JPH02249748A - Brake fluid pressure control device for vehicle - Google Patents

Abstract

PURPOSE:To reduce spin moment of a wheel by limiting a brake fluid pressure so as to te generated lower in a wheel in the turning center inner side than that in a wheel in the turning center outer side, when a detection value of a vehicle in its turning condition is in not less than a predetermined value. CONSTITUTION:Solenoid valves 13, 14, which are energized to interrupt circulation of brake fluid, are provided in a halfway part of rear wheel brake pipes 5, 6 and controlled by a controller 20. The controller 20 inputs output signals of a lateral acceleration sensor 15 serving as a turn detecting means and a longitudinal acceleration sensor 16 serving as a braking condition detecting sensor. When the lateral acceleration sensor 15 increases its detection value to not less than a predetermined value, a pressure of brake fluid is limited lower in a wheel in the turn center inner side than a pressure of brake fluid in a wheel in the turn center outer side. When the longitudinal acceleration sensor 16 generates its output reaching a predetermined value or more the brake fluid pressure is controlled so as to be released from its restriction for the wheel in the turn center inner side.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a vehicle brake fluid that maintains good cornering performance by controlling the hydraulic pressure of the brake fluid supplied to left and right wheels during braking while the vehicle is turning. This invention relates to a pressure control device.

2. Description of the Related Art Generally, when a vehicle is braking while turning, the braking force tends to cause the vehicle to oversteer and spin. Therefore, a so-called anti-skid control device is used to apply the optimum braking force without locking the wheels. As is known, this type of control device reduces the braking force applied to the wheels on the inside side of the turning center to be lower than the braking force applied to the wheels on the outside side of the turning center during braking, thereby controlling the tire and road surface. A common method is to increase the frictional force between the wheels and prevent the vehicle from oversteering. As an example of the above means,
For example, in Japanese Patent Application Laid-open No. 57-14.4158, a braking fluid pressure increase rate for the rear wheel on the inner side of the turning center is set in the middle part of the brake pipe disposed between the mask cylinder and the rear wheel.
A left and right hydraulic pressure control device is provided to increase the braking hydraulic pressure to a rate lower than that of the rear wheels on the outside of the turning center, and the left and right hydraulic pressure is controlled based on the movement of a weight body in response to lateral acceleration applied to the vehicle body. An example of a configuration is disclosed in which a control device is operated to create a difference in brake fluid pressure between left and right wheels during braking during a turn.

Generally, when braking, the load on the rear wheels decreases compared to the load on the front wheels, and the rear wheels tend to lock up more easily.
In order to match the front and rear distribution ratios of vehicle weight and braking force, a proboscising valve is usually placed in the middle of the brake pipe leading to the rear wheels. This provisioning valve is designed to reduce the subsequent rate of increase in rear wheel hydraulic pressure by a constant ratio relative to the front wheels when the brake hydraulic pressure reaches a certain hydraulic pressure that is the activation starting point.

Furthermore, a separate hydraulic pressure control valve is provided, and the brake hydraulic pressure applied to the wheels is appropriately controlled by opening and closing the control valve using the movement of the suspension arm during turning, etc.
Examples of devices are also known that prevent spins during vehicle braking.

Problems to be Solved by the Invention However, such conventional brake fluid pressure control devices,
Particularly, in the example of the device described in Japanese Unexamined Patent Publication No. 57-144158, by detecting the lateral acceleration applied to the vehicle, that is, the turning state of the vehicle, the braking fluid pressure to the rear wheels on the inner side of the turning center is determined. Since the rate of increase is controlled to be lower than the rate of increase in brake fluid pressure for the rear wheels on the outside of the center of the turn, it is possible to prevent the vehicle from spinning during gentle braking, but on the other hand, when braking suddenly, the vehicle body may move laterally. There is a problem in that the so-called drift moment that is swept away by the vehicle becomes large, and the behavior of the vehicle tends to become unstable. Furthermore, since the rate of increase in brake fluid pressure is kept low compared to normal braking, the deceleration required during sudden braking is reduced, and there is also the problem that sudden braking may not be effective. There is.

Therefore, the present invention solves the problems that conventional vehicle brake fluid pressure control devices have, and can reduce both the spin moment and drift moment of the wheels during turning braking, and can also perform sudden braking in an emergency. The purpose is to provide a device that can be operated.

Means for Solving the Problems In order to achieve the above object, the present invention provides a turning state detection system for detecting a turning state of a vehicle in a vehicle brake fluid pressure control device that independently controls brake fluid pressure applied to wheels. means, a braking state detecting means for detecting a braking state of the vehicle, and when the detection value of the turning state detecting means is equal to or greater than a predetermined value, the brake fluid pressure of the wheels on the inner side of the turning center is lowered to that of the wheels on the outer side of the turning center. control means that limits the brake fluid pressure to be lower than the brake fluid pressure, and releases the brake fluid pressure restriction for the wheels on the inner side of the turning center when the detected value of the braking state detection means reaches a predetermined value or more; It has a configuration with

According to this configuration, when the driver depresses the brake pedal while the automobile is turning in either the left or right direction, when the detection value of the turning state detection means reaches a predetermined value, the control performed by the controller etc. A signal is output from the means to limit the brake fluid pressure of the wheels on the inside of the turning center to be lower than the brake fluid pressure of the wheels on the outside of the turning center, and as a result, the spin moment of the wheels is suppressed to a low level. .

On the other hand, when the detection value of the braking state detection means reaches a predetermined value or more, the control means outputs a signal to cancel the restriction on the wheels located on the inner side of the turning center, and the same brake is applied to the left and right wheels. Hydraulic pressure is applied and the vehicle returns to normal braking. As a result, the drift moment of the wheels can be suppressed to a low level, and sudden braking is possible.

Embodiment Hereinafter, one embodiment of the vehicle brake fluid pressure control device according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a general diagram showing the present invention, in which 1 is a brake pedal, and 2 is a brake pedal 1.
The brake fluid 4 in the reservoir tank 3 is transferred to the rear wheel fluid chamber 2a in the mask cylinder 2.
and brake pipes 5 from the front wheel fluid chamber 2b. 6.
7. '8 via right rear wheel 9. Left rear wheel 10. Each wheel cylinder 9a, 10a of the right front wheel II, the left front wheel 12,
Ila, 12a. Further, a blow-shinning valve 30 is provided between the rear wheel liquid chamber 2a and the brake vibrators 5, 6 to reduce the liquid pressure generated by the mask cylinder 2 at a predetermined ratio.

A solenoid valve 13, 14, which is a two-position valve, is installed in the middle of the brake vibrator 5, 6 for the rear wheels. The above-mentioned solenoid valves 13.14 are normally located at positions where the brake fluid 4 from the mask cylinder 2 flows to the rear wheels 9, 10 as shown in the figure, and the solenoid 13a of the solenoid valves 13.14
, 14a, the solenoids 13a, 14a are energized.
Each solenoid valve 13, 14 is switched by the action of
The flow of brake fluid 4 is cut off.

Reference numeral 15 denotes a lateral acceleration sensor as a turning detection means for detecting turning of the vehicle, and this lateral acceleration sensor 15 detects the magnitude of lateral acceleration applied to the vehicle body when the vehicle turns.

Reference numeral 16 denotes a longitudinal acceleration sensor as means for detecting the braking state of the vehicle, and this longitudinal acceleration sensor 16 detects the magnitude of acceleration applied to the longitudinal direction of the vehicle body during braking.

Reference numeral 20 denotes a controller as a control means, and upon receiving detection signals from the lateral acceleration sensor 15 and the longitudinal acceleration sensor 16, the controller 20 controls the electromagnetic valves 13 and 14.
The open/close state of the switch is controlled by signal output lines 21 and 22.

The basic operation of the device of the present invention with such a configuration is as follows. That is, when the driver depresses the brake pedal 1 from the illustrated state, the pressure of the brake fluid 4 inside the rear wheel fluid chamber 2a and the front wheel fluid chamber 2b of the mask cylinder 2 increases, causing the brake fluid from the reservoir tank 3 to increase. 4 is supplied to each of the four wheel cylinders 9a, lOa, , lla, and 12a via brake vibrators 5, 6, 7°8 and electromagnetic valves 13, 14, and braking force is generated at each wheel. At this time, rear wheel 9
, a solenoid valve 1 provided in the brake vibrators 5 and 6 on the to side.
3.14 remains open.

Next, assume that the driver depresses the brake pedal 1 while the vehicle is turning at high speed. Then, when the detected value of the lateral acceleration sensor 15 as a turning state detection means exceeds a predetermined value, the controller 20 activates the solenoids 13a, 14a.
A signal is transmitted to the solenoid on the rear wheel side, which is located inward of the turning center, and this solenoid is switched to the closing side. Therefore, during gentle braking, the brake fluid pressure of the rear wheels on the inner side of the turning center is limited to be lower than the brake fluid pressure of the wheels on the outer side of the turning center, and the spin moment of the rear wheels is suppressed to a low level. Figure 2 shows the braking force X and lateral force Y applied to the car.
It is generally known that when the braking force X is reduced by 8Fx as shown in the figure, the lateral force Y increases by ΔFF. FIG. 3 shows a state in which a spin moment is generated by the braking force when the brake pedal is depressed while the automobile is turning. That is, when the play pedal is depressed while the vehicle body 45 is turning to the left as shown by arrow A, a moment M is generated around the center of gravity 0 as shown by a broken line. In this case, the braking force applied to the left rear wheel 10 is FXI F
The force in the it direction is PY, but if the hydraulic pressure of the brake fluid 4 supplied to the wheel cylinder 10a (FIG. 1) of the left rear wheel 10 is lowered and the braking force Px is reduced by ΔFK,
The lateral force py increases by ΔFY. Therefore, around the center of gravity O of the vehicle body 45, a moment is generated in a direction that cancels the moment Ml shown by the solid line, that is, the moment M shown by the broken line, and reduces the moment that causes spin due to braking. be able to.

On the other hand, during the above operation, when the detected value of the longitudinal acceleration sensor 16 as a braking state detection means reaches a predetermined value or more,
A signal for switching the solenoid to the release side again is transmitted from the controller 20 to the solenoid that has been switched to the closing side, and the restriction on the rear wheel on the inner side of the turning center is released. Therefore, the same brake fluid pressure is supplied to the rear wheels 9 and 10, and the vehicle returns to its normal braking state.

The behavior of such a vehicle will be explained based on the graphs of FIGS. 4 and 5. Each of the graphs shows the relationship between the vehicle's yawing moment and deceleration, and ■ in Figure 4 is for a vehicle equipped with a normal blown-portioning valve; In the braking region, the spin moment becomes large and the vehicle tends to spin (and conversely, in the region where the deceleration is large, that is, in the sudden braking region, the drift moment becomes large. Note that line H and line L indicates the limit values of the spin moment and drift moment, respectively, and the inside of both H and L is the stable area.Also, the point P
is the maximum braking acceleration that the vehicle can generate (IG =
It shows 9.8m/S.

Graph ■ in the figure shows the case where the brake fluid pressure of the rear wheel on the inside side of the center of the turn is lowered as described above in order to prevent spin in the slow braking region during such a high-speed turn.
According to this graph (2), it can be seen that while the spin moment decreases in the slow braking region, the drift moment increases in the sudden braking region, and the maximum braking acceleration does not reach IG.

On the other hand, the graph (■) shown in FIG. 5 shows the behavior of the vehicle when the present invention is applied. While the spin moment of the vehicle is reduced, the drift moment in the sudden braking region is also reduced, and the vehicle is always within the stability region indicated by the lines H and L. Furthermore, since the maximum braking acceleration IG (point P) that an ordinary driver can apply during braking has been reached, the effect of sudden braking is obtained.

The operation of the present invention will be explained in more detail based on the time chart of FIG.

That is, the driver at time t while the vehicle is running. Assume that the steering wheel is turned to the left or right. Then, the lateral acceleration of the vehicle gradually increases and reaches a predetermined value Y1o at time t1. In this example, the above Y t
o is set to 0.6G.

Next, time 1. When the lateral acceleration sensor 15 detects that the lateral acceleration has reached a predetermined value Y1°, and this detection signal is input to the controller 20, the controller 20 outputs a control signal Q, and the electromagnetic valve 13 .14, only the solenoid valve of the rear wheel on the inner side of the turning center is closed. However, at this time, the brake pedal 1 is not depressed by the driver, so no braking force is applied to the vehicle. Furthermore, as shown in graph C, yaw rate also occurs by a predetermined amount.

Next, when the driver depresses the brake at time t, this depressing force causes the brake fluid pressure in the mask cylinder 2 to become zero.
From P. This brake fluid pressure P. is reduced by the blow-off conning valve 30, so that hydraulic pressure from O to P is supplied to the wheel cylinder of the rear wheel on the outer side of the turning center as shown in a. At this time, the solenoid valve of the rear wheel on the inner side of the turning center is closed, so no brake fluid pressure is supplied to the rear wheel on the inner side of the turning center. Therefore, based on the above-described operating principle, the spin moment of the vehicle during slow braking is reduced.

When braking force is applied to the vehicle in this way, the longitudinal acceleration of the vehicle changes, but the longitudinal acceleration sensor 16 detects that the longitudinal acceleration has reached a predetermined value X go at time t. , this detection signal is input to the controller 20. Then, the controller 20 outputs the control signal Q.
A signal to turn off is output, and accordingly, the solenoid valve of the rear wheel on the inside side of the turning center is released among the solenoid valves 13 and 14, and the solenoid valve of the rear wheel on the inside side of the turning center is opened. The brake fluid pressure shown in b is supplied. Therefore, the same brake fluid pressure is supplied to the left and right rear wheels 9, 10,
The vehicle returns to normal braking. In the case of this example, the above X.

is set to 0.5G.

In this way, the yaw rate gradually approaches zero from time t, as shown in graph C', and braking ends at time t.

Now, for comparison with the effect of the present invention described above, if the acceleration in the longitudinal direction is set to a predetermined value X1. The dashed line in the figure shows the change in yaw rate when the energization to the rear wheels on the inside side of the turning center is continued even when the yaw rate is exceeded, and the energization to the solenoid valve is stopped only when the lateral acceleration falls below the predetermined value Y1°. Denoted by C'. In this case, it is observed that the yaw rate changes greatly toward the drift side at time t.

Therefore, it is clear that if the energization of the solenoid valves of the rear wheels 9 and 10 is controlled only based on the factor of lateral acceleration, it is not possible to prevent the vehicle from rapidly drifting.

In this embodiment, [11] is used as the vehicle braking state detection means.
Although the rear acceleration sensor 16 is used, the braking state can also be detected from a change in brake fluid pressure or the depression force on the brake pedal l instead of the front (multiphase speed sensor 15).Furthermore, the anti-skid In the case of a vehicle equipped with a traction control system, the solenoid valves provided in these devices can be replaced by the solenoid valves 13 and 14 in the above embodiments.

Effects of the Invention As explained in detail above, the vehicle brake fluid pressure control device according to the present invention independently controls the brake fluid pressure applied to the wheels, and detects the turning state of the vehicle. a turning state detection means for detecting the braking state of the vehicle; a braking state detection means for detecting the braking state of the vehicle; The brake fluid pressure is limited to be lower than the brake fluid pressure of the wheels on the outside side, and when the detected value of the braking state detection means reaches a predetermined value or more, the brake fluid pressure on the wheels on the inside side of the turning center is Since the configuration includes a control means for canceling the pressure restriction, the following effects are brought about. That is, when the vehicle is braking for a turn, the turning state detection means detects this, and when the detection value of the turning detection means reaches a predetermined value, the control means determines that the brake fluid pressure of the wheel on the inner side of the turning center is outside the turning center. Since a signal is output that limits the brake fluid pressure to be lower than the brake fluid pressure of the wheel on the other side, the spin moment of the wheel can be lowered.

Furthermore, when the detection value of the braking state detection means reaches a predetermined value or more during the above operation, a signal is output from the control means to cancel the restriction on the wheels on the inner side of the turning center. The same brake fluid pressure is supplied to the left and right small wheels, and the vehicle returns to normal braking, keeping the drift moment of the wheels low and stabilizing the vehicle's behavior, as well as providing sudden braking required in an emergency. The effect is that the operation becomes possible.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an embodiment of the vehicle brake fluid pressure control device according to the present invention, Fig. 2 is a graph showing the relationship between braking force and lateral force applied to a car, and Fig. 3 is a graph showing the relationship between braking force and lateral force applied to a car. Schematic diagrams illustrating practical examples of braking and lateral forces, Figures 4 and 5
The figure shows the yawing moment of the conventional vehicle and the vehicle of the present invention!・
FIG. 6 is a graph showing the relationship between speed and deceleration, and FIG. 6 is a time chart showing an example of the operation of the present invention. l...brake pedal, 2...mask cylinder, 3...
・・Reservoir tank s 5+ 6r L 8・・
・Brake vibration, 9... Right rear wheel, 10... Left rear wheel, 11... Right front wheel, 12... Left front wheel, 13.14... Solenoid valve, 15... Lateral acceleration sensor, 1
G...Longitudinal acceleration sensor, 20...Hmph!・Roller, Figure 2 Figure 3

Claims (1)

[Claims] (1) A vehicle brake fluid pressure control device that independently controls the brake fluid pressure applied to the wheels, including a turning state detection means for detecting a turning state of the vehicle, a braking state detection means for detecting a braking state of the vehicle, When the detection value of the turning state detection means is equal to or higher than a predetermined value, the brake fluid pressure of the wheels on the inside side of the turning center is limited to be lower than the brake fluid pressure of the wheels on the outside side of the turning center, and the above-mentioned braking is A brake fluid pressure control device for a vehicle, comprising a control means for releasing the brake fluid pressure restriction for the wheels on the inner side of the turning center when the detected value of the state detection means reaches a predetermined value or more. .