JP2008080879A - Set of crank arms for bicycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a set of crank arms for a bicycle for easily pedalling the bicycle with a simple structure, a small number of components, and high productivity. <P>SOLUTION: A set of the crank arms 1A for a bicycle of the present invention comprises a first lightweight crank arm 11 and a second heavyweight crank arm 12. In a set of the crank arms 1A for a bicycle of the present invention, the second crank arm 12 is heavier than the first crank arm 11 by 50-260g. The first and second crank arms 11, 12 are balanced at a position inclined 10-20 degrees from a perpendicular A to the rotational direction for moving a bicycle B forward in a no-load and static condition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a set of bicycle crank arms on which pedals are rotatably mounted.

Conventionally, a pair of bicycle crank arms is designed to be symmetric with respect to the center of rotation. That is, the rotation diameter of the pedal attached to the crank arm of a pair of bicycles is adapted to the range of motion depending on the driver's physique.
As a crank arm of such a set of bicycles, a crank arm shown in Non-Patent Document 1 will be described with reference to FIG. FIG. 6 is an explanatory diagram for explaining a state in which a pair of conventional bicycle crank arms rotate.
As shown in FIG. 6, for example, in one crank arm, the rotating pedal position during traveling is divided into four blocks (1) to (4) at intervals of 90 ° with respect to the vertical line, and the direction of the arrow Suppose that one crank arm is rotated. At this time, when the pedaling force that contributes to traveling is measured, the (1) block and (2) block contribute to traveling as driving force, but the (3) block and (4) block work as resistance. In the transition state from the (4) block to the (1) block, the other crank arm is in the transition state from the (2) block to the (3) block, and the driving force is reduced. Furthermore, a large pedal effort is required to rotate the bicycle in the forward direction.

  When traveling on a normal flat ground or downhill, the above is not particularly problematic because of the inertial force of the bicycle and the force of gravity acting in the traveling direction. However, when driving a bicycle from a stationary state or when climbing a hill, a large pedaling force is required, which places a burden on the foot and causes a great fatigue when riding a long ride.

  In order to solve this problem, in Patent Document 1, the crank is expanded and contracted depending on the running state using a rotary link mechanism called an eccentric guide plate device. When the drive telescopic crank having such a configuration is driven, the pedal can be rotated at the same diameter as the conventional one, and the crank length can be extended and the amount of torque can be increased when the driving force is required.

JP-A-5-155375 Asahi Shimbun (Evening), page 5 (issued September 14, 2002)

  Although the above-mentioned conventional technology solves the problem that a heavy pedaling force is required when driving a bicycle from a stationary state or when climbing a hill, the mechanism is complicated, but the mechanism is complicated. There are many parts and productivity is inferior. Furthermore, the bicycle has many opportunities to be exposed to the outdoors regardless of the weather, and the complicated link structure is likely to break down and is likely to be deteriorated, so that its life is shortened.

  In addition, the motor ability of the driver is not symmetrical, and there are right-handed and left-handed. Right-handed and left-handed are not only dexterous, but also cause a difference in power. That is, the pedaling force on the side that is not the dominant leg is usually smaller than the pedaling force on the side that is the dominant leg. Therefore, a normal bicycle designed symmetrically does not fully utilize the characteristics of each driver.

  The present invention has been made in view of the above problems, and provides a pair of crank arms for a bicycle that has a simple configuration, has a small number of parts, is highly productive, and is easy to row a bicycle. Objective.

A set of bicycle crank arms of the present invention that solves the above-described problems are a set of bicycle crank arms that are rotatably mounted with a bicycle body interposed therebetween, and the set of bicycle crank arms includes: A light weight first crank arm on which a pedal is rotatably mounted and a heavy second crank arm on which a pedal is rotatably mounted are provided.
Preferably, the first crank arm is disposed on the side that is the dominant leg, and the second crank arm is disposed on the side that is not the dominant leg.
More preferably, the second crank arm makes the inertial mass at the pedal position 50 g to 260 g heavier than the first crank arm.

According to the present invention, since the second crank arm is heavier than the first crank arm, when the second crank arm reaches the starting position, the bicycle B is moved forward to return to the balance position by its own weight. It rotates in the direction of rotation. In this way, a part of the pedaling force on the non-dominant leg side can be compensated.
It should be noted that the “rowing position” refers to a position (position of 10 ° to 20 ° with respect to the vertical line) at which it is easy to input (stepping force) to the pedal.
In addition, the “balance position” refers to a position where the first crank arm and the second crank arm are balanced with no load when the tire is not in contact with the ground.
The “balance position” is substantially the same as “the rowing position”.

Further, according to the present invention, when the dominant leg side reaches a position where it is difficult to input (stepping force) to the pedal, a rotational force can be obtained by the input (stepping force) on the dominant leg side. Due to this rotational force, an inertial force acts on the second crank arm, and the second crank arm generates a rotational force that rotates in the rotational direction for moving the bicycle forward instead of the first crank arm. By this rotational force, the bicycle is moved forward by relatively rotating the first crank arm.
At this time, the second crank arm rotates while accelerating in the rotational direction for advancing the bicycle, so that the second crank arm passes through the position where the resistance of the second crank arm is the largest, and the second crank arm is rowed. Reaching out position.
Thus, by eliminating the position where it is difficult to input (stepping force) to the pedal on the dominant leg side, the pedal attached to the first crank arm 11 can be easily rowed on the dominant leg side.

  At the same time, when the second crank arm reaches the rowing position while accelerating, the rotational speed of the second crank arm at the rowing position increases, so that the side that is not the dominant leg is utilized by using the momentum. Can compensate for part of the pedaling force.

  The set of bicycle crank arms according to any one of claims 1 to 3, wherein a pedal attached to the second crank arm is shifted 180 degrees from a pedal attached to the first crank arm. The first crank arm and the second crank arm are balanced at positions inclined by 10 ° to 20 ° with respect to the vertical direction in the rotational direction for advancing the bicycle in a static state with no load, respectively. It is good also as a structure.

According to the present invention, when the pedal attached to the first crank arm on the dominant leg side is padded in the rotational direction in which the bicycle is advanced, the pedal of the first crank arm starts from 10 ° in the rotational direction in which the bicycle is advanced. Since the position reached 20 ° forward (rowing start position), it is possible to input (depressing force) to the pedal from that position. In this way, it is possible to make it easier to row the pedal attached to the first crank arm 11 on the dominant leg side by eliminating the position where it is difficult to input (stepping force) to the pedal on the dominant leg side.
That is, as compared with the contribution of the pedaling force in the conventional normal bicycle shown in FIG. 6, the rowing position of the first crank arm is deviated from 10 ° to 20 ° in the rotational direction for moving the bicycle forward. It is possible to reduce the area where it is difficult to transmit the pedaling force on the leg side.
For this reason, the decrease rate of the pedaling force during one rotation of the crank arm can be kept low according to the characteristics of each driver, and the bicycle can be easily rowed.

In addition, the present invention may be a bicycle having a set of bicycle crank arms according to any one of claims 1 to 3.
According to the present invention, since it has the pair of bicycle crank arms described in any one of claims 1 to 3, it is possible to obtain a bicycle that is easy to row.

According to the pair of bicycle crank arms of the present invention, the weight of the second crank arm on the non-dominant leg is set to be heavier than the weight of the first crank arm on the dominant leg side. Can be compensated for by the inertial force obtained on the dominant leg side, making it easier to row the bicycle at the time of starting or at low speeds of climbing.
Further, according to the pair of bicycle crank arms of the present invention, since it has a simple configuration, deterioration and damage are reduced.
Moreover, according to the set of bicycle crank arms of the present invention, the number of parts can be reduced, and the productivity is increased. Moreover, it can be manufactured at low cost.
Further, according to the bicycle of the present invention, the bicycle can be easily rowed at the time of starting or at a low speed of climbing.

  Next, the best mode for carrying out the present invention will be described. In the drawings to be referred to, FIG. 1 is a view showing a state in which a pair of bicycle crank arms according to the present embodiment is attached to a bicycle, and FIG. 2 is a pair of bicycle cranks according to the present embodiment. FIG. 3 is an enlarged view showing a state in which the arms are statically balanced with no load, and FIG. 3 is an explanatory diagram for explaining a state in which a pair of bicycle crank arms according to the present embodiment rotates.

  As shown in FIG. 1, a pair of bicycle crank arms 1A according to the present invention includes a lightweight first crank arm 11 on which a pedal 7 is rotatably mounted and a pedal 7 that is rotatably mounted. The second crank arm 12 is heavy and is pivotally attached to the bicycle B.

Here, as shown in FIG. 1, the first crank arm 11 and the second crank arm 12 are arranged on the left and right sides of the bicycle B, and are provided at substantially the center of each main body attachment portion 13 (see FIG. 2). A drive shaft (not shown) is inserted through the formed through hole and is integrally attached to the bicycle B.
In the present embodiment, since there are generally many right-handed people, the driver's dominant leg is assumed to be the right leg, and the first crank arm 11 is disposed on the right side in the traveling direction of the bicycle B when viewed from the bicycle B. The second crank arm 12 is arranged on the left side in the traveling direction of the bicycle B. Note that the first crank arm 11 is integrally formed with a gear (not shown) of the bicycle B, as in a normal bicycle.

  As shown in FIG. 2, the first crank arm 11 and the second crank arm 12 are rotatable about a drive shaft (not shown). In the present embodiment, it is assumed that the bicycle B moves forward by rotating the pair of bicycle crank arms 1A in the direction of the arrow in FIG.

  The first crank arm 11 is a crank arm for a driver's dominant leg, has a substantially rod shaft shape, has a main body attachment portion 13 that is an attachment portion to the bicycle B at one end portion, and the other end. The pedal mounting part 14 for pedal mounting is provided in the part. As the first crank arm 11, a known bicycle crank arm can be used.

The second crank arm 12 is a crank arm for a leg which is not a driver's dominant leg, has a substantially rod shaft shape, and has a main body attachment portion 13 (not shown) which is an attachment portion to the bicycle B at one end portion. And has a pedal mounting portion 14 for pedal mounting at the other end.
The second crank arm 12 is formed in an L shape, has a main body attachment portion 13 at one end, and has a pedal attachment portion 14 in a portion bent in an L shape.
The length from the main body attachment portion 13 to the pedal attachment portion 14 of the second crank arm 12 is substantially the same as that of the first crank arm 11.

The second crank arm 12 is formed such that the inertial mass at the pedal position is 50 to 260 g, more preferably 100 to 160 g heavier than the inertial mass at the pedal position of the first crank arm 11.
This is because if the difference in inertial mass at the pedal position is less than 50 g, the effect of supplementing the treading force cannot be obtained effectively, while if it exceeds 260 g, the burden on the dominant leg side becomes excessive.
For example, it is possible to make a difference in inertial mass at the pedal position by forming the first crank arm 11 from aluminum and the second crank arm 12 from stainless steel.

  Further, for example, the first crank arm 11 and the second crank arm 12 may be formed of the same material. As described above, the second crank arm 12 and the first crank arm 11 are different in shape, and the second crank arm 12 has a larger volume than the first crank arm 11, so that the second crank arm 12 is larger than the first crank arm 11. Since the amount of material used increases, even when the same material is used, a difference in inertial mass at the pedal position can be provided.

  Even if the weight of the second crank arm 12 is made heavier than that of the first crank arm 11 in this way, it does not greatly differ from the weight range of a normal bicycle crank arm. Further, although the weight balance on the left and right is biased to one side with respect to the traveling direction of the bicycle B, if the difference in the inertial mass at the pedal position is within the range of 50 g to 260 g, the vehicle travels at the normal traveling speed of the bicycle B. It will not be a hindrance.

As shown in FIG. 2, the balance positions of the first crank arm 11 and the second crank arm 12 configured as described above are as follows. The axis line connecting the attachment portions 14 is a position inclined with respect to the vertical line A by a predetermined angle (inclination angle θ1) in the rotational direction in which the bicycle is advanced. In the present embodiment, the direction of the arrow shown in FIG.
Further, the “static state with no load” is a state in which the tire is not grounded and the first crank arm 11 and the second crank arm 12 are stationary, and the first crank arm 11 and the first crank arm 11 are stationary. 2 A state where no load is applied to the crank arm 12.
Since the second crank arm 12 is heavier than the first crank arm 11 as described above, the first crank arm 11 is always located above the main body mounting portion 13 in the no-load state. The second crank arm 12 is positioned below the main body attachment portion 13 and balanced.

The inclination angle θ1 formed by the second crank arm 12 and the perpendicular A in a static state with no load is preferably 10 ° to 20 °.
When the inclination angle θ1 is less than 10 °, there is almost no difference from a normal bicycle, and the effect of supplementing the pedaling force cannot be effectively obtained. On the other hand, when the inclination angle θ1 exceeds 20 °, the burden on the dominant leg side is reduced. This is because it becomes excessive.

Hereinafter, with reference to FIG. 3, the operating state of the pair of bicycle crank arms 1A of the present invention will be described.
FIGS. 3A to 3H are views showing the operation of the crank arm.
In FIG. 3, for convenience of explanation, a circle is drawn along the trajectory of the pedal, and the inside of the circle is equally divided into eight blocks.

As shown in FIG. 3A, the first crank arm 11 and the second crank arm 12 are each tilted, for example, by 20 ° with respect to the perpendicular A (see FIG. 1) in the rotational direction in which the bicycle is advanced. In the right position.
In the present embodiment, the pair of bicycle crank arms 1A is rotated clockwise (in the direction of the arrow in FIG. 2) to advance the bicycle B.
The pedaling position of the pedal attached to the first crank arm 11 is, for example, a position advanced by 20 ° in the rotational direction in which the bicycle B is advanced, so that the pedal attached to the first crank arm 11 is Smooth.
When the driver depresses the pedal attached to the first crank arm 11 in this state, a rotational force is gradually generated by the depression force.
On the other hand, when the first crank arm 11 is rotated downward in the clockwise direction, the second crank arm 12 is relatively rotated in the clockwise direction along the circumferential direction by the rotation of the first crank arm 11.

As shown in FIG. 3B, when the first crank arm 11 rotates between the blocks (2) toward the block (3), the second crank arm 12 relatively blocks between the blocks (6). Rotate towards (7).
Between the blocks (2), the pedal attached to the first crank arm 11 is stepped substantially vertically, so that the stepping force is efficiently transmitted and the rotational force can be increased.

As shown in FIG. 3 (c), when the driver steps on the pedal attached to the first crank arm 11 and advances between the blocks (3) toward the block (4), the second crank arm 12 is , Relatively rotate between the blocks (7) toward the block (8).
Between the blocks (3), the pedal attached to the first crank arm 11 is stepped substantially vertically, so that the stepping force is efficiently transmitted and the rotational force can be increased.

  As shown in FIG. 3D, when the driver further steps on the pedal attached to the first crank arm 11 and advances between the blocks (4) toward the block (5), the second crank arm 12 is moved. Relatively rotates between the blocks (8) towards the block (1).

  As shown in FIG. 3B and FIG. 3C, when the pedal attached to the first crank arm 11 passes between the block (2) and the block (3), The pedaling force of the attached pedal is the largest and the turning force is the largest.

When the first crank arm 11 further rotates and the pedal attached to the first crank arm 11 reaches near the position a in FIG. 3 (e), the pedal starts to be kicked slightly rearward. The input (stepping force) on the dominant leg side of the person becomes difficult and the rotational force is attenuated.
Instead, at each stage of FIG. 3 (a) to FIG. 3 (d), in particular, at the stage of FIG. 3 (b) to FIG. Due to the inertial force applied to the crank arm 12, the second crank arm 12 rotates from the position a 'to the vicinity of the c' position shown in FIG. 3 (e). 11 is rotated from position a to near position c. In this way, it is possible to make it easier to row the pedal attached to the first crank arm 11 on the dominant leg side by eliminating the position where it is difficult to input (stepping force) to the pedal on the dominant leg side.

  Then, when the pedal attached to the second crank arm 12 is depressed from near the position c ′ in FIG. 3 (e), rotational force is generated by the input (stepping force) on the non-dominant leg side, and FIG. 3 (f), FIG. 3 (g) and FIG. 3 (h), the second crank arm 12 rotates in the rotational direction for moving the bicycle B forward, and the first crank arm 11 relatively moves in the rotational direction for moving the bicycle B forward. Rotate to

  When the second crank arm 12 reaches the rowing position, the state where the second crank arm 12 becomes the resistance of the first crank arm 11 is eliminated. Since the second crank arm 12 tries to return to the balanced position (see FIG. 3A) due to its own weight, the second crank arm 12 rotates in the rotational direction (the direction shown in FIG. 3G) for moving the bicycle B forward. With this rotational force, a part of the pedaling force on the side that is not the dominant leg can be compensated.

  Then, the second crank arm 12 returns to the balanced position, and the first crank arm 11 returns to the balanced position, that is, reaches the starting position, so that the driver can again smoothly on the dominant leg side. Can be rowed. Thus, since the return of the first crank arm 11 to the balance position reaches the rowing position, it is not necessary to apply the pedaling force to the rowing position, and the bicycle B can be easily rowed. Moreover, since the position where it is difficult to transmit the input (stepping force) to the pedal on the non-dominant leg side and the dominant leg side can be passed by inertial force, it is possible to suppress a decrease in driving force when the pedal is rotated once. .

The operations of the first crank arm 11 and the second crank arm 12 can also be described as follows. Here, ω: rotational angular velocity, R: arm length (radial direction) of first crank arm 11 and second crank arm 12, r: arm radial length of first crank arm 11 and second crank arm 12 ( Radius), dr: arm minute length (radius) of first crank arm 11 and second crank arm 12, and γ: arm density of first crank arm 11 and second crank arm 12; 11 and the force dF ₁ , dF ₂ in the rotation direction at the dr portion of the second crank arm 12 can be expressed by Expression (1) and Expression (2). Here, for simplification, it is assumed that the cross-sectional areas A ₁ and A _{2 of} the arms do not change in the radial direction.

  If the equations (1) and (2) are respectively integrated, the force F in the rotational direction of the first crank arm 11 and the second crank arm 12 can be obtained. Then, this force difference ΔF shown in the equation (3) is a necessary pedaling force difference.

As apparent from the equations (1) and (2), the rotational force F is proportional to the square of the rotational angular velocity ω, and therefore the value of ΔF is not constant, and is the value when the rotation is low. Is small and the value increases when the rotation is fast.
Thus, the static balance of the pair of bicycle crank arms 1A defined in the present invention and the difference in the required pedaling force during the traveling of the bicycle B are not in a proportional relationship that can be expressed linearly.

  However, as the subject of the present invention, the rotational angular velocity ω is small at the time of starting or at a low climbing speed, and a pedaling force is required as shown in Non-Patent Document 1. According to the pair of bicycle crank arms 1A according to the present invention, by making the statically balanced position easy to input (stepping force) to the pedal, the difference in pedaling force between the left and right legs inherent to the driver is utilized. Thus, a part of the pedaling force can be compensated.

  The content of the present invention has been described in detail above, but the content of the present invention is not limited to this, and can be widely modified and modified without departing from the spirit of the present invention.

For example, the first crank arm 11 and the second crank arm 12 are 10 in the rotational direction in which the axis connecting the respective pedal mounting portions 14 with respect to the vertical line A advances the bicycle B in a static state with no load. It is sufficient if it is formed so as to be balanced at a position inclined from 20 ° to 20 °.
Here, FIG. 4 and FIG. 5 are views showing a state in which a set of bicycle crank arms according to another embodiment of the present invention is statically balanced with no load.

As shown in FIG. 4, the pair of bicycle crank arms 1 </ b> B includes a first crank arm 21 and a second crank arm 22. The first crank arm 21 is a known bicycle crank arm.
The second crank arm 22 is positioned on the vertical line A, extends from the short shaft portion 22a having the main body attachment portion 13 and the short shaft portion 22a, and has a predetermined rotational direction for moving the bicycle B forward relative to the short shaft portion 22a. And a long shaft portion 22b having a pedal mounting portion 14 that is inclined at an angle. The long shaft portion 22b is formed to become wider as it goes in the circumferential direction.
The balance position between the first crank arm 21 and the second crank arm 22 is, for example, an inclination angle in the rotational direction in which the axis connecting the respective pedal attachment portions 14 advances the bicycle B with respect to the perpendicular A, respectively. The position is inclined by θ2 = 20 °.
Other configurations are the same as those of the pair of bicycle crank arms 1A.

Further, as shown in FIG. 5, the pair of bicycle crank arms 1 </ b> C includes a first crank arm 31 and a second crank arm 32. The first crank arm 31 is a known bicycle crank arm.
The second crank arm 32 is located on the vertical line A and extends from the shaft portion 32a having the main body attachment portion 13 and the shaft portion 32a, and is inclined by 90 °, for example, in the rotational direction in which the bicycle B is advanced with respect to the shaft portion 32a. The shaft portion 32b and the shaft portion 32c having the pedal mounting portion 14 extending in parallel with the shaft portion 32a from the shaft portion 32b are configured.
The balance position between the first crank arm 31 and the second crank arm 32 is, for example, an inclination angle in the rotational direction in which the axis connecting the respective pedal attachment portions 14 advances the bicycle B with respect to the perpendicular A, respectively. The position is inclined by θ3 = 20 °.
The other configuration is the same as that of the pair of bicycle crank arms 1A. In order to make a difference in inertial mass at the pedal position between the first crank arm 31 and the second crank arm 32, for example, the second crank arm A weight may be attached to 32.

It is a figure which shows a mode that the set of bicycle crank arms which concern on this embodiment were pivotally attached to the bicycle. It is an enlarged view of a set of bicycle crank arms according to the present embodiment, and shows a state in which they are statically balanced with no load. It is explanatory drawing for demonstrating a mode that a pair of bicycle crank arm which concerns on this embodiment rotates. It is a figure which shows a mode that a pair of crank arm for bicycles concerning other embodiment of this invention is balancing statically with no load. It is a figure which shows a mode that a pair of crank arm for bicycles concerning other embodiment of this invention is balancing statically with no load. It is explanatory drawing for demonstrating a mode that a pair of conventional crank arms for bicycles rotate.

Explanation of symbols

1A, 1B, 1C A set of bicycle crank arms 11, 21, 31 First crank arms 12, 22, 32 Second crank arms 13 Main body attachment portion 14 Pedal attachment portion A Perpendicular B Bicycle

Claims (5)

A pair of bicycle crank arms that are pivotally mounted around the bicycle body,
The set of bicycle crank arms includes:
A lightweight first crank arm with a pedal pivotably mounted on it, and
A heavy second crank arm on which a pedal is pivotally mounted for rotation;
A set of bicycle crank arms.   The pair of bicycle crank arms according to claim 1, wherein the first crank arm is disposed on a side that is a dominant leg, and the second crank arm is disposed on a side that is not a dominant leg.   The pair of bicycle crank arms according to claim 1 or 2, wherein the second crank arm has an inertial mass in a pedal position that is 50g to 260g heavier than the first crank arm. The pedal attached to the second crank arm is arranged 180 degrees away from the pedal attached to the first crank arm,
The first crank arm and the second crank arm are balanced at positions inclined by 10 ° to 20 ° in a rotational direction for advancing the bicycle with respect to a vertical line in a static state with no load. A set of bicycle crank arms according to any one of claims 1 to 3.   A bicycle having a set of bicycle crank arms according to any one of claims 1 to 4.

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