Fuel supply method

Abstract

The method of the present invention calculates based on the status of the exhaust emission purifier, a required supply of fuel to be supplied from the fuel supply valve to the exhaust passage, reads a unit fuel supply L U in accordance with a energized time t U for the fuel supply valve per one shot, supplies with a driving cycle depending on the required supply, fuel in the unit supply to the exhaust passage, when E DT −E DU <E A −(L U −g) is established, the energized time t UT corresponding to the target fuel supply is interpolated as a function of (L U /g) and the target fuel supply L U is updated as a new unit supply L U , and the function of (L U /g) is supplied as a new energized time t U from the fuel supply valve to the exhaust passage.

1 - 9 . (canceled) 
     
     
         10 . A method for supplying fuel from a fuel supply valve to an exhaust passage at an upstream side of an exhaust emission purifier, the method comprising the steps of:
 calculating, based on the status of the exhaust emission purifier, a required supply of fuel to be supplied from the fuel supply valve to the exhaust passage;   reading a unit fuel supply L U  to be supplied to the exhaust passage in accordance with a energized time t U  to the fuel supply valve per one shot;   intermittently supplying, with a driving cycle depending on the required supply, fuel of the unit fuel supply L U  from the fuel supply valve to the exhaust passage;   reading the maximum tolerance E A  corresponding to the unit supply L U ;   reading the maximum variation error E DU  of the fuel supply valve corresponding to the unit supply L U ;   calculating, regard to the fuel the unit supply L U , an actual fuel supply g actually supplied to the exhaust passage;   setting a target fuel supply L UT  that is less than the unit supply L U  by a certain amount;   reading the maximum variation error E DT  of the fuel supply valve corresponding to the target fuel supply L UT ;   judging whether E DT −E DU <E A −(L U −g) is established or not;   interpolating, when it is judged that E DT −E DU <E A −(L U −g) is established, an energized time T UT  to the fuel supply valve corresponding to the target fuel supply L UT  as a function of (L U /g); and   updating the target fuel supply L UT  as a new unit fuel supply L U  and using the function of (L U /g) as a new energized time t U  to drive the fuel supply valve to supply fuel to the exhaust passage.   
     
     
         11 . The method as claimed in  claim 10 , wherein: the step of reading a unit fuel supply L U  to be supplied to the exhaust passage in accordance with an energized time t U  to the fuel supply valve per one shot reads the latest updated unit supply L U . 
     
     
         12 . The method as claimed in  claim 10 , wherein when fuel to be supplied from the fuel supply valve in accordance with the required supply at every driving cycle of the fuel supply valve is in an amount exceeding the double of the unit fuel supply, a half of the to-be-supplied amount is supplied. 
     
     
         13 . The method as claimed in  claim 11 , wherein when fuel to be supplied from the fuel supply valve in accordance with the required supply at every driving cycle of the fuel supply valve is in an amount exceeding the double of the unit fuel supply, a half of the to-be-supplied amount is supplied. 
     
     
         14 . The method as claimed in  claim 10 , wherein the state of the exhaust emission purifier for calculating the required supply is a temperature of the exhaust emission purifier or an air/fuel ratio of exhaust flowing therein, and
 the method further comprises a step of judging, by carrying-out of the step of intermittently supplying fuel from the fuel supply valve to the exhaust passage for the energized time t U , whether the temperature of the exhaust emission purifier or the air/fuel ratio of the exhaust flowing therein is convergent or not and, only when it is judged that the temperature of the exhaust emission purifier or the air/fuel ratio of the exhaust flowing therein is convergent, the step of judging whether E DT −E DU <E A −(L U −g) is established or not is carried out.   
     
     
         15 . The method as claimed in  claim 14 , wherein the step of judging whether the temperature of the exhaust emission purifier or the air/fuel ratio of the exhaust flowing therein is convergent or not, includes a step of judging whether at least one of the temperature of the exhaust emission purifier and the change rate thereof is within a predetermined range or not, or whether at least one of the air/fuel ratio of the exhaust flowing in the exhaust emission purifier and the change rate thereof is within a predetermined range or not. 
     
     
         16 . The method as claimed in  claim 10 , wherein when the sum of a detection error of the air/fuel ratio and a detection error of an air-intake amount is less than the maximum tolerance, the step of judging whether E DT −E DU <E A −(L U −g) is established or not is carried out. 
     
     
         17 . The method as claimed in  claim 10 , further comprising a step of judging whether an amount of HC passing through the exhaust emission purifier has a value equal to or less than a predetermined value, and
 when it is judged that an amount of HC passing through the exhaust emission purifier has a value equal to or less than a predetermined value, the step of judging whether E DT −E DU <E A −(L U −g) is established or not is carried out.   
     
     
         18 . The method as claimed in  claim 10 , further comprising a step of judging whether a value E T /ΔT C  obtained by dividing a detection temperature error E T  of the exhaust emission purifier by the rate ΔT C  of temperature increase of the exhaust emission purifier per unit time is smaller than the maximum tolerance E A  or not, and
 when it is judged that E T /ΔT C <E A  is established, the step of judging whether E DT −E DU <E A −(L U −g) is established or not is carried out. 
 
     
     
         19 . The method as claimed in  claim 18 , further comprising a step of judging whether an amount of HC passing through the exhaust emission purifier has a value equal to or less than a predetermined value and, only when it is judged that an amount of HC passing through the exhaust emission purifier has a value equal to or less than a predetermined value, the step of judging whether E T /ΔT C <E A  is established or not is carried out.