SUPPORT TUBE OF A CAMSHAFT WITH VARYING WALL THICKNESS

Abstract

A support tube for a camshaft may include at least one setting region for setting at least one component and a free region adjoining the setting region. The support tube may further include a tube wall that has a varying thickness. In the setting region, the tube wall may exhibit a wall thickness that is greater than the wall thickness of the tube wall in the free region. Furthermore, a method for producing such a support tube may involve forming a profiled strip material with varying wall thickness into the support tube. In some cases the tube wall of the support tube may be hydroformed.

Claims

1-10. (canceled)

11. A support tube for a camshaft comprising: a first setting region for setting a first component; a second setting region for setting a second component, wherein the first and second setting regions have mutually different outer surfaces; a free region adjoining the first and second setting regions; and a tube wall that has a varying thickness, wherein thickened portions of the tube wall in the first and second setting regions have a greater thickness than a thickness of the tube wall in the free region, wherein the thickened portions of the tube wall in the first and second setting regions extend into an interior of the support tube such that an outer circumferential surface of the support tube is unvarying in that transitions or offsets between the free region and the setting regions are avoided.

12. The support tube of claim 11 wherein the thickened portions of the tube wall in the first and second setting regions are 110% to 190% as thick as the thickness of the tube wall in the free region.

13. The support tube of claim 11 wherein the thickened portions of the tube wall in the first and second setting regions are twice as thick as the thickness of the tube wall in the free region.

14. The support tube of claim 11 wherein the tube wall is hydroformed.

15. The support tube of claim 11 comprising the first component set on the first setting region, wherein the first component is at least one of a cam, a cam segment comprising at least two cams with mutually different cam tracks, a bearing ring, a sliding element having at least one guide track, or a support sleeve for receiving a cam of a cam segment or of a sliding element.

16. The support tube of claim 11 wherein at least in the first setting region a material of the tube wall has on the outer circumferential surface at least one of a raised formation, a protrusion, or a toothing.

17. The support tube of claim 16 wherein the toothing is a longitudinal toothing.

18. The support tube of claim 16 wherein the raised formation is a rolled formation.

19. A method for producing the support tube of claim 11, the method comprising forming a profiled strip material that has a varying wall thickness into the support tube of claim 11.

20. A support tube for a camshaft comprising: a first setting region for setting a first component; a second setting region for setting a second component; a free region adjoining the first setting region; and a tube wall, wherein thickened portions of the tube wall in the first and second setting regions have greater thicknesses than a thickness of the tube wall in the free region, wherein the thickened portion of the tube wall in the first setting region extends into an interior of the support tube such that an outer diameter of the tube wall in the first setting region is the same as an outer diameter of the tube wall in the free region.

21. The support tube of claim 20 wherein the first and second setting regions have mutually different outer surfaces.

22. The support tube of claim 20 wherein an outer circumferential surface of the support tube is free of any transition between the first setting region and the free region.

23. The support tube of claim 20 wherein an outer circumferential surface of the support tube is free of any offset between the first setting region and the free region.

24. The support tube of claim 20 wherein the thickened portion of the tube wall in the first setting region is 110% to 190% as thick as the thickness of the tube wall in the free region.

25. The support tube of claim 20 wherein the tube wall is hydroformed.

26. The support tube of claim 20 comprising the first component set on the first setting region, wherein the first component is at least one of a cam segment with at least two different cam tracks, or a sliding element having at least one guide track.

27. The support tube of claim 20 wherein at least in the first setting region a material of the tube wall has on the outer circumferential surface at least one of a rolled formation or a longitudinal toothing.

Description

[0017] A camshaft according to the invention is explained in more detail in the following text with reference to a drawing, in which, schematically:

[0018] FIG. 1 shows a sectional illustration from the side of an embodiment of a camshaft according to the invention with an embodiment of a support tube according to the invention.

[0019] FIG. 1 schematically illustrates a sectional illustration from the side of an embodiment of a camshaft 10 according to the invention with an embodiment of a support tube 1 according to the invention. Consequently, the camshaft 10 comprises a support tube 1, which is in the form of a hollow shaft. A through-opening 5 extends in an axial direction through the support tube 1. The support tube 1 comprises a tube wall 2, which comprises at least one setting region 3.1 and 3.2, respectively, and at least one free region 4.1, 4.2 and 4.3, respectively. Advantageously, the support tube 1 comprises three free regions 4.1, 4.2 and 4.3 and two setting regions 3.1 and 3.2. In the region of the first setting region 3.1, a raised material formation 6 has advantageously been created on the outer surface 9 of the support tube 1. It is also conceivable for a toothing, in particular a longitudinal toothing, which serves as a raised material formation, to have been formed in the first setting region 3.1.

[0020] Furthermore, a cam segment 11 has been set on the support tube 1 in the first setting region 3.1. The shaft segment 11 comprises a first cam 11.1 and a second cam 11.2. The first cam 11.1 and the second cam 11.2 have different cam tracks from one another. In the second setting region 3.2 of the support tube 1, a support sleeve 12 has advantageously been placed on the support tube 1. Advantageously, no pretreatment of the outer surface 9 of the support tube 1 in the form of a raised material formation, in particular of a toothing or rolled formation or the like, is formed on the outer surface 9 of the support tube 1 in the second setting region 3.2, such that, for example, the support sleeve 12 has been merely slid onto the support tube 1, in particular onto the setting region 3.2. In this case, it is conceivable for the support sleeve 12 to be heated, for example, with the result that it undergoes a widening of its through-bore, such that, after being heated, the support sleeve 12 is slid onto the support tube 1 as far as its defined setting region 3.2. After the support sleeve 12 has been positioned on the support tube 1, the support sleeve 12 is cooled and reaches its starting temperature, with the result that in particular the through-opening of the support sleeve 12 contracts again and an interference fit between the support sleeve 12 and the support tube 1 arises. However, alternatively or additionally to the heating of the support sleeve 12, it would also be conceivable for the support tube 1 to be cooled, at least before the support sleeve 12 is slid onto the support tube 1. Advantageously, throughout the sliding-on process, at least the support sleeve 12 is heated or the support tube 1 is cooled. After the support sleeve 12 has been slid onto the support tube 1, at least the support sleeve 12 is then cooled or the support tube 1 is then heated. This (shaft/hub) connection is also referred to as a thermal shrink fit or thermal transverse interference fit. Advantageously, in this case, the support sleeve 12 only covers the support tube 1 in the setting region 3.2 of the support sleeve 12 on the support tube 1. Instead of the support sleeve 12, it also possible for other components, for example a cam or a cam segment, a sliding element, etc., to be attached to the support tube 1 by means of the abovementioned method.

[0021] However, it is also conceivable for a raised material formation for example in the form of a rolled formation to have been created on the outer surface 9 of the support tube 1 in the second setting region 3.2, such that when the support sleeve 12 is attached to the second setting region 3.2, a force-fitting connection is allowed on account of the material displacement between the support sleeve 12 and the support tube 1. The cam segment 11 and the support sleeve 12 are components 20 which are arranged or have been set on the respective setting regions 3.1 and 3.2 of the support tube 1 in order to form a camshaft 10.

[0022] As is apparent from FIG. 1, the thickened portions of the wall thicknesses, in particular the wall thickness 8 of the setting regions 3.1 and 3.2, extend in the direction of the through-opening 5 and thus into the interior of the support tube 1. The wall thickness 7 of the free region 4.1, 4.2, 4.3 is, as is apparent from FIG. 1, less or thinner than the wall thickness 8 of the setting regions 3.1 and 3.2.

LIST OF REFERENCE SIGNS

[0023] 1 Support tube

[0024] 2 Tube wall

[0025] 3.1 (First) setting region

[0026] 3.2 (Second) setting region

[0027] 4.1 (First) free region

[0028] 4.2 (Second) free region

[0029] 4.3 (Third) free region

[0030] 5 Through-opening

[0031] 6 Raised (material) formation

[0032] 7 Wall thickness of the free region

[0033] 8 Wall thickness of the setting region

[0034] 9 Outer surface of the support tube

[0035] 10 Camshaft

[0036] 11 Cam segment

[0037] 11.1 First cam

[0038] 11.2 Second cam

[0039] 12 Support sleeve

[0040] 20 Component