Abstract: A braking system for a wheeled vehicle includes a pressurized air source (63), an air actuated wheel braking device (51, 59), an operator control (49, 61) for commanding the supply of air to the braking device, an electronic control (19) which responds to vehicle speed and wheel speed to selectively invoking an antilock mode of braking. A control valve (37, 55) responds to the electronic control (19) and the operator control (49, 61) to selectively control the supply of air from the source to the braking device. In the antilock mode, the control valve is initially enabled to release braking pressure and thereafter alternately enabled and disabled to maintain braking pressure at a substantially constant reduced pressure, and subsequently alternately enabled and disabled at a reduced ratio of enabled duration to disabled duration to rebuild braking pressure.

Abstract: The invention relates to an electronically controllable brake booster with a vacuum chamber and a pressure chamber, which are separated from each other by a movable wall, a control valve arrangement which can be actuated by means of an electromagnetic actuation means, and by means of which a pressure difference between the pressure chamber and the vacuum chamber can be adjusted, with the control valve arrangement, as a function of a current flowing through the electromagnetic actuation means, assuming a holding position in which the current ranges between a higher value and a lower value without the control valve arrangement leaving the holding position, a first pressure changing position in which the current is higher than the higher value, and a second pressure changing position in which the current is lower than the low value, characterized in that upon a changeover of the control valve arrangement from the holding position into the first or the second pressure changing position, or upon a changeover from

Abstract: The adaptive brake application and initial skid detection system allows rapid brake application and prevents deep initial skids. Brake pressure is compared with a predetermined threshold brake pressure. Wheel velocity error signals are also generated to indicated the difference between the wheel velocity and a reference velocity signal. A pressure bias modulator integrator responsive to brake pressure signals adjusts the wheel velocity error signals to provide an anti-skid control signal. The pressure bias modulator integrator can also be initialized to the value of the measured brake pressure when the wheel velocity error signals indicate the beginning of a skid. Brake pressure difference signals are generated to indicate the difference between brake pressure and a commanded brake pressure, and an adjusted brake pressure error signal is generated in response to the brake pressure difference signals.

Abstract: The present invention is directed to an anti-skid control system wherein at least a pressure decrease mode for decreasing a hydraulic braking pressure and a pulse pressure increase mode for intermittently increasing the hydraulic braking pressure, with a pressure increasing signal provided in accordance with the braking condition of a vehicle. Peaks of the wheel speed in the pulse pressure increase mode are detected continuously on the basis of a variation of a wheel acceleration relative to a vehicle acceleration. Then, the time when each peak of the wheel speed was detected is set as a rise timing of the pressure increasing signal in the pulse pressure increase mode, and a time period for which the pressure increasing signal outputs is adjusted, on the basis of a variation of the rotating condition of the wheel at the time when the peak of the wheel speed was detected.

Abstract: An antilock brake control device of this invention includes a electronic control device 30 to operate antilock brake control and the hydraulic unit 20 which operates by a control signal from the electronic control device 30, wherein the maximum target amount of slip is preset, the rate of pressure reduction is determined so as to vary the amount of slip along a quadratic curve which regards the predetermined maximum target amount of slip as a extreme value, and the fluid pressure of the wheel cylinder is reduced at the rate of pressure reduction.

Abstract: A process and a device for controlling the brake system of a vehicle, in which in traction control and at the beginning of the control, a braking force build-up independent on the slippage takes place, which is stopped when a sizable braking effect is detected on the spinning wheel. Alternatively or in addition to this system, it is provided that, when the vehicle decelerates in active traction control, the braking force build-up pulses and/or the braking force decrease pulses are determined as a function of the measured slippage of at least one wheel, while outside these areas the pulses are determined so that the increase in braking force takes place in steps with the same change in the braking force.

Abstract: A brake valve control method to control the operation of the brake valves is provided in which an error check can be made with one arithmetic logic unit. Signals from a wheel speed sensor are processed to compute the respective wheel speed, and signals from the wheel speed sensor are counted for a prescribed period to derive an approximate wheel speed. If the difference between the wheel speed and the approximate wheel speed is less than or equal to a threshold value, then processing to control the valves is continued; if the difference is greater than a threshold value, then processing to control the valves is suspended.

Abstract: The solenoid control valves of a solenoid-operated automotive antilock braking system are cyclically controlled to enable the valves to operate in a stable, partially open position that provides a desired fluid flow while minimizing noise associated with acceleration and deceleration of the controlled fluid. After an incipient lock-up condition is detected and the solenoid valve has been energized to hold and/or permit a partial release of the brake pressure, the solenoid is initially de-energized for a defined interval designed to reduce the current to a scheduled value. In this interval, the solenoid current is re-circulated through a free-wheeling diode for a smooth decay, allowing the valve to slowly open in a smooth and stable fashion. Then the solenoid is pulse-width modulated (PWM) at a frequency and duty cycle designed to maintain the solenoid current at the scheduled value. The interval of PWM is relatively brief to avoid any instability associated with the current pulsation.

Abstract: An anti-lock control method whereby a control period of pressurization/pressure-reduction during anti-lock control is maintained constant. In the anti-lock control method, a control period T(n) from a high peak of a body velocity to a next high peak is measured, a difference between a target control period time (Tset) and the control period time T(n) is obtained when the control period time is shorter than the target control period time (Tset), the difference is added to a current pressurization start delay time Twait(n-1) to obtain a next pressurization start delay time Twait(n), and a next pressurization start time is delayed by the obtained pressurization start delay time.

Abstract: The object to be achieved by the present invention is to improve accuracy in determining whether or not it is necessary to terminate antiskid control and to reduce the frequency with which the control is terminated. The solution proposed by the present invention is to stop operation of a hydraulic pump before it is determined that the antiskid control should be terminated during the duty pressure increase operation, whereby fluid pressure in a wheel brake can be raised to a level of fluid pressure in a master cylinder before it is determined that the antiskid control should be terminated, to continue the antiskid control as long as the wheel tends to be locked and to terminate the antiskid control when the wheel does not tend to be locked.

Abstract: A process is disclosed for restoring brake pressure in a brake of a motor vehicle having an antilock brake system which subjects the brake to a brake regulating cycle. The brake regulating cycle comprises a pressure reduction phase, wherein the brake pressure is reduced from a deregulating pressure P.sub.max to a holding pressure P.sub.min, a pressure maintenance phase, wherein the holding pressure P.sub.min is maintained in the brake, and a pressure restoration phase, wherein the brake pressure in the brake is increased. According to the invention, during the pressure restoration phase the brake pressure is increased with a steep pressure gradient PG.sub.H during a first pressure increase stage until a pressure level P.sub.K is reached. Thereafter the brake pressure is increased with a low pressure gradient PG.sub.N in a second pressure increase stage. The steep pressure gradient PG.sub.H is calculated as a function of P.sub.max and P.sub.min of the last regulating cycle, while the low pressure gradient PG.

Abstract: A processing circuit has a computing cycle divided into several subcycles of uniform duration. The time base values of the last three nulls of a square wave signal produced from the sinusoidal signal of a wheel speed sensor are stored in a register with three places. At the beginning of a subcycle the difference D of the latest and of the oldest time base values stored in the register is formed and in some cases after limiting is converted to a value 1/D and stored, while the previously stored oldest value is erased. At the start of a new computing cycle the stored value 1/D is further processed as the new wheel speed.

Abstract: According to the present invention, the gradient of duty pressure increase can be adjusted to a best possible value even when an M/C pressure has varied. For example, duty ratio is set to a first set value when a difference between the M/C pressure and a wheel locking pressure is equal to or larger than a predetermined value and to a second set value for a longer pressure increase duration when the difference is smaller than the predetermined value. Then, a brake fluid pressure control valve is operated so that the duty pressure can be increased according to the duty ratio.

Abstract: A processing circuit has a computing cycle divided into several subcycles of uniform duration. The time base values of the last three nulls of a square wave signal produced from the sinusoidal signal of a wheel speed sensor are stored in a register with three places. At the beginning of a subcycle the difference D of the latest and of the oldest time base values stored in the register is formed and in some cases after limiting is converted to a value 1/D and stored, while the previously stored oldest value is erased. At the start of a new computing cycle the stored value 1/D is further processed as the new wheel speed.

Abstract: A vehicle anti-skid control device includes an inlet valve and an outlet valve which can each open and close, thereby selectively applying hydraulic brake pressure to a wheel of a vehicle, along brake lines connected thereto. An electronic control device applies electronic signals to selectively open and close the inlet and outlet valves. The waveform of the signals is configured to operate the inlet valve in such a way as to prevent sudden changes in the brake pressure.

Abstract: An anti-skid braking system for wheeled vehicles having fluid actuated brakes associated with the vehicle wheels, has speed sensors associated with the vehicle wheels, a control device responsive to speed signals from the speed sensors to actuate a pressure dump device to periodically release the fluid pressure applied to the brake of any wheel which is determined to be about to lock and to later re-apply the actuating pressure to that brake when the tendency of that wheel to lock has reduced, pulsing of the pressure dump device at intervals during the pressure re-apply phase to cause a repeated interruption to the re-application of pressure to that brake. The pulse timing of the pulsing of the pressure dump device is controlled by the occurrence of wheel angular deceleration being determined to be equal to or in excess of a predetermined threshold value, the magnitude of which is dependent upon events from the previous anti-lock braking cycle.

Abstract: An anti-lock controller is used in an anti-lock control system for detecting a locked condition of a wheel of a vehicle based on wheel rotation speed signal which are pulse signals. The anti-lock controller is provided with a malfunction detector constructed by a soft ware. This malfunction detector includes an interrupt detection function to produce an interrupt signal on receipt of the pulse signal. At the same time, the controller suspends current operations and transfers control thereof to a routine for detecting the locked condition of the wheel. A malfunction determination function is prepared for determining that the anti-lock controller malfunctions when the interrupt signal is absent with a detection of the pulse signal.

Abstract: In a method and device for identifying a pressure variable, in particular in a brake system, the pressure difference is estimated on the basis of a pressure gradient and the actuation duration of a solenoid valve.

Abstract: A braking force control apparatus for use with an automotive vehicle supported on road wheels each of which has a wheel cylinder for applying a braking force to the corresponding road wheel in response to a fluid pressure introduced thereto. The fluid pressure is controlled by a solenoid valve which is movable between open and closed positions in response to a control signal having a variable duty ratio. The duty ratio of the control signal is changed at predetermined intervals of time to move the solenoid valve in a plurality of steps toward the closed position.

Abstract: In an antiskid brake system that increases or decreases a wheel cylinder pressure according to a wheel speed and vehicle speed, an algorithm applied to pressure increase after pressure decrease is improved. A first target pressure increase amount is computed based on the wheel speed and vehicle speed, and a second target pressure increase amount is computed based on a total pressure decrease amount when pressure is decreased. The wheel cylinder pressure is then increased according to the first target pressure increase amount when an elapsed time from the start of pressure decrease to the start of pressure increase, is longer than a predetermined value, and according to the second target pressure increase amount when the elapsed time is shorter than the predetermined value. In this way, increase of slip amount due to excessive pressure increase is prevented.

Abstract: A control method and system for a vehicle anti-lock brake system to provide for recovery from premature activation of the vehicle anti-lock brake system. The control system includes a microprocessor and accompanying components to perform the control method steps of generating an input signal representing a vehicle wheel velocity, processing the input signal to determine a wheel slip duration, comparing the wheel slip duration to a slip duration threshold, generating a premature activation recovery control signal when the wheel slip duration fails to exceed the slip duration threshold, and performing premature activation recovery control of the anti-lock brake system in response to the premature activation recovery control signal.

Abstract: A brake pressure controller, responsive to a wheel speed sensor and coupled to a brake, performs a cyclic control of pressure applied to the brake. A brake pressure cycle includes a pressure apply stage and a pressure dump stage having activation conditions based upon a slip threshold parameter. A predetermined base threshold quantity is modified in dependence upon a measured time duration of the pressure dump stage and/or a slip depth error quantity so that a greater amount of slip is added to the base slip threshold when braking on a deformable surface than when braking on a non-deformable surface.

Abstract: A method and system for controlling an anti-lock brake system cycle rate in a vehicle wherein the cycle includes a primary apply stage and a secondary apply stage in which increasing pressure is applied to the brake. The primary and secondary stages are separated by a hold stage in which a substantially constant pressure is applied to the brake for a time interval which varies as a function of the estimated average vehicle deceleration.

Abstract: Temperature of brake fluid is estimated, and a pressure-increase gradient change ratio Pup, a pressure-reduction gradient change ratio Pdw, and pump-discharge gradient change quantity Ppmp in correspondence with an amount of decline in pump-discharge capacity at the estimated brake-fluid temperature are calculated respectively. These compensation multipliers Pup, Pdw, and Ppmp are variables for obtaining a pressure-increase gradient change ratio, pressure-reduction gradient change ratio, and pump-discharge gradient change quantity identical to a time of normal temperature (i.e., a time of normal temperature when pump-discharge capacity has not declined). Accordingly, a pressure-increase time Tup and pressure-reduction time Tdw in ABS control and TRC control are calculated utilizing these compensation multipliers to obtain control performance of brake-fluid pressure similar to a time of normal temperature.

Abstract: 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.

Abstract: Improvements in vehicle antilock braking systems of the type having an operator controlled master cylinder (11) and a second source (55, 57) of pressurized hydraulic fluid for selectively supplying rebuild pressure after an antilock event are disclosed. The improved system is selectively operable in one of three braking modes, a normal braking mode (119) where braking force is proportional to an operator brake pedal pressure, an enhanced anti-skid braking mode (69) where braking force may be maintained at a maximum nonskid level, and a conventional anti-skid braking mode (71) where braking force follows a cyclic pattern of fluid pressure bleed and build. The system includes circuitry (17, 19, 35, 37, 93, 95) for determining the speed of each wheel and an arrangement (59) operable independently of any vehicle wheels for determining vehicle deceleration. This comparison normally invokes the enhanced anti-skid braking mode.

Abstract: An anti-skid braking system for wheeled vehicles having fluid actuated brakes associated with the vehicle wheels, speed sensors associated with the vehicle wheels and a cyclically operating control device which is responsive to speed signals from the speed sensors to actuate a pressure dump device to periodically release the fluid pressure applied to the brake of any wheel which is determined to be about to lock and to later re-apply the actuating pressure to that brake when the tendency of that wheel to lock has reduced, and wherein the pressure dump phase is arranged to be cancelled during wheel-lock when the aggregate dump time for the current cycle exceeds a limit value based upon a weighted-average dump time of previous cycles.

Abstract: In an anti-lock braking system in which pressure is reduced in pulses separated by pressure maintenance phases, the duration of the first maintenance phase is dependent upon the vehicle deceleration and the wheel slip. A second pressure reduction pulse is triggered only when the wheel acceleration is less than a predetermined low threshold.

Abstract: The present invention relates to an improved antiskid control apparatus for vehicles. When the front wheel on either one of the right and left sides is antiskid-controlled, this apparatus detects whether the road surface is in the condition of split .mu. in which the road surface friction coefficient is different between the right and left wheels by more than the prescribed value. When the road surface is found to have a split .mu. condition, antiskid control should be implemented on the front wheel mentioned above. To control the rise in brake fluid pressure, the other front wheel must then be shifted in whatever direction facilitates control of the threshold value. In other words, even if a wheel does not attain a sufficient coefficient of surface friction, antiskid control is needed to control easily the rise in brake fluid pressure. A large side force is applied continuously to the vehicle, thereby reducing slippage and cancelling the yaw moment.

Abstract: Methods for brake pressure control in a vehicular antilock brake system wherein brake pressure is restored to within a window of peak brake pressure after a reduction in pressure in response to a forced departure during vehicle braking. In a preferred embodiment, the pressure reduction is adaptively controlled. The vehicle has a plurality of wheels and each wheel has brake. The method includes increasing brake pressure at a wheel so as to attain a prereduction peak brake pressure, and initiating a pressure reduction mode of operation wherein brake fluid flows from the brake of the wheel. The method also includes restoring the brake pressure at the wheel to the desired brake pressure after termination of the pressure reduction mode of operation without making actual brake pressure measurements.

Abstract: 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.