Fluid-pressure and analogous brake systems – Speed-controlled – Braking pressure demand or braking force desire
Reexamination Certificate
1999-01-19
2001-11-27
Butler, Douglas C. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Braking pressure demand or braking force desire
C303S003000
Reexamination Certificate
active
06322168
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.
Conventionally, in order to prevent a lock of a wheel during a braking operation, an antilock brake control (hereinafter, referred to as an ABS control) is applied to a brake apparatus of a vehicle. The ABS control is for preventing a lock of a wheel by changing a state of a brake force among three states, that is, a pressure-increasing state, a holding state and a pressure-decreasing state so that a slip rate of the wheel does not exceed a predetermined value. Accordingly, when performing the ABS control, a brake force is intermittently changed in association with the changeover among the above-mentioned three states. Thus, when the ABS control is applied to the above-mentioned brake force, a vibration may be generated in a fluid pressure within the apparatus in association with changes in the brake force. If such a vibration is transmitted to a brake pedal, a movement which is not intended by the driver may occur in the brake pedal. In such a condition, it is determined that an emergency braking is required since an operational speed of the brake pedal exceeds a predetermined value despite that the driver does not perform an emergency braking operation, and the brake assist control may be started which results in an incongruous feel provided to the driver. Accordingly, in the above-mentioned conventional apparatus, the brake assist control may be improperly performed due to a vibration in a fluid pressure generated during an execution of the ABS control even when an emergency braking is not required, and, thereby, a riding quality of the vehicle may be deteriorated.
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 prevent the brake assist control being improperly executed while the ABS control is executed.
In order to achieve the above-mentioned objects, there is provided according to one aspect of the present invention a brake force control apparatus performing a normal control for generating a brake force corresponding to a brake pressing force, 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 and an antilock brake control for preventing a slip of a wheel by controlling a brake force,
characterized by:
control prohibiting means for determining whether or not the antilock brake control is being performed, and for prohibiting a start of said brake assist control when said antilock brake control is being performed.
When the antilock brake control is being performed, a brake force is intermittently changed. According to the changes in brake force, a vibration is generated in the fluid pressure of the brake force control apparatus. Such a vibration is transmitted to the brake pedal, and a movement of the brake pedal is generated in association with the vibration since the brake pedal is being operated during the ABS is in operation. Accordingly, when the antilock brake control is being performed, there may be a case in which an operational state of the brake pedal satisfies said predetermined condition even when an emergency braking is not required. In the present invention, when the antilock brake control is being performed, a start of the brake assist control is prohibited by the control prohibiting means. Accordingly, the brake assist control is not being performed if the condition for starting the brake assist control is satisfied due to the above-mentioned vibration associated with an execution of the antilock brake control. Thereby, an incongruous feel is prevented from being provided to a driver.
Additionally, there is provided according to another aspect of the present invention a brake force control apparatus performing a normal control for generating a brake force corresponding to a brake pressing force, 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 and an antilock brake control for preventing a slip of a wheel by controlling a brake force,
characterized by:
control prohibiting means for determining whether or not the antilock brake control is being performed, and for prohibiting a start of said brake assist control until a predetermined time has been passed after said antilock brake control is being performed.
When the antilock brake control is started, a controlled state of the brake force control apparatus is changed. According to such a change of the controlled state, a discontinuous change is generated in the fluid pressure of the brake force control apparatus. Accordingly, a vibration is generated in the fluid pressure of the brake force control apparatus. Such a vibration is transmitted to the brake pedal, and a movement of the brake pedal is generated in association with the vibration since the brake pedal is being operated during the ABS is in operation. Accordingly, immediately after the antilock braking operation is started, there may be a case in which an operational state of the brake pedal satisfies said predetermined condition by which the start of the brake assist control is determined even when an emergency braking is not required. In the present invention, when an elapsed time after the antilock brake control is started does not reach the predetermined time, a start of the brake assist control is prohibited by the control prohibiting means. Accordingly, the brake assist control is not being performed if the condition for starting the brake assist control is satisfied due to the above-mentioned vibration associated with an execution of the antilock brake control. Thereby, an incongruous feel is prevented from being provided to a driver.
There is provided according to another aspect of the present invention to provide a brake force control apparatus performing a normal control for generating a brake force corresponding to a brake pressing force, 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 and an antilock bra
Butler Douglas C.
Kenyon & Kenyon
Kramer Devon
Toyota Jidosha & Kabushiki Kaisha
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