Constant camber suspension

An automobile wheel suspension system which maintains the substantially vertical orientation of the wheel supporting strut during cornering of the vehicle or when a road hazard is encountered. The wheel suspension system utilizes a ball joint to connect the top of the vertically extending wheel strut to the body frame and a bell crank pivoted on the control arm supporting the wheel. The ball joint permits the body or chassis of the vehicle to tilt with respect to the strut while the bell crank maintains the orientation of the strut as the vehicle rolls or when the wheel makes contact with a bump in the pavement.

BACKGROUND OF THE INVENTION 
This invention relates to an independent wheel suspension system for 
vehicles and more particularly to a suspension system especially useful 
for passenger motor vehicles. 
When an automobile is not moving, or is moving in a straight line, the 
tires are theoretically in a vertical position, with the tread flat on the 
surface of the pavement. When the vehicle goes into a turn, it tends to 
lean about its roll axis, which is an imaginary line running along the 
length of the car positioned at about axle height in the rear and close to 
the ground at the front. Weight is transferred to the outer wheels due to 
the effects of centrifugal force. The inside wheels take a drop in loading 
while the outside wheels take the increased loading. 
In addition, with current suspension designs, the tires tend to depart from 
their vertical position, which is measured by camber. Camber is the 
angular measure of a tire's departure from the vertical and is considered 
negative if the tire leans inward toward the body at the top, positive if 
it leans outward at the top. 
When a car makes a turn (i.e., corners) and the body rolls outwardly unless 
the suspension acts to compensate, it will be seen that with zero camber 
as defined above, the tires will depart from vertical with reduced tread 
or tire surface in contact with the road surface. With the outer wheels 
carrying the bulk of the load, it is quite apparent that this can under 
some circumstance be quite a dangerous situation. 
A front end suspension system which has been developed to deal with this 
situation consists of nonparallel, laterally extending arms connected 
between the body of each wheel. This system is quite often referred to as 
the unequal-lengths A-arms due to the fact that the nonparallel arms are 
not equal in length and are A-shaped. This close to vertical during rolls 
and road irregularities which could effect camber. However, this 
suspension is expensive because of the number of parts involved, is not 
suitable for use with rear wheels, and requires more space between the 
body and the wheels resulting in a narrower span of the body for a given 
track dimension. 
The so-called MacPherson strut was developed to deal with some of the 
limitations of the unequal-length A-arms suspension. Simply described, 
this strut involves the use of a simple lateral link and a long strut 
extending up to the unitized body structure, the strut including the coil 
spring and shock absorber. The MacPherson strut is considered a major 
improvement over earlier suspension systems and can readily be used with 
rear wheels as well but it is not quite as effective as the unequal-arm 
front suspension in obtaining proper wheel camber (that is, maintaining 
vertical tire orientation) during cornering of the vehicle and its 
consequent roll. 
The following United States patents show a variety of wheel suspension 
systems currently known and/or in use: U.S. Pat. Nos. 2,198,680, 
2,718,409, 2,846,234, 2,876,018, 3,497,233, 4,159,128, and 4,653,772. None 
of the preceding patents describes the present invention. 
SUMMARY OF THE INVENTION 
The present invention overcomes some of the problems and limitations of the 
MacPherson independent wheel suspension described above by insuring that 
the vertical orientation of the wheel supporting strut remains stable or 
substantially unaltered during cornering or when an obstacle is 
encountered. 
In accordance with a preferred embodiment of this invention there is 
provided a wheel suspension system utilizing a ball joint to connect the 
top of the vertically extending wheel strut to the body frame and a bell 
crank pivoted on the control arm supporting the wheel. The ball joint 
permits the body or chassis of the vehicle to tilt with respect to the 
strut while the bell crank maintains the orientation of the strut as the 
vehicle rolls or when the wheel makes contact with an obstacle in the 
pavement. 
It is thus a principal object of this invention to provide an improved 
wheel suspension system that maintains the orientation of the wheel during 
cornering and other conditions. 
Other objects and advantages of this invention will hereinafter become more 
evident from the following description of a preferred embodiment of this 
invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIGS. 1 and 2, there is illustrated a front wheel suspension 
10 comprising a support arm 12 pivotally mounted at one end to body 
suspension member 14 by a pin 16 for vertical movement of arm 12 as shown 
by the double headed arrow a-b around pin 16. 
On the free end of arm 12 is mounted a ball joint 18 through which is 
attached the lower end of strut 22 which extends up almost or 
substantially vertically. By almost or substantially vertically extending 
herein is meant that the strut is predominantly on a vertical orientation. 
The upper end of strut 22 is attached to body 24 of the vehicle through a 
ball joint 26 which allows body 24 to rotate with respect to strut 22 in 
all directions as shown by double headed arrow c-d. 
Strut 22 supports a member 27 which carries axle 28 for wheel 32. Also 
mounted on strut 22 is a collar 35 which is prevented from moving along 
the length of strut 22 by a pair of stops 36 and 38 mounted on strut 22. A 
bushing (not shown) would be provided within collar 35 to facilitate the 
rotation of strut 22 for steering. 
The upper portion of strut 22 comprises a piston rod 42 riding within the 
tubular part 44 forming a shock absorber and terminating at its opposite 
end in ball joint 26. A spring 46 is mounted between stops 48 and 52 
mounted on piston rod 42 and tubular part 44, respectively. 
It is understood that the vehicle in which suspension 10 is incorporated is 
of common design in which body 24 and body suspension member 14 are 
integral with each other and for this purpose may be represented by a 
connecting body member 54, forming a vehicle body 55. Body 24, member 14 
and member 54 forming vehicle body 55 would rotate together about ball 
joint 26 as shown by double headed arrow c-d. 
At some intermediate point along the length of support arm 12 is located a 
pin 56 which supports pivotally the elbow of a bell crank 58. The bottom 
leg 58a terminates with a pin 62 to which is pivotally attached one end of 
a short link 64 the other end of which is pivotally mounted on body 
suspension member 14 through a pin 66. 
Upper leg 58b of bell crank 58 terminates with a pin 68 to which is 
pivotally attached one end of a strut link 72 the other end of which is 
pivotally attached by way of a pin 74 to collar 35 as illustrated. 
For an illustration of how suspension system 10 maintains the position of 
strut 22 and hence wheel 32 during a body roll, reference is made to FIG. 
3, where body 55 is shown rolling clockwise as indicated by arrowhead d. 
Movement of the various parts is shown in broken lines. Pin 16 drops down 
a particular distance to a new position 16' while pin 56 supporting the 
heel of bell crank 58 drops down a fraction of that distance to a new 
position 56', while pin 62 supporting the free end of leg 58a of crank 58 
drops somewhat less than the distance traversed by pin 16 to a new 
position 62' with the result that bell crank 58 not only drops but also 
rotates counterclockwise. Pin 68 effectively rotates circularly around pin 
74 on collar 35 to a new position 68' with the consequence that strut 22 
virtually remains unchanged in its vertical position. It will be noted 
that ball joint 26 at the top of strut 22 permits body 24 to rotate around 
the upper portion of strut 22 thereby not exerting a translational force 
on strut 22. 
To illustrate the operation of wheel suspension 10 when wheel 32 hits an 
obstacle or drops into a pothole, reference is made to FIG. 4. When wheel 
32 (axle 28) rises sharply because of a bump, strut 22 assumes the 
position shown by numeral 22 compressing spring 46, bell crank 58 rises 
and rotates counterclockwise to a new position shown by numeral 58" so 
that link 72 assumes the position shown by numeral 72". It will be noted 
that while strut 22 does rise along with wheel 32, the vertical 
orientation of strut 22 remains substantially unchanged. 
In a similar fashion, should wheel 32 drop into a rut, bell crank 58 will 
assume the position shown by numeral 58"', and link 72 will assume the 
position shown by numeral 72"'. There again it will be seen that the 
orientation of strut 22 is largely unaffected by the movements of wheel 32 
just described. 
It has been noted that collar 35 is mounted on strut 22 to permit the 
latter to rotate with respect to the former. This arrangement permits 
suspension 10 to be employed with the front wheels to permit strut 22 to 
turn for steering, or, in a four wheel steered vehicle, the rear wheels as 
well. For rear, non-steerable wheels, it may still be desirable to employ 
collars with some degree of rotational movement, if desired, or collar 35 
may be designed not to have that type of action. 
It will be seen from the preferred embodiment of this invention described 
above, it is possible to utilize modern wheel suspension designs in such a 
way as to avoid or minimize the adverse effects of a roll or contacts made 
with bumps or ruts in the pavement on the position of the wheel struts of 
the vehicle. This should bring increased safety to the operation of high 
performance vehicles and provide an additional margin of safety during 
normal operation of a vehicle during an emergency accident avoidance 
situation or where unexpected obstacles appear on the road under high 
speed, cruising conditions. 
While only a preferred embodiment of this invention has been described it 
is understood that many variations thereof are possible without departing 
from the principles of this invention as defined in the claims which 
follow.