Note: Descriptions are shown in the official language in which they were submitted.
CA 02476163 2004-07-30
TORQUE REACTION CONTROL LINK
[001] BACKGROUND OF THE INVENTION
[002] Field of Invention
This invention relates to a rigid drive axle suspension system for motor
vehicles.
[003] Description of Prior Art
[004] Typically, as part of an automobiles suspension, the driveshaft between
the
engine/transmission and the rigid drive axle gear housing is enclosed in a
"torque
tube." The torque tube is rigidly attached to a drive axle/gear housing
assembly at one
end and the other end has a"balP' that is enclosed by "ball drive housing"
that is
attached to the output end of the transmission. Inside the "ball" is the
universal joint
that rotates the driveshaft inside the "torque tube." At the axle gear housing
the
driveshaft rotates the pinion gear through a straight splined coupling.
[005] This design has severe limitations in that the complete axle housing has
to
pivot from the "ball" at the transmission in all planes. This makes it
difficult to control
the bump and roll steer of the axle as desired.
[006] Presently, many race cars use a modified form that incorporates a
sliding or
"slipper ball" end of the torque tube that allows the torque tube's length to
change.
This allows some design freedom, but still has limitations, in that there is
no allowance
for lateral shifting of the axle perpendicular to the torque tube. To overcome
these
shortcomings many other cars now use a torque arm with an open driveshaft. The
torque arm is rigidly attached to the axle housing and extends toward the
transmission.
The end of the torque arm attached to the chassis near the transmission may be
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mounted in rubber. Sometimes it is attached to the chassis through a pivotally
connected short vertical link.
[007] Other designs typically have the torque arm attached to the chassis
through a
shock absorber with a parallel spring. This allows the end of the torque arm
to move in
all planes with the vertical plane controlled by the spring and shock
absorber.
[008] A torque arm has limitations on the length of the side view swing arm
(SVSA)
because of the placement of the engine/transmission in the chassis of the
vehicle. It
may also intrude into the body of the vehicle.
[009] All of these designs are limited, because the length of the torque tube
or
torque arm is restricted by the distance between the rigid drive axle and the
transmission. Because of this limitation, the torque reaction is fed into the
chassis at or
less than one half of the wheelbase of the vehicle. This causes the torque
reaction to
lift the chassis both at the front and at the rear. The lifting of the chassis
at the end
where the drive axle is located decreases the sprung weight and increases the
undamped weight on the drive axle, thereby reducing the control of the axle by
the
shock absorbers, when the wheels and axle move vertically over irregular
terrain.
[0010] There is also a considerable change of the pinion angle in the negative
direction when the axle is displaced vertically with the short torque tube or
torque arm.
This change in the negative direction of pinion angle causes forward
rotational scrub of
the tire contact patch on the ground, and when accelerating, a loss of
traction. Pinion
angle, usually measured in degrees is the convergent angle formed by the
planes of
the horizon and the longidutinal axis of the pinion gear intersecting. Zero
pinion angle
is when the planes are parallel. Negative pinion angle is when the planes are
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convergent toward the center of the vehicle and positive pinion angle is when
they are
convergent away from the center.
[0011] Various vehicle suspension systems have been designed to allow a
vehicle to
maintain traction of the drive axle tires when accelerating over irregular
terrain. United
States Patent No. 2,300,844 (Olley) discloses a four link suspension having
upper links
that are shorter than the lower links. In this invention the instant center
produced by the
projection lines of the upper and lower links intersecting will move closer to
the drive
axle when the axle goes into a bump condition. The problem with this design is
the
side view swing arm (SVSA) is relatively short and becomes shorter with the
movement of the instant center toward the drive axle which causes an increase
in the
pinion angle change in the negative direction and the conversion of sprung
weight on
the drive axle to direct vertical force or undamped weight on the tires or
road wheels
thus decreasing the ability of the tires to maintain traction over irregular
surfaces while
accelerating.
[0012] Another vehicle suspension systems is disclosed in United States Patent
No.
3,575,253 (Brumm) in which a rigid driven rear axle is connected adjacent each
end of
the vehicle body by single longitudinal link and by a spring strut consisting
of a helical
spring and a telescopic shock absorber. The projected line of the link
intersects with
the projected line of the vehicles chassis and the resulting instant center
lies at a point
beyond the axle opposite the drive axle. This awkward configuration results in
the
instant center shifting from one end of the vehicle to the opposite end when
the drive
axle moves into a bump condition. The problem with this design is that the
when the
drive axle moves into a bump condition the torque reaction of the axle when
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accelerating will pull the vehicle's chassis down at the drive axle decreasing
available
chassis clearance to the ground, drive axle clearance to the chassis and the
springs
and shock absorbers available stroke. Another problem with this design is that
it calls
for the spring strut or shock absorber bearing the axle's reaction forces in a
bending
mode.
[0013] Thus it is readily apparent that there is a longfelt need for a vehicle
suspension system that positions the instant center closer to the opposite
axle than the
drive axle that will remain at a relatively static position or move away from
the drive
axle toward or beyond the opposite axle during a bump condition. A significant
deficiency with the previous developed solutions, as well as many other
similar
devices, is that they provide a vehicle suspension system that limits the
ability of the
vehicle's drive axle tires to maintain traction when accelerating over
irregular terrain
andlor puts the drive axle reaction forces on the spring strut or shock
absorber rather
than the axle attachment structures. The present invention satisfies the above-
mentioned needs, as well as others, and overcomes the deficiencies in devices
heretofore developed.
[0014] SUMMARY OF THE INVENTION
[0015] The invention relates to a suspension system for a motor vehicle that
controls
the torque reaction of the rigid drive axle and the longitudinal position of
the drive axle
in relationship to the vehicle's chassis comprising a chassis, a rigid drive
axle, an
opposite axle and road wheels attached to the ends of each axle, a torque
reaction
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control link positioned longitudinally of the motor vehicle between the road
wheels and
with one or two pairs of longitudinal control arms pivotally attached to the
rigid drive
axle, positioned longitudinally of the motor vehicle. The torque reaction
control link is
positioned at a lower elevation than the pairs of longitudinal control arms
and between
and proximate to the road wheels for controlling torque reaction of said rigid
drive axle,
in combination with said at least one torque reaction control link. Each pair
of
longitudinal control arms are pivotally connected to the rigid -drive axle at
one end and
to the chassis at the other end, so that each of which longitudinal control
arms has an
effective projection line longitudinally of the motor vehicle. The torque
reaction control
link is pivotally connected to the rigid drive axle at one end and to the
chassis at the
other, so that the torque reaction control link has a longitudinal plane that
extends
longitudinally of the motor vehicle and whereby the effective projection lines
of the pair
or pairs of longitudinal control arms and the longitudinal plane of the torque
reaction
control link intersect each other forming a convergent angle at an instant
center located
closer to the opposite axle than to the rigid drive axle and that when a force
moves the
rigid drive axle vertically up the convergent angle does not increase.
[0016] It is an object of the present invention to provide a torque reaction
control link
in a lower position than a torque tube or torque arm so that there is no
intrusion into the
vehicles body.
[0017] It is a further object to provide a torque reaction control link on a
rigid drive
axle suspension with a proper length and installation angle from horizontal
and a side
view swing arm (SVSA) that may be any length desired that will remain the same
or
lengthen when the axle moves up vertically into a bump condition.
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[0018] Still a further object of the present invention is to provide a torque
reaction
control link suspension that minimizes pinion angle change in the negative
direction
when the axle moves up vertically into a bump condition.
[0019] Still another object of the present invention is to provide a torque
reaction
control link suspension to minimize the conversion of sprung weight on the
drive axle to
an undamped vertical force on the tires.
[0020] Still another object of the present invention is to provide a torque
reaction
control link suspension for a rigid drive axle suspension that allows a
vehicle to
maintain traction of the drive axle tires when accelerating over irregular
terrain.
[0021] Still another object of the present invention is to provide a torque
reaction
control link suspension in which no bending moments will be induced into the
shock
absorbers or spring struts.
[0022] BRIEF DESCRIPTION OF DRAWINGS
[0023] FIG. 1 is a side view of a prior art torque tube rigid drive axle
suspension for a
motor vehicle.
[0024] FIG. 2 is a top view of a prior art torque tube rigid drive axle
suspension for a
motor vehicle.
[0025] FIG. 3 is a side view of a prior art torque arm rigid drive axle
suspension for a
motor vehicle.
[0026] FIG. 4 is a top view of a prior art torque arm rigid drive axle
suspension for a
motor vehicle.
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[0027] FIG. 5 is a side view of a partially decoupled open or closed tube
rigid drive axle
suspension for a motor vehicle depicting a preferred embodiment of a torque
reaction control
link of the present invention.
[0028] FIG. 6 is a top view of a partially decoupled open or closed tube rigid
drive axle
suspension for a motor vehicle depicting a preferred embodiment of a torque
reaction control
link of the present invention.
[0029] FIG. 7 is a side view of a closed tube rigid drive axle inverted three
link suspension
system for a motor vehicle depicting another preferred embodiment of a torque
reaction
control link of the present invention.
[0030] FIG. 8 is a top view of a closed tube rigid drive axle inverted three
link suspension
systems for a motor vehicle depicting another preferred embodiment of a torque
reaction
control link of the present invention.
[0031] DESCRIPTION OF THE PREFERRED EMBODIMENT
[0032]
[0033] At the outset, it should be clearly understood that like reference
numerals are
intended to identify the same structural elements, portions, or surfaces
consistently throughout
the several drawing figures, as may be further described or explained by the
entire written
specification of which this detailed description is an integral part. These
embodiments should
not be construed as the only applications that the inventions may be used.
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[0034] A significant deficiency with the previously developed suspension
systems
such as those depicted in FIGS. 1-4, as well as many other similar devices, is
that they
provide a vehicle suspension system that limits the ability of the vehicle
drive axle tires
to maintain traction when accelerating over irregular terrain and/or puts the
drive axle
reaction forces on the spring strut or shock absorbers rather than the axle
attachment
structures. Generally these axles are fitted with birdcages and when birdcages
are
used the axle becomes known as decoupled. A decoupled rigid drive axle is one
in
which the longitudinal control and the torque reaction control are independent
of each
other. A birdcage is a device with a bearing that has an inside diameter that
fits over
the outside diameter of an open or closed axle tube. The bearing is retained
in a
housing and the housing has upper and lower brackets rigidly attached to it.
The
brackets are nominally positioned above and below the axle's vertical center.
Each
bracket has an attachment point for pivotally connecting a longitudinal
control arm. An
open tube axle is a rigid drive axle that serves two purposes: the open tube
axle is a
rigid beam that connects the wheels together and it rotates the wheels
simultaneously.
Birdcages are needed to allow the open tube axle to rotate. Sometimes, closed
tube
rigid drive axles are fitted with birdcages because the design of the
suspension system
requires a decoupled axle but for various reasons an open tube axle is not
wanted. A
closed tube rigid drive axle has the rotating axles enclosed in housings
called tubes.
The tubes extend outward from both sides of the drive axle's gear housing to
hubs and
wheels. Any rigid drive axle that uses bird cages must have a device such as a
torque
tube or a torque arm that are rigidly attached to the drive axle's gear
housing and
pivotally attached to the vehicle's chassis to keep the gear housing from
rotating about
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the axle. The torque reaction control link of the present invention replaces
the heavier
and more costly torque tube or torque arm.
[0035] The invention relates to a torque reaction control link for a partially
decoupled
open or a closed tube rigid drive axle suspension or the third control link
for an inverted
three link suspension for a closed tube rigid drive axle that has the third
link attached
pivotally to the bottom of the rigid drive axle housing assembly. The
preferred
embodiment of the present invention uses a straight line mechanism commonly
called
a Watt's Link, proximate each road wheel, for the sole longitudinal control of
the rigid
drive axle. This mechanism is designed using three components. In this
application an
approximate vertical center component provides a means to pivotally connect
two
approximately horizontal components to the rigid drive axle. The approximate
vertical
component is an axle attachment structure called a birdcage which is rotatably
mounted and laterally secured as a means for attachment to the rigid drive
axle. The
two approximately horizontal components are called upper and lower
longitudinal
control arms. The upper longitudinal control arm is pivotally connected to the
upper
bracket of the birdcage and the lower longitudinal control arm is pivotally
connected to
the lower bracket of the birdcage. The opposite ends of each of the
longitudinal control
arms are pivotally connected to the chassis of the motor vehicle, in opposite
directions
longitudinally and approximately perpendicular from the rigid drive axle. With
proper
design and arrangement of the components the rigid drive axle can be made to
move
in an approximate straight vertical line over a short span. Perpendicular to
the
approximate straight vertical movement of the rigid drive axle is the
effective
longitudinal control of the axle. Because the vertical movement is nearly
straight the
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longitudinal control point is close to infinity; thus an effective projected
longitudinal
control arm is near infinite in length. The torque reaction control link of
the present
invention is limited in length and is positioned longitudinally in the motor
vehicle, lower
than the longitudinal control arms and the installed horizontal slope of the
torque
reaction control link must be such that the longitudinal plane through the
pivotal
connection points below the rigid drive axle and the motor vehicle's chassis
of the
torque reaction control link must converge and intersect with the effective
projected
longitudinal control arm of the Watt's Link, nearer the opposite axle than the
rigid drive
axle. The point where they intersect is called an instant center and the
horizontal
distance from the rigid drive axle to the instant center is called a side view
swing arm.
When the rigid drive axle moves vertically up, the horizontal slope of the
torque
reaction control link will change more than the slope of the effective
projected
longitudinal control arm of the Watt's Link, because it is shorter. The
convergent angle
formed by the intersection of the longitudinal plane of the torque reaction
control link
and the effective projected longitudinal control arm of the Watt's Link will
become more
acute and the instant center will move further from the rigid drive axle
toward the
opposite axle or beyond. The side view swing arm will lengthen.
[0036] Adverting now to the drawings, FIG. 1 is a side view of a prior art
torque tube
rigid drive axle suspension for a motor vehicle. Torque tube 12 is rigidly
attached to
rigid drive axle/gear housing assembly 10 at one end, the other end is
attached to ball
13 that is enclosed in a housing (not shown) affixed to the transmission
output end.
The side view swing arm (SVSA) 14 for a torque tube suspension is the
horizontal
distance from the center of rigid drive axle/gear housing assembly 10 to pivot
point 15
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of the torque tube 12 at the output end of the vehicle transmission. A problem
with this
basic design is that the torque tube has limitations on the length of the side
view swing
arm (SVSA) because of the placement of the engine/transmission in the chassis
of the
vehicle. Furthermore when the axle moves vertically into bump the pinion angle
changes in a negative direction which results in forward rotational scrub of
the road
wheels. There has been a longfelt need to lengthen the side view swing arm
without
moving the engine/transmission further from the rigid drive axle.
[0037] FIG. 2 is a top view of prior art torque tube rigid drive axle
suspension for a
motor vehicle. Torque tube 12 is rigidly attached to rigid axle/gear housing
assembly
which is mounted to rigid drive axle 11. Mounted at opposite ends of rigid
drive axle
11 are road wheels 16. Rigid drive axle 11 in this type of suspension system
is either
an open tube or a closed tube drive axle. An open tube is a rigid drive axle
that serves
two purposes: it is a rigid beam that connects the left and right road wheels
together
and it rotates the road wheels simultaneously. A closed tube axle is a rigid
drive axle
that has the rotating axles enclosed in housings called tubes that extend from
both
sides of the gear housing outward to the road wheels. FIGS. I and 2 do not
show
transmission, chassis, axle attachment structures, longitudinal control arms,
track bar,
springs or shock absorbers for clarity.
[0038] FIG. 3 is a side view of prior art torque arm rigid drive axle
suspension for a
motor vehicle. Torque arm 18 is generally oriented in a longitudinal direction
toward the
transmission. One end of torque arm 18 is rigidly attached to a rigid drive
axle/gear
housing assembly 10 and the other end is attached to the chassis near the
transmission and may be mounted in rubber or pivotally connected to chassis 30
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through vertical link 19. SVSA 14 for a torque arm used in conjunction with a
rigid drive
axle suspension is the horizontal distance from the center of rigid drive
axle/gear
housing assembly 10 to pivot point 17 proximate the vehicles chassis. The same
problem that exists with a suspension system that includes a torque tube is
present
with this basic design. The SVSA for the torque arm is dependent on the length
of the
torque arm which in turn is limited by the placement of the
engine/transmission in the
chassis of the vehicle. Clearly there has been a longfelt need to lengthen the
SVSA
when the axle moves vertical into bump position without having to physically
lengthen
the torque arm. The vehicle suspension system of the present invention (one
that
positions the instant center closer to the opposite axle than the drive axle,
that will
remain at a relatively static position or move away from the drive axle toward
or beyond
the opposite axle during a bump condition) does not have the limitation in
length of the
side view swing arm.
[0039] FIG. 4 is a top view of a prior art torque arm rigid drive axle
suspension for a
motor vehicle. Mounted at opposite ends of rigid drive axle 11 are road wheels
16.
Torque arm18 is rigidly attached to rigid drive axle/gear housing assembly 10.
FIGS. 3
and 4 do not show transmission, drive shaft, axle attachment structures,
longitudinal
control arms, track bar, springs or shock absorbers. The drawings of the drive
axles
shown in FIGS. 1-4 do not show any longitudinal control for clarity.
[0040] Unlike the decoupled rigid drive axle depicted in FIGS. 1-4 the
preferred
embodiments of the instant invention depicted in FIGS. 5-8 show a torque
reaction
control link for a partially decoupled open or a closed tube rigid drive axle
suspension
or a third control link on an inverted three link suspension for a closed tube
rigid drive
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axle that has the third link attached pivotally to the bottom of the rigid
drive axle. A
partially decoupled rigid drive axle uses the torque reaction control link of
the present
invention and the longidutinal control arms in combination, to control the
axle's torque
reaction, but the longitudinal control of the axle is independent or decoupled
from the
torque reaction control.
[0041] FIG. 5 is a'side view of a partially decoupled open or closed tube
rigid drive
axle suspension for a motor vehicle depicting torque reaction control link 28
of the
present invention. At the outboard ends of rigid drive axle 11, near the road
wheels 16,
axle attachment structures 20 (in this case birdcages) are rotatably mounted
and
laterally secured to rigid drive axle 11. Upper longitudinal control arms 22
are a pair of
arms, pivotally connected to upper brackets on axle attachment structures 20
and their
opposing ends are pivotally connected to chassis 30 in the direction away from
the
opposite axle (not shown on drawing). Upper longitudinal control arms are
positioned
above the rigid drive axle and extend longitudinally of the vehicle. Lower
longitudinal
control arms 24 are a pair of arms, that are positioned longitudinally of the
vehicle and
are pivotally connected to lower brackets on axle attachment structure 20 and
their
opposite ends are pivotally connected to chassis 30 in the direction of the
opposite axle
(not shown on drawing). Lower longitudinal control arms 24 are pivotally
connected to
axle attachment structures 20 at an elevation below the rigid drive axle. The
two pairs
of longitudinal arms control the fore and aft location of the axle in
relationship to the
vehicle, independent of the torque reaction control and therefore the
longitudinal
control is decoupled. Lower axle attachment structure 26 is rigidly attached
to the
underside of the rigid drive axle/gear housing 10 to which one end of torque
reaction
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control link 28 is pivotally connected. The other end of torque reaction
control link 28 is
pivotally connected to chassis 30 toward the opposite axle (not shown on
drawing).
Torque reaction control link 28 is positioned at lower elevation than
longitudinal control
arms 22 and 24. The torque reaction control of the axle is achieved with the
longitudinal control arms working in combination with the torque reaction
control link,
therefore the torque reaction control is not decoupled. There is an effective
projection
line 23 for longitudinal control for rigid drive axle 11, used in.conjunction
with birdcages
as the axle attachment structures. If upper and lower longitudinal control
arms 22 and
24 are not parallel to each other longitudinally, the effective projection
line 23 for
longitudinal control passes through the convergent point of upper and lower
longitudinal control arms 22 and 24 individual projected lines 21, and the
longitudinal/vertical center of the rigid drive axle. If upper and lower
longitudinal control
arms 22 and 24 are parallel to each other longitudinally as shown in FIG. 5;
effective
projection line 23 for longitudinal control is parallel to upper and lower
longitudinal
control arms 22 and 24, and passes through the longitudinal/vertical center of
rigid
drive axle 11.
[0042] Effective projection line 23 for longitudinal control converges at an
angle with
longitudinal plane 27 for the torque reaction control link and the point at
which effective
projection line 23 and longitudinal plane 27 intersect is instant center 29.
Instant center
29 is the point from where the complete rigid drive axle/gear housing assembly
10
rotates about when rigid drive axle 11 moves vertically. The horizontal
distance from
the center of the rigid drive axle/gear-housing assembly to instant center 29
is SVSA
14 for this embodiment of the present invention. The change of the horizontal
slope of
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effective projection line 23 for longitudinal control will be less than the
change of the
slope for torque reaction control link 28 when the rigid drive axle 11 moves
up
vertically. The result of the upward movement of rigid drive axle 11 is that
instant
center 29 will move away from rigid drive axle 11 and SVSA 14 will lengthen.
In both
embodiments of the present invention torque reaction control link 28 may be a
single
link, a pair of parailel links, a pair of links convergent toward the chassis
from the axle,
a pair of links convergent toward the axle from the chassis, a triangular A-
Arm with the
apex at the chassis and the pair of opposite ends at the axle or the apex at
the axle
and the pair of opposite ends at the chassis. Torque reaction control link 28
may have
a hydraulic tracking damper with a compression spring, a spring rod with
compression
springs, or a torque absorber using resilient strut bushings or springs, all
operatively
arranged as part of its length.
[0043] FIG. 6 is a top view of a partially decoupled open or closed tube rigid
drive
axle suspension for a motor vehicle depicting torque reaction control link 28
of the
present invention, longitudinally positioned in between road wheels 16 with
one end
pivotally connected to the chassis 30 toward the opposite axle (not shown on
drawing).
The opposite end is pivotally connected to lower axle attachment structure 26
(not
visible on drawing) because it is rigidly attached below to the rigid drive
axle/gear
housing assembly 10. Axle attachment structures 20 (in this case birdcages)
are
rotatably mounted and laterally secured to the outboard ends of rigid drive
axle 11,
near road wheels 16. Upper longitudinal control arms 22 are pivotally
connected to
upper brackets on axle attachment structures 20, and their opposite ends are
pivotally
connected to chassis 30 away from the opposite axle (not shown on drawing).
Lower
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longitudinal arms 24 are pivotally connected to lower brackets (not visible on
drawing)
on axle attachment structures 20 and their opposite ends are pivotally
connected to
chassis 30 toward the opposite axle (not shown on drawing).
[0044] FIG. 7 is a side view of a closed tube rigid drive axle inverted three
link
suspension for a motor vehicle depicting torque reaction control link 28 as
the third link
of the present invention. Near road wheels 16, axle attachment structures 20
are rigidly
attached to rigid drive axle 11. Upper longitudinal control arms 22 each have
one end
pivotally connected to an axle attachment structure 20, and their opposite
ends are
pivotally connected to chassis 30 toward the opposite axle (not shown on
drawing).
Lower axle attachment structure 26 is rigidly attached to the underside of
rigid drive
axle 11, between road wheels 16. One end of torque reaction control link 28 is
pivotally
connected to the lower axle attachment structure 26 and its opposite end is
pivotally
connected to chassis 30, toward the opposite axle (not shown on drawing).
Torque
reaction control link 28 has to be positioned lower than the longitudinal
control arms.
Effective projection line 23 for longitudinal control converges at an angle
with effective
longitudinal plane 27 for the torque reaction control link, and where the
lines intersect is
instant center 29. Instant center 29 is the point from where the complete
rigid drive
axle/gear housing assembly 10 rotates about when rigid drive axle 11 moves
vertically.
The horizontal distance from the center of the rigid drive axle/gear-housing
assembly to
instant center 29 is SVSA 14 for this embodiment of the present invention. The
change
of the horizontal slope of effective projection line 23 for longitudinal
control will be less
than the change of the slope for torque reaction control link 28 when the
rigid drive axle
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11 moves up vertically. The result of the upward movement of rigid drive axle
11 is that
instant center 29 will move away from rigid drive axle 11 and SVSA 14 will
lengthen.
[0045] FIG. 8 is a top view of a closed tube rigid drive axle inverted three
link
suspension for motor vehicle depicting torque reaction control link 28 as the
third link of
the present invention. Torque reaction control link 28 is longitudinally
positioned
between the road wheels 16 and one end is pivotally connected to chassis 30
toward
the opposite axle (not shown on drawing). The opposite end of torque reaction
control
link 28 is pivotally connected to lower axle attachment structure 26 (not
visible in
drawing), because it is rigidly attached below to rigid drive axle/gear
housing assembly
10. Near road wheels 16, axle attachment structures 20 are rigidly attached to
rigid
drive axle 11. Upper longitudinal control arms 22 each have one end pivotally
connected to an axle attachment structure 20 with their opposite ends
pivotally
connected to chassis 30, toward the opposite axle (not shown on drawing). No
track
bar, springs or shock absorbers are shown in FIGS. 5-8 for clarity.
[0046] A vehicle configured with a suspension system of the instant invention
will be
able to maintain traction of the drive axle tires, when accelerating over
irregular terrain
because there is less pinion angle change in the negative direction. The
change is
caused by the radius of the SVSA moving in an arc when the axle is vertically
displaced. This change can be almost instantaneous when the axle and tires go
into a
bump condition. If the vehicle is accelerating at or near the limit of
adhesion and the
axle and tires are suddenly rotated in a forward direction by the pinion angle
change,
the tires are forced to scrub on the road surface a distance proportional to
the angular
change at the radius of the tires. This causes the tires to lose adhesion or
traction.
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[0047] The drive axle tires of a vehicle equipped with torque reaction control
link 28
of the present invention will maintain traction when accelerating over
irregular terrain
because there is less sprung weight removed from the drive axle and converted
to an
undamped vertical force on the tires. This conversion is caused by the torque
reaction
acting on the chassis in an upward vertical direction, through the suspension
links at
the instant center of SVSA 14. With a SVSA as long as the wheelbase there is
no
sprung weight removed from the drive axle, and more favorable sprung to
unsprung
weight ratio is maintained. This enables the shock absorbers to control the
sprung and
unsprung masses. The tires will then continue to provide traction.
[0048] While the invention has been described with reference to certain
preferred
embodiments, it will be appreciated by those skilled in the art that
modifications and
variations may be made without departing from the spirit and scope of the
invention.
[0049] REFERENCE NUMERALS IN DRAWINGS
10. Axle/Gear Housing Assembly
11. Rigid Drive Axle
12. Torque Tube
13. Ball
14. SVSA
15. Pivot Point
16. Road Wheels
17. Pivot Point
18. Torque Arm
18
CA 02476163 2004-07-30
19. Vertical Link
20. Axle Attachment Structure
21. Projected Lines
22. Upper Longitudinal Control Arm
23. Projection Line
24. Lower Longitudinal Control Arm
26. Lower Axle Attachment Structure
27. Longitudinal Plane
28. Torque Reaction Control link
29. Instant Center
30. Chassis
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