Adjustable Camshaft

Abstract

An adjustable camshaft may include an inner shaft and an outer shaft arranged coaxially thereto, and a phase shifter having a stator and a rotor. The stator may be connected to the outer shaft in a rotationally fixed manner, and the rotor may be connected to the inner shaft in a rotationally fixed manner. On an outside of the outer shaft, a first connection contour may be provided. The first connection contour may interact with a second connection contour on the stator formed complementarily thereto in a form-fit manner and enabling at least a tolerance offset in an axial direction.

Claims

1. An adjustable camshaft comprising: an inner shaft and an outer shaft arranged coaxially thereto; and a phase shifter having a stator and a rotor, the stator being connected to the outer shaft in a rotationally fixed manner, and the rotor being connected to the inner shaft in a rotationally fixed manner; and a first cam fixed to the inner shaft in a rotationally fixed manner by a pin; a second cam fixed on the outer shaft in a rotationally fixed manner by one of a thermal joining fit, welding, soldering, gluing, or a press fit; wherein on an outside of the outer shaft, a first connection contour is provided, the first connection contour interacting with a second connection contour on the stator formed complementarily thereto in a form-fit manner and enabling at least a tolerance offset in an axial direction; wherein on an outside diameter of the inner shaft, a third connection contour is provided, the third connection contour interacting with a fourth connection contour on the rotor formed complementarily thereto in a form-fit manner and enabling at least a tolerance offset between the rotor and the inner shaft in the axial direction; wherein the first connection contour and the third connection contour are each formed crowned; wherein the first connection contour is arranged on a sleeve fastened on the outer shaft, the sleeve being located between the outer shaft and the stator; and wherein the sleeve is one of welded, glued, crimped, or soldered on the outer shaft.

2. The camshaft according to claim 1, wherein the first connection contour is formed integrally with the outer shaft.

3. The camshaft according to claim 1, wherein at least one of: the first connection contour and the second connection contour are formed in such a manner that the first and second connection contours allow at least one of a radial movability and a tilting of the stator to the outer shaft; and the third connection contour and the fourth connection contour are formed in such a manner that the third and fourth connection contours allow at least one of a radial movability and a tilting of the rotor to the inner shaft.

4. The camshaft according to claim 1, wherein the second and fourth connection contours are formed crowned.

5. The camshaft according to claim 1, wherein at least one of the first and the second connection contours and the third and the fourth connection contours are formed as one of a tooth contour or a polygonal contour.

6. The camshaft according to claim 5, wherein at least one of the first and the second connection contours and the third and the fourth connection contours are formed as a polygonal contour having an outer hexagon and an inner hexagon.

7. The camshaft according to claim 1, wherein a width of an opening in the outer shaft through which the pin is inserted is greater than a diameter of the pin.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) It shows, in each case schematically,

(2) FIG. 1 a sectional representation through a camshaft according to the invention with a first connection contour designed integrally with an outer shaft of the camshaft,

(3) FIG. 2 a representation as in FIG. 1, however with a first connection contour formed on a sleeve,

(4) FIG. 3 a representation as in FIG. 1, however with an inner shaft of the camshaft screwed to a rotor of a phase shifter,

(5) FIG. 4 a representation as in FIG. 3, however with a first connection contour designed crowned on a sleeve,

(6) FIG. 5 a representation as in FIG. 2, however with a first and third connection contour designed crowned.

DETAILED DESCRIPTION

(7) Corresponding to FIGS. 1 to 5, a camshaft 1 according to the invention comprises an inner shaft 2 and an outer shaft arranged coaxially thereto. An adjustment of the inner shaft 2 relative to the outer shaft 3 in this case takes place by means of a phase shifter 4, the stator 5 of which is connected to the outer shaft 3 in a rotationally fixed manner and the rotor 6 of which is connected to the inner shaft 2 in a rotationally fixed manner. Such a camshaft 1 is usually employed in an internal combustion engine 7, for example in a motor vehicle, in order to influence valve opening time.

(8) In the case of camshafts known from the prior art to date the inner shaft 2 was connected to the rotor 6 in a fixed manner and the outer shaft 3 to the stator 5 of the phase shifter 4 in a fixed manner, wherein even a small inclined position of the rotor 6 relative to the inner shaft 2 could lead to a jamming of the rotor 6 relative to the stator 5 and thus to a function impairment, since no tolerance offset whatsoever was possible. This is where the camshaft 1 according to the invention comes in, which on an outside of the outer shaft 3 comprises a first connection contour 8, which interacts with a second connection contour 9 on the stator 5 that is formed complementarily thereto in a form-fit manner and makes possible at least a tolerance offset in axial direction 10. Because of this it is thus possible to make possible an at least minor tolerance offset between the stator 5 and the outer shaft 3, which is capable of offsetting any existing inclined position of the rotor 6 relative to the stator 5 even in the case of a rotor 6 (see FIGS. 3 and 4) that is screwed to the inner shaft 2 in a fixed manner.

(9) In a further advantageous embodiment of the solution according to the invention, a third connection contour is provided on an outside of the inner shaft 2, which interacts with a fourth connection contour 12 on the rotor 6 designed complementarily thereto in a form-fit manner and likewise makes possible at least a tolerance offset in axial direction. Such an embodiment is shown for example in FIGS. 1, 2 and 5. Depending on design of the individual connection contours 8, 9, 10 and 12, not only a tolerance offset in axial direction 10 is possible here but also a tolerance offset in radial direction 13 and/or an offset of angular deviations between for example the stator 5 and the outer shaft 3 or the rotor 6 and the inner shaft 2, i.e. an offset upon a tilting 17.

(10) In order to be able to offset in particular a tilting 17 between for example the rotor 6 and the inner shaft 2 or the stator 5 and the outer shaft 3, the connection contours 9 and 11, 12 respectively interacting with one another either have to have a certain radial height or at least one of these connection contours 8, 9 or 11, 12 should be formed crowned, as is shown for example in the embodiments of the camshaft 1 according to the invention in accordance with FIGS. 4 and 5.

(11) Here, all camshafts 1 have a first cam 14 which is connected to a first cam 14 via a pin 15 of the inner shaft 2 in a rotationally fixed manner and a second cam 16 that is connected to shaft 3 in a rotationally fixed manner. Here, the second cam 16 can be connected to the outer shaft for example by means of a thermal joining fit, by means of gluing, crimping, soldering or welding.

(12) Looking now at the individual embodiments of the camshaft 1 according to the invention shown in FIGS. 1 to 5, it is evident that according to FIG. 1 a first connection contour 8 is arranged on the outer shaft 3 and an associated second connection contour 9 is arranged on the associated stator 5. The first connection contour 8 in this case is formed integrally with the outer shaft 3. In the same manner, a third connection contour 11 is provided on the inner shaft 2 and on the associated rotor 6 a fourth connection contour 12 formed complementarily thereto. The connection contours 8, 9, 11 and 12 are designed in such a manner that these make possible both a tolerance offset in axial direction 10 and also a tolerance offset with respect to a tilting 17.

(13) Looking at the camshaft 1 according to the invention in accordance with FIG. 2, a first connection contour 8 is evident there, but which is not formed integrally with the outer shaft 3 but on a sleeve 18, wherein the third and fourth connection contour 11, 12 are formed analogously to FIG. 1. With these connection contours 8, 9, 11, 12, too, at least a tolerance offset in axial direction 10 is possible. Here, too, tilting is possible within the scope of the axial play and of the radial play.

(14) In the case of the camshaft shown according to FIG. 3, the rotor 6 is screwed to the inner shaft 2 in a fixed manner via a screw 19, likewise as according to FIG. 4. A tolerance offset between the outer shaft 3 and the stator 5 however is possible via the first and second connection contour 8, 9, wherein the first connection contour 8 in turn is arranged on a sleeve 18.

(15) Looking at FIGS. 4 and 5 it is evident there that according to FIG. 4 the first connection contour 8 according to FIG. 5 the first and third connection contour 8, 11 are formed crowned and because of this make possible a tolerance offset with respect to a tilting 17. Since the inner shaft 2 according to FIG. 4 is coupled to the rotor 6 via the screw 19 in a fixed manner, the stator 5 in this case can follow for example an inclined position of the rotor 6.

(16) The connection contours 8, 9, 11, 12 in this case can be formed for example as tooth contour or as polygonal contour for example as outer and inner polygon, for example as outer hexagon and inner hexagon. Here it is merely important that a torque transmission free of play is possible in order to be able to achieve an exact control of the valve opening times.

(17) With the camshaft 1 according to the invention it is possible for the first time compared with camshafts known up to now from the prior art to offset tolerances both in axial direction 10 and also if applicable also in radial direction 13 or with respect to a tilting 17 and in order to be able to thereby ensure an easy adjustability of the camshaft 1 in the long term, in particular by preventing a jamming of the phase shifter 4.