Adjustable valve train with hydraulic lifters

Abstract

A valve train with a hydraulic lifter in an engine, and a method of configuring a hydraulic lifter of an engine, are disclosed. The valve train includes a valve, a cam, and at least one coupling component. The valve train further includes the hydraulic lifter, which has a nominal length and is coupled at least indirectly between the valve and the cam by way of the at least one coupling component. The valve train additionally includes a mechanism for varying the nominal length of the hydraulic lifter so that the nominal length is substantially closer to a minimum length of the hydraulic lifter than to a maximum length of the hydraulic lifter.

What is claimed is:  
     
         1 . A valve train in an engine comprising: 
 a valve;    a cam;    at least one coupling component;    a hydraulic lifter having a nominal length and coupled at least indirectly between the valve and the cam by way of the at least one coupling component; and    a mechanism for varying the nominal length of the hydraulic lifter so that the nominal length is substantially closer to a minimum length of the hydraulic lifter than to a maximum length of the hydraulic lifter.    
     
     
         2 . The valve train of  claim 1 , wherein the nominal length is equal to the minimum length plus up to one-third of a difference between the minimum length and the maximum length.  
     
     
         3 . The valve train of  claim 2 , wherein the nominal length is equal to the minimum length plus one of 3%, 10% and 20% of the difference between the minimum and maximum lengths.  
     
     
         4 . The valve train of  claim 1 , wherein the at least one coupling component includes a push rod.  
     
     
         5 . The valve train of  claim 4 , wherein the at least one coupling component further includes a rocker arm.  
     
     
         6 . The valve train of  claim 5 , wherein the valve includes a valve stem, wherein an end of the valve stem abuts a first end of the rocker arm, wherein a first end of the push rod abuts a second end of the rocker arm, and wherein a second end of the push rod abuts a first end of the hydraulic lifter, a second end of the hydraulic lifter being in contact with the cam.  
     
     
         7 . The valve train of  claim 5 , wherein the mechanism includes at least one of an adjustment nut and a set screw that can be varied in position so as to vary a position of the rocker arm and thus further vary a position of the push rod, causing the nominal position of the hydraulic lifter to be varied.  
     
     
         8 . The valve train of  claim 4 , wherein the mechanism includes a device capable of varying a length of the push rod.  
     
     
         9 . The valve train of  claim 1 , wherein the cam includes an automatic compression release mechanism by which a shape of a perimeter of the cam can be varied.  
     
     
         10 . An internal combustion engine comprising: 
 a crankcase;    a crankshaft supported by the crankcase;    a camshaft having a cam, wherein the camshaft is supported by the crankcase and is rotationally coupled to the crankshaft so that rotation of the crankshaft causes rotation of the camshaft;    a valve;    at least one component coupling the valve to the cam, wherein the at least one component includes a hydraulic lifter; and    a mechanism for adjusting a nominal position associated with the hydraulic lifter so that the nominal position is closer to a first position at which the hydraulic lifter is at a minimum length than to a second position at which the hydraulic lifter is at a maximum length.    
     
     
         11 . The internal combustion engine of  claim 10 , wherein the at least one component further includes at least one of a push rod and a rocker arm.  
     
     
         12 . The internal combustion engine of  claim 11 , wherein the mechanism includes at least one of an adjustment nut and a set screw that is capable of adjusting a position of the rocker arm in relation to the crankcase, which in turn adjusts the nominal position of the hydraulic lifter.  
     
     
         13 . The internal combustion engine of  claim 11 , wherein the mechanism includes a device that is capable of adjusting a length of the push rod.  
     
     
         14 . The internal combustion engine of  claim 10 , wherein the cam includes a means for providing automatic compression release functionality.  
     
     
         15 . The internal combustion engine of  claim 10 , wherein the mechanism adjusts the nominal position to be at no more than one-third of a distance from the first position to the second position.  
     
     
         16 . The internal combustion engine of  claim 15 , wherein the mechanism adjusts the nominal position to be at one of 10% and 20% of the distance.  
     
     
         17 . A method of configuring a hydraulic lifter of an internal combustion engine, the method comprising: 
 providing a valve train including the hydraulic lifter, wherein the valve train couples a cam of the engine to a valve of the engine at least indirectly by way of the hydraulic lifter; and    adjusting at least one component of the valve train to set a nominal length of the hydraulic lifter so that the nominal length is substantially closer to a minimum length of the hydraulic lifter than a maximum length of the hydraulic lifter.    
     
     
         18 . The method of  claim 17 , wherein the nominal length is set to be equal to the minimum length plus up to one-third of a difference between the minimum length and the maximum length.  
     
     
         19 . The method of  claim 18 , wherein the nominal length is equal to the minimum length plus one of 3%, 10% and 20% of the difference between the minimum and maximum lengths.  
     
     
         20 . The method of  claim 18 , further comprising: 
 readjusting the nominal position of the hydraulic lifter at a later time.