Nissan Motor Company Limited

Fukashi Sugasawa

Haruhiko Iizuka

Junichiro Matsumoto

Yukihiro Etoh

Junsuke Kuroki

Masatsugu Yokote

Tomohiro Yamamura

Ken Ito

Toshiaki Tanaka

Tohru Takahashi

Takeshi Fujishiro

Yohsuke Akatsu

Sadahiro Takahashi

Kazunori Mori

Hiroshi Mouri

Takashi Imaseki

Kenji Kawagoe

Hiroshi Imai

Fumiaki Kato

Noburu Fukasawa

Nagayuki Marumo

Sadahiro Takakashi

Akitoshi Mumura

Takashi Fujishiro

Haruhiko Itzuka

Hiroshi Mori

Vehicular acceleration is sensed and used to set and/or modify at least two of a plurality of control sensitivity values in a manner which increases one with respect to the other and thus avoids the situation wherein a limited amount of servo power is wasted by futile operation of a servo powered arrangement which cannot produce a large control effect under the instant operating conditions and enables an adequate amount servo power to be directed to the operation of a different arrangement which can be effective.

Control system for optimizing operation of vehicle performance/safety

In a vehicle vibration damping force control system, rolling, pitching and bouncing motions are detected independently in a predetermined priority order; each detected motion is compared with respective predetermined levels; if each detected motion exceeds each predetermined level, hydraulic switch valves are controlled so that operating fluid energized by stroke changes of the hydraulic cylinders due to the detected vibration motion is passed through damping force generating mechanisms to increase a damping force against only the detected vibration motion, without generating any other damping forces against other non-detected vibration motions. Since only the necessary damping force is generated against only the detected vibration motion, the damping force is minimized to maintain vehicle riding comfort.

Vehicle vibration damping force control system

A damping device is installed between a vehicle body and desired two of wheels and provided with a damping force producing mechanism for producing a larger damping force when the two wheels make strokes involving a relative movement therebetween, such as at the time of rolling, pitching, etc. than when the two wheels make strokes without involving any substantial relative movement therebetween, such as at the time of bouncing. In one embodiment, the damping force producing mechanism comprises a pair of restrictions in communication with cross conduits interconnecting upper and lower cylinder chambers. The conduits and cylinder chambers are arranged so as to cause a larger flow rate of fluid to pass through the restrictions when the wheel strokes involve a relative movement between the wheels than when the wheel strokes does not involve such relative movement.

Hydraulic damping device for vehicles

A suspension control system for automotive vehicles automatically adjusts the damping strength of variable shock absorbers or other dampers in accordance with road surface conditions as recognized by frequency analysis of a vehicle height or vibration sensor signal. The sensor signal reflects vertical displacement of the vehicle body from the road surface and includes high-frequency components due solely to displacement of the wheels or unsprung mass relative to the road surface and low-frequency components due to displacement of the vehicle body or sprung mass. The sensor signal is filtered into these separate frequency bands, the amplitude of each of which is compared to a corresponding reference level. The results of comparison give an indication of the degree and scale of irregularities in the road surface; specifically, a high-amplitude low-frequency component indicates larger-scale bumps and dips capable of bouncing the vehicle whereas a strong high-frequency component reflects a rough-textured road surface, such as gravel. The comparison information is sent to a suspension system controller which causes actuation of the shock absorbers to a stiffer mode of operation when the low-frequency sensor signal components are relatively strong.

Automotive suspension control system with road-condition-dependent

A suspension control system includes a mechanism for monitoring wheel slippage on each of individual wheels as a parameter represenatative of road/tire traction. Suspension control is performed generally according to the vehicle driving conditions reflected in various suspension control parameters, such as vehicular speed, lateral acceleration and so forth in order to adjust spring coefficient or damping characteristics of a suspension system which is provided between a vehicle body and a suspension member supporting each individual wheel in order to adjust wheel load distribution and whereby to minimize variation of vehicular attitude change. Suspension control is further performed with taking the road/tire friction as one of suspension control parameters in order to provide traction dependent wheel load distribution.

Suspension control system for automotive vehicle with adjustment of

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.

Vehicle steering system with flow dividing valve

A steering control system for a vehicle includes an actuator for steering rear wheels in response to a control signal, a steering angle sensor, a vehicle speed sensor, and controller for controlling a rear wheel steer angle by producing the control signal according to the following transfer function; ##EQU1## where a.sub.0, a.sub.1, a.sub.2, a.sub.3, a.sub.4 and a.sub.5 are parameters whose values are determined by the vehicle speed, vehicle constants determined by the specification of the vehicle, and desired constants representing a preset desired steering characteristic.

Four wheel steering system for vehicle

A power drift control device produces a yaw moment in the direction of causing oversteer on the basis of acceleration and steering wheel angle during cornering of a vehicle. The yaw moment is variable depending upon variation of acceleration at a rate which increases as a steering wheel angle increases.

Device for controlling drift of vehicle during cornering

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.

Vehicle having secondarily steered front and rear wheels

A suspension control system for automotive vehicles automatically adjusts the damping strength of variable shock absorbers or other dampers in accordance with road surface conditions as recognized by frequency analysis of a vehicle height or vibration sensor signal. The sensor signal reflects vertical displacement of the vehicle body from the road surface and includes high-frequency components due solely to displacement of the wheels of unsprung mass relative to the road surface and low-frequency components due to displacement of the vehicle body or sprung mass. The sensor signal is filtered into these separate frequency bands, the amplitude of each of which is compared to a corresponding reference level. The results of comparison give an indication of the degree and scale of irregularities in the road surface; specifically, a high-amplitude low-frequency component indicates larger-scale bumps and dips capable of bouncing the vehicle whereas a strong high-frequency component reflects a rough-textured road surface, such as a gravel. The comparison information is sent to a suspension system controller which causes actuation of the shock abosrbers to a stiffer mode of operation when the low-frequency sensor signal components are relatively strong.

In order to imprive the accuracy of the time derivative of a steering angle signal consisting of discrete measured values, a vehicle steering control system for producing a steering angle control signal from the steering angle, the time derivative of the steering angle and other data is provided with a controller having a averaging section for periodically determining an average of a predetermined number of the measured values of the steering angle, and a differentiating section for determining the time derivative of the steering angle by using the averages determined by the averaging section, instead of directly using the steering angle signal.

Vehicle steering angle control system

A fail-safe steer angle control system includes a front auxiliary steering actuator for controlling a front wheel steering angle in response to a front control signal representing a front wheel auxiliary steering angle, a rear wheel steering actuator for controlling a rear wheel steering angle in response to a rear control signal, a steering angle sensor for sensing the steering wheel angle, and a controller which produces the front control signal based on the steering wheel angle in accordance with a predetermined first relationship, and produces the rear control signal based on the steering wheel angle in accordance with a predetermined second relationship. The controller has a fail-safe section which adjusts the first or second relationship when an abnormal condition is detected in either the front steering system or the rear steering system.

Fail-safe steering angle control system for four-wheel steerable vehicle

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. In accordance with the present invention, the control system is provided with means for correcting the control constants Kf and Kr in such a way that the control constants Kf and Kr become a steady-state value when the steer angle is larger than a predetermined value and become smaller than the steady-state value when the steering angle becomes smaller than the predetermined value, means for correcting the control constants Tf and Tr in such a way that the control constants Tf and Tr become a steady-state value when the steer angle is larger than a predetermined value and become smaller than the second mentioned steady-state value when the steer angle becomes smaller than the second mentioned predetermined value, means for correcting the control constants Kf and Kr in such a way that the control constant Kr reduces at the rate larger than the control constant Kf as the steer angle reduces from the first mentioned predetermined value, and means for correcting the control constants Tf and Tr in such a way that the control constant Tf reeduces at the rate larger than the control contant Tr as the steer angle reduces from the second mentioned predetermined value.

Four-wheel steer control system

A rear wheel steering control system for a four wheel steerable vehicle has a controller such as a microcomputer for steering rear wheels through a hydraulic actuator. When a small turning radius is required, the controller steers the rear wheels in an opposite direction to a direction in which the front wheels are steered. The control system further has various sensors such as front wheel angle sensor, rear wheel angle sensor, vehicle speed sensor and gear position sensor for sensing a position of a transmission. From one or more of the sensor output signals, the controller determines whether the vehicle is in a predetermined condition in which the rear wheel steering action in the opposite direction should be restrained in order to prevent the rear end of the vehicle from swinging laterally in the opposite direction and bumping against an adjacent object. If it is determined that the vehicle is in the predetermined condition, the controller steers the rear wheels gradually in the opposite direction.

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Yokohama, Japan

Fukashi Sugasawa