JPH04372446A - Brake device for automobile - Google Patents

Abstract

PURPOSE:To suppress spin, carry out drift control and improve the traveling stability by permitting a brake power to be supplied as yap controlling brake power to one between the left and right brake mechanisms and setting the supply direction and supply quantity of the yaw controlling brake power according to the traveling state. CONSTITUTION:A brake power generating means C which generated a brake power separately from the operation of a brake pedal 22 and consists of a hydraulic pump-32 and an accumulator 33 for storing a hydraulic pressure is provided, and the generated brake power is adjusted so as to secure a necessary distribution ratio by a brake power supply adjusting means A consisting of a hydraulic control valve and applied to the brake mechanisms LB and RB for left and right wheels. The brake power supply adjusting means A performs control so that the supply direction and supply quantity of the yaw controlling brake power are adjusted in the direction for correcting the yaw behavior to the stable side by a supply state setting means 15A in an ECU 15, when the yaw behavior deflects from the stable state.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking system for an automobile, and more particularly to a braking system for an automobile that can perform yaw rate control to suppress spin and drift.

0002

[Prior Art] Various yaw rate controls have been proposed for automobiles to suppress spin and drift, but these generally use a 4WS (four-wheel steering) system to steer the rear wheels in addition to the front wheels. It is done by doing.

[0003] For example, in the case of spin suppression, it can be suppressed by increasing the rear wheels in the same phase as the front wheels, so while detecting the movement in the yaw direction (yaw rate) of the vehicle when turning, this yaw rate is adjusted to the turning state. This is done through feedback control of the steering state of the rear wheels to the in-phase side so that the steering condition is adjusted accordingly.

0004

[Problems to be Solved by the Invention] However, since such conventional yaw rate control means only control force in the vehicle width direction (lateral direction), the control range is limited, and in particular, it is difficult to control the behavior of the vehicle body. There is a problem in that near the limit of , it is not possible to obtain much control effect, and it is not possible to sufficiently stabilize the behavior and attitude of the vehicle body, such as spin suppression and drift suppression.

In particular, the characteristics of the movement of the vehicle in the yaw direction, such as the steering characteristics when turning, change slightly depending on the on/off state of the accelerator and the state of the braking operation.

[0006] Furthermore, when the accelerator is turned off during a turn or when braking on a road with a low friction coefficient, the tendency to oversteer increases.
There is a risk that the tendency of understeer will increase and the behavior of the vehicle will become unstable.

Furthermore, even when traveling straight, the movement characteristics of the vehicle in the yaw direction may change slightly depending on the on/off state of the accelerator or the braking operation, and the posture of the vehicle body may not be stable.

[0008] In order to suppress such undesirable phenomena, quick control is required, but since control by steering is poor in responsiveness, even four-wheel steering is insufficient to suppress such phenomena. There are challenges.

The present invention was devised in view of the above-mentioned problems, and is capable of quickly and reliably controlling the movement of an automobile in the yaw direction, thereby suppressing spin and drift, as well as controlling the movement when turning or going straight. An object of the present invention is to provide a braking device for an automobile that can ensure running stability of an automobile.

0010

[Means for Solving the Problems] Therefore, the braking device for an automobile of the present invention includes a braking force generating means for generating braking force, and a left wheel braking mechanism for braking the left wheel of the automobile, in the braking system of the automobile. , a right wheel braking mechanism for braking a right wheel of the automobile, and appropriately supplying braking force from the braking force generating means to either the left wheel braking mechanism or the right wheel braking mechanism as a braking force for yaw control. and supply state setting means for setting the supply direction and supply amount when the braking force for yaw control is supplied by the braking force supply regulating means in accordance with the running state of the vehicle. It is characterized by

Preferably, the automobile is provided with yaw behavior determining means for determining whether or not the yaw behavior of the vehicle body during running deviates from a stable state, and the supply state setting means is connected to the yaw behavior determining means. When it is determined that the yaw behavior of the vehicle body deviates from a stable state, the braking force supply adjusting means adjusts the yaw behavior by a predetermined amount in the direction of correcting it to the stable side so that the braking force for yaw control is supplied. The above-mentioned supply direction and supply amount are set so as to generate a moment of force.

0012

[Function] In the above-mentioned braking device for an automobile according to the present invention, when the supply state setting means needs to supply braking force for yaw control by the braking force supply adjusting means depending on the running state of the automobile, the supply state setting means determines the supply direction. The braking mechanism is set to either the left wheel braking mechanism or the right wheel braking mechanism, and the amount of braking force to be supplied for yaw control. Then, the braking force supply adjusting means supplies the braking force from the braking force generating operation means to the left wheel braking mechanism or the right wheel braking mechanism as a braking force for yaw control according to the set conditions. As a result, a moment is generated in the vehicle body in the yaw direction due to the braking force applied to one of the left and right wheels, and this moment can be used to control the attitude of the vehicle body in the yaw direction.

In particular, the vehicle is equipped with a yaw behavior determining means for determining whether the yaw behavior of the vehicle body deviates from the stable state during running, and the yaw behavior determining means determines whether the yaw behavior of the vehicle body deviates from the stable state. When it is determined that this is the case, the distribution state setting means generates a moment of a predetermined magnitude in a direction to correct the yaw behavior toward stability so that the braking force supply adjustment means supplies braking force for yaw control. Since the above-mentioned supply direction and supply amount are set, the yaw behavior of the vehicle body is controlled to be stable.

[0014]

[Embodiment] Hereinafter, embodiments of the present invention will be explained with reference to the drawings. Figs. 1 and 2 show a braking device for an automobile as an embodiment of the present invention, and Fig. 1 is a schematic diagram showing the structure of the braking device. The formula diagram and FIG. 2 are flowcharts showing the operation of the main parts.

As shown in FIG. 1, the automobile braking system B of this embodiment includes a brake pedal 22 that performs an artificial braking operation, and a braking force generator that generates braking force separately from the operation of the brake pedal 22. Means C, and a left wheel braking mechanism L that brakes the left wheels of the automobile (that is, the left front wheel 1L and the left rear wheel 13L).
B and the right wheels of the car (that is, the right front wheel 1R and the right rear wheel 13)
A right wheel braking mechanism RB and a left wheel braking mechanism LB that brake R)
and a braking force supply adjusting means A that adjusts the supply of braking force to the right wheel braking mechanism RB, and a supply state setting means 15A that sets the braking force supply state by the braking force supply adjusting means A.

The brake pedal 22 is connected to a master cylinder 22A, and braking hydraulic pressure is delivered from the master cylinder 22A in accordance with the amount by which the brake pedal 22 is depressed.

The braking force generating means C consists of a hydraulic pump 32 and an accumulator 33 that stores the pressure oil pressurized by the hydraulic pump 32, and is designed to always store a predetermined hydraulic pressure regardless of the brake pedal 22. .

The left wheel braking system LB has a front left wheel 1L and a rear left wheel 1.
3L with a required distribution ratio, and is comprised of hydraulic braking mechanisms 311 and 313 such as hydraulic piping, cylinders, and brake shoes driven by the cylinders. The right wheel braking system RB, like the left wheel braking system LB, is composed of hydraulic braking mechanisms 312 and 314, and applies braking force to the front right wheel 1R and the rear right wheel 13R at a required distribution ratio. There is.

[0019] Then, the left wheel braking system LB and the right wheel braking system RB
are designed to operate independently of each other, and the braking force acting on the right wheel braking system RB and the braking force acting on the left wheel braking system LB are distributed as required through the braking force supply adjustment means A. It is now adjusted to follow the ratio.

The braking force supply adjustment means A is constituted by a hydraulic control valve, and the hydraulic control valve A connects the hydraulic pressure of the master cylinder, which is delivered in response to depression of the brake pedal 22, to the hydraulic control valve A. The braking force is distributed to each hydraulic system of the right-wheel braking system RB and the left-wheel braking system LB at a predetermined distribution ratio, and the braking force is supplied by the supply state setting means 15A even if the brake pedal 22 is not depressed. Then, an appropriate amount of braking force from the braking force generating means C can be supplied to either the left wheel braking mechanism LB or the right wheel braking mechanism RB.

The supply state setting means 15A is provided in the electronic control unit (ECU) 15 mounted on the vehicle, and is for setting the distribution state by the braking force supply adjustment means A according to the running state of the vehicle. Specifically, ECU15
When it is determined that the yaw behavior of the vehicle body deviates from a stable state according to the judgment of the yaw behavior judgment means (not shown) provided in the yaw behavior judgment means (not shown) provided in the The braking force supply state is set so as to generate a moment (yaw behavior stabilizing moment).

In other words, when the brake pedal 22 is depressed, the braking force distribution state to the left and right wheels is set, and when the brake pedal 22 is not depressed, the right wheel braking system RB and the left wheel are distributed. Braking system LB
A required amount of supply braking force is set for either one of them, and the setting of this braking force will be explained in detail later.

The ECU 15 includes a vehicle speed sensor 29 that detects the speed of the vehicle, a yaw rate sensor 23 that detects the turning state of the vehicle, a lateral G sensor 27 that detects the lateral acceleration of the vehicle, and an operating angle of the steering wheel 4 (steering wheel angle). ) is connected to a steering wheel angle sensor 16 that detects the angle.

The above-mentioned yaw behavior judgment means determines the deviation Δ between the yaw rate Ψ′ that actually occurs in the vehicle and the yaw rate (theoretical yaw rate) ΨI′ that naturally occurs when turning.
Ψ′ is larger than the threshold α, and this yaw rate deviation Δ
When the time rate of change (time differential) ΔΨ″ of Ψ′ is larger than the threshold β, it is determined that the yaw behavior of the vehicle body has deviated from a stable state.

[0025] The yaw behavior of the vehicle body deviates from a stable state when, for example, the vehicle tends to spin or drift. Here, we are particularly trying to control the vehicle so that it tends to spin. The yaw behavior judgment also determines whether there is this spin tendency.

The judgment by this yaw behavior judgment means is based on the EC
Lateral acceleration ay from the lateral G sensor 27 input to U15
and the vehicle speed V from the vehicle speed sensor 29, the theoretical yaw rate ΨI' can be calculated using the following formula: ΨI'=ay/V

...obtained from (1), this theoretical yaw rate Ψ
I' and the yaw rate Ψ' from the yaw rate sensor 23 (
= dΨ/dt), the yaw rate deviation ΔΨ' can be calculated using the following formula: ΔΨ'=Ψ'-ay/V
...
(2), the deviation ΔΨ' is compared with the threshold value α, and the time change rate ΔΨ''(=dΨ'/dt) of the deviation ΔΨ' is compared with the threshold value β.

[0027] In this way, the reason for using not only the deviation ΔΨ' but also its time rate of change ΔΨ'' as a criterion is when the yaw behavior of the vehicle body starts to deviate from a stable state, for example at the start of a spin. Sometimes, the deviation ΔΨ′ should increase rapidly at a certain speed, and conversely, if the deviation ΔΨ′ does not suddenly increase, the yaw behavior is considered to be within the stable state. Thresholds α and β are set so that it can be quickly determined that the deviation from the stable state has started.
A relatively small value is selected for .

The supply state setting means 15A sets the yaw behavior stabilizing moment (here, spin suppressing moment) M
The following formula M=IZ ・ΔΨ″ (where IZ: moment of inertia of the vehicle)

・
...(3) is calculated, and the distribution state of the braking force to the left and right wheels is set so that this moment M is generated.

[0029] In order to realize such a moment M,
The difference BF between the left and right braking forces may be adjusted as shown in the following equation (4). BF =2×M/TR (However, TR
: tread) ...(4)

For this reason, the supply state setting means 15A calculates the difference BF between the left and right braking forces from equation (4), and adjusts, for example, the spin during turning so that the moment M is generated in the direction that stabilizes the yaw behavior. For suppression, the braking force on the outer wheel (outer wheel) side of the turn is set to be greater than the braking force on the inner wheel side by a difference BF.

Therefore, when the brake pedal 22 is not depressed, the braking force BF is applied to only one of the right-wheel braking system RB and the left-wheel braking system LB (the outer-wheel braking system for spin suppression during turning). give. Furthermore, if the brake pedal 22 is depressed, the braking hydraulic pressure (corresponding to the total braking force applied to the front wheels) is outputted from the master cylinder 22A according to the amount of depression as the braking force BF.
Until reaching B, the braking force B is applied only to one of the braking systems mentioned above.
If the braking hydraulic pressure exceeds the braking force BF from the master cylinder 22A that is output according to the amount of depression, the excess brake force is applied to the right wheel braking system RB and the left wheel braking system at a predetermined ratio (for example, 1:1). It is distributed to the braking system LB.

As a result, regardless of whether or not the brake pedal 22 is depressed, when the yaw behavior becomes unstable, a moment M is generated by the braking force BF in a direction that stabilizes the yaw behavior, and the yaw behavior is stabilized. Further, when the brake pedal 22 is depressed, the braking force is increased according to the amount of depression.

With the above-described configuration, the automobile braking device B of this embodiment controls braking in the following manner.

Right wheel braking system R by braking force supply adjustment means A
The supply state of the braking force to the braking system B and the left wheel braking system LB is set by the supply state setting means 15A, and the control by the supply state setting means 15A and the braking force supply adjusting means A is performed, for example, according to the flowchart shown in FIG. The procedure is as follows.

That is, first, the yaw rate Ψ' detected by the yaw rate sensor 23, the lateral acceleration ay detected by the lateral G sensor 27, and the vehicle speed V detected by the vehicle speed sensor 29 are read into the ECU 15 (step S1). .

Next, the yaw behavior judgment means determines the theoretical yaw rate ay/V found from the detected yaw rate Ψ′ actually occurring in the vehicle, the lateral acceleration ay, and the vehicle speed V.
The absolute value of the deviation ΔΨ′ is calculated using equation (1) (
Step S2).

Then, the yaw behavior judgment means determines the deviation ΔΨ'
is larger than the threshold α and the time change rate ΔΨ of the deviation ΔΨ′
″ is larger than the threshold β (step S3
).

If this condition is not met, it can be determined that the yaw behavior of the vehicle has not started to deviate from a stable state, such as in a spin, and the left/right distribution of braking force will not be changed; If so, it can be determined that the yaw behavior of the vehicle body has started to deviate from the stable state, and step S
Proceed to step 4 and subsequent steps to control the left and right distribution of braking force.

Then, in step S4, a yaw behavior stabilizing moment (spin suppressing moment) M is calculated using equation (3) through the supply state setting means 15A, and the process proceeds to step S5, in which this spin suppressing moment M is realized. The left and right braking force difference BF is calculated using equation (4).

Furthermore, in step S6, the left and right braking force difference B
The brake fluid pressure that achieves F is calculated, and the braking system on the required side (the braking system on the outer wheel side if suppressing spin during turning) is operated in accordance with this brake fluid pressure.

Once the left and right braking force difference BF is set in this way, the braking force is distributed through the braking force supply adjustment means (hydraulic control valve) A so that the set left and right braking force difference BF is achieved. .

For example, when the brake pedal 22 is not depressed, the right wheel braking system RB and the left wheel braking system LB
Braking force BF is applied to only one of the braking systems (the braking system on the outer wheel side for spin suppression during turning), and if the brake pedal 22 is depressed, the master cylinder 22A outputs an output according to the amount of depression. Until the braking hydraulic pressure (corresponding to the total braking force applied to the front wheels) reaches the braking force BF, the braking force BF is applied only to one of the braking systems mentioned above, and the master cylinder 2 outputs an output according to the amount of depression.
When the braking oil pressure from 2A exceeds the braking force BF, the excess braking force is distributed to the right wheel braking system RB and the left wheel braking system LB at a predetermined ratio (for example, 1:1).

As a result, regardless of whether or not the brake pedal 22 is depressed, when the yaw behavior is about to become unstable, a moment M is generated by the braking force BF in a direction that stabilizes the yaw behavior, and the yaw behavior is stabilized. Further, when the brake pedal 22 is depressed, the braking force is increased according to the amount of depression.

As a result, the yaw behavior of the vehicle body is quickly and reliably controlled to a stable state, making it possible to achieve a high level of spin and drift suppression during turns, and to improve the control effect particularly near the limits of vehicle behavior. You will get more. It also has the effect of improving straight-line stability, which tends to be impaired depending on poor road conditions, accelerator on/off, and braking operations.

[0045] Furthermore, it is highly conceivable that this automobile braking device be installed in a car equipped with a 4WS system to stabilize the yaw behavior in cooperation with the 4WS system. Performance can be further improved.

[0046]

As described in detail above, according to the automobile braking device of the present invention, the braking system of the automobile includes a braking force generating means that generates a braking force, and a left wheel braking device that brakes the left wheel of the automobile. and a right wheel braking mechanism for braking a right wheel of the automobile, and applying braking force from the braking force generating means to either the left wheel braking mechanism or the right wheel braking mechanism as a braking force for yaw control. A braking force supply adjustment means that can supply the braking force as appropriate; and a supply state setting means that sets the supply direction and amount of braking force for yaw control when the braking force supply adjustment means supplies the braking force for yaw control according to the driving state of the vehicle. With this configuration, it is now possible to perform yaw control reliably and responsively, which was considered insufficient with four-wheel steering, etc., and improve the running of the vehicle when turning or going straight, including spin suppression and drift suppression. This has the advantage of ensuring stability.

The above-mentioned automobile is provided with a yaw behavior determining means for determining whether the yaw behavior of the vehicle body deviates from a stable state during driving, and the supply state setting means is configured to determine whether the yaw behavior of the vehicle body is determined by the yaw behavior determining means. When it is determined that the yaw behavior has deviated from a stable state, a moment of a predetermined magnitude is generated in a direction to correct this yaw behavior toward a stable side so that the braking force supply adjustment means supplies a braking force for yaw control. By setting the above-mentioned supply direction and supply amount so as to increase the amount of water, the above-mentioned effects can be reliably obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a schematic configuration of a braking device for an automobile as an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of essential parts of a braking system for an automobile as an embodiment of the present invention.

[Explanation of symbols]

1L Front left wheel 1R Front right wheel 4 Handle 13L Rear left wheel 13R Rear right wheel 15 ECU 15A Supply state setting means 16 Handle angle sensor 22 Brake pedal 22A as braking operation means
Master cylinder 23 Yaw rate sensor 27 Lateral G sensor 29 Vehicle speed sensor 32 Hydraulic pump 33 Accumulators 311 to 314 Hydraulic braking mechanism A Braking force supply adjustment means (hydraulic control valve)
B Automotive braking system LB Left wheel braking system RB Right wheel braking system

Claims (2)

[Claims] Claim 1: A braking system for an automobile, comprising a braking force generating means for generating a braking force, a left wheel braking mechanism for braking a left wheel of the automobile, and a right wheel braking mechanism for braking a right wheel of the automobile. and a braking force supply adjusting means capable of appropriately supplying the braking force from the braking force generating means to either the left wheel braking mechanism or the right wheel braking mechanism as a braking force for yaw control; A braking device for a motor vehicle, comprising a supply state setting means for setting a supply direction and a supply amount of a braking force for yaw control according to a running state of the vehicle. 2. The above-mentioned automobile is provided with yaw behavior determining means for determining whether the yaw behavior of the vehicle body deviates from a stable state during driving, and the supply state setting means is configured to control the yaw behavior of the vehicle body by the yaw behavior determining means. When it is determined that the yaw behavior deviates from the stable state, a moment of a predetermined magnitude is applied in the direction to correct the yaw behavior toward a stable state so that the braking force supply adjustment means supplies a braking force for yaw control. 2. A braking device for an automobile according to claim 1, wherein said supply direction and said supply amount are set so as to cause said braking device to generate said braking device.