Fluid-pressure and analogous brake systems – Speed-controlled – Braking pressure demand or braking force desire
Reexamination Certificate
1998-10-21
2001-08-28
Oberleitner, Robert J. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Braking pressure demand or braking force desire
C303S113400, C303S139000, C303S113200, C303S122000
Reexamination Certificate
active
06280008
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a. brake force control apparatus and, more particularly, to a brake force control apparatus which generates, when an emergency braking is required, a brake force greater than that generated in an ordinary time.
BACKGROUND ART
Conventionally, for example, as disclosed in Japanese Laid-Open Patent Application 4-121260, a brake force control apparatus which generates, when an emergency braking is required, a brake force greater than that generated in a normal time is known. The above-mentioned conventional apparatus comprises a control circuit which generates a drive signal corresponding to an operational speed of a brake pedal and a fluid pressure generating mechanism which generates a brake fluid pressure corresponding to the drive signal generated by the control circuit.
The control circuit determines that, when an operational speed of a brake pedal is less than a predetermined value, the brake pedal is not normally operated. In this case, the fluid pressure generating mechanism is controlled so that a brake fluid pressure corresponding to a brake pressing force is generated. Hereinafter, this control is referred to as a normal control. Additionally, the control circuit determines that, when an operational force of the brake pedal exceeds a predetermined value, an emergency braking is required by the driver. In this case, the fluid pressure generating mechanism is controlled so that a brake fluid pressure is maximized. Hereinafter, this control is referred to as a brake assist control. Thus, according to the above-mentioned conventional apparatus, a brake force corresponding to a brake pressing force can be generated in a normal time, and a large brake force can be immediately generated in an emergency. Thereby, an emergency braking can be performed and a rapid braking can be achieved even if the driver intends to perform an emergency braking but is unable to hold a large pressing force applied to a brake pedal.
Conventionally, in order to improve a driving stability, apparatuses for a vehicle which perform an antilock brake control (hereinafter, referred to as an ABS control), a vehicle stability control (hereinafter, referred to as ASC), a traction control (hereinafter, referred to as TRC) or a suspension attenuation force control are known. These apparatuses control a distribution of braking and driving forces, a distribution of rolling rigidity, a posture, and a distribution of a load to each wheel so as to improve a driving stability of the vehicle with respect to changes in a moving condition or a driving condition of the vehicle. Hereinafter, such an apparatus which improves a driving stability of a vehicle is referred to as a vehicle characteristic changing apparatus. By the above-mentioned conventional brake force control apparatus is provided to a vehicle together with the vehicle characteristic changing apparatus, a rapid braking can be achieved by performing a brake assist control and an improvement of a driving stability of a vehicle can be achieved so that safety of the vehicle is greatly improved.
However, in the vehicle having the above-mentioned vehicle characteristic changing apparatus, when an abnormality occurs in the vehicle characteristic changing apparatus, a driving stability is changed as compared to that of a normal time. Additionally, in the vehicle having the above-mentioned vehicle characteristic changing apparatus, when the brake assist control is performed as an emergency braking is required, a side force which can be generated by the vehicle is decreased and the driving stability is changed since a large brake force is generated rapidly. Accordingly, In the vehicle having both the above-mentioned vehicle characteristic changing apparatus and the brake force control apparatus, when the brake assist control is performed by the above-mentioned brake force control apparatus under a condition in which the vehicle characteristic changing apparatus malfunctions, an amount of change of a driving stability is increased as compared to a case in which the vehicle characteristic changing apparatus is normal and before the brake assist control is performed.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide an improved and useful brake force control apparatus in which the above-mentioned problems are eliminated.
A more specific object of the present invention is to provide a brake force control apparatus which can minimize a change in a driving stability of a vehicle when a vehicle characteristic changing apparatus malfunctions.
In order to achieve the above-mentioned objects, there is provided according to one aspect of the present invention a brake force control apparatus adapted to be provided on a vehicle having a vehicle characteristic changing apparatus for controlling a driving stability of the vehicle, the brake force control apparatus performing a normal control for generating a brake force corresponding to a brake pressing force and a brake assist control for generating a brake force larger than that of the normal control when an operational state of a brake pedal satisfies a predetermined condition,
characterized by:
pressure increasing slope controlling means for decreasing an increasing slope of a brake force of at least rear wheels among front and rear wheels of the vehicle when the brake assist control is performed and if an abnormality occurs in the vehicle characteristic changing apparatus.
In the present invention, the vehicle characteristic changing apparatus controls a driving stability of a vehicle. Accordingly, if an abnormality occurs in the vehicle characteristic changing apparatus, the driving stability of the vehicle is changed. If the brake assist control performed in such a case, a brake force is increased, and, thereby, a degree of change in the driving stability is further increased. When the brake force is increased, the rear wheels are easily locked as compared to the front wheels. In the present invention, when an abnormality occurs in the vehicle characteristic changing apparatus, an increasing slope of a brake force when the brake assist control is performed is decreased by the pressure increasing slope controlling means for at least the rear wheels which are easily locked. Accordingly, when an abnormality occurs in the vehicle characteristic changing apparatus, a change in the driving stability of the vehicle due to the execution of the brake assist control is suppressed.
According to the above-mentioned invention, when an abnormality occurs in the vehicle characteristic changing apparatus, a change in the driving stability of the vehicle due to the execution of the brake assist control can be suppressed while obtaining a brake effect according to the brake assist control by decreasing an increasing slope of the rear wheels when the brake assist control is performed.
Additionally, there is provided according to another aspect of the present invention a brake force control apparatus adapted to be provided on a vehicle having a vehicle characteristic changing apparatus for controlling a driving stability of the vehicle, the brake force control apparatus performing a normal control for generating a brake force corresponding to a brake pressing force and a brake assist control for generating a brake force larger than that of the normal control when an operational state of a brake pedal satisfies a predetermined condition,
characterized by:
control prohibiting means for prohibiting an execution of the brake assist control when an abnormality occurs in the vehicle characteristic changing apparatus.
In this invention, the vehicle characteristic changing apparatus controls a driving stability of a vehicle. Accordingly, if an abnormality occurs in the vehicle characteristic changing apparatus, the driving stability of the vehicle is changed. If the brake assist control performed in such a case, a brake force is increased, and, thereby, a degree of change in the driving stability is further increased. In the present invention, when an abnormality occurs in th
Kenyon & Kenyon
Kramer Devon
Oberleitner Robert J.
Toyota Jidosha & Kabushiki Kaisha
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