Abstract: A road curvature estimating apparatus for a vehicle includes a vehicle attitude detector which detects an attitude of the vehicle with respect to a road, a front-and-rear wheel steer-angle detector, a vehicle speed detector and a road curvature calculator. The road curvature calculator calculates a curvature of a road ahead of the vehicle on the basis of the measured vehicle attitude, the measured vehicle speed and the measured steer angles of the front and rear wheels by means of a state estimation of modern control theory. A controller executes a control of an automatic steering mechanism on the basis of the road curvature calculated.

Abstract: A vehicle steering system includes a first steering mechanism for a manual steering mode and a second steering mechanism for an automatic steering mode. A controller steers the vehicle in accordance with information on driving environment, with the second steering mechanism when the automatic mode is selected with a mode selector. There is further provided a holding device for holding the steering angle of the first steering mechanism when the automatic steering operation of the second steering mechanism is under way. In response to selection of the automatic mode, the controller performs the automatic steering control only when a sensor senses a straightforward neutral position of the first steering mechanism.

Abstract: A steering system for an automotive vehicle provides an improved steering response characteristic and has has an elastic member which is included in a transmission path from a steering wheel to tires of the vehicle to be operated by the steering wheel, such as a steering column coupling which is elastically deformed according to the rotation of a steering column shaft, or a rack insulator for elastically supporting a rack housing of a rack/pinion steering mechanism. The elastic member is comprised of a spring element and a damping element of which the ratio C/K of the damping coefficient C to the spring constant K is such that C/K is greater than 1/(10.pi.).

Abstract: A four-wheel steering apparatus for use with a motor vehicle supported on a pair of front wheels and a pair of rear wheels. The apparatus comprises a control unit for steering the front wheels to provide a front wheel auxiliary steer angle satisfying the following equation: ##EQU1## where .theta..sub.(s) is a Laplace transform of the front wheel steer angle and .delta..sub.f(s) is a Laplace transform of the front wheel auxiliary steer angle, S is a Laplacian, and K, .tau..sub.1, .tau..sub.2, T.sub.1 and T.sub.2 are constants inherent on the motor vehicle and for steering the rear wheels to provide a rear wheel auxiliary steer angle satisfying the following equation: ##EQU2## where .theta..sub.(s) is a Laplace transform of the front wheel steer angle, .delta..sub.r(s) is a Laplace transform of the rear wheel auxiliary steer angle, and K', .tau..sub.1 ', .tau..sub.2 ', T.sub.1 ' and T.sub.2 ' are constants inherent on the motor vehicle.

Abstract: Herein disclosed is a pneumatic tire which comprises a case and a tread which covers a crown portion of the case. The tread includes a foamed rubber which has a volume not less than 10% of that of the entire of the tread, and the foamed rubber is formed of a rubber composition which contains rubber components each having a glass transition point not higher than -60.degree. C.

Abstract: A rear wheel steering control system for automotive vehicles steers rear wheels of the vehicle with a same-phase angle as the front wheels for a relatively small steering wheel operation angle, and with an opposite-phase angle to the front wheels for a relatively large steering wheel operation angle. The control system serves to mitigate an enhanced understeering tendency of front wheel drive type vehicles during cornering. A delay means is operative in a particular steering wheel operation angle range in which the rear wheels steering angle changes between a maximum same-phase steering angle and a maximum opposite-phase steering angle. The delay means sets a delayed rear wheel steering response characteristic with reference to a manual steering wheel operation, for maintaining a stable maneuverability during a lane change.

Abstract: In an apparatus for actively controlling a steer angle of front wheels of a vehicle, a steering angle of a steering wheel is detected and then an active control amount for actively controlling the steer angle of the front wheels including a proportional term and a differential term is calculated. After only the differential term has been delayed, the steer angle of the front wheels is controlled in accordance with the active control amount. Since the differential component in the active control amount has been delayed, the steer angle of the front wheels is changed gradually, so that the variation in the steering force is suppressed. Therefore, the maneuverability and operating properties of the vehicle can be improved.

Abstract: An auxiliary steering system for a vehicle is adapted to additionally steer the front wheels and/or rear wheels of a vehicle upon the main steering of the front wheels by a steering maneuver of a steering wheel, while an auxiliary steer angle is determined in accordance with a differential value of a main steer angle of the front wheels. An auxiliary steering system further includes a limiter means adapted to restrict an upper limit of the differential value in accordance with a main steer speed or in accordance with both of the main steer speed and the main steer angle, whereby the auxiliary steer angle does not become too large and a jerk of the vehicle is prevented even if the main steer speed is high, while within a large main steer angle range the auxiliary steer angle is not suppressed and remains capable of compensating for a lowering of a tire cornering power.

Abstract: In an apparatus for actively controlling a steer angle of front wheels of a vehicle in accordance with a steering wheel angle, an active control amount for actively controlling the steer angle of the front wheels is calculated by an equation including a proportional term and a differential term. A coefficient of the differential term is changed in accordance with a lateral acceleration such that it is kept unchanged within a first range in which the cornering power is large, but is increased in a second range in which the cornering power is decreased due to the non-linearity of tires. Thus, the reduction in the cornering power in the second range can be compensated for and the stability and response during the high lateral G turning can be improved.

Abstract: Herein disclosed is a pneumatic tire which comprises a case and a tread which covers a crown portion of the case. The tread includes a foamed rubber which has a volume not less than 10% of that of the entire of the tread, and the foamed rubber is formed of a rubber composition which contains rubber components each having a glass transition point not higher than -60.degree. C.

Abstract: The wear resistance of the pneumatic tire used under a high severity region is improved by using a particular high-trans polybutadiene rubber in a rubber composition for a ground contact part of the tire tread.

Abstract: A rubber composition for tire having improved processability, wear resistance, rebound resilience and heat build-up comprises 20.about.70 parts by weight of a specified butadiene polymer, 30.about.80 parts by weight of at least one rubber selected from natural rubber, high cis-1,4 polyisoprene rubber and styrene-butadiene copolymer rubber, and 0.about.30 parts by weight of high cis-1,4 polybutadiene and/or low cis-1,4 polybutadiene, and contains 35.about.100 parts by weight of carbon black, 0.about.50 parts by weight of process oil, 0.5.about.5 parts by weight of aliphatic carboxylic acid and 0.1.about.3 parts by weight of sulfur based on 100 parts by weight of the above rubber components.

Abstract: A vehicle steering system includes a front hydraulic actuator for steering front wheels, a rear hydraulic actuator for steering rear wheels, a front control valve of an open center type for controlling the fluid pressure of the front actuator, a rear control valve of the open center type for controlling the fluid pressure of the rear actuator, a common fluid pressure source, and a flow dividing valve for dividing a fluid flow from the common pressure source into two flows directed to the front and rear control valves so that the front and rear control valves of the open center type can control the fluid pressures independently and accurately.

Abstract: A method of steering a vehicle having a set of steerable front wheels and a set of steerable rear wheels. The front and rear wheels are both secondarily steered in addition to a main steer of the front wheels caused by an operation of a front wheel steering gear in response to an operation of a steering wheel. The method comprises providing to the front wheels a secondary steer angle corresponding to at least a differentiated value of a steer angle of a steering wheel in such a way as to increase an overall steer angle of the front wheels and providing to the rear wheels a secondary steer angle proportional to the steer angle of the steering wheel and in the same direction as the steer angle of the front wheels.

Abstract: A heavy duty pneumatic tire for use in construction vehicles, truck and bus is disclosed, which comprises a tread rubber having improved cut resistance, resistance to rib tear, wear resistance, resistance to heat build-up, processability and the like. The tread rubber comprises 20-100 parts by weight of a particular modified styrene-butadiene copolymer and 80-0 parts by weight of other diene series rubber as a rubber component and contains 40-80 parts by weight of a particular carbon black based on 100 parts by weight of the rubber component.

Abstract: A stabilized transmitter includes a gain converter that varies its gain according to an electrical signal; a power amplifier that amplifies a high-frequency signal passed through the gain converter; and a compensator having a temperature sensor which detects the temperature of the power amplifier for producing from a detection result of the temperature sensor the electrical signal applied to the gain converter so as to thereby to compensate for variations of the gain of the power amplifier caused by temperature variations. The compensator is adjusted in advance so that the gain of the power amplifier at a reference temperature becomes a predetermined value.

Abstract: A rubber composition having improved resistance to crack growth and cut resistance comprises 1.about.15 parts by weight of a resin composed mainly of propylene-ethylene block copolymer based on 100 parts by weight of rubber ingredient, and particular amount of carbon black having specified iodine absorption value and DBP oil absorption.