Off-axis camshaft phaser

Abstract

A variable camshaft timing system, includes a camshaft phasing mechanism that selectively changes an angular position of an input relative to an output; a first camshaft phaser sprocket, coupled with the input of the camshaft phasing mechanism, configured to engage a first endless loop that communicates rotational force from a crankshaft to the input of the camshaft phasing mechanism; and a second camshaft phaser sprocket, axially spaced from the first camshaft phaser sprocket and coupled with the output of the camshaft phasing mechanism, configured to engage a second endless loop that communicates rotational force from the output of the camshaft phasing mechanism to a camshaft and change the angular position of the camshaft relative to the crankshaft, wherein the camshaft phasing mechanism is mounted about an axis that is different from an axis of camshaft rotation.

What is claimed is: 
     
         1 . A variable camshaft timing system, comprising:
 a camshaft phasing mechanism that selectively changes an angular position of an input relative to an output;   a first camshaft phaser sprocket, coupled with the input of the camshaft phasing mechanism, configured to engage a first endless loop that communicates rotational force from a crankshaft to the input of the camshaft phasing mechanism; and   a second camshaft phaser sprocket, axially spaced from the first camshaft phaser sprocket and coupled with the output of the camshaft phasing mechanism, configured to engage a second endless loop that communicates rotational force from the output of the camshaft phasing mechanism to a camshaft and change the angular position of the camshaft relative to the crankshaft, wherein the camshaft phasing mechanism is mounted about an axis that is different from an axis of camshaft rotation.   
     
     
         2 . The variable camshaft timing system recited in  claim 1 , wherein the first camshaft phaser sprocket and the second camshaft phaser sprocket rotate about a common axis. 
     
     
         3 . The variable camshaft timing system recited in  claim 1 , wherein the camshaft phasing mechanism is hydraulically-actuated. 
     
     
         4 . The variable camshaft timing system recited in  claim 1 , wherein the camshaft phasing mechanism is electrically-actuated. 
     
     
         5 . The variable camshaft timing system recited in  claim 1 , wherein at least one of the first endless loop or the second endless loop is a chain. 
     
     
         6 . The variable camshaft timing system recited in  claim 1 , wherein the camshaft phasing mechanism is attached to an internal combustion engine by an idler shaft or an engine accessory. 
     
     
         7 . A variable camshaft timing system, comprising:
 a camshaft phasing mechanism that selectively changes an angular position of an input relative to an output;   a first camshaft phaser sprocket, coupled with the input of the camshaft phasing mechanism, configured to receive rotational force from a crankshaft; and   a second camshaft phaser sprocket, axially spaced from the first camshaft phaser sprocket and coupled to the output of the camshaft phasing mechanism, configured to provide rotational force to a camshaft and change the angular position of the camshaft relative to the crankshaft, wherein the variable camshaft timing device is mounted about an axis that is different from an axis of camshaft rotation.   
     
     
         8 . The variable camshaft timing system recited in  claim 7 , wherein the first camshaft phaser sprocket, the second camshaft phaser sprocket, or both directly engage one or more gears. 
     
     
         9 . The variable camshaft timing system recited in  claim 7 , wherein the first camshaft phaser sprocket and the second camshaft phaser sprocket each engage an endless loop. 
     
     
         10 . The variable camshaft timing system recited in  claim 7 , wherein the first camshaft phaser sprocket and the second camshaft phaser sprocket rotate about a common axis. 
     
     
         11 . The variable camshaft timing system recited in  claim 7 , wherein the camshaft phasing mechanism is hydraulically-actuated. 
     
     
         12 . The variable camshaft timing system recited in  claim 7 , wherein the camshaft phasing mechanism is electrically-actuated. 
     
     
         13 . The variable camshaft timing system recited in  claim 7 , wherein the camshaft phasing mechanism is attached to an internal combustion engine by an idler shaft or an engine accessory. 
     
     
         14 . A variable camshaft timing system, comprising:
 an inner camshaft phasing mechanism that selectively changes an angular position of an inner camshaft phasing mechanism input relative to an inner camshaft phasing mechanism output;   a first inner camshaft phaser sprocket, coupled with the inner camshaft phasing mechanism input, configured to engage an endless loop that communicates rotational force from a crankshaft to the inner camshaft phasing mechanism input; and   a second inner camshaft phaser sprocket, axially spaced from the first inner camshaft phaser sprocket and coupled with the inner camshaft phasing mechanism output, configured to engage an inner camshaft endless loop that communicates rotational force from the inner camshaft phasing mechanism output to an inner camshaft;   an outer camshaft phasing mechanism that selectively changes an angular position of an outer camshaft phasing mechanism input relative to an outer camshaft phasing mechanism output;   a first outer camshaft phaser sprocket, coupled with the outer camshaft phasing mechanism input, configured to engage an endless loop that communicates rotational force from the crankshaft to the outer camshaft phasing mechanism input; and   a second outer camshaft phaser sprocket, axially spaced from the first outer camshaft phaser sprocket and coupled with the outer camshaft phasing mechanism output, configured to engage an outer camshaft endless loop that communicates rotational force from the outer camshaft phasing mechanism output to an outer camshaft, wherein the inner camshaft and the outer camshaft are concentric.   
     
     
         15 . The variable camshaft timing system recited in  claim 14 , wherein a single endless loop engages the first inner camshaft phaser sprocket and the first outer camshaft phaser sprocket. 
     
     
         16 . The variable camshaft timing system recited in  claim 14 , wherein the inner camshaft phasing mechanism and the outer camshaft phasing mechanism are hydraulically-actuated. 
     
     
         17 . The variable camshaft timing system recited in  claim 14 , wherein the inner camshaft phasing mechanism and the outer camshaft phasing mechanism are electrically-actuated. 
     
     
         18 . The variable camshaft timing system recited in  claim 14 , wherein at least one of the endless loops is a chain. 
     
     
         19 . The variable camshaft timing system recited in  claim 14 , wherein the camshaft phasing mechanism is attached to an internal combustion engine by an idler shaft or an engine accessory.