Fuel supply apparatus

A fuel supply apparatus for supplying fuel to an internal combustion engine, comprising:

• a first fuel pump drawing fuel from a fuel tank and discharging the fuel at a first pressure;
• a first fuel supply system including first fuel injection mechanisms for injecting fuel into said internal combustion engine at said first pressure and a first fuel delivery pipe receiving the fuel discharged from said first fuel pump and delivering the fuel to said first fuel injection mechanisms;
• a second fuel supply system including second fuel injection mechanisms for injecting fuel into said internal combustion engine at a second pressure that is higher than said first pressure, a second fuel pump driven by said internal combustion engine and drawing and further pressurizing the fuel discharged from said first fuel pump and discharging the fuel at said second pressure, and a second fuel delivery pipe receiving the fuel discharged from said second fuel pump and delivering the fuel to said second fuel injection mechanisms;
• and
• a discharge quantity calculating portion for obtaining required supply quantities to said first and second fuel supply systems, respectively, in accordance with an operation condition of the internal combustion engine and for determining a discharge quantity from said first fuel pump based on the required supply quantities obtained, wherein
• said discharge quantity calculating portion includes
• a first calculating portion for calculating the required supply quantity to said first fuel supply system based on at least a fuel injection quantity by said first fuel injection mechanisms and the number of revolutions of said internal combustion engine,
• second calculating portion for calculating the required supply quantity to said second fuel supply system based on the number of revolutions of said internal combustion engine without said fuel injection quantity, and
• third calculating portion for determining the discharge quantity from said first fuel pump in accordance with a sum of the required supply quantities calculated by said first and second calculating portions.