JP2013086535A - Weighted bicycle crank arm, and crank arm mounting weight - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a weighted bicycle crank arm for compensating for a part of pedaling force of a rider, especially when the bicycle starts moving or the bicycle is running uphill at low speed, and preventing the appearance from being impaired as compared with an existing bicycle.SOLUTION: The weighted bicycle crank arm 1 includes: a right crank arm 11 and a left crank arm 12 (a pair of crank arms) which are turnably pivoted across a body of a bicycle B with pedals 13 shifted at 180° from each other, and a weight 10 mounted on the left crank arm 12 so as to be rotated as the left crank arm 12 is rotated. In a no-load and stationary state, the center of gravity position G of the weight 10 is located below the center C of rotation on the perpendicular A, and the pair of crank arms are balanced at the position inclined in the rotational direction for advancing the bicycle B by the predetermined angle, respectively, with respect to the perpendicular A.

Description

  The present invention relates to a bicycle crank arm with a weight and one crank arm in a set of crank arms, in which a weight is attached to one crank arm in a set of crank arms rotatably mounted with a bicycle body interposed therebetween. The present invention relates to a weight for attaching a crank arm.

Conventionally, a set of 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.
In such a conventional pair of bicycle crank arms, when one crank arm is rotated once (360 ° rotation), the change in the influence of the pedaling force applied to the pedal of one crank arm A description will be given according to the pedal position.

  Here, the change in the influence of the driver's pedaling force according to the pedal position when one crank arm is rotated clockwise in one crank arm will be described with reference to FIG. In FIG. 5, for convenience, the circle drawn along the pedal trajectory is divided into eight blocks ((1) blocks to (8) blocks) at 45 ° intervals in the counterclockwise direction with respect to the vertical line. Yes. Here, description will be made on the assumption that the pedals of a pair of conventional crank arms move counterclockwise between the blocks (1) to (8).

  The pedaling force of the driver contributes to driving as a driving force when the pedal of one crank arm is in the blocks (1) to (4), but the pedal of one crank arm is in the blocks (5) to (8). When it is, it works as a resistance. When the pedal of one crank arm is in the transition state from the block (8) to the block (1), the pedal of the other crank arm is in the transition state from the block (4) to the block (5) and driven. Power is reduced. For this reason, it can be seen that a large pedaling force is required to rotate one crank arm further in the direction in which the bicycle is advanced (drive direction).

When driving on normal flat ground or downhill, you can use the rotational inertia force (force to keep the rotation) obtained by the treading force so far, and the gravity acting in the direction of the bicycle can be divided Thus, since it is possible to travel with less pedaling force, the reduction in driving force as described above is not particularly problematic.
On the other hand, the gear crank originally has a shape with poor rotation balance and is difficult to receive a rotational inertia force. In particular, during slow rotation such as when climbing (during low-speed climbing), the rotational angular force of the gear crank decreases and the rotational inertia force becomes insufficient, and the crank arm inputs to the pedal. There was a weak point that it was difficult to reach an easy position. In addition, especially for drivers with low leg strength, when starting a bicycle from a standstill, try to reduce the burden on the foot by moving the pedal to a position where it can be easily input to the pedal and then stepping on the bicycle. There was a need.

  In view of this problem, for example, in Patent Document 1, as shown in FIG. 6, a light first crank arm 111 on which a pedal is rotatably mounted and the same phase of the first crank arm 111 with a cycle of 180 °. And a heavy second crank arm 112 on which a pedal is pivotally mounted. The first crank arm 111 is provided with a mounting portion for the pedal 113 of the first crank arm 111 and the rotation of the bicycle B main body. The shaft and the mounting portion of the pedal 113 of the second crank arm 112 are provided along imaginary straight lines passing through the respective centers. The second crank arm 112 is mounted on the pedal 113 of the second crank arm 112. And the rotation axis of the bicycle B main body are bent so as to protrude on the opposite side to the rotation direction in which the bicycle is advanced with respect to a virtual straight line. The pair of crank arms 100 and the second crank arm 112 are configured so as to be balanced at positions inclined by 20 ° to 30 ° in the rotation direction with respect to the perpendicular in a static state with no load. Has been proposed.

  In the set of crank arms 100 described in Patent Document 1, the inertial mass at the pedal position of the second crank arm 112 is 50 g to 260 g, more preferably, the inertial mass at the pedal position of the first crank arm 111. It is formed so as to be heavier from 100 g to 160 g. As one of the simplest methods for providing a difference in inertial mass at the pedal position, the first crank arm 111 and the second crank arm are formed of metals having different specific gravities (for example, the first crank arm 111 is made of aluminum). And the second crank arm 112 is made of iron.

  The set of crank arms 100 described in Patent Document 1 is stationary with no load by making a difference in the moment (the force that causes rotation) between the first crank arm 111 and the second crank arm 112. By making the balance position of the first crank arm 111 and the second crank arm 112 in a state constant at all times, the position where it is difficult for the driver to input to the pedal is eliminated, and the pedal effort of the driver To compensate for a part of

  Further, for example, Patent Document 2 discloses a bicycle axle device that assists the rotational inertia force of a gear crank during traveling by providing a flywheel that rotates a wheel together with the hub on a hub of a bicycle rear wheel. Has been.

Japanese Patent No. 4616814 Utility Model Full Text No.2-01969

  However, in the set of crank arms 100 described in Patent Document 1, as shown in FIG. 5, the second crank arm 112 is connected to the mounting portion of the pedal 113 of the second crank arm 112 and the rotation of the bicycle B main body. Between the shaft and the virtual straight line, it is bent so as to protrude on the opposite side to the rotational direction in which the bicycle B is moved forward. However, in general bicycles, the left and right crank arms are usually formed in a substantially straight rod shape. Therefore, a bent crank arm such as the second crank arm 112 shown in FIG. There is a fact that it is difficult to accept.

  In addition, the shape of the second crank arm 112 can be freely set as long as the above-described balance position conditions are satisfied. On the other hand, in order to set the most suitable shape, various types of crank arms are actually manufactured and bicycles are manufactured. It is necessary to collect objective data by implementing a running experiment. However, this takes enormous effort and time. Moreover, since the number of molds is required for the number of patterns, the cost becomes high. Thus, the time and economical burden until setting the shape of the 2nd crank arm 112 was large.

  Further, unlike the set of crank arms 100 described in Patent Document 1 described above, it is not common to form the first crank arm 111 and the second crank arm 112 from different materials. By doing so, there is a possibility of giving the user a further uncomfortable appearance. On the other hand, if the first crank arm 111 and the second crank arm 112 are formed of the same material (for example, aluminum), the discomfort in appearance is reduced, but the first crank arm 111 and the second crank arm 112 are not affected. As a result of the reduced moment difference, the rotational inertial force of the entire gear crank is reduced, so that the driver's pedaling force cannot be sufficiently compensated.

  In particular, bicycles with exterior multi-stage transmission gears installed on the rear wheels that are currently widely distributed on the market need to use parts such as derailleurs in addition to the chain length being longer than single gear chains. For this reason, there are more elements (mechanical loads) that are resistant to rotational inertial force than single-gear bicycles. When the set of crank arms 100 described in Patent Document 1 is applied to such a bicycle with a multi-stage transmission gear, in order to compensate for a decrease in rotational inertia force due to a mechanical load, the first crank Although it is necessary to increase the moment difference between the arm 111 and the second crank arm 112, as described above, it is difficult to obtain a sufficient moment difference without giving the user a sense of discomfort in appearance.

  In addition, the bicycle axle device described in Patent Document 2 transmits the rotational inertia force generated by the flywheel attached to the rear wheel hub in the driving direction together with the hub to the hub during traveling. Since it assists the rotational inertia force of the gear crank indirectly by assisting the force that rotates the rear wheels in the driving direction, the burden on the driver's feet at the start of the bicycle or at low speed running uphill Can not be reduced. Further, in order to effectively improve the rotational inertia force of the gear crank, it is necessary to design the flywheel to be somewhat large. However, the provision of a large disc-shaped flywheel on the rear wheel may give the user a feeling of strangeness in appearance.

  The present invention has been made in view of the above problems, and firstly, a part of the driver's pedaling force can be compensated particularly at the time of starting a bicycle or traveling at a low speed on an uphill. An object of the present invention is to provide a bicycle crank arm with a weight that is less likely to cause an uncomfortable appearance in comparison with existing bicycles.

  The bicycle crank arm with a weight according to claim 1, which has solved the above-mentioned problem, is a pair of crank arms that are pivotally mounted so as to be rotatable with the bicycle body interposed therebetween, and are respectively attached to pedals with a 180 ° offset. A bicycle crank arm with a weight comprising: a weight attached to a base end side of one crank arm in the set of crank arms so as to rotate in accordance with the rotation of the one crank arm; In a static state with no load, the weight has a center of gravity positioned below the center of rotation on a vertical line passing through the center of rotation of the pair of crank arms, and the pair of cranks In a static state with no load, the arms are balanced at positions inclined by a predetermined angle with respect to the perpendicular to the rotational direction in which the bicycle moves forward. To.

  According to such a configuration, in a bicycle crank arm with a weight, when the weight is in a static state with no load, the position of the center of gravity is above the rotation center on a perpendicular line passing through the rotation center of the pair of crank arms. Since it is attached to one crank arm so as to be located on the lower side, a moment for moving the position of the center of gravity on the vertical line passing through the center of rotation always acts on the weight. Therefore, by attaching such a weight to one crank arm, it is possible to make a difference between the moments of one crank arm and the other crank arm. Thereby, a set of crank arms is always balanced at a fixed position in a static state with no load. More specifically, in a static state with no load, a set of crank arms is balanced with respect to the vertical line at positions inclined by a predetermined angle in the rotational direction in which the bicycle is advanced.

  According to this, it is possible to eliminate a position where it is difficult for the driver to transmit the pedaling force to the pedal attached to the crank arm. For example, when starting a bicycle, the pedal of the crank arm (the other crank arm) on which the weight is not attached can be positioned at a position where the driver can easily input the pedal.

Further, for example, when the other crank arm reaches a position where it is difficult to input to the pedal after starting the bicycle, one crank arm is caused by the rotational force obtained by the input to the other crank arm so far. In addition, since the rotational inertia force can be transmitted to the weight, a rotational force in the rotational direction that causes the bicycle to move forward on one crank arm is generated. And by this rotational force, the pedal of the other crank arm can be relatively rotated to pass the position where it is difficult to input to the pedal.
In addition, one crank arm and the weight rotate while accelerating in the rotational direction for moving the bicycle forward, so that one crank arm passes through a position where the resistance of the crank arm becomes the largest, and the other crank arm is pulled out. Since the position reaches the position, it is possible to eliminate the position where it is difficult to input to the pedal of one crank arm. Further, when one crank arm reaches the rowing position, the weight tends to return to the balance position due to its own weight, and thus a rotational force is generated in the rotational direction that causes the bicycle to move forward. The arm can be rotated in the direction of rotation that advances the bicycle. For this reason, a part of the driver's pedaling force can be compensated.
As described above, according to such a configuration, even when the rotational inertia force of the gear crank is reduced when traveling at a low speed on an uphill or the like, it is possible to easily ride a bicycle. Can be reduced.

  Furthermore, by attaching a weight to the base end side of one crank arm, it is less likely to cause an uncomfortable appearance when compared to a bicycle equipped with an existing set of crank arms not equipped with such a weight. Can do. That is, in a general town bicycle, a sprocket is usually mounted on the base end side of the other crank arm, and a user has some component attached to the base end side of the crank arm. Since many people are familiar with the situation, it can be said that even if a weight is provided on one crank arm, the influence on the appearance is small. This is clear even when compared with the case where the shape of the left and right crank arms is different or a flywheel is provided on the hub of the rear wheel, as in the technique described in Patent Document 1 or Patent Document 2 described above. is there. Thus, according to the bicycle crank arm with the weight, it is possible to make it difficult to produce an uncomfortable appearance when compared with a general town bicycle.

  The bicycle crank arm with a weight according to claim 2 is the bicycle crank arm with a weight according to claim 1, wherein the weight is a substantially disk-shaped member and is divided into two by a line passing through the center thereof. One region and the other region are formed so as to have a weight difference.

According to such a configuration, the center of gravity of the weight can be shifted from the position of the center of rotation of the pair of crank arms with a simple configuration, so that it is easy to manufacture a bicycle crank arm with a weight, Cost can be reduced.
In addition, in the bicycle crank arm with the weight, the weight is a substantially disk-shaped member, so that the rotation balance of the weight is good. For this reason, during running, the rotational inertia force of the weight itself can be obtained satisfactorily. Then, the rotational inertia force in the driving direction of the weight itself is transmitted to one crank arm, so that the rotational inertia force in the driving direction of one crank arm can be assisted. The rotational inertia force in the driving direction can be assisted.
Furthermore, since the weight is a substantially disk-like member, the weight is attached to the base end of one crank arm. In a typical town bicycle, a sprocket is attached to the base end of the other crank arm. Since it can be approximated in appearance and appearance, it is possible to make it more difficult to produce a sense of incongruity in appearance.

  Further, the bicycle crank arm with a weight according to claim 3 is the bicycle crank arm with a weight according to claim 2, wherein the weight is placed on either the one region or the other region. It is characterized by having a notch part by which a part is notched.

According to such a configuration, in the bicycle crank arm with the weight, the weight includes, for example, a cutout portion in which a part of the surface is cut out in one region, so that one region and the other Since there is a weight difference between the regions, the center of gravity position of the weight and the center of rotation of the pair of crank arms are shifted when attached to one crank arm. Accordingly, the balance position of the pair of crank arms can be shifted to a position inclined by a predetermined angle in the rotational direction in which the bicycle is advanced with respect to the vertical line.
Further, since the configuration is simple, the manufacturing is easy and the manufacturing cost can be reduced.

  The bicycle crank arm with a weight according to claim 4 is the bicycle crank arm with a weight according to claim 2 or claim 3, wherein the weight has an outer peripheral edge formed in an arc shape in a sectional view. It is characterized by being.

  According to such a configuration, in a bicycle crank arm with a weight, the air resistance of the weight can be reduced, so that it becomes easier to rotate the weight with the rotation of one crank arm, and the rotational inertial force of the weight itself. It becomes easier to obtain.

In addition, the present invention is provided on the base end side of one crank arm in a set of crank arms that are pivotally mounted with a bicycle body interposed therebetween and are shifted 180 ° from each other on the front end side. A crank arm mounting weight that is mounted so as to rotate in accordance with the rotation of the one crank arm, the crank arm mounting weight being divided into two regions by a line passing through the center of the crank arm mounting weight. The center of gravity position is located below the rotation center of the set of crank arms and the set of crank arms in a static state with no load. The line passing through the center of rotation and the center of gravity and the center of gravity is connected to the line connecting the base end portion and the tip end portion of the one crank arm. Characterized in that it the attached to the base end portion of one of the crank arm so that a predetermined angle tilt.
According to such a configuration, the action as described in the first aspect of the invention can be obtained by attaching to an existing bicycle, so that it is possible to easily ride the existing bicycle.

According to the bicycle crank arm with a weight of the present invention, it is possible to make it easier for the driver to input to the pedal when starting the bicycle or when traveling at a low speed on an uphill. Also, according to the bicycle crank arm with a weight of the present invention, the rotational inertia force of one crank arm can be assisted by the rotational inertia force of the weight itself, and as a result, the rotational inertia force of one set of crank arms can be reduced. Can assist. Thus, according to the bicycle crank arm with a weight of the present invention, a part of the driver's pedaling force can be compensated, and the burden on the driver's foot can be reduced.
Moreover, according to the bicycle crank arm with a weight of the present invention, the weight is attached to one of the crank arms, so that it is possible to make it difficult to produce an uncomfortable appearance in comparison with an existing bicycle.
Further, according to the bicycle crank arm with a weight of the present invention, since the configuration is simple, the manufacture is easy and the manufacturing cost can be reduced.
Moreover, according to the weight for attaching a crank arm of the present invention, it is possible to make it easier to ride an existing bicycle by being attached to the existing bicycle.

It is the figure which looked at a mode that one set of crank arms which provided the weight which concerns on embodiment of this invention was pivotally attached to the bicycle from the side surface of the bicycle main body. FIG. 2 is an enlarged view of the bicycle crank arm with a weight shown in FIG. 1, and shows a state in which the bicycle crank arm with a weight is statically balanced with no load. It is the figure which looked at the crank arm for bicycles with a weight which concerns on embodiment of this invention shown in FIG. 2 from the front of the bicycle main body, and is the enlarged view which made a part a cross section. It is a reference figure at the time of dividing a weight of a bicycle crank arm with a weight concerning an embodiment of the present invention into a plurality of parts, and calculating moment. It is explanatory drawing for demonstrating a mode that the crank arm for bicycles with a weight which concerns on embodiment of this invention rotates. It is the figure which looked at a mode that a pair of conventional crank arms were pivotally attached to the bicycle body from the side of the bicycle body.

  Next, the structure of the bicycle crank arm with weight and the crank arm mounting weight according to the embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, a bicycle crank arm 1 with a weight includes a right crank arm 11 and a left crank arm 12 (a set of crank arms) that are rotatably mounted with a bicycle B body interposed therebetween, and a left crank arm. 12 is provided with a weight 10 (crank arm mounting weight) attached so as to rotate with the rotation of the left crank arm 12. In the following, the right crank arm 11 and the left crank arm 12 may be collectively expressed as “a set of crank arms”.

As shown in FIGS. 1 and 2, the weight 10 is a substantially disk-shaped member made of metal here, and the center thereof is positioned coaxially with the rotation center C (see FIG. 2) of a set of crank arms. The left crank arm 12 is attached to the proximal end side. Therefore, here, the line L passing through the center of rotation C of the pair of crank arms shown in FIG. 2 and the line passing through the center of the weight 10 coincide.
The weight 10 is provided with a notch portion 10a in which a part of its surface is notched in one region when divided into two by a horizontal line passing through the center, and the weight 10 is disposed near the center of the left crank arm 12. A through-hole-shaped mounting portion 10b (see FIG. 3) for mounting on the base end side is provided.
The weight 10 is disposed between the left crank arm 12 and the bicycle B main body, and is attached to the base end side of the left crank arm 12 so as to rotate as the left crank arm 12 rotates. It has become.

  The notch 10a is formed by dividing a weight 10 main body into two parts by a horizontal line passing through the center of the weight 10 and a line connecting a point with a predetermined width from the outer peripheral edge to the center and a line passing through the center of the weight 10. And a region surrounded by a line along the outer peripheral edge of the mounting portion 10b is cut out. By providing this notch 10a, the weight 10 has a weight smaller in one region across the line passing through the center than in the other region. For this reason, the weight 10 has the center of gravity position G located in the other region (the side where the notch 1a is not provided) across the line passing through the center. Here, the center-of-gravity position G of the weight 10 indicates a position where the weight 10 is balanced in a static state with no load.

  The mounting portion 10b (see FIG. 3) has a through-hole shape as described above, and has a diameter substantially equal to the diameter of a main body mounting portion 12a of the left crank arm 12 described later. As shown in FIG. 3, a rotating shaft 20 that protrudes from the bicycle B main body is inserted through the attachment portion 10 b.

As shown in FIG. 2, the right crank arm 11 and the left crank arm 12 have a substantially straight bar shape, and are formed in the same shape and weight here. Further, as shown in FIG. 3, the right crank arm 11 and the left crank arm 12 have body attachment portions 11a and 12a, which are attachment portions to the bicycle B, on the proximal end side, and pedals on the distal end side. Pedal attachment portions 11b and 12b for attaching 13 and 13 respectively are provided. Further, the right crank arm 11 and the left crank arm 12 are pivotally attached to the bicycle B while being shifted from each other by 180 °. That is, the pedal 13 attached to the pedal attachment portion 11b of the right crank arm 11 and the pedal 13 attached to the pedal attachment portion 11b of the left crank arm 12 are arranged so as to be shifted from each other by 180 °.
In the embodiment of the present invention, it is assumed that the bicycle B moves forward by rotating a pair of crank arms in the direction of the arrow in FIG.

  As shown in FIG. 3, the main body attachment portions 11 a and 12 a are formed in a through hole shape, and the rotation shafts 20 protruding left and right from the main body of the bicycle B are inserted into the main body attachment portions 11 a and 12 a, respectively. In FIG. 3, only the main body attachment portion 12a is shown, and the main body attachment portion 11a is indicated by a broken line, and detailed illustration is omitted. However, since the main body attachment portion 11a and the main body attachment portion 12a have the same structure, Here, the main body attachment portion 12a will be described as an example. The main body attachment portion 12a has a support portion 12c for supporting a part of the tip portion of the rotary shaft 20 described later. The support portion 12c is configured as a wall that partitions a part of the inside of the main body attachment portion 12a, and has a through hole that matches the shape of the distal end side of the rotary shaft 20 in the vicinity of the center thereof.

  As shown in FIG. 3, the pedal attachment portions 11 b and 12 b are formed in a through hole shape, and a female screw groove (not shown) is provided on the surface, and an attachment shaft 13 a that inserts the inside of the pedals 13 and 13 into the female screw groove. A male screw provided at the tip of the screw is screwed together. In this way, the pedals 13 and 13 are pivotally attached to the pedal mounting portions 11b and 12b, respectively.

  Further, as shown in FIG. 3, the right crank arm 11 has a sprocket 21 attached to the base end side via a connecting member (not shown). In addition, this sprocket 21 is connected to the hub of the rear wheel (drive wheel) 30 (see FIG. 1) via a chain (not shown) with the rotational force in the drive direction of the pedals 13 and 13 (the direction in which the bicycle B is advanced). The information is transmitted to a worn freewheel (none of which is shown), and a known one is used as appropriate. Although not shown in detail, the sprocket 21 is a ring-shaped member and has a peripheral surface with a saw blade shape, and a chain (not shown) is stretched around the peripheral surface.

On the other hand, as shown in FIG. 3, the left crank arm 12 has a weight 10 attached to the base end side via an attachment member 15. Here, how to attach the weight 10 to the left crank arm 12 will be described.
As shown in FIG. 3, the attachment member 15 includes a cylindrical portion 15a and a flange portion 15b extending from the base end side of the cylindrical portion 15a toward the radially outer side.
The cylindrical portion 15a has an outer diameter that is substantially the same as or slightly smaller than the diameter of the mounting portion 10b and the diameter of the main body mounting portion 12a of the left crank arm 12. In addition, the cylindrical portion 15a is formed such that the mounting member 15 has an inner diameter larger than the diameter of the distal end side of the rotary shaft 20 and a height larger than the thickness of the mounting portion 10b.

  When the cylindrical portion 15a of the mounting member 15 is inserted from one side of the mounting portion 10b of the weight 10, the flange portion 15b of the mounting member 15 contacts the periphery of the mounting portion 10b in the left crank arm 12, and the cylindrical portion 15a A part of the distal end side protrudes from the other side of the mounting portion 10b. The distal end side of the cylindrical portion 15a protruding from the other side of the mounting portion 10b is inserted into the main body mounting portion 12a of the left crank arm 12 from the bicycle B main body side. Thereby, the weight 10 is clamped by the main body attachment portion 12a of the left crank arm 12 and the flange portion 15b of the attachment member 15. In this way, the weight 10 is attached to the left crank arm 12.

  Here, the weight 10 is arranged such that a line passing through the center (line L passing through the rotation center C) is disposed substantially horizontally, the notch 10a is disposed on the upper side with respect to the center, and the center and the center of gravity position G are on the perpendicular A. , The line connecting the body mounting portion 12a and the pedal mounting portion 12b of the left crank arm 12 moves forward on the bicycle B with respect to a line (perpendicular line A) passing through the center of the weight 10 and the center of gravity G. It is attached to the left crank arm 12 so as to be inclined by 20 ° to 30 ° in the rotating direction. Since the right crank arm 11 and the left crank arm 12 are formed in the same shape and weight, the left crank arm 12 and the right crank arm 11 to which the weight 10 is attached in this way are used as the rotation shaft of the bicycle B main body. If each is attached to the shaft 20, in a static state with no load, the respective bicycles are balanced at positions inclined by 20 ° to 30 ° in the rotational direction in which the bicycle is advanced.

Next, how to attach the left crank arm 12 to which the weight 10 is attached to the rotating shaft 20 will be described. In addition, as for the rotating shaft 20, the front end side has a diameter smaller than the base end side, and the vertical cross-sectional shape is formed in the rectangular shape.
The left crank arm 12 is inserted through the front end side of the rotating shaft 20 in the order of the mounting member 15 and the support portion 12c, with the side on which the mounting member 15 is mounted inside. In this state, the main body attaching portion 12a can be attached to the rotating shaft 20 by fitting the nut 14 matching the shape of the leading end side from the leading end side of the rotating shaft 20 penetrating the support portion 12c. In this way, the left crank arm 12 can be rotatably attached to the rotary shaft 20 integrally with the weight 10.

  As the right crank arm 11 and the left crank arm 12 as described above, for example, a known set of crank arms can be used as appropriate. The weight 10 is attached to the main body attachment portion 12a of the left crank arm 12, but the structure of the main body attachment portion 12a can be changed from the conventional one by using, for example, the attachment member 15 as described above. The weight 10 can be attached. Therefore, a known set of crank arms can be used as they are.

  As described above, when the weight 10 is attached to the left crank arm 12 as described above, the gravity center position G thereof does not coincide with the rotation center C of the pair of crank arms, and the rotation center C It is located on the perpendicular A passing through.

  Specifically, as shown in FIG. 2, the weight 10 has a no-load portion in a static state in which a line passing through the center (common to the line L passing through the rotation center C) is located on the horizontal line, 10a is attached to the left crank arm 12 so that a small weight region is located above the rotation center C and a heavy weight region is located below the rotation center C.

In the static state with no load, the weight 10 has a left crank arm so that the center of gravity G does not coincide with the rotation center C of the pair of crank arms and is positioned on the perpendicular A passing through the rotation center C. 12 is attached to the weight 10, a moment is always applied to the weight 10 so as to move the center of gravity G to the vertical line A passing through the rotation center C. That is, in a static state with no load, the weight 10 always takes the posture shown in FIGS.
In this way, by attaching the weight 10 to the left crank arm 12, the center positions of the right crank arm 11 and the left crank arm 12 are made different from each other so that the center of gravity position is below the rotation center C. In this way, the same state as the so-called “Yajirobe” is created.

In other words, the bicycle crank arm 1 with a weight according to the present invention is applied to the left crank arm 12 to which the weight 10 is attached and the right crank arm 11 in a static state with no load, by applying the “mechanical force of wiping”. in, always place, i.e., against the perpendicular line a, it is obtained as balance in location, by a predetermined angle theta ₁ inclined in the direction of rotation to advance the bicycle B.
Here, the “no load and static state” means that the tire is not grounded and the weight 10, the right crank arm 11 and the left crank arm 12 are all stationary, A state where no load is applied to the right crank arm 11 and the left crank arm 12.

For example, the predetermined angle θ ₁ is preferably 20 ° to 30 ° in the direction in which the bicycle is advanced. This is because when the predetermined angle θ ₁ is less than 20 °, there is almost no difference from a normal bicycle, and the effect of supplementing a part of the pedaling force of the driver cannot be sufficiently obtained, while the predetermined angle θ ₁ is 30 °. This is because the pedal 13 of the left crank arm 12 is in a position where it is difficult to step on, and the burden on the foot becomes excessive. When the predetermined angle θ ₁ 20 ° ~30 °, at the start, with the driver is likely to enter into the pedal 13, since the pedal 13 can be depressed vertically, effectively a depressing force of the driver to the pedal 13 Can communicate and is preferable.

Next, the moment Mo ₁₀ obtained by the weight 10 alone will be described by exemplifying specific dimensions of the weight 10. In general, the moment Mo _α of the rotating body α can be obtained by the following equation [1].

(Equation 1)
Mo _α = W · D (1)

  In Expression [1], “W” is the mass of the rotating body α, and “D” is the distance from the center of rotation of the rotating body α to the position of the center of gravity. And in above-mentioned formula [1], mass W of rotating body alpha can be calculated by the following formula [2].

(Equation 2)
W = r ² π × t × sg (2)

  In Expression [2], “r” is the distance from the center of rotation to the outer peripheral surface of the rotating body α, that is, the radius of the rotating body α, “t” is the thickness of the rotating body α, and “sg "" Is the specific gravity of the material of the rotating body α. Further, π≈3.14.

For example, when the weight 10 as described above is formed of iron (specific gravity = 7.9) and the weight is about 450 g, the dimensions of the weight 10 are, for example, the outer diameter r ₁ is 8.5 cm, the inner diameter is r ₂ can be set to 7.5 cm, and the thickness t can be set to 0.4 cm.

Next, the moment Mo ₁₀ obtained by the weight 10 will be described below with reference to FIG. Here, for convenience, as shown in FIG. 4, when the weight 10 is virtually divided into the ring portion 10R, the center of gravity 10G, and the center 10C, the moment is obtained only in the center of gravity 10G. Conceivable. That is, since the center of gravity G of the ring portion 10R and the center portion 10C is considered to be the center of the weight 10, D = “0” according to the equation [1], and thus the moment becomes “0”. . Accordingly, here, the determining the moment of the gravity center portion 10G as a moment _{Mo 10} of the weight 10.

  The center-of-gravity portion 10G is a portion (a portion surrounded by a thick frame in FIG. 4) obtained by removing a semicircular member having a radius of 2.5 cm concentrically with the semicircular member having a radius of 7.5 cm. is there. Here, the moment of the center of gravity 10G is obtained by subtracting the latter from the former after individually obtaining the moment of the semicircular member having a radius of 7.5 cm and the moment of the semicircular member having a radius of 2.5 cm. I will do it. The center-of-gravity position G of the semicircular member having a radius of 7.5 cm is assumed to be a position that is about 70% away from the center of the weight 10 and closer to the outer peripheral edge side, and therefore it is assumed that the distance D = 5.3. The center-of-gravity position G of the semicircular member having a radius of 2.5 cm is considered to be a position that is closer to the outer peripheral edge side by about 70% from the center of the weight 10, and therefore, it is assumed that the distance D = 1.8 cm. be able to.

Then, according to the equations [1] and [2], the moment of the center of gravity 10G is approximately 1423.4 (g · cm). Therefore, it can be seen that the moment Mo _{10 of the} weight 10 is 1423.4 (g · cm).

Next, how much the pedaling load of the right crank arm 11 increases when the weight 10 that can obtain the moment Mo ₁₀ is attached to the left crank arm 12 when the padding is started. A description will be given by replacing how much the mass of the pedal 13 of the left crank arm 12 increases in a state where the pedal is not attached. Here, a case where a weight 10 is provided on the left crank arm of a general 26-inch bicycle for town will be described as an example.
Here, the pedaling load becomes the largest when the bicycle is driven from a static state with no load. Since the weight 10 is provided on the left crank arm 12, the pedal 13 of the right crank arm 11 is always depressed when starting to row.
Then, by providing the weight 10 on the left crank arm 12, it is considered that the load when the right crank arm 11 is stepped down and the left crank arm 12 is lifted increases.
On the other hand, when the pedal 13 of the left crank arm 12 reaches the rowing position, a force is exerted to return the weight 10 to the balance position by its own weight, that is, the force by which the left crank arm 12 rotates in the driving direction due to gravity. Therefore, the pedaling load will not increase.
Therefore, when the influence on the driver due to the provision of the weight 10 on the left crank arm 12 is taken into consideration, the influence on the pedaling of the right crank arm 11 when the pedaling load is the largest is determined. Is enough.

It is the moment Mo ₁₀ of the weight 10 that directly affects pedaling. As described above, the moment Mo ₁₀ of the weight 10 is approximately 1423.4 (g · cm). On the other hand, the distance from the center of rotation of the pedal 13 of the 26-inch bicycle to the position of the center of gravity corresponds to the distance from the main body mounting portion 12a of the left crank arm 12 to the pedal mounting portion 12b. The distance is approximately 16.5 cm. Here, in order to replace the moment Mo _{10 of the} weight 10 with the increase in pedaling load when the driver pushes the pedal 13 from the state where the pedal 13 of the right crank arm 11 is stationary, the unit time The amount of rotation ω is not considered. Also, the increase in mass of the pedal 13 and _{W pp.} Based on the above, the moment Mo ₁₀ of the weight 10 can be replaced with an increase in the mass of the pedal 13 of the left crank arm 12 by the following equation [3].

(Equation 3)
M _oα = W _pp × 16.5 (3)

  According to the equation [3], the pedaling load of the right crank arm 11 due to the weight 10 provided on the left crank arm 12 is the pedaling load when the weight of the pedal 13 of the left crank arm 12 is increased by approximately 86 g. It turns out that it is equivalent to a load. Here, since the mass of one pedal attached to a general 26-inch bicycle is about 160 g, if 86 g of the increase is added to this, the mass of one pedal is about 246 g. Bicycles with a pedal weight of about 246 g are actually on the market and are within the range that can be easily handled by adults with average physical strength. From the above, it can be said that the increase in pedaling load of the right crank arm 11 due to the weight 10 provided on the left crank arm 12 is not an excessive burden on the driver.

  Further, by setting the weight 10 to about 450 g as described above, when the weight 10 is attached to the left crank arm 12, the weight on the left crank arm 12 side with respect to the bicycle B main body increases by about 450 g. However, since members not provided on the left crank arm 12 side such as a sprocket 21 and a chain (not shown) are arranged on the right crank arm 11 side in the first place, considering the weight, the left and right sides of the bicycle B main body The difference in weight will not be excessive, and the left and right rotation balance will not be impaired. Therefore, even if such a weight 10 is provided, it does not hinder traveling at the normal traveling speed of the bicycle B. Therefore, by attaching the weight 10 to the left crank arm 12, it is possible to effectively obtain the rotational inertia force of the weight 10 itself due to the large moment mass as described above without imposing an excessive burden on the driver. it can.

  Hereinafter, with reference to FIG. 5 and FIG. 2 as appropriate, the operation of a set of crank arms in which the weight 10 according to the embodiment of the present invention is provided on the left crank arm 12 will be described. In FIG. 5, for convenience of explanation, a circle is drawn along the trajectory of the pedals 13 and 13, and the inside of the circle is equally divided into eight blocks.

  As shown in FIG. 5 (a), the weight 10 does not coincide with the center of rotation C (see FIG. 2) of the pair of crank arms and rotates in a static state with no load. The left crank arm 12 is attached to the left crank arm 12 so as to be positioned on a vertical line A (see FIG. 2) passing through the center C. In this state, the right crank arm 11 and the left crank arm 12 are connected to the vertical line A (FIG. 2). For example) at a position inclined by 30 ° in the rotational direction in which the bicycle B (see FIG. 1) moves forward. Here, it is assumed that the pair of crank arms rotates clockwise (in the direction of the arrow in FIG. 2) to advance the bicycle B (see FIG. 1).

The starting position of the pedal 13 attached to the right crank arm 11 is a position advanced by 20 ° to 30 ° in the rotational direction in which the bicycle B is advanced, so that the pedaling force of the driver can be easily transmitted to the pedal 13. Can be smoothly rowed.
When the driver depresses the pedal 13 attached to the right crank arm 11 in this state, a rotational force is gradually generated by the depression force. On the other hand, when the right crank arm 11 rotates downward in the clockwise direction, the left crank arm 12 relatively rotates in the clockwise direction along the circumferential direction by the rotation of the right crank arm 11.

  As shown in FIG. 5B, when the right crank arm 11 rotates between the blocks (2) toward the block (3), the left crank arm 12 relatively moves between the blocks (6). ). Between the blocks (2), the pedal 13 attached to the right crank arm 11 is depressed substantially vertically, so that the depression force can be efficiently transmitted to increase the rotational force.

As shown in FIG. 5 (c), when the driver steps on the pedal 13 attached to the right crank arm 11 and advances between the blocks (3) toward the block (4), the left crank arm 12 is Relatively, the block (7) is rotated toward the block (8).
As between the blocks (3), the pedal 13 attached to the right crank arm 11 is depressed substantially vertically, so that the depression force is efficiently transmitted and the rotational force is increased. Can do.

  As shown in FIGS. 5B and 5C, the pedal 13 attached to the right crank arm 11 is attached to the right crank arm 11 when passing between the blocks (2) and (3). The pedaling force of the pedal 13 is the largest and the rotational force is the largest.

  Subsequently, as shown in FIG. 5 (d), when the driver further steps on the pedal 13 attached to the right crank arm 11 and advances between the blocks (4) toward the block (5), the left crank The arm 12 relatively rotates between the blocks (8) toward the block (1).

When the right crank arm 11 further rotates and the pedal 13 attached to the right crank arm 11 reaches the vicinity of the position a in FIG. 5 (e), the pedal 13 starts to kick slightly rearward. It becomes difficult for a person to input to the pedal 13, and the rotational force is attenuated.
Instead, the driver inputs to the pedal 13 of the right crank arm 11 at each stage of FIG. 5 (a) to FIG. 5 (d), particularly at the stage of FIG. 5 (b) to FIG. 5 (d). Due to the obtained rotational inertia force and the rotational inertia force of the weight 10 obtained by rotating the weight 10 in the driving direction together with the left crank arm 12, the left crank arm 12 is shown in FIG. Rotation from the position 'to the vicinity of the position c' causes the right crank arm 11 to relatively rotate from the position a to the vicinity of the position c.
In this way, it is possible to eliminate a position where it is difficult for the driver to input to the pedal 13.

  Then, when the pedal 13 attached to the left crank arm 12 is depressed from near the position c ′ in FIG. 5 (e), a rotational force is generated by the depression force, and FIG. 5 (f), FIG. 5 (g), FIG. As shown in h), the left crank arm 12 rotates in the rotational direction for moving the bicycle B forward, and the right crank arm 11 relatively rotates in the rotational direction for moving the bicycle B forward.

  At this time, as shown in FIG. 5 (e), when the left crank arm 12 is in the c ′ position, the center of gravity position G (see FIG. 2) of the weight 10 is in the region (1). Due to its own weight, it tries to return to the balanced position (see FIG. 5A) and rotates in the driving direction. In conjunction with this rotation, the left crank arm 12 rotates in the driving direction. As described above, the left crank arm 12 is rotated in the driving direction by using the rotational force generated by the weight 10 trying to return to the balanced position in addition to the rotational force obtained by the driver inputting to the pedal 13. Therefore, a part of the driver's pedaling force can be effectively compensated.

In this manner, as shown in FIG. 5A again, when the left crank arm 12 reaches the rowing position, the state in which the left crank arm 12 becomes the resistance of the right crank arm 11 is canceled.
Then, the weight 10 and the left crank arm 12 return to the balanced position, and the right crank arm 11 returns to the balanced position, that is, reaches the starting position, so that the driver can start again smoothly. Can do. As described above, when the right crank arm 11 returns to the balance position, it reaches the rowing position, so that 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 for the driver to transmit the pedaling force to the pedal 13 can be passed by inertial force, a decrease in driving force when the pedal 13 is rotated once can be suppressed.

According to the crank crank arm 1 with a weight described above, the following operational effects can be obtained.
According to the bicycle crank arm 1 with a weight, in a static state with no load, a set of crank arms balances with respect to the perpendicular A at a position inclined by a predetermined angle in the rotational direction in which the bicycle B is advanced, In particular, it is possible to eliminate a position where it is difficult for the driver to input to the pedal 13 at the time of starting or when traveling at a low speed on an uphill.

  Further, according to the bicycle crank arm 1 with the weight, by transmitting the rotational inertia force of the weight 10 itself obtained by the weight 10 rotating with the rotation of the left crank arm 12 to the left crank arm 12, The rotational inertia force of a set of crank arms can be assisted. Here, since the weight 10 is a substantially disk-shaped member, the rotation balance is good, and the rotation inertia force can be obtained more effectively.

  More specifically, objects on the real earth are governed by two laws: gravity and inertia. In order to correspond to these two laws, the weight 10 alone realizes a balance such that the pedal 13 of the right crank arm 11 naturally comes to an ideal position at the time of rowing, while the weight 10 itself However, the shape is selected so that the flywheel effect can be obtained, and the design is such that the rotation of one set of crank arms is easily sustained. In other words, by making the weight 10 a substantially disk-shaped member, the rotation balance becomes good and it is possible to make it less susceptible to the influence of gravity during rotation, so that a force that keeps rotating (rotational inertial force) can be effectively obtained. Can do. Then, by transmitting the rotational inertia force of the weight 10 itself to the left crank arm 12, the rotational inertia force of the left crank arm 12 can be assisted, and as a result, the rotational inertia force of a set of crank arms can be assisted. Can do it.

  As shown in FIGS. 1 and 3, the state in which the weight 10 is attached to the base end side of the left crank arm 12 is similar in appearance to the state in which the sprocket 21 is attached to the base end side of the right crank arm 11. It is possible to make it difficult to produce an uncomfortable appearance due to the weight 10 being attached to the left crank arm 12. Further, since the weight 10 can be uniquely determined in accordance with the material forming the weight 10 and the required moment, the weight 10 can be easily manufactured and the manufacturing cost can be reduced. Further, since the weight 10 is not on the flow line when the driver raises and lowers his / her foot on the pedal 13, the foot can be smoothly raised and lowered when the driver gets on and off the bicycle B or pauses. .

As described above, the bicycle crank arm 1 with a weight according to the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and may be appropriately changed without departing from the gist of the present invention. Is possible. For example, the weight 10 may have an outer peripheral surface formed in an arc shape in sectional view. According to this, since the air resistance of the weight 10 can be reduced, the rotation balance of the weight 10 can be made better. As a result, the rotational inertia force in the driving direction of the weight 10 can be obtained more effectively.
In the above-described embodiment, the weight 10 is configured as a substantially disk-like member with an emphasis on rotational balance. However, the present invention is not limited to this, and the gravity center position G rotates in a static state with no load. The shape is not limited as long as it can be positioned below the center C. For example, the weight 10 may be a semicircular member, or the weight 10 may be formed in a rectangular shape or a rhombus, and a notch may be provided above the center. In the embodiment described above, the dimensions of the weight 10 are set in consideration of effectively obtaining the rotational inertia force by the weight 10 and the balance in appearance with the sprocket 21 attached to the right crank arm 11. For example, the diameter may be reduced to increase the thickness.
Furthermore, although the weight 10 has been described as a component of the bicycle crank arm 1 with a weight in the above-described embodiment, the present invention is not limited to this, and it is a matter of course that the weight 10 alone may be distributed. According to this, it is possible to easily ride an existing bicycle by attaching the weight 10 to the existing bicycle.

1 Crank arm for bicycle with weight 10 Weight (weight for crank arm mounting)
10a mounting portion 10b notch portion 11 right crank arm 11a main body mounting portion 11b pedal mounting portion 12 left crank arm 12a main body mounting portion 13 pedal 13a mounting shaft 20 rotating shaft 21 sprocket 30 driving wheel B bicycle

Claims (5)

A pair of crank arms that are pivotally mounted with the bicycle body sandwiched therebetween and that are respectively attached to the distal end by shifting the position by 180 °, and the base end of one crank arm in the pair of crank arms A bicycle crank arm with a weight having a weight attached to the side to rotate with the rotation of the one crank arm,
In a static state with no load, the weight has a center of gravity located below the center of rotation on a perpendicular passing through the center of rotation of the set of crank arms,
The pair of crank arms are balanced at a position inclined at a predetermined angle with respect to the vertical direction in a rotational direction for advancing the bicycle in a static state with no load, respectively. .   2. The weight according to claim 1, wherein the weight is a substantially disk-shaped member, and is formed such that one region and the other region have a weight difference when divided into two by a line passing through the center thereof. Bicycle crank arm with the described weight.   The bicycle crank arm with a weight according to claim 2, wherein the weight includes a notch portion in which a part of a surface thereof is notched in either the one region or the other region. .   The bicycle crank arm with a weight according to claim 2 or 3, wherein the weight has an outer peripheral edge formed in an arc shape in a sectional view. This one crank arm on the base end side of one crank arm in a set of crank arms that are pivotally mounted with the bicycle body interposed therebetween and are shifted 180 ° from each other on the distal end side. A crank arm mounting weight that is mounted to rotate with rotation of
The crank arm mounting weight is formed so that one region and the other region having a weight difference when divided by a line passing through the center thereof have a weight difference. Is located below the center of rotation of the set of crank arms and on a vertical line passing through the center of rotation of the set of crank arms, and a line passing through the center and the position of the center of gravity. For mounting a crank arm, wherein the crank arm is attached to the base end portion of the one crank arm so as to be inclined at a predetermined angle with respect to a line connecting the base end portion and the tip end portion of the one crank arm. Weight.

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