Abstract: A turning motion control system for a vehicle includes an actuator, and an actuator control device for controlling the actuator so that an actual turning motion state of the vehicle becomes close to a target turning motion state. The actuator control device is designed so that its control-permitted state and its control-stopped state can be switched from one to another through a switching device operated by a driver. When an air-pressure decreased state detecting device has detected an air-pressure decreased state, the actuator control device carries out the control of the operation of the actuator, irrespective of a switching mode of the switching device. Thus, even if an air-pressure decrease or an abnormality is generated in any of wheels in a state in which the turning motion control by the actuator has been stopped, the stability of the vehicle can be ensured.

Abstract: When a shift position is shifted from an R range to a D range and when the shift position is shifted from the D range to the R range, an electrically-operated parking brake device is automatically cancelled. In this manner, the electrically-operated parking brake device is cancelled without waiting for the depression of an accelerator pedal with a driver's intention to start a vehicle taken into consideration. Therefore, it is possible not only to alleviate a burden on the driver in canceling the electrically-operated parking brake device, but also to prevent an abrupt starting of the vehicle due to the cancellation of the electrically-operated parking brake device while the accelerator pedal is being depressed to transmit a large driving force to driven wheels.

Abstract: A turning motion control system for a vehicle includes an actuator, and an actuator control device for controlling the actuator so that an actual turning motion state of the vehicle becomes close to a target turning motion state. The actuator control device is designed so that its control-permitted state and its control-stopped state can be switched from one to another through a switching device operated by a driver. When an air-pressure decreased state detecting device has detected an air-pressure decreased state, the actuator control device carries out the control of the operation of the actuator, irrespective of a switching mode of the switching device. Thus, even if an air-pressure decrease or an abnormality is generated in any of wheels in a state in which the turning motion control by the actuator has been stopped, the stability of the vehicle can be ensured.

Abstract: An electric parking brake system that includes a parking brake, and an electric motor, wherein the parking brake is activated by the electric motor. Operation of the parking brake is controlled such that a vehicle is decelerated at a target deceleration of a predetermined magnitude when an operation command to operate the parking brake is issued by a driver via an operation switch while the vehicle is running. If a service brake fails while a vehicle is running, when the driver depresses the operation switch to issue the operation command to a parking brake to brake the vehicle, the parking brake is controlled such that the vehicle is decelerated at the target deceleration of the predetermined magnitude set on the basis of the number of times of depressing the operation switch.

Abstract: If a service brake fails while a vehicle is running, when the driver depresses an operation switch to issue an operation command to a parking brake to brake the vehicle, the parking brake is controlled such that the vehicle is decelerated at a target deceleration of a predetermined magnitude set on the basis of the number of times of depressing the operation switch. Consequently, even if the temperature and degree of wear of a friction material of the parking brake vary, the vehicle can be decelerated at the target deceleration at all times, whereby a stable braking effect which is not affected by the conditions of the friction material of the parking brake can be obtained. Moreover, since the magnitude of the target deceleration is set according to the number of times of depressing the operation switch, a deceleration required by the driver can be generated in an ensured fashion.

Abstract: When a shift position is shifted from an R range to a D range and when the shift position is shifted from the D range to the R range, an electrically-operated parking brake device is automatically cancelled. In this manner, the electrically-operated parking brake device is cancelled without waiting for the depression of an accelerator pedal with a driver's intention to start a vehicle taken into consideration. Therefore, it is possible not only to alleviate a burden on the driver in canceling the electrically-operated parking brake device, but also to prevent an abrupt starting of the vehicle due to the cancellation of the electrically-operated parking brake device while the accelerator pedal is being depressed to transmit a large driving force to driven wheels.

Abstract: An electrically operated parking brake apparatus that includes an electric motor and a screw mechanism The screw mechanism includes a screw-threaded shaft adapted to be rotationally driven by the electric motor, and a nut member meshing with the screw-threaded shaft, the nut member being movable along the screw-threaded shaft by the rotation of the screw-threaded shaft. The parking brake apparatus also includes a transmission member connected to the nut member for transmitting a brake operating force to a wheel brake, and a rotation preventing unit for preventing the rotation of the screw-threaded shaft so as to hold the brake operating force by fixing the position of the nut member relative to the screw-threaded shaft. The rotation preventing unit in one embodiment is an electromagnetic brake for confining the screw-threaded shaft to a stationary portion of a vehicle body.

Abstract: An electrically operated parking brake apparatus that includes an electric motor and a screw mechanism The screw mechanism includes a screw-threaded shaft adapted to be rotationally driven by the electric motor, and a nut member meshing with the screw-threaded shaft, the nut member being movable along the screw-threaded shaft by the rotation of the screw-threaded shaft. The parking brake apparatus also includes a transmission member connected to the nut member for transmitting a brake operating force to a wheel brake, and a rotation preventing unit for preventing the rotation of the screw-threaded shaft so as to hold the brake operating force by fixing the position of the nut member relative to the screw-threaded shaft. The rotation preventing unit in one embodiment is an electromagnetic brake for confining the screw-threaded shaft to a stationary portion of a vehicle body.

Abstract: A first vehicle body speed is calculated based on a wheel rotational speed detected in a speed sensor for an object wheel. The largest value of speeds based on the wheel rotational speeds detected in speed sensors for four wheels is corrected by a correction value based on an inner and outer wheel speed difference during the turning of a vehicle so as to calculate a second vehicle body speed for every object wheel. A higher one of the first and second vehicle body speeds is selected as an estimated vehicle body speed for use in the anti-lock control for the object wheel. This enables a substantially accurate estimation of an estimated vehicle body speed during the turning of the vehicle.

Abstract: In a hydraulic braking pressure control system for a rear wheel brake wherein a control piston normally works to provide a hydraulic braking pressure control by cooperation with a cut-off valve interposed between an input chamber leading to a master cylinder and an output chamber leading to a wheel cylinder of the brake, the cut-off valve has a valve seat piston whose pressure-receiving area facing the output chamber is larger than the pressure-receiving area facing the output chamber. This ensures that opening and closing of the cut-off valve can be repeated in accordance with the output pressure from the master cylinder, so that the output pressure from the master cylinder can be reduced and applied to the brake wheel cylinder.

Abstract: The present invention relates to a method for estimating vehicle speeds independently on front and rear wheels of a four-wheel motor vehicle on the basis of front wheel speeds and rear wheel speeds, for use as a basis for determining slip rates for front and rear wheels. According to the first method of the invention, a reference wheel speed determined by the vehicle speed as estimated from the left and right wheel speeds cannot be unnecessarily increased during turning of the vehicle. According to the second and third methods of the invention, the estimated vehicle speed largely does not deviate from the actual vehicle speed in the event of a phase difference of variants produced between the left and right wheels due to an anti-lock control during the turning of the vehicle.

Abstract: A hydraulic braking pressure control system which includes a sleeve slidably received in a housing with opposite ends facing an output chamber connected to a brake device, and a pilot chamber connected to a control hydraulic pressure source. A control piston is slidably received in the sleeve, with one end of the control piston facing the output chamber and the other end facing a control chamber connected to the control hydraulic pressure source through a lock valve which is adapted to be closed in response to the movement of the sleeve, in a direction to increase the volume of the output chamber. A cut-off valve located between an input chamber leading to a master cylinder and the output chamber includes a valve member having a maximum amount of movement in a seating direction which is regulated to a position of the valve member spaced apart from a valve seat when a valve seat member follows movement of the sleeve in a direction to reduce the volume of the pilot chamber to the maximum amount.

Abstract: The present invention is a method for estimating the speed of a vehicle with antilock brake devices by obtaining a vehicle speed as a reference value for determining a slip ratio of a wheel based upon a wheel speed, an acceleration and a deceleration. At least the deceleration is based upon a differentiated value of a highest wheel speed from all wheels. In a vehicle in which the drive wheels are rigidly coupled, at least the deceleration is based upon a differentiated value of a highest value of the lowest wheel speed of the drive wheels and the wheel speeds of the driven wheels.

Abstract: In a method of anti-lock brake control, in which when the wheel is about to become locked, a control valve is capable of controlling a braking pressure for a brake device irrespective of a braking operation. The control valve is operated to reduce the braking pressure of the brake device in order to reduce a braking force, thereby preventing the wheel from becoming locked. When the braking pressure is to be recovered, the control valve is operated to intermittently increase the braking pressure of the brake device for a given time in order to moderate the increasing of the braking force. The control of the intermittent increasing of the braking pressure is stopped when the completion of the braking operation has been detected in the course of intermittently increasing the braking pressure in recovering the braking pressure. This avoids the wasteful operation of the control valve to prevent the generation of any unwanted operational noise and a wasteful consumption of electric power.

Abstract: A four-wheel steering motor vehicle adapted to prevent a steering ratio of the rear wheels to the front wheels from varying at the time of sudden braking when the pressure of a brake liquid is reduced by an antilock brake unit.

Abstract: A hydraulic brake pressure control device for a vehicle including a casing having first and second cylinder portions in coaxial arrangement and a pillar-like cylinder projecting portion which projects into the first cylinder portion. A piston is disposed in the casing having first and second piston portions which are connected together and slidably fitted in the first and second cylinder portions, repsectively. A third cylinder portion in the piston is slidably fitted around the projecting portion. A spring is provided in the casing urging the piston in one direction. A control chamber is defined in the first cylinder portion and exerts, upon introduction of a liquid pressure thereinto, a pressing force onto the piston in the opposite direction.

Abstract: A signal value on the basis of a lower wheel speed is compared with a signal value on the basis of a high wheel speed and, when the difference therebetween is larger than a predetermined value, a higher vehicle speed of two previously estimated vehicle speeds is used for anti-lock control and a reference value with which a wheel speed will be compared is derived from such vehicle speed. Thus, a range of condition for judging that wheels of a vehicle are about to be locked is enlarged.