Pedal-equipped bicycle

Abstract

Provided is a pedal-equipped bicycle mounted with a steering assist device capable of suppressing a decrease in operability when a vehicle body is inclined in a left-right direction in accordance with stepping-on of left and right pedals. A pedal-equipped bicycle 1 has: a vehicle body frame 2 including a down tube 22 having a front end part connected to a head tube 21 and a rear end part extending in an oblique direction so as to be positioned below the front end part; a front fork 3; and a steering assist device 40 including a battery 41, a steering assist motor 42, and a torque transmission mechanism 43. The down tube 22 has a shape in which, when viewed in an axial direction, a width in the left-right direction with respect to the pedal-equipped bicycle 1 is larger than a width in a direction perpendicular to the axial direction and the left-right direction. The steering assist motor 42 is disposed such that, when viewed in an up-down direction, at least a part thereof overlaps with the down tube 22 in which the battery 41 is stored.

Description

Pedal bicycle

[0001] The present invention relates to a pedal bicycle.

[0002] Pedal bicycles with electric power steering systems (EPS) that use electric actuators to assist the rider in steering are known. The electric power steering system includes a steering assist device that transmits torque to the steering column of the pedal bicycle using an electric steering assist motor, various sensors that detect the steering torque and steering angular velocity applied to the steering column, and a control device that controls the steering assist motor. The control device controls the steering assist motor based on the detected values ​​of the various sensors.

[0003] The steering assist motor is disposed on the pedal bicycle while being mechanically connected to the steering column by a gear, etc. The pedal bicycle described in Patent Document 1 has a steering assist device disposed to the left of the head tube of the body frame so that a gear fixed to the steering column meshes with a gear fixed to the output shaft of the steering assist motor.

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

[0005] Pedal bicycles are configured so that torque is transmitted to the rear wheel, which is the drive wheel, by alternately stepping on the left and right pedals located on the left and right sides of the body frame.

[0006] The pedal bicycle described in Patent Document 1 has the steering assist motor, which is a heavy object, located to the left of the head tube. Therefore, the center of gravity of the pedal bicycle described in Patent Document 1 is shifted to the left of the lateral center of the vehicle body. Furthermore, the steering assist motor is located in the upper part of the vehicle body, which moves a larger amount lateral than the lower part of the vehicle body when the vehicle body is tilted lateral with the contact point between the wheels and the road surface as the center of rotation.

[0007] In a pedal bicycle that tilts left and right around the contact point between the wheel and the road surface as the center of rotation, the moment of inertia of the steering assist motor increases in proportion to the radius from the center of rotation. Furthermore, the greater the moment of inertia of the steering assist motor that occurs when tilting left and right around the contact point between the wheel and the road surface as the center of rotation, the more difficult it becomes to tilt left and right. Furthermore, in a pedal bicycle, the angle of left and right tilt must be changed to match the left and right shift in the center of gravity caused by the steering assist motor.

[0008] The pedal bicycle described in the cited document 1 has a steering assist motor located to the left of the head tube, above and away from the center of rotation. Therefore, tilting the pedal bicycle described in the cited document 1 in the left-right direction is significantly affected by the moment of inertia of the steering assist motor.

[0009] In this way, in the pedal bicycle described in the cited document 1, the steering assist motor is positioned as described above, which reduces operability when leaning left and right in response to depression of the left and right pedals. For this reason, it is desirable to suppress the reduction in operability when leaning the vehicle body left and right in response to depression of the left and right pedals.

[0010] The present invention aims to provide a pedal bicycle equipped with a steering assist device that can suppress a decrease in operability when tilting the body left and right in accordance with the pressure on the left and right pedals.

[0011] The inventors have been studying a pedal bicycle that can suppress a decrease in maneuverability when leaning the bicycle body left and right in response to pedaling, even when equipped with a steering assist device. As a result of their intensive study, the inventors have come up with the following configuration.

[0012] A pedal-equipped bicycle according to one embodiment of the present invention is a pedal-equipped bicycle having a body frame including a head tube and a down tube whose front end is connected to the head tube and which extends diagonally so that its rear end is located lower than the front end; a front fork including a steering column rotatably supported on the head tube; and a steering assist device including a steering assist motor, a battery that supplies power to the steering assist motor, and a torque transmission mechanism that transmits the torque of the steering assist motor to the steering column or transmits the torque of the steering column to the steering assist motor.

[0013] The down tube has a shape such that, when viewed in the axial direction, the width in the left-right direction of the pedaled bicycle is greater than the width in a direction perpendicular to the axial direction and the left-right direction. The steering assist motor is disposed behind the rear edge of the head tube so that at least a portion of the motor overlaps with the down tube when viewed in the vertical direction of the pedaled bicycle.

[0014] As described above, a portion of the steering assist motor overlaps with the down tube behind the rear edge of the head tube when viewed from above. The heavy steering assist motor is located closer to the center of gravity of the pedal bicycle, including the rider, than the head tube. Therefore, the influence of the steering assist motor on tilting the body of the pedal bicycle in the left-right direction is reduced by locating the steering assist motor behind the rear edge of the head tube so as to overlap with the down tube.

[0015] Furthermore, the shift in the center of gravity of the pedaled bicycle in the left-right direction is suppressed by arranging the steering assist motor so that it overlaps the down tube when the pedaled bicycle is viewed from above.

[0016] As a result, it is possible to suppress a decrease in operability when tilting the vehicle body in the left-right direction in accordance with depression of the left and right pedals.

[0017] From another perspective, the pedaled bicycle of the present invention preferably includes the following configuration: A pedal support is supported by the down tube and is positioned so as to overlap the axis of the down tube when the pedaled bicycle is viewed in a vertical direction.

[0018] As described above, the steering assist motor supported by the down tube is positioned below the head tube. Furthermore, the moment of inertia of the steering assist motor when tilting the body of the pedaled bicycle left or right around the ground contact point of the wheel becomes smaller the closer the steering assist motor is positioned using the down tube to the ground contact point. Therefore, by supporting the steering assist motor on the down tube, the effect of the steering assist motor on the operation of tilting the body of the pedaled bicycle left or right can be reduced.

[0019] Furthermore, the axis of the down tube is located at the center of the pedaled bicycle in the left-right direction. In other words, the steering assist motor is located so as to overlap the center of the pedaled bicycle in the left-right direction. Therefore, the shift in the center of gravity of the pedaled bicycle in the left-right direction due to the placement of the steering assist motor on the pedaled bicycle is further reduced. This reduces the deterioration of maneuverability when leaning the bicycle left and right in response to the pressure on the left and right pedals.

[0020] According to another aspect, the pedal bicycle of the present invention preferably includes the following configuration: The steering assist motor is housed within the down tube.

[0021] As described above, the steering assist motor is housed within the down tube. Therefore, the center of the down tube in the lateral direction and the rotation axis of the steering assist motor are close to each other. Therefore, the shift in the lateral center of gravity of the pedal-equipped bicycle caused by the placement of the steering assist motor is further reduced. This reduces the deterioration of maneuverability when leaning the bicycle left and right in response to depression of the left and right pedals.

[0022] From another perspective, the pedal bicycle of the present invention preferably includes the following configuration: The torque transmission mechanism changes the torque of the output shaft of the steering assist motor and transmits it to the steering column.

[0023] As described above, the torque of the steering assist motor is changed by the torque transmission mechanism and transmitted to the steering column. Therefore, when the torque of the steering assist motor is amplified by the torque transmission mechanism, the steering assist motor can rotate the steering column with a smaller torque capacity than when the torque of the steering assist motor is transmitted directly to the steering column. This reduces the moment of inertia of the steering assist motor that occurs when the body of the pedal-equipped bicycle is tilted left or right around the wheel's contact point as the center of rotation. This reduces the deterioration of operability when the body is tilted left or right in accordance with the pressure on the left and right pedals.

[0024] The terminology used in this specification is used for the purpose of defining particular embodiments only, and is not intended to limit the invention.

[0025] As used herein, "and / or" includes all combinations of one or more of the associated listed members.

[0026] In this specification, 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.

[0027] 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.

[0028] 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.

[0029] Terms defined in commonly used dictionaries should be construed to have a meaning consistent with the meaning in the context of the relevant art and this disclosure, and should not be construed in an idealized or overly formal sense unless expressly defined herein.

[0030] 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.

[0031] 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.

[0032] In this specification, an embodiment of a pedal bicycle according to the present invention will be described.

[0033] 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.

[0034] 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.

[0035] [Pedal Bicycle] In this specification, a pedal bicycle refers to a lean-type vehicle in which a body frame is supported by a front wheel located in front of the body frame and a rear wheel (drive wheel) located behind the body frame. The pedal bicycle also has a left pedal and a right pedal that the rider uses to transmit torque to the drive wheels. The pedal bicycle is configured to transmit torque to the drive wheels when the rider alternately presses down on the left pedal located to the left of the body frame and the right pedal located to the right of the body frame. The pedal bicycle rotatably supports the front wheel, for example, by a pine-needle fork rotatably supported on the body frame.

[0036] [Down Tube] In this specification, the down tube refers to the part of the body frame of a pedal-equipped bicycle that connects the head tube, which supports the front fork, to the bottom bracket hanger, which supports the rotation shafts of the left and right pedals. The down tube is a pipe-shaped member made of iron, aluminum, carbon, or the like. The down tube extends rearward and downward from the head tube. Therefore, the down tube extends diagonally so that the upper end is located behind the lower end.

[0037] [Steering column] In this specification, the term "steering column" refers to a component of a pedal bicycle that is rotatably housed within the head tube and connected to the fork that rotatably supports the front wheel. The steering column is connected to a steering column connector of a bicycle stem.

[0038] [Steering assist device] In this specification, the steering assist device refers to a unit that combines an electric steering assist motor that constitutes an electric steering system with a torque transmission mechanism that transmits torque. The steering assist device transmits torque to the steering shaft of a two-wheeled vehicle, which is the torque transmission object that transmits torque to the steering assist motor. The steering assist device performs, for example, steering support for the driver of the two-wheeled vehicle and steering operations to make the vehicle body independent.

[0039] [Forward / Backward Direction] In this specification, the forward / backward direction refers to the forward / backward direction as seen from the perspective of a rider riding a pedal bicycle with the steering assist device attached to the pedal bicycle.

[0040] [Left and right direction] In this specification, the left and right direction means the left and right direction as seen from the rider of the pedal bicycle with the steering assist device attached to the pedal bicycle.

[0041] [Up-down direction] In this specification, the up-down direction refers to the left-right direction as seen from the rider of the pedal bicycle with the steering assist device attached to the pedal bicycle.

[0042] [Torque transmission mechanism] In this specification, the term "torque transmission mechanism" refers to a mechanism that transmits torque input via an input member to an output member. The torque transmission mechanism may be configured to transmit the input torque while changing the magnitude, direction, etc. of the input torque. The torque transmission mechanism may be configured, for example, with gears, chains, belts, links, etc.

[0043] [Dancing] In this specification, dancing refers to one method of riding a pedaled bicycle. In dancing, the rider of the pedaled bicycle alternately depresses the left and right pedals while not seated in the saddle, and alternately leans the bicycle body left and right in response to the pressure on the left and right pedals. Dancing is used when a large torque is transmitted to the pedaled bicycle, such as when traveling uphill or accelerating. Note that dancing also includes the case where the rider, while seated in the saddle, alternately leans the bicycle body left and right in response to the pressure on the left and right pedals.

[0044] According to one embodiment of the present invention, it is possible to suppress a decrease in operability when tilting the vehicle body in the left-right direction in accordance with depression of the left and right pedals.

[0045] FIG. 1 is a side view of a pedaled bicycle according to a first embodiment of the present invention. FIG. 2 is a top view of the pedaled bicycle according to the first embodiment of the present invention. FIG. 3 is a view taken along the arrows III-III in FIG. 1. FIG. 4 is a view taken along the arrows IV-IV in FIG. 1. FIG. 5 is a front view of a pedaled bicycle according to the first embodiment of the present invention with the left and right pedals not depressed. FIG. 6 is a front view of a pedaled bicycle according to the first embodiment of the present invention with the left pedal depressed and tilted to the right. FIG. 7 is a front view of a pedaled bicycle according to the first embodiment of the present invention with the right pedal depressed and tilted to the left. FIG. 8 is a side view of a pedaled bicycle according to a modification of the first embodiment of the present invention.

[0046] Each embodiment will be described below 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.

[0047] [Embodiment 1] <Overall configuration of pedaled bicycle> A pedaled bicycle 1 according to embodiment 1 of the present invention will be described using Figures 1 to 4. Figure 1 is a side view of the pedaled bicycle 1 according to embodiment 1 of the present invention. Figure 2 is a top view of the pedaled bicycle 1. Figure 3 is a view taken along the arrows III-III in Figure 1. Figure 4 is a view taken along the arrows IV-IV in Figure 1.

[0048] Hereinafter, arrow F in the figures indicates the forward direction of pedaled bicycle 1. Arrow RR in the figures indicates the rearward direction of pedaled bicycle 1. Arrow U in the figures indicates the upward direction of pedaled bicycle 1. Arrow D in the figures indicates the downward direction of pedaled bicycle 1. Arrow L in the figures indicates the leftward direction of pedaled bicycle 1. Arrow R in the figures indicates the rightward direction of pedaled bicycle 1. Furthermore, in the following description, the up / down, left / right, and front / rear directions respectively refer to the up / down, left / right, and front / rear directions as seen by the rider of pedaled bicycle 1.

[0049] As shown in Figures 1 and 2, a pedaled bicycle 1 according to this embodiment has a steering assist device 40. The pedaled bicycle 1 has a body frame 2, a front fork 3, a handlebar 4, a front wheel 5, a rear wheel 6, a saddle 7, a left pedal 8, and a right pedal 9. The handlebar 4, the front wheel 5, the rear wheel 6, the saddle 7, the left pedal 8, and the right pedal 9 are configured in the same manner as conventional bicycles, and detailed explanations thereof will be omitted. Components similar to those in the first and second embodiments will be assigned the same reference numerals and explanations thereof will be omitted.

[0050] The body frame 2 supports a front fork 3, a rear wheel 6, a saddle 7, a left pedal 8, and a right pedal 9. The body frame 2 includes a head tube 21, a down tube 22, a seat tube 23, a top tube 24, seat stays 25, and chain stays 26.

[0051] The head tube 21 supports the front fork 3. The head tube 21 is located at the front end of the body frame 2. The head tube 21 is disposed so as to extend in the vertical direction.

[0052] The down tube 22 connects the head tube 21 and the seat tube 23. The down tube 22 extends rearward and downward from the rear edge of the head tube 21. The rear end of the head tube 21 is positioned lower than the front end. The front end of the down tube 22 is connected to the lower end of the head tube 21. The rear end of the down tube 22 is connected to the lower end of the seat tube 23.

[0053] 3, when viewed in the axial direction, the width W of the down tube 22 in the left-right direction is greater than the width H of the down tube 22 in a direction perpendicular to the axial direction and the left-right direction. In other words, the cross section of the down tube 22 perpendicular to the axis is formed in a rectangular shape extending in the left-right direction.

[0054] 1, the seat tube 23 connects the down tube 22 and the top tube 24. The seat tube 23 supports the saddle 7.

[0055] The top tube 24 connects the seat tube 23 and the head tube 21. The top tube 24 extends forward and upward from the front edge of the upper end of the seat tube 23. The front end of the top tube 24 is positioned higher than the rear end. The rear end of the top tube 24 is connected to the upper end of the seat tube 23. The front end of the top tube 24 is connected to the upper end of the head tube 21.

[0056] The seat stays 25 and the chain stays 26 support the rear wheel. The front ends of the seat stays 25 and the chain stays 26 extend rearward from the seat tube 23. The rear ends of the seat stays 25 and the chain stays 26 are connected to each other. The rear end of the chain stay 26 is connected to the rear end of the seat stay 25.

[0057] The body frame 2 configured in this manner rotatably supports the front fork 3 via the head tube 21. The body frame 2 supports the saddle 7 via the seat tube 23. The body frame 2 supports the left pedal 8 and the right pedal 9 via the connection between the down tube 22 and the seat tube 23. The body frame 2 also supports the rear wheel 6 via the connection between the seat stays 25 and the chain stays 26.

[0058] The front fork 3 supports the front wheel 5. The front fork 3 includes a steering column 31, a left fork portion 32, and a right fork portion 33. The front fork 3 is configured as a pine needle fork. The lower end of the steering column 31 is connected to the upper ends of the left fork portion 32 and the right fork portion 33. The steering column 31 passes through the head tube 21. The steering column 31 is also rotatably supported by the head tube 21. The left fork portion 32 and the right fork portion 33 support the axle of the front wheel 5. The handlebars 4 are attached to the upper end of the steering column 31 via a stem.

[0059] 1 to 4, the steering assist device 40 is an electric power steering drive device that assists the rider in steering the pedal bicycle 1. The steering assist device 40 is supported on the down tube 22. The steering assist device 40 controls the torque of the steering column 31 based on the detection value of a torque sensor 44 that detects the torque applied to the steering column 31.

[0060] The steering assist device 40 includes a battery 41 , a steering assist motor 42 , a torque transmission mechanism 43 , and a torque sensor 44 .

[0061] The battery 41 is a power source for the steering assist motor 42. The battery 41 is configured by a known storage battery such as a lithium ion battery. The battery 41 is electrically connected to the steering assist motor 42 and the torque sensor 44. The battery 41 is supported by the down tube 22. At least a portion of the battery 41 is housed inside the down tube 22. Therefore, at least a portion of the battery 41 overlaps with the down tube 22 when viewed in the up-down direction. Furthermore, when viewed in the up-down direction, the battery 41 overlaps with an imaginary center plane C (see FIGS. 2 and 5 ) that passes through the center line in the left-right direction, which is the axis of the down tube 22.

[0062] The steering assist motor 42 outputs torque to the steering column 31. The steering assist motor 42 is an electric motor that is powered by electric power from the battery 41. The steering assist motor 42 is located behind the rear edge of the head tube 21. In addition, a portion of the steering assist motor 42 overlaps with the down tube 22 when viewed in the up-down direction.

[0063] The steering assist motor 42 is supported on the lower surface of the down tube 22. Therefore, at least a portion of the steering assist motor 42 overlaps with the down tube 22 when viewed rearward and in the up-down direction from the rear edge of the head tube 21. In addition, the steering assist motor 42 is located within a certain range from the imaginary center plane C of the down tube 22.

[0064] The torque transmission mechanism 43 changes (increases or decreases) the torque output by the steering assist motor 42 and transmits it to the steering column 31. The torque transmission mechanism 43 is connected to the steering assist motor 42 and the steering column 31. The torque transmission mechanism 43 may be configured in any way, such as a gear, a link, a belt, or a chain, as long as it is capable of transmitting the torque of the steering assist motor 42 to the steering column 31.

[0065] As shown in Figure 4, the torque transmission mechanism 43 has an input gear 431 fixed to the output shaft of the steering assist motor 42 and an output gear 432 fixed to the steering column 31. The input gear 431 is formed of a bevel gear. The output gear 432 is formed of a sector-shaped bevel gear. The diameter of the output gear 432 is larger than the diameter of the input gear 431. Therefore, the torque transmission mechanism 43 increases the torque output by the steering assist motor 42 and transmits it to the steering column 31.

[0066] The steering assist device 40 configured in this manner outputs torque output by the steering assist motor 42 to the steering column 31 via the torque transmission mechanism 43 .

[0067] A portion of the steering assist motor 42 is positioned so as to overlap the down tube 22 when looking at the pedaled bicycle 1 from above, thereby preventing imbalance in the center of gravity of the pedaled bicycle 1. Furthermore, the closer the steering assist motor 42 is positioned to the lower end of the down tube 22, the closer it is to the center position in the fore-and-aft direction of the body frame 2 and to the road surface on which the front wheel 5 and rear wheel 6 are in contact with the ground.

[0068] <Regarding behavior of the bicycle body when the rider depresses the left pedal 8 and right pedal 9> Using Figures 5 to 7, we will explain how the rider controls the posture of the pedaled bicycle 1 when the rider depresses the left pedal 8 and right pedal 9. Figure 5 is a front view of the pedaled bicycle 1 with the left pedal 8 and right pedal 9 not depressed. Figure 6 is a front view of the pedaled bicycle 1 in a state where the left pedal 8 is depressed and the bicycle is tilted to the right. Figure 7 is a front view of the pedaled bicycle 1 in a state where the right pedal 9 is depressed and the bicycle is tilted to the left.

[0069] As shown in Figures 5 and 6, when a rider of a pedaled bicycle 1 (see Figure 5) located in the neutral position N, for example, depresses the left pedal 8 (see arrow A1 in Figure 6), the rider pulls the left part of the handlebar 4 upward with the left hand (see arrow A2 in Figure 6) to absorb the upward reaction force generated by depressing the left pedal 8 and to prevent the center of gravity of the pedaled bicycle 1 from moving from the imaginary central plane C.

[0070] As shown in Figure 6, when the rider pulls the left part of the handlebars 4 upward in accordance with the magnitude of the pedaling force on the left pedal 8, the pedal bicycle 1 is tilted to the right of the neutral position N around the contact point G of the front wheel 5 and rear wheel 6 with the road surface as the center of rotation. At this time, the rider adjusts their body posture so that their center of gravity is aligned with the imaginary central plane C when viewed from above. As a result, the center of gravity of the pedal bicycle 1, including the rider, is maintained near the imaginary central plane C when viewed from above due to the force applied to the left pedal 8 and the tilt of the pedal bicycle 1 to the right.

[0071] When the driver moves the left pedal 8 to the lowest position, he or she finishes lifting up the left part of the steering wheel 4. Furthermore, the driver depresses the right pedal 9 and lifts up the right part of the steering wheel 4 in accordance with the pedaling force on the right pedal 9.

[0072] The pedaled bicycle 1, which has been tilted to the right of the neutral position N, is tilted toward the neutral position N from a position tilted to the right of the neutral position N with the ground contact position G of the front wheel 5 and the rear wheel 6 as the center of rotation by the rider pulling the left part of the handle 4 upward in accordance with the magnitude of the pedaling force on the right pedal 9.

[0073] As shown in Figure 7, the pedaled bicycle 1 is tilted to the left of the neutral position N by the rider depressing the right pedal 9 (see arrow A3) and pulling the right portion of the handlebars 4 upward (see arrow A4). At this time, the rider adjusts their body posture so that their center of gravity is aligned with the imaginary central plane C when viewed from above. As a result, the center of gravity of the pedaled bicycle 1, including the rider, is maintained near the imaginary central plane C when viewed from above due to the rider's depressing the right pedal 9 and the leftward tilt of the pedaled bicycle 1.

[0074] In order to maintain the center of gravity of the pedaled bicycle 1, including the rider, near the imaginary central plane C, the rider tilts the pedaled bicycle 1 to the right in response to the pressure on the left pedal 8, and tilts the pedaled bicycle 1 to the left in response to the pressure on the right pedal 9. When the rider stands up from the saddle 7 and depresses the left and right pedals 8 and 9 (dancing) in order to transmit greater driving force to the rear wheel 6, the tilt of the pedaled bicycle 1 caused by pulling up the handlebars 4 in response to the pressure on the left and right pedals 8 and 9 becomes greater than the tilt when the rider is seated in the saddle 7. In this way, the pedaled bicycle 1 moves straight without turning by alternately leaning left and right in response to the pressure on the left and right pedals 8 and 9.

[0075] Therefore, the influence of the steering assist motor 42 on the operation of tilting the pedaled bicycle 1 in the left-right direction is suppressed by arranging the steering assist motor 42 behind the rear edge of the head tube 21 so that it overlaps with the down tube 22. In addition, shifting of the center of gravity of the pedaled bicycle 1 in the left-right direction is suppressed by arranging the steering assist motor 42 so that it overlaps with the down tube 22 when viewed in the up-down direction.

[0076] Furthermore, the lateral maneuverability of the pedaled bicycle 1 when tilting left and right around the ground contact point G of the front wheel 5 and rear wheel 6 as the center of rotation is affected by the magnitude of the moment of inertia around the ground contact point G. The moment of inertia of the steering assist motor 42 around the center of rotation of the front wheel 5 and rear wheel 6 becomes smaller the closer the steering assist motor 42 is positioned to the ground contact point G. Furthermore, the center of gravity of the pedaled bicycle 1 becomes lower the closer the steering assist motor 42 is positioned to the ground contact point G. Therefore, a pedaled bicycle 1 having a steering assist motor 42 can suppress an increase in the moment of inertia around the ground contact point G as the center of rotation by positioning the steering assist motor 42 on the down tube 22 extending downward from the head tube 21.

[0077] By supporting the steering assist motor 42 by the down tube 22, the center of gravity of the pedaled bicycle 1 is located within a certain range from the imaginary center plane C. Therefore, imbalance in the left-right direction of the pedaled bicycle 1 is suppressed.

[0078] Furthermore, the steering assist device 40 increases the torque of the steering assist motor 42 and transmits it to the steering column 31 by the torque transmission mechanism 43. Therefore, the steering assist motor 42 can rotate the steering column 31 with a smaller capacity than when the torque of the steering assist motor 42 is transmitted directly to the steering column 31. Therefore, the capacity and weight of the steering assist motor 42 are reduced by using the torque transmission mechanism 43. When the weight ratio of the steering assist motor 42 to the battery 41 is equal to or less than a certain value, the influence of the moment of inertia of the steering assist motor 42 about the ground contact position G as the rotation center is reduced.

[0079] In this way, the increase in the moment of inertia of the steering assist motor 42, which has the ground contact position G as its center of rotation, is suppressed, and the imbalance in the left-right direction is suppressed, thereby suppressing the decrease in operability when tilting the vehicle body left and right in accordance with the depression of the left and right pedals.

[0080] [Modification of Embodiment 1] A pedaled bicycle 1A, which is a modification of the pedaled bicycle of the present invention, will be described using Figure 8. Figure 8 is a side view of a pedaled bicycle 1A according to a modification of Embodiment 1 of the present invention. Note that in the following embodiment, specific descriptions of the same points as in the embodiments already described will be omitted, and the description will focus on the differences.

[0081] As shown in FIG. 8, the pedal bicycle 1A has a steering assist device 40.

[0082] The steering assist motor 42 of the steering assist device 40 is supported by the down tube 22. The steering assist motor 42 is housed inside the down tube 22. In this case, the steering assist motor 42 is disposed so as to overlap with the imaginary center plane C (see FIG. 2) of the down tube 22 when viewed in the up-down direction.

[0083] Furthermore, because the steering assist motor 42 is housed in the hollow portion of the down tube 22, it is disposed so that the imaginary center plane C in the left-right direction of the down tube 22 and the rotation axis of the steering assist motor 42 are close to each other. Therefore, by disposing the steering assist motor 42 in the hollow portion of the down tube 22, the left-right weight balance of the pedaled bicycle 1A is maintained approximately even. This further reduces the deterioration of maneuverability when leaning the vehicle body left-right in accordance with the depression of the left pedal 8 and the right pedal 9.

[0084] 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.

[0085] In the above-described embodiment, the pedal bicycle 1, 1A has a head tube 21, a down tube 22, a seat tube 23, and a top tube 24. However, it is sufficient for the pedal bicycle to have a head tube, a down tube, and a seat tube.

[0086] In the above-described embodiment, the steering assist motor 42 is supported on the down tube 22. However, the steering assist motor may be supported on at least one of the head tube, the seat tube, and the top tube.

[0087] In the first embodiment described above, the battery 41 is housed inside the down tube 22. However, the battery may be supported by the body frame. The battery may be arranged, for example, on the outer surface of the down tube. The battery may be arranged, for example, inside the seat tube.

[0088] In the above-described embodiment, the steering assist motor 42 is disposed on the lower surface of the down tube 22. Also, the steering assist motor 42 is housed inside the down tube 22. However, the steering assist motor may be disposed on the upper surface of the down tube. Also, the steering assist motor may be supported on the head tube, the top tube, or the seat tube.

[0089] In the above-described embodiment, the torque transmission mechanism 43 is disposed on the lower surface of the down tube 22 or inside the down tube 22. However, the torque transmission mechanism may also be disposed above the down tube. Furthermore, the torque transmission mechanism may also be housed in the head tube or disposed outside the body frame.

[0090] In the above-described embodiment, the steering assist motor 42 is disposed closer to the head tube 21 than the battery 41. However, the steering assist motor may be disposed farther from the head tube than the battery 41, 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 may be disposed inside the top tube.

[0091] In each of the above-described embodiments, the steering assist device 40 has the steering assist motor 42 as an actuator. However, the actuator of the steering assist device may be an electric actuator such as an electric cylinder.

[0092] 1, 1A Pedaled bicycle 2 Body frame 3 Front fork 4 Handlebars 5 Front wheel 6 Rear wheel 7 Saddle 8 Left pedal 9 Right pedal 21 Head tube 22 Down tube 23 Seat tube 24 Top tube 25 Seat stay 26 Chain stay 31 Steering column 32 Left fork section 33 Right fork section 40 Steering assist device 41 Battery 42 Steering assist motor 43 Torque transmission mechanism 44 Torque sensor 431 Input gear 432 Output gear A1 Arrow indicating pressing down on left pedal A2 Arrow indicating pulling up on left part of handlebar A3 Arrow indicating pressing down on right pedal A4 Arrow indicating pulling up on right part of handlebar C Virtual centre plane N Neutral position G Ground contact position

Claims

1. A pedaled bicycle having: a body frame including a head tube and a down tube whose front end is connected to the rear edge of the head tube and extends diagonally so that its rear end is located lower than the front end; a front fork including a steering column rotatably supported on the head tube; and a steering assist device including a steering assist motor, a battery that supplies power to the steering assist motor, and a torque transmission mechanism that transmits the torque of the steering assist motor to the steering column, wherein the down tube has a shape whose width in the left-right direction with respect to the pedaled bicycle when viewed in the axial direction is greater than its width in a direction perpendicular to the axial direction and the left-right directions, and the steering assist motor is positioned so that at least a portion of it overlaps with the down tube behind the rear edge of the head tube when viewed in the vertical direction of the pedaled bicycle.

2. A pedaled bicycle as described in claim 1, wherein the steering assist motor is supported by the down tube and is positioned so as to overlap with the axis of the down tube when the pedaled bicycle is viewed in the vertical direction.

3. A pedaled bicycle according to claim 1 or 2, wherein the steering assist motor is housed within the down tube.

4. A pedaled bicycle according to any one of claims 1 to 3, wherein the torque transmission mechanism changes the torque of the output shaft of the steering assist motor and transmits it to the steering column.

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