Control device for leaning vehicle

Abstract

A control device for a leaning vehicle comprises: an acquisition unit that acquires a target inclination angle of a vehicle body in the vehicle width direction as determined according to the traveling operation state of a leaning vehicle, the actual inclination angle, which is the actual inclination angle of the vehicle body in the vehicle width direction and which can be changed according to the roll rigidity produced by the suspension, and deviation between the target inclination angle and the actual inclination angle; a determination unit that determines the output value of a lean-driving unit in accordance with the value of a first torque against roll rigidity generated corresponding to the actual inclination angle and the value of a second torque generated so as to eliminate the deviation; and a drive control unit that executes control of the lean-driving unit according to the output value.

Description

Lean vehicle control device

[0001] The present disclosure relates to a control device for a lean vehicle.

[0002] Conventionally, various powered vehicles for small passengers, such as small, one-person vehicles, have been put into practical use as one of the easy means of transportation. In such small passenger vehicles, miniaturization is achieved by shortening the vehicle's longitudinal length and width. However, narrowing the vehicle width can make it difficult for the vehicle to maintain its stability. For example, centrifugal forces generated on the outside of a turn during a turn can cause the vehicle's posture to become unstable. Therefore, lean vehicles have been proposed that include a lean mechanism that tilts the vehicle body relative to the road surface (the wheels in contact with the road surface) in the vehicle width direction (inward of the turn) depending on the driving condition, thereby balancing the centrifugal forces generated on the outside of the turn during a turn and improving the stability of the vehicle's posture.

[0003] Japanese Patent Application Laid-Open No. 2021-160610

[0004] In order to popularize lean vehicles such as those described above, it is necessary to give lean vehicles a simple structure that allows for cost reduction, and to provide control that enables the vehicle to achieve a stable lean posture when turning even with this simple structure.

[0005] Therefore, one of the problems that the embodiments of the present invention aim to solve is to provide a control device for a lean vehicle that can achieve a stable lean posture when cornering in a lean vehicle with a simple structure that can achieve cost reduction.

[0006] A lean vehicle control device as an example of the present disclosure includes: a plurality of wheel units provided at least at a front position and a rear position of a vehicle body, at least one of which has a pair of wheels spaced apart in a vehicle width direction; a lean unit provided near any one of the plurality of wheel units that has the pair of wheels, the lean unit including a lean mechanism that tilts the wheel unit and the vehicle body relative to the ground toward the inside of a turn and a lean drive unit for driving the lean mechanism; and a lean unit provided on any one of the plurality of wheel units that has the pair of wheels, the lean unit generating roll stiffness when the vehicle body tilts in the vehicle width direction relative to the ground. a suspension; and a control device for a lean vehicle, the control device comprising: an acquisition unit that acquires a target inclination angle in the vehicle width direction of the vehicle body determined by the driving operation state of the lean vehicle; an actual inclination angle that is the actual inclination angle in the vehicle width direction of the vehicle body that can change depending on the roll stiffness generated by the suspension; and a deviation between the target inclination angle and the actual inclination angle; a determination unit that determines an output value of the lean drive unit in accordance with a first torque value that is generated in response to the actual inclination angle and resists the roll stiffness, and a second torque value that is generated to eliminate the deviation; and a drive control unit that controls the lean drive unit in accordance with the output value.

[0007] With the above configuration, for example, the actual lean angle can be changed quickly regardless of the circumstances under which the actual lean angle of the vehicle body is changed (for example, regardless of the magnitude of the amount of change or the rate of change). In other words, even if the roll stiffness generated by the suspension changes when the vehicle body leans relative to the ground, the output of the lean drive unit is determined based on an output value for resisting the roll stiffness corresponding to the roll stiffness (actual lean angle) and an output value for eliminating the deviation between the target lean angle and the actual lean angle. As a result, it becomes easier to achieve the ideal cornering posture of a lean vehicle, which contributes to improving driving stability.

[0008] FIG. 1 is an exemplary and schematic side view showing the configuration of a lean vehicle according to an embodiment. FIG. 2 is an exemplary and schematic image diagram showing a state in which the lean vehicle according to the embodiment is not tilted in the vehicle width direction when viewed from the rear. FIG. 3 is an exemplary and schematic image diagram showing a state in which the lean vehicle according to the embodiment is tilted in the vehicle width direction (toward the inside of a turn) when viewed from the rear. FIG. 4 is an exemplary and schematic perspective view showing the configuration of a passive suspension as a suspension provided on the front wheels of the lean vehicle according to the embodiment. FIG. 5 is an exemplary and schematic image diagram showing a state in which the lean vehicle according to the embodiment is not tilted in the vehicle width direction when viewed from the front. FIG. 6 is an exemplary and schematic image diagram showing a state in which the lean vehicle according to the embodiment is tilted in the vehicle width direction (toward the inside of a turn) when viewed from the front. FIG. 7 is an exemplary and schematic block diagram showing the configuration of a control device that performs lean control in the lean vehicle according to the embodiment. Fig. 8 is an exemplary explanatory diagram showing the relationship between roll stiffness generated with respect to the roll angle and the lean motor torque required to achieve an appropriate roll angle in a lean vehicle according to the embodiment. Fig. 9 is an exemplary explanatory diagram showing the relationship between the roll angle and the torque limit value when applying lean motor torque to achieve an appropriate roll angle in a lean vehicle according to the embodiment and applying torque limiting to prevent lifting of the wheels of the lean vehicle. Fig. 10 is an exemplary flowchart showing a control procedure for controlling a lean posture in a lean vehicle according to the embodiment when the seesaw arm rotates within its swing range. Fig. 11 is an exemplary flowchart showing a control procedure for controlling a lean posture in a lean vehicle according to the embodiment when the seesaw arm rotates beyond its swing range.

[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] FIG. 1 is an exemplary schematic side view showing the configuration of a lean vehicle 10 according to an embodiment. The lean vehicle 10 of this embodiment includes a plurality of wheel units, a lean unit, and a suspension. The plurality of wheel units are provided at least at the front and rear of the vehicle body, and at least one of the wheel units includes a pair of wheels spaced apart in the vehicle width direction. The lean unit is provided near one of the plurality of wheel units that includes a pair of wheels, and includes a lean mechanism that tilts the wheel unit and the vehicle body toward the inside of a turn relative to the ground, and a lean drive unit that drives the lean mechanism. The suspension is provided on one of the plurality of wheel units that includes a pair of wheels, and generates roll stiffness when the vehicle body tilts in the vehicle width direction relative to the ground. This configuration allows the lean vehicle 10 to maintain stable driving performance, particularly driving stability during cornering, while achieving reduced costs compared to vehicles with lean units on front and rear wheels.

[0011] FIG. 1 illustrates a lean vehicle 10 having a pair of wheels spaced apart in the vehicle width direction at the front and rear of the vehicle body. As will be described later, FIG. 1 illustrates a configuration in which a lean unit is disposed on the rear wheel unit, and a passive suspension, an example of a suspension, is disposed on the front wheel unit. In FIG. 1, the lean vehicle 10 is shown placed on a horizontal ground surface GL and not tilted. FIG. 1 illustrates a forward direction DF, a rearward direction DB, an upward direction DU, a downward direction DD, a rightward direction DR, and a leftward direction DL. The forward direction DF is the front direction of the lean vehicle 10 (i.e., the forward direction), and the rearward direction DB is the opposite direction to the forward direction DF. The upward direction DU is the vertically upward direction, and the downward direction DD is the vertically downward direction (i.e., the opposite direction to the upward direction DU). The vertically downward direction is the direction of gravity. The right direction DR is the right direction as seen from the lean vehicle 10 traveling in the forward direction DF, and the left direction DL is the opposite direction to the right direction DR. The forward direction DF, the backward direction DB, the right direction DR, and the left direction DL are all horizontal directions. The upward direction DU and the downward direction DD are, for example, perpendicular to the forward direction DF.

[0012] The lean vehicle 10 in this embodiment is, for example, a small, one-seater vehicle. As described above, the lean vehicle 10 has a plurality of wheel units 16 (rear wheel unit 16R, front wheel unit 16F) provided at least at the front and rear positions of the vehicle body 12 and each having a pair of wheels 14 spaced apart in the vehicle width direction (right direction DR, left direction DL). In other words, the lean vehicle 10 of this embodiment shown in FIG. 1 is a four-wheel vehicle. Note that FIG. 1 is a view of the lean vehicle 10 from the right side, and for the sake of structural explanation, the front and rear wheels 14 on the right side are not shown.

[0013] In the lean vehicle 10 shown in FIG. 1 , for example, the rear wheel unit 16R is a drive wheel unit. The drive wheels (rear wheels 14) may be driven by a power transmission mechanism using, for example, a drive motor or a reduction mechanism, or may be driven by an in-wheel motor built into each wheel 14. On the other hand, the front wheel unit 16F is a non-drive wheel and a rotating wheel that can rotate in the vehicle width direction of the lean vehicle 10 (i.e., the right direction DR and the left direction DL). The traveling direction of the rotating wheel can rotate to the right or left from the forward direction DF. Note that in another embodiment, the rear wheel unit 16R may be a non-drive wheel, and the front wheel unit 16F may be a drive wheel that can rotate left and right. Furthermore, the lean vehicle 10 may be provided with a wheel unit 16 that includes a pair of wheels 14 spaced apart in the vehicle width direction at least at one of a front position and a rear position. For example, the lean vehicle 10 may have six or more wheels, or may be a three-wheel vehicle with one wheel on either the front or rear side. The three-wheeled lean vehicle will be described later.

[0014] The vehicle body 12 has a main body 12a. The main body 12a includes a bottom 12b, a front wall 12c connected to the forward (DF) side of the bottom 12b, a front portion 12d extending from the upper end of the front wall 12c in the forward direction DF, a rear wall 12e connected to the rearward (DB) side of the bottom 12b, and a rear portion 12f extending from the upper end of the rear wall 12e in the rearward direction DB. The main body 12a includes, for example, a metal frame and a panel fixed to the frame.

[0015] The vehicle body 12 further includes a seat 18 fixed on the bottom portion 12b, an accelerator pedal 20 and a brake pedal 22 arranged on the forward direction DF side of the seat 18, a control device 24 fixed to the bottom portion 12b, a handle 26 attached to the front portion 12d, etc. Although not shown, other members (e.g., a roof, headlights, etc.) may be fixed to the main body portion 12a.

[0016] The seat 18 includes a seat surface 18a and a backrest 18b so that the driver can adjust the depression of an accelerator pedal 20 and a brake pedal 22 and turn a steering wheel 26 while seated.

[0017] The accelerator pedal 20 adjusts the output state of a drive motor that rotates and drives the drive wheels (rear wheels 14) by adjusting the amount of depression by the driver. The brake pedal 22 adjusts the braking state of a mechanical brake or the like provided on the wheels 14 by adjusting the amount of depression by the driver.

[0018] The steering wheel 26 is a member that can rotate right and left. The rotation angle (sometimes referred to as the input angle) of the steering wheel 26 relative to a predetermined rotation position (sometimes referred to as the straight-ahead rotation position) that indicates straight driving is an example of turning target information that indicates the target direction and target degree of turning. In this embodiment, "input angle = zero" indicates straight driving, "input angle > zero" indicates a right turn, and "input angle < zero" indicates a left turn. The magnitude (i.e., absolute value) of the input angle indicates the target degree of turning. The driver can input the turning target information by operating the steering wheel 26. Note that the connection between the steering wheel 26 and a steering mechanism that steers the front wheels 14 may be realized by a mechanically connected mechanical steering mechanism or by an electrically connected steer-by-wire system.

[0019] A direction sensor 28 is fixed to a portion of the vehicle body 12, for example, the rear wall portion 12e. The direction sensor 28 is a sensor that measures the roll angle and yaw angular velocity of the vehicle body 12. The direction sensor 28 also includes an acceleration sensor 30, a gyro sensor 32, and a control unit 34. The acceleration sensor 30 is a sensor that detects acceleration in a given direction, for example, a triaxial acceleration sensor. The direction of acceleration detected by the acceleration sensor 30 is referred to as the detection direction. When the leaning vehicle 10 is stopped, the detection direction is the same as the vertically downward direction DD. The gyro sensor 32 is a sensor that detects angular velocity around a rotation axis in a given direction, for example, a triaxial angular velocity sensor. The control unit 34 determines the roll angle and yaw angular velocity using signals from the acceleration sensor 30, the gyro sensor 32, and, for example, a signal from a speed sensor 36 disposed in the front wheel unit 16F. The control unit 34 is, for example, a data processing device including a computer. These sensors constitute an inertial measurement unit (IMU) and can acquire the actual tilt state (actual lean angle) of the lean vehicle 10 while it is running.

[0020] First, the rear wheel unit 16R mounted on the lean vehicle 10 will be described.

[0021] As shown in FIG. 1 , in a lean vehicle 10, a rear wheel unit 16R disposed on the rearward DB side of a rear wall portion 12e of a vehicle body 12 includes a rear coupling device 38A that couples the rear wheels 14 to the vehicle body 12. The lean vehicle 10 shown in FIG. 1 illustrates an example in which the rear wheels 14 are driven to rotate by a power transmission mechanism, such as a drive motor 40 and a reduction gear mechanism 42. The rear wheel unit 16R also includes a battery 44 that supplies power to the drive motor 40, a lean motor (a lean drive unit for driving the lean mechanism) of the lean unit (described later), and various devices mounted on the lean vehicle 10. In the lean vehicle 10 configured as shown in FIG. 1 , a lean unit is provided on one of the front wheel unit 16F and the rear wheel unit 16R, but not on the other. A suspension (passive suspension) that generates roll stiffness is provided on the other of the front wheel unit 16F and the rear wheel unit 16R, but not on one of them. Therefore, the weight distribution of the vehicle body 12 of the lean vehicle 10 of this embodiment is such that a greater weight is distributed to the rear wheel unit 16R, which is equipped with a lean unit, than to the front wheel unit 16F, which is not equipped with a lean unit (the side on which a suspension is mounted, as described below). As a result, more of the lean motor torque generated by the lean unit can be transmitted to the road surface (ground surface GL), improving the posture control performance of the lean unit. The drive motor 40 is rotationally controlled in accordance with the depression amount of the accelerator pedal 20, and drives the rear wheels 14 to rotate via a reduction mechanism 42. Well-known configurations can be used for the drive motor 40, the power transmission mechanism using the reduction mechanism 42, the battery 44, and the like, and detailed description thereof will be omitted.

[0022] The rear wheel unit 16R and the vehicle body 12 are connected by a rear connecting bar 46A. An end 46Aa of the rear connecting bar 46A on the vehicle body 12 side is rotatably connected to the vehicle body 12, and an end 46Ab on the rear wheel unit 16R side is fixed to the rear wheel unit 16R. A rear spring member 48, which functions as a suspension, is interposed between the middle portion of the rear connecting bar 46A and the vehicle body 12. As a result, the rear wheel unit 16R (the rear wheel 14) and the vehicle body 12 are able to move (rotate) relative to each other in the vertical direction. For example, when traveling over uneven ground GL, the rear wheel unit 16R mainly displaces vertically, reducing the transmission of vertical vibrations to the vehicle body 12. Note that in the configuration of FIG. 1, only one rear spring member 48 is present, located approximately in the center of the vehicle width direction, and does not have roll rigidity. Therefore, the rear wheel unit 16R of the lean vehicle 10 of this embodiment does not have a configuration that generates roll stiffness with a spring element. The front wheel unit 16F (front coupling mechanism 38B, described later) and the vehicle body 12 are connected by a front coupling bar 46B. An end 46Ba of the front coupling bar 46B on the vehicle body 12 side is fixed to the vehicle body 12, and an end 46Bb on the front wheel unit 16F side is fixed to the front wheel unit 16F.

[0023] Fig. 2 is an exemplary and schematic image diagram of the lean vehicle 10 viewed from the rear, showing the lean vehicle 10 not leaning in the vehicle width direction. Fig. 3 is an exemplary and schematic image diagram of the lean vehicle 10 viewed from the rear, showing the lean vehicle 10 leaning in the vehicle width direction (toward the inside of a turn). Note that, in order to facilitate understanding of the behavior of the lean vehicle 10, Figs. 2 and 3 omit illustration of the power transmission mechanisms of the rear coupling device 38A, such as the drive motor 40 and the reduction mechanism 42.

[0024] As described above, the rear coupling device 38A couples the two wheels 14 (rear wheels) to the vehicle body 12. The rear coupling device 38A also includes a lean unit. The lean unit includes a rear link mechanism 50 that functions as a lean mechanism (a mechanism that tilts the lean vehicle 10 toward the inside of a turn) and a lean motor 52 that is attached to the rear link mechanism 50 and functions as a lean drive unit.

[0025] The rear link mechanism 50 is a so-called parallel link and has the function of tilting the rear wheel unit 16R (wheel unit) and the vehicle body 12 toward the inside of a turn relative to the ground. The rear link mechanism 50 includes three vertical link members 50a, 50b, and 50c aligned in order toward the rightward direction DR and two horizontal link members 50d and 50e aligned in order toward the downward direction DD. As shown in FIG. 2 , when the lean vehicle 10 is upright (position SR1) on horizontal ground GL (i.e., ground GL perpendicular to the vertically upward direction DU), the vertical link members 50a, 50b, and 50c are parallel to the vertical direction, and the horizontal link members 50d and 50e are parallel to the horizontal direction. Here, the vertical link member 50a may be referred to as the first vertical link member. The vertical link member 50b may be referred to as the third vertical link member or the second support member. The vertical link member 50c may be referred to as the second vertical link member. The lateral link member 50d may be referred to as a first lateral link member or a first support member. The lateral link member 50e may be referred to as a second lateral link member. The lean mechanism includes a vertical link member 50a (first vertical link member) connected to one wheel 14 and extending in the vehicle height direction, and a vertical link member 50c (second vertical link member) connected to the other wheel 14 and extending in the vehicle height direction. The lean mechanism also includes a lateral link member 50d (first lateral link member) extending in the vehicle width direction, and a lateral link member 50e (second lateral link member) extending in the vehicle width direction. One end of the lateral link member 50d (first lateral link member) is rotatably connected to the upper end of the vertical link member 50a (first vertical link member), and the other end is rotatably connected to the upper end of the vertical link member 50c (second vertical link member). The horizontal link member 50e (second horizontal link member) has one end rotatably connected to the lower end of the vertical link member 50a (first vertical link member) and the other end rotatably connected to the lower end of the vertical link member 50c (second vertical link member). The lean mechanism also has a vertical link member 50b (third vertical link member) rotatably connected to the intermediate portion of the horizontal link member 50d (first horizontal link member) and the other end rotatably connected to the intermediate portion of the horizontal link member 50e (second horizontal link member).The lean motor 52 (lean drive unit) is connected to one end of the vertical link member 50b (third vertical link member) and the intermediate portion of the horizontal link member 50d (first horizontal link member), thereby moving the vertical link member 50b (third vertical link member) and the horizontal link member 50d (first horizontal link member) relative to each other. In this manner, the two vertical link members 50a, 50c and the two horizontal link members 50d, 50e form a parallelogram link mechanism. The vertical link member 50b connects the central portions of the two horizontal link members 50d, 50e. As a result, the driving force of the lean motor 52 (lean drive unit) can be efficiently transmitted to the link mechanism without using a spring element (suspension). The vertical link members 50a, 50b, 50c and the horizontal link members 50d, 50e are made of, for example, metal.

[0026] The rear link mechanism 50 has bearings that rotatably connect multiple link members. For example, bearing 54a rotatably connects vertical link member 50b and horizontal link member 50e. Bearing 54b rotatably connects vertical link member 50a and horizontal link member 50e. Bearing 54c rotatably connects vertical link member 50c and horizontal link member 50e. Other link members are similarly rotatably connected to each other by bearings. The rotation axes of bearings 54a, 54b, etc., connecting each link member extend from the rearward direction DB toward the forward direction DF (in this embodiment, the rotation axes are parallel to the forward direction DF). The two connected link members can rotate relatively around the rotation axes within a predetermined angular range (e.g., a range less than 180 degrees). This structure enables the rear link mechanism 50 to tilt the rear wheel unit 16R and the vehicle body 12 toward the inside of a turn (vehicle width direction) relative to the ground GL. For example, when a lean vehicle 10 turns, as shown in FIG. 3 , the lean vehicle 10 leans toward the inside of the turn (right direction DR) to resist the centrifugal force generated in the outside of the turn (left direction DL). When the vehicle body is tilted toward the inside of the turn to resist the centrifugal force, the lean vehicle 10 can turn stably. However, as the centrifugal force increases and the vehicle body 12 begins to swing toward the outside of the turn, stability decreases. Therefore, in order to continue turning smoothly, it is necessary to intentionally tilt the lean vehicle 10 toward the inside of the turn. Therefore, the rear link mechanism 50 uses the lean motor 52 to intentionally tilt the lean vehicle 10 toward the inside of the turn, thereby improving the posture stability of the lean vehicle 10 during turning.

[0027] The lean motor 52 is an example of a drive device configured to drive the rear link mechanism 50, and is, for example, an electric motor. The lean motor 52 is connected, for example, to the vertical link member 50b and the upper horizontal link member 50d. The lean motor 52 rotates the horizontal link member 50d relative to the vertical link member 50b. In other words, the lean motor 52 (lean mechanism) tilts the vehicle body 12 by relatively moving the horizontal link member 50d (first support member) connected to the wheel 14 and the vertical link member 50b (second support member) connected to the vehicle body 12. In this case, the drive amount of the lean motor 52 and the relative movement amount between the horizontal link member 50d (first support member) and the vertical link member 50b (second support member) are linearly related. This prevents the transmission of drive force from the lean motor 52 from being affected by spring elements, etc. As a result, the lean vehicle 10 can maintain a more stable turning posture by controlling the vehicle only with the first and second torque values ​​(described later) in consideration, without requiring complex control. In other words, the wheels 14 (vehicle body 12) can smoothly lean toward the inside of the turn (i.e., to the right or left in the vehicle width direction). This leaning motion is also called a roll motion. The lean motor 52 and the vertical link member 50b may be connected via a gear. The lean motor 52 and the lateral link member 50d may also be connected via a gear. Hereinafter, the torque generated by the lean motor 52 is also referred to as lean motor torque. The lean motor torque rolls the vehicle body 12. That is, control can be achieved to tilt the rear wheel unit 16R and the vehicle body 12 toward the inside of the turn relative to the ground GL. In another embodiment, the lean motor may be fixed to the rear wheel unit 16R, and the output side (rotating shaft side) of the lean motor may be connected to the vehicle body 12. In this case, the rear wheel unit 16R and the vehicle body 12 may be tilted relative to each other, so that the rear wheel unit 16R and the vehicle body 12 are tilted toward the inside of the turn relative to the ground GL.

[0028] As described above, the position SR1 shown in FIG. 2 indicates a state in which the lean vehicle 10 is upright, and the position SR2 shown in FIG. 3 indicates a state in which the lean vehicle 10 is tilted with respect to the horizontal ground GL. As shown in the position SR1, when the lateral link member 50d is perpendicular to the vertical link member 50b, the rear wheels 14 are upright with respect to the horizontal ground GL. The entire lean vehicle 10, including the vehicle body 12, is upright with respect to the ground GL. The vehicle body upward direction DVU in FIG. 2 is the upward direction of the vehicle body 12. When the lean vehicle 10 is not tilted, the vehicle body upward direction DVU is the same as the upward direction DU. In this embodiment, a predetermined upward direction with respect to the vehicle body 12 is used as the vehicle body upward direction DVU.

[0029] When the lean vehicle 10 in the position SR1 is traveling straight ahead and there are irregularities on the ground surface GL, the wheel 14 is displaced in the vertical direction due to the vertical translation action of the rear link mechanism 50, and the rear connecting bar 46A and the rear spring member 48 cooperate to allow the rear wheel unit 16R (rear link mechanism 50) to move (pivot) in the vertical direction relative to the vehicle body 12. As a result, when the lean vehicle 10 travels over, for example, uneven ground surface GL, the transmission of vertical vibrations to the vehicle body 12 is reduced, which can contribute to improved traveling stability.

[0030] On the other hand, as shown in the position SR2 in FIG. 3 , when the vertical link member 50b rotates clockwise relative to the horizontal link member 50d in the rear view, the right rear wheel 14R moves toward the vehicle body upward direction DVU, and the left rear wheel 14L moves toward the opposite direction relative to the vehicle body 12. Therefore, with the rear wheels 14R, 14L in contact with the ground GL, the wheels 14L, 14R, and therefore the vehicle body 12, tilt toward the right direction DR with respect to the ground GL. For example, when the leaning vehicle 10 turns right, the vehicle body 12 can be tilted toward the inside of the turn (right direction DR) to balance the centrifugal force generated toward the outside of the turn. In this case, the amount of tilt of the vehicle body 12 toward the inside of the turn can be appropriately adjusted by controlling the lean motor 52. Note that when the vertical link member 50b rotates counterclockwise relative to the horizontal link member 50d, the vehicle body 12 tilts toward the left direction DL. In other words, the vehicle body 12 can be tilted so as to balance the centrifugal force when turning left as well.

[0031] In the posture SR2 shown in Figure 3, the vehicle body upward direction DVU is tilted toward the right direction DR with respect to the upward direction DU. Hereinafter, the angle between the upward direction DU and the vehicle body upward direction DVU when looking at the lean vehicle 10 facing forward DF will be referred to as the roll angle Ar or the tilt angle Ar. Here, "Ar > zero" indicates tilt toward the right direction DR, and "Ar < zero" indicates tilt toward the left direction DL. The roll angle Ar of the vehicle body 12 can be said to be the roll angle Ar of the lean vehicle 10 having the vehicle body 12.

[0032] FIG. 3 , which shows the position SR2, illustrates the rear control angle ACr of the rear link mechanism 50. The rear control angle ACr indicates the angle of the orientation of the vertical link member 50b relative to the orientation of the lateral link member 50d. In the rear view showing the position SR2, "ACr = zero" indicates that the vertical link member 50b is perpendicular to the lateral link member 50d. "ACr > zero" indicates that the vertical link member 50b has rotated clockwise relative to the lateral link member 50d from the "ACr = zero" state. Although not shown, "ACr < zero" indicates that the vertical link member 50b has rotated counterclockwise relative to the lateral link member 50d from the "ACr = zero" state. As illustrated, when the lean vehicle 10 is positioned on a horizontal ground surface GL (i.e., a ground surface GL perpendicular to the vertically upward direction DU), the rear control angle ACr is approximately equal to the roll angle Ar.

[0033] As will be described later, the front wheel unit 16F is equipped with a passive suspension 54 and a link mechanism that generates greater roll rigidity as the tilt (roll) of the vehicle body 12 increases, while allowing the front wheels 14 to tilt in the vehicle width direction. Therefore, the front wheels can also tilt the vehicle body 12 in the vehicle width direction relative to the ground. In other words, the lean vehicle 10 can adjust the posture of the vehicle body 12 in the vehicle width direction depending on the driving state and road surface conditions, and change it to a posture suitable for driving.

[0034] As described above, the rear link mechanism 50 on the rear wheel side tilts (rolls) the vehicle body 12 toward the inside of a turn using the lean motor 52, thereby maintaining a balance with the centrifugal force generated during a turn. In this case, this roll causes the front wheels 14 to roll in the same way.

[0035] The rear link mechanism 50 and a front-wheel-side link mechanism described below are examples of a tilting device (sometimes referred to as a front tilting device or a rear tilting device) configured to tilt the vehicle body 12 in the vehicle width direction of the lean vehicle 10. The lean motor 52 is an example of a drive device (sometimes referred to as a rear drive device) configured to generate a drive force (i.e., lean motor torque) that drives the rear tilting device. The drive force of the rear drive device is a force that rolls the vehicle body 12 toward the inside of a turn relative to the pair of rear wheels 14.

[0036] The rear wheel unit 16R may have a locking mechanism (not shown) that stops the movement of the rear link mechanism 50. By operating the locking mechanism, the rear control angle ACr can be fixed. As a result, for example, when parking the lean vehicle 10, the rear control angle ACr can be fixed to zero, thereby stabilizing the parking position.

[0037] Next, the front wheel unit 16F will be described. Fig. 4 is an exemplary schematic perspective view showing the configuration of a passive suspension 54, which is a front-wheel side link mechanism (also referred to as a front coupling mechanism 38B) included in the front wheel unit 16F and is provided on the front wheel side of the lean vehicle 10, as an example of a suspension. Note that Fig. 4 explains the basic operation of the passive suspension 54, and members not relevant to the explanation are not shown.

[0038] The passive suspension 54 (front connecting mechanism 38B) is, for example, a well-known double wishbone type suspension, and is composed of an upper arm 56, a lower arm 58, a ball joint 60 (only one side is shown), a hub knuckle 62 (only one side is shown), a shock absorber 64, etc.

[0039] As described above, the basic structure of the double wishbone passive suspension 54 is a well-known structure, and detailed description thereof will be omitted. However, a pair of upper arms 56 and lower arms 58 spaced apart in the vehicle height direction are provided for the left and right wheels 14, respectively. That is, the pair of upper arms 56 are provided for the left and right wheels 14, respectively, with one end rotatably connected to the wheel 14 and the other end rotatably connected to the vehicle body 12. The pair of lower arms 58 are spaced apart from the upper arms 56 in the vehicle height direction and provided for the left and right wheels 14, respectively, with one end rotatably connected to the wheel 14 and the other end rotatably connected to the vehicle body 12. In other words, the ends of the upper arms 56 and lower arms 58 that are farther from the wheels 14 are rotatably connected to a part of the vehicle body 12, and the ends that are closer to the wheels 14 are rotatably connected to a hub knuckle 62 that is connected to the wheel 14 via a ball joint 60. One end of the hub knuckle 62 is rotatably connected to the upper arm 56, and the other end is rotatably connected to the lower arm 58. This allows the hub knuckle 62 to swing in the vehicle width direction around approximately the center of the hub knuckle 62, allowing the wheel 14 to tilt in the vehicle width direction. The shock absorber 64 generates roll rigidity by expanding and contracting, and generates a force that resists centrifugal force during cornering, i.e., a force that suppresses the lean vehicle 10 from swinging toward the outside of the corner. One end of each of the pair of shock absorbers 64 is connected to either the pair of upper arms 56 or the pair of lower arms 58, and the other end is connected to the vehicle body 12. In the case of FIG. 4 , one end (lower end) of the shock absorber 64 is rotatably connected to the lower arm 58. Note that in other embodiments, one end (lower end) of the shock absorber 64 may be connected to the upper arm 56. By configuring the passive suspension 54 in this manner, as will be explained below, it is possible to achieve cost reduction while maintaining stable driving performance, particularly driving stability during cornering.

[0040] A seesaw arm 66 extending in the vehicle width direction is connected to the other end (upper end) of the shock absorber 64 of the passive suspension 54 of this embodiment. The seesaw arm 66 is, for example, an arc-shaped plate member, and the upper ends of the left and right shock absorbers 64 are rotatably connected to both ends of the seesaw arm 66. The center of the seesaw arm 66 is rotatably connected to a portion of the vehicle body 12 by a predetermined amount. The seesaw arm 66 swings before the shock absorbers 64 expand and contract, thereby enabling the lean vehicle 10 to tilt. In other words, the start of the expansion and contraction movement of the shock absorbers 64 can be delayed. As a result, the lean vehicle 10 can tilt the wheels 14 (front wheels) toward the inside of the turning direction of the lean vehicle 10 (vehicle width direction) by the amount of expansion and contraction of the shock absorbers 64 and the amount of swing of the seesaw arm 66. In other words, the amount of tilt of the wheels 14 (front wheels) can be expanded beyond the expansion and contraction capacity of the shock absorbers 64, thereby contributing to expanding the range within which the vehicle posture is stable during cornering.

[0041] Furthermore, the passive suspension 54 including the seesaw arm 66 can prevent roll stiffness from being generated in a first region (first angle range) from the start of tilting of the vehicle body 12 up to a predetermined angle (up to the swing range of the seesaw arm 66). Furthermore, the seesaw arm 66 (passive suspension 54) can generate roll stiffness by the spring force of the shock absorber 64 in a second region (second angle range) that is tilted further from the first region. In other words, the passive suspension 54 of this embodiment is configured to vary the roll stiffness characteristics depending on the degree of leaning of the lean vehicle 10. Specifically, in the small tilt region (first region), roll stiffness is reduced to prioritize ease of leaning (ease of leaning), and in the large tilt region (second region), roll suppression is prioritized to prioritize roll stiffness. As a result, when the turning radius is large or the vehicle speed is slow, and the centrifugal force generated in the outside direction of the turn is small, it is easier to achieve a lean posture of the lean vehicle 10. Also, when the centrifugal force becomes large, the increased roll rigidity can reduce instability in the tilted posture of the lean vehicle 10 (front wheels 14) (improving posture maintenance ability).

[0042] The operation of the front wheel unit 16F configured as described above will be described with reference to FIGS. 5 and 6. FIG. 5 is an exemplary and schematic image diagram showing the lean vehicle 10 as viewed from the front, in a state where the lean vehicle 10 is not tilted in the vehicle width direction (toward the inside of a turn). FIG. 6 is an exemplary and schematic image diagram showing the lean vehicle 10 as viewed from the front, in a state where the lean vehicle 10 is tilted toward the inside of a turn. Note that, to facilitate understanding of the behavior of the lean vehicle 10, FIGS. 5 and 6 only show the upper arm 56, lower arm 58, hub knuckle 62, shock absorber 64, and seesaw arm 66 of the front wheel unit 16F (passive suspension 54), and omit other components. Also, FIGS. 2 and 3 described above show the lean vehicle 10 as viewed from the rear, and FIG. 3 shows the lean vehicle 10 turning right. 5 and 6 are views of the lean vehicle 10 as seen from the front side, and FIG. 6 is a view of the lean vehicle 10 turning left.

[0043] As described above, the upper arms 56 and lower arms 58 that make up the passive suspension 54 connect the wheels 14 (front wheels) to the vehicle body 12. The left and right upper arms 56 and the left and right lower arms 58 rotate in opposite directions to each other, thereby displacing the wheels 14 up and down in response to unevenness in the ground GL. In other words, this reduces the effect of unevenness in the ground GL from being transmitted to the vehicle body 12, contributing to improved ride comfort. Furthermore, the upper arms 56 and the lower arms 58 rotate in the same direction to tilt the wheels 14, thereby enabling the vehicle body 12 to tilt inward of a turn (in the vehicle width direction) relative to the ground GL, similar to the rear wheel unit 16R (rear link mechanism 50).

[0044] For example, as shown in the position SF1 in FIG. 5 , when the lean-mounted vehicle 10 is standing upright on a horizontal ground surface GL (i.e., a ground surface GL perpendicular to the vertically upward direction DU), the upper arms 56 and the lower arms 58 are parallel to the horizontal. In this state, the shock absorbers 64 are in a steady state, and essentially no spring force (spring expansion / contraction from the state in which the springs support the vehicle's own weight) other than the spring force supporting the vehicle's own weight is generated. If the ground surface GL is uneven and both the left and right wheels 14 simultaneously displace upward or downward, the left and right upper arms 56 and the left and right lower arms 58 rotate in opposite directions to absorb the displacement caused by the unevenness. Furthermore, if the ground surface GL is uneven and one wheel 14 displaces upward or downward in response to the unevenness, the upper arms 56 and the lower arms 58 rotate in the same direction in response to the unevenness to absorb the displacement caused by the unevenness. In this case, if the degree of unevenness is relatively small and the amount of rotation of the lower arm 58 is within the swing range of the seesaw arm 66 to which the shock absorber 64 is connected, the shock absorber 64 does not expand or contract, and the amount of displacement due to the unevenness is absorbed only by the swing of the seesaw arm 66, thereby stabilizing the posture of the vehicle body 12. On the other hand, if the degree of unevenness exceeds the swing range of the seesaw arm 66, the shock absorber 64 begins to expand or contract, and the amount of displacement due to the unevenness is absorbed by the swing of the seesaw arm 66 and the expansion and contraction of the shock absorber 64.

[0045] Next, the behavior of the front wheel unit 16F (passive suspension 54) when the lean vehicle 10 turns will be described using Figure 6. As described above, when the lean vehicle 10 turns, for example, in the left direction DL, centrifugal force is generated in the outside direction of the turn (right direction DR). Therefore, to counteract this centrifugal force, the lean vehicle 10 needs to be tilted inward. In this case, in the front wheel unit 16F, the left and right upper arms 56 and the left and right lower arms 58 rotate in the same direction, thereby tilting the wheels 14 and tilting the vehicle body 12 in the inside direction of the turn (vehicle width direction) relative to the ground GL.

[0046] For example, as shown in the posture SF2 in FIG. 6 , when the lean vehicle 10 turns left, it needs to lean toward the left, which is the inside of the turn, to balance the centrifugal force generated toward the outside of the turn. As described above, the lean vehicle 10 can be intentionally tilted toward the inside of the turn (leaning) by driving the lean motor 52 on the rear wheel unit 16R side. In this case, the drive control of the lean motor 52 is performed based on a target lean angle (turning target information, target lean angle) calculated from the vehicle speed of the lean vehicle 10 and the rotation angle (input angle) of the steering wheel 26, and an actual lean angle (actual lean angle) obtained from an inertial measurement unit. In this case, the target lean angle and the actual lean angle may differ depending on the driving state, road surface condition, etc. Therefore, the lean vehicle 10 controls the lean motor torque generated by the lean motor 52 of the rear wheel unit 16R to resist the roll stiffness generated by the shock absorber 64 (passive suspension 54) and to eliminate the deviation between the target lean angle and the actual lean angle, thereby realizing the ideal cornering posture of the lean vehicle 10.

[0047] In the front wheel unit 16F (passive suspension 54), when the lean vehicle 10 is in the early stages of tilt, that is, when centrifugal force is small and the amount of rotation of the lower arm 58 (upper arm 56) is within the swing range of the seesaw arm 66 to which the shock absorber 64 is connected (first region where the actual tilt angle is from zero to a predetermined angle), the shock absorber 64 does not expand or contract, and the lean vehicle 10 (wheel 14) is allowed to tilt only by the swing of the seesaw arm 66 (the shock absorber does not generate roll stiffness). In other words, if the lean motor 52 generates lean motor torque to achieve the target lean angle, the ideal cornering posture of the lean vehicle 10 can be easily achieved. On the other hand, when the centrifugal force becomes large and it is necessary to increase the lean vehicle 10's inward tilt and the actual tilt angle exceeds the swing range of the seesaw arm 66 (for example, the swing range restricted by a swing stopper or the like) (when the actual tilt angle is in the second region equal to or greater than a predetermined angle defining the first region), the shock absorbers 64 begin to expand and contract, generating a repulsive force (roll stiffness). In this case, the shock absorbers 64 on the inside of the turn are compressed, and the shock absorbers 64 on the outside of the turn are extended. However, in this case, the repulsive force of the shock absorbers 64 is opposite to the control direction of the lean motor 52, which attempts to tilt the lean vehicle 10 toward the inside of the turn in order to balance the centrifugal force generated toward the outside of the turn. This makes it difficult to tilt the lean vehicle 10 toward the inside of the turn. In other words, simply controlling the lean motor 52 to achieve the target lean angle may make it difficult to achieve the ideal turning posture of the lean vehicle 10.

[0048] Therefore, in this embodiment, the lean motor 52 is controlled to generate lean motor torque to cancel out (resist) the roll stiffness generated by the shock absorber 64 on the wheel unit side, which does not have a lean unit installed.

[0049] FIG. 7 is an exemplary schematic block diagram showing the configuration of a control device 24 that performs lean control in a lean vehicle 10. The control device 24 includes a target lean angle acquisition unit 24a, an actual lean angle acquisition unit 24b, a deviation acquisition unit 24c, a motor torque determination unit 24d, a drive control unit 24e, and the like. The target lean angle acquisition unit 24a can acquire a target lean angle (target tilt angle) corresponding to the driving requested by the driver from a speed sensor 36 (vehicle speed of the lean vehicle 10) and the rotation angle (input angle) of the steering wheel 26, for example, using a map created in advance through testing. The actual lean angle acquisition unit 24b can acquire an actual lean angle (actual tilt angle) that indicates the current actual tilt state of the lean vehicle 10 using an inertial measurement unit (IMU) included in a direction sensor 28 provided on the rear wall 12e of the vehicle body 12. The deviation acquisition unit 24c calculates the deviation between the acquired target lean angle and the actual lean angle. The target lean angle acquisition unit 24a, the actual lean angle acquisition unit 24b, and the deviation acquisition unit 24c may be collectively referred to as an acquisition unit. The motor torque determination unit 24d (sometimes simply referred to as a determination unit) determines the output torque (output value) of the lean motor 52 (lean drive unit) based on a lean motor torque (first torque value) that counteracts the roll stiffness (a force that reduces the lean angle) generated in the shock absorber 64 (suspension) due to the current lean angle (actual lean angle) of the lean vehicle 10, and a lean motor torque (second torque value) that eliminates the deviation between the target lean angle and the actual lean angle acquired by the deviation acquisition unit 24c. The motor torque determination unit 24d determines the output value as, for example, a sum of the first torque value and the second torque value. For example, when the actual lean angle is in the first region from zero to a predetermined angle, as described above, only the seesaw arm 66 swings, and the roll stiffness does not increase (is not generated). Therefore, the motor torque determination unit 24d regards the first torque value in the first region as zero and determines the output value of the lean motor 52 in accordance with the second torque value. On the other hand, in the second region where the actual tilt angle is equal to or greater than the first region of a predetermined angle, the motor torque determination unit 24d takes into account the first torque value based on the roll stiffness generated in the shock absorber 64 and determines the output value of the lean motor 52 in accordance with the first torque value and the second torque value.The drive control unit 24e controls the drive of the lean motor 52 so as to output the output torque (lean motor torque) determined by the motor torque determination unit 24d. In other words, the output value is determined using only the second torque value except for the actual tilt angle condition (second region) where the roll stiffness has a large effect, so the actual tilt angle can be changed more quickly. Furthermore, when determining the output value of the lean motor 52, the lean vehicle 10 can determine the output value without using anything other than the first torque value and the second torque value, for example. As a result, the actual tilt angle can be changed more quickly.

[0050] FIG. 8 is an illustrative diagram showing the relationship between the roll stiffness generated with respect to the roll angle (lean angle) in the lean vehicle 10 and the lean motor torque required to achieve an appropriate roll angle.

[0051] As described above, the front wheel unit 16F (passive suspension 54) includes the shock absorber 64. As shown in FIG. 8 , when the lean vehicle 10 leans toward the inside of a turn, the roll stiffness RP increases with increasing roll angle (the lean of the lean vehicle 10). However, in the case of the passive suspension 54 of this embodiment, due to the presence of the seesaw arm 66, only the seesaw arm 66 swings during the initial stage of the lean (roll, lean), and the roll stiffness does not increase (is not generated). Then, when the seesaw arm 66 rotates beyond its swing range, the roll stiffness increases with increasing roll angle (lean angle). As described above, the roll stiffness acts in the opposite direction to the force that attempts to lean the lean vehicle 10 by driving the lean motor 52. Therefore, one of the causes of the deviation between the target lean angle and the actual lean angle is the roll stiffness, which changes with changes in the roll angle.

[0052] For example, if the actual lean angle becomes smaller than the target lean angle due to a repulsive force (roll stiffness) generated by the expansion and contraction of the shock absorbers 64 when road conditions suddenly change, i.e., if the lean vehicle 10 is not lean enough, the lean motor 52 is controlled to generate a lean motor torque in a direction that increases the lean angle. In this case, as shown in FIG. 8 , the motor torque determiner 24d determines the lean motor torque so as to add a torque Na (torque in the direction that increases the lean angle) corresponding to the roll stiffness generated for the current actual roll angle Ma to the lean motor torque corresponding to the target lean angle, thereby canceling the roll stiffness. In other words, the deviation can be eliminated by bringing the actual lean angle closer to the target lean angle. The drive controller 24e then drives the lean motor 52 to generate a lean motor torque that adds a torque for canceling the roll stiffness, thereby enabling control to achieve an ideal cornering posture of the lean vehicle 10. Similarly, when the actual lean angle is larger than the target lean angle, the ideal turning posture of the lean vehicle 10 can be realized by implementing control to output lean motor torque so as to eliminate the deviation between the target lean angle and the excessively tilted actual lean angle.

[0053] The relationship between the roll stiffness generated for the roll angle (lean angle) shown in FIG. 8 and the lean motor torque required to achieve an appropriate roll angle can be created in advance, for example, through testing. This relationship may be provided as a map or the like. By referencing the pre-stored map, the motor torque determination unit 24d can obtain the lean motor torque (first torque value) that resists the roll stiffness of the shock absorber 64 (passive suspension 54) generated in response to the actual lean angle at the moment the lean vehicle 10 leans with the roll stiffness. The motor torque determination unit 24d can then quickly determine the torque that cancels out the generated roll stiffness and brings the actual lean angle closer to the target lean angle, thereby eliminating the deviation.

[0054] As described above, when the lean vehicle 10 is tilted (leaned) toward the inside of a turn to resist the centrifugal force generated toward the outside of the turn during a turn, the reaction force (force that resists lean) of the shock absorber 64 (spring element) increases as the lean angle increases. If the lean motor torque is increased to increase the lean angle against the reaction force in order to approach the target lean angle, the lean motor torque may exceed the axle load (load acting on the rear wheels) on the rear wheel unit 16R. In this case, continued application of the lean motor torque may cause the wheel 14 on the inside of the turn to lift, resulting in a decrease in driving performance and cornering performance. Therefore, in the lean vehicle 10 of this embodiment, the maximum output torque of the lean motor 52 (lean drive unit) is limited to a torque limit value determined based on the roll stiffness characteristics of the left and right wheels 14 of the front wheel unit 16F (wheel unit 16 not provided with the lean motor 52) equipped with a passive suspension 54, which is an example of a suspension. For example, the drive control unit 24e sets a torque limit value for the lean motor torque when driving the lean motor 52 to generate lean motor torque to cancel out roll stiffness, thereby suppressing the lifting phenomenon of the wheel 14 on the inside of the turn.

[0055] Figure 9 is an illustrative diagram showing the relationship between the roll angle and the torque limit value when applying lean motor torque to achieve an appropriate roll angle in a lean vehicle 10 according to an embodiment, and when torque is limited to prevent lift from occurring in the wheels 14 of the lean vehicle 10.

[0056] In FIG. 9 , the torque limit line L1 indicates the torque limit value when the front wheel unit 16F (passive suspension 54) of the lean vehicle 10 of this embodiment does not have roll stiffness. That is, this is the case when the vehicle does not have a spring element such as a shock absorber 64. The torque limit line L1 is determined depending on the driving conditions of the lean vehicle 10, such as the weight of the vehicle body 12, the height of the center of gravity, the front-rear and left-right positions of the center of gravity, the front-rear and left-right tilt angles of the vehicle body, the vehicle speed, changes in the turning radius, and the rotational resistance of the lean mechanism and suspension. However, since the front wheel unit 16F (passive suspension 54) does not have (or does not generate) roll stiffness even when the lean angle changes, the torque limit value that does not cause the wheel 14 to lift does not change until the roll angle (lean angle) exceeds a predetermined value, but changes after the roll angle (lean angle) exceeds the predetermined value. However, as described above, the torque limit line L1 (torque limit value) changes depending on the driving conditions. That is, the position of the torque limit line L1 shown on the vertical axis in Fig. 9 is determined. Then, based on the torque limit line L1 (torque limit value), whose position on the vertical axis changes depending on the driving state, the torque limit line L2 after the roll angle (lean angle) exceeds a predetermined value is determined according to the roll angle.

[0057] For example, in a lean vehicle 10, if the front wheel unit 16F (passive suspension 54) has roll stiffness, the roll stiffness generated changes in response to changes in the lean angle, as described above. In other words, increasing the lean motor torque also increases the roll stiffness, making the rear wheels 14 more likely to lift. Therefore, if the roll stiffness is present (or changes), the torque limit value is set by subtracting the roll stiffness amount according to the roll stiffness characteristics. As a result, the lifting phenomenon of the rear wheels 14 can be suppressed. The torque limit line L2 shown in FIG. 9 is the torque limit value when the front wheel unit 16F (passive suspension 54) has roll stiffness in the lean vehicle 10 of this embodiment. The torque limit value indicated by the torque limit line L2 can be predetermined (e.g., can be mapped) by subtracting the varying roll stiffness amount from the torque limit line L1 determined depending on the driving state, based on the change characteristics of the roll stiffness that change when the roll angle is changed, for example, through testing.

[0058] Note that the passive suspension 54 of the lean vehicle 10 of this embodiment includes a seesaw arm 66. Therefore, in the initial stage of tilt (roll), only the seesaw arm 66 swings, and roll stiffness does not increase (is not generated). Then, when the seesaw arm 66 rotates beyond its swing range, roll stiffness increases with increasing roll angle (lean angle). Therefore, the torque limit line L2 follows the torque limit line L1 within the swing range of the seesaw arm 66, and the torque limit value decreases once the swing range of the seesaw arm 66 is exceeded. That is, the torque limit value is a constant value in a first region where the actual tilt angle ranges from zero to a predetermined angle, and decreases from the constant value as the actual tilt angle increases in a second region where the actual tilt angle is equal to or greater than the predetermined angle. Note that a smaller torque limit value may result in the lean vehicle 10 being unable to adequately resist the centrifugal force generated in the outward direction of the turn. In such a case, the driver may be notified to drive in a manner that reduces the centrifugal force, for example, by reducing the vehicle speed or increasing the turning radius.

[0059] In this way, when the lean motor 52 applies lean motor torque so as to tilt the lean vehicle 10 toward the inside of the turn, by setting a lean motor torque limit value according to the roll angle (lean angle), it is possible to improve the stability of the turning posture of the lean vehicle 10 when turning and to suppress the floating phenomenon of the wheels 14 when turning.

[0060] Therefore, according to the lean vehicle 10 of this embodiment, it is possible to achieve an ideal cornering posture of the lean vehicle 10 by controlling the lean motor 52 (lean unit) in consideration of the repulsive force (roll rigidity) generated by the expansion and contraction of the shock absorbers 64. As a result, it is possible to provide a lean vehicle 10 with a simple structure that can achieve a more stable lean posture during cornering while maintaining stable driving performance by achieving a good balance between roll suppression by the roll rigidity of the suspension (shock absorbers 64) of the front wheel unit 16F and tilt control by the lean unit of the rear wheel unit 16R, and that is easier to reduce costs.

[0061] In this way, by configuring the lean vehicle 10 so that a lean unit is disposed on at least one of the wheel units at the front position (front wheels) and the rear position (rear wheels) and the passive suspension 54 is disposed on the other wheel unit, the structure and control can be simplified compared to a configuration in which lean units are disposed on both the front and rear positions and control both, which can contribute to reducing the cost of the lean vehicle 10. Furthermore, even when a lean unit is mounted on one of the front and rear wheel units and a passive suspension 54 that generates roll stiffness is mounted on the other wheel unit, the lean vehicle 10 can maintain stable driving performance and achieve a stable lean posture when cornering.

[0062] A control procedure for controlling the lean posture of the lean vehicle 10 configured as described above will be described with reference to the flowcharts of FIGS.

[0063] First, we will explain the control when the shock absorber 64 does not expand or contract during the initial stage of tilting of the lean vehicle 10 (stage when centrifugal force is small), and the tilting of the lean vehicle 10 (wheels 14) is allowed only by the swinging of the seesaw arm 66 (the shock absorber 64 does not generate roll stiffness).

[0064] FIG. 10 is an exemplary flowchart showing a control procedure for controlling the lean posture of the lean vehicle 10 when the seesaw arm 66 rotates within the swing range (first region).

[0065] The target lean angle acquisition unit 24a of the control device 24 acquires the vehicle speed of the lean vehicle 10 from the speed sensor 36 (S100) and also acquires the rotation angle (input angle) of the steering wheel 26 (S102).The target lean angle acquisition unit 24a then acquires a target lean angle corresponding to the driving requested by the driver based on the vehicle speed and rotation angle (S104).Next, the actual lean angle acquisition unit 24b acquires an actual lean angle indicating the current actual tilt state of the lean vehicle 10 using an inertial measurement unit included in the direction sensor 28 (S106).

[0066] The deviation acquisition unit 24c then calculates (acquires) the deviation between the acquired target lean angle and the actual lean angle (S108). In this case, as described above, the lean vehicle 10 can be tolerated only by the swing of the seesaw arm 66, so the shock absorber 64 does not expand or contract, and roll stiffness is not generated. Therefore, the motor torque determination unit 24d determines the lean motor torque (output value) of the lean motor 52 to drive the lean motor 52 so as to eliminate the deviation between the target lean angle and the actual lean angle (S110). The drive control unit 24e then controls the drive of the lean motor 52 so as to output the lean motor torque determined by the motor torque determination unit 24d (S112). As a result, the ideal cornering posture of the lean vehicle 10 can be achieved.

[0067] In this way, in the early stages of leaning of the lean vehicle 10 (stage when centrifugal force is small), when the shock absorber 64 does not expand or contract and the lean vehicle 10 (wheel 14) is allowed to lean only by the swinging of the seesaw arm 66 (the shock absorber 64 does not generate roll stiffness), the lean motor 52 can easily realize the ideal cornering posture of the lean vehicle 10 by generating lean motor torque to achieve the target lean angle.

[0068] Next, we will explain the control when the centrifugal force generated in the lean vehicle 10 becomes large, and it is necessary to increase the inward tilt of the lean vehicle 10 when turning, and the seesaw arm 66 exceeds the swing range (in the case of the second region). In other words, we will explain the control procedure when the shock absorber 64 starts to expand and contract and generates a repulsive force (roll stiffness).

[0069] FIG. 11 is an exemplary flowchart showing a control procedure for controlling the lean posture of the lean vehicle 10 when the seesaw arm 66 rotates beyond the swing range.

[0070] The target lean angle acquisition unit 24a of the control device 24 acquires the vehicle speed of the lean vehicle 10 from the speed sensor 36 (S200) and also acquires the rotation angle (input angle) of the steering wheel 26 (S202).The target lean angle acquisition unit 24a then acquires a target lean angle corresponding to the driving requested by the driver based on the vehicle speed and rotation angle (S204).Next, the actual lean angle acquisition unit 24b acquires an actual lean angle indicating the current actual tilt state of the lean vehicle 10 using an inertial measurement unit included in the direction sensor 28 (S206).

[0071] When the shock absorbers 64 start expanding and contracting and a repulsive force (roll stiffness) is generated, and the lean motor 52 is controlled to tilt the lean vehicle 10 toward the inside of a corner against the centrifugal force, it is necessary to simultaneously perform control to counteract the roll stiffness and control to eliminate the deviation between the target lean angle and the actual lean angle. In this case, the motor torque determiner 24d, for example, refers to a pre-stored map to obtain a lean motor torque (first torque value) that counteracts the roll stiffness of the shock absorbers 64 (passive suspension 54) that is generated corresponding to the actual lean angle (S208). The deviation obtainer 24c calculates (obtains) the deviation between the obtained target lean angle and the actual lean angle (S210). The motor torque determiner 24d obtains a lean motor torque (second torque value) that eliminates the deviation between the target lean angle and the actual lean angle obtained by the deviation obtainer 24c (S212). Then, the motor torque determination unit 24d adds the first torque value and the second torque value to determine the lean motor torque (output value) of the lean motor 52 (S214). The drive control unit 24e controls the drive of the lean motor 52 so as to output the lean motor torque determined by the motor torque determination unit 24d (S216). As a result, the ideal cornering posture of the lean vehicle 10 can be achieved.

[0072] In this way, when the centrifugal force acting on the lean vehicle 10 increases and it becomes necessary to increase the inward tilt of the lean vehicle 10, the ideal turning posture of the lean vehicle 10 can be easily achieved by taking roll stiffness into consideration. In other words, even when the seesaw arm 66 exceeds the swing range and the passive suspension 54 generates roll stiffness during turning of the lean vehicle 10, the lean motor 52 can easily achieve the ideal turning posture of the lean vehicle 10 by generating lean motor torque to achieve the target lean angle.

[0073] 10 and 11, for the sake of explanation, the flowcharts are shown separately for the cases where roll stiffness is not generated and where it is generated, but the process shown in Fig. 11 is executed while the lean vehicle 10 is traveling. During the process, a determination is made as to whether roll stiffness is generated (for example, a determination is made as to whether the seesaw arm 66 is within the swing range), and if roll stiffness is not generated, the first torque value is set to zero and the process is executed. By repeatedly executing this process at a predetermined cycle, it becomes possible to run the lean vehicle 10 in a desired posture.

[0074] In the example shown in FIG. 4 , the seesaw arm 66 is used to expand the range of stability of the vehicle posture during cornering. In other embodiments, instead of the seesaw arm 66, a structure that can eliminate roll stiffness in a region (first region) where the tilt (roll angle) of the vehicle body 12 is small may be used to achieve a similar effect. For example, by installing a passive stabilizer with a free-running section, roll stiffness is eliminated in a region (first region) where the roll angle is small, and the expansion / contraction operation of the shock absorber 64 is delayed (i.e., expansion / contraction begins in the second region), thereby increasing the overall amount of tilt and expanding the range of stability of the vehicle posture during cornering. Also in this case, by preventing roll stiffness from being generated in the first region when the centrifugal force generated in the outward direction of the corner is small, it is possible to easily achieve a lean posture of the lean vehicle 10. Furthermore, by generating roll stiffness by the shock absorber 64 in the second region when the centrifugal force is large, it is possible to reduce instability in the tilt posture of the lean vehicle 10 (front wheels 14) due to the generated roll stiffness. The spring elements included in the passive suspension 54 may be those whose roll stiffness changes stepwise depending on the state of expansion and contraction, such as variable shock absorbers, which can generate small and large roll stiffness. In this case, too, when the centrifugal force generated in the outward direction of the turn is small, the generated roll stiffness can be reduced, making it easier to achieve an appropriate lean posture of the lean vehicle 10. Furthermore, when the centrifugal force is large, the roll stiffness generated in the second region can be increased, making it possible to reduce instability in the tilt posture of the lean vehicle 10 (front wheels 14).

[0075] Furthermore, even if the roll stiffness changes when the wheel unit on the side where the suspension is provided and the vehicle body 12 lean toward the inside of a turn relative to the ground GL, the output of the lean motor 52 is determined based on the lean motor torque that cancels out the roll stiffness according to the roll stiffness (actual lean angle) and the lean motor torque that eliminates the deviation between the target lean angle and the actual lean angle. As a result, it becomes easier to achieve the ideal turning posture of the lean vehicle 10, which can contribute to improving driving stability.

[0076] The lean vehicle 10 shown in the above-described embodiment is a four-wheel vehicle in which the front wheel unit 16F and the rear wheel unit 16R each include a pair of two wheels 14 spaced apart in the vehicle width direction. In other embodiments, the lean vehicle may be configured with three wheels, and the same effects as the four-wheel vehicle described above can be obtained. When the lean vehicle is configured with three wheels, for example, the front wheel side includes one wheel and the rear wheel side includes a pair of wheels (two wheels) spaced apart in the vehicle width direction. In this case, the front wheel unit (front wheel unit) is configured with a suspension to reduce vertical vibrations caused by unevenness in the road surface from being transmitted to the vehicle body. The rear wheel unit (rear wheel unit) can be configured with the lean mechanism (mechanism including a lean motor, etc.) described in FIG. 2 and the passive suspension 54 described in FIG. 4.

[0077] In this way, a three-wheel lean vehicle can easily achieve an ideal turning posture, just like the four-wheel lean vehicle 10. Note that the rear wheel may be one wheel and the front wheel may be two wheels, and the same effect can be obtained.

[0078] As described above, the lean vehicle 10 of this embodiment includes a plurality of wheel units 16 (rear wheel unit 16R, front wheel unit 16F) provided at least at the front and rear positions of the vehicle body 12, at least one of which includes a pair of wheels 14 spaced apart in the vehicle width direction; a lean unit provided near one of the wheel units 16 that includes a pair of wheels 14 among the plurality of wheel units 16, the lean unit including a lean mechanism (a mechanism that tilts the lean vehicle 10 toward the inside of a turn) that tilts the wheel unit and the vehicle body 12 relative to the ground toward the inside of a turn and a lean drive unit (lean motor 52) for driving the lean mechanism; and a suspension provided on one of the wheel units that includes a pair of wheels 14 among the plurality of wheel units 16, the lean mechanism generating roll stiffness when the vehicle body 12 tilts in the vehicle width direction relative to the ground. According to this configuration, for example, a lean unit is provided on at least one of the wheel units 16 at the front and rear positions of the vehicle body 12, and a suspension is provided on one of the wheel units (e.g., the other wheel unit). Therefore, it is possible to provide a lean vehicle with a simple structure that can achieve a more stable lean posture when cornering while maintaining stable driving performance by balancing roll suppression through the roll rigidity of the suspension and tilt control through the lean unit, and that is easier to reduce costs.

[0079] The control device 24 of the lean vehicle 10 also includes a target lean angle acquisition unit 24a that acquires a target lean (inclination) angle in the vehicle width direction of the vehicle body 12 that is determined by the driving operation state of the lean vehicle 10, an actual lean angle acquisition unit 24b that acquires an actual lean (inclination) angle that is the actual inclination angle in the vehicle width direction of the vehicle body 12 that can change due to roll stiffness generated by the suspension, a deviation acquisition unit 24c that acquires the deviation between the target lean angle and the actual lean angle, a motor torque determination unit 24d that determines the output value of the lean motor 52 so as to resist the roll stiffness according to the actual inclination angle and to eliminate the deviation, and a drive control unit 24e that controls the lean motor 52 in accordance with the output value. Note that the target lean angle acquisition unit 24a, the actual lean angle acquisition unit 24b, and the deviation acquisition unit 24c may be combined into an acquisition unit. With this configuration, for example, even if the roll stiffness changes when the wheel unit on the side where the suspension is provided and the vehicle body 12 lean toward the inside of a turn relative to the ground, the output value of the lean motor 52 can be determined while taking into consideration the effect of roll stiffness in advance when outputting so as to eliminate the deviation between the target lean angle and the actual lean angle. As a result, it becomes easier to achieve the ideal turning posture of the lean vehicle 10, which contributes to improving driving stability.

[0080] In the above embodiment, the motor torque determiner 24d may determine the output value of the lean motor 52 based on a first torque value that resists the roll stiffness generated in response to the actual lean (inclination) angle and a second torque value that is generated to eliminate the deviation. This configuration can quickly reflect the torque determination that counteracts the roll stiffness generated by the suspension and brings the actual lean angle closer to the target lean angle to eliminate the deviation. As a result, it becomes easier to quickly achieve the ideal cornering posture of the lean vehicle 10, contributing to improved driving stability.

[0081] In the above embodiment, the motor torque determiner 24d may, for example, add the first torque value and the second torque value together to determine the output value of the lean motor 52. According to this configuration, the output value is determined without using any value other than the first torque value and the second torque value, so that the actual tilt angle can be changed more quickly.

[0082] In the above embodiment, the motor torque determiner 24d may determine the output value of the lean motor 52 in accordance with the second torque value in a first region where the actual tilt angle ranges from zero to a predetermined angle, and may determine the output value of the lean motor 52 in accordance with the first and second torque values ​​in a second region where the actual tilt angle is equal to or greater than the predetermined angle. With this configuration, the second torque value alone is used except for the actual tilt angle in a state where the roll stiffness has a large effect (second region), allowing the actual tilt angle to be changed more quickly.

[0083] Furthermore, in the above embodiment, the drive control unit 24e may, for example, limit the maximum value of the output torque of the lean motor 52 to a torque limit value determined according to the roll stiffness characteristics of the left and right wheels 14 in the wheel unit 16 equipped with a suspension. According to this configuration, for example, when the lean motor 52 applies lean motor torque so as to tilt the lean vehicle 10 toward the inside of a turn, a lean motor torque limit value according to the roll angle (lean angle) is set to limit the application of the lean motor torque, thereby making it possible to suppress the lifting phenomenon of the wheels 14 during cornering.

[0084] In the above embodiment, the torque limit value may be a constant value in a first region where the actual tilt angle is from zero to a predetermined angle, and may be set to decrease from the constant value as the actual tilt angle increases in a second region where the actual tilt angle is equal to or greater than the predetermined angle. This configuration can, for example, improve the stability of the turning posture of the lean vehicle 10 during cornering and suppress the lifting of the wheels 14 during cornering.

[0085] In the above embodiment, for example, the vehicle may have a front wheel unit 16F having a pair of wheels 14 disposed at a front position of the vehicle body 12 and spaced apart in the vehicle width direction, and a rear wheel unit 16R having a pair of wheels 14 disposed at a rear position of the vehicle body 12 and spaced apart in the vehicle width direction, and a lean unit may be provided on one of the front wheel unit 16F and the rear wheel unit 16R but not on the other, and a suspension that generates roll rigidity may be provided on the other of the front wheel unit 16F and the rear wheel unit 16R but not on the other. With this configuration, for example, it is possible to reduce the cost of the lean vehicle 10 while maintaining stable driving performance, particularly improving driving stability during cornering.

[0086] In the above embodiment, the lean mechanism may include, for example, a first support member (lateral link member 50d) connected to the wheel 14 and a second support member (vertical link member 50b) connected to the vehicle body 12. The lean drive unit tilts the vehicle body 12 by moving the first support member and the second support member relative to each other. The amount of drive of the lean motor 52 and the amount of relative movement between the first support member and the second support member may have a linear relationship. With this configuration, for example, the transmission of driving force from the lean motor 52 is not affected by a spring element or the like. As a result, a more stable cornering posture of the lean vehicle 10 can be maintained by control that considers only the first torque value and the second torque value, without requiring complex control.

[0087] In the above embodiment, for example, the lean mechanism may include a first vertical link member (vertical link member 50a) connected to one wheel 14 and extending in the vehicle height direction, a second vertical link member (vertical link member 50c) connected to the other wheel 14 and extending in the vehicle height direction, a first lateral link member (lateral link member 50d) having one end rotatably connected to the upper end of the first vertical link member and the other end rotatably connected to the upper end of the second vertical link member and extending in the vehicle width direction, and a second lateral link member (lateral link member 50d) having one end rotatably connected to the lower end of the first vertical link member. The lean motor 52 may be connected to one end of the third vertical link member and to the intermediate portion of the first horizontal link member, thereby moving the third vertical link member and the first horizontal link member relative to each other. According to this configuration, for example, the transmission of driving force from the lean motor 52 is not affected by a spring element or the like. As a result, a more stable cornering posture of the lean vehicle 10 can be maintained without requiring complex control, by considering only the first torque value and the second torque value.

[0088] In the above embodiment, the suspension may be a passive suspension 54 having, for example, a pair of upper arms 56 provided on the left and right wheels 14, each having one end rotatably connected to the wheel 14 and the other end rotatably connected to the vehicle body 12, a pair of lower arms 58 spaced apart in the vehicle height direction from the upper arms 56, provided on the left and right wheels 14, each having one end rotatably connected to the wheel 14 and the other end rotatably connected to the vehicle body 12, and a pair of shock absorbers 64 having one end connected to either the pair of upper arms 56 or the pair of lower arms 58 and the other end connected to the vehicle body 12. This configuration, for example, can reduce the cost of the lean vehicle 10 while maintaining stable driving performance, particularly improving driving stability during cornering.

[0089] In the above embodiment, the passive suspension 54 may have, for example, a seesaw arm 66 whose center is connected to the vehicle body 12 so as to be able to rotate a predetermined amount, and whose opposite ends are connected to the other ends of the pair of shock absorbers 64. With this configuration, for example, the amount of tilt of the lean vehicle 10 can be expanded beyond the expansion and contraction capacity of the spring members (shock absorbers 64), thereby contributing to expanding the range within which the vehicle posture can be stabilized during cornering.

[0090] In the above embodiment, the weight distribution of the vehicle body 12 may be such that a larger weight is distributed to the wheel unit side equipped with the lean unit than to the wheel unit side equipped with the suspension. This configuration, for example, makes it possible to transmit a larger amount of the lean motor torque generated by the lean unit to the road surface (ground GL), thereby improving the posture control performance of the lean unit.

[0091] 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.

[0092] 10... lean vehicle, 12... vehicle body, 14... wheel, 16... wheel unit, 16R... rear wheel unit, 16F... front wheel unit, 24... control device, 24a... target lean angle acquisition unit, 24b... actual lean angle acquisition unit, 24c... deviation acquisition unit, 24d... motor torque determination unit, 24e... drive control unit, 38A... rear coupling device, 50... rear link mechanism, 52... lean motor, 54... passive suspension, 56... upper arm, 58... lower arm, 64... shock absorber, 66... ​​seesaw arm.

Claims

1. A control device for a lean vehicle, comprising: a plurality of wheel units provided at least at a front position and a rear position of a vehicle body, at least one of which has a pair of wheels spaced apart in the vehicle width direction; a lean unit provided near one of the plurality of wheel units that has the pair of wheels, the lean unit including a lean mechanism that tilts the wheel unit and the vehicle body toward the inside of a turn relative to the ground and a lean drive unit for driving the lean mechanism; and a suspension provided on one of the plurality of wheel units that has the pair of wheels, the suspension generating roll stiffness when the vehicle body tilts in the vehicle width direction relative to the ground, the control device comprising: an acquisition unit that acquires a target tilt angle in the vehicle width direction of the vehicle body determined by the driving operation state of the lean vehicle; an actual tilt angle that is the actual tilt angle in the vehicle width direction of the vehicle body that can change due to the roll stiffness generated by the suspension; and a deviation between the target tilt angle and the actual tilt angle. A lean vehicle control device comprising: a determination unit that determines an output value of the lean drive unit in accordance with a first torque value that resists the roll stiffness and is generated in response to the actual tilt angle, and a second torque value that is generated to eliminate the deviation; and a drive control unit that executes control of the lean drive unit in accordance with the output value.

2. The lean vehicle control device according to claim 1, wherein the determination unit determines the sum of the first torque value and the second torque value as the output value of the lean drive unit.

3. A control device for a lean vehicle as described in claim 1, wherein the determination unit determines the output value of the lean drive unit in accordance with the second torque value in a first region where the actual inclination angle is from zero to a predetermined angle, and determines the output value of the lean drive unit in accordance with the first torque value and the second torque value in a second region where the actual inclination angle is equal to or greater than the predetermined angle.

4. A control device for a lean vehicle as described in claim 1, wherein the drive control unit limits the maximum value of the output torque of the lean drive unit to a torque limit value determined in accordance with the roll stiffness characteristics of the left and right wheels in the wheel unit to which the suspension is attached.

5. A lean vehicle control device as described in claim 4, wherein the torque limit value is a constant value in a first region where the actual inclination angle is from zero to a predetermined angle, and in a second region where the actual inclination angle is equal to or greater than the predetermined angle, the torque limit value decreases from the constant value as the actual inclination angle increases.

6. A lean vehicle control device as described in claim 1, comprising: a front wheel unit provided at a forward position of the vehicle body and having a pair of wheels spaced apart in the vehicle width direction; and a rear wheel unit provided at a rear position of the vehicle body and having a pair of wheels spaced apart in the vehicle width direction, wherein the lean unit is provided on one of the front wheel unit and the rear wheel unit and not on the other, and the suspension that generates the roll stiffness is provided on the other of the front wheel unit and the rear wheel unit and not on one.

7. A lean vehicle control device as described in claim 6, wherein the lean mechanism has a first support member connected to the wheel and a second support member connected to the vehicle body, the lean drive unit tilts the vehicle body by moving the first support member and the second support member relative to each other, and the drive amount of the lean drive unit and the relative movement amount between the first support member and the second support member are in a linear relationship.

8. The lean vehicle control device according to claim 7, wherein the lean mechanism comprises: a first vertical link member connected to one of the wheels and extending in the vehicle height direction; a second vertical link member connected to the other wheel and extending in the vehicle height direction; a first lateral link member having one end rotatably connected to the upper end of the first vertical link member and the other end rotatably connected to the upper end of the second vertical link member, and extending in the vehicle width direction; a second lateral link member having one end rotatably connected to the lower end of the first vertical link member and the other end rotatably connected to the lower end of the second vertical link member, and extending in the vehicle width direction; and a third vertical link member having one end rotatably connected to an intermediate portion of the first lateral link member and the other end rotatably connected to an intermediate portion of the second lateral link member; and the lean drive unit is connected to the one end of the third vertical link member and the intermediate portion of the first lateral link member, and moves the third vertical link member and the first lateral link member relative to each other.

9. A lean vehicle control device as described in claim 6, wherein the suspension is a passive suspension having: a pair of upper arms provided on the left and right wheels, one end of which is rotatably connected to the wheel and the other end of which is rotatably connected to the vehicle body; a pair of lower arms spaced apart in the vehicle height direction from the upper arms, provided on the left and right wheels, one end of which is rotatably connected to the wheel and the other end of which is rotatably connected to the vehicle body; and a pair of shock absorbers, one end of which is connected to either the pair of upper arms or the pair of lower arms and the other end of which is connected to the vehicle body.

10. The lean vehicle control device according to claim 9, wherein the passive suspension has a seesaw arm whose center is connected to the vehicle body so as to be able to rotate by a predetermined amount and whose both ends are connected to the other ends of the pair of shock absorbers.

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