JPH0362578B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an anti-lock device that eliminates wheel lock that may occur during braking of a vehicle by loosening the brake, thereby ensuring good braking stability.

Various anti-lock methods have been proposed in the past to prevent the occurrence of wheel lock, but this control basically uses the increased brake oil pressure to detect an excessive brake force condition, which is the occurrence of wheel lock. This is to prevent the wheels from sliding on the road surface, and also to raise the brake oil pressure again when the wheels are no longer locked to prevent unnecessary extension of the braking distance. This system requires extremely high responsiveness, with hydraulic pressure control having to be carried out within a few seconds.

Brake hydraulic pressure reducing devices used in such anti-lock systems are generally pneumatically or hydraulically operated power piston-driven devices that utilize vacuum or hydraulic pressure from the vehicle's engine system or steering system. However, such types are subject to various limitations because they require operational connections with various parts of the vehicle.

In recent years, small-sized brake systems that control brake oil pressure using electromagnetic valves have also been applied to practical vehicles.

However, although the conventional control type using this type of solenoid valve has the advantage of being small in size, the control cycle is slow (poor response), resulting in poor wheel behavior during braking. The brake pressure is not smooth, causing vibration in the steering wheel.Furthermore, in the type that uses a pump to repressurize the brake oil pressure, the control characteristics of the drop and repressurization of the brake oil pressure are controlled by the performance of the pump, making it delicate. In addition to problems such as difficult control, the hydraulic circuit is often a complex closed circuit type, making it difficult to bleed air.

In view of these points, the present inventor has conducted extensive studies with the aim of developing a novel anti-lock device that has excellent control responsiveness and control state selectivity for releasing and repressurizing the brake when a wheel lock occurs. This is what we have come to do. That is, the present invention
The brake hydraulic pressure is lowered, re-pressurized,
It is an object of the present invention to provide an anti-lock device which can take a suitable control mode of holding and is structurally simple.

That is, in the present invention, a normally open valve mechanism is interposed in the hydraulic transmission system (hereinafter referred to as the first system) from the master cylinder to the brake device, and this valve mechanism is operated by external pressing force. After closing the flow path, the brake hydraulic pressure is reduced by increasing the internal volume of the oil chamber on the brake device side. A piston mechanism is attached to the valve mechanism that uses the hydraulic pressure of the second system to apply a pressing force to close and move the valve. The feature is that it can be easily performed using hydraulic control.

The gist of the present invention to achieve such an object is to provide a first system for transmitting brake hydraulic pressure connected from a master cylinder of a vehicle to a brake device, and a first system that is independent of the first system. a second system for transmitting the discharge hydraulic pressure from the pump; a brake hydraulic pressure control valve interposed in the middle of the first system;
a piston mechanism that drives the brake hydraulic control valve by hydraulic action from the oil chamber c of the second system; A normally open valve mechanism is divided into an output oil chamber b, a valve seat body which is stopped at the normally open position by a first hold spring, and a valve seat body which is kept at the normally open position by a second hold spring. The valve body is moved by the pressing force from the piston mechanism and engages with the valve seat body to close the valve, and then the engaged valve body and the valve seat body are closed. The piston mechanism is provided so that the internal volume of the output oil chamber b can be increased by integrally moving the piston mechanism.
Normally, the hydraulic pressure in the oil chamber c is released to the reservoir by the switching operation of the electromagnetic valve device, and when it is necessary to lower the brake oil pressure during wheel antilock control, the hydraulic pressure is maintained in the oil chamber c by the switching operation of the electromagnetic valve. It features a wheel anti-lock device.

The present invention will be described below based on embodiments shown in the drawings.

FIG. 1 shows an outline of the configuration of an embodiment of the present invention, and in the figure, 1 is a brake pedal, 2 is a master cylinder, 3 is a reservoir, 4 is a brake device, and 5 is a connection from the master cylinder 2 to the brake device. This is a brake hydraulic pressure transmission pipe (hereinafter referred to as a first system pipe), and a brake hydraulic pressure control device 6 is interposed in the middle of this first system pipe.

This brake hydraulic control device 6 includes a normally open valve formed by a valve seat body 9 and a valve body 10 in a cylinder 8 of a valve body 7, and has an input oil chamber a, an output oil chamber, and an output oil chamber in the cylinder 8. The valve seat body 9 and the valve body 10 are biased and fixed at a limit position on the output oil chamber side by hold springs 11 and 12, respectively.

In this example, the valve seat body 9 is provided in a stepped shape, and the piston cup 13 is fitted into the small diameter portion on the side of the input oil chamber a to provide a liquid-tight seal between the input and output oil chambers. ing. Further, the valve body 10 has a rubber sheet attached to a shaft-shaped piston to form a valve seat 14 that abuts against the valve seat, and also has an annular shape that engages with the valve seat body 9 after the valve seat 14 is slightly deformed. Assembling the body.

A decay rod 15 is engaged with the end of the valve body 10 on the side of the input oil chamber b, and this applies an external pressing force to the valve body 10 by means of a piston mechanism serving as a drive device, which will be described later.

In the brake hydraulic control device configured as described above, the valve body 10 is normally spaced apart from the valve seat body 9 and communicates between the input and output oil chambers a and b, thereby controlling the hydraulic pressure from the master cylinder. When the valve body 10 comes into contact with the valve seat 9 under pressure from the day-scale rod 15, the communication between the input and output oil chambers a and b is cut off, and furthermore, the pressure from the day-scale rod 15 is transmitted to the brake device. When the pressing force increases and the valve seat body 9 is moved via the valve body 10,
The brake oil pressure can be reduced by increasing the internal volume of the cylinder output oil chamber b by an amount corresponding to the moving distance.

The moving distance of the valve body and the valve seat body is determined by the balance between the respective hydraulic pressures of the input oil chamber a and the output oil chamber b and the pressing force from the decay rod 15, and the pressing force from the decay rod 15 is adjusted accordingly. By controlling the increase/decrease or holding, the brake oil pressure can be controlled to an appropriate state.

Next, the piston mechanism described above will be explained. In this example, the cylinder 8 is attached to the valve body 7.
Another cylinder 16 concentric with the output oil chamber b is formed outside the output oil chamber b, a decay piston 17 is slid into this cylinder 16, and the decay rod 15 is engaged with this decay piston 17. There is. One of the two oil chambers c and d divided by the decay piston 17 (the side that applies hydraulic pressure in the direction of pressing the decay rod 15), the oil chamber c, is a control oil that generates hydraulic pressure. The other oil chamber d is connected to a separate hydraulic system (hereinafter referred to as second system piping) from the first system piping for transmitting brake hydraulic pressure so as to form an oil chamber that does not generate hydraulic pressure. ing. That is, the hydraulic pressure supply pipe 20 from the pump 18 for hydraulic discharge is a normally open type first pipe.
The oil chamber c is connected to the oil chamber c via a solenoid valve 19, and the oil chamber c is connected to the oil chamber d and the reverber 3 via a normally open second solenoid valve 22 via a separate hydraulic discharge pipe 21.
and connected to the pump 18.

Note that 23 is a check valve installed in a bypass path connecting from the pump 18 to the hydraulic discharge pipe 21, and functions to determine the maximum hydraulic pressure that can be supplied to the oil chamber c. Therefore, with such a check valve 23, the pump 18 can be driven all the time or driven only during anti-lock control, and there is no need for precise design attention to the amount of oil discharged.

The operation of the piston mechanism configured as described above is controlled by the oil pressure value applied to the oil chamber c by the operation of the first and second electromagnetic valves 19 and 22. That is, in the normal state shown in the figure, no hydraulic pressure acts on the decay piston 17 in both axial directions, and therefore the decay rod 1
5 as well, the external pressing force described above does not act on it.

While the first solenoid valve 19 remains open, the second solenoid valve 2
2 is closed, the oil discharged from the pump 18 is supplied to the oil chamber c, and therefore the decay piston 17
Hydraulic pressure acts from the oil chamber c side to apply an external pressing force to the decal rod 15.
As described above, depending on the magnitude of this pressing force, the line from the master cylinder to the brake device is shut off and the brake oil pressure is reduced in the brake oil pressure control valve 6.

Next, by continuing to close the second solenoid valve 22 and closing the first solenoid valve 19, the oil pressure in the oil chamber c is maintained at the current oil pressure value.

If only the second solenoid valve 22 is opened or closed again from this state, the oil pressure value in the oil chamber c can be appropriately reduced or maintained, and the oil pressure c
In other words, the decrease in the amount of oil in the brake cylinder occurs as a result of repressurization of the brake oil pressure.

In this way, the brake hydraulic pressure is reduced, maintained, and repressurized by controlling the opening and closing of the first and second solenoid valves 19 and 22, and the second system piping is connected to the first system piping. Because it is separate and independent from the above, it exhibits the excellent effect of being able to provide sufficiently large and rapid changes in hydraulic pressure.

The signals for operating the first and second solenoid valves 19 and 22 for wheel anti-lock control can be obtained using an electrical control circuit according to a known anti-skid control method. FIG. 2 shows an example of the initiation of such antilock control.

In Fig. 2, the upper stage uses the wheel speed signal V _W (detected as a voltage signal) and the pseudo deceleration signal V _T.
The relationship that determines the time when the pump 12 starts driving and the time when the first and second solenoid valves 19 and 22 start operating (normally open (off) → closed circuit (on)) is shown.
The relationship between the operation timing of the second electromagnetic valve is shown, and the lower row shows the relationship between the drive of the pump and the change characteristics of the brake oil pressure using the same time chart.

In the anti-lock control method shown in FIG. 2, the wheel speed signal V _W suddenly drops when the vehicle is braked.
At time t ₀ when this exceeds a certain maximum deceleration Gmax, the second solenoid valve 22 is turned on, and at the same time, the pump 18 is turned on. Then, the first solenoid valve 19 is turned on after a delay of a minute time ΔT from this time point _t0 . Through this series of operations, oil pressure is first supplied to the oil chamber c, and the brake oil pressure control valve is initially closed.
When stopping the brake oil pressure increase alone is not sufficient, the brake oil pressure is reduced in the following manner. i.e. wheel speed signal
Using a pseudo speed signal V _{T that} is subtracted from V _W by a constant value _ΔV and in which a limit of the deceleration gradient is set, the _first electromagnetic This opens the valve 19 (returns it to off).

As described above, according to the anti-lock device according to the present invention, the structure of each hydraulic piping system is simplified, air bleeding is easy, and the various parts of the device do not slide during normal braking, which improves durability and It has the advantage of being excellent in safety, and because of the simple structure that uses the first and second hold springs, the spring force of these first and second hold springs acts in stages, and the valve is closed. Since it is possible to clearly distinguish between the process up to closing the brake and the subsequent increase in the internal volume of the output oil chamber b, the mode of holding, depressurizing, and repressurizing the brake oil pressure can be appropriately selected. The practical utility is extremely great.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of a wheel anti-lock device according to the present invention, and FIG. 2 is a diagram showing an example of control characteristics at the start of anti-skid control. 1: Brake pedal, 2: Master cylinder,
3: Reservoir, 4: Brake device, 5: Piping,
6: Brake hydraulic control valve, 7: Valve body, 8: Cylinder, 9: Valve seat body, 10: Valve body, 1
1, 12: Hold spring, 13: Piston cup, 14: Valve seat, 15: Decay rod, 16: Cylinder, 17: Decay piston, 18: Pump, 19: First solenoid valve, 20: Hydraulic pressure supply pipe, 21: Hydraulic discharge piping, 22: second solenoid valve, 23: check valve.

Claims (1)

[Claims] 1. A first system for transmitting brake hydraulic pressure connected from the master cylinder of the vehicle to the brake device, a second system that is independent of the first system and transmits the discharge hydraulic pressure from the pump, and the first system. and a piston mechanism that drives the brake hydraulic pressure control valve by hydraulic action from the oil chamber c of the second system, and the brake hydraulic control valve is installed in the valve cylinder. a normally open valve mechanism that divides the valve into an input oil chamber a on the master cylinder side and an output oil chamber b on the brake device side, the valve seat body being stopped at the valve normally open position by a first hold spring; The valve body is stopped at the normally open position by a second hold spring, and the valve body is moved by the pressing force from the piston mechanism and engaged with the valve seat body, thereby closing the valve. Further, the engaged valve body and the valve seat body are then moved together to increase the internal volume of the output oil chamber b, and the piston mechanism normally increases the internal volume of the oil chamber c by the switching operation of the electromagnetic valve device. A wheel antilock device characterized in that the hydraulic pressure is released to a reservoir, and when it is necessary to lower the brake hydraulic pressure during wheel antilock control, the hydraulic pressure is maintained in the oil chamber c by switching operation of the electromagnetic valve.