Abstract: A brake fluid pressure control device has a wheel brake fluid pressure control valve having a discharge valve and provided in a main fluid passage extending from a master cylinder to wheel brakes. A discharged fluid reservoir is provided to temporarily store the brake fluid discharged from the discharge valve. A pump is provided to pump the brake fluid out of the discharged fluid reservoir and return it to the main fluid passage. A fluid supply passage branches from the main fluid passage at a point upstream of a flow return point from the pump and extends to the discharged fluid reservoir. A traction control changeover valve is provided to checking a fluid flow from the flow return point toward the master cylinder during traction control. A shutoff valve is provided to check a fluid flow from the fluid supply passage to the discharged fluid reservoir while the pressure in the master cylinder is being applied.

Abstract: A zero-point correction device for a gravity-type accelerometer employed in a vehicle having wheels, includes a calculator for calculating an estimated vehicle acceleration Aw based on the wheel speed, and a detector for detecting a gravitationally detected acceleration Am based on said gravity-type accelerometer. A subtractor is provided for subtracting a correction amount Ao obtained in each operation cycle from the gravitationally detected acceleration Am to produce a corrected acceleration Ac which is a corrected version of said gravitationally detected acceleration Am. The correction amount Ao for the present operation cycle is obtained by adding to the correction amount Ao obtained in the previous cycle, a value commensurate with a difference between the estimated vehicle acceleration Aw and the corrected acceleration Ac.

Abstract: A wheel speed correction device for use in a vehicle corrects for the change of the circumferential wheel speed caused by variations in the wheel tire diameter, differences in the paths of the left and right wheels when the vehicle turns, and/or abnormal slipping between the tire and the road surface. The wheel speed correction device has a device for measuring a wheel rotation angular speed of each wheel, a device for correcting a coefficient representing a tire diameter and producing a corrected coefficient for each wheel, a device for calculating, from the measured angular speed, a diameter-corrected wheel speed using the corrected coefficients, a device for obtaining a turning correction amount from a difference between diameter-corrected wheel speeds of the left and right wheels, and a device for correcting the diameter-corrected wheel speed using the turning correction amount.

Abstract: A brake fluid pressure control device has a wheel brake fluid pressure control valve including a discharge valve provided in a main fluid passage extending from a master cylinder to wheel brakes. A discharged fluid reservoir is provided to temporarily store the brake fluid discharged from the discharge valve. A pump is provided to pump the brake fluid out of the discharged fluid reservoir to return it to the main passage. A fluid supply passage branches from the main passage at a point upstream of a flow return point from the pump and extends to the discharged fluid reservoir. A traction control changeover valve is provided to check a fluid flow from the flow return point toward the master cylinder during traction control. A shutoff valve is provided to check a fluid flow from the master cylinder to the discharged fluid reservoir through the fluid supply passage while the master cylinder is pressurized.

Abstract: A vehicle travel direction estimating device is provided which has a wheel speed calculating device for calculating the speed and acceleration Aw of a vehicle. In addition, a gravity-type accelerometer is provided for producing a gravitationally detected acceleration Am. When both Aw and Am increase or decrease simultaneously, it is determined that the vehicle is travelling forward, and when one of Aw and Am increases while the other decreases, it is determined that the vehicle is travelling in reverse. To detect this feature, a calculating system is provided to form differential values Daw and Dam from accelerations Aw and Am. The vehicle travel direction is estimated using the differential values Daw and Dam.

Abstract: A device for calculating estimated vehicle acceleration and speed for use in estimating vehicle speed Vv and vehicle acceleration Av, such that a subservient acceleration Az based on the wheel speed is used when As>Az during acceleration or when As<Az during deceleration, while the substitute acceleration As based on the gravity-type accelerometer is used in place of Az when As<Az during acceleration or when As>Az during deceleration.

Abstract: A flow control valve includes a sleeve formed with an inlet port and an outlet port and a spool slidably mounted in the sleeve. A fluid passage having an orifice connects a high-pressure end and a low-pressure end of the spool. An annular seal is liquid-tightly fitted in an annular groove formed in the inner periphery of the sleeve and extends into an annular groove formed in the outer periphery of the spool with a gap left therebetween. A biasing elements is provided to bias the spool in a direction opposite to the direction in which the fluid pressure differential between both ends of the spool tends to urge the spool. A seal can be effected by the annular seal and a shoulder portion of the spool defining the annular groove thereof. The seal, however allows fluid communication from the inlet port toward the outlet port through the orifice to be established with the movement of the spool.

Abstract: A brake system having at least one static pressure line having a static pressure generator. The static pressure line has a bilateral driving piston having one end thereof acted on by a brake pressure and the other end acted on by a control pressure, a changeover valve capable of shutting off the fluid flow from the static pressure generator to the wheel brake, a flow control valve for controlling the control pressure of the driving piston, and an electronic control unit for giving a control command to the flow control valve. The driving piston is controlled so as to keep its predetermined neutral position while the manual input is zero, and, in a normal operation phase, so as to move in such a direction as to reduce the capacity of the static pressure line so that a manual control stroke will be shortened in a predetermined relationship with deceleration or with other braking factors closely associated with the deceleration.

Abstract: A brake system has a manually controlled brake pressure generator, independent controlled brake circuits each having a wheel brake and a flow control valve for electronically controlling the pressure of the wheel brake, a dynamic pressure source necessary for the pressure control by the flow control valve, a reservoir, a sensor such as a wheel speed sensor, and an electronic control unit. A pair of check valves for introducing and returning fluid are provided in parallel to each other between an output circuit of the brake pressure generator and each controlled brake circuit. A solenoid changeover valve for antilock is provided between the output circuit of the brake pressure generator and the check valves for introducing fluid to close the line during antilock control.

Abstract: A brake system wherein an auxiliary power based on a manual force is electronically controlled to control the braking force so as to obtain braking effects corresponding to a manual control input. The braking force is controlled so that a vehicle deceleration corresponding to the control input can be obtained when the control input is equal to or greater than a comparatively small predetermined control input value Lo. When the control input is smaller than Lo, the braking force is controlled so that the vehicle acceleration will not exceed a value corresponding to the control input.

Abstract: A wheel speed control apparatus for controlling a braking force and/or a driving force transmitted to wheels maintains the difference between the peripheral speed of each of the wheels and the vehicle running speed or an inferred value thereof at a value approximating the optimum value. The apparatus includes a normal control that detects and controls the increase or incipient increase of the difference over the absolute value using a differential value of the difference and difference or the rotational speed of the wheels. An integrating control detects and controls the continuation for a certain period of slightly excessive tendency of the absolute value of the difference, by comparing with a predetermined threshold value one of values which is smaller than the value with which, when the differential value is zero, the normal control would determines the excessive different only with the absolute value.

Abstract: A fluid pressure controller having a housing having a first port and a second port, and a spool axially slidably mounted in the housing. First and second chambers are defined between opposing ends of the spool between the spool and the housing. The controller further has an electricity/power converter for applying to the spool an axial driving force corresponding to the magnitude of an electric command, and a spring for holding the spool in its initial position when the value of the electric command to the converter is zero. A variable-size orifice is provided to separately control communications between the first chamber and the first port depending upon the axial position of the spool. The second chamber normally communicates with the second port. A fixed-size orifice and a relief valve are provided parallel to each other in passages connecting the first and second chambers.

Abstract: A fluid pressure controller has a houisng including an input port, a discharge port and an output port, and a spool is axially slidably mounted in the housing. First and second chambers are defined at opposing ends of the spool by the spool and the housing. Ring valve members are mounted on the spool at axial spaced locations to define oppositely oriented variable-size orifices for pressure increase and pressure reduction. They are adapted to separately control communications between the first chamber and the input port and between the first chamber and the discharge port depending upon the axial position of the spool and to close both communications when the spool is in its closed position. Thus the pressure controller can be freely changed between providing pressure increase, pressure reduction and pressure hold.

Abstract: A brake device has a static pressure line for generating brake fluid pressure in at least one line by manual operation, a dynamic pressure source such as a power pump, an electronic control unit, a stroke sensor for detecting the control input of the manual operation, a unit for measuring or estimating the vehicle deceleration, a first control valve adapted to alternately supply and not supply pressure fluid from the dynamic pressure source to the static pressure line, and a second control valve adapted to alternately discharge and not discharge pressure fluid from the static pressure line to a reservoir.

Abstract: An electronically controlled brake device for controlling a brake pressure according to a manual input. While the dynamic pressure line is functioning normally, the dynamic pressure acts on one end of a push rod associated with a brake pedal to give such a force as to counteract the control input to the brake pedal. If the dynamic pressure line fails, the push rod comes into contact with a dynamic pressure piston to transmit the control input force to a master cylinder. An electronic pressure control valve is provided to adjust the connection of the dynamic pressure source with a reservoir and with a dynamic pressure chamber in response to the commands of an electronic control unit so that its output pressure will be in a predetermined relationship with the pedal stroke. Thus in normal conditions, a desired deceleration is obtained with a shorter pedal stroke and in the failure of dynamic pressure, a minimum deceleration is obtained with a lighter pedal force.

Abstract: A fluid pressure controller includes a housing formed with an input port, a discharge port and an output port, a spool axially slidably mounted in a bore provided in the housing, a spring for keeping the spool in its inoperative position, and an electricity/power converter for imparting to the spool an axial driving force corresponding to the amplitude of an electric signal applied to the converter. First and second chambers are defined by the inner peripheral surface of the bore and both end faces of the spool. The spool is formed with an internal passage connecting the first and second chambers together and having its intermediate portion throttled to form a fixed-size orifice and with a peripheral channel at a point between the first chamber and the fixed-size orifice so as to communicate with the internal passage. The output port normally communicates with the second chamber.

Abstract: An anti-lock brake control system for an automobile is provided with a master cylinder, a main fluid passage communicating between the master cylinder and at least one wheel brake, a recirculating passage branched off from the main fluid passage for recirculating a fluid medium back to the main fluid passage, a pump disposed in the recirculating passage for recirculating the fluid medium, a pressure regulator for reducing or increasing the brake pressure of the wheel brake and an anti-lock modulator for changing the area of the main fluid passage. The modulator is provided with a housing having a fluid chamber, a first port communicating with the master cylinder and a second port communicating with the pump, and with a movable element vertically movably accommodated in the fluid chamber. The movable element is normally located at a lower position in the fluid chamber by the gravity and moved upwards by the flow of the fluid medium discharged from the pump.

Abstract: A brake pressure control device for vehicles is arranged in a pipeline connecting a master cylinder (22) and a wheel brake (23) with an electromagnetic directional control valve (24) which is switchable to any one of a plurality of valve positions by electromagnetic force. The electromagnetic directional control valve (24) is switched between a first valve position and a second valve position. Bidirectional flow of fluid is allowed when the electromagnetic directional control valve is in the first valve position. Unidirectional flow of the fluid is allowed but a reverse flow of the fluid is prevented when the electromagnetic directional control valve is in the second valve position.

Abstract: A system (apparatus and method) for measuring a revolution speed of a rotary member improves accuracy by estimating the speed during a unit operation period in response to pulse signals detected from the rotary member. When a pulse signal is not detected, the system obtains the revolution speed by selecting the lesser of a first estimated value and a second estimated value. The first estimated value is determined on the basis of the calculated revolution speed during the previous unit operation period and also the calculated acceleration during that previous operation period. The second estimated value is determined on the basis of a lapse time between a detected time of the last signal and the completion time of the current unit operation period.

Abstract: A reference wheel velocity calculation apparatus for use in an automotive vehicle includes a device for sampling actual wheel velocities detected at a predetermined sampling cycle, a device to select a suitable velocity as the basis of the calculation of reference wheel velocity, and a calculator for calculating an intermediate reference velocity of the present sampling point from the selected wheel velocity by suppressing the variance of intermediate reference velocity within predetermined limit(s). Further, a greater one of the presently sampled selected wheel velocity and a calculated intermediate reference velocity is selected as a quasi-reference wheel velocity which is then smoothed according to index to obtain the reference wheel velocity. The limit of the variance may be changed in regard to the accelerometer provided in the vehicle. Also, the smoothing index may be changed with respect to the factors such as the behavior of the wheel velocity.