JPH08258681A - Braking pressure distribution control device - Google Patents

Abstract

PURPOSE: To control the brake pressure in compliance with attitude change of a vehicle by furnishing a starting time control means which controls the starting time of a driving means on the basis of the change rate of the vehicle deceleration when it has exceeded the specified value. CONSTITUTION: A brake pressure distribution control processing is started in linkage with a driver's stepping-on of a brake pedal, and when a condition is generated such that the drive of a brake pressure distribution valve 5 is admitted according to the judging process, the control starting time set using a map according to the gradient of the deceleration is retarded until the set time on a control start timer has elapsed, and the drive of the valve 5 is postponed. When the vehicle 1 is in abrupt braking in cornering, the valve 5 is put in quick follow-up after stepping-on of the brake pedal, and at the time of gentle braking, the follow-up can be made in a lag from the stepping-on of the pedal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking pressure distribution control device for independently controlling the braking pressure of wheels before an anti-skid control device operates, and more particularly to traveling when a brake is operated during turning of a vehicle. The present invention relates to a braking pressure distribution control device that enhances stability.

[0002]

2. Description of the Related Art Conventionally, various types of anti-skid control devices have been widely known as a brake control device according to the prior art in order to improve a braking force of a vehicle. In particular, a braking pressure of front wheels and rear wheels is controlled. In the four-wheel anti-skid brake system, the front and rear wheels are prevented from locking together even during braking, so the spin due to the rear wheel lock is reliably prevented, and during braking during turning. Even if there is a cornering force, steering correction during braking is also possible, and high turning braking performance is obtained.

On the other hand, in such a four-wheel anti-skid brake device, braking is performed at a time of sudden braking that causes wheel lock or on a low μ road surface having a low friction coefficient between a tire and a road surface such as a snow road or a frozen road surface. Although it has a great effect on improving safety when riding, it does not operate during normal braking on high μ road surface where the friction coefficient between the road surface and the tire is relatively high, and the braking performance is exactly the same as the normal brake. It was

However, when the driver depresses the brake pedal during turning to perform braking, the braking force is not enough to cause wheel lock, that is, the tire is braked even when the anti-skid control is not operating. Occurs, and the cornering force is reduced by this slip. As a result, the balance of the gripping force between the front wheels and the rear wheels is lost, and as a result, the vehicle behavior in which the vehicle attitude changes to understeer or oversteer occurs, and the directional stability of the vehicle is disturbed from the neutral steer. Furthermore, if the steering angle is large or the speed is high, the behavior of the vehicle exceeding the limit of the steering correction ability of the driver occurs,
There is a problem that the driver's mistake cannot be completely covered.

Further, in order to solve this problem, as another conventional technique, there is a braking pressure distribution control device as shown in Japanese Patent Laid-Open No. 60-248466. This device is a speed sensor that detects an amount corresponding to the vehicle speed or the vehicle speed,
A steering angle sensor that detects a steering angle or an amount equivalent to the steering angle, a lateral motion sensor that detects a lateral motion state of the vehicle, a braking sensor that detects a braking state of the vehicle, and at least a front wheel and a rear wheel by an electric signal. When a braking state of the vehicle is detected by the braking pressure distribution valve that independently distributes the braking pressure of the wheels and the braking sensor, a predetermined steer characteristic is maintained based on the detection values of the speed sensor and the lateral motion sensor. And a control means for outputting a control signal of the braking pressure to the braking pressure distribution valve.

This braking pressure distribution control device automatically controls the braking force distribution of the front and rear wheels so as to maintain a predetermined lateral motion determined by the vehicle speed and steering angle during turning braking, for example, yaw rate.
Even if a braking operation is performed during turning, the driver does not behave in a manner that requires steering correction, and directional stability can be ensured during turning braking.

[0007]

In the braking pressure distribution control device according to the other prior art described above, when the vehicle is in the motion state for performing this control, when the brake pedal is depressed, the braking operation is performed. Accordingly, control is started. On the other hand, there is a time delay in the braking force in the vehicle from the depression of the brake pedal to the generation of the braking force on the tire, and further from the generation of the braking force to the change in the posture of the vehicle.

As a result, for example, when the driver performs a pumping brake or a sudden braking in which the brake pedal is intermittently depressed during turning, the braking pressure distribution control device performs the control following the depression of the brake pedal, and the actual control is performed. Control can be performed by following changes in the posture of the vehicle. Therefore, during pumping braking or sudden braking, this braking pressure distribution control device operates properly, but slow braking that does not affect running stability. Since the control operation is performed even at times, there is a problem that the drive feeling of the vehicle is deteriorated.

Further, since the braking pressure distribution valve operates in response to the depression of the brake pedal, the frequency of operation of the braking pressure distribution valve increases, which deteriorates the driver feeling due to vibration, noise, etc. There were problems such as shortening the life of the distribution valve.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a braking pressure distribution control device capable of controlling the braking pressure in response to changes in the attitude of the vehicle. There is.

[0011]

In order to solve the above-mentioned problems, the braking pressure distribution control device according to the invention of claim 1 uses at least a detection means for detecting the motion state of the vehicle and a detection signal from the detection means. The braking pressure distribution means for independently distributing the braking pressures of the front wheels and the rear wheels, the speed difference between the left wheel and the right wheel calculated by the signal from the detection means exceeds a predetermined speed difference, and the deceleration is reduced by a predetermined deceleration. A drive means for driving the braking pressure distribution means when the speed exceeds the speed, and a start time of the drive means based on a deceleration change rate when the deceleration of the vehicle exceeds a predetermined deceleration. It consists of start time control means.

[0012]

With the above structure, the start time control means sets the start time from the deceleration change rate when the deceleration of the vehicle exceeds a predetermined deceleration based on the detection signal from the detection means. However, since the drive means drives the braking pressure distribution means for independently distributing the braking pressure of at least the front wheels and the rear wheels after the lapse of time, the braking pressure distribution means is braked during turning braking of the vehicle during sudden braking. It is possible to operate quickly following the depression of the pedal, and during slow braking, it can be operated later than the depression of the brake pedal.

[0013]

Embodiments of the present invention will be described below with reference to FIGS.

In the figure, 1 is a vehicle, 2A, 2B, 2C and 2D.
Indicate tires, and the wheels 2A to 2D are attached to the vehicle 1 via a vehicle suspension device (none of which is shown) or the like. A brake mechanism such as a disc brake is provided near the wheels 2A to 2D. Further, the wheels 2A and 2B become the front wheels of the vehicle 1,
A and 2B are provided in a steering device (not shown).

3A, 3B, 3C and 3D are wheels 2A to 2D
The wheel cylinder which is located in the vicinity and constitutes a part of the brake mechanism provided on the vehicle 1 side is shown.

Further, the wheel cylinders 3A to 3D
Is a disc rotor attached to the wheels 2A to 2D side, a brake carrier fixed to the vehicle 1 side so as to sandwich the disc rotor, a brake caliper attached to the brake carrier, and the brake. A brake pad sandwiched between a caliper and the disc rotor; and a brake cylinder that is provided on the brake caliper and that generates a pressing force that presses the brake pad to sandwich the disc rotor when hydraulic pressure is supplied, and It consists of a piston.

Then, the wheel cylinders 3A to 3D
By independently supplying brake fluid from a master cylinder 4 which will be described later via a braking pressure distribution valve 5, this hydraulic pressure serves as a pressing force to the pistons, and the wheel cylinders 3A to 3C.
The brake pad D of FIG. 3 sandwiches the disc rotor, restrains the disc rotor, and applies braking force to the wheels 2A, 2B, 2C, 2D individually to brake the vehicle 1.

4 is an engine room of the vehicle 1 (not shown)
Shows a master cylinder that constitutes a brake mechanism together with the wheel cylinders 3A to 3D provided in a vehicle, etc., and the master cylinder 4 is a brake pedal (not shown) provided in a driver's cab and provided with a brake switch to be described later. When the driver depresses the brake pedal, the brake oil in the master cylinder 4 is supplied to the wheel cylinders 3A to 3D via the braking pressure distribution valve 5, respectively.

Reference numeral 5 denotes a braking pressure distribution valve as a braking pressure distribution means provided between the master cylinder 4 and the wheel cylinders 3A to 3D. The braking pressure distribution valve 5 is an electromagnetic four flow rate adjusting valve. The input side of the braking pressure distribution valve 5 and the master cylinder 4 are connected by a supply pipe 6, and the output side of the braking pressure distribution valve 5 and the wheel cylinders 3A to 3D are output pipes 7A to 7D. Each is connected.
Further, the braking pressure distribution valve 5 is adapted to individually control the braking pressure supplied from the master cylinder 4 to the wheel cylinders 3A to 3D by a signal from a controller 11 described later.

8A, 8B, 8C and 8D are wheels 2A to 2D
A wheel speed sensor as a detection means provided on the side of the vehicle 1 located in the vicinity is shown, and as the wheel speed sensors 8A to 8D, for example, an electromagnetic pickup type rotation detecting element or an optical detecting element is used. The detection signal is output to the controller 11.

Reference numeral 9 indicates a longitudinal acceleration sensor which constitutes a detecting means, and 10 indicates a lateral acceleration sensor which also constitutes a detecting means. The acceleration sensors 9 and 10 are constituted by, for example, a gyro sensor or the like. The acceleration and deceleration of the vehicle 1 are detected, and the lateral acceleration sensor 10 detects the lateral acceleration. Further, the acceleration sensors 9 and 10 are connected to the input side of the controller 11.

Reference numeral 11 denotes a controller. The controller 11 is composed of a microcomputer having a storage area 11A such as a ROM and a RAM, and a brake switch (not shown) and wheel speed sensors 8A to 8A are provided on its input side.
D, the longitudinal acceleration sensor 9 and the lateral acceleration sensor 10 are connected, and the braking pressure distribution valve 5 is connected to the output side. Further, the storage area 11A stores the braking pressure control program shown in FIG. 2, and the characteristic map 14 of the control start time T0 with respect to the inclination α of the deceleration d of FIG. 3 and a predetermined left and right speed difference. v0 and deceleration d0 are stored respectively. Further, the wheel speed sensors 8A to 8D and the acceleration sensor 9, which are input to the controller 11,
The motion state of the vehicle 1 is detected by calculating the detection signal from 10.

The braking pressure distribution control device in this embodiment is constructed as described above. Next, the operation will be described based on the braking pressure distribution control program of FIG. Thus, the brake switch that detects whether the brake pedal is in the operated state or the non-operated state is turned on by detecting that the brake pedal is in the operated state, and the processing is started.

First, in step 1, the front, rear, left, and right wheel speed sensors 8A to 8D are used to detect the respective wheels 2A to 2D.
Detects the wheel speed of.

In step 2, a predetermined calculation is performed from the wheel speeds to calculate the deceleration d.
Speed difference between right wheels (wheels 2A and 2B, wheels 2C and 2D) |
Calculate v | The calculation of the deceleration d and the speed difference | v | between the left and right wheels is generally well known and therefore omitted.

Further, in step 4, it is judged whether or not the vehicle 1 is in a turning state and the speed difference | v | is larger than a predetermined speed difference v0 for judging that the cornering force may collapse. When it is determined to be “YES” in 4, it is determined in step 5 whether or not the deceleration d is greater than a predetermined deceleration d0 requiring the braking pressure distribution control for the attitude control of the vehicle 1. If the determination is “NO” in step 4 or step 5, the process proceeds to step 6, the control start timer T described later is cleared, the flag is set to “1” in step 7, and step 15
Returned by. That is, in step 6, even if it is determined that the braking pressure distribution control is necessary by the processing of steps 1 to 5 before the previous time, the braking pressure distribution control is not necessary by the processing of steps 1 to 5 this time. If it is determined that the braking pressure distribution control set based on the processing of steps 1 to 5 before the previous time is canceled.

On the other hand, if "YES" is determined in step 5, the process proceeds to step 8, and this time it is determined in step 8 whether "flag = 1". If "YES", the above-mentioned steps are executed. This is the case when it is determined that the braking pressure distribution control is necessary for the first time in the processes of 1 to 5, and the control start time T0 is not set yet. Therefore, after starting the control start timer T in step 9, The control start time T0 is set by the processing from 10 onward.

That is, in step 10, as shown in FIG. 4, the rate of change when the deceleration d exceeds a predetermined deceleration d0, that is, the slope α, is calculated, and in step 11, it is preliminarily tested, simulated, or the like. The control start time T0 for the calculated inclination α shown in FIG.
Control time T0 from the inclination α calculated in step 10 based on the characteristic map 14 of the braking pressure distribution control execution start margin time (in consideration of the time delay until the posture change occurs).
The flag is set to "0" in step 12, and the process returns in step 15.

On the other hand, if "NO" is determined in step 8, it is determined that the braking pressure distribution control is already required in the processing of steps 1-5 before the previous time, and the processing of steps 1-5 of this time. However, since that state is continued, it moves to step 13, and in step 13, it is judged whether or not the control start timer T, which has been timed by the execution of step 9 before the previous time, has passed the control start time T0. , "NO", the control start timer T still has the control start time T0.
Since it has not passed, it returns in step 15,
If the determination is "YES", it means that the control start timer T has passed the control start time T0.
The braking pressure distribution valve 5 of No. 4 is driven, and the braking pressure of the wheel cylinders 3A to 3D is calculated by the braking pressure distribution valve 5 and the deceleration d calculated with the wheel speed detected in steps 1, 2 and 3 and the left and right wheels. The attitude of the vehicle 1 can be controlled by individually controlling the speed difference | v |.

Next, referring to FIG. 4, the movement of the vehicle 1 will be described in detail. When the vehicle 1 is now braking suddenly, the deceleration d becomes as shown by the characteristic line 15A, and the predetermined value set in step 10 is set. Rate of change when deceleration exceeds d0 (slope α)
Becomes a tangent line at the intersection of the characteristic line 15A and the predetermined deceleration d0 and becomes abrupt α1.

Then, in step 11, the control start time T0 is set from the map 14 of FIG. 3 based on this sudden α1, so the control start time T0 is short.

Further, the control start timer T, which was started in advance in step 13, waits until the short control start time T0 has elapsed, and in step 14, the braking pressure distribution valve 5 is driven. As a result, at the time of sudden deceleration, the braking pressure distribution control can be performed almost simultaneously with the depression of the brake pedal.

On the other hand, when the deceleration of the vehicle 1 is set to be abruptly decelerated, the deceleration d becomes like the characteristic line 15B, and the slope α when the deceleration d0 exceeds the predetermined deceleration d0 set at step 10 is the characteristic line. Α2 is a tangent line at the intersection of 15B and the predetermined deceleration d0.

Then, in step 11, the control start time T0 is set from this gradient α2, and in step 13, this time T
It waits until 0 has elapsed, and after this time has elapsed, the braking pressure distribution valve 5 is driven in step 14. As a result, the braking pressure distribution control can be performed with a slight delay from the depression of the brake pedal at the time of slightly sudden deceleration.

Further, the deceleration of the vehicle 1 becomes the characteristic line 15C during the slow braking, and in this case, the predetermined deceleration d is not exceeded. Therefore, it is determined as "NO" in step 5, and the braking pressure distribution control is not performed. It works.

However, in the braking pressure distribution control device according to this embodiment, the braking pressure distribution control process is started in association with the depression of the brake pedal by the driver, and steps 4, 5, 8 are performed.
When it is determined that the braking pressure distribution valve 5 is allowed to be driven by the determination process of, the control start time T0 set from the map 14 by the slope α of the deceleration d is made to wait until the control start timer T elapses. Since the driving of the braking pressure distribution valve 5 is delayed, the braking pressure distribution valve 5 is made to quickly follow the depression of the brake pedal during the sudden braking during the turning braking of the vehicle 1, and the brake pedal is delayed from the depression of the brake pedal during the slow braking. Can be followed. As a result, the wheels 2A to
The 2D braking force can be individually controlled, and the attitude control of the vehicle 1 can be effectively performed.

Further, even when the driver performs the pumping brake by intermittently stepping on the brake pedal at the time of turning, the braking pressure distribution control device according to the present embodiment has the following characteristic line 15B shown in FIG. Since the braking pressure distribution valve 5 is operated after the depression of the brake pedal, it is possible to follow the actual posture change of the vehicle 1.

Further, at the time of gentle braking where the deceleration d does not exceed the predetermined deceleration d0, the drive of the braking pressure distribution valve 5 can be regulated as shown by the characteristic line 15C in FIG. As a result, the operating frequency of the braking pressure distribution valve 5 can be reduced, the driver feeling can be prevented from deteriorating due to vibration, noise, etc., and the life of the braking pressure distribution valve 5 can be effectively extended.

Thus, in the braking pressure distribution control device according to the present embodiment, it is possible to suppress the understeer and the oversteer even during the braking during the turning to maintain the neutral steer, and to secure the directional stability during the turning braking. The safety can be significantly improved.

In the above embodiment, steps 4, 5 and 8 in FIG. 2 are specific examples of the driving means according to the present invention, and steps 6, 10, 11, 12, 13, and 14 are start time controlling means. This is a specific example.

In the above embodiment, the wheel speeds of the respective wheels 2A to 2D are detected by the front, rear, left and right wheel speed sensors 8A to 8D in step 1, but the present invention is not limited to this. However, the acceleration, deceleration, and lateral acceleration may be detected from the longitudinal acceleration sensor 9 and the lateral acceleration sensor 10, and the deceleration d and the speed difference | v | between the left wheel and the right wheel may be calculated from this.

Further, the braking pressure distribution valve 5 in the above embodiment is
Although the four wheels are adjusted independently, the present invention is not limited to this, and the front wheels and the rear wheels may be adjusted independently.

Further, the anti-skid control device described in the prior art is added to the braking pressure distribution control device according to the above-mentioned embodiment so that the anti-skid control device is operated when the wheels 2A to 2D approach the locked state. For example, the locked state of the wheels 2A to 2D can be suppressed, the vehicle attitude control during turning braking can be more reliably performed, the braking distance can be shortened, and danger can be safely avoided.

[0044]

As described above in detail, according to the present invention of claim 1, the start time is controlled based on the deceleration change rate when the deceleration of the vehicle exceeds the predetermined deceleration by the start time control means. The braking pressure distribution means for independently distributing at least the braking pressure of the front wheels and the rear wheels after the lapse of time is driven by the driving means. Therefore, during turning braking of the vehicle, the braking pressure distribution means should be provided during the sudden braking. It can be operated quickly following the depression of the brake pedal, and can be operated later than the depression of the brake pedal during gentle braking, and the vehicle's posture is suppressed from understeering and oversteering during turning braking to maintain neutral steering. Therefore, it is possible to secure the directional stability at the time of turning braking and significantly improve the traveling safety.

[Brief description of drawings]

FIG. 1 is a block diagram showing a braking pressure distribution control device according to an embodiment of the present invention.

FIG. 2 is a flow chart showing a braking pressure distribution control program.

FIG. 3 is a characteristic diagram showing characteristics of control start time T0 with respect to inclination α of deceleration d.

FIG. 4 is an explanatory diagram showing a deceleration d with respect to a stop distance.

[Explanation of symbols]

 3A, 3B, 3C, 3D wheel cylinder 4 master cylinder 5 braking pressure distribution valve (braking pressure distribution means) 8A, 8B, 8C, 8D wheel speed sensor 9 longitudinal acceleration sensor 10 lateral acceleration sensor 11 controller

Claims (1)

[Claims] 1. A detection means for detecting a motion state of a vehicle,
The braking pressure distributing means for independently distributing the braking pressures of at least the front wheels and the rear wheels on the basis of the detection signal from the detecting means and the speed difference between the left wheel and the right wheel calculated by the signal from the detecting means produce a predetermined speed difference. Drive means for driving the braking pressure distribution means when the deceleration exceeds the predetermined deceleration, and
A braking pressure distribution control device comprising: a start time control means for controlling a start time of the drive means based on a deceleration change rate when the deceleration of the vehicle exceeds a predetermined deceleration.