Note: Descriptions are shown in the official language in which they were submitted.
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1 BACKGROUND OF THE IN~ENTION
This invention relates to vehicle suspension
systems, and in particular to racing cars, where it endea-
vors to continually provide the maximum possible cornering
force by each tire.
In order to develop the maximum cornering force,
each tire must obtain the maximum traction by obtaining
the maximum tire-to-road contact area, and by having the
ma~imum tire-to-road contact time and loading.
In the past, many attemp~s have been made to
achieve a superior suspension system. There have been
many designs of suspension layouts and geometries, aimed
a-t obtaining the desired tire inclination or camber for
each and every road and vehicle condition, in an eEfort to
obtain the greatest contact area, allowing for tire distor-
tion which occurs during cornering.
Also, there have been many designs of springing
and damping sys-tems that attempt to minimize the wheel
bounce or vertical displacement, in an effort to achieve
firm and continuous tire-to-road contact.
On a race track, there can be differences in
camber, surface smoothness and adhesion between the various
corners, and conditions can change significantlv during a
race due to surface damage, rubber and oil accumulation,
and other causes. During a race, drivers may have to use
i3
different lanes through corners, in order to avoid other
race cars, where parameters affecting the vehicle handling
are different. Also, during a race, the handling
characteristics of a vehicle will change as the fuel load
changes, when new tires are fitted, and if wear or damage
to the tires or suspension occurs.
Clearly, a "fixed" suspension system, that is,
one that does not compensate for all the variants, cannot
possibly achieve the optimum road-holding, hence maximum
cornering force.
SUMMARY OF THE INVENTION
The invention resides in providing a system that
continually and automatically compensates for the
aforementioned varian-ts, so that it-instantaneously -
controls each tire camber to achieve the greatest possible
contact area, and regulates the springing, damping and
stiffness of each wheel so as to obtain the maximum
possible tire-to-road contact time and loading.
Accordingly, in one of its broad aspectsr the
invention resides in a vehicle having a plurality of wheels
wherein each wheel has a variable camber, a suspension
system comprising: a lateral-acceleration-sensing means,
determining and providing lateral-acceleration input
relating to lateral acceleration of the vehicle;
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a plurality of camber-sensing means, each corresponding to
a particular wheel and determining and providing camber
input relating to the chamber part of the particular wheel;
a plurality of camber-control means, each corresponding to
a particular wheel; a computing means which receives the
input from each lateral-acceleration-sensing means and from
each of the camber-sensing means, processes the inputs
corresponding to at least one selected wheel, and provides
a camber-output to the camber-control means for controlling
the camber of the at least one selected wheel.
Accordingly, in one of its further broad
aspect, the invention resides in a vehicle having a
plurality of wheels, a suspension system comprising: a
plurality of body-roll-sensing means, each corres-
ponding to a particular wheel and determining and
providing body-roll input relating to lateral body-roll
of the vehicle in a region proximate the particular
wheel; a plurality of vertical-control means, each
corresponding to a particular wheel and controlling a
vertical position of the particular wheel with respect
to a chassis; a computing means receives the input from
each of the body-roll-sensing means, processes the
inputs corresponding to at least one selected wheel, and
provides a vertical-output to the ver~ical-control means
'D ~A ~!~1~; ~
~QJII ~ V~D
1 for controlling the vertical position of the at least one
selected wheel.
BRIEF DESCRIPTION OF THE DRA~INGS
The nature of the in~ention, and the best manner
of carrying it out will be more clearly understood from
the following description thereof with reference to the
accompanying drawings, in which:
Figure 1 represents a schematic view of a vehicle
suspension system for one wheel, wherein a mechanism is
provided for changing the camber of a wheel;
Figure 2 represents a schematic view of another
embodiment of the inven-tion, in which there is additionally
provided a ver-tical control means;
Figure 3 represents a schematic view of another
embodiment oE the invention, in which there is additionally
provided means for adjusting the spring constant and damp-
ing co-efficient of the vehicle suspension system;
Figure 4 represents a schematic view of another
embodiment of the invention in which an alternate position
for the damping means is shown;
Figure 5A represents a schematic view of another
embodiment of the invention wherein a combined anti-roll
and damping system is provided;
Figure 5B represents a schematic diagram of a
hydraulic circuit for the anti-roll and damping system
of Figure 5A;
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7~ii3
1 Figure 6A represents. a schemati,c vi,ew of another
embodiment of the invention wherein a combined anti-roll
and damping system is provided in combination with the
tire control mechanism; and
~''igure 6B represents a schematic diagram of a
hydraulic circuit for the particular embodiment shown in
Figure ~A.
DETAILED DESC~IPTI.ON OF THE INVENTION
AND PREFERRED E~BODIMENT THEREOF
lQ As can be seen from Figure 1, an independent
suspension assembly normally comprises a king-pin, or up-
right 1 which supports the wheel 2 by means of an a.xle 3
and bearing 4, hinyed to an upper.lateral control arm, or
! wish-bone S, and to a lower lateral control arm, or wish-
bone 6, the inner ends of the control arms are hinged to
the chassis, or body, of the vehicle 7, typically by means
of spherical bearings 8.
In an embodiment of the invention which is shown
in Figure 1, the inner end of the upper control arm 5 is
hinged to a lever, the fulcrum of which is hinged to the
vehicle structure. Another part of the lever .is connected
to a camber control unit 10, such that movement of the
piston of the camber control unit 10 causes the upper
control arm to move laterally, causing a change in the
camber of the wheel.
~3'7~i~
1 An alternatiYe embodi~ent (not shown) uses a con-
ventional layout, but has one., or both, camber control
arms as a telescopic unit, such that movement of the camber
control unit 10, which is incorporated i.n the control arm .
S 5 or 6, changes the distance between the inner and outer
bearings, thus changing the wheel camber.
Typically, as shown in Figures 1 and 2, the camber
control unit 10 is a hydraulic cylinder and piston assembly.
It may be, however, an electric motor and associated gears
which produce a linear displacement when connected to con-
trol arms 5 or 6. Generally, however, the camber control
unit is operated by the central control regulating means
11 which controls the working fluid supplied to various
piston and cylinder assemblies. A computing means 12
tJ;
incorporated into sai.d central control regulating means 11,
or operating as a separate unit and interfacing with the
contral control regulating means, as shown in Figurs 1 to
4, receives signals from laterally mounted accelerometers
48 and camber indicators 40 mounted on each kingpin or up-
right 1. From these signals the computing means 12 cal-
culates the amount of change in the wheQl camber that is
required for each vehicle wheel so as to maximize the
amount of tire-to-road contact regardless of vehicle body
roll, wheel bounce, or other undesirable conditionsO
The desired wheel camber angles for each wheel
at a given cornering force or acceleration are stored in
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1 the memory of the computing ~eans 12~ and arepre-detcrmined
using such means as a test track, for example. Provision
is thus made in the computing means for memory circuits
capable of storing pre-set ~alues of tire camber angle for
eac~ tire at given values of lateral cornering acceleration
for the front and/or rear ends of the vehicle. During
vehicle operation, the computing means 12 continually sends
signals to the central control regulating means 11 to cause
the camber control units 10 to adjust wheel camber to the
pre-determined value of wheel camber for that individual
wheel, at the particular measured instantaneous lateral
cornering acceleration of the front and/or rear ends of
the veh:icle.
Provision may also be made for further circuitry
within the computing means to allow re-adjustment of each
of the pre-stored values of tire camber angle at each of
the associated lateral acceleration values, during vehicle
operation. This feature would allow the compu-ting means
to self-adjust for changing conditions, such as a different
vehicle welght, to achieve optimum tire camber at the new
condition.
To accomplish self-adjustment, the computing
means 12 would make a slight incremental adjustment, either
an increase or decrease in each of the tire camber angles
- 25 at the front and/or rear of the vehicle. During a given
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3'~53
1 period, ~or e~ample the period necess~XX~ to complete one
circuit of a xace track duri.n~ a race, the compu~ing means
for each sensed ~alue of lateral acceleration would con~
tinuall~ adjust the front and/or rear tire cam~er to the
pre-stored value of tire camber plus or minus the incre-
mental adjustmentO In addition, during such given period r
the computing means would measure and store in its memory
th.e maximum measured lateral acceleration of the front
and/or rear of the vehicle. If this maximum value attain-
able was higher than any of the pre-existing stored values,
the computing means would adjust each of the pre-stored
values of camber by the incremental amount, and store
these values in the memory. These values then become the
pre-stored value~.
If the maximum attainable values for lateral
acceleration were lower than the pre-stored values, the
computer would not make any adjustment to the pre-stored
values, but rather would retain such values in its memory.
The computing means 12 would then make for the next given
period an incremental adjustment of the tire camber of the
front and/or rear tires opposlte to that which was made
previously and then repeat the above process. For example, if
an increase had been made to the tire camber, and the maximum
attainable lateral acceleration during the given period
was lower than the maximum pre-stored value, the computing
~2~753
1 means would retai.n the pre-stored yalue ! and ~or the next
given period, make an i.ncremental adjustment resulting in
a decrease in the tire camber of the front and/or rear
tires.
Provision may be ~ade to allow separate adjust-
ment of the front wheels separate from the rear wheels.
For example, the computing means to maximize lateral
attainable acceleration of th.e vehicle may find it necessary
to make incremental adjustment to increase the pre-stored
values of camber angle on the front tires, while making
incremental adjustment to decrease tire camber on the rear .
wheels.
In this fashion the vehicle suspension system
can continually prvvide the optimum wheel camber angle
or both the front and rear of the vehicle, which therefore
provides maximum tire-to-road contact and hence maximum
cornering acceleration despite changing vehicle character-
istics such as vehicle weight distribution.
In one embodiment of this invention, the wheel
camber sensing means 40 may utilize a gyroscope as a
reference for determining the camber angle of each wheel.
In another embodiment the wheel camber sensing means 40
may be configured so as to measure changes in referer~ce
dimensions between datum points on wheel suspension com-
ponents as a means of determining wheel camber angle.
_g_
3753
1 An important ~eature of the inyention is its
ability to allow the driv~r to adjust the vehicle handlin~
characteristics, so that the amount of under steer or over~
steer at various cornering accelerations can be controlled~
While normally it is desirable to obtain the maximum
cornering force at each tire, it may be necessary at times
to reduce the cornering force at either the front or rear
tires in order to achieve the desired vehicle control.
Depending on the preferred tire wear pattern,
the computing means 12 can be programmed or manually ad-
~usted to increase or decrease the cambers on either the
front or rear tires from the normal maximum-force settings
so that the cornering force at that particular end of the
vehicle is reduced.
As a further refinement of the above feature,
provision may be made for optical sensors to sense each
tire temperature across its surface. In response to such
measurement, the computing means 12 upon receiving such
input may either reduce or increase tire camber on one or
more wheels to adjust the temperature profile across the
tire closer to a pre-determined condition. Provision may
also be for cancelation of inputs resulting from extreme
conditions, such as tire skid or vehicle spin.
The invention may utili~e conventional springs
1~, torson bars~ shock absorbers or dampers 20, and anti-
roll bars as means in which to resiliently suspending the
wheels from the vehicle chassis.
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3~7~3
1 As a ~uxthe~ refinement o~ this inYentiOn~ anothe~
embodiment as shown in Figures 2 and 3 has adde~ a vertical
control unit 13 to each wh~el suspension system. Each.
vertical control unit 13 is comprised of a pis-ton and
cylinder which has pressurized wo.rking fluid supplied to
it by the central control regulating means ll. The purpose
of such vertical control units 13 is to provide a vehicle
leveling and clearance device to both level the vehicle
body despite unequal weight distribution on each wheel,
and to also adjust the vehicle chassis clearance above the
road surface, By means of sensors 48 described later in
more detail, the computing means 12 can cause the central
control regulating means 11 to adjust the vertical control
units 13 to reduce lateral and longitudinal roll of the
vehicle, and thereby increase the maximum attainable corner-
ing acceleration of the vehicle.
The invention provides for vertical control
units 13 to be affixed to a conventional vehicle suspension
means, such as a coil spring 1~, leaf spring, torson spring,
or pneumatic diaphragm and chamber ~not shown) to form an
assembly. Each assembly is then affixed to both the
vehicle chassis 7 at one end and the suspended wheel or a
part affixed thereto, such as the lower lateral control
arm 6, at the other. As shown in Figures 2, 3 and ~, in
order for the central control regulating means 11 to
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3~75i~
1 properly adjust the ve~tical contxol units 13 for each
wheel to its desired height, lateral and longitudinal body
roll sensors 48 proYide input to the computin~ means 12.
The eomputing means 12 ealculates the amount of adjustmen-t
neeessary to eliminate body roll, and in turn supplies
signals to the eentral control regulating means 11 which
then adjusts the working fluid pressure in pressure lines 53
eonnected to each vertieal control unit 13.
Vertical control units 13a may also be incorporated
into a vehicle suspension system as shown in Figures 5A
and 6A, and used in the hydraulic circuit for the anti-
roll and damping eircuit shown in Figures 5B and 6B later
described. Eaeh hydraulie eircuit for a suspended wheel
on one side of the vehiele is intereonneeted to the
~1
eorresponding eireuit on the opposite side of the vehiele.
A eentral eontrol regulating means 11 interfaeing with a
computing means 12 may be used to supply pressurized hydrau-
lic fluid to the hydraulic systems shown in Figures 5B and
6s to regulate the vehiele clearanee. In this fashion
hydraulic eireuits whieh ineorporate vertieal control units
13a, as well as a central eontrol regulating means 11 and a
eomputing means 12 may aecomplish the dual purposes of
1) d~mping and eontrolling vehiele body roll, and 2) sim-
ultaneously controlling the vertical ground clearance of the
vehicle at each ihdividual wheel,
Variable loading expansion chambers 87 and
orifiees 88, sueh as those shown in Figure ~A, may be
~;~43~S3
1 incorporated in each hydraulic cixcuit to regulate the
degree of independence of each ~heel suspension unit on
each other suspension unit.
A pressurized hydraulic accumulator ~not shown)
with control valves may be used to regulate the amount
of fluid in each hydraulic circuit. Accordingly, the
vehicle attitude, or front and rear ground clearances, can
be adjusted.
As a further refinement~ this invention also
provides for means to vary the effective suspension spring
constant, as well as means for varying the damping co-
efficient of a shock absorbing means. The shock absorbing
means may be located within the hydraulic circuit in the
form of a variable orifice 88 as shown in Figures 5B or 6B,
or may be independently regulated units 21, such as shown
in Figures 3 and 4. By combining a means for adjusting the
damping co-efficient of the suspension system, as well as
a means for varying the spring constant rate, the dynamic
response of each wheel suspension unit may be optimized for
the road conditions encountered by each wheel.
Figures 3 and 6A as shown are means of varyiny
the effective suspension spring constant rate by means of
a conventional coil spring 14, a lower control arm 6, a
variable fulcrum 17, and a piston and cylinder 16 regulated
by a central control regulating means 11 interfacing a
-13
~3753
1 computing means 120 This aspect o~ the inYentiOn is not
to be limited to use of a conventi~nal coil spring 14 as the
spring suspension means, as other con~entional suspension
means (not shown~ may also be employed~ such as a torsional
bar suspension with a variable length radius arm. Figures
3 and 6A show a particular embodiment of this aspect of
the invention, wherein a piston and cylinder 16 is affixed
at one end to a movable fulcrum 17, and at the other to
the vehicle chassis. The wheel suspending link 6 is
attached to the wheel at one end, and at the other is
pivoted about; the movable fulcrum. The variable fulcrum
piston and cylinder 16 is connected by means of pressure
lines 52 to a central centrol regulating means 11. On
response to signals received from accelerometers 40 mounted
typically on each wheel hub, king pin, or upright and
measuring wheel vertical accelerations, the computing
means 12 sencls signa]s to the central control regulating
means 11, which in turn regulates the working fluid
pressure in pressure lines 52 to cause movement of the
piston 16 which adjusts the location of the fulcrum of a
lower lateral control arm 6, to which a convention spring
means 14 is affixed.
In this way the computing means 12 can adjust
the position of the variable fulcrum 17 which effectively
changes the spring constant of the conventional sprin~
means 14, and effectively optimizes the suspension character-
istics for the road conditions encountered.
37S3
1 To ad~us.t the damping co-efficient of the wheel
suspension system, th~ invention further provides in
Figure 3 a shock absorbing device 21 regulated by a central
control means 11 which interfaces with a computing means
12. Such regulated shock absorb;ng device 21 is affixed
at one end to the veh.icle chass~s and at the other *o the
wheel hub. Figure 4 shows another configuration for the
¦ location of the shock absorbing member or damping unit 21.
I In both embodiments shown in Figure 3 and 4, the
¦ 10 member 21 is connected to means of hydraulic pressure lines
¦ 51 to a central control regulating means 11. Fluid move-
~ ment within these pressure lines 51 to and from each damping
'I unit independently passes through adjustable orifices
¦ within the central control regulating means so that its
! 15 motion in each direction, resulting from wheel bounce and
,
rebound, can be regulated.
Figures 2, 3 and 4 contemplate the damping unit 21,
vertical control unit 13, and conventional suspension means
14 as being mechanically distinct components. In another
embodim2nt of this invention, as shown in Figures 5A and
6A, the above three suspension components may be combined
by use of two piston and cylinder units 60 and 62 affixed
to lower control arm 6 which is in turn affixed to a
suspended wheel.
Moreover, in a further embodiment, as shoWn in
Figure 6B, such components may be combined in a single
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1 hydraulic circuit~ and such individual hydraulic circuits
may be cross-linked to give anti-roll capabilities in
addition to damping control.
Figures 5B and 6s show a left side ~L] and a
right side (Rl of a pair of whee~ suspension members mounted
on the front or rear of a vehicle. It is possible to have
an identical circuit for both the front and rear of the
vehicle, and cross-link such circuits so as to further
increase anti-roll capabilities of the suspension if desired.
Such cross-linking would occur at corresponding junctions
58 and 59 of the front and rear hydraulic circuits, as
shown in Figures 5B and 6B.
Figure 6A and the corresponding hydraulic circuit
of Figure 6B make use of a variable expansion chamber 87.
In another embodiment, such as shown in Figure 5A and the
corresponding hydraulic circuit of 5B, a conventional spring
means 14 may be used to replace the variable expansion
chamber 87 as the vehicle suspension means.
While only shown in Figures 6A and 6B, it is
2~ contemplated that both of the embodiments shown in
Figur2s 5A and 5B and Figures 6A and 6B may incorpoate
a variable fulcrum 17 operated by a central control reg-
ulating means 11 and computing means 12 to vary the effec-
tive spring constant of each wheel suspension system.
In a preferred embodiment as shown in Figure 3,
or the configuration of Figures 6A and 6B wherein provision
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37~3
1 is ~ade for a central control regulating unit 11 to adjust
the variable fulcrum pOSitiOn 17 and ori:fice diameters ~8
two methods may be used to adjust the spring constant and
damping co-efficient of each wheel to obtain optimum dynamic
response of each wheel for given road conditions, thereby
minimizing vehicle chassis movement and as a result increas-
ing the tire-road contact.
The first method provides for additional vertical
accelerometers 50 mounted on the vehicle chassis in prox-
imity to each wheel. The computer means 12 then causes
the variable fulcrum position 17 and damping co-efficient
of damping means 21 or 88 to be ad]usted to result in min-
imum output Erom the accelerometers 50 mounted on the
vehicle bod~, thereby minimizlng vehicle chassis motion.
I .
In an alternative configuration, vertical acceler-
ometers 40 mounted on each wheel are used to provide a
forced vibrational input signal as a function of time for
each wheel to computing means 12 which uses pre-programmed
equations to determine the vehicle chassis movement. These pre-
programmed equations describe the optimum conventional
spring constants ~in terms of variable fulcrum position 17)
and optimum damping co-efficients (in terms of variable
orifice sizes in the central control regulating unit, or
in the hydraulic circuit itself - reference 88 of ~igure 5B
and 6B) each as a function of forced vibrational input.
Computing means 12 for each forced vibrational input selects
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~4375i3
1 the optimum ~ulcxum position 17 and variahle oxifice dla-
meter, and sends the appropri`ate sign~l to the central
control regulat~ng unit so that both the fulcrum positlon
17 and amount of damping through the oxifices may be
adjusted accordingly. Figure 6B shows only manually
operated damping orifice adjustments 88. However it is
recognized a central control regulating means 11 may also be
provided, in addition to a computing means 12,to adjust
the orifices ~y servo or electromechanical means.
In like manner for the provision of computing
means 12 having self-adjusting memory capability for camber
control, in a preferred e~,bodimen-t self-adjusting memory
capability is also provided in -the computing means 12 for
ad~usting the spring constants and the damping co-efficients
contained in the pre-programmed equations. The computing
means 12 is programed to systematically make slight
variation in the signal sent to the central control regu-
lating means 11, which then correspondingly makes slight
adjustments i,n the positicn of the fulcrum 17 and the
variable orifice diameters. As a next step, the computing
means determines whether the output from sensors 48
(which determine the amount of lateral body roll and
longitudinal body roll) has diminished, and if so, maintains
the modified signal heing sent to the central control
regulatin~ unit.
Provision also made for the computing means 12
to store in the memory the magnitude of the amended signal
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:
3~2~3~3
1 for a given vibrati.onal input from the ~er-tical accelero-
meters 40, similar to the self-adjustin~ procedure used
for camber control.
In a further aspect of this ;nvention, transmission
means may be provided to transmit values for data stored
in the memory of the computing means 12 as well as for
transmîtting values of the sensors to a location remote
from the vehicle, so tha~ the data may be analyzed.
As an added feature of this invention, a safety
feature is contemplated whereby the central control reg-
ulating unit 11, or the hydraulic circuit of Figures 5s
or 6B,are provided with an ability to quickly dump working
fluid contained in pressure lines 51, 53 or 70L, 72L and
72~ into a reservoir (not shown~, so that all suspension
1~
systems "collapse". The vehicle chassis underside is
further provided with an undercoating of a durable adhesive
material, whereupon the collapse of the suspension system
results in said chassis underside contacting the road
surface to allow faster stopping in emergency conditions.
The central hydraulic unit 11 and/or the
adjus~able or.ifices 88 of the hydraulic circuit shown in
Figures 5B and 6B would normally be accessable to the
driver, so that adjustments to the wheel loadings, dampenings
and stiffnesses could be made while the vehicle is in
motion.
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3753
1 A prime feature of the inYention is its abi.li.ty
to automatically and continuall~ control all adjus~nents
of the suspension system, so as. to provide the opt;mum
settings that achieve the maximum possible t.ire-to-road
contact time and loading, hence the maximum possible corner-
ing force and corner;ng speed.
In another embodirnent, the operator of the vehicle
can manually adjust the various parameters that control
the camber and suspcnsion. The operator would observe the
data received from the various sensors and then manually
Z adjust the various control parameters in accordance with
I the discretion of the operator.
Z Although specific embodiments of the invention
have been described, it will be understood by persons
skilled in the art that functionally equivalent variations
are intended to fall within the scope of the invention.
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