Adjustable camshaft

Abstract

An adjustable camshaft for an internal combustion engine includes an outer shaft and a support shaft defining at least one bore with a relief groove configured outside of the bore. The support shaft extends along a longitudinal axis. The outer shaft may include a cam element disposed on the support shaft such that the outer shaft is displaceable along the support shaft along the longitudinal axis wherein the outer shaft is latchable on the support shaft in at least two axial latching positions. A biasing means, a press-fit retainer, and a latching element are disposed within the bore such that the biasing means urges the latching element toward any one recess of the plurality of recesses defined in the outer shaft.

What is claimed is: 
     
         1 . An adjustable camshaft for an internal combustion engine, the adjustable camshaft comprising:
 a support shaft extending along a longitudinal axis;   an outer shaft including a cam element disposed on the support shaft such that the outer shaft is displaceable along the support shaft along the longitudinal axis wherein the outer shaft is latchable on the support shaft in at least two axial latching positions; and   a bore defined in the support shaft with a relief groove defined outside of the bore;   wherein a biasing means, a press-fit retainer, and a latching element are disposed within the bore such that the biasing means urges the latching element toward a recess of a plurality of recesses defined in the outer shaft.   
     
     
         2 . The adjustable camshaft as defined in  claim 1  wherein the relief groove is configured as one of a full-circle groove, semi-circle groove, straight groove and a circumferential groove. 
     
     
         3 . The adjustable camshaft as defined in  claim 2  wherein the relief groove defines a groove depth which varies along a length of the relief groove. 
     
     
         4 . The adjustable camshaft as defined in  claim 2  wherein the relief groove defines a groove depth which is fixed along a length of the relief groove. 
     
     
         5 . The adjustable camshaft as defined in  claim 3  wherein the groove depth falls in a depth range of about 1.5 mm to about 6 mm. 
     
     
         6 . The adjustable camshaft as defined in  claim 3  wherein the groove depth falls in a depth range of about 1.5 mm to about 6 mm. 
     
     
         7 . The adjustable camshaft as defined in  claim 5  wherein the relief groove defines a groove width which falls in a width range of about 1.5 mm to about 6 mm. 
     
     
         8 . The adjustable camshaft as defined in  claim 6  wherein the relief groove defines a groove width which falls in a width range of about 1.5 mm to about 6 mm. 
     
     
         9 . The adjustable camshaft as defined in  claim 7  wherein the bore defines a bore diameter which falls in a diameter range of about 8 mm to about 16 mm. 
     
     
         10 . The adjustable camshaft as defined in  claim 8  wherein the bore defines a bore diameter which falls in a diameter range of about 8 mm to about 16 mm. 
     
     
         11 . A method for manufacturing an adjustable camshaft for an internal combustion engine, comprising the steps of:
 providing a support shaft having a bore and a relief groove defined outside of the bore;   inserting a biasing means into a lower region of the bore;   inserting a latching element into the bore such that the latching element is adjacent to an upper end the biasing means;   press-fitting a press-fit retaining ring in an upper region of the bore so that the latching element is disposed in an aperture defined by the press-fit retaining ring; and   positioning the outer shaft onto the support shaft so that the latching element may be disposed in one of a plurality of detent positions defined on the outer shaft.   
     
     
         12 . The method for manufacturing an adjustable camshaft as defined in  claim 11  wherein the relief groove is defined outside of the at least one bore. 
     
     
         13 . The method for manufacturing an adjustable camshaft as defined in  claim 12  wherein the relief groove is configured to reduce cam shaft deflection along a longitudinal axis of the cam shaft. 
     
     
         14 . The method for manufacturing an adjustable camshaft as defined in  claim 13  wherein the relief groove is configured as one of a full-circle groove, semi-circle groove, straight groove and a circumferential groove.