Abstract: A rear wheel suspension arrangement for an automotive vehicle provides an axle housing rotatably mounting rear vehicular road wheels, each of the wheels having a wheel center. At each wheel, a radius rod which extends forwardly and inwardly, as viewed in a normal forward direction of the vehicle, is connected to the axle housing at a first articulated connection at a position lower than the wheel center. Further, a front lateral link, extending generally transversely to the forward direction of the vehicle is connected to the axle housing at a second articulated connection also located below the wheel center. In addition, a rear lateral link, positioned rearwardly of the front lateral link and extending in the traverse direction of the vehicle, is connected to the axle housing at a third articulated connection also located below the wheel center. The suspension structure also includes an upper arm having an articulated connection to the axle housing at a position above the wheel center.

Abstract: An axle supporting member for a rear wheel is suspended to a suspension member by an upper link system which includes an A-arm and a side rod. The forward lower link member and the side rod are respectively arranged in front and rear of a vertical plane passing through a rotary axis of the rear wheel, while a suspension spring and a shock absorber are seated on the forward lower link member positioned in front of the above-mentioned vertical plane with respect to the longitudinal direction of the vehicle. Accordingly, an initial load transmitted from the suspension spring is mainly borne by the front end part of the suspension member, so that an initial load exerted to the rear end part of the suspension member becomes smaller. Thereby, it is possible to reduce the resilient deformation of bushings in the front and rear parts of the suspension member upon application of a wind-up input force.

Abstract: A vehicle axle suspension system including wheel support members for rotatably supporting road wheels, a suspension member for supporting the road wheel support members for vertical swinging movement, and elastic suspension elements. The elastic suspension elements include a pair of front elastic suspension elements provided at different suspension points in front of the road wheel support members for elastically mounting the suspension member to the vehicle and a pair of rear elastic suspension elements provided at different suspension points behind the road wheel support members for elastically mounting the suspension member to the vehicle. The elastic suspension elements are positioned to provide an understeer characteristic when a lateral force acts on a suspension roll center determined by suspension geometry to rotate the suspension member around a virtual roll axis extending through an elastic center of the front elastic suspension elements and an elastic center of the rear elastic suspension elements.

Abstract: A height control system in an automotive suspension system has a pressure supply network for adjusting pressure in a plurality of height adjusting actuator in respective suspension systems for adjusting relative distance between the vehicle body and suspension members at portions where the suspension systems are provided. The height control system includes a communication control valve provided in the pressure supply network so as to selectively establish and block fluid communication between the pressure supply network and one of the height control actuator. The communication control valve is to be operated to open for establishing fluid communication between one of the at least two actuators and the communication passage means when at least one of the height levels at the at least two portions is out of a predetermined target height range, and to close the communication control valve while all of the height levels monitored are within the predetermined target height range.

Abstract: A height control system utilizing at least first and second mutually different target height ranges for selectively using in vehicular height control. The first target height range is utilized for detecting the height adjustment initiating timing and the second target height range is utilized for detecting the height adjustment terminating timing. The first and second target height ranges are variable depending upon the vehicle driving condition, such as vehicle driving speed, road surface condition and so forth.

Abstract: A height control system in an automotive suspension system has a pressure supply network for adjusting pressure in a plurality of height adjusting actuator in respective suspension systems for adjusting relative distance between the vehicle body and suspension members at portions where the suspension systems are provided. The height control system includes a communication control valve provided in the pressure supply network so as to selectively establish and block fluid communication between the pressure supply network and one of the height control actuator. The communication control valve is to be operated to open for establishing fluid communication between one of the at least two actuators and the communication passage means when at least one of the height levels at the at least two portions is out of a predetermined target height range, and to close the communication control valve while all of the height levels monitored are within the predetermined target height range.

Abstract: A fail-safe control unit for a vehicle having a first control system for controlling a steer angle and a second control system for controlling a condition of the vehicle, such as a driving force distribution in a 4WD system, or a damping characteristic of a suspension system. When one of the first and second control systems becomes abnormal, and the other remains normal, the fail-safe control unit adjusts the normal control system so as to maintain or improve the directional stability of the vehicle notwithstanding the failure of the abnormal system.

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 control system for an automotive suspension system and a power steering system employs a steering operation pattern as a parameter representative of the vehicle traveling condition and vehicular driving characteristics. The control system performs selection of control modes or control characteristics based on the vehicle traveling condition and vehicle driving characteristics.

Abstract: A steering control system for controlling either or both of the front and rear wheel steer angles of a vehicle includes a steering input sensor for sensing a steering input such as a steering wheel angle and an electronic control unit which includes a basic control section for calculating a desired steer angle in accordance with the sensed steering input and a time derivative of the steering input. In order to improve the vehicle stability by eliminating unstable vehicle response to driver's unconscious fluctuating steering operation, the control unit further includes a gain adjusting section for discriminating unconscious operation from intentional steering operation by comparing the time rate of change of the steering input with a predetermined reference level, and for decreasing the gain by which the derivative of the steering input is multiplied in determining the desired steer angle when the time rate of change of the steering input is smaller than the reference level.

Abstract: A vehicular height control system includes means for detecting road roughness condition on the basis of a vehicular height indicative signal which is produced by a vehicular height sensor. The control system also includes means for detecting the road roughness condition satisfying a predetermined condition for disabling vehicular height control. Disabling of vehicular height control keeps the control system free from fluctuation of vehicular height indicative signal value due to uneveness of the road surface.

Abstract: A suspension and steering control system includes a mode selection which enables a normal mode wherein the suspension is conditioned to produce a soft damping and sufficient power assistance to the steering to produce light steering characteristics and a sporty mode wherein the suspension is conditioned to produce a firm ride and the power assistance to the steering lowered to produce heavier steering characteritics. The system further includes an arrangement for sensing parameters which are related to the attitude of the vehicle and/or the suspension thereof and for (a) during the normal mode, temporarily conditioning the suspension to produce the firm ride characteristics if the attitude of the vehicle is apt to change beyond a predetermined amount, and for (b), during the sporty mode, temporarily conditioning the suspension to produce the soft ride in the event that no substantial changes in the vehicle attitude related parameters are sensed.

Abstract: A steering control system comprises means for performing a secondary steer of front and rear wheels by angles computed using a steer angle .theta., steer angle angular velocity .theta. and vehicle speed V from the following formulas, ##EQU1## where .delta.f is a front wheel secondary steer angle, .delta.r is a rear wheel secondary steer angle, N is a steer gear ratio and Kf, Kr, Tf and Tr are control constants which are functions of vehicle speed.

Abstract: An electronically controlled power steering system comprises a vehicle speed sensor, a steering wheel angle sensor, a power steering gear including a control valve, a bypass valve for regulating a flow rate of hydraulic fluid supplied to the control valve of the power steering gear in response to a control signal generated by a controller. The controller is operative responsive to sensor output signals of the sensors for generating the control signal. With the controller, the control signal is varied in response to the vehicle speed and the steering wheel angle when the steering wheel angle is less than a predetermined value, but this varying tendency of the control signal in response to the steering wheel angle is restrained when the steering wheel angle is not less than the predetermined value.

Abstract: A suspension control system employs a road sensor monitoring road roughness or smoothness and producing a road condition indicative signal. The control system also employs other sensor or sensors for monitoring at least one preselected suspension control parameter, such as vehicle speed, steering angular variation and so forth, other than road roughness. The suspension switches between relatively hard and relatively soft characteristics based on the preselected suspension control prameters. In order to make suspension control more precisely suited to the vehicle driving conditions, the control characateristics of the suspension system are adjusted depending upon the road condition.

Abstract: A vehicle height control system has at least two vehicle height sensors which are mounted at points suitable for detecting changes in vehicular profile. Each vehicle height sensor monitors vehicle height at the associated portion of the vehicle and produces a vehicle height indicative signal having a value representative of the vehicle height at the associated portion. The vehicle height control system also has height control means respectively associated with individual suspension systems, each of which is associated with a corresponding vehicle wheel. The height control means is connected to a controller and controlled by means of a control signal selected so as to hold the relative distance between the vehicle body and the vehicular wheels in a given relationship. The controller monitors the output values of the vehicle height sensors so as to detect abnormal output values from one or more of the vehicle height sensors.