Steering-assistance device and leaning vehicle

Abstract

The present invention realizes a steering-assistance motor which enables a steering-assistance device to be easily assembled to a leaning vehicle while maintaining transmission accuracy of torque from a torque transmission mechanism accommodated in a leaning vehicle case. A steering-assistance device 1 has: a steering-assistance motor 30; a torque transmission mechanism 40; and a case 20 that accommodates the torque transmission mechanism 40. The steering-assistance device 1 is provided in a leaning vehicle 100 having a pine-needles type fork 120. The torque transmission mechanism 40 includes a torque transmission member 45 fixed to a steering shaft 121. The case 20 is rotatably supported by one end part and the other end part of the torque transmission member 45 in the rotation axis direction without coming into contact with a head pipe 111. The steering-assistance motor 30 outputs the torque to the steering shaft 121 of the leaning vehicle 100 via the torque transmission mechanism 45 or receives torque from the steering shaft 121.

Description

Steering assist device and lean vehicle

[0001] The present invention relates to a steering assist device and a lean vehicle having the steering assist device.

[0002] Lean-wheel vehicles are known that have an electric power steering system (EPS) that uses an electric actuator to assist the driver in steering. The electric power steering system includes a steering assist device that transmits torque to a steering shaft of the lean-wheel vehicle by an electric steering assist motor or that transmits torque from the steering shaft to the steering assist motor, various sensors that detect the steering torque and steering angular velocity applied to the steering shaft, 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 lean-to vehicle (motorcycle) described in Patent Document 1 has a steering assist device disposed on a so-called torii-shaped front fork rotatably supported on a body frame. The torii-shaped front fork has left and right shock absorbers, a top bridge connecting the upper ends of the left and right shock absorbers, a bottom bridge connecting the left and right shock absorbers below the top bridge, and a steering shaft connected to the top bridge and the bottom bridge. A handlebar is fixed to the top bridge. The left and right shock absorbers rotatably support the front wheel.

[0004] The steering assist device includes the steering assist motor, a plurality of gears constituting a torque transmission mechanism that transmits the torque of the steering assist motor to a steering shaft, and a case that houses the plurality of gears and supports the steering assist motor. In the steering assist device, a gear supported via a bearing on an upper part of the case is fixed to the steering shaft, and a fitting portion that fits into a head pipe of the body frame is provided on a lower part of the case.

[0005] Japanese Patent Application Laid-Open No. 2017-206169

[0006] In the lean-to vehicle, the steering angle range of the handlebar steered by the driver is smaller than that of a four-wheel vehicle. Therefore, the rotation angle of the steering shaft rotated by the steering assist device is also small. The steering assist device of the lean-to vehicle, which transmits torque over such a small rotation angle, is required to have high rotation accuracy. The rotation accuracy of the multiple gears is affected by the meshing accuracy of the multiple gears arranged in the case.

[0007] Meanwhile, the steering assist device supported by the steering shaft and the head pipe is subjected to vertical vibrations from the front wheels of the lean vehicle, and the case supporting the steering assist motor, which is a heavy object, is prone to elastic deformation in the vertical direction due to the vertical vibrations.

[0008] The meshing accuracy of the multiple gears decreases due to elastic deformation of the case, so the case needs to have high rigidity and support the gears fixed to the steering shaft via high-rigidity bearings so that the meshing accuracy of the multiple gears does not decrease due to elastic deformation.

[0009] However, increasing the rigidity of the case increases its weight, which increases the load on the steering shaft supporting the case. Therefore, the steering assist device of Patent Document 1 suppresses elastic deformation of the case by assembling a gear supported on the upper part of the case to the steering shaft and assembling a fitting portion of the lower part of the case to the head pipe.

[0010] The steering shaft, which is rotatably supported on the head pipe via a bearing, is positioned on the head pipe under conditions where errors such as machining errors and assembly errors of the head pipe, the bearing, and the steering shaft have accumulated. Therefore, when assembling the steering assist device to the lean vehicle, it is necessary to align the positions of both the steering shaft and the head pipe, which are different components. Therefore, there is a need for a steering assist device and a lean vehicle having the steering assist device that can be easily assembled to a lean vehicle while maintaining the torque transmission accuracy of the torque transmission mechanism housed in the case.

[0011] The present invention aims to provide a steering assist device that can be easily assembled to a lean vehicle while maintaining the torque transmission accuracy of the torque transmission mechanism housed in the case, and a lean vehicle having the steering assist device.

[0012] The present inventors have studied a steering assist device that can be easily installed in a lean vehicle while maintaining the torque transmission accuracy of a torque transmission mechanism housed in a case, and a lean vehicle having the steering assist device. As a result of extensive research, the present inventors have come up with the following configuration.

[0013] A steering assist device according to one embodiment of the present invention is a steering assist device having a steering assist motor, a torque transmission mechanism that transmits the torque output by the steering assist motor or the torque input to the steering assist motor, and a case that supports the steering assist motor and houses the torque transmission mechanism.

[0014] The steering assist device has a pine-needle fork including a left fork portion supporting the left end of the front wheel axle, a right fork portion supporting the right end of the front wheel axle, and a steering shaft extending upward from a connecting portion connecting the upper end of the left fork portion to the upper end of the right fork portion, and is installed in a lean vehicle that supports the steering shaft on a head pipe of a body frame so as to be rotatable about the axis of the head pipe. The torque transmission mechanism includes a torque transmission member that houses the steering shaft and is fixed to the steering shaft by a pressing force in the direction of the rotational axis of the steering shaft. The case is supported by one end and the other end in the direction of the rotational axis of the torque transmission member so as to be rotatable about the rotational axis without contacting the head pipe. The steering assist motor outputs torque to the steering shaft of the lean vehicle via the torque transmission mechanism, or receives torque from the steering shaft via the torque transmission mechanism.

[0015] As described above, the case is supported by one end and the other end of the torque transmission member in the rotational axis direction. This allows the steering assist motor and part of the torque transmission mechanism supported by the case to be supported by the torque transmission member. In this way, the support rigidity of the case for the torque transmission member is improved by being supported at two points, one end and the other end of the torque transmission member in the rotational axis direction. This allows the torque transmission accuracy of the torque transmission mechanism to be maintained.

[0016] Furthermore, the steering assist device is fixed to the steering shaft via the torque transmission member, which is fixed to the steering shaft by the axial pressing force of the steering shaft, without coming into contact with the head pipe. Therefore, the steering assist device can be fixed to the steering shaft even if its position relative to the steering shaft varies due to the influence of the processing accuracy and assembly accuracy of each part. Furthermore, the steering assist device can be easily and rigidly assembled to the lean vehicle simply by combining the steering shaft and the torque transmission member.

[0017] The steering assist device is supported on the steering shaft of the pine-needle fork via a torque transmission member included in the torque transmission mechanism. The pine-needle fork to which the steering assist device is attached does not have left and right fork sections, a top bridge, a bottom bridge, etc. located around the steering shaft, so the steering assist device can be easily attached.

[0018] Furthermore, since the case is fixed to the steering shaft without coming into contact with the head pipe, no external force is applied from the lean vehicle when the case is assembled to the lean vehicle, thereby suppressing elastic deformation of the case.

[0019] This allows the steering assist device to be easily assembled to the lean vehicle while maintaining the torque transmission accuracy of the torque transmission mechanism housed in the case of the lean vehicle.

[0020] From another viewpoint, it is preferable that the steering assist device of the present invention includes the following configuration: At least one of the steering assist motor and the case has a rotation prevention portion that prevents the case from rotating about the rotation axis of the steering shaft. The rotation prevention portion is connected to a body frame of the lean vehicle. The rotation prevention portion is configured so that the connection position with the body frame can be adjusted in the axial direction of the steering shaft.

[0021] As described above, the case is rotatably supported on the torque transmission member via bearings or the like. Therefore, when the steering assist motor outputs torque, the case rotates about the rotation axis of the torque transmission member. However, because the case is connected to the body frame of the lean vehicle by the anti-rotation portion, the case can be prevented from rotating about the rotation axis of the torque transmission member.

[0022] On the other hand, the torque transmission member has its position in the rotational axis direction fixed relative to the head pipe and the steering shaft by a pressing force in the rotational axis direction generated by a bolt or the like fastened to the steering shaft. At this time, the position of the steering assist device in the rotational axis direction relative to the head pipe fluctuates depending on the magnitude of the pressing force. However, even if the position of the steering assist device in the rotational axis direction relative to the head pipe fluctuates, the steering assist device can be connected to the body frame via the anti-rotation portion by adjusting the connection position of the anti-rotation portion relative to the body frame.

[0023] This allows the steering assist device to be easily assembled to the lean vehicle while maintaining the torque transmission accuracy of the torque transmission mechanism housed in the case of the lean vehicle.

[0024] From another viewpoint, it is preferable that the steering assist device of the present invention includes the following configuration: the torque transmission mechanism has a plurality of rotating bodies and is supported by the case so that the rotation axes of the plurality of rotating bodies extend in the rotation axis direction of the steering shaft, and the steering assist motor is supported by the case so that the output shaft extends in the rotation axis direction of the torque transmission member.

[0025] As described above, the case supports the steering assist motor and the torque transmission mechanism with the rotation shaft of the steering assist motor and the rotation shafts of the multiple rotors extending in the rotation axis direction of the torque transmission member. Therefore, the case can support the steering assist motor and the torque transmission mechanism close to each other. In other words, the steering assist motor and the multiple rotors are supported by the case with being arranged in a concentrated manner near the steering shaft.

[0026] This allows the torque transmission accuracy of the torque transmission mechanism housed in the case of a lean vehicle to be maintained, while suppressing elastic deformation of the case due to vertical vibrations and making it possible to easily assemble the steering assist device to the lean vehicle.

[0027] From another viewpoint, the steering assist device of the present invention preferably includes the following configuration: In the steering assist device, a portion of the head pipe is located inside the case.

[0028] As described above, the steering assist device is disposed in proximity to the head pipe by arranging the case at a position overlapping the head pipe when viewed in the front-rear or left-right direction of the lean vehicle, thereby making it possible to reduce the vertical size of the space occupied by the head pipe and the case.

[0029] Furthermore, if the sizes of the case and the torque transmission member are increased in the axial direction of the head pipe so that a portion of the head pipe is positioned inside the case, the support spacing of the case increases. Therefore, the support rigidity of the case, which is supported by the torque transmission member, for the torque transmission member is improved. This makes it possible to suppress elastic deformation of the case due to vertical vibrations and to easily assemble the steering assist device to the lean vehicle while maintaining the torque transmission accuracy of the torque transmission mechanism housed in the case.

[0030] A lean vehicle according to one embodiment of the present invention has a pine-needle fork including a left fork section supporting the left end of the front wheel axle, a right fork section supporting the right end of the front wheel axle, and a steering shaft extending upward from a connecting section connecting the upper end of the left fork section and the upper end of the right fork section, and is a lean vehicle that supports the steering shaft rotatably around the axis of the head pipe, and has the steering assist device.

[0031] The steering assist device is configured so that the steering shaft is accommodated in a torque transmission member of the steering assist device, and is fixed to the steering shaft without contacting the head pipe by a pressing force in the direction of the rotation axis of the steering shaft, and so that torque can be output from the steering assist device to the steering shaft.

[0032] As described above, in a lean vehicle in which the pine-needle fork is rotatably supported on the head pipe of the body frame, the steering shaft is housed in the torque transmission member, and a pressing force is applied to the torque transmission member in the direction of the rotation axis of the steering shaft. This allows the steering assist device to be fixed to the steering shaft. Therefore, the steering assist device can be easily and rigidly assembled to the lean vehicle.

[0033] In addition, in the steering assist device, the steering shaft is housed in the torque transmission member, so that the case is not subjected to external force from the lean vehicle when assembled to the lean vehicle, thereby suppressing elastic deformation of the case.

[0034] This makes it possible to easily assemble the steering assist device to the lean vehicle while maintaining the torque transmission accuracy of the torque transmission mechanism housed in the case of the lean vehicle.

[0035] The terminology used in this specification is used for the purpose of defining particular embodiments only, and is not intended to limit the invention.

[0036] As used herein, "and / or" includes all combinations of one or more of the associated listed members.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] In this specification, an embodiment of a steering assist device and a lean vehicle according to the present invention will be described.

[0044] 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.

[0045] 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.

[0046] [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 performs any processing on the steering shaft of a lean vehicle, which is the torque transmission object that transmits torque to the steering assist motor. For example, the steering assist device supports the steering of a driver who drives a lean vehicle, performs steering operations to make the vehicle body independent, etc.

[0047] [Pine-needle-shaped fork] In this specification, a pine-needle-shaped fork refers to a fork in which a left fork portion that supports the rotation shaft of the front wheel and a right fork portion that supports the end of the rotation shaft extend from one end of the steering shaft. In a lean vehicle in which the front wheel is supported by the pine-needle-shaped fork, the left fork portion and the right fork portion are located below the head pipe of the body frame that supports the pine-needle-shaped fork.

[0048] [Fore-and-aft direction] In this specification, the fore-and-aft direction means the fore-and-aft direction as seen from the driver driving a lean vehicle in a state in which a steering assist device is attached to the lean vehicle.

[0049] [Left and right direction] In this specification, the left and right direction means the left and right direction as seen from the driver driving a lean vehicle in a state in which a steering assist device is attached to the lean vehicle.

[0050] [Lean vehicle] In this specification, a lean vehicle is a vehicle that turns left with its body leaning to the left relative to its direction of travel, and turns right with its body leaning to the right relative to its direction of travel. The lean vehicle includes not only two-wheeled vehicles with front and rear wheels, but also vehicles with three or more wheels.

[0051] [Rotating Body] In this specification, a rotating body refers to a member that rotates around an arbitrary rotation axis. The rotating body is rotatably supported by a shaft, bearing, etc. whose axis is the rotation axis. The rotating body includes, for example, a gear, a pulley, a link, etc.

[0052] [Torque Transmission Member] In this specification, the torque transmission member refers to a member that transmits external torque to a steering shaft of a fork-type fork of a lean-to vehicle. The torque transmission member is fixed to the steering shaft. The torque transmission member includes, for example, a gear, a pulley, a link, etc.

[0053] [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. Examples of the torque transmission mechanism include gears, chains, belts, links, etc.

[0054] [Torque Transmission Accuracy] In this specification, torque transmission accuracy refers to the amount of time lag between when torque is input from the input member and when it is transmitted to the output member in the torque transmission mechanism. For example, in a torque transmission mechanism composed of gears, the torque transmission accuracy is determined by the amount of time it takes for the teeth of one gear to come into contact with the teeth of the other gear, which varies depending on the size of the gap (backlash) between the teeth of one meshing gear and the teeth of the other meshing gear. A torque transmission mechanism with large backlash has low torque transmission accuracy because it takes a long time for torque to be transmitted from one gear to the other gear.

[0055] According to one embodiment of the present invention, the steering assist device can be easily assembled to a lean vehicle while maintaining the torque transmission accuracy of the torque transmission mechanism housed in the lean vehicle case.

[0056] FIG. 1 is a partial cross-sectional view showing a side of a steering assist device according to a first embodiment of the present invention. FIG. 2 is a side view of the steering assist device according to the first embodiment of the present invention and a lean vehicle. FIG. 3 is a front view showing the steering assist device according to the first embodiment of the present invention and a front fork of the lean vehicle. FIG. 4 is a partial side view showing the steering assist device according to the first embodiment of the present invention and a front fork of the lean vehicle. FIG. 5 is a partial cross-sectional view showing a side of the steering assist device according to the first embodiment of the present invention in a state where it is supported on a steering shaft of a lean vehicle. FIG. 6 is a partial cross-sectional view showing a side of the steering assist device according to the first embodiment of the present invention in a state where it is assembled to the steering shaft of a lean vehicle. FIG. 7 is a partial cross-sectional view showing a side of the steering assist device according to a second embodiment of the present invention in a state where it is supported on a steering shaft of a lean vehicle.

[0057] 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.

[0058] [First Embodiment] <Overall Configuration of Steering Assist Device> A steering assist device 1 according to a first embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a partial cross-sectional view of the steering assist device 1 according to the first embodiment of the present invention.

[0059] Hereinafter, arrow F in the figures indicates the forward direction of a lean vehicle having the steering assist device 1. Arrow RR in the figures indicates the rearward direction of a lean vehicle having the steering assist device 1. Arrow U in the figures indicates the upward direction of a lean vehicle having the steering assist device 1. Arrow D in the figures indicates the downward direction of a lean vehicle having the steering assist device 1. Arrow L in the figures indicates the leftward direction of a lean vehicle having the steering assist device 1. Arrow R in the figures indicates the rightward direction of a lean vehicle having the steering assist device 1. Furthermore, in the following description, the up / down direction, left / right direction, and front / rear direction respectively mean the up / down direction, left / right direction, and front / rear direction when viewed from the driver operating the lean vehicle.

[0060] <Steering assist device> As shown in Figure 1, the steering assist device 1 is an electric power steering drive device that assists the steering operation of a driver of a lean vehicle 100 (see Figure 2), which will be described later. The steering assist device 1 is provided on a steering shaft 121 (see Figure 2) of the lean vehicle 100. The steering assist device 1 is a drive device that controls the torque of the steering shaft 121 based on detection values ​​of a torque sensor 61 (see Figure 2), which detects the torque applied to the steering shaft 121, a steering angle sensor 62, which detects the steering angle of the steering shaft 121, etc.

[0061] The steering assist device 1 has a case 20 , a steering assist motor 30 , a torque transmission mechanism 40 , and a rotation prevention portion 50 .

[0062] The case 20 houses the torque transmission mechanism 40 and supports the steering assist motor 30. The case 20 has a lower case portion 21 and an upper case portion 22. The lower case portion 21 and the upper case portion 22 configure the case 20 as a housing that houses the torque transmission mechanism 40.

[0063] The lower case portion 21 is located at the bottom of the case 20. The bottom of the lower case portion 21 has a motor shaft insertion hole 21a into which the output shaft 30a of the steering assist motor 30 can be inserted, and a lower case portion torque transmission member insertion hole 21b that can support the torque transmission member 45 of the torque transmission mechanism 40 that is fixed to the steering shaft 121. The lower case portion 21 is configured so that the steering assist motor 30 can be fixed with the output shaft 30a inserted into the motor shaft insertion hole 21a.

[0064] The upper case portion 22 is located at the top of the case 20. The upper portion of the upper case portion 22 has an upper case portion torque transmission member insertion hole 22b that can support the torque transmission member. The upper case portion torque transmission member insertion hole 22b is positioned so as to overlap the lower case portion torque transmission member insertion hole 21b when viewed in the vertical direction when the upper case portion 22 and the lower case portion 21 are assembled. The upper case portion 22 and the lower case portion 21 define a space that can accommodate the torque transmission mechanism 40.

[0065] The steering assist motor 30 outputs torque from an output shaft 30a to the steering shaft 121. The steering assist motor 30 is an electric motor that rotates by power supplied from a power source (not shown). The steering assist motor 30 is fixed to the lower case portion 21 with the output shaft 30a inserted into a lower case portion torque transmission member insertion hole 21b of the lower case portion 21. The output shaft 30a is positioned relative to the lower case portion 21 by a bearing 42. The output shaft 30a is located inside the case 20.

[0066] The torque transmission mechanism 40 transmits the torque output by the steering assist motor 30 to the steering shaft 121. The torque transmission mechanism 40 is connected to the steering assist motor 30 and the steering shaft 121. The torque transmission mechanism 40 has, for example, a motor shaft gear 41, an intermediate gear 43, and a torque transmission member 45, which is a gear that transmits torque to the steering shaft 121, which are multiple rotating bodies. The torque transmission mechanism 40 may have any configuration, 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 30 to the steering shaft 121.

[0067] The motor shaft gear 41 transmits the torque of the steering assist motor 30 to another rotating body. The motor shaft gear 41 is fixed to the output shaft 30a of the steering assist motor 30. Therefore, the motor shaft gear 41 is supported by the case 20 so as to be rotatable about the rotation axis of the output shaft 30a. The motor shaft gear 41 is positioned relative to the case 20 by a bearing 42.

[0068] The intermediate gear 43 transmits torque between the motor shaft gear 41 and the torque transmission member 45. The intermediate gear 43 has a shaft and at least one gear. The shaft of the intermediate gear 43 is rotatably supported by the case 20 via a pair of bearings 44. Thus, the intermediate gear 43 is supported by the case 20 rotatably about the rotation axis of the shaft of the intermediate gear 43.

[0069] The rotation axis of the intermediate gear 43 extends along the rotation axis of the output shaft 30a. That is, the rotation axis of the intermediate gear 43 extends in the direction of the rotation axis of the output shaft 30a. The intermediate gear 43 meshes with the motor shaft gear 41. The intermediate gear 43 is positioned in the case 20 so that the gap (backlash) between the gear of the motor shaft gear 41 and the gear of the intermediate gear 43 is appropriate.

[0070] The torque transmission member 45 is a gear that transmits the torque of the intermediate gear 43 to the steering shaft 121 and transmits the torque of the steering shaft 121 to the intermediate gear 43. The torque transmission member 45 has a space that can accommodate the steering shaft 121. Therefore, the torque transmission member 45 rotates about the rotation axis S of the steering shaft 121 (hereinafter simply referred to as the rotation axis S). The rotation axis of the torque transmission member 45 extends along the rotation axis of the output shaft 30a. In other words, the rotation axis of the torque transmission member 45 extends in the direction of the rotation axis of the output shaft 30a.

[0071] One end of the torque transmission member 45 in the direction of the rotation axis is rotatably supported by the lower case portion 21 via a bearing 46a located in the lower case portion torque transmission member insertion hole 21b. The other end of the torque transmission member 45 in the direction of the rotation axis is rotatably supported by the upper case portion 22 via a bearing 46b located in the upper case portion torque transmission member insertion hole 22b. Thus, the torque transmission member 45 is supported by the case 20 so as to be rotatable about the rotation axis.

[0072] The torque transmission member 45 meshes with the intermediate gear 43. One end of the torque transmission member 45 in the rotational axis direction is positioned in the lower case portion 21 by the lower case portion torque transmission member insertion hole 21b. The other end of the torque transmission member 45 in the rotational axis direction is positioned in the upper case portion 22 by the upper case portion torque transmission member insertion hole 22b. As a result, the torque transmission member 45 is positioned in the case 20 so that an appropriate gap is formed between the gear of the intermediate gear 43 and the gear of the torque transmission member 45.

[0073] The anti-rotation portion 50 prevents the case 20 and the steering assist motor 30 from rotating about the rotation axis of the torque transmission member 45 due to the torque of the steering assist motor 30. The anti-rotation portion 50 is provided, for example, on the steering assist motor 30 and the body frame 110 (see FIG. 2) of the lean vehicle 100. The anti-rotation portion 50 is a screw hole portion 51 provided in the steering assist motor 30 and a bracket 52 provided on the body frame 110 of the lean vehicle 100 on which the steering assist device 1 is provided. The screw hole portion 51 and the bracket 52 (see FIG. 4) are configured to be fastenable with a screw.

[0074] The anti-rotation portion 50 is configured so that the connection position of the screw hole portion 51 relative to the bracket 52 can be adjusted in the direction of the rotation axis S. The bracket 52 has, for example, an elongated hole 52a into which a screw used to fasten the bracket 52 to the screw hole portion 51 is inserted. The elongated hole 52a extends in the direction of the rotation axis S. This allows the screw hole portion 51 and the bracket 52 to be connected by a screw even if the position of the steering assist device 1 relative to the body frame 110 varies within the range of the length of the elongated hole 52a in the direction of the rotation axis S.

[0075] The steering assist device 1 configured in this manner transmits the torque output by the steering assist motor 30 to the motor shaft gear 41, the intermediate gear 43, and the torque transmission member 45 in that order. Thus, the steering assist device 1 outputs the torque of the steering assist motor 30 to the steering shaft 121.

[0076] Furthermore, the steering assist device 1 transmits the torque of the steering shaft 121 of the lean vehicle 100 in this order to the torque transmission member 45, the intermediate gear 43, and the motor shaft gear 41. Therefore, the steering assist device 1 outputs the torque of the steering assist motor 30 in response to the torque input from the steering shaft 121.

[0077] Furthermore, in the steering assist device 1, one end and the other end of the torque transmission member 45, which are spaced apart in the direction of the rotation axis, are supported by the case 20. In this case, the steering assist device 1 can support the torque transmission member 45 by the case 20 with higher rigidity than when the torque transmission member 45 is supported at one location via a bearing of the same size.

[0078] Furthermore, the case 20 supports the steering assist motor 30 and multiple rotating bodies in a state in which the rotational axis of the output shaft 30a of the steering assist motor 30 and the shaft of the intermediate gear 43 extend in the direction of the rotational axis of the torque transmission member 45. This allows the steering assist motor 30 and the torque transmission mechanism 40 to be supported close to the steering shaft 121. Therefore, the case 20 can suppress the moment generated in the torque transmission member 45. This maintains the torque transmission accuracy of the torque transmission mechanism 40 housed in the lean vehicle case 20, suppresses elastic deformation of the case 20 due to vibration in the up-and-down direction, and allows the steering assist device 1 to be easily assembled to the lean vehicle 100.

[0079] <Lean vehicle having steering assist device> Next, a lean vehicle 100 having a steering assist device 1 will be described with reference to Figures 2 to 5. Figure 2 is a side view of the steering assist device 1 and the lean vehicle 100. Figure 3 is a front view showing the steering assist device 1 and a pine-needle fork 120 of the lean vehicle 100. Figure 4 is a partial side view showing the steering assist device 1 and the pine-needle fork 120 of the lean vehicle 100. Figure 5 is a partial cross-sectional view showing a side view of the steering assist device 1 supported by a steering shaft 121 of the lean vehicle 100.

[0080] As shown in FIG. 2 , the lean vehicle 100 includes a body frame 110 , a pine needle fork 120 , a handlebar 127 , a seat 130 , a power unit 140 , a front wheel 150 , a rear wheel 160 , and a body cover 170 .

[0081] The body frame 110 supports the fork 120, the power unit 140, the seat 130, etc. The power unit 140 includes a power source such as an engine or an electric motor, and a transmission mechanism such as a transmission. In Figure 1, the body frame 110 is indicated by a dashed line.

[0082] The body frame 110 includes a head pipe 111 extending in the vertical direction, a front frame 112 extending rearward from the head pipe 111, and a rear frame 113 extending rearward from the rear end of the front frame 112. The head pipe 111 is disposed at the front of the lean vehicle 100. The steering assist device 1 is disposed around the head pipe 111.

[0083] The head pipe 111 is supported by a front frame 112. A steering shaft 121 included in a pine needle type fork 120 is inserted into the head pipe 111 so as to be able to rotate freely.

[0084] The front frame 112 extends rearward and downward from a front end connected to the head pipe 111. The rear frame 113 supports a seat 130 and a tail lamp (not shown).

[0085] 3, the pine needle fork 120 supports the front wheel 150. The pine needle fork 120 includes a steering shaft 121, a crown 122, a left fork portion 123 that supports the left end of the axle of the front wheel 150, and a right fork portion 125 that supports the right end of the axle of the front wheel 150.

[0086] The steering shaft 121 extends in the up-down direction of the lean vehicle 100. A crown 122 is fixed to the lower end of the steering shaft 121. A left fork portion 123 and a right fork portion 125 are connected to the crown 122. In other words, the crown 122 is a connecting portion that connects the left fork portion 123 and the right fork portion 125. Therefore, the steering shaft 121 supports the left fork portion 123 and the right fork portion 125. The left fork portion 123 has a left shock absorber 124. The right fork portion 125 has a right shock absorber 126.

[0087] The steering shaft 121 is supported rotatably about the axis of the head pipe 111 via bearings 115 held at both ends of the head pipe 111. The steering shaft 121 is fixed to the bearings 115 of the head pipe 111 by the pressing force of a lock nut 116 in the direction of the rotation axis S. In other words, the pine needle fork 120 is fixed to the body frame 110 in the direction of the rotation axis S and is supported rotatably about the axis of the head pipe 111.

[0088] A handle 127 extending in the vehicle width direction is attached to the upper end of the steering shaft 121 via the steering assist device 1, a torque sensor 61 (described later), and a steering angle sensor 62. The pine needle fork 120 is configured so that the front wheel 150 can be rotated about a rotation axis S by operating the handle 127.

[0089] The front wheel 150 is rotatably supported by the pine needle fork 120. The left end of the axle of the front wheel 150 is supported by a left shock absorber 124 of the left fork section 123. The right end of the axle of the front wheel 150 is supported by a right shock absorber 126 of the right fork section 125. The rear wheel 160 is supported by the rear frame 113. The rear wheel 160 is driven by power from the power unit 140 transmitted via a transmission member such as a chain.

[0090] 2, the body cover 170 is one of the exterior parts that cover the body frame 110, the pine fork 120, the steering assist device 1, etc. The body cover 170 includes a front cover 171, a pair of front fenders 172, a rear fender 173, and a leg shield 174.

[0091] The front cover 171 is located in front of the seat 130. The front cover 171 covers at least a part of the head pipe 111, the pine needle fork 120, and the steering assist device 1.

[0092] Each front fender 172 is disposed above the front wheel 150. Each front fender 172 is disposed below the front cover 171. The rear fender 173 is disposed above the rear wheel 160.

[0093] The leg shield 174 is disposed rearward of the head pipe 111. The leg shield 174 extends in the vertical direction. The leg shield 174 is disposed so as to be positioned in front of the vehicle relative to the legs of a user when the user is riding in the lean vehicle 100.

[0094] The front wheel 150 is positioned below the head pipe 111. The front wheel 150 is disposed below the front cover 171.

[0095] 4, in the lean vehicle 100, the steering assist device 1 is disposed in front of the head pipe 111 and behind the front cover 171. In other words, in the lean vehicle 100, the steering assist device 1 is disposed in a space covered by the front cover 171 in front of the head pipe 111.

[0096] The lean vehicle 100 supports the steering assist device 1 by a steering shaft 121. The steering assist device 1 is supported by the steering shaft 121 that extends upward from the upper end of the head pipe 111.

[0097] 5, the upper end of the steering shaft 121 is housed in a steering shaft insertion hole 45a of the torque transmission member 45. The torque transmission member 45 is fixed to the steering shaft 121 by being pressed against a lock nut 116 by the pressing force of a bolt 117 that is screwed in the direction of the rotation axis S. Therefore, the steering shaft 121 can rotate integrally with the torque transmission member 45.

[0098] A torque sensor 61 that detects the torque applied to the steering shaft 121 and a steering angle sensor 62 that detects the angular acceleration, angular velocity, etc. about the rotation axis S are disposed on the upper end of the torque transmission member 45 fixed to the steering shaft 121. Furthermore, the steering angle sensor 62 supports the steering wheel 127 via the steering wheel fixing member 114.

[0099] The lean vehicle 100 configured in this manner detects the torque applied to the steering shaft 121 due to the driver's operation of the steering wheel 127, and the angular acceleration of the steering shaft 121. In the lean vehicle 100, the steering assist device 1 transmits torque to the steering assist device 1 based on the detected torque, angular velocity, etc. of the steering shaft 121.

[0100] <Assembly of Steering Assist Device> Next, assembly of the steering assist device 1 to the lean vehicle 100 will be described with reference to Fig. 6. Fig. 6 is a partial cross-sectional view showing a side view of the steering assist device 1 being assembled to the steering shaft 121 of the lean vehicle 100.

[0101] 6, when the steering assist device 1 is installed in the lean vehicle 100, the handlebars 127 are removed from the steering shaft 121 of the pine needle fork 120 of the lean vehicle 100. The steering shaft 121 is supported on the head pipe 111 by a lock nut 116.

[0102] The steering assist device 1 is assembled to the lean vehicle 100 with the torque transmission mechanism 40 housed inside the case 20 and the steering assist motor 30 fixed thereto. The steering assist device 1 is disposed on the lean vehicle 100 so that the case 20 and the steering assist motor 30 are located in front of the head pipe 111.

[0103] First, the upper end of the steering shaft 121 is inserted into the steering shaft insertion hole 45a of the torque transmission member 45 supported by the case 20. The torque transmission member 45 is moved toward the head pipe 111 until one end thereof comes into contact with the lock nut 116. This maintains the position of the torque transmission member 45 in the direction of the rotation axis S. In other words, the position of the steering assist device 1 including the torque transmission member 45 in the direction of the rotation axis S is maintained.

[0104] Next, the bolt 117 is screwed into the upper end of the steering shaft 121 in the direction of the rotation axis S. The other end of the torque transmission member 45 is pressed by the bolt 117 in the direction of the rotation axis S. The torque transmission member 45 is fixed to the steering shaft 121 by the frictional force between the torque transmission member 45 and the bolt 117 and the frictional force between the torque transmission member 45 and the lock nut 116. The position of the steering assist device 1 supported by the lock nut 116 is determined relative to the head pipe 111 in the axial direction of the head pipe 111.

[0105] Next, a screw hole 51 of the steering assist motor 30 is connected to a bracket 52 of the body frame 110. The position of the steering assist device 1 fixed to the steering shaft 121 relative to the bracket 52 varies depending on the assembly state of the head pipe 111 and the steering shaft 121.

[0106] The screw hole portion 51 and the bracket 52 are connected by a screw at the position of the elongated hole 52a that corresponds to the position of the steering assist motor 30 relative to the head pipe 111. This allows the steering assist device 1 to suppress rotation about the rotation axis S relative to the head pipe 111.

[0107] Next, the torque sensor 61 and the steering angle sensor 62 are fixed to the upper end of the torque transmission member 45. Furthermore, the steering wheel 127 is fixed to the torque sensor 61 and the steering angle sensor 62 by the steering wheel fixing member 114. In this way, the steering assist device 1 is incorporated into the lean vehicle 100.

[0108] The steering assist device 1 is supported on a steering shaft 121 of a pine-needle fork 120 (see FIG. 3) via a torque transmission member 45. The pine-needle fork 120 does not have left and right fork portions, a top bridge, a bottom bridge, etc. located around the steering shaft 121, so the steering assist device 1 can be easily assembled.

[0109] Furthermore, the steering assist device 1 can be assembled to the lean vehicle 100 by accommodating the steering shaft 121 of the pine needle fork 120 in the steering shaft insertion hole 45a of the torque transmission member 45 and fixing it with the bolt 117. In this manner, the steering assist device 1 is configured to be assembled to the steering shaft 121. Therefore, the steering assist device 1 can be assembled to the lean vehicle 100 more easily than, for example, when the case 20 is assembled to the head pipe 111 and the torque transmission member 45 is assembled to the steering shaft 121.

[0110] The case 20, the steering assist motor 30, and the torque transmission mechanism 40 are supported by the steering shaft 121 via a torque transmission member 45. In this case, the case 20 is supported by the torque transmission member 45 without coming into contact with the head pipe 111.

[0111] Therefore, by being supported by the steering shaft 121, the case 20 is not elastically deformed by force from the body frame 110 due to processing errors, assembly errors, etc., compared to when the case 20 is supported by, for example, the head pipe 111 and the steering shaft 121, which are different members. Therefore, the steering assist device 1 can maintain the torque transmission accuracy of the torque transmission mechanism 40 when assembled to the steering shaft 121.

[0112] [Embodiment 2] <Overall configuration of steering assist device> A steering assist device 10 according to embodiment 2 of the steering assist device of the present invention will be described using Figure 7. 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.

[0113] As shown in FIG. 7 , the steering assist device 10 includes a case 20 , a steering assist motor 30 , a torque transmission mechanism 40 , and a rotation prevention portion 50 .

[0114] The torque transmission mechanism 40 includes a motor shaft gear 41 , an intermediate gear 43 , and a torque transmission member 450 that is a gear that transmits torque to the steering shaft 121 .

[0115] The torque transmission member 450 has a steering shaft insertion hole 450a, which is a through hole capable of accommodating the steering shaft 121. Therefore, the torque transmission member 450 is configured as a gear with the rotation axis S as its rotation axis.

[0116] Furthermore, one end of the torque transmission member 450 in the rotational axis direction has a head pipe housing portion 450b that can house the head pipe 111. The head pipe housing portion 450b is a recess that extends in the rotational axis direction of the torque transmission member 450. The head pipe housing portion 450b has a size that allows the head pipe 111 to be housed therein without coming into contact with the head pipe 111.

[0117] One end of the torque transmission member 450 in the rotational axis direction is rotatably supported by the lower case portion 21 via a bearing 46a. The other end of the torque transmission member 450 in the rotational axis direction is rotatably supported by the upper case portion 22 via a bearing 46b. Thus, the torque transmission member 450 is supported by the case 20 so as to be rotatable about the rotational axis.

[0118] <Assembly of the Steering Assist Device> The upper end of the steering shaft 121 is inserted into the steering shaft insertion hole 450a of the torque transmission member 450 supported by the case 20. The torque transmission member 450 is moved toward the head pipe 111 until the bottom of the head pipe housing portion 450b comes into contact with the lock nut 116. At this time, the lock nut 116 and the upper end of the head pipe 111 are positioned inside the case 20. In other words, the steering assist device 10 is positioned so as to overlap with the head pipe 111 when viewed in the front-to-rear or left-to-right direction of the lean vehicle 100. Therefore, the steering assist device 10 can reduce the vertical size of the space occupied by the head pipe 111 and the case 20.

[0119] Furthermore, when viewed in the left-right direction, the steering assist device 10 can increase the distance between one end and the other end in the direction of the rotation axis S supported by the case 20 depending on the length of the portion that overlaps with the head pipe 111. This improves the support rigidity of the steering assist device 10 in the up-down direction.

[0120] This allows the steering assist device 10 to be easily assembled to the lean vehicle 100, maintaining the torque transmission accuracy of the torque transmission mechanism 40 housed in the case 20 while suppressing elastic deformation of the case 20 due to vertical vibrations.

[0121] 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.

[0122] In each of the above-described embodiments, the steering assist device 1, 10 is supported on the steering shaft 121 of the lean vehicle 100 having a power source. However, the steering assist device may also be supported on the steering column of a bicycle that does not have a power source.

[0123] In each of the above-described embodiments, the steering assist device 1, 10 is located in front of the steering shaft 121. However, the steering assist device may be located behind the steering shaft.

[0124] In each of the above-described embodiments, the torque transmission member 45, 450 of the steering assist device 1, 10 is fixed to the steering shaft 121 by frictional force generated by a pressing force in the direction of the rotation axis S. However, the torque transmission member may be fixed to the steering shaft by a configuration other than frictional force generated by a pressing force in the axial direction of the steering shaft. The torque transmission member may be fixed to the spline shaft by, for example, a key, a tapered fit, a spline fit, or the like.

[0125] In each of the above-described embodiments, the steering assist device 1, 10 is provided in a lean vehicle 100 having a pine-needle type fork 120. However, the steering assist device may also be provided in a lean vehicle having a so-called torii type fork in which the left and right fork portions are connected by a top bridge and a bottom bridge, and the top bridge and the bottom bridge support a steering shaft.

[0126] In each of the above-described embodiments, the anti-rotation portion 50 is configured to connect the bracket 52 to the screw hole portion 51 with a screw. However, the anti-rotation portion does not have to be configured to connect the screw hole portion and the bracket with a screw. For example, the anti-rotation portion may be configured to insert a pin into a pin hole.

[0127] In each of the above-described embodiments, the anti-rotation portion 50 is configured to be able to adjust the connection position between the screw hole portion 51 and the bracket 52 in the direction of the rotation axis S by connecting the screw hole portion 51 and the bracket 52 using the elongated hole 52a of the bracket 52. However, the position adjustment of the anti-rotation portion does not have to be configured to be performed using the elongated hole of the bracket. The anti-rotation portion may be, for example, a combination of a groove extending in the direction of the rotation axis S and a pin inserted into the groove.

[0128] REFERENCE SIGNS LIST 1, 10 Steering assist device 20 Case 21 Lower case portion 21a Motor shaft insertion hole 21b Lower case portion torque transmission member insertion hole 22 Upper case portion 22b Upper case portion torque transmission member insertion hole 30 Steering assist motor 30a Output shaft 40 Torque transmission mechanism 41 Motor shaft gear 43 Intermediate gear 45, 450 Torque transmission member 45a, 450a Steering shaft insertion hole 46a, 46b Bearing 50 Anti-rotation portion 51 Threaded hole portion 52 Bracket 52a Elongated hole 61 Torque sensor 62 Steering angle sensor 100 Lean vehicle 110 Body frame 111 Head pipe 112 Front frame 113 Rear frame 114 Handle fixing member 42, 44, 115 Bearing 116 Lock nut 117 Bolt 120 Pine needle fork 121 Steering shaft 122 Crown 123 Left fork section 124 Left shock absorber 125 Right fork section 126 Right shock absorber 127 Handlebars 130 Seat 140 Power unit 150 Front wheel 160 Rear wheel 170 Body cover 171 Front cover 172 Front fender 173 Rear fender 174 Leg shield 450b Head pipe housing S Rotation axis of steering shaft

Claims

1. A steering assist device having: a steering assist motor; a torque transmission mechanism that transmits torque output by the steering assist motor or torque input to the steering assist motor; and a case that supports the steering assist motor and houses the torque transmission mechanism, the steering assist device having a pine-needle fork including a left fork section that supports a left end of a front wheel axle, a right fork section that supports a right end of the front wheel axle, and a steering shaft that extends upward from a connecting section that connects an upper end of the left fork section and an upper end of the right fork section, the steering shaft being supported on a head pipe of a vehicle body frame so as to be rotatable about the axis of the head pipe, the torque transmission mechanism including: a torque transmission member that houses the steering shaft and is fixed to the steering shaft by a pressing force in the direction of the rotational axis of the steering shaft, the case being supported so as to be rotatable about the rotational axis by one end and the other end of the torque transmission member in the direction of the rotational axis without coming into contact with the head pipe, the steering assist motor being A steering assist device that outputs torque to a steering shaft of the lean vehicle via the torque transmission mechanism, or receives torque from the steering shaft via the torque transmission mechanism.

2. A steering assist device as described in claim 1, wherein at least one of the steering assist motor and the case has a rotation prevention portion that prevents the case from rotating around the rotation axis of the steering shaft, and the rotation prevention portion is connected to the body frame of the lean vehicle and is configured so that the connection position with the body frame can be adjusted in the direction of the rotation axis of the steering shaft.

3. A steering assist device as described in claim 1 or 2, wherein the torque transmission mechanism has a plurality of rotating bodies and is supported by the case so that the rotation axes of the plurality of rotating bodies extend in the direction of the rotation axis of the steering shaft, and the steering assist motor is supported by the case so that its output shaft extends in the direction of the rotation axis of the plurality of rotating bodies.

4. A steering assist device according to any one of claims 1 to 3, wherein a portion of the head pipe is positioned inside the case.

5. A lean vehicle having a pine-needle fork including a left fork section supporting the left end of the front wheel axle, a right fork section supporting the right end of the front wheel axle, and a steering shaft extending upward from a connecting section connecting the upper end of the left fork section and the upper end of the right fork section, and supporting the steering shaft rotatably around the axis of the head pipe, the lean vehicle having a steering assist device described in any one of claims 1 to 4, wherein the steering shaft is accommodated in a torque transmission member of the steering assist device and is fixed to the steering shaft by a pressing force in the direction of the rotation axis of the steering shaft without contacting the head pipe, and configured to be able to output torque from the steering assist device to the steering shaft.

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