AXLE WHEEL END AXIAL THRUST ASSEMBLY

FIELD OF THE INVENTION

[0001] The present disclosure relates generally to solid axle assemblies for vehicles and, more specifically, to bearing assemblies that are utilized on the wheel end sections of such solid axle assemblies.

BACKGROUND

[0002] Salisbury solid axles are often used in passenger trucks and sport utility vehicles. Salisbury axles are unique in the fact that the axle transmits driving torque to the wheel as well as carries and transmits both radial and axial thrust loads.

[0003] As shown in Figure 1 , many existing wheel end bearings 10 for use with solid vehicle axles include an outer cup 11 that is press-fit into the corresponding axle tube 12 to maintain location and define an outer raceway for the corresponding rollers 13. No additional retention features are required for this type of wheel end bearing 10 in that the bearing only handles radial loads. Lubrication for wheel end bearing 10 is provided by the same oil sump that provides lubrication to the differential gears 15 (Figure 2) that are disposed at the center section of the axle assembly. To maintain lubrication, an oil seal 14 is press-fitted outboard of the wheel end bearing in axle tube 12.

[0004] Radial wheel end loads are handled primarily at wheel end bearing 10, whereas axial loads are not. Rather, as best seen in Figures 2 through 4, axial loads are transmitted along axle shaft 16. Typically, "C Locks" 18 are utilized to resist outward axial loading and a cross shaft 20 disposed between the opposing axles in a housing 25 of differential 17 absorbs inward axial loading. A typical C Lock includes a heavy annular lock ring 19 received in an annular groove 21 formed on the inboard end of a corresponding axle shaft 16. In the fully assembled configuration (Figure 3), annular lock ring 19 is further received in an annular recess 23 formed in an end face of a corresponding differential gear 15. During normal operations, inward axial loading has a higher magnitude than outward axial loading due to vehicle dynamics during cornering. When outward axial load on axle shaft 16 occurs, axle shaft 16 attempts to move outwardly from axle tube 12, which causes annular lock ring 19 of the corresponding C Lock 18 to push on the corresponding differential side gear 15.

Ultimately, the outward axial load is dispersed through differential carrier bearings 24 to housing 25 of the differential, as shown in Figure 4.

[0005] When inward axial loading is generated from vehicle cornering, an end face 27 of axle shaft 16 thrusts against differential cross shaft 20, as best seen in Figure 2. In turn, the inward axial loading is transmitted through differential carrier bearings 24, as shown in Figure 4.

[0006] The present invention recognizes and addresses considerations of prior art constructions and methods.

SUMMARY

[0007] One embodiment of an axle assembly of a vehicle includes a differential assembly, a first axle tube extending outwardly from a first side of the differential assembly, the first axle tube including a proximal end adjacent the differential assembly, an opposite distal end, and an axle bore extending therebetween, a first axle shaft rotatably received in the first axle tube, the first axle shaft including a proximal end disposed in the differential assembly, and an opposite distal end extending outwardly from the distal end of the first axle shaft, a radial bearing assembly including an outer race and a plurality of roller elements rotatably received therein, the radial bearing assembly being axially fixed within the axle bore of the first axle tube, and an annular collar that is disposed within the axle bore of the first axle tube and is both axially and non-rotatably fixed to the axle shaft, the annular collar being disposed between the proximal end of the axle shaft and the radial bearing assembly, wherein the annular collar abuts the radial bearing assembly as the first axle shaft moves outwardly with respect to the first axle tube.

[0008] Another embodiment of an axle assembly of a vehicle includes a differential assembly, a first axle tube extending outwardly from a first side of the differential assembly, the first axle tube including a proximal end adjacent the differential assembly, an opposite distal end, and an axle bore extending therebetween, a first axle shaft rotatably received in the first axle tube, the first axle shaft including a proximal end disposed in the differential assembly, and an opposite distal end extending outwardly from the distal end of the first axle shaft, a radial bearing assembly including an outer race and a plurality of roller elements rotatably received therein, and an annular collar that is disposed within the axle bore of the first axle tube and is axially fixed to the axle shaft, the annular collar being disposed between the proximal end of the axle shaft and the radial bearing assembly, wherein the annular collar abuts the radial bearing assembly as the first axle shaft moves outwardly with respect to the first axle tube. [0009] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended drawings, in which:

[0011] Figure 1 is a partial cross-sectional view of a wheel end section of a prior art solid axle assembly;

[0012] Figure 2 is a partial perspective view of the prior art axle shaft shown in Figure 1 and a corresponding differential;

[0013] Figure 3 is a partial perspective view of the prior art axle shaft and differential shown in Figure 2, including a cross shaft of the differential;

[0014] Figure 4 is a cut away side view of the prior art axle shaft and differential shown in Figure 2;

[0015] Figure 5 is a partial cross-sectional view of a wheel end section of a solid axle assembly including an axial thrust assembly in accordance with an embodiment of the present invention; and

[0016] Figure 6 is an exploded perspective view of the axial thrust assembly shown in Figure 5.

[0017] Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention according to the disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Reference will now be made in detail to presently preferred embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation, not limitation, of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope and spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0019] Referring now to Figures 5 and 6, a wheel end axial thrust assembly 100 for use with a solid vehicle axle in accordance with an embodiment of the present disclosure includes a thrust component including an annular collar 102, a radial bearing assembly 160, and a snap ring 150 received in an annular groove 148 of the corresponding axle tube 140, outboard of radial bearing assembly 160. Axial thrust assembly 100 is disposed in the wheel end of axle tube 140 about the wheel end of a corresponding axle shaft 130, as discussed in greater detail below.

[0020] Annular collar 102 of the axial thrust component includes an annular body portion having a cylindrical inner surface 104, a cylindrical outer surface 105, and a pair of annular sidewalls 106 extending therebetween. As best seen in Figure 5, an annular flange 108 extends axially outwardly from the inner perimeter of its outboard sidewall 106. The distal end of annular flange 108 terminates in an annular end face 109 that is substantially transverse to a longitudinal center axis of axle shaft 130. As shown, at least one threaded bore 110 (two are utilized in the present example) extends through the body portion of annular collar 102 from its outer surface 105 to its inner surface 104. Threaded bore 110 is configured to receive an oval point set screw 112 having a corresponding threaded outer surface 114 therein so that a domed end 116 of the set screw extends inwardly beyond inner surface 104 of annular collar 102. As such, domed end 116 of set screw 112 can engage a correspondingly shaped recess 132 in axle shaft 130, thereby non-rotatably fixing annular collar to axle shaft 130. Utilizing a set screw and recess configuration to affix annular collar 102 to axle shaft 130 reduces stress

concentrations in the axle shaft as compared to a snap ring and annular groove arrangement. Note, in alternate embodiments set screws having variously shaped ends (dog point, conical, etc.) may be used to engage correspondingly shaped recesses formed in axle shaft 130, thereby fixing annular collar 102 thereto. In yet other embodiments, a roll pin can be received in a through bore formed in axle shaft 130 to affix annular collar 102 thereto.

[0021] Axle tube 140 includes at least one access aperture 142 to allow set screws 112 to pass therethrough and be threadedly engaged with a correspondingly threaded bore 110 of annular collar 102. As shown, access aperture 142 is threaded and configured to receive a correspondingly threaded plug 144. As well, the diameter of access aperture 142 is preferably greater than the diameter of threaded outer surface 114 of set screw 112 so that set screw 112 can pass therethrough without having to engage its threads. Preferably, set screw 112 and threaded plug 144 include drive recesses 118 and 146, respectively, that are configured to be engaged by a corresponding hex key. Alternately, various configurations of the bores may be utilized to receive tool ends of various shapes, such as flat blades, Phillips head, etc.

[0022] Outer cup 162 of radial bearing assembly 160 defines a cylindrical outer race 164 for needle rollers 170. A first annular flange 166 and second annular flange 168 extend radially-inwardly from opposite ends of outer race 164. As shown in Figure 5, an annular gap exits between the inner perimeter of first annular flange 166 and the outer surface of axle shaft 130. The annular gap allows annular flange 108 of annular collar 102 to extend axially along axle shaft 130 so that end face 109 of annular flange 108 abuts the plurality of rollers 170, as discussed in greater detail below. Outer cup 162 is preferably a machined and ground component made from a carburized grade of steel to enhance control of the press-fit, bearing clearances, and increase allowable hoop stresses.

[0023] Outer cup 162 is preferably received in cylindrical recess 143 of axle tube 140 in a press-fit, outboard of annular collar 102 adjacent an annular flange 145 that is transverse to the longitudinal center axis of axle tube 140. Annular flange 145 extends inwardly from cylindrical recess 143 to bore 141 of axle tube 140. Outer cup 162 is press-fit in cylindrical recess 143 to assist in handling outward axial thrust forces. Note, in some embodiments, outward axial thrust forces are handled solely by the press-fit of outer cup 162 in axle tube 140. However, in the present embodiment, a snap ring 150 is provided in an annular groove 148 defined by the inside surface of axle tube 140 to handle outward axial thrust forces. A split 151 in snap ring 150 allows the ring to be compressed as it is slid inwardly into cylindrical recess 143 of axle tube 140, expanding outwardly upon being seated in annular groove 148. An oil seal 180 is press-fit into axle tube 140 outboard of snap ring 150 to help maintain lubricating fluids therein.

[0024] Each needle roller 170 disposed in outer cup 162 includes a cylindrical rolling surface extending between a first end face 172 and a second end face 174. Each first and second end face 172 and 174 is transverse to a longitudinal center axis of the corresponding needle roller 170. As such, when needle rollers 170 are disposed between the outer surface of axle shaft 130 and outer cup 162, first end faces 172 and second end faces 174 are parallel to first annular flange 166 and second annular flange 168, respectively, of outer cup 162.

[0025] During vehicle operations, axial thrust forces on axle shaft 130 are transferred to annular collar 102 due to set screws 112, of which there are two in the present embodiment, engaging corresponding recesses 132 of axle shaft 130. When the axial thrust force is directed outwardly, the axial thrust force is transferred from annular collar 102 to rollers 170 by way of abutment of end face 109 of its annular flange 108 with first end faces 172 of the plurality of rollers. Subsequently, the outward axial thrust force is transferred to outer cup 162 by the abutment of second end faces 174 of the plurality of rollers 170 with its second annular flange 168. Note, when the outward axial thrust force is low enough, the press-fit between outer cup 162 and axle tube 160 may be great enough to prevent outward motion of axle shaft 130.

However, when the thrust force is great enough, outer cup 162 transfers the axial thrust force to snap ring 150. Snap ring 150 ultimately transfers the axial thrust force to axle tube 140 by way of being seated in annular groove 148 thereof. As previously noted, in alternate embodiments, snap ring 150 is not required where the press-fit between outer cup 162 and axle tube 140 exceeds maximum expected outward axial thrust forces on axle shaft 130. In alternate embodiments, annular thrust washers may be disposed between one or both of first end faces 172 of rollers 170 and first annular flange 166, and second end faces 174 of rollers 170 and second annular flange 168, to provide more uniform bearing surfaces during thrust force transfer.

[0026] Inward axial thrust forces acting on axle shaft 130 are preferably handled by abutment of the axle shaft's innermost end with a cross shaft 20 (Figures 3 and 4) of the axle's differential, in the manner previously discussed. [0027] While one or more preferred embodiments of the invention are described above, it should be appreciated by those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope and spirit thereof. It is intended that the present invention cover such modifications and variations as come within the scope and spirit of the appended claims and their equivalents.