JP2022170319A - Connection member, bicycle, and electric-assisted bicycle - Google Patents

Abstract

To provide a light-weight connection member for connecting a crank to a chain wheel capable of rotating on an axis of rotation in a circumferential direction.SOLUTION: A coupling member comprises a body part, a plurality of arm parts, and a first recessed part. The body part is in an annular shape surrounding a center axis extending in an axial direction. The arm parts extend at least radially outward from the body part when viewed from the axial direction. The first recessed part is arranged on an axial end face of at least one of the body part and the arm parts, and recessed in the axial direction. The arm part is asymmetrical about an axis of symmetry when viewed from the axial direction.SELECTED DRAWING: Figure 3

Description

TECHNICAL FIELD The present invention relates to a connecting member, a bicycle, and a power-assisted bicycle.

2. Description of the Related Art Conventionally, a bicycle is known in which a crank is connected to a chainwheel using a connecting member called a spider arm. The spider arm, chainwheel, and crank may also be referred to as chainring, spider, and crankarm, respectively. For example, the spider has a plurality of spider arms that connect to the chainrings, a central portion from which the spider arms protrude, and a connecting hole in the center of the central portion. A connection member of the crank arm is inserted into the connection hole (see EP 3392129).

EP-A-3392129

The spider arm rotates with the chainwheel. Therefore, in order to reduce the burden on the person who uses the bicycle, the spider arm is required to be lightweight.

An object of the present invention is to reduce the weight of a connecting member for connecting a crank to a chain wheel.

An exemplary connecting member of the present invention is a member for connecting a crank to a chain wheel that is circumferentially rotatable about a central axis. The connecting member includes a body, a plurality of arms, and a first recess. The body has an annular shape surrounding the axially extending central axis. The arm portion extends at least radially outwardly from the body portion when viewed in the axial direction. The first concave portion is arranged on an axial end face of at least one of the body portion and the arm portion and is axially concave. The first direction is the direction in which the arm extends. The second direction is a direction perpendicular to the first direction and the axial direction. An axis of symmetry extends in the first direction through the center of the arm in the second direction. When viewed from the axial direction, the arm portion has a shape that is asymmetric with respect to the axis of symmetry.

An exemplary bicycle of the present invention comprises the connecting member described above, a chainwheel and a crank. The chain wheel is rotatable in one circumferential direction around the central axis. The crank is connected to the chain wheel by the connecting member.

An exemplary power-assisted bicycle of the present invention includes the connecting member described above, a chain wheel, a crank, a driving device, and a power supply section. The chain wheel is rotatable in one circumferential direction around the central axis. The crank is connected to the chain wheel by the connecting member. The drive provides torque to the chainwheel. The power supply supplies power to the driving device.

According to the exemplary connecting member, bicycle, and power-assisted bicycle of the present invention, the weight of the connecting member for connecting the crank to the chain wheel can be reduced.

FIG. 1 is a schematic diagram of a bicycle. FIG. 2 is a perspective exploded view showing the connecting structure between the bicycle crank and chainwheel. FIG. 3 is a perspective view showing a configuration example of one axial end of the connecting member. FIG. 4 is a perspective view showing a configuration example of the other end in the axial direction of the connecting member. FIG. 5A is a plan view of an arm portion according to the embodiment; FIG. 5B is a plan view of an arm portion according to the first modification; FIG. 6A is a side view of an arm portion according to the embodiment; FIG. 6B is a side view of an arm portion according to a second modification;

Exemplary embodiments are described below with reference to the drawings.

In this specification, the direction parallel to the central axis Ac of the connecting member 1 of the bicycle 100 is referred to as "axial direction Da". One of the axial directions Da is called "one axial direction Da1", and the other direction is called "other axial direction Da2". In each component, the end on the one axial Da1 side is referred to as "one axial end", and the end on the other Da2 side in the axial direction is referred to as "other axial end". Further, in the surface of each constituent element, the surface facing the one axial direction Da1 is called the "one axial end surface", and the surface facing the other axial direction Da2 is called the "other axial end surface".

A direction orthogonal to the central axis Ac is called a "radial direction". Among the radial directions, the direction toward the central axis Ac is called "radially inward", and the direction away from the central axis Ac is called "radial outward". In each component, the radially inner end is referred to as a "radial inner end" and the radially outer end is referred to as a "radial outer end". In addition, among the side surfaces of each component, the side surface facing radially inward is referred to as the "radial inner surface", and the side surface facing radially outward is referred to as the "radial outer surface".

Further, the direction of rotation about the central axis Ac is called "circumferential direction Dr". One direction of the circumferential direction Dr is called "one circumferential direction Dr1", and the other direction is called "the other circumferential direction Dr2". In the following description, one circumferential direction Dr1 is the front side of the bicycle 100 in the direction in which the chain wheel 1034 and the connecting member 1 rotate. The other circumferential direction Dr2 is behind in this rotating direction. In each component, an end in the circumferential direction Dr is called a "circumferential end". Further, among the circumferential direction end portions, the end portion on the one circumferential direction Dr1 side is called the "circumferential direction one end portion", and the end portion on the circumferential direction other Dr2 side is called the "circumferential direction other end portion".

In addition, in terms of the positional relationship between any one of azimuth, line, and plane and any other, "parallel" means not only a state in which they do not intersect at all no matter how far they are extended, but also a state in which they are substantially parallel. include. In addition, "perpendicular" includes not only the state in which the two intersect each other at 90 degrees, but also the state in which they are substantially perpendicular. In other words, "parallel" and "perpendicular" each include a state in which there is an angular deviation in the positional relationship between the two without departing from the gist of the present invention.

Note that these names are merely used for explanation, and are not intended to limit actual positional relationships, directions, names, and the like.

<1. Bicycle 100>
FIG. 1 is a schematic diagram of a bicycle 100. As shown in FIG. FIG. 2 is a perspective exploded view showing the connection structure between the crank 1031 and the chain wheel 1034 of the bicycle 100. FIG.

As shown in FIG. 1, the bicycle 100 has a vehicle body 101, two wheels 102, a power transmission mechanism 103, a driving device 104, and a power supply section 105.

Body 101 includes a handle 1011 and a saddle 1012 . Two wheels 102 , power transmission mechanism 103 , driving device 104 and power supply section 105 are attached to vehicle body 101 . The two wheels 102 have a front wheel 102f and a rear wheel 102r. The front wheels 102 f are attached to the front portion of the vehicle body 101 , and the rear wheels 102 r are attached to the rear portion of the vehicle body 101 . A power transmission mechanism 103 is connected to the rear wheel 102r.

The power transmission mechanism 103 includes a radially extending crank 1031, a crankshaft 1032 extending in the axial direction Da along the central axis Ac, a pedal 1033, an annular chain wheel 1034 centered on the central axis Ac, and a chain wheel. a connecting member 1 attached to 1034; A pedal 1033 is connected to a radially outer end of the crank 1031 so as to be rotatable about an axis Ar extending in the axial direction Da.

The connecting member 1 is a so-called spider arm, and arm portions 3, which will be described later, radially extend side by side in the circumferential direction Dr. The connecting member 1 is a member for connecting the crank 1031 to the chain wheel 1034 rotatable about the central axis Ac in the circumferential direction Dr. In this embodiment, when the bicycle 100 moves forward, the chain wheel 1034 rotates in one circumferential direction Dr1. As shown in FIG. 2 , one axial end of crankshaft 1032 is fixed to connecting member 1 . The other axial end of crankshaft 1032 is attached to the radially inner end of crank 1031 so as to be rotatable about central axis Ac. In other words, the crank 1031 is connected to the chain wheel 1034 via the crankshaft 1032 and the connecting member 1 .

The power transmission mechanism 103 further has a driven gear (not shown) and a chain (not shown). The driven gear is attached to the rear wheel 102r. The chain transmits the torque of the chainwheel 1034 to the driven gear.

The driving device 104 is attached to the power transmission mechanism 103 . The driving device 104 has an output section (not shown) that transmits torque to the power transmission mechanism 103 . One axial end of the crankshaft 1032 is connected to this output portion. Torque output from the driving device 104 is transmitted to the chain wheel 1034 via the crankshaft 1032 and the connecting member 1 .

The power supply unit 105 is attached to the vehicle body 101 . The power supply unit 105 is a chargeable/dischargeable battery and supplies electric power to the driving device 104 .

In bicycle 100, when a user seated on saddle 1012 steps on pedal 1033, crank 1031 rotates about central axis Ac. Torque around the central axis Ac generated at this time is transmitted to the chain wheel 1034 via the crankshaft 1032 and the connecting member 1 . The chain wheel 1034 rotates in the circumferential direction Dr by the transmitted torque. Torque is transmitted from the chain wheel 1034 to the rear wheel 102r via the chain to rotate the rear wheel 102r.

In addition, the torque generated by drive 104 is also transmitted to chain wheel 1034 . The drive device 104 has a sensor (not shown) that detects the torque applied to the crankshaft 1032 and applies torque to the chain wheel 1034 from the output section as needed. The torque transmitted from the output section is added to the torque for running the bicycle 100 . That is, the driving device 104 assists the torque necessary for running the bicycle 100 as necessary.

In this embodiment, the bicycle 100 is a power-assisted bicycle that assists the force of stepping on the pedals 1033 of the user. However, the bicycle 100 is not limited to the example of this embodiment, and may not be a power-assisted bicycle. That is, in the bicycle 100, the driving device 104 and the power supply section 105 may be omitted.

As described above, bicycle 100 includes connecting member 1 , chain wheel 1034 and crank 1031 . The chain wheel 1034 is rotatable in the circumferential direction Dr about the central axis Ac. Crank 1031 is connected to chain wheel 1034 by connecting member 1 .

Bicycle 100 further includes drive device 104 and power supply unit 105 . Drive 104 provides torque to chain wheel 1034 . The power supply unit 105 supplies power to the driving device 104 . The bicycle 100 is also an example of the "electrically assisted bicycle" of the present invention.

According to the bicycle 100 of this embodiment, the first concave portion 4, which will be described later, is arranged in the connecting member 1, thereby connecting the crank 1031 and the chain wheel 1034 of the bicycle 100 (electrically assisted bicycle in this embodiment). The weight of the member 1 can be reduced.

<2. Connection member 1>
Next, the configuration of the connecting member 1 will be described with reference to FIGS. 3 to 6B. FIG. 3 is a perspective view showing a configuration example of one axial end of the connecting member 1. As shown in FIG. FIG. 4 is a perspective view showing a configuration example of the other end in the axial direction of the connecting member 1. As shown in FIG. FIG. 5A is a plan view of the arm section 3 according to the embodiment. FIG. 5B is a plan view of the arm portion 3 according to the first modified example. FIG. 6A is a side view of the arm section 3 according to the embodiment. FIG. 6B is a side view of the arm portion 3 according to the second modified example. 3, the connecting member 1 is viewed from the one Da1 side in the axial direction. 4, the connecting member 1 is viewed from the other Da2 side in the axial direction. 5A and 5B are views of the arm portion 3 from the other Da2 side in the axial direction. 6A and 6B are looking at the arm part 3 from the second direction D2.

The connecting member 1 includes a body portion 2 , a plurality of arm portions 3 and a first recessed portion 4 . In addition, the connecting member 1 further includes a cylindrical portion 5 and preferably further includes ribs 6 . The cylindrical portion 5 and ribs 6 will be described later.

The body portion 2 has an annular shape surrounding a central axis Ac extending in the axial direction Da and spreads in the radial direction.

A plurality of arm portions 3 are arranged in the circumferential direction Dr. A plurality of arm portions 3 extend radially from the body portion 2 . The arm portion 3 extends at least radially outward from the body portion 2 when viewed in the axial direction Da. For example, in the present embodiment, the arm portion 3 extends radially outward and in one circumferential direction Dr1 when viewed from the axial direction Da. However, it is not limited to this example, and the arm portion 3 may extend radially outward when viewed from the axial direction Da, or may extend radially outward and in the other circumferential direction Dr2 when viewed from the axial direction Da. good.

When viewed from the axial direction Da, the arm portion 3 has a non-symmetrical shape with respect to the axis of symmetry As (see FIG. 3 and FIG. 5A described later). Note that the axis of symmetry As extends in the first direction D1 through the center of the arm portion 3 in the second direction D2. The first direction D1 is the direction in which the arm portion 3 extends, and the second direction D2 is the direction perpendicular to the first direction D1 and the axial direction Da. For example, when viewed from the axial direction Da, the arm portion 3 inclines in the one circumferential direction Dr1 as it goes radially outward. Therefore, the shape of the arm portion 3 on the one circumferential direction Dr1 side is different from the shape of the arm portion 3 on the circumferential direction other Dr2 side. Moreover, the shape of the one circumferential end portion of the arm portion 3 is different from the shape of the other circumferential end portion of the arm portion 3 .

The first recessed portion 4 is arranged on the axial end surface of at least one of the body portion 2 and the arm portion 3 and is recessed in the axial direction Da. For example, at least part of the first recess 4 is arranged on the axial end surface of the body portion 2 . At least part of the first concave portion 4 is arranged on the axial end surface of the arm portion 3 . That is, the first concave portion 4 may be arranged only on one of the axial end face of the body portion 2 and the axial end face of the arm portion 3 , or may be arranged on only one of the axial end face of the body portion 2 and the axial end face of the arm portion 3 . It may be arranged on both end faces. In the present embodiment, the first concave portion 4 is arranged from the body portion 2 to the arm portion 3 only on one axial end face of the connecting member 1 (see FIG. 3 and the like). However, the arrangement of the first recesses 4 is not limited to the example in this embodiment. The first concave portion 4 may be arranged only on the other axial end surface of the connecting member 1 or may be arranged on both the one axial end surface and the other axial end surface of the connecting member 1 . Also, the first concave portion 4 may be arranged in only one of the body portion 2 and the arm portion 3 .

By arranging the first recessed portion 4 recessed in the axial direction Da on the axial end surface of at least one of the body portion 2 and the arm portion 3, the connecting member 1 can be hollowed out. Furthermore, by making the arm portion 3 have an asymmetrical shape, for example, a portion of the outer edge portion of the arm portion 3 viewed in the axial direction Da that is less stressed when the chain wheel 1034 is rotated is removed. can do. Therefore, it is possible to reduce the weight of the connecting member 1 while maintaining the rigidity of the connecting member 1 for connecting the crank 1031 to the chain wheel 1034 .

In the present embodiment, the length of the one circumferential end portion of the arm portion 3 is shorter than the length of the other circumferential end portion of the arm portion 3 when viewed from the axial direction Da. Specifically, the length of the one circumferential end of the arm portion 3 is the length along the outer edge of the one circumferential end of the arm portion 3 as viewed in the axial direction Da. The length of the other circumferential end of the arm portion 3 is the length along the outer edge of the other circumferential end of the arm portion 3 as viewed in the axial direction Da. In this way, the other end in the circumferential direction of the arm portion 3 can be made longer. By increasing the length of the other end in the circumferential direction of arm portion 3 , the stress acting on the other end in the circumferential direction of arm portion 3 when force is applied to connecting member 1 can be dispersed. Therefore, the strength of the arm portion 3 can be improved.

Preferably, when viewed from the axial direction Da, the first interval S1 between the one circumferential end of the arm portion 3 and the one circumferential end of the first recess 4 is the first distance between the other circumferential end of the arm portion 3 and the first recessed portion 4 . It is wider than the second interval S2 between the recess 4 and the other end in the circumferential direction (see FIG. 3). By doing so, the first interval S1 can be made wider, so that the rigidity of the one circumferential end portion of the arm portion 3 can be improved. However, this illustration does not exclude a configuration in which S1≦S2 when viewed from the axial direction Da in at least one arm portion 3 .

More preferably, when viewed from the axial direction Da, the first spacing S1 widens radially inward. When the chain wheel 1034 rotates, the force acting on the one circumferential end of the arm portion 3 increases radially inward. Therefore, increasing the first spacing S1 inward in the radial direction can suppress an increase in the acting stress. Therefore, the rigidity of the one end portion in the circumferential direction of the arm portion 3 can be improved. However, this illustration does not exclude a configuration in which at least one arm portion 3 has the first spacing S1 narrower or constant as viewed from the axial direction Da toward the radially inward direction.

In this embodiment, as shown in FIG. 6A, the first width d1 of the arm portion 3 in the axial direction Da is wider than the second width d2 of the body portion 2 in the axial direction Da. By setting d1>d2, the thickness of the arm portion 3 in the axial direction Da (that is, the first width d1) can be increased. Therefore, the strength of the arm portion 3 can be improved.

However, it is not limited to the example of this embodiment, and in at least one arm portion 3, the second width d2 in the axial direction Da of the body portion 2 is the second width It may be wider than one width d1. By setting d1<d2, the thickness of the body portion 2 in the axial direction Da (that is, the second width d2) can be increased. Therefore, the strength of the body portion 2 can be improved.

The illustration of FIGS. 6A and 6B does not exclude a configuration in which d1=d2 in at least one arm portion 3. FIG.

<2-1. arm portion 3>
Next, the arm portion 3 has an arm base portion 31 and a fixing portion 32 .

The arm base 31 extends in the first direction D1 when viewed from the axial direction Da. Specifically, the arm base portion 31 extends at least radially outward from the body portion 2 when viewed in the axial direction Da. For example, in the present embodiment, the arm base 31 extends radially outward and in one circumferential direction Dr1 when viewed from the axial direction Da. However, the arm base portion 31 is not limited to this example, and the arm base portion 31 may extend radially outward when viewed from the axial direction Da, or may extend radially outward and in the other circumferential direction Dr2 when viewed from the axial direction Da. good.

The fixed portion 32 extends in the first direction D1 from the radially outer end portion of the arm base portion 31 and can be fixed to the chain wheel 1034 (see FIG. 2). In this embodiment, the fixed portion 32 is plate-shaped and is screwed to the chain wheel 1034 using bolts (not shown). Specifically, the fixed portion 32 has a hole portion 32a. The hole portion 32a penetrates the fixed portion 32 in the axial direction Da. The bolts described above are inserted through the holes 32 a and screwed into the threaded holes 1034 a of the chain wheel 1034 . However, the means for fixing the fixing portion 32 to the chain wheel 1034 is not limited to this example. For example, the fixing means described above may be brazing using brazing material, welding, or the like.

Preferably, when viewed from the axial direction Da, a third space S3 between the radially outer end of the hole portion 32a and the radially outer end of the fixing portion 32 is equal to the radially inner end of the hole portion 32a and the first concave portion. 4 (see FIG. 3). By setting S3<S4, the third space S3 can be made shorter, and the radially outer end portion of the fixing portion 32 can be disposed further radially inward. Therefore, since the radial size of the fixing portion 32 can be made smaller, the radial size of the connecting member 1 can be made smaller, and the weight of the connecting member 1 can be reduced. However, this illustration does not exclude configurations where S3≧S4.

Moreover, preferably, the arm portion 3 further has a stepped portion 33 . The stepped portion 33 is arranged between the arm base portion 31 and the fixed portion 32 (see FIG. 4 and the like). The stepped portion 33 has a connection surface 33a. The connecting surface 33a connects the radially outer end portion of the one axial end surface of the arm base portion 31 and the radially inner end portion of the one axial end surface of the fixed portion 32 . The radially outer end portion of the one axial end surface of the arm base portion 31 is arranged at one axial direction Da1 relative to the radially inner end portion of the one axial end surface of the fixing portion 32 .

For example, in this embodiment, the connection surface 33a extends in the axial direction Da. However, the connection surface 33a may extend in a direction intersecting with the axial direction Da, without being limited to the illustration of the present embodiment. In other words, the connection surface 33a may extend in the axial direction Da or in a direction intersecting the axial direction Da.

Due to the arrangement of the stepped portion 33 , when the connecting member 1 is fixed to the chain wheel 1034 , the stepped portion 33 can determine the mounting position of the chain wheel 1034 in the radial direction. Therefore, it becomes easier to attach the connecting member 1 to the chain wheel 1034 .

Preferably, when viewed from the axial direction Da, at least a region of the connecting surface 33a on the side of the other circumferential direction Dr2 extends radially inward toward the other circumferential direction Dr2. In this way, the chamfered portion 33b can be formed at least in the portion of the stepped portion 33 on the other side Dr2 in the circumferential direction. In other words, the chamfered portion 33b is formed at least at a portion of the radially outer end portion of the arm base portion 31 on the side of the other side Dr2 in the circumferential direction. Specifically, at the corner between the connection surface 33a and the other end surface in the circumferential direction of the arm base 31, so-called round chamfering can be applied to form a curved surface therebetween. Therefore, when the chain wheel 1034 to which the connecting member 1 is connected rotates, the stress acting on the other circumferential end of the stepped portion 33 (in other words, the other circumferential end of the arm base 31 at the radially outer end) is It prevents you from concentrating. That is, the above stress can be dispersed by the chamfered portion 33b. Therefore, the strength of the arm portion 3 can be improved, and particularly the strength between the arm base portion 31 and the fixing portion 32 can be improved. However, this illustration does not exclude a configuration in which at least one arm portion 3 is not formed with the chamfered portion 33b. That is, the chamfered portion 33b may be omitted. For example, in at least one arm portion 3, when viewed from the axial direction Da, the region of the connection surface 33a at least on the side of the other circumferential direction Dr2 does not need to extend radially inward toward the other circumferential direction Dr2.

Note that the example of the present embodiment does not exclude a configuration in which at least one arm portion 3 does not have the stepped portion 33 . That is, in at least one arm portion 3, the step portion 33 and the connection surface 33a may be omitted. For example, the radially outer end portion of the one axial end surface of the arm base portion 31 may be directly connected to the radially inner end portion of the one axial end surface of the fixed portion 32 .

Next, in this embodiment, the arm portion 3 further has a second concave portion 34 . The second recessed portion 34 is arranged at one circumferential end portion of the arm portion 3 and is recessed in the other circumferential direction Dr2. That is, the second recess 34 is arranged at the circumferential end of the chain wheel 1034 and the connecting member 1 on the rotational direction side of the arm portion 3 . By providing the second concave portion 34 at the one circumferential end of the arm portion 3 where the action of stress is small, the strength of the one circumferential end of the arm portion 3 is suppressed, and the thickness of the arm portion 3 is reduced. The weight of the connecting member 1 can be further reduced.

Preferably, in the two arm portions 3 adjacent in the circumferential direction, the radial inner end portion of the second concave portion 34 in the arm portion 3 on the side of the other circumferential Dr2 is the radial outer end portion of the body portion 2 and the circumferential It is gently connected to one of the other ends in the circumferential direction of the arm portion 3 on the one Dr1 side (see FIGS. 3 and 4, etc.). For example, in the portion where the radially inner end portion of the second recessed portion 34 is connected to the radially outer end portion of the body portion 2 , the tangential direction of the one circumferential end portion of the arm portion 3 viewed from the axial direction Da is the body portion 2 is parallel to the tangential direction seen from the axial direction Da of the radially outer end of the . Alternatively, the radially inner end portion of the second concave portion 34 arranged at the one circumferential end portion of the arm portion 3 on the other circumferential Dr2 side is connected to the other circumferential end portion of the arm portion 3 on the circumferential one Dr1 side. , the tangential direction seen from the axial direction Da of the one circumferential end of the arm portion 3 on the other circumferential Dr2 side is the axial direction Da of the other circumferential end of the arm portion 3 on the one Dr1 side in the circumferential direction. parallel to the tangential direction. In this way, the connecting portion between the radial inner end of the second recess 34, the radial outer end of the body portion 2, and the other circumferential end of the arm portion 3 on the circumferential one Dr1 side. no angle is formed. Therefore, stress can be prevented from concentrating on this connection portion. Therefore, the strength of this connecting portion can be improved. However, this illustration does not exclude a configuration in which the two are not smoothly connected at the connection portion described above.

In addition, in the present embodiment, as shown in FIG. 3 , the fifth interval S5 between the one circumferential end portion and the other circumferential end portion of the arm portion 3 is the same as the radial outer end portion of the first concave portion 4 . Widest in position. With this configuration, even if the arm portion 3 is hollowed out by, for example, arranging the second recess 34 at a radial position radially inward of the radially outer end portion of the first recess 4 , the diameter of the fixing portion 32 remains unchanged. A decrease in strength on the direction inner side can be suppressed. Since the connecting member 1 is connected to the chain wheel 1034 at the fixing portion 32 , maintaining the strength of the fixing portion 32 can also maintain the strength of the connection between the connecting member 1 and the chain wheel 1034 . Therefore, it is possible to reduce the weight of the connecting member 1 while firmly connecting the connecting member 1 to the chain wheel 1034 .

Further, in the present embodiment, as shown in FIG. 3 , at the same radial position as the radial outer end of the first recess 4 , the one circumferential end of the arm portion 3 is arranged closest to the one Dr1 in the circumferential direction. With this configuration, even if the arm portion 3 is hollowed out by, for example, arranging the second recess 34 at a radial position radially inward of the radially outer end portion of the first recess 4 , the diameter of the fixing portion 32 remains unchanged. A decrease in strength on the direction inner side can be suppressed. Since the connecting member 1 is connected to the chain wheel 1034 at the fixing portion 32 , maintaining the strength of the fixing portion 32 can also maintain the strength of the connection between the connecting member 1 and the chain wheel 1034 . Therefore, it is possible to reduce the weight of the connecting member 1 while firmly connecting the connecting member 1 to the chain wheel 1034 .

In addition, the configuration is not limited to the example of the present embodiment, and at least one arm portion 3 may have a configuration in which the second concave portion 34 is not provided. That is, the second recess 34 may be omitted in at least one arm portion 3 . Also, the illustration of this embodiment does not exclude a configuration in which the fifth spacing S5 is not widest at the same radial position as the radially outer end of the first recess 4 in at least one arm portion 3 . Furthermore, in the example of the present embodiment, in at least one arm portion 3, one circumferential end portion of the arm portion 3 is arranged closest to the one Dr1 in the circumferential direction at the same radial position as the radial outer end portion of the first concave portion 4. It does not exclude configurations that are not For example, as shown in FIG. 5B, in at least one arm portion 3, the width of the arm base portion 31 in the second direction D2 may increase radially inward. By doing so, the strength of the arm portion 3 can be improved.

<2-2. Cylindrical portion 5>
The cylindrical portion 5 extends in the axial direction Da from the radially inner end portion of the body portion 2 . As described above, the connecting member 1 has the tubular portion 5 . For example, in the present embodiment, the cylindrical portion 5 extends from the radial inner end portion of the body portion 2 in both the one axial direction Da1 and the other axial direction Da2. However, the tubular portion 5 may extend only in the one axial direction Da1 from the radially inner end portion of the body portion 2 without being limited to the illustration of the present embodiment. Alternatively, the tubular portion 5 may extend only from the radially inner end portion of the body portion 2 toward the other axial direction Da2. The cylindrical portion 5 can improve the rigidity of the radially inner end portion of the body portion 2 . A crankshaft 1032 is inserted through and fixed to the radially inner end portion of the body portion 2 . For example, the crankshaft 1032 is spline-fitted to the tubular portion 5 . By arranging the cylindrical portion 5 at the radially inner end portion of the body portion 2, the contact area between the inner surface of the cylindrical portion 5 and the crankshaft 1032 can be increased. Therefore, the accuracy of fixing the crankshaft 1032 to the connecting member 1 can be improved.

Preferably, when viewed from the axial direction Da, the first concave portion 4 is in contact with the radial outer surface of the cylindrical portion 5 (see FIG. 3). In this way, the first concave portion 4 can be made wider, so that the lightening portion of the connecting member 1 can be made larger. Therefore, the weight of the connecting member 1 can be further reduced. However, the exemplification of the present embodiment does not exclude the configuration in which the first concave portion 4 is arranged away from the radial outer surface of the cylindrical portion 5 when viewed from the axial direction Da.

<2-3. Rib 6>
The rib 6 connects the tubular portion 5 and one of the outer edge portion of the body portion 2 and the outer edge portion of the arm portion 3 when viewed in the axial direction Da. In this embodiment, as described above, the connecting member 1 further includes ribs. When viewed from the axial direction Da, the rib 6 is in contact with the first recess 4 in the circumferential direction Dr. Due to the arrangement of the ribs 6, when the chain wheel 1034 rotates, the ribs 6 are reinforced even if stress acts on the body part 2, particularly the part of the body part 2 where the part of the first recess 4 is arranged. The effect makes it difficult to transform. Therefore, the rigidity of the body portion 2 can be improved. In addition, the illustration of this embodiment does not exclude the structure in which the connecting member 1 does not have the rib 6 . That is, the rib 6 may be omitted.

In this embodiment, the number of ribs 6 is the same as the number of arms 3 . However, the number of ribs 6 is not limited to the example of the present embodiment, and the number of ribs 6 may be singular or plural different from the number of arms 3 .

<3. Others>
The embodiments of the present invention have been described above. It should be noted that the scope of the present invention is not limited to the above-described embodiments. The present invention can be implemented by adding various modifications to the above-described embodiments without departing from the gist of the invention. In addition, the matters described in the above-described embodiments can be appropriately and arbitrarily combined as long as there is no contradiction.

INDUSTRIAL APPLICABILITY The present invention can be used, for example, in vehicles that transmit torque from a crank to a chain wheel.

DESCRIPTION OF SYMBOLS 100... Bicycle, 101... Vehicle body, 1011... Handle, 1012... Saddle, 102... Wheel, 102f... Front wheel, 102r... Rear wheel, 103... Power transmission mechanism , 1031... Crank, 1032... Crankshaft, 1033... Pedal, 1034... Chain wheel, 104... Drive unit, 105... Power supply unit, 1... Connection member, 2. Body portion 3 Arm portion 31 Arm base portion 32 Fixing portion 32a Hole portion 33 Stepped portion 33a Connection surface 33b Chamfered portion 34 Second concave portion 4 First concave portion 5 Cylindrical portion 6 Rib Ac Central axis D1 First direction D2 Second direction As... symmetry axis Da... axial direction Da1... one axial direction Da2... other axial direction Dr... circumferential direction Dr1... one circumferential direction , Dr2... the other in the circumferential direction

Claims (19)

A connecting member for connecting a crank to a chain wheel circumferentially rotatable about a central axis,
an annular body portion surrounding the central axis extending in the axial direction;
a plurality of arm portions extending at least radially outward from the body portion when viewed in the axial direction;
a first concave portion arranged in an axial end surface of at least one of the body portion and the arm portion and recessed in the axial direction;
with
a first direction is a direction in which the arm portion extends, a second direction is a direction perpendicular to the first direction and the axial direction;
an axis of symmetry extends in the first direction through the center of the arm in the second direction;
The connecting member, wherein the arm portion has a non-symmetrical shape with respect to the axis of symmetry when viewed from the axial direction. Seen from the axial direction,
The arm portion extends radially outward and in one circumferential direction,
The connecting member according to claim 1, wherein the length of the one circumferential end of the arm portion is shorter than the length of the other circumferential end of the arm portion. At least part of the first recess is arranged on the axial end face of the arm,
When viewed from the axial direction, a first interval between one circumferential end of the arm portion and the first recess is wider than a second interval between the other circumferential end of the arm portion and the first recess, The connection member according to claim 1 or 2. 4. The connecting member according to claim 3, wherein the first distance widens radially inward when viewed from the axial direction. The connection member according to any one of claims 1 to 4, wherein a first width of the arm portion in the axial direction is wider than a second width of the body portion in the axial direction. The connection member according to any one of claims 1 to 4, wherein the second axial width of the body portion is wider than the first axial width of the arm portion. The arm portion
an arm base extending at least radially outwardly from the body when viewed in the axial direction;
a fixing portion extending in the first direction from a radially outer end portion of the arm base portion and capable of being fixed to the chain wheel;
a stepped portion disposed between the arm base portion and the fixed portion;
has
the stepped portion has a connecting surface that connects a radially outer end portion of the one axial end surface of the arm base portion and a radially inner end portion of the one axial end surface of the fixed portion;
the radially outer end of the one axial end face of the arm base is arranged axially in one direction relative to the radially inner end of the one axial end face of the fixed portion;
7. The coupling member according to any one of claims 1 to 6, wherein the connecting surface extends in an axial direction or in a direction crossing the axial direction. 8. The coupling member according to claim 7, wherein, when viewed from the axial direction, at least a region of the connecting surface on the other side in the circumferential direction extends radially inward toward the other side in the circumferential direction. The fixing part has a hole extending through the fixing part in the axial direction,
8. When viewed from the axial direction, a third distance between the hole and the radially outer end of the fixing portion is narrower than a fourth distance between the hole and the first recess. The connecting member according to . 10. A connecting member according to any preceding claim, further comprising a tubular portion extending axially from the radially inner end of the body portion. At least part of the first recess is arranged on the axial end face of the body,
11. The connecting member according to claim 10, wherein said first recess is in contact with a radially outer surface of said cylindrical portion when viewed from the axial direction. further comprising a rib that connects the cylindrical portion and one of the outer edge portion of the body portion and the outer edge portion of the arm portion when viewed from the axial direction,
12. The connecting member according to claim 11, wherein the rib is in contact with the first recess in the circumferential direction when viewed from the axial direction. The connecting member according to any one of claims 1 to 12, wherein the arm portion has a second concave portion arranged at one end portion in the circumferential direction of the arm portion and recessed in the other circumferential direction. The arm portions are plural and arranged in the circumferential direction,
In the two arm portions adjacent to each other in the circumferential direction, the radially inner end portion of the second recess in the arm portion on the other side in the circumferential direction is the radially outer end portion of the body portion and the 14. The connecting member according to claim 13, gently connected to one of the other circumferential ends of the arm portion. 15. The fifth space between the one circumferential end portion and the other circumferential end portion of the arm portion is the widest at the same radial position as the radial outer end portion of the first recess. connecting member. 16. The arm portion according to any one of claims 13 to 15, wherein the one circumferential end portion of the arm portion is disposed closest to the one circumferential end portion at the same radial position as the radial outer end portion of the first recess. connecting member. The connecting member according to any one of claims 1 to 16, wherein the width of the arm base in the second direction increases radially inward. A connection member according to any one of claims 1 to 17;
a chain wheel circumferentially rotatable about a central axis;
a crank connected to the chain wheel by the connecting member;
A bicycle. A connection member according to any one of claims 1 to 17;
a chain wheel circumferentially rotatable about a central axis;
a crank connected to the chain wheel by the connecting member;
a drive for applying torque to the chainwheel;
a power supply unit that supplies power to the driving device;
electric assist bicycle.

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