JPH0345453A - Turning behavior controller of vehicle - Google Patents

Abstract

PURPOSE:To prevent unwanted turning behavior of a vehicle by braking individually each wheel inside and outside the turning direction so that the detected value of yaw rate in the vehicle approaches a desired value when the detected value of vehicle speed exceeds a predetermined limit value. CONSTITUTION:In a vehicle turned by steering a wheel W, the steering amount of the wheel W, vehicle speed and yaw rate of the vehicle are respectively by means A-C. Tire grip limit vehicle speed corresponding to the steering amount of the wheel is detected by a means D. A desired yaw rate corresponding to the steering amount of the wheel and tire grip limit vehicle speed is set by a means E. When the detected vehicle speed exceeds the tire grip limit vehicle speed, the respective wheels W1, W2 inside and outside the turning direction are individually braked by a means F so that the detected vehicle speed is reduced up to desired vehicle speed with the detected yaw rate approaching the desired yaw rate. Thus, the vehicle is prevented from the unwanted turning behavior.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for suppressing undesirable behavior of a vehicle during turning by automatic braking.

(Prior Art) As a turning behavior control device for this type of vehicle, that is, an automatic braking technology, there is a device that applies braking force only to the inner wheel in the turning direction during turning, and assists the generation of the vehicle's yaw rate. This method has been proposed in Japanese Patent Publication No. 63-279976.

(Problems to be Solved by the Invention) However, the lever device is intended to promote the generation of a yaw rate of the vehicle during turning, and is not effective against lateral slip of the wheels. In other words, when the vehicle enters a corner at high speed and turns the steering wheel, or when the steering wheel is turned further while turning, a centrifugal force that exceeds the grip limit of the wheels is generated in the vehicle, causing the wheels to turn. The vehicle may slip sideways and spin,
Behavior such as drifting out to the outside in the turning direction cannot be prevented.

Since such undesirable turning behavior is based on excessive vehicle speed and excessive yaw rate that cannot be suppressed by braking only the inner wheels in the turning direction, the present invention suppresses the excessive vehicle speed by automatic braking, and It is an object of the present invention to provide a device which individually brakes the inner and outer wheels in the turning direction so as to suppress excessive yaw rate, thereby preventing undesirable turning behavior from occurring.

(Means for Solving the Problems) For this purpose, the turning behavior control device of the present invention, as conceptually shown in FIG. a vehicle speed detection means for detecting vehicle speed; a yaw rate detection means for detecting a yaw rate of the vehicle; a vehicle speed limit detection means for determining a tire grip limit vehicle speed according to a steering amount; a target yaw rate setting means for determining a target yaw rate for the vehicle; It is constructed by providing brake means for individually braking.

(Operation) When the vehicle is turning with its wheels steered, the steering amount detection means detects the steering amount of the wheels, and the limit vehicle speed detection means determines the tire grip limit vehicle speed from this steering amount. Further, the target yaw rate setting means determined the target yaw rate that should naturally be obtained from the steering amount and the diamond grip limit vehicle speed. When the vehicle speed detected by the vehicle speed detection means exceeds the tire grip limit vehicle speed, the braking means individually brakes the inner and outer wheels in the turning direction in such a manner that the yaw rate detected by the yaw rate detection means approaches the target yaw rate. Reduce tire grip to the limit vehicle speed.

Therefore, under any amount of steering, the vehicle speed will not exceed the tire grip limit vehicle speed, and the vehicle will always run in the grip range, and the vehicle's yaw rate will not exceed the target yaw rate, so that when the vehicle is turning It can prevent you from spinning or drifting out.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 shows an embodiment of the apparatus of the present invention, in which IL and IR indicate left and right front wheels, 2L and 2R indicate left and right rear wheels, 3L and 3R indicate front wheel cylinders, and 4L and 4R indicate rear wheel cylinders, respectively. 5 is a brake pedal, 6 is a master cylinder that simultaneously outputs the same hydraulic pressure to two systems 7.8 when the brake pedal is depressed, and the master cylinder hydraulic pressure of system 7 is routed through branched systems 7L and 7R to wheel cylinder 3L. , 3
R, the front wheels IL and IR are braked, and the master cylinder fluid pressure of system 8 passes through branched systems 8L and 8R to wheel cylinders 4L and 4R, where it is applied to the rear wheels 2.

Brake 2R.

In contrast to such a normal front-rear split type two-system hydraulic brake system, in this example, cut valves 11L and II are installed in systems 7L, 7R, 8L, and 8R, respectively, to open these systems in the normal state.
R.

Insert 12L and 12R. An accumulator 13 is provided which functions as a hydraulic pressure source for automatic braking, and a pump 14 supplies brake fluid from a reservoir 55 to this accumulator 13 to accumulate hydraulic pressure for automatic braking. The drive motor 15 of the pump 14 is connected to the power supply 17 via a pressure switch 16, which pressure switch
When the internal pressure of pump 3 reaches a specified value, it opens and motor 15 (pump 14) is turned off. In this way, the above specified pressure is always stored in the accumulator 13.

7-1-The internal pressure of the accumulator 13 is applied to the cut valves 11L, IIR, 12L, and 12R by the circuit 18, and these cut valves respond to the accumulator internal pressure to the corresponding system 7L.

7R, 8L, and 8R shall be cut off. The output chambers of cylinders 19L, 19R, 2OL, and 2OR are connected to these systems, respectively, and an electromagnetic proportional valve 21L is connected to the human power chamber of the cylinder.
, 21R, 22L, and 22R output ports. These electromagnetic proportional valves communicate output ports to the accumulator pressure circuit 18 and drain circuit 23 in accordance with the solenoid drive currents II to 14, and apply hydraulic pressure proportional to the corresponding solenoid drive current to the cylinders 19L, 19R, 2OL, 2O.
Supply to R.

The solenoid drive current i, % i 4 is controlled by a controller 31, which includes signals from a pressure sensor 32.33 for detecting the hydraulic pressure Pp and PR of the system 7.8, and a steering wheel (not shown) turning signal. Signals from the steering angle sensor 34 that detects the angle θ, and wheel rotation sensors 35 to 38 that detect the left front wheel rotation speed ω1, the right front wheel rotation speed ω2, the left rear wheel rotation speed ω3, and the right rear wheel rotation speed ω4, respectively. , as well as a signal from a yaw rate sensor 39 that detects the yaw rate Y of the vehicle.

The controller 31 executes the control program shown in FIG. 3 based on the human power information to perform normal wheel braking and wheel braking for turning behavior control, which will be described below. That is, first, in steps 41 to 43, the hydraulic pressure PFIPR1 wheel rotational speed ω1 to ω4, yaw rate Y, and steering angle θ of system 7.8 are read. Pressure PF, PR! Of course, if the brake pedal 5 is not depressed, the value is 0. In the next step 44, the vehicle speed V is calculated from the wheel rotational speeds ω1 to ω4. In this calculation, during non-braking when the brake pedal 5 is not depressed, the rotation speed of the front wheel, which is a non-driving wheel, is ω1. Since ω2 almost matches the vehicle speed, when the front wheel radius is R, V=R, (ω1+ω2)
/2 calculation. During braking, a pseudo vehicle speed is determined from all the wheel rotational speeds ω1 to ω by a method commonly used in anti-skid control, and this is set as the vehicle speed V.

In step 45, it is determined from the vehicle speed V and steering angle θ whether the vehicle is in the grip region or slip region as shown in FIG. In Figure 4, α indicates the tire grip limit vehicle speed,
Although it varies depending on the steering angle θ, if the vehicle speed V is below the limit vehicle speed, it is in the grip region, and if it exceeds the limit vehicle speed, it is in the slip region. In the slip area, the tires cannot resist the centrifugal force that occurs when turning, causing the tires to slip, causing the vehicle to spin or drift out.

For example, the vehicle speed V shown in Figure 4. , steering angle θ. To explain the case where the vehicle shifts to point B by increasing the steering angle θ to θ1 while driving at point B, the vehicle moves from the grip region to the slip region, causing the vehicle to spin or drift out. In this case, the vehicle speed is the limit vehicle speed V on the line α
, or less, the above-mentioned undesirable turning behavior will not occur.

If the grip area does not cause this undesirable turning behavior,
At step 46, set the front wheel cylinder to 3 cylinders.

System 7 corresponding to target brake fluid pressure P,, P, to 3R
Set the same hydraulic pressure PF for the rear wheel cylinders 4L and 4R, and set the target brake hydraulic pressure P3 to the rear wheel cylinders 4L and 4R. P4 is set to be the same as the hydraulic pressure P of the corresponding system 8. Then, in step 47, a fifth
Solenoid ratio valve 21L, 2 from the table data corresponding to the figure.
The drive currents 11 to 14 of 1R, 22L, and 22R are looked up, and in step 48 these are output to the corresponding electromagnetic proportional valves.

By the way, if the automatic brake fluid pressure sources 13 to 17 are normal and pressure is stored in the accumulator 13, the cut valves 11L, IIR, 12L, and 12R will respond to the corresponding systems 7L, 7R, 8L, and 8R. It's blocked.

For this reason, solenoid proportional valves 2LL, 21R, 22L, 2
2R is supplied with drive currents 11 to 14, and the corresponding cylinders 19L, 19R, 2OL,
When feeding the 2OR, these cylinders can supply brake fluid pressure to the corresponding wheel cylinders.

By the way, in order to determine the electromagnetic proportional valve drive currents i and %iQ as described above so that these brake fluid pressures are the same as the fluid pressures Pp and PR from the master cylinder 6,
Each wheel is braked normally in response to depression of the brake pedal 5.

If it is determined in step 45 that the vehicle is in the slip region, the tire grip limit vehicle speed ν corresponding to the current steering angle θ is determined.

(See Figure 4). Next step 50
, the target yaw rate Y3 of the vehicle, that is, the steering amount θ
The target yaw rate that should naturally be obtained from the tire grip limit vehicle speed V and tire grip limit is determined by Y and GJVS. Here, 65 is the limit lateral acceleration of the vehicle body at the tire grip limit vehicle speed, which differs from vehicle to vehicle, and is, for example, about 0.8G.

In the next step 51, the deviation EV between the detected vehicle speed V and the limit vehicle speed V is determined, and the deviation E between the detected yaw rate Y and the target yaw rate Y5 is determined. Next, in step 52, turning is carried out to reduce the vehicle speed deviation E and the yaw rate deviation (i.e., to bring the vehicle speed V closer to the limit vehicle speed V in such a manner that the yaw rate Y approaches the target yaw rate Y). Pout the target brake fluid pressure Pout for the outer wheels in the direction and the target brake fluid pressure Plh for the inner wheels in the turning direction ``Kv'By+L'' EvP, n=
Kv-Ev-KY・E.

Find it by Here, is the proportionality constant for vehicle speed deviation, K
Y is a proportionality constant for yaw rate deviation, which makes ε9
The brake fluid pressure until =0.8Y=0 is determined.

Also, if turning right, the left front and rear wheels are IL.

2L target brake fluid pressure P,, P3 is the target brake fluid pressure P01 for the outer wheel in the turning direction. Corresponding to the right front and rear wheels IR
.

2R target brake fluid pressure P2. P corresponds to the target brake fluid pressure Pin for the inner wheel in the turning direction, and the opposite is true if the vehicle is turning left.

Next, the control proceeds to steps 47 and 48, where the electromagnetic proportional valve drive currents 11 to 1 are used to obtain the target brake fluid pressures P1 to P.
By determining 4 and outputting it to the corresponding electromagnetic proportional valve, the vehicle speed is brought to the limit vehicle speed while bringing the yaw rate closer to the target yaw rate through individual automatic braking of the left and right wheels. Therefore, when the vehicle enters the slip region, the vehicle speed is reduced to the limit vehicle speed and returned to the grip region, and the yaw rate of the vehicle is prevented from exceeding the target yaw rate, thereby preventing the vehicle from spinning or drifting out. I can do it.

In addition, if the above-mentioned braking operation becomes impossible due to a failure of the hydraulic pressure sources 13 to 17, the pressure in the accumulator pressure circuit 18 disappears, and the cut valves ILL, IIR, 12L, and 12R are activated.
opens the corresponding systems 7L, 7R, 8L, and 8R.

Therefore, when the brake pedal 5 is depressed, the master cylinder hydraulic pressure output from the master cylinder 6 to the systems 7, 8 is directly applied to the wheel cylinders 3L, 3R, 4L,
Heading to 4R, you can brake each wheel directly without becoming unable to brake.

(Effects of the Invention) As described above, the device of the present invention is configured to suppress excessive vehicle speed and excessive yaw rate, which cause undesirable turning behavior of the vehicle, by individual automatic braking of the left and right wheels, so that the vehicle can always be driven in the grip area. At the same time, the yaw rate can be prevented from exceeding the target yaw rate, and undesirable turning behavior such as spin or drift-out of the vehicle can be prevented, greatly contributing to safety.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram of the turning behavior control device of the present invention, Fig. 2 is a system diagram showing an embodiment of the device of the present invention, Fig. 3 is a flowchart showing a control program of the controller on the same side, and Fig. 4 is a tire A diagram illustrating the grip limit vehicle speed, FIG. 5 is a diagram showing the relationship between the electromagnetic proportional valve drive current and the target brake fluid pressure. IL, IR...Front wheel 2L, 2R...
Rear wheels 3L, 3R, 4L, 4R...Wheel cylinder 5...Brake pedal 6...Master cylinder 11L, IIR, 12L, 12R...Cut valve 12...Accumulator 14...Pump 19L
, 19R, 2OL, 2OR...Cylinder 21L,
21R, 22L, 22R...Solenoid proportional valve 31...
・Controller 32.33...Pressure sensor 34
... Rudder angle sensor 35-38 ... Wheel rotation sensor 39 ... Yaw rate sensor Fig. 1 Fig. 3

Claims (1)

[Claims] 1. In a vehicle that is turned by wheel steering, a steering amount detection means for detecting the amount of wheel steering, a vehicle speed detection means for detecting vehicle speed, and a yaw rate detection means for detecting the yaw rate of the vehicle. , limit vehicle speed detection means for determining a tire grip limit vehicle speed according to the steering amount; target yaw rate setting means for determining a target yaw rate corresponding to these steering amounts and tire grip limit vehicle speed; when the detected vehicle speed exceeds the tire grip limit vehicle speed; Vehicle turning behavior control comprising: braking means for individually braking inner wheels and outer wheels in the turning direction so that the vehicle speed is reduced to a limit vehicle speed in such a manner that the detected yaw rate approaches the target yaw rate. Device.