INTEGRATED SEAL DESIGN FOR JOINT COVER ASSEMBLY

Cross Reference to Related Applications

[0001] This application claims priority to U.S. Provisional Patent Application 60/956,315, filed August 16, 2007, the disclosure of which is incorporated by reference in its entirety.

Technical Field

[0002] The present disclosure relates to sealing cover assemblies and in particular to a constant velocity joint (CVJ) sealing cover assembly, such as a boot cap assembly or a grease cover assembly.

Background

[0003] Universal joints, and especially constant velocity joints, operate to transmit torque between two rotational members. The rotational members are typically interconnected by a cage, or yoke, that allows the rotational members to operate with their respective axes at a relative angle. Constant velocity joints and similar rotating couplings typically include a boot cover assembly and grease cover to enclose and protect the coupling during operation. Since the boot cover assembly is partially flexible, the boot cover assembly is able to seal around the joint while permitting articulation and relative axial movement of differing rotating members of the joint. The boot cover assembly and the grease cover seal lubricant in the joint so as to reduce friction and extend the life of the joint. The boot cover assembly and the grease cover also seal out dirt, water and other contaminants to protect the functionality of the joint. However, leaks may reduce the life of the joint, and contaminants in the grease may disturb the chemical composition of the grease, degrading its performance.

[0004] Universal joints are commonly classified by their operating characteristics. One important operating characteristic relates to the relative angular velocities of the two shafts connected thereby. In a constant velocity type of universal joint, the instantaneous angular velocities of the two shafts are always equal, regardless of the relative angular orientation between the two shafts. In a non-constant velocity type of universal joint, the instantaneous

angular velocities of the two shafts vary with the angular orientation (although the average angular velocities for a complete rotation are equal). Another important operating characteristic is the ability of the joint to allow relative axial movement between the two shafts. A fixed joint does not allow this relative movement, while a plunge joint does.

[0005] FIG. 1 illustrates a constant velocity joint (CVJ) 20. CVJ 20 includes driven end 22 and a driving end 24. CVJ 20 further includes a joint assembly 26 coupled to a shaft 28 with a boot cover assembly 30 connected therebetween. CVJ 20 further includes a grease cover 32 that seals the driving end 22. Boot cover assembly 30 includes a metal cover 34 and a flexible boot 40. A portion of metal cover 34 is crimped onto boot 40 for attachment thereto. Boot cover assembly 30 protects the moving parts of CVJ 20 during operation. Joint assembly 26 includes a first rotational member 42, a second rotational member 44, and a plurality of balls 46. Shaft 28 is splined to second rotational member 44 to allow axial movement therebetween. Metal cover 34 has an axial length Ll that is defined by the axial distance that metal cover 34 extends from the first rotational member 42 to the crimped attachment of metal cover 34. [0006] Joint assembly 26 can be any type of articulated universal joint, including a plunging tripod, a fixed tripod, a plunging ball joint, and a fixed ball joint. As will be discussed in greater detail herein, boot 40 may be employed with any type of articulating joint. During operation of CVJ 20, boot 40 accommodates relative axial displacement of a joint assembly 26 and shaft 28 while maintaining a seal therebetween.

[0007] With continual reference to FIG. 1 and specific reference to FIG. 2, the boot 40 includes a contoured body of revolution 52 having a small end 54, a large end 56, a middle portion 58, and a curved portion 60. As illustrated in FIG. 1, small end 54 is coupled to shaft 28 and large end 56 is crimped to metal cover 34, which is, in turn, coupled to first rotational member 42. Small end 54 may be coupled to shaft 28 with a conventional type of 'hose clamp' connector or any other suitable means.

[0008] While boot cover assembly 30 may be adequate for certain applications, greater relative angles of operation of CVJ 20 may result in shaft 28 contacting large end 56. To avoid this contact, greater clearance between metal cover 34 and shaft 28 may be required. However, the resulting larger diameter of the metal cover 34 would increase the weight of the CVJ 20.

Also to avoid this contact, a shorter axial length Ll may be provided to permit greater articulation, or a greater operating angle, within CVJ 20. However, a shorter axial length Ll would result in greater stresses in the crimped connection between metal cover 34 and large end 56 as axial movement between shaft 28 and second rotational member 44 causes curved portion 60 to roll and operation at greater operating angles induces stresses in boot 40 that, at least in part, transmit through the crimped connection. Additionally, the rotational speeds (over about 10,000 rprn) of the CVJ 20 imparts centrifugal forces on the boot 40 which may distort the shape of the boot 40 and impart additional stresses and forces into the crimped connection. [0009] In addition, the crimped connection between metal cover 34 and boot 40 may allow leaks if improperly crimped or overstressed. Greater articulation or greater axial movement within CVJ 20 may result in greater decoupling stresses and forces within the crimped connection. These increased decoupling stresses and forces may result in premature failure of the crimped connection. That is, values of stresses, forces, and deflection that can be tolerated in curved portion 60 cannot be tolerated in the crimped connection of boot cover assembly 30. Furthermore, a desirable boot cover assembly would provide a more reliable interconnection between the cover and boot than a crimped connection.

[0010] What is needed, therefore, is a boot cover assembly that can accommodate greater axial extension and relative angles within a joint assembly, reduce weight, simplify manufacture, and produce a more reliable boot cover assembly.

Brief Description of the Drawings

[0011] Referring now to the drawings, exemplary illustrations are shown in detail. Although the drawings represent some examples, the drawings are not necessarily to scale and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present invention. Further, the exemplary illustrations set forth herein are not intended to be exhaustive or otherwise limit or restrict the claims to the precise forms and configurations shown in the drawings and disclosed in the following detailed description. [0012] FIG. 1 is a sectional view of a prior art constant velocity joint. [0013] FIG. 2 is a sectional view of a prior art boot.

[0014] FIG. 3 is a sectional view of a joint assembly in accordance with one exemplary illustration.

[0015] FIG. 4 is a sectional view of the boot cover assembly of FIG. 3. [0016] FIG. 5 is a partial sectional view of a boot cover portion of the boot cover assembly of FIG. 4.

[0017] FIG. 6 is a perspective view of the boot cover portion of FIG. 5. [0018] FIG. 7 is an end view of the boot cover portion of FIG. 5, illustrating the view of FIG. 4 as line 4-4.

[0019] FIG. 8 is an enlarged partial sectional view of the boot cover portion taken along line 8-8 of FIG. 7, with the boot portion removed for clarity.

[0020] FIG. 9 is a sectional view of detail area 9 of the boot cover assembly of FIG. 8, with the boot portion removed for clarity.

[0021] FIG. 10 is an enlarged view of sectional view portion 9 of FIG. 8, with a portion of a first rotational member included for clarity.

[0022] FIG. 11 is a partial sectional view of the boot cover portion taken along line 8-8 of FIG. 7.

[0023] FIG. 12 is an enlarged view of encircled area 12 of FIG. 4, a portion of a first rotational member included for clarity.

[0024] FIG. 13 is a sectional view of an alternative example of the boot cover assembly of FIG. 4.

[0025] FIG. 14 is a perspective view of the assembly of FIG. 13.

[0026] FIG. 15 is an end view of the assembly of FIG. 13, illustrating the view of FIG. 13 as line 13-13.

[0027] FIG. 16 is an end view of the assembly of FIG. 13 (taken opposite the view of FIG. 15), illustrating the view of FIG. 13 as line 13-13.

[0028] FIG. 17 is a partial sectional view of the boot cover portion taken along line 17-17 of FIGS. 15 and 16.

[0029] FIG. 18 is an enlarged view of encircled area 18 of FIG. 17. [0030] FIG. 19 is an enlarged view of encircled area 19 of FIG. 13.

[0031] FIG. 20 is an enlarged view of encircled area 20 of FIG. 13. [0032] FIG. 21 is an enlarged view of encircled area 21 of FIG. 13. [0033] FIG. 22 is a sectional view of a portion of an exemplary boot cover assembly.

Detailed Description

[0034] Various exemplary illustrations are provided herein of an articulating joint and a method of making the same. An articulating joint may include a first rotational member, a second rotational member coupled to the first rotational member for rotation therewith, and a sealing cover assembly. The sealing cover assembly includes a first portion selectively coupled to the first rotational member, and a second portion selectively coupled to the second rotational member. The second portion may be molded onto the first portion. The first portion includes a retaining feature. The sealing cover assembly further includes a coupling region formed on a surface of the retaining feature and disposed adjacent the first rotational member when the first portion is coupled to the first rotational member. The coupling region is configured to form a mechanical interlock between the first portion and the second portion. The coupling region also includes a sealing surface configured to seal against the first rotational member. [0035] An exemplary method for manufacturing a sealing cover for an articulating joint may include forming a first portion having a first side and a second side, such that the first side at least partially defines a retention feature, and forming a second portion on the first portion. The second portion is mechanically interlocked onto a portion of the first portion during the forming of the second portion. Forming the first portion includes forming a sealing surface, and forming the second portion includes forming a sealing lip on the sealing surface. The sealing lip includes a generally planar surface for sealing the first rotational member of the joint. [0036] FIG. 3 illustrates a joint 120 having a driven end 122 and a driving end 124. Joint 120 further includes a joint assembly 126 that is coupled to a shaft 128. A boot cover assembly 130 is connected between the joint assembly 126 and the shaft 128. A grease cover 132 seals the driving end 124 of joint 120. Joint assembly 126 includes a first rotational member 142, a second rotational member 144, and a plurality of balls 146. As illustrated, shaft 128 is splined to second rotational member 144. A plurality of fasteners 148 secure the assembly 130 to the first

rotational member 142. While the fasteners 148 are illustrated as bolts that are threaded into apertures within the first rotational member 142, other suitable fasteners may be used. The first rotational member 142 includes a generally annular surface 152 for sealing with the boot cover assembly 130. Viewed in section in FIG. 3, the annular surface 152 extends about a perimeter of the first rotational member 142.

[0037] FIGS. 4 and 5 illustrate the boot cover assembly 130 in greater detail. Boot cover assembly 130 serves to protect moving parts of joint 120. The boot cover assembly 130 includes a cover portion 154, a boot portion 156, and a coupling region 158. [0038] Coupling region 158 may include a mechanical interlocking between the cover portion 154 and the boot portion 156, in any variety of ways described below. For example, coupling region 158 may include apertures in one of the cover or boot portions, such that the other of the cover and boot portions is received in the apertures. Apertures may thus encourage retention of the boot portion by the cover portion in the coupling region. Apertures may take a variety of forms, described further below. Merely by way of example, apertures may include an annular groove about a perimeter of the cover portion 154, one or more apertures formed about cover portion 154, or the like. Alternatively or in addition to the apertures, a coupling link may be provided that secures a cover and boot portion together, as further described below. [0039] As another example of a mechanical interlocking between cover and boot portions 154, 156, cover and boot portions 154, 156 may be formed of different materials and chemically and/or physically bonded to each other in a generally single-stage, two-shot forming process. For example, the cover and boot portions 154, 156 may each be generally simultaneously injection molded in a single mold, where a first material used to form the cover portion 154 is introduced to a first side of a mold, and a second material used to form the boot portion 156 is introduced at a second generally opposite side of the mold. The first material and second material thus may generally run into the interior of the mold, "meeting" anywhere between the first and second sides of the mold, preferably in the vicinity of the coupling region 158, during the process of forming the cover and boot portions 154, 156, as further described below. [0040] Cover portion 154 is generally defined by an axis A-A and formed of a first material 162, and boot portion 156 is formed of a second material 164, as discussed below. Cover portion

154 has a generally radially extending annular face 170 that abuts the surface 152 of the first rotational member 142 (with a sealing lip interposed therebetween, as discussed in greater detail below), and an axially extending generally cylindrical body 172 that extends between the first rotational member 142 and the coupling region 158. Cylindrical body 172 has an axial length L2 (see FIG. 4) that is defined by the distance that cover portion 154 extends from the first rotational member 142 to the coupling region 158.

[0041] The cover portion 154 further includes an axially extending lip 174 and a retaining feature 176 having a plurality of retaining apertures 178 formed therein. Cover portion 154 also includes apertures 180 to allow fasteners 148 to directly fasten cover portion 154 to first rotational member 142. In one embodiment, the fasteners 148 are interposed through the cover portion 154 and threaded into the first rotational member 142. A sealing portion 188 is formed on the face 170 and includes a raised generally annular body.

[0042] As best seen in FIG. 6, the boot cover portion 154 includes a plurality of fastening portions 190 and a plurality of connecting portions 192. In the illustrative embodiment, each fastening portion 190 includes an aperture 180 formed therein. Each of the connecting portions 192 interconnects at least two of the fastening portions 190 about the axis A-A (when viewed along the axis A-A, as is FIG. 7). Each fastening portion 190 is defined, at least in part, by a first fastening surface portion 200 (see FIG. 12) that is generally perpendicular to the axis A-A, and a second fastening surface portion 202 that is oriented at an angle α with respect to the first fastening surface portion 200 when viewed perpendicular to the axis A-A, as best seen in FIG. 12. At least a portion of the boot portion 156 is attached to the first fastening surface portion 200 and the second fastening surface portion 202.

[0043] As best seen in FIGS. 4 and 10-12, the sealing portion 188 may vary in geometry about the axis A-A, about a perimeter of cover portion 154. Specifically, the sealing portion 188, while forming a continuous lip surface 210 about the axis A-A for sealing with the first rotational member 142, is shaped in a first configuration 212 adjacent each of the plurality of fastening portions 190, as shown in FIG. 12, and in a second configuration 214 adjacent each of the plurality of connecting portions 192, as shown in FIG. 10. That is, the sealing portion has different configurations depending on, at least, whether the sealing portion is adjacent a portion

of the boot cover 154 that includes a fastening portion. These different configurations may be advantageous due to the differing amounts of compression typically experienced adjacent a fastening portion 190 as compared to a portion of a sealed member that is between fastening portions 190.

[0044] With attention to FIG. 12, each fastening portion 190 includes a generally planar fastening surface 220 that is generally the same as the face 170. Each connecting portion 192 includes a first connection portion 224, a step portion 226, and a transition portion 228, a generally planar connecting surface 230, a generally planar step surface 232, and a transition surface 234 (FIGS. 9 and 10). The first connection portion 224 is defined, at least in part, by the connecting surface 230, the step portion 226 is defined, at least in part, by the step surface 232, and the transition portion 228 is defined, at least in part, by the transition surface 234. [0045] The sealing portion 188 abuts the plurality of step surfaces 232 and the plurality of fastening surfaces 220. As best seen in FIGS. 4 and 11, the lip surface 210 is generally planar for contacting and sealing with the surface 152 of the first rotational portion 142. As best seen in FIG. 10, the lip surface 210 may include two beads 240 for contacting the surface 152 of the first rotational member 142. Alternatively, as best seen in FIG. 12, the lip surface 210 may include a single bead 244 for contacting the surface 152 of the first rotational member 142. [0046] As best seen in FIGS. 5 and 6, each fastening portion 190 includes a semi-cylindrical second fastening portion 250 defined, at least in part, by one of the second fastening surface portions 202. Each second fastening portion 250 permits a fastener 148 to couple the assembly 130 with the first rotational member 142. In the embodiment illustrated, each second fastening portion 250 permits a fastener 148 to be rotated as the fastener 148 threads into an aperture within the first rotational member 142.

[0047] In the embodiment illustrated, a second fastening portion 254 of the boot portion 154 is coupled to each of the second fastening surface portions 202 of the cover portion 156. Also in the embodiment illustrated, the second fastening portion 254 is formed of the second material 164 and integral with the sealing portion 188. An interface 256 between the second fastening portions 254 and the second fastening surface portions 202 is bonded with an adhesive. As best seen in FIG. 12, when the assembly 130 is fastened to the first rotational member 142, the

surface 210 seals with the surface 152 as the sealing portion 188 is at least partially forced toward the direction F, e.g., by surface 152. The direction F is generally parallel to the axis A-A. Therefore, each interface 256 between the second fastening portions 254 and the second fastening surface portions 202 is generally maintained in shear. This shear force resists movement of the sealing portion 188 to provide a sealing force on the first configuration 212 of the sealing portion 188, to provide a seal between the fastening portions 190 and the first rotational member 142. The second configuration 214 of the sealing portion 188, by contrast, is generally compressed between the step 226 and the surface 152 to provide a seal between the connecting portions 192 and the first rotational member 142. Accordingly, the sealing portion 188 is formed generally continuously about a perimeter of cover assembly 130 and/or surface 152 of first rotational member 142, albeit in differing configurations 212, 214 that alternate about the axis A-A. The sealing portion 188 thus provides a seal against the first rotational member 142 substantially about an entire perimeter of the first rotational member 142. An adhesive may not be included between the step 226 and the second configuration 214 of the sealing portion 188 since the second configuration 214 of the sealing portion 188 is coupled to the step 226 by compression when the first rotational member 142 is fastened to the assembly 130 (as compared to the connection in shear at the interface 256, for which an adhesive may be employed for additional stability of the boot portion 156 relative to the cover portion 154). [0048] With particular attention to FIG. 4, the assembly 130 may also include molding legs 260 that interconnect the second fastening portion 254 and the sealing portion 188 with the boot portion 156. That is, the second material 164 may be injected into a mold and permitted to flow to simultaneously form the boot portion 156, the second fastening portion 254 and the sealing portion 188, generally in a single unitary or integral piece.

[0049] Boot cover assembly 130 may be formed by injection molding. The mold may include a cover region and a boot region. Boot cover portion 154 may be molded in the shape illustrated in FIGS. 5-6, inserted into a cover region of the mold, and then the second material 164 injected into the boot region of the mold. The molded boot cover assembly 130 is then allowed to cure, thereby forming the boot cover assembly 130.

[0050] First material 162 may be a relatively rigid material, and may be a metal, an alloy, or selected from the family of thermoplastic polyester resins, specifically polybutylene terephthalate (PBT) and polyethylene terephthalate (PET) or may be a thermoplastic vulcanizates (TPV) or a nylon or nylon blend. First material 162 may also be a resin and a filler to increase rigidity and strength. While fillers such as carbon fiber and glass fibers are preferred, other fillers compatible with the contemplated resins could also be used. The first material may be a metal or a metal alloy that is formable by stamping such that the cover portion 154 may be stamped.

[0051] Second material 164 is preferably a flexible material, and may be plastic or any elastomer, such as rubber, silicone, or thermoplastic elastomer (TPE). Also preferably, second material 164 has hardness values in the range of about 55-75 Shore A or about 35-55 Shore D, and even more preferably, a hardness of about 40-44 Shore D. Materials that are specifically compatible with a typical boot cover assembly 130 environment are relatively rigid thermoplastic polyesters for first material 162, and thermoplastic polyester elastomers for second material 164 due to the desirable bonding formed in coupling region 158 during the two-shot molding process. [0052] The connection between cover portion 154 and boot portion 156 is more resistant to decoupling stresses and forces than the prior art crimped connection. That is, values of stresses, forces, and deflection that can be tolerated in coupling region 158 of boot cover assembly 130 may not be tolerated in the crimped connection of boot cover assembly 30. This more resistant connection can better accept greater articulation and axial movement within joint 120. [0053] In addition, in accordance with one aspect of the invention, the first material 162 of cover portion 154 may be lighter than the metals used to produce a typical prior art metal cover 34. Therefore, when assembled, boot cover assembly 130 provides a lighter joint 120. [0054] Alternatively, the first material may be a die cast metal. When the first material is die cast, an adhesive may be used either with or without retaining apertures, as desired. [0055] FIGS. 13-21 illustrate an alternative embodiment of the boot cover assembly of FIG. 4 that may entirely eliminate any need for an adhesive to bond the first material to the second material. A boot cover assembly 330 may be connected between a joint assembly, e.g., joint assembly 126, substantially as described above in regard to cover assembly 130. Boot cover

assembly 330 serves to protect moving parts of a joint, and may have a first end 322 (corresponding to a driven end of the joint) and a second end 324 (corresponding to a driving end of the joint). The boot cover assembly 330 includes a cover portion 354, a boot portion 356, and one or more coupling regions 358a,b (collectively, 358).

[0056] Cover portion 354 is generally defined by an axis B-B and formed of a first material 362, and boot portion 356 is formed of a second material 364. Cover portion 354 has a generally radially extending annular face 370 that abuts a surface 352 of a first rotational member 342 (with a sealing lip interposed therebetween, as discussed in greater detail below), and an axially extending generally cylindrical body 372 that extends between the first rotational member 342 and a first one of the coupling regions 358a. A second coupling region 358b is disposed adjacent the annular face 370, and generally provides a second site for mechanical interlock features for the boot portion 356 adjacent a sealing surface 388 of the boot portion 356, as will be described further below.

[0057] The cover portion 354 further includes an axially extending lip 374. Cover portion 354 also includes apertures 380 to receive fasteners (not shown) to directly fasten cover portion 354 to first rotational member 342. As best seen in FIG. 16, fasteners may be interposed through the cover portion 354 and threaded into the first rotational member 342. A sealing portion 388 is formed on the face 370 and includes a raised generally annular body for abutting surface 352, thereby sealing a perimeter, even the entire portion of a perimeter, of the first rotational member 342. In other words, sealing portion 388 may form a continuous lip surface 410 about the axis B-B for sealing with the first rotational member 342, thereby providing a seal surface that seals substantially about an entire perimeter of the first rotational member 342. [0058] As best seen in FIG. 16, the boot cover portion 354 includes a plurality of fastening portions 390 and a plurality of connecting portions 392. In the illustrative embodiment, each fastening portion 390 includes an aperture 380 formed therein. Each of the connecting portions 392 interconnects at least two of the fastening portions 390 about the axis B-B (when viewed along the axis B-B, as is FIG. 16). Each fastening portion 390 is defined, at least in part, by a first fastening surface portion 400 that is generally perpendicular to the axis B-B (FIG. 19), and a second fastening surface portion 402 that is orientated at an angle α with respect to the first

fastening surface portion 400 when viewed perpendicular to the axis B-B (FIGS. 17 and 18). At least a portion of the boot portion 356 is attached to the first fastening surface portion 400 and the second fastening surface portion 402.

[0059] Each fastening portion 390 and each connecting portion 392 includes a first portion 424, a step portion 426, and a transition portion 428, a generally planar connecting surface 430, a generally planar step surface 432, and a transition surface 434. The first portion 424 is defined, at least in part, by the connecting surface 430, the step portion 426 is defined, at least in part, by the step surface 432, and the transition portion 428 is defined, at least in part, by the transition surface 434. The step surface 432 includes a groove 436 (FIGS. 16, 18 and 19) that generally continuously encircles the axis B-B, although in the embodiment illustrated, the groove 436 is not circularly shaped about the entire perimeter of cover portion 154 when viewed along the axis B-B.

[0060] The sealing portion 388 abuts the plurality of step surfaces 432. As best seen in FIGS. 13 and 17, the lip surface 410 is generally planar for contacting and sealing with the surface 352 of the first rotational member 342. As best seen in FIGS 18 and 19, the lip surface 410 may include two beads 440 for contacting the surface 352 of the first rotational member 342. [0061] As best seen in FIGS. 14 and 16, each fastening portion 390 includes a semi- cylindrical second fastening portion 450 defined, at least in part, by one of the second fastening surface portions 402. Each second fastening portion 450 permits a fastener (not shown) to couple the assembly 330 with the first rotational member 342, generally without interference with cover portion 354. In the embodiment illustrated, each second fastening portion 450 permits a fastener 348 to be rotated as the fastener 348 threads into an aperture within the first rotational member 342.

[0062] A lining 454 is coupled to each of the second fastening surface portions 402. Also in the embodiment illustrated, the lining 454 is formed of the second material 364 and may be integral with the sealing portion 388. As best seen in FIG. 13, when the assembly 330 is fastened to the first rotational member 342, the surface 410 seals with the surface 352 as the sealing portion 388 is at least partially forced toward the direction F, e.g., by first rotational member 342. Adhesive may therefore not be required between the step 426 and the sealing

portion 388, since the sealing portion 388 is coupled to the step 426 by compression when the first rotational member 342 is fastened to the assembly 330.

[0063] As described above, the second coupling region 358b is disposed adjacent the annular face 370, and generally provides a second site for mechanical interlock features for the boot portion 356 adjacent a sealing surface 388 of the boot portion 356. For example, as best seen in FIGS. 17 and 18, the connecting portions 392 also include retention apertures 460 formed between an outer cover surface 462 and the step surfaces 432. During molding, the second material may flow past the groove 436 and out the apertures 460 to form buttons 466. The buttons 466 have a dimension that is greater than the diameter of the apertures 460 to prevent the buttons 466 from being pulled through the apertures 460. Accordingly, the buttons retain the sealing portion 388 on the step surface 432, generally in all three dimensions, i.e., along the longitudinal axis B-B, and in any direction generally perpendicular to longitudinal axis B-B. [0064] The second material 364 may be injected into a mold and permitted to flow to simultaneously form the boot portion 356, the lining 454, the sealing portion 388, and the buttons 466. In the embodiment illustrated, the buttons 466 and the groove 436 reduces the need for an adhesive or other bonding between the cover portion 354 and the sealing portion 388. [0065] FIG. 21 illustrates coupling region 358a in greater detail to include a labyrinth or undulating surface region 470 formed on the cover portion 354. The undulating surface region 470 includes a first generally cylindrical surface 510, a second generally cylindrical surface 508 positioned radially within the first generally cylindrical surface 510 (e.g., with respect to axis B- B of cover portion 354), a third generally cylindrical surface 506, a fourth generally cylindrical surface 504 positioned radially within the third generally cylindrical surface 506, a fifth generally cylindrical surface 502, a sixth generally cylindrical surface 500, a first internal interconnecting surface 516, a second internal interconnecting surface 514, a third internal interconnecting surface 512, a first external interconnecting surface 520, a second external interconnecting surface 518. The surfaces 500, 502, 504, 506, 508, 510, 512, 514, 516, 518, and 520 include generally circular portions (in section) while the surfaces 500, 502, 504, 506, 508, and 510 include generally cylindrical portions. While the undulating surface region 470 is

illustrated with three (3) annular grooves or apertures (at 512, 514, 516), any suitable number of apertures or grooves may be formed in the cover portion 354.

[0066] In an exemplary embodiment of forming the grease cover assembly 330, the cover portion 354 is formed by die-casting a metal (or alloy) or molding a resin. Then, the boot portion 356 is molded onto the cover portion 354 such that each of the surfaces 500, 502, 504, 506, 508, 510, 512, 514, 516, 518, and 520 are in contact with a portion of the second material 364. Further, at least a portion of the second material 364 will flow through the retention apertures 460 and form the buttons 466. A stamping process can form the undulating surface feature 470 when the cover portion 354 is a metal or alloy, especially where the undulating surface feature 470 is relatively simple, e.g. a single groove or surface undulation. In examples where more complex mechanical locking features are desired, e.g., three or more grooves as shown in FIG. 21, a precision forming process, e.g., die-casting, may be preferred. [0067] With the material of the boot portion 356 in contact with the undulating surface region 470, the undulating surface region 470 provides a retaining feature for at least mechanically locking the boot portion 356 to the cover portion 354 to resist at least shear and tensile forces that tend to uncouple the boot portion 356 from the cover portion 354. In contrast, this resistance to shear loading may be provided with an adhesive when no undulating surface portion 470 is provided

[0068] In the embodiment illustrated, the cover portion 354 is a die cast metal with the groove 346 and undulating surface region 470 formed during a die casting process. Any part of a die cast cover portion 354 may be entirely encased in the second material 364 to prevent galvanic corrosion.

[0069] The connection between cover portion 354 and boot portion 356 can be designed to employ shapes that are more resistant to decoupling stresses than the prior art crimped connection. That is, values of stresses caused by extreme operating deflections may be less, at least in coupling regions 358, than that for the crimped connection of boot cover assembly 30. This lower stress connection can better accept greater degrees of articulation and axial movement within a joint, e.g., joint 120.

[0070] FIG. 22 illustrates a further exemplary illustration of a boot cover assembly as a sealing cover assembly 530. The sealing cover assembly 530 includes a metal first portion, or cover portion, 554, a second portion, or boot portion, 556, and two coupling regions 558a, 558b. In the example illustrated, the cover portion 554 is formed of a steel material, and boot portion 556 is formed of a flexible material, such as a rubber material.

[0071] Cover portion 554 includes a first radially extending coupling portion 558a, a radially extending annular face 570 that contours the first rotational member 442, an axially extending cylindrical body 572 that extends between the first rotational member 442 and the first coupling portion 558a, and a generally frusto-conical portion 574 extending between the annular face 570 and the cylindrical body 572. Cover portion 554 further includes an axially extending lip 576 extending from a periphery of the annular face 570. A plurality of retention apertures 578 are formed in the first coupling region 558a.

[0072] Boot portion 556 includes a boot body 580 and an overrnolded portion 582. Overmolded portion 582 includes a sealing portion 588 and a web portion 594 that extends between the sealing portion 588 and the coupling region 558. The sealing portion 588 bindingly contacts the first rotational member 442 to provide a seal between cover portion 554 and first rotational member 442. The second radially extending coupling portion 558b of cover portion 554 is disposed adjacent the radially extending annular face 570 and the sealing portion 588. [0073] In the example illustrated, the web portion 594, the sealing portion 588, the coupling portion 558, and the boot body 580 form a continuous surface 600 of the rubber material to seal grease inside the joint and to provide a barrier between the cover portion 554 and the grease. The coupling regions 558a, b each provide a mechanical lock between the cover portion 554 and the boot portion 556 as the rubber material flows into the retaining apertures 568. In this exemplary illustration, the steel cover portion 554 bonds with the second material sufficiently to eliminate a need for an undulating surface region.

[0074] Additionally, a plurality of retention apertures 592 are formed in the annular face 570 of the cover portion 554. The boot portion extends through the retention apertures 592 to form a button 590. The buttons 590 interface with the retention apertures 592 to provide a mechanical interlock between the cover portion 554 and the boot portion 556 adjacent the annular face 570

of the cover portion 554. Accordingly, the boot portion 556 is stabilized in the vicinity of the annular face 570 of the cover portion 554, thereby reducing or even eliminating any need for an adhesive to further secure the boot portion 556 to the cover portion 554. [0075] The sealing portion 588 extends across the face of the first rotational member 442, to an end portion 576 of the cover portion 554. The sealing portion 588 includes a generally continuous sealing surface about the perimeter of the cover portion 554, and thus seals substantially an entire perimeter of the first rotational member 442. The sealing portion 588 is press-fit between the end portion 576 and the upper surface of the first rotational member 442, such that at least a portion of the sealing portion 588 is in radial compression between the end portion 576 and first rotational member 442. The provision of this radial compression in combination with the mechanical interlock between the cover portion 554 and boot portion 556 adjacent the sealing portion 588 allows the sealing portion 588 to be molded to the cover portion 554 without an adhesive, thereby simplifying assembly and manufacture of the assembly 530. While an adhesive may nonetheless be provided to further increase retention of the sealing portion 588 to the cover portion 554, in the exemplary illustration shown in FIG. 22 the mechanically interlocked relationship between the cover portion 554 and boot portion 556 and the radial compression of the sealing portion 588 by the end portion 576 results in a stable and consistent seal between the cover assembly 530 and the first rotational member 442. Additionally, first rotational member 442 may define an outer surface 579 and a step surface 577 for receiving the cover assembly 530. Accordingly, first rotational member 442 may define a reduced overall packaging diameter, e.g., as defined at least in part by the outer surface 579, while also allowing for an interference fit between the step surface 577 and the cover assembly 530. In other words, the step surface 577 and end portion 576 may cooperated to define an interference fit with the sealing portion 588, thereby enhancing retention of the cover assembly 530 to the first rotational member 442.

[0076] The preceding description has been presented only to illustrate and describe exemplary embodiments of the methods and systems of the present invention. It is not intended to be exhaustive or to limit the invention to any precise form disclosed. It will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for

elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. The invention may be practiced otherwise than is specifically explained and illustrated without departing from its spirit or scope. The scope of the invention is limited solely by the following claims.