Tilting vehicle

Abstract

A tilting vehicle according to an embodiment comprises a plurality of wheels that are provided to a vehicle body and that include at least one steered wheel, a tilting mechanism that relatively tilts the vehicle body toward the inside of a turn in relation to the ground, a steering part that is capable of performing a mechanical turning operation in the lateral direction of the vehicle body, a transmission part that transmits a steering angle input by the steering part to the steered wheel, and a low transmission member that is interposed in the transmission part and that lowers the transmission rate of the steering angle to the steered wheel.

Description

Lean vehicle

[0001] The present disclosure relates to lean vehicles.

[0002] In recent years, various powered vehicles for small passengers have been put into practical use as a convenient means of transportation. In such vehicles, miniaturization is achieved by shortening the length in the front-to-rear direction of the vehicle and narrowing the vehicle width. One example of such a vehicle is a lean-type vehicle, which has a function of intentionally tilting the body in the vehicle width direction to improve vehicle stability during cornering.

[0003] However, if the centrifugal force during cornering is large, the vehicle posture may become unstable even when the vehicle body is tilted.

[0004] Tetsunori Haraguchi and two others, "Inner Wheel Float Characteristics During Sudden Steering of an Inward-Leaning Personal Mobility Vehicle," Proceedings of the Society of Automotive Engineers of Japan Annual Conference, May 21, 2018, Spring 2018, ROMBUN No. 124. Tetsuya Kaneko and two others, "Vehicle Response Characteristics During Sudden Steering of a Personal Mobility Vehicle with a Lean Mechanism and a Study on Methods for Improving Its Performance," Proceedings of the Society of Automotive Engineers of Japan, Society of Automotive Engineers of Japan, 2019, Vol. 50, No. 3, pp. 796-801.

[0005] Therefore, one of the problems that the embodiments of the present invention aim to solve is to provide a lean vehicle that can improve the stability of the vehicle body during cornering with a simple configuration.

[0006] The lean vehicle of the embodiment comprises a plurality of wheels including at least one steering wheel provided on a vehicle body, a lean mechanism that tilts the vehicle body toward the inside of a turn relative to the ground, a steering unit capable of mechanically turning the vehicle body left and right, a transmission unit that transmits the steering angle input to the steering unit to the steering wheel, and a low transmission member interposed in the transmission unit that reduces the transmission rate of the steering angle transmitted from the steering unit to the steering wheel, and when a steering angle that exceeds the allowable minimum turning radius of the vehicle body is input from the steering unit, the low transmission member reduces the transmission rate of the steering angle so that the turning radius of the vehicle body is within the range of the allowable minimum turning radius.

[0007] The lean vehicle of the embodiment can improve the stability of the vehicle body during cornering with a simple configuration.

[0008] FIG. 1 is a schematic side view showing an example of the configuration of a lean vehicle according to an embodiment. FIG. 2 is an exemplary schematic view of the lean vehicle according to the embodiment when viewed from the rear side. FIG. 3 is another exemplary schematic view of the lean vehicle according to the embodiment when viewed from the rear side. FIG. 4 is an exemplary perspective view of a front wheel unit, a steering shaft, and a handle when the lean vehicle according to the embodiment is viewed from the left front. FIG. 5 is a cross-sectional view showing an example of the configuration of a low-rigidity member interposed in the steering shaft of the lean vehicle according to the embodiment. FIG. 6 is a perspective view showing an example of the configuration of a low-rigidity member interposed in the steering shaft of the lean vehicle according to the embodiment. FIG. 7 is a schematic diagram illustrating an example of the operation of the lean vehicle according to the embodiment when turning. FIG. 8 is a schematic diagram illustrating an example of the operation of the lean vehicle according to the embodiment when turning. FIG. 9 is a block diagram showing an example of the functional configuration of a control device provided in the lean vehicle according to the embodiment. FIG. 10 is a block diagram showing an example of the procedure of lean control processing of the control device provided in the lean vehicle according to the embodiment. FIG. 11 is a schematic diagram showing an example of lean control of the lean vehicle according to the embodiment. Fig. 12 is a schematic diagram showing an example of lean control for a lean vehicle according to a modified embodiment, Fig. 13 is a schematic diagram showing another example of lean control for a lean vehicle according to a modified embodiment, and Fig. 14 is a schematic diagram showing yet another example of lean control for a lean vehicle according to a modified embodiment.

[0009] Hereinafter, embodiments and modifications of the present disclosure will be described with reference to the drawings. The configurations of the embodiments and modifications described below, as well as the actions and effects brought about by the configurations, are merely examples and are not limited to the contents described below.

[0010] 1 is a schematic side view showing an example of the configuration of a lean vehicle 10 according to an embodiment. The lean vehicle 10 according to the embodiment is, for example, a small one-seater vehicle, and the running stability of the lean vehicle 10 during cornering, such as turning right or left, is improved by tilting the body 12 of the lean vehicle 10 inwardly of the turn using a lean unit 60 (described later).

[0011] 1, the lean vehicle 10 is placed on a horizontal ground GL and is not tilted. In FIG. 1, the +X direction, −X direction, +Y direction, −Y direction, +Z direction, and −Z direction are shown.

[0012] The ±X direction and ±Y direction are both horizontal directions. The +X direction is the forward direction of the lean vehicle 10, i.e., the forward direction. The -X direction is the opposite direction of the +X direction and is the rearward direction of the lean vehicle 10, i.e., the backward direction. The +Y direction is the right direction as seen from the lean vehicle 10 traveling in the +X direction. The -Y direction is the opposite direction of the +Y direction and is the left direction as seen from the lean vehicle 10 traveling in the +X direction.

[0013] The ±Z directions are directions perpendicular to the horizontal ground GL, i.e., perpendicular to the ±X and ±Y directions. The +Z direction is the vertically upward direction. The −Z direction is the opposite direction of the +Z direction and is the vertically downward direction, i.e., the direction of gravity. As will be described later, the up-down direction based on the body 12 of the lean vehicle 10 may not necessarily coincide with the ±Z directions.

[0014] As shown in FIG. 1, the lean vehicle 10 of the embodiment includes a vehicle body 12, a front wheel unit 16F, a rear wheel unit 16R, a steering shaft 50, a handle 58, a drive motor 40, a lean unit 60, and the like.

[0015] The lean vehicle 10 of this embodiment is configured as a four-wheel vehicle including a pair of front wheels 14F and a pair of rear wheels 14R that are provided at the front and rear positions of a vehicle body 12 and spaced apart from each other in the vehicle width direction, i.e., the +Y direction and the −Y direction. As will be described later, the pair of front wheels 14F are included in a front wheel unit 16F, and the pair of rear wheels 14R are included in a rear wheel unit 16R.

[0016] In addition, in the lean vehicle 10 of this embodiment, the front wheels 14F are configured as steering wheels that change the direction of travel of the lean vehicle 10, and the rear wheels 14R are configured as drive wheels that drive the vehicle body 12 using power from the drive motor 40.

[0017] However, the number of wheels that the lean vehicle 10 may have is not limited to four. The lean vehicle 10 may be a three-wheel vehicle, for example, having one front wheel 14F in the center in the vehicle width direction and a pair of rear wheels 14R spaced apart in the vehicle width direction.

[0018] Alternatively, the lean vehicle 10 may be configured with at least a pair of wheels spaced apart in the vehicle width direction on the side equipped with the lean unit 60 described later, and may be provided with multiple wheels, one each in the front and rear directions of the vehicle body 12, in addition to such a pair of wheels, or may be provided with three or more pairs of wheels spaced apart in the vehicle width direction, including a pair of wheels equipped with the lean unit 60.

[0019] Furthermore, it is optional to determine which of the multiple wheels, such as the front wheels 14F and the rear wheels 14R, that the lean vehicle 10 may have as steered wheels and which as driven wheels. In the example of Figure 1, the rear wheels 14 may be steered wheels instead of the front wheels 14F, and the front wheels 14F may be driven wheels instead of or in addition to the rear wheels 14R.

[0020] 1 is a view of the lean vehicle 10 as seen from the left side, and for the sake of structural explanation, the left front wheel 14F and rear wheel 14R are not shown.

[0021] The vehicle body 12 includes a bottom 12a, a front wall 12c connected to the +X direction side of the bottom 12a, a front portion 12f extending in the +X direction from the upper end of the front wall 12c, a rear wall 12b connected to the −X direction side of the bottom 12a, and a rear portion 12r extending in the −X direction from the upper end of the rear wall 12b. The vehicle body 12 has, for example, a metal frame and panels fixed to the frame.

[0022] The vehicle body 12 is equipped with an accelerator pedal 21, a brake pedal 22, a steering wheel 58, a steering shaft 50, a seat 18, a direction sensor 28, a control device 30, and the like.

[0023] The accelerator pedal 21 and the brake pedal 22 are provided, for example, on the bottom of the front wall 12c of the vehicle body 12. The accelerator pedal 21 drives and rotates the rear wheels 14R, which are drive wheels, while adjusting the output state of the drive motor 40 by adjusting the amount of depression by the driver. The brake pedal 22 adjusts the braking state of mechanical brakes and the like provided on the front wheels 14F and rear wheels 14R by adjusting the amount of depression by the driver.

[0024] The handlebars 58 are attached to the front portion 12f of the vehicle body 12. The handlebars 58 are rotatable to the right and left, allowing a desired steering angle to be input to the front wheels 14F, which are steered wheels, to turn the vehicle body 12 to the right or left.

[0025] However, there are no particular limitations on the form of the handle 58. That is, the handle 58 may be a circular steering wheel, a bar handle extending horizontally, or an upright stick- or lever-shaped tiller handle, etc.

[0026] In this specification, the rotational position indicating straight-ahead travel is also referred to as the straight-ahead rotational position, and the rotational angle of the handle 58 is also referred to as the input angle. Furthermore, "input angle = zero" indicates straight-ahead travel, "input angle > zero" indicates a right turn, and "input angle < zero" indicates a left turn. Furthermore, the handle 58 has a stopper (not shown) that limits the rotational angle of the handle 58.

[0027] The handle 58 in the embodiment is an example of a steering unit that can perform a mechanical turning operation in the left and right directions of the vehicle body 12 .

[0028] The steering shaft 50 connects the steering wheel 58 and the front wheel unit 16F, and mechanically transmits the steering angle input to the steering wheel 58 to the front wheels 14F, which are steered wheels included in the front wheel unit 16F. That is, the steering shaft 50 rotates rightward or leftward around the extension direction of the steering shaft 50 as the axis of rotation in response to the driver's operation of the steering wheel 58, and the front wheels 14F also turn rightward or leftward accordingly.

[0029] In this manner, in this embodiment, the entire steering shaft 50 serves as a transmission path for transmitting the steering angle input to the handle 58 to the front wheels 14F.

[0030] The steering shaft 50 is attached to the vehicle body 12 with its upper end tilted toward the rear of the vehicle body 12, i.e., in the −X direction. When viewed from the side of the vehicle body 12, the axis in the extension direction of the steering shaft 50 and a perpendicular line (−Z direction) extending from the axis of the steering shaft 50 form a predetermined angle δ, for example.

[0031] Furthermore, the steering shaft 50 has an upper shaft 54 ​​whose upper end is connected to the handlebars 58, a lower shaft 52 whose lower end is connected to the front wheel unit 16F, and a low-rigidity member 56 that connects the lower end of the upper shaft 54 ​​to the upper end of the lower shaft 52. In other words, the low-rigidity member 56 is interposed midway along the steering shaft 50. In addition, the upper shaft 54 ​​is provided with an angle sensor 23 that detects the rotation angle of the handlebars 58.

[0032] The low-rigidity member 56 may be, for example, a rubber spring or a metal spring. By providing the low-rigidity member 56 midway along the steering shaft 50, the overall rigidity of the steering shaft 50 is reduced, thereby suppressing changes in the direction of the front wheels 14F relative to the input angle from the handlebars 58. Strictly speaking, the rigidity of the steering shaft 50 refers to torsional rigidity.

[0033] Therefore, even if the input angle from the steering wheel 58 is too large, the turning radius of the lean vehicle 10 does not become too small, and the running stability of the lean vehicle 10 when turning can be improved.

[0034] As described above, the connection between the handlebars 58 and the steering mechanism that steers the front wheels 14F is realized by a mechanical steering mechanism.

[0035] The steering shaft 50 is an example of a transmission unit that transmits the steering angle input to the steering wheel 58 to the front wheels 14F. The low-rigidity member 56 is an example of a low-rigidity transmission member that reduces the transmission rate of the steering angle from the steering wheel 58 to the front wheels 14F.

[0036] The seat 18 is fixed onto the bottom 12a of the vehicle body 12. The seat 18 includes a seat surface 18a and a backrest 18b so that the driver can adjust the depression of the accelerator pedal 21 and the brake pedal 22 and steer the steering wheel 58 while seated.

[0037] The direction sensor 28 is fixed to, for example, the rear wall portion 12b of the vehicle body 12. The direction sensor 28 is a sensor that includes an acceleration sensor 25, a gyro sensor 24, and a control unit 20, and measures the roll angle and yaw angular velocity of the vehicle body 12.

[0038] The acceleration sensor 25 is a sensor that detects acceleration in any direction, such as a three-axis acceleration sensor. The direction of acceleration detected by the acceleration sensor 25 is also referred to as the detection direction. When the lean vehicle 10 is stopped, the detection direction coincides with the −Z direction.

[0039] The gyro sensor 24 is a sensor that detects an angular velocity around a rotation axis in any direction, and is, for example, a three-axis angular velocity sensor.

[0040] The control unit 20 determines the roll angle and the yaw angular velocity using signals from the acceleration sensor 25, the gyro sensor 24, and a signal from a speed sensor 26 disposed in, for example, the front wheel unit 16F. The control unit 20 is, for example, a data processing device including a computer.

[0041] These sensors constitute an inertial measurement unit (IMU), which can acquire the actual lean angle, which is the actual tilt state of the lean vehicle 10 while it is running.

[0042] The control device 30 is, for example, a data processing device including a computer, and is fixed to, for example, the bottom 12a of the vehicle body 12. The control device 30 controls each part of the lean vehicle 10 to control the lean of the vehicle body 12 when the lean vehicle 10 is turning.

[0043] Although not shown in the drawings, other components such as a roof, headlights, etc. may be fixed to the vehicle body 12 in addition to the components described above.

[0044] The rear wheel unit 16R is disposed on the −X direction side of the rear wall portion 12b of the vehicle body 12 and has a pair of rear wheels 14R, which are drive wheels. Thus, the rear wheel unit 16R functions as a drive wheel unit. The rear wheels 14R are driven to rotate by a power transmission mechanism using, for example, a drive motor 40 and a speed reduction mechanism 42. However, the method of driving the rear wheels 14R is not limited to this, and the rear wheels 14R may also be driven to rotate by, for example, incorporating an in-wheel motor or the like in the rear wheels 14R.

[0045] The front wheel unit 16F is configured with a pair of front wheels 14F that are non-drive wheels and are steerable wheels that can rotate in the vehicle width direction of the lean vehicle 10, i.e., in the +Y direction and the -Y direction, and functions as a steering wheel unit.

[0046] A rear coupling device 38R that couples the rear wheel unit 16R to the vehicle body 12 is connected to the rear wheel unit 16R. The rear coupling device 38R is provided with a rear coupling bar 46R that couples the rear wheel unit 16R to the vehicle body 12, as well as a power transmission mechanism such as a drive motor 40 and a reduction mechanism 42, and a lean unit 60 that tilts the vehicle body 12 toward the inside of a turn.

[0047] The rear connecting bar 46R has an end 46Ra on the vehicle body 12 side rotatably connected to the vehicle body 12, and an end 46Rb on the rear wheel unit 16R side fixed to the rear wheel unit 16R.

[0048] Furthermore, a rear spring member 48, which functions as a suspension, is interposed between the middle portion of the rear connecting bar 46R and the end portion 46Ra on the vehicle body 12 side. As a result, the rear wheel unit 16R having the rear wheel 14R and the vehicle body 12 can move relative to each other in the vertical direction, i.e., rotate, and when traveling over uneven ground GL, for example, the rear wheel unit 16R mainly displaces vertically, suppressing the transmission of vertical vibrations to the vehicle body 12 side.

[0049] The drive motor 40 has its rotation controlled in accordance with the depression amount of the accelerator pedal 21, and drives the rear wheel 14R to rotate via a speed reduction mechanism 42. A battery 44 supplies power to the drive motor 40, the lean unit 60, and various devices mounted on the lean vehicle 10. Well-known configurations can be used for the power transmission mechanism using the drive motor 40 and the speed reduction mechanism 42, the battery 44, etc., and detailed description thereof will be omitted.

[0050] The lean unit 60 of the embodiment drives the rear wheels 14R of the rear wheel unit 16R so as to move the inside wheel of the turning upward and the outside wheel of the turning downward. This allows the body 12 to lean toward the inside of the turning when the lean vehicle 10 turns. The detailed configuration of the lean unit 60 will be described later.

[0051] The lean unit 60 is an example of a lean mechanism that tilts the vehicle body 12 toward the inside of a turn relative to the ground.

[0052] The load of the vehicle body 12 of the lean vehicle 10 of this embodiment is distributed more to the rear wheel unit 16R side, which is equipped with the lean unit 60, than to the front wheel unit 16F side, which does not have the lean unit 60 (front wheel load Wf < rear wheel load Wr). As a result, it is possible to transmit more of the lean motor torque generated by the lean unit 60 to the road surface (ground surface GL), thereby improving the posture control performance of the lean vehicle 10.

[0053] Furthermore, in the lean vehicle 10, it is preferable to configure the ground contact points of the front wheels 14F, which are steered wheels, to be located a length Q behind, or in the −X direction, the axis in the extension direction of the steering shaft 50, i.e., the axis Ax along which the steering shaft is extended. The length Q is also referred to as the trail length. By appropriately setting this length Q, it is possible to obtain a lean vehicle 10 that has the desired straight-line stability and turning performance.

[0054] A front coupling mechanism 38F that couples the front wheel unit 16F to the vehicle body 12 is connected to the front wheel unit 16F. The front coupling mechanism 38F has a front coupling bar 46F that couples the front wheel unit 16F to the vehicle body 12. An end 46Fa of the front coupling bar 46F on the vehicle body 12 side is fixed to the vehicle body 12, and an end 46Fb on the front wheel unit 16F side is fixed to the front wheel unit 16F.

[0055] (Configuration Example of Rear Wheel Unit) Next, the rear wheel unit 16R mounted on the lean vehicle 10 and the configuration around the rear wheel unit 16R will be described in detail with reference to FIGS. 2 and 3. FIG.

[0056] 2 is an exemplary schematic diagram of the lean vehicle 10 according to the embodiment, viewed from the rear. More specifically, FIG. 2 shows the lean vehicle 10 in a state where it is not tilted in the vehicle width direction. Note that in FIG. 2, power transmission mechanisms such as the drive motor 40 and the reduction mechanism 42 are omitted from illustration to facilitate understanding of the behavior of the lean vehicle 10.

[0057] As described above, the rear coupling device 38R couples the two rear wheels 14R to the vehicle body 12 via the rear coupling bar 46R. However, in FIG. 2, the rear coupling bar 46R is located behind the vertical link member 622b (described later), i.e., in the depth direction of the page, and is not shown.

[0058] 2, the rear connecting device 38R includes a lean unit 60. The lean unit 60 includes a rear link mechanism 620 including horizontal link members 621a, 621b and vertical link members 622a, 622b, 622c, etc., and a lean motor 610 attached to the rear link mechanism 620 and functioning as a lean drive unit.

[0059] The horizontal link members 621a and 621b and the vertical link members 622a, 622b, and 622c included in the rear link mechanism 620 are configured as parallel links that maintain the two rear wheels 14R parallel to each other.

[0060] The three vertical link members 622a, 622b, 622c are aligned in this order from the -Y direction to the +Y direction at a position between the two rear wheels 14R, and extend parallel to the vertical direction when the lean-mounted vehicle 10 is standing upright without tilting on the horizontal ground GL, i.e., on the ground GL perpendicular to the vertical +Z direction. The two lateral link members 621a, 621b are aligned in this order from the +Z direction to the -Z direction at a position between the two rear wheels 14R, and extend parallel to the horizontal direction when the lean-mounted vehicle 10 is standing upright without tilting on the horizontal ground GL, i.e., on the ground GL perpendicular to the ±Z directions.

[0061] The two vertical link members 622a, 622c and the two horizontal link members 621a, 621b form a parallelogram link mechanism. The vertical link member 622b connects the central portions of the two horizontal link members 621a, 621b. The vertical link members 622a, 622b, 622c and the horizontal link members 621a, 621b are made of, for example, metal.

[0062] Furthermore, the vertical link member 622a and the horizontal link member 621b are rotatably connected by a bearing 623a. The vertical link member 622b and the horizontal link member 621b are rotatably connected by a bearing 623b. The vertical link member 622c and the horizontal link member 621b are rotatably connected by a bearing 623c. Other link members are also rotatably connected to one another by bearings in the same manner.

[0063] The rotation axes of the bearings 623a, 623b, 623c, etc. that connect the link members extend from the −X direction toward the +X direction. Therefore, in the lean vehicle 10 of this embodiment, the rotation axes of the bearings 623a, 623b, 623c, etc. are parallel to the ±X directions. Two linked link members can rotate relatively around the rotation axis within a predetermined angular range. The angular range in which the link members can rotate is set to, for example, a range less than 180°.

[0064] The lean motor 610 is a drive device configured to drive the rear link mechanism 620, and is, for example, an electric motor. The lean motor 610 is connected, for example, to the vertical link member 622b and the upper horizontal link member 621a. The lean motor 610 and the vertical link member 622b may be connected via a gear. Also, the lean motor 610 and the horizontal link member 621a may be connected via a gear.

[0065] The lean motor 610 rotates the lateral link member 621a relative to the longitudinal link member 622b. As a result, the rear wheel 14R tilts toward the inside of the turn, i.e., to the right or left in the vehicle width direction, and the vehicle body 12 also tilts toward the inside of the turn. This tilting motion is also called a roll motion. The torque generated by the lean motor 610 and that rotates the lateral link member 621a to roll the vehicle body 12 is also called a lean motor torque.

[0066] In this manner, control can be achieved to tilt the rear wheel unit 16R and the vehicle body 12 toward the inside of a turn relative to the ground GL. However, the lean motor 610 may be fixed to the rear wheel unit 16R, and the output side of the lean motor 610, i.e., the rotary shaft side, may be connected to the vehicle body 12. In this case, by tilting the rear wheel unit 16R and the vehicle body 12 relative to each other, it may be possible to tilt only the vehicle body 12 toward the inside of a turn relative to the ground GL while keeping the rear wheel unit 16R upright with respect to the ground GL.

[0067] As described above, the example in Figure 2 shows the lean-mounted vehicle 10 in an upright position. When the horizontal link member 621a is perpendicular to the vertical link member 622b, the rear wheel 14R stands upright relative to the horizontal ground surface GL. Therefore, the entire lean-mounted vehicle 10, including the vehicle body 12, also stands upright relative to the ground surface GL.

[0068] Here, the upward direction of the vehicle body 12 of the lean vehicle 10 relative to the vehicle body 12 is defined as the vehicle body upward direction +Zv. When the lean vehicle 10 is not tilted, the vehicle body upward direction +Zv coincides with the +Z direction, which is the opposite direction to the direction of gravity.

[0069] The rear link mechanism 620 also has the function of reducing vertical vibrations that are applied to the vehicle body 12 due to unevenness of the ground surface GL.

[0070] That is, when the lean vehicle 10 is traveling straight on uneven ground GL, the rear wheel 14R is displaced in the vertical direction due to the vertical translation action of the rear link mechanism 620, and the rear connecting bar 46R and the rear spring member 48 cooperate to enable the rear wheel unit 16R and the rear link mechanism 620 to move (pivot) relative to the vehicle body 12 in the vertical direction. As a result, the transmission of vertical vibrations to the vehicle body 12 is reduced, which can contribute to improved driving stability.

[0071] Figure 3 is another exemplary schematic diagram of the lean vehicle 10 according to the embodiment, as viewed from the rear. More specifically, Figure 3 shows the lean vehicle 10 leaning toward the inside of a turn. The inside of the turn of the lean vehicle 10 in Figure 3 is the +Y direction, that is, the rightward direction on the page. Note that, in Figure 3 as well, power transmission mechanisms such as the drive motor 40 and the reduction mechanism 42 are omitted from illustration to make it easier to understand the behavior of the lean vehicle 10.

[0072] 3, when the lean vehicle 10 turns, a centrifugal force acting toward the outside of the turn (-Y direction) is generated in the lean vehicle 10. In such a case, the vehicle body 12 tilts toward the inside of the turn (+Y direction) to resist this centrifugal force.

[0073] However, if the centrifugal force becomes large and the vehicle body 12 begins to swing toward the outside of the turn, stability decreases. Therefore, in order to continue smooth cornering, it is necessary to intentionally tilt the lean vehicle 10 toward the inside of the turn. Therefore, the rear link mechanism 620 uses the lean motor 610 to intentionally tilt the lean vehicle 10 toward the inside of the turn, thereby improving the posture stability of the lean vehicle 10 during cornering.

[0074] More specifically, when the lean vehicle 10 turns, the vertical link member 622b rotates clockwise relative to the horizontal link member 621a, causing the upper end of the rear wheel 14R and the vehicle body 12 to tilt in the +Y direction relative to the ground GL, starting from the lower end of the rear wheel 14R that is in contact with the ground GL. This makes it possible to balance the centrifugal force generated in the outward direction of the turn.

[0075] At this time, the vehicle body upward direction +Zv is inclined toward the +Y direction with respect to the +Z direction. Hereinafter, the angle between the +Z direction and the vehicle body upward direction +Zv when viewing the lean vehicle 10 from the rear side will be referred to as the inclination angle Ar. The inclination angle Ar of the vehicle body 12 corresponds to the roll angle of the vehicle body 12, and is also the inclination angle Ar (roll angle) of the lean vehicle 10. Furthermore, "Ar > zero" indicates inclination toward the +Y direction, and "Ar < zero" indicates inclination toward the -Y direction.

[0076] When the lean vehicle 10 is viewed from the rear, the angle of the extension direction of the vertical link member 622b relative to the extension direction of the lateral link member 621a is referred to as the rear control angle ACr of the rear link mechanism 620.

[0077] "ACr = zero" indicates that the vertical link member 622b is perpendicular to the horizontal link member 621a. "ACr > zero" indicates that the vertical link member 622b has rotated clockwise relative to the horizontal link member 621a from the "ACr = zero" state. Although not shown, "ACr < zero" indicates that the vertical link member 622b has rotated counterclockwise relative to the horizontal link member 621a from the "ACr = zero" state.

[0078] When the lean vehicle 10 is positioned on a horizontal ground surface GL, that is, a ground surface GL perpendicular to the ±Z direction, the rear control angle ACr is approximately the same as the lean angle Ar.

[0079] The rear link mechanism 620 has a stopper (not shown) that limits the rear control angle ACr between the horizontal link member 621 a and the vertical link member 622 b, thereby preventing the vehicle body 12 from tilting to the extent that it becomes difficult to maintain the balance of the vehicle body 12.

[0080] The rear link mechanism 620 may also include a locking mechanism (not shown) that stops the movement of each link member. Activating the locking mechanism can fix the rear control angle ACr. As a result, for example, when parking the lean-to vehicle 10, the rear control angle ACr can be fixed to zero, thereby stabilizing the parking position.

[0081] (Configuration Example of Front Wheel Unit) Next, the configurations of the front wheel unit 16F, steering shaft 50, and handlebars 58 mounted on the lean vehicle 10 will be described in detail with reference to FIGS.

[0082] FIG. 4 is an exemplary perspective view of the front wheel unit 16F, the steering shaft 50, and the handlebars 58 when the lean vehicle 10 according to the embodiment is viewed from the left front.

[0083] 4 and as described above, the front wheel unit 16F and the handlebars 58 are connected by a steering shaft 50. The steering shaft 50 includes an upper shaft 54, a lower shaft 52, and a low-rigidity member 56 interposed therebetween.

[0084] The upper shaft 54 ​​is provided with a rotary damper 541 and a steering damper 542. The rotary damper 541 and the steering damper 542 are devices that suppress vibrations applied to the handle 58 due to unevenness of the ground GL, etc.

[0085] The rotary damper 541 is a type of hydraulic steering damper, and is provided, for example, on the axis of the upper shaft 54. The piston of the rotary damper 541 moves within a doughnut-shaped oil cylinder in accordance with the rotation of the steering shaft, and the viscosity of the oil provides a damping force against vibrations acting on the handle 58.

[0086] The steering damper 542 is also called a piston-type damper or a cylinder-type damper, and extends, for example, from a connection part 543 at the lower end of the upper shaft 54, directly above the low-rigidity member 56, toward the rear of the steering shaft 50, that is, in the −X direction, so as to be perpendicular to the extension direction of the steering shaft 50. The piston of the steering damper 542 moves within the oil cylinder in accordance with the movement of the steering wheel 58, and as a result, a damping force against vibrations acting on the steering wheel 58 can be obtained due to the viscosity of the oil.

[0087] The rotary damper 541 can provide a relatively high torque while being less dependent on speed, so by combining the rotary damper 541 with the steering damper 542, a stable effect can be obtained over a wide range of speeds.

[0088] Furthermore, as described above, the low-rigidity member 56 interposed between the upper shaft 54 ​​and the lower shaft 52 reduces the transmission efficiency of the input angle from the steering wheel 58. On the other hand, by attaching the rotary damper 541 and the steering damper 542 to the steering shaft 50, they have the function of suppressing vibrations applied to the steering wheel 58 and also impart rigidity to the steering shaft 50. Therefore, in comparison with the low-rigidity member 56, the rotary damper 541 and the steering damper 542 can also be said to be rigid members.

[0089] By providing the rotary damper 541 and the steering damper 542 closer to the steering wheel 58 than the low-rigidity member 56, rather than providing them in a portion closer to the front wheel unit 16F, such as the lower shaft 52, it is possible to alleviate the discomfort felt by the driver due to the reduced steering response caused by the low-rigidity member 56. Therefore, the rotary damper 541 and the steering damper 542 can also be said to be resistance members against the input operation on the steering wheel 58.

[0090] 4, both the rotary damper 541 and the steering damper 542 are provided on the steering shaft 50. However, the rotary damper 541 and the steering damper 542 are mechanisms for suppressing vibration of the steering wheel 58 and improving the ride comfort and ease of operation for the driver, and do not contribute to the effect itself of the embodiment in which the low-rigidity member 56 is interposed in the steering shaft 50 to improve the stability of the vehicle body 12.

[0091] Therefore, the lean vehicle 10 may be provided with only one of the rotary damper 541 and the steering damper 542, or may be provided with neither the rotary damper 541 nor the steering damper 542.

[0092] The lower shaft 52 has a connection portion 521 at its lower end for connection with the front wheel unit 16F. This allows the input angle from the handlebars 58 to be transmitted to the front wheel unit 16F via the upper shaft 54, the low-rigidity member 56, and the lower shaft 52.

[0093] The front wheel unit 16F may be equipped with, for example, a parallel link similar to the above-mentioned rear link mechanism 620, so that when the rear wheel 14R of the rear wheel unit 16R is tilted toward the inside of the turn relative to the ground GL by the lean unit 60, the two front wheels 14F included in the front wheel unit 16F can also be tilted toward the inside of the turn relative to the ground GL in accordance with the tilt of the rear wheel 14R.

[0094] Therefore, in addition to the lean motor 610 and the above-mentioned rear link mechanism 620, the lean unit 60 may also include a parallel link or the like provided on the front wheel unit 16F.

[0095] Fig. 5 is a cross-sectional view showing an example of the configuration of a low-rigidity member 56 interposed in the steering shaft 50 of the lean vehicle 10 according to the embodiment. More specifically, Fig. 5 shows a cross section of the low-rigidity member 56 perpendicular to the extension direction of the steering shaft 50. Fig. 6 is a perspective view showing an example of the configuration of the low-rigidity member 56 interposed in the steering shaft 50 of the lean vehicle 10 according to the embodiment.

[0096] As shown in FIGS. 5 and 6 , the low-rigidity member 56 of this embodiment includes an outer shell 561 , an inner shell 562 , a shaft member 563 , and a rubber member 565 .

[0097] The outer shell 561 is a metal member having a substantially rectangular cross-sectional shape, and an inner shell 562, a shaft member 563, and a rubber member 565 are housed in the internal space. The inner shell 562 is a metal member having a substantially rectangular cross-sectional shape tilted, for example, at 45° relative to the outer shell 561. Each side surface of the inner shell 562 is concave, recessed inward into the inner shell 562. The shaft member 563 is a metal member provided inside the inner shell 562 at a position coinciding with the rotation axis of the steering shaft 50 and rotatable integrally with the inner shell 562. The rubber members 565 are cylindrical and press-fit into four spaces between the inner shell 562 and the outer shell 561 so as to face the recesses in the inner shell 562.

[0098] The cylindrical rubber member 565 is compressed while rotating between the inner shell 562 and the outer shell 561, so that the low-rigidity member 56 is configured as, for example, a Neidhardt rubber spring having nonlinear spring characteristics and damping properties.

[0099] In the low-rigidity member 56 configured in this manner, the outer shell 561 is fixed to, for example, the lower shaft 52 on the front wheel unit 16F side, and the shaft member 563 is connected to, for example, the upper shaft 54 ​​on the handlebar 58 side, so that the input angle from the handlebar 58 is transmitted to the front wheel unit 16F with a low transmission rate.

[0100] The low-rigidity member 56 may be a night rubber spring or the like, which includes a rubber spring as described above, or may be a metal spring alone, or a combination of a rubber spring and a metal spring. The shape of the low-rigidity member 56 can also be selected arbitrarily, and may be, for example, a compression coil spring or a leaf spring.

[0101] In addition, the steering shaft 50 only needs to have a low-rigidity portion in the middle of the extension direction, and instead of the above-mentioned low-rigidity member 56, the middle portion of the steering shaft 50 may be made thinner than the other portions, and this portion may function as a low-rigidity member.

[0102] The extent to which the overall rigidity of the steering shaft 50 is set using the low-rigidity member 56 and the like will be described later.

[0103] (Example of Turning Operation of Lean Vehicle) Next, the operation of the lean vehicle 10 of the embodiment when turning will be described with reference to Figures 7 and 8. Figures 7 and 8 are schematic diagrams that explain an example of the operation of the lean vehicle 10 according to the embodiment when turning.

[0104] More specifically, Figures 7 and 8 show the lean vehicle 10 when turning right. The left drawings in Figures 7 and 8 (Figures 7(a) and 8(a)) are views of the lean vehicle 10 when turning from the rear side, and the right drawings in Figures 7 and 8 (Figures 7(b) and 8(b)) are views of the lean vehicle 10 when turning from above.

[0105] As shown in Figure 7, the lean vehicle 10 has a predetermined minimum radius at which the lean vehicle 10 can turn, i.e., a minimum allowable turning radius Ra. Specifically, the minimum allowable turning radius Ra is determined by the maximum allowable centrifugal force Fa (see Figure 8). The maximum allowable centrifugal force Fa is the maximum centrifugal force that provides stability for the vehicle body 12 during a turn, and can be determined from the maximum tilt angle of the vehicle body 12, the maximum speed of the lean vehicle 10, the tread width of the pair of rear wheels 14R, and the center of gravity position of the lean vehicle 10.

[0106] More directly, it is generally considered difficult to maintain the stability of the vehicle body 12 if the resultant force (Fb×W) obtained by combining a vector in the direction of gravity, i.e., the −Z direction, which indicates the load W of the entire lean vehicle 10, and a vector indicating the centrifugal force Fb acting on the vehicle body 12 during a turn, extends beyond the front wheel 14F and rear wheel 14R on the outside of the turn, i.e., the line connecting the outer wheels, to the outside. More strictly, in order to sufficiently stabilize the vehicle body 12 during a turn, it is preferable that the resultant force (Fb×W) be contained within the width of the vehicle body 12.

[0107] The maximum lean angle of the vehicle body 12 is the maximum angle of the rear control angle ACr between the lateral link member 621a and the longitudinal link member 622b, which is limited by a stopper provided in the rear link mechanism 620. The tread width of the pair of rear wheels 14R is the distance between the centers of the contact surfaces of the rear wheels 14R.

[0108] The maximum speed of the lean vehicle 10 may be set to vary depending on the input angle of the steering wheel 58 at that time. That is, for example, the maximum speed when traveling straight and the maximum speed when turning may be different. Even in this case, the allowable minimum turning radius Ra for each input angle of the steering wheel 58 can be calculated appropriately based on the maximum speed that changes for each input angle of the steering wheel 58.

[0109] When a steering angle that results in a turning radius Rb exceeding the minimum allowable turning radius Ra of the vehicle body 12 is input from the steering wheel 58, according to the above definition, the centrifugal force Fb acting on the vehicle body 12 increases to the point where it becomes difficult to maintain the stability of the vehicle body 12.

[0110] While the allowable minimum turning radius Ra is determined as described above, the minimum turning radius determined by the physical configuration of the vehicle body 12 may be smaller than the allowable minimum turning radius Ra. Examples of the physical configuration of the vehicle body 12 that determine the minimum turning radius include the maximum steering angle of the steering wheel 58 and the wheelbase.

[0111] The maximum steering angle of the steering wheel 58 is the maximum rotation angle of the steering wheel 58 that is limited by a stopper provided on the steering wheel 58. The wheelbase is the length from the center point of the pair of front wheels 14F and the pair of rear wheels 14R that the lean vehicle 10 has, which are aligned in the ±X direction, to the center point of the rear wheels 14R.

[0112] As shown in FIG. 8, when a steering angle that results in a turning radius Rb exceeding the minimum allowable turning radius Ra is input from the steering wheel 58, in the lean vehicle 10 of this embodiment, the low rigidity member 56 adjusts the torsion angle θ of the steering shaft 50 so that the turning radius Rb of the vehicle body 12 is within the range of the minimum allowable turning radius Ra.

[0113] If the turning radius Rb is within the range of the allowable minimum turning radius Ra, the resultant force (Fa x W) of the vector of the centrifugal force Fa applied to the vehicle body 12 at that time and the vector of the load W of the lean vehicle 10 can be contained within the width of the vehicle body 12.

[0114] Here, the rigidity required for the turning radius Rb to be equal to the minimum allowable turning radius Ra can be set as the upper limit value of the rigidity k of the entire steering shaft 50. The upper limit value of the rigidity k of the entire steering shaft 50 can be calculated as follows.

[0115] In other words, the torsional angle θ of the steering shaft 50 when the vehicle body 12 turns is determined by the maximum steering angle of the handlebars 58 when the stiffness k of the steering shaft 50 is sufficiently large, the centrifugal force Fa applied when turning at the above-mentioned minimum allowable turning radius Ra, the torsional moment M of the steering shaft 50 generated by the above-mentioned length Q, which is the trail length, and the stiffness k of the steering shaft 50.

[0116] When the steering shaft 50 is tilted backward as described above, the calculation of the torsional moment M of the steering shaft 50 must take into account the angle δ (see FIG. 1), which is the tilt angle of the steering shaft 50.

[0117] 8(a), since the vehicle body 12 is tilted toward the inside of the turn during turning, the steering shaft 50 is also tilted toward the inside of the turn, and in this case, the effective centrifugal force Fa' acting on the steering shaft 50 is lower than the above-mentioned centrifugal force Fa in accordance with the tilt angle ε of the steering shaft 50 toward the inside of the turn. Here, the tilt angle ε is the angle between the axis in the extension direction of the steering shaft 50 and the perpendicular line (-Z direction) extending from the axis of the steering shaft 50, as viewed from the rear of the vehicle body 12.

[0118] These are shown in the following formulas (1), (1)' and (2).

[0119] Torsion moment M = Fa' x (Wf / W) x Q x cos δ (1) Centrifugal force Fa' = Fa x cos ε (1)' Torsion angle θ = M / k (2)

[0120] At this time, the torsion angle θ of the steering shaft 50 reduces the actual steering angle of the front wheels 14F relative to the input angle from the steering wheel 58. In this case, the stiffness k when the turning radius Rb = the minimum allowable turning radius Ra can be set as the upper limit value of the stiffness k of the steering shaft 50. The actual stiffness k of the steering shaft 50 can be set to be equal to or less than this upper limit value.

[0121] The torsion angle θ of the steering shaft 50 is an example of the operating range of the steering shaft 50 that drives the front wheels 14F by mechanical operation.

[0122] (Configuration example and control example of control device) Next, a configuration example of the control device 30 provided in the lean vehicle 10 according to the embodiment will be described with reference to Fig. 9 and Fig. 10. Fig. 9 is a block diagram showing an example of the functional configuration of the control device 30 provided in the lean vehicle 10 according to the embodiment.

[0123] The control device 30 of the embodiment includes, as functional units, a target lean angle acquisition unit 301, an actual lean angle acquisition unit 302, a deviation acquisition unit 303, a motor torque determination unit 304, and a drive control unit 305. These functional units are realized by a central processing unit (CPU) of the control device 30 configured as, for example, a computer, reading out a control program stored in a read-only memory (ROM), expanding the program into a random access memory (RAM), and executing the program.

[0124] The target lean angle acquisition unit 301 determines the target lean angle corresponding to the driving desired by the driver, for example, by using a map created in advance through testing, etc., based on the vehicle speed of the lean vehicle 10 acquired from the speed sensor 26 and the rotation angle (input angle) of the steering wheel 58 acquired from the angle sensor 23.

[0125] The actual lean angle acquisition unit 302 identifies the actual lean angle, which indicates the actual tilt state of the lean vehicle 10 at present, using an inertial measurement unit included in the direction sensor 28 provided on the rear wall portion 12 b of the vehicle body 12 .

[0126] The deviation acquisition unit 303 calculates the deviation between the identified target lean angle and the actual lean angle.

[0127] The motor torque determination unit 304 determines an output torque (output value) determined by a lean motor torque that cancels out the roll stiffness generated in the rotary damper 541, steering damper 542, etc. due to the current inclination (actual lean angle) of the lean vehicle 10, and a lean motor torque that eliminates the deviation between the target lean angle calculated by the deviation acquisition unit 303 and the actual lean angle.

[0128] The drive control unit 305 controls the drive of the lean motor 610 so as to output the lean motor torque determined by the motor torque determination unit 304 .

[0129] FIG. 10 is a block diagram showing an example of a procedure of the lean control process of the control device 30 provided in the lean vehicle 10 according to the embodiment.

[0130] 10 , a target lean angle is input as a target value r(s) to the control device 30. The target lean angle is acquired by a target lean angle acquisition unit 301 from the vehicle speed of the lean vehicle 10 and the rotation angle of the steering wheel 58.

[0131] Furthermore, deviation acquisition unit 303 calculates the deviation between the target lean angle input as target value r(s) and the actual lean angle acquired by actual lean angle acquisition unit 302, and inputs the deviation to motor torque determination unit 304, which is a feedback controller. Based on the deviation input from deviation acquisition unit 303, motor torque determination unit 304 outputs output torque as feedback value Gfb(s).

[0132] On the other hand, the target lean angle acquired as the target value r(s) by the target lean angle acquisition unit 301 is input to a motor torque determination unit 304, which also functions as a feedforward controller. The motor torque determination unit 304 outputs an output torque as a feedforward value Gff(s) based on the target lean angle input from the target lean angle acquisition unit 301.

[0133] The output torque, which is the feedback value Gfb(s), and the output torque, which is the feedforward value Gff(s), are calculated taking into consideration the roll stiffness of the rotary damper 541, the steering damper 542, and the like.

[0134] The drive control unit 305 outputs the lean motor torque, which is the sum of the output torque, which is the feedback value Gfb(s), and the output torque, which is the feedforward value Gff(s), output from the motor torque determination unit 304, as a control input value u(s) to the lean motor 610, which is the object of control.

[0135] The lean motor 610 generates the lean motor torque output from the drive control unit 305 as the control input value u(s), and rotates the lateral link member 621a by the generated lean motor torque, thereby causing the vehicle body 12 to lean toward the inside of the turn.

[0136] The actual lean angle acquisition unit 302 acquires the actual lean angle as an output value y(s) from the inertial measurement unit included in the direction sensor 28 , and inputs it to the deviation acquisition unit 303 .

[0137] As described above, the lean control of the lean vehicle 10 of the embodiment is performed by two-degree-of-freedom control in which feedback control and feedforward control are performed in parallel. By performing both feedback control and feedforward control, the lean control of the lean vehicle 10 can be performed with high accuracy.

[0138] However, the method of lean control of the lean vehicle 10 is not limited to the method shown in Fig. 10. As an example, the lean control of the lean vehicle 10 may be performed solely by feedback control.

[0139] (Summary) Some lean vehicles maintain balance by tilting the body toward the inside of the turn when turning. However, when the turning radius is small, the centrifugal force acting toward the outside of the turn makes it easy for the inner wheels to lift up, making it difficult to maintain balance.

[0140] One possible solution to this problem is to introduce steer-by-wire (SBW) technology, which connects the steering wheel and steering wheels with an electrical signal. This changes the relationship between the input angle from the steering wheel and the actual steering angle of the steering wheels, making it possible to adjust the turning radius to maintain balance.

[0141] However, if the steering mechanism is made by wire, a steering motor, a driver for driving the steering motor, a control device for these, a functional safety device, etc. are required, which results in high costs.

[0142] According to the embodiment of the lean vehicle 10, the vehicle is provided with a steering shaft 50 that transmits the steering angle input to the steering wheel 58 to the front wheels 14F, which are the steered wheels, and a low-rigidity member 56 that is interposed in the steering shaft 50 and reduces the transmission rate of the steering angle to the front wheels 14F.

[0143] This allows the lean vehicle 10 to improve its cornering stability with a simple mechanical configuration. Since there is no need to introduce a complex and expensive steer-by-wire system, the lean vehicle 10 can be obtained at low cost. Furthermore, since the lean vehicle 10 of the embodiment is relatively lightweight, it is possible to steer it without introducing a steer-by-wire system.

[0144] According to the lean vehicle 10 of the embodiment, when a steering angle exceeding the minimum allowable turning radius Ra of the vehicle body 12 is input from the steering wheel 58, the low rigidity member 56 reduces the transmission rate of the steering angle from the steering wheel 58 so that the turning radius Rb of the vehicle body 12 is within the range of the minimum allowable turning radius Ra.

[0145] This prevents the lean vehicle 10 from having a turning radius Rb that is less than the minimum allowable turning radius Ra of the vehicle body 12, thereby improving the stability of the lean vehicle 10 when turning.

[0146] According to the lean vehicle 10 of the embodiment, the low-rigidity member 56 reduces the torsion angle, which is the operating range of the steering shaft 50, so that when a steering angle exceeding the minimum allowable turning radius Ra of the vehicle body 12 is input from the steering wheel 58, the turning radius Rb of the vehicle body 12 falls within the range of the minimum allowable turning radius Ra, due to a reduction in the overall rigidity of the steering shaft 50 including the low-rigidity member 56.

[0147] This allows the steering system to have a simple configuration, and a low-cost lean vehicle 10 can be obtained.

[0148] According to the lean vehicle 10 of the embodiment, the low-rigidity member 56 includes at least one of a metal spring and a rubber spring.

[0149] This allows a low-rigidity member 56 with a simple configuration to be interposed in the steering shaft 50, thereby improving the stability of the lean vehicle 10 when turning.

[0150] According to the embodiment of the lean vehicle 10, the steering shaft 50 transmits the steering angle input from the steering wheel 58 to the steered front wheels 14F, and has at least one of a rotary damper 541 and a steering damper 542 that resists the input operation of the steering wheel 58, located closer to the steering wheel 58 than the part where the low-rigidity member 56 is interposed on the transmission path of the steering shaft 50.

[0151] This allows the driver to feel a certain response when operating the steering wheel 58, and reduces the discomfort the driver may feel due to the reduced steering response caused by the low-rigidity member 56.

[0152] In the above-described embodiment, the steering shaft 50 with the low-rigidity member 56 interposed therein is used as a steering system for improving the stability of the lean vehicle 10 during cornering. However, the steering system for a lean vehicle using a low-rigidity member is not limited to the above configuration. As an example, a low-rigidity member may be interposed in a steering gear that rotates in accordance with the input angle from the steering wheel 58.

[0153] (Modifications) In the above-described embodiment, an example of a lean vehicle 10 in which all four wheels, the front wheels 14F which are steered wheels and the rear wheels 14R which are drive wheels, are tilted with respect to the horizontal ground GL to tilt the vehicle body 12 toward the inside of a turn has been described. However, as described above, the lean vehicle 10 is not limited to a four-wheel vehicle, and any combination of steered wheels and drive wheels may be used, and the lean vehicle 10 may also be provided with a lean mechanism that tilts the vehicle body without tilting the wheels.

[0154] Below, using Figures 11 to 14, we will compare the features of a four-wheeled lean vehicle 10 equipped with the above-mentioned lean unit 60, a three-wheeled vehicle equipped with a lean mechanism that tilts the body by tilting the wheels, similar to the above-mentioned lean unit 60, and a three-wheeled vehicle equipped with a lean mechanism that tilts the body without tilting the wheels.

[0155] First, for comparison, an example of the lean vehicle 10 of the above-described embodiment is shown in FIG.

[0156] 11 is a schematic diagram showing an example of lean control of the lean vehicle 10 according to the embodiment. As shown in FIG. 11, the lean vehicle 10 according to the embodiment is configured as a four-wheel vehicle including a pair of front wheels 14F and a pair of rear wheels 14R.

[0157] Both of these front wheels 14F and rear wheels 14R are configured to be able to lean using a parallel link or the like, thereby allowing the vehicle body 12 to lean toward the inside of a turn. A lean mechanism that tilts these front wheels 14F and rear wheels 14R can be provided on either the front wheels 14F or the rear wheels 14R. A lean mechanism may also be provided on either the front wheels 14F or the rear wheels 14R.

[0158] Of the front wheels 14F and rear wheels 14R, for example, the front wheels 14F are steered wheels and the rear wheels 14R are driven wheels. However, the front wheels 14F may be configured to function as both steered wheels and driven wheels. In this case, both the front wheels 14F and the rear wheels 14R are driven wheels.

[0159] 12 is a schematic diagram showing an example of lean control of a lean vehicle 10a according to a modified embodiment. As shown in FIG. 12, the lean vehicle 10a of the modified embodiment differs from the configuration of the above-described embodiment in that both the front wheels 14Fa and the rear wheels 14Ra are steered wheels. In this case, at least one of the front wheels 14Fa and the rear wheels 14Ra can be used as a drive wheel.

[0160] The lean vehicle 10a of the modified example can be configured similarly to the above-described embodiment except for the above points.

[0161] That is, in the modified lean vehicle 10a, a lean mechanism is provided on at least one of the front wheels 14Fa and the rear wheels 14Ra, and the vehicle body 12g can be tilted by tilting the front wheels 14Fa and the rear wheels 14Ra.

[0162] 13 is a schematic diagram showing another example of lean control of a lean vehicle 10b according to a modified example of the embodiment. As shown in FIG. 13, the lean vehicle 10b of the modified example differs from the configuration of the above-described embodiment in that it has only one front wheel 14Fb instead of the pair of front wheels 14F.

[0163] The lean vehicle 10b of the modified example can be configured similarly to the above-described embodiment except for the above points.

[0164] That is, in the lean vehicle 10b of the modified example, the front wheels 14Fb are steered wheels and the rear wheels 14Rb are driven wheels. However, similar to the configurations of Figures 11 and 12 described above, both the front wheels 14Fb and the rear wheels 14Rb may be steered wheels, or both the front wheels 14Fb and the rear wheels 14Rb may be driven wheels.

[0165] In addition, in the lean vehicle 10b of the modified example, a lean mechanism is provided on at least one of the front wheels 14Fb and the rear wheels 14Rb, and the vehicle body 12j can be tilted by tilting the front wheels 14Fb and the rear wheels 14Rb.

[0166] In addition, if a lean mechanism is provided only on the front wheel 14Fb side of the front wheel 14Fb and the rear wheel 14Rb, it is also possible to configure the front wheel 14Fb side with a pair of wheels spaced apart in the vehicle width direction, and the rear wheel 14Rb side with a single wheel.

[0167] 14 is a schematic diagram showing yet another example of lean control of a lean vehicle 10c according to a modified example of the embodiment. As shown in FIG. 14, the lean vehicle 10c of the modified example differs in that, instead of the lean mechanism that tilts the front wheels 14Fb and the rear wheels 14Rb to tilt the vehicle body 12j as in the lean vehicle 10b of FIG. 13 described above, the lean vehicle 10c of the modified example tilts the vehicle body 12k without tilting at least the wheels on the side where the lean mechanism is provided.

[0168] More specifically, in the lean vehicle 10c of the modified example, a lean mechanism is provided on the rear wheel 14Rc. In this case, for example, a lean motor can be fixed to the rear wheel 14Rc, and the rotating shaft side of the lean motor, which is the output side, can be connected to the vehicle body 12k. As a result, the lean motor tilts the vehicle body 12k relative to the rear wheel 14Rc, which remains upright.

[0169] In this case, the front wheel 14Fc, which does not have a lean mechanism, may be configured to tilt in accordance with the tilt of the vehicle body 12k by being equipped with a parallel link or the like configured to keep the front wheel 14Fc parallel to the vehicle body 12k.

[0170] In this way, even if a wheel having a lean mechanism has a lean mechanism that maintains an upright position, the wheel side having the lean mechanism can be configured to have a pair of wheels spaced apart in the vehicle width direction.

[0171] As described above, the configuration of the embodiment can be applied to lean vehicles having various configurations, such as the type of lean mechanism, the total number and arrangement of wheels, and the combination of steered wheels and drive wheels.

[0172] Although the embodiments and modifications of the present disclosure have been described above, the above-described embodiments and modifications are merely examples and are not intended to limit the scope of the invention. The novel embodiments and modifications described above can be implemented in various forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The above-described embodiments and modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims.

[0173] [Summary of the Present Embodiment] The present embodiment has at least the following configuration.

[0174] A lean vehicle is provided on a vehicle body and comprises a plurality of wheels including at least one steering wheel; a lean mechanism that tilts the vehicle body toward the inside of a turn relative to the ground; a steering unit that is capable of mechanically turning the vehicle body left and right; a transmission unit that transmits a steering angle input to the steering unit to the steering wheel; and a low transmission member interposed in the transmission unit that reduces the transmission rate of the steering angle transmitted from the steering unit to the steering wheel, wherein when a steering angle that exceeds the allowable minimum turning radius of the vehicle body is input from the steering unit, the low transmission member reduces the transmission rate of the steering angle so that the turning radius of the vehicle body is within the range of the allowable minimum turning radius.

[0175] This configuration uses a simple mechanical structure to improve the stability of the lean vehicle 10 during turning. Also, since the lean vehicle 10 is prevented from having a turning radius Rb that is less than the minimum allowable turning radius Ra of the vehicle body 12, the stability of the lean vehicle 10 during turning can be improved.

[0176] In addition, the transmission unit drives the steering wheel by mechanical operation, and the low transmission member is a low-rigidity member that is interposed in the mechanical operating part in the extension direction of the transmission unit and has lower rigidity than other parts of the operating part, and when a steering angle that exceeds the allowable minimum turning radius of the vehicle body is input from the steering unit due to the decrease in the overall rigidity of the transmission unit including the low-rigidity member, the mechanical operating range is reduced so that the turning radius of the vehicle body is within the range of the allowable minimum turning radius.

[0177] According to this configuration, the steering system can be made simple in configuration, and a low-cost lean vehicle 10 can be obtained.

[0178] In addition, the transmission unit is a shaft connecting the steering unit and the steering wheel, and the low-rigidity member reduces the torsion angle of the shaft so that the turning radius of the vehicle body falls within the range of the minimum allowable turning radius when a steering angle exceeding the minimum allowable turning radius of the vehicle body is input from the steering unit due to a decrease in the overall rigidity of the shaft including the low-rigidity member.

[0179] According to this configuration, the steering system can be made simple in configuration, and a low-cost lean vehicle 10 can be obtained.

[0180] The low-rigidity member includes at least one of a metal spring and a rubber spring.

[0181] According to this configuration, a low-rigidity member 56 with a simple configuration can be interposed in the steering shaft 50, thereby improving the stability of the lean vehicle 10 when turning.

[0182] The transmission unit also has a transmission path that transmits the steering angle input from the steering unit to the steered wheel, and has a resistance member against the input operation in the steering unit, located on the transmission path closer to the steering unit than the part where the low-rigidity member is interposed.

[0183] With this configuration, the driver can feel a certain response when operating the steering wheel 58, and the discomfort felt by the driver due to the reduced steering responsiveness caused by the low-rigidity member 56 can be alleviated.

[0184] The lean mechanism also includes a lean motor that drives a link mechanism that tilts the vehicle body toward the inside of a turn, and a control device that controls the lean motor with an output torque that is set based on the deviation between a target lean angle set from the steering angle input from the steering unit and an actual lean angle that indicates the inclination state of the lean vehicle.

[0185] According to this configuration, the lean motor is controlled by the output torque set based on the deviation between the target lean angle and the actual lean angle, so that the lean control of the lean vehicle 10 can be performed with high precision.

[0186] 10, 10a, 10b, 10c... lean vehicle, 12, 12g, 12j, 12k... vehicle body, 14F, 14Fa, 14Fb, 14Fc... front wheels, 14R, 14Ra, 14Rb, 14Rc... rear wheels, 30... control device, 50... steering shaft, 52... lower shaft, 54... upper shaft, 56... low rigidity member, 60... lean unit, 610... lean motor, 620... rear link mechanism, Ra... allowable minimum turning radius.

Claims

1. A lean vehicle comprising: a plurality of wheels provided on a vehicle body, including at least one steering wheel; a lean mechanism that tilts the vehicle body inward relative to the ground during a turn; a steering unit capable of mechanically turning the vehicle body left and right; a transmission unit that transmits a steering angle input to the steering unit to the steering wheel; and a low transmission member interposed in the transmission unit that reduces the transmission rate of the steering angle transmitted from the steering unit to the steering wheel, wherein when a steering angle that exceeds the allowable minimum turning radius of the vehicle body is input from the steering unit, the low transmission member reduces the transmission rate of the steering angle so that the turning radius of the vehicle body is within the range of the allowable minimum turning radius.

2. The lean vehicle described in claim 1, wherein the transmission section drives the steering wheel by mechanical action, the low transmission member is a low rigidity member interposed in the mechanical operating part in the extension direction of the transmission section and having lower rigidity than other parts of the operating part, and when a steering angle exceeding the minimum allowable turning radius of the vehicle body is input from the steering section due to a decrease in the overall rigidity of the transmission section including the low rigidity member, the mechanical operating range is reduced so that the turning radius of the vehicle body is within the range of the minimum allowable turning radius.

3. A lean vehicle as described in claim 2, wherein the transmission unit is a shaft connecting the steering unit and the steering wheel, and the low-rigidity member reduces the torsion angle of the shaft so that the turning radius of the vehicle body falls within the range of the minimum allowable turning radius when a steering angle exceeding the minimum allowable turning radius of the vehicle body is input from the steering unit due to a decrease in the overall rigidity of the shaft including the low-rigidity member.

4. The lean vehicle according to claim 2, wherein the low-rigidity member includes at least one of a metal spring and a rubber spring.

5. A lean vehicle as described in claim 2, wherein the transmission unit has a transmission path that transmits the steering angle input from the steering unit to the steered wheels, and has a resistance member against the input operation at the steering unit, located on the transmission path closer to the steering unit than the portion where the low rigidity member is interposed.

6. A lean vehicle as described in claim 1, wherein the lean mechanism comprises a lean motor that drives a link mechanism that tilts the vehicle body toward the inside of a turn, and a control device that controls the lean motor with an output torque that is set based on the deviation between a target lean angle set from the steering angle input from the steering unit and an actual lean angle that indicates the tilt state of the lean vehicle.

Images