Aisin Seiki Kabushiki Kaisha

Aisin Seiki K.k.

Toyota Jidosha Kabushiki Kaisha

Toyota Jidosha K.k.

Aisin Seiki Kaibshiki Kaisha

Kuniaki Okamoto

Hiroyuki Ichikawa

Kazutaka Kuwana

Tsuyoshi Yoshida

Masaru Kamikado

Nobuyasu Nakanishi

Tatsuo Sugitani

Kazunori Sakai

Satoshi Itabashi

The anti-skid control system is capable of performing highly reliable anti-skid control through its accurate estimation of the vehicle speed and proper compensatory control even when sharp braking occurs or in the brake fluid pressure control on road surfaces with a low coefficient of friction likely to cause considerable fluctuations in wheel acceleration. The anti-skid control system is provided with a fluid pressure generating device, a fluid pressure controlling device, a wheel velocity detecting device, a standard speed setting device, a fluid pressure controlling mode setting device which sets either the pressure decrease mode or the pressure hold mode when the wheel velocity declines to a level lower than the standard speed and sets the pressure increase mode when the wheel velocity is equal to or higher than the standard speed. A maximum inflection point detecting device detects the maximum inflection point indicating the maximum value for the shift of the wheel velocity mentioned above from an increase to a decrease when the wheel velocity is not any lower than the standard speed. A fluid pressure controlling mode correcting device switches from the pressure increase mode mentioned above to either the pressure hold mode or the pressure decrease mode when the wheel velocity becomes equal to or higher than the standard speed and also becomes equal to or higher than the wheel velocity at the maximum inflection point.

Anti-skid control system

The anti-skid control system is constructed with a brake fluid pressure source for generating brake fluid pressure at high and low levers, a switching valve feeding either high pressure or low pressure to the wheel cylinders, a wheel velocity detecting device sensing the driving wheel rotating speed, an acceleration detecting device detecting the vehicle acceleration and a first arithmetic operation device for finding the estimated vehicle speed and the wheel rotating acceleration based on the wheel velocity detected by the wheel velocity detecting device and the vehicle body acceleration detected by the acceleration detecting device. A brake fluid pressure controlling device is provided for increasing, decreasing or maintaining the brake fluid pressure in the wheel cylinders, controlling the switching valve on the basis of wheel velocity, estimated vehicle speed, and wheel rotating acceleration. A second arithmetic operation device marks the minimum and maximum values in the wheel velocity after a brake fluid pressure reduction based on the wheel velocity detected by the wheel velocity detecting device calculates the recovery acceleration in the wheel velocity in the shift from the minimum value to the maximum value and compares the recovery acceleration with the set value. A vehicle acceleration correcting device corrects the vehicle body acceleration detected by the acceleration detecting device so as to set the vehicle body acceleration at a smaller value in case the recovery acceleration is less than the set value.

Anti-skid brake control system based on acceleration detection

An anti-skid control system for an automotive vehicle is provided with an actuator which is disposed in a hydraulic circuit between a pressure generator and a wheel brake cylinder. The actuator is arranged to control the hydraulic braking pressure applied to the wheel brake cylinder. In response to a wheel speed detected by a wheel speed detector, it is determined in an electronic control unit whether a condition for decreasing the braking pressure is effected. When this condition is effected, the decrease mode is provided in the control unit. When a predetermined period of time lapses after the decrease mode is initiated, the decrease mode is turned to a pressure control mode for applying the braking pressure to prevent the road wheel from being locked. When the condition is not effected during the predetermined period of time after the decrease mode is initiated, the decrease mode is turned to a direct supply mode for directly communicating the pressure generator with the wheel brake cylinder. Consequently, the lack of braking force caused by the delay of timing for decreasing the hydraulic braking pressure due to an erroneous detection of a locking condition of the road wheel on a rough road is effectively prevented.

Anti-skid control system for an automotive vehicle

The invention is directed to an arrangement for controlling a braking force applied to a road wheel, with a hydraulic braking pressure supplied to a wheel brake cylinder through an actuator. A standard speed is set on the basis of a wheel speed detected by a wheel speed sensor, and a peak of the wheel speed changing from increase thereof to decrease thereof is detected. A coefficient of friction of road surface is determined on the basis of a vehicle acceleration detected by an acceleration sensor. The actuator is controlled according to a pressure control mode selected from a decrease mode for decreasing the pressure, a hold mode for holding the pressure, a first increase mode for increasing the pressure when the wheel speed exceeds the standard speed, and a second increase mode for increasing the pressure when the wheel speed exceeds the peak of the wheel speed. The first increase mode is selected when the coefficient of friction exceeds a predetermined value and the standard speed exceeds a predetermined speed. The second increase mode is selected when the standard speed is lower than the predetermined speed.

Anti-skid control system having dual pressure increase modes

The anti-skid control system is provided with wheel velocity sensors only for the driving wheels and yet is capable of performing the anti-skid control through its accurate estimation of the vehicle speed and proper compensatory control even when sharp braking occurs immediately upon the release of the accelerator after the occurrence of acceleration slip. The anti-skid control system is capable of starting the anti-skid control with certainty even when the braking operation is not detected because of a failure in the operation of the brake switch. The system is provided with a fluid pressure generating device, a fluid pressure controlling device, a brake operation detecting device, an acceleration detecting device, a wheel velocity detecting device, a braking force controlling device, a brake force correcting device and an acceleration slip detecting device.

The invention is directed to an anti-skid control system for controlling a braking force applied to a road wheel with a hydraulic braking pressure supplied to a wheel brake cylinder through a pressure control valve controlled by an electronic controller. On the basis of a wheel speed of the road wheel detected by a wheel speed sensor, the controller calculates an estimated vehicle speed and sets a reference speed on the basis thereof. In the controller, the wheel speed is compared with the reference speed, and in response to a result of comparison the hydraulic pressure supplied to the wheel brake cylinder is controlled by the pressure control valve. Through an adjustment by the controller, the hydraulic braking pressure is decreased in response to a change of difference between the wheel speed and the estimated vehicle speed for a certain period of time. The controller may be arranged to calculate an integrated value of the difference between the wheel speed and the estimated vehicle speed, to compare a value which is obtained by subtracting the integrated value from the wheel speed, with the reference speed, and to decrease the hydraulic pressure in the wheel brake cylinder in response to the result of comparison.

The invention is directed to an arrangement for monitoring a road condition which determines the coefficient of friction of the road surface on the basis of a signal corresponding to an acceleration of a vehicle detected by an acceleration sensor. The signal is converted into one of at least two predetermined values by conversion means in response to a magnitude of the acceleration every cycle of a predetermined time period. The converted value is summed up by summing means by a predetermined number of consecutive cycles to provide a total value in the last cycle thereof which is stored in memory means. Then, in determination means, one of at least two standard values is selected in response to the condition of increase or decrease of the total value in the present cycle provided by the summing means as compared with the total value in the previous cycle stored in the memory means. And, the total value in the present cycle is compared with the above one of at least two standard values to produce a road condition signal corresponding to a result of comparison which represents the coefficient of friction of the road surface. The present system is applicable to an anti-skid control system for an automotive vehicle.

Road condition monitoring system

The anti-skid control system is provided with wheel velocity sensors only for the driving wheels and is capable of performing the anti-skid control through its accurate estimation of the vehicle speed and proper compensatory control even when sharp braking occurs immediately upon the release of the accelerator after the occurrence of acceleration slip. The anti-skid control system is capable of starting the anti-skid control with certainty even when the braking operation is not detected because of a failure in the operation of the brake switch. The system is provided with a fluid pressure generating device, a fluid pressure controlling device, a brake operation detecting device, an acceleration detecting device, a wheel velocity detecting device, a braking force controlling device, a first estimated vehicle speed setting device and a second estimated vehicle speed setting device.

Growing community of inventors

Nagoya, Japan

Kuniaki Okamoto