Guided booster crank device

Abstract

The utility model provides a guide type force increasing crank device has a crank body, and the both ends of crank body are respectively accommodated with a first transmission and a second transmission, and are connected on the first transmission and the second transmission with a transmission element around, and the second transmission has a clamping column which protrudes from the side of the crank body, and a force increasing arm has a head end, and a clamping hole which can be correspondingly sleeved on the clamping column is arranged on the head end, and a force increasing fixing bolt is locked on the second transmission through the clamping column and the outside of the force increasing arm which is relatively far away from the crank body, and the structure strength can be greatly improved to prolong the service life, and the force increasing arm can be easily replaced and maintained, and the labor can be saved, and the guide effect of the force direction forward can be produced to improve the work efficiency.

Description

Technical Field

[0001] This utility model relates to the transmission structure of bicycles, and in particular to a guided power-increasing crank device. Background Technology

[0002] The existing bicycle drive structure mainly has a crank of fixed length, which connects the pedal to the center of a drive sprocket (i.e., the drive shaft). By stepping on the pedal, the crank can drive the drive sprocket to make a 360° circular motion around its center with the length of the crank as the radius. This, in turn, drives the chain connected to the drive sprocket, which in turn drives the bicycle wheels to rotate, thus achieving the purpose of propelling the bicycle forward.

[0003] However, existing crank structures cannot extend their cranks to increase the lever arm length when the pedal is turned to the position where force is required, thus failing to achieve the effect of saving effort. Furthermore, when the conventional crank structure is turned to the highest position (0°) and the lowest position (180°), the direction of force applied by the pedal will form a straight line perpendicular to the crank and drive shaft. At this time, the effective lever arm length is zero (commonly known as the top and bottom dead points), and the optimal force application efficiency cannot be maintained. In addition, although there are many crank structures on the market that claim to have increased force efficiency, they not only have the disadvantage of overly complex structural composition, but also generally suffer from insufficient structural strength, making them easy to damage, and are difficult to disassemble and repair.

[0004] Therefore, how to improve the above-mentioned problems is the primary issue that this utility model aims to solve. Utility Model Content

[0005] The main purpose of this utility model is to provide a guided force-increasing crank device, which has the advantages of simple structure, easy disassembly and maintenance, and can effectively improve its overall structural strength, thereby improving its transmission stability and extending its service life. It can also achieve the effect of saving effort by increasing its lever arm, and can generate a guiding effect that makes the force applied forward, thereby improving work efficiency. It can also ensure that there are no dead points at the top or bottom, thus achieving the best force application efficiency.

[0006] To achieve the aforementioned objectives, this utility model provides a guided force-increasing crank device, comprising:

[0007] A crank body has a first end and a second end opposite to the first end. The crank body can perform a circular motion with the first end as the axis. A first drive wheel is provided inside the first end, and a second drive wheel is provided inside the second end. The first drive wheel has a connecting part that protrudes outward from one side of the crank body and can be used to engage with a positioning ring. The second drive wheel has a locking post that protrudes outward from the other side of the crank body.

[0008] A transmission element, in a ring shape, is connected to the first transmission wheel and the second transmission wheel, so that when the crank body performs the circular motion, the transmission element can be driven by the first transmission wheel to drive the second transmission wheel to rotate; and

[0009] A lever arm includes a first arm and a second arm. The first arm has a head end and a tail end opposite to the head end. The head end has a locking hole that extends through two opposite sides of the head end. The first arm is fitted onto the locking post of the second drive wheel through the locking hole. A lever-enhancing fixing bolt passes through the locking post on the outer side of the lever arm that is relatively away from the crank body and locks it onto the second drive wheel. The second arm is fixed to the tail end at one end. The second arm and the first arm are arranged side by side. The other end of the second arm has a pedal assembly part that is offset from the center of the locking hole. The pedal assembly part extends into an enlarged hole in the first arm.

[0010] Preferably, the crank body consists of an outer shell and a cover plate that can be correspondingly fitted onto one side of the outer shell. A cylindrical column extends from the interior of the outer shell corresponding to the first end, and a first connecting hole is formed on the side wall of the outer shell corresponding to the second end. The cylindrical column extends outward and protrudes from the cover plate, and a toothed hole communicating with the outside is formed inside the cylindrical column. The cover plate has a second connecting hole on the side wall corresponding to the first end, which is opposite to the cylindrical column and allows the cylindrical column to pass through. The connecting part of the first drive wheel is sleeved on the cylindrical column, so that the connecting part can pass outward from the second connecting hole and out of the crank body. Several engaging grooves are provided around the outer circumference of the connecting part.

[0011] Furthermore, the cover plate has a cylindrical protrusion extending towards the outer casing on the side wall corresponding to the second end. The protrusion is configured opposite to the first connection hole of the outer casing, and a bearing is provided in the first connection hole. The second drive wheel is disposed inside the second end of the crank body and is located between the first connection hole and the protrusion. The second drive wheel has a recess on its end face facing the cover plate that allows the protrusion to be inserted into it. The second drive wheel has a locking post protruding from its end that is relatively far from the recess. The locking post is disposed with its bottom facing the bearing. The outer circumferential surface of the locking post has several grooves, and the inner edge of the locking hole has protruding teeth that can be engaged with each groove.

[0012] Preferably, the positioning ring has a first internal tooth portion and a second internal tooth portion sequentially formed along its inner edge. The first internal tooth portion is used to engage with the engaging groove on the outer peripheral surface of the connecting portion, while the second internal tooth portion engages with the groove on the outer peripheral surface of a locking ring. An anti-slip pad and a pressing member are sequentially sleeved on the end of the locking ring that is relatively far away from the positioning ring. The anti-slip pad is located between the pressing member and the locking ring.

[0013] Preferably, the positioning ring has a first internal tooth and a second internal tooth sequentially formed along its inner edge. The first internal tooth is used to engage with a locking groove on the outer peripheral surface of the connecting part, while the second internal tooth engages with a groove on the outer periphery of a fitting ring. A third internal tooth is formed on the inner edge of the fitting ring. A connecting cylinder that can be pressed into the inner edge of a set of seats on a central shaft is sleeved on a central shaft. A second locking groove that can engage with the third internal tooth is formed at the end of the connecting cylinder.

[0014] Preferably, the first drive wheel has a first ring tooth portion, the second drive wheel has a second ring tooth portion, and the transmission element is composed of a timing belt or a chain that can mesh with the first ring tooth portion and the second ring tooth portion.

[0015] Preferably, the inside of the crank body forms an annular track that can accommodate the first drive wheel, the second drive wheel and the transmission element, and an elongated slot is formed at the position enclosed by the annular track, penetrating the two opposite side walls of the crank body.

[0016] Preferably, the inner diameter of the enlarged hole is larger than the outer diameter of the pedal assembly, so that a clearance space is formed between the enlarged hole and the pedal assembly.

[0017] Preferably, the second arm has a plurality of protrusions on its end face facing the first arm, and the second arm abuts against the first arm with each of the protrusions.

[0018] Preferably, the first end of the crank body is used to connect with one side of a sprocket connecting plate, and three positioning protrusions are provided on the end face of the first end facing the sprocket connecting plate, and a locking hole is provided on the end face of the sprocket connecting plate used to connect with the crank body, so that the positioning protrusions can be inserted into each other.

[0019] The above-mentioned objectives and advantages of this utility model can be readily understood from the following detailed description and accompanying drawings of the selected embodiments. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the composition of the crank device of this utility model.

[0022] Figure 2 This is a schematic diagram of the structure of the lever arm of this utility model.

[0023] Figure 3 This is a schematic diagram of the structure of the crank device of this utility model when connected with the sprocket connecting plate and the central shaft.

[0024] Figure 4 This is a schematic diagram of the assembly of the crank body and the sprocket connecting plate of this utility model.

[0025] Figure 5 This is a perspective view of the crank assembly of this utility model.

[0026] Figure 6 This is a schematic cross-sectional view of the crank assembly of this utility model.

[0027] Figure 7 This is a schematic diagram of the crank device of this utility model in use.

[0028] Figure 8 This is a schematic diagram of the structure of the crank device of this utility model when applied to the assembly of a toothless press-fit bottom shaft.

[0029] Figure 9 This is a partial cross-sectional view of the assembled part in Figure 8.

[0030] The crank body 11; first end 111; second end 112; outer shell 12; annular track 121; cover plate 13; protrusion 131; cylindrical column 14; toothed hole 141; first connecting hole 15; bearing 151; second connecting hole 16; long slot hole 18; positioning protrusion 19; first transmission wheel 21; first ring tooth portion 22; connecting portion 23; engaging groove 231; second transmission wheel 31; second ring tooth portion 32; recess 33; engaging post 34; groove 341; transmission element 41; force-multiplying arm 51; first support arm 52; head end 521; tail end 522. Bolt 523; Second support arm 53; Protrusion 531; Locking hole 54; Protruding tooth 541; Force-increasing fixing bolt 55; Pedal assembly part 56; Pedal 57; Enlarged hole 58; Positioning ring 61; First internal tooth part 611; Second internal tooth part 612; Locking ring 62; Groove 621; Threaded section 622; Anti-slip pad 63; Abutting part 64; Fitting ring 65; Groove 651; Third internal tooth part 652; Connecting cylinder 66; Second locking groove 661; Central shaft 71, 71B; Crank fixing bolt 72; Assembly seat 73; Sprocket connecting piece 81; Locking hole 82. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0032] Please see Figures 1 to 7 The image shown is a guided force-increasing crank device provided by this utility model, which mainly consists of a crank body 11, a first transmission wheel 21, a second transmission wheel 31, a transmission element 41, and a force-increasing arm 51, wherein:

[0033] The crank body 11 has a first end 111 and a second end 112 opposite to the first end 111. The crank body 11 can perform a circular motion with the center point of the first end 111 as the axis. In this embodiment, the crank body 11 is composed of an outer shell 12 and a cover plate 13 that can be correspondingly covered on one side of the outer shell 12. A cylindrical column 14 extends from the inner side of the outer shell 12 corresponding to the first end 111. A first connecting hole 15 is formed on the side wall of the outer shell 12 corresponding to the second end 112, and a bearing 151 is provided in the first connecting hole 15. The cylindrical column 14 extends outward and protrudes from the cover plate 13. A toothed hole 141 communicating with the outside is formed inside the cylindrical column 14. A second connecting hole 16 is formed on the side wall of the cover plate 13 corresponding to the first end 111, which is opposite to the cylindrical column 14 and allows the cylindrical column 14 to pass through. A cylindrical protrusion 131 protrudes towards the outer shell 12 on the side wall of the cover plate 13 corresponding to the second end 112. The protrusion 131 is opposite to the first connecting hole 15 of the outer shell 12.

[0034] The first drive wheel 21 is sleeved on the cylindrical column 14 and located inside the first end 111 of the crank body 11. The first drive wheel 21 has a first ring tooth 22 formed at one end facing the outer shell 12, and a hollow cylindrical connecting part 23 is formed at the other end of the first drive wheel 21 away from the first ring tooth 22, which can be correspondingly sleeved on the outer circumferential surface of the cylindrical column 14. The connecting part 23 can also pass out from the second connecting hole 16 to one side of the crank body 11 and can be used to connect with a positioning ring 61. Several engaging grooves 231 are provided around the outer circumferential surface of the connecting part 23.

[0035] The second drive wheel 31 is disposed inside the second end 112 of the crank body 11 and between the first connection hole 15 and the protrusion 131. One end of the second drive wheel 31 is expanded to form a second ring tooth portion 32, and a recess 33 is formed on the end face of the second drive wheel 31 facing the cover plate 13, which allows the protrusion 131 to be inserted into it. At the other end of the second drive wheel 31 away from the second ring tooth portion 32, a locking post 34 is formed that can extend outward from the first connection hole 15. The locking post 34 is disposed with its bottom facing the bearing 151 so that it can be supported by the bearing 151, so that the second drive wheel 31 is rotatably disposed inside the second end 112 of the crank body 11, and the smooth rotation of the second drive wheel 31 can be ensured. Several grooves 341 are provided on the outer peripheral surface of the locking post 34 exposed in the first connection hole 15.

[0036] The transmission element 41 is ring-shaped and connected to the first ring tooth portion 22 of the first transmission wheel 21 and the second ring tooth portion 32 of the second transmission wheel 31. An annular track 121 is formed inside the outer casing 12 of the crank body 11 to accommodate the first transmission wheel 21, the second transmission wheel 31, and the transmission element 41. The transmission element 41 is composed of a timing belt or chain that meshes with the first ring tooth portion 22 and the second ring tooth portion 32. The tooth ratio of the first ring tooth portion 22 to the second ring tooth portion 32 is 1:1. This ensures that when the crank body 11 is in circular motion, while the first transmission wheel 21 is stationary, the transmission element 41 can be subjected to [unspecified influence] during its rotation around the first transmission wheel 21. The first ring tooth 22 drives the second transmission wheel 31 and its locking pin 34 to rotate. A long slot 18 is provided in the position enclosed by the annular track 121 of the crank body 11, penetrating the two opposite side walls of the crank body 11. The long slot 18 can provide additional space for setting up, for example, a speed sensor, a cadence sensor or a power sensor (not shown in the figure). The present invention uses a transmission element 41 made of timing belt or chain, which not only has the advantages of being easy to obtain and easy to maintain and replace, but also has the advantages of being more suitable for high torque use environments due to the elasticity of the transmission element 41 made of timing belt or chain. This can effectively improve the problem of easy deformation, damage or breakage when using traditional rigid shaft transmission.

[0037] Referring to Figures 1, 2, 3, and 7, the lever arm 51 consists of a first arm 52 and a second arm 53. The first arm 52 and the second arm 53 are respectively arc-shaped. The first arm 52 has a head end 521 and a tail end 522 opposite to the head end 521. The head end 521 has a locking hole 54 that extends through both opposite sides of the head end 521. The inner edge of the locking hole 54 has protruding teeth 541 that can engage with the corresponding slots 341. The first arm 52 is fitted onto the locking post 34 of the second transmission wheel 31 through the locking hole 54. A force-enhancing fixing bolt 55 passes through the locking post 34 and is locked to the second drive wheel 31 via the outer side of the force-enhancing arm 51, which is relatively away from the crank body 11. This allows the first support arm 52 to be driven by the locking post 34 of the second drive wheel 31 to change its yaw angle. Since the force-enhancing fixing bolt 55 passes through the locking post 34 and is locked to the second drive wheel 31 via the outer side of the force-enhancing arm 51, which is relatively away from the crank body 11, it is not obstructed by the crank body 11 and has a larger operating space. This allows the use of force-enhancing fixing bolts with a larger outer diameter (e.g., an outer diameter of at least...). The bolts used are 8mm for fixing, which can significantly improve the structural strength and bonding strength. The second support arm 53 is fixed to the tail end 522 of the first support arm 52 by a bolt 523 at one end. The second support arm 53 and the first support arm 52 are arranged side by side in a folded manner, and the second support arm 53 is located between the crank body 11 and the first support arm 52. At the other end of the second support arm 53, there is a pedal assembly part 56 that is offset from the center of the locking hole 54. The pedal assembly part 56 is used to assemble a pedal 57, and the pedal assembly part 56 extends into the first support arm 52. In the enlarged hole 58, the inner diameter of the enlarged hole 58 is larger than the outer diameter of the pedal assembly 56, so as to form a clearance space between the enlarged hole 58 and the pedal assembly 56, which is required for the second support arm 53 to move its pedal assembly 56 downward when it is bent and deformed by force. In addition, several protrusions 531 are provided on the end face of the second support arm 53 facing the first support arm 52, and the second support arm 53 abuts against the first support arm 52 with each of the protrusions 531. The arrangement of each protrusion 531 ensures that the second support arm 53 does not fit against the first support arm 52 over a large area, which is conducive to stress transmission. Furthermore, by employing a folded and extended lever-like method to increase the torque length of the first arm 52 and the second arm 53, the force-applying arm formed by the connection of the first arm 52 and the second arm 53 can be larger than the force-applying arm of a traditional pedal crank structure consisting of only a single crank. According to the torque principle (M=F*d, F: force, d: lever arm), under the same torque (Moment), the force required to be applied by the guide-type force-enhancing crank device provided by this utility model is smaller, thereby achieving a force-saving effect.

[0038] Furthermore, please refer to the accompanying materials. Figure 3 , Figure 6 As shown, the positioning ring 61 has a first internal tooth portion 611 and a second internal tooth portion 612 sequentially formed along its inner edge. The first internal tooth portion 611 is used to engage with the engaging groove 231 on the outer peripheral surface of the connecting portion 23, while the second internal tooth portion 612 engages with the groove 621 on the outer peripheral surface of the locking ring 62. An anti-slip washer 63 and a pressing member 64 are sequentially sleeved on the end of the locking ring 62 that is relatively away from the positioning ring 61. The anti-slip washer 63 is located between the pressing member 64 and the locking ring 62. A threaded section 622 is provided on the outer peripheral surface of the end of the locking ring 62 that is relatively away from the positioning ring 61, so that the crank body 11 is positioned in the... The toothed hole 141 of the first end 111 is engaged with the end of a central shaft 71, and the crank body 11 and the central shaft 71 are locked together by a crank fixing bolt 72. The connecting part 23 of the first drive wheel 21 engages with the positioning ring 61, and the threaded section 622 of the locking ring 62 is screwed onto the end of a set of seats 73 on the frame assembly where the central shaft 71 is located. This allows the crank assembly and the frame to form a locking assembly. The anti-slip pad 63 and the abutment member 64 generate a relative clamping action, which can reliably position and ensure the strength of the connection, thereby improving the stability of the transmission and ensuring the power amplification effect and the safety of use.

[0039] Furthermore, referring to Figures 3, 4, and 5, the first end 111 of the crank body 11 is connected to one side of a sprocket connecting piece 81, thereby enabling the crank body 11 to drive the sprocket assembly (not shown) connected to the other side of the sprocket connecting piece 81 to rotate. Three positioning protrusions 19 are further provided on the end face of the first end 111 facing the sprocket connecting piece 81, and engaging holes 82 are provided on the end face of the sprocket connecting piece 81 where it connects to the crank body 11, allowing the positioning protrusions 19 to be inserted into each other. This ensures that when the crank body 11 performs circular motion, the positioning protrusions 19 can form a three-point connection with the sprocket connecting piece 81, further guaranteeing the reliability and efficiency of the transmission of the crank body 11 driving the sprocket connecting piece 81, and effectively reducing force loss.

[0040] In practical use, as shown in Figure 7, when the user applies force to the pedal 57 attached to the second support arm 53 with the ball of their foot, the extended force arm 51 can drive the crank body 11 to perform circular motion more effortlessly. During the circular motion of the crank body 11, the transmission element 41 is driven by the first ring tooth 22 while rotating around the first transmission wheel 21, which in turn drives the second transmission wheel 31 and its locking pin 34 to rotate. At this time, the first support arm 52 connected to the locking pin 34 can swing in the opposite direction of the crank body 11 as the locking pin 34 rotates, so that the extended force arm 51 can maintain a constant angle with the ground. This effectively prevents safety problems caused by the additional length of the extended force arm 51 and ensures that the crank body 11 can perform circular motion smoothly.

[0041] Furthermore, by assembling the pedal 57 in the pedal assembly portion 56 of the second support arm 53, which is offset from the locking hole 54, the movement trajectory of the center point of the pedal 57 can form a circular motion that deviates from the movement trajectory of the locking hole 54 and conforms to ergonomics. Therefore, it can generate a guiding effect that makes the force direction forward, thereby improving work efficiency. At the same time, it can also ensure that there are no dead points at the top or bottom, thus ensuring that it has the best force application efficiency.

[0042] As can be seen from the above description, the guide-type power-enhancing crank device provided by this utility model not only has the advantages of simple structure and easy disassembly and maintenance, but also provides a structural strength like an integral unit through its combination method, which can effectively improve its overall structural strength, thereby improving its transmission stability and extending its service life. At the same time, it can achieve the effect of saving effort by increasing its lever arm, and can generate a guiding effect that makes the force direction forward, thereby improving work efficiency. It can also ensure that there are no dead points at the top and bottom, thus achieving the best force application efficiency. Therefore, it is highly practical and progressive.

[0043] As shown in Figures 8 and 9, the guided crankshaft device provided by this utility model can also be further connected to the toothless press-fit bottom shaft 71B by using the positioning ring 61 in conjunction with other components. The positioning ring 61 also has a first internal tooth 611 and a second internal tooth 612 sequentially formed along its inner edge. The first internal tooth 611 engages with the engagement groove 231 on the outer peripheral surface of the connecting part 23, while the second internal tooth 612 engages with the groove 651 on the outer periphery of a fitting ring 65. A third internal tooth 652 is formed on the inner edge of the fitting ring 65. A connecting sleeve 66, which can be press-fitted into the inner edge of the mounting seat (not shown) of the frame, is sleeved onto the bottom shaft 71B. At both ends of the connecting sleeve 66, a third internal tooth 652 is formed that can engage with the third internal tooth 652 on the opposite side. The two locking grooves 661 allow the crank body 11 to engage with the end of the central shaft 71B through the toothed hole 141 at the first end 111. After the crank body 11 and the central shaft 71B are locked together by a crank fixing bolt 72, the connecting part 23 of the first transmission wheel 21 engages with the positioning ring 61. The groove 651 of the fitting ring 65 and the third internal tooth 652 respectively lock the second internal tooth 612 of the positioning ring 61 and the second locking groove 661 of the connecting cylinder 66. This allows the guide crank device provided by this utility model to be applied to the toothless press-fit central shaft 71B assembly, further ensuring the synchronous movement of the crank devices assembled at both ends of the central shaft 71B. It also has the functions of reliable positioning and ensuring its engagement strength, as well as improving its stability during transmission, thus ensuring the power-enhancing effect and safety of use.

[0044] However, the above embodiments are only used to illustrate the present utility model and are not intended to limit the present utility model. Any substitution of equivalent elements should still fall within the scope of the present utility model.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A guided force-increasing crank device, characterized in that, It contains: A crank body has a first end and a second end opposite to the first end. The crank body can perform a circular motion with the first end as the axis. A first drive wheel is provided inside the first end, and a second drive wheel is provided inside the second end. The first drive wheel has a connecting part that protrudes outward from one side of the crank body and can be used to engage with a positioning ring. The second drive wheel has a locking post that protrudes outward from the other side of the crank body. A transmission element, in a ring shape, is connected to the first transmission wheel and the second transmission wheel, so that when the crank body performs the circular motion, the transmission element can be driven by the first transmission wheel to drive the second transmission wheel to rotate; and A lever arm includes a first arm and a second arm. The first arm has a head end and a tail end opposite to the head end. The head end has a locking hole that extends through two opposite sides of the head end. The first arm is fitted onto the locking post of the second drive wheel through the locking hole. A lever-enhancing fixing bolt passes through the locking post on the outer side of the lever arm that is relatively away from the crank body and locks it onto the second drive wheel. The second arm is fixed to the tail end at one end. The second arm and the first arm are arranged side by side. The other end of the second arm has a pedal assembly part that is offset from the center of the locking hole. The pedal assembly part extends into an enlarged hole in the first arm.

2. The guided force-increasing crank device according to claim 1, characterized in that: The crank body consists of an outer shell and a cover plate that can be fitted onto one side of the outer shell. A cylindrical column extends from the inner side of the outer shell corresponding to the first end, and a first connecting hole is formed on the side wall of the outer shell corresponding to the second end. The cylindrical column extends outward and protrudes from the cover plate, and a toothed hole communicating with the outside is formed inside the cylindrical column. The cover plate has a second connecting hole on the side wall corresponding to the first end, which is opposite to the cylindrical column and allows the cylindrical column to pass through. The connecting part of the first drive wheel is sleeved on the cylindrical column, so that the connecting part can pass outward from the second connecting hole and out of the crank body. Several engaging grooves are provided around the outer circumference of the connecting part.

3. The guided force-increasing crank device according to claim 2, characterized in that: The cover plate has a cylindrical protrusion on its side wall corresponding to the second end, which protrudes towards the outer shell. The protrusion is positioned opposite to the first connection hole of the outer shell, and a bearing is provided in the first connection hole. The second drive wheel is disposed inside the second end of the crank body and is located between the first connection hole and the protrusion. The second drive wheel has a recess on its end face facing the cover plate, which allows the protrusion to be inserted into it. The second drive wheel has a locking post protruding from its end opposite to the recess, and the locking post is positioned with its bottom facing the bearing. The outer circumferential surface of the locking post has several grooves, and the inner edge of the locking hole has protruding teeth that can engage with each groove.

4. The guided force-increasing crank device according to claim 2, characterized in that: The positioning ring has a first internal tooth and a second internal tooth formed sequentially along its inner edge. The first internal tooth is used to engage with the engagement groove on the outer peripheral surface of the connecting part, while the second internal tooth engages with the groove on the outer peripheral surface of a locking ring. An anti-slip pad and a pressing member are sequentially sleeved on the end of the locking ring that is relatively away from the positioning ring. The anti-slip pad is located between the pressing member and the locking ring. A threaded section is provided on the outer peripheral surface of the end of the locking ring that is relatively away from the positioning ring, which can be screwed onto a set of seats of the frame.

5. The guided force-increasing crank device according to claim 2, characterized in that: The positioning ring has a first internal tooth and a second internal tooth sequentially formed along its inner edge. The first internal tooth is used to engage with the engagement groove on the outer peripheral surface of the connecting part, while the second internal tooth engages with the groove on the outer peripheral surface of a fitting ring. A third internal tooth is formed on the inner edge of the fitting ring. A connecting cylinder that can be pressed into the inner edge of a set of seats on a central shaft is sleeved on a central shaft. A second engagement groove that can engage with the third internal tooth is formed at the end of the connecting cylinder.

6. The guided force-increasing crank device according to claim 1, characterized in that: The first drive wheel has a first ring tooth portion, the second drive wheel has a second ring tooth portion, and the transmission element is composed of a timing belt or a chain that can mesh with the first ring tooth portion and the second ring tooth portion.

7. The guided force-increasing crank device according to claim 1, characterized in that: The crank body has an annular track inside that can accommodate the first drive wheel, the second drive wheel and the transmission element, and a long slot is formed at the position enclosed by the annular track, penetrating the two opposite side walls of the crank body.

8. The guided force-increasing crank device according to claim 1, characterized in that: The inner diameter of the enlarged hole is larger than the outer diameter of the pedal assembly, so that there is a clearance space between the enlarged hole and the pedal assembly.

9. The guided force-increasing crank device according to claim 1, characterized in that: The second arm has several protrusions on its end face facing the first arm, and the second arm abuts against the first arm with each of the protrusions.

10. The guided force-increasing crank device according to claim 1, characterized in that: The first end of the crank body is used to connect with one side of a sprocket connecting plate, and three positioning protrusions are provided on the end face of the first end facing the sprocket connecting plate, and a locking hole is provided on the end face of the sprocket connecting plate used to connect with the crank body, so that the positioning protrusions can be inserted into each other.

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