Camshaft and corresponding production method

Patent metadata

Field	Value
Publication number	US-9828889-B2
Application number	US-201214234057-A
Country	US
Kind code	B2
Filing date	Jul 18, 2012
Priority date	Jul 21, 2011
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

A camshaft for an internal combustion engine may include a shaft and at least one component that is joined to said shaft. The component may be connected via a joint surface of the component to a joint surface of the shaft. At least one of the joint surface of the component and the joint surface of the shaft may have a predefined roughness only partially on load-critical regions.

First claim

The invention claimed is:

1. A camshaft for an internal combustion engine, comprising: a shaft having an outer joint surface and at least one component with an inner joint surface that is joined to said shaft, the at least one component is connected via the inner joint surface of the at least one component to the outer joint surface of the shaft, wherein at least one of the inner joint surface of the at least one component and the outer joint surface of the shaft has a predefined roughness over a circumferential angle of ca. 20 to 140° in a region of a cam tip of an associated cam elevation,
wherein the predefined roughness in the region of the associated cam elevation extends over the circumferential angle of ca. 20 to 140° and further in an opposing region over the circumferential angle of ca. 20 to 140°, thereby providing an increased normal force for higher torque transmission.

2. The camshaft according to claim 1 , wherein the predefined roughness is incorporated by way of at least one of a laser, mechanically, or by a chemical method.

3. The camshaft according to claim 2 wherein the predefined roughness has machining tracks that are aligned at least one of parallel, transverse or diagonal to a camshaft axis of the shaft, and the inner joint surface of the at least one component and the outer joint surface of the shaft have a different roughness.

4. The camshaft according to claim 3 , wherein the machining tracks form a machining pattern and the individual machining tracks are arranged at an angle of 0-90° relative to the camshaft axis.

5. The camshaft according to claim 4 , wherein the machining pattern includes at least one of a checked pattern, a rhomboid pattern, and a rectangular pattern.

6. The camshaft according to claim 1 , wherein the at least one component is formed as at least one of a cam, a signal generator wheel, a chain/belt wheel, a plug, a gearwheel, a drive element or output element, a tool interface, an adjusting element, an aligning element, an assembly aid element, a bearing ring, and a sleeve.

7. The camshaft according to claim 6 , wherein at least one of the outer and inner joint surfaces is roughened in a ring-shaped manner at least partially at two axial edges that are spaced apart from each other.

8. The camshaft according to claim 1 , wherein the at least one component is connected to the shaft by at least one of a press fit and a thermally joined fit, wherein the at least one component includes cams that are heated for the thermally joined fit.

9. The camshaft according to claim 1 , further comprising a structural element connected to the at least one component and including a third joint surface having the predefined roughness.

10. The camshaft according to claim 9 , wherein the structural element and the at least one component are connected to each other via a screw connection.

11. The camshaft according to claim 9 , wherein the structural element is arranged on a front side of the at least one component.

12. The camshaft according to claim 9 , wherein at least one of the at least one component is formed from a metal with a carbon content of at least 0.6% by weight, whereas the shaft has a lower carbon content, and at least one of the inner joint surface of the component, the third joint surface of the structural element, and the outer joint surface of the shaft have an initial roughness that is incorporated and hardened by a laser, wherein the shaft is hardened by the laser prior to incorporating the predefined roughness.

13. The camshaft according to claim 12 , wherein the initial roughness incorporated and hardened by the laser comprises a track that is composed of individual laser points, wherein first and second centers of the individual laser points are arranged offset to each other, and the individual laser points are arranged overlapping each other, and the shaft is formed from E335 steel, and the components are formed from C60 or 100Cr6 steel.

14. The camshaft according to claim 1 , wherein the inner joint surface has the predefined roughness incorporated by a laser.

15. The camshaft according to claim 1 , further comprising axially parallel machining tracks formed as hardened sliding tracks incorporated in at least one of the outer and inner joint surfaces, and the at least one component includes a cam, and the inner joint surface is formed as a cam seat that is turned on an inside and which is overlaid with machining tracks formed as laser structures.

16. The camshaft according to claim 1 , wherein at least one of the outer and inner joint surfaces is roughened in a ring-shaped manner at least partially at two axial edges that are spaced apart from each other.

17. The camshaft according to claim 1 , wherein the predefined roughness is incorporated by the laser has machining tracks that are aligned at least one of parallel, transverse, or diagonal to a camshaft axis, and the outer joint surface and inner joint surface have a different roughness.

18. A device for producing a camshaft having a shaft with an outer joint surface and at least one cam with an inner joint surface that is joined to said shaft, said at least one cam is connected via the inner joint surface of the at least one cam to the outer joint surface of the shaft, comprising:
a feed unit for displacing the shaft,
a holding and heating device for heating the at least one cam and for fixing the at least one cam during assembly, and
a laser for incorporating partial roughness over a circumferential angle of ca. 20 to 140° in at least one of the inner joint surface of the at least one cam and the outer joint surface of the shaft immediately prior to sliding on the at least one cam, the partial roughness being in a region of a cam tip of an associated cam elevation.

19. A method for producing a camshaft having a shaft with an outer joint surface and at least one cam with an inner joint surface that is joined to said shaft, said cam is connected via the inner joint surface of the at least one cam to the outer joint surface of the shaft, comprising:
providing a feed unit that displaces the shaft,
heating the at least one cam before assembly and fixing the at least one cam during assembly via a holding and heating device, and
incorporating, via a laser, a partial roughness over a circumferential angle of ca. 20 to 140° in at least one of the inner joint surface of the at least one cam and the outer joint surface of the shaft immediately prior to sliding on the at least one cam, the partial roughness being in a region of a cam tip of an associated cam elevation.

Assignees

• Lettmann Markus
• Rieger Ralf
• Schneider Falk
• Grunwald Lutz
• Menonna Antonio
• Steichele Stefan
• Mahle Int Gmbh

Inventors

• Lettmann Markus
• Rieger Ralf
• Schneider Falk
• Grunwald Lutz
• Menonna Antonio
• Steichele Stefan

Classifications

• F01L1/04 Primary

  by means of cams, camshafts, cam discs, eccentrics or the like (F01L1/10 takes precedence) · CPC title

• Y10T29/49293

  Camshaft making · CPC title

• B23P11/025 Primary

  by using heat or cold · CPC title

• B23P2700/02

  Camshafts · CPC title

• F16H53/025

  characterised by their construction, e.g. assembling or manufacturing features · CPC title