KR200198827Y1 - Ellipse type chain sprocket for bicycle pedal - Google Patents

Abstract

The present invention relates to the oval shape of the pedal chain chain that is connected to the crank arm of the bicycle and transmits the rotational force to the rear wheel by the chain. In particular, a circular sprocket when the driving source is a human force such as a bicycle chain sprocket. The power consumption ratio resulting from the difference between the rotational force of the sprocket and the elliptical sprocket has emerged as a more urgent matter and is designed to improve driving ability by improving it.

Description

Bicycle Pedal Side Oval Chain Sprocket

The present invention relates to a bicycle pedal side elliptical chain sprocket. When driving on a flat surface, the demand for the force that is concentrated in the surroundings of the sprocket is gentler than that of a circular one, and the force applied to the pedal is relatively even. The present invention relates to an elliptical sprocket capable of improving driving ability by proportioning the long axis and the short axis formed in the elliptical sprocket.

Conventional circular sprockets require a concentrated force between about 5-20 ° when the pedal runs through the periphery on the vertical axis when driving on a flat surface, and thus returns to a position that can be applied to the pedal during driving on high ground, i. It was not effective because of the crowds of.

An object of the present invention is to solve the above problems, and in particular to the elliptical chain sprocket of the pedal side of the bicycle that can improve the driving ability by the proportion of the long axis and the short axis of the ellipse formed by the sprocket in the elliptical shape will be.

1 is a graph showing the force at each rotation angle of a circle and an ellipse.

2 is an explanatory diagram of the effective radius of an ellipse.

3 is an explanatory diagram for showing the pedal position causing the minimum rotational power.

4 is an explanatory diagram for showing the position of the pedal causing the maximum rotational power according to the leg length.

5 is an explanatory diagram for showing the position of the pedal causing the maximum rotational power according to the height of the saddle.

6 is an explanatory diagram for showing a pedal position causing a maximum rotational power.

* Explanation of symbols for main parts of the drawings

SP1: Pedal side chain sprocket SP2: Rear wheel side chain sprocket

Pa: Pedal Sa: Saddle

P1: front wheel P2: rear wheel

Q: Rp: Effective radius of the ellipse

Ph: angle of crank arm

Table 1: The rotational force according to the angle of the crank arm at Q = 1.

Table 2: Rotational force with angle of crank arm at Q = 1.2.

Table 3 shows the rotational force according to the angle of the crank arm at Q = 1.5.

Table 4: Rotational force by angle of crank arm at Q = 2.

The design of the invention is oval instead of the general circular chain sprocket as shown in FIGS. 4, 5 and 6. Assuming that the force of the leg, which is the driving source of the sprocket, is constantly applied vertically downward, the rotational force at each position is as follows based on the rotational force at the position advanced 90 ° from the vertical. 0 ° when the clamp arms are perpendicular to each other and are perpendicular to each other)

Torque K = constant, L = length of crank arm, F = vertical force

Rp = effective radius of the ellipse

(Distance between the center of the crank arm at the angle φ and the ellipsoid)

If the rotational force when φ = 90 ° is set to 1 At this time, the effective radius Rp = 1.

The effective radius Rp of the ellipse

,

here,

If we set K, L, F = 1, the torque is Becomes

Tables 1 to 4 show the rotational force according to the angle of the crank arm , Ph = crank arm angle RP = effective radius, TORQUE = rotational force. Therefore, Table 1 is circular, and Tables 2, 3 and 4 are elliptical. As can be seen here, when the constant force F acts in the vertical direction, the effective rotational force at each rotation angle of the crank arm is much more effective when elliptical than circular. It can be seen that.

FIG. 1 shows the relationship between the angle of the crank arm and the rotational force. In addition, the relationship between the effective radius of the ellipse of the above equation and the angle φ is as follows.

The trajectory of the ellipse in FIG. 2 is the trajectory of the point P when the circumferences of the circle 1 and the circle 2 contact each other and the center of the circle 2 rotates on the circumference of the circle 3, and the center of the ellipse is the circle 3 and the circle 1. The points F1 and F2 meet on the horizontal line of. So in Figure 2

M = R sin θ + C sin θ = (R + C) sin θ

K = R sin θ- C sin θ = (R-C) cos θ

Here, θ = rotational movement angle of circle 2 (angle converted into circular sprocket)

Rp = M ² + K ²

The effective radius Rp is as described above

Becomes

here,

On the other hand, in the present invention, as shown in FIG. 2, the force F of the leg does not always act vertically downward depending on the riding position of the occupant, so the angle between the chain sprocket and the crank arm needs to be changed appropriately. That is, the angle of the crank arm to which the maximum or rotational force is applied depends on the leg length of the occupant and the height of the saddle. The amount of force acting depends on the angle between the lower and upper knees of the leg when applying force to the pedal, and since the lower and upper knees are almost horizontal, it can exert a lot of force. By mounting in a position that can accept the force, the effect of the elliptic sprocket can be doubled.

In Figure 3, a is the position of a suitable crank arm when the leg is long or the saddle is raised. B is the normal case, and c is the case where the leg is short or the saddle is lower. In the case of short or lower saddle, the value of? Is about 75 °, the case of normal is about 80 °, and when the leg is long or the saddle is raised, the value of? Is about 87 °.

4 and 5 are for explaining the position of the crank arm in which the force of the leg causes the maximum rotation force. As shown in FIGS. 4 and 5, the most suitable leg angle according to the leg length and the height of the saddle is shown. It can be seen that the angle φ is different because the position to form a different.

In FIG. 6, a is the position of the crank arm that causes the maximum rotational force when the leg is long or the saddle is raised, and b is the position where the maximum rotational force is normally when the leg is short or the saddle is lowered. It is shown that the short leg or lower saddle has a φ value of about 73 °, and in general, the φ value is about 80 ° and the leg is long or the saddle is raised.

Therefore, it is preferable to mount the crank arm at the most suitable position according to the length of the leg and the height of the saddle, and the position of the crank arm can be made variable by a known clamping method.

As described above, the present invention continuously distributes the force distribution on the crank arm according to the angle of the crank arm in one rotation of the crank arm while distributing the force applied to the crank arm by dispersing the force applied to the crank arm even when driving for a long time. It can reduce the fatigue of, and has the same effect as the previous product at the same cost.

Claims (1)

The pedal side chain sprocket (SP1) of the bicycle is formed in an oval shape, and the angle (ac) between the pedal side crank arm and the chain sprocket is mounted in a range of 75 ° to 87 ° according to the length of the leg and the height of the bicycle saddle. Bicycle pedal side oval chain sprocket, characterized in that configured to be.