Lean vehicle

Abstract

To provide a lean vehicle that is simple to be capable of reducing cost in which stable travel performance can be kept, and stable lean position can be realized at the time of turning.SOLUTION: A lean vehicle comprises: a plurality of wheel units with a pair of wheels apart from each other in a vehicle width direction which are arranged at least at a front position and a rear position; a lean unit which is arranged in the vicinity of one of the wheel units and includes a lean mechanism inclining the wheel unit and a vehicle body relative to a ground surface in a turning inside direction and a lean drive part to drive the lean mechanism; and a passive suspension which is arranged at the other of the wheel units where roll stiffness is generated when the vehicle body is inclined in the vehicle width direction relative to the ground surface.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to lean vehicles. [Background technology]

[0002] Conventionally, various powered vehicles for small passengers, for example, small vehicles for one person, have been put into practical use as one of the easy means of transportation. In the case of such vehicles for small passengers, the size is reduced by shortening the length in the front-rear direction of the vehicle and narrowing the vehicle width. On the other hand, narrowing the vehicle width makes it difficult to maintain the vehicle's independence, and for example, the vehicle posture may become unstable due to the centrifugal force generated in the outside direction of the turn when the vehicle turns. For this reason, a lean vehicle has been proposed that includes a lean mechanism that can balance the centrifugal force generated in the outside direction of the turn when the vehicle turns by relatively tilting the vehicle body and the road surface (the wheels that are in contact with the ground) in the vehicle width direction (inside direction of the turn) depending on the driving state, thereby improving the stability of the vehicle posture. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-160610 A Summary of the Invention [Problem to be solved by the invention]

[0004] In order to make lean vehicles such as those described above more widespread, it is desirable to provide a simple structure that can maintain stable driving performance while realizing a stable lean posture when cornering, as well as a configuration that can easily reduce costs.

[0005] Therefore, one of the problems that the embodiments of the present invention aim to solve is to provide a lean vehicle that is simple and allows for cost reduction, which can achieve a stable lean posture when cornering while maintaining stable driving performance. [Means for solving the problem]

[0006] A lean vehicle as an example of the present disclosure comprises a plurality of wheel units provided at least at the front and rear positions of the vehicle body and equipped with a pair of wheels spaced apart in the vehicle width direction, a lean unit provided near one of the wheel units and equipped with a lean mechanism that tilts the wheel unit and the vehicle body relative to the ground in the inward direction of a turn and a lean drive unit for driving the lean mechanism, and a passive suspension provided on the other wheel unit and generating roll rigidity when the vehicle body leans in the vehicle width direction relative to the ground.

[0007] According to the above configuration, for example, a lean unit is disposed on at least one of the wheel units at the front and rear of the vehicle body, and a passive suspension is disposed on 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 during cornering while maintaining stable driving performance by performing a good balance between roll suppression by the roll rigidity of the passive suspension and tilt control by the lean unit, and a configuration that can be more easily reduced in cost. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an exemplary schematic side view showing the configuration of a lean vehicle according to an embodiment. [Diagram 2] FIG. 2 is an exemplary schematic image diagram showing a state in which the lean vehicle according to the embodiment is not inclined in the vehicle width direction when viewed from the rear side. [Diagram 3] FIG. 3 is an exemplary schematic image diagram showing a state in which the lean vehicle according to the embodiment is tilted in the vehicle width direction (inner turning direction) when viewed from the rear side. [Figure 4] FIG. 4 is an exemplary schematic perspective view showing the configuration of a passive suspension provided on the front wheels of a lean vehicle according to an embodiment. [Diagram 5]FIG. 5 is an exemplary schematic image diagram showing a state in which the lean vehicle according to the embodiment is not inclined in the vehicle width direction when viewed from the front side. [Figure 6] FIG. 6 is an exemplary schematic image diagram showing a state in which the lean vehicle according to the embodiment is tilted in the vehicle width direction (inner turning direction) when viewed from the front side. [Figure 7] FIG. 7 is an exemplary schematic block diagram showing the configuration of a control device that performs lean control in a lean vehicle according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0010] 1 is an exemplary schematic side view showing the configuration of a lean vehicle 10 according to an embodiment. In the lean vehicle 10 of this embodiment, a lean unit is disposed on at least one of the wheel units at the front and rear positions of the vehicle body, and a passive suspension capable of generating roll stiffness is disposed on the other wheel unit. With this configuration, the lean vehicle 10 is configured to maintain stable driving performance, particularly driving stability during cornering, while realizing cost reduction compared to a vehicle equipped with lean units on the front and rear wheels.

[0011] In FIG. 1, the lean vehicle 10 is placed on a horizontal ground surface GL and is not tilted. In FIG. 1, a forward direction DF, a backward direction DB, an upward direction DU, a downward direction DD, a right direction DR, and a left direction DL are shown. The forward direction DF is the forward direction of the lean vehicle 10 (i.e., the forward direction), and the backward direction DB is the opposite direction to the forward direction DF. The upward direction DU is a vertically upward direction, and the downward direction DD is a 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 vehicle for one person. The lean vehicle 10 has a plurality of wheel units 16 (rear wheel unit 16R, front wheel unit 16F) provided at least at a front position and a rear position of a vehicle body 12 and equipped with a pair of wheels 14 spaced apart in the vehicle width direction (right direction DR, left direction DL). That is, the lean vehicle 10 in this embodiment is a four-wheel vehicle. Note that FIG. 1 is a view of the lean vehicle 10 as seen from the right side, and for the sake of explanation of the structure, 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 a drive motor, a reduction mechanism, or the like, 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-driven 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. In another embodiment, the rear wheel unit 16R may be a non-driven wheel, and the front wheel unit 16F may be a driving wheel that can rotate in the left-right direction. In addition, 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 a front position and a rear position, and may have, for example, six or more wheels.

[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 front direction DF side of the bottom 12b, a front portion 12d extending from an upper end of the front wall 12c toward the front direction DF, a rear wall 12e connected to the rear direction DB side of the bottom 12b, and a rear portion 12f extending from an upper end of the rear wall 12e toward the rear direction DB. The main body 12a has, 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 in the drawings, 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 portion 18a and a backrest portion 18b so that the driver can adjust the depression of an accelerator pedal 20 and a brake pedal 22 and can turn a steering wheel 26 while in a seated position.

[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 called input angle) of the steering wheel 26 relative to a predetermined rotation position (sometimes called straight-line rotation position) indicating straight travel is an example of turning target information indicating a target direction of turning and a target degree of turning. In this embodiment, "input angle = zero" indicates straight travel, "input angle > zero" indicates right turning, and "input angle < zero" indicates left turning. 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 mechanical steering mechanism that is mechanically connected, or may be realized by a steer-by-wire that is electrically connected.

[0019] A direction sensor 28 is fixed to a part 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 an arbitrary direction, for example, a three-axis acceleration sensor. The direction of the acceleration detected by the acceleration sensor 30 is called the detection direction. When the lean vehicle 10 is stopped, the detection direction is the same as the vertical downward direction DD. The gyro sensor 32 is a sensor that detects an angular velocity around a rotation axis in an arbitrary direction, for example, a three-axis angular velocity sensor. The control unit 34 identifies the roll angle and the yaw angular velocity using a signal from the acceleration sensor 30, a signal from the gyro sensor 32, and, for example, a signal from a speed sensor 36 arranged 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 inclination 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 the lean vehicle 10, the rear wheel unit 16R arranged on the rear direction DB side of the rear wall portion 12e of the 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 shows an example in which the rear wheels 14 are rotated and driven by a power transmission mechanism such as a drive motor 40 and a speed reduction 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 a lean mechanism) of the lean unit described later, and various devices mounted on the lean vehicle 10. Therefore, the weight distribution of the vehicle body 12 of the lean vehicle 10 of this embodiment is such that the rear wheel unit 16R side having the lean unit is more distributed than the front wheel unit 16F side (a suspension mounted side described later) not having the lean unit. As a result, it is possible to transmit more of the lean motor torque generated by the lean unit to the road surface (ground GL), and the posture control performance by the lean unit can be improved. The drive motor 40 has its rotation controlled in response to the depression amount of the accelerator pedal 20, and drives the rear wheels 14 to rotate via a speed reduction mechanism 42. Well-known configurations can be used for the drive motor 40, the power transmission mechanism using the speed reduction mechanism 42, the battery 44, etc., 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 that functions as a suspension is interposed between the middle part of the rear connecting bar 46A and the vehicle body 12. As a result, the rear wheel unit 16R (the wheel 14 that is the rear wheel) and the vehicle body 12 can move (rotate) relative to each other in the vertical direction. For example, when traveling on a ground GL with unevenness, the rear wheel unit 16R mainly displaces vertically, reducing the transmission of vertical vibration to the vehicle body 12 side. In the case of the configuration of FIG. 1, only one rear spring member 48 is present at approximately the center in 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 connecting mechanism 38B described later) and the vehicle body 12 are connected by a front connecting bar 46B. An end 46Ba of the front connecting 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 showing a state in which the lean vehicle 10 is not inclined in the vehicle width direction when viewed from the rear side of the lean vehicle 10. Fig. 3 is an exemplary and schematic image diagram showing a state in which the lean vehicle 10 is inclined in the vehicle width direction (turning inner direction) when viewed from the rear side of the lean vehicle 10. Note that, in Figs. 2 and 3, the power transmission mechanism such as the drive motor 40 and the reduction mechanism 42 of the rear coupling device 38A is omitted in order to make it easier to understand the behavior of the lean vehicle 10.

[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 in the turning inward direction) 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 a function of tilting the rear wheel unit 16R (wheel unit) and the vehicle body 12 in the turning inward direction relative to the ground. The rear link mechanism 50 has three vertical link members 50a, 50b, 50c arranged in order toward the right direction DR, and two horizontal link members 50d, 50e arranged in order toward the downward direction DD. As shown in FIG. 2, when the lean vehicle 10 stands upright without tilting on a horizontal ground GL (i.e., ground GL perpendicular to the vertical upward direction DU) (position SR1), the vertical link members 50a, 50b, 50c are parallel to the vertical direction, and the horizontal link members 50d, 50e are parallel to the horizontal direction. 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 parts of the two horizontal link members 50d, 50e. 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 a plurality of link members. For example, the bearing 54a rotatably connects the vertical link member 50b and the horizontal link member 50e. The bearing 54b rotatably connects the vertical link member 50a and the horizontal link member 50e. The bearing 54c rotatably connects the vertical link member 50c and the horizontal link member 50e. The other link members are also rotatably connected to each other by bearings. The rotation shafts of the bearings 54a, 54b, etc. that connect each link member extend from the rear direction DB side toward the front direction DF side (in this embodiment, the rotation shafts are parallel to the front direction DF). The two link members connected to each other can rotate relatively around the rotation shafts within a predetermined angle range (for example, a range less than 180 degrees). With this structure, the rear link mechanism 50 can realize a structure that tilts the rear wheel unit 16R and the vehicle body 12 in the turning inner direction (vehicle width direction) relative to the ground GL. For example, when the lean vehicle 10 turns, as shown in FIG. 3, the lean vehicle 10 tilts in the inside direction (right direction DR) to resist the centrifugal force generated in the outside direction (left direction DL). When the vehicle body is tilted in the inside direction to resist the centrifugal force, the lean vehicle 10 is stable during turning, but when the centrifugal force becomes large and the vehicle body 12 is swung in the outside direction, the stability decreases. Therefore, in order to continue turning smoothly, it is necessary to intentionally tilt the lean vehicle 10 to the inside of the turn. Therefore, the rear link mechanism 50 intentionally tilts the lean vehicle 10 in the inside direction by the lean motor 52, 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 to, for example, 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. As a result, the wheel 14 (body 12) tilts in the turning inner direction (i.e., rightward or leftward in the vehicle width direction). Such a tilting 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 horizontal link member 50d may be connected via a gear. Hereinafter, the torque generated by the lean motor 52 is also called a lean motor torque. The lean motor torque rolls the body 12. That is, a control can be realized to tilt the rear wheel unit 16R and the body 12 in the turning inner direction relative to the ground GL. In another embodiment, the lean motor may be fixed to the rear wheel unit 16R, and the output side (rotary 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 relatively to each other, so that the rear wheel unit 16R and the vehicle body 12 may be tilted toward the inside of the turn relative to the ground GL.

[0028] The posture SR1 shown in FIG. 2 indicates a state in which the lean vehicle 10 is upright, and the posture SR2 shown in FIG. 3 indicates a state in which the lean vehicle 10 is inclined with respect to the horizontal ground GL. As shown in the posture SR1, when the horizontal link member 50d is perpendicular to the vertical link member 50b, the rear wheels 14 are upright with respect to the horizontal ground GL. Then, 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 inclined, 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 posture 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 operation 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, for example, on the ground surface GL that has irregularities, the transmission of vertical vibrations to the vehicle body 12 is reduced, which can contribute to improving the traveling stability.

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

[0031] In the posture SR2 shown in Fig. 3, the vehicle body upward direction DVU is inclined 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 the forward direction DF will be referred to as the roll angle Ar or the inclination angle Ar. Here, "Ar>zero" indicates inclination toward the right direction DR, and "Ar<zero" indicates inclination 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 showing the posture SR2 shows 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 horizontal link member 50d. In the rear view showing the posture SR2, "ACr = zero" indicates that the vertical link member 50b is perpendicular to the horizontal link member 50d. "ACr > zero" indicates that the vertical link member 50b has rotated clockwise relative to the horizontal 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 horizontal link member 50d from the "ACr = zero" state. As shown in the figure, when the lean vehicle 10 is located on a horizontal ground surface GL (i.e., a ground surface GL perpendicular to the vertical upward direction DU), the rear control angle ACr is approximately the same as 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 capable of tilting the front wheels 14 in the vehicle width direction while generating greater roll rigidity as the inclination (roll) of the vehicle body 12 increases. Therefore, the vehicle body 12 can also be tilted in the vehicle width direction relative to the ground on the front wheel side. In other words, the lean vehicle 10 can adjust the posture of the vehicle body 12 in the vehicle width direction according to the driving state and road surface condition, 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 in the turning inward direction by the lean motor 52, thereby maintaining a balance with the centrifugal force generated during turning. In this case, the wheels 14 on the front wheel side can also roll due to the roll.

[0035] The rear link mechanism 50 and a front wheel side link mechanism described later are an example of a tilting device configured to tilt the vehicle body 12 in the vehicle width direction of the lean vehicle 10 (they may also be called a front tilting device or a rear tilting device). The lean motor 52 is an example of a drive device configured to generate a drive force (i.e., lean motor torque) that drives the rear tilting device (they may also be called a rear drive device). The drive force of the rear drive device is a force that rolls the vehicle body 12 in the turning inner direction relative to the wheels 14, which are a pair of rear wheels.

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

[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 called a front connecting mechanism 38B) included in the front wheel unit 16F and is provided on the front wheel side of the lean vehicle 10. Note that Fig. 4 explains the basic operation of the passive suspension 54, and members that are not involved in the explanation are omitted from the illustration.

[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 type passive suspension 54 is a well-known structure, and detailed description 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. The upper arm 56 and the lower arm 58 have ends farther from the wheels 14 rotatably connected to a part of the vehicle body 12, and ends closer to the wheels 14 rotatably connected to a hub knuckle 62 connected to the wheels 14 via a ball joint 60. The hub knuckle 62 has one end rotatably connected to the upper arm 56 and the other end rotatably connected to the lower arm 58, so that it can swing in the vehicle width direction about the approximate center of the hub knuckle 62, allowing the wheels 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 the centrifugal force during turning, i.e., a force that suppresses the lean vehicle 10 from swinging in the outside direction during turning. 4, one end (lower end) of the shock absorber 64 is rotatably connected to the lower arm 58. In other embodiments, the one end (lower end) of the shock absorber 64 may be connected to the upper arm 56.

[0040] A seesaw arm 66 extending in the vehicle width direction is connected to the other end (upper end) of the shock absorber 64 in the passive suspension 54 of this embodiment. The seesaw arm 66 is, for example, an arc-shaped plate member, and the upper end sides of the left and right shock absorbers 64 are rotatably connected to both ends of the seesaw arm 66. In addition, the center of the seesaw arm 66 is rotatably connected to a part of the vehicle body 12. The seesaw arm 66 has a function of swinging before the shock absorber 64 expands and contracts, thereby enabling the lean vehicle 10 to tilt. In other words, the start of the expansion and contraction operation of the shock absorber 64 can be delayed. As a result, the lean vehicle 10 can tilt the wheels 14 (front wheels) in the turning inner direction (vehicle width direction) of the lean vehicle 10 by the amount of expansion and contraction of the shock absorber 64 and the amount of swinging of the seesaw arm 66. In other words, the amount of inclination of the wheels 14 (front wheels) can be expanded beyond the expansion and contraction capacity of the shock absorbers 64, which contributes to expanding the range within which the vehicle attitude can be stabilized during cornering.

[0041] Moreover, the passive suspension 54 including the seesaw arm 66 can prevent the generation of roll stiffness in a first region (first angle range) from the start of the tilt of the vehicle body 12 to a predetermined angle (up to the swing range of the seesaw arm 66). Moreover, 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) further tilted from the first region. That is, the passive suspension 54 of this embodiment is configured to have different roll stiffness characteristics according to the degree of tilt of the lean vehicle 10. That is, in a region where the tilt is small (first region), the roll stiffness is reduced in order to prioritize ease of tilting (ease of leaning), and in a region where the tilt is large (second region), the roll stiffness is increased in order to prioritize roll suppression. 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 easy to achieve a lean posture of the lean vehicle 10. Also, when the centrifugal force becomes large, it is possible to reduce instability of the tilt posture of the lean vehicle 10 (front wheels 14) due to the increased roll rigidity (improve posture maintenance ability).

[0042] The operation of the front wheel unit 16F thus configured will be described with reference to Figs. 5 and 6. Fig. 5 is an exemplary and schematic image diagram showing a state in which the lean vehicle 10 is not tilted in the vehicle width direction (turning inner direction) when viewed from the front side of the lean vehicle 10. Fig. 6 is an exemplary and schematic image diagram showing a state in which the lean vehicle 10 is tilted in the turning inner direction when viewed from the front side of the lean vehicle 10. In Figs. 5 and 6, the upper arm 56, the lower arm 58, the hub knuckle 62, the shock absorber 64, and the seesaw arm 66 of the front wheel unit 16F (passive suspension 54) are illustrated typically, and other configurations are omitted from the illustration, in order to make it easier to understand the behavior of the lean vehicle 10. In addition, Figs. 2 and 3 described above show the lean vehicle 10 as viewed from the rear side, and Fig. 3 shows the lean vehicle 10 turning right. 5 and 6 are views of the lean vehicle 10 as viewed 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 constituting 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 in the up and down direction in response to the unevenness of the ground GL. In other words, the influence of the unevenness of the ground GL is suppressed from being transmitted to the vehicle body 12, contributing to an improvement in ride comfort. In addition, 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 be tilted in the turning inward direction (vehicle width direction) with respect to the ground GL, similar to the rear wheel unit 16R (rear link mechanism 50).

[0044] For example, as in the posture SF1 of FIG. 5, when the lean vehicle 10 stands upright on a horizontal ground surface GL (i.e., ground surface GL perpendicular to the vertical upward direction DU) without inclining, the upper arm 56 and the lower arm 58 are parallel to the horizontal direction. In this case, the shock absorber 64 is in a steady state, and basically no spring force is generated. When the ground surface GL is uneven and the left and right wheels 14 are displaced upward or downward at the same time, the left and right upper arms 56 and the left and right lower arms 58 rotate in opposite directions to absorb the amount of displacement caused by the unevenness. Also, when the ground surface GL is uneven and one wheel 14 is displaced upward or downward in response to the unevenness, the upper arm 56 and the lower arm 58 rotate in the same direction in response to the unevenness to absorb the amount of displacement caused by the unevenness. In this case, when 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, when the degree of unevenness exceeds the swing range of the seesaw arm 66, the shock absorber 64 begins to expand or contract, and the swing of the seesaw arm 66 and the expansion and contraction of the shock absorber 64 absorb the amount of displacement due to the unevenness.

[0045] Next, the behavior of the front wheel unit 16F (passive suspension 54) when the lean vehicle 10 turns will be described with reference to Fig. 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, in order to cancel the 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) with respect to the ground GL.

[0046] For example, as shown in the posture SF2 in FIG. 6, when the lean vehicle 10 turns left, it is necessary to tilt the lean vehicle 10 to the left, which is the inside of the turn, to balance the centrifugal force generated in the outside of the turn. As described above, the lean vehicle 10 can be intentionally tilted (leaned) in the inside of the turn 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 executed based on a target tilt angle (turn 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 device. In this case, the target lean angle and the actual lean angle may differ depending on the driving state, road surface state, etc. Therefore, the lean vehicle 10 controls the lean motor torque generated by the lean motor 52 of the rear wheel unit 16R 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), in the initial stage of the lean vehicle 10 tilt, that is, when the centrifugal force is small and the amount of rotation of the lower arm 58 (upper arm 56) is within the swing range (first region) of the seesaw arm 66 to which the shock absorber 64 is connected, 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. In other words, if the lean motor 52 generates a lean motor torque so as to realize the target lean angle, the ideal turning posture of the lean vehicle 10 can be easily realized. 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 swing range of the seesaw arm 66 is exceeded (in the case of the second region), the shock absorber 64 starts to expand or contract, generating a repulsive force, and the roll rigidity increases, so that it becomes resistant to the increased centrifugal force. In this case, the shock absorber 64 on the inside of the turn is compressed, and the shock absorber 64 on the outside of the turn is 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 tries to tilt the lean vehicle 10 toward the inside of the turn to balance with the centrifugal force generated in the outside of the turn, making it difficult to tilt the lean vehicle 10 toward the inside of the turn. In other words, it may be difficult to achieve the ideal turning posture of the lean vehicle 10 by simply controlling the lean motor 52 to the target lean angle.

[0048] Therefore, in this embodiment, the lean motor 52 is controlled to generate a lean motor torque that cancels the roll stiffness generated by the shock absorber 64 on the wheel unit side where no lean unit is mounted, in accordance with the roll stiffness generated by the shock absorber 64 on the wheel unit side.

[0049] FIG. 7 is an exemplary schematic block diagram showing the configuration of the control device 24 that performs lean control in the 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 corresponding to the driving requested by the driver from the speed sensor 36 (vehicle speed of the lean vehicle 10) and the rotation angle (input angle) of the steering wheel 26, for example, by using a map created in advance by testing or the like. In addition, the actual lean angle acquisition unit 24b can acquire an actual lean angle indicating the actual inclination state of the lean vehicle 10 at present, by an inertial measurement device included in the direction sensor 28 provided on the rear wall portion 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. Then, the motor torque determination unit 24d determines a lean motor torque that eliminates the deviation between the target lean angle and the actual lean angle acquired by the deviation acquisition unit 24c. The drive control unit 24e drives and controls the lean motor 52 so as to output the lean motor torque determined by the motor torque determination unit 24d.

[0050] For example, when the actual lean angle becomes smaller than the target lean angle due to the repulsive force (roll stiffness) generated by the expansion and contraction of the shock absorber 64, that is, when the lean vehicle 10 is insufficient in inclination, the lean motor 52 is correctively controlled to generate a lean motor torque in a direction to increase the inclination. Conversely, when the actual lean angle becomes larger than the target lean angle due to a sudden change in road surface conditions, that is, when the lean vehicle 10 is too large in inclination, the lean motor 52 is correctively controlled to generate a lean motor torque in a direction to decrease the inclination (to raise the attitude of the lean vehicle 10). The correction value of the lean motor 52 at this time can be determined, for example, by using a map created in advance by testing or the like. This map can be, for example, associated with the lean motor torque of the lean motor 52 for canceling the roll stiffness generated by the expansion and contraction of the shock absorber 64.

[0051] Therefore, according to the lean vehicle 10 of this embodiment, it is possible to realize an ideal turning 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 absorber 64. As a result, it is possible to provide a lean vehicle 10 with a simple structure that can realize a more stable lean posture during turning while maintaining stable driving performance by performing a good balance between roll suppression by the roll rigidity of the suspension (shock absorber 64) of the front wheel unit 16F and tilt control by the lean unit of the rear wheel unit 16R, and a configuration that can be more easily reduced in cost.

[0052] In this way, by arranging a lean unit on at least one of the wheel units at the front position (front wheels) and the rear position (rear wheels) of the lean vehicle 10 and arranging a passive suspension 54 on the other wheel unit, the structure and control can be simplified compared to a configuration in which lean units are arranged at both the front and rear positions and both are controlled, which can contribute to reducing the cost of the lean vehicle 10. Also, 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.

[0053] In the example shown in FIG. 4, the seesaw arm 66 is used to expand the range of stabilization of the vehicle posture during turning. In another embodiment, instead of the seesaw arm 66, a structure that can prevent roll stiffness in the vicinity (first region) where the tilt (roll angle) of the vehicle body 12 is small may be used to obtain a similar effect. For example, the passive stabilizer may be installed in a manner that has a free running section, so that the roll stiffness is not generated in the vicinity (first region) where the roll angle is small, and the expansion and contraction operation of the shock absorber 64 may be delayed (i.e., the expansion and contraction may be started in the second region), and the overall amount of tilt may be increased to expand the range of stabilization of the vehicle posture during turning. Also in this case, when the centrifugal force generated in the outside direction of the turn is small, the lean posture of the lean vehicle 10 can be easily realized by preventing the roll stiffness from being generated in the first region. Also, when the centrifugal force is large, the roll stiffness is generated by the shock absorber 64 in the second region, so that the instability of the tilt posture of the lean vehicle 10 (the wheels 14 on the front wheel side) caused by the generated roll stiffness can be reduced. The spring element included in the passive suspension 54 may be one in which the generated roll stiffness changes stepwise depending on the expansion / contraction state, for example, a variable shock absorber or the like may be used to generate small and large roll stiffness. In this case as well, when the centrifugal force generated in the outside direction of the turn is small, the generated roll stiffness can be reduced to facilitate realizing an appropriate lean posture of the lean vehicle 10. When the centrifugal force increases, the roll stiffness generated in the second region can be increased to reduce instability in the tilt posture of the lean vehicle 10 (front wheels 14).

[0054] As described above, the lean vehicle 10 of this embodiment includes a plurality of wheel units (rear wheel unit 16R, front wheel unit 16F) provided at least at the front and rear positions of the vehicle body 12 and equipped with a pair of wheels 14 spaced apart in the vehicle width direction, a lean unit provided near one of the wheel units and equipped with a lean mechanism (mechanism for tilting the lean vehicle 10 in the turning inner direction) for tilting the wheel unit and the vehicle body 12 relatively to the ground in the turning inner direction and a lean drive unit (lean motor 52) for driving the lean mechanism, and a passive suspension 54 (front coupling mechanism) provided on the other of the wheel units for 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 at the front and rear positions of the vehicle body 12, and a passive suspension 54 is provided on the other wheel unit. Therefore, it is possible to provide a lean vehicle with a simple structure that achieves a more stable lean posture when cornering while maintaining stable driving performance by balancing roll suppression by the roll rigidity of the passive suspension 54 and tilt control by the lean unit, and a configuration that makes it easier to reduce costs.

[0055] In the above embodiment, the passive suspension 54 may have different roll stiffness characteristics in a first region from the start of the inclination of the vehicle body 12 to a predetermined angle and a second region further inclined from the first region. For example, the passive suspension 54 may have a roll stiffness that increases gradually in the first region where the inclination of the vehicle body 12 is small, and a rate of change in the roll stiffness that increases at a higher rate than in the first region in the second region where the inclination exceeds the first region and further increases. In other words, the passive suspension 54 may change the roll stiffness so that the roll stiffness increases as the inclination of the vehicle body 12 increases. In another embodiment, the passive suspension 54 may not generate roll stiffness in the first region, but may generate roll stiffness in the second region where the inclination increases. In other words, the roll stiffness of the passive suspension 54 may be generated when the inclination of the vehicle body 12 (the wheels 14 on the front wheel side) exceeds a predetermined value. With this configuration, in the first region where the inclination is small, the roll stiffness can be reduced to prioritize lean, and in the second region where the inclination is large, the roll stiffness can be increased to prioritize roll suppression. As a result, roll suppression by the roll stiffness of the passive suspension 54 and tilt control by the lean unit can be balanced to achieve a more stable lean posture during cornering while maintaining stable driving performance.

[0056] In the above embodiment, the passive suspension 54 may include a lower arm 58 and an upper arm 56 supporting the wheels 14, a pair of spring members (shock absorbers 64) arranged at a distance in the vehicle width direction and connected at their lower ends to either the lower arm 58 or the upper arm 56, and a seesaw arm 66 having upper ends connected to ends in the vehicle width direction and a central portion rotatably connected to the vehicle body 12. According to this configuration, for example, a structure can be easily realized in which lean is prioritized in a region (first region) where the inclination is small, so that roll stiffness is not generated, and in a region (second region) where the inclination is large, so that roll suppression is prioritized, and roll stiffness is increased. Also, a structure can be easily realized in which the amount of inclination of the lean vehicle 10 is expanded beyond the expansion and contraction capacity of the spring members (shock absorbers 64) to expand the range in which the vehicle posture is stabilized during cornering.

[0057] In the above embodiment, the weight of the vehicle body 12 may be distributed so that the wheel unit side having the lean unit is more heavily weighted than the wheel unit side having the suspension. With this configuration, for example, it becomes possible to transmit more of the lean motor torque generated by the lean unit to the road surface (ground surface GL), thereby improving the posture control performance of the lean unit.

[0058] Although the embodiment and the modified examples of the present disclosure have been described above, the above-mentioned embodiment and the modified examples are merely examples and are not intended to limit the scope of the invention. The above-mentioned novel embodiment and modified examples can be implemented in various forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. The above-mentioned embodiment and modified examples are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0059] 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 plurality of wheel units each including a pair of wheels spaced apart in a vehicle width direction, the wheel units being provided at least at a front position and a rear position of a vehicle body; a lean unit provided near one of the wheel units, the lean unit including a lean mechanism that tilts the wheel unit and the vehicle body toward an inner side of a turn relative to the ground and a lean drive unit that drives the lean mechanism; a passive suspension provided on the other of the wheel units and configured to generate roll stiffness when the vehicle body tilts relative to the ground in the vehicle width direction; A lean vehicle equipped with

2. 2. The lean vehicle according to claim 1, wherein the passive suspension has different roll stiffness characteristics between a first region from a start of the lean of the vehicle body to a predetermined angle and a second region that is further leaned from the first region.

3. 3. The lean vehicle according to claim 2, wherein the passive suspension comprises: a lower arm and an upper arm that support the wheels; a pair of spring members arranged at a distance in the vehicle width direction and having their lower ends connected to one of the lower arm and the upper arm; and a seesaw arm having upper ends connected to ends in the vehicle width direction, respectively, and a central portion connected to the vehicle body so as to be rotatable.

4. 2. The lean vehicle according to claim 1, wherein the weight of the vehicle body is distributed such that a greater weight is distributed to a wheel unit side having the lean unit than to a wheel unit side provided with the passive suspension.

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