Low friction camshaft with electric phaser

Abstract

An exemplary engine assembly includes a crankshaft, and a camshaft having cam lobes mounted thereon. The cam lobes are configured to provide lift to respective devices as a function of a rotation of the camshaft. The cam lobes are circumferentially offset from one another such that a timing of operation of the lift is different for each of the at least two cam lobes. The assembly includes at least one roller bearing coupled to the camshaft, and an electric cam phaser configured to alter the timing of the camshaft with respect to the crankshaft as a function of engine operation.

What is claimed is: 
     
         1 . An engine assembly comprising:
 a crankshaft;   a camshaft having at least two cam lobes mounted thereon, the at least two cam lobes configured to provide lift to respective devices as a function of a rotation of the camshaft, wherein the at least two cam lobes are circumferentially offset from one another such that a timing of operation of the lift is different for each of the at least two cam lobes;   at least one roller bearing coupled to the camshaft; and   an electric cam phaser configured to alter the timing of the camshaft with respect to the crankshaft as a function of engine operation.   
     
     
         2 . The engine assembly of  claim 1 , wherein the at least one roller bearing is one of a conical roller bearing, a ball bearing, a needle bearing, and a cylindrical bearing. 
     
     
         3 . The engine assembly of  claim 1 , wherein at least one of the roller bearings coupled to the camshaft operates without a lubricating oil feed. 
     
     
         4 . The engine assembly of  claim 3 , wherein all of the roller bearings coupled to the camshaft do not have a lubricating oil feed. 
     
     
         5 . The engine assembly of  claim 1 , wherein:
 the camshaft is comprised of an inner shaft and an outer shaft that is outside the inner shaft;   one of the at least two cam lobes is mounted to the inner shaft;   another of the at least two cam lobes is mounted to the outer shaft; and   the electric cam phaser is a cam phaser assembly that provides dual independent control and is configured to rotate the inner shaft with respect to the outer shaft.   
     
     
         6 . The engine assembly of  claim 1 , wherein the respective devices are one of a valve, an injection pump, a vacuum pump, a fuel pump, or other actuated device. 
     
     
         7 . The engine assembly of  claim 1 , wherein the engine assembly is one of a spark ignition (SI) engine and a compression ignition (CI) engine. 
     
     
         8 . A method of manufacturing an engine, comprising:
 providing a crankshaft;   providing a camshaft having multiple lobes configured to provide mechanical action to respective devices as a function of a rotation of the camshaft, wherein the at least two cam lobes are circumferentially offset from one another such that a timing of operation of the mechanical action is different for at least two of the multiple cam lobes;   coupling at least one roller bearing to the camshaft;   coupling an electric cam phaser between the camshaft and the crankshaft; and   configuring the electric cam phaser to alter the timing of the camshaft with respect to the crankshaft as a function of engine operation.   
     
     
         9 . The method of  claim 8 , wherein coupling at least one roller bearing to the camshaft comprises coupling one of a conical roller bearing, a ball bearing, a needle bearing, and a cylindrical bearing. 
     
     
         10 . The method of  claim 8 , wherein coupling the at least one roller bearing to the camshaft comprises coupling at least one of the roller bearings to the camshaft that does not have a lubricating feed. 
     
     
         11 . The method of  claim 8 , wherein coupling the at least one roller bearing to the camshaft comprises coupling roller bearings to the camshaft that are all without a lubricating feed. 
     
     
         12 . The method of  claim 8 , wherein:
 providing the camshaft comprises providing an inner shaft concentrically placed within an outer shaft such that both inner and outer shafts rotate with respect to a central rotation axis; and further comprising:   mounting one of the at least two cam lobes to the inner shaft;   mounting one of the at least two cam lobes to the outer shaft; and   wherein configuring the electric cam phaser further comprises configuring the electric cam phaser assembly to provide dual acting control and to rotate the inner shaft with respect to the outer shaft.   
     
     
         13 . The method of  claim 8 , wherein providing the camshaft to provide the mechanical action further comprises providing the camshaft to provide the mechanical action to the respective devices that are one of a valve, an injection pump, a vacuum pump, and a fuel pump or other actuated device. 
     
     
         14 . The method of  claim 8 , wherein the engine is one of a spark ignition (SI) engine and a compression ignition (CI) engine. 
     
     
         15 . A camshaft assembly comprising:
 a camshaft having at least two cam profiles positioned along respective axial locations, the at least two cam profiles configured to provide lift to respective devices of an engine, wherein the at least two cam profiles are circumferentially offset from one another such that a timing of operation of the lift is different for each of the at least two cam profiles; and   at least one roller bearing coupled to the camshaft;   an electric cam phaser coupled to the camshaft and coupleable to a crankshaft, the electric cam phaser configured to alter the timing of the camshaft with respect to the crankshaft as a function of engine operation.   
     
     
         16 . The camshaft assembly of  claim 15 , wherein the at least one roller bearing is one of a conical roller bearing, a ball bearing, a needle bearing, and a cylindrical bearing. 
     
     
         17 . The camshaft assembly of  claim 15 , wherein at least one of the roller bearings coupled to the camshaft does not have a lubricating oil feed. 
     
     
         18 . The camshaft assembly of  claim 17 , wherein all of the roller bearings coupled to the camshaft do not have a lubricating oil feed. 
     
     
         19 . The camshaft assembly of  claim 15 , wherein:
 the camshaft is comprised of an inner shaft and an outer shaft that is outside the inner shaft;   one of the at least two cam profiles is mounted to the inner shaft;   another of the at least two cam profiles is mounted to the outer shaft; and   the electric cam phaser is an electric cam phaser assembly that provides dual independent control and is configured to rotate the inner shaft with respect to the outer shaft.   
     
     
         20 . The camshaft assembly of  claim 15 , wherein the respective devices are one of a valve, an injection pump, a vacuum pump, and a fuel pump or other actuated device.