Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
1999-02-26
2001-06-19
Oberleitner, Robert J. (Department: 3613)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
C701S037000, C188S322150
Reexamination Certificate
active
06247685
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to suspension systems for motor vehicles which ensure optimum control of the damping-force characteristic of a shock absorber, and more particularly, to the art of improving riding comfort and stability of a vehicular position during steering operation.
2. Description of the Related Art
In connection with the known suspension systems for motor vehicles which ensure control of the damping-force characteristic of a shock absorber, JP-A 5-330325 shows a suspension control system. This system calculates an absolute speed of vertical vibration of a vehicle body. In accordance with the direction of the absolute speed, the system controls a damping coefficient of a shock absorber such that the contraction-side damping coefficient has a small value whereas the extension-side damping coefficient has a large value, or the contraction-side damping coefficient has a large value whereas the extension-side damping coefficient has a small value. By this, without detecting a relative speed between a vehicle body located above the spring and an axle located below the spring, i.e. a sprung-unsprung relative speed, behavior of the vehicle body, i.e. sprung behavior, due to road input can be restrained.
With this known suspension control system, a damping performance of a motor vehicle can be secured with regard to sprung behavior due to road input. However, with regard to damping of behavior in the roll direction when a great lateral acceleration is applied to the vehicle body during steering operation, a controlling force is insufficient due to a moment of inertia in the roll direction being applied to the vehicle body.
Moreover, if the system is constructed to produce a damping force sufficient to damp roll behavior during steering operation, an excessive damping force is produced with respect to road input, resulting in deteriorated riding comfort during ordinary cruising.
It is, therefore, an object of the present invention to provide suspension systems for motor vehicles which ensure optimum control of the damping-force characteristic of a shock absorber in accordance with every aspect of vehicular behavior occurring during non-steering and steering operations to achieve both steering stability and riding comfort.
SUMMARY OF THE INVENTION
One aspect of the present invention lies in providing a method of controlling a suspension system for a motor vehicle, said suspension system including a shock absorber arranged between a vehicle body and a wheel of the motor vehicle and having a device for allowing a change in a damping-force characteristic, the method comprising the steps of:
sensing a vertical behavior of the motor vehicle;
sensing a roll angle of the motor vehicle during steering operation;
sensing a roll rate of the vehicle during steering operation;
carrying out an ordinary control of the damping-force characteristic of the shock absorber in accordance with said vertical behavior as sensed;
carrying out a first roll restraining control in place of said ordinary control when said roll angle as sensed is equal to or greater than a predetermined threshold value; and
carrying out a second roll restraining control in place of said ordinary control when said roll rate as sensed is equal to or greater than a predetermined threshold value,
said second roll restraining control providing the damping-force characteristic of the shock absorber higher than that of said first roll restraining control.
Another aspect of the present invention lies in providing a suspension system for a motor vehicle with a vehicle body and a wheel, comprising:
a shock absorber arranged between the vehicle body and the wheel and including a device for allowing a change in a damping-force characteristic;
a first sensor for sensing a vertical behavior of the motor vehicle;
a second sensor for sensing a roll angle of the motor vehicle during steering operation;
a third sensor for sensing a roll rate of the motor vehicle during steering operation;
a control unit connected to said shock absorber and said first, second, and third sensors,
said control unit including a fundamental control part for carrying out an ordinary control of said damping-force characteristic of said shock absorber in accordance with said vertical behavior as sensed,
said control unit including a first roll restraining control part for carrying out a first roll restraining control in place of said ordinary control when said roll angle as sensed is equal to or greater than a predetermined threshold value,
said control unit including a second roll restraining control part for carrying out a second roll restraining control in place of said ordinary control when said roll rate as sensed is equal to or greater than a predetermined threshold value,
said second roll restraining control providing said damping-force characteristic of said shock absorber higher than that of said first roll restraining control.
REFERENCES:
patent: 4564214 (1986-01-01), Tokunaga et al.
patent: 5231583 (1993-07-01), Lizell
patent: 5322318 (1994-06-01), Kimura et al.
patent: 5440488 (1995-08-01), Yamaoka et al.
patent: 5485377 (1996-01-01), Sasaki et al.
patent: 5691899 (1997-11-01), Terasaki
patent: 5935181 (1999-08-01), Iwasaki
patent: 6002975 (1999-12-01), Schiffmann et al.
patent: 0 706 905 (1996-04-01), None
patent: 5-330325 (1993-12-01), None
Patent Abstracts of Japan, vol. 097, No. 008 (Aug. 29, 1997).
Patent Abstracts of Japan, vol. 096, No. 002 (Feb. 29, 1996).
Foley & Lardner
Oberleitner Robert J.
Talavera Melanie
Unisia Jecs Corporation
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