Fluid-pressure and analogous brake systems – Speed-controlled – Odd condition or device detection
Reexamination Certificate
2001-05-29
2002-06-25
Butler, Douglas C. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Odd condition or device detection
C303S001000
Reexamination Certificate
active
06409289
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and a device for ensuring the braking effect of brake actuators in a vehicle. Many modifications of such methods and devices are known in the related art.
BACKGROUND INFORMATION
German Patent Application No. 198 46 392 describes a method of drying a vehicular operating brake having a brake disk and brake linings. The response of the operating brake when driving in rain or snow or on wet roads is improved by the methods described in German Patent Application No. 198 46 392, thus ensuring a shorter stopping distance. Information about the degree of wetness is generated first. On the basis of this information, an automatic drying function is activated, applying the brake linings to the brake disks in such a way that there is essentially no noticeable deceleration of the vehicle.
German Patent No. 44 27 170 describes a method of ensuring the braking effect of brakes in vehicles in wet weather. According to this method, a sensor device determines the presence of wetness. If there is wetness, the time when the brakes are not operated is determined. At least when the brake operation-free time thus determined exceeds a time threshold, a braking operation is performed by a controller provided in the vehicle during a certain braking time. During the braking operation, a brake pressure is generated, the resulting braking effect being determined so that the driver will not perceive any deceleration of the vehicle.
The publications cited above contain activation conditions which, when met, result in the brake actuators present in the vehicle being activated in such a way that braking-diminishing films on these brake actuators are removed. If none of these activation conditions are met, the operation of the gas pedal is considered.
Against this background, the object is as follows: Existing methods and equipment for ensuring the braking effect of brake actuators arranged in the vehicle are to be improved to the extent that the driver's desire for acceleration can be implemented without being affected.
At this point, reference should be made to the publication “FDR—Die Fahrdynamikregelung von Bosch” [FDR—driving dynamics control by Bosch] in the automotive engineering journal ATZ, vol. 96, no. 11 (1994) pp. 674-689. This publication describes a device for controlling the yaw rate of the vehicle. To do so, the measured yaw rate is compared with a setpoint for the yaw rate. This comparison determines a system deviation of the yaw rate as a function of which braking measures and/or engine measures are implemented on individual wheels independently of the driver. A yaw moment is applied to the vehicle mainly as a result of the braking measures independent of the driver, causing the actual yaw rate to approach the setpoint.
Furthermore, reference is made to SAE Paper 870337 “ASR traction control—a logical extension of ABS.” This SAE paper describes a slip-regulated brake system with which traction control, in addition to brake slip control, can be implemented. Braking measures independent of the driver are also necessary to implement traction control.
The term “braking measures independent of the driver” as used above means that a brake pressure can be generated in the wheel brake cylinders with braking measures independently of the driver even if the driver has not operated the brake pedal. With these braking measures it is also possible to produce a higher brake pressure in the wheel brake cylinders than the admission pressure which is determined by operation of the brake pedal by the driver. To implement braking measures independently of the driver, there must be a pump in the brake system where a brake pressure can be produced independently of the driver.
The content of the publication cited above publication “FDR—Die Fahrdynamikregelung von Bosch” [FDR—driving dynamics control by Bosch] as well as the content of SAE Paper 870337 are hereby incorporated by reference in the present application.
SUMMARY OF THE INVENTION
The present method relates to a method of ensuring the braking effect of brake actuators in a vehicle, each brake actuator containing first and second components for producing the braking effect. With the present method, films on the first components that could interfere with the deployment of the braking effect are removed. To do so, when an activation condition is met, the brake actuators for removing the brake films are controlled in such a way that the second components are applied to the first components, so that there is little or no slowing of the vehicle that could be perceived by the driver.
According to the present invention, a quantity describing the operation of the accelerator pedal is taken into account in the present method in checking on whether the activation condition has been met. The activation condition has been met if the quantity describing the operation of the accelerator pedal indicates that the accelerator pedal has not been operated. This measure ensures that the driver's desire for acceleration is implemented without being affected. In other words, If the accelerator pedal has been operated, i.e., if the driver intends to accelerate, then in this situation the brake actuators are not activated to remove the films. Consequently, the driver's intent to accelerate can be implemented without being affected.
In addition to the quantity describing the operation of the accelerator pedal, additional quantities are also analyzed as part of the activation condition. First, quantities related to operation of the brake actuators are analyzed. One of these quantities describes the operation of the brake pedal, i.e., whether the driver is operating the brake pedal and thus braking measures depending on the driver are being implemented.
Another of these quantities represents operation of the brake actuators independently of the driver. In other words, this quantity indicates whether braking measures are being implemented independently of the driver, as is the case, for example, as part of a yaw rate regulator described in the publication cited above “FDR—Die Fahrdynamikregelung von Bosch” [FDR—driving dynamics control by Bosch] or as part of the traction control described in SAE Paper 870337 cited above. Therefore, the two quantities indicated above are analyzed as part of the activation condition, because it is not necessary to remove the films at the moment when the brake actuators are being operated, whether by the driver or independently of the driver.
Furthermore, a velocity quantity describing the velocity of the vehicle is analyzed. This is done for the following reason. At low velocities, it is much less problematic if the full braking effect is not available from the beginning than at high velocities.
In addition, a quantity representing the operation of the windshield wiper or a sensor for detecting wetness is analyzed. This is done because it is not usually necessary to remove the films until there is wetness.
In summary, the activation condition is met and thus it is necessary to remove the films when:
the quantity describing operation of the accelerator pedal indicates that the accelerator pedal is not being operated, and/or
a quantity describing operation of the brake pedal indicates that the brake pedal is not being operated, and/or
a velocity quantity describing the velocity of the vehicle is greater than a respective threshold value, and/or
a quantity representing operation of the brake actuators independently of the driver indicates that there is operation of the brake actuators independently of the driver, and/or
a quantity representing operation of the windshield wiper indicates that the windshield wiper is being operated, or if a sensor for detecting wetness indicates that there is wetness.
The activation condition is usually met when all the individual conditions listed above are met at the same time. However, this should not be a restriction. It is also conceivable for the activation condition to be met even if only some of these indi
Rychlak Stefan
Wagner Jochen
Butler Douglas C.
Kenyon & Kenyon
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