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COMPOSITE STEERING COLUMN
CROSS-REFERENCE TO RELATED
This application claims priority from United States Provisional Patent Application filed Nov. 9, 2001 and assigned application Ser. No. 60/345,053, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to steering columns, and in particular to a steering column housing which is easy to manufacture and assemble, is light weight, and is less costly to manufacture than prior designs.
2. Brief Description of the Related Art Traditionally, vehicle steering columns were formed from
heavy gauge metal tubular housings fixed to the firewall and dashboard of the vehicle. Articulated and telescoping steering columns became more massive as a direct result of additional metal tubing, universal joints, and more parts. By their very nature, these structures were designed to be rigid so the operator maintained positive operational control of the vehicle at all times. Today steering columns are made substantially the same way with complex structures and rigid heavy metal materials, resulting in too much additional weight and unforgiving structures in collisions.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a tilting and/or telescoping steering column for a vehicle having a substantially fewer parts and hence lower mass than prior designs. It is another object of the instant invention to provide a steering column housing formed from multiple components which are substantially less expensive to manufacture than the previous metal tubular housings. It is yet another object of the instant invention to provide a steering column housing assembly which is easier to manufacture and no longer requires the conventional hydraulic pressing of bearings into rigid tubular housings to journal the steering column shaft(s).
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is an oblique view of one embodiment of a composite steering column assembly embodying the instant invention;
FIG. 2 is an elevation left view of the assembly shown in FIG. 1;
FIG. 3 is an elevation right view of the assembly shown in FIG. 1;
FIG. 4 is a partial section view of the assembly shown in FIG. 3 taken along line IV—IV;
FIG. 5 is an oblique view of an inner face of one half of the lower composite steering column housing shown in FIG. 1; and
FIG. 6 is an oblique view of an inner face of one half of the upper portion of the composite steering column housing shown in FIG. 1.
DETAILED DESCRIPTION OF THE
For purposes of the following description, the terms 5 "upper," "lower," "left," "rear," "front," "vertical," "horizontal" and derivatives of such terms shall relate to the invention as oriented in FIG. 1. However, it is to be understood the invention may assume various alternative orientations, except where expressly specified to the con10 trary. It is also to be understood the specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Specific dimensions and other physical characteris15 tics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise.
Generally, a steering column housing assembly is provided formed from a plurality of components interconnected
20 together using conventional fastening methods for housing a tilting and/or telescoping steering column shaft assembly. In one form of the invention, the steering column housing assembly includes a lower housing member formed from two halves interconnected together. Pivotally coupled to the
25 lower housing assembly is an upper steering column assembly likewise formed from halves interconnected together. The upper and lower housing members are in turn interconnected by a positioning locking system to control the tilt position of the upper housing assembly to the lower housing
According to one form of the invention, a steering column assembly is provided comprising a lower steering column housing formed from at least a first and a second mating member adapted to be interconnected together to form a
35 longitudinal passage between an upper and a lower end, the longitudinal passage having at least one bearing seat formed therein. An upper steering column housing is formed from at least a first and a second mating member adapted to be interconnected to form another longitudinal passage
40 between an upper and a lower end, the lower end of the longitudinal passage within the upper steering column housing having an inside diameter greater than the inside diameter of the upper end with the longitudinal passage and having at least one bearing seat formed therein. The lower
45 end of said upper steering column housing is pivotally coupled to the upper end of the lower steering column housing such that the upper steering column housing pivots between a first and a second position relative to the lower steering column housing. The relative position of the upper
50 steering column housing is maintained by a positioning device interconnecting the upper steering column housing with the lower steering column housing. The steering column assembly defined above further includes bearing members which are retained within the bearing seats formed
55 within each of the lower and upper steering column housings. A lower and an upper steering column shafts are journaled within respective ones of the lower and upper steering column housings by the bearing member, and interconnected to each other by a universal joint. The first
60 and second mating members of each of the lower and upper steering column housing members are preferably formed from a moldable or castable material, and most preferably a polymeric material. In a preferred embodiment, the first and second mating members of the lower and upper steering
65 column housing members are injection molded using the polymeric material although other materials such as magnesium and other light weight casting materials may also be
used. Additionally, The positioning device may be selected from the group of devices including pneumatic, hydraulic, tooth and pawl, and magneto-rheological locking members.
A method for manufacturing the steering column assembly defined above from a polymeric material, includes the 5 steps of molding or casting a lower and an upper steering column housing from the moldable or casting material, and journaling a lower and an upper steering column shaft and fixing the lower and upper steering column shafts within a respective one of the lower and upper steering column 10 housings. More particularly, the method further comprises the steps of pivotally interconnecting the upper and lower steering column housings and the upper and lower steering column shafts together such that the upper steering column housing is permitted to pivot about a predetermined axis 15 relative to the lower steering column housing. The method further contemplates the step of molding each of the lower and upper steering column housings in at least two portions which are adapted to be interconnected together. It is preferred the lower and upper steering column housings are 20 injection molded from the polymeric material. The step of fixing the lower and upper steering column shafts within respective ones of the lower and upper steering column housings includes positioning the lower and upper steering column shafts within at least one of the at least two portions 25 prior to being interconnected. Furthermore bearing seats are formed within each of the at least two portions of the lower and upper steering column housings for receiving a respective bearing member therein during the assembly. Attachment bosses are also molded during the molding process 30 such that each of the at least two members of the upper and lower steering column housings can be interconnected by fasteners. The method further comprises the step of pivotally coupling the upper and lower steering column housing together with at least one of the upper and lower steering 35 column housing having at least one ball coupler, and the other of the upper and lower steering column housings having at least one socket for receiving the at least one ball coupler. Lastly, the method includes interconnecting the lower and upper steering column housings together with a 40 positioning device, the positioning device including one of a pneumatic cylinder, a hydraulic cylinder, a tooth and pawl locking mechanism, and a magneto-rheological locking mechanism.
According to another form of the invention, a tiltable, 45 polymeric steering-column housing for a motor vehicle is provided, comprising a lower member formed from at least two mold or cast pieces and configured to mate with each other to define a longitudinal passage interconnecting an upper end to a lower end of the lower member. The longi- 50 tudinal passage of the lower member includes at least one bearing or bushing seat formed therein. An upper member is formed from at least two mold or cast pieces and configured to mate with each other to define another longitudinal passage interconnecting an upper end to a lower end of the 55 upper member. Like in the lower member, the longitudinal passage of the upper member includes at least one bearing or bushing seat formed therein. The lower end of the upper member is pivotally interconnected to the upper end of the lower member such that the upper member pivots between 60 a first and a second position relative to the lower member. A journal bearing or bushing is disposed within each of the seats formed in each of the lower and upper members. A lower and an upper steering column shaft are disposed within respective ones of the longitudinal passages defined 65 in each of the lower and upper members, and journaled within each longitudinal passage. A universal coupler or
joint interconnects the lower and upper steering column shafts to substantially complete the column assembly.
Refer to FIGS. 1-3 which generally illustrate the basic components of the steering column assembly 10 as viewed from the exterior. Essentially, but not limited there to, steering column assembly 10 includes an upper steering column shaft 12 interconnected to a lower steering column shaft 14 by a universal joint (not shown) with both shafts 12 and 14 journaled within a housing assembly 16. In general practice, the free end of the upper steering column shaft 12 is configured to receive a steering wheel (not shown) while the free end of lower steering column shaft 14 is interconnected to another shaft or steering gear box in a well known and conventional manner. The steering column assembly 10 in this embodiment is held in position by fasteners extending through coupling points in the lower end of the housing assembly 16. In addition, steering column assembly 10 may be attached to a frame work or structure of the instrument panel assembly in such a manner so as to stabilize the upper portions of the lower steering column housing in position.
The steering column assembly 10 includes a lower housing assembly 18 having a lower end configured to be fixed to the vehicle and an upper and an opposite end which is adapted to be coupled along Axis A to an upper housing assembly 20. The connection between the upper and lower housing assemblies 18, 20, respectively, is such that the upper housing assembly 20 pivots about a line defined by Axis A relative to the lower housing assembly 18. Pivotal movement of the upper housing assembly 20 relative to the lower housing assembly 18 is controlled in substantial part by a position locking mechanism 22 interconnected at opposite ends to the lower housing assembly 18 and the upper housing assembly 20. A release mechanism 24 disposed at an upper end of the position locking mechanism 22 is manipulated by the operator to engage and disengage the locking mechanism to permit pivotal movement of the upper housing assembly 20 relative to the lower housing assembly 18.
Although the embodiment illustrated in FIGS. 1-3 is that of a tilt steering column assembly 10, the instant invention is equally applicable to steering column assemblies which are fixed or have a telescoping characteristic, as well as telescoping and tilting characteristics. For example, the reader is referred to corresponding U.S. Pat. No. 5,899,497 for an example of a steering column having a particular ball and socket coupling to make the pivotal connection and to U.S. Pat. No. 5,267,480 for an example of a telescoping steering column shaft assembly. Moreover, locking mechanism 22 may include any one of a variety of mechanisms, including, but not limited to, hydraulic cylinder systems, air cylinder systems, magneto-rheologic locking systems, as well as the more conventional tooth and pawl locking engagement members. However, in a preferred embodiment, gas and magneto-rheologic locking devices have been found to produce the most versatility in tilt/telescope positioning.
Referring to FIGS. 1, 2, and 4, the lower housing assembly 18 is contemplated to be formed from two or more mold or casting halves. As best illustrated in FIG. 2, the line of bisection is illustrated by the line B which marks the interface between the right half 30 of the lower housing assembly 18 and the left half 32 of the lower housing assembly 18. In FIG. 2, the assembled lower housing assembly 18 includes a tubular longitudinal passage 33 through which the lower steering column shaft 14 extends. The two halves 30, 32 cooperate and define a flange 35 at the lower end of the housing assembly 16 for bolting the lower housing assembly 18 to the vehicle. At the opposite end of
the lower housing assembly 18, one half of a bracket member 36 is formed on each component for reasons which will be readily apparent below. Moreover, each half 30, 32 of the lower housing assembly 18 further includes an extending flange 37 which cooperates to form a yoke 38 for 5 affecting the pivotal coupling with the upper housing assembly 20. A hemispherical coupler 39 is illustrated which may extend from the inner surface of the flange 37 to form a ball-type coupling between the upper housing assembly 20 and the lower housing assembly 18 similar to that disclosed 10 in U.S. Pat. No. 5,899,497 and assigned to Douglas Autotech Corporation. Moreover, each is coupled to the other along shared mating surfaces and held together by bolts or other fasteners passing through each half at predetermined boss locations such as identified by the letter F. This type of 15 construction of the lower housing assembly 18 permits each half 30, 32 to be mold or cast, preferably injection molded from a high strength polymeric material such as glass-filled nylon or similarly strong polymeric material. In a preferred embodiment, the components are formed by injection mold- 20 ing using Verton RF-700-12 EM HS UV BK9-001 (60% Long Glass filled nylon). But just about any moldable material could also be used, depending upon the desired strength requirements. Die casting of the components from Magnesium, Aluminum, and other light weight metals have 25 also been considered. The only molding issues encountered are the formation of weld lines (areas where the glass fibers don't fully mesh such as occurs around holes), and warpage of the ears on the lower housing. By creating the housing from injection molded polymeric materials, the overall 30 structure is substantially lighter in weight than conventional steel structures. There is about a 25% weight reduction vs. a steel equivalent. The bolts or other fasteners extending between the two housing halves 30, 32 at the fixed locations F provide a rigid tubular support structure for the steering 35 column assembly 10.
A similar construction method is utilized to form the two halves 40, 42 of upper housing assembly 20. As shown in FIGS. 1, 3, and 6, the upper housing assembly 20 includes a right portion 40, and a left portion 42 interconnected 40 similar to steering column assembly 10. When combined together, the two halves 40, 42, define a longitudinal passage
47 which is configured at two locations to form bearing seats such as 49 for mounting bearings 44 and 50 (See FIG. 4) at spaced locations to journal the upper steering column shaft 45 12. On the exterior of the upper housing assembly 20, the two halves 40, 42 combine to form a bracket member 46, briefly mentioned earlier, to support one end of the locking mechanism 22. The two halves 40, 42, are coupled along matching faces using appropriate fasteners such as the bolts 50 mentioned earlier.
Referring to FIGS. 1 and 6, the upper housing assembly 20 is generally cylindrical, having an enlarged bell portion
48 which includes opposing and aligned recesses 51 for receiving the hemispherical couplers 39 described earlier 55 extending from the inner surfaces of the flanges 37 forming the yoke 38. The interaction of the hemispherical couplers 39 with the recesses 51 in the bell portion 48 serve to define the pivot Axis A between the two members and about the universal joint 52 best shown in FIG. 4 interconnecting an 60 upper end of shaft 14 with the lower end of shaft 12. Likewise, as with the lower housing assembly 18, the bracket member 46 defined proximate one end of the upper housing assembly 20 is formed by downwardly extending flange 54. The flanges 54 extending from each half 40, 42 of 65 the upper housing assembly 20, cooperate to produce a yoke-like structure, for supporting one end of the position
locking mechanism 22, as well as the release mechanism 24, The coupling between the position locking mechanism 22, release mechanism 24, and the bracket member 46, may be affected in a number of ways using a variety of fasteners, although it is contemplated to use the hemispherical couplers 56 similar to that defined on the flanges 37 with conventional screws or bolts passing concentrically through each of the two hemispherical couplers 56 to provide the proper load on the coupling, as well as to fasten the two housing halves 40, 42 together at that juncture. Likewise, other bosses F may be defined in each half 40,42 to receive other fasteners there through such as 58, to rigidly interconnect the two halves 40, 42, to form the upper housing assembly 20.
As mentioned above, it is contemplated in one aspect of the invention the two halves 40, 42 of the upper housing assembly 20 be formed from a polymeric material using injection molding or related techniques. In this manner, a substantial weight reduction can be achieved by using the polymeric or light weight metal materials, which can be structured to provide substantial rigidity and support to the upper steering column shaft 12. Moreover, the two halves 40, 42 provide assembling advantages over the prior art by providing direct access to the longitudinal passage 47 where bearings 44 and 50 can be inserted before being enclosed by the opposite half of the upper housing assembly 20.
Modifications of the invention described above will occur to those skilled in the art and to those who make or use the invention. For example, it is contemplated that fixed steering column housings may be formed from a polymeric material for use in harsh environments such as salt water. The polymeric material itself may be self lubricating so the steering column shafts rotate easily. Likewise, telescoping steering column designs may also be built using the polymeric material to form a shuttle or slide within either the upper or lower steering column housings. Again, the polymeric materials could be selected to provide the desired characteristics. Therefore, it is understood that the embodiments shown in these drawings and described herein are merely for illustrative purposes and not intended to limit the scope of the invention, which is defined by any claims in a subsequent or related application and interpreted according to the principals of patent law, including the doctrine of equivalence.
The invention claimed is:
1. A steering column assembly, comprising in combination:
a lower steering column housing formed from at least a first and a second mating member interconnected together transversely relative to a longitudinal passage extending between an upper and a lower end of said lower steering column housing, said longitudinal passage having at least one bearing seat formed therein;
an upper steering column housing formed from at least a first and a second mating member interconnected together transversely relative to form a longitudinal passage extending between an upper and a lower end of said upper steering column housing, said lower end of said longitudinal passage within said upper steering column housing having an inside diameter greater than an inside diameter of said upper end with said longitudinal passage having at least one bearing seat formed therein, said lower end of said upper steering column housing pivotally coupled to said upper end of said lower steering column housing such that said upper