JPS63269767A - Antiskid control device - Google Patents

Abstract

PURPOSE:To early eliminate the hydro-planing in the case that a reduced brake fluid pressure condition is maintained for a predetermined time under antiskid control by temporarily stopping such a pressure reducing control and locking a wheel. CONSTITUTION:A control unit 9 receiving output signals from a brake fluid pressure sensor 6, a wheel speed sensor 7 and a braking switch 8 calculates a slip rate of a wheel 4 according to a rotational speed of the wheel 4. Then, the control unit 9 controls an actuator 5 according to the slip rate to reduce a brake fluid pressure. When a reduced brake fluid pressure condition is maintained for a predetermined time under antiskid control where the brake fluid pressure is controlled, it is assumed that hydro-planing occurs at the wheel 4, and the brake fluid pressure is temporarily increased to lock the wheel 4. Accordingly, a water screen between the wheel 4 and a road surface is eliminated to thereby reduce a braking distance.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an anti-skid braking device that controls braking.

(Prior Art) This type of anti-skid braking device generally includes a wheel speed detector that detects the rotational speed of each wheel, and a wheel speed detector, as shown in, for example, Japanese Patent Application Laid-Open No. 80-35650. The system is equipped with a control unit that calculates the slip rate of the wheels based on the output signal from the device, determines whether the brakes will be locked based on this slip rate, and controls the brake fluid pressure, and the control unit locks the brakes. It prevents you from falling into a situation.

(Problem to be Solved by the Invention) By the way, the above-mentioned device lowers the brake fluid pressure to a predetermined pressure by operating the anti-skid braking device, for example, when the vehicle is running at high speed and the wheels are about to lock due to brake operation. The system attempts to restore wheel speed by holding or reducing the pressure.

However, at this time, if a so-called hydroplane phenomenon occurs in which a water film forms between the tire and the road surface, and the coefficient of friction between the tire and the road surface is extremely reduced, the rotational force transmitted from the road surface to the tire also decreases. Even though the brake fluid pressure is reduced by the anti-skid braking device, it takes time to recover the wheel speed or the wheel speed does not recover as shown by the X area in FIG. Until the wheel speed recovers to the set value due to removal of a water film between the tires and the road surface, the brake fluid pressure is kept in a reduced state by the anti-skid braking device, and therefore the vehicle as a whole The problem is that the braking distance becomes longer.

The present invention was developed in view of the above-mentioned circumstances, and its purpose is to instantly stop the wheels when the wheels are in a hydroplane phenomenon when the anti-skid braking device is controlling the brake fluid pressure. To provide an anti-skid braking device capable of shortening a braking distance of a vehicle by eliminating a water film between a tire and a road surface by setting the device in a locked state.

(Means for Solving the Problems) The present invention includes a wheel speed detector (7) that detects the rotational speed of the wheel (4), and a wheel speed detector (7) that detects the rotational speed of the wheel (4) based on the output signal from this detector (7). In an anti-skid braking device comprising a control unit (9) that calculates a slip ratio, maintains brake hydraulic pressure at a predetermined hydraulic pressure, and reduces the pressure with respect to this predetermined hydraulic pressure, the control unit (9)
) temporarily stops the pressure reduction control of the brake fluid pressure and locks the wheels if the brake fluid pressure is maintained in a reduced pressure state for a predetermined period of time during an anti-skid operation that controls the brake fluid pressure. It is characterized by comprising a hydraulic pressure changing means for changing the brake hydraulic pressure.

(Function) According to the present invention, when the brake fluid pressure is controlled by the anti-skid braking device, the wheel (4) falls into a hydroplane phenomenon, and the reduction of the brake fluid pressure by the anti-skid braking device continues for a predetermined time or more. When the brake fluid pressure is temporarily increased by the controller (9), the wheels (4) are momentarily locked and the water film between the tires and the road surface is eliminated, so that Brake control by the anti-skid braking device is normally performed without being adversely affected by the hydroplane phenomenon.

(Embodiments) The anti-skid braking device according to the present invention will be described below according to embodiments shown in the drawings.

Fig. 1 schematically shows a brake mechanism incorporating an anti-skid braking device according to the present invention, in which a master cylinder (2) is interlocked and connected to a brake pedal (1), and a hydraulic pressure extending from the master cylinder (2) is connected to the brake pedal (1). Pipeline (3
) is connected to the wheel cylinder (40) of a brake device incorporated in the wheel (4), and when the brake pedal (1) is depressed, the piston (not shown) of the master cylinder (2) is pressurized. Brake fluid is supplied to the wheel cylinder (40) to brake the wheel (4).

In the above brake mechanism, an actuator (5) is provided in the middle of the hydraulic pipe (3) for adjusting the pressure of the brake fluid at a predetermined level or reducing the pressure.
), and the actuator (5) and the wheel cylinder (40) in the hydraulic conduit (3).
A fluid pressure detector (6) for detecting brake fluid pressure is interposed between the brake fluid pressure and the brake fluid pressure.

Further, the wheel (4) is provided with a wheel speed detector (7) of, for example, an electromagnetic pickup type for detecting the rotational speed of the wheel (4), while the brake pedal (1) is provided with a wheel speed detector (7) for detecting the rotational speed of the wheel (4). A braking switch (8) is provided that detects the depression operation of 1) and outputs an on signal.

(9) is a control unit comprising a computer that controls the actuator (5) based on output signals from the vehicle speed detector (7), the hydraulic pressure detector (6), and the braking switch (8); , this control unit (9) controls the wheels (4) based on the output signal from the wheel speed detector (7) with the output signal from the braking detector (8) accompanying the depression of the brake pedal (1). ), determine the locked state of the brake from this slip ratio, and control the actuator (5) when it is determined that the brake is in the locked state,
The brake fluid pressure is maintained at a predetermined pressure or reduced.

In the above anti-skid braking device, the actuator (5) of the present invention is controlled by the control unit (9) as shown in the flowchart of FIG.

That is, as shown in FIG. 2, first, in step (11), the presence or absence of an on signal from the braking detector (8),
That is, it is determined whether or not braking is being performed by depressing the brake pedal (1), and if the ON signal is not output, the process returns to the original state, whereas if the ON signal is output, the process returns to step (12). Calculate the slip rate of the wheel (4).

This slip rate is calculated according to the flowchart shown in FIG. 3, and is calculated by calculating the control reference speed and the deceleration of the vehicle based on the wheel speed detected by the wheel speed detector (7). , from these arcs the wheels (4
) is calculated.

Then, based on the slip rate of the wheels (4) calculated in step (12), the data is stored in advance in the storage device of the control unit (9) and arithmetic processing is performed using the data.
In step 13), it is determined whether the wheels (4) are in a locked state or not.

If it is determined that the wheel (4) is in a locked state, the actuator (5) is activated in step (14).
It outputs a hydraulic pressure holding signal that maintains the brake hydraulic pressure to the wheel cylinder (40) at a set pressure.

Then, in step (15), the slip rate of the wheel (4) is calculated again, and based on the calculated slip rate, in step (16), it is determined whether the wheel speed has recovered to the set value or more, and the set value is determined. If the brake fluid pressure has recovered to the set pressure or higher, the process moves to step (19) and outputs a fluid pressure pressurization signal to the actuator (5) to increase the brake fluid pressure to the wheel cylinder (40) to the set pressure or higher. On the other hand, if the brake fluid pressure is still below the set pressure, a fluid pressure reduction signal is output to the actuator (5) to further reduce the brake fluid pressure to the wheel cylinder (40) below the set pressure.

After outputting the hydraulic pressure reduction signal, it is determined again in step (18) whether the wheel speed has recovered to the set value or higher.
If the wheel speed has recovered to the set value or higher, in step (19), a hydraulic pressure increase signal is sent to the actuator (5) to increase the brake fluid pressure to the wheel cylinder (40) to a level higher than the set pressure. On the other hand, if the wheel speed has not yet recovered to the set value, the process returns to step (17).

However, the brake fluid pressure is reduced in step (17) for a set time (for example, 1.5 seconds)! ! If this continues, it is assumed that the wheel (4) is in a hydroplane phenomenon, and the subroutine is switched to hydroplane mode (HP mode), and the actuator (5) is activated to the wheel cylinder (40). It temporarily (for seconds) outputs a fluid pressure pressurization signal that increases the brake fluid pressure above the set pressure.

Thus, by temporarily increasing the brake fluid pressure in the subroutine (area indicated by Y in Fig. 4), the wheels (4) are momentarily locked, and the water film between the tires and the road surface is removed. Since the coefficient of friction between the tires and the road surface increases, the rotational speed of the wheels (4) quickly recovers and the control unit (9) quickly recovers, as shown in FIG.
) outputs a pressure reduction signal (17)
Since the step (1θ) of outputting the pressurization signal occurs in a short time, even if a hydroplane phenomenon occurs during braking, the stopping distance of the vehicle will not be significantly extended.

(Effects of the Invention) As described above, according to the present invention, when a wheel falls into a hydroplane phenomenon during brake fluid pressure control, if the brake fluid pressure reduction operation by the anti-skid braking device continues for a predetermined time or longer, , the brake fluid pressure is temporarily increased by the controller to momentarily lock the wheels and eliminate a water film between the tires and the road surface;
Subsequent brake control by the anti-skid braking device is performed normally without being adversely affected by the hydroplane phenomenon, and therefore the braking distance of the vehicle is not significantly extended due to the hydroplane phenomenon.
Overall, the braking distance of the vehicle in the event of a hydroplane phenomenon during braking can be made shorter than before.

[Brief explanation of drawings]

Fig. 1 is a system diagram schematically showing the brake mechanism of a vehicle equipped with an anti-skid braking device according to the present invention, Figs. 2 and 3 are flowcharts showing the main calculation processing of the control unit, and Fig. 4 is a flowchart showing the main calculation processing of the control unit. A drawing showing an example of changes in wheel speed and brake fluid pressure when the anti-skid braking device according to the present invention is activated, and FIG. 5 is an example of changes in wheel speed and brake fluid pressure when the conventional anti-skid braking device is activated. FIG. (4)...Wheel (7)...Wheel speed detector (9)...Control unit Figure 3

Claims (1)

[Claims] Wheel speed detector (7) that detects the rotational speed of the wheel (4)
and a control unit (9) that calculates the slip rate of the wheels based on the output signal from the detector (7), maintains the brake hydraulic pressure at a predetermined hydraulic pressure, and reduces the pressure to this predetermined hydraulic pressure. In the anti-skid braking device, the control unit (9) controls the brake fluid pressure to be reduced when the brake fluid pressure is maintained in a reduced pressure state for a predetermined period of time during anti-skid operation to control the brake fluid pressure. 1. An anti-skid braking device comprising: hydraulic pressure changing means for changing the brake hydraulic pressure to a level that temporarily stops the brake fluid and locks the wheels.