Rocker system, camshaft, and valve train for use with an internal combustion engine

Abstract

An internal combustion engine system includes an engine with a plurality of pistons housed in respective ones of a plurality of cylinders. A valve train is provided for opening and closing intake and exhaust valves of the cylinders during nominal engine operations. The valve train is also configured to provide for asynchronous switching between selected cam lobe lift profiles for opening and closing of the intake and/or exhaust valves.

What is claimed is: 
     
         1 . A rocker system for an internal combustion engine having a camshaft with at least one camshaft lobe, the at least one camshaft lobe including a cam lobe profile with a first portion, a second portion, and a third portion, the rocker system comprising:
 at least one input rocker lever rotatable about an engine component in response to motion received from the at least one camshaft lobe; and   an output rocker lever rotatable about the engine component, and the output rocker lever can be selectively coupled to the at least one input rocker lever to control opening and closing of at least one of an exhaust valve and an intake valve associated with a cylinder of the internal combustion engine, the at least one input rocker is rotated by the first portion of the cam lobe profile to produce a desired lift of the at least one of the exhaust valve and the intake valve while the at least one input rocker lever is coupled to the output rocker lever, wherein the at least one input rocker is rotated by the second portion of the cam lobe profile to misalign the at least one input rocker lever with the output rocker lever to prevent coupling of the at least one input rocker lever and the output rocker lever, and the at least one input rocker lever is rotated by the third portion of the cam lobe profile to align the at least one input rocker lever with the output rocker lever for coupling the at least one input rocker lever to the output rocker lever.   
     
     
         2 . The rocker system of  claim 1 , wherein the at least one input rocker lever is aligned with the output rocker lever for switching engagement with the output rocker lever over a first range of crank angle degrees of a crankshaft of the internal combustion engine. 
     
     
         3 . The rocker system of  claim 2 , wherein the at least one input rocker is misaligned with the output rocker to prevent switching engagement with the output rocker lever over a second range of crank angle degrees of the crankshaft of the internal combustion engine. 
     
     
         4 . The rocker system of  claim 2 , wherein the output rocker lever controls opening and closing of the at least one of the exhaust valve and the intake valve while in switching engagement with the input rocker lever. 
     
     
         5 . The rocker system of  claim 1 , further comprising at least one valve lift switch for coupling the at least one input rocker lever to the output rocker lever when the at least one input rocker is aligned with the output rocker to transfer motion from the first portion of the at least one camshaft lobe to the at least one of the exhaust valve and the intake valve. 
     
     
         6 . The rocker system of  claim 5 , wherein the at least one input rocker lever includes a first input rocker lever, the rocker system further comprising a second input rocker lever, and the first and second input rocker levers are each rotatable about the engine component in response to motion received from respective ones of a first camshaft lobe and a second camshaft lobe of the camshaft. 
     
     
         7 . The rocker system of  claim 6 , wherein the at least one valve lift switch includes at least one pin that is movable to selectively couple each of the first and second input rocker levers to the output rocker lever. 
     
     
         8 . The rocker system of  claim 6 , wherein the at least one valve lift switch includes a first pin that is movable to selectively couple the first input rocker lever to the output rocker lever and a second pin that is movable to selectively the second input rocker lever to the output rocker lever. 
     
     
         9 . A camshaft for an internal combustion engine having a cylinder and at least one of an intake valve and an exhaust valve associated with the cylinder, the camshaft comprising:
 at least one camshaft lobe configured to control an opening and closing timing of the at least one of the exhaust valve and the intake valve by the at least one cam shaft lobe inducing movement of a rocker lever, the at least one camshaft lobe including a cam lobe profile including:
 a first portion that produces a lift to open the at least one of the exhaust valve and the intake valve through the rocker lever while the rocker lever is associated with the at least one of the exhaust valve and the intake valve; 
 a second portion which misaligns the rocker lever to prevent association of the rocker lever with the at least one of the exhaust valve and the intake valve; and 
 a third portion which aligns the rocker lever for associating the rocker lever to the at least one of the exhaust valve and the intake valve. 
   
     
     
         10 . The camshaft of  claim 9 , wherein the third portion of the cam lobe profile is a constant lift profile that lifts the rocker lever over a first range of crank angle degrees of a crankshaft of the internal combustion engine. 
     
     
         11 . The camshaft of  claim 10 , wherein the second portion of the cam lobe profile is a base circle profile extends from the first portion of the cam lobe profile to the third portion of the cam lobe profile. 
     
     
         12 . The camshaft of  claim 10 , wherein the third portion of the cam lobe profile is connected to the first portion of the cam lobe profile with a transition portion that is smaller in size than the constant lift profile. 
     
     
         13 . A valve train for an internal combustion engine, the valve train comprising:
 one of an intake valve or exhaust valve;   a camshaft including a camshaft lobe;   a first rocker lever movable by the camshaft lobe; and   a switch apparatus for selectively coupling the first rocker lever to a second rocker lever, wherein the camshaft lobe includes a lift profile with a first portion that lifts the one of the intake valve or exhaust valve associated with the camshaft lobe through the first rocker lever, a second portion that misaligns the first rocker lever with the second rocker lever, and a third portion that aligns the first rocker lever with the second rocker lever.   
     
     
         14 . The valve train of  claim 13 , wherein the second at least one other rocker lever is an output rocker lever connected to the one of the intake valve or exhaust valve. 
     
     
         15 . The valve train of  claim 13 , wherein the second rocker lever is moved by a second camshaft lobe, wherein the second camshaft lobe includes a second lift profile that lifts the one of the intake valve or exhaust valve when associated with the second camshaft lobe through the second rocker lever, and the second camshaft lobe includes a base circle portion that is a same size as the third portion of the camshaft lobe. 
     
     
         16 . The valve train of  claim 13 , wherein the second portion of the lift profile of the camshaft lobe misaligns the switch apparatus to prevent coupling of the first rocker lever with the second rocker lever. 
     
     
         17 . The valve train of  claim 13 , wherein the second portion of the lift profile of the camshaft lobe aligns the switch apparatus to couple of the first rocker lever with the second rocker lever. 
     
     
         18 . The valve train of  claim 13 , wherein the switch apparatus includes at least one pin that is housed in one of the first and second rocker levers when the first and second rocker levers are not coupled to one another. 
     
     
         19 . The valve train of  claim 18 , wherein the at least one pin spans between the first rocker lever and the second rocker lever when the first and second rocker levers are coupled to one another. 
     
     
         20 . A method for operating a rocker system, the method comprising:
 aligning an input rocker lever and an output rocker lever with a camshaft lobe;   coupling the aligned input rocker lever to the output rocker lever;   lifting at least one of an intake valve and an exhaust valve with the output rocker lever in response to movement of the input rocker lever induced by the camshaft lobe;   decoupling the input rocker lever from the output rocker lever; and   misaligning the input rocker lever with the output rocker lever with the camshaft lobe to prevent coupling the input rocker lever to the output rocker lever until the input rocker lever and the output rocker lever are aligned with the camshaft lobe.