JP2002240770A - Pedaling mechanism of bicycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drastically solve the most fundamental problems regarding drive performance of a conventional human power pedaling mechanism such as pulsation of rotational drive force and insufficient torque at around a top dead center to improve performance of a bicycle. SOLUTION: Driving characteristics are drastically improved by setting a drive side point of application of force as a base point for efficiently converting/ transferring drive force by pedaling to the rotational drive force of a rear wheel with a predetermined phase difference with a pedal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a pedaling mechanism for a bicycle that rotates a rear wheel by alternately depressing a pair of pedals.

[0002]

2. Description of the Related Art Conventionally, a pedaling mechanism of a bicycle includes a "driving force generating mechanism" for generating driving force and a "driving force transmitting mechanism" for transmitting driving force. The driving force generation mechanism consists of a crankshaft located below the saddle and 180 ° at both ends of the crankshaft.
It comprises a pair of pedal arms with pedals attached with a phase difference of degrees, and generates a rotational driving force on the crankshaft by alternately depressing the pair of pedal arms. The driving force transmission mechanism is composed of a driving sprocket mounted on the crankshaft, a driven sprocket mounted on the rear wheel shaft via a one-way clutch, and a chain or belt wound around the driving sprocket and the driven sprocket. It plays the role of transmitting the driving force as it is to the rear wheel axle.

[0003] The rotational driving force generated by such a pedaling mechanism is mainly a vertical component due to human leg strength or weight, so that the tangential component to the crankshaft changes in a sine curve with respect to the pedal phase, and the pedal is moved vertically. Near the state (dead center), it is almost {zero}. This is a fatal problem of the rotation driving force generating mechanism by human power. The driving force transmission mechanism transmits the driving force by wrapping the chain around a constant diameter driving sprocket attached to the crankshaft and a constant diameter driven sprocket attached to the rear wheel shaft. Since the point is always constant (at top dead center) irrespective of the pedal phase, the transmitted driving force is always the same as the direction of the driving input, and the fluctuating driving input is transmitted as it is as the rotational driving force for the rear wheels. You. As a result, the transmitted driving force fluctuates in a sine curve even if the rotation speed of the crankshaft as the drive input is constant, so that the load repeats ゛ acceleration-deceleration ゛, and the acceleration energy is greater than the deceleration energy At times, the cycle can be continued because of the inertia, but when the load increases, the inertia decreases and the cycle is interrupted (operation is disabled). In particular, since there is no inertia at the time of starting, even when the load is small, the pedal cannot be started near the top dead center. This is a so-called vertical dead center problem, which is an essential problem of the conventional pedaling mechanism.

[0004]

The most essential problems of the driving performance such as the pulsation of the driving force of the conventional pedaling mechanism and the shortage of the driving force in the vicinity of the upper and lower dead center have not been solved at present. The current bicycle cannot be used in a city with many slopes because there are many slopes. It would be a very important task to improve the performance of the bicycle by drastically re-washing the pedaling mechanism with human power.

[0005]

As a means for solving this problem, the present invention aims to provide a new pedaling mechanism having the following structure. In the present invention, while the rotational driving force is generated by the pedaling operation in the same manner as in the related art, the drive-side working point as the driving force transmission base point is provided with a predetermined phase difference from the pedal (usually 45 to 90 degrees around the center of the crankshaft). As a result, the tangential driving force T acting on this point and the transmission driving force T1 acting in the direction of the driven side acting point are changed by the pedal phase a.
At an angle (90 + a + b degrees), and the transmission driving force T1 has a reciprocal transmission coefficient Co of a sine curve.
sec (a + b) works, and the drive input T becomes a substantially constant value even in the vicinity of the extremely small top and bottom dead center. As described in the previous section [0003], in the conventional pedaling mechanism, the difference in mechanism is that the direction of the transmission driving force T2 is always the same as the driving force T regardless of the pedal phase a. That is, the driving force can be leveled mechanically with a small improvement of the driving mechanism, and the output efficiency can be greatly improved as described later.

[0006]

[Drive characteristics of the new pedaling mechanism] "Link type pedaling" in which the right and left drive side working points arranged on the crankshaft and the driven side working point of the rear wheel axle are connected by a rack / pinion mechanism (details will be described later) with a phase difference of 180 degrees. The mechanical analysis of the driving performance will be described based on the “mechanism”. (FIG. 1) is a schematic diagram showing a mechanical relationship centering on the driving side action point A1,
The tangential component of the driving force W mainly in the vertical direction due to human power is generated as the tangential driving force T at the driving side action point A1. At this time, the driving side operating point A1 is shifted from the driven side operating point A2.
The transmission driving force T1 (= axial thrust of the rack) acting in the direction of the arrow A is the pedal phase a
Intersects at an angle a + b obtained by adding the initial phase b of the drive-side action point A1, so that the tangential component T1 sin of the transmission drive force T1
(A + b) balances the driving force T. Here, the initial phase b is a function of the dimensions of the pedaling mechanism and the pedal phase a, and can be practically kept within the range of 0 to 10 degrees. (Equation 1), (Equation 2), and (Equation 3) express the above-mentioned mechanical relationship. The transmission speed V1 of the transmission driving force T1 in the direction of the driven side operation point A2 at the driving side operation point A1 is equal to the tangential speed V of the driving force T and the angle 90-.
Since it crosses at (a + b), it can be regarded as the velocity component in that direction of V and is expressed by (Equation 4). [Figure 3]
1), (Equation 2) and (Equation 3) are graphed, wherein the ratio of the transmission driving force T1 to the driving force T is the driving force ratio, and the ratio of the transmission driving speed V1 to the driving speed V is the driving speed ratio. In addition, the value of the dimension d = R / L of the pedaling mechanism that determines the initial phase angle a is shown as a parameter.

(Equation 1)

(Equation 2)

(Equation 3)

(Equation 4)

[0007]

[Characteristic comparison] (FIG. 3) As is clear from FIG. 3, the transmission driving force T2 in the conventional pedaling mechanism is the same as the driving input T, and changes in a sine curve with respect to the pedal phase a. The driving force T1 is the driving input T
Is maintained in a substantially constant value with respect to the phase angle a because the transfer coefficient acts even if f varies like a sine curve. Drive input speed V
Is constant when the load is 0 in the conventional pedaling mechanism, but V1 = Vsin (a + b) in the new pedaling mechanism.
It fluctuates like a sine curve. Since the drive output is obtained by multiplying the net drive force obtained by subtracting the load from the transfer drive force by the transfer speed, in the conventional pedaling mechanism, the net drive force is always negative when the phase a of the pedal is near the top and bottom dead center, so that Although continuous operation cannot be performed without force, the new pedaling mechanism can always maintain the net driving force to be positive when the load is within the transmission driving force, and the transmission speed Vsi
The product multiplied by n (a + b) is the output. The relationship between the load and the output can be expressed by (Equation 6) and (Equation 7).
On the vertical axis, the ratio of the net drive output to the maximum drive output is output efficiency y1 (new pedaling mechanism) and y2 (conventional pedaling mechanism), and the ratio of load to drive input is load factor x. FIG. 4 shows changes in the output efficiencies y1 and y2 due to the pedal phase a.
The acceleration energy is obtained by integrating the net drive output with time, and means the total energy that can overcome the load and can be accelerated. When the acceleration energy when the load factor x is 0 is the maximum acceleration energy, the acceleration energy is the maximum. The relationship between the acceleration energy ratios e1 (new pedaling mechanism) and e2 (conventional pedaling mechanism), which are ratios to the acceleration energy, and the load factor x can be expressed by (Equation 8) and (Equation 9).
5) is a graph of it. (Figure 7), (Figure
8) As is clear, the output efficiency of the conventional pedaling mechanism is 64% of the drive input where the load factor x is the average drive force, even if the excess or deficiency energy is absorbed by the inertia, while the drive limit is the operating limit. With the new pedaling mechanism, it is possible to operate the load factor x up to 100%. There is a great difference in the acceleration energy at each load factor, indicating a drastic improvement in output efficiency.

(Equation 5)

(Equation 6)

(Equation 7)

(Equation 8)

(Equation 9)

The pedaling mechanism of the bicycle includes a driving force generating mechanism 10 for converting the pedaling operation force of the driver H into a rotating force of the crankshaft 13, and a driving force conversion for transmitting the force generated on the crankshaft 13 to the rear wheel shaft 27. It consists of a transmission mechanism (Fig. 6).

The driving force generating mechanism 10 has a pedal 11 at a tip end thereof, and includes a pair of pedal arms 12, 12 corresponding to the left and right feet of the driver H and a crankshaft 13, and a driving force conversion transmitting mechanism. Reference numeral 20 includes a pair of crank arms 21, 21 having a fulcrum member 22 at the distal end, a pair of racks 23, 23, a pair of pinion gear units 26, and a rear wheel shaft 27 (see FIG.
6), (Fig. 7).

The pair of crank arms 21 are fixed to both ends of the crankshaft 13 at 180-degree symmetric positions. A pair of fulcrum members 22 as drive-side action points are connected to each crank arm.
It protrudes outward from the side of the tip of 21 (Fig.
1, Figure 2). Further, the pair of racks 23, 23 are also functionally connecting rods, and one end of each of them is a fulcrum member 2 respectively.
Connection bearings 23j, 23j suitable for 2, 22 are attached.

[0011] The pair of racks 23, 23 are provided with connecting bearings 23j, 23.
The fulcrum members 22 and 22 are inserted into j to be swingably connected to the fulcrum members 22 and 22. Further, the pair of pedal arms 12, 12 are fixed to the fulcrum members 22, 22, respectively, from outside the connection bearings 23j, 23j. At this time, the mounting angle of the pedal arms 12, 12 with respect to the crank arms 21, 21 is such that the position of the pedal 11 of each pedal arm 12, the phase difference between the pedal arm 12 and the crank arm 21 (45 to 90 degrees)
The position is set to be equivalent to the position of the pedal 11 when it is assumed that the pedal 11 is directly attached to the crankshaft. Therefore, the pair of pedals 11, 11 are located on opposite sides of the crankshaft 13 (FIG. 9).

The other ends of the pair of racks 23, 23 having one ends connected to the fulcrum members 22, 22 slidably penetrate the casings 26a of the corresponding pinion gear units 26, respectively, and are pulled out rearward (see FIG. 1). 6, Figure 7). Pinion gear unit 26
, A pinion gear 25 and a one-way clutch 24 coaxially arranged with the pinion gear 25 are incorporated, and through holes formed with linear bearings 26b, 26b are formed in the front and rear surfaces of the casing 26a (FIG. 8).

The pair of pinion gear units 26 and 26 are respectively processed to prevent the one-way clutch 24 and the pinion gear 25 from coming off through one end of the rear wheel shaft 27 so that the entire pinion gear unit 26 swings with respect to the rear wheel shaft 27. It is attached so that it can be done. At this time, the pinion gear 25 can freely rotate around the rear wheel shaft 27, and the one-way clutch 24 is fixed to the rear wheel shaft 27. Also, the one-way clutch 24 is engaged with the pinion gear in the direction of performing the connecting operation only when the pinion gear 25 rotates in the traveling direction of the bicycle.

On the other hand, the gear teeth 23 engraved below the rack 23
g is engaged with the pinion gear 25 when the rack 23 is inserted into the casing 26a via the linear bearings 26b, 26b, and serves as a driven side action point. As a result, even if one end of the rack 23 swings up and down, the pinion 25 does not rotate, and the pinion gear rotates only when the rack 23 reciprocates in its axial direction. Further, the rear wheel axle 27 is driven by the one-way clutch 24 in the same direction only when the pinion gear 25 rotates in the traveling direction of the bicycle.

The bicycle pedaling mechanism incorporated as described above operates as follows. When the driver H performs pedaling operation, the crank arm 21 and the pedal arm
12 rotates around the crankshaft 13, and a tangential drive input T generated at a fulcrum member 22 which is a base point of drive force transmission is converted into an axial thrust of a rack as a drive force transmitted to the rear wheels. However, the magnitude of the tangential component balances the drive input T. That is, as described in the preceding section [0006], a reciprocal transmission coefficient of a sine function acts on the driving force T, so that a substantially constant transmission driving force is generated even when the pedal phase a changes (FIG. 1). ).

The driving force conversion transmission mechanism 20 of the present invention comprises a driving sprocket 28 mounted on the crankshaft 13, a driven sprocket 29 mounted on the rear wheel shaft 27, and a chain CH wound around the driving sprocket 28 and the driven sprocket 29. (Figure 2).

The drive sprocket 28 has tooth profiles 28P, 28P having a radius of curvature smaller than the sprocket radius in order to provide a function as a drive-side action point of force with a symmetric phase of 180 degrees across the crankshaft 13. An elliptical one is used, and the driven sprocket 29 (having the same structure as the conventional pedaling mechanism) is connected to the rear wheel axle via the one-way clutch 24.
The chain CH is provided with a tensioner 29t. The teeth on both ends of the pedaling arms 12, 12 and the drive sprocket 28 are positioned with respect to the pedal with a phase difference (45 to 90 degrees) about the crankshaft (FIG. 2).

The driving characteristics when the present pedaling mechanism is operated are basically as described in [0006], but the tooth profile at both ends as the driving side action point is completely the same as the link type fulcrum described in the preceding paragraph. Since the meshing point with the chain slightly fluctuates according to the phase a of the pedal instead of the fixed point, a slight difference occurs in the characteristic curve by this amount.

[0019]

As described in the above paragraphs [0006] and [0007], by providing a drive-side action point, which is a base point of drive force transmission, with a predetermined phase difference from the pedal, the characteristics of the transmitted drive force are greatly changed. The most essential problems such as the top dead center problem of the current pedaling mechanism by human power can be solved with a small improvement of the mechanism, and the output efficiency can be greatly improved. In short, the pedal operation that was heavy at the top dead center becomes lighter, and it is possible to climb up a steep hill without coasting, and it is possible to speed up lightly on flat terrain.

[0020]

[Brief description of the drawings]

FIG. 1 is a mechanical relationship diagram of a link-type pedaling mechanism of the present invention.

FIG. 2 is a mechanical relationship diagram of a special sprocket type pedaling mechanism of the present invention.

FIG. 3 is a driving force diagram of the pedaling mechanism of the present invention.

FIG. 4 is an output diagram of the pedaling mechanism of the present invention.

FIG. 5 is an acceleration energy diagram of the pedaling mechanism of the present invention.

FIG. 6 is a side view schematically showing an embodiment of the present invention.

FIG. 7 is an exploded perspective view of the power transmission mechanism according to the embodiment of the present invention.

FIG. 8 is a cross-sectional view illustrating a main part of the power transmission mechanism according to the embodiment of the present invention.

FIG. 9 is a diagram of a driving force generating mechanism according to the embodiment of the present invention.

[Explanation of symbols]

 CH chain 12 pedal arm 13 crankshaft 22 fulcrum member 23 rack 24 one-way clutch 25 pinion gear 27 rear wheel shaft 28 drive sprocket 29 driven sprocket

Claims (3)

[Claims] 1. A point of action of a force centering on a crankshaft for transmitting a drive input with a predetermined phase difference (usually 45 to 90 degrees) to right and left pedals symmetrical with respect to 180 degrees (hereinafter referred to as a drive side action). A driving force generating mechanism having a driving point, and a driving point of force that pivots by pedaling operation by directly connecting a point of application of a force centered on the rear wheel axle (hereinafter referred to as a driven point of operation) with a link or a chain. A pedaling mechanism for a bicycle comprising a power conversion transmission mechanism that converts the tangential driving force of the crankshaft generated in the above to the direction from the driving side working point to the driven side working point and transmits the converted power. 2. A drive in which a two-point crankshaft having a phase difference of 180 degrees as a drive-side action point and left and right pedal arms fixed at both ends thereof with a predetermined phase difference (45 to 90 degrees). It is composed of a force generating mechanism and a driving force conversion transmission mechanism having a structure in which each end of a left / right rack / pinion unit attached to both ends of a rear wheel shaft via a one-way clutch is coupled to a crank shaft via a bearing. The bicycle is characterized in that the driving force in the tangential direction with respect to the crankshaft at the point is converted into the direction of the rack shaft and transmitted, and the rear wheels are directly driven via links instead of the conventional chain drive. Pedaling mechanism. 3. The method according to claim 1, wherein the conventional circular sprocket is replaced with a 180 ° symmetrical phase with respect to the crankshaft center to provide a function as a drive side action point. A specially shaped sprocket with two teeth, and a driving force generating mechanism with a structure in which the left and right pedal arms are fixed to both ends of the crankshaft with a predetermined phase difference (45 to 90 degrees) from both end teeth (action point) And a power conversion transmission mechanism that drives a rear wheel by winding a chain or belt around the pedaling mechanism. Embodiments of the present invention will be described below with reference to the drawings.