Concentric dual independent camshaft phaser for dual overhead camshaft valve train

Abstract

A variable valve timing system and methods of operation are provided. A primary valve train driver is configured to rotate about a primary axis. A primary camshaft includes a first plurality of cams positioned on the primary camshaft. The primary camshaft is coaxially coupled to the primary valve train driver. The first plurality of cams is configured to rotate about the primary axis. A primary camshaft phaser is coaxially coupled to the primary camshaft. The primary camshaft phaser is rotatably coupled to the primary valve train driver so as to rotate the primary camshaft phaser and the primary camshaft to a first phase angle. A secondary camshaft driver on the primary axis is coaxially coupled to the primary camshaft, and a secondary camshaft phaser is coaxially coupled to the primary camshaft and coupled to the secondary camshaft driver on the primary axis. The secondary camshaft phaser is rotatably coupled to the primary valve train driver so as to rotate the secondary camshaft driver on the primary axis to a second phase angle.

1 . A variable valve timing system, comprising:
 a primary valve train driver configured to rotate about a primary axis;   a primary camshaft including a first plurality of cams positioned on the primary camshaft, the primary camshaft coaxially coupled to the primary valve train driver, the first plurality of cams configured to rotate about the primary axis;   a primary camshaft phaser coaxially coupled to the primary camshaft, the primary camshaft phaser rotatably coupled to the primary valve train driver so as to rotate the primary camshaft phaser and the primary camshaft to a first phase angle with respect to the primary valve train driver;   a secondary camshaft driver on the primary axis coaxially coupled to the primary camshaft; and   a secondary camshaft phaser coaxially coupled to the primary camshaft and coupled to the secondary camshaft driver on the primary axis , the secondary camshaft phaser rotatably coupled to the primary valve train driver so as to rotate the secondary camshaft driver on the primary axis to a second phase angle with respect to the primary valve train driver.   
     
     
         2 . The variable valve timing system of  claim 1 , wherein the secondary camshaft driver is a first secondary camshaft driver, and further comprising a secondary camshaft configured to rotate about a secondary axis, the secondary camshaft including a second plurality of cams positioned on the secondary camshaft and a second secondary camshaft driver on the secondary axis coupled to the first secondary camshaft driver on the primary axis by a synced drive mechanism, wherein the secondary camshaft phaser is configured to rotate the secondary camshaft to the second phase angle with respect to the primary valve train driver. 
     
     
         3 . The variable valve timing system of  claim 1 , wherein the primary valve train driver includes a primary valve train driver coupled to the crankshaft via a synced drive mechanism. 
     
     
         4 . The variable valve timing system of  claim 1 , wherein the primary valve train driver includes a pulley. 
     
     
         5 . The variable valve timing system of  claim 2 , wherein the first plurality of cams is configured to open a plurality of intake valves. 
     
     
         6 . The variable valve timing system of  claim 5 , wherein the second plurality of cams is configured to open a plurality of exhaust valves. 
     
     
         7 . The variable valve timing system of  claim 2 , wherein the first plurality of cams is configured to open a plurality of exhaust valves. 
     
     
         8 . The variable valve timing system of  claim 7 , wherein the second plurality of cams is configured to open a plurality of intake valves. 
     
     
         9 . The variable valve timing system of  claim 2 , wherein one or more of the primary valve train driver, the primary camshaft phaser, the secondary camshaft phaser, and the secondary camshaft driver on the primary axis are concentric with the primary camshaft. 
     
     
         10 . The variable valve timing system of  claim 2 , further comprising one or more fasteners coaxially coupling one or more of the primary valve train driver, the primary camshaft phaser, the secondary camshaft phaser and the secondary camshaft driver on the primary axis to the primary camshaft. 
     
     
         11 . The variable valve timing system of  claim 1 , wherein the primary camshaft phaser includes a plurality of vanes actuatable via a change in fluid pressure to rotate the primary camshaft phaser with respect to the primary valve train driver. 
     
     
         12 . The variable valve timing system of  claim 1 , wherein the secondary camshaft phaser includes a plurality of vanes actuatable via a change in fluid pressure to rotate the secondary camshaft phaser with respect to the primary valve train driver. 
     
     
         13 . The variable valve timing system of  claim 1 , wherein the primary camshaft phaser includes a primary movable lock pin configured to engage and disengage the primary valve train driver, and wherein the secondary camshaft phaser includes a secondary movable lock pin configured to engage and disengage the primary valve train driver. 
     
     
         14 . A method of operating a valve train variable comprising:
 rotating a primary camshaft phaser and a primary camshaft coaxially coupled to the primary camshaft phaser about a primary axis to a first phase angle with respect to a primary valve train driver coaxially coupled to the primary camshaft and configured to rotate about the primary axis, the primary camshaft including a first plurality of cams positioned on the camshaft, the first plurality of camshaft configured to rotate about the primary axis; and   rotating a secondary camshaft phaser and a secondary camshaft driver on the primary axis coupled to the secondary camshaft phaser about the primary axis to a second phase angle with respect to the primary valve train driver, the secondary camshaft phaser and the secondary camshaft driver on the primary axis coaxially coupled to the primary camshaft.   
     
     
         15 . The method of  claim 14 , further comprising rotating a secondary camshaft to the second phase angle, via the secondary camshaft driver on the primary axis, coupled to the secondary camshaft by a synced drive mechanism coupling the secondary camshaft driver on the primary axis to the secondary camshaft . 
     
     
         16 . The method of  claim 14 , wherein rotating the primary camshaft phaser and the primary camshaft to the first phase angle with respect to the primary valve train driver includes actuating the primary camshaft phaser via a change in a fluid pressure. 
     
     
         17 . The method of  claim 14 , further comprising rotating the primary valve train driver via a crankshaft coupled to a plurality of pistons. 
     
     
         18 . The method of  claim 17 , wherein the primary valve train driver is configured to rotate at ½ the speed of the crankshaft. 
     
     
         19 . The method of  claim 14 , further comprising actuating a plurality of intake valves via the first plurality of cams. 
     
     
         20 . The method of  claim 14 , further comprising actuating a plurality of exhaust valves via the first plurality of cams. 
     
     
         21 . An engine assembly including:
 an engine block housing a plurality of cylinders, the plurality of cylinders including a plurality of pistons positioned therein, the plurality of pistons coupled to a crankshaft;   a cylinder head coupled to the engine block;   a plurality of intake valves positioned in the cylinder head a plurality of exhaust valve positioned in the cylinder head a primary valve train driver coupled to the crankshaft, the primary valve train driver configured to rotate about a primary axis;   an intake camshaft including a first plurality of cams configured to cause actuation of the intake valves, the intake camshaft coaxial coupled to the primary valve train driver, the first plurality of cams configured to rotate about the primary axis;   an intake camshaft phaser coaxially coupled to the intake camshaft, the intake camshaft phaser rotatably coupled to the primary valve train driver so as to rotate the intake camshaft phaser and the intake camshaft to a first phase angle with respect to the primary valve train driver;   a drive sprocket coaxially coupled to the intake camshaft; and   an exhaust camshaft phaser coaxial coupled to the intake camshaft and coupled to the drive sprocket, the exhaust camshaft phaser rotatably coupled to the primary valve train driver so as to rotate the exhaust camshaft phaser and the drive sprocket to a second phase angle with respect to the primary valve train driver.   
     
     
         22 . The engine assembly of  claim 21  further comprising an exhaust camshaft including a second plurality of cams configured to cause actuation of the exhaust valves and, the exhaust camshaft including a secondary sprocket coupled to the drive sprocket by a chain drive, wherein the exhaust camshaft phaser is configured to rotate the exhaust camshaft to the second phase angle with respect to the primary valve train driver. 
     
     
         23 . The engine assembly of  claim 21 , wherein the primary valve train driver includes a camshaft pulley and is coupled to the crankshaft via a belt. 
     
     
         24 . The engine assembly of  claim 21 , wherein the primary valve train driver is configured to rotate at ½ the speed of the crankshaft. 
     
     
         25 . The engine assembly of  claim 21 , wherein one or more of the primary valve train driver, the intake camshaft phaser, the exhaust camshaft phaser, and the drive sprocket are concentric with the intake camshaft. 
     
     
         26 . The engine assembly of  claim 21 , further comprising one or more fasteners coaxially coupling one or more of the primary valve train driver, the intake camshaft phaser, the exhaust camshaft phaser and the drive sprocket to the intake camshaft. 
     
     
         27 . The engine assembly of  claim 21 , wherein the intake camshaft phaser includes a first plurality of vanes actuatable via a change in a first fluid pressure to rotate the intake camshaft phaser with respect to the primary valve train driver and wherein the exhaust camshaft phaser includes a second plurality of vanes actuatable via a change in second fluid pressure to rotate the exhaust camshaft phaser with respect to the primary valve train driver. 
     
     
         28 . The engine assembly of  claim 21 , wherein the intake camshaft phaser includes a primary movable lock pin configured to engage and disengage the primary valve train driver and wherein the exhaust camshaft phaser includes a secondary movable lock pin configured to engage and disengage the primary valve train driver.