Anti-roll system for a vehicle

First and second cross-bars extend laterally across the width of a vehicle and are pivotally connected intermediate their lengths in scissors fashion. One end of each cross-bar is pivotally connected to a wheel support assembly which is in turn pivotally connected to the vehicle body by a spring and damper assembly. The other end of the first cross-bar is pivotally connected to the vehicle body by a hydraulic cylinder and piston assembly. The other end of the second cross-bar is pivotally connected via a lever to the actuator of a variable flow hydraulic valve. Lateral forces exerted by the wheels and cross-bars relative to the vehicle body during a turn operate the hydraulic valve to send a proportionate amount of hydraulic fluid to the upper or lower portion of the hydraulic cylinder to thereby prevent rolling of the vehicle body.

BACKGROUND OF THE INVENTION 
The present invention relates to vehicle suspension systems, and more 
particularly, to a cross-bar hydraulic suspension system for preventing 
the roll of an automobile during turning. 
When a vehicle is steered through a turn by a driver the vehicle is 
subjected to centrifugal forces tending to roll the vehicle body radially 
outwardly of a circular path of travel of the vehicle. Modern passenger 
cars often have soft suspension springs for a more comfortable ride. 
However in such cars the roll can develope into a large angle due to the 
roll moment produced during the turning of the vehicle, and excessive 
lateral inclination of the vehicle is experienced. As a result, the driver 
and passengers are subjected to more discomfort during the turn, and 
maneuverability and driving safety is also reduced. 
Various anti-roll systems have been proposed for preventing a vehicle from 
rolling during a turn. However they either do not effectively limit the 
roll without sacrificing a smooth ride, or they are unduly complex and 
expensive. 
U.S. Pat. No. 4,354,567 of Puchas and assigned to Daimler-Benz, AG, 
discloses a rear axle assembly including triangular tilted control arms 
which are employed to suspend the driven wheels from the body. When 
increased lateral forces act on the wheels during a turn, the effect 
produced is so-called "lateral force understeer." 
U.S. Pat. No. 4,345,661 of Nishikawa and assigned to Honda, discloses an 
anti-roll system for a vehicle equipped with power steering for producing 
a steering reactive force modulated by the speed at which the vehicle is 
running. The system introduces pressurized hydraulic fluid for the 
steering reactive force into four individual shock absorber type 
assemblies connected with each wheel in a McPherson strut arrangement. 
U.S. Pat. No. 4,281,850 of Studer discloses an anti-sway apparatus 
comprising a transverse beam elastically connected at each end with a 
transverse axle supported by leaf springs. The beam is in turn pivotally 
connected at each end to the vehicle body. 
U.S. Pat. No. 4,277,076 of Hanna discloses a hydropneumatic anti-roll 
suspension system including a hydraulic actuator for suspending each wheel 
from the vehicle body and a spring accumulator. 
U.S. Pat. No. 4,076,275 of Hiruma discloses a hydropneumatic vehicle 
suspension system for body height control including four hydraulic 
piston/cylinder assemblies. 
U.S. Pat. No. 4,054,303 of deKruyff and assigned to General Motors 
discloses a stabilizer bar arrangement for the front end of a vehicle. It 
includes cross-bars secured at their outer ends to the oppositely disposed 
lower control arms and having juxtapositioned inner ends, with a slot 
formed in one cross-bar and a pin mounted in the other cross-bar and 
extending into the slot. 
U.S. Pat. No. 4,030,777 of Rabenseifner and assigned to Volkswagenwerk, AG, 
discloses a suspension system having separate hydraulic cylinders for each 
wheel. The movement of the piston in each cylinder in response to 
different loadings of the associated wheel of the vehicle controls the 
flow of pressurized fluid to and from the device so as to maintain the 
piston within a predetermined range of positions relative to the cylinder. 
U.S. Pat. No. 3,893,680 of Marcillat et al. discloses a device for limiting 
transverse leaning of a vehicle which utilizes pendulum type electric 
switches for controlling the flow of hydraulic fluid into and out of 
multiple cylinders. 
U.S. Pat. No. 3,885,809 of Pitcher discloses an anti-roll suspension system 
in which a hydraulic strut for each wheel is controlled. 
U.S. Pat. No. 3,871,681 of Piniot and assigned to Peugeot discloses a 
McPherson strut type assemblies supporting a pair of vehicle wheels, the 
assemblies being connected with a hydraulic pump for leveling or adjusting 
the trim of the vehicle. 
U.S. Pat. No. 3,820,812 of Stubbs and assigned to Rover, discloses an 
active anti-roll suspension system including four hydraulic 
piston/cylinder assemblies acted upon by corresponding control units. 
U.S. Pat. No. 3,752,497 of Enke et al. and assigned to Daimler-Benz, 
discloses another anti-roll suspension system including an actively 
controlled hydraulic piston/cylinder assembly for each wheel. A control 
valve is controlled during turns by a lateral acceleration pick-up. 
U.S. Pat. No. 3,038,739 of Vogel discloses another anti-roll suspension 
system for a vehicle in which separate hydraulically controlled cylinders 
are connected between the supporting A-arms of an associated wheel. 
U.S. Pat. No. 3,016,101 of Fiala and assigned to Daimler-Benz, discloses a 
system for improving the steering reaction of a vehicle. The system 
includes a hydropneumatic cylinder for each wheel, and the cylinders are 
operatively connected to a common control. 
U.S. Pat. No. 2,976,052 of Hanna and assigned to Westinghouse, discloses 
another anti-roll system for a vehicle in which includes hydraulically 
controlled shock absorbers for each wheel. 
Finally, U.S. Pat. No. 2,137,947 of Moore discloses another vehicle 
anti-roll system which includes a pair of double acting hydraulic shock 
absorbers that cooperate with a single transverse rear axle. 
SUMMARY OF THE INVENTION 
Accordingly, it is the primary object of the present invention to provide 
an improved anti-roll suspension system for a vehicle. 
It is another object of the present invention to provide such a system 
which does not sacrifice ride smoothness. 
It is another object of the present invention to provide such a system 
which is less complex than prior anti-roll suspension systems. 
Yet another object of the present invention is to provide such a system 
which reacts more quickly upon entering a turn than prior anti-roll 
systems. 
Still another object of the present invention is to provide such a system 
which is not adversely affected by bumps. 
Another object of the present invention is to provide such a system which 
is less costly and more reliable than prior anti-roll systems. 
Yet another object of the present invention is to provide such a system 
which operates proportionally to supply more roll resisting force on 
sharper turns and during turns taken at higher speeds. 
Still another object of the present invention is to provide such a system 
which can be incorporated into conventional automobile designs with a 
minimum of structural modification. 
Accordingly, in the illustrated embodiment of the present invention first 
and second cross-bars extend laterally across the width of a vehicle and 
are pivotally connected intermediate their lengths in scissors fashion. 
One end of each cross-bar is pivotally connected to a wheel support 
assembly which is in turn pivotally connected to the vehicle body by a 
spring and damper assembly. The other end of the first cross-bar is 
pivotally connected to the vehicle body by a hydraulic cylinder and piston 
assembly. The other end of the second cross-bar is pivotally connected via 
a lever to the actuator of a variable flow hydraulic valve. Lateral forces 
exerted by the wheels and cross-bars relative to the vehicle body during a 
turn operate the hydraulic valve to send a proportionate amount of 
hydraulic fluid to the upper or lower portion of the hydraulic cylinder to 
thereby prevent rolling of the vehicle body.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, a pair of front wheels 10 and 12 are each rotatably 
mounted on corresponding axle assemblies 14 and 16 which are in turn 
connected to the lower ends of a pair of spring and damper assemblies 18 
and 20, respectively. Each of the spring and damper assemblies includes a 
shock absorber such as 22 whose upper end is pivotally mounted to the 
vehicle frame or body 24 with a rubber mount 26. A coil spring such as 28 
surrounds each of the shock absorbers and is compressed between the 
vehicle body and the corresponding axle assembly as the corresponding 
wheel moves up and down relative to the vehicle body. 
Referring to FIG. 2, a pair of compression struts 30 and 32 pivotally 
connect the outer ends of corresponding cross-bars 34 and 36 to lower 
portions of the vehicle body or frame 24 on either side thereof. These 
compression struts maintain longitudinal location of the wheels relative 
to the vehicle body. The cross-beams 34 and 36 are pivotally connected 
intermediate their lengths in scissors fashion by a bolt and spacer 
assembly 38. Referring to FIG. 1, one end of the cross-bar 36 is pivotally 
connected to the lower end of a lever 40 which is in turn pivotally 
connected to the vehicle body 24 via pin and bracket assembly 44. The 
other end of the cross-bar 36 is pivotally connected to the axle assembly 
16 via ball joint 46. One end of the other cross-bar 34 is pivotally 
connected to the other axle assembly 14 via ball joint 48. The other end 
of the cross-bar 34 is pivotally connected to the lower end of a hydraulic 
cylinder and piston assembly 50, the upper end of which is pivotally 
mounted to the vehicle body 24. This hydraulic assembly 50 is controlled 
as hereafter described to move the cross-beams in a manner that will 
prevent rolling of the vehicle body during a turn. 
Referring to FIG. 2, a pair of steering arms 52 and 54 are connected to and 
extend forwardly from the axle assemblies 14 and 16, respectively. These 
arms are pivotally connected to links 56 and 58 which are moved 
transversely relative to the vehicle body by a power steering actuator 60. 
Referring again to FIG. 1, the upper end of the lever 40 extends through an 
opening 62 in the vehicle body into the engine compartment. A movable 
actuator 64 of a hydraulic valve 66 is pivotally connected to the upper 
end of the lever 40. The valve is rigidly mounted to a suitable structure 
in the engine compartment and is used to control the flow of hydraulic 
fluid to and from the hydraulic piston and cylinder assembly 50. It will 
be understood that lateral movement of the wheels (left or right in FIG. 
1) relative to the vehicle body will cause the lever 40 to pivot and move 
the actuator 64 of the valve 66 a proportional amount. 
Referring to FIG. 3, the valve 66 is of the variable flow type and is more 
fully described in U.S. Pat. No. 3,602,104. Movement of the valve actuator 
64 by the lever 40 in either direction from a neutral middle position 
causes a similar movement in the valve spool from its neutral position. 
This opens a variable orifice and establishes a direction of flow. A 
compensator piston automatically controls flow by maintaining a fixed 
pressure across the selected orifice opening. Notches machined in the 
directional control spool provide a variable orifice opening to the 
selected work port when the spool is shifted from its neutral position. 
Additional lands on the spool provide a path to the return port from the 
opposite work port completing the four-way valve action. 
Referring still to FIG. 3, a hydraulic pump, such as the power steering 
pump 68, pumps hydraulic fluid from a reservoir 70 to the pressure inlet P 
of the valve 66 via conduits 72, 74 and 76 and power steering actuator 60. 
A port pressurized (spool out) outlet C1 of the valve is connected to one 
end of the hydraulic piston and cylinder assembly 50 via conduit 78. A 
port pressurized (spool in) inlet C2 of the valve is connected to the 
other end of the hydraulic piston and cylinder assembly 50 via conduit 80. 
A return outlet R of the valve 66 is connected via conduit 82 to the 
reservoir. Another conduit 84 connects a low pressure outlet form the 
hydraulic piston and cylinder assembly 50 to the reservoir. This low 
pressure outlet is covered and sealed by the piston 85 when the piston is 
in its intermediate position shown in FIG. 3. This occurs when both wheels 
10 and 12 are in their normal positions. The length of the piston then 
limits the amount of correction possible during cornering. The outlet to 
the conduit 84 serves as a pressure relief valve. The system thus operates 
on relative position rather than relative pressure. 
Having described the structure of the preferred embodiment of my invention, 
its operation will now be described. Assume that FIG. 1 is a front end 
view of the vehicle. Assume further that the vehicle makes a right turn at 
a relatively high rate of speed. The resulting lateral movement of the 
wheels 10 and 12 and the cross-bars 34 and 36 to the left in FIG. 1 
relative to the vehicle body pivots lever 40 clockwise and pushes the 
actuator 64 of valve 66 into the valve. The outlet C1 and inlet C2 of the 
valve are connected to the hydraulic cylinder 50 so that hydraulic fluid 
is pumped into the top of the cylinder, forcing its piston 85 downwardly 
along with the end of the cross-bar 34 connected thereto. This in turn 
prevents the vehicle body from rolling in a clockwise direction. The 
system is proportional in that valve 66 delivers more fluid to the top of 
the cylinder 50 the more the vehicle body tries to move laterally to the 
right relative to the wheels. Because of the geometry of the system and 
the design of the hydraulic circuit, the system doesn't have to stabilize, 
and it prevents rolling of the vehicle body from the outset of a turn. 
Also, the system works during a wide range of vehicle velocities. 
Referring still to FIG. 1, assume that the vehicle makes a left hand turn. 
The wheels and cross-bars start to move laterally to the right relative to 
the vehicle body. This pivots lever 40 counter-clockwise, moving actuator 
64 outward from the valve 66. Hydraulic fluid is then pumped into the 
bottom of the cylinder 50, forcing its piston upwardly along with the end 
of the cross-bar 34 connected thereto. This prevents the vehicle body from 
rolling in a counter-clockwise direction. 
The spring and damper assemblies 18 and 20 function normally during turns 
and straight travel. If either wheel hits a bump or hole, the cylinder 50 
does not have fluid pumped into it but rather reacts passively and 
operates as a third damper. This is desirable on rough roads. Because of 
the connected cross-bars and the forward steering linkage the turning of 
the front wheels at the start of a turn acts as an initial input to the 
hydraulic circuit. The system is therefore "pre-loaded" and reacts quickly 
to prevent rolling of the vehicle body. During turns, the body does not 
roll so the spring and damper assemblies still have their full degree of 
movement available to absorb bumps. It will be noted that the cross-bars 
extend transversely a substantial proportion of the lateral distance 
between the front wheels. Therefore the radius of up and down arcuate 
travel of each of the front wheels is very long. Because of this the 
desired anti-rolling action can be accomplished with relatively small 
movements of the piston inside the cylinder 50. Also there is plenty of 
ground clearance beneath the cross-bars. 
Having described a preferred embodiment of my anti-roll suspension system, 
it will be apparent to those skilled in the art that my invention may be 
modified in both arrangement and detail. For example a different hydraulic 
circuit may be utilized which could include a different valve, a separate 
pump and multiple actuating cylinders. The system could be adapted to 
suspensions other than the McPherson strut type. Therefore the protection 
afforded by invention should only be limited in accordance with the scope 
of the following claims.