utility model provides a collapsible tricycle of no chain, its aim at designs a structure more brief, ride more comfortable, manufacturing cost more controllable, folding more convenient, the chainless bicycle of adjustable speed.

To achieve the above object, the present invention has the following considerations in its overall concept.

Firstly, the structure of the bicycle is as simple and as simple as possible, and the frame of the tricycle is built up by using as few connecting rods as possible.

Secondly, because of having removed the traditional chain that can promote the drive ratio, in order to guarantee the speed of riding, the diameter of drive wheel can not too little. Therefore, in order to reduce the volume and length of the whole vehicle, the front wheel and the rear wheel must use small-size wheels, the two wheels are as consistent as possible so as to be mutually exchanged, and the sizes of the wheels are as uniform as possible, so that the cost and the quality are also favorably controlled.

Moreover, because the driving wheel is larger, in order to ensure the simple structure of the whole vehicle, the intersection of other parts and the driving wheel should be reduced as much as possible on the side surface.

Fourthly, no matter how the height of the handlebar and the height of the cushion are adjusted according to the height of a rider and the requirement of the rider, the rider can keep a comfortable posture for riding, and therefore the position relation of hands, feet and buttocks needs to be kept reasonable as much as possible.

Fifthly, because there is no speed regulating mechanism formed by the traditional chain and gear set, a simple speed regulating mechanism is needed to be added in the technical scheme of chainless coaxial transmission so as to meet the speed requirements of riders under different situations.

Finally, the ease of folding needs to be further improved. The best proposal is to arrange a folding device at the approximate middle position of the vehicle body as much as possible, and the front and the rear wheels are overlapped as much as possible after being folded, so that the volume is smaller after being folded and the vehicle is convenient to drag.

In order to achieve the above object, the present invention provides a chainless foldable tricycle, comprising: front wheel, front rod, handle; a cross beam, a folding hinge; a drive wheel, a drive wheel center bearing, a drive wheel center drive assembly, pedals, pedal links (also referred to as "cranks" in conventional bicycles), a drive wheel lever; a cushion and a cushion support rod; a rear wheel, a rear lever; the method is characterized in that: the front wheel is a guide wheel, and a bearing of the front wheel is connected with one end of the front rod, which is close to the ground; the front wheel rotates around a bearing of the front wheel in a forward direction or a reverse direction; a sleeve hole at the front end of the cross beam is sleeved on the front rod to be in pivot connection; the upward end of the front rod is connected with the handle; the front rod is driven to rotate left and right by rotating the handle, so that the front wheel is driven to rotate left and right; the cross beam is basically parallel to the ground; the cross beam is provided with a folding hinge, and after the hinge is unfolded, the bicycle is folded at the hinge position by nearly 180 degrees; the driving wheels are positioned below the cross beam and between the front wheels and the rear wheels; the driving wheel is provided with two pedals and two pedal connecting rods, one end of each pedal connecting rod is connected with the corresponding pedal, and the other end of each pedal connecting rod is connected with the central transmission assembly of the driving wheel; when the pedal is stepped to ride forwards, the pedal sequentially drives the pedal connecting rod, the driving wheel central transmission assembly and the driving wheel to rotate; one end of the driving wheel rod close to the ground is connected with the driving wheel center bearing; the driving wheel rotates around the driving wheel central bearing in a forward direction or a reverse direction; the driving wheel rod is fixedly connected with the cross beam, and the driving wheel rod and the cross beam cannot move relatively, so that the driving wheel and the cross beam are always in the same plane; the rear end of the cross beam is fixedly connected with the rear rod, and the cross beam and the rear rod cannot move relatively, so that the rear wheel and the cross beam are always in the same plane; the rear wheel is a supporting wheel, and a bearing of the rear wheel is connected with one end of the rear rod, which is close to the ground; the rear wheel rotates around a bearing of the rear wheel in a forward direction or a reverse direction; the diameter of the front wheel is substantially the same as the diameter of the rear wheel; the geometrical centers of the front wheel, the rear wheel and the hinge form a triangle, the bottom edge of the triangle is basically parallel to the ground, and the left edge and the right edge of the triangle are basically equal, so that after the bicycle is folded by approaching 180 degrees through the hinge, the front wheel and the rear wheel are basically overlapped; the diameters of the front wheels and the rear wheels are both larger than 25% of the diameter of the driving wheel and are both smaller than 75% of the diameter of the driving wheel; the geometric center of the cushion and the circle center of the driving wheel are connected into a straight line, and the included angle between the straight line and the vertical line of the ground is more than 5 degrees and less than 60 degrees; the ground vertical projection of the geometric center of the cushion is positioned behind the ground vertical projection of the circle center of the driving wheel, and the distance between the two projections is more than 5 cm and less than 60 cm; when the bicycle is completely unfolded, the lowest points of the front wheel, the driving wheel and the rear wheel are on the same straight line; the supporting rod of the cushion is fixedly connected with the cross beam and cannot move relatively. The ground vertical line is a straight line perpendicular to the ground at the contact point of the driving wheel and the ground.

The utility model also provides a but collapsible tricycle of chain of speed governing, its characterized in that: the pedal link (also referred to as a "crank" in conventional bicycles) includes a sleeve and a screw having a diameter substantially the same as the diameter of the sleeve's internal cavity; the inner cavity of the sleeve and the screw rod are both provided with threads and correspond to each other; when the screw rod or the sleeve is screwed in the clockwise or anticlockwise direction, the screw rod gradually enters the sleeve, so that the length of the pedal connecting rod is shortened; when the screw or the sleeve is screwed in the opposite direction, the screw gradually protrudes out of the sleeve, so that the length of the pedal link is extended. The speed regulation scheme actually comprises two implementation modes, namely screwing the screw and screwing the sleeve. It is generally preferred that the screw be threaded and the sleeve remain stationary so that the pedal is folded 90 degrees and erected to allow more room for the screw to be threaded and not obstructed by the steel bars on the drive wheel. With regard to the screwing direction, it is generally preferred that the screwing-out is counter-clockwise and the screwing-in is clockwise.

The utility model also provides a more firm, the better collapsible tricycle of no chain of bearing nature, its characterized in that: a reinforcing rod is arranged between the driving wheel rod and the rear rod, and two ends of the reinforcing rod are respectively fixedly connected with the driving wheel rod and the rear rod.

It is known in the art for the drive wheel central transmission assembly to typically include a ratchet arrangement. The technical means is described in detail in the 'chainless bicycle transmission mechanism' (see pages 3-5 of the utility model patent specification with the application number of 201320792629.5), 'inflation-free maintenance chainless bicycle' (see pages 3-9 of the utility model patent specification with the application number of 201720393138.1), 'a chainless bicycle' (see pages 4-13 of the utility model patent specification with the application number of 202020087158.8), 'a rear drive chainless bicycle' (see pages 3-9 of the utility model patent specification with the application number of 202220154810.2), and is applied to the practical bicycle production practice, and the invention points and the invention concept are not repeated here. Therefore, the technical content of this section does not relate to whether the disclosure of this specification is sufficient or not, and whether the specification of article 26, article 3 of the patent law is met, that is, whether the technical solution described in this specification is clear and complete (hereinafter, 26 articles 3 of the problem).

The handlebar and the cushion of the bicycle can be adjusted in height, and are generally realized through mutual sleeving of the inner tube and the outer tube and the locking mechanism (such as a hoop). The height adjustment technique is well known in the art and will not be described herein. Therefore, this section of the technical disclosure does not relate to 26 of the 3-tier problems.

The phrase "the supporting rod of the seat cushion is fixedly connected to the cross member and is not movable relative to the cross member" means that the part of the supporting rod fixed to the cross member and the cross member cannot move relative to each other, but this does not mean that the height adjusting member (usually, the elevator tube fixedly connected directly to the seat cushion) of the supporting rod cannot move up and down.

The folding mechanism on the bicycle cross beam, i.e. the folding hinge (usually including a locking device), is well-established in the art and will not be described herein. Therefore, this section does not relate to the 26-item 3 problem.

After the bicycle is folded, the magnetic attraction device can be additionally arranged on the front wheel and the rear wheel, so that the front wheel and the rear wheel can be attracted together. The technical means is the mature prior art in the field, and is not the point and concept of the present invention, and will not be described herein again. Therefore, this section does not relate to the 26-item 3 problem.

The three wheels of the bicycle are fixedly connected with the front rod, the driving wheel rod and the rear rod, and are usually sleeved on bearings at the centers of the three wheels through sleeves at one ends of the front rod, the driving wheel rod and the rear rod, which are close to the ground, and then are fastened through nuts. The technical means is the mature prior art in the field, and is not the point and concept of the present invention, and will not be described herein again. Therefore, this section of the technical disclosure does not relate to 26 of the 3-tier problems.

The brake device of the bicycle can be selectively arranged on one or two of the three wheels, and the brake device can be selected to be a disc brake or wheel brake (namely V brake) device. This part of the technical content is well known in the art and will not be described herein. Therefore, this section of the technical disclosure does not relate to 26 of the 3-tier problems.

The cushion support rod and the driving wheel rod or the rear rod can be communicated with each other through the cross beam, so that the lifting component in the cushion support rod can be deeply inserted into the driving wheel rod or the rear rod. Of course, a design that does not involve such interpenetration may be selected. Therefore, the cushion support rod and the driving wheel rod or the rear rod may be in the same line or not. These designs are conventional in the art and will not be described further herein. Therefore, this section of the technical disclosure does not relate to 26 of the 3-tier problems.

The working mechanism of the speed regulating mechanism is that the length change of the pedal connecting rod is utilized to regulate the transmission ratio. The longer the pedal link, the easier but slower to ride, and conversely, the harder but faster to ride. When the screw or sleeve is actually turned, the pedal should generally be folded to a position parallel to the pedal link so that less space is occupied when screwing the screw or sleeve, preventing it from being obstructed by the steel bars on the drive wheel. When the length of the pedal connecting rod is adjusted to a proper position, the pedal returns to the state vertical to the pedal connecting rod, and at the moment, if the screw or the sleeve is screwed, the pedal is obstructed by the steel bar on the driving wheel, so that the length of the pedal connecting rod can be prevented from being changed.

The specific connection mode of the reinforcing rod, the driving wheel rod and the rear rod may be welding or other conventional connection modes, and is not described herein again. Therefore, this section does not relate to the 26-item 3 problem.

Because the utility model adopts the above technical scheme to can obtain following beneficial effect.

Firstly, the structure of the bicycle is simpler, the basic frame of the tricycle is built up by using fewer connecting rods, and the front wheel and the rear wheel are smaller, so that the whole body of the tricycle is lighter.

Second, the structure of bicycle is comparatively reasonable, rides passerby's hand, foot, buttock position design and makes to ride comparatively comfortable, can ride for a long time.

Thirdly, due to the simple structure, the production cost and the quality control of the bicycle are more controllable, and the economical efficiency is improved.

Fourthly, the folding mechanism is simple in arrangement, so that the folding is convenient and fast, and the structure after folding is regular.

Fifthly, the speed is regulated by the extension and retraction of the pedal connecting rod, and the speed regulating mechanism is simple and convenient to operate.

Drawings

The present invention will be described in further detail with reference to the accompanying drawings.

Figure 1 is the bicycle. Part 1 is a handle, part 2 is a crossbar, part 3 is a front bar yoke (for adjusting handle height), part 4 is a front bar, part 5 is a drive wheel, part 6 is a pedal link (also referred to as a "crank" in a conventional bicycle), part 7 is a front wheel, part 8 is a folding hinge, part 9 is a cushion yoke (for adjusting cushion height), part 10 is a cushion, part 11 is a reinforcement bar, part 12 is a rear bar, part 13 is a pedal, part 14 is a rear wheel, and part 15 is a drive wheel bar.

Fig. 2 is a state in which the bicycle is completely folded. The height of the handle and the seat cushion are both adjusted to be the lowest.

Fig. 3 shows the pedal link (now in the shortest state), part 1 is the drive wheel axle connection hole (for connecting the drive wheel central transmission assembly), part 2 is the sleeve, 3 is the screw thread, part 4 is the screw, and part 5 is the pedal connection hole.

Fig. 4 shows the state in which the screw of the pedal link is screwed out of the sleeve. At the moment, part of the screw rod is positioned in the sleeve so as to ensure the stability and firmness of the whole pedal connecting rod.

Detailed Description

As shown in fig. 1 and 2, the preferred embodiment of the present invention is: a chainless foldable tricycle comprising: front wheel, front rod, handle; a cross beam, a folding hinge; the driving wheel, a driving wheel center bearing, a driving wheel center transmission assembly, a pedal connecting rod and a driving wheel rod are arranged on the driving wheel; a cushion and a cushion support rod; a rear wheel, a rear rod; the method is characterized in that: the front wheel is a guide wheel, and a bearing of the front wheel is connected with one end of the front rod, which is close to the ground; the front wheel rotates around a bearing of the front wheel in a forward direction or a reverse direction; a sleeve hole at the front end of the cross beam is sleeved on the front rod to be in pivot connection; the upward end of the front rod is connected with the handle; the front rod is driven to rotate left and right by rotating the handle, so that the front wheel is driven to rotate left and right; the cross beam is parallel to the ground; the cross beam is provided with a folding hinge, and after the hinge is unfolded, the bicycle is folded at the hinge position by nearly 180 degrees; the driving wheels are positioned below the cross beam and between the front wheels and the rear wheels; the driving wheel is provided with two pedals and two pedal connecting rods, one end of each pedal connecting rod is connected with the corresponding pedal, and the other end of each pedal connecting rod is connected with the central transmission assembly of the driving wheel; when the pedal is stepped to ride forwards, the pedal sequentially drives the pedal connecting rod, the driving wheel central transmission assembly and the driving wheel to rotate; one end of the driving wheel rod close to the ground is connected with the driving wheel center bearing; the driving wheel rotates around the driving wheel central bearing in a forward direction or a reverse direction; the driving wheel rod is fixedly connected with the cross beam, and the driving wheel rod and the cross beam cannot move relatively, so that the driving wheel and the cross beam are always positioned on the same plane; the rear end of the cross beam is fixedly connected with the rear rod, and the cross beam and the rear rod cannot move relatively, so that the rear wheel and the cross beam are always in the same plane; the rear wheel is a supporting wheel, and a bearing of the rear wheel is connected with one end of the rear rod, which is close to the ground; the rear wheel rotates around a bearing of the rear wheel in a forward direction or a reverse direction; the diameter of the front wheel is the same as the diameter of the rear wheel; the geometrical centers of the front wheel, the rear wheel and the hinge form a triangle, the bottom edge of the triangle is parallel to the ground, and the left edge and the right edge of the triangle are basically equal, so that after the bicycle is folded by approaching 180 degrees through the hinge, the front wheel and the rear wheel are basically overlapped; the diameters of the front wheels and the rear wheels are both 50% of the diameter of the driving wheel; the geometric center of the cushion and the circle center of the driving wheel are connected into a straight line, and the included angle between the straight line and the vertical line of the ground is 30 degrees; the ground vertical projection of the geometric center of the cushion is positioned behind the ground vertical projection of the circle center of the driving wheel, and the distance between the two projections is 25 cm; when the bicycle is completely unfolded, the lowest points of the front wheel, the driving wheel and the rear wheel are basically on the same straight line; the supporting rod of the cushion is fixedly connected with the cross beam and cannot move relatively; a reinforcing rod is arranged between the driving wheel rod and the rear rod, and two ends of the reinforcing rod are respectively fixedly connected with the driving wheel rod and the rear rod. The ground vertical line is a straight line perpendicular to the ground at the contact point of the driving wheel and the ground.

As shown in fig. 3 and 4, another preferred embodiment of the present invention is: a speed-adjustable chainless foldable tricycle is characterized in that: one end of the pedal connecting rod is provided with a driving wheel shaft connecting hole (used for connecting a driving wheel central transmission assembly), and the other end of the pedal connecting rod is provided with a pedal connecting hole; the pedal connecting rod comprises a sleeve and a screw rod, and the diameter of the screw rod is basically the same as that of the inner cavity of the sleeve; the inner cavity of the sleeve and the screw rod are both provided with threads and correspond to each other; when the screw is screwed in the clockwise direction, the screw gradually enters the sleeve, so that the length of the pedal connecting rod is shortened; when the screw rod is screwed in the anticlockwise direction, the screw rod gradually extends out of the sleeve, so that the length of the pedal connecting rod is extended.

Other technical features of the present invention are described in the specification with clear text, and are easy to understand, so that they are not repeated separately by the specific embodiments or are shown one by the drawings. It should be noted that the present invention has a large number of technical contents belonging to the prior art in the field, and other patent specifications cited in the present specification are described in detail, so that the present specification does not repeat the description of the prior art means. The innovative part of the utility model is mainly embodied as follows: the bicycle is simple in overall structure, comfortable to ride, light and handy in whole bicycle, convenient to fold, free of speed regulation means in a chain coaxial transmission technical scheme, and controllable in production cost and quality.

Claims

1. A chainless foldable tricycle, comprising:

front wheel, front rod, handle;

a cross beam, a folding hinge;

the driving wheel, a driving wheel center bearing, a driving wheel center transmission assembly, a pedal connecting rod and a driving wheel rod are arranged on the driving wheel;

a cushion and a cushion support rod;

a rear wheel, a rear lever;

the method is characterized in that:

the front wheel is a guide wheel, and a bearing of the front wheel is connected with one end of the front rod, which is close to the ground; the front wheel rotates around a bearing of the front wheel in a forward direction or a reverse direction;

a sleeve hole at the front end of the cross beam is sleeved on the front rod to be in pivot connection; the upward end of the front rod is connected with the handle; the front rod is driven to rotate left and right by rotating the handle, so that the front wheel is driven to rotate left and right;

the cross beam is basically parallel to the ground; the cross beam is provided with a folding hinge, and after the hinge is unfolded, the bicycle is folded at the hinge position by nearly 180 degrees;

the driving wheel is positioned below the cross beam and between the front wheel and the rear wheel; the driving wheel is provided with two pedals and two pedal connecting rods, one end of each pedal connecting rod is connected with the corresponding pedal, and the other end of each pedal connecting rod is connected with the central transmission assembly of the driving wheel; when the pedal is stepped to ride forwards, the pedal sequentially drives the pedal connecting rod, the driving wheel central transmission assembly and the driving wheel to rotate;

one end of the driving wheel rod close to the ground is connected with the driving wheel center bearing; the driving wheel rotates around the driving wheel central bearing in a forward direction or a reverse direction;

the driving wheel rod is fixedly connected with the cross beam, and the driving wheel rod and the cross beam cannot move relatively, so that the driving wheel and the cross beam are always positioned on the same plane;

the rear end of the cross beam is fixedly connected with the rear rod, and the cross beam and the rear rod cannot move relatively, so that the rear wheel and the cross beam are always in the same plane;

the rear wheel is a supporting wheel, and a bearing of the rear wheel is connected with one end, close to the ground, of the rear rod; the rear wheel rotates around a bearing of the rear wheel in a forward direction or a reverse direction;

the diameter of the front wheel is substantially the same as the diameter of the rear wheel;

the geometrical centers of the front wheel, the rear wheel and the hinge form a triangle, the bottom edge of the triangle is basically parallel to the ground, and the left edge and the right edge of the triangle are basically equal, so that after the bicycle is folded by approaching 180 degrees through the hinge, the front wheel and the rear wheel are basically overlapped;

the diameters of the front wheels and the rear wheels are both larger than 25% of the diameter of the driving wheel and are both smaller than 75% of the diameter of the driving wheel;

the geometric center of the cushion and the circle center of the driving wheel are connected into a straight line, and the included angle between the straight line and the vertical line of the ground is more than 5 degrees and less than 60 degrees; the ground vertical projection of the geometric center of the cushion is positioned behind the ground vertical projection of the circle center of the driving wheel, and the distance between the two projections is more than 5 cm and less than 60 cm;

when the bicycle is completely unfolded, the lowest points of the front wheel, the driving wheel and the rear wheel are in the same straight line;

the supporting rod of the cushion is fixedly connected with the cross beam and cannot move relatively.

2. A cycle as claimed in claim 1, wherein:

the pedal connecting rod comprises a sleeve and a screw rod, and the diameter of the screw rod is basically the same as that of the inner cavity of the sleeve;

the inner cavity of the sleeve and the screw rod are both provided with threads and correspond to each other;

when the screw rod or the sleeve is screwed in the clockwise or anticlockwise direction, the screw rod gradually enters the sleeve, so that the length of the pedal connecting rod is shortened;

when the screw or the sleeve is screwed in the opposite direction, the screw gradually protrudes out of the sleeve, so that the length of the pedal link is extended.

3. A cycle as claimed in claim 1 or 2, wherein: a reinforcing rod is arranged between the driving wheel rod and the rear rod, and two ends of the reinforcing rod are respectively fixedly connected with the driving wheel rod and the rear rod.