SK50192015A3 - Bike driven by oscillating cranks movements - Google Patents

Abstract

The crank mechanism for driving the bicycle has a shaft (2) mounted in the bicycle frame (1) on which the drive sprocket (3) is mounted centrally. Cranks (4) are mounted on both ends of the shaft (2) via the freewheels (5). The freewheels (5) ensure the transmission of the torque from the cranks (4) to the shaft (2) by turning the cranks (4) in the direction of the cyclist's force acting on the pedal (6) and freely rotating the cranks (4) against the shaft (2). Since the rotation of the keys (4) is not bound to one another, they can also be used in a counter-swinging motion, particularly in a region close to the position where the cyclist's force on the pedal (6) is perpendicular to the cranks (4).

Description

Technical field.

The proposed solution relates to the construction of a crank mechanism used mainly for driving a bicycle. A new solution will make the use of the cyclist's force to drive a bicycle more efficient.

BACKGROUND OF THE INVENTION.

In commonly used bicycles, the pedals are mounted on two cranks rigidly connected via a shaft and rotated 180 degrees to each other. The drive sprocket is fixed to one of the keys centrally with the shaft. By force on the pedal, both cranks, the shaft and the drive sprocket rotate simultaneously about the axes of the shaft. Most of the cyclist's force on the pedal is achieved by lowering the legs and gravitationally acting on the weight of the cyclist. The resulting torque due to the cyclist's force on the pedal varies two times during the crank speed from near zero to the maximum. The instantaneous torque value is the product of the magnitude of the force and the magnitude of the force arm. The force arm is the distance of the force vector from the shaft axis. At the moment when the direction of the force applied to the pedal passes the axis of rotation of the keys, the moment of force is zero because the arm of the force is zero. The maximum arm of the force is at the moment when the direction of the force applied to the pedal is perpendicular to the crank and is then equal to the length of the crank. The length of the keys is limited by the physiological dimensions of the cyclist.

As a result of the anatomical structure of the human body, the seated cyclist is able to exert the greatest force on the pedal as soon as his leg in the knee is approaching an extended position. However, in conventional crank mechanisms, the seated cyclist has a leg extended in the knee at a crank position close to the zero arm position. The disadvantages of the current solution of the crank mechanism of the bicycle drive are the large variations in the magnitude of the available torque and the existence of the so-called dead crank angle, i.e. the crank position in which the arm is at least zero, which is particularly negative when uphill. A disadvantage is also that the maximum force action of the seated cyclist is in the crank position when the arm of the force is small and hence the available torque is small.

SUMMARY OF THE INVENTION.

These drawbacks are overcome by the proposed solution, which is based on the use of an alternating rocking movement of the keys to create a rotational movement of the drive sprocket for driving the bicycle. In the frame of the bicycle there is a rotatably mounted shaft on which the drive sprocket is mounted centrically. At both ends of the shaft, the cranks are supported by freewheels which allow the keys to rotate independently of one another and ensure the transmission of torque from the keys to the shaft and the drive sprocket in only one direction of rotation of the keys and free rotation of the keys. Since the pivoting of the keys is not tied, the cranks can be used not only by classical rotation, but also by reciprocally oscillating about the shaft axis in any range of rotation, namely in the region of the maximum arm, ie in the area close to the the pedal is perpendicular to the crank. By propelling the bicycle to each other in the opposite direction of swinging the keys in the region of the maximum arm of the force, the negative effect of the blind key angle is eliminated, allowing a faster transmission to be used than with a conventional drive. This advantage of the proposed solution is particularly evident when the load is heavier than, for example, when driving uphill. The pedals must be connected to the cyclist's shoes to reverse the keys. In order to facilitate the coordination of the cyclist's movements in the construction of the bicycle with exclusively swinging movement of the keys, it is possible to couple the pedals by, for example, a pulley guide. Clamping the keys should ensure that when one handle is rotated by the cyclist, the other handle turns in the opposite direction. In such a coupling of the keys and the drive of the bicycle only by swinging the keys, it is possible to use longer cranks which increases the torque on the crank and also it is not necessary to connect the pedals with the cyclist spikes. In the design of the bicycle drive with exclusively swinging movement of the keys, the maximum force action of the seated cyclist in the area of the keys position where there is a large arm of force and the available torque is significantly greater than in a conventional solution.

BRIEF DESCRIPTION OF THE DRAWINGS.

Picture no. 1 shows a mechanism for rotating or oscillating movement of the keys and with cranks mounted on the shaft ends on unidirectional bearings.

Picture no. 2 shows a mechanism for pivoting or rocking movement of the keys and with cranks mounted over the idle bushes in the shaft cavity.

Picture no. 3 shows the coupling of the keys in the drive with only the pivoting movement of the keys.

DETAILED DESCRIPTION OF THE INVENTION.

A first exemplary embodiment is a design of a bicycle key mounting according to FIG. 1, which allows the drive to be rotated by 180 ° in a conventional manner, but also to be actuated by an alternating rocking movement of the keys in the region of the maximum torque exerted by the cyclist on the pedal. In the frame of the bicycle 1 there are screwed bowls 11 with built-in rolling bearings 12. In the bearings 12 there is a shaft 2 with a square shoulder for connection with the drive sprocket 3, which has a square shoulder of the shaft 2 corresponding to a square hole. On the right side of the shaft 2 is formed an external right-hand thread on which the nut 13 is screwed. On the outer cylindrical surface of the nut 13 is pressed the inner ring of the freewheel 5, on the outer ring the pressed crank 4 with the pedal 6. On the left end of the shaft 2 is formed an external left-hand thread on which the nut 14 is screwed. On the outer cylindrical surface of the nut 14 is pressed the inner ring of the freewheel 5 on which outer ring is pressed the crank 4 with pedal 6. This solution uses single-direction rolling bearings, which are bearings with integrated freewheel. The orientation of the freewheels 5 is such that they transmit the torque generated by the cyclist's force from the cranks 4 to the shaft 2 and allow the cranks 4 to rotate freely in the opposite direction.

The second exemplary embodiment is a design solution of the bicycle key arrangement according to figure 2, which enables the drive also by classical rotation of the keys rotated by 180 ° relative to each other, but also by the alternating swinging movement of the keys in the area of maximum torque exerted by the cyclist. In the frame of the bicycle 1 there are screwed bowls 11 with built-in rolling bearings 12. In the bearings 12 a shaft 2 is mounted, on which the drive chain wheel 3 is fastened by screws 15. In the shaft cavity 2 there are bearings 16 and 17 at both ends and freewheels The axial position of the auxiliary shafts 7 is secured by circlips 18 and 19. Cranks 4 are fastened to the square ends of the auxiliary shafts 7 by bolts 20. The orientation of the idle bushes 5 is such that they transmit the torque from the cyclist's force from the cranks 4 to the shaft 2 and allow the keys to rotate freely in the opposite direction.

A third embodiment is the construction of the bicycle according to figure 3, allowing the drive only by alternating rocking movement of the keys in the region of the maximum torque exerted by the cyclist on the pedal. This solution complements the first and second exemplary embodiments by interlocking the movements of the keys 4. The pulley 21 is rotatably mounted on the bicycle frame 1, in the groove of which the rod 20 is guided, the ends of which are fixed to the cranks 4 near the pedals 6.

When the cyclist exerts a force on the pedal 6 on one of the cranks 4, the other crank 4 rotates in the opposite direction due to the coupling 20 by the puller 20. The upper dead center of the key 4 is limited by the stop 22 and thus the swing angle of the keys (4) is also limited.

Claims (3)

Claims: 1- Crank mechanism for driving a bicycle, characterized in that a shaft (2) is rotatably mounted in the bicycle frame (1) on which the drive sprocket (3) is centrally fixed and both cranks (4) are connected to the shaft (2) via freewheels (5) that transfer torque from the keys (4) to the shaft (2) when turning the keys (4) in the direction of the cyclist's force on the pedal (6) and freely rotating the keys (4) against the shaft (2) in the opposite direction. 2- The crank mechanism for driving a bicycle according to claim 1, characterized in that the auxiliary shafts (7) are fixedly connected to the cranks (4) via freewheels (5) in the shaft cavity (2). A crank mechanism for driving a bicycle according to item 1 or 2, allowing only the pivoting movement of the keys, characterized in that on both cranks (4) the ends of the tie rod (20) which are guided over the roller (21) are fixed near the pedals. to move the crank (4) in the opposite direction of the cyclist's force on the pedal (6) when the crank (4) is rotated in the direction of the cyclist's force acting on the pedal (6).