Tuning fuel composition for driving cycle conditions in spark ignition engines

Abstract

Tuning fuel composition delivered to a spark ignition, internal combustion engine as a function of driving cycle conditions results in improvements in one or more of fuel efficiency and combustion emissions.

1 - 12 . (canceled)  
   
   
       13 . A fuel system for spark ignition engines having a CR of 11 or more, comprising: 
 at least a first fuel and a second fuel;    the first fuel having a RON greater than 100, a burn rate greater than 105% of isooctane and a laminar flame speed greater than 105% of isooctane;    means for injecting the first fuel into the engine for combustion therein in response to at least a first predetermined engine operating condition;    a second fuel having a RON less than 90, a burn rate greater than 105% of isooctane and a laminar flame speed greater 105% of isooctane; and    means for injecting the second fuel into the engine for combustion therein in response to at least a second predetermined engine operating condition.    
   
   
       14 . The fuel system of  claim 13  including at least a third fuel having a RON between that of the first and second fuel, further characterized as having a burn rate and flame speed greater than 105% of isooctane.  
   
   
       15 . The fuel system of  claim 14  wherein the third fuel is admixed from the first and second fuel.  
   
   
       16 . The fuel system of  claim 15  wherein the admixture functions to allow engine operation at or about MBT.  
   
   
       17 . The fuel system of  claim 14  wherein the third fuel functions to allow engine operation at or about MBT.  
   
   
       18 . A method for operating spark ignition, internal combustion engine having a CR of 11 or more comprising: 
 combusting a first fuel having a RON greater than 100,a burn rate greater than 105% of isooctane and a laminar flame speed greater than 105% of isooctane under high load conditions;    and combusting a second fuel having a RON less than 90, a burn rate of greater than 105% isooctane and a laminar flame speed greater than 105% isooctane under low load conditions.    
   
   
       19 . The method of  claim 18  having the additional step of combusting a third fuel under moderate load conditions wherein said third fuel has a RON between that of the first and second fuel and further characterized as having a burn rate and flame speed greater than 105% of isooctane.  
   
   
       20 . The method of  claim 19  wherein the third fuel is admixed from the first and second fuel.  
   
   
       21 . The method of  claim 20  wherein the admixture functions to allow engine operation at or about MBT.  
   
   
       22 . The method of  claim 19  wherein the third fuel functions to allow engine operation at or about MBT.  
   
   
       23 . A method for operating a vehicle having a spark ignition engine to increase the efficiency and reduce the emissions of the engine under conditions of use comprising: 
 supplying a first fuel to the engine at about high engine load conditions; and    supplying a second fuel to the engine at about low engine load conditions,    the first fuel having a RON greater than 100, a burn rate greater than 105% of isooctane and a laminar flame speed greater than 105% of isooctane;    the second fuel having a RON less than 90, a burn rate greater than 105% of isooctane and a laminar flame speed greater than 105% of isooctane; and    whereby engine efficiency is increased and emissions are reduced.    
   
   
       24 . The method of  claim 23  wherein said engine is a direct injection, stratified charge engine.  
   
   
       25 . The method of  claim 23  wherein said engine is a port fuel injected, stratified charge engine.  
   
   
       26 . The method of  claim 23  having an additional step of supplying a third fuel to the engine at about moderate load levels, said third fuel having a RON less than about 100 and greater than about 90.  
   
   
       27 . The method of  claim 26  wherein the third fuel is admixed from the first and second fuel.  
   
   
       28 . The method of  claim 27  wherein the admixture functions to allow engine operation at or about MBT.  
   
   
       29 . The method of  claim 26  wherein the third fuel functions to allow engine operation at or about MBT.  
   
   
       30 . A fuel system for spark ignited engines that operate under high exhaust gas recycle during low to moderate engine load conditions the system comprising: 
 means for supplying to the engine a first fuel during high load conditions; and    means for supplying to the engine a second fuel during low load conditions;    the first fuel having a RON greater than 100, a burn rate greater than 105% of isooctane and a laminar flame speed greater than 105% of isooctane;    the second fuel having a RON less than 90, a burn rate greater than 105% of isooctane and a laminar flame speed greater than 105% of isooctane; and    whereby engine efficiency is increased and emissions are reduced.    
   
   
       31 . The method of  claim 30  further including means for supplying to the engine a third fuel during moderate load conditions, said fuel having a RON greater than about 90 and less than about 100, a burn rate and flame speed greater than about 105% of isooctane.  
   
   
       32 . The method of  claim 31  wherein the third fuel is admixed from the first and second fuel.  
   
   
       33 . The method of  claim 32  wherein the admixture functions to allow engine operation at or about MBT.  
   
   
       34 . The method of  claim 31  wherein the third fuel functions to allow engine operation at or about MBT.  
   
   
       35 . In a vehicle having spark ignition engine, the improvement wherein the engine has a CR of 11 or more; 
 wherein at least a first fuel and a second fuel are available on the vehicle for combustion by the engine, the first fuel having a RON greater than 100, and under high load conditions a burn rate greater than 105% of isooctane and a laminar flame speed greater than 105% of isooctane, and the second fuel having a RON less than 90, and under low load conditions a burn rate greater than 105% of isooctane and a laminar flame speed greater than 105% of isooctane; and    wherein the first fuel is supplied to the engine when operating under high load conditions and the second fuel is supplied to the engine when operating under low load conditions.    
   
   
       36 . The vehicle of  claim 35  wherein a third fuel is available on the vehicle and is supplied to the engine thereof, said fuel having a RON greater than about 90 and less than about 100, and a burn rate and flame speed greater than about 105% of isooctane.  
   
   
       37 . The vehicle of  claim 36  wherein the third fuel is admixed from the first and second fuel.  
   
   
       38 . The vehicle of  claim 37  wherein the admixture functions to allow engine operation at or about MBT.  
   
   
       39 . The vehicle of  claim 36  wherein the third fuel functions to allow engine operation at or about MBT.  
   
   
       40 . A method of operating an internal combustion engine having a CR of 11 or more, the method comprising: 
 providing a plurality of fuels of different and predetermined combustion properties, each fuel selected to improve engine performance under preselected operating conditions; and    supplying the selected fuel to the engine when operating at the preselected condition.    
   
   
       41 . A method of reducing emissions and increasing efficiency of a spark ignition internal combustion engine having a CR of 11 or more, the method comprising: 
 providing a plurality of fuels of different and predetermined combustion properties, each fuel selected to improve engine performance under preselected operating conditions; and    supplying the selected fuel to the engine when operating at the preselected condition.    
   
   
       42 . A fuel system for spark ignition engines having a CR of 11 or more, comprising: 
 at least a first fuel and a second fuel;    the first fuel having a RON set at the minimum required to allow operating the engine at MBT when at wide open throttle at the rpm setting for maximum power, a burn rate greater than 105% of isooctane and a laminar flame speed greater than 105% of isooctane;    means for injecting the first fuel into the port or engine for combustion therein in response to at least a first predetermined engine operating condition;    a second fuel having a RON less than 90, a burn rate greater than 105% of isooctane and a laminar flame speed greater than 105% of isooctane; and    means for injecting the second fuel into the port or engine for combustion therein in response to at least a second predetermined engine operating condition.    
   
   
       43 . The fuel system of  claim 42  further comprising a third fuel having a RON greater than about 90 and less than about 100, and a burn rate and flame speed greater than about 105% of isooctane.  
   
   
       44 . The fuel system of  claim 43  wherein the third fuel is admixed from the first and second fuel.  
   
   
       45 . The fuel system of  claim 44  wherein the admixture functions to allow engine operation at or about MBT.  
   
   
       46 . The fuel system of  claim 43  wherein the third fuel functions to allow engine operation at or about MBT.