Fuel supply system of internal combustion engine

Abstract

A fuel supply system for use in an internal combustion engine, comprising: an intake passage; a downstream fuel injection valve near the port of each cylinder of the engine and downstream of the intake passage; and a controller, wherein the intake passage includes a fuel injection/evaporation device which has an upstream fuel injection valve; a heater for evaporating injected fuel; and an air passage for supplying the injected fuel with air. The controller is adapted to control the amount of fuel injected from the downstream fuel injection valve and the upstream fuel injection valve, thereby controlling the fuel-air ratio of the injected fuel.

1 . A fuel supply system for use in an internal combustion engine, comprising: 
 an intake passage;    a downstream fuel injection valve locating at a downstream position of said intake passage near the intake port of each cylinder of said engine; and    a controller,    wherein    said intake passage is equipped with a fuel injection and evaporation device which has    an upstream fuel injection valve;    a heater for evaporating injected fuel; and    an air passage for supplying said injected fuel with air, and    said controller is adapted to control amounts of fuel injected from said downstream fuel injection valve and said upstream fuel injection valve, thereby controlling the fuel-air ratio of the injected fuel.    
   
   
       2 . A fuel supply system according to  claim 1 , wherein said controller has a fuel allotment calculation means for calculating a fuel allotment ratio for allotting fuel between said upstream fuel injection valve and said downstream fuel injection valve.  
   
   
       3 . A fuel supply system according to  claim 2 , wherein said fuel allotment calculation means allots less amount to said downstream fuel injection valve than to said upstream fuel injection valve.  
   
   
       4 . A fuel supply system according to  claim 1 , wherein said controller comprises a fuel amount correction means ( 19   f ) for correcting the fuel amount at each cylinder, said fuel amount correction means correcting the amount of fuel injected from said downstream fuel injection valve.  
   
   
       5 . A fuel supply system according to  claim 2 , wherein said controller comprises a fuel amount correction means ( 19   f ) for correcting the fuel amount at each cylinder, said fuel amount correction means correcting the amount of fuel injected from said downstream fuel injection valve.  
   
   
       6 . A fuel supply system according to  claim 3 , wherein said controller comprises a fuel amount correction means ( 19   f ) for correcting the fuel amount at each cylinder, said fuel amount correction means correcting the amount of fuel injected from said downstream fuel injection valve.  
   
   
       7 . A fuel supply system according to  claim 4 , wherein said controller further comprises a storage area for storing constant control parameters for correcting the amount of fuel injected from said downstream fuel injection valve.  
   
   
       8 . A fuel supply system according to  claim 5 , wherein said controller further comprises a storage area for storing constant control parameters for correcting the amount of fuel injected from said downstream fuel injection valve.  
   
   
       9 . A fuel supply system according to  claim 6 , wherein said controller further comprises a storage area for storing constant control parameters for correcting the amount of fuel injected from said downstream fuel injection valve.  
   
   
       10 . A fuel supply system according to  claim 7 , wherein said controller comprises a corrective fuel amount calculation means for correcting the fuel amount at each cylinder, said corrective fuel amount calculation means calculating a corrective fuel amount for each cylinder based on the actual fuel-air ratio and a target fuel-air ratio for the cylinder, wherein said storage area is adapted to store said calculated corrective fuel amount.  
   
   
       11 . A fuel supply system according to  claim 8 , wherein said controller comprises a corrective fuel amount calculation means for correcting the fuel amount at each cylinder, said corrective fuel amount calculation means calculating a corrective fuel amount for each cylinder based on the actual fuel-air ratio and a target fuel-air ratio for the cylinder, wherein said storage area is adapted to store said calculated corrective fuel amount.  
   
   
       12 . A fuel supply system according to  claim 9 , wherein said controller comprises a corrective fuel amount calculation means for correcting the fuel amount at each cylinder, said corrective fuel amount calculation means calculating a corrective fuel amount for each cylinder based on the actual fuel-air ratio and a target fuel-air ratio for the cylinder, wherein said storage area is adapted to store said calculated corrective fuel amount.