Unisia Jecs Corporation

Atsugi Unisia Corp.

Nissan Motor Company Limited

Atsugi Motor Parts Company, Limited

Atsugia Unisia Corp.

Mitsuo Sasaki

Fumiyuki Yamaoka

Shinobu Kakizaki

Makoto Kimura

Junichi Emura

Toru Takahashi

Hiroyuki Shimizu

Katsuya Iwasaki

Toshiro Hirai

Hiroyuki Sugiyama

Hiroshi Kato

Hiroyuki Yamaguchi

Tamotsu Yamaura

Michiya Nakamura

Takeshi Fuchida

Chiharu Nakazawa

Rotary damper

A method of controlling a suspension system include sensing a behavior of a motor vehicle, producing a control signal in accordance with the behavior sensed, carrying out normal control of a damping-force characteristic of a shock absorber in accordance with the control signal produced and based on a predetermined damping-force characteristic curve, determining a brake operating state, determining a frictional coefficient of a road surface, determining a frequency input from the road surface, and reducing variations in a load of a wheel by controlling the damping-force characteristic of the shock absorber in accordance with the brake operating state, frictional coefficient, frequency determined.

Suspension systems for motor vehicles

An apparatus and method for controlling damping force characteristics of respective vehicular shock absorbers in which vehicular vertical behavior(s) at the position(s) of the vehicular body which are forward by a predetermined distance from a tread of rear left and right road wheels are determined, the positions including front left and right road wheel sides, and corresponding vertical behavior signals are derived. Control signals for front left and right and rear left and right road wheel side shock absorbers are formed on the basis of respective processed signals having frequency-dependent characteristics formed from the vehicular behavior signal(s). The damping force characteristics of front left and right road wheel side shock absorbers are controlled on the basis of the control signals formed on the basis of the processed signal based on the front left and right road wheel vehicular behavior signals. Those of rear left and right road wheel side shock absorbers are controlled on the basis of the control signals formed on the basis of the processed signals based on the front position vehicular vertical behavior signal at the position forward from the tread between the rear left and right road wheels. The phases of the control signals V are generally matched with vehicular behavior velocity signals which would actually be generated at rear road wheel arranged positions of the vehicle.

Apparatus and method for controlling damping force characteristic of

A suspension control apparatus for use with shock absorbers provided between sprung and unsprung masses of the vehicle at the respective road wheel positions for providing variable damping force characteristics. A control unit receives first sensor signals indicative of sensed vehicle sprung mass vertical behaviors for controlling the shock absorbers to have respective target damping force characteristics determined based on the vehicle sprung mass vertical behaviors. A surface condition of a road on which the vehicle is running is determined based on the first sensor signals. The control unit also receives a second sensor signal indicative of a sensed vehicle lateral acceleration for detecting vehicle steering operation. The second sensor signal is compared with a reference value. Vehicle steering operation is detected in response to a result of comparison of the second sensor signal with the reference value. The target damping force characteristics for vehicle steering operation are determined upon the detection of the vehicle steering operation. The reference value is corrected based on the determined surface condition.

Automotive vehicle suspension control apparatus

A suspension control system for use with shock absorbers provided between sprung and unsprung masses of an automotive vehicle at the positions of the respective vehicle road wheels for providing variable damping force characteristics. Sprung mass vertical velocities at the respective road wheel positions are derived from a sensed sprung mass vertical behavior. Relative velocities between the sprung and unsprung masses at the respective road wheel positions are derived from the sensed sprung mass vertical behavior with the use of a predetermined transfer function including terms related to damping coefficients of the respective shock absorbers. A control unit is provided for producing control signals based on the derived sprung mass vertical velocities and the derived relative velocities to control the damping force characteristics of the respective shock absorbers. Damping coefficients of the respective shock absorbers are determined based on the corresponding control signals. The terms related to the damping coefficients of the respective shock absorbers are varied according to the determined damping coefficients.

Automotive vehicle suspension control system

In apparatus and method for controlling a damping force characteristic of each of front and rear left and right road wheel positioned shock absorbers based on a Sky Hook control theory, rear left and right road wheel position vehicular behaviors are estimated using a predetermined transfer function established between front road wheel position vehicular behaviors and rear road wheel position vehicular behaviors from front left and right road wheel position vehicular behavior related signals with the damping force characteristics of the rear road wheel positioned shock absorbers controlled on the basis of rear road wheel position control signals formed for the rear left and right road wheel positioned shock absorbers on the basis of the estimated rear road wheel position vehicular behaviors.

A step motor driving method employing an electric circuit operable on a supply voltage applied thereto for generating a step drive signal having a variable on-duty ratio to drive the step motor. A PWM control is made to change the step drive signal on-duty ratio. The the step drive signal on-duty ratio is increased to compensate for a supply voltage drop.

Step motor driving method and apparatus for performing PWM control to

In apparatus and method for controlling a damping force characteristic for a vehicular suspension system, a relative velocity between a sprung mass and an unsprung mass is calculated using a predetermined transfer function from a sprung mass vertical velocity derived on the basis of a sprung mass acceleration signal. The predetermined transfer function is, in a embodiment, expressed as G.sub.U(S) =(QS.sup.2 +RS)/(FS.sup.2 +DS +E), wherein Q=-m.sub.1 .multidot.c.sub.2, R=-m.sub.1 .multidot.k.sub.2, F=c.sub.1 .multidot.c.sub.2, D=c.sub.1 .multidot.k.sub.2, E=k.sub.1 .multidot.k.sub.2, S denotes a Laplace operator, c.sub.1 denotes an attenuation constant of each shock absorber, c.sub.2 denotes an attenuation constant of the corresponding one of road wheels, k.sub.1 denotes a spring constant of the shock absorber. k.sub.2 denotes a spring constant of the corresponding one of the road wheels, m.sub.1 denotes the sprung mass, and m.sub.2 denotes the unsprung mass.

In apparatus and method for controlling a damping force characteristic for a vehicular suspension system, a control force (F) based on an ideal Sky Hook theory is generated even when a low responsive characteristic and less expensive actuator such as a stepping motor associated with an adjuster of each shock absorber and which is not enabled to respond to an unsprung mass resonance frequency and a control signal based on a sprung mass vertical velocity and on a relative velocity between a vehicle body (sprung mass) and a road wheel assembly (unsprung mass) is formed using a signal processing circuit so that the control signal is formed in a low frequency band. The damping force characteristic of each shock absorber is controlled on the basis of the formed control signal.

In an apparatus and method for controlling damping forces of vehicular shock absorbers, at least one of pitch rate or roll rate of the vehicle is derived on the basis of output signals from at least three of wheel speed sensors located on front road wheels and located on either of rear right and left road wheels.

A method of driving a stepping motor comprises dividing a drive signal for each drive step into a plurality of portions in the direction of a time axis, and controlling the drive signal in connection with the plurality of portions thereof in a way of PWM so as to obtain a pattern of a gradual change in a on-duty ratio of the drive signal.

Method of driving stepping motor

In an apparatus and method for controlling a damping force characteristic of a vehicular shock absorber, a vertical sprung mass velocity signal V.sub.n is determined on the basis of a vertical G sensor output signal as a control signal. A control gain when a control unit changes a damping force characteristic of either an extension stroke side or a compression stroke side of a piston member of the shock absorber according to the control signal is increased as a moving average of peak values of the vertical sprung mass velocity signal V.sub.n is reduced.

A suspension control system for an automotive vehicle is provided. This suspension control system comprises variable damping force shock absorbers and a control unit which controls the shock absorbers to assume damping force characteristics in a range between preselected higher and lower damping coefficients. The control unit is operable to provide a control parameter indicative of bouncing motion of a vehicle body based on sprung vertical speed to determine a damping coefficient against the bouncing motion. When the control parameter is greater than a threshold value, the damping coefficient is modified to a lower value, while when the control parameter is less than the threshold value, the damping coefficient is modified to a higher value. With this damping coefficient modification, the bouncing motion is suppressed effectively while assuring passenger comfort.

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Atsugi, Japan

Mitsuo Sasaki