Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
2000-06-14
2001-10-02
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C701S038000, C280S005512, C280S005515, C188S266100
Reexamination Certificate
active
06298294
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.
SUMMARY OF THE INVENTION
On the other hand, when the four wheeled vehicles turn, the vehicles would become more stable against the turn and a rolling due to the turn if the mass center or the center of gravity of the vehicle body could be lowered.
In view of the above, it is a primary object of the present invention to provide a device for controlling the damping coefficients of those shock absorbers mounted in the suspension of a four wheeled vehicle in such an ordinary arrangement that each acts between each wheel and a corresponding portion of the vehicle body in parallel with a corresponding suspension spring, so that the center of gravity of the vehicle body is lowered during a turn running according to the art of constructing a phantom damping system by the actual shock absorbers.
According to the present invention, such a primary object 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 lateral inside of a turn running 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 and a substantially same phantom angular damping moment against a rolling angular movement of the vehicle body as the shock absorbers acting between the wheels and the corresponding portions of the vehicle body during a rolling of the vehicle body due to the turn running of the vehicle;
means for calculating values of at least the first and second phantom damping coefficients for obtaining an optimum rolling performance of the vehicle body by the phantom damping system during the turn 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 as well as against a rolling movement due to a turn running of the vehicle.
Further, in the rolling of the vehicle body damped by the shock absorbers acting between the wheels and the corresponding portions of the vehicle body, the vehicle body will roll around a roll 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 of the suspension system by a rolling of the vehicle body will generally balance in the vertical direction.
However, the vehicle body damped by the above-mentioned phantom damping system rolls around the pivot point of the phantom angular shock absorber connected with the upper end of the phantom side shock absorber positioned at the lateral inside of the turn running of the vehicle. As will be appreciated from the detailed descriptions made hereinbelow, the condition that the vertically disposed phantom side shock absorber, and therefore the upper end thereof, is positioned at the lateral inside of the turn running of the vehicle means that a vertically disposed central axis of the phantom side shock absorber is positioned at a concave side of a phantom curved trace drawn by the center of gravity or the mass center of the vehicle body of the turn running vehicle. Therefore, the mass center of the vehicle body damped by the above-mentioned phantom damping system lowers according to a rolling thereof due to a turn running of the vehicle.
The basic principle of the damping coefficient control according to the present invention will be described with reference to
FIGS. 1 and 2
.
Referring to
FIG. 1
showing a standard skeleton model of the suspension system of a four wheeled vehicle from a back thereof, a vehicle body
110
is supported by left and right wheels
112
L and
112
R via a pair of parallel combinations of left and right suspension springs
114
L and
114
R and left and right shock absorbers
116
L and
116
R, respectively. The shock absorbers
116
L and
116
R correspond to a pair of shock absorbers
22
FL and
22
FR or a pair of shock absorbers
22
RL and
22
RR described hereinbelow with reference to
FIG. 4
, and are each of a variable type in which its damping coefficient is variably controllable by a control signal supplied from a controller such as electric control means
24
of
FIG. 4. 118
is the center of gravity or mass center of the vehicle body
110
. It is herein assumed that the vehicle is making a left turn, so that the left side of the vehicle is an inside of the turn, while the right side of the vehicle is an outside of the turn.
The roll motion of the vehicle body supported by such a suspension system is expressed with regard to a movement in the vertical direction and a rotation around the mass center
118
as follows:
M
(
X
¨
in
+
X
¨
out
2
)
=
KXin
+
KXout
+
Cin
X
.
in
+
Cout
Xout
.
(
1
)
I
Ψ
¨
=
W
2
KXin
-
W
2
KXout
+
W
2
Cin
X
.
in
-
W
2
Cout
X
.
out
(
2
)
wherein M and I are the mass and the inertial moment of the vehicle body
110
around the mass center
118
thereof, respectively, Xin and Xout are vertical shiftings of inside (left side) and outside (right side) portions of the vehicle body vertically above the inside and outside wheels
112
L and
112
R relative thereto, respectively, to b
Murata Masahiro
Onuma Toshio
Suzuki Satoshi
Tomida Koichi
Arthur Gertrude
Cuchlinski Jr. William A.
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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