Fuel injection system and fuel injecting method for internal combustion engine

摘要

An internal combustion engine in which fuel injection valves are arranged on the upstream side and on the downstream side of the throttle valve respectively, in which process values such as the engine speed and the vehicle speed cause fuel injection to be accurately restricted at predetermined upper limit values. A total injection quantity determination unit determines total quantity Qtotal of fuel to be injected from the upstream side and downstream side fuel injection valves. An injection rate determination unit determines an injection rate Rupper of the upstream injection valve. An injection quantity restriction unit restricts fuel injection of each of the fuel injection valves when process values such as the vehicle speed and the engine speed reach or approach the predetermined upper limit value. The injection quantity determination unit determines the injection quantity Qupper of the upstream injection valve and the injection quantity Qlower of the downstream injection valve.