JPH03246151A - Turning action controlling device for vehicle - Google Patents

Abstract

PURPOSE:To secure the stability of a vehicle while achieving a proper turning ability by providing a turning condition detecting means for detecting the turning condition of the vehicle, a deceleration detecting means for detecting the deceleration, and a wheel braking force setting means. CONSTITUTION:For turn controlling operation of a vehicle, a wheel braking force setting means sets wheel braking forces different between the inner side and outer side in the turning direction to generate a yaw moment corresponding to the turning condition in response to signals from a turning condition detecting means and a deceleration detecting means for detecting the turning condition and deceleration of the vehicle respectively, and the differential braking force is set corresponding to the deceleration. The differential braking force is thus set considering the deceleration also, so a proper control considering the deceleration is achieved, thereby the stability of the vehicle can be secured without setting the turning ability to be excessive even for a reduced speed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a turning behavior control device for a vehicle, and particularly to a device for controlling vehicle behavior during turning using braking.

(Prior Art) As a device for controlling braking force during turning braking of a vehicle, there is a device as described in Japanese Utility Model Application Publication No. 59-155264.

In this system, the timing to apply the brakes on the outer wheels is delayed compared to that on the inner wheels, and when a turning angle of the steering wheel exceeding a certain level is detected during braking, the control means applies the brakes on the wheels located on the outside of the turn. Control to delay the timing.

According to this method, it is possible to delay the increase in the hydraulic pressure of the outer wheel in the turning direction, that is, the increase in the brake hydraulic pressure, in accordance with the steering angle, and to generate a difference in braking force for obtaining initial turning performance.

(The secret H that the invention attempts to solve) However, when correcting the turning performance by generating a yaw moment based on the difference in braking force between the inner and outer wheels, the difference in braking force is uniformly determined only in the turning state defined by the amount of steering, etc. When making a decision, the vehicle behavior will depend on the deceleration during the turn. For example, it is determined based only on the amount of steering, and as in the above publication, a difference is made in the brake fluid pressure regardless of the deceleration (that is, a difference in braking force is set).
In this case, the tendency of the vehicle to spin during high lateral acceleration (high lateral G) and slow deceleration driving is strengthened, and the vehicle may turn more than the amount of steering by the driver. On the other hand, from this point,
If the braking force difference is kept low, it cannot be expected that sufficient turning performance will be obtained when necessary.

The present invention provides a turning behavior control device for a vehicle that improves turning performance when the vehicle turns and prevents excessive turning, thereby ensuring vehicle stability and ensuring appropriate turning performance. The purpose is to

(Means for Solving the Problems) For this purpose, the turning behavior control device of the present invention, as conceptually shown in FIG. 1, includes turning state detection means for detecting the turning state of the vehicle, and deceleration for detecting deceleration. detecting means; and in response to signals from these means, different wheel braking forces are applied between the inside and outside of the turning direction so as to generate a yaw moment in the vehicle according to the turning state when the vehicle is braked, and the braking force is changed according to the deceleration. and wheel braking force setting means for setting the difference.

(Function) When the vehicle is braking for a turning, the wheel braking force setting means adjusts the braking force of the vehicle according to the turning state in response to signals from the turning state detecting means and the deceleration detecting means, which respectively detect the turning state and deceleration of the vehicle. The braking force of the wheels is varied between the inner and outer sides of the turning direction to generate a yaw moment, and the difference in braking force is made to correspond to the deceleration.

As a result, the braking force difference is set in consideration of deceleration, and appropriate control that takes deceleration into account is possible.
& Even when waiting for deceleration, turning performance does not become excessive, ensuring vehicle stability.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 shows the configuration of an embodiment of the turning behavior control device of the present invention.

In FIG. 2, IL and IR indicate left and right front wheels, 2L and 2R indicate left and right rear wheels, 3 indicates a brake pedal, and 4 indicates a tandem master cylinder, respectively. Each wheel IL, IR, 2L, 2R is equipped with a wheel cylinder 5L, 5R, 6L, 6R,
When these wheel cylinders are supplied with hydraulic pressure from the master cylinder 4, each wheel is individually braked.

Here, to explain the brake hydraulic system, the front wheel brake system 7F from the master cylinder 4 is connected to the pressure response switching valve 8F.
, output chamber 9a of pilot cylinder 9F, conduit 10F,
IIF, 12F, and hydraulic pressure control valves 13F and 14F to the left and right front wheel cylinders 5L and 5R, and the rear brake system 7R from the master cylinder 4 is connected to the pressure response switching valve 8R and the output chamber 9 of the pilot cylinder 9R.
a, pipes 10R, IIR, 12R, hydraulic control valve 13R,
14R, it leads to left and right rear wheel cylinders 6L and 6R.

In relation to the input chambers 9b of the pilot cylinders 9F and 9R, the pump 15, the reservoir 16 and the accumulator 17
An automatic brake hydraulic pressure source including a hydraulic pressure source is provided, and an electromagnetic switching valve 18 is inserted between this and the pilot cylinder input chamber 9b. This valve 18 normally operates in the pilot cylinder input chamber 9b.
The pilot cylinders 9F and 9R are placed in the non-operating position as shown in the figure by communicating with the reservoir 16, and when ON, the pilot cylinder input chamber 9b is communicated with the accumulator 17, which is kept at a constant pressure by appropriately driving the pump 15, so that future liquid is The pressure causes the pistons 9C of the pilot cylinders 9F and 9R to stroke against the built-in spring 9d, and the output chamber 9a
The liquid inside is to be discharged.

In addition, the pressure response switching valves 8F and 8R open the corresponding systems 7F and 7R as shown in the diagram in normal conditions, and when the solenoid switching valve 18 is turned on and the pilot cylinders 9F and 9R are operated, the pressure thereon switches the valves. , systems 7F and 7R will be in a state where they are checked (blocking the liquid flow toward the master cylinder 4).

The electromagnetic switching valve 18 is controlled by a current i5 to the solenoid of the valve, which is output as a control signal from a controller to be described later, and is switched when the current i is OA (including during the foot brake). Valve 18 is OFF
(ie, normal state), the current is assumed to be ON when the current i is 2. Furthermore, when it is ON, as described above (system 7F,
7R is checked and the liquid in the output chambers 9a of the pilot cylinders 9F and 9R is discharged, and as a result, the pipes 10F and I
In the system after the OR, the hydraulic pressure is increased based on the automatic brake hydraulic pressure source without depending on the depression of the brake pedal 3, and therefore the wheels IL, IR, 2L, and 2R are controlled by their respective hydraulic pressure control valves 13F. , 14F, 13R, and 14R, braking is automatically performed for the wheels corresponding to the wheels to be controlled (automatic braking).

The hydraulic pressure control valves 13F, 14F, 13R, 14R are connected to the wheel cylinders 5L, SR, 6L of the corresponding wheels, respectively.
, the brake fluid pressure toward 6R is individually controlled for anti-skindoing and turning behavior control of the present invention,
When OFF, the brake fluid pressure is at the pressure increase position shown in the figure, increasing the pressure toward the source pressure. When the first stage is ON, the brake fluid pressure is at a holding position, where the brake fluid pressure does not increase or decrease. When the second stage is ON, the brake fluid pressure is partially reduced. This will be the depressurization position where the pressure will be lowered by releasing it to Zaha 19F and 19R.

The control of these hydraulic pressure control valves is also carried out by the current from the controller (described later) to the solenoid of the corresponding valve (control valve drive current).
1l=i, when the currents 11 to i4 are OA, the pressure increase position is set, when the currents 11 to i4 are 2A, the pressure holding position is set, and when the current iI-1a is 5A, the pressure reduction position is set. do.

The brake fluid in the reservoirs 19F and 19R is pumped by the pumps 20F and 2OR, which are driven during pressure retention and pressure reduction.
This is returned to the conduit 10F and IOR, and similar accumulators 21F and 21R are connected and provided to these conduits as well. The accumulators 21F and 21R accumulate hydraulic pressure due to the stroke of the piston 9C of the pilot cylinder during automatic braking.

The hydraulic pressure control valves 13F, 14F, 13'R, 14R and the electromagnetic switching valve 18 are turned on and off by the controller 22, respectively.
This controller 22 receives a signal from a steering angle sensor 23 that detects the steering angle θ, a signal from a brake switch 24 that is turned ON when the brake pedal 3 is depressed, and the rotation of wheels IL, IR, 2L, and 2R. Signals from wheel speed sensors 25 to 28 that detect circumferential speeds 1 to VW4, lateral acceleration sensors that detect lateral acceleration g of the vehicle body (
A signal from a lateral G sensor) 29 and a signal from a longitudinal acceleration sensor (a longitudinal G sensor) 30 are respectively input. Signals from wheel speed sensors are used for antiskin and traction control. For traction control, it is assumed that a control signal is sent from the controller 22 to the engine power regulator.

The controller 22 also includes a wheel cylinder 5L for each wheel.
, 5R, 6L, and signals from hydraulic pressure sensors 31R, 31L, 32L, and 32R that detect hydraulic pressures P1 to P4 of 6R are input.

The output of the hydraulic pressure sensor for each wheel is determined by setting a target value for the wheel cylinder hydraulic pressure so that the deviation between the target value and the actual wheel cylinder hydraulic pressure becomes zero (that is, adjusting the wheel cylinder hydraulic pressure to that target value). It is used as a control signal when performing feedback control of brake fluid pressure (so as to match the brake fluid pressure).

In the above embodiment system, during normal braking, braking is performed as follows.

When the brake pedal 3 is depressed during normal braking, the controller 22 receives a signal from the brake switch 24, which closes in response, and turns the electromagnetic switching valve 18 to 0FF (is=o).
As a result, the pilot cylinder 9F,
9R connects the input chamber 9b to the reservoir 16 and maintains the position shown in the figure, the pressure response switching valves 8F and 8R also maintain the position shown in the figure, and the front and rear wheel brake systems 7F and 7R are opened. Further, the controller 22 controls the wheels IL and IR.

Hydraulic pressure control valve 1 unless brake lock occurs in 2L and 2R.
Turn off 3F, 14F, 13R, 14R (L-i
4=O) and keep it in the state shown.

Therefore, the same hydraulic pressure (master cylinder hydraulic pressure) simultaneously output from the master cylinder 4 to the front and rear wheel brake systems 7F and 7R when the brake pedal 3 is depressed is applied to the pressure responsive switching valves 8F and 81?, respectively. , pilot cylinder 9F
, 9R's output chamber 9a, conduit 10F, IOR and hydraulic pressure control valves 13F, 14F, 13R, 14R, and the brake fluid pressure is sent to the wheel cylinders 5L, 5R, 6L.
, 6R, and brake each wheel IL, IR, 2L, and 2R individually.

During this time, the controller 22 calculates a pseudo vehicle speed by a well-known calculation from the rotational circumferential speeds (wheel speeds) ■1 to VW4 of the wheels IL, IR, 2L, and 2R detected by the sensors 25 to 28,
The braking slip rate of each wheel is calculated from this and the individual wheel speed. Then, the controller 22 determines whether or not the brakes of each wheel are locked based on this slip ratio, and when the brake is about to lock, the hydraulic pressure control valves 13F and 14F of the corresponding wheel are activated.

By setting 13R or 14R to the first stage ONt, the brake fluid pressure of the corresponding wheel is prevented from increasing further. If brake lock occurs despite this,
The controller 22 turns on the hydraulic pressure control valve of the corresponding wheel in two steps.
By setting the brake fluid to the reduced pressure position, the brake fluid pressure of the relevant wheel is lowered to prevent brake lock. As a result, when the corresponding wheel starts to recover its rotation (spinnerve), the controller 22 sets the hydraulic pressure control valve of the corresponding wheel to the pressure holding position and stops any further decrease in the brake hydraulic pressure. Then, as the rotation of the wheel is restored, the controller 22 turns off the hydraulic pressure control valve of the corresponding wheel to the pressure increasing position, thereby increasing the brake hydraulic pressure toward the master cylinder hydraulic pressure. By repeating the skinned cycle described above, the brake fluid pressure of each wheel is controlled to a value that achieves maximum braking efficiency, and normal anti-skid control is performed.

FIG. 3 is a control program showing an example of the main turning behavior control (turning behavior control 11 during foot braking) including braking force difference correction processing according to deceleration executed by the controller 22. This process is executed by an operating system (not shown) using regular interrupts at regular intervals.

First, in step 101, the steering angle θ of the steering wheel is determined from the signals of the steering angle sensor 23 and the longitudinal G sensor 30.
Read each deceleration α. In the next step 102, it is determined whether the brake pedal 3 is depressed by the driver based on whether the brake switch 24 is turned on. If the result is NO, that is, if the brake pedal 3 is not depressed, the main turning behavior control is not necessary in this program example, so the process proceeds to step 106 and sets ΔP as the brake fluid pressure difference command value to be described later. Let it be O. In this case, this program ends through steps 104 and 105, but each hydraulic pressure control valve drive current 11 to i4 is set to OA.
1, and each hydraulic pressure control valve maintains its normal OFF position as shown in FIG.

On the other hand, if the answer to step 102 is Yes, the brake pedal 3
If it is determined that the driver has stepped down, the process proceeds to step 103 and subsequent steps to perform the turning behavior control that the present invention aims at.

That is, a difference is created between the left and right braking forces of the front and/or rear wheels depending on the turning state and deceleration, so that the braking force of the outer wheel in the turning direction is lower than the braking force of the inner wheel in the turning direction. Execute processing for control.

In step 103, the brake fluid pressure difference ΔP between the inner and outer wheels in the turning direction is determined according to the magnitude of the steering angle θ, and the braking force difference is corrected according to the deceleration α based on this fluid pressure difference ΔP. After correction, a ΔP value as a final brake fluid pressure difference command value is calculated. Fig. 4 shows an example of the characteristics for calculating the hydraulic pressure difference ΔP, which should be set according to the steering angle θ, and the hydraulic pressure difference ΔP1 increases as the steering angle θ becomes larger in the range where the steering angle θ is a predetermined value 08 or more. The value is set to be . Further, FIG. 5 shows an example of the characteristics of the correction coefficient used for the above correction. The correction coefficient 1 is a coefficient that is multiplied by the value ΔP in order to adjust the control gain according to the deceleration α, and is such that the differential pressure at the time of i deceleration is reduced.
The characteristics shown in the figure are set corresponding to the deceleration α within a range up to a predetermined value α.

Therefore, in step 103, the brake fluid pressure difference ΔP is determined from the above-mentioned relationship based on the steering angle θ and deceleration α at the time of execution of the step, and at the same time, a correction coefficient of 1 is determined, and these are used to determine the actual brake fluid pressure difference ΔP. The brake fluid pressure difference ΔP between the inner and outer wheels is calculated and determined according to the following formula.

ΔP = K, xΔp, ---(i
) Next, in steps 104 and 105, using the hydraulic pressure difference ΔP determined above, the brake hydraulic pressure P, (
j = 1 to 4), and the corresponding hydraulic pressure control valve drive current i
Lookup and output. In order to achieve the determined hydraulic pressure difference, for example, the outer wheels IR in the turning direction should be adjusted so that the hydraulic pressure difference ΔP is generated between the inner and outer wheels.

Try to lower the hydraulic pressure P2+P of 2R (when turning left) or IL, 2L (when turning right), (when turning left) or pHp:l (when turning right). In this case, in this embodiment, each wheel is provided with hydraulic pressure sensors 31L, 31R, 32L, and 32R, so if the turning direction is determined based on the sign of the steering angle θ signal, for example, if it is determined to be a left turn, For example, the set brake fluid pressure P2 for the front wheel IR on the outside in the turning direction and the set brake fluid pressure P4 for the rear wheel 2R can be determined in the following manner, and feedback control can be performed so that they respectively match their target values. .

Pz-P+-ΔP ---(2)P,
= P3-ΔP --- (3) Here, the first term on the right side in each of the above equations is the actual hydraulic pressure of the wheel cylinders 5L and 61 due to the brake pedal depression force of the inner front axle IL and the rear wheel 2L, respectively. That is, the hydraulic pressure sensor 31
This is the brake fluid pressure detected by L and 32L. In this example, based on this, the hydraulic pressure on the outer ring side is set to be lower by 62 minutes. In this way, the braking force of the inner wheels IL, 2L is controlled by the hydraulic pressure control valves 13F, 13R so as to depend on the force of pressing the brake pedal.
The drive currents 11+13 of 11 and 13 are kept at OA, while the braking force of the outer wheels IR and 2H is limited, that is, the brake fluid pressure is set according to equations (2) and (3) above. In order to operate the hydraulic pressure control valves 14F and 14R, the pattern of the driving electric current vLlz+i4 (ON-OFF pattern of the control valve) may be determined and output.

With the above control, when braking is performed by depressing the brake pedal 3, the braking force of the outer wheel in the turning direction is smaller than the value corresponding to the depressing force of the brake pedal 3. Therefore, the vehicle turns due to the yaw moment in the turning direction. Although it is encouraged,
In this case, as in equation (1) above, the hydraulic pressure difference ΔP, which depends on the steering angle θ, is multiplied by a correction coefficient of 1, so that the differential pressure becomes small during slow deceleration, that is, the braking force difference becomes small. Therefore, correction is performed so that the yaw moment becomes small.

When the braking force difference is determined only by the amount of steering, the turning tendency becomes too strong during slow deceleration and there is a risk of spin.
In this example, the braking force difference is generated by making the braking force of the outer wheel in the turning direction smaller than the braking force of the inner wheel according to the magnitude of the steering angle θ and the deceleration α, so that the braking force difference is appropriately controlled. The power difference is set. This eliminates the problem of poor turning performance that typically occurs during braking and poor steering effectiveness (even when the steering wheel is turned, the vehicle's trajectory tends to swell outward in the direction of the turn). In addition, it is possible to avoid a situation in which the vehicle turns more than the amount of steering by the driver during high g/overturn speed braking, and it is possible to achieve control without excess or deficiency.

In the above, the brake fluid pressure difference ΔP was determined by correcting the correction coefficient according to the deceleration α by +, but the fluid pressure difference may be further modified in accordance with the vehicle speed.

The vehicle speed is obtained by a vehicle speed detection means such as estimating the vehicle speed from the rotational speed of the driven wheels, and in the process at step 103 in FIG. 3, 2 is added to the correction coefficient depending on the vehicle speed as shown in FIG.
By additionally applying and determining the brake fluid pressure difference ΔP by the calculation of 8P""K+XKz×ΔP1, fine-grained control of the negative layer is possible.

In addition, the steering angle θ was used to detect the turning state, but
Lateral acceleration, yaw rate, etc. may be used instead of or together with the steering angle θ.

Furthermore, in the case of a vehicle that has a high G and has a very large yaw rate during slow deceleration braking, it is possible to apply a differential pressure in the direction of stability during slow deceleration.

FIG. 7 is a control program showing another example of the present invention. Whereas the previous program was a system that controlled only when the brake pedal was depressed, it is also possible to control turning behavior when the foot brake is not applied. This is what I did.

The processing in steps 101 to 105b is performed in step 1 of FIG.
This is similar to cases 01 to 105, but step 1
If it is determined in step 02 that the brake pedal 3 is not depressed, the automatic brake is turned on in step 106a.
Determine whether the timing is right. This can be determined, for example, by checking whether the vehicle is in a predetermined turning state during engine braking.

If the answer to step 106a is Yes, step 10
At 6b, in order to perform braking by the automatic brake hydraulic pressure source, the current is switched to a state of 1s=2A, that is, to turn on the switching valve 18, and at the next step 106C, step 1 is set.
Similarly to 03, the hydraulic pressure difference ΔP calculation process is executed based on FIGS. 4 and 5. In step 106d, for example, the brake fluid pressure of the inner wheel in the turning direction P1. .

(When turning left, Pl, P:I, when turning right, P:
Z+P4) is set to the above ΔP value, and the brake fluid pressure P of the outer wheel. As for ut, it is set to O, steps 105a and 105b are executed, and this program is ended. In this case, the control valve drive current corresponding to the inner wheel in the turning direction is 11+ t3 (when turning left) or 12+
i4 (when turning right), the pattern (control valve ON-OFF pattern)
is set, while for the outer wheels, the wheel hydraulic pressure control valve drive current is set to 28, and is switched to and held at the pressure holding position. In this way, each current 11 to 141
Is is set and output, and the electromagnetic switching valve 18 and hydraulic pressure control valve 13
By controlling F, 14F, 1313R, and 14R, the automatic brake system is activated, and the brake fluid pressure of the inner wheel in the turning direction is controlled to the ΔP value, while the brake fluid pressure of the outer wheel is prevented from increasing. Therefore, a braking force difference can be automatically generated between the two to generate a yaw moment, and the braking force difference can be made appropriate depending on the deceleration at that time.

Note that if the answer to step 106a is NO, ΔP is set to the value O in step 106e, and the automatic brake system is also left inactive.

As described above, even when braking is not applied (non-footbraking), the main control is applied according to engine brake deceleration, that is, automatic braking is applied when turning, and in that case, braking force difference is also applied according to the magnitude of deceleration. Control may be performed to increase the brake fluid pressure of the inner wheel so that this occurs.

In each of the above-mentioned sides, both the front wheels and the rear wheels are controlled, but the braking force difference may be generated between the inner and outer wheels by controlling only the front wheels or only the rear wheels. Also, the fluid pressure difference ΔP
may be a function of time, for example, after being determined -1, it gradually decreases as time passes, and after a predetermined time ΔP=O
It may also be configured to gradually decrease as ΔP becomes 0 after a predetermined period of time. Furthermore, in order to provide a difference in braking force, a hydraulic pressure sensor was used and its detected value was used to control the brake hydraulic pressure of the wheels, but the ON/OFF operation of the hydraulic pressure control valve was made to correspond to the hydraulic pressure value in advance. If this is done, that is, if the control wJ mode is not performed with feedback control, a hydraulic pressure sensor is not necessary for this turning behavior control, and the 0N-OFF
If a proportional valve is used instead of a type control valve, the hydraulic pressure is determined by the current command, so a hydraulic pressure sensor is not necessary in this case as well, and such a configuration may be used.

(Effects of the Invention) Thus, as described above, the turning behavior control device of the present invention varies the braking force between the inner and outer wheels in the turning direction so that a yaw moment is generated during turning braking, and the difference in braking force is made to correspond to the deceleration. Because of this configuration, it is possible to perform appropriate behavior control that takes into account not only turning conditions but also deceleration, and it is possible to prevent excessive turning even during slow deceleration, improving turning performance while ensuring stability. can be achieved.

[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 turning behavior control device of the present invention, and Fig. 3 is a flowchart showing an example of a control program of the controller during turning. , Figure 4 is a diagram showing an example of the characteristics for setting the brake fluid pressure difference ΔP according to the steering angle applied in the same program, and Figure 5 is a diagram showing an example of the characteristics for the correction coefficient due to deceleration. FIG. 6 is a diagram showing an example of a characteristic with a correction coefficient of 2 depending on vehicle speed, and FIG. 7 is a flowchart showing another example of a control program of the controller. LL, IR...Front wheel 2L, 2R...Rear wheel 3...Brake pedal 4...Tandem master cylinder 5L, 5R, 6L, 6R...Wheel cylinder 7
R...Rear brake system 8F, 8R...Pressure response switching valve 9F, 9R...Pilot cylinder 10F, IO
R, IIF, IIR, 12F, 12R...Pipe 1
3F, 13R, 14F, 14R...hydraulic pressure control valve 1
5, 20F, 2OR...Pump 16, 19F, 19R...Reservoir 17, 21F,
21R...Accumulator 18...Solenoid switching valve 22...Controller 23...Steering angle sensor 24...Brake switch 25, 26.27.28...Wheel speed sensor 29...
Lateral acceleration sensor 30... Longitudinal acceleration sensor 31L, 31R, 32L, 32R... Hydraulic pressure sensor Figure

Claims (1)

[Claims] 1. Turning state detection means for detecting the turning state of the vehicle; deceleration detection means for detecting deceleration; and in response to signals from these means, the vehicle A vehicle characterized in that it is equipped with a wheel braking force setting means for differentiating the wheel braking force between the inner and outer sides of the turning direction so as to generate a yaw moment, and for setting the difference in braking force according to the deceleration. Turning behavior control device. 2. The turning state detection means includes lateral acceleration detection means for detecting lateral acceleration applied to the vehicle, and the wheel braking force setting means is configured to set a difference in braking force in a stable direction during slow deceleration when lateral acceleration is large. 2. The vehicle turning behavior control device according to claim 1, wherein the wheel braking force is set to .