Cross member for a vehicle having rack and pinion steering

A cross member for use in a motor vehicle having a frame with right and left rails and a rack and pinion steering gear assembly is disclosed. The cross member includes a center portion disposed between the right and left rails and being operative to support a rack and pinion steering gear. The cross member further includes right and left arm portions projecting upwards from the center portion and terminating at first and second ends, respectively. The first and second ends attach to the right and left rails of the motor vehicle frame. The cross member further includes right and left steering gear apertures disposed in the right and left arm portions. The rack and pinion steering gear assembly operatively passes through the apertures, thereby providing maximum free length of the right and left rails and minimum front overhang.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to a cross member for a motor 
vehicle frame. More particularly, the present invention relates to a cross 
member having passages therein to permit the passage therethrough of rack 
and pinion steering linkage. 
2. Disclosure Information 
Motor vehicle frames having longitudinally extending frame rails 
interconnected with transverse cross members are well known in the motor 
vehicle industry. The forward portion of the longitudinal frame rails are 
often designed to absorb energy by plastically collapsing under certain 
impacts. One factor that determines the energy absorbing character of the 
motor vehicle is the "free length" of the frame rail. Specifically, this 
relates to the length of frame extending forward from the forward face of 
the front cross member. 
As is well known, the front cross member serves multiple roles. First, 
unlike a unibody vehicle, cross-members are interspersed between the 
longitudinal rails to provide torsional rigidity to the overall frame 
structure. Second, the front cross member is commonly situated under the 
front of the engine to provide strength for mounting the engine. Third, 
the front cross member provides support for the front suspension 
attachments. The suspension imparts lateral loads on the frame that are 
best resisted by a transverse cross member. 
Recently, another variable has entered the equation for the design of the 
front end of some vehicles, especially those in the sport utility market 
segment. Consumers are demanding vehicles with a minimum "overhang." 
Overhang is one measure of a vehicle's ability to traverse a path having a 
dramatic change in slope, such as a climbing a steep hill, or entering a 
steeply inclined driveway. The vehicle with shorter overhang is less 
likely to drag the front end on the ground. The significant component of 
vehicle overhang under consideration here is the distance from the front 
axle centerline to the leading edge of the vehicle, typically the bumper. 
Therefore, it can be seen that overhang is minimized by locating the front 
axle as far forward as possible. Since the front cross member is typically 
mounted just forward of the front axle, the desire to minimize overhang 
conflicts with the desire to provide maximum "free length" of the frame 
for absorbing energy. 
This conflict has been a significant impediment to incorporating a rack and 
pinion steering gear assembly into such vehicles. It is commonly known to 
those skilled in the art to locate the rack and pinion steering gear 
assembly center line as close to the front axle centerline as possible. 
Typically this has been accomplished by mounting the rack and pinion gear 
assembly on the front or the rear face of the front cross member. 
Unfortunately, the rack and pinion steering gear assembly is as effective 
as the cross member for purposes of compromising free length. As a result, 
these locations consume precious free length otherwise required for energy 
absorption. 
One solution has been to locate the rack and pinion steering gear assembly 
directly beneath the cross member. However, this design significantly 
compromises ground clearance. The unresolved conflicts created by these 
design objectives has prevented the incorporation of rack and pinion 
steering in vehicles of the body on frame design. Instead, as shown in 
FIG. 1, a recirculating ball steering gear with the associated linkage, 
has been used, much to the dissatisfaction of many consumers who prefer 
the tight, crisp steering that is associated with rack and pinion steering 
assemblies. 
Therefore, it would be advantageous to provide a front cross member capable 
of cradling a rack and pinion steering gear assembly and providing the 
strength necessary to support the engine and suspension imposed loads, 
while providing sufficient free length, overhang and ground clearance. 
SUMMARY OF THE INVENTION 
The present invention solves the problems associated with the prior art by 
providing a cross member for use in a motor vehicle frame having right and 
left rails extending substantially parallel to a longitudinal axis of the 
vehicle. The vehicle also includes a rack and pinion steering gear 
assembly extending substantially parallel to a transverse axis of the 
vehicle. 
The cross member includes a center portion disposed between the right and 
left rails and being operative to support a rack and pinion steering gear. 
The cross member further includes right and left arm portions projecting 
upwards from the center portion and terminating at first and second ends, 
respectively. The first and second ends attach to the right and left rails 
of the motor vehicle frame. 
The cross member further includes right and left steering gear apertures 
disposed in the right and left arm portions. The rack and pinion steering 
gear assembly operatively passes through the apertures. 
It is an advantage of the present invention to provide a cross member for a 
motor vehicle having a body on frame design which permits the use of rack 
and pinion steering gear assembly while providing maximum free length of 
the right and left rails and minimum front overhang. These and other 
objects, features and advantages of the present invention will become 
apparent from the drawings, detailed description and claims which follow.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings, FIGS. 2 and 3 show a body-on-frame design of 
a motor vehicle 10. The vehicle 10 includes a body (not shown) that rests 
on right and left rails 12, 14 which are substantially parallel to the 
longitudinal axis of the motor vehicle 10. The rails 12, 14 combine with 
several transversely oriented cross members to form torsionally strong 
frame 16 (shown in part). 
A front cross member 22 is generally positioned adjacent to and 
substantially parallel to a driven front axle 24. In the preferred 
embodiment, the cross member is disposed forward of the driven front axle 
24. As can be seen, the cross member 22 extends between right and left 
rails 12, 14, substantially transverse to the longitudinal axis of the 
motor vehicle. Generally, due to the strength of the frame adjacent to the 
cross member 22, right and left suspensions 26 will depend from the frame 
adjacent to the cross member 22. 
For simplicity, the following description is limited to the left side of 
the suspension, it being understood that the right side is the same, 
except where noted. A road wheel (not shown) attaches to hub 28 which is 
rotatably mounted to a knuckle 30, which is attached to an upper 
suspension member 32 depending pivotally from the rail 14. The knuckle 30 
is also attached to a lower suspension member 34 which depends pivotally 
from the cross member 22. A rack and pinion steering gear assembly 36 
provides steering control to the hub 28 and road wheel assembly (not 
shown). 
Referring now to FIGS. 4-5, the cross member 22 of the present invention 
can be seen. The cross member 22 includes a center portion 40 extending 
between right and left arm portions 42, 44, which in turn project upward 
to first and second ends, 45, 47, respectively. The right and left arm 
portions 42, 44 form an angle, .theta., with the center portion 40, which 
ranges in value between 85 and 165 degrees. The first and second ends 45, 
47 provide the necessary attachment points to the right and left rails 12, 
14 of the motor vehicle frame. Attachment may be by any conventional 
method, including, but not limited to, welding or fastening with rivets or 
threaded fasteners. 
Referring now to FIG. 6, a particularly preferred embodiment has the center 
portion 40 and right and left arm portions 42, 44 formed by joining an 
upper member 46 to a lower member 48. Specifically, the center portion 40 
is formed by joining an upper center portion 50 with a lower center 
portion 52 of the respective upper and lower members 46, 48. This 
construction yields a hollow box section having significantly improved 
torsional and bending resistance than a simple planar or open section 
construction. The upper and lower members 46, 48 may be joined by any 
conventional method, including, but not limited to, welding or fastening 
at appropriate intervals with threaded fasteners or rivets. 
Similarly, the right arm portion 42 is formed by joining a right upper arm 
portion 54 which terminates at an upper first end 62 with a right lower 
arm portion 56 which terminates at a lower first end 64 of the respective 
upper and lower members 46, 48. The left arm portion 44 is formed by 
joining a left upper arm portion 58 which terminates at an upper second 
end 66 with a left lower arm portion 60 which terminates at a lower second 
end 68 of the respective upper and lower members 46, 48. In the preferred 
embodiment, the upper and lower first ends 62, 64 and the upper and lower 
second ends 66, 68 each provide attachment points to the right and left 
rails 12, 14 of the motor vehicle frame. 
Referring back now to FIGS. 4-5, the cross member 22 further includes right 
and left steering gear apertures 70, 72 disposed in the right and left arm 
portions 42, 44. The apertures provide adequate clearance for components 
of the rack and pinion steering gear assembly 36 to pass through and 
operate without interference. This permits locating the rack and pinion 
steering gear assembly 36 at the same position on the longitudinal axis of 
the motor vehicle as the cross member 22, which in turn provides a maximum 
free length of the right and left rails with a minimum front overhang. 
Referring again now to FIG. 6, the particularly preferred embodiment 
includes right and left inner steering gear apertures 74, 76 located on 
the right and left upper arm portions 54, 58, respectively, of the upper 
member 46. Similarly, right and left outer steering gear apertures 78, 80 
are located in the right and left lower arm portions 56, 60, respectively, 
of the lower member 52. The right inner steering gear aperture 74 is 
positioned to be axially aligned with the right outer steering gear 
aperture 78 when the upper and lower members 46, 52 are joined. The left 
inner steering gear aperture 76 is positioned to be axially aligned with 
the left outer steering gear aperture 80 when the upper and lower members 
46, 52 are joined. Together, the right inner and outer steering gear 
apertures 74, 78 and the left inner and outer steering gear apertures 76, 
80 permit locating the rack and pinion steering gear assembly 36 at the 
same position on the longitudinal axis of the motor vehicle as the cross 
member 22. 
Referring back now to FIGS. 4-5, the cross member 22 may also include right 
and left bridge members extending through respective steering gear 
apertures 70, 72. The bridge members 82, 84 enhance the structural 
properties of the cross member 22 after providing for the steering gear 
apertures 70, 72. 
Referring to FIG. 6, the bridge members 82, 84 are shown having an inverted 
U shape and being fitted in the particularly preferred embodiment. The 
right bridge member 82 has one end adapted to be attached to a portion of 
the right inner steering aperture 74 in the right upper arm portion 54. 
The right bridge member 82 extends through the arm to an opposite end 
which is adapted to be secured to the right outer steering gear aperture 
78 in the right lower arm portion 56. Similarly, the left bridge member 84 
has one end adapted to be attached to a portion of the left inner steering 
aperture 76 in the left upper arm portion 58. The left bridge member 84 
extends through the arm to an opposite end which is adapted to be secured 
to the right outer steering gear aperture 80 in the right lower arm 
portion 60. 
All of the components of the cross member 22 can be stamped or otherwise 
formed from materials capable of sustaining compressive and tensile loads. 
Such materials include, but are not limited to, steel, aluminum, and high 
strength synthetic polymeric materials such as high strength 
polycarbonate. 
When installed in the motor vehicle, the center portion 40 of the cross 
member 22 cradles and supports the rack and pinion steering gear 36. In 
this manner, the cross member serves the above stated purposes in addition 
providing superior ground clearance and protection for the rack and pinion 
steering gear assembly from objects such as rocks, logs, etc. which may 
protrude from the terrain over which the motor vehicle is driven. 
Other variations and modifications of the present invention will, no doubt, 
occur to those skilled in the art. For instance, those skilled in the art 
will appreciate, in view of this disclosure, that a cross member according 
to the present invention may be used on many variations of a suspension. 
For example, the cross member could be located immediately behind the 
driven axle while providing the benefits described above. The present 
invention has applicability to many different types of suspensions and 
drive axle arrangements used in industrial and automotive designs. It is 
the following claims, including all equivalents, which define the scope of 
the invention.