Suspension system for automotive vehicles

In a suspension system for an automotive vehicle which comprises a longitudinal shaft fixedly mounted on the vehicle body structure along the fore-and-aft axis, a control arm of the so-called "A" type swingably supported at one end thereof from the shaft by means of a pair of front and rear rubber bushes, and a pair of retainer plates fixed to front and rear ends of the shaft and arranged to receive a load acting on the control arm in the forward or rearward direction through a portion of the respective rubber bushes for restricting forward or rearward displacement of the control arm, a stopper member is secured to the rear portion of the control arm and straddling the rear end of the shaft with a predetermined clearance, the stopper member being brought into engagement with the rear end of the shaft when the load acting on the control arm is larger than a predetermined value.

BACKGROUND OF THE INVENTION 
The present invention relates to a suspension system for automotive 
vehicles, and more particularly to an improvement of a double wishbone 
type suspension, a strut type suspension, and the like. 
Such a conventional suspension system as described above comprises a 
longitudinal shaft fixedly mounted on a vehicle body structure along the 
fore-and-aft axis of the vehicle, a control arm of the so-called "A" type 
swingably supported at one end thereof from the longitudinal shaft by 
means of a pair of front and rear rubber bushes and having a swingable end 
supporting thereon a road wheel, and a pair of retainer plates fixed to 
front and rear ends of the shaft and being arranged to receive a load 
acting on the control arm in the forward or rearward direction through a 
portion of the respective rubber bushes for restricting forward or 
rearward displacement of the control arm. 
In the case that the control arm is adapted as an upper control arm in the 
suspension system, the upper control arm will receive a heavy load acting 
thereon in the forward direction due to braking force of the vehicle or 
shocks from the road in traveling of the vehicle. In the case that the 
control arm is adapted as a lower control arm in the suspension system, 
the lower control arm will receive a heavy load acting thereon in the 
rearward direction due to braking force of the vehicle or shocks from the 
road in traveling of the vehicle. This is caused by the fact that the 
maximum load acting on the control arm in forward traveling of the vehicle 
is extremely larger than that in backward traveling of the vehicle. When a 
heavy load acts on the control arm in the forward or rearward direction, 
one of the retainer plates concentrically receives the heavy load through 
one of the rubber bushes, and the reaction force from the retainer plate 
is given to the front or rear portion of the control arm. For this reason, 
sufficient strength of the rubber bushes, retainer plates, and control arm 
is required to resist the heavy load and reaction force. This means that 
the assembly of the rubber bushes, retainer plates and control arm becomes 
larger in size and causes an obstacle to a small size and light weight 
construction of the suspension system. 
SUMMARY OF THE INVENTION 
It is, therefore, a primary object of the present invention to provide an 
improved suspension system which is designed to disperse the heavy load 
concentrically acting on the retainer plates so as to ensure the strength 
of the rubber bushes, retainer plates and control arm in a possibly small 
construction. 
According to the present invention briefly summarized, the primary object 
is accomplished by provision of a suspension system for an automotive 
vehicle which comprises a longitudinal shaft fixedly mounted on the 
vehicle body structure and extending along the fore-and-aft axis of the 
vehicle, a control arm of the so-called "A" type swingably supported at 
one end thereof from the longitudinal shaft by means of a pair of front 
and rear rubber bushes to be swung upwardly and downwardly, the control 
arm having a swingable end supporting thereon a road wheel, a pair of 
retainer plates fixed to front and rear ends of the shaft and being 
arranged to receive a load acting on the control arm in the forward or 
rearward direction through a portion of the respective rubber bushes for 
restricting forward or rearward displacement of the control arm, and a 
stopper member secured to any one of front and rear portions of the 
control arm and straddling any one of the front and rear ends of the shaft 
with a predetermined clearance, the stopper member being brought into 
engagement with the one end of the shaft when the load acting on the 
control arm is larger than a predetermined value.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, FIGS. 1 and 2 illustrates a front suspension 
system of the double wishbone type which comprises a lower control arm 20 
of the so-called "I" type and an upper control arm 30 of the so-called "A" 
type. A steering knuckle 10 is supported by the swingable end of lower 
control arm 20 to rotatably support a front road wheel 11 thereon, and it 
is operatively connected to a steering linkage 12 to be steered. As well 
seen in FIG. 2, the lower control arm 20 is mounted on a cross-member 41 
of the vehicle body structure by means of a sleeve-like rubber bush 51 to 
be swung upwardly and downwardly. As well seen in FIG. 1, the swingable 
end of control arm 20 is connected to the lower end of steering knuckle 10 
by means of a lower ball joint assembly 13. The lower control arm 20 is 
also connected at its intermediate portion to the front end of a strut bar 
21 and to the lower end of a shock absorber assembly 22. The strut bar 21 
is connected at its rear end to a cross-member 42 of the vehicle body 
structure by means of a cushion assembly 52, and the upper end of shock 
absorber assembly 22 is connected to a stationary bracket 44 by means of a 
cushion assembly 53, as shown in FIG. 1. The bracket 44 is fixedly mounted 
on a side-member 43 of the vehicle body structure. 
The upper control arm 30 is supported from a longitudinal shaft 31 by means 
of a pair sleeve-like rubber bushes 54 and 55 to be swung upwardly and 
downwardly, and the swingable end of control arm 30 is connected to the 
upper end of knuckle 10 by means of an upper ball joint assembly 19. The 
longitudinal shaft 31 is fixedly mounted on the bracket 44 along the 
fore-and-aft axis of the vehicle and is provided at its opposite ends with 
a pair of retainer plates 32 and 33 which are held in place by a pair of 
fastening nuts 34 and 35 threaded on the opposite ends of shaft 31. In the 
practice, the fastening nuts 34 and 35 may be replaced with a pair of 
bolts threaded into the opposite ends of shaft 31. The front retainer 
plate 32 is engaged with an annular flange 54a of rubber bush 54 to 
receive thereon a load acting on the upper control arm 30 in the forward 
direction thereby to restrict the forward displacement of control arm 30. 
The rear retainer plate 33 is engaged with an annular flange 55a of rubber 
bush 55 to receive thereon a load acting on the upper control arm 30 in 
the rearward direction thereby to restrict the rearward displacement of 
control arm 30. 
As can be well seen in FIG. 3, a longitudinal torsion bar 61 is connected 
to the rear portion of upper control arm 30 by means of a torque arm 
member 60 and is located coaxially with the longitudinal shaft 31. The 
torque arm member 60 is fixed to the rear portion of control arm 30 by 
means of a pair of bolts 62 and nuts 63 and straddles the nut 35 at the 
rear end of shaft 31. The bolts 62 are respectively inserted into a collar 
member 64 assembled within control arm 30. The torsion bar 61 is connected 
at its front end to the center of torque arm member 60 by means of sline 
coupling. At the connected portion of torsion bar to torque arm member 60, 
a cover plate 65 is secured to calking to the center of torque arm member 
60, and a dust boot 66 is fixed at its opposite ends to torque arm member 
60 and torsion bar 61 to cover the rear portion of torque arm member 60. 
The cover plate 65 faces to the rear end 31a of shaft 31 with a 
predetermined clearance a, and it will abut against the rear end 31a of 
shaft 31 when a load larger than a predetermined value acts on the control 
arm 30 in the forward direction. In this arrangement, the clearance a is 
determined to be smaller than the maximum flexure of rubber bush flange 
54a. Thus, the cover plate 65 acts as a stopper member to define the 
spline coupling of torque arm member 60 and torsion bar 61. In addition, 
the torsion bar 61 is connected at its rear end to a cross-member of the 
vehicle body structure by means of an anchor bracket (not shown). 
With the construction described above, when the upper control arm 30 
receives a forward load acting thereon due to braking force of the vehicle 
or shocks from the road in traveling of the vehicle, the forward load is 
mainly received by the front retainer plate 32 through the rubber bush 
flange 54a to restrict the forward displacement of upper control arm 30. 
If the forward load is larger than the predetermined value, the cover 
plate 65 abuts against the rear end 31a of shaft 31, and a portion of the 
forward load is received by the rear end of shaft 31 through torque arm 
member 60 and cover plate 65 so that the load acting on the front portion 
of control arm 30 is dispersed. Owing to this dispersion of the forward 
load, the front portion of upper control arm 30 can be fabricated in a 
light weight and small size construction. Furthermore, the abutment of 
cover plate 65 against the rear end of shaft 31 serves to reliably 
restrict relative displacement of torque arm 60 and torsion bar 61. As a 
result, the spline coupling of torque arm 60 and torsion bar 61 is 
maintained in a reliable and stable condition in spite of its simple 
construction. When the forward load is smaller than the predetermined 
value, the cover plate 65 does not abut against the rear end of shaft 31. 
In this instance, both of rubber bushes 54 and 55 act to effectively 
absorb shocks from the road. This means that the rubber bushes 54 and 55 
may be constructed in a relatively small size. 
In the preferred embodiment described above, the present invention is 
adapted to the front suspension system in which the torsion bar 61 is 
connected to the upper control arm 30, but it is obvious that the present 
invention may be adapted to a suspension system of the double wishbone 
type in which a coil spring is disposed between a lower control arm and 
the vehicle body structure, and a stopper member is secured to the rear 
portion of an upper control arm of the so-called "A" type. Furthermore, 
the present invention may be adapted to a front suspension system of the 
strut type in which a stopper member is secured to the front portion of a 
lower control arm of the so-called "A" type and faces to one end of a 
supporting shaft for the lower control arm with a predetermined clearance 
in the fore-and-aft direction of the vehicle. 
In this type of suspension system, when a rearward load acting on the lower 
control arm is larger than a predetermined value, the stopper member abuts 
against the rear end of the supporting shaft to disperse the rearward 
load. 
Having thus described the preferred embodiment of the invention it should 
be understood that numerous structural modifications and adaptations may 
be resorted to without departing from the spirit of the invention.