CONSTANT VELOCITY JOINTS

Technical Field

The present invention relates to constant velocity (CV) joints generally and more specifically to structures and methods for assembly and disassembly of these joints.

Background Art

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 to enclose and protect the coupling during operation.

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.

Prior art traditional fixed ball joints are generally used with the rear propeller shaft and with the front and rear side shafts in an all-wheel drive vehicle. Specifically, FIG. 1 illustrates a prior art constant velocity joint 20. Joint 20 includes a cylindrical propeller shaft 26 having an annular circumferential groove 30 formed therein, and an outer race 38 which has an integral shaft 40 attached to one end thereof. In one configuration, the shaft 40 connects to a rear differential (not shown). In a second configuration the shaft 40 connects to a transfer case. In a third configuration the shaft 40 connects to a hub wheel on front or rear side shafts (not shown). An inner wall 42 of the outer race 38 generally defines a constant velocity joint chamber 44. An annular inner race 46, having an annular race groove 50 formed therein, is located or housed within the outer race 38. The inner race 46 is connected to the propeller shaft 26 via a splined connection. A ring retainer 48 is located partially within race groove 50

and the shaft groove 30 to axially retain the shaft 26 on the inner race 46. A plurality of balls or rolling elements 52 are located between an outer surface 54 of the inner race 46 and the inner wall 42 of the outer race 38.

A boot 60 has one end connected to an end 62 of the outer race 38. The boot 60, which is generally made of a urethane or thermoplastic, has an opposite end engaging the propeller shaft 26. The boot 60 is held in place about the propeller shaft 26 by a boot clamp (not shown).

The balls 52 are held in position between the outer race 38 and inner race 46 surfaces by a cage 56. Each ball 52 is located within tracks (not shown) of the inner wall 42 of the outer race 38. Further, each ball 52 is located within tracks (not shown) of the inner race 46. Rotation of the shaft 40 and outer race 38 rotates the inner race 46 at a generally constant speed thus allowing for constant velocity to flow through the joint 10 and between the shaft 40 and propeller shaft 26 that is disposed at an angle in relation to the shaft 40.

For a non-collapsing joint 20, shaft 26 typically has a collar 70 formed thereon and/or the splines formed on the shaft may be limited in length to limit the travel of shaft 26 within inner race 46 beyond the illustrated connection configuration where the shaft groove 30 is generally aligned with the race groove 50. Race groove 50 has a frusto-conical surface to allow shaft 26 to be removed from inner race 46. This frusto-conical surface permits retaining ring 48 to be contracted such that retaining ring 48 is positioned within shaft groove 30 and not within race groove 50, thereby eliminating any interference between retaining ring 48 and race groove 50 and permitting shaft 26 to be removed from inner race 46.

While the frusto-conical surface formed on race groove 50 will allow disassembly of joint 20, some operational configurations of joint 20 may result in a force exerted on shaft 26 that tends to pull shaft 26 away from shaft 40. When this force is experienced, retaining ring 48 may be urged by the frusto-conical surface into shaft groove 30 and shaft 26 may undesirably axially translate out of contact with inner race 46. Other operational occurrences may be experienced that tend to result in a force exerted on shaft 26 that tends to push shaft 26 toward shaft 40.

While the constant velocity joint 20 may operate satisfactorily for its intended purpose, constant velocity joints in general are an area of constant innovation. One area for improvement is the assembly and disassembly of the shaft/inner race connection. What is

needed, therefore, is a joint assembly that can be disassembled when desired while reducing the occurrences of an undesired disassembly, such as discussed above.

Disclosure of the Invention

An embodiment of the present invention includes a joint assembly that includes a retaining member, an inner member, and an outer member. The inner member has an inner member groove. The outer member has an outer member groove. The outer member groove and the inner member groove are selectively aligned to permit the retaining member to be at least partially disposed within both the inner member groove and the outer member groove. The retaining member is selectively biased toward at least one of the inner member groove and the outer member groove. The inner member groove and the outer member groove cooperate to urge the retaining member into one of the inner member groove and the outer member groove, thereby permitting the inner member to move in a first direction relative to the outer member. At least one of the inner member groove and the outer member groove includes a surface portion that bindingly engages the retaining member when said inner member is moved in a second direction.

Another embodiment includes a joint that includes a retaining member and a shaft having a shaft groove. The joint also includes a race having a race groove. At least one of the shaft groove and the race groove is defined, at least in part, by a groove chamfer. The shaft is selectively interposed within the race by translating the shaft in a first direction. The retaining member selectively engages both of the shaft groove and the race groove. The retaining member bindingly engages the groove chamfer to selectively restrict movement of the shaft in a second direction.

Yet a further embodiment provides a method of disassembly for a joint assembly. The method includes urging an inner member in a first direction to disengage a retaining member from an engaging surface of an outer member, and removing the inner member from the outer member by urging the inner member in a second direction.

Brief Description of Drawings

The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a partial sectional view of a prior art constant velocity joint.

FIG. 2 is a partial sectional view of a constant velocity joint according to a first embodiment.

FIGS. 3-10 are partial, enlarged sectional views of the embodiment of FIG. 2, not necessarily to scale, with some splines on the inner race omitted for clarity, and illustrated in various configurations during assembly and disassembly.

HG. 11 is a partial sectional view of another embodiment of a constant velocity joint. FIG. 12 is a partial sectional view of another embodiment of an inner race, with some splines omitted for clarity.

Detailed Description

Referring to the drawings, exemplary constant velocity joints are shown. The illustrated constant velocity joints may be fixed constant velocity joints of the monoblock style that may be used in the propeller shaft (prop shaft) or in the front or rear side shaft of a vehicle. It should be noted, however, that any type of constant velocity joints, including without limitation, tripod, fixed tripod, or the like might be used in accordance with the present invention. That is, one of ordinary skill in the art will recognize the advantages realized by embodiments in substantially all types of constant velocity joints, and other connections between two members. Therefore, the invention should not be limited to the illustrated embodiments.

Referring now to FIG. 2, a constant velocity joint 120 is shown according to an embodiment. The illustrated constant velocity joint 120 includes an inner member, or shaft, 126, and an outer race 138 which may have an integral shaft 140 attached to one end thereof. Torque is transmitted between shafts 126, 140. An inner wall 142 of the outer race 138 generally defines a constant velocity joint chamber 144. An outer member, or inner race, 146 is located or housed within the outer race 138. The inner race 146 is connected to the propeller shaft 126 of the vehicle by a ring retainer, or retaining member, 148 located on an inside surface 150 of the inner race 146, as discussed in greater detail below. A plurality of balls or rolling elements 152 are located between an outer surface 154 of the inner race 146 and the inner wall 142 of the outer race 138. A boot 160 has one end connected to an end 162 of the outer race 138.

With combined reference to MCiS. 2-10, the interconnection between shaft 126 and inner race 146 will be discussed in greater detail. Shaft 126 includes a race end 164 with a

plurality of shaft splines 166 formed therein and a retaining surface defining a shaft groove 170 formed circumferentially therein. Each shaft spline 166 extends radially and axially from race end 164. Shaft groove 170 includes a groove chamfer 172, at one axial end of shaft groove 170, a shaft groove step 174 at an opposing axial end of shaft groove 170, and a shaft end chamfer 176. Groove chamfer 172 is preferably a frusto-conical surface formed on shaft 126 at the intersection of shaft groove 170 and race end 164, and may be a non-continuous, segmented surface. Shaft end chamfer is preferably a frusto-conical surface.

Inner race 146 includes a race chamfer 180, a race groove 182, a race step 184, and a plurality of race splines 186 formed therein. Each race spline 186 extends radially and axially from inner race 146. Race groove 182 includes a generally cylindrical race groove inner wall 190, a first wall 192, and a second wall 194. Race splines 186 matingly engage shaft splines 166 to transmit torque therebetween while permitting relative axial movement. In the embodiment illustrated, ring retainer 148 cannot be urged completely into race groove 182 and disengage shaft groove 170 when shaft groove 170 and race groove 182 are aligned (FIGS. 2, 5, and 6). In the embodiment illustrated, the first wall 192, and the second wall 194 are chamfered, preferably defining, at least in part, frusto-conical surfaces.

In the embodiment illustrated, ring retainer 148 is a split ring with a gap between circumferential ends. The circumferential ends of ring retainer 148 can be converged such that the maximum diameter defined by ring retainer 148 is less than the inner diameter defined by the inner race 146. In this manner, ring retainer 148 may be positioned within shaft groove 170 as shaft 126 is interposed through, or moved rectilinearly within, inner race 146. Shaft splines 166 have sufficient axial length L (FIG. 2) to permit shaft 126 to translate through inner race 146 to the extent that the shaft groove step 174 extends through the race step 184 (FIG. 8).

To connect shaft 126 with inner race 146 for retention therein, specific reference is made to FIGS. 3-6. In FIG. 3, πng retainer 148 is positioned within, or engaged with, shaft groove 170. Shaft 126 is then interposed through inner race 146 in a first direction, or m the direction of arrow F. As ring retainer 148 contacts inner race 146, race chamfer 180 urges ring retainer 148 to contract within shaft groove 170. Ring retainer 148 will contract until a diameter defined by ring retainer 148 is generally equal to the diameter defined by the inside surface 150. Ac shaft 126 is further argod in the flist diicctiOxi, δ _^ g roUixior 148 will _s dϊάe along inside surface 150 as ring retainer 148 is biased toward inside surface 150. Ring

retainer 148 will pass within inner race 146 as shaft 126 is inserted into, or interposed within, inner race 146, as best seen in FIG. 4. As shaft 126 is further inserted within inner race 146, shaft groove 170 aligns with race groove 182, and ring retainer 148 expands due to the aforementioned bias to engage, or be at least partially positioned within, race groove 182, as best seen in HG. 5. In this configuration, ring retainer 148 engages both race groove 182 and shaft groove 170 and relative movement between shaft 126 and inner race 146 is restrained at least to a degree.

With specific reference to FIG. 6, when shaft 126 is urged in a second direction, or in the direction of arrow S, groove chamfer 172 urges ring retainer 148 toward race groove 182, and into binding engagement with first wall 192 and inner wall 190 of race groove 182. In this configuration, shaft 126 is restrained from further movement in the second direction relative inner race 146, thus preventing undesired removal of shaft 126 from inner race 146 during operation of joint 120. In the embodiment illustrated, the first direction is generally opposite the second direction along an axis of shaft 126.

To disconnect shaft 126 with inner race 146, shaft 126 is urged in the first direction F, as illustrated in HG. 7. As shaft 126 is urged in the first direction, shaft groove step 174 urges ring retainer 148 to guide along second wall 192 of race groove 182 and contract. As ring retainer 148 contracts, ring retainer 148 moves out of engagement with race groove 182 as the diameter defined by ring retainer 148 reduces to about the diameter defined by inside surface 150 of inner race 146. The second wall 194 of race groove 182 has a chamfer to encourage ring retainer 148 to disengage from race groove 182. In the embodiment illustrated, the second wall 194 is frusto conical to encourage the ring retainer 148 to move out of engagement with the race groove 182. A technician may feel or hear ring retainer 148 disengage from the inner race groove 182 and the starting of relative movement between shaft 126 and inner race 146.

As shaft 126 is moved further in the first direction, ring retainer 148 guides along the inside surface 150 until ring retainer 148 is translated beyond race step 184, as best seen in FIG. 8. Once ring retainer 148 is moved sufficiently to remove any interference between ring retainer 148 and inside surface 150, ring retainer 148 is allowed to expand to an unbiased diameter, or dimension. A technician may feel or hear ring retainer 148 expand to the unbiased diameter.

Shaft 126 may then be urged in the second direction S, as best seen in FIG. 9. When shaft 126 is urged in the second direction, ring retainer 148 will disengage from shaft groove 170 as groove chamfer 172 urges ring retainer 148 to expand, if necessary, as ring retainer 148 is guided radially outwardly along a surface portion of race step 184. In the embodiment illustrated in FIG. 9, ring retainer 148 is selectively biased to a dimension greater than any unbiased dimension. Shaft 126 may be further urged in the second direction, as best seen in FIG. 10, as ring retainer 148 is guided along shaft 126. Additional movement of shaft 126 in the second direction will permit race step 184 to urge ring retainer 148 to guide along shaft 126 and contract as ring retainer 148 encounters the shaft end chamfer 176. Further movement of shaft 126 in the second direction will permit shaft 126 to be removed from contact with inner race 146.

FIG. 11 illustrates an alternative embodiment of the shaft 126 as a shaft 126'. Shaft 126' includes a race end 164' with a plurality of shaft splines 166' formed therein and a shaft groove 170' formed circumferentially therein. Each shaft spline 166' extends radially and axially from race end 164'. Shaft groove 170' includes a segmented frusto-conical groove chamfer 172', at one axial end of shaft groove 170', and a shaft groove step 174' at an opposing axial end of shaft groove 170'. Shaft 126' also includes a retaining surface defining a second shaft groove 200 formed therein. A second retaining member, or clip, 210 is bindingly engaged within second shaft groove 200.

As operational forces urge shaft 126' in the first direction, clip 210 will interfere with inner race 146, thereby preventing further movement of shaft 126' in the first direction. In this manner, clip 210 and the second shaft groove 200 cooperate to prevent undesired disassembly of shaft 126' and inner race 146. The axial distance that separates the shaft groove 170 from the second shaft groove 200 may permit operational forces of joint 120 to disengage ring retainer 148 from race groove 182, but will not allow ring retainer 148 to translate beyond race step 184.

While grooves 170, 182, 200 are preferably formed to extend 360°, grooves 170, 182, 200 need not extend 360° in other embodiments. Additionally, grooves 170, 182, 200 may be continuous grooves or segments or have varying depths and widths with respect to shafts 126, 126' and inner race 146. While shafts 126, 126' and inner race 146 are described as having splined surfaces, other COUDIIπS means or surfaces that allow relati ^v e '"Cation therebetween are also contemplated.

FIG. 12 illustrates an alternative embodiment of the inner race 146 as an inner race 246. The inner race 246 includes a race chamfer 280, a race groove 282, a race step 284, a plurality of race splines 286 formed therein, and a chamfered race step groove 288. Each race spline 286 extends radially and axially from inner race 246. Race groove 282 includes a generally cylindrical race groove inner wall 290, a generally annular first wall 292, and a generally annular second wall 294.

In operation, the shaft 126, 126' (FIG. 8) is moved in the first direction as described above until the ring retainer 148 passes the race step 284. The race step groove 288 guides the ring retainer 148 as ring retainer 148 expands to the unbiased diameter. When the shaft 126 is moved in the second direction S (to remove the shaft 126 (FIG. 9) from the inner race 246), the race step groove 288, which has a diameter about equal to the diameter of an outer portion of the retainer ring 148, will center the ring retainer 148 relative to the inner race 246 as the groove chamfer 172, 172' urges the ring retainer 148 toward the inner race 246. Further movement of the shaft 126 in the second direction results in groove chamfer 172, 172' expanding the ring retainer 148 until the ring retainer 148 will slide over the outer surface of shaft splines 166 of race end 164. The centering ability of the race step groove 288 will reduce instances of shear of ring retainer 148 during disassembly.

While the embodiments have been described with respect to specific examples, including preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and techniques that fall within the spirit and scope of the invention as set forth in the appended claims.