Patent Application
20070259721
Advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
Referring to
A steering gear 74 on the motor vehicle body, remote from the steering column includes an input shaft 76 rotatably supported on a housing 78 of the steering gear and a rack bar 80 supported on the housing for back and forth linear translation in response to rotation of the input shaft. Opposite ends, not shown, of the rack bar are linked to dirigible wheels of the motor vehicle for steering the motor vehicle in the usual fashion in response to rotation of the input shaft 76. An intermediate shaft 82 according to this invention spans the gap between the steering shaft 64 and the steering gear input shaft 76.
The intermediate shaft 82 includes a tubular shaft element 84 and a solid shaft element 86 telescoped into the tubular shaft element and coupled thereto by splines or the like for unitary rotation about and for relative linear translation in the direction of a rotation axis 88 of the intermediate shaft. A lower universal coupling 90 of the steering assembly 60 includes an inner yoke 92 attached rigidly to the tubular shaft element 84, an outer yoke 94 clamped to the steering gear input shaft 76, and a cross or spider (not shown) between the yokes. An upper universal coupling 98 of the steering assembly 60 includes an outer yoke 100 clamped to the steering shaft 64, an inner yoke 102, and a cross or spider (not shown) between the yokes.
Referring to
The sleeve 108 is preferably made of metal and/or a similar rigid material to that of the shaft element 86 having sufficient strength. A cylindrical portion 114 of the sleeve 108 defines a through-bore 116 in the sleeve for axial receipt of the end portion 106 of the shaft element 86. Both the end portion 106 and the cylindrical portion 114 respectively carry a plurality of mating splines 118, 120 that mate to one another for preventing rotation of the sleeve 108 with respect to the shaft element 86. Preferably, the cylindrical portion 114 of the sleeve 108 is fitted tightly enough to prevent any axial movement of the sleeve 108 with respect to the shaft element 86 and may also be crimped or adhered to further secure the rigid connection.
Two diametrically opposite tabs 122, 124 of the sleeve 108 project laterally outward from the cylindrical portion 114 and extend longitudinally in an axial direction with respect to rotation axis 88. Preferably, the elongated tabs 122, 124 are substantially parallel to axis 88 and extend substantially along the entire axial length of the cylindrical portion 114. The tabs 122, 124 generally serve dual functions; first, the tabs 122, 124 prevent rotation of the isolator 110 with respect to the sleeve 108, and second, the tabs 122, 124 act as rotational safety stops against the yoke 102 if the isolator 110 fails or shears due to excessive torque.
The isolator 110 continuously extends circumferentially about the sleeve 108 and has two diametrically opposite cover segments 126, 128 that substantially cover respective tabs 122, 124 of the sleeve 108 and two diametrically opposite ears 130, 132 spaced circumferentially between the tabs 122, 124. Each ear 130, 132 projects radially outward to a convex face 134 that faces radially outward and generally conforms to a partial cylindrical shape that is substantially concentric to axis 88. Preferably, both the cover segments 126, 128 and the convex faces 134 of the ears 130, 132 extend at least the entire axial length of the sleeve 108. Each ear 130, 132 has a lobe 136 that projects axially outward to an apex 138 contiguous to the respective faces 134 and thus extending partially circumferentially with respect to axis 88. Each apex 138 of the lobes 136 is spaced axially beyond a distal and circumferentially continuous edge 140 of the sleeve 108 for resiliently compressible and axial contact with the yoke 102.
The inner yoke 102 of the universal coupling 98 has an inner surface 141 extending circumferentially about axis 88 and a bottom surface 142 disposed substantially perpendicular to axis 88 and contiguous to the inner surface 141. Both surfaces 141, 142 generally define the cavity 112. Two diametrically opposing grooves 144, 146 in the yoke 102 are defined by the inner surface 141 and communicate laterally or radially inward with the cavity 112. A trailing end of each groove 144, 146 is open for axial receipt of the respective cover segments 126, 128 and respective tabs 122, 124. The yoke 102 also has a distal and circumferentially continuous crimp ring 148 disposed concentrically to axis 88 and projecting axially away from bottom surface 142. The crimp ring 148 has an uncrimped state 150, as best shown in
During assembly of the steering assembly 60, the isolator 110 is preferably molded circumferentially about the sleeve 108. As a single unit, the resultant elastomeric coupling 104 is then slid axially over the end portion 106 of the shaft element 86 after rotationally aligning the mating splines 118, 120. Once the cylindrical portion 114 of the coupling 104 is fixed rigidly to the shaft element 86, the cover segments 126, 128 are then rotationally aligned to the grooves 144, 146 in the yoke 102 of the universal coupling 98. Once rotationally aligned, the isolator 110 of the elastomeric coupling 104 of the intermediate shaft 82 is then slid axially and press fitted into the cavity 112 of the yoke 102. This axial insertion continues until the apexes 138 of the lobes 136 of the respective ears 130, 132 generally contact the bottom surface 142 of the yoke 102 that defines in-part the cavity 112.
With the intermediate shaft 82 properly positioned in the yoke 102, the crimp ring 148 is plastically deformed from the cylindrical uncrimped state 150 (see
During operation of the steering assembly 60, the convex faces 134 of the ears 130, 132 generally remain in stationary contact with the inner surface 141 of the yoke 102. The radial thickness of the ears 130, 132 and corresponding shear strength and the thickness of the cover segments 126, 128 of the isolator 110 and corresponding compressibility enable absorption of rotational or torque induced vibration. The axial projection of the lobes 136, the tapering down effect to the distal apexes 138 of the lobes 136, and the axial clearance between any portion of the rigid sleeve 108 and the rigid yoke 102 provides and assures absorption capability of axially induced vibrations.
Rotational movement of the yoke 102 is transmitted to the shaft element 86 through the exterior driving faces 134 of the isolator 110. Moreover, the grooves 144, 146 in the yoke 14 generally engage the cover segments 126, 128 of the isolator 110 to transmit rotational movement of the yoke 102 to the shaft element 86. In addition to transmitting rotational movement of the yoke 102, the isolator 110 disrupts noise and vibration between the shaft element 86 and the yoke 102. The elastomeric isolator 110 is of a sufficient elasticity and thickness to adequately isolate noise and vibration by operating in compression. Further, as best shown in
Known intermediate shafts typically utilize isolators, unlike the present invention, made of santoprene and having an axial compliance of about 600 to 800 Newtons per millimeter which is generally insufficient for absorbing axial vibrations. Changing to a softer or more flexible material such as neoprene is desirable, however, such use would cause known isolators to fail or shear upon application of typical torsional forces. U.S. Pat. No. 6,533,666, previously cited, utilizes neoprene and resolves the failure concerns when torque is applied by introducing the lugs 46 as part of the rigid sleeve 34. Unfortunately, the lugs along with additional factors eliminate or substantially reduce the ability of the isolator 30 to absorb axial vibration.
The intermediate shaft 82 of the present invention can absorb axial vibration and has an axial compliance within the range of 70 to 300 Newtons per millimeter. In comparison, the axial compliance of the intermediate shaft disclosed in U.S. Pat. No. 6,533,666 is about 400 to 500 Newtons per millimeter. This improvement in axial compliance is achieved by the structural differences of the intermediate shaft while maintaining a connecting yoke of substantially the same size.
Referring to
While the forms of the invention herein disclosed constitute presently preferred embodiments, many other are possible. For instance, the sleeve 108 may be a unitary part of the shaft element 86 (i.e. manufactured as one unitary piece). It is not intended herein to mention all the possible equivalent forms or ramification of the invention. It is understood that terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention.
This application claims priority of U.S. Provisional Patent Application Ser. No. 60/798,632 filed May 8, 2006, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60798632 | May 2006 | US |
