Internal Combustion Engine Controller

An internal combustion engine controller comprising:

• a voltage booster circuit for boosting a battery voltage and outputting a boosted voltage;
• a first switching element disposed on an upstream side along a current direction of an injector, said first switching element flowing a current through said injector by using said boosted voltage;
• a second switching element disposed in parallel with said first switching element on the upstream side along a current direction of said injector, said second switching element flowing a current through said injector by using said battery voltage;
• a third switching element disposed on a downstream side along a current direction of said injector, said third switching element controlling a current flowing through said injector;
• a resistor serially connected to said injector, said resistor detecting a current flowing through said injector;
• and
• a driver control unit for controlling and driving said first, second and third switching elements, wherein said driver control unit has a current detector circuit for detecting a current flowing through said resistor during a whole period while a current flows through said injector.

A method of controlling a current flowing through an injector of an internal combustion engine, comprising:

• in a first period, a step of flowing a peak current through said injector by turning on a first switching element and by using a boosted voltage obtained by making a voltage booster circuit boost a power supply voltage;
• in a second period, a step of flowing a hold current through said injector by using a power source voltage, by performing on/off control of a second switching element;
• and
• in a third period, a step of flowing a regeneration current through said voltage booster circuit via said injector, by turning off said first and second switching elements, wherein:
• a current flowing through a first resistor serially connected between said injector and a ground is detected during said first and second periods;
• a current flowing through a second resistor serially connected between said injector and said voltage booster during said third period;
• and
• a period transits to said second period when a current detected with said second resistor reaches a predetermined value during said third period.