Fluid-pressure and analogous brake systems – Speed-controlled – With failure responsive means
Reexamination Certificate
2000-01-10
2002-07-02
Rodriguez, Pam (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
With failure responsive means
C303S140000, C303S141000, C303S146000, C303S189000
Reexamination Certificate
active
06412885
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a brake system for vehicles such as automobiles, and more particularly, to a brake system for vehicles which comprises braking force generation means adapted to generate braking forces according to the amount of depression of a brake pedal.
2. Description of the Prior Art
The brake system for vehicles such as automobiles generally comprises braking force generation means provided for each of the wheels, each including a rotary member such as a brake rotor or a brake drum constructed to rotate together with a corresponding wheel and a movable member such as a brake pad or a brake shoe constructed to be driven according to the amount of depression (force or stroke of depression) of the brake pedal, so that each of the braking force generation means generates a braking force by a friction material of the movable member being pressed against the rotary member, so as thereby to brake the rotation of the corresponding wheel.
As one of those brake systems there is known an electric brake system in which the movable member of the braking force generation means is driven by an ultrasonic motor, wherein the ultrasonic motor provided for each of the wheels is controlled according to the amount of depression of the brake pedal, while the braking force generation means is constructed to dissolve a braking force generating condition when it went wrong in a condition of generating a braking force.
According to such an electric brake system of the prior application, since the ultrasonic motors are controlled separately for each of the wheels, the braking force of each of the wheels can be controlled independently of those of other wheels, and since the braking condition is dissolved even when the braking force generation means went wrong in a condition of generating a braking force, there can be avoided such a trouble that the running of the vehicle is interfered by a standing generation of a needless braking force due to a trouble of the brake system.
However, in the above-mentioned conventional electric brake system, although a fail-safe is cared for against a trouble of each of the braking force generation means each provided for each of the wheels, the stability of the behavior of the vehicle under a condition that the braking force generation means of a certain one of the wheels went wrong, i.e., the running stability of the vehicle as a whole, leaves a large room for further improvements.
In more detail, if the braking force generation means of either one of the wheels went wrong, there occurs a situation during a braking of the vehicle that, while the braking force of the wheel where the braking force generation means went wrong makes no change in spite of any change of the amount of depression of the brake pedal, the braking force of the wheel transversely opposite to the wheel where the braking force generation means went wrong changes according to the amount of depression of the brake pedal (an unbalanced braking condition), whereby a needless yaw moment is applied to the vehicle, deteriorating the running stability of the vehicle. Such a problem is latent not only in the electric brake system but also in various types of brake systems by which the braking of each of the wheels is controllable independently of those of the other wheels by each braking force generation means provided exclusively for each corresponding wheel.
Particularly when the braking force generation means went wrong to generate no braking force, a needless yaw moment is applied to the vehicle according to the depression of the brake pedal by a driver, rendering the vehicle to be liable to a deterioration of behavior, while on the other hand, if the braking force generation means went wrong to hold a braking force, the vehicle is subjected to a fluctuating yaw moment according to a depression of the brake pedal by the driver, thereby causing not only a deterioration of the running behavior of the vehicle but also causing a useless consumption of the kinetic energy generated by the engine for driving the vehicle. The adverse effect of a trouble occurred in the braking force generation means on a deterioration of the behavior of the vehicle is generally more noticeable when the engine is generating a higher level of kinetic energy, i.e. the vehicle speed, and therefore the momentum of the vehicle, is higher.
SUMMARY OF THE INVENTION
The present invention was made in view of the above-mentioned problems in conventional brake systems such as the electric brake system which are capable of controlling the braking force of each of the wheels independently of those of other wheels. A primary object of the present invention is to improve the running stability of vehicles than ever, by preventing a needless too large yaw moment from being applied to the vehicle when the braking force generation means of either one of the wheels went wrong, so as thereby to decrease or eliminate any adverse effect being applied to the vehicle due to the trouble of the braking force generation means.
According to the present invention, the above-mentioned primary object is accomplished by a brake system for vehicles, comprising braking force generation means each provided for each of wheels to generate a braking force according to an amount of depression of a brake pedal, and control means for controlling each of the braking force generation means for each of the wheels independently of the other braking force generation means for the other wheels, wherein when either one of the braking force generation means went wrong, the control means controls other normal one or ones of the braking force generation means, so as substantially not to apply any needless yaw moment to the vehicle.
According to the above-mentioned construction, when either one of the braking force generation means went wrong, the control means controls other normal one of ones of the braking force generation means so as substantially not to apply any needless yaw moment to the vehicle, whereby it is definitely prevented that there occurs such a situation that the vehicle is applied with a needless excessive yaw moment during a running thereof.
Alternatively, according to the present invention, the above-mentioned object is accomplished by a brake system for vehicles, comprising braking force generation means each provided for each of wheels to generate a braking force according to an amount of depression of a brake pedal, and a control means for controlling each of the braking force generation means for each of the wheels independently of the other braking force generation means for the other wheels, wherein the vehicle has an engine for generating a kinetic energy for the vehicle to run, and when either one of the braking force generation means went wrong, the control means restricts the generation of the kinetic energy by the engine.
According to the above-mentioned construction, when either one of the braking force generation means went wrong, the generation of the kinetic energy by the engine is restricted, whereby it is suppressed that the speed and the kinetic energy of the vehicle rise high, so that thereby an adverse influence of a needless yaw moment being applied to the vehicle due to a malfunction of the braking force generation means on a stable running of the vehicle is decreased.
In the above-mentioned construction, when either one of the braking force generation means went wrong to generate substantially no braking force, the control means may forbid one of the braking force generation means positioned transversely opposite to the wrong braking force generation means to operate, so as to prevent a needless yaw moment from being applied to the vehicle. According to such a construction, it is definitely avoided that there occurs an unbalance braking condition such that the wrong braking force generation means generates no braking force during a braking of the vehicle, while the braking force of one of the braking force generation means positioned transversely opposite to the
Inoue Hideyuki
Otomo Akihiro
Shirai Kenji
Yoshino Yasunori
Kramer Devon
Rodriguez Pam
Toyota Jidosha & Kabushiki Kaisha
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