Abstract
A method for producing a constructed camshaft of an internal combustion engine may be used in connection with a camshaft having a cam, a shaft, and an anti-friction bearing. The method may involve machining the cam, machining the shaft to produce a setting region for arranging the cam, heating the cam and the anti-friction bearing, pushing the cam onto the shaft into a preliminary position and pushing the anti-friction bearing onto the shaft into a bearing position, equalizing a temperature between the shaft, the cam, and the anti-friction bearing by cooling at least the cam, and setting the cam onto an end position by way of pushing the cam onto the setting region.
Claims
1.-13. (canceled)
14. A method for producing a constructed camshaft of an internal combustion engine, the camshaft comprising a cam, a shaft, and an anti-friction bearing, wherein the method comprises: machining the cam; machining the shaft to produce a setting region for arranging the cam; heating the cam and the anti-friction bearing; pushing the cam onto the shaft into a preliminary position, and pushing the anti-friction bearing onto the shaft into a bearing position; equalizing a temperature between the shaft, the cam, and the anti-friction bearing by cooling at least the cam; and setting the cam onto an end position by way of pushing the cam onto the setting region.
15. The method of claim 14 comprising cooling the shaft before heating the cam and the anti-friction bearing.
16. The method of claim 14 comprising cooling the shaft after heating the cam and the anti-friction bearing.
17. The method of claim 14 wherein equalizing the temperature between the shaft, the cam, and the anti-friction bearing comprises heating the shaft.
18. The method of claim 14 wherein machining the shaft to produce the setting region comprises forming an elevation on an outer surface of a circumferential face of the shaft.
19. The method of claim 14 wherein machining the shaft comprises producing a bearing region for arranging the anti-friction bearing on the shaft.
20. The method of claim 19 wherein the bearing region is produced by forming an elevation on an outer surface of a circumferential face of the shaft.
21. The method of claim 20 wherein the elevation is formed by roll forming or grinding.
22. The method of claim 14 wherein during the step of pushing the anti-friction bearing onto the shaft into a bearing position, the method comprises positioning on the shaft a spacer element on both sides of the anti-friction bearing.
23. The method of claim 22 comprising heating the spacer elements with the cam and the anti-friction bearing prior to positioning the spacer elements on the shaft.
24. The method of claim 14 wherein prior to machining the shaft to produce the setting region, the method comprises connecting the shaft to an end piece.
25. The method of claim 14 wherein machining the cam comprises grinding such that the cam is ready for use.
26. The method of claim 14 wherein the anti-friction bearing is a cylindrical roller bearing.
27. The method of claim 14 wherein the anti-friction bearing is a needle bearing with an inner ring.
28. An anti-friction bearing for use in connection with a constructed camshaft having a cam and a shaft, the anti-friction bearing comprising: an inner ring; an outer ring; and a projection that extends in a radial direction on an end side of at least one of the outer ring or the inner ring so as to prevent an axial displacement between the inner and outer rings.
29. The anti-friction bearing of claim 28 configured as a needle bearing.
Description
[0025] Embodiments of a constructed camshaft and the method for producing it and one embodiment of an anti-friction bearing which is to be used advantageously will be described in greater detail in the following text using drawings, in which, in each case schematically:
[0026] FIG. 1 shows a lateral sectional illustration of one embodiment of a constructed camshaft during the method step of pushing cams onto an end position,
[0027] FIG. 2 shows a lateral sectional illustration of that embodiment of a constructed camshaft which is shown in FIG. 1, with cams which are set at the end position,
[0028] FIG. 3 shows a lateral sectional illustration of a further embodiment of a constructed camshaft during the method step of pushing the cams and the anti-friction bearing onto an end position,
[0029] FIG. 4 shows a lateral sectional illustration of that embodiment of a constructed camshaft which is shown in FIG. 3, with cams which are set at the end position,
[0030] FIG. 5 shows a lateral sectional illustration of a further embodiment of a constructed camshaft within closed bearings of a cylinder head cover,
[0031] FIG. 6a shows a detail of a plan view of an end side of one embodiment of an anti-friction bearing according to the invention,
[0032] FIG. 6b shows a detail of a plan view of an end side of a further embodiment of an anti-friction bearing according to the invention, and
[0033] FIG. 6c shows a detail of a plan view of an end side of a further embodiment of an anti-friction bearing according to the invention.
[0034] Elements with an identical function and method of operation are provided with the same designations in FIGS. 1 to 6c.
[0035] FIG. 1 shows a lateral sectional illustration of one embodiment of a constructed camshaft 1. The camshaft 1 has a shaft 9 which is configured, in particular, as a hollow shaft. An end piece 6 is connected to the shaft 9. A distal end of the end piece 6 extends at least in sections into a through opening 9.1 of the shaft 9. It is also conceivable that the shaft 9 is configured as a solid shaft and the through opening 9.1 which is shown in FIG. 1 extends merely, starting from an end side of the shaft 9, into the shaft 9 in sections in the form of a blind bore. In this embodiment, the blind bore is then dimensioned in such a way that the distal end of the end piece 6 can be received. The end piece 6 is advantageously machined, respectively produced from a solid shaft. A cam 2 and a further cam 3 are pushed in the mounting direction 30 from a preliminary position into an end position and, as a consequence, in the direction of the setting region 7, respectively 8. The cam 2, respectively the further cam 3 are advantageously heated to a temperature of from approximately 170 C. to approximately 220 C. Furthermore, it is conceivable that the shaft 9 is cooled. As a result, a defined spacing is produced between the passage opening 2.1, respectively 3.1 of the cam 2, respectively the further cam 3 and the outer surface 9.2 of the shaft 9, with the result that the cams 2, respectively 3 can also be pushed beyond setting regions 7, respectively 8 without the occurrence of clamping, in order to be set at their defined preliminary position. The setting regions 7 and 8 are produced by means of an elevation 7.1, respectively 8.1, in particular a material elevation, advantageously a material accumulation or material structuring. The setting regions 7 and 8 are advantageously formed on the outer surface 9.2 of the shaft 9 by means of roll-forming. Furthermore, the camshaft 1 has an anti-friction bearing 4 which is arranged on the shaft 9. The anti-friction bearing 4 has the components which are known fundamentally, namely an outer ring 4.1, an inner ring 4.2, rolling bodies 4.3 and a cage 4.4. A further anti-friction bearing 5 is arranged by way of example on the end piece 6 and is of comparable configuration to the anti-friction bearing 4 with regard to their components. The cam 2 and the further cam 3 are arranged in a preliminary position such that they are spaced apart from one another in the axial direction along the longitudinal axis 10. As a consequence, the preliminary position lies, as viewed in the mounting direction 30, axially along the longitudinal axis 10 in front of the respective setting regions 7, respectively 8. The cam 2 and the further cam 3 are advantageously moved in the same mounting direction 30, in order to be displaced from a preliminary position to an end position, in particular to the setting region 7, respectively 8. It would also be conceivable, however, that the cam 2 is moved onto the setting region 7 in a first mounting direction 30, whereas the further cam 3 is moved onto the setting region 8 in a mounting direction (not shown here) which is opposed with respect to the mounting direction 30. The anti-friction bearing 4 and the further anti-friction bearing 5 are advantageously already arranged in their end position, with the result that a displacement of the anti-friction bearings 4 and 5 is also no longer necessary after a temperature equalization between the cams 2 and 3, respectively the anti-friction bearings 4 and 5 and the shaft 9. It is conceivable that the setting region 8 is ground by means of a tube grinding operation, advantageously the roll-forming of the setting region 8, as a result of which the position and also the tolerances of the cams 2 and 3 can advantageously be defined more precisely.
[0036] FIG. 2 shows a lateral sectional illustration of that embodiment of a constructed camshaft 1 which is shown in FIG. 1, in the final mounted state. This means that the cam 2 and the further cam 3 are arranged, respectively set in the end position on the corresponding setting regions 7 and 8. Here, a (transverse) press-fit connection is produced between the cams 2, respectively 3 and the shaft 9 in the shaft section of the setting regions 7, respectively 8.
[0037] FIGS. 3 and 4 show a further embodiment of a constructed camshaft 1, which embodiment differs from the embodiment of the camshaft 1 in accordance with FIGS. 1 and 2 in that the anti-friction bearing 4 is also set onto a machined bearing region. As shown in FIG. 3, the anti-friction bearing 4 is set onto a preliminary position which, as viewed in the mounting direction 30, lies axially along the longitudinal axis 10 in front of the bearing region 40. The bearing region 40 is advantageously produced in a comparable manner with respect to the setting regions 7 and 8 by means of an elevation 40.1, in particular a material accumulation, particularly advantageously by means of roll-forming. It is also conceivable that the bearing region 40 has a differing surface structure, respectively surface design in comparison with the setting regions 7 and 8. In a comparable manner to the setting of the cams 2 and 3, the anti-friction bearing 4 is also pushed onto a preliminary position on the shaft 9 after heating to, for example, approximately 170 C. and is set onto the bearing region 40 and accordingly onto its end position only after a temperature equalization between the anti-friction bearing 4 (and, as a consequence, also the cams 2 and 3) and the shaft 9. It is conceivable that the bearing region 40, advantageously the roll-formed portion of the bearing region 40, is ground by means of a tube grinding operation, as a result of which the position and also the tolerances of the anti-friction bearing can advantageously be defined more precisely.
[0038] FIG. 5 shows a further embodiment of a constructed camshaft 1, which embodiment differs from that embodiment of a constructed camshaft which is shown in FIGS. 1 and 2 in that the anti-friction bearing 4 and the further anti-friction bearing 5 have an outer ring 4.1 with an enlarged diameter. It is advantageously possible as a result that, in the case of a correspondingly dimensioned, in particular closed bearing, respectively in the case of closed bearing brackets 50, respectively 51 of a bearing gate of a cylinder head cover (not shown here), complete pushing of the finally mounted camshaft 1 through the closed bearing brackets 50, respectively 51 of the bearing gates of the cylinder head cover is made possible. Secondly, as in the case, for example, of the embodiments of the camshaft 1 in accordance with FIGS. 1 to 4, it would be possible that the camshaft 1, in particular the camshaft final assembly, is carried out within the cylinder head cover. It would be necessary here, however, that the anti-friction bearing 4, respectively 5 and the individual cams 2 and 3 are pre-positioned in corresponding holding elements (not shown here). The shaft 9, with or without an end piece 6, could then be pushed through said positioned and advantageously heated elements, in particular the cams 2, 3 and the anti-friction bearings 4, 5, before the temperature equalization between the cams 2, 3, the anti-friction bearings 4, 5 and the shaft 9 takes place. It is also conceivable, however, that defined cutouts (not shown here) are provided in the cylinder head cover (not shown here), in particular in its bearing brackets, through which defined cutouts the tips of the cams 2, 3 are pushed during the introduction of the constructed camshaft 1 into the cylinder head cover.
[0039] FIG. 6a shows a detail of a plan view of an end side of one embodiment of an anti-friction bearing 20 according to the invention which is configured, for example, as a needle bearing. The outer ring 21 and the inner ring 22 in each case have end-side projections 23, respectively 24 which extend in the radial direction. The projections 23 and 24 are configured so as to be spaced apart from one another axially. The projections 23 of the outer ring 21 and the projections 24 of the inner ring 22 also have a geometric design or dimension which differs from one another. It is also conceivable that the outer ring 21 and the inner ring 22 in each case have merely one projection 23, respectively 24 on the respective end side (the outer ring 21 and the inner ring 22 have in each case two end sides). Those projections 23 of the outer ring 21 which are configured on the respective end side and the projections 24 of the inner ring 22 of the rings 21, respectively 22 advantageously overlap at least in sections, with the result that friction occurs in said overlap region between the outer ring 21 and the inner ring 22. It is conceivable in accordance with FIG. 6a that the inner ring 22 has a smaller length (as viewed in the axial direction) than the outer ring 21, with the result that the inner ring 22 is accordingly enclosed axially, respectively delimited axially to the outside at least in sections by the outer ring 21 on account of the configuration of the projections 23 of the outer ring 21 or the projections 24 of the inner ring 22. As a result, the anti-friction bearing 20 forms a unit which is closed within itself, a movement in the axial direction of the outer ring 21 and/or the inner ring 22 being avoided, but a rotation in the circumferential direction of the inner ring 22 relative to the outer ring 21 still being possible, and the functionality of the bearing therefore not being impaired.
[0040] FIGS. 6b and 6c in each case show a detail of a plan view of an end side of a further embodiment of an anti-friction bearing 20 according to the invention. Accordingly, in the embodiment in accordance with FIG. 6b, merely the outer ring 21 has projections 22, merely the inner ring 22 having projections 24 in accordance with the embodiment of FIG. 6c. The respective projections 23, respectively 24 advantageously always extend, as viewed in the axial direction, along the outer side of the end side of the other ring 21, respectively 22 which has no projections, as a result of which said projection-less ring 21, respectively 22 is delimited, respectively enclosed axially to the outside by the ring 21, respectively 22 with projections 23, respectively 24, as a consequence. The axially inner ring 21, respectively 22 is the inner ring 22 in FIG. 6b or the outer ring 21 in FIG. 6a. A reverse arrangement would also be conceivable, however, in the case of which the projections 23, respectively 34, respectively the at least one projection of one of the rings 21, respectively 22 extend, respectively extends, as viewed in the axial direction, on the inner side of that end side of the other projectionless ring 21, respectively 22 which also extends in the radial direction at least in sections.
LIST OF DESIGNATIONS
[0041] 1 (Constructed) camshaft [0042] 2 Cam [0043] 2.1 Passage opening [0044] 3 Further cam [0045] 3.1 Passage opening [0046] 4 Anti-friction bearing [0047] 4.1 Outer ring [0048] 4.2 Inner ring [0049] 4.3 Rolling bodies [0050] 4.4 Cage [0051] 5 Further anti-friction bearing [0052] 6 End piece [0053] 7 Setting region [0054] 7.1 Elevation [0055] 8 Setting region [0056] 8.1 Elevation [0057] 9 Shaft [0058] 9.1 Through opening [0059] 9.2 Outer surface of the circumferential face [0060] 10 Longitudinal axis [0061] 20 Anti-friction bearing [0062] 21 Outer ring [0063] 22 Inner ring [0064] 23 End-side flanged edge [0065] 24 End-side flanged edge [0066] 30 Mounting direction [0067] 40 Bearing region [0068] 40.1 Elevation [0069] 50 Bearing bracket [0070] 51 Bearing bracket
