Fluid-pressure and analogous brake systems – Speed-controlled – Odd condition or device detection
Reexamination Certificate
1998-10-22
2001-02-20
Oberleitner, Robert J. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Odd condition or device detection
C303S155000, C303S196000, C303S113400
Reexamination Certificate
active
06189987
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a brake force control apparatus and, more particularly, to a brake force control apparatus which generates a brake force greater than that generated at an ordinary time, when an emergency braking is performed by a driver of a vehicle.
Conventionally, for example, as disclosed in Japanese Laid-Open Patent Application 4-121260, a brake force control apparatus is known which generates, when an emergency braking is required, a brake force greater than that generated in a normal time. The above-mentioned conventional apparatus is equipped with a brake booster, which generates a pushing force having a given power ratio with respect to brake pressing force Fp. The pushing force generated by the brake booster is transformed to a master cylinder. The master cylinder generates a master cylinder pressure PM/C based on the pushing force of the brake booster, that is, the brake pressing force Fp.
The above-conventional apparatus is equipped with a fluid pressure generating mechanism, which generates an assist hydraulic pressure in which a pump is used as a fluid pressure source. The fluid pressure generating mechanism generates the assist hydraulic pressure based on a driving signal supplied from a control circuit. When the brake pedal is operated at a speed higher than a predetermined speed, the control circuit determines that an emergency braking is carried out by the driver, and outputs to the fluid pressure generating mechanism a drive signal which requests a maximum assist hydraulic pressure.
The assist hydraulic pressure generated by the fluid pressure generating mechanism and the master cylinder pressure PM/C generated by the master cylinder are both supplied to a change valve. If the assist hydraulic pressure is higher than the master cylinder pressure PM/C, the change valve supplies the wheel cylinder to the assist hydraulic pressure. If the master cylinder pressure PM/C is higher than the assist hydraulic pressure, he change valve supplies the master cylinder pressure PM/C to the wheel cylinder.
According to the conventional apparatus, if the brake pedal is operated at a speed equal to or less than the given operating speed, the master cylinder pressure PM/C adjusted to a level depending on the brake pressing force Fp is supplied to the wheel cylinders. Hereinafter, the control of realizing the above-mentioned state will be referred to as a normal control. If the brake pedal is operated at a speed higher than the given operating speed, a high assist hydraulic pressure is supplied to the wheel cylinders in which the pump serves as a fluid pressure source. Hereinafter, the control of realizing the above-mentioned state will be referred to as a brake assist control. Hence, according to the conventional apparatus, a brake force based on the brake pressing force Fp obtained when the driver performs normal braking can be generated, and can rapidly be raised after an emergency braking is performed.
However, besides a situation in which the driver intentionally performs the emergency braking, the brake pedal may be pressed at a high speed if the vehicle is traveling on a rough road or the vehicle rides over a step on the road. According to the above conventional apparatus, the brake assist control is performed without exception when the brake pedal is depressed at a speed equal to or higher than the predetermined value irrespective of the vehicle traveling environment. Hence, the conventional apparatus may generate an unnecessarily large braking force when the vehicle is traveling on a rough road or passing a step.
SUMMARY OF INVENTION
The present invention is made in view of the above-mentioned point, and it is an object of the present invention to provide a brake force control apparatus which cannot generate an unnecessarily large brake force when an emergency brake is performed while a vehicle is traveling on a rough road or riding over a step.
A first brake force control apparatus that achieves the object executes a normal control of generating a brake force based on a brake pressing force, and a brake assist control of generating a brake force greater than that generated at a normal time. This brake force control apparatus is equipped with operation speed detection means for detecting a brake operation speed, and determines that a condition for execution of the brake assist control related to the brake operation speed stands when the brake operation speed exceeds a predetermined speed. Further, the brake force control apparatus of the present invention is equipped with body vibration detection means for detecting a body vibration of a vehicle, and changes the predetermined speed on the basis of the body vibration.
When the vehicle is traveling on a rough road or when the vehicle is passing a step, a large body vibration is likely to occur. If a large body vibration occurs when the vehicle is traveling, the brake operation may temporarily be performed at a higher speed. Hence, if a large body vibration is generated, the condition for execution of the brake assist control related to the brake operation speed may stand easily although the driver does not perform the emergency braking. The first execution condition change means changes the predetermined speed based on the body vibration in order to prevent the condition for execution of the brake assist control in cases as described above. Hence, according to the brake assist control of the present invention, it is possible to create a situation in which the brake assist control is started with more difficulty at the time of traveling a rough road or passing a step.
A second brake force control apparatus directed to achieving the above object executes a normal control of generating a brake force based on a brake pressing force, and a brake assist control of generating a brake force greater than that generated at a normal time. This brake force control apparatus is equipped with operation speed detection means for detecting a brake operation speed, and determines that a condition for execution of the brake assist control related to the brake operation speed stands when the brake operation speed exceeds a predetermined speed. Further, the brake force control apparatus of the present invention is equipped with body vibration detection means for detecting a body vibration of a vehicle, and inhibits execution of the brake assist control when the predetermined body vibration is detected.
In the present invention, the first execution inhibiting means inhibits execution of the brake assist control when the predetermined body vibration occurs. Hence, when the vehicle is traveling on a rough road or passing a step, the brake assist control is not executed even if the braking is performed due to the body vibration. Thus, according to the brake force control apparatus of the present invention, it is possible to definitely prevent the brake assist control from being executed due to an external turbulence.
A third brake force control apparatus directed to achieving the above-mentioned object executes a normal control of generating a brake force based on a brake pressing force, and a brake assist control of generating a brake force greater than that generated at a normal time. This brake force control apparatus is equipped with operation speed detection means for detecting a brake operation speed, and determines that a condition for execution of the brake assist control related to the brake operation speed stands when the brake operation speed exceeds a predetermined speed. Further, the brake force control apparatus of the present invention is equipped with road surface condition detection means for detecting a road surface condition, and changes the predetermined speed on the basis of the road surface condition.
A high-speed braking operation may temporarily be detected although the driver does not actually perform the emergency braking. The second execution condition change means changes the predetermined speed on the basis of the road surface condition in order to prevent the condition for execution
Kenyon & Kenyon
Kramer Devon
Oberleitner Robert J.
Toyota Jidosha & Kabushiki Kaisha
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