Aisin Seiki Kabushiki Kaisha

Toyota Jidosha Kabushiki Kaisha

Aisin Seiki K.k.

Toyota Jidosha Kogyo Kabushiki Kaisha

Seiko Koki Kabushiki Kaisha

Aisin Seiki Company, Ltd.

Toyota Jidosha K.k.

Aisin Seiki Kaibshiki Kaisha

Kazutaka Kuwana

Tsuyoshi Yoshida

Hiroyuki Ichikawa

Nobuyasu Nakanishi

Kenji Tozu

Masaru Kamikado

Kuniaki Okamoto

Tatsuo Sugitani

Kazunori Sakai

Hiroaki Takeuchi

Shinsuke Sakane

Hiromu Kuromitsu

Masahiro Inden

Takashi Hida

Tomohiko Hosoda

Hiroyuki Amano

Ken Asami

Masanobu Ishikawa

Noboru Noguchi

Tsutomu Mitsui

Tadaaki Hashiride

Kouji Hirao

Satoshi Itabashi

Michiharu Nishii

Masahiro Ueda

Yoshiharu Adachi

Shoji Kawata

Shinji Kawai

Masamoto Ando

Hiroshi Nakashima

Takashi Nagashima

Tsukasa Watanabe

Takehiko Fushimi

Yasuo Kuwabara

Genji Mizuno

Teiji Okuyama

Masanori Hirose

Katsuki Takayama

Jun Funakawa

Hidemori Tsuka

Seiji Nonoyama

Akemi Takada

Tetsuya Morita

Hiroshi Kuromitsu

Kohji Hiro

Takayuki Tomohara

Tetsuya Miyachi

Yasuo Noda

Daiju Nomura

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 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 pressure control means. On the basis of a wheel speed of the road wheel detected by detecting means, a wheel acceleration and an estimated vehicle speed are calculated. A difference between the wheel speed and the estimated vehicle speed is calculated, and an integrated value thereof during a certain period is obtained. Then, a wheel lock rate indicative of a locking condition of the road wheel is set on the basis of the integrated value at least. Means is provided for setting an increasing time for increasing the hydraulic braking pressure and a holding time for holding it as it is with a proportion therebetween determined in response to a relationship between the wheel acceleration and the wheel lock rate, or setting a decreasing time and the holding time as well. The pressure control means is arranged to alternately increase and hold the hydraulic braking pressure in response to the increasing time and holding time, or decrease and hold it as well.

Anti-skid control system for an automotive vehicle that includes an

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 braking forces applied to road wheels with hydraulic braking pressure supplied from a master cylinder to wheel brake cylinders and controlled in response to braking condition of the road wheels. A wheel speed of at least one of the road wheels is detected to provide an output signal corresponding to the wheel speed. A hydraulic braking pressure supplied to each of the wheel brake cylinders is increased, held or decreased in response to a variation of the wheel speed. The hydraulic braking pressure supplied to each of the wheel brake cylinders is increased in response to a proportion between an increasing time for increasing the pressure and a holding time for holding the pressure. The increasing time provided for one of at least two wheel brake cylinders is prohibited from being coincident with the increasing time provided for the other. Thus, the timing for increasing the hydraulic braking pressure in one of the wheel brake cylinders will not coincide with that in the other.

The invention is directed to an anti-skid control system for controlling a braking force applied to each of the road wheels with a hydraulic braking pressure supplied to a wheel brake cylinder through pressure control means. A wheel speed of each of the road wheels is detected. Then, an estimated vehicle speed for each of the road wheels is calculated on the basis of the wheel speed and a decreasing rate of estimated vehicle speed for at least one of the road wheels other than the road wheel for which the estimated vehicle speed is being calculated. The estimated vehicle speed is, therefore, prevented from being set largely below the actual speed of the vehicle. The pressure control means is provided for increasing, holding or decreasing the hydraulic braking pressure in response to a result of comparison between the estimated vehicle speed and the wheel speed for each of the road wheels.

A brake control device for vehicles includes a master cylinder, a plurality of wheel cylinders, and an anti-lock control apparatus disposed between the master cylinder and the wheel cylinders of at least one hydraulic circuit. The anti-lock control apparatus includes a hydraulic pump, a reservoir and a changeover device which is selectively changed over at least between a first condition which permits an increase in the hydraulic pressure of the wheel cylinders of at least one hydraulic circuit and a second condition which permits an decrease in the hydraulic pressure of the wheel cylinders of at least one hydraulic circuit in response to the locking condition of the road wheels. The hydraulic pump includes a housing, a slidable piston device for defining a pump chamber which is communicated with the reservoir and the changeover device at a side of one end thereof in the housing, an inlet check valve disposed between the pump chamber and the reservoir for permitting fluid communication from the reservoir to the pump chamber and for interrupting fluid communication from the pump chamber to the reservoir, an outlet check valve disposed between the pump chamber and the changeover device for permitting fluid communication from the pump chamber to the changeover device and for interrupting fluid communication from the changeover device to the pump chamber, and a piezo element for reciprocating the piston device disposed at the other end of the piston device.

Anti-lock brake circuit with a piezo hydraulic pump and changeover valve

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.

An anti-skid controlling apparatus which establishes the time allocation for the pressure decreasing time and decreased pressure holding time, as well as the time allocation for the pressure increasing time and increased pressure holding time, in accordance with the correlation between wheel acceleration and wheel lock level. The brake fluid pressure in the wheel cylinder is increased, held constant or decreased as needed. This makes it possible to establish optimal time allocation settings allowing for the pressure increasing and decreasing characteristics of the pressure controlling device. In turn, brake fluid pressure control is kept optimally provided independent of various factors that would affect the brake fluid pressure in the wheel cylinder. Thus the apparatus is suitable for use on board diverse kinds of vehicle with diverse characteristics.

Anti-skid controlling apparatus

The invention is directed to an arrangement for controlling a braking force applied to each of right and left road wheels individually depending upon a braking condition, with a hydraulic braking pressure supplied to each of wheel brake cylinders through actuators respectively. The actuators are controlled by the braking force control system wherein output signals of wheel speed detectors are fed into first and second detecting circuits respectively by which the braking conditions of the road wheels are detected. Then, the detected signals are fed into a first driving circuit which produces driving signals fed to the actuators on the basis of an output signal fed from either of the detectors for one road wheel having a tendency to be locked first. One of the actuators provided for the road wheel on the road surface of the lower coefficient of friction is driven by a driving signal fed from the first driving circuit, whereas the other actuator is driven by a driving signal which is fed from the first driving circuit and modified thereafter by the second driving circuit in response to a value representing a vehicle speed so as to increase the hydraulic braking pressure rapidly when the vehicle is driven at low speed, consequently shortening the stopping distance.

Anti-skid control system for a road surface having a split coefficient

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

An anti-skid control system for an automotive vehicle is provided with an actuator which is disposed in a hydraulic circuit between a hydraulic pressure generator and a wheel brake cylinder. The actuator is operated by an electronic controller so as to control a hydraulic braking pressure supplied to the wheel brake cylinder in response to at least an output of a wheel speed sensor which detects a rotational speed of a road wheel. In the controller, a desired hydraulic pressure is set, and the actuator is operated to control the hydraulic braking pressure to the desired hydraulic pressure. Where the actuator comprises a proportional pressure control solenoid valve connected to the controller which is provided with a resistor for detecting a current fed to the solenoid valve, the desired hydraulic pressure is set in response to the current.

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.

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Toyota, Japan

Kazutaka Kuwana