Attitude control device

Abstract

To enhance the posture stability at the time of turning of a vehicle.SOLUTION: A posture control system is mounted on a vehicle in which an inclination of a second vehicle body relative to a first vehicle body is permitted. When a rotation speed difference between left and right rear wheels is controlled during initial turning time, the vehicle is turned in a direction opposite to an operation direction of a steering operation member. Accordingly, the vehicle can be preferably inclined inward of turning, and the posture stability of the vehicle can be enhanced.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an attitude control device mounted on a vehicle that is tiltable about an axis extending in the front-rear direction. [Background technology]

[0002] Patent Document 1 describes a posture control device mounted on a vehicle that includes three wheels and is tiltable around an axis extending in the front-rear direction. In the posture control device described in Patent Document 1, when the vehicle is accelerating, tilting around the axis extending in the front-rear direction is permitted when the vehicle speed becomes higher than a first set speed, and when the vehicle is decelerating, tilting is restricted when the vehicle speed becomes equal to or lower than a second set speed that is higher than the first set speed. This can improve the driving feel for the driver. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 59-120586 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to improve the posture stability of a vehicle when cornering.

[0005] The attitude control device according to the present invention is mounted on a vehicle that can tilt around an axis extending in the front-rear direction of a second body relative to a first body, and controls the rotational speed difference between the left and right rear wheels at the beginning of a turn to turn the vehicle in the opposite direction to the operating direction of a steering operation member. 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, thereby improving the attitude stability of the vehicle during a turn. [Brief description of the drawings]

[0006] [Figure 1] 1 is a perspective view showing a vehicle equipped with an attitude control device according to an embodiment of the present invention; [Diagram 2] FIG. [Diagram 3] 2 is a diagram conceptually showing a structure of the attitude control device. FIG. [Figure 4] 5 is a flowchart showing a lean lock control program stored in a storage unit of the posture control device. [Diagram 5] 5 is a flowchart showing a reverse turning rotation speed difference control program stored in the storage unit. [Figure 6] 4 is a plan view showing a traveling state of the vehicle when the reverse turning rotation speed difference control program is executed. FIG. [Figure 7] 5A to 5C are front views showing the attitude of the vehicle when the reverse turning rotation speed difference control program is executed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] An example of the attitude control device according to the present invention will be described in detail below with reference to the drawings. The attitude control device is mounted on a vehicle 8 shown in Figs. 1 and 2, but is not limited thereto. EXAMPLES

[0008] A vehicle 8 shown in Figures 1 and 2 has a total of three wheels: a front wheel 10, a left rear wheel 12 as a left wheel, and a right rear wheel 14 as a 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 front-rear direction. The axis of the lean shaft 26 corresponds to the front-rear axis.

[0009] The front wheel 10 is rotatably held by a pair of legs 32 of a front fork 30. The front fork 30 is also rotatably held relative to the second vehicle body 24, and a steering shaft 36 that is rotatable 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, and the front fork 30 is rotated relative to the second vehicle body 24, thereby causing the front wheel 10 to be steered.

[0010] The second vehicle body 24 is provided with a steering operation amount sensor 40 as a steering operation state detection device that detects the operation angle as the operation amount 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 where the steering angle of the front wheels 10 is approximately 0.

[0011] The second vehicle body 24 is integrally provided with 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 about the longitudinal axis relative to the first vehicle body 16. In addition, the first vehicle body 16 is provided with a lean lock device 50, which is switchable between a state in which rotation of the lean shaft 26 about the axis relative to the first vehicle body 16 is permitted and a state in which rotation is restricted.

[0012] The lean lock device 50 may include, for example, a so-called electric brake including a rotating body provided to be rotatable integrally with the lean shaft 26, a frictional engagement member, and an electric pressing device for pressing the frictional engagement member against the rotating body. The electric pressing device presses the frictional engagement member against the rotating body, thereby restricting the rotation of the lean shaft 26 about its axis, and the frictional engagement member is moved away from the rotating body, thereby allowing the rotation of the lean shaft 26 about its axis. The lean lock device 50 may also include a so-called electromagnetic clutch including a convexity forming member having an engaging convexity provided on the lean shaft 26, a concaveity forming member having an engaging concave portion provided on the first vehicle body 16, and an electric approaching / separating device for moving the concaveity forming member toward and away from the convexity forming member. The electric approach / separation device brings the recess-forming member closer to the convex-forming member, and the engaging convex portion and the engaging concave portion are brought into an engaged state, thereby restricting rotation of the lean shaft 26, and the recess-forming member is moved away from the convex-forming member, and the engaging convex portion and the engaging concave portion are brought into a disengaged state, thereby allowing rotation of the lean shaft 26.

[0013] The left and right rear wheels 12, 14 are provided with in-wheel motors 12m, 14m (see FIG. 3) as drive devices of 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 forces 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.

[0014] 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 mainly composed of a computer, a steering operation amount sensor 40, the front wheels 10, and the left and right rear wheels 12, 14, and is connected with 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 a lean angle that is a rotation angle of the lean shaft 26 with respect to the first vehicle 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 with a lean lock device 50 and in-wheel motors 12m, 14m via drive circuits 76, 77, 78, respectively.

[0015] 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.

[0016] The lean lock device 50 is controlled based on the traveling speed v of the vehicle 8. The lean lock device 50 is controlled according to 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 lock is released by control of the lean lock device 50, and the rotation of the lean shaft 26 is permitted. On the other hand, if the determination is NO, in S4, the lean is locked, and the rotation of the lean shaft 26 is restricted.

[0017] 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. Taking this into consideration, the set speed v0 is set, and can be called the speed at which lean lock is preferable, in other words, the speed at which left-right lean is acceptable.

[0018] 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.

[0019] When the vehicle 8 is turned in a direction opposite to the direction of operation of the steering wheel 20, the second body 24 is tilted outward due to centrifugal force, and the direction of this tilt corresponds to the inward direction of the operation of the steering wheel 20. When the vehicle 8 then turns toward the steering direction of the steered wheels 10, the second body 24 can be satisfactorily tilted inward. This control is called reverse turning rotational speed difference control.

[0020] In the ECU 62, a reverse turning rotation speed difference control program shown in the flowchart 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.

[0021] 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 the operation is detected based on the positive or negative of the operation angle φ, and in S15, the rotational speeds of the left and right rear wheels 12, 14 are detected. Then, in S16, the in-wheel motors 12m, 14m are controlled so that the rotational speed of the wheel on the inside of the turning, determined by the operation direction determined in S14, is made greater than the rotational speed of the wheel on the outside of the turning by a set value (set speed difference) d.

[0022] 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 or not 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 an amount at which the second body 24 is considered to be reliably inclined, or an amount determined by the operation angle φ of the steering wheel 20. The set lean angle θ0 can be set to a constant value or a variable value.

[0023] If the determination in S23 is NO, in S19, the set speed difference d, i.e., the rotation speed difference 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 rotation speed difference 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.

[0024] 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 in a state of being 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.

[0025] As shown in Fig. 6(b) and Fig. 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 tilt angle to the left, becomes larger than the set lean angle θ0, the reverse turning rotational speed difference control is terminated as shown in Fig. 6 and Fig. 7(c). This causes the vehicle 8 to turn in the direction of the steering angle of the front wheels 10, that is, 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.

[0026] As shown in Fig. 6, a normal four-wheel vehicle V turns along the trajectory shown by the dashed line A in the turning direction of the steering wheel. In contrast, the present vehicle 8 turns along the trajectory shown by the 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 favorably tilted to the inside of the turn, making it difficult for the vehicle to tip over due to centrifugal force, and improving posture stability.

[0027] In this embodiment, the reverse turning rotation speed difference control gradually increases the rotation speed difference between the left and right rear wheels 12, 14. This prevents the vehicle 8 from suddenly turning in the opposite direction to the direction of the steering wheel 20 caused by the rotation speed difference being suddenly increased, 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.

[0028] As described above, in this embodiment, the attitude control device is configured by the steering operation amount sensor 40, the wheel speed sensors 64F, 64RL, 64RR, the lean angle sensor 66, and 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, as well as a portion that stores and executes the program, etc. of the ECU 62. Of these, the rotational speed difference control portion is configured by the portion of the ECU 62 that stores and executes the reverse rotational speed difference control program shown in the flowchart of Fig. 5, and the lean lock control portion is configured by the portion of the ECU 62 that stores and executes the lean lock control program shown in the flowchart of Fig. 4.

[0029] 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. [Explanation of symbols]

[0030] 8: Vehicle 10: Front wheel 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 invention

[0031] (1) A posture control device for controlling the 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 longitudinal axis that is an axis that extends in the longitudinal 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; Including, The attitude control device, 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 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 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 the turn, determined by the direction of operation of the steering operation member.

[0032] "When the operation of the steering operation member is detected" means when a turning operation is performed, and corresponds to a case where the steering operation member is operated from a straight traveling state, a case where a turning direction change operation (a change operation from a rightward or leftward turn to a leftward or rightward turn, but does not include a change operation from a rightward or leftward turn to straight traveling) is performed, etc. Specifically, it 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."

[0033] (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 vehicle's traveling speed 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 equal to or greater than a set value.

[0034] (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.

[0035] The set lean angle can be set to a value corresponding to the absolute value of the amount of operation of the steering operation member, or can be set to a constant value.

[0036] (4) The attitude control device described in any one of (1) to (3), wherein the rotational speed difference control unit makes the rotational speed of the wheel on the inside of the turning among the left wheel and the right wheel greater than the rotational speed of the wheel on the outside of the turning by a set rotational speed difference or more.

[0037] The steered wheels, which are the 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. Therefore, 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 to tilt the second vehicle body.

[0038] (5) An attitude control device described in any one of items (1) to (4), wherein the second vehicle body is held tiltably 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.

[0039] The vertical distance from the axis of the center of gravity may be greater than or equal to 1 / 3, greater than or equal to 1 / 2, greater than or equal to 2 / 3, greater than or equal to 3 / 4, etc. of the width of the second body.

[0040] (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 the front-rear direction relative 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, respectively; A vehicle including: The rotational speed difference control unit, at the beginning of a turn of the vehicle, makes the rotational speed of the inside wheel of the turn, determined by the operating direction of the steering operation member, of the left wheel and the right wheel, greater than the rotational speed of the outside wheel of the turn, thereby tilting the second vehicle body relative to the first vehicle body to the inside of the turn determined by the operating direction of the steering operation member.

[0041] The vehicle described in this section may adopt any of the technical features described in sections (1) to (5).

[0042] (7) The vehicle according to (6), wherein the second vehicle body is provided with a steering wheel that can be turned in response to operation of the steering operation member.

Claims

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 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.

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 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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