Ball spline shaft without ball retainer

Abstract

This application relates to a ball spline shaft without a ball retainer. A shaft assembly for transmitting torque in a transmission system is provided. The shaft assembly includes an outer shaft member extending along an axis and including an inner surface defining a bore and a plurality of outer recesses at least partially defining the bore. An inner shaft member extends along the axis and includes an outer surface defining a plurality of inner recesses or at least one of the plurality of inner recesses aligned with the outer recesses. At least one rolling element is positioned between the outer recesses and the inner recesses or between the outer recesses and the inner recesses. At least one of the outer surface of the inner shaft member or the inner surface of the outer shaft member is configured to axially retain at least one rolling element, and the shaft assembly does not include a ball retainer.

Description

Technical Field

[0001] This invention generally relates to a shaft assembly for transmitting torque. More specifically, this invention relates to a telescopic shaft assembly for transmitting torque in a transmission system. Background Technology

[0002] Vehicles (such as automobiles, trucks, SUVs, crossovers, minivans, boats, aircraft, all-terrain vehicles, recreational vehicles, or other suitable vehicles) typically include a drivetrain for transmitting power from an engine or other propulsion system to the wheels. The drivetrain typically includes a telescopic axle assembly capable of transmitting torque. The telescopic axle assembly typically comprises a tubular outer axle member and an inner axle member. The inner axle member is at least partially disposed within the outer axle member and is movable relative to the outer axle member along a longitudinal axis. The telescopic axle assembly typically uses rolling elements or bearings between the outer and inner axle members to reduce friction during repeated expansion, contraction, and compression.

[0003] The rolling elements of a telescopic shaft assembly are typically constructed as steel rollers or steel balls. The rolling elements are configured to roll between the outer and inner shaft members during the linear telescopic movement of the telescopic shaft assembly, while rotational torque can continue to be transmitted between the outer and inner shaft members.

[0004] A telescopic shaft configured to connect two constant-velocity joints is known. This configuration typically includes a bearing cage positioned between an outer and an inner shaft, which holds rolling elements. The bearing cage is typically positioned between the outer and inner shafts via retaining elements. While telescopic shafts with bearing cages are popular, they are not without drawbacks. For example, additional packaging space is typically required to position the ball cage between the outer and inner shafts. The presence of the ball cage also often creates a hydraulic effect, adversely affecting free relative telescopic movement.

[0005] Therefore, there is a desire to continue improving the operating mechanism and efficiency of telescopic shafts in transmission systems to provide extended service life, reduced hydraulic effects, fewer parts, and reduced packaging requirements. Summary of the Invention

[0006] This section provides a general overview of the disclosure and should not be construed as a complete and comprehensive enumeration of all objectives, aspects, features and advantages relating to the disclosure.

[0007] This disclosure generally relates to a shaft assembly without a ball cage, which improves the operating mechanism of a telescopic shaft in a drive system to provide extended operating life, reduced hydraulic effects, fewer parts, and reduced packaging requirements.

[0008] One aspect of this disclosure is to provide a shaft assembly for transmitting torque. The shaft assembly includes an outer shaft member extending along an axis and including an inner surface defining a bore and a plurality of outer recesses at least partially defining the bore. An inner shaft member extends along the axis and includes an outer surface defining at least one of a plurality of inner recesses or inner pockets aligned with the outer recesses. At least one rolling element is positioned between an outer recess and an inner pocket, or between two outer recesses. At least one of the outer surface of the inner shaft member or the inner surface of the outer shaft member is configured to axially retain at least one rolling element, and the shaft assembly does not include a cage.

[0009] Another aspect of this disclosure is a method of assembling a shaft assembly for transmitting torque. The method includes providing an outer shaft member, an inner shaft member, and a sleeve that define a bore. The method further includes aligning a first end of the sleeve with the bore and aligning a second end of the sleeve with the inner shaft member. The sleeve includes a tapered section and a straight section. The method further includes positioning a first portion of the inner shaft member in the tapered section and placing a first circumferentially arrayed rolling element within one of an inner pocket or inner groove defined by an outer surface of the first portion of the inner shaft member. The method further includes positioning the first portion and the first circumferentially arrayed rolling element through the tapered section of the sleeve and into the straight section.

[0010] The features and technical advantages of the invention have been outlined quite extensively above to facilitate a better understanding of the following detailed description. Additional features and advantages of the invention that form the subject matter of the claims will now be described. Those skilled in the art will understand that the disclosed concepts and specific embodiments can be readily used as a basis for modifying or designing other embodiments to achieve the same objectives of the invention. Those skilled in the art will also recognize that such equivalent embodiments do not depart from the spirit and scope of the invention as set forth in the appended claims. These and other aspects of this disclosure are disclosed in the following detailed description of embodiments, the appended claims, and the accompanying drawings. Attached Figure Description

[0011] This disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be emphasized that, by convention, the various features on the drawings are not drawn to scale. Instead, for clarity, the dimensions of the various features have been arbitrarily enlarged or reduced.

[0012] Figure 1 It is a perspective view of a shaft assembly including an inner shaft member and an outer shaft member according to the principles of this disclosure, wherein the outer shaft member is shown as transparent to show the features of the inner shaft member.

[0013] Figure 2 It is a perspective view of the inner shaft component based on the principles of this disclosure.

[0014] Figure 3It is a perspective view of the outer shaft component based on the principles of this disclosure.

[0015] Figure 4 This is a perspective view of another embodiment of a shaft assembly based on the principles of this disclosure.

[0016] Figure 5 This is a plan view illustrating the sequential steps in a method for assembling a shaft assembly according to the principles of this disclosure.

[0017] Figure 6 This is a flowchart illustrating the method of assembling a shaft assembly in accordance with the principles of this disclosure. Detailed Implementation

[0018] Example embodiments will now be described more fully with reference to the accompanying drawings. Generally, this disclosure relates to telescopic shaft assemblies for transmitting torque in a drive system. However, example embodiments are provided only to make this disclosure more detailed and to fully convey the scope to those skilled in the art. Numerous specific details, such as examples of particular components, apparatuses, and methods, are set forth to provide a thorough understanding of embodiments of this disclosure. It will be apparent to those skilled in the art that the use of specific details is not necessary, that example embodiments may be embodied in many different forms, and that neither should be construed as limiting the scope of this disclosure. In some example embodiments, well-known processes, well-known apparatus structures, and well-known technologies are not described in detail.

[0019] Referring to the accompanying drawings, in which the same numerals denote corresponding components throughout the drawings, a ball spline shaft "shaft assembly" without a ball retainer and an assembly method are provided. This shaft assembly and assembly method improve the operating framework of telescopic shafts in drive systems to provide extended operating life, reduced hydraulic effects, fewer parts, and lower packaging requirements.

[0020] Now for reference Figure 1 The shaft assembly is generally shown as 10. Shaft assembly 10 is a rolling element telescopic shaft assembly 10 capable of being connected to or integrally formed with a transmission system (not shown) and transmitting torque. Although shaft assembly 10 can be incorporated into any suitable device, it is particularly suitable for use as a telescopic shaft assembly in the transmission system of a vehicle (e.g., an automobile). Shaft assembly 10 includes an outer shaft member 12 and an inner shaft member 14 telescopically engaging with the outer shaft member 12. The outer shaft member 12 extends along a longitudinal axis A and defines an inner surface 16, which defines an internal bore 18 centered on axis A. It should be understood that the portion of the outer shaft member 12 defining the bore 18 may be generally tubular. The inner shaft member 14 is positioned within the bore 18 and is telescopically movable relative to the outer shaft member 12. The inner surface 16 may include an annular groove 17 (…). Figure 2 (), for receiving the retaining ring 19, for retaining the inner shaft member 14 within the hole 18.

[0021] like Figure 2 As best shown, the inner surface 16 of the outer shaft member 12 defines at least one (e.g., multiple) outer grooves 20 disposed in the inner surface 16. Each outer groove 20 extends along axis A and may be disposed substantially parallel to axis A. In some embodiments, each outer groove 20 may be circumferentially equidistant from axis A. In some embodiments, each outer groove 20 may not be circumferentially equidistant from axis A. As will be described in more detail below, each outer groove 20 can be used via one or more support elements 22 located therein ( Figure 1 Torque is transmitted to the inner shaft member 14. More specifically, a plurality of support elements 22 may be positioned in each outer recess 20. In some embodiments, each outer recess at least partially accommodates the same number of support elements 22. The inner surface 16 may further define at least one outer fluid recess 24 for reducing pressure buildup during operation via hydraulic effects. In some embodiments, at least one outer fluid recess 24 includes an outer fluid recess 24 adjacent to one outer recess 20. In some embodiments, the at least one outer fluid recess 24 extends along the inner surface 16 parallel to axis A, equal to or greater than the length of the outer recess 20. In some embodiments, the at least one outer fluid recess 24 has a circumferential width and radial depth less than that of the outer recess 20, for example, half or less than half the size of the outer recess. The outer fluid recess 24 may be positioned symmetrically relative to axis A.

[0022] like Figure 1 and Figure 3 As best shown, the inner shaft member 14 is at least partially disposed within or enters the bore 18 of the outer shaft member 12. The inner shaft member 14 defines an outer surface 26 that extends along a longitudinal axis A and is telescopingly movable substantially along the longitudinal axis A when the shaft assembly 10 is assembled. The outer surface 26 of the inner shaft member 14 defines at least one (e.g., multiple) inner pockets 28 disposed in the outer surface 26. Each inner pocket 28 may be configured as a partially spherical recess (e.g., a hemisphere or smaller). Each inner pocket 28 may be disposed in at least one row of pockets 29 extending along axis A and may be disposed substantially parallel to axis A. The at least one row of pockets 29 may include multiple rows of pockets 29, and each row of pockets 29 may be circumferentially aligned with an outer recess 20. In some embodiments, each row of pockets 29 may be circumferentially equidistant. In some embodiments, each row of pockets 29 may not be circumferentially equidistant. An imaginary plane defined by the open end of each outer groove 20 can be positioned at an imaginary plane defined by the open end of the inner bag 28 in the corresponding row of bags 29, such that the corresponding outer groove 20 and inner bag 28 are substantially mirror images of each other in circumferential positioning. The corresponding outer groove 20 and inner bag 28 together form the respective support openings.

[0023] In some embodiments, each inner pocket 28 in a row of pockets 29 is axially equidistant. In some embodiments, an outer surface 26 defines at least one inner fluid groove 30. In some embodiments, the at least one inner fluid groove 30 includes an inner fluid groove 30 located between each row of pockets 29. In some embodiments, the at least one inner fluid groove 30 extends along the outer surface 26 parallel to axis A, equal to or greater than the length of the row of pockets 29. In some embodiments, the circumferential width and radial depth of the at least one inner fluid groove 30 are less than the circumferential width and radial depth of the inner pocket 28, for example, half its size or less than half its size. The inner fluid groove 30 may be symmetrically positioned relative to axis A and substantially circumferentially aligned with the outer fluid groove 24 relative to axis A. The circumferential width and radial depth of the inner pocket 28 are generally equal to the circumferential width and radial depth of the outer groove 20. In some embodiments, the outer groove 20 extends along axis A a first distance, and the multiple rows of inner pockets 29 extend along axis A a second distance, wherein the first distance is greater than the second distance.

[0024] The shaft assembly 10 includes a plurality of rolling elements 22 (e.g., balls or rollers), each rolling element being rollatably arranged within a corresponding opening between the outer recess 20 and the inner pocket 28. During relative axial movement or telescopic movement between the outer shaft member 12 and the inner shaft member 14 with minimal sliding friction, the rolling elements 22 rollatably engage the outer shaft member 12 and the inner shaft member 14. The rolling elements 22 may be formed of stainless steel. In some embodiments, the rolling elements 22 have a diameter, and more than half of this diameter is positioned within the outer recess 20 and the inner pocket 28. For example, since a retainer is not required, 95% or less, 85% or less, or 75% or less of the diameter of the rolling elements 22 can be positioned within the outer recess 20 and the inner pocket 28. Furthermore, since a ball retainer typically spaces the rolling elements 22 along axis A, the absence of a ball retainer also allows the shaft assembly 10 to have a smaller outer diameter and a reduced length.

[0025] The multi-row pockets 29 may correspond to a plurality of outer recesses 20, wherein each inner pocket 28 in a row of pockets 29 is arranged opposite to a corresponding outer recess 20 to form a pair. The number of pairs formed may be at least two, at least four, at least six, at least eight, at least ten, or at least twelve. In this case, at least one rolling element 22 is rollingly arranged between each inner pocket 28 and the outer recess 20. The number of inner pockets 28 in each row of pockets 29 may be equal. For example, the number of inner pockets 28 in each row of pockets 29 may be at least two, at least four, at least six, at least eight, at least ten, or at least twelve. In the illustrated embodiment, the number of inner pockets 28 in each row of pockets 29 may be nine.

[0026] Now for reference Figure 4According to another embodiment, a shaft assembly 110 in an assembled state is shown. Unless otherwise stated, the shaft assembly 110 may share... Figures 1-3 All the same features, elements, arrangements, compositions, and assembly methods are shown. However, the inner pocket 28 is now replaced by an inner recess 128. More specifically, the shaft assembly 110 includes an outer shaft member 112 and an inner shaft member 114 telescopically engaging with the outer shaft member 112. The outer shaft member 112 includes an inner surface 116 defining a bore 118. The inner shaft member 114 is positioned within the bore 118 and is telescopically movable relative to the outer shaft member 112. The inner surface 116 of the outer shaft member 112 defines a space that can be referenced. Figures 1-3 The description includes a set of external fluid grooves (not shown) and a set of external grooves 120 with the same configuration. The inner surface 116 may also include an annular groove 117 for receiving a retaining ring 119 to hold the inner shaft member 114 within the bore 118.

[0027] The inner shaft member 114 defines an outer surface 126 that, when the shaft assembly 110 is assembled, telescopically moves and extends generally along the longitudinal axis A. The outer surface 126 of the inner shaft member 114 defines an inner recess 128 and an inner fluid recess (not shown). The inner recess 128 can be positioned relative to a reference... Figures 1-3 The described position relative to the row bag 29 is as previously described. Furthermore, each recess 128 may be configured to hold the same number of rolling elements 122 as the row bag 29, as previously described. In the illustrated embodiment, each recess 128 holds eight rolling elements 122. Similar to the previous embodiments, the shaft assembly 110 does not use a cage to hold the rolling elements 122. As shown, each recess 128 may extend between a first end 134 and a second end 136, and the rolling elements 122 may extend substantially between the first end 134 and the second end 136 and contact each other. The first end 134 and the second end 136 may be partially spherical to abut the spherical surface of the rolling element 122 and axially retain the rolling element therein. In some embodiments, the rolling element 122 has a diameter, and more than half of this diameter is located within the outer recess 120 and the inner recess 128. For example, since a cage is not required, 95% or less, 85% or less, or 75% or less of the diameter of the rolling element 122 can be positioned within the outer groove 120 and the inner groove 128. In some embodiments, the diameters of the first end 134 and the second end 136 are slightly larger than the diameter of the rolling element 122.

[0028] Figure 5 This is a plan view illustrating the sequential steps in a method 200 for assembling a shaft assembly according to the principles of this disclosure. First, refer to... Figure 5In the leftmost figure, sleeve 238 is positioned on the ends of outer shaft members 12, 112 that define holes 18, 118. Sleeve 238 includes an inner surface 240 and defines a straight section 242 positioned adjacent to the outer shaft members 12, 112 and a tapered section 244 spaced apart from the outer shaft members 12, 112 by the straight section 242. The inner surface 240 of the tapered section 244 gradually extends radially outward in a direction away from the straight section 242. A first portion adjacent to the first end 246 of the inner shaft members 14, 114 is placed within the tapered section 244, and rolling elements 22, 122 are placed in an inner pocket 28 or inner groove 128 in a first circumferential array 248. The inner shaft members 14, 114 are then moved deeper into sleeve 238 such that the first circumferential array 248 remains against the inner surface 240 of sleeve 238 and the first portion is located within the straight section 242. In some embodiments, the inner surface 240 of the straight segment 242 may define a rolling element retaining groove 250 extending toward the outer shaft members 12, 112. Next, additional rolling elements 22, 122 are placed in an inner pocket 28 or inner groove 128 located on a second portion of the inner shaft members 14, 114 in a second circumferential array 252. This process continues until each inner pocket 28 retains a rolling element 22, 122, or the inner groove 128 is filled with rolling elements 22, 122 as described above. Then, retaining rings 19, 119 are placed within the annular grooves 17, 117.

[0029] Figure 6This is a flowchart generally illustrating a method 200 for assembling a shaft assembly according to the principles of this disclosure. At 202, method 200 includes providing an outer shaft member, an inner shaft member, and a sleeve that define a bore. At 204, the method continues by aligning a first end of the sleeve with the bore and a second end of the sleeve with the inner shaft member. In some embodiments, the second end of the sleeve defines a tapered section, and the first end of the sleeve defines a straight section. At 206, the method continues by placing rolling elements of a first circumferential array into one of an inner pocket or inner groove defined by the outer surface of a first portion of the inner shaft member. At 208, the method includes further moving the first portion of the inner shaft member into the sleeve (e.g., into the straight section). In some embodiments, the inner shaft member moves from the tapered section toward the straight section until the rolling elements are held between one of the inner pockets or inner grooves and the inner surface of the sleeve. At 210, the method continues by placing the rolling elements of an additional circumferential array (e.g., a second circumferential array) into one of the inner pockets or recesses defined by another portion (e.g., a second portion) of the inner shaft member and further moving the inner shaft member into the sleeve. Step 210 is repeated until all the inner pockets contain rolling elements or each recess is filled with rolling elements. In other words, at 210, the method repeats steps 206 and 208 until all the inner pockets contain rolling elements or each recess is filled with rolling elements. At 212, the method continues by placing a retaining ring between the outer surface of the inner shaft member and the inner surface of the outer shaft member to hold the inner shaft member in a hole in the outer shaft member.

[0030] 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 can be modified to include any number of variations, alterations, substitutions, or equivalent arrangements not described to date, provided that such variations, alterations, or substitutions are proportionate to the concept 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 described embodiments. Moreover, any feature, element, or component of any embodiment may be used in combination with any other embodiment. Therefore, the invention should not be considered as limited by the foregoing description. Rather, this disclosure is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which will be given the broadest interpretation to cover all such modifications and equivalent structures permitted by law.

Claims

1. A shaft assembly for transmitting torque, the shaft assembly comprising: An outer shaft member extends along an axis and includes an inner surface defining a hole and a plurality of outer grooves that at least partially define the hole; An inner shaft member extending along the axis, the inner shaft member including an outer surface defining at least one of a plurality of inner grooves or a plurality of inner pockets aligned with the outer groove; At least one rolling element is positioned between the outer groove and the inner bag or between the outer groove and the inner groove; Wherein, at least one of the outer surface of the inner shaft member or the inner surface of the outer shaft member is configured to axially retain the at least one rolling element, and the shaft assembly does not include a cage, and Wherein, the inner surface of the outer shaft member defines a plurality of outer fluid grooves between the plurality of outer grooves, and / or the outer surface of the inner shaft member defines a plurality of inner fluid grooves between the plurality of inner pockets or the plurality of inner grooves.

2. The shaft assembly according to claim 1, wherein, The outer surface of the inner shaft member defines the inner pocket, and the size of each inner pocket is configured to axially hold a single rolling element.

3. The shaft assembly according to claim 2, wherein, The inner bag defines multiple rows of bags.

4. The shaft assembly according to claim 3, wherein, Each row of bags and each outer groove is parallel to the axis.

5. The shaft assembly according to claim 4, wherein, The outer groove extends a first distance along the axis and the multi-row bag extends a second distance along the axis, wherein the first distance is greater than the second distance.

6. The shaft assembly according to claim 3, wherein, The multiple rows of bags and the outer groove are arranged circumferentially around the axis.

7. The shaft assembly according to claim 1, wherein, The outer surface of the inner shaft member defines the inner groove, and each inner groove extends between a first end and a second end, wherein the at least one rolling element includes a plurality of rolling elements that fill the inner groove.

8. The shaft assembly according to claim 7, wherein, The first and second ends of the inner groove define a partially spherical shape.

9. The shaft assembly according to claim 8, wherein, Each of the inner grooves and each of the outer grooves is parallel to the axis.

10. The shaft assembly according to claim 9, wherein, The outer groove extends a first distance along the axis and the inner groove extends a second distance along the axis, wherein the first distance is greater than the second distance.

11. The shaft assembly according to claim 1, wherein, The at least one rolling element has a diameter, and more than half of the diameter is positioned within the outer groove and the inner pocket or within the outer groove and the inner groove.

12. The shaft assembly according to claim 1, wherein, The inner surface of the outer shaft member defines the plurality of outer fluid grooves between the plurality of outer grooves, and the outer surface of the inner shaft member defines the plurality of inner fluid grooves between the plurality of inner pockets or the plurality of inner grooves, each of the outer fluid grooves being aligned with one of the inner fluid grooves.

13. The shaft assembly according to claim 1, wherein, The inner surface of the outer shaft member defines an annular groove, and a retaining ring is located within the annular groove to hold the inner shaft member in the hole of the outer shaft member.

14. A method of assembling a shaft assembly for transmitting torque, the method comprising: Provides an outer shaft component, an inner shaft component, and a sleeve that define the bore; Align the first end of the sleeve with the hole and align the second end of the sleeve with the inner shaft member. The first end of the sleeve includes a cylindrical straight section and the second end of the sleeve includes a truncated conical section that branches out radially outward away from the cylindrical straight section. The first portion of the inner shaft member is positioned in the truncated conical section, and the rolling elements of the first circumferential array are placed in one of the inner pockets or inner grooves defined by the outer surface of the first portion of the inner shaft member. as well as The first portion and the rolling element of the first circumferential array are passed through the truncated conical section and positioned to engage with the inner surface of the cylindrical straight section of the sleeve.

15. The method of claim 14, further comprising positioning a second portion of the inner shaft member in the truncated conical section, placing the rolling elements of the second circumferential array in one of an inner pocket or inner groove located on the second portion, and placing the first portion in the cylindrical straight section.

16. The method of claim 15, further comprising placing a retaining ring between the outer surface of the inner shaft member and the inner surface of the outer shaft member to retain the inner shaft member in the hole of the outer shaft member.

17. The method of claim 14, wherein, The rolling elements of the first circumferential array are placed into the inner bag.

18. The method of claim 14, wherein, The rolling elements of the first circumferential array are placed in the inner groove.

19. The method of claim 14, further comprising placing the rolling elements of the first circumferential array into a rolling element retaining groove defined by the inner surface of the cylindrical straight section of the sleeve.

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