Tokico, Ltd.

Masaru Sakuma

Toshio Takayama

Susumu Sawano

Kunihiro Matsunaga

Yutaka Kitano

Tohma Yamaguchi

Hirotaka Oikawa

Youichi Kumemura

Hideaki Nagai

Tatsuya Funabashi

Toshi Takayama

A solenoid-controlled valve has first and second valve bodies axially movably provided in a bore of a cylinder. A first spring is interposed between an end of th valve and the first valve body, a second spring is interposed between the two valve bodies, and an electromagnetic force generating device has a movable member which causes the two valve bodies to move in association with each other. Valve opening and closing modes of the two valve bodies are changed in a plurality of stages according to the displacement of the movable member. A restricting portion restricts relative displacement of the two valve. bodies away from each other so that the influence of the urging force of the second spring on the driving force of the electromagnetic force generating device becomes zero in the valve opening and closing mode in the final stage.

Solenoid-controlled valve

A motor-driven brake apparatus has a motor and a ball screw that converts rotational motion of the motor into rectilinear motion of a screw member. A position detector detects a stroke position of the screw member. A controller controls the motor on the basis of the result of detection by the position detector. The controller controls the motor so as to change the clearance between an inner pad (outer pad) and a disk according to vehicle running conditions.

Motor-driven brake apparatus

When a stroke speed exceeds a reference value of a stroke speed threshold value, a solenoid is energized to tract an armature, thereby opening an atmospheric valve independently of the position of a plunger. Consequently, power pistons, together with an output rod, are moved forward by a thrust corresponding to a pressure difference between a constant-pressure chamber and a variable-pressure chamber to perform a full-power braking operation. A reaction-adjusting mechanism contributes to an improvement in safety by functioning in such a way that when the part of the reaction force from the output shaft that is transmitted to an input rod reaches a predetermined value, a boosting ratio is increased, so that the reference value of the stroke speed threshold value can be set high to prevent unnecessary braking.

Braking system

The objective of the present invention is to present a reliable evaluation method for determining whether a moving vehicle is in a stable antiskid control operation or in an unstable antiskid control operation even when there are wheel speed pulsation caused, and a device based on such a method. In the antiskid control apparatuses and the methods of the invention, it is determined that the moving vehicle is in the stable control when the wheel acceleration being generated while the wheel speed is decreasing exceeds a predetermined threshold value, and also determined that the moving vehicle is in the unstable control when the wheel acceleration is below the threshold value. In another antiskid control apparatus and the method of the invention, it is determined that moving vehicle is in the unstable control or in the stable control basis on the changes in the wheel slipping rate with respect to the coefficient of friction between the wheel and a road.

Evaluation and control method and apparatus for vehicle operation of

In the disclosed method and apparatus, the brake fluid pressure in a wheel cylinder is reduced and thereafter it is re-increased so that the braking torque is linearly increased with respect to time due to the anti-skid control and the rate of change of the coefficient of road surface friction with respect to the wheel slip rate is determined while the brake fluid pressure is thus re-increased so that the brake fluid pressure is re-relieved when said rate of change comes below a predetermined threshold. The method of invention calculates the rate of change by achieving, when there is no pulsatory change in the wheel speed during the re-increase of the brake fluid pressure the steps of: obtaining the wheel speed at the point of time which is the midpoint of first and second points of time giving the same wheel speed, subtracting from this wheel speed at the midpoint the wheel speed at the first point of time or at the second point of time, increasing by four times the result of subtraction and dividing this increased result by the time period between the first and second points of time, obtaining a reciprocal of the result of the division, subtracting from this reciprocal, a reciprocal of the wheel acceleration at the first point of time, multiplying the result of the subtraction with the vehicle speed and a value which is attained by dividing the rate of increase of the braking torque at the midpoint by the product of the wheel load and the effective wheel radius, and then increasing the result of the multiplication by three times.

Method and apparatus for anti-skid control

The present invention comprises a modulator which controls the brake fluid pressure which is provided to the hydraulic systems which extend from the brake fluid pressure source to each wheel, and a controller which controls said modulator. The controller lowers the rate of the increase in brake fluid pressure in one of the wheels on the opposite right or left side of a wheel which is being antiskid controlled, and by thus operating the modulator and maintaining or decreasing brake fluid pressure, relaxes the conditions for the initiation of antiskid control. Concretely, it lowers the threshold values for the slip ratio and the deceleration in the wheel speed, which are used in the decision to initiate antiskid control.

Antiskid control apparatus

In the present invention, the conditions necessary for the change from the reducing-pressure mode to the holding pressure mode are changed based on the length of the period of instability from the beginning of wheel slippage to the stopping of this slippage, and the length of the period of continued severe locking in which the slip ratio of the wheel exceeds a certain fixed value. Therefore, even when there is a disturbance in the form of roughnesses in the road surface or the like, this is determined to be a temporary phenomenon and the switching of the setting from the reducing-pressure mode to the holding pressure mode can take place in a reliable manner, and the usual, stable braking power can be achieved in correspondence with the relationship between the road surface and the tires.

Antilock brake control apparatus

In an antiskid control device comprising detectors for measuring circumferential velocities of a plurality of wheels an actuator for operating a braking oil pressure for each of the wheels and an electric circuit for calculating friction coefficients on the road surfaces, to which the wheels are in contact, calculating aimed wheel circumferential velocities from the friction coefficients on the road surfaces and operating the actuator such that each of the aimed wheel circumferential velocities and each of the measured wheel circumferential velocities coincide with each other, the electrical circuit operates the actuator by setting individual aimed wheel circumferential velocities for the plurality of wheels from a vehicle deceleration calculated from an average value for the friction coefficients on the road surfaces with which a plurality of wheels are in contact, respectively, and the slip ratio for each of the plurality of wheels.

Antiskid control device

An antiskid control device, comprising a detector for detecting a circumferential speed of wheel, a valve for controlling a hydraulic braking force to the wheel, and an electronic control circuit for determining a ratio of a mean value of rising rates and a mean value of lowering rates of the circumferential speed of wheel in a predetermined period of time in every antiskid control cycle for rise and drop of the circumferential speed of wheel based on a detection signal from the detector, for estimating a coefficient of friction of road surface from the ratio to correct the target circumferential speed of wheel based on the estimated coefficient of friction of road surface, and for operating the valve means to let the wheel circumferential speed approach the corrected target circumferential speed.

An anti-skid control device comprising a detector for detecting a wheel circumferential velocity, an electromagnetic valve for controlling a hydraulic braking pressure for a wheel and an electronic control circuit for preparing an aimed wheel circumferential velocity based on a detection signal from the detector during a time of braking and controlling the electromagnetic valve so as to bring the wheel circumferential velocity closer to said aimed wheel circumferential velocity.

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Yamanashi-ken, Japan

Masaru Sakuma