JPH01215657A - Brake liquid pressure control device for vehicle - Google Patents

Abstract

PURPOSE:To prevent the occurrence of spin of a vehicle by controlling so that the increasing rate of brake-liquid pressure for the wheels on the inner side with regard to the turning center is lower than that for the wheels on the outer side, when a brake pedal has been stepped in, in such a condition as the output of a turning detection means has exceeded a prescribed value. CONSTITUTION:When a brake pedal 1 is stepped in, the brake liquid from a master cylinder 2 is supplied to respective wheel cylinders 9a to 12a via pipings 6 to 8 and pressure-intensifying solenoid valves 13 to 16, so that a vehicle is braked. In this case, a lateral acceleration sensor 25 for detecting the lateral directional acceleration applied to the vehicle at the time of turning is provided, and when the detected value thereof exceeds a prescribed value, and also when the operation of the brake pedal 1 is detected by a brake switch 30, the pressure-intensifying solenoid valves for the wheels on the inner side with regard to the turning center are subjected to duty-control, in the condition that pressure-reducing solenoid valves 21 to 24 have been cut off. Thus, the increasing rate of brake-liquid pressure for the wheels on the inner side with regard to the turning center can be lowered than that for the wheels on the outer side to prevent the occurrence of spin of the vehicle.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a vehicle that maintains good turning performance by controlling the hydraulic pressure of brake fluid supplied to left and right wheels when braking while the vehicle is turning. The present invention relates to a brake fluid pressure control device for use in automobiles.

(Prior Art) Generally, when a brake pedal is depressed while a vehicle is turning, the braking force causes the vehicle to oversteer and tend to spin. In order to prevent the occurrence of spin due to this phenomenon, conventional methods have been used to prevent the vehicle from oversteering by lowering the braking force of the wheels on the inner side of the turning center during braking than the braking force of the wheels on the outer side of the turning center. A so-called anti-skid control device has been proposed to prevent this.

For example, Japanese Patent Application Laid-Open No. 57-144158 discloses a left and right hydraulic pressure control system that has a valve body in the middle of a brake pipe disposed between a mask cylinder and a rear wheel that moves directly in response to lateral acceleration caused by turning the vehicle. A device is provided so that the rate of increase in brake fluid pressure for the rear wheels on the inner side of the center of the turn is lower than the rate of increase in the brake fluid pressure for the rear wheels on the outer side of the center of the turn due to the movement of the valve body during turning. A brake system has been disclosed in which a difference is created between the brake fluid pressures of the left and right rear wheels.

(Problems to be Solved by the Invention) However, in the hydraulic pressure control device described in the above-mentioned Japanese Patent Application Laid-Open No. 57-144158, the valve body is controlled by the lateral acceleration acting on the vehicle as a left and right hydraulic pressure control device. Since a complicated valve mechanism is required to directly move the brake fluid to create a difference in brake fluid pressure supplied to the left and right rear wheels, it is difficult to manufacture the device, leading to an increase in cost.

In order to solve these problems, the applicant has developed a brake fluid pressure control device that independently controls the brake fluid pressure applied to the wheels via control valves provided corresponding to each wheel. Based on the output of a turning braking detection means provided at an arbitrary position, when the output exceeds a first predetermined value set in advance, the brake fluid pressure of the wheel on the inner side of the turning center is reduced, and then the output is reduced. a second value smaller than the first predetermined value;
A system has already been proposed in which the brake fluid pressure of the wheels on the outer side of the turning center is reduced until it becomes equal to the brake fluid pressure of the inner wheels when

According to such a brake fluid pressure control device, there is no need for a fluid pressure control device having a complicated valve mechanism, so there is an advantage that the overall configuration can be simplified and costs can be reduced. However, according to various experiments conducted by the present inventor, it has been found that this brake fluid pressure control device has the following points to be improved.

That is, in the above brake fluid pressure control device, when the output of the swing braking detection means exceeds the first predetermined value,
Since the brake fluid pressure of the wheels on the inner side of the turning center, which has already been increased, is reduced, there is a risk that the vehicle will spin before the pressure is reduced.

The present invention has been made in view of the above points, and an object of the present invention is to provide a brake fluid pressure control device for a vehicle that is appropriately configured to more reliably prevent the occurrence of vehicle spin during turning braking.

(Means for Solving the Problem) In order to achieve the above object, the present invention provides a vehicle brake in which the brake fluid pressure applied to the wheels is independently controlled via control valves provided corresponding to each wheel. The hydraulic control device includes: a turning detection means for detecting turning of the vehicle; a braking detection means for detecting actuation of a brake pedal; and an output of the turning detection means based on outputs of the turning detection means and the braking detection means. When the braking detection means detects the operation of the brake pedal in a state in which the brake pressure exceeds a predetermined value, the brake fluid pressure of the wheels on the inner side of the turning center is changed to the rate of increase in the brake fluid pressure of the wheels on the outer side of the turning center. control means for controlling the driving of the control valve so as to increase the pressure at a lower rate of increase than the control valve.

(Function) According to this configuration, when the braking detection means detects the operation of the brake pedal while the output of the turning detection means exceeds a predetermined value, the control means controls the brake fluid of the wheels on the inner side of the turning center. Since the rate of pressure rise is controlled to be lower than that of the outer wheels, a moment is generated around the center of gravity of the vehicle in the opposite direction to the direction that causes the vehicle to spin, which causes the This brings about the effect of reducing the moment that causes spin.

(Embodiment) FIG. 1 is a schematic diagram showing an embodiment of the present invention. A mask cylinder 2 is provided in conjunction with a brake pedal 1, and when the brake pedal 1 is depressed, brake fluid 4 in a reservoir tank 3 is released from a rear wheel liquid chamber 2a and a front wheel liquid chamber 2b in the mask cylinder 2, respectively. Right rear wheel 9, left rear wheel 10 via brake pipe 5.6.7°8
, each wheel cylinder 9a of the front right wheel 11 and the front left wheel 12,
ioa, lla, and 12a. In addition, a solenoid valve 13.14.15.16 for pressure increase is provided in the middle of each brake pipe 5.6.7.8, and these solenoid valves 13.14.15.1
6 and wheel cylinders 9a, 10a, lla, 1
2a, pipes 17.18.19.20 are branched to each brake pipe 5.6.7.8, and these pipes 1
7. 18. 19.20 is the solenoid valve for pressure reduction 21.22
．． It is connected to the reservoir tank 3 via 23 and 24. The solenoid valves 13.14.15.16 for pressure increase are normally in positions that allow the brake fluid 4 from the mask cylinder 2 to flow to all of the wheels as shown in the figure.
4.15.16 Solenoid 13a.

When electricity is applied to 14a, 15a, and 16a, each solenoid valve 13, 14, 15, 16 is switched to the left side in the figure by the action of the solenoid, and the flow of brake fluid 4 is cut off. On the other hand, the solenoid valves 21, 22, 23, 24 for pressure reduction are normally in positions that block the brake fluid 4 from the mask cylinder 2 as shown in the figure. ．． 22.23.24 solenoid 2
1a', 22a, 23a, 24a, each solenoid valve 21.22.2 is activated by the action of the solenoid.
3.24 is switched to the left side in the figure to allow the brake fluid 4 to flow toward the reservoir tank 3 side.

In this embodiment, a lateral acceleration sensor 2 is installed at an arbitrary position on the vehicle.
5 is provided to detect the lateral acceleration applied to the vehicle when the vehicle turns, and a brake switch 30 is provided to operate in conjunction with the operation of the brake pedal 1. Detects stepping. The outputs of the lateral acceleration sensor 25 and the brake switch 30 are respectively supplied to the controller 40, and based on these outputs, the controller 40 controls the pressure increase solenoid valves 13, 14, 15, 16 and the pressure decrease solenoid valves 21 and 21. 22.23.24 Control valve operation signal output line 51.52.53.54.55.5
6.57.58.

The basic operation of such a configuration is as follows.

That is, when the driver depresses the brake pedal 1 in the illustrated state, the pressure of the brake fluid 4 inside the front wheel fluid chamber 2a and the rear wheel fluid chamber 2b of the mask cylinder 2 increases, and the brake fluid 4 from the reservoir tank 3 increases. is brake pipe 5
．． 6.7.8 and solenoid valve for pressure increase 13.14.15.
16 to each of the four wheel cylinders 9a, 10a
, lla, and 12a to generate braking force at each wheel. At this time, the solenoid valve 21.22.23 for pressure reduction
．． 24 is blocked.

In addition, when lowering the hydraulic pressure of the brake fluid 4 applied to a particular wheel, the signal output line from the controller 40 shuts off the pressure increasing solenoid valve corresponding to the wheel whose hydraulic pressure is to be lowered, and at the same time The pressure reducing solenoid valve corresponding to the pressure solenoid valve is switched to the circulation side, and the brake fluid 4 in the brake pipe is made to flow to the reservoir tank 3 side for a certain period of time. By performing such an operation, it becomes possible to reduce only the brake fluid pressure of a specific wheel.

In this embodiment, the actuation of the brake pedal 1 is detected by the output of the brake switch 30 while the controller 40 detects that the detected value of the lateral acceleration sensor 25 exceeds a predetermined value set in advance. sometimes,
With the pressure reducing solenoid valves 21, 22, 23 and 24 being shut off, the pressure increasing solenoid valves corresponding to the wheels on the inner side of the turning center are duty-controlled by the controller 40 via the corresponding signal output lines. In this way, the brake fluid pressure applied to the wheels on the inside of the turning center will be increased intermittently, so the rate of increase will be the same as that of the wheels on the outside of the turning center where the brake fluid pressure is continuously increased. It will be lower than in the side wheels.

The operation of this embodiment will be further explained below with reference to FIGS. 2, 3, and 3.
This will be explained using FIG. FIG. 2 shows the relationship between braking force X and lateral force Y applied to the vehicle. Generally, it is known that there is a relationship between braking force X and lateral force Y such that when braking force X is reduced by zzF, lateral force Y increases by AF. Furthermore, when the brake pedal is depressed while the vehicle is turning, the braking force causes the vehicle to oversteer and tend to spin.

This state will be explained with reference to FIG. That is, vehicle 45
When the brake pedal is depressed during a left turn as shown by arrow A, a moment M is generated around the center of gravity 0, as shown by the broken line, which causes the vehicle to spin. In this case, the braking force applied to the left rear wheel 10 is FX+, and the lateral force is F. Here, the hydraulic pressure of the brake fluid 4 supplied to the wheel cylinder 10a (FIG. 1) of the left rear wheel lO is lower than the hydraulic pressure applied to the right rear wheel 9, and the braking force is applied to the right rear wheel 9. Assuming that AFX is lower than the power Fx, the lateral force applied to the left rear wheel 10 increases by AF compared to the lateral force Fy applied to the right rear wheel 9. Therefore, around the center of gravity 0 of the vehicle 45, there is a moment M1 shown by the solid line (that is, a moment shown by the broken line)
A moment is generated in a direction that cancels M, resulting in an effect of reducing the moment that causes spin due to braking.

FIG. 4 is a time chart showing the operation of this embodiment based on the above-mentioned effect, and the operation of each member corresponding to the reference numeral shown in FIG. 1 is plotted on the horizontal axis at each time t. +tl+
It is shown in correspondence with t2+ t3+.

Note that this example assumes that the braking force is applied while the vehicle 45 is turning left.

Graph ■ in the figure indicates the detected value G of the lateral acceleration sensor 25,
The graph ■ is the output signal of the brake switch 30, and the graphs ■, ■, and ■ are the output signals of the mask cylinder 2 and the right rear wheel 9, respectively.
Graph (2) shows the state of shutoff and flow of the pressure increasing solenoid valve 14 corresponding to the left rear wheel 10.

Vehicle 45 is at time 1. When a left turn is started at t, the detection value G of the lateral acceleration sensor 25 increases, and at time t.

A predetermined value G set in advance. exceed. During this left turn, when the brake pedal 1 is depressed at time t2, the brake fluid pressure in the mask cylinder 2 begins to rise.
As a result, the brake fluid pressure in the wheel cylinder 9a of the right rear wheel 9 also increases.

On the other hand, the brake fluid pressure in the wheel cylinder 10a of the left rear wheel 10 on the inner side of the turning center is a predetermined value G, which is set in advance by the detected value G of the lateral acceleration sensor 25 in the controller 40. is detected, the output of the brake switch 30 causes the brake pedal 1 to
is detected to be stepped on, that is, time t
After 2, the solenoid 14a of the pressure increasing solenoid valve 14 corresponding to the left rear wheel 1O is duty-controlled by the controller 40 via the signal output line 52, so that the brake fluid pressure in the wheel cylinder 9a of the right rear wheel 9 is lower than that of the brake fluid pressure in the wheel cylinder 9a of the right rear wheel 9. The pressure will be increased with a delay and at a lower rate of increase.

That is, the solenoid 14a of the pressure increasing electromagnetic valve 14 corresponding to the left rear wheel 10 is turned ON at time t2, and the electromagnetic valve 14 is in a cut-off state for a predetermined time τ. , the solenoid valve 14 is turned off at time t3, and the solenoid valve 14 enters the flow state. After that, the predetermined time τ. At time t, when FP has elapsed, it is turned ON again and the above operation is repeated. Therefore, the brake fluid pressure in the wheel cylinder 10a of the left rear wheel lO is at the time t2 when the brake pedal 1 is depressed.
for a predetermined time τ. There is no change until time t, when , has passed, and then time t3, when the solenoid 14a is turned off.
and t.

After the hydraulic pressure P1 is maintained for a period (τ., I) during which the solenoid 14a is ON from time t4 to t, the solenoid 14a is
is turned OFF again between time t and t6 (τOFF>
The pressure is increased from P to P2, and the pressure increase is intermittent, so the pressure is increased later than in the mask cylinder 2 and the wheel cylinder 9a of the right rear wheel 9, and at a lower rate of increase. That will happen.

In this way, if the brake fluid pressure for the left rear wheel 10 on the inside side of the turning center is increased later than the brake fluid pressure on the right rear wheel 9 on the outside side of the turning center, and at a lower rate of increase, A difference occurs between the brake fluid pressures of the right rear wheel 9 and the left rear wheel 10, and the braking force Fx of the left rear wheel 10 is greater than the braking force Fx of the right rear wheel 9 by an amount corresponding to the difference in brake fluid pressure between the two (AFx ) decreases, and the left rear wheel 10 corresponds to the decrease in AFX.
The lateral force Fy of the vehicle 45 increases AFy more than that of the right rear wheel 9, thereby canceling the moment )M shown by the solid line around the center of gravity 0 of the vehicle 45, that is, the moment )M shown by the broken line. A moment is generated, making it possible to reduce the moment that causes spin due to braking.

Although only the control of the brake fluid pressure of the left rear wheel IO and the right rear wheel 9 has been described above, similar control can be performed not only for the left and right rear wheels but also for the right front wheel 11 and the left front wheel 12 as necessary. Can be done.

Note that this invention is not limited only to the embodiments described above, and numerous modifications and changes are possible. For example, in the above-described embodiment, the turning of the vehicle is detected by the lateral acceleration sensor 25, but it is also possible to detect the turning of the vehicle from the wheel loads. Furthermore, in the above-described embodiment, the cut-off period (τ.) and the flow period (τ.FF) of the pressure increasing solenoid valve by duty control were kept constant, but as shown in FIG. 5, the cut-off period τ. It is also possible to make the duty ratio variable so that , is proportional to G (the strength of turning and the magnitude of moment). In this way, by controlling the increase rate of the brake fluid pressure of the wheels on the inner side of the turning center in accordance with the strength of the turning, it is possible to further improve the stability of the vehicle during turning braking.

(Effects of the Invention) As described above, according to the present invention, brake fluid pressure control for a vehicle is performed in which brake fluid pressure applied to wheels is independently controlled via control valves provided corresponding to each wheel. In the device, when the brake pedal is depressed with the output of the turning detection means exceeding a predetermined value, the rate of increase in the brake fluid pressure of the wheels on the inner side of the turning center increases as the brake fluid pressure of the wheels on the outer side of the turning center increases. Since the rate of increase in hydraulic pressure is controlled to be lower than the rate of increase in brake fluid pressure, it is possible to more reliably prevent the occurrence of vehicle spin during corner braking, compared to reducing the brake fluid pressure once increased during corner braking. It can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing the relationship between the braking force applied to the vehicle and the lateral force, and Fig. 3 is a diagram showing the relationship between the braking force and the lateral force on the vehicle. A schematic diagram showing an actual example, FIG. 4 is a time chart showing the operation of the embodiment shown in FIG. 1, and FIG. FIG. ■...Brake pedal 2...Mask cylinder 3
... Reservoir tank ' 5, 6.7.8 ... Brake pipe 9 ... Right rear wheel 10 ... Left rear wheel 11 ...
・Right front wheel 12...Left front wheel 13, 14.1
5.16...Solenoid valve for pressure increase 21, 22.23.24.
... Solenoid valve for pressure reduction 25 ... Lateral acceleration sensor 30.
... Brake switch 40 ... Controller patent applicant Nissan Motor Co., Ltd. Fig. 1 Fig. 2 Y Fig. 3 Copy of Sefj -

Claims (1)

[Claims] 1. In a brake fluid pressure control device for a vehicle that independently controls brake fluid pressure applied to wheels via control valves provided corresponding to each wheel, a turning of the vehicle is detected. a turning detection means for detecting operation of a brake pedal; a braking detection means for detecting operation of a brake pedal; When the means detects the operation of the brake pedal, the brake fluid pressure of the wheels on the inner side of the turning center is increased at a lower rate of increase than the increase rate of the brake fluid pressure of the wheels on the outer side of the turning center. 1. A vehicle brake fluid pressure control device comprising: control means for controlling driving of a control valve.