BEARING ASSEMBLY HAVING A SHAFT, A FIRST BEARING, AND A NUT

Abstract

A bearing assembly includes a shaft, a first bearing, and a nut. The nut has a thread, which is screwed onto a threaded region formed on the shaft, and a bearing seat formed on the shaft adjoins the threaded region. The inner ring of the first bearing contacts the bearing seat, and the nut contacts the inner ring of the first bearing. The inner ring of the first bearing is arranged spaced apart from the threaded region of the shaft. A runout region of a thread cut into the threaded region of the shaft is arranged in a subsection of the bearing seat adjoining the threaded region.

Claims

1-15. (canceled)

16. A bearing assembly, comprising: a shaft; a first bearing, and a nut including a thread threadedly engaged with a threaded region of the shaft; wherein a bearing seat arranged on the shaft adjoins the threaded region, an inner ring of the first bearing contacts the bearing seat, the nut contacts the inner ring of the first bearing, the inner ring of the first bearing is arranged spaced apart from the threaded region of the shaft, and a runout region of a thread cut into the threaded region of the shaft is arranged in a subsection of the bearing seat adjoining the threaded region.

17. The bearing assembly according to claim 16, wherein the nut is arranged as a shaft nut, the thread of the nut includes an internal thread, the threaded region of the shaft includes an external thread, and the inner ring of the first bearing is pressed onto the bearing seat.

18. The bearing assembly according to claim 16, wherein the bearing seat is arranged as a finely machined and/or ground cylindrical and/or outer-cylindrical, surface.

19. The bearing assembly according to claim 18, wherein the cylindrical and/or outer-cylindrical surface is only interrupted by a depression that runs out in the runout region.

20. The bearing assembly according to claim 16, wherein the nut presses against the inner ring of the first bearing.

21. The bearing assembly according to claim 16, wherein the bearing seat covers a larger region in an axial direction than the inner ring of the first bearing.

22. The bearing assembly according to claim 21, wherein the bearing seat extends further in the axial direction than a contact region between the bearing seat and the inner ring of the first bearing.

23. The bearing assembly according to claim 21, wherein the axial direction corresponds to a direction of an axis of rotation of the shaft.

24. The bearing assembly according to claim 16, wherein the nut includes a first inner-cylindrical region adjoining the thread of the nut and contacting the bearing seat and/or the runout region.

25. The bearing assembly according to claim 16, wherein the nut includes a circumferential chamfer in a circumferential direction on an edge region oriented toward the shaft.

26. The bearing assembly according to claim 16, wherein a largest clear internal diameter of the nut in a region of the thread of the nut is less than or equal to a clear internal diameter of an inner-cylindrical region adjoining the thread of the nut.

27. The bearing assembly according to claim 16, wherein an outer ring of the first bearing is accommodated in a housing and an outer ring of a second bearing is accommodated in and/or set against an step of the housing.

28. The bearing assembly according to claim 27, wherein the housing is arranged integrally and includes an internal toothing.

29. The bearing assembly according to claim 27, wherein the housing is includes in several parts and includes a ring gear having internal toothing.

30. The bearing assembly according to claim 27, wherein an inner ring of the second bearing is arranged on the shaft and/or is set against a step provided on the shaft.

31. The bearing assembly according to claim 16, an outer ring of the first bearing and an outer ring of a second bearing rest against steps arranged on a housing arranged in an axial direction between the first bearing and the second bearing, and the second bearing is arranged in the axial direction between the first bearing and a step arranged on the shaft against which an inner ring of the second bearing is set.

32. The bearing assembly according to claim 16, wherein the first bearing is arranged in an axial direction between the nut and a second bearing.

33. The bearing assembly according to claim 16, wherein an inner cylindrical region arranged on the nut is arranged in an axial direction between the thread of the nut and the inner ring of the first bearing.

34. The bearing assembly according to claim 16, wherein the bearing seat on the shaft is arranged in an axial direction between the threaded region of the shaft and a second bearing.

35. The bearing assembly according to claim 16, wherein the shaft is arranged as a planet carrier in which planet bolts are accommodated and/or connected, on which planet gears are rotatably mounted, and toothings of the planet gears mesh with an internal toothing and with a toothing of a rotatably arranged part.

36. The bearing assembly according to claim 35, wherein the planet gears are mounted on the planet bolts by bearings and/or needle bearings mounted on the planet bolts, and the rotatably arranged part includes a sun gear.

37. The bearing assembly according to claim 16, wherein the nut includes a second inner-cylindrical region that adjoins the thread of the nut and is arranged on a side of the thread of the nut facing away from a first inner-cylindrical region.

38. The bearing assembly according to claim 37, wherein the second inner-cylindrical region has a smaller clear internal diameter than a smallest clear internal diameter of the thread of the nut and/or is pressed onto a second outer-cylindrical region of the shaft that adjoins the threaded region of the shaft and has a smaller outer diameter than a largest outer diameter the threaded region of the shaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG. 1 is a cross-sectional view of a bearing assembly according to an example embodiment of the present invention for a planetary gear.

[0035] FIG. 2 is a perspective view of the bearing assembly.

[0036] FIG. 3 is an enlarged view of the region identified as B in FIG. 1.

[0037] FIG. 4 is an enlarged view of the region identified as C in FIG. 1.

DETAILED DESCRIPTION

[0038] As schematically illustrated in the Figures, the bearing assembly has bearings (5, 7) accommodated in a housing part, e.g., housing 6 having ring gear, for mounting a shaft. The shaft is arranged as a planet carrier 2 together with a second flange 4 of the planet carrier 2, for example.

[0039] Here, the second flange 4 and the planet carrier 2 are connected in a rotationally-fixed manner, e.g., as a single piece, i.e., integrally, i.e., for example, in one piece, or as two parts connected to one another, i.e., for example, in two pieces.

[0040] A respective planet bolt 3 is pressed into a bore of the planet carrier 2 and also into a bore of the second flange 4.

[0041] A first bearing 7 is pre-tensioned by a nut 1, e.g., a shaft nut, screwed onto an external thread of the shaft. For this purpose, the nut 1 presses the inner ring of the first bearing 7, which is pushed onto the shaft, e.g., the planet carrier 2, in the axial direction towards the second bearing 5. As a result, the shaft is pulled in the opposite direction and the inner ring of the second bearing 5 pushed onto the shaft, e.g., onto the second flange 4, is thus pressed towards the first bearing 7. The outer rings of the two bearings 5 and 7 are located on a shoulder of the housing 6. Therefore, a closed power flow is obtained, which flows from the nut via the planet carrier 2 together with the second flange 4 and the second bearing 5, the housing 6 and the first bearing 7, back to the nut 1.

[0042] Both bearings (5, 7) are thus pre-tensioned by the nut 1.

[0043] Both bearings (5, 7) are, for example, arranged as angular bearings.

[0044] A ring gear having internal toothing is accommodated in the housing 6, or the ring gear is integrated into the housing 6 by an internal toothing being formed on the inside of the housing 6, e.g., axially between the two shoulders.

[0045] The planet gears, which are rotatably mounted on the planet pin 3, mesh with the internal toothing, on the one hand, and with the toothing of a rotatably mounted sun gear, on the other hand.

[0046] The nut 1 is particularly suitable if the planetary gear stage has a flange block output. Because in this case the external diameter of the planet carrier 2 on the output side is very large. For example, the radial distance region covered by the nut 1 and in relation to the axis of rotation of the planet carrier 2 includes the radial distance region covered by the inner ring of the first bearing 7 or at least the two radial distance regions overlap.

[0047] In the bearing assembly described herein, the shaft 2, e.g., the planet carrier 2, has a finely machined bearing seat 30 on which the inner ring of the first bearing 7 is arranged. However, this finely machined bearing seat 30 extends further in the axial direction than the axial region required by the inner ring of the first bearing 7.

[0048] A threaded region 32, e.g., an externally threaded region, of the shaft adjoins the bearing seat 30 of the shaft, onto which the nut 1 is screwed using its thread, e.g., an internal thread.

[0049] The threaded region 32 is, for example, arranged as an externally threaded region.

[0050] During the production of the threaded region 32, a tool, e.g., a cutter, is moved in the axial direction, i.e., for example, in the direction of the axis of rotation of the shaft 2, while the tool produces the thread by cutting. At the end of the threaded region 32, the finely machined, i.e., for example, smooth, cylindrical region of the bearing seat 30 does adjoin; however, the tool produces a runout region 31 when it is moved out radially. This is because the shaft is still rotated in the circumferential direction around its axis of rotation while the tool is being removed in a radial direction, so that a thread lead that runs out in the runout region 31 results. The radial depth of the thread lead, i.e., the helical indentation of the threaded region 32, decreases as the axial distance from the threaded region 32 increases. The smallest radial distance of the thread lead is therefore a strictly monotonically increasing function in the runout region 31 with increasing axial distance from the threaded region 32 until this smallest radial distance reaches the outer radius of the bearing seat 30. The inner ring of the bearing 7 is arranged axially spaced apart from the threaded region 32 and from the runout region 31. The runout region 31 is surrounded by the otherwise finely machined bearing seat 30 because the bearing seat 30 is axially extended further than the inner ring of the bearing 7 and has been manufactured before the threaded region 32 is cut.

[0051] Although the raw part of the shaft is only finely machined in the region of the bearing seat 30, e.g., also in the region of the runout region 31 produced later, the raw part is only roughly machined in the region in which the threaded region 32 is later produced, i.e., for example, machined using turning. After the threaded region 32 has been produced, the maximum radial distance in the threaded region 32 is less than half the external diameter of the bearing seat 30. This is because the peaks between the indentations of the thread turn are also machined when the threaded region 32 is produced.

[0052] The nut 1 has an internal thread, using which the nut 1 is screwed onto the threaded region 32 of the shaft. The nut 1 has a finely machined inner-cylindrical region adjoining its internal thread area which, when the nut 1 is screwed in, slides onto the bearing seat 30, e.g., the runout region 31, and thus effectuates a radially directed centering of the nut 1 in relation to the shaft, e.g., the planet carrier 2.

[0053] In addition, the nut has a circumferential chamfer in the circumferential direction on its end region facing toward the first bearing 7. This facilitates threading in when pushing onto the shaft.

[0054] According to example embodiments of the present invention, there is no undercut adjoining the threaded region 32 on the shaft, rather the runout region 31 is connected to the threaded region 32.

[0055] In further exemplary embodiments according to the present invention, the nut 1 is not only configured having an inner cylindrical region, e.g., a snug fit, at its end region facing toward the first bearing 7, but also at its end region facing away from the first bearing 7. Thus, two inner cylindrical regions adjoin the thread of the nut 1 axially on both sides, in which the clear internal diameter of the second inner cylindrical region, i.e., the inner cylindrical region arranged further away from the first bearing, is smaller than the clear internal diameter of the first inner cylindrical region. For example, however, it is also smaller than the smallest internal diameter of the thread of the nut 1 and also has a runout region that is required for the cutting tool during the manufacturing of the thread. The shaft has a corresponding outer cylindrical region which adjoins the threaded region 32 on the side facing away from the runout region 31 and is, for example, arranged without a runout region. This means that the nut can be centered on the shaft with a snug fit on both sides, radially and axially without play, and even more improved concentricity is achievable. For example, when the shaft is arranged as a planet carrier, this improves the service life of the planetary gear.

[0056] In further exemplary embodiments according to the present invention, the planet carrier 2 is arranged having one flange and is thus mounted in the housing 6 via the two bearings 5 and 7. The planet pins are, for example, only inserted on one side into the respective bores of the planet carrier 2.

LIST OF REFERENCE NUMERALS

[0057] 1 nut [0058] 2 planet carrier [0059] 3 planet pin [0060] 4 second flange of the planet carrier [0061] 5 bearing [0062] 6 housing having ring gear [0063] 7 bearing [0064] 30 bearing seat [0065] 31 runout region [0066] 32 threaded region