Double-lever prying labor-saving rear single wheel driving type tricycle and method

Abstract

The invention discloses a double-lever prying labor-saving rear single wheel driving type tricycle and a method, and relates to the technical field of manpower tricycles. A rear single-wheel drive type tricycle comprises a frame, a front fork, a hopper, a front wheel, rear wheels and a transmission system. The transmission system comprises two sets of double-lever prying transmission mechanisms; the double-lever prying transmission mechanism comprises a base plate, a crank, a lever A, a rocker A, a lever B and a rocker B, the base plates of the two sets of double-lever prying transmission mechanisms are fixedly connected to the two outer sides of the U-shaped framework respectively. And the two sets of double-lever prying transmission mechanisms share one rotating shaft. The tricycle power transmission method is based on a rear single-wheel drive type tricycle. The two sets of double-lever prying transmission mechanisms are symmetrically arranged on the two sides of the U-shaped framework and share the driving rotating shaft to directly drive the single rear wheel, the structure is compact, rigidity is good, and power transmission is direct and efficient. The electric tricycle is particularly suitable for a single-rear-wheel drive tricycle needing a certain loading capacity.

Description

Technical Field

[0001] The present invention relates to the technical field of human-powered tricycles, in particular to a double-lever prying labor-saving rear single-wheel drive tricycle and a method thereof. Background Art

[0002] The transmission structure of existing human-powered tricycles mostly uses a sprocket and chain transmission pair. In other words, the human foot moves in circles on two pedals, which rotates the driving sprocket, which in turn drives the driven sprocket through the chain, thereby driving the tricycle forward. Although existing human-powered tricycles can achieve labor-saving effects by shifting gears (essentially changing the gear ratio between the chainring and flywheel), this labor-saving effect is limited by various factors and has an upper limit (the gear ratio limit is approximately 0.43, meaning that for every pedaling rotation, the rear wheel only rotates 0.43 times).

[0003] The limiting factors are mainly reflected in the following aspects: Limitation of the lever arm ratio: The radius of the circle drawn with the center point of the flywheel as the center is equivalent to the power arm, and the radius of the drive wheel (usually the rear wheel) is equivalent to the resistance arm. Due to the limitations of the flywheel size and installation position, as well as the drive wheel size and vehicle structure, the length of the power arm will not be greater than the resistance arm, and the effort-saving effect is relatively limited.

[0004] Limitations of mechanical design: A flywheel that is too large requires a longer rear derailleur and frame space, which can easily exceed the conventional design range; a chainring with too small a number of teeth can lead to poor engagement between the chain and the chainring, which can easily cause the chain to come off or wear out; under extreme gear ratios, the chain's inclination angle is too large (for example, a small chainring + a large flywheel), resulting in increased friction loss and reduced transmission efficiency.

[0005] Ergonomic limitations: If the gear ratio is too small (for example, <0.43), the rider will only move forward a short distance after pedaling one circle. The rider will need to pedal at an extremely high frequency to maintain a certain speed, which is far beyond the human body's comfort range and can easily lead to muscle fatigue or knee injuries, which is counterproductive.

[0006] In summary, it is very necessary to design a new transmission structure for human-powered tricycles so that they can achieve better labor-saving effects and have good riding comfort. Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a double-lever prying and labor-saving rear single-wheel drive tricycle and method. It improves the transmission mechanism of the traditional human-powered tricycle and adopts a double-lever prying transmission mechanism to replace the sprocket and chain transmission mechanism of the traditional human-powered tricycle, which can achieve better labor-saving effect and at the same time has good riding comfort.

[0008] The technical solution of the present invention is: a double-lever prying and labor-saving rear single-wheel drive tricycle, comprising a frame, a front fork, a bucket, a front wheel, a rear wheel and a transmission system; A vertically inclined main pole is provided in the middle of the frame, a seat is provided at the upper end of the main pole, a front fork frame is provided at the front end of the frame, a front fork mounting hole is provided at the front end of the front fork frame, and a U-shaped frame is provided at the rear end of the frame, the closed end of the U-shaped frame is directly or indirectly fixedly connected to the main pole, and the open end of the U-shaped frame extends toward the rear end of the frame; the front fork is rotatably mounted in the front fork mounting hole of the frame; the middle of the outer wall of the rear end of the truck bed is fixedly connected to the front fork; the two front wheels are rotatably mounted on both sides of the truck bed via the front wheel axles; the rear wheels are rotatably mounted on the inner side of the U-shaped frame and rotate under the drive of the transmission system; The transmission system includes two sets of double-lever prying transmission mechanisms; the double-lever prying transmission mechanism includes a base plate, a crank, lever A, rocker A, lever B and rocker B; the front end of the crank is rotatably mounted on the base plate via a rotating shaft, and the rear end of the crank is hinged to the front end of lever A; lever A is provided with a hinge point A between the front and rear ends, and the rear end of lever A is hinged to the front end of lever B; the front end of rocker A is hinged to the base plate, and the rear end of rocker A is hinged to the hinge point A of lever A; lever B is provided with a hinge point B between the front and rear ends, and the rear end of lever B is a free end; the front end of rocker B is hinged to the base plate, and the rear end of rocker B is hinged to the hinge point B of lever B; when the crank rotates in a circle, lever A swings up and down around hinge point A, and lever B swings up and down around hinge point B; The base plates of the two sets of double-lever prying transmission mechanisms are respectively fixedly connected to the two outer sides of the U-shaped frame; the two sets of double-lever prying transmission mechanisms share a rotating shaft; the front ends of the cranks of the two sets of double-lever prying transmission mechanisms are respectively connected to the two ends of the same rotating shaft.

[0009] A further technical solution of the present invention is that the rear wheel is directly or indirectly fixedly mounted on the middle of the rotating shaft, and the axis of the rear wheel coincides with the axis of the rotating shaft.

[0010] A further technical solution of the present invention is: the transmission system also includes two sets of pedal assemblies; the pedal assembly includes a pedal shaft and a pedal fixedly mounted on the pedal shaft, one end of the pedal shaft extends outside the pedal to form a mounting end; the two sets of pedal assemblies are respectively rotatably mounted on the free ends of levers B of the two sets of double-lever prying transmission mechanisms through the mounting ends of the pedal shaft, and are arranged perpendicular to the lever B.

[0011] A further technical solution of the present invention is: when the free end of lever B moves from the uppermost end to the lowermost end and then to the uppermost end of the swing stroke, a movement cycle of the double-lever prying transmission mechanism is completed. In one movement cycle, the crank rotates 360°.

[0012] A further technical solution of the present invention is: the rod section of lever A between the front end and the hinge point A is defined as the first resistance arm, the rod section of lever A between the rear end and the hinge point A is defined as the first power arm, the rod section of lever B between the front end and the hinge point B is defined as the second resistance arm, and the rod section of lever B between the rear end and the hinge point B is defined as the second power arm; the length ratio of the first resistance arm to the first power arm is 1:x, and the value range of x is 1.5 to 2.5; the length ratio of the second resistance arm to the second power arm is 1:y, and the value range of y is 2 to 10.

[0013] A further technical solution of the present invention is: the value of x is 2, and the value of y is 4.

[0014] The technical solution of the present invention is: a tricycle power transmission method based on the above-mentioned rear single-wheel drive tricycle; Before executing the method, define the following concepts: Ⅰ. The two sets of double-lever prying transmission mechanisms in the rear single-wheel drive tricycle are named as the left mechanism and the right mechanism respectively; II. In the lever-prying transmission mechanism, the free end of lever B swings from the uppermost end to the lowermost end and then from the lowermost end to the uppermost end, completing a motion cycle. A motion cycle consists of a first half-cycle and a second half-cycle. The first half-cycle is completed when the free end of lever B swings from the uppermost end to the lowermost end, and the second half-cycle is completed when the free end of lever B swings from the lowermost end to the uppermost end. Here’s how: A. Left down, right up: When the free end of lever B of the left mechanism swings downward, the left mechanism is in the first half of the motion cycle. Actively exerting force on the pedal corresponding to the left mechanism drives the free end of lever B of the right mechanism to swing upward passively. At this time, the right mechanism is in the second half of the motion cycle. B. Right down, left up: When the free end of lever B of the right mechanism swings downward, the right mechanism is in the first half of the motion cycle. Actively exerting force on the pedal corresponding to the right mechanism drives the free end of lever B of the left mechanism to swing upward passively. At this time, the left mechanism is in the second half of the motion cycle. C. Repeat this process by alternately pedaling on the two pedals, driving the free ends of the levers B of the two sets of double-lever prying transmission mechanisms to swing up and down alternately, thereby driving the rotating shaft to rotate continuously in the same direction, and then driving the rear wheel to rotate continuously in the same direction, thus realizing the riding of the tricycle; Steps A and B in the method are performed simultaneously.

[0015] A further technical solution of the present invention is: in step A of the above method, the power transmission path includes three consecutive paths: I. Left Mechanism: Stepping on the pedal corresponding to the left mechanism drives lever B in the left mechanism to rotate about hinge point B, causing the free end of lever B to descend and the front end of lever B to rise. Lever B pulls lever A to rotate about hinge point A, causing the front end of lever A to descend and the rear end of lever A to rise. Rockers A and B swing adaptively, and the crank rotates 180° clockwise. II. Rotating shaft: The rotating shaft shared by both mechanisms is driven by the crank in the left mechanism and rotates 180°; III. Right-side mechanism: The rotation of the shaft drives the crank in the right-side mechanism to rotate 180°. The crank pulls lever A to rotate about hinge point A, causing the front end of lever A to descend and the rear end of lever A to ascend. Lever A pulls lever B to rotate hinge point B, causing the free end of lever B to ascend and the front end of lever B to descend. At this point, the movement process of "left down and right up" is realized; In sub-step B of the above method, the power transmission path includes three consecutive paths; I. Right Mechanism: Stepping on the pedal corresponding to the right mechanism drives lever B in the right mechanism to rotate about hinge point B, causing the free end of lever B to descend and the front end of lever B to rise. Lever B pulls lever A to rotate about hinge point A, causing the front end of lever A to descend and the rear end of lever A to rise. Rockers A and B swing adaptively, and the crank rotates 180° clockwise. II. Rotating shaft: The rotating shaft shared by both mechanisms is driven by the crank in the right mechanism and rotates 180°; III. Left-side mechanism: The rotation of the shaft drives the crank in the left-side mechanism to rotate 180°. The crank pulls lever A to rotate about hinge point A, causing the front end of lever A to descend and the rear end of lever A to ascend. Lever A pulls lever B to rotate hinge point B, causing the free end of lever B to ascend and the front end of lever B to descend. At this point, the movement process of "lower right and upper left" is realized.

[0016] Compared with the prior art, the present invention has the following advantages: 1. Significant two-stage effort-saving effect: By designing the lever arm ratios of levers A and B, a two-stage force amplification is achieved. Taking the example of lever A with a 1:2 lever arm ratio and lever B with a 1:4 lever arm ratio in Example 1 as an example, the total effort-saving ratio reaches 1:8, far exceeding the gear ratio limit of a traditional chain drive (0.43). This makes driving a rear-wheel drive tricycle even more effortless, especially when starting or climbing a slope.

[0017] 2. High Riding Comfort: Two dual-lever prying drive mechanisms are mounted on either side of the U-shaped frame. Riders drive the tricycle by alternately pedaling downwards on two pedals. Compared to the circular pedaling of traditional tricycles, this linear up-and-down motion better aligns with the body's natural force generation, reducing the risk of muscle fatigue and knee injuries, and improving comfort during extended rides.

[0018] 3. Stable structure and efficient drive: Two dual-lever prying drive mechanisms are mounted on either side of the U-shaped frame, sharing a common drive shaft to directly drive the single rear wheel. The compact structure offers excellent rigidity and direct and efficient power transmission. This makes it particularly suitable for rear-wheel drive tricycles requiring a certain load capacity, such as freight tricycles.

[0019] The present invention is further described below with reference to the figures and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A perspective view of the present invention; Figure 2 is a three-dimensional diagram of the transmission system of the present invention at a first viewing angle; Figure 3 is a three-dimensional diagram of the transmission system of the present invention at a second viewing angle; Figure 4 This is the simplified motion trajectory diagram of the double-lever prying transmission mechanism structure; Figure 5 It is a state diagram of the present invention at the beginning of the first half motion cycle; Figure 6 This is the first state diagram of the present invention in the first half of the motion cycle; Figure 7 This is the second state diagram of the present invention in the first half of the motion cycle; Figure 8 It is a state diagram of the present invention at the beginning of the second half motion cycle; Figure 9 This is the first state diagram of the present invention in the second half of the motion cycle; Figure 10 This is the second state diagram of the present invention in the second half of the motion cycle; Figure 11 2 is a diagram showing the positional relationship between the transmission system and the frame of the present invention.

[0021] Special Notes: Figure 1 Each line segment in the figure represents a rod. All rods in one color represent a motion state of the transmission mechanism. Green arcs or circles represent the motion trajectories of different rods. Multiple colors on a line indicate that the rod is in this position in multiple states of the transmission mechanism.

[0022] Legend: base plate 1; crank 2; rotating shaft 21; lever A3; hinge point A31; rocker A4; lever B5; hinge point B51; rocker B6; frame 71; main rod 711; front fork skeleton 712; U-shaped skeleton 713; front fork 72; bucket 73; front wheel 74; rear wheel 75; pedal 76. DETAILED DESCRIPTION Example 1

[0023] like Figure 1-11 As shown, the double-lever prying and labor-saving rear single-wheel drive tricycle includes a frame 71, a front fork 72, a bucket 73, a front wheel 74, a rear wheel 75 and a transmission system.

[0024] The frame 71 is an integral rigid component. A vertically inclined main rod 711 is provided in the middle of the frame 71, a seat is provided at the upper end of the main rod 711, a front fork frame 712 is provided at the front end of the frame, a front fork mounting hole is provided at the front end of the front fork frame 712, and a U-shaped frame 713 is provided at the rear end of the frame 71. The closed end of the U-shaped frame 713 is directly or indirectly fixedly connected to the main rod 711, and the open end of the U-shaped frame 713 extends toward the rear end of the frame 71. The front fork 72 is rotatably mounted in the front fork mounting hole of the frame 71. The middle of the rear end outer wall of the bucket 73 is fixedly connected to the front fork 72. The two front wheels 74 are rotatably mounted on both sides of the bucket 73 via the front wheel axles 741. The rear wheel 75 is rotatably mounted on the inner side of the U-shaped frame 713 and rotates under the drive of the transmission system.

[0025] The transmission system includes two dual-lever prying transmission mechanisms. These mechanisms comprise a base plate 1, a crank 2, a lever A3, a rocker A4, a lever B5, and a rocker B6. The front end of crank 2 is rotatably mounted on base plate 1 via a rotating shaft 21 (the front end of crank 2 is fixedly connected to rotating shaft 21). The rear end of crank 2 is hinged to the front end of lever A3. Lever A3 has a hinge point A31 between its front and rear ends, and its rear end is hinged to the front end of lever B5. The front end of rocker A4 is hinged to base plate 1, and its rear end is hinged to hinge point A31 of lever A3. Lever B5 has a hinge point B51 between its front and rear ends, with its rear end being free. The front end of rocker B6 is hinged to base plate 1, and its rear end is hinged to hinge point B of lever B5. As crank 2 rotates in a circular motion, lever A3 swings up and down around hinge point A31, and lever B5 swings up and down around hinge point B51.

[0026] The base plates 1 of the two dual-lever prying transmission mechanisms are fixedly connected to the outer sides of the U-shaped frame 713. The two dual-lever prying transmission mechanisms share a common rotating shaft 21. This sharing is defined as the front ends of the cranks 2 of the two dual-lever prying transmission mechanisms being connected to the ends of the same rotating shaft 21. The rear wheel 75 is directly or indirectly fixedly mounted in the middle of the rotating shaft 21, rotating synchronously with the rotating shaft 21, with the axis of the rear wheel 75 coinciding with the axis of the rotating shaft 21.

[0027] Preferably, the transmission system further includes two pedal assemblies. The pedal assemblies include a pedal shaft and a pedal 76 fixedly mounted on the shaft. One end of the pedal shaft extends outside of the pedal 76 to form a mounting end. The two pedal assemblies are rotatably mounted to the free ends of levers B5 of the two dual-lever prying transmission mechanisms via the mounting ends of the pedal shafts, and are arranged perpendicular to the levers B5.

[0028] Preferably, when the free end of the lever B5 moves from the uppermost end to the lowermost end and then to the uppermost end of the swing stroke, the crank 2 rotates 360°.

[0029] Preferably, the section of lever A3 between the front end and hinge point A31 is defined as the first resistance arm, the section of lever A3 between the rear end and hinge point A31 is defined as the first power arm, the section of lever B5 between the front end and hinge point B51 is defined as the second resistance arm, and the section of lever B5 between the rear end and hinge point B51 is defined as the second power arm. The length ratio of the first resistance arm to the first power arm is 1:x, where x is 2; the length ratio of the second resistance arm to the second power arm is 1:y, where y is 4.

[0030] The working principle of the double-lever prying transmission mechanism in the present invention is as follows: The free end of lever B5 swings from the uppermost end (upper extreme point) to the lowermost end (lower extreme point) and then from the lowermost end to the uppermost end, completing one movement cycle of the double-lever prying transmission mechanism. A movement cycle consists of a first half movement cycle and a second half movement cycle. The first half movement cycle is completed when the free end of lever B5 swings from the uppermost end to the lowermost end, and the second half movement cycle is completed when the free end of lever B5 swings from the lowermost end to the uppermost end.

[0031] During the first half of the motion cycle, an external driving force (i.e., downward pressure) is applied to the free end of lever B5. Under this external driving force, lever B5 rotates about hinge point B51, causing the free end of lever B5 to descend and the front end of lever B5 to ascend. Lever B5 pulls lever A3 to rotate about hinge point A31, causing the front end of lever A3 to descend and the rear end of lever A3 to ascend. Rockers A4 and B6 oscillate adaptively, and crank 2 rotates approximately 180° clockwise (the shaft 21 fixed to the front end of crank 2 also rotates synchronously by the same angle).

[0032] During the second half of the motion cycle, an external driving force (i.e., a clockwise torque) must be applied to shaft 21. Under this external driving force, crank 2 rotates approximately 180° clockwise (shaft 21, which is fixedly connected to the front end of crank 2, also rotates synchronously by the same angle). Crank 2 pulls lever A3 around hinge point A31, causing the front end of lever A3 to descend and the rear end of lever A3 to ascend. Lever A3 pulls lever B5 around hinge point B51, causing the free end of lever B5 to ascend and the front end of lever B5 to descend.

[0033] The labor-saving effect of the double-lever prying transmission mechanism of the present invention is described as follows: During the first half of the motion cycle, levers B5 and A3 in the dual-lever prying transmission mechanism can achieve first- and second-level effort-saving effects, respectively. As described above, the rod sections of lever B5 on either side of hinge point B51 are the second power arm (the rod section between the rear end of lever B5 and hinge point B51) and the second resistance arm (the rod section between the front end of lever B5 and hinge point B51). The rod sections of lever A3 on either side of hinge point A31 are the first power arm (the rod section between the rear end of lever A3 and hinge point A31) and the first resistance arm (the rod section between the front end of lever A3 and hinge point A31). During the first half of the motion cycle, the external driving force is applied to the second power arm (the free end of lever B5). Because the second power arm is longer than the second resistance arm, the first-level effort-saving effect is achieved through the principle of leverage. Because the second resistance arm is hinged to the first power arm and the first power arm is longer than the first resistance arm, the second-level effort-saving effect is achieved through the principle of leverage, thereby achieving a two-stage multiplied effort-saving effect.

[0034] The working principle of the present invention is briefly described as follows: A tricycle power transmission method is based on the above-mentioned rear single-wheel drive tricycle.

[0035] Before executing the method, define the following concepts: Ⅰ. The two sets of double-lever prying transmission mechanisms in the rear single-wheel drive tricycle are named as the left mechanism and the right mechanism respectively; Ⅱ. In the lever prying transmission mechanism, the free end of lever B5 swings from the uppermost end to the lowermost end and then from the lowermost end to the uppermost end, completing a motion cycle. A motion cycle includes a first half motion cycle and a second half motion cycle. The free end of lever B5 swings from the uppermost end to the lowermost end to complete the first half motion cycle, and the free end of lever B5 swings from the lowermost end to the uppermost end to complete the second half motion cycle.

[0036] Here’s how: A. Left down and right up: When the free end of the lever B5 of the left mechanism swings downward, the left mechanism is in the first half of the motion cycle. Active force is exerted on the pedal 76 corresponding to the left mechanism, thereby driving the free end of the lever B5 of the right mechanism to passively swing upward. At this time, the right mechanism is in the second half of the motion cycle.

[0037] B. Lower right and upper left: When the free end of the lever B5 of the right mechanism swings downward, the right mechanism is in the first half of the motion cycle. Active force is exerted on the pedal 76 corresponding to the right mechanism, thereby driving the free end of the lever B5 of the left mechanism to passively swing upward. At this time, the left mechanism is in the second half of the motion cycle.

[0038] C. Repeat this process by alternately pedaling on the two pedals 76, thereby driving the free ends of the levers B5 of the two sets of double-lever prying transmission mechanisms to swing up and down alternately, thereby driving the rotating shaft 21 to rotate continuously in the same direction, and then driving the rear wheel 75 to rotate continuously in the same direction, thereby realizing the riding of the tricycle.

[0039] Steps A and B in the method are performed simultaneously.

[0040] In step A of the above method, the power transmission path includes three consecutive paths: I. Left Mechanism: Stepping on pedal 76 corresponding to the left mechanism drives lever B5 in the left mechanism to rotate about hinge point B51, causing the free end of lever B5 to descend and the front end of lever B5 to ascend. Lever B5 pulls lever A3 to rotate about hinge point A31, causing the front end of lever A31 to descend and the rear end of lever A31 to ascend. Rockers A4 and B6 swing adaptively, causing crank 2 to rotate 180° clockwise. Ⅱ shaft: The shaft 21 shared by the two mechanisms is driven by the crank 2 in the left mechanism and rotates 180 °; III. Right-side mechanism: The rotation of shaft 21 drives crank 2 in the right-side mechanism to rotate 180°. Crank 2 pulls lever A3 to rotate around hinge point A31, causing the front end of lever A3 to descend and the rear end of lever A3 to ascend. Lever A3 pulls lever B5 to rotate around hinge point B51, causing the free end of lever B5 to ascend and the front end of lever B5 to descend.

[0041] At this point, the movement process of "left down and right up" is realized.

[0042] In sub-step B of the above method, the power transmission path includes three consecutive paths; I. Right Mechanism: Stepping on pedal 76 corresponding to the right mechanism drives lever B5 in the right mechanism to rotate about hinge point B51, causing the free end of lever B5 to descend and the front end of lever B5 to ascend. Lever B5 pulls lever A3 to rotate about hinge point A31, causing the front end of lever A3 to descend and the rear end of lever A3 to ascend. Rockers A4 and B6 swing adaptively, causing crank 2 to rotate 180° clockwise. Ⅱ shaft: the two sets of mechanisms share the shaft 21 is driven by the crank 2 in the right mechanism and rotates 180 °; III. Left-side mechanism: The rotation of shaft 21 drives crank 2 in the left-side mechanism to rotate 180°. Crank 2 pulls lever A3 to rotate around hinge point A31, causing the front end of lever A3 to descend and the rear end of lever A3 to ascend. Lever A3 pulls lever B5 to rotate around hinge point B51, causing the free end of lever B5 to ascend and the front end of lever B51 to descend.

[0043] At this point, the movement process of "lower right and upper left" is realized.

Claims

1. The double-lever prying and labor-saving rear single-wheel drive tricycle is characterized by: Including frame, front fork, bed, front wheel, rear wheel and transmission system; A vertically inclined main pole is provided in the middle of the frame, a seat is provided at the upper end of the main pole, a front fork frame is provided at the front end of the frame, a front fork mounting hole is provided at the front end of the front fork frame, and a U-shaped frame is provided at the rear end of the frame, the closed end of the U-shaped frame is directly or indirectly fixedly connected to the main pole, and the open end of the U-shaped frame extends toward the rear end of the frame; the front fork is rotatably mounted in the front fork mounting hole of the frame; the middle of the outer wall of the rear end of the truck bed is fixedly connected to the front fork; the two front wheels are rotatably mounted on both sides of the truck bed via the front wheel axles; the rear wheels are rotatably mounted on the inner side of the U-shaped frame and rotate under the drive of the transmission system; Its characteristics are as follows: the transmission system includes two sets of double-lever prying transmission mechanisms; the double-lever prying transmission mechanisms include a base plate, a crank, a lever A, a rocker A, a lever B and a rocker B; the front end of the crank is rotatably mounted on the base plate via a rotating shaft, and the rear end of the crank is hinged to the front end of the lever A; a hinge point A is provided between the front and rear ends of lever A, and the rear end of lever A is hinged to the front end of lever B; the front end of the rocker A is hinged to the base plate, and the rear end of the rocker A is hinged to the hinge point A of lever A; the rear end of the lever B is hinged to the hinge point B of lever A; the rear end of the lever B is a free end; the front end of the rocker B is hinged to the base plate, and the rear end of the rocker B is hinged to the hinge point B of lever B; when the crank rotates in a circle, the lever A swings up and down around the hinge point A, and the lever B swings up and down around the hinge point B; The base plates of the two sets of double-lever prying transmission mechanisms are respectively fixedly connected to the two outer sides of the U-shaped frame; the two sets of double-lever prying transmission mechanisms share a rotating shaft; the front ends of the cranks of the two sets of double-lever prying transmission mechanisms are respectively connected to the two ends of the same rotating shaft.

2. The rear single-wheel drive tricycle according to claim 1, characterized in that: The rear wheel is directly or indirectly fixedly mounted on the middle of the rotating shaft, and the axis center line of the rear wheel coincides with the axis center line of the rotating shaft.

3. The rear single-wheel drive tricycle according to claim 2, characterized in that: The transmission system also includes two sets of pedal assemblies; the pedal assembly includes a pedal shaft and a pedal fixedly mounted on the pedal shaft, one end of the pedal shaft extends outside the pedal to form a mounting end; The two sets of pedal assemblies are respectively rotatably mounted on the free ends of the levers B of the two sets of double-lever prying transmission mechanisms through the mounting ends of the pedal shafts, and are arranged perpendicular to the levers B.

4. The rear single-wheel drive tricycle according to claim 3, wherein: When the free end of lever B moves from the uppermost end to the lowermost end and then to the uppermost end of the swing stroke, one movement cycle of the double-lever prying transmission mechanism is completed. In one movement cycle, the crank rotates 360°.

5. The rear single-wheel drive tricycle according to claim 4, characterized in that: The rod section of lever A between the front end and the hinge point A is defined as the first resistance arm, the rod section of lever A between the rear end and the hinge point A is defined as the first power arm, the rod section of lever B between the front end and the hinge point B is defined as the second resistance arm, and the rod section of lever B between the rear end and the hinge point B is defined as the second power arm; the length ratio of the first resistance arm to the first power arm is 1:x, and the value range of x is 1.5 to 2.5; the length ratio of the second resistance arm to the second power arm is 1:y, and the value range of y is 2 to 10.

6. The rear single-wheel drive tricycle according to claim 5, characterized in that: The value of x is 2 and the value of y is 4.

7. A power transmission method for a tricycle, based on the rear single-wheel drive tricycle according to any one of claims 1 to 6; Before executing the method, define the following concepts: Ⅰ. The two sets of double-lever prying transmission mechanisms in the rear single-wheel drive tricycle are named as the left mechanism and the right mechanism respectively; II. In the lever-prying transmission mechanism, the free end of lever B swings from the uppermost end to the lowermost end and then from the lowermost end to the uppermost end, completing a motion cycle. A motion cycle consists of a first half-cycle and a second half-cycle. The first half-cycle is completed when the free end of lever B swings from the uppermost end to the lowermost end, and the second half-cycle is completed when the free end of lever B swings from the lowermost end to the uppermost end. Its characteristics are: Here’s how: A. Left down, right up: When the free end of lever B of the left mechanism swings downward, the left mechanism is in the first half of the motion cycle. Actively exerting force on the pedal corresponding to the left mechanism drives the free end of lever B of the right mechanism to swing upward passively. At this time, the right mechanism is in the second half of the motion cycle. B. Right down, left up: When the free end of lever B of the right mechanism swings downward, the right mechanism is in the first half of the motion cycle. Actively exerting force on the pedal corresponding to the right mechanism drives the free end of lever B of the left mechanism to swing upward passively. At this time, the left mechanism is in the second half of the motion cycle. C. Repeat this process by alternately pedaling on the two pedals, driving the free ends of the levers B of the two sets of double-lever prying transmission mechanisms to swing up and down alternately, thereby driving the rotating shaft to rotate continuously in the same direction, and then driving the rear wheel to rotate continuously in the same direction, thus realizing the riding of the tricycle; Steps A and B in the method are performed simultaneously.

8. The tricycle power transmission method according to claim 7, wherein: In step A of the method, the power transmission path includes three paths that are connected in sequence: I. Left Mechanism: Stepping on the pedal corresponding to the left mechanism drives lever B in the left mechanism to rotate about hinge point B, causing the free end of lever B to descend and the front end of lever B to rise. Lever B pulls lever A to rotate about hinge point A, causing the front end of lever A to descend and the rear end of lever A to rise. Rockers A and B swing adaptively, and the crank rotates 180° clockwise. II. Rotating shaft: The rotating shaft shared by both mechanisms is driven by the crank in the left mechanism and rotates 180°; III. Right-side mechanism: The rotation of the shaft drives the crank in the right-side mechanism to rotate 180°. The crank pulls lever A to rotate about hinge point A, causing the front end of lever A to descend and the rear end of lever A to ascend. Lever A pulls lever B to rotate hinge point B, causing the free end of lever B to ascend and the front end of lever B to descend. At this point, the movement process of "left down and right up" is realized; In sub-step B of the above method, the power transmission path includes three consecutive paths; I. Right Mechanism: Stepping on the pedal corresponding to the right mechanism drives lever B in the right mechanism to rotate about hinge point B, causing the free end of lever B to descend and the front end of lever B to rise. Lever B pulls lever A to rotate about hinge point A, causing the front end of lever A to descend and the rear end of lever A to rise. Rockers A and B swing adaptively, and the crank rotates 180° clockwise. II. Rotating shaft: The rotating shaft shared by both mechanisms is driven by the crank in the right mechanism and rotates 180°; III. Left-side mechanism: The rotation of the shaft drives the crank in the left-side mechanism to rotate 180°. The crank pulls lever A to rotate about hinge point A, causing the front end of lever A to descend and the rear end of lever A to ascend. Lever A pulls lever B to rotate hinge point B, causing the free end of lever B to ascend and the front end of lever B to descend. At this point, the movement process of "lower right and upper left" is realized.

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