JP2014051108A - Turning travel control device, and turning travel control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise stability in turning travel in a vehicle with a narrow tread width in comparison with a vehicle height.SOLUTION: A wheel load of a turning inner wheel is detected, and when the wheel load is smaller than a first preset wheel load threshold in at least one of a front wheel and a rear wheel, approach of a turning travel state of a self-vehicle to a limit of turning performance is transmitted to a driver. In addition, when the wheel load is smaller than a second wheel load threshold preset within a range smaller than that of the first wheel load threshold in at least one of the front wheel and the rear wheel, a warning for separating the turning travel state of the self-vehicle from the limit of the turning performance is transmitted to the driver. Furthermore, when the wheel load is smaller than the second wheel load threshold in both of the front wheel and the rear wheel, or when the wheel load is smaller than a third wheel load threshold preset within a range smaller than that of the second wheel load threshold in at least one of the front wheel and the rear wheel, the turning travel state of the self-vehicle is controlled so as to be separated from the limit of the turning performance.

Description

  The present invention relates to a turning traveling control device and a turning traveling control method.

  In the prior art described in Patent Document 1, when the wheel load of either one of the left and right wheels becomes 0 or substantially 0, the front wheel generates a maximum braking force to reduce the cornering force of the front wheel, It is intended to prevent rollover when turning in a vehicle with a high center of gravity.

Japanese Patent Laid-Open No. 10-329682

However, there is a possibility that the control intervention timing will be too late after the wheel load on the inner side of the turn has already become zero or substantially zero. In addition, the configuration in which the braking force is uniformly generated only on the front wheels is sufficient. There is a possibility that the deceleration action cannot be obtained.
The subject of this invention is improving the stability at the time of turning driving | running | working in the vehicle with a narrow tread width compared with vehicle height.

  A turning control apparatus according to an aspect of the present invention is a vehicle in which a value obtained by dividing 1/2 of the tread width of the vehicle by the height of the center of gravity is less than 1, detects a wheel load of a turning inner wheel, and detects a front wheel and a rear wheel. On the other hand, when the wheel load is smaller than a preset first wheel load threshold value, the driver is notified that the turning state of the vehicle is approaching the limit of turning performance. Further, when at least one of the front wheel and the rear wheel has a wheel load smaller than a second wheel load threshold set in advance within a range smaller than the first wheel load threshold, the turning performance of the host vehicle is turned. A warning is sent to the driver to move away from the limit. Further, in both the front wheel and the rear wheel, when the wheel load is smaller than the second wheel load threshold value, or at least one of the front wheel and the rear wheel, the wheel load is previously set within a range smaller than the second wheel load threshold value. When it is smaller than the set third wheel load threshold, the turning traveling state of the host vehicle is controlled so as to be separated from the limit of turning performance.

  According to the present invention, in response to the decrease in wheel load, as a first step, the fact that the turning state of the host vehicle is approaching the limit of turning performance is transmitted, and as the second step, the turning state of the host vehicle is determined. An alarm is transmitted to move away from the limit of the turning performance, and the turning traveling state of the host vehicle is controlled to move away from the limit of the turning performance as a third stage. In this way, by performing different control interventions in stages, it is possible to improve the stability during turning in a vehicle having a narrow tread width compared to the vehicle height.

It is a figure which shows an example of a vehicle with a narrow vehicle width compared with vehicle height. It is a figure which shows the relationship between half of a tread width and the height of a center of gravity It is a figure which shows schematic structure of a turning travel control apparatus. It is a system block diagram of an electronically controlled throttle. It is a system block diagram of a steering by wire. It is a schematic block diagram of a brake actuator. It is a flowchart which shows a turning traveling control process. SSF and is a graph showing the relationship between the first coefficient k _1. Is a graph describes the settings of the second coefficient k _2. It is a graph which shows the relationship between lateral acceleration and a wheel load in case the wheel load of a front-and-rear wheel differs in a stationary state. It is a figure explaining the setting of the 3rd threshold value. It is a graph which shows the relationship between a wheel load and a cornering force.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<< First Embodiment >>
"Constitution"
The present embodiment is suitable for a vehicle having a narrower vehicle width than the vehicle height.
FIG. 1 is a diagram illustrating an example of a vehicle having a narrower vehicle width than the vehicle height.
As a vehicle having a vehicle width narrower than the vehicle height, for example, there is a tandem type 2-theta vehicle proposed as a city commuter.
FIG. 2 is a diagram showing the relationship between half the tread width and the height of the center of gravity.
The static stability factor (SSF) is a ratio (= T / 2H) between half of the tread width T and the center of gravity height H, and represents a static stability limit. As the vehicle width is narrower than the vehicle height, the rollover limit is lower because the SSF is smaller.

FIG. 3 is a diagram illustrating a schematic configuration of the turning control device.
The turning control device of the present embodiment includes a vehicle speed sensor 11, a steering angle sensor 12, a lateral acceleration sensor 13, a yaw rate sensor 14, a roll angle sensor 15, a wheel load sensor 16, and a controller 17. .
The vehicle speed sensor 11 detects a vehicle body speed (hereinafter referred to as a vehicle speed) V. This vehicle speed sensor 11 is provided, for example, in a driven gear on the output side of the transmission, detects the magnetic lines of force of the sensor rotor by a detection circuit, converts the change in the magnetic field accompanying the rotation of the sensor rotor into a pulse signal, and outputs it to the controller 17. To do. The controller 17 determines the vehicle speed V from the input pulse signal.

  The steering angle sensor 12 detects the steering angle θs of the steering shaft. The steering angle sensor 12 detects the rotation of a magnet built in a detection gear that rotates in synchronization with the steering shaft, for example, by two MR (ferro-magnetoresistance) elements, and detects the direction of the magnetic field accompanying the rotation of the steering shaft. The vector change is converted into an electric signal and output to the controller 17. The controller 17 determines the steering angle θs of the steering shaft from the input electric signal. The steering angle sensor 12 detects a right turn as a positive value and a left turn as a negative value.

  The lateral acceleration sensor 13 detects the lateral acceleration a of the vehicle. The lateral acceleration sensor 13 detects, for example, the displacement of the movable electrode with respect to the fixed electrode as a change in capacitance, and converts it into a voltage signal proportional to the lateral acceleration and outputs it to the controller 17. The controller 17 determines the lateral acceleration a from the input voltage signal. The lateral acceleration sensor 13 detects right turn as a positive value and detects left turn as a negative value.

  The yaw rate sensor 14 detects the yaw rate γ of the vehicle body. The yaw rate sensor 14 is provided on a body on a spring, and vibrates a vibrator made of, for example, a crystal tuning fork with an alternating voltage, and converts the distortion amount of the vibrator caused by Coriolis force at the time of angular velocity input into an electric signal. Output to the controller 17. The controller 17 determines the yaw rate γ of the vehicle from the input electric signal. The yaw rate sensor 14 detects a right turn as a positive value and a left turn as a negative value.

  The roll angle sensor 15 detects the roll angle φ of the vehicle body. This roll angle sensor 15 is provided on a vehicle body that is on a spring, and vibrates a vibrator made of, for example, a crystal tuning fork with an alternating voltage, and converts the amount of distortion of the vibrator caused by Coriolis force at the time of angular velocity input into an electric signal. To the controller 17. The controller 17 determines the yaw rate γ of the vehicle from the input electric signal. The yaw rate sensor 15 detects right turn as a positive value and detects left turn as a negative value.

The wheel load sensor 16 detects the wheel load W of each wheel. The wheel load sensor 16 is, for example, a strain gauge provided in the upper mount portion of the suspension. The wheel load sensor 16 detects the strain of the resistor as a change in electrical resistance, converts it into a voltage signal proportional to the vertical load, and outputs it to the controller 17. . The controller 17 determines the wheel load W of each wheel from the input voltage signal.
Note that when distinguishing between front and rear wheels, description will be made by attaching “F” to the reference numerals for the front wheels and “R” for the reference signs for the rear wheels. Also, when distinguishing front, rear, left and right wheels, “FL” is added to the code related to the front left wheel, “FR” is added to the code related to the front right wheel, and “RL” is added to the code related to the rear left wheel. In the following description, “RR” is added to the reference numerals related to the rear right wheel.

The controller 17 is composed of, for example, a microcomputer, and executes a turning traveling control process, which will be described later, based on detection signals from the respective sensors. The display 18, the speaker 19, the driving force control device 20, the steering control device 30, The brake control device 50 is drive-controlled.
The display 18 displays road guidance information. The display 18 is provided in the vicinity of the dashboard so that the driver can visually recognize and operate the display 18 and includes, for example, a touch panel including a liquid crystal display and an operation input unit. That is, arbitrary display is performed by partially blocking or transmitting the light emitted from the backlight through the driving circuit. Further, a user's touch operation on the screen is detected by a resistive film type or capacitive type touch sensor, and various settings are performed based on the touch position.

The speaker 19 outputs voice guidance as road guidance information. The speaker 19 is provided in the vehicle compartment and is composed of, for example, a dynamic speaker. That is, an electric signal is input to the coil directly connected to the diaphragm, and the diaphragm is vibrated by the vibration of the coil due to electromagnetic induction, thereby emitting sound corresponding to the electric signal.
The driving force control device 20 controls the driving force of the rotational driving source. For example, if the rotational drive source is an engine, the engine output (the number of revolutions and the engine torque) is controlled by adjusting the opening of the throttle valve, the fuel injection amount, the ignition timing, and the like. If the rotational drive source is a motor, the motor output (number of revolutions and motor torque) is controlled via an inverter.

As an example of the driving force control device 20, a configuration of an electronically controlled throttle that controls the opening of the throttle valve will be described.
FIG. 4 is a system configuration diagram of an electronically controlled throttle.
A throttle shaft 22 extending in the radial direction is supported in the intake pipe 21 (for example, an intake manifold), and a disk-like throttle valve 23 having a diameter smaller than the inner diameter of the intake pipe 21 is supported on the throttle shaft 22. Is fixed. A throttle motor 25 is connected to the throttle shaft 22 via a speed reducer 24.

  Therefore, when the throttle motor 25 is rotated to change the rotation angle of the throttle shaft 22, the throttle valve 23 closes or opens the intake pipe 21. That is, when the surface direction of the throttle valve 23 is along the direction perpendicular to the axis of the intake pipe 21, the throttle opening is in the fully closed position, and when the surface direction of the throttle valve 23 is along the axis direction of the intake pipe 21, The throttle opening is the fully open position. When an abnormality occurs in the throttle motor 25, the motor drive system, the accelerator sensor 26 system, the throttle sensor 29 system, etc., the throttle shaft 22 is opened in the opening direction so that the throttle valve 23 is opened by a predetermined amount from the fully closed position. It is mechanically energized.

  The accelerator sensor 26 has two systems, and detects a pedal opening degree PPO that is a depression amount (operation amount) of the accelerator pedal 27. The accelerator sensor 26 is a potentiometer, for example, and converts the pedal opening of the accelerator pedal 27 into a voltage signal and outputs the voltage signal to the engine controller 28. The engine controller 28 determines the pedal opening PPO of the accelerator pedal 27 from the input voltage signal.

  The throttle sensor 29 has two systems and detects the throttle opening SPO of the throttle valve 23. The throttle sensor 29 is a potentiometer, for example, and converts the throttle opening of the throttle valve 23 into a voltage signal and outputs the voltage signal to the engine controller 28. The engine controller 28 determines the throttle opening SPO of the throttle valve 23 from the input voltage signal.

The engine controller 28 normally sets a target throttle opening SPO ^* according to the pedal opening PPO, and sets the motor control amount according to the deviation ΔPO between the target throttle opening SPO ^* and the actual throttle opening SPO. Set. Then, this motor control amount is converted into a duty ratio, and the throttle motor 25 is driven and controlled by a pulsed current value. Further, when the engine controller 28 receives a drive command from the controller 17, the engine controller 28 drives the throttle motor 25 with priority given to the drive command. For example, when a driving command for reducing the driving force is received, the throttle motor 25 is driven and controlled by reducing the target throttle opening SPO ^* corresponding to the pedal opening PPO.
The above is the description of the driving force control device 20.

Next, the steering control device 30 will be described.
The steering control device 30 controls at least the turning angle of the steered wheels. For example, the turning angle is controlled by steering-by-wire, or the turning angle is controlled by a variable steering angle ratio mechanism (VGR: Variable Gear Ratio). Further, the assisting torque may be applied in the correction direction of the turning angle by electric power steering, and the steering angle may be controlled by urging the correction steering.

As an example of the steering control device 30, a configuration of a steering-by-wire will be described.
FIG. 5 is a system configuration diagram of a steering-by-wire system.
The steering wheel 31 is connected to a steering shaft 32, and steered wheels (steering wheels) 33L and 33R are connected to a pinion shaft 37 through a knuckle arm 34, a tie rod 35, and a rack and pinion 36 in this order. The steering shaft 32 and the pinion shaft 37 are connected via a clutch 38 so as to be able to be intermittently connected.

  Therefore, in a state where the clutch 38 is connected (fastened), when the steering wheel 31 is rotated, the steering shaft 32, the clutch 38, and the pinion shaft 37 are rotated. The rotational movement of the pinion shaft 37 is a forward and backward movement of the tie rod 35 by the rack and pinion 36, and the steered wheels 33 </ b> L and 33 </ b> R are steered via the knuckle arm 34.

  A steered motor 39 is connected to the pinion shaft 37. When the steered motor 39 is driven with the clutch 38 disconnected, the pinion shaft 37 rotates to steer the steered wheels 33L and 33R. The Therefore, the steering angle θw of the steered wheels 33L and 33R is controlled by detecting the steering angle θs of the steering wheel 31 and controlling the driving of the steered motor 39 in accordance with the detected steering angle θs.

A reaction force motor 41 is connected to the steering shaft 32. When the reaction force motor 41 is driven in a state where the clutch 38 is disengaged, a reaction force torque is applied to the steering shaft 32. Therefore, the reaction force received from the road surface when the steered wheels 33L and 33R are steered is detected or estimated, and the reaction force motor 41 is driven and controlled in accordance with the detected or estimated reaction force, so that the driver can perform the steering operation. In contrast, an operation reaction force is applied.
The steered motor 39 and the reaction force motor 41 are driven and controlled by a steering controller 42 constituted by, for example, a microcomputer. The steering controller 42 inputs various signals detected by the vehicle speed sensor 11, the steering angle sensor 12, the yaw rate sensor 14, the turning angle sensor 43, and the hub sensor 44.

  The turning angle sensor 43 detects the turning angle θw of the pinion shaft 37. The turning angle sensor 43 detects, for example, rotation of a magnet built in a detection gear that rotates in synchronization with the pinion shaft 37 with two MR (ferro-magneto resistance) elements, and accompanies the rotation of the pinion shaft 37. The vector change in the magnetic field direction is converted into an electric signal and input to the steering controller 42. The steering controller 42 determines the turning angle θw of the pinion shaft 37 from the input electric signal. The turning angle sensor 43 detects a right turn as a positive value and a left turn as a negative value.

  The hub sensor 44 detects the tire lateral force Yf. The hub sensor 44 is provided in each hub unit of the left and right wheels, and converts, for example, a change in displacement difference between the inner ring and the outer ring in a bearing in the hub unit into an electric signal using a hall element and a magnetized encoder. Input to the steering controller 42. The steering controller 42 determines the tire lateral force from the input electric signal. The tire lateral force Yf is the total value of the tire lateral forces of the left and right wheels detected by the hub sensor 44.

The steering controller 42 normally controls the steering motor 39 and the reaction force motor 41 while driving the steering motor 39 with the clutch 38 disconnected, thereby executing steer-by-wire, and desired steering characteristics and turning behavior. Realizes the characteristics and realizes good operation feeling. On the other hand, when an abnormality occurs in the system, the steer-by-wire is stopped and the clutch 38 is returned to the engaged state as fail-safe to ensure mechanical backup. In addition, when the steering controller 42 receives a drive command from the controller 17, the steering controller 42 controls the steering motor 39 and the reaction force motor 41 by giving priority to the drive command. For example, when steering by wire is executed, when a drive command for reducing (turning back) the turning angle θw is received, the target turning angle corresponding to the driver's steering angle θs is corrected to be reduced. The rudder motor 39 is driven and controlled. At this time, the reaction force motor 41 is driven and controlled so that the steering reaction force increases.
The above is the description of the steering control device 30.

Next, the brake control device 50 will be described.
The brake control device 50 controls the braking force of each wheel. For example, the hydraulic pressure of a wheel cylinder provided in each wheel is controlled by a brake actuator used for anti-skid control (ABS), traction control (TCS), stability control (VDC: Vehicle Dynamics Control), and the like.
A configuration of a brake actuator will be described as an example of the brake control device 50.
FIG. 6 is a schematic configuration diagram of the brake actuator.
The brake actuator 51 is interposed between the master cylinder 52 and the wheel cylinders 53FL to 53RR.
The master cylinder 52 is a tandem type that creates two hydraulic pressures according to the driver's pedaling force. The master cylinder 52 transmits the primary side to the front left and rear right wheel cylinders 53FL and 53RR, and the secondary side transmits the right front wheel and A diagonal split system is used for transmission to the wheel cylinders 53FR and 53RL for the left rear wheel.

Each wheel cylinder 53FL to 53RR is built in a disc brake that generates a braking force by clamping a disc rotor with a brake pad, or a drum brake that generates a braking force by pressing a brake shoe against the inner peripheral surface of the brake drum. is there.
The primary side includes a first gate valve 61A, an inlet valve 62FL (62RR), an accumulator 63, an outlet valve 64FL (64RR), a second gate valve 65A, a pump 66, and a damper chamber 67.

  The first gate valve 61A is a normally open valve that can close the flow path between the master cylinder 52 and the wheel cylinder 53FL (53RR). The inlet valve 62FL (62RR) is a normally open valve that can close the flow path between the first gate valve 61A and the wheel cylinder 53FL (53RR). The accumulator 63 is communicated between the wheel cylinder 53FL (53RR) and the inlet valve 62FL (62RR). The outlet valve 64FL (64RR) is a normally closed valve that can open a flow path between the wheel cylinder 53FL (53RR) and the accumulator 63. The second gate valve 65A is a normally closed valve that can open a flow path that connects the master cylinder 52 and the first gate valve 61A and the accumulator 63 and the outlet valve 64FL (64RR). The pump 66 communicates the suction side between the accumulator 63 and the outlet valve 64FL (64RR), and communicates the discharge side between the first gate valve 61A and the inlet valve 62FL (62RR). The damper chamber 67 is provided on the discharge side of the pump 66, suppresses pulsation of the discharged brake fluid, and weakens pedal vibration.

Similarly to the primary side, the secondary side also has a first gate valve 61B, an inlet valve 62FR (62RL), an accumulator 63, an outlet valve 64FR (64RL), a second gate valve 65B, a pump 66, A damper chamber 67.
The first gate valves 61A and 61B, the inlet valves 62FL to 62RR, the outlet valves 64FL to 64RR, and the second gate valves 65A and 65B are two-port, two-position switching, single solenoid, and spring offset type electromagnetic operations, respectively. It is a valve. The first gate valves 61A and 61B and the inlet valves 62FL to 62RR open the flow path at the non-excited normal position, and the outlet valves 64FL to 64RR and the second gate valves 65A and 65B are at the non-excited normal position. The flow path is closed.

The accumulator 63 is a spring-type accumulator in which a compression spring faces the piston of the cylinder.
The pump 66 is a positive displacement pump such as a gear pump or a piston pump that can ensure a substantially constant discharge amount regardless of the load pressure.
With the above configuration, the primary side will be described as an example. When the first gate valve 61A, the inlet valve 62FL (62RR), the outlet valve 64FL (64RR), and the second gate valve 65A are all in the non-excited normal position. Then, the hydraulic pressure from the master cylinder 52 is transmitted as it is to the wheel cylinder 53FL (53RR) and becomes a normal brake.

  Further, even when the brake pedal is not operated, the first gate valve 61A is excited and closed while the inlet valve 62FL (62RR) and the outlet valve 64FL (64RR) are in the non-excited normal position. The second gate valve 65A is excited and opened, and the pump 66 is further driven to suck the hydraulic pressure in the master cylinder 52 through the second gate valve 65A and discharge the hydraulic pressure to the inlet valve 62FL (62RR). ) To the wheel cylinder 53FL (53RR) to increase the pressure.

  Further, when the inlet valve 62FL (62RR) is excited and closed when the first gate valve 61A, the outlet valve 64FL (64RR), and the second gate valve 65A are in the non-excited normal position, the wheel cylinder 53FL (53RR) is closed. ) To the master cylinder 52 and the accumulator 63 are blocked, and the hydraulic pressure of the wheel cylinder 53FL (53RR) is maintained.

  Further, when the first gate valve 61A and the second gate valve 65A are in the non-excited normal position, the inlet valve 62FL (62RR) is excited and closed, and the outlet valve 64FL (64RR) is excited and opened. The hydraulic pressure of the wheel cylinder 53FL (53RR) flows into the accumulator 63 and is reduced. The hydraulic pressure flowing into the accumulator 63 is sucked by the pump 66 and returned to the master cylinder 52.

Also on the secondary side, the normal braking, pressure increasing, holding, and pressure reducing operations are the same as the operations on the primary side, and detailed description thereof will be omitted.
The brake controller 54 controls each wheel cylinder by drivingly controlling the first gate valves 61A and 12B, the inlet valves 62FL to 62RR, the outlet valves 64FL to 64RR, the second gate valves 65A and 65B, and the pump 66. Increase, hold, or reduce the fluid pressure of 53FL to 53RR.
In the present embodiment, a diagonal split method is used in which the brake system is divided into front left / rear right and front right / rear left, but the present invention is not limited thereto. The front / rear split method may be adopted.

  Further, in the present embodiment, the spring-shaped accumulator 63 is adopted, but the present invention is not limited to this, and the brake fluid extracted from each of the wheel cylinders 53FL to 53RR is temporarily stored to efficiently reduce the pressure. Therefore, any type such as a weight type, a gas compression direct pressure type, a piston type, a metal bellows type, a diaphragm type, a bladder type, and an in-line type may be used.

  In the present embodiment, the first gate valves 61A and 61B and the inlet valves 62FL to 62RR open the flow path at the non-excited normal position, and the outlet valves 64FL to 64RR and the second gate valves 65A and 65B are non-excited. Although the flow path is closed at the normal excitation position, the present invention is not limited to this. In short, since it is only necessary to open and close each valve, the first gate valves 61A and 61B and the inlet valves 62FL to 62RR open the flow path at the excited offset position, and the outlet valves 64FL to 64RR and the second gate are opened. The valves 65A and 65B may close the flow path at the excited offset position.

The brake controller 54 normally controls the hydraulic pressures of the wheel cylinders 52FL to 52RR by driving and controlling the brake actuator 51 in accordance with anti-skid control, traction control, and stability control. When the brake controller 54 receives a drive command from the controller 17, the brake controller 54 drives and controls the brake actuator 51 with priority given to the drive command. For example, when a drive command for increasing the pressure of a predetermined wheel cylinder among the four wheels is received, the brake actuator 51 is driven and controlled by increasing the normal target hydraulic pressure.
The above is the description of the brake control device 60.

Next, a turning traveling control process executed by the controller 17 every predetermined time (for example, 10 msec) will be described.
FIG. 7 is a flowchart showing the turning control process.
First, in step S101, various data are read.
In the subsequent step S102, it is determined whether or not the absolute value of the yaw rate γ is greater than a preset threshold value γt. Here, when the absolute value of the yaw rate γ is larger than the threshold value γt, it is determined that the vehicle is turning, and the process proceeds to step S103. On the other hand, when the absolute value of the yaw rate γ is equal to or less than the threshold value γt, it is determined that the vehicle is not turning and the process returns to the predetermined main program as it is.
In step S103, it is determined whether at least one of the following formulas (1) and (2) is satisfied.

W _{F_t1:} inner wheel loads of the front wheels at the time t1 W _{F_t2:} inner wheel loads of the front wheels at the time t2 W _{F_in:} amount of change in the front wheel turning inner load during a turn starts W _{R_t1:} inner wheel load W of the rear wheel at the time t1 _{R_t2:} turning inner load of the rear wheel at the time t2 W _{R_in:} variation of the turning inner wheel load of the rear wheels during a turn starts a _t1: time lateral acceleration a _t2 of t1: lateral acceleration time t2 a _ts: during a turn starts Amount of change in lateral acceleration kc: preset coefficient

The time point t1 is the current time point, and the time point t2 is, for example, a time point one sampling period before. That is, in the front wheels, the ratio of the lateral acceleration relative to the inner turning wheel load, the amount was changed from time t2 to time point _{t1 {(W F_t2 / a t2} ) - (W F_t1 / a t1)} sought, the amount of change in advance the set threshold value _(kcW F_in _{/ a ts)} determines larger or not. Further, the amount {(W _R — _{t 2} / at 2) − (W _R — _t1 / a _t1 )} in which the ratio of the lateral acceleration to the inner wheel load at the rear wheel changes from the time t2 to the time t1 is obtained. preset threshold determines _(kcW R_in _{/ a ts)} is greater than.
Here, when neither of the above formulas (1) and (2) is satisfied, it is determined that there is no decreasing tendency of the turning inner ring load or that the decreasing tendency of the turning inner ring load is moderate, and the process proceeds to step S104. . On the other hand, when satisfying at least one of the above expressions (1) and (2), it is determined that the turning inner ring load is in a decreasing tendency, and the process proceeds to step S105.

In step S104, it is determined whether or not at least one of the following expressions (3) and (4) is satisfied.
W _F <k ₁ W _f (3)
W _R <k ₁ W _r (4)
W _F: front turning inner wheel load W _f: wheel load of the front wheels in the stationary state W _R: rear wheel turning inner load W _r: wheel load k of the rear wheel in a static state _1: first coefficient set in advance

  Here, when neither of the above formulas (3) and (4) is satisfied, it is determined that the ground contact property of the turning inner wheel is not lowered, and the turning traveling state of the own vehicle is not approaching the limit of the turning performance. Then, it returns to the predetermined main program as it is. On the other hand, when satisfying at least one of the above formulas (3) and (4), it is determined that the ground contact property of the turning inner wheel is low, and the turning traveling state of the host vehicle is approaching the limit of the turning performance. The process proceeds to step S105.

Here, the first coefficient k ₁ will be described.
Figure 8 is a graph showing the relationship between SSF and the first coefficient k _1.
An SSF, that is, a vehicle having a ratio of half the tread width to the center of gravity height H (= T / 2H) greater than 1, is a conventional vehicle. On the other hand, an SSF of less than 1 is a vehicle having a narrow vehicle width as assumed in this embodiment. That is, the smaller the SSF is, the easier it is to lose the wheel load of the turning inner wheel. For example, in a vehicle with an SSF of less than 0.5, the vehicle may roll over under a static balance condition in the roll direction of less than about 0.5G. In a vehicle with an SSF of less than 0.5 and less than 1, the roll direction There is a possibility that the vehicle rolls over at about 0.5 G or more and less than 1 G under the static balance condition. Therefore, when the SSF is in a range smaller than 1.0 and larger than 0.5, a point where SSF = 1.0 and k ₁ = 0 and a point where SSF = 0.5 and k ₁ = 0.5 the straight line connecting the set the first coefficient k ₁ in the lower region. When the SSF is in a range smaller than 0.5 and larger than 0, the first coefficient k ₁ is set in the range of 0.5 to 1.0.

In step S105, it is determined whether or not both the following expressions (5) and (6) are satisfied.
W _F ≧ k ₂ W _f (5)
W _R ≧ k ₂ W _r (6)
k ₂ : preset second coefficient The second coefficient k ₂ is in the range of 0 to 1, and is smaller than the first coefficient k ₁ described above.

Here, a description is given of a second coefficient k _2.
Figure 9 is a graph describes the settings of the second coefficient k _2.
When cornering, the load transfer from the inside of the turn to the outside of the turn, the inner wheel load _{W F_in} and _{W R_in} according to the increase of the lateral acceleration is decreased, the turning outer wheel load _{W F_out} and _{W R_out} increases.
Of turning inner transition of front turning inner wheel load W _{F_in} is substantially linear, there is a characteristic that the slope changes at transition is part of the inner wheel load W _{R_in} of the rear wheels. The second coefficient k ₂ is set so that the point at which the slope changes becomes the second threshold value k ₂ W _r .

  Here, when both of the above formulas (5) and (6) are satisfied, it is not necessary to issue an alarm because the grounding property of the turning inner wheel is still within the allowable range, and the turning state of the host vehicle is the limit of the turning performance. It is determined that it is enough to transmit that it has approached the process, and the process proceeds to step S106. On the other hand, when either of the above formulas (5) and (6) is not satisfied, it is determined that the ground contact property of the turning inner wheel is low and at least an alarm needs to be issued, and the process proceeds to step S107.

  In step S106, the fact that the turning state of the vehicle is approaching the limit of turning performance is displayed on the display 18 or voice guidance is output from the speaker 19, and then the routine returns to the predetermined main program. Here, only the current turning state is transmitted to the driver, and no specific operation is prompted, but it may be transmitted that the current vehicle speed and steering angle can be maintained.

In step S107, an alarm for separating the turning traveling state of the host vehicle from the limit of turning performance is displayed on the display 18, or voice guidance is output by the speaker 19. Here, a specific operation such as reducing the vehicle speed or reducing the steering angle is urged.
In a succeeding step S108, it is determined whether or not at least one of the following expressions (7) and (8) is satisfied.
W _F ≧ k ₂ W _f and W _R <k ₂ W _r (7)
W _F <k ₂ W _f and W _R ≧ k ₂ W _r (8)

  Here, when neither of the above formulas (7) and (8) is satisfied, the grounding property of the turning inner wheel is deteriorated in both the front wheel and the rear wheel, and the turning traveling state of the own vehicle has the turning performance. Since there is a possibility that the limit will be reached, it is determined that control intervention is necessary for the turning operation itself, and the process proceeds to step S109. On the other hand, when at least one of the above formulas (7) and (8) is satisfied, either the front wheel or the rear wheel determines that the grounding property of the turning inner wheel is still within the allowable range, and proceeds to step S110. .

In step S109, the driving command is output to the steering control device 30 so that the turning angle θw is decreased, and then the process returns to a predetermined main program.
FIG. 10 is a graph showing the relationship between the lateral acceleration and the wheel load when the front and rear wheels have different wheel loads in a stationary state.
The ratio of change [Delta] W _F of the front wheels of the wheel load to changes .DELTA.a _F of the lateral acceleration and (ΔW _F / _{Δa F),} the ratio of change [Delta] W _R of the wheel load of the rear wheel with respect to the change .DELTA.a _R of the lateral acceleration (ΔW _R / _{Δa R} If the braking force is applied to the smaller side of the front wheel and the rear wheel in a stationary state, the turning behavior may become unstable. For this reason, control intervention is performed on the turning travel itself, but here, only steering control for reducing the turning angle θw is performed, and accelerator control and brake control for decreasing the vehicle speed V are not performed.

In step S110, it is determined whether or not both the following expressions (9) and (10) are satisfied.
W _F ≧ k ₃ W _f (9)
W _R ≧ k ₃ W _r (10)
k ₃ : preset third coefficient The third coefficient k ₃ is in the range of 0 to 1 and is smaller than the second coefficient k ₂ described above.

Here, the third threshold value corresponding to k ₃ W _f and k ₃ W _r will be described.
FIG. 11 is a diagram illustrating the setting of the third threshold value.
(A) in the figure is a graph showing the relationship between the lateral acceleration and the yaw moment, and (b) in the figure is a graph showing the relationship between the wheel load and the cornering power.
Here, as shown in (b) of the figure, the cornering force with respect to the wheel load has a non-linear characteristic, and there is an inflection point at which the cornering force turns from increasing to decreasing as the wheel load decreases. Therefore, in the state where the lateral acceleration is low, even if the stability factor is an understeer characteristic, the size of the cornering force of the front and rear wheels is reversed by the wheel load movement during turning, as shown in FIG. There is a possibility of changing from an understeer characteristic to an oversteer characteristic. Accordingly, the values k ₃ W _f and k ₃ W _r set by multiplying the stationary wheel loads W _f and W _r by the third coefficient k ₃ set in advance, and the cornering as the wheel load decreases. Of the values corresponding to the inflection points at which the force changes from increasing to decreasing, the larger value is set as the third threshold value.

  Here, when both of the above formulas (9) and (10) are satisfied, the grounding performance of the turning inner wheel is lowered, but the improvement of the turning traveling state can be expected by the alarm output. It is determined that no intervention is required, and the process returns to the predetermined main program as it is. On the other hand, when either of the above formulas (9) and (10) is not satisfied, the ground contact property of the turning inner wheel is lowered, and the possibility that the turning traveling state of the own vehicle reaches the limit of the turning performance is increased. Therefore, it is determined that control intervention is necessary for the turning travel itself, and the process proceeds to step S111.

In step S111, it is determined whether or not at least one of the following expressions (11) and (12) is satisfied.
W _F ≧ k ₃ W _f and W _R <k ₃ W _r (11)
W _F <k ₃ W _f and W _R ≧ k ₃ W _r (12)
Here, when at least one of the above formulas (7) and (8) is satisfied, it is determined that either the front wheel or the rear wheel is in a range where the ground contact property of the turning inner wheel can still generate the braking force. Then, the process proceeds to step S112. On the other hand, when neither of the above formulas (11) and (12) is satisfied, the grounding property of the turning inner wheel is deteriorated in both the front wheel and the rear wheel, and the generation of braking force contributes to the stability of turning traveling. It is determined that there is a possibility of influence, and the process proceeds to step S115.

In step S112, a drive command is output to the drive force control device 20 so that the drive force decreases.
In the subsequent step S113, a drive command is output to the brake control device 30 so that the braking force increases.
Here, the braking force of the three wheels whose wheel load is larger than the third threshold is increased. That is, when the above expression (11) is satisfied, the braking force of a total of three wheels, that is, the turning inner wheel and turning outer wheel in the front wheel and the turning outer wheel in the rear wheel, is increased. On the other hand, when the above expression (12) is satisfied, the braking force of a total of three wheels, that is, the turning inner wheel and the turning outer wheel in the rear wheel and the turning outer wheel in the front wheel, is increased.

In step S114, a drive command is output to the steering control device 30 so that the turning angle θw changes in accordance with the cornering force balance between the front wheels and the rear wheels, and then the process returns to a predetermined main program.
Here, the cornering force of the front wheel and the rear wheel is estimated according to the wheel load of the front wheel and the rear wheel, and the balance of the cornering force in the front and rear is determined.

FIG. 12 is a graph showing the relationship between wheel load and cornering force.
(A) in the figure shows the relationship between the wheel load and the cornering force at the front wheel, and (b) in the figure shows the relationship between the wheel load and the cornering force at the rear wheel.
The intermediate value between the cornering force corresponding to the wheel load of the turning inner wheel and the cornering force corresponding to the turning outer wheel is determined as the cornering force of the front wheel and the rear wheel, and the balance of the front and rear wheels is determined.

  At this time, when the front wheel cornering force is balanced with the rear wheel cornering force, the steering wheel tends to be in a neutral steering tendency. When is smaller than the cornering force of the rear wheel, it tends to be understeered.

Therefore, the turning angle θw is controlled so as to obtain a desired steering characteristic. For example, when the oversteer tendency is suppressed, a drive command is output to the steering control device 30 so that the steered angle θw decreases, and when the understeer tendency is suppressed, the steered angle θw is increased. A drive command is output to the steering control device 30.
In step S115, a drive command is output to the steering control device 30 so that the turning angle θw decreases, and then the process returns to a predetermined main program.

As described above, the ratio of change [Delta] W _F of the front wheels of the wheel load to changes .DELTA.a _F of the lateral acceleration and (ΔW F _/ Δa _F), the ratio of change [Delta] W _R of the wheel load of the rear wheel with respect to the change .DELTA.a _R of the lateral acceleration ( When ΔW _R / Δa _R ) is substantially the same, if a braking force is applied to the smaller side of the front wheel and the rear wheel in a stationary state, the turning behavior may become unstable. For this reason, control intervention is performed on the turning travel itself, but here again, only steering control for reducing the turning angle θw is performed, and accelerator control and brake control for decreasing the vehicle speed V are not performed.
The above is the turning control process based on the flowchart of FIG.

<Action>
Next, the operation of the first embodiment will be described.
In the present embodiment, when the host vehicle starts turning (the determination in step S102 is “Yes”), and the amount of change in the value obtained by dividing the wheel load by the lateral acceleration is greater than the threshold (the determination in step S103 is “ yes "), or when at least one of the wheel load W _F and W _R is smaller than the first threshold value (the determination in step S104 is" Yes "), the turning state of the vehicle to the limit of turning performance Information indicating that the user is approaching is displayed on the display 18 or voice guidance is output from the speaker 19 to present information (step S106).

By presenting such information, it is possible to prompt the driver to improve the turning state, for example, by depressing the accelerator pedal, depressing the brake pedal, or switching back the steering wheel. Then, a really improved driver operation, the amount of change value obtained by dividing the wheel load in the lateral acceleration becomes smaller than the threshold value (the determination in step S103 is "No"), and the wheel load W _F and W _R is the When it becomes larger than the threshold values k ₁ W _f and k ₁ W _r (determination in step S104 is “No”), the information presentation to the driver is terminated.

On the other hand, further decrease the ground of the inner turning wheel is, when at least one of the wheel load W _F and W _R is smaller than the second threshold value (the determination in step S105 is "No"), the turning state of the vehicle Is displayed on the display 18 or voice guidance is output from the speaker 19 to output a warning (step S107). Here, a specific improvement operation is urged such as depressing the accelerator pedal, depressing the brake pedal, or switching back the steering wheel.
Such an alarm output can prompt the driver to perform an improvement operation stronger than mere information presentation. The actual driver performs a remedial action, when the wheel load W _F and W _R is larger than the second threshold value (the determination in step S105 is "Yes"), and terminates the alarm output to the driver .

On the other hand, when both the wheel load W _F and W _R is less than the second threshold value (the determination in step S108 is "No"), controls the turning traveling state of the vehicle to be separated from the limit of turning performance.
Specifically, only steering control for reducing the turning angle θw is performed (step S109). Thereby, stability at the time of turning can be improved, suppressing that turning behavior becomes unstable.

The spacing, decreased ground contact property of the turning inner wheel Furthermore, when at least one of the wheel load W _F and W _R is smaller than the third threshold value (the determination in step S110 is "No"), the limit of turning performance The turning traveling state of the host vehicle is controlled so as to do so.
Specifically, when one of the wheel load W _F and W _R is greater than the third threshold value (the determination at Step S111 is "Yes"), the engine control to reduce the driving force (step S112), control Brake control (step S113) for increasing power and steering control (step S114) for controlling the turning angle are performed.

First, in the brake control, the braking force is generated only on the wheel whose wheel load is larger than the third threshold, that is, only the wheel that maintains the grip state that is the minimum necessary to generate the braking force. Thereby, stability at the time of turning can be improved, suppressing that turning behavior becomes unstable.
In the steering control, the cornering forces of the front wheels and the rear wheels are estimated, and the turning angle is controlled according to the balance of the cornering forces before and after. For example, when the cornering force of the front wheels is larger than the cornering force of the rear wheels and is in an oversteer tendency, the steer angle θw is decreased to suppress the oversteer tendency. Thus, by controlling the turning angle according to the balance of the cornering forces before and after, it is possible to improve the stability during turning while suppressing the turning behavior from becoming unstable.

On the other hand, when both the wheel load W _F and W _R is smaller than the third threshold value (the determination in step S111 is "No"), controls the turning traveling state of the vehicle to be separated from the limit of turning performance .
Specifically, only steering control for reducing the turning angle θw is performed (step S115). Thereby, stability at the time of turning can be improved, suppressing that turning behavior becomes unstable.

Thus, according to the decrease of the wheel load W _F and W _R, turning traveling state of the vehicle to convey that approaches the limit of turning performance as a first step, the turning of the vehicle as the second step An alarm is transmitted for separating the running state from the limit of the turning performance, and the turning state of the host vehicle is controlled so as to be separated from the limit of the turning performance as a third stage. In this way, by performing different control interventions in stages, it is possible to improve the stability during turning in a vehicle having a narrow tread width compared to the vehicle height.

<< Modification 1 >>
In the present embodiment, the wheel load is detected by the wheel load sensor 16, but the present invention is not limited to this.
For example, according to the following formula, in the front and rear wheels in accordance with the front wheel and calculates the wheel load movement amount [Delta] W _F and [Delta] W _R from turning inside to outside of the turn at the rear wheels, the calculated wheel load movement amount [Delta] W _F and [Delta] W _R it may be detected wheel load W _F and W _R of the turning inner wheel.
ΔW _F = ΔW × {Kφ _F / (Kφ _F + Kφ _R )}
ΔW _R = ΔW × {Kφ _R / (Kφ _F + Kφ _R )}
ΔW = {(W × H × g × sinφ × cosφ) + a} / T
Kφ _F : Front wheel roll rigidity Kφ _R : Rear wheel roll rigidity ΔW: Wheel load movement of the entire vehicle W: Vehicle mass H: Height of center of gravity φ: Roll angle a: Lateral acceleration T: Tread width

As described above, calculates the wheel load movement amount [Delta] W _F and [Delta] W _R, thereby by detecting the wheel load W _F and W _R of the turning inner wheel, it is possible to omit the wheel load sensor 16.
From the above, the wheel load sensor 16 corresponds to the “wheel load detection means”, and the processing in steps S103, S104, and S106 corresponds to the “first control means”. Further, the processes in steps S105 and S107 correspond to “second control means”, and the processes in steps S108 to S115 correspond to “third control means”.

"effect"
Next, the effect of the main part in 1st Embodiment is described.
(1) turning control device of this embodiment is a vehicle divided by the 1/2 height of the center of gravity of the tread width of the vehicle is less than 1, and detects the wheel load W _F and W _R of the turning inner wheel , when at least one of the wheel load W _F and W _R is less than the first threshold value, turning traveling state of the vehicle is transmitted to the driver that approaches the limit of turning performance. At least one of the wheel load W _F and W _R is, when smaller than the second threshold set in advance by the smaller range than the first threshold value, to separate the turning traveling state of the vehicle from the limit of turning performance An alarm is transmitted to the driver. Then, both the front and rear wheels, when the wheel load W _F and W _R is less than the second threshold value, or wheels at least one of the load W _F and W _R are previously a smaller range than the second threshold value When it is smaller than the set third threshold value, the turning traveling state of the host vehicle is controlled so as to be separated from the limit of the turning performance.

Thus, according to the decrease of the wheel load W _F and W _R, turning traveling state of the vehicle to convey that approaches the limit of turning performance as a first step, the turning of the vehicle as the second step An alarm is transmitted for separating the running state from the limit of the turning performance, and the turning state of the host vehicle is controlled so as to be separated from the limit of the turning performance as a third stage. In this way, by performing different control interventions in stages, it is possible to improve the stability during turning in a vehicle having a narrow tread width compared to the vehicle height.

(2) turning control apparatus of this embodiment calculates the change amount of a value obtained by dividing the wheel load in the lateral acceleration, at least one of either the amount of change is greater than the threshold value, or the wheel load W _F and W _R Is smaller than the first threshold, the driver is notified that the turning state of the vehicle is approaching the limit of turning performance.
In this way, by determining the ratio of the lateral acceleration to the wheel load in consideration, it is possible to detect a decreasing tendency of the turning inner wheel load. Accordingly, rather than determining only changes the wheel load W _F and W _R of the wheel load, may be turning traveling state of the vehicle is transmitted to the driver at an earlier stage that approaches the limit of turning performance.

(3) The turning control device of the present embodiment sets the first threshold values k ₁ W _f and k ₁ W _r by multiplying the wheel loads W _f and W _r at rest by the first coefficient k _1. To do. First coefficient k ₁ is, as the value obtained by dividing 1/2 of the tread width center of gravity height of the vehicle in the range of 0 to 1 is smaller, is set to a large value.
Thus, by setting the first threshold value with the first coefficient k ₁ that changes according to the center-of-gravity height and tread width of the vehicle with the wheel loads W _f and W _r at rest as a reference, for each vehicle It is possible to set an optimum threshold value. Therefore, the fact that the turning traveling state of the host vehicle is approaching the limit of turning performance can be transmitted to the driver at an appropriate timing.

(4) The turning control device of the present embodiment sets the second threshold values k ₂ W _f and k ₂ W _r by multiplying the wheel loads W _f and W _r at rest by the second coefficient k _2. To do. Second coefficient k ₂ is set in a range smaller than and the first coefficient k ₁ in the range of 0 to 1.
Thus, the optimal threshold value for each vehicle is set by setting the second threshold value with the second coefficient k ₂ smaller than the first coefficient k ₁ with reference to the wheel loads W _f and W _r at rest. Can be set. Therefore, an alarm for separating the turning traveling state of the host vehicle from the limit of the turning performance can be transmitted to the driver at an appropriate timing.

(5) The turning control device of the present embodiment sets the third threshold values k ₃ W _f and k ₃ W _r by multiplying the stationary wheel loads W _f and W _r by the third coefficient k _3. To do. Third coefficient k ₃ is set in and a second range smaller than the coefficient k ₂ in the range of 0 to 1.
In this way, by setting the third threshold value with the third coefficient k ₃ smaller than the second coefficient k ₂ on the basis of the stationary wheel loads W _f and W _r , the optimum threshold value for each vehicle is set. Can be set. Therefore, the control intervention for separating from the limit of the turning performance can be performed at an appropriate timing.

(6) turning the control apparatus of the present embodiment, the value set by multiplying the third coefficient k ₃ in the wheel load W _f and W _r at rest, cornering force with decreasing wheel load The larger one of the values corresponding to the inflection points at which changes from increasing to decreasing is set as the third threshold value. Third coefficient k ₃ is set in and a second range smaller than the coefficient k ₂ in the range of 0 to 1.
Thus, by setting the third threshold value with the value according to the motion limit in the roll direction and the value according to the motion limit in the yaw direction, the stability in the roll direction and the yaw direction is ensured for each vehicle. It is possible to set an optimum threshold value. Therefore, the control intervention for separating from the limit of the turning performance can be performed at an appropriate timing.

(7) turning control apparatus of this embodiment, when both the wheel load W _F and W _R is less than the second threshold value, or when less than the third threshold value, steering to reduce the turning angle Perform control only.
As described above, when both the front and rear wheel ground contact characteristics are lowered, only the steering control for reducing the turning angle θw is performed, and the accelerator control and the brake control for decreasing the vehicle speed V are not performed, so that the turning behavior is not improved. Stability at the time of turning can be improved while suppressing becoming stable.

(8) The turning control device of the present embodiment
When either one of the wheel load W _F and W _R is less than the third threshold value, to reduce the driving force and the vehicle speed control wheel load increases the braking force of greater wheel than the third threshold value, and Both steering controls for reducing the turning angle are executed.
In this way, by generating braking force only on wheels whose wheel load is greater than the third threshold, that is, on wheels that maintain a grip state that is at least necessary to generate braking force, the turning behavior is not improved. Stability at the time of turning can be improved while suppressing becoming stable.

(9) The turning control device of the present embodiment is
According to the following formula, the inner wheel in the front and rear wheels in accordance with the front wheel and calculates the wheel load movement amount [Delta] W _F and [Delta] W _R from turning inside to outside of the turn at the rear wheels, the calculated wheel load movement amount [Delta] W _F and [Delta] W _R detecting the wheel load _{W F} and _{W R} of.
ΔW _F = ΔW × {Kφ _F / (Kφ _F + Kφ _R )}
ΔW _R = ΔW × {Kφ _R / (Kφ _F + Kφ _R )}
ΔW = {(W × H × g × sinφ × cosφ) + a} / T
Kφ _F : Front wheel roll rigidity Kφ _R : Rear wheel roll rigidity ΔW: Wheel load movement amount of the entire vehicle W: Vehicle mass H: Height of center of gravity φ: Roll angle a: Lateral acceleration T: Tread width In this way, wheel load movement calculates the amount [Delta] W _F and [Delta] W _R, thereby by detecting the wheel load W _F and W _R of the turning inner wheel, it is possible to omit the wheel load sensor 16.

(10) turning control apparatus of this embodiment, the wheel load sensor 16 detects the wheel load W _F and W _R of the inner wheel in the front and rear wheels.
Thus, by detecting the wheel load W _F and W _R through the wheel load sensor 16 can be obtained easily correct the wheel load W _F and W _R.

(11) the turning control method of this embodiment is a vehicle divided by the height of the center of gravity of 1/2 of the tread width of the vehicle is less than 1, and detects the wheel load W _F and W _R of the turning inner wheel , when at least one of the wheel load W _F and W _R is less than the first threshold value, turning traveling state of the vehicle is transmitted to the driver that approaches the limit of turning performance. At least one of the wheel load W _F and W _R is, when smaller than the second threshold set in advance by the smaller range than the first threshold value, to separate the turning traveling state of the vehicle from the limit of turning performance An alarm is transmitted to the driver. Then, both the front and rear wheels, when the wheel load W _F and W _R is less than the second threshold value, or wheels at least one of the load W _F and W _R are previously a smaller range than the second threshold value When it is smaller than the set third threshold value, the turning traveling state of the host vehicle is controlled so as to be separated from the limit of the turning performance.

Thus, according to the decrease of the wheel load W _F and W _R, turning traveling state of the vehicle to convey that approaches the limit of turning performance as a first step, the turning of the vehicle as the second step An alarm is transmitted for separating the running state from the limit of the turning performance, and the turning state of the host vehicle is controlled so as to be separated from the limit of the turning performance as a third stage. In this way, by performing different control interventions in stages, it is possible to improve the stability during turning in a vehicle having a narrow tread width compared to the vehicle height.
Although the present invention has been described with reference to a limited number of embodiments, the scope of rights is not limited thereto, and modifications of the embodiments based on the above disclosure are obvious to those skilled in the art.

11 Vehicle speed sensor 12 Steering angle sensor 13 Lateral acceleration sensor 14 Yaw rate sensor 15 Roll angle sensor 16 Wheel load sensor 17 Controller 18 Display 19 Speaker 20 Driving force control device 23 Throttle valve 25 Throttle motor 26 Accelerator sensor 28 Engine controller 29 Throttle sensor 30 Steering Control device 32 Steering shaft 37 Pinion shaft 38 Clutch 39 Steering motor 42 Steering controller 43 Steering angle sensor 44 Hub sensor 50 Brake control device 51 Brake actuator 53FL to 53RR Wheel cylinder 54 Brake controller 52 Master cylinder 61A, 61B First gate valve 62FL ~ 62RR Inlet valve 63 Accumulator 64FL ~ 64RR A DOO inlet valve 65A, 65B second gate valve 66 the pump 67 damper chamber

Claims (11)

A vehicle in which 1/2 of the tread width of the vehicle divided by the height of the center of gravity is less than 1,
Wheel load detecting means for detecting the wheel load of the turning inner ring;
When the wheel load detected by the wheel load detecting means is smaller than the first wheel load threshold value set in advance on at least one of the front wheel and the rear wheel, the turning traveling state of the host vehicle approaches the limit of the turning performance. First control means for transmitting to the driver;
When at least one of the front wheel and the rear wheel, the wheel load detected by the wheel load detecting means is smaller than a second wheel load threshold set in advance in a range smaller than the first wheel load threshold, the host vehicle A second control means for transmitting an alarm for separating the turning traveling state of the vehicle from the limit of the turning performance to the driver;
The wheel detected by the wheel load detecting means in both the front wheel and the rear wheel when the wheel load detected by the wheel load detecting means is smaller than the second wheel load threshold value or at least one of the front wheel and the rear wheel. When the load is smaller than a preset third wheel load threshold in a range smaller than the second wheel load threshold, the third running state is controlled to turn away from the turning performance limit. A turning travel control device comprising a control means. The first control means includes
A change amount of a value obtained by dividing the wheel load detected by the wheel load detection unit by a lateral acceleration is calculated, and the change amount is greater than a preset change amount threshold value, or the wheel load detected by the wheel load detection unit 2. The turning travel control device according to claim 1, wherein when the vehicle is smaller than the first wheel load threshold value, the fact that the turning state of the host vehicle is approaching a limit of turning performance is transmitted to the driver. . The first wheel load threshold is:
It is set by multiplying the wheel load at rest by a preset first coefficient,
The first coefficient is
The turning control device according to claim 1 or 2, wherein the smaller the value obtained by dividing the height of the center of gravity of the vehicle by 1/2 of the tread width in the range from 0 to 1, the larger the value is set. The second wheel load threshold is
It is set by multiplying the wheel load at rest by a preset second coefficient,
The second coefficient is
The turning control device according to any one of claims 1 to 3, wherein the turning control device is set in a range of 0 to 1 and smaller than the first coefficient. The third wheel load threshold is:
Set by multiplying the wheel load at rest by a preset third factor,
The third factor is
The turning control device according to any one of claims 1 to 4, wherein the turning control device is set in a range of 0 to 1 and smaller than the second coefficient. The third wheel load threshold is:
Of the value set by multiplying the stationary wheel load by a preset third coefficient and the value corresponding to the inflection point where the cornering force turns from increasing to decreasing as the wheel load decreases Is set to the value of
The third factor is
The turning control device according to any one of claims 1 to 4, wherein the turning control device is set in a range of 0 to 1 and smaller than the second coefficient. The third control means includes
The wheel load detected by the wheel load detecting means for both the front wheel and the rear wheel when the wheel load detected by the wheel load detecting means is smaller than the second wheel load threshold value, or for both the front wheel and the rear wheel. The turning control device according to any one of claims 1 to 6, wherein only when the steering wheel is smaller than the third wheel load threshold value, steering control for reducing a turning angle is executed. The third control means includes
When either the front wheel or the rear wheel has a wheel load detected by the wheel load detecting means smaller than the third wheel load threshold, the driving force is reduced and the wheel load is reduced to the third wheel load. The turning travel control device according to any one of claims 1 to 7, wherein both vehicle speed control for increasing a braking force of a wheel larger than a threshold value and steering control for decreasing a turning angle are executed. . The wheel load detection means includes
According to the following formula, the wheel load movement amount from the turning inner side to the turning outer side of the front wheel and the rear wheel is calculated, and the wheel load of the turning inner wheel in the front wheel and the rear wheel is detected according to the calculated wheel load movement amount. The turning travel control device according to any one of claims 1 to 8.
ΔW _F = ΔW × {Kφ _F / (Kφ _F + Kφ _R )}
ΔW _R = ΔW × {Kφ _R / (Kφ _F + Kφ _R )}
ΔW = {(W × H × g × sinφ × cosφ) + a} / T
Kφ _F : Front wheel roll rigidity Kφ _R : Rear wheel roll rigidity ΔW: Wheel load movement of the entire vehicle W: Vehicle mass H: Height of center of gravity φ: Roll angle a: Lateral acceleration T: Tread width The wheel load detection means includes
The turning travel control device according to any one of claims 1 to 9, wherein the wheel load of the turning inner wheel at the front wheel and the rear wheel is detected by a sensor. A vehicle in which 1/2 of the tread width of the vehicle divided by the height of the center of gravity is less than 1,
Detects the wheel load of the turning inner ring,
Calculate the amount of change in the value obtained by dividing the wheel load by the lateral acceleration,
When at least one of the front wheel and the rear wheel, the wheel load is smaller than a preset first wheel load threshold, the vehicle is informed that the turning state of the vehicle is approaching the limit of turning performance,
When at least one of the front wheel and the rear wheel, the wheel load is smaller than a second wheel load threshold value set in advance in a range smaller than the first wheel load threshold value, the turning performance of the own vehicle is turned. To alert the driver to move away from the limit of
When both the front wheel and the rear wheel have the wheel load smaller than the second wheel load threshold or at least one of the front wheel and the rear wheel, the wheel load is smaller than the second wheel load threshold. When the vehicle is smaller than the preset third wheel load threshold value, the turning control state of the vehicle is controlled so as to be separated from the limit of the turning performance.

Images