Bicycle steering assist motor unit and bicycle provided with same

Abstract

A steering assist motor unit 1 has a torque transmission rotating body 22 included in a second torque transmission path for transmitting a torque of a steering assist motor 11 to a first torque transmission path. The torque transmission rotating body 22 has an inner surface 22a that is penetrated by a steering column 3 through a gap so that the torque of the steering assist motor 11 is not directly transmitted from the torque transmission rotating body 22 to the steering column 3. The second torque transmission path includes a bicycle stem 33 which is disposed side by side in the axial direction with respect to the torque transmission rotating body 22 so that the torque is transmitted from the torque transmission rotating body 22 to the steering column 3, and which rotates integrally with the steering column 3 by being tightened in the tangential direction against the outer peripheral surface of the steering column 3. The bicycle stem 33 has a torque transmission part 33a for transmitting the torque between the torque transmission rotating body 22 and the bicycle stem 33, by coming into contact with a part of the torque transmission rotating body 22.

Description

Motor unit for assisting steering of bicycle and bicycle equipped with the same

[0001] The present invention relates to a motor unit for assisting steering of a bicycle and a bicycle equipped with the same.

[0002] Bicycle steering assist motors that assist steering of a bicycle handlebar are known. For example, Patent Document 1 discloses a robotic steering mechanism for an autonomous bicycle that includes a sensor, a steering control assembly configured to adjust the steering angle of the bicycle's front wheel, and a controller that acquires values ​​from the sensor. The controller adjusts the steering angle using the steering control assembly based on the values ​​from the sensor.

[0003] The document discloses that the steering control assembly includes a steering actuator, a steering column, and a gear assembly. The document also discloses that the steering gear of the gear assembly is attached to the steering column with a set screw. Figure 4 of the document discloses an ahead stem structure for connecting the steering wheel to the steering column.

[0004] US Patent Application Publication No. 2020 / 0102043

[0005] The ahead stem structure disclosed in Patent Document 1 includes a top cap, a lifting member, and a bicycle stem. The lifting member is located inside the top of the steering column, and by rotating the top cap, it expands to press against the inner surface of the steering column. This allows the lifting member to lift the steering column in the axial direction. The top cap is located at the upper end of the steering column and is connected to the lifting member by a threaded portion. The bicycle stem is connected to the outer circumferential surface of the steering column.

[0006] In the configuration disclosed in Patent Document 1, it is necessary to machine a threaded hole in the steering column through which a screw for attaching the steering gear of the gear assembly passes. After the threaded hole is machined in the steering column, when the top cap of the ahead stem structure is rotated and the steering column is pulled up by the pulling-up member, the position of the threaded hole changes in the axial direction of the steering column.

[0007] Therefore, with the configuration disclosed in Patent Document 1, it is difficult to assemble the steering gear, i.e., the torque transmission rotor of the torque transmission mechanism that transmits the output torque of the motor to the steering column, to the steering column using the set screw.

[0008] In response to this, there is a demand for a motor unit configuration in which a torque transmission rotor that transmits the output torque of a motor to a rotating shaft such as a steering column can be easily assembled to the rotating shaft.

[0009] An object of the present invention is to realize a motor unit configuration in which a torque transmission rotor that transmits the output torque of a motor to a rotating shaft such as a steering column can be easily assembled to the rotating shaft.

[0010] The present inventors have studied a configuration for transmitting the torque of a motor to a rotating shaft without machining the rotating shaft.

[0011] As a result of extensive research, the inventors have come up with a configuration in which the tightening member is attached to the rotating shaft so that the output torque of the motor is transmitted to the rotating shaft via the torque transmission rotor and the tightening member, rather than directly transmitted to the rotating shaft by the torque transmission rotor that transmits the output torque of the motor to the rotating shaft. This makes it possible to transmit the output torque of the motor to the rotating shaft without providing a screw hole in the steering column as in the configuration disclosed in Patent Document 1.

[0012] Therefore, the torque transmission rotor that transmits the output torque of the motor to a rotating shaft such as a steering column can be easily assembled to the rotating shaft.

[0013] As a result of the above-mentioned investigation, the inventors have come up with the following configuration.

[0014] A bicycle steering assist motor unit according to one embodiment of the present invention includes a steering column connected to a handlebar via a stem for integral rotation, the steering column including a torque transmission rotor that transmits motor torque to a first torque transmission path through which torque input to the handlebar is transmitted to the steering column. The torque transmission rotor protrudes upward from a body frame and rotates integrally with the handlebar. The torque transmission rotor has an inner surface through which a rotating shaft included in the first torque transmission path passes via a gap, making it easy to insert the torque transmission rotor into the rotating shaft and preventing direct transmission of torque from the motor to the outer circumferential surface of the rotating shaft. The second torque transmission path is formed separately from the torque transmission rotor so that torque from the motor transmitted from the torque transmission rotor is transmitted to the rotating shaft. The second torque transmission path includes a tightening member that is arranged alongside the torque transmission rotor in the axial direction of the rotating shaft and tightens tangentially to the outer circumferential surface of the rotating shaft so that at least a portion of the tightening member contacts the outer circumferential surface of the rotating shaft and rotates integrally with the rotating shaft. The tightening member has a torque transmission portion that transmits torque between the torque transmission rotor and the torque transmission rotor by contacting a part of the torque transmission rotor or a rotation transmission member formed to rotate integrally with the torque transmission rotor.

[0015] In the above-described configuration, the tightening member is arranged alongside the torque-transmitting rotor in the axial direction of the rotor shaft and is tightened tangentially to the outer circumferential surface of the rotor shaft, thereby rotating integrally with the rotor shaft. The torque-transmitting portion of the tightening member transmits torque to the torque-transmitting rotor by contacting a part of the torque-transmitting rotor or a rotation-transmitting member formed to rotate integrally with the torque-transmitting rotor. This allows the torque-transmitting rotor to rotate integrally with the rotor shaft by the tightening member.

[0016] As described above, the torque transmission rotor, which rotates integrally with the rotary shaft due to the tightening member, has a gap between its inner surface and the rotary shaft, which allows the torque transmission rotor to be attached to the rotary shaft after the torque transmission rotor has been attached, without precision machining of the torque transmission rotor and the rotary shaft, thereby realizing a second torque transmission path, which is a path for transmitting torque from the motor to the rotary shaft.

[0017] Therefore, it is possible to realize a motor unit configuration in which a torque transmission rotor that transmits the output torque of a motor to a rotating shaft such as a steering column can be easily assembled to the rotating shaft.

[0018] Furthermore, when the above-described configuration is applied to an ahead stem structure, the ahead stem can be used as the tightening member, thereby realizing the above-described configuration without increasing the number of parts.

[0019] Furthermore, when the above-described configuration is applied to a threaded stem structure, the tightening member is tightened against the rotating shaft of the threaded stem, making it possible to utilize the rigidity of the rotating shaft to tighten the tightening member. This allows the tightening member to be more firmly tightened and attached to the rotating shaft, thereby more reliably transmitting the torque of the motor to the rotating shaft.

[0020] According to another aspect, the bicycle steering assist motor unit of the present invention may include the following configuration: The torque transmission portion of the tightening member is at least one of: (1) a side surface of the tightening member that is close to the torque transmitting rotor and that receives a load in the axial direction of the rotating shaft and comes into contact with a side surface of the torque transmitting rotor or the rotation transmitting member that is close to the tightening member; (2) a first recess formed to come into contact with a first protrusion that protrudes from the torque transmitting rotor or the rotation transmitting member in the axial direction of the rotating shaft; or (3) a second protrusion formed to come into contact with a second recess that is recessed in the axial direction of the rotating shaft of the torque transmitting rotor or the rotation transmitting member.

[0021] This allows the tightening member to realize a torque transmission section that transmits torque between the torque-transmitting rotor and the torque-transmitting rotor. That is, in (1), the tightening member contacts the torque-transmitting rotor or the rotation-transmitting member when it receives an axial load from the rotating shaft, allowing the torque-transmitting rotor to rotate integrally with the rotating shaft. In addition, in (2), the first concave portion of the tightening member contacts the first convex portion that protrudes from the torque-transmitting rotor or the rotation-transmitting member in the axial direction of the rotating shaft, allowing the torque-transmitting rotor to rotate integrally with the rotating shaft. In addition, in (3), the second convex portion of the tightening member contacts the second concave portion that is recessed in the axial direction of the rotating shaft on the torque-transmitting rotor or the rotation-transmitting member, allowing the torque-transmitting rotor to rotate integrally with the rotating shaft.

[0022] Therefore, it is possible to realize a motor unit configuration in which a torque transmission rotor that transmits the output torque of a motor to a rotating shaft such as a steering column can be easily assembled to the rotating shaft.

[0023] According to another aspect, the bicycle steering assist motor unit of the present invention may include the following configuration: the torque transmission rotor is located below the tightening member in the axial direction of the rotation shaft.

[0024] This allows the torque transmission rotor and motor to be positioned lower than the tightening member, allowing the torque transmission rotor and motor to be positioned lower relative to the rotation axis and preventing the torque transmission rotor and motor from interfering with handle operation.

[0025] According to another aspect, the bicycle steering assist motor unit of the present invention may include the following configuration: the torque transmission rotor and the tightening member, or the torque transmission rotor, the rotation transmission member, and the tightening member, are pressed against each other in the axial direction of the rotation shaft by an axial pressing mechanism.

[0026] This allows the torque-transmitting rotor and the tightening member, or the torque-transmitting rotor, the rotation-transmitting member, and the tightening member, to be pressed against each other in the axial direction of the rotary shaft, thereby allowing the torque-transmitting rotor to rotate integrally with the rotary shaft by the tightening member.

[0027] Therefore, it is possible to realize a motor unit configuration in which a torque transmission rotor that transmits the output torque of a motor to a rotating shaft such as a steering column can be easily assembled to the rotating shaft.

[0028] Moreover, in the case of an ahead stem, the axial pressing mechanism can be realized by a part of the ahead stem configuration, and therefore the above configuration can be realized without adding any new parts.

[0029] According to another aspect, the bicycle steering assist motor unit of the present invention may include the following configuration: the torque transmission rotor and the tightening member are pressed downward in the axial direction of the rotary shaft by the axial pressing mechanism.

[0030] This allows the torque transmission rotor and the tightening member to be pressed against the body frame or the like, so that the torque transmission rotor can be sandwiched between the tightening member and the body frame, and the torque transmission rotor can be rotated integrally with the rotation shaft by the tightening member.

[0031] Therefore, it is possible to realize a motor unit configuration in which a torque transmission rotor that transmits the output torque of a motor to a rotating shaft such as a steering column can be easily assembled to the rotating shaft.

[0032] According to another aspect, the bicycle steering assist motor unit of the present invention may include the following configuration: The rotation transmission member is located between the torque transmission rotor and the tightening member.

[0033] This allows the torque-transmitting rotor and the tightening member to rotate integrally with each other by the rotation-transmitting member, and therefore the torque-transmitting rotor can be rotated integrally with the rotary shaft by the tightening member.

[0034] Therefore, it is possible to realize a motor unit configuration in which a torque transmission rotor that transmits the output torque of a motor to a rotating shaft such as a steering column can be easily assembled to the rotating shaft.

[0035] According to another aspect, the bicycle steering assist motor unit of the present invention may include the following configuration: the rotation transmission member has a recess that mates with a torque transmission protrusion formed on the torque transmission rotor, or a protrusion that mates with a torque transmission recess formed on the torque transmission rotor, or has a rotation transmission member torque transmission portion that receives an axial load from the rotating shaft and comes into contact with a side surface of the torque transmission rotor.

[0036] This allows the rotation transmission member and the torque transmission rotor to rotate integrally. The rotation transmission member comes into contact with the tightening member and rotates integrally with it, so the torque transmission rotor rotates integrally with the tightening member via the rotation transmission member. Therefore, the torque transmission rotor can be rotated integrally with the rotating shaft by the tightening member.

[0037] Therefore, it is possible to realize a motor unit configuration in which a torque transmission rotor that transmits the output torque of a motor to a rotating shaft such as a steering column can be easily assembled to the rotating shaft.

[0038] According to another aspect, the bicycle steering assist motor unit of the present invention may include the following configuration: The torque transmitting rotor is in direct contact with the tightening member without the rotation transmitting member being interposed therebetween.

[0039] As a result, even without a rotation transmission member, the torque transmission rotor can be rotated integrally with the rotary shaft by the tightening member.

[0040] Therefore, it is possible to realize a motor unit configuration in which a torque transmission rotor that transmits the output torque of a motor to a rotating shaft such as a steering column can be easily assembled to the rotating shaft.

[0041] A bicycle according to one embodiment of the present invention includes a bicycle operation assist motor unit having the above-described configuration. In the bicycle, the torque transmission rotor that transmits the output torque of the motor to the rotary shaft can be easily assembled to the steering column.

[0042] The terminology used in this specification is used for the purpose of defining particular embodiments only, and is not intended to limit the invention.

[0043] As used herein, "and / or" includes all combinations of one or more of the associated listed members.

[0044] As used herein, the use of "including," "comprising," or "having" and variations thereof identify the presence of stated features, steps, operations, elements, components, and / or equivalents thereof, but may include one or more of the steps, operations, elements, components, and / or groups thereof.

[0045] As used herein, the terms "attached," "connected," "coupled," and / or their equivalents are used broadly to encompass both "direct and indirect" attachments, connections, and couplings. Furthermore, "connected" and "coupled" are not limited to physical or mechanical connections or couplings, but can also include direct or indirect electrical connections or couplings.

[0046] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0047] Terms defined in commonly used dictionaries should be construed to have a meaning consistent with the relevant art and meaning in the context of this disclosure, and should not be construed in an idealized or overly formal sense unless expressly defined herein.

[0048] It will be understood that in describing the present invention, several techniques and processes are disclosed, each of which has distinct advantages and can be used in conjunction with one or more, or in some cases all, of the other disclosed techniques.

[0049] Thus, for the sake of clarity, the description of the present invention refrains from unnecessarily repeating every possible combination of the individual steps, but the specification and claims should be read with the understanding that all such combinations are within the scope of the present invention.

[0050] In this specification, an embodiment of a motor unit for assisting steering of a bicycle according to the present invention will be described.

[0051] In the following description, numerous specific examples are set forth to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced without these specific examples.

[0052] Accordingly, the following disclosure is to be considered as illustrative of the present invention and is not intended to limit the invention to the specific embodiments illustrated by the following drawings or description.

[0053] [Bicycle] In this specification, a bicycle is a vehicle that has a handlebar, a steering column that passes through a head tube, at least one front wheel, and at least one rear wheel, and is driven by a rider who rotates pedals. The bicycle may be a two-wheeled vehicle or a three-wheeled vehicle. The bicycle may be a vehicle that leans left and right, or a vehicle that does not lean left and right.

[0054] [Vehicle Frame] In this specification, the term "vehicle frame" refers to the frame that constitutes a bicycle, and includes members that constitute the skeleton of the bicycle, such as the head tube, top tube, and down tube.

[0055] [Handlebar] In this specification, the handlebar refers to a bar handle that extends in the left-right direction. The handlebar connector of the bicycle stem is connected to the left-right central portion of the handlebar.

[0056] [Assist] In this specification, the term "assist" refers to an operation of auxiliary inputting a rotational driving force to the steering column connected to the steering wheel, by an actuator, to rotate the steering wheel about the axis of the steering column, based on the input of a force by the occupant to the steering wheel or the input of an external force transmitted to the steering column via the front wheels. The assist includes a case in which the rotational driving force is input to the steering column so as to increase the input of the force by the occupant to the steering wheel, and a case in which the rotational driving force is input to the steering column so as to reduce the input of the external force transmitted to the steering column. When the input of the force by the occupant to the steering wheel is increased, the rotational driving force is input in a direction that further rotates the steering column. On the other hand, when the input of the external force transmitted to the steering column is reduced, the rotational driving force is input in a direction that suppresses the rotation of the steering column.

[0057] [Rotational Axle] In this specification, the rotational axis refers to the steering column, which is rotatably housed in the head tube of a bicycle and connected to the front fork that rotatably supports the front wheel, or a shaft-shaped part connected to the steering column. The steering force is transmitted to the rotational axis from the handlebars, and external forces are transmitted to the rotational axis via the front fork.

[0058] [First Torque Transmission Path] In this specification, the term "first torque transmission path" refers to a path through which torque input to a steering wheel is transmitted from the steering wheel to a steering column. The first torque transmission path also includes a path through which torque is transmitted from the steering column to the steering wheel. The first torque transmission path includes components that transmit torque from the steering wheel to the steering column, such as a steering wheel, a stem, and a steering column gear.

[0059] [Second Torque Transmission Path] In this specification, the second torque transmission path refers to a path through which torque output from a motor is transmitted to the first torque transmission path. The second torque transmission path also includes a path through which torque is transmitted from the first torque transmission path to the motor. The second torque transmission path includes, for example, a motor or a member capable of transmitting torque, such as a gear, a pulley, a link, a belt, a chain, or a sprocket.

[0060] [Near Side] In this specification, the term "side closest to a certain member" refers to the side of the target member that is closest to the certain member. For example, if a tightening member disposed in the axial direction of the rotation shaft relative to a torque-transmitting rotor is cylindrical, both end faces of the tightening member in the axial direction are side faces, and the end face of both end faces that is closest to the torque-transmitting rotor is the side face closest to the torque-transmitting rotor. Note that even if the target member has a shape other than cylindrical, the part of the surface of the target member that is closest to the certain member is the side face closest to the certain member.

[0061] [Rotating integrally] In this specification, "rotating integrally" includes not only cases where separate members are directly connected and rotate integrally, but also cases where separate members are indirectly connected via other members and rotate integrally.

[0062] [Tightening] In this specification, tightening refers to a state in which a member is fastened to the outer circumferential surface of a rotating shaft with a fastening member, thereby fixing the member to the rotating shaft. At least a portion of the tightened member is pressed against and in contact with the outer circumferential surface of the rotating shaft.

[0063] According to one embodiment of the present invention, it is possible to realize a motor unit configuration in which a torque transmission rotor that transmits the output torque of a motor to a steering column can be easily assembled to the steering column.

[0064] Fig. 1 is a left side view showing the schematic configuration of a bicycle steering assist motor unit according to a first embodiment. Fig. 2 is a left side view showing the schematic configuration of a bicycle steering assist motor unit according to a second embodiment. Fig. 3 is a left side view showing the schematic configuration of a bicycle having a bicycle steering assist motor unit. Fig. 4 is a diagram showing the schematic configuration of a stem mechanism and a steering assist device. Fig. 5 is a left side view showing an example of a bicycle stem according to a fourth embodiment. Fig. 6 is a top view of the bicycle stem and bicycle steering assist motor unit. Fig. 7 is a left side view showing the schematic configuration of a bicycle in which a steering assist motor and a battery are housed in a down tube.

[0065] Hereinafter, embodiments will be described with reference to the drawings. In each drawing, the same parts are designated by the same reference numerals, and the description of the same parts will not be repeated. Note that the dimensions of the components in each drawing do not faithfully represent the actual dimensions of the components and the dimensional ratios of the components.

[0066] Hereinafter, arrow F in the figures indicates the forward direction of the vehicle. Arrow RR in the figures indicates the rearward direction of the vehicle. Arrow U in the figures indicates the upward direction of the vehicle. Arrow D in the figures indicates the downward direction of the vehicle. Arrow L in the figures indicates the leftward direction of the vehicle. Arrow R in the figures indicates the rightward direction of the vehicle. Furthermore, in the following explanation, the up-down direction, left-right direction, and front-rear direction respectively refer to the up-down direction, left-right direction, and front-rear direction when viewed from the rider riding the bicycle.

[0067] (First embodiment) A bicycle steering assist motor unit 1 according to a first embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a left side view showing a schematic configuration of the bicycle steering assist motor unit 1 according to the first embodiment.

[0068] The bicycle steering assist motor unit 1 includes a steering assist motor 11 (motor) and a torque transmission mechanism 12 .

[0069] The steering assist motor 11 outputs torque that rotates the steering column 3 (rotation shaft). The steering assist motor 11 is connected to the torque transmission mechanism 12 so as to be able to transmit the output torque. In other words, the output shaft 11a of the steering assist motor 11 is connected to the torque transmission mechanism 12 so as to be able to input the output torque.

[0070] Although not specifically shown, the steering assist motor 11 is supported by the bicycle body frame. In the example shown in Figure 1, the steering assist motor 11 is located in front of the steering column 3, but it may also be located behind, to the left or right of the steering column 3, as long as it is close to the steering column 3.

[0071] The torque transmission mechanism 12 transmits the output torque of the steering assist motor 11 to the steering column 3. More specifically, the torque transmission mechanism 12 has a torque transmission portion 21 and a torque transmission rotor 22.

[0072] The torque transmission rotor 22 is disposed on the outer peripheral surface 3a of the steering column 3. The torque transmission rotor 22 has an inner surface 22a through which the steering column 3 passes via a gap, so that the torque transmission rotor 22 can be easily inserted into the steering column 3 and the torque of the motor 3 is not transmitted directly from the torque transmission rotor 22 to the outer peripheral surface of the steering column 3. In other words, when the steering column 3 passes through the torque transmission rotor 22, a gap is formed between the steering column 3 and the inner surface 22a of the torque transmission rotor 22. The torque transmission rotor 22 has a through hole with an inner diameter larger than the outer diameter of the steering column 3. The inner surface of this through hole is the inner surface 22a.

[0073] The torque transmission rotor 22 is located above the head tube 61. Although not shown, a bearing is disposed between the torque transmission rotor 22 and the head tube 61 to support the torque transmission rotor 22 rotatably about the axis P of the steering column 3 relative to the head tube 61.

[0074] The torque transmission unit 21 is connected to the output shaft 11a of the steering assist motor 11 so as to be able to transmit torque, and is also connected to the torque transmission rotor 22 so as to be able to transmit torque. As a result, the torque transmission unit 21 transmits the torque output from the output shaft 11a of the steering assist motor 11 to the torque transmission rotor 22. As will be described later, the torque transmission rotor 22 transmits the torque of the steering assist motor 11 to a first torque transmission path through which torque input to the steering wheel is transmitted to the steering column 3. The torque transmission rotor 22 constitutes a part of a second torque transmission path.

[0075] The torque transmission unit 21 and the torque transmission rotor 22 are configured as part of a mechanism capable of transmitting torque, such as a gear, a pulley, a link, a belt, a chain, a sprocket, etc. The torque transmission unit 21 and the torque transmission rotor 22 may be configured to change (amplify or decrease) the torque output from the steering assist motor 11.

[0076] The torque transmission mechanism 12 is housed in a casing 13. The casing 13 is supported by the bicycle body frame (not shown). Therefore, the torque transmission mechanism 12 is rotatable relative to the casing 13. The output shaft 11a of the steering assist motor 11 may be located inside the casing 13 or outside the casing 13.

[0077] The steering column 3 passes through the head tube 61 of the bicycle and is pulled up relative to the bicycle body frame (head tube 61) by the top cap 31 and the anchor 32. Therefore, the steering column 3 protrudes upward relative to the body frame.

[0078] More specifically, the anchor 32 is disposed inside the upper portion of the steering column 3. A threaded portion (not shown) of the top cap 31 is rotatably connected to the top of the anchor 32. The anchor 32 is configured so that its outer surface can move radially using a dedicated anchor installation tool (not shown). The anchor 32 is pre-fixed to the inner peripheral surface of the steering column 3 with its outer surface moving radially to press against the inner peripheral surface of the steering column 3. The top cap 31 is disposed between the axial end face of the head tube 61 and the bicycle stem 33 and a portion of the bicycle steering assist motor unit 1 (torque transmission rotor 22), which are each connected to the steering column 3. Although not shown in particular, a bearing is disposed between the torque transmission rotor 22 and the head tube 61.

[0079] In this embodiment, the torque transmission rotor 22 of the bicycle steering assist motor unit 1 is located closer to the head tube 61 than the bicycle stem 33 in the axial direction of the steering column 3 .

[0080] In the above-described configuration, by rotating the top cap 31 as described above, the steering column 3 can be pulled up in the axial direction relative to the bicycle body frame (head tube 61) by the anchor 32. The top cap 31 and the anchor 32 correspond to a pulling-up member.

[0081] In this way, the stem structure of this embodiment is a so-called ahead stem structure.

[0082] The bicycle stem 33 is formed separately from the torque transmission rotor 22. In other words, the bicycle stem 33 and the torque transmission rotor 22 are separate components. The bicycle stem 33 is fixed to the steering column 3 so that it can rotate integrally with the steering column 3. Specifically, the bicycle stem 33 is fixed to the outer peripheral surface of the steering column 3 by being tightened tangentially relative to the outer peripheral surface of the steering column 3. As a result, at least a portion of the bicycle stem 33 contacts the outer peripheral surface of the steering column 3, and rotates integrally with the steering column 3. Therefore, the steering column 3 rotates integrally with the bicycle stem 33, which is connected to the handlebars. The path along which torque input to the handlebars is transmitted to the steering column 3 via the bicycle stem 33 is the first torque transmission path. The bicycle stem 33 corresponds to a tightening member.

[0083] Methods for fixing the bicycle stem 33 to the steering column 3 include, for example, a fixing method using a clamp, a fixing method in which multiple separate parts are arranged to radially sandwich the steering column 3 and connected with fastening members, etc. In this embodiment, the bicycle stem 33 is fixed to the steering column 3 with fastening members 36.

[0084] The bicycle stem 33 is arranged alongside the torque transmission rotor 22 of the torque transmission mechanism 12 in the axial direction of the steering column 3. The torque transmission rotor 22 is located below the bicycle stem 33 in the axial direction of the steering column 3.

[0085] Therefore, when the steering column 3 is pulled axially upward by the top cap 31 and anchor 32 as described above, the bicycle stem 33 and torque transmission rotor 22 are sandwiched axially between the top cap 31 and the head tube 61. In other words, the top cap 31 and anchor 32 are included in the axial pressing mechanism 8 that presses the bicycle stem 33 and torque transmission rotor 22 in the axial direction of the steering column 3.

[0086] In this embodiment, the bicycle stem 33 and the torque transmission rotor 22 are pressed downward in the axial direction of the steering column 3 by the axial pressing mechanism 8 .

[0087] Because the torque transmission rotor 22 is located between the bicycle stem 33 and the head tube 61, by being pressed axially together with the bicycle stem 33 as described above, the torque transmission rotor 22 rotates integrally with the bicycle stem 33. Therefore, the torque transmission rotor 22 rotates integrally with the steering column 3 via the bicycle stem 33.

[0088] As a result, when torque is input from the motor to the torque transmission rotor 22, the torque transmission rotor 22 causes the steering column 3 to rotate about the axis P.

[0089] In this embodiment, the bicycle stem 33 corresponds to the tightening member in the bicycle steering assist motor unit 1. In other words, the bicycle steering assist motor unit 1 also includes the bicycle stem 33 for rotating the torque transmission rotor 22 integrally with the steering column 3.

[0090] The bicycle stem 33 has a torque transmission portion 33a that contacts a portion of the torque transmission rotor 22 to transmit torque between the bicycle stem 33 and the torque transmission rotor 22. In this embodiment, the torque transmission portion 33a is one of the axial end faces of the bicycle stem 33 that is closest to the torque transmission rotor 22. In other words, the torque transmission portion 33a is the side of the bicycle stem 33 that is closest to the torque transmission rotor 22 and that receives the axial load of the steering column 33 and comes into contact with the side of the torque transmission rotor 22 that is closest to the bicycle stem 33.

[0091] In this embodiment, the torque transmitting rotor 22 is in direct contact with the bicycle stem 33 without any rotation transmitting member or the like interposed therebetween.

[0092] The bicycle steering assist motor unit 1 according to this embodiment has a torque transmission rotor 22 on a steering column 3 connected to rotate integrally with the handlebars via a bicycle stem 33, and the torque transmission rotor 22 is included in a second torque transmission path that transmits torque from the steering assist motor 11 to a first torque transmission path that transmits torque input to the handlebars to the steering column 3. The torque transmission rotor 22 protrudes upward from the body frame, rotates integrally with the handlebars, and has an inner surface 22a through which the steering column 3 passes via a gap, so that the torque transmission rotor 22 can be easily inserted into the steering column 3 that rotates integrally with the handlebars and is included in the first torque transmission path, and so that the torque of the steering assist motor 11 is not transmitted directly from the torque transmission rotor 22 to the outer peripheral surface of the steering column 3. The second torque transmission path is formed separately from the torque transmission rotor 22 so that the torque of the steering assist motor 11 transmitted from the torque transmission rotor 22 is transmitted to the steering column 3, and includes a bicycle stem 33 that is arranged alongside the torque transmission rotor 22 in the axial direction of the steering column 3 and is tightened tangentially to the outer peripheral surface of the steering column 3, so that at least a portion of the bicycle stem 33 comes into contact with the outer peripheral surface of the steering column 3 and rotates integrally with the steering column 3. The bicycle stem 33 has a torque transmission portion 33a that comes into contact with a portion of the torque transmission rotor 22 and transmits torque between the bicycle stem 33 and the torque transmission rotor 22.

[0093] In the above-described configuration, the bicycle stem 33 is arranged alongside the torque transmission rotor 22 in the axial direction of the steering column 3, and is tightened tangentially against the outer circumferential surface of the steering column 3, thereby rotating integrally with the steering column 3. The torque transmission portion 33a of the bicycle stem 33 contacts a portion of the torque transmission rotor 22, thereby transmitting torque between the torque transmission rotor 22 and the bicycle stem 33. This allows the torque transmission rotor 22 to rotate integrally with the steering column 3 via the bicycle stem 33.

[0094] As described above, the torque transmission rotor 22, which rotates integrally with the steering column 3 via the bicycle stem 33, has a gap between its inner surface and the steering column 3. This makes it possible to retrofit the torque transmission rotor 22 to the steering column 3 without precision machining the torque transmission rotor 22 or the steering column 3, thereby realizing a second torque transmission path that transmits torque from the steering assist motor 11 to the steering column 3.

[0095] Therefore, it is possible to realize a configuration of a bicycle steering assist motor unit 1 in which the torque transmission rotor 22 that transmits the output torque of the steering assist motor 11 to the steering column 3 can be easily assembled to the steering column 3.

[0096] Furthermore, when the above-described configuration is applied to an ahead stem, the ahead stem can be used as the bicycle stem 33. This allows the above-described configuration to be realized without increasing the number of parts.

[0097] Furthermore, in this embodiment, the torque transmission portion 33a of the bicycle stem 33 is a side surface of the bicycle stem 33 that is closest to the torque transmission rotor 22 and that receives the axial load of the steering column 3 and comes into contact with the side surface of the torque transmission rotor 22 that is closest to the bicycle stem 33. This allows for the torque transmission portion 33a to be realized in the bicycle stem 33, transmitting torque between the torque transmission rotor 22 and the torque transmission rotor 22. In other words, because the torque transmission portion 33a of the bicycle stem 33 comes into contact with the torque transmission rotor 22 when it receives the axial load of the steering column 3, the bicycle stem 33 can rotate the torque transmission rotor 22 integrally with the steering column 3.

[0098] Furthermore, in this embodiment, the torque transmission rotor 22 is located below the bicycle stem 33 in the axial direction of the steering column 3. As a result, the torque transmission rotor 22 and the steering assist motor 11 are positioned below the bicycle stem 33, which allows the torque transmission rotor 22 and the steering assist motor 11 to be located at a lower position relative to the steering column 3 and prevents the torque transmission rotor 22 and the steering assist motor 11 from interfering with handlebar operation.

[0099] Furthermore, in this embodiment, the torque transmission rotor 22 and the bicycle stem 33 are pressed against each other in the axial direction of the steering column 3 by the axial pressing mechanism 8. This allows the torque transmission rotor 22 and the bicycle stem 33 to be pressed against each other in the axial direction of the steering column 3. Therefore, the torque transmission rotor 22 can be rotated integrally with the steering column 3 by the bicycle stem 33.

[0100] Moreover, in the case of an ahead stem, the axial pressing mechanism 8 can be realized by a part of the ahead stem configuration, and therefore the above configuration can be realized without adding any new parts or the like.

[0101] In this embodiment, the torque transmission rotor 22 and the bicycle stem 33 are pressed downward in the axial direction of the steering column 8 by the axial pressing mechanism 8. This allows the torque transmission rotor 22 and the bicycle stem 33 to be pressed against the body frame or the like, so that the torque transmission rotor 22 can be sandwiched between the bicycle stem 33 and the body frame. This allows the torque transmission rotor 22 to rotate integrally with the steering column 3 by the bicycle stem 33.

[0102] Furthermore, in this embodiment, the torque transmitting rotor 22 is in direct contact with the bicycle stem 33 without a rotation transmitting member in between. This allows the torque transmitting rotor 22 to be rotated integrally with the steering column 3 by the bicycle stem 33, even without a rotation transmitting member.

[0103] 2 is a left side view showing the schematic configuration of a bicycle steering assist motor unit 100 according to a second embodiment. The bicycle steering assist motor unit 100 according to this embodiment differs from the bicycle steering assist motor unit 1 of the first embodiment in that the torque transmission mechanism 112 has a torque transmission portion 121 that is a gear having two-stage gear portions 121a, 121b, and the torque transmission rotor 122 has a gear portion 122a. In the following, the same components as those in the first embodiment are denoted by the same reference numerals and their description will be omitted, and only the components that differ from the first embodiment will be described.

[0104] 2, the bicycle steering assist motor unit 100 includes a steering assist motor 11 and a torque transmission mechanism 112. The torque transmission mechanism 112 includes a torque transmission portion 121 and a torque transmission rotor 122.

[0105] The torque transmission unit 121 is a gear having two gear stages 121a and 121b. Specifically, the torque transmission unit 121 has a first gear stage 121a and a second gear stage 121b having a smaller diameter than the first gear stage 121a. The first gear stage 121a overlaps with the second gear stage 121b so that their rotation axes coincide. The first gear stage 121a and the second gear stage 121b are integrally formed. The torque transmission unit 121 is housed in the casing 113.

[0106] The first gear portion 121a meshes with a gear portion (not shown) formed on the outer peripheral surface of the output shaft 11a of the steering assist motor 11. The second gear portion 121b meshes with a gear portion 122a of a torque transmission rotor 122, which will be described later.

[0107] The torque transmission rotor 122 has a gear portion 122a on at least a portion of its outer circumferential surface. The gear portion 122a is, for example, fan-shaped or semicircular when viewed in the axial direction of the steering column 3. The gear portion 122a meshes with the second gear portion 121b of the torque transmission part 121. Similar to the torque transmission rotor 22 of the first embodiment, the torque transmission rotor 122 has an inner surface 122b that has a gap between it and the steering column 3 when the steering column 3 passes through it.

[0108] Similar to the torque transmission rotor 22 of the first embodiment, the torque transmission rotor 122 is located between the bicycle stem 33 and the head tube 61, and is sandwiched axially between the top cap 31 and the head tube 61 together with the bicycle stem 33. This allows the torque transmission rotor 122 to rotate integrally with the steering column 3 via the bicycle stem 33.

[0109] With the above configuration, the output torque of the steering assist motor 11 can be transmitted to the steering column 3 by the torque transmission mechanism 112 .

[0110] (Embodiment 3) Figure 3 is a left side view showing the schematic configuration of a bicycle X having a bicycle steering assist motor unit 200. The bicycle X according to this embodiment is, for example, a two-wheeled vehicle. The bicycle X has a front wheel 4, a rear wheel 5, a body frame 6, and a steering mechanism 7. The configurations of the front wheel 4, the rear wheel 5, and the body frame 6 are the same as those of conventional bicycles, and detailed explanations will be omitted. Components similar to those in embodiments 1 and 2 will be assigned the same reference numerals and explanations will be omitted.

[0111] 3, the steering mechanism 7 includes a fork 71, a steering column 3 (not shown), a stem mechanism 130, a steering assist device 73, and a handlebar 2. The steering column 3 extends obliquely so that its upper end is located rearward of its lower end.

[0112] The fork 71 rotatably supports the front wheel 4 at its lower end. The steering column 3 is connected to the upper end of the fork 71. The steering column 3 passes through the head tube 61 of the body frame 6. A stem mechanism 130 is attached to the upper end of the steering column 3. The handlebars 2 are supported by the stem mechanism 130. The steering assist device 73 assists in steering the handlebars 2 based on the torque input to the handlebars 2 or the steering column 3.

[0113] 4 is a diagram showing a schematic configuration of the stem mechanism 130 and the steering assist device 73. The stem mechanism 130 has a top cap 31, an anchor 32, and a bicycle stem 133.

[0114] The bicycle stem 133 has a first stem 134, a torque sensor 30, and a second stem 135 (tightening member).

[0115] The first stem 134 has a handle connection portion (not shown) at one end thereof, to which the handle 2 is connected. The other end of the first stem 134 is connected to the torque sensor 30.

[0116] The second stem 135 has, at one end, a steering column connection portion 135a that covers the outer peripheral surface of the steering column 3. The steering column 3 is connected to the steering column connection portion 135a. The steering column connection portion 135a is fastened in a tangential direction to the outer peripheral surface of the steering column 3. For example, the steering column connection portion 135a is formed in a cylindrical shape that is partially open in the circumferential direction so as to sandwich the outer peripheral surface of the steering column 3 in a direction intersecting the axial direction (lateral direction), and with the steering column 3 sandwiched in between, the open portion is fastened in a tangential direction to the outer peripheral surface of the steering column 3 by a fastening member 136. The fastening position of the fastening member 136 at the steering column connection portion 135a is a position between the steering column 3 and the torque sensor 30 when the second stem 135 is viewed from the side.

[0117] The steering column connecting portion 135a has a stem recess 135b that accommodates a part of a rotation transmission member 223 (described later) on the inner surface of the steering column connecting portion 135a, at a position opposite the fastening member 136 with respect to the steering column 3. The stem recess 135b extends in the axial direction of the steering column 3. The other end of the second stem 135 is connected to the torque sensor 30.

[0118] The torque sensor 30 is located behind the steering column 3. Therefore, the second stem 135 is connected to the steering column 3 so as to extend rearward. The first stem 134 is located axially outward of the steering column 3 and extends in a direction intersecting the axis P of the steering column 3 when viewed in the left-right direction.

[0119] The torque sensor 30 is positioned so as to overlap at least a portion of the anchor 32 when the bicycle stem 133 is viewed in the front-to-rear direction.

[0120] As a result, the torque sensor 30 is disposed above the steering column 3 in a position that overlaps with at least a portion of the anchor 32 when the bicycle stem 133 is viewed in the left-right or front-rear direction. In other words, the torque sensor 30 is prevented from being disposed so as to protrude significantly upward from the top of the steering column 3. Therefore, the torque sensor 30 can be disposed compactly in the up-down direction relative to the steering column 3.

[0121] Steering assist device 73 includes torque sensor 30 and bicycle steering assist motor unit 200. Bicycle steering assist motor unit 200 includes steering assist motor 11 and torque transmission mechanism 212. Torque transmission mechanism 212 is housed in casing 213 supported by a body frame (not shown).

[0122] The torque transmission mechanism 212 has a torque transmission portion 122, a torque transmission rotor 222, and a rotation transmission member 223. Similar to the torque transmission rotor 122 of the second embodiment, the torque transmission rotor 222 has an inner surface 222a that has a gap between it and the steering column 3 when the steering column 3 passes through, so that the torque transmission rotor 222 can be easily inserted and the torque of the steering assist motor 11 is not directly transmitted from the torque transmission rotor 222 to the outer peripheral surface of the steering column 3.

[0123] The torque transmission rotor 222 is sandwiched together with the steering column connection part 135a in the axial direction of the steering column 3 between the top cap 31 of the stem mechanism 130 and a bearing part 34 that rotatably supports the torque transmission rotor 122 relative to the head tube 61. Note that a bearing or the like (not shown) is disposed between the steering column connection part 135a and the casing 213. This allows the steering column connection part 135a to rotate relative to the casing 213.

[0124] As described above, the torque transmission rotor 222 is sandwiched between the top cap 31 and the bearing portion 34 together with the steering column connection portion 135a in the axial direction of the steering column 3, thereby transmitting the torque transmitted from the torque transmission portion 112 to the steering column 3 and the steering column connection portion 135a. Therefore, the second stem 135 corresponds to the tightening member in the bicycle steering assist motor unit 200. In other words, the bicycle steering assist motor unit 200 also includes the second stem 135 for rotating the torque transmission rotor 222 integrally with the steering column 3.

[0125] The torque transmission rotor 222 has, on its inner surface 222a, a transmission recess 222b (second recess, torque transmission recess) that accommodates a portion of the rotation transmission member 223. The transmission recess 222b extends in the axial direction of the steering column 3. That is, the transmission recess 222b is recessed in the axial direction of the steering column 3. The transmission recess 222b is provided in the torque transmission rotor 222 so as to connect with the stem recess 135b provided in the steering column connection portion 135a of the second stem 135. In this embodiment, the transmission recess 222b is provided on the inner surface of a portion of the inner surface 222a of the torque transmission rotor 222 where the torque transmission portion 121 transmits torque.

[0126] The rotation transmission member 223 is a rod-shaped member that connects the torque transmission rotor 222 and the second stem 135 so that they can rotate integrally. The rotation transmission member 223 is configured as a separate member from the torque transmission rotor 222, the second stem 135, and the steering column 3. The rotation transmission member 223 extends in the axial direction of the steering column 3 between the inner surfaces of the torque transmission rotor 222 and the second stem 135 and the outer circumferential surface of the steering column 3, and connects the torque transmission rotor 222 and the second stem 135 so that they can rotate integrally. An upper portion of the rotation transmission member 223 is housed in a stem recess 135b provided on the inner surface of the steering column connection portion 135a of the second stem 135. A lower portion of the rotation transmission member 223 is housed in a transmission recess 222b provided on the inner surface 222a of the torque transmission rotor 222. Therefore, the rotation transmission member 223 has a protrusion that contacts the inner surface of the transmission recess 222 b and also the inner surface of the stem recess 135 b. In other words, the rotation transmission member 223 has a protrusion that fits into the transmission recess 222 b, which serves as a torque transmission recess formed in the torque transmission rotor 222.

[0127] The protrusion corresponds to a first protrusion protruding in the axial direction from the torque transmission rotor 222, and the stem recess 135b corresponds to the first recess. In addition, the stem recess 135b of the second stem 135 comes into contact with a rotation transmission member 223 formed to rotate integrally with the torque transmission rotor 222, thereby functioning as a torque transmission part that transmits torque between the torque transmission rotor 222 and the stem recess 135b.

[0128] With the above configuration, the torque transmission rotor 222 and the second stem 135 rotate integrally via the rotation transmission member 223. As described above, the second stem 135 rotates integrally with the steering column 3, and therefore the torque transmission rotor 222 rotates integrally with the steering column 3 via the second stem 135.

[0129] In this embodiment, the bicycle steering assist motor unit 200 has a rotation transmission member 223 that extends in the axial direction of the steering column 3 between the inner surface 222a of the torque transmission rotor 222 and the inner surface of the second stem 135 and the outer peripheral surface of the steering column 3, and connects the torque transmission rotor 222 and the second stem 135 so that they can rotate integrally.

[0130] This allows the second stem 135 and the torque transmission rotor 222 to rotate integrally via the rotation transmission member 223. Therefore, the torque of the steering assist motor 11 input to the torque transmission rotor 222 is transmitted to the steering column 3 via the rotation transmission member 223 and the second stem 135 tightened to the steering column 3. Therefore, with the above-described configuration, the torque of the steering assist motor 11 can be transmitted to the steering column 3 more reliably.

[0131] Furthermore, in this embodiment, the rotation transmission member 223 is formed as a separate member from the torque transmission rotor 222, the second stem 135, and the steering column 3. This makes it possible to easily realize a configuration in which the torque transmission rotor 222, the second stem 135, and the steering column 3 rotate integrally, and also makes it possible to realize a simple configuration for the torque transmission rotor 222, the second stem 135, and the steering column 3 without making them complex shapes.

[0132] In this embodiment, the second stem 135 has a stem recess 135b as a torque transmission portion that contacts a rotation transmission member 223 formed to rotate integrally with the torque transmission rotor 222, thereby transmitting torque between the second stem 135 and the torque transmission rotor 222. Specifically, the second stem 135 has, on its inner surface, the stem recess 135b that extends in the axial direction and can accommodate the rotation transmission member 223.

[0133] This allows the rotation transmission member 223 to be disposed on the inner surface of the second stem 135 without impairing the function of the second stem 135 as a stem. Moreover, since there is no need to process the steering column 3 in order to dispose the rotation transmission member 223, the rotation transmission member 223 can be easily attached to the steering column 3. Therefore, it is possible to easily realize a configuration in which the second stem 135 can simultaneously function as a stem and as a member that transmits the torque of the steering assist motor 11 from the torque transmission rotor 222 to the steering column 3.

[0134] In addition, in this embodiment, the stem recess 135b as a torque transmission portion is a first recess formed in the second stem 135 so as to come into contact with the first convex portion of the rotation transmission member 223 that protrudes from the torque transmission rotor 222 in the axial direction of the steering column 3.

[0135] This provides a torque transmission section in the second stem 135 that transmits torque between the torque transmission rotor 222. That is, the stem recess 135b of the second stem 135 comes into contact with the first protrusion that protrudes from the torque transmission rotor 222 in the axial direction of the rotation shaft, so the torque transmission rotor 222 can be rotated integrally with the steering column 3 by the second stem 135.

[0136] (Embodiment 4) Figure 5 is a diagram showing an example of the configuration of a bicycle stem 33 provided with a torque sensor 30. Specifically, as shown in Figure 5, the bicycle stem 33 has a handlebar holder 234, a steering column holder 235, and the torque sensor 30. The handlebar holder 234 includes a handlebar connection portion (not shown). Note that the handlebar holder 234 and the steering column holder 235 may be separate components. Except for the following description, the configuration of this embodiment is the same as that of embodiment 1, and therefore a description of the same parts as embodiment 1 will be omitted.

[0137] The handle holding portion 234 and the steering column holding portion 235 are each connected to the torque sensor 30. The handle holding portion 234 is a rod-shaped member. One end of the handle holding portion 234 has a handle connection portion (not shown) that is connected to the handle 2. The other end of the handle holding portion 234 is connected to the torque sensor 30. The steering column holding portion 235 is a rod-shaped member. The other end of the steering column holding portion 235 has a steering column connection portion 235a that is connected to the steering column 3. One end of the steering column holding portion 235 is connected to the torque sensor 30. The handle connection portion and the steering connection portion 235a each have, for example, a clamp structure.

[0138] The steering column holding portion 235 is configured to space the torque sensor 30 and the handle holding portion 234 radially from the steering column 3 when viewed in the axial direction of the steering column 3. As a result, the handle 2 connected to the handle connecting portion of the handle holding portion 234 is also spaced radially from the steering column 3 when viewed in the axial direction of the steering column 3.

[0139] The handlebar holder 234, torque sensor 30, and steering column holder 235 are aligned in a straight line in the front-to-rear direction when viewed from above the bicycle stem 33. In other words, when viewed from the front-to-rear direction of the bicycle stem 33, the handlebar holder 234, torque sensor 30, and steering column holder 235 are arranged so that they overlap. This allows the torque sensor 30 to be positioned compactly in the left-to-right direction relative to the bicycle stem 33.

[0140] In the example shown in Figure 5 above, the torque sensor 30 is located in the front-rear direction relative to the steering column connection portion 235a. However, the torque sensor may also be located in the left-right direction relative to the steering column connection portion. In this case, the torque sensor may be located in a position where at least a portion of the torque sensor overlaps with the steering column connection portion when viewed from the left to right of the bicycle stem. This type of torque sensor location may also be applied to the configuration of embodiment 3.

[0141] 5, the steering column holding portion 235, the torque sensor 30, and the handle holding portion 234 are arranged in this order from the steering column 3 toward the steering wheel 2 in a top view: steering column holding portion 235, torque sensor 30, handle holding portion 234. However, as long as the torque sensor is located between the steering column holding portion and the handle holding portion, the steering column holding portion, torque sensor, and handle holding portion may be arranged in any order.

[0142] 5, the torque sensor 30 is located in front of the steering column 3. However, the torque sensor may be located behind the steering column, or to the left or right of the steering column.

[0143] 6 is a top view of the bicycle stem 33 and the bicycle steering assist motor unit 1. As shown in FIG. 6, at least a portion of the steering assist motor 11 of the bicycle steering assist motor unit 1 overlaps with the down tube 62 of the bicycle body frame 6 when viewed from above. In this embodiment, the width of the down tube 62 is wider than the width of the top tube 63.

[0144] This allows the bicycle steering assist motor unit 11 to be arranged compactly on the bicycle. The steering assist motor 11 is arranged above the down tube 62.

[0145] While the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiments, and can be practiced by appropriately modifying the above-described embodiments within the scope of the spirit thereof.

[0146] The above embodiments have been described with reference to an ahead-stem structure. However, the configurations of the above embodiments can also be applied to a threaded stem structure in which a portion of the stem (the thread) is inserted into and fixed in a steering column. In this case, the stem has a handlebar connection portion connected to a steering wheel and a rod-shaped steering column connection portion inserted into the steering column and partially protruding above the vehicle frame. With the steering column connection portion passing through a torque transmission rotor, a tightening member tightens the stem in a tangential direction relative to the outer circumferential surface of the stem so that the torque transmission rotor can rotate integrally with the steering column connection portion. The tightening member has a torque transmission portion that contacts a portion of the torque transmission rotor to transmit torque between the torque transmission rotor and the torque transmission rotor. As a result, even in a threaded stem structure, the output torque of the steering assist motor can be transmitted to the steering column, as in the above embodiments. Note that the steering column connection portion corresponds to the rotation axis.

[0147] When the configurations of the above embodiments are applied to a threaded stem structure, the tightening member is tightened against the steering column connection part, which is the stem rotation axis, and the rigidity of the steering column connection part can be utilized for tightening. This allows the tightening member to be more firmly tightened and attached to the steering column, and motor torque can be more reliably transmitted to the steering column.

[0148] In addition, even in the above-mentioned thread stem structure, a rotation transmission member 223 as in embodiment 3 may be provided between the torque transmission rotor and the tightening member and the steering column connection portion so that the torque transmission rotor and the tightening member rotate integrally.

[0149] In each of the above-described embodiments, the torque transmission mechanism 12, 112, 212 includes a torque transmission portion 21, 121 and a torque transmission rotor 22, 122, 222. However, the torque transmission mechanism may include only the torque transmission rotor. In this case, the output torque of the steering assist motor is transmitted to the torque transmission rotor.

[0150] In each of the above embodiments, another member (e.g., a disk-shaped member such as a washer) may be disposed as a rotation transmission member between the torque transmission rotor 22, 122, 222 and the bicycle stem 33 or second stem 135 serving as a tightening member. This allows torque to be transmitted between the torque transmission rotor 22, 122, 222 and the bicycle stem 33 or second stem 135 via the rotation transmission member, allowing them to rotate integrally. In this case, the torque transmission rotor, the rotation transmission member, and the tightening member may be pressed against each other in the axial direction of the rotation axis by the axial pressing mechanism of each embodiment. This allows greater torque to be transmitted between the torque transmission rotor 22, 122, 222 and the bicycle stem 33 or second stem 135.

[0151] Furthermore, in the above-described configuration, as in embodiment 3, a rod-shaped rotation transmission member may be provided that connects the torque transmission rotor 22, 122, 222 to the bicycle stem 33 or the second stem 135 so as to rotate them integrally.

[0152] The tightening member has a side surface of the rotation transmission member that is close to the torque transmitting rotor and that comes into contact with the side surface of the rotation transmission member that is close to the tightening member. The rotation transmission member has a rotation transmission member torque transmission portion that receives the axial load of the steering column and comes into contact with the side surface of the torque transmitting rotor. The rotation transmission member may have a recess that fits with a torque transmitting protrusion formed on the torque transmitting rotor, or a protrusion that fits with a torque transmitting recess formed on the torque transmitting rotor.

[0153] In each of the above-described embodiments, the torque transmitting rotor 22, 122, 222 is located above the bicycle stem 33 or the second stem 135 serving as the tightening member in the axial direction of the steering column 3. However, the torque transmitting rotor may also be located below the tightening member in the axial direction of the steering column.

[0154] In each of the above-described embodiments, the torque transmitting rotor 22, 122, 222 and the bicycle stem 33 or second stem 135 serving as the tightening member are pressed in the axial direction of the steering column 3 by the pressing mechanism 8. However, the torque transmitting rotor and the tightening member do not have to be pressed in the axial direction of the steering column by the pressing mechanism.

[0155] In the first, second, and fourth embodiments, the torque transmission rotor 22, 122 is sandwiched between the bicycle stem 33 and the head tube 61, and rotates integrally with the steering column 3 via the bicycle stem 33. However, as in the third embodiment, the bicycle stem and the torque transmission rotor may be connected by a rotation transmission member so as to rotate integrally.

[0156] In the first and second embodiments, the steering column 3 extends in the vertical direction. However, the steering column may extend in an oblique direction, as in the third embodiment. The steering column of the third embodiment may also extend in the vertical direction, as in the first and second embodiments.

[0157] In the first and second embodiments, the steering assist motor 11 is located behind the steering column 3. In the third embodiment, the steering assist motor 11 is located in front of the steering column 3. However, the steering assist motor may be located in any position relative to the steering column, such as in front of, behind, to the left or right of the steering column, as long as it is located near the steering column.

[0158] In the first and second embodiments, the torque transmitting rotor 122 is disposed closer to the head tube 61 than the bicycle stem 33. However, the torque transmitting rotor may be disposed farther from the head tube than the bicycle stem.

[0159] In the second and third embodiments, the gear portion 122a of the torque transmission rotor 122 is, for example, fan-shaped or semicircular when viewed in the axial direction of the steering column 3. However, the gear portion of the torque transmission rotor may also be circular when viewed in the axial direction of the steering column 3.

[0160] In the third embodiment, the bicycle steering assist motor unit 200 has a torque transmission mechanism 112 having a configuration similar to that of the second embodiment. However, the torque transmission mechanism of the bicycle steering assist motor unit may have a configuration different from that of the second embodiment.

[0161] In the third embodiment, the rotation transmission member 223 is configured as a separate member from the torque transmission rotor 222, the second stem 135, and the steering column 3. However, the rotation transmission member may be formed integrally with any of the torque transmission rotor, the second stem, or the steering column. Also, a portion of the rotation transmission member may be formed integrally with at least one of the torque transmission rotor, the second stem, or the steering column.

[0162] For example, when the rotation transmitting member is formed integrally with the torque transmitting rotor, the torque transmitting rotor has a first convex portion that protrudes from the torque transmitting rotor in the axial direction of the steering column. In this case, the torque transmitting portion of the second stem is a stem concave portion that is formed to contact the first convex portion. Also, when the rotation transmitting member is formed integrally with the second stem, the second stem has a second convex portion that protrudes from the second stem in the axial direction of the steering column. In this case, the second convex portion is a torque transmitting portion that is formed to contact a second concave portion that is recessed in the torque transmitting rotor in the axial direction of the steering column.

[0163] In the fourth embodiment, at least a portion of the steering assist motor 11 of the bicycle steering assist motor unit 1 overlaps with the down tube 62 of the bicycle body frame 6 when viewed from above. However, the steering assist motor does not have to overlap with the down tube of the bicycle body frame when viewed from above.

[0164] In the fourth embodiment, the steering assist motor 11 is disposed above the down tube 62. However, the steering assist motor may be disposed below the down tube. Also, the steering assist motor may be disposed inside the down tube as shown in FIG. 7 .

[0165] 7 is a left side view showing a schematic configuration of the bicycle Y in which the steering assist motor 311 and battery 312 are housed in the down tube 62. The battery 312 supplies power to the steering assist motor 311. Although not specifically shown, the bicycle steering assist motor unit 300 has a torque transmission mechanism for transmitting the output torque of the steering assist motor 311 to the steering column 3.

[0166] This improves the design of the bicycle Y equipped with the bicycle steering assist motor unit 300. Furthermore, by locating the steering assist motor 311 and the battery 312 inside the down tube 62, the center of gravity of the bicycle Y can be lowered.

[0167] The torque transmission mechanism may be housed in the down tube 62, the head tube 61, or may be disposed outside the body frame 6. In the example shown in Fig. 7, the steering assist motor 311 is disposed closer to the head tube 61 than the battery 312. However, the steering assist motor may be disposed farther from the head tube than the battery, or may be disposed at the same distance from the head tube as the battery. Furthermore, either the steering assist motor or the battery may be disposed outside the down tube or inside the top tube.

[0168] 1, 100, 200, 300 Bicycle steering assist motor unit 2 Handlebar 3 Steering column (rotating shaft) 3a Outer periphery 4 Front wheel 5 Rear wheel 6 Body frame 61 Head tube 62 Down tube 63 Top tube 7 Steering mechanism 8 Axial pressing mechanism 71 Fork 11, 311 Steering assist motor (motor) 11a Output shaft 12, 112, 212 Torque transmission mechanism 21, 121 Torque transmission section 121a First gear section 121b Second gear section 22, 122, 222 Torque transmission rotating body 122a Gear section 22a, 122b, 222a Inner surface 30 Torque sensor 31 Top cap 32 Anchor (lifting member) 33 (tightening member) 33a Torque transmission section 34 Bearing section 36 Fastening member 73 Steering assist device 13, 113, 213 Casing 130 Stem mechanism 133 Bicycle stem 134 First stem 135 Second stem (tightening member) 135a, 235a Steering column connection portion 135b Stem recess (torque transmission portion) 136 Fastening member 222b Transmission recess 223 Rotation transmission member 234 Handlebar holding portion 235 Steering column holding portion 312 Battery X, Y Bicycle P Axis

Claims

1. A motor unit for assisting steering of a bicycle, comprising a steering column connected to a handlebar via a stem so as to rotate integrally with the handlebar, and a torque transmission rotor included in a second torque transmission path which transmits the torque of a motor to a first torque transmission path through which torque input to the handlebar is transmitted to the steering column, wherein the torque transmission rotor protrudes upward from a body frame and rotates integrally with the handlebar, and has an inner surface through which a rotating shaft included in the first torque transmission path passes via a gap so that the torque transmission rotor can be easily inserted and the torque of the motor is not transmitted directly from the torque transmission rotor to the outer circumferential surface of the rotating shaft, and the second torque transmission path includes a tightening member which is formed separately from the torque transmission rotor so that the torque of the motor transmitted from the torque transmission rotor is transmitted to the rotating shaft, the tightening member is arranged in line with the torque transmission rotor in the axial direction of the rotating shaft and is tightened in a tangential direction relative to the outer circumferential surface of the rotating shaft so that at least a portion of the tightening member comes into contact with the outer circumferential surface of the rotating shaft and rotates integrally with the rotating shaft, a torque transmission portion that transmits torque between the torque transmission rotor and the torque transmission rotor by contacting a part of the torque transmission rotor or a rotation transmission member formed to rotate integrally with the torque transmission rotor.

2. A motor unit for bicycle steering assist as described in claim 1, wherein the torque transmission portion of the tightening member is at least one of: (1) a side surface of the tightening member close to the torque transmitting rotor that receives an axial load of the rotating shaft and comes into contact with a side surface of the torque transmitting rotor or the rotation transmitting member close to the tightening member; (2) a first recess formed to come into contact with a first convex portion protruding from the torque transmitting rotor or the rotation transmitting member in the axial direction of the rotating shaft; or (3) a second convex portion formed to come into contact with a second recess of the torque transmitting rotor or the rotation transmitting member recessed in the axial direction of the rotating shaft.

3. A motor unit for assisting steering of a bicycle as claimed in claim 1 or 2, wherein the torque transmission rotor is located below the tightening member in the axial direction of the rotary shaft.

4. A motor unit for assisting bicycle steering as described in any one of claims 1 to 3, wherein the torque transmission rotating body and the tightening member, or the torque transmission rotating body, the rotation transmission member and the tightening member, are pressed against each other in the axial direction of the rotating shaft by an axial pressing mechanism.

5. A motor unit for assisting steering of a bicycle as described in claim 4, wherein the torque transmission rotor and the tightening member are pressed downward in the axial direction of the rotating shaft by the axial pressing mechanism.

6. A motor unit for assisting steering of a bicycle as claimed in any one of claims 1 to 5, wherein the rotation transmission member is located between the torque transmission rotor and the tightening member.

7. A motor unit for bicycle steering assist as described in any one of claims 1 to 6, wherein the rotational transmission member has a recess that mates with a torque transmission protrusion formed on the torque transmission rotor, or a protrusion that mates with a torque transmission recess formed on the torque transmission rotor, or has a rotational transmission member torque transmission portion that contacts a side of the torque transmission rotor when subjected to an axial load from the rotating shaft.

8. A motor unit for assisting steering of a bicycle as claimed in any one of claims 1 to 5, wherein the torque transmission rotor is in direct contact with the tightening member without passing through the rotation transmission member.

9. A bicycle comprising a motor unit for assisting bicycle operation according to any one of claims 1 to 8.

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