INTERMEDIATE SHAFT ASSEMBLY FOR STEERING COLUMNS

Abstract: A steering column assembly (20) is provided comprising an outer isolator (34) closed at one end (40) and open at an opposite end (41); at least one tubular resilient member (50) concentrically disposed within and adhered to an inner wall (38) of the outer isolator tube (34); and an inner isolator tube member (60) having one end (64) extending from the open end (41) of the outer isolator tube (34). A telescoping shaft insert assembly (70) is provided having a first end (80) concentrically received within an inner wall (68) of the inner isolator tube (60) and with an opposite end (90) of the telescoping shaft assembly (70) from the open end (41) of the outer isolator tube (34). The tubular resilient member (50) disposed between the outer and inner isolator tubes (34, 60) is preferably made from a polymeric material and absorbs or dampens transient noise and vibration produced by the road and sensed in the steering wheel (24).

Description: INTERMEDIATE SHAFT ASSEMBLY FOR STEERING COLUMNS BACKGROUND OF THE INVENTION Field of the Invention This invention relates generally to steering column assemblies and particularly to an intermediate shaft for a steering column which offers reduced backlash and vibration and improved lateral stability than prior designs Discussion of the Related Art Steering wheels of automobile and other vehicles are, in most cases, connected by one or more senally arranged shafts from the steering gear box to the steering wheel of the vehicle In the early designs, a single solid shaft was connected at one end to the steering gear and at the other end to the steering wheel Later designs incorporated one or more universal joints for routing the shaft from the steering wheel to the steering gear It was found that solid steering column shafts presented a significant danger to drivers In later designs it was common to connect the steering wheel to the steering gear by a pair of tubular, concentncally positioned members which could telescope relative to one another, but were fixed rotationally The tubular members had interconnecting end portions to permit rotation or transfer of torque from the steering wheel to the steering gear However, these designs present substantially the same danger as pπor designs because the telescoping distance was short in comparison to the shaft assembly Moreover, as in the previous designs, the shaft transmitted vibrations produced by the road and engine to the steering wheel, producing numbness and fatigue in the operator's hands Additionally, the interconnection of the tubular members created substantial backlash or nonresponsiveness in the steering wheel due to the gap between the concentncally arranged tubes United States patent 5,243,874 illustrates a more recent structure for use in steering columns A pair of telescoping members are provided having a preselected cross-sectional configuration that facilitates the insertion of one tubular member in the other The surface configuration of the interconnecting portions is complementary to prevent rotation of one with respect to the other The outer surface of the internal member is spaced from the inner surface of the outer member forming an annulus which receives a thermosetting resinous material injected therein at an elevated temperature The thermosetting resin shrinks upon cooling to form a sleeve having a cross-sectional area less than the annulus to permit telescopic movement of the inner tube The disadvantage of the construction is the substantial backlash which exists as a result of the shrinkage of the resin Another problem is the need to maintain the concentnc onentation of the inner tube with respect to the outer tube during the injection step so the inner tube does not become eccentric with the rotational axis SUMMARY OF THE INVENTION The intermediate shaft assembly of the steering column in one embodiment of the invention includes an outer tube having an outer wall and an inner wall, and an inner tube having a first end concentncally disposed within the inner wall of the outer tube, the inner tube having an outer wall and an inner wall At least one, and preferably several resilient tubular members are disposed within the outer tube and receive the inner tube therein to position the inner tube within the outer tube A shaft insert assembly, having a first end, is concentrically disposed within the inner wall of the mner tube and has a second end which extends from the second end of the inner tube The intermediate shaft assembly is mounted in the steering column by universal joints, a first universal joint being attached to the first end of the outer tube, and a second universal joint being attached to the second end of the shaft assembly A mechanical bond attaches the outer tube and the inner tube to the resihent tube in substantial fixed relationship The substantial fixed relationship of the two tubes is aided by the feet that the outside diameter of the resilient tube is slightly greater than the inside diameter of the outer tube, and the inside diameter of the resilient tube is slightly less than the outside diameter of the inner tube, such that when placed concentrically within each other, fit in close relationship The mechanical bond between the respective tube members substantially locks them in place In another form of the invention, the outer tube includes a collapsible section intermediate the first and second ends The collapsible section defines a predetermined area of weakness or failure pomt m the outer tube such that upon an impact, the outer tube collapses or folds in the collapsible section and substantially eliminates the transfer of forces longitudinally along the intermediate shaft In yet another form of the mvention, the concentrically arranged tubes interconnected by the resihent tubular members have a pm extending transversely therethrough for the purposes of providing a redundant coupling m the event the adhesion with either of the tubular members fails The intermediate shaft embodying the instant invention offers several advantages over the prior designs, including substantially reduced backlash about the longitudinal axis of the mtermediate shaft as well as unproved lateral stability of the inner tubular member Moreover, the inner tube is concentric with the outer tube and the chances of eccentricity are significantly reduced The shaft insert assembly is dimensioned such that a reduction in the overall length of the mtermediate shaft of approximately 40 percent is available to absorb impacts The crumple zone in the outer tube further reduces the risk of injury from impact forces transferred along the axis of the intermediate shaft The advantages and improvements over the prior designs set forth above will be better understood from a reading of the detailed descnption when taken in combination with the attached drawing figures, wherein BRIEF DESCRIPTION OF THE DRAWING FIGURES Fig 1 is a schematic diagram illustrating one application of the mtermediate shaft assembly embodying the mvention, Fig 2 is an isometric diagram of one form of the mvention, Fig 3 is a longitudinal cross-section of the invention shown m Fig 2 taken along line II-II, Fig 4 is a transverse cross-section of the mvention taken along line IV-IV shown m Fig 3, Fig 5 is a transverse cross-section of the mvention taken along lme V-V shown m Fig 3, Fig 6 is an enlarged, fragmentary cross-section of a portion of the mvention, Fig 7 is a longitudinal cross-section of the mvention shown in Fig 3 in a collapsed configuration, Fig 8 is an lsometnc view of an alternate embodiment of the mvention, Fig 9 is a cross-section of the mvention shown m Fig 8 and taken along lme IX-IX, and Fig 10 is a longitudinal cross-section of the invention shown m Fig 9 when in a collapsed configuration DETAILED DESCRIPTION OF DIFFERENT EMBODIMENTS The following descnption will descnbe an application of the mvention for use in automobiles However, the invention has applications elsewhere, including rotary actuators or drive assemblies Accordingly, Fig 1 illustrates a shaft assembly 20 which may form an mtermediate component in a steering column 22, which includes a steering wheel 24 at one end and a steering gear box 28 at an opposite end The steering gear box 28 m turn is interconnected to the wheels 30 of the vehicle 32 One embodiment of the shaft assembly 20, shown m greater detail in Figs 2-6, mcludes an outer isolator tubular member 34 having a cylindrical outer wall 36 and a cylindrical inner wall 38 The length of the outer member 34 may range between one and six feet, depending upon the application The outside diameter of wall 36 may also vary, ranging from 1 5 mches to more than 4 or 5 mches The mside diameter of wall 38 may also vary, but m a preferred embodiment is about 0 25 inch to about 0 75 mch less than the outside diameter, except m certain circumstances as will be described more fully below The outer member 34 is preferably made from a ngid mateπal such as steel, although aluminum alloys and bronze may also be suitable It is also contemplated that composite materials may also be used, including certain wrapped laminates and/or carbon composites Member 34 is preferably a nght circular cylinder open at each end 40 and 41 Attached to the first end 40 of member 34, and at least partially received within the cylmdncal inner wall 38, is a coupler 42 configured to interconnect end 40 of the shaft assembly 20 and another portion of the steering column 22 In the preferred embodiment, the coupler 42 is a universal jomt having a yoke 44 ngidly coupled to a base 46 which is welded or otherwise rigidly attached to the inner wall 38 and end 40 of outer member 34 The attachment of the coupler or universal joint 42 to end 40 of the outer member is preferably a permanent type of attachment such that one half of the coupler 42 becomes an integral part of outer member 34 and closes end 40 Disposed within cylmdncal member 34 and concentric with the longitudinal axis LA of the outer member 34 is at least one, preferably at least two, and most preferably four to five cylmdncal tubular resihent members 50, each having an outer wall 52, an inner wall 54, and having a combmed length less than the overall mside length of the outer member 34 In the embodiment shown, a plurality of resilient members or isolator elements 50 are provided, each made from a polymenc matenal such as rubber, PVC, polyurethane, or the like The hardness of each of the resilient members 50 may range between a durometer of 40 and 95, depending upon the particular characteristics to be achieved Each of the isolator elements 50 has an outside diameter at least equal to and preferably slightly greater than the mside diameter of inner wall 38 such that each of the isolator elements are firmly held withm the outer member 34 In the preferred embodiment, the isolator elements 50 are arranged within the outer tubular member 34 m spaced tandem arrangement, each concentnc about the longitudinal axis LA of the outer member 34 It is further contemplated that substantially no gap will exist between the outer wall 52 of the resihent isolator member 50 and the inner wall 38 of the outer member 34 Most preferably, each of the resihent isolator members 50 is slightly compressed so they are elongated longitudinally m order to be received within outer member 34 The space 56 between adjacent resilient isolator members 50 should be at least sufficient to permit the necessary longitudinal elongation The space between adjacent isolator elements 50 may be a fraction of an mch, preferably at least about one-eighth of an inch and as large as three-quarters of an mch, most preferably about three-eighths of an mch Disposed within and extendmg through substantially all of the isolator elements 50 and concentnc with the longitudinal axis LA of the outer member 34 and elements 50 is a cylmdncal mner tubular member or inner isolator tube 60 havmg a first end 62 adjacent base 46 and a second end 64 extendmg out from the second end 41 of the outer tubular member 34 and beyond the isolator elements 50 The inner member or isolator inner tube 60 is preferably m the form of a nght circular cylinder and includes a cylmdncal outer wall 66 and a cylmdncal inner wall 68 The diameter of cylmdncal wall 66 is substantially equal and preferably slightly greater than the mside diameter of each isolator element 50 such that the inner member 60 is securely retained within the outer member 34 by the resilient isolator elements 50 The inner member 60 is preferably made from the same type of matenal as the outer member 34, including metal, polymers, and alloys or composites used to form the outer member 34 The nature of the matenal forming the resilient members 50, combined with the combmed surface area contacting the inner member 60 and the outer member 34 provides a high friction, substantially rigid coupling between the three components Each of the resilient members 50 may be slid onto the outside diameter of inner member 60 and moved to the appropnate location In such an embodiment, it is contemplated that the mside diameter of each resilient member 50 is slightly less than the outside diameter of the inner member 60 so that the resilient members 50 do not slide freely thereon To ensure that the plurality of resilient elements securely retain inner member 60 with respect to the outer member 34, an adhesive or lubncant may be applied to the mside wall 38 of the outer member 34 and the outside wall 52 of each of the resilient members 50 and to the mside wall 54 of the resilient members 50 and the outside wall 66 of the inner member 60 As mentioned above, the adhesive acts as a lubncant in the assembly of the respective elements The adhesive (not shown) may be any one of a number including those selected from the groups of thermoplastics, thermoset components, epoxies, acrylics and polyesters and may cure to a hard or glassy phase, but preferably should remam somewhat resihent The adhesive may also contam a lubncant such as an ultra high molecular weight polyethylene, graphite, sihcone, or other matenal which serves to lower the coefficient of friction If a lubricant alone is used, it may be applied to the outer diameter of the resihent members to aid m assembly Once the isolator is assembled, the lubricant dissipates or evaporates, creatmg a very high static friction condition or mechanical bond The lubncants may be any of a number including greases and oils and the like compnsed of vanous compound bases such as petroleum or synthetic-based lubncants In a prefened embodiment, the lubricant should be compatible with the matenal comprising the resilient members, and have a substantially high vapor pressure so that the lubncant may evaporate rather rapidly or be absorbed by the resihent members once the lubncant has served its lubncatmg purpose The evaporation or absorption of the lubncant creates a high friction contact between the resilient member and the outer member It is anticipated that a lubncant havmg a low surface tension would be prefened such that the lubncant could evaporate or be dnven from the assembly once completed What is desired is to create a high coefficient of friction between the members 34, 60 and the resilient members 50 once assembly is complete Moreover, the type of adhesive or lubncant selected should be compatible and appropnate for bonding or adhering structures of different or dissimilar composition For the purposes of this discussion and the drawing figures, the mechanical bond of the outer member and the inner member to the resilient elements has not been shown for the purposes of maintaining clanty to the drawing figures In an alternative embodiment, each of the resilient members 50 may be formed m-situ around the inner member 60 For example, each resilient member 50 may be molded about the mner member 60 Acceptable molding techniques mclude injection molding, compression molding, pour molding or casting Extrusion may also be possible provided the elastomenc or polymenc matenal is sufficiently viscous By forming the resihent members 50 on the inner member 60, a good strong bond can be achieved Better adhesion can be attained by first treatmg or pramng the outer diameter of the inner member 60 pnor to forming of the resilient members Received within the inner member 60 through end 64 and concentnc with the longitudinal axis of the outer member 34 is an msert assembly 70 which couples the opposite end of the shaft assembly 20 to the other components of the steering column 22 The msert assembly 70 mcludes an msert 72, a shaft 74, and a second universal jomt or coupler 76 The msert 72 is preferably made from high strength matenals such as metals and certain polymers or composite structures and has an outer wall 78 which is substantially cylmdncal m shape from a first end 80 to an opposite end 82 The outside diameter of wall 78 from end 80 to a shoulder 84 proximate end 82 is slightly less or generally equal to the mside diameter of cylmdncal inner wall 68 such that the portion of msert 72 from end 80 up to the shoulder 84 is received by inner cavity 68 of the inner member 60 The outside diameter of wall 78 between shoulder 84 and end 82 is substantially equal to the outside diameter of cylmdncal outer wall 66 of the inner member 60 Shoulder 84 is mclmedto define a valley or space between the end 64 of the isolator inner tube and the msert 72 In one embodiment, insert 72 is ngidly attached to inner member 60 by welding shoulder 84 to end 64 In an alternative arrangement, shoulder 84 may also mclude one or more bosses or keys (not shown) spaced radially about on wall 78 which correspond to recesses or slots (also not shown) formed m end 64 of tube 60 which serve to rotationally lock msert with respect to inner member 60 Other mechanical devices such as threaded couplmg, screws, pms and cams may be used to interconnect the msert 72 longitudinally with inner member 60 Additionally, a suitable adhesive may be used to bond the outer wall 78 between end 80 and 84 with the mside wall 68 of the inner isolator tube 60 Insert 72 mcludes a tubular passage 86 to receive shaft 74 therein In a prefened embodiment, the inner tubular passage 86 is not cylmdncal, but rather polygonal and is concentric with the longitudinal axis of the outer member 34 For example, passage 86 may be square, pentagonal, hexagonal, septagonal, or octagonal in cross-section Most preferably, passage 86 is hexagonal and extends from end 80 and out through end 82 of the msert The dimensions of the passage 86 are generally the same or slightly larger than the outside diameter of shaft 74 received therein As shown in Figs 3 and 5, shaft 74 is polygonal, and most preferably hexagonal, and mcludes a first end 88 which is received through end 82 of the msert and extends out beyond end 80 A second end 90 of the shaft 74 is attached to the coupler 76, and most preferably a yoke 92 of a universal jomt In a similar fashion, shaft 84 is preferably made from a high strength matenal, preferably steel Hexagonal shaft 74 is free to telescope m and out of the tubular passage 86 with respect to msert 72 to permit longrtudmal flexibility and adjustability to mtermediate shaft assembly 20 The amount of adjustment or telescopic translation is preferably the entire length of shaft 74 and most preferably the distance along the inner wall 38 from base 46 to a pomt just inside end 82 of insert 72, or the maximum distance the design permits The primary purpose of the telescopic action is to absorb and compress upon impact to lessen the chance of injury to the operator Although longitudinal flexibility is provided, rotational motion with respect to msert 72 and inner and outer tubes 60 and 34 is stnctly minimized by the flat surfaces on shaft 74 engaging correspondmg flat surfaces on the wall of passage 86 In a preferred embodiment, tolerances between the shaft 74 and passage 86 are about 002 mch to stnctly minimize backlash Proximate end 40 of the outer isolator tube 34 and extendmg transversely through the walls 36 and 38 of the outer member 34 and the walls 66, 68 of the inner member 60 are a series of holes 94A and 94B, respectively The location of the holes on each of the respective elements is such that they are aligned to permit passage of a safety backup pm 95 entirely through the outer isolator tube 34 The safety backup pm mcludes a shaft 96, one end 98 of which terminates m a head 100 having a tapered surface 102 The opposite end 104 extendmg through the opposite side of the outer isolator tube 34 is configured to receive a self-centeπng alignment washer 106 havmg a tapered surface 108 The alignment washer is retained on shaft 96 by mechanical means, including cotter pms, nveting and the like The tapered surfaces 102 and 108 face inwardly to engage holes 94A within the outer isolator tube and center the backup pm within the holes to prevent chafing or abrasion of the pm shaft 96 against the vanous respective tubular elements Abrasion of the shaft is also reduced by producmg holes 94A and 94B with a larger diameter than that of shaft 96 In operation, the shaft assembly 20 is assembled as shown m the drawing figures and attached to the steermg column at both ends by the universal jomts 42 and 76 The telescopmg nature of shaft 74 within msert 72 and inner isolator tube 60 permits flexibility in adaptmg the shaft assembly 20 to vanous steermg column anangements In a prefened embodiment, the shaft assembly is designed such that the shaft is substantially m the extended configuration for reasons which will become apparent below As the steermg wheel is turned or rotated, these rotational forces are transfened through the steermg column and universal jomt 76 to shaft 74 The hexagonal or polygonal nature of shaft 74 within the inner tubular wall 86 of the msert 72 transfers the rotational force to mner member 60 and across the resilient isolator elements 50 to the outer member 34 These rotational forces are then transferred from the outer member 34 to the universal jomt 42 coupled at the end 40 to the opposite end of the steermg column Road and engine vibration and other transient forces migrating up the steermg column are substantially dampened and removed from the steermg column by the resihent isolator members 50 disposed between the outer member 34 and the inner member 60 As a result, less vibration is sensed by the operator at the steermg wheel causmg less fatigue than m pnor devices The handling charactenstics of the vehicle can be adjusted by changing the hardness of the isolator elements 50 For example, a very responsive shaft is achieved by usmg a high durometer hardness polymenc matenal for the isolator elements 50 The higher durometer hardness matenals have a higher modulus of elasticity and are more efficient the transfer of rotational forces, producing a quick transfer response from the steermg wheel to the steermg gear box Alternatively, a softer response can be obtamed by usmg a lower durometer hardness polymeric material with a relatively lower modulus of elasticity An important aspect of the mvention is the safety backup pm 95 extendmg through the respective tubular elements In the event that the resilient isolator elements 50 separate from one or both of the members 34 and 60, control of the vehicle is not lost smce any rotational force transfened from the shaft 74 to the member 60 will be transfened to the outer member 34 by the shaft 96 of the safety backup pm 95 The gap between the safety backup pm 95 and the holes 94A-94B is sufficient to accommodate any rotational flex between the inner member and the outer member Another important aspect of the mvention is the reduced nsk of injury to the operator as a result of transfer of impact forces longitudinally along the steermg column shaft to the steermg wheel In a crash situation, the mtermediate shaft assembly 20 collapses and absorbs the crash energy through the telescopic nature of the hexagonal shaft 74 m the msert 72 When installed, the shaft 74 is substantially extended with respect to the msert 72, permitting substantial translation of the shaft within the outer tube 34 Additional safety features are shown m an alternate embodiment of the mvention descnbed below In the alternate embodiment of the mvention, shown m Figures 9 and 10, the mtermediate shaft assembly 220 mcludes an outer tubular member 234 preferably m the form of a right circular cylmder and havmg an outer wall 236 and an inner wall 238 The member 234 is open at both aids, identified as first end 240 and second and opposite end 241, and may have a length ranging from several mches to more than svx. feet, depending upon the particular application The cylmder 234 proximate end 240 is crenulated, identified by reference numeral 210, havmg annular ridges 212 and valleys 214 The bellows or crenulations 210 are formed preferably by hydroformmg, a process wherem fluid under pressure is used to deform and conform the tube to the shape of a mold In the formmg process, the thickness of the cylmder walls is reduced m the area of deformation, producmg a prefened zone of weakness along the cylmder The zone of weakness produces a failure zone where the cylmder 234 will fracture to absorb energies produced by a collision or crash As m the previous embodiment, member 234 is made from a substantially rigid, high strength matenal such as steel, although other matenals may be found suitable for use End 240 of the cylmder 234 is closed by the base 246 of a universal jomt or coupler 242 which has been welded thereto, while the opposite end 241 is open to receive the various components descnbed below Within tubular member 234 and ananged concentncally immediately adjacent inner wall 238 is at least one, and preferably more than two, resihent and polymeric members 250 Each member 250 is preferably a nght circular cylmder havmg an outer wall 252 m intimate contact with the inner wall 238 of the tubular member 234 The resilient members 250 also mclude a concentric and longitudinal passage or inner wall 252 In a preferred embodiment, the resilient members 250 are located within tubular member 234 at a point mtermediate crenulations 210 and end 241 In the case of multiple resihent members 250 within the tubular member 234, it is preferred that a space exists between adjacent resilient members to permit elongation of the resilient members, as will become more apparent below As m the previous embodiment, the resilient members 250 are preferably made from a polymeric matenal such as rubber, PVC, polyurethane, or the like The hardness of the resihent members may have a wide range as earlier specified With respect to the tolerance between the outside diameter of the resilient members 250 and the inner wall 238 of the tubular member 234, it is contemplated that substantially no gap will exist as the outside diameter of the resilient member is slightly greater than the mside diameter of the wall 238 pnor to positioning the resilient members 250 within the tubular member 234 Each of the resihent members 250 is slightly radially compressed m order to place the resihent members 250 in the outer member 234 As a result of the compression, each of the resilient members 250 becomes elongated longitudinally When m place, the tendency of the resilient members 250 to assume their onginal shape results m intimate contact of the outer wall 252 with the inner wall 238 In a preferred embodiment, an adhesive or lubricant, havmg lubrication characteristics m its viscous state, is used to assist m the location of each of the resilient members within the tubular member 234 After sufficient time has passed, the mechanical bond is created and rigidly secures the resihent member 250 in place It is contemplated that the inner wall of tubular member 234, and/or the outer wall 252 of resihent member 250 may need to be pretreated or pnmed in order to complete the bond between die respective elements Each of the resihent members 250 is concentncally received along the longitudinal passage 254 of an inner tubular member or isolator tube 260 havmg a first end 262 located proximate and just short of the crenulations 210 and a second end 264 extendmg out from the end 241 of tubular member 234 and beyond the end of the last resilient member 250 contained by tubular member 234 The inner tubular member 260 is preferably m the form of a right circular cylmder and has a cylmdncal outer surface 266 and a concentric cylmdncal inner passage 268 The diameter of the cylmdncal outer surface 266 is substantially equal to and may be slightly greater than the mside diameter of the longitudinal passage 254 If the diameters are different, the inner member 260 produces further compression and longitudinal elongation of each of the resilient members 250 such that a much greater surface area, both along the inner wall 254 and the outer wall 252, respectively, of the resihent members 250, are m contact with the outer and inner tubular members 234 and 260 As a result, the inner member 260 is securely retained and held m place by the resihent members 250 The mechanical bond, mentioned above, may also be used to substantially fix and make more ngid the coupling between the inner tubular member 260 and the inner passage of the resilient members 250 The adhesive or lubricant, preferably applied to the inner tubular passage 254 and the outside surface 266, serves mitially as a lubncant to assist in the msertion of the inner member 260 into the inner passage 254 of each of the resilient members 250 Thereafter, the mechanical bond is created and securely locates the inner member 260 therein In particular, the preferred adhesive or lubricants may be one selected from the group identified above However, m a prefened embodiment, the resilient members 250 are molded around the inner member 260 m the manner described above Substantially received within the cylmdncal inner passage 268 from end 264 is a generally cylmdncal msert 272 havmg a first end 280 within the inner member 260 and a second opposite end 282 extendmg from inner member 260 The msert 272 is only partially received within inner member 260, the depth controlled by a shoulder 284 formed in the outer cylmdncal surface 278 Shoulder 284 is located proximate end 282 and defines a transition from a diameter which is received within the inner cylmdncal passage 268 The outside diameter of the cylmdncal wall 278 between shoulder 284 and the second end 282 is substantially equal to the outside diameter of the wall 266 The msert 272 is preferably rigidly fastened to the end 264 of the inner tubular member 260 by weldmg the shoulder 284 to the second end 264 The weldmg of the two components prevents rotational and translative motion of the msert with respect to the inner tubular member 260 It should be noted that msert 272, m particular the portion between end 280 and shoulder 284, is received wrthm and extends along only a fraction of the overall length of the inner tubular member 260 The msert 272 also mcludes a concentnc longitudinal inner passage 286 which is configured to receive a shaft 274 havmg a first end extendmg through the msert 272 and at least partially into the inner cylmdncal passage 268 of the inner member 260 A second and opposite end of the shaft 274 extends out beyond the end 282 of the msert, where it is securely attached to a coupler or U-joiπt member 276 In a prefened embodiment, passage 286 of the msert 272 is not cylmdncal, but rather has a polygonal cross-section substantially conesponding to the cross- section of the shaft 274 Most preferably, shaft 274 has a hexagonal cross-section of a dimension just slightly less than that of the longitudmal passage 286 and sufficient to permit longitudmal translation of the shaft 274 within the passage 286 The tolerances between the passage 286 and the shaft 274 are on the order of 002 mch to substantially reduce any backlash associated with the dimensional differences between the two components yet sufficient to permit translation of the shaft with respect to the msert The polygonal cross-section of the shaft and the longitudmal passage provides a secure rotational coupling between the shaft 274 and the msert 272 and substantially reduces the risk of slippage The length of shaft 274 may vary between substantially equal to the length of outer tubular member 234 or a fraction thereof In a prefened embodiment, the length of shaft 274 is substantially equal to the distance between end 241 of tubular member 234 and the crenulation area 210 With the end of the shaft 274 received or extendmg through msert 272, a travel distance about equal to the length of the outer tubular member 234 is provided if the shaft encounters compressive forces The substantially rigid placement of the inner tube of the member 260 with respect to the outer tube of the member 234 and the secure attachment of the msert 272 within the inner tube of the member 260, results in shaft 274 having substantial lateral ngidity and stability Extendmg transversely entirely through at least the outer tubular member 234 and the inner tubular member 260 is a pm 295 In a prefened embodiment, the pm extends through the concentnc members at a pomt near the crenulations 210 and the first end 262 of the inner tubular member That is to say that the pm should be located at a pomt as close to the crenulations 210 as possible m order to permit the greatest travel distance for the shaft 274 The pm 295 extends through holes 294A and 294B m the respective members which have diameters substantially greater than the shaft 296 of the pm Tapered heads and washers center the pm within the holes to prevent abrasion or wear on the pm shaft The safety pm 295 is provided to ensure the transfer of rotational forces from the shaft through the inner tubular member to the outer tubular member m the event that the resihent member or members become detached with respect to either the inner tubular member or the outer tubular member In operation, the mtermediate shaft 220 is located m the steermg column assembly with U-joint 242 attached to the lower portion of the steermg column assembly 222 and the coupler 276 terconnectmg the upper end of the mtermediate shaft assembly to the steermg column 222 The telescopic action of the shaft 274 permits easy and quick adjustment of the mtermediate shaft assembly to substantially fit or accommodate any gap or variation m the distance between the upper and lower portions of the steermg column Rotational action of the steermg wheel is transmitted to the coupler 276 attached to the end of shaft 274, which m turn imparts rotational energy to the insert fixed at the end of the inner tubular member 260 As a result of the substantially ngid and responsive couplmg of the inner tubular member to the outer tubular member by way of the resihent members 250, the rotational action imparted to the inner tubular member is transfened to the outer tubular member 234 and the coupler 242 Any road or engme vibrations transmitted up through the steermg column are substantially removed or prevented from being transfened to the inner tubular column 260 by the resilient members 250 In the event that the vehicle is mvolved m a collision, any impact or compressive forces expenenced by the intermediate column 220 are absorbed m the telescopmg action of the shaft with respect to the inner and outer tubular members 260, 234 In instances where the collision energy exceeds a certain threshold and impacts the mtermediate column after collapse of the shaft, the outer tubular member fells at the crenulated portion 210 to interrupt the connection between the lower portion of the steermg column assembly to the mtermediate shaft and, in essence, break the physical structure responsible for the transfer of that destructive energy The telescopmg nature of the mtermediate column, when combined with the crumple zone produced by the crenulated portion 210, substantially and significantly reduces the risk of injury to the vehicle operator as a result of the collision with the steermg wheel The above descnption is considered that of the prefened embodiments only Modifications of the mvention will occur to those skilled m the art and to those who make or use the mvention Therefore, it is understood that the embodunents shown in the drawmgs and descnbed above are merely for illustrative purposes and not mtended to limit the scope of the mvention, which is defined by the followmg claims as mteφreted according to the principles of patent law, including the doctrine of equivalents

Claims: The embodiments of the mvention m which an exclusive property or privilege is claimed are defined as follows 1 An mtermediate shaft assembly for a steermg column, compnsmg in combination an outer tube havmg an outer wall and an inner wall defining a first and second ends, at least one resilient tube concentrically disposed within and immediately adjacent said inner wall of said outer tube, said at least one resilient tube havmg an outer wall and an inner wall extendmg between first and second ends, an inner tube havmg a first end concentncally disposed within said inner wall of said at least one resihent tube and havmg a second end extendmg from said second end of said outer tube, said inner tube havmg an outer wall and an inner wall, and a telescopmg shaft assembly havmg a first end concentncally disposed within said inner wall of said inner tube mtermediate said first and second ends of said outer tube, and rigidly secured to said inner tube, and said shaft assembly havmg a second end extendmg from said second end of said inner tube 2 The intermediate shaft assembly as defined in claim 1 , wherein said outer wall of said at least one resilient tube has an outside diameter greater than an mside diameter of said inner wall of said outer tube, and an mside diameter of said inner wall of said at least one resilient tube is less than an outside diameter of said inner tube outer wall 3 The intermediate shaft assembly as defined m claim 1 , wherem said at least one resilient tube mcludes a plurality of resihent tube elements tandemly arranged within said outer tube 4 The mtermediate shaft assembly as defined in claim 1, wherein said telescopmg shaft assembly mcludes an tubular msert disposed within said inner wall of said inner tube and attached to said second end of said inner tube, said tubular msert havmg a polygonal longitudmal axial passage, and a shaft slidably received within said polygonal longitudmal axial passage and rotationally fixed therein 5 The mtermediate shaft assembly as defined in claim 1 , further mcludmg a pm extending transversely through a hole m at least said outer tube and said mner tube 6 The mtermediate shaft assembly as defined in claun 1 , further mcludmg a mechanical bond of said resihent tube to said inner wall of said outer tube and to said outer wall of said inner tube 7 The mtermediate shaft assembly as defined in claim 1 , wherein said resilient tube has a durometer hardness m the range of 50 to 90 8 The mtermediate shaft assembly as defined in claun 1, wherem said outer tube mcludes a collapsible section mtermediate said first and second ends 9 The mtermediate shaft assembly as defined m claim 4, further mcludmg a space between each of said resihent tube elements 10 A steermg column assembly, comprising a tubular outer member closed at one end and open at an opposite end, at least one tubular resilient member concentncally disposed within and m fhctional engagement with an inner wall of said tubular outer member, a tubular inner member concentrically disposed within and m fhctional engagement with an inner wall of said at least one tubular resilient member, said tubular inner member havmg one end extendmg from said open end of said tubular outer member, and a telescopmg polygonal shaft msert assembly havmg a first end concentrically received within said one end of said tubular inner member and attached thereto, with an opposite end of said shaft msert assembly extendmg from said one end of said tubular inner member 11 The steermg column assembly as defined m claun 10, wherem said tubular outer member mcludes a collapsible portion mtermediate said one end and said opposite end 12 A collapsible mtermediate shaft assembly for a vehicle steermg column, compnsmg first and second tubular members, each tubular member open at both ends, said first tubular member concentncally disposed within said second tubular member such that said first end of said first tubular member extends from said first end of said second tubular member, a plurality of resihent tubular isolator members concentrically disposed within said second tubular member and extenor of said first tubular member for fixmg said first tubular member within said second tubular member, a tubular msert member at least partially received m said first end of said first tubular member and ngidly attached thereto, an inner passage of said tubular msert member havmg a polygonal cross-section, and a shaft member, havmg a polygonal cross-section complimentary to said polygonal cross- section of said inner passage, and havmg a first end received within said inner passage of said tubular msert member and translatable along a longitudmal axis m and out of said first tubular member 13 The collapsible mtermediate shaft as defined m claun 12, further mcludmg a pm extending transversely through at least said second end of said first and second tubular members for maintaining said fixed relationship of said first tubular member with respect to said second tubular member 14 The collapsible mtermediate shaft as defined in claim 13, further mcludmg said second end of said second tubular member havmg a crumple zone for shearmg said second end of said second tubular member from a remamder of said second tubular member upon a compressive force of predetermined magnitude 15 The collapsible mtermediate shaft as defined m claim 14, further mcludmg a first coupler attached to said second end of said second tubular member for couplmg the collapsible mtermediate shaft to the steermg column, a second coupler attached to said second end of said shaft for couplmg the collapsible mtermediate shaft to the steermg column, and said plurality of resihent tubular members frictionally engaging said first and second tubular members 16 The collapsible mtermediate shaft as defined m claim 15, further mcludmg an anti- resonant device concentncally received along said second end of said first tubular member and engaging an inner wall of said second tubular member and centermg said second end of said first tubular member within said second tubular member 17 The collapsible mtermediate shaft as defined m claun 16, wherem said first and second tubular members and said plurality of resilient tubular members are right circular cylmders, said polygonal inner passage m said msert member is hexagonal, and said plurality of resilient tubular members are made from a polymenc matenal 18 The collapsible mtermediate shaft as defined in claim 12, further mcludmg said second end of said second tubular member havmg a crumple zone for shearmg said second end of said second tubular member from a remamder of said second tubular member upon a compressive force of predetermined magnitude 19 The collapsible mtermediate shaft as defined in claim 12, further mcludmg a first coupler attached to said second end of said second tubular member for couplmg the collapsible mtermediate shaft to the steermg column, a second coupler attached to said second end of said shaft for couplmg the collapsible mtermediate shaft to the steermg column, and said plurality of resilient tubular members frictionally coupled to said first and second tubular members 20 The collapsible mtermediate shaft as defined m claun 12, further mcludmg an anti- resonant device concentncally received along said second end of said first tubular member and engaging an inner wall of said second tubular member and centermg said second end of said first tubular member within said second tubular member 21 The collapsible mtermediate shaft as defined m claim 16, wherem said first and second tubular members and said plurality of resilient tubular members are nght circular cylmders 22 The collapsible mtermediate shaft as defined m claim 16, wherem said polygonal inner passage m said msert member is hexagonal 23 The collapsible mtermediate shaft as defined in claim 16, wherem said plurality of resilient tubular members are made from a polymenc matenal 24 A method for manufacturing a collapsible mtermediate shaft for a steermg column, comprising the steps of bonding a plurality of resilient tubular isolator members at spaced intervals within a first isolator tube, said resilient tubular isolator members disposed concentrically within said first isolator tube, bonding a second isolator tube concentncally within said plurality of resilient tubular isolator members such that said plurality of resilient tubular isolator members mtercoimect said first isolator tube to said second isolator tube, securely attaching a shaft msert to an end of said second isolator tube extendmg outwardly from an end of said first isolator tube, said shaft formed with a longitudmal passage havmg a polygonal cross-section, and inserting a shaft mto said longitudmal passage of said shaft msert such that said shaft translates between a first and a second longitudmal position, but is fixed rotationally with respect to said shaft msert, said shaft havmg a cross-section shape and dimension conespondmg to said polygonal cross-section of said longitudmal passage AMENDED CLAIMS [received by the International Bureau on 18 December 1998 (18.12.98); original claims 1 and 10 amended; original claim 4 cancelled; new claim 25 added; remaining claims unchanged (4 pages)] 1. An intermediate shaft assembly for a steering column, comprising in combination: an outer tube having an outer wall and an inner wall defining a first and second ends; at least one resilient tube concentrically disposed within and immediately adjacent said inner wall of said outer tube, said at least one resilient tube having an outer wall and an inner wall extending between first and second ends; an inner tube having a first end concentrically disposed within said inner wall of said at least one resilient tube and having a second end extending from said second end of said outer tube, said inner tube having an outer wall and an inner wall; and a telescoping shaft assembly concentrically disposed within said inner tube, said telescoping shaft assembly including a tubular insert disposed within said inner wall of said inner tube and attached to said second end of said inner tube, said tubular insert having a polygonal longitudinal axial passage, and a shaft slidably received within said polygonal longitudinal axial passage and rotationally fixed therein. 2. The intermediate shaft assembly as defined in claim 1, wherein said outer wall of said at least one resilient tube has an outside diameter greater than an inside diameter of said inner wall of said outer tube, and an inside diameter of said inner wall of said at least one resilient tube is less than an outside diameter of said inner tube outer wall. 3. The intermediate shaft assembly as defined in claim 1, wherein said at least one resilient tube includes a plurality of resilient tube elements tandemly ananged within said outer tube. 5. The intermediate shaft assembly as defined in claim 1, further including a pin extending transversely through a hole in at least said outer tube and said inner tube. 6. The intermediate shaft assembly as defined in claim 1, further including a mechanical bond of said resilient tube to said inner wall of said outer tube and to said outer wall of said inner tube. 7. The intermediate shaft assembly as defined in claim 1, wherein said resilient tube has a durometer hardness in the range of 50 to 90. 8. The intermediate shaft assembly as defined in claim 1, wherein said outer tube includes a collapsible section intermediate said first and second ends. 9. The intermediate shaft assembly as defined in claim 4, further including a space between each of said resilient tube elements. 10. A steering column assembly, comprising: a tubular outer member closed at one end and open at an opposite end; at least one tubular resilient member concentrically disposed within and in frictional engagement with an inner wall of said tubular outer member; a tubular inner member concentrically disposed within and in frictional engagement with an inner wall of said at least one tubular resilient member, said tubular inner member having one end extending from said open end of said tubular outer member; and a telescoping shaft assembly concentrically disposed within said inner member, said telescoping shaft assembly including a tubular insert disposed within said inner wall of said inner member and attached to said second end of said inner member, said tubular insert having a polygonal longitudinal axial passage, and a shaft slidably received within said polygonal longitudinal axial passage and rotationally fixed therein. 11. The steering column assembly as defined in claim 10, wherein said tubular outer member includes a collapsible portion intermediate said one end and said opposite end. 24. A method for manufacturing a collapsible intermediate shaft for a steering column, comprising the steps of: bonding a plurality of resilient tubular isolator members at spaced intervals within a first isolator tube, said resilient tubular isolator members disposed concentrically within said first isolator tube; bonding a second isolator tube concentrically within said plurality of resilient tubular isolator members such that said plurality of resilient tubular isolator members interconnect said first isolator tube to said second isolator tube; securely attaching a shaft insert to an end of said second isolator tube extending outwardly from an end of said first isolator tube, said shaft formed with a longitudinal passage having a polygonal cross-section; and inserting a shaft into said longitudinal passage of said shaft insert such that said shaft translates between a first and a second longitudinal position, but is fixed rotationally with respect to said shaft insert, said shaft having a cross-section shape and dimension conesponding to said polygonal cross-section of said longitudinal passage. 25. An intermediate shaft assembly for a steering column, comprising in combination: an outer tube having an outer wall and an inner wall defining a first and second ends; at least one resilient tube concentrically disposed within and immediately adjacent said inner wall of said outer tube, said at least one resilient tube having an outer wall and an inner wall extending between first and second ends; an inner tube having a first end concentrically disposed within said inner wall of said at least one resilient tube and having a second end extending from said second end of said outer tube, said inner tube having an outer wall and an inner wall; and a telescoping shaft assembly having a first end concentrically disposed within said inner wall of said inner tube intermediate said first and second ends of said outer tube, and rigidly secured to said inner tube, and said shaft assembly having a second end extending from said second end of said inner tube.

Inventors: GAUKEL PATRICK D, GAUKEL, PATRICK, D.
Applicants: DOUGLAS AUTOTECH CORP, DOUGLAS AUTOTECH CORP.
Application year: 1998
Main classification: F16D3
IPC codes: B62D1, F16D3