Fluid-pressure and analogous brake systems – Multiple systems
Reexamination Certificate
2000-11-09
2002-09-17
Graham, Matthew C. (Department: 3683)
Fluid-pressure and analogous brake systems
Multiple systems
C188S072500, C188S073200, C303S113100
Reexamination Certificate
active
06450586
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a brake control apparatus for use in a vehicle such as a automobile, and more particularly, to a brake control apparatus for controlling a pressure force of a brake pad in accordance with rotation of wheels to prevent the wheels from locking in a vehicle which presses the brake pad to a brake disk in accordance with a braking operation to brake the wheels.
In general, a disc brake is known which applies a brake to wheels by friction between a braking pad and a brake disk in a vehicle such as an automobile. More particularly, actuation of a brake pedal is transmitted to a caliper with the aid of a pressure of brake oil on applying the brake to the wheels in the vehicle, in order to press the brake pad to the brake disk. As a result, the brake disc applies the brake to the wheels in accordance with the friction between the brake pad and the brake disk.
On the other hand, it will be assumed that a harsh braking is applied in the vehicle when the vehicle runs on a slippery road surface on the basis of rainfall or snowfall. The wheels of the vehicle may become a locking state when a braking force exceeds a friction force between the wheels and a road surface. The locking state means that the wheels stops rotating but a car body runs forward. In case where locked wheels are front wheels, it is difficult to steer the vehicle. In case where the locked wheels are rear wheels, an attitude of the car body becomes unstable.
Under the circumstances, a sort of anti-lock brake apparatuses are developed and are realized. In each of the anti-lock brake apparatuses, the wheels are prevented from locking by brake actuation such as a pumping brake actuation to keep a steering ability and to make the attitude of the car body become stable. More specifically, the brake oil pressure is decreased at once in order that the pressure force of the brake pad reduces to the brake disk in a conventional one of the anti-lock brake apparatuses, when detection is made at the instant preceding the locking of the wheels or at the initial locking of wheels. When the pressure force of the brake pad reduces to the brake disk, the braking force is slightly less than a friction force between the road surface and the wheels. As a result, the wheels return to rotate. After that, the brake oil pressure is increased in order to increase the pressure force of the brake pad. A cycle is repeated in which the pressure force of the brake pad is decreased and is increased. As a result, the lock of the wheels is released.
However, the conventional anti-brake apparatus uses, as the brake pad of the ant-brake, the brake pad, which is used in a usual brake operation in order to carry out the anti-brake operation. Therefore, it is impossible to carry out both of the usual brake operation and the anti-brake operation at the same time in the conventional anti-brake apparatus although it is possible to carry out either one of the usual brake operation and the anti-brake operation. In this event, the usual brake operation is carried out at first in the conventional anti-brake apparatus when the brake pedal is pressed. When detection is made at the instant preceding the locking of the wheels or at the initial locking of wheels, the usual brake operation is turned into the anti-brake operation in the conventional ant-brake apparatus. Therefore, it is difficult to prevent the wheels from locking although if it is possible to early release the wheels from locking in the conventional anti-brake apparatus. When the timing is advanced at which the usual brake operation is turned into the anti-brake operation, the duration of the usual brake operation becomes short. As a result, the braking time duration becomes long and the braking distance also becomes long.
In addition, a force, which produced on the basis of variation of the oil pressure in the caliper, is transmitted to the brake pedal when the conventional anti-brake apparatus. Such a transmission will be called a kickback. As a result, the brake pedal vibrates with quick steps. Inasmuch as the brake pedal vibrates with quick steps in no concern to the driver's intension, the driver has unmoral feeling. Even if a light or a sound sends a notice when the kickback occurs, it is difficult for the driver to remove the unmoral feeling.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide a brake control apparatus capable of preventing the wheels from locking without increasing braking time duration and a braking distance.
It is another object of this invention to provide a brake control apparatus capable of preventing the occurrence of a kickback.
Other objects of this invention will become clear as the description proceeds.
According to a first aspect of this invention, there is provided a brake control apparatus comprising a brake disk rotating with a wheel, a main brake mechanism for pressing a main friction member to the brake disk in accordance with an operation of a brake operating member to brake the wheel, lock detecting means for detecting whether or not the wheel becomes an instant condition preceding a locking or an initial condition of the locking to produce a lock detection signal when the wheel becomes the instant condition preceding the locking or the initial condition of the locking, main brake control means for controlling the main brake mechanism to make the main brake mechanism temporarily reduce a main press force which is applied from the main friction member to the brake disk. The brake control apparatus comprises a subsidiary brake mechanism for pressing a subsidiary friction member to the brake disk to brake the wheel and first subsidiary brake control means for controlling the subsidiary brake mechanism to make the subsidiary brake mechanism repeat a variation cycle during the operation of the brake operating member before the first subsidiary brake control means receives the lock detection signal. The subsidiary brake mechanism increases a subsidiary press force after reducing the subsidiary press force in the variation cycle. The subsidiary press force is applied from the subsidiary friction member to the brake disk.
When operating the brake-operating member, the main brake mechanism makes presses the main friction member to the brake disk, which rotates with the wheel, in accordance with the operation of the brake-operating member. On the basis of the friction between the brake disk and the main friction member that is based on the press, the rotation of the wheel is stopped. When the braking force becomes greater than the friction force between the wheel and the road surface and when the wheel becomes the instant condition preceding the locking or the initial condition of the locking, the lock detecting means detects that the wheel becomes the instant condition preceding the locking or the initial condition of the locking. The lock detecting means produces the lock detection signal. In accordance with the lock detection signal, the main brake control means controls the main brake mechanism. Under the control, the main press force of the main friction member increases after reducing temporarily. As a result, an ant-lock braking operation is carried out which is similar to a pumping brake operation.
By the way, first subsidiary brake control means controls the subsidiary brake mechanism during the operation of the brake operating member before the first subsidiary brake control means receives the lock detection signal. More particularly, the subsidiary brake mechanism repeats the variation cycle while the main friction member continues to be pressed to the brake disk, before the main brake control means starts controlling the main brake mechanism. The subsidiary press force increases after reduction. As readily understood from the above description, the wheel is supplied with a main braking force and a subsidiary braking force at the same time. The main braking force is based on an usual braking operation according to the main brake mechanism. The subsidiary braking force is based
Graham Matthew C.
Shlesinger & Arkwright & Garvey LLP
LandOfFree
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