WO2009023869A1

WO2009023869A1 - Mechanical locking feature for joint cover

Info

Publication number: WO2009023869A1
Application number: PCT/US2008/073432
Authority: WO
Inventors: Brian M. Valovick
Original assignee: Gkn Driveline North America, Inc.
Priority date: 2007-08-16
Filing date: 2008-08-18
Publication date: 2009-02-19
Also published as: WO2009023873A1; WO2009026246A1

Abstract

A sealing cover assembly for an articulating joint is disclosed. An articulating joint may include a first rotational member, a second rotational member, and a shaft secured to the second rotational member. A sealing cover assembly may include a first portion selectively coupled to the first rotational member of the articulating joint, and a second portion selectively coupled to the second rotational member of the articulating joint. The first portion includes a retaining feature, and at least a portion of second portion is formed on the retaining feature. The sealing cover assembly further includes a coupling region formed on a surface of the retaining feature that is configured to form a mechanical interlock between the first portion and the second portion when the second portion is formed onto the first portion.

Description

MECHANICAL LOCKING FEATURE FOR JOINT COVER

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 anon-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 24. 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 joints. 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 (not shown) 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 rpm) 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 increase reliability.

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 an exemplary illustration of the present invention;

[0015] FIG. 4 is an enlarged sectional view of the boot cover assembly of FIG. 3; [0016] FIG. 4A is an enlarged view of a encircled area 4A taken from FIG. 4; [0017] FIG. 4B is an enlarged view of a portion of encircled area 4B taken from FIG. 4; [0018] FIG. 5 is an enlarged partial sectional view the boot cover assembly of FIG. 4; [0019] FIG. 5 A is an enlarged view of a portion of encircled area 5 A taken from FIG. 5 ; [0020] FIG. 6 is an enlarged partial sectional view of an exemplary illustration of a boot cover assembly; [0021] FIG. 7 is a sectional view of another example of a boot cover assembly; [0022] FIG. 8 is an enlarged partial sectional view of another exemplary illustration of a boot cover assembly for use in a joint assembly;

[0023] FIG. 8 A is an enlarged view of a portion of encircled area 8 A taken from FIG. 8;

[0024] FIG. 8B is an enlarged view of a portion of encircled area 8B taken from FIG. 8;

[0025] FIG. 8C is an enlarged view of FIG. 8 A;

[0026] FIG. 9 is a partial perspective view of a portion of the boot cover assembly of

FIG. 8;

[0027] FIG. 10 is a sectional view of another exemplary illustration of a boot cover assembly for use in a joint assembly;

[0028] FIG. 11 is a sectional view of another exemplary illustration of a cover portion for use in a joint assembly; and

[0029] FIG. 12 is an enlarged view of the cover portion illustrated in FIG. 11.

Detailed Description

[0030] Various exemplary illustrations of an articulating joint and a sealing cover assembly therefor, and methods of making a sealing cover assembly for an articulating joint, are disclosed herein. An articulating joint may include a first rotational member, a second rotational member, and a shaft secured to the second rotational member. A sealing cover assembly may include a first portion selectively coupled to the first rotational member of the articulating joint, and a second portion selectively coupled to the second rotational member of the articulating joint. The first portion includes a retaining feature, and at least a portion of second portion is formed on the retaining feature. The sealing cover assembly further includes a coupling region formed on a surface of the retaining feature that is configured to form a mechanical interlock between the first portion and the second portion when the second portion is formed onto the first portion.

[0031] A method of making a sealing cover for an articulating joint may include forming a first portion for selectively coupling to a first rotational member of the articulating joint, and forming a second portion for selectively coupling to the second rotational member. The first portion includes a first side and a second side, and forming the first portion includes forming a retention feature. The second portion is formed on and mechanically interlocked with the retention feature of the first portion.

[0032] Turning now to FIG. 3, an articulating joint 120 is illustrated 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 cap assembly or 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.

[0033] FIGS. 4, 4A₅ 4B, 5, and 5A illustrate boot cover assembly 130 in greater detail. Boot cover assembly 130 serves to protect moving parts of joint 120. However, unlike prior art boot cover assemblies, boot cover assembly 130 does not include a traditional metal cover. Instead, boot cover assembly 130 includes a first portion or cover portion 154, a second portion or boot portion 156, and a coupling region 158.

[0034] Coupling region 158 may include a retaining feature that is configured to form a mechanical interlock between the cover portion 154 and the boot portion 156, in any variety of ways, as 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. [0035] As another example of a retaining feature that forms a mechanical interlock 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.

[0036] With attention to FIG. 3 , cover portion 154 may be formed of a first material 162, and boot portion 156 may be formed of a second material 164, as discussed below. Coupling region 158, while illustrated by a line in FIGS. 3-5, is preferably a region containing both the cover and boot portions 154, 156. In examples where the cover and boot portions 154, 156 are formed of different materials, coupling region 158 may exhibit both a chemical and/or physical bonding therebetween (as best seen in FIG. 5A). The bonding of the two materials, as shown in FIG. 5A, generally results in an irregular border between the two materials, such that the bonding occurs over irregular surfaces that resist forces tending to separate the boot and cover portions 154, 156 in shear, tension, or compression. FIGS. 3-5 also illustrate a sealing portion 160 formed on at least a portion of cover portion 154. Sealing portion 160 is preferably formed of a flexible material that ensures a seal between cover portion 154 and first rotational member 142.

[0037] Cover portion 154 has a radially extending annular face 170 that abuts the first rotational member 142, and an axially extending 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. 3) that is defined by the distance that cover portion 154 extends from the first rotational member 142 to the coupling region 158. As shown, axial length L2 of boot cover assembly 130 is shorter than axial length Ll (see FIG. 1) of boot cover assembly 30.

[0038] Cover portion 154 further includes an axially extending lip 174 (FIG. 4) that may incorporate a retention bead 176 (as best seen in FIG. 4A). Retention bead 176 may be positioned within a circular groove (not shown) of first rotational member 142 to provide a more effective seal between cover portion 154 and first rotational member 142. Cover portion 154 may be secured to first rotational member 142 via a press-fit connection between the first rotational member 142 and retention bead 176. Alternatively or in addition to the press-fit connection, cover portion 154 may be provided with apertures 180, as also shown in FIG. 4, to receive fasteners (not shown) to secure cover portion 154 directly to first rotational member 142. Cover portion 154 may incorporate an integrated seal 178 (as best seen in FIG. 4B) extending therefrom. Integrated seal 178 includes a raised annular portion or bead 184 that may generally seal about any apertures in first rotational member 142, in examples where the cover portion 154 is secured to the first rotational member 142 with mechanical fasteners (not shown). Integrated seal 178 may be secured to the cover portion 154 with an adhesive or bonding agent if desired. Where a boot portion, e.g., boot portion 156, is molded onto a cover portion, e.g., cover portion 154, such adhesives or bonding agents may be applied prior to the forming of the boot portion 156. The molding process generally heats the adhesive or bonding agent, activating the adhesive, and further securing the boot portion 156 to the cover portion 154.

[0039] Boot cover assembly 130 may be formed by injection molding. During the molding process for boot cover assembly 130, a mold (not shown) may be prepared for a two-shot injection. Boot cover assembly 130 may be molded in a single process that includes introduction of at least the first material 162 and the second material 164. The mold includes a cover region and a boot region. Boot cover assembly 130 may be molded in the shape illustrated in FIGS. 3-5, as the first material is injected into the cover region and the second material injected into the boot region. The molded boot cover assembly is then allowed to cure, thereby forming the boot cover assembly 130.

[0040] In examples where the boot and cover portions 154, 156 are formed of different materials, a first material 162 that is used for cover portion 156 is preferably a relatively rigid material. For example, first material 162 may be selected from the family of thermoplastic polyester resins, specifically polybutylene terephthalate (PBT) and polyethylene terephthalate (PET) or may be a thermoplastic vulcinizates (TPV) or a nylon or nylon blend. First material 162 may also be a resin and a filler to increase rigidity and strength. Also preferably, first material 162 has hardness values in the range of about 70 to about 150 Rockwell R, about 40 to about 140 Rockwell M, or greater than about 70 Shore D. While fillers such as carbon fiber and glass fibers are preferred, other fillers compatible with the contemplated resins could also be used.

[0041] The cover portion 154 may be formed of a second material 164 that is flexible in comparison to at least first material 162, and may be plastic or any elastomer, such as rubber, silicone, or thermoplastic elastomer (TPE), as examples. 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.

[0042] Sealing portion 160 provides for a more reliable seal between cover portion 154 and first rotational member 142. Sealing portion 160 and retention bead 176 are preferably formed of a sealing material such as flexible thermoplastic and may be formed of the same material as the second material 164. Sealing portion 160, retention bead 176, and integrated seal 178 are preferably formed during the molding process by injecting the sealing material into the mold, although other processes, including overmolding or welding, may be used. Preferably, sealing portion 160 is about 2-3 millimeters in thickness. When fasteners are inserted through apertures 180 to fasten cover portion 154 to first rotational member 142, integrated seal 178 is desirably in compression and exerting a force on first rotational member, thereby providing a positive seal therebetween.

[0043] The pressures induced by the molding process ensures that the coupling region 158 provides a reliable bond between cover portion 154 and boot portion 156. The pressures of the molding process and the flow of resins (first material 162, second material 164) in the mold provide for a coupling region 158 that is both a chemical bond, as well as a physical bond (as best illustrated in FIG. 5A). The chemical bond may be cross-linked. The coupling region 158 forms a bond between cover portion 154 and boot portion 156 that is selectively in shear, compression and tension during operation of joint 120. These shear, compressive, and tensile forces are the result of at least deflection within boot cover assembly 130 due to torsional and rotational movement of joint 120.

[0044] The connection between cover portion 154 and boot portion 156 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 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 joint 120. [0045] In addition, in accordance with one aspect of the invention, the first material 162 of cover portion 154 is 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. Additionally, since axial length L2 of boot cover assembly 130 is shorter than axial length Ll of boot cover assembly 30, the shaft 128 may be shorter than the prior art shaft 28. A shorter shaft 128 may contribute to a reduced rotational weight of joint 120. Furthermore, a reduced axial length L2 will allow articulation within joint 120 of a greater angle before the shaft 128 contacts the boot cover assembly 130. However, the shorter length L2 preferably also allows for a significant length of section 156 to minimize tension stress that may occur at larger angles. ELEMENT No. 186

[0046] FIG. 6 illustrates an alternate embodiment of a boot cover assembly 230. Boot cover assembly 230 is intended for a similar application as boot cover assembly 130 and includes an axially extending portion 272 that includes a first portion 254, a second portion 256, and a coupling portion 258. Coupling portion 258 provides a connection between first portion 254 and second portion 256. First portion 254 is formed of a first material 262, and second portion 256 is formed of a second material 264. Second portion 256 includes a sealing portion or bead 260 that seals against a first rotational member (not shown in FIG. 6) of an articulating joint. Preferably, first portion 254 and second portion 256 are molded onto coupling portion 258. In one embodiment, first portion 254 and second portion 256 are simultaneously molded onto the coupling portion 258. An adhesive or bonding agent may be applied to further secure coupling portion 258 to the first and second portions 254, 256. While coupling portion 258 may be a stainless steel band with a phosphate coating, coupling portion 258 may be constructed of other metals and other coatings, or other suitable materials. Also, coupling portion 258 is not limited to the shape illustrated in the embodiment of FIG. 6, but may be any suitable shape. Element No. 272 [0047] FIG. 7 illustrates another alternate embodiment of a boot cover assembly 330. Boot cover assembly 330 may be used for a fixed joint where an internal rolling diaphragm is not desired. Boot cover assembly 330 includes a first portion 354, a second portion 356, and a coupling portion 358. First portion 354 is formed of a first material 362, and second portion 356 is formed of a second material 364. Coupling portion 358 provides a structural connection between first portion 354 and second portion 356. Preferably, first portion 354 and second portion 356 are molded onto coupling portion 358. hi one embodiment, first portion 354 and second portion 356 are simultaneously molded onto the coupling portion 358, as discussed below. Coupling portion 358 is preferably constructed of the same material as coupling portion 258.

[0048] First material 262, 362 is preferably a relatively rigid material, and may be selected from the family of thermoplastic polyester resins, specifically polybutylene terephthalate (PBT) and polyethylene terephthalate (PET). First material 262, 362 forms a strong bond when molded to a metallic coupling portion 258, 358, especially when coupling portion 258, 358 is provided with a phosphate coating. Alternatively, first portion 254, 354 may be molded of 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.

[0049] Second material 264, 364 is preferably a flexible material, and may be plastic or any elastomer, such as rubber, silicone, or thermoplastic elastomer (TPE). Second material 264, 364 also forms a strong bond when molded to a metallic coupling portion 258, 358, especially when coupling portion 258, 358 is provided with a phosphate coating. Sealing portion 260 is preferably formed in a similar manner as sealing portion 160. [0050] Turning now to FIG. 8, another example of a boot cover assembly 130 or sealing cover assembly 430 is illustrated. The sealing cover assembly 430 includes a first portion, or cover portion, 454, a second portion, or boot portion, 456, and a coupling region 458. FIG. 9 illustrates the cover portion 454, with the boot portion 456 removed for clarity. As shown in FIGS. 8, 8A, 8B, and 9, coupling region may include various types of mechanical interlock regions for the cover and boot portions, such as an undulating surface region and apertures, each as described further below.

[0051] Cover portion 454 is formed of a first material 462, and boot portion 456 is formed of a second material 464, and first and second materials 462, 464 may be different materials, as discussed below. In one example, coupling region 458, best illustrated in FIG. 8, is a region containing both the first material 462 and the second material 464 that exhibits a physical bonding therebetween. However, coupling region 458 may also exhibit a chemical bonding therebetween. The physical bonding is due, at least in part, to a retaining feature, illustrated as a generally undulating surface portion 466 formed on the cover portion 454. Undulating surface portion 466 may be formed, e.g., in a stamping process, especially as may be convenient for simpler shapes, e.g., a single valley or bead. Where a more complex undulating surface portion 466 is desired, e.g., with a number of surface undulations, valleys, beads, etc., undulating surface portion 466 may be more reliably formed in a precision molding or casting process. FIG. 8 also illustrates a retaining aperture 468 formed in at least a portion of cover portion 454, while a plurality of retaining apertures 468 are preferably formed in the cover portion 454, as seen in greater detail in FIG. 9. As illustrated in the exemplary illustration of FIGS. 8 and 9, the retaining apertures 468 have the second material 464 extending therein, as discussed in greater detail below.

[0052] FIG. 8C illustrates one of the coupling regions 458 in greater detail to include a labyrinth or undulating surface region 466 formed on the cover portion 454. The undulating surface region 466 includes a first generally cylindrical surface 710, and a second generally cylindrical surface 708 positioned radially within the first generally cylindrical surface 710 with respect to the longitudinal axis of the cover portion 454, e.g., axis X-X in FIG. 9. The undulating surface region 466 may further include, a third generally cylindrical surface 706, a fourth generally cylindrical surface 704 positioned radially within the third generally cylindrical surface 704, a fifth generally cylindrical surface 702, a sixth generally cylindrical surface 700, a first internal interconnecting surface 716, a second internal interconnecting surface 714, a third internal interconnecting surface 712, a first external interconnecting surface 720, a second external interconnecting surface 718. The surfaces 700, 702, 704, 706, 708, 710, 712, 714, 716, 718, and 720 include generally circular portions (in section) while the surfaces 700, 702, 704, 706, 708, and 710 include generally cylindrical portions. While the undulating surface region 466 is illustrated with three (3) annular grooves (at 712, 714, 716), any suitable number of grooves or apertures may be formed in the cover portion 454. [0053] In an exemplary embodiment of forming the grease cover assembly 430, the cover portion 454 is formed by die-casting a metal (or alloy) or molding a resin. Then, the boot portion 456 is molded onto the cover portion 454 such that each of the surfaces 700, 702, 704, 706, 708, 710, 712, 714, 716, 718, and 720 are in contact with a portion of the second material 464. Further, at least a portion of the second material 464 will flow through the retention apertures 468. In the example shown in FIG. 8C, a precision forming process, e.g., die casting, may be used to form the undulating surface region 466. A stamping process can form the undulating surface feature 466 when the cover portion 454 is a metal or alloy, inasmuch as a stamping process may reliably produce the undulating surface feature 466. In other words, a stamping process may be desirable where undulating surface region 466 includes relatively simple features, e.g., only one or two surface undulations. [0054] 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

[0055] 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.

[0056] Cover portion 454 has a radially extending annular face 470 that contours a first rotational member 442 of a constant velocity joint (not shown), and an axially extending cylindrical body 472 that extends between the first rotational member 442 and the coupling region 458, and a generally frusto-conical portion 474 extending between the annular face 470 and the cylindrical body 472. Cover portion 454 further includes a lip 476 extending from a periphery of the annular face 470. The lip 476 may include a plurality of lip apertures 478 that extend through the lip 476 generally parallel to the axis of the cover portion 454. The lip apertures 478 and the retaining apertures 468 are formed generally in axial alignment with the cover portion 454 to permit the cover portion to be formed in a single stamping operation where the cover portion 454 is formed in the shape as illustrated in FIG. 9 while the apertures 468, 478 are punched.

[0057] Boot portion 456 includes a boot body 480 and an overmolded portion 482. Overmolded portion 482 includes a retention bead 486 that extends from the lip 476. The overmolded portion 482 is interposed within the apertures 478 and also includes a sealing portion 488 that is illustrated to include two concentric sealing beads 490, and a web portion 494 that extends between the sealing portion 488 and the coupling region 458. The sealing portion 488 bindingly contacts the first rotational member 442 to provide a seal between cover portion 454 and first rotational member 442.

[0058] In the example illustrated, the web portion 494, the sealing portion 488, the coupling portion 458, and the boot body 480 form a continuous surface 500 of the second material 464 to seal grease inside the joint and to provide a barrier between the cover portion 454 and the grease. Additionally, the sealing cover assembly includes a reinforcing insert, or sleeve, 510 to prevent overcompression of the second material 464. That is, the reinforcing insert 510 may reduce peak stress concentrations within the first portion at a fastener interface. Accordingly, a mechanical fastener (not shown) used to secure cover portion 454 may be received in an aperture 511 defined by the insert 510 to allow securement to an aperture 443 in the first rotational member 442, and will not impinge upon the relatively softer material from which the cover portion 454 is primarily formed. Further, compression of cover portion 454 caused by mechanical fasteners used to secure the cover portion 454 may be more easily controlled, owing to the stronger material characteristics, e.g., steel, of the insert 510. Additionally, reinforcing insert 510 may provide a generally controlled compression of a gasket or seal provided by the second material 464, especially where the sealing cover assembly employs a non-traditional first material such as a plastic or nylon material. In other words, the reinforcing insert 510 generally reduces peak stress concentrations within the cover portion 454 at the fastener interface in which the reinforcing insert 510 is disposed, thereby limiting a compression of the boot portion 456 or any portion thereof, which may be formed of a softer material, against any part of the articulating joint, e.g., the first rotational member 442. [0059] In the example illustrated, boot cover assembly 430 is be formed by injection molding the cover portion 454, and then overmolding the boot portion 456 thereon. The coupling region 458 provides a mechanical lock between the cover portion 454 and the boot portion 456 as the second material flows into the retaining apertures 468 and around the undulating surface region 466.

[0060] In examples where the boot and cover portions are formed of different materials, first material 462 may be a relatively rigid material, and may be selected from the family of steels, or other metals, thermoplastic polyester resins, specifically polybutylene terephthalate (PBT) and polyethylene terephthalate (PET) or may be a thermoplastic vulcinizates (TPV) or a nylon or nylon blend. First material 462 may also be a resin and a filler to increase rigidity and strength. Also preferably, first material 462 has hardness values in the range of about 70 to about 450 Rockwell R, about 40 to about 440 Rockwell M, or greater than about 70 Shore D. While fillers such as carbon fiber and glass fibers are preferred, other fillers compatible with the contemplated resins could also be used. Alternatively, the first material may be a die cast metal 462, a magnesium, aluminum, or other die cast material, or any other material that is convenient. An adhesive that is activated during the molding process, e.g., an oven molding process, may be used either with or without retaining apertures, as desired. These adhesives may further assure a maximum level of retention and sealing of features provided in the second material and/or boot portion.

[0061] Second material 464 may be formed of a material that is relatively flexible in comparison to at least the first material 462, and may be plastic or any elastomer, such as rubber, silicone, or thermoplastic elastomer (TPE). In these examples, second material 464 preferably 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 430 environment are relatively rigid thermoplastic polyesters for first material 462, and thermoplastic polyester elastomers for second material 464 due to the desirable bonding formed in coupling region 458. Any other materials that are convenient may be employed.

[0062] As with the connection between cover portion 154 and boot portion 156 described above, the connection between cover portion 454 and boot portion 456 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 than for the crimped connection of boot cover assembly 30. This lower stress connection can better accept greater degrees of articulation and axial movement within an articulating joint. [0063] FIG. 10 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 a coupling region 558. 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 the second material 464 of boot cover assembly 430. The cover portion 554 is similar to the cover portion 454 of boot cover assembly 430, with at least the exception that no undulating surface region 466 is provided. [0064] Cover portion 554 includes a radially extending coupling portion 566, a radially extending annular face 570 that contours the first rotational member 442, and an axially extending cylindrical body 572 that extends between the first rotational member 442 and the coupling portion 566, 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 568 may be formed in the coupling portion 566.

[0065] Boot portion 556 includes a boot body 580 and an overmolded portion 582. The overmolded portion 582 also includes a sealing portion 588 that is illustrated to include two concentric sealing beads 590, 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.

[0066] 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 second material 464 to seal grease inside the joint and to provide a barrier between the cover portion 554 and the grease. The coupling region 558 provides a mechanical lock between the cover portion 554 and the boot portion 556 as the second material 464 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. The sealing portion 588 may be bonded to frusto-conical portion 574 during a molding process step, e.g., with an adhesive or bonding agent, to further secure sealing portion 588 to the cover portion 554. Further, any mechanical locking features, e.g., apertures, undulating surface regions, such as those described herein, or the like, may be employed to provide further stability of the boot portion 556, as an alternative or in addition to the use of adhesives or bonding agents. [0067] Turning now to FIGS. 11 and 12, another exemplary illustration of a cover portion 654 is shown that is formed of a plastic, e.g., nylon, material. Cover portion 654 is generally similar to cover portion 454 described above in regard to FIG. 9, and includes like features as described above, the like features indicated by reference characters having the same last two numbers, e.g., the retention apertures 668 shown in FIG. 11 are generally identical to the retention apertures 468 described above in regard to FIG. 9. Further, cover portion 654 is provided with a support insert assembly 690, which performs a similar function as that described above in regard to reinforcing insert 510. Support insert assembly 690 may be especially useful where cover portion 654 is desired to be secured to a first rotational member via a plurality of mechanical fasteners disposed about a perimeter of cover portion 654. Support insert assembly 690 generally is formed of a relatively strong material, e.g., steel, that has a greater capacity for supporting load exerted upon cover portion 654 by mechanical fasteners securing the cover portion 654 to the first rotational member 142, at least as compared with the nylon or other softer material from which the cover portion 654 is primarily formed. For example, support insert assembly may be formed of a steel material, and may generally extend entirely through a depth of cover portion 654. Accordingly, a mechanical fastener (not shown in FIGS. 11-12) used to secure cover portion 654 will generally engage only the support insert 690, and will not impinge upon any relatively softer materials from which the cover portion 654 may be formed. Further, compression of cover portion 654 and/or support insert assembly 690 caused by mechanical fasteners used to secure the cover portion 654 may be more easily controlled. In other words, as with insert 510, support insert assembly 690 may provide a generally controlled compression of relatively softer components of a sealing cover assembly, especially where the sealing cover assembly employs a non-traditional cover material such as a plastic or nylon material. Support insert 690 may thereby generally reduce a tendency of the cover portion 654 to crack under forces exerted upon cover portion 654. Support insert 690 may be integrally molded within cover portion 654, or may be assembled as part of the cover portion 654 in any other way that is convenient.

[0068] The preceding description has been presented only to illustrate and describe exemplary illustrations 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 exemplary illustrations disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all examples 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.

Claims

ClaimsWhat is claimed is:

1. A sealing cover assembly for an articulating joint, the articulating joint including a first rotational member, a second rotational member, and a shaft secured to the second rotational member, the sealing cover assembly comprising: a first portion selectively coupled to the first rotational member of the articulating joint, the first portion having a retaining feature; a second portion selectively coupled to the second rotational member of the articulating joint, wherein at least a portion of the second portion is formed on the retaining feature; and a coupling region formed on a surface of the retaining feature, the coupling region configured to form a mechanical interlock between the first portion and the second portion when the second portion is formed onto the first portion.

2. The sealing cover assembly of claim 1, wherein the retaining feature includes an undulating surface region.

3. The sealing cover assembly of claim 2, wherein at least a portion of the coupling region is coupled to the second portion after the forming of the first portion.

4. The sealing cover assembly of claim 2, wherein the undulating surface region includes a first generally cylindrical surface and a second generally cylindrical surface positioned radially within the first generally cylindrical surface.

5. The sealing cover assembly of claim 4, wherein the undulating surface region includes a third generally cylindrical surface and a fourth generally cylindrical surface positioned radially within the third generally cylindrical surface.

6. The sealing cover assembly of claim 1, wherein the retaining feature includes a plurality of retaining apertures formed in the first portion, the second portion received in the retaining apertures.

7. The sealing cover assembly of claim 1 , wherein at least a portion of the second portion is molded onto at least a portion of the first portion.

8. The sealing cover assembly of claim 1, further comprising a bead formed in the second portion and positioned between the first portion and the first rotational member.

9. The sealing cover assembly of claim 8, wherein the bead includes a plurality of concentric bead portions for contacting the first rotational member.

10. The sealing cover assembly of claim 1, wherein the first portion is formed of a first material, and the second portion is formed of a second material different from said first material.

11. The sealing cover assembly of claim 10, wherein the second material is selected from the group consisting of a thermoplastic elastomer, rubber, and silicone.

12. The sealing cover assembly of claim 11 , wherein the first material is selected from the group consisting of steel, PBT, PET, and filled polyester resins.

13. The sealing cover assembly of claim 11, further comprising a reinforcing insert coupled to at least a portion of the first portion, wherein the reinforcing insert limits a compression of the second portion against the articulating joint.

14. The sealing cover assembly of claim 1, further comprising a reinforcing insert coupled to at least a portion of the first portion, wherein the reinforcing insert reduces peak stress concentrations within the first portion at a fastener interface by limiting a compression of the first portion.

15. An articulating joint, comprising: a first rotational member; a second rotational member coupled to the first rotational member for rotation therewith; a shaft coupled to the second rotational member for rotation therewith; and a sealing cover assembly, including: a first portion selectively coupled to the first rotational member, the first portion having a retaining feature; a second portion selectively coupled to the second rotational member, wherein at least a portion of the second portion is molded on to the retaining feature; and a coupling region formed on a surface of the retaining feature, the coupling region configured to form a mechanical interlock between the first portion and the second portion when the second portion is formed onto the first portion.

16. The articulating joint of claim 15, wherein the retaining feature includes an undulating surface region.

17. The articulating joint of claim 16, wherein at least a portion of the coupling region is coupled to the second portion after the forming of the first portion.

18. The articulating joint of claim 16, wherein the undulating surface region includes a first generally cylindrical surface and a second generally cylindrical surface positioned radially within the first generally cylindrical surface.

19. The articulating joint of claim 18, wherein the undulating surface region includes a third generally cylindrical surface and a fourth generally cylindrical surface positioned radially within the third generally cylindrical surface.

20. The articulating joint of claim 15, wherein the retaining feature includes a plurality of retaining apertures formed in the first portion, the second portion received in the retaining apertures.

21. The articulating joint of claim 15, further comprising a bead formed in the second portion and positioned between the first portion and the first rotational member for contacting the first rotational member.

22. The articulating joint of claim 15, wherein the first portion is formed of a first material, and the second portion is formed of a second material different from said first material.