Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
2000-07-11
2001-09-04
Nguyen, Tan (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C701S038000, C280S005512, C280S005515
Reexamination Certificate
active
06285935
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the art of vehicle suspension, and more particularly, to a device for controlling the damping coefficients of shock absorbers provided between a body of a four wheeled vehicle and the wheels thereof by constructing a phantom damping system substantially equivalent to the damping system provided by the actual shock absorbers.
2. Description of the Prior Art
In the art of the vehicle suspension, it is already known to variably control the damping coefficients of the shock absorbers incorporated therein so that a more desirable suspension performance is available.
For example, when the damping coefficient of a shock absorber disposed in parallel with a suspension spring supporting the vehicle body at a corresponding portion thereof on a wheel is variably controlled to be proportional to a ratio of the vertically stroking velocity of the corresponding body portion to the difference between the vertically stroking velocity of the corresponding body portion and the vertically stroking velocity of the wheel, the shock absorber can be imagined as acting between the vehicle body and a phantom stationary overhead construction, as generally called “sky hook damper.
If the shock absorber for the vehicle body could act against a stationary overhead construction, the stability performance of the vehicle body would of course be much improved, because the end of the shock absorber opposite to the vehicle body would no longer fluctuate as it actually does together with the wheel along the road surface in the actual construction.
On the other hand, when the four wheeled vehicles turn, the vehicles would become more stable against a rolling due to the turn if the center of gravity of the vehicle body is lowered. In view of this, in a co-pending earlier patent application No. (1243), a basic inventive concept of which is originated in the inventor of the present application, it has been proposed to control the damping coefficient of shock absorbers mounted in an ordinary arrangement between each wheel and a corresponding portion of the vehicle body of a four-wheeled vehicle by constructing a phantom damping system as a substitute for the actual shock absorbers, so that the vertical damping force against the vertical stroking and the angular damping moment against the rolling of the vehicle body are equivalently provided by a combination of a phantom side shock absorber located laterally inside of a turn of the vehicle as arranged to act vertically and a phantom angular shock absorber arranged to act between an upper end of the phantom side shock absorber and the vehicle body. By the damping coefficients of the actual shock absorbers being so equivalently controlled by way of the phantom damping system, when the vehicle body rolls, it rolls around a pivot point between the upper end of the phantom side shock absorber and the corresponding lateral end of the phantom angular shock absorber, so that the center of gravity of the vehicle body is lowered according to a rolling thereof due to a turn running of the vehicle.
SUMMARY OF THE INVENTION
It is contemplated that if the center of gravity of the vehicle body is lowered when the vehicle body pitches longitudinally so as to incline rearward or forward due to an acceleration or a braking of the vehicle, the running stability of the vehicle will be further improved.
In view of the above, it is a primary object of the present invention to provide a device for controlling damping coefficients of shock absorbers of a four-wheeled vehicle such that the center of gravity of the vehicle body is lowered according to a rolling of the vehicle body due to a turn running of the vehicle and also according to a pitching of the vehicle body due to an acceleration or a deceleration of the vehicle.
According to the present invention, such a primary object of the present invention is accomplished by a device for controlling damping coefficients of shock absorbers of a four-wheeled vehicle having a vehicle body, front left, front right, rear left and rear right wheels each supporting the vehicle body at a corresponding portion thereof, and the shock absorbers each acting between each of the wheels and the corresponding portion of the vehicle body, comprising:
means for constructing a phantom damping system composed of a phantom side shock absorber disposed vertically at a skewed position laterally inside of a turn running of the vehicle and longitudinally shifted from a center of gravity of the vehicle body in a direction of an acceleration or a deceleration of the vehicle to have a lower end movable along a ground surface together with the vehicle and an upper end vertically movable relative to the lower end with a first phantom damping coefficient therebetween, and a phantom angular shock absorber arranged to act between the upper end of the phantom side shock absorber and the vehicle body with a second phantom damping coefficient therebetween, such that the phantom damping system provides the vehicle body with a substantially same phantom vertical damping force against a vertical movement of the vehicle body, a substantially same phantom angular damping moment against a rolling angular movement of the vehicle body during a rolling of the vehicle body due to the turn running, and a substantially same phantom angular damping moment against a pitching angular movement of the vehicle body during a pitching of the vehicle body due to the acceleration or the deceleration of the vehicle, respectively, as the shock absorbers acting between the wheels and the corresponding portions of the vehicle;
means for calculating values of at least the first and second phantom damping coefficients for obtaining an optimum rolling and/or pitching performance of the vehicle body by the phantom damping system during the turn and/or acceleration or deceleration running of the vehicle; and
means for controlling the damping coefficients of the shock absorbers acting between the wheels and the corresponding portions of the vehicle body based upon the calculated values of the first and second phantom damping coefficients.
When the phantom damping system is so constructed as described above, the vehicle body will be provided with a substantially same damping effect by the phantom side and angular shock absorbers as that provided by the shock absorbers acting between the wheels and the corresponding portions of the vehicle body against a vertical movement, a rolling movement due to a turn running as well as a pitching movement due to an acceleration or deceleration of the vehicle.
In the rolling or pitching of the vehicle body damped by the ordinary shock absorbers acting between the wheels and the corresponding portions of the vehicle body, the vehicle body will roll around a roll center or pitch around a pitch center generally vertically aligned with the mass center of the vehicle body and substantially maintained at a constant height, because the vertical forces generated in the left side and the right side or the vertical forces generated in the front side and the rear side of the ordinary suspension system by a rolling or a pitching of the vehicle body will generally balance in the vertical direction.
However, the vehicle body damped by the above-mentioned phantom damping system rolls and/or pitches around the pivot point of the phantom angular shock absorber connected with the upper end of the phantom side shock absorber positioned laterally inside of a turn running of the vehicle and longitudinally shifted from the mass center of the vehicle body in a direction of a longitudinal acceleration or deceleration. Therefore, the center of gravity or the mass center of the vehicle body damped by the above-mentioned phantom damping system lowers according to a rolling or a pitching thereof due to the turn running or the acceleration or the deceleration of the vehicle.
The principle of the damping coefficient control according to the present invention will be described with reference to
FIGS. 1-5
.
Referring t
Nguyen Tan
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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