JPH0221982B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake force control device for a vehicle.

In general, this type of brake force control obtains braking force by transmitting the hydraulic pressure generated in the master cylinder by the force applied to the brake pedal to the brake device, and furthermore, the braking force of the wheels is controlled compared to the state of vehicle deceleration. In consideration of cases in which wheel locking may occur due to excessive force, some vehicles are also known that are equipped with a so-called anteskid control mechanism that reduces the wheel braking force in such cases.

By the way, this kind of brake force control takes into consideration the case where the brake force of the wheel is excessive due to a change in the conformation state between the wheel and the road surface relative to the input brake fluid pressure, and it is not necessary to control the brake force when the brake force is insufficient. In some cases, there is no mechanical means to optimize the braking force other than increasing the force applied to the brake pedal.

However, even if the driver of the vehicle operates the brake pedal while feeling the actual deceleration of the vehicle, the brake generation force may vary due to fading of the friction material in the brake system, water leakage, etc. If there is a significant change in the brake performance, it may be difficult to respond appropriately to brake operation.
In severe cases, the external operating force (depressing force) may be insufficient.

Therefore, in the present invention, when the brake force is insufficient due to the fade phenomenon etc. that occurs in the brake device, the brake control mechanism is configured to mechanically compensate for the lack of external operating force. This system is designed to solve the problems that occur when the vehicle deceleration associated with the braking force is small. Specifically, it includes a means for outputting a signal proportional to the external brake operation force, and a means for outputting a signal proportional to the vehicle deceleration during braking. A means for outputting a signal and a booster attached to a brake fluid pressure generation mechanism are provided, and the booster controls brake fluid pressure increase/decrease by comparing a set deceleration corresponding to an external brake operation force with an actually detected vehicle deceleration. In the brake force control device, the booster has a shell, a diaphragm that divides the inside of the shell into two chambers, and a rod that connects the brake pedal and the master cylinder, and controls the differential pressure between these two chambers into the rod. The brake force control device is characterized in that the brake force control device is configured to perform brake fluid pressure increase/decrease control of the booster by adding the brake force control device.

The device of the present invention is similar to when a skid occurs, which causes so-called wheel lock, in that the vehicle deceleration is small compared to the braking force, but is different in that the wheel speed at this time does not decrease compared to when a skid occurs. The control modes can be clearly distinguished.

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

In the figure, 1 is a brake pedal, 2 is a pneumatically actuated booster, 3 is a master cylinder connected to the brake pedal 1 by a rod 4, and 5 is a brake to which the brake fluid pressure generated in the master cylinder 3 is transmitted. It is a braking device that generates force.

And Booster 2 moves high and low 2 inside Ciel 6.
It is equipped with a power piston 7 and a diaphragm 8 which are divided into air chambers, a high pressure chamber 7 is communicated with the atmosphere, and a low pressure chamber 10 is connected to a negative pressure source 12 such as an engine intake manifold via a normally closed solenoid valve 11. ing. For this reason, normally, when the brake pedal 1 is depressed, brake fluid pressure is generated in the master cylinder 3 in proportion to the depression force, which is an external operating force transmitted via the rod 4, and the brake fluid pressure is adjusted accordingly. Generates braking force.

In addition, if the solenoid valve 11 is switched to open, a pressure difference is generated between the two high and low air chambers 9 and 10, and this pressure difference ΔP acts on the power piston 7 to reduce the brake fluid pressure of the rod 4. This will be superimposed as an axial force for generation, and the generated brake fluid pressure will be increased compared to the pressing force on the brake pedal 1.

In this example, the circuit that controls the operation of the booster 2 includes a converter 14 that converts a signal from a detection switch 13 that detects the force applied to the brake pedal 1 into a voltage signal that corresponds to deceleration. The signal from the detection switch 15 that detects the actual vehicle deceleration is compared by the calculation comparator 16, and when these signals have a predetermined correspondence relationship shown during normal brake control, the solenoid valve 11 is activated. On the other hand, when the vehicle deceleration is smaller than a predetermined range compared to the depression force on the brake pedal, the solenoid valve is operated to increase the brake fluid pressure generated by the master cylinder 3. In this case, if the wheel speed suddenly drops, control to prevent the wheels from locking is required, so the brake fluid pressure needs to be lowered. In such a case, it is necessary to stop the operation of the solenoid valve, as activation will have the opposite effect.A separate wheel speed detection circuit may be provided for this purpose, but if the vehicle deceleration is Therefore, when the control is performed in a condensed manner, the control modes will naturally be differentiated.

In addition, in the case of such a method of detecting wheel deceleration, when the wheel deceleration (including the case where it is detected as vehicle deceleration) is greater than the brake pedal force, the booster 2 is activated to reduce the brake fluid pressure of the rod 4. It is also possible to operate in the direction of weakening the generated axial force to maintain an appropriate braking force generation state.

Furthermore, in the brake force control device of the present invention,
Even if a problem occurs in the electrical systems 13 to 16, the brake pedal depression force is transmitted directly to the master cylinder 3 via the rod 4, so there is an advantage that no braking will occur.

As described above, the brake force control device according to the present invention has a relatively simple structure, and in addition to the structure that mechanically transmits the depression force on the brake pedal to the brake device, the brake force control device according to the present invention If a lack of braking force occurs due to a brake failure, etc., the booster has the effect of compensating for the lack of braking force.This makes it possible to perform good input control of the braking force, and its usefulness is extremely large. It is something.

[Brief explanation of drawings]

The drawing is a schematic explanatory diagram of a brake force control device showing an embodiment of the present invention. 1: Brake pedal, 2: Booster, 3: Master cylinder, 4: Rod, 5: Brake device, 6: Shell, 7: Power piston, 8: Diaphragm, 9: High pressure chamber, 10: Low pressure chamber, 11: Solenoid valve , 12: negative pressure source, 13: detection switch, 1
4: converter, 15: detection switch, 16: calculation comparator.

Claims (1)

[Claims] 1 Equipped with a means for outputting a signal proportional to the external brake operation force, a means for outputting a signal proportional to the vehicle deceleration during braking, and a booster attached to the brake fluid pressure generation mechanism, the system corresponds to the external brake operation force. In a brake force control device that controls the booster to increase or decrease brake fluid pressure by comparing a set deceleration with an actually detected vehicle deceleration, the booster includes a shell, a diaphragm that divides the inside of the shell into two chambers, and a brake. It has a rod that connects a pedal and a master cylinder, and by applying the differential pressure between these two chambers to the rod via a diaphragm, the brake fluid pressure of the booster is controlled to increase or decrease. brake force control device.