JP7632136B2 - Attitude control device - Google Patents

Description

The present invention relates to an attitude control device mounted on a vehicle that can tilt around an axis extending in the front-rear direction.

Patent Document 1 describes an attitude control device mounted on a vehicle that includes three wheels and is capable of tilting around an axis extending in the fore-and-aft direction. In the attitude control device described in Patent Document 1, when the vehicle is accelerating, tilting around the axis extending in the fore-and-aft direction is permitted when the vehicle speed becomes greater than a first set speed, and when the vehicle is decelerating, tilting is restricted when the vehicle speed becomes equal to or less than a second set speed that is greater than the first set speed. This can improve the driving feel for the driver.

Japanese Unexamined Patent Publication No. 59-120586

The objective of the present invention is to improve the posture stability of a vehicle when turning.

Means for solving the problems and effects

The attitude control device according to the present invention is mounted on a vehicle that can tilt around an axis that extends in the fore-and-aft direction of a second vehicle body relative to a first vehicle body, and at the beginning of a turn, the vehicle is turned in the opposite direction to the operating direction of the steering operation member by controlling the difference in rotational speed between the left and right rear wheels. This makes it possible to favorably tilt the vehicle to the inside of the turn determined by the operating direction of the steering operation member, improving the attitude stability of the vehicle when turning.

1 is a perspective view showing a vehicle equipped with an attitude control device according to an embodiment of the present invention; FIG. 2 is a diagram conceptually showing a structure of the attitude control device. FIG. 5 is a flowchart showing a lean lock control program stored in a storage unit of the posture control device. 5 is a flowchart showing a reverse turning rotation speed difference control program stored in the storage unit. 4 is a plan view showing a traveling state of the vehicle when the reverse turning rotation speed difference control program is executed. FIG. 5A to 5C are front views showing the attitude of the vehicle when the reverse turning rotation speed difference control program is executed.

Below, an example of the attitude control device according to the present invention will be described in detail with reference to the drawings. This attitude control device is mounted on a vehicle 8 shown in Figures 1 and 2, but is not limited thereto.

The vehicle 8 shown in Figures 1 and 2 has a total of three wheels: a front wheel 10, a left rear wheel 12 as the left wheel, and a right rear wheel 14 as the right wheel. The vehicle also includes (x) a first body 16 that rotatably holds each of the left and right rear wheels 12, 14, and (y) a second body 24 that has a driver's seat 22 on which a driver sits and rotatably holds the front wheel 10 via a front fork 30. The second body 24 is held on the first body 16 so as to be able to tilt around a lean shaft 26 that extends in the fore-and-aft direction. The axis of the lean shaft 26 corresponds to the fore-and-aft axis.

The front wheel 10 is rotatably held by a pair of legs 32 of the front fork 30. The front fork 30 is also rotatably held relative to the second vehicle body 24, and a steering shaft 36 that can rotate integrally with the steering wheel 20 serving as a steering operation member is connected to a steering column 34 of the front fork 30. When the steering wheel 20 is operated, the steering shaft 36 is rotated about its axis, causing the front fork 30 to rotate relative to the second vehicle body 24, and the front wheel 10 is accordingly steered.

The second vehicle body 24 is also provided with a steering operation amount sensor 40 as a steering operation state detection device that detects the operation angle as the amount of operation of the steering wheel 20. The steering operation amount sensor 40 detects one of the rotation angles in the right direction and the left direction from the neutral position of the steering wheel 20 as a positive value and the other as a negative value. The neutral position of the steering wheel 20 refers to the position when the steering angle of the front wheels 10 is approximately 0.

The second body 24 is integrally mounted on the lean shaft 26 so as to be tiltable about the longitudinal axis, while the lean shaft 26 is held so as to be rotatable relative to the first body 16 about the longitudinal axis. In addition, the first body 16 is provided with a lean lock device 50, which can be switched between a state in which rotation of the lean shaft 26 about the axis relative to the first body 16 is permitted and a state in which rotation is restricted.

The lean lock device 50 may include, for example, a so-called electric brake that includes a rotating body that is rotatable integrally with the lean shaft 26, a friction engagement member, and an electric pressing device that presses the friction engagement member against the rotating body. The electric pressing device presses the friction engagement member against the rotating body, thereby restricting the rotation of the lean shaft 26 around its axis, and the friction engagement member is moved away from the rotating body, thereby allowing the rotation of the lean shaft 26 around its axis. The lean lock device 50 may also include a so-called electromagnetic clutch that includes a convex portion forming member having an engaging convex portion provided on the lean shaft 26, a concave portion forming member having an engaging concave portion provided on the first vehicle body 16, and an electric approach/separation device that moves the concave portion forming member toward and away from the convex portion forming member. The electric approach/separation device brings the recess-forming member closer to the protrusion-forming member, engaging the engaging protrusion and engaging recess, restricting rotation of the lean shaft 26, and moves the recess-forming member away from the protrusion-forming member, disengaging the engaging protrusion and engaging recess, allowing rotation of the lean shaft 26.

The left and right rear wheels 12, 14 are provided with in-wheel motors 12m, 14m (see FIG. 3) as drive devices for the vehicle 8. The in-wheel motor 12m corresponds to the left drive device, and the in-wheel motor 14m corresponds to the right drive device. The in-wheel motors 12m, 14m apply drive force to the left and right rear wheels 12, 14, respectively. In the vehicle 8, the left and right rear wheels 12, 14 are drive wheels.

The vehicle 8 is provided with a control device 60 that controls the vehicle 8. The control device 60 is provided with an ECU 62, which is mainly a computer, a steering operation amount sensor 40, the front wheels 10, and the left and right rear wheels 12, 14, and is connected to wheel speed sensors 64F, 64RL, 64RR that detect the rotation speed of the wheels, a lean angle sensor 66 as a lean angle detection device that detects the lean angle, which is the rotation angle of the lean shaft 26 relative to the first body 16, an accelerator operation state detection device 70 that detects the operation state of an accelerator pedal 68 as an accelerator operation member operated by the driver, a brake operation state detection device 74 that detects the operation state of a brake pedal 72 as a brake operation member, and the like, and is also connected to the lean lock device 50 and in-wheel motors 12m, 14m via drive circuits 76, 77, 78, respectively.

The ECU 62 detects the traveling speed v of the vehicle 8 based on the detection values of the wheel speed sensors 64F, 64RL, 64RR. The ECU 62 also controls the in-wheel motors 12m, 14m, etc. based on the operation states of the accelerator pedal 68 and the brake pedal 72 detected by the accelerator operation state detection device 70 and the brake operation state detection device 74. The driving and braking of the vehicle 8 are controlled by controlling the in-wheel motors 12m, 14m.

The lean lock device 50 is controlled based on the traveling speed v of the vehicle 8. The lean lock device 50 is controlled in accordance with a lean lock control program shown in the flowchart of Fig. 4. The lean lock control program is executed at predetermined set time intervals.
In step 1 (hereinafter abbreviated as S1, the same applies to the other steps), the running speed v is detected based on the detection values of the wheel speed sensors 64F, 64RL, 64RR, and in S2, it is determined whether the running speed v is greater than a set speed v0. If the determination is YES, in S3, the lean lock device 50 is controlled to release the lock and allow the lean shaft 26 to rotate. On the other hand, if the determination is NO, in S4, the lean lock is established and the rotation of the lean shaft 26 is restricted.

When the vehicle 8 is traveling at a low speed, it is preferable to lock the lean of the second body 24 relative to the first body 16 in order to ensure posture stability. The set speed v0 is set with this in mind, and can be called the speed at which lean lock is preferable, in other words, the speed at which left-right lean is acceptable.

Furthermore, in this vehicle 8, the ratio (H/W) of the height H of the center of gravity G from the lean axis 26 to the vehicle width W of the second body 24 is large, and the ratio H/W is 0.5 or more.
Thus, the vehicle 8 is a small vehicle, and the value of H/W is large. Therefore, in order to ensure posture stability, it is desirable to tilt the second body 24 inward during turning. However, during turning, the second body 24 is likely to tilt outward due to centrifugal force. Also, it is possible for the driver seated in the driver's seat 22 of the second body 24 to tilt the second body 24 inward by tilting his/her body inward, but this requires advanced technology. Therefore, in this embodiment, the driving forces (driving force difference) applied to each of the left and right rear wheels 12, 14 are controlled at the beginning of turning, and the vehicle 8 is turned in the opposite direction to the direction of operation of the steering wheel 20 by controlling the rotational speed difference between the left and right rear wheels 12, 14.

When the vehicle 8 is turned in the opposite direction to the steering wheel 20 operation, centrifugal force causes the second body 24 to tilt outward, but the direction of this tilt corresponds to the inward direction of the steering wheel 20 operation. When the vehicle 8 then turns in the direction of the steering wheels 10, the second body 24 can be satisfactorily tilted inward. This control is called reverse turning rotational speed difference control.

In the ECU 62, a reverse turning rotation speed difference control program shown in the flow chart of FIG. 5 is executed at predetermined set time intervals.
In S11, the traveling speed v is detected, the steering operation amount sensor 40 detects the operation angle φ from the neutral position of the steering wheel 20, and in S12, it is determined whether the traveling speed v is greater than a set speed v0, and in S13, it is determined whether the absolute value of the operation angle φ is greater than a set value (set operation angle) φ0. The set value φ can be set to an operation angle that is considered to be desirable for ensuring posture stability by tilting the second body 24 inward during turning.

If the determination in either S12 or S13 is NO, S11 to S13 are repeatedly executed. If the determination in S12 or S13 becomes YES, the reverse turning rotational speed difference control is started. In S14, the direction of operation is detected based on the positive or negative operation angle φ, and in S15, the rotational speeds of the left and right rear wheels 12 and 14 are detected. Then, in S16, the in-wheel motors 12m and 14m are controlled so that the rotational speed of the wheel on the inside of the turn, determined by the operation direction determined in S14, is made greater than the rotational speed of the wheel on the outside of the turn by a set value (set speed difference) d.

Then, in S17, the lean angle θ (inclination angle), which is the rotation angle of the lean shaft 26, is detected by the lean angle sensor 66. Then, it is determined whether the absolute value of the lean angle θ is greater than a set value (set lean angle) θ0. The set lean angle θ0 can be set to a value at which the second body 24 is considered to be definitely inclined, or a value determined by the operating angle φ of the steering wheel 20. The set lean angle θ0 can be a constant value or a variable value.

If the determination in S23 is NO, in S19, the set speed difference d, i.e., the difference in rotation speed between the left and right rear wheels 12, 14, is increased by α (d+α), and the process returns to S15. Thereafter, S15 to S19 are repeatedly executed until the absolute value of the lean angle θ becomes larger than the set lean angle θ0. The difference in rotation speed between the left and right rear wheels 12, 14 is gradually increased.
When the determination in S19 becomes YES, the reverse turning rotation speed difference control is ended in S20.

As shown in Figures 6(a) and 7(a), for example, when the driver operates the steering wheel 20 to the left, reverse turning rotational speed difference control is performed, and the rotational speed of the left rear wheel 12 is made greater than the rotational speed of the right rear wheel 14. This causes the vehicle 8 to turn to the right. Although the front wheels 10 are steered to the left, the first body 16 and the second body 24 are pushed to the right due to the difference in rotational speed between the left and right rear wheels 12, 14, and the vehicle 8 is turned to the right.

As shown in Figures 6(b) and 7(b), when the vehicle 8 turns to the right, centrifugal force acts on the vehicle 8, causing the vehicle 8 to tilt to the left. When the lean angle θ, which is the angle of tilt to the left, becomes larger than the set lean angle θ0, the reverse turning rotational speed difference control is terminated, as shown in Figures 6 and 7(c). This causes the vehicle 8 to turn in the direction of the steering angle of the front wheels 10, i.e., to the left. In this case, the second body 24 is in a state of being tilted to the left, which is the inside of the turn.

As shown in FIG. 6, a normal four-wheel vehicle V turns along the trajectory shown by dashed line A in the turning direction of the steering wheel. In contrast, the present vehicle 8 turns along the trajectory shown by solid line B in the opposite direction to the operation direction of the steering wheel 20, and then turns in the operation direction of the steering wheel 20. This allows the second body 24 to be tilted effectively to the inside of the turn, making it less likely to tip over due to centrifugal force and improving posture stability.

In this embodiment, the reverse turning rotational speed difference control gradually increases the rotational speed difference between the left and right rear wheels 12, 14. This prevents the vehicle 8 from being suddenly turned in the opposite direction to the direction of the steering wheel 20 due to a sudden increase in the rotational speed difference, suppresses the driver's discomfort, and suppresses a decrease in the running stability of the vehicle 8.
Furthermore, since there is no need to provide a steering mechanism for steering the front wheels 10 by a steering actuator, the structure can be simplified and costs can be reduced accordingly.

As described above, in this embodiment, the steering operation amount sensor 40, the wheel speed sensors 64F, 64RL, 64RR, the lean angle sensor 66, the lean lock control program of the ECU 62 shown in the flowchart of FIG. 4, and the reverse rotational speed difference control program shown in the flowchart of FIG. 5 are included in the control device 60, and the posture control device is configured by the parts that store and execute the reverse rotational speed difference control program shown in the flowchart of FIG. 5 and the like. The rotational speed difference control unit is configured by the parts that store and execute the lean lock control program shown in the flowchart of FIG. 4 and the like.

Although the set lean angle θ0 is a fixed value, it can be determined based on the operation angle φ of the steering wheel 20. When the operation angle φ is large, it can be set to a larger value than when the operation angle φ is small.
Furthermore, the structure of the vehicle is not important. For example, brakes may be provided on the front wheels 10 and the left and right rear wheels 12, 14. The present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art.

8: Vehicle 10: Front wheels 12, 14: Left and right rear wheels 12m, 14m: In-wheel motor 16: First vehicle body 20: Steering wheel 22: Driver's seat 24: Second vehicle body 26: Lean axis 40: Steering angle sensor 50: Lean lock device 60: Control device 62: ECU 64: Wheel speed sensor 66: Lean angle sensor

Patentable inventions

(1) A posture control device for controlling a posture of a vehicle including a first vehicle body that rotatably holds left and right wheels, which are drive wheels, and a second vehicle body that has a driver's seat in which a driver sits and is tiltable about a front-rear axis that is an axis that extends in the front-rear direction relative to the first vehicle body,
The attitude control device,
a steering operation state detection device that detects an operation state of a steering operation member that can be operated by the driver;
a rotational speed difference control unit that controls a rotational speed difference between the left wheel and the right wheel by controlling driving forces applied to the left wheel and the right wheel, respectively;
The attitude control device comprises: a rotational speed difference control unit that, when the operation of the steering operation member is detected by the steering operation state detection device, performs reverse turning rotational speed difference control, which is control for making the rotational speed of the wheel on the inside of a turn, determined by the direction of operation of the steering operation member detected by the steering operation state detection device, greater than the rotational speed of the wheel on the outside of a turn, among the left wheel and the right wheel, thereby tilting the second vehicle body around the longitudinal axis relative to the first vehicle body to the inside of a turn, determined by the direction of operation of the steering operation member.

"When operation of the steering operation member is detected" means when a turning operation is performed, such as when the steering operation member is operated from a straight-ahead state, or when a turning direction change operation is performed (this refers to a change operation from turning to the right or left to turning to the left or right, but does not include a change operation from turning to the right or left to straight-ahead driving). Specifically, this can be defined as "when the absolute value of the operation amount from the neutral position of the steering operation member becomes equal to or exceeds a set value."

(2) The vehicle includes a lean lock device that is switchable between a state that allows tilt of the second vehicle body relative to the first vehicle body about the longitudinal axis and a state that restricts tilt,
the attitude control device includes a lean lock control unit that controls the lean lock device to allow tilt of the second vehicle body about the longitudinal axis relative to the first vehicle body when the traveling speed of the vehicle is higher than a set speed, and limits tilt of the second vehicle body about the longitudinal axis relative to the first vehicle body when the traveling speed of the vehicle is equal to or lower than the set speed,
The attitude control device described in (1) is configured to execute the reverse turning rotational speed difference control when the traveling speed of the vehicle is higher than the set speed and the absolute value of the operation amount of the steering operation member detected by the steering operation state detection device is equal to or greater than a set value.

(3) The attitude control device includes a lean angle detection device that detects a lean angle, which is an inclination angle of the second vehicle body relative to the first vehicle body about the longitudinal axis,
The attitude control device according to claim 1 or 2, wherein the rotational speed difference control unit terminates the reverse turning rotational speed difference control when the lean angle detected by the lean angle detection device becomes larger than a set lean angle.

The set lean angle can be set to a value that corresponds to the absolute value of the amount of operation of the steering operation member, or can be set to a constant value, etc.

(4) An attitude control device described in any one of items (1) to (3), in which the rotational speed difference control unit makes the rotational speed of the wheel on the inside of the turning wheel among the left wheel and the right wheel greater than the rotational speed of the wheel on the outside of the turning wheel by at least a set rotational speed difference.

The steered front wheels are steered based on the operation of the steering operation member. In this state, the difference in rotational speed between the left and right rear wheels causes the vehicle to turn in the opposite direction to the steering direction of the steered wheels. For this reason, it is desirable to increase the difference in rotational speed between the left and right rear wheels when the steering angle of the steered wheels is large. In this case, the difference in rotational speed can be gradually increased. This is because it is not desirable to suddenly increase the difference in rotational speed in order to turn the vehicle in the opposite direction to the steering direction of the front wheels. There are also cases where the driver leans his or her body in an attempt to tilt the second vehicle body.

(5) An attitude control device according to any one of items (1) to (4), in which the second vehicle body is held tiltable about the longitudinal axis relative to the first vehicle body, and the vertical distance of the center of gravity of the second vehicle body from the longitudinal axis is large relative to the width of the second vehicle body.

The vertical distance from the axis of the center of gravity can be 1/3 or more, 1/2 or more, 2/3 or more, 3/4 or more, etc., of the width of the second body.

(6) a first body that rotatably holds a left wheel and a right wheel;
A second vehicle body having a driver's seat and tiltable about a front-rear axis that is an axis extending in a front-rear direction with respect to the first vehicle body;
A steering operation member operable by a driver;
a steering operation state detection device that detects an operation state of the steering operation member;
a left side drive unit and a right side drive unit provided on the left side wheels and the right side wheels, respectively, for applying driving force thereto;
a rotational speed difference control unit capable of controlling a rotational speed difference between the left wheel and the right wheel by controlling the left side drive device and the right side drive device,
The rotational speed difference control unit, at the beginning of a turn of the vehicle, makes the rotational speed of the inner wheel of the turn, determined by the operating direction of the steering operation member, among the left wheel and the right wheel, greater than the rotational speed of the outer wheel of the turn, thereby tilting the second vehicle body relative to the first vehicle body to the inner side of the turn determined by the operating direction of the steering operation member.

The vehicle described in this section may adopt any of the technical features described in paragraphs (1) through (5).

(7) The vehicle described in (6) in which the second vehicle body is equipped with a steering wheel that can be turned in response to the operation of the steering operation member.

Claims (2)

A posture control device for controlling a posture of a vehicle including a first vehicle body that rotatably holds left and right wheels, which are drive wheels, and a second vehicle body that has a driver's seat in which a driver sits, and is provided so as to be tiltable about a front-rear axis that is an axis that extends in a front-rear direction relative to the first vehicle body,
the vehicle includes a lean lock device switchable between a state allowing and a state restricting tilt of the second vehicle body about the longitudinal axis relative to the first vehicle body,
The attitude control device,
a steering operation state detection device that detects an operation state of a steering operation member that can be operated by the driver;
a rotational speed difference control unit that controls a rotational speed difference between the left wheel and the right wheel by controlling driving forces applied to the left wheel and the right wheel , respectively;
a lean lock control unit that controls the lean lock device to allow tilt of the second vehicle body about the longitudinal axis relative to the first vehicle body when the traveling speed of the vehicle is higher than a set speed, and to restrict tilt of the second vehicle body about the longitudinal axis relative to the first vehicle body when the traveling speed of the vehicle is equal to or lower than the set speed;
Including,
The attitude control device is configured to perform reverse turning rotational speed difference control, which is control for making the rotational speed of the wheel on the inside of a turn, determined by the direction of operation of the steering operation member detected by the steering operation state detection device, greater than the rotational speed of the wheel on the outside of a turn, among the left and right wheels, when the traveling speed of the vehicle is greater than the set speed and the absolute value of the operation amount of the steering operation member detected by the steering operation state detection device is greater than a set value, thereby tilting the second vehicle body around the longitudinal axis relative to the first vehicle body to the inside of the turn, determined by the direction of operation of the steering operation member. A posture control device for controlling a posture of a vehicle including a first vehicle body that rotatably holds left and right wheels, which are drive wheels, and a second vehicle body that has a driver's seat in which a driver sits, and is provided so as to be tiltable about a front-rear axis that is an axis that extends in a front-rear direction relative to the first vehicle body,
The attitude control device,
a steering operation state detection device that detects an operation state of a steering operation member that can be operated by the driver;
a rotational speed difference control unit that controls a rotational speed difference between the left wheel and the right wheel by controlling driving forces applied to the left wheel and the right wheel , respectively;
a lean angle detection device that detects a lean angle, which is an inclination angle of the second vehicle body relative to the first vehicle body about the longitudinal axis;
Including,
An attitude control device in which, when the operation of the steering operation member is detected by the steering operation state detection device, the rotational speed difference control unit performs reverse turning rotational speed difference control, which is control for making the rotational speed of the wheel on the inside of the turn, determined by the direction of operation of the steering operation member detected by the steering operation state detection device, greater than the rotational speed of the wheel on the outside of the turn, among the left and right wheels, thereby tilting the second vehicle body around the longitudinal axis relative to the first vehicle body to the inside of the turn, determined by the direction of operation of the steering operation member , and terminates the reverse turning rotational speed difference control when the lean angle detected by the lean angle detection device becomes larger than a set lean angle .

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