Constant velocity joint, cage therefor, and method of manufacturing the same

Abstract

A constant velocity joint, a cage therefor, and a method of manufacturing the same. The constant velocity joint has an inner race, an outer race disposed about the inner race, a plurality of rolling members disposed for rolling motion between the inner race and the outer race, and a cage disposed between the inner race and the outer race. The cage has a first region of a first hardness and a plurality of second regions of a second hardness, the second hardness being greater than the first hardness.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 868,688, filed August 22, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to axle assemblies for motor vehicles, and more specifically to constant velocity joints for axle assemblies, and particularly to rolling member cages for constant velocity joints. Background Technology

[0004] The demand for constant-velocity joints (CVJs) used in automotive axle joint applications is increasing, requiring low-quality, small-size packaging, high mechanical efficiency, and long lifespan. To improve the mechanical efficiency and lifespan of CVJs, it is known to carburize and temper the entire ball cage to enhance its strength and lifespan, achieving uniform temper hardness throughout, followed by finishing. However, the tempering process ultimately reduces the surface hardness of the entire ball cage, making it more susceptible to various failure modes such as Brinelling and quasi-static fatigue.

[0005] Therefore, a constant velocity coupling is needed to overcome at least the aforementioned disadvantages. Summary of the Invention

[0006] One aspect of this disclosure provides a constant velocity joint having an inner ring, an outer ring disposed around the inner ring, a plurality of rolling members disposed for rolling movement between the inner and outer rings, and a cage disposed between the inner and outer rings. The cage has a first region of a first hardness and a plurality of second regions of a second hardness greater than the first hardness.

[0007] According to a further aspect of this disclosure, a cage for a constant velocity joint is provided. The cage has an annular body having a first region of a first hardness and a plurality of second regions of a second hardness greater than the first hardness.

[0008] According to another aspect of this disclosure, a method for constructing a cage for a constant velocity joint is provided. The method includes: providing an annular body extending about a central axis; forming a plurality of through holes in the annular body; hardening the annular body in a first process; and hardening material extending around at least a portion of each of the plurality of through holes in a second process following the first process.

[0009] These and other aspects, purposes, advantages and features will become apparent to those skilled in the art upon reading the following description in conjunction with the accompanying drawings. Attached Figure Description

[0010] The subject matter considered to be the invention is specifically pointed out and clearly stated in the claims at the end of the specification. The foregoing and other features and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings: Figure 1 This is a front view of a fixed-center constant velocity joint constructed according to one aspect of this disclosure; Figure 2 yes Figure 1 A perspective view of the cage and rolling assembly of a medium-speed joint; Figure 3A It is shown after the first hardening process. Figure 1 A three-dimensional view of the cage frame for a medium-speed joint; Figure 3B It is shown after the second hardening process performed after the first hardening process. Figure 1 A three-dimensional view of the cage frame for a medium-speed joint. Detailed Implementation

[0011] Please refer to the accompanying drawings, in which the invention will be described with reference to specific embodiments without constituting a limitation thereof. Figure 1 A constant velocity joint 10 is shown, comprising an inner ring 12 having opposing inner ring sides, from which a plurality of inner ball rails 14 extend to the other inner ring side. In a non-limiting embodiment, the inner ball rails 14 are shown as grooves (also referred to as slots) extending between opposing sides of the inner ring 12. An outer ring 16 is disposed around the inner ring 12 such that the inner ring 12 and the outer ring 16 extend coaxially about a common central axis 18. The outer ring 16 has opposing outer ring sides, from which a plurality of outer ball rails 20 extend to the other outer ring side. In a non-limiting embodiment, the outer ball rails 20 are shown as grooves (also referred to as slots) extending between opposing sides of the outer ring 16. The inner ball rails 14 and the outer ball rails 20 are radially aligned with each other, and a plurality of rolling elements 22 (shown as spherical balls) are disposed between the inner ring 12 and the outer ring 16 for rolling reception within the inner ball rails 14 and the outer ball rails 20. A rolling element cage (also referred to as a rolling member cage, hereinafter referred to as cage 24) is disposed between the inner ring 12 and the outer ring 16 to facilitate maintaining the rolling members 22 spaced apart from each other and contained between the inner ring 12 and the outer ring 16. The cage 24 has a first region 26 of a first material hardness (also referred to as first hardness) extending along the exposed outer surface 24a of the cage 24; and a plurality of second regions 28 of a second material hardness (also referred to as second hardness), wherein the second hardness is greater than the first hardness.

[0012] In the exemplary non-limiting embodiment shown, each inner ball rail 14 is paired with an outer ball rail 20 to form a ball rail pair. The radius of curvature of each inner ball rail groove may be formed concave or convex, and the radius of curvature of each outer ball rail may be formed concave or convex. In a non-limiting embodiment, the radius of curvature of each inner ball rail groove may be formed concave or convex, and the radius of curvature of each outer ball rail groove may be another concave or convex shape.

[0013] The cage 24 has a plurality of through holes 30 formed between planar opposite sides 32, wherein when the CVJ is in a straight, non-inclined direction, the planar opposite sides 32 are generally parallel to each other and transverse (also referred to as perpendicular) to the central axis 18, and generally transverse to the central axis 18a of the cage 24. A plurality of rolling members 22 are disposed in the through holes 30, which are shown as circumferentially spaced around the cage 24. In the non-limiting example embodiment shown, a single rolling member 22 is disposed in a single through hole 30 such that a single rolling member 22 is received in each through hole 30. The through hole 30 has an outer surface (also referred to as an outer periphery) that defines the boundary of the through hole 30 and defines the shape of the through hole 30. The through hole 30 may be shaped as needed, for example, circular, and in the non-limiting example embodiment shown, the through hole 30 is generally elliptical. Each through hole 30 has an opposite first segment 34 closest to the opposite side 32, the first segment 34 extending generally parallel to the opposite side 32, wherein the first segment 34 of each through hole 30 faces each other in a mirror relationship. Each through-hole 30 also has opposing second segments 36 extending between the first segments 34 in a generally transverse relationship with the first segments 34, wherein the second segments 36 of each through-hole 30 face each other in a mirror relationship. A plurality of second regions 28 of the cage 24 have a second hardness increased relative to a first hardness of the first region 26, extending around at least a portion of each through-hole 30. In the illustrated non-limiting embodiment, the first segment 34 is formed as the second region 28, thereby having an increased second hardness; while the second segment 36 is provided as the first region 26, thereby having a first hardness decreased relative to the hardness of the second region 28. By giving the first segment 34 an increased second hardness, it is possible to withstand the generally parallel parallel to the cage central axis 18a and the X-axis ( ) generated between the rolling member 22 and the first segment 34. Figure 2 A axially extending force Fx is applied to suppress wear and / or deformation of the cage 24 (especially the first section 34), such as true Brinell indentation caused by plastic deformation due to impact loads, and pseudo Brinell indentation caused by wear / polishing due to vibration (as an example and not a limitation).

[0014] The first hardness of the first region 26 is formed by a non-inductively hardened material in a first hardening process. During manufacturing, the annular body 38 with the cage 24 having through holes 30 can be hardened in the first hardening process (e.g., a carburizing heat treatment process, also known as surface hardening), wherein carbon in a carbon-rich atmosphere diffuses into the metal of the body 38 while the body 38 is above the transformation temperature. After the carbon diffuses into the iron-based metal of the body 38, a quenching process is performed to quench the body 38 and rapidly cool it below the transformation temperature, thereby forming a hardened outer surface layer with the first hardness, which is harder than the core of the body 38. Therefore, the entire body 38 at this point has a surface-hardened outer surface layer with the first hardness and a softer core.

[0015] The increased second hardness of the second region 28 is formed by hardening the material extending around at least a portion of each of the plurality of through holes 30 in a second process following the first process. As discussed above, the first section 34 is hardened in a second hardening process (e.g., by induction heat treatment) to form an induction-hardened material throughout the second region 28 forming the first section 34. The second section 36 can retain a relatively low first hardness provided by the first hardening process. Therefore, the first section 34, which bears the maximum load Fx from the rolling member 22 during use, has a greater hardness relative to the second section 36 and the remainder of the body 38, thereby enabling resistance to wear and damage (as discussed above). As a result, the remainder of the body 38, with a relatively low first hardness, exhibits increased toughness and quasi-static fatigue properties. Thus, the cage 24 is provided with a varying hardness material composition, which achieves an optimized combination of toughness through the first hardness throughout the first region 26 and optimized resistance to wear and Brinell indentation (true and false) through the increased second hardness throughout the second region 28 relative to the first hardness.

[0016] According to another aspect of this disclosure, a method for manufacturing a cage 24 for a constant velocity joint 10 is provided. The method includes: providing an annular body 38 extending about a central axis 18a; forming a plurality of through holes 30 in the annular body 38; hardening the annular body 38 in a first process to give the annular body 38 a uniform first hardness; and hardening, in a second process following the first process, a material extending about at least a portion of each of the plurality of through holes 30 to give the subsequently hardened portion (also referred to as a second region 28) a second hardness greater than that of the remainder of the annular body 38 (also referred to as a first region 26).

[0017] The method may further include: performing hardening of the annular body 38 in a first process by a non-inductive hardening process (e.g., a surface hardening process); and performing hardening of the second region 28 in a second process by an inductive hardening process, while not performing inductive hardening on the first region 26.

[0018] The method may further include: providing an annular body 38 having opposing sides 32 extending generally transversely to the central axis 18a; and hardening a first segment 34 of each of the plurality of through holes 30 (which extends adjacently and generally along and is generally parallel to the opposing side 32) during a second process, while not further hardening a second segment 36 of each through hole extending between the first segments 34 during the second process.

[0019] Although the invention has been described in detail with reference to only a limited number of embodiments, it should be readily understood that the invention is not limited to these disclosed embodiments. Rather, the invention may be modified to include any number of variations, alterations, substitutions, or equivalent arrangements not previously described but consistent with the spirit and scope of the invention. Furthermore, while various embodiments of the invention have been described, it should be understood that aspects of the invention may include only some of the embodiments described. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment and are interchangeable and applicable to selected embodiments where applicable, even if not explicitly shown or described. Therefore, the invention should not be considered as limited by the foregoing description.

Claims

1. A constant velocity coupling, comprising: Inner circle; An outer ring, which surrounds the inner ring; Multiple rolling elements are configured to roll between the inner ring and the outer ring; as well as A cage frame is disposed between the inner ring and the outer ring, the cage frame having a first region of first hardness and a plurality of second regions of second hardness, the second hardness being greater than the first hardness.

2. The constant velocity joint of claim 1, wherein the cage has a plurality of through holes, wherein the plurality of rolling members are disposed in the through holes, and the plurality of second regions extend around at least a portion of each of the through holes.

3. The constant velocity joint of claim 2, wherein the cage has planar opposite sides, the plurality of through holes are formed between the opposite sides, each of the plurality of through holes having a first segment closest to the opposite side and a second segment extending between the first segments, wherein the first segment has the second hardness.

4. The constant velocity joint as claimed in claim 3, wherein the second section has the first hardness.

5. The constant velocity joint as claimed in claim 2, wherein the plurality of through holes are equidistant from each other.

6. The constant velocity joint of claim 5, wherein the second hardness of the plurality of second regions is formed by an induction-hardening material.

7. The constant velocity joint of claim 6, wherein the first hardness of the first region is formed by a non-inductively hardened material.

8. The constant velocity joint of claim 7, wherein the first hardness of the first region is formed by a surface-hardening material.

9. The constant velocity connector as claimed in claim 4, wherein the first section of each of the plurality of through holes is a mirror image of each other, and the second section of each of the plurality of through holes is a mirror image of each other.

10. A cage for a constant velocity joint, comprising: The annular body has a first region with a first hardness and a plurality of second regions with a second hardness greater than the first hardness.

11. The cage of claim 10, wherein the cage has a plurality of through holes sized to accommodate rolling members, the plurality of second regions extending around at least a portion of each of the plurality of through holes.

12. The cage frame of claim 11, wherein the cage frame has planar opposite sides, the plurality of through holes are formed between the opposite sides, each of the plurality of through holes having a first segment closest to the opposite side and a second segment extending between the first segments, wherein the first segment has the second hardness.

13. The cage frame of claim 12, wherein the second section has the first rigidity.

14. The cage frame of claim 12, wherein the plurality of through holes are equidistant from each other.

15. The cage of claim 14, wherein the second hardness of the plurality of second regions is formed by an induction-hardening material.

16. The cage of claim 15, wherein the first hardness of the first region is formed of a non-inductively hardened material.

17. The cage of claim 16, wherein the first hardness of the first region is formed by a surface-hardening material.

18. A method of manufacturing a cage for a constant velocity joint, comprising: Provides a ring-shaped body extending around the central axis; Multiple through holes are formed in the annular body; The annular body is hardened in the first process; as well as In a second process following the first process, the material extending around at least a portion of each of the plurality of through holes is hardened.

19. The method of claim 18, further comprising: Provides the annular body having opposite sides that extend generally transversely to the central axis; And a first section of each of the plurality of through holes is hardened during the second process, the first section extending generally parallel to the opposite sides; And during the second process, the second section of each of the plurality of through holes extending between the first sections is not hardened.

20. The method of claim 19, further comprising using an induction hardening process to harden the first segment during the second process.

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