Fuel injection system for internal-combustion engine and method of controlling fuel injection system for internal-combustion engine

An engine control unit for an internal-combustion engine driving a fuel injection valve electromagnetically to provide fuel injection multiple number of times per operation cycle to a combustion chamber of the internal-combustion engine, the engine control unit comprising:

• a microcomputer outputting a valve open time for opening the fuel injection valve and an injection time for injecting the fuel injection valve;
• a booster circuit that boosts the voltage of the battery to generate a boost voltage for the engine control unit;
• a voltage driver which controls the supply of an Ipeak current generated by the boost voltage and an Ihold1 current generated by the boost voltage or the battery voltage smaller than the Ipeak current to the fuel injection valve according to the valve opening time, and controls the supply of an Ihold2 current generated by the battery voltage smaller than the Ihold1 current to the fuel injection valve according to the fuel injection time, wherein
• the Ipeak current and the Ihold1 current are predetermined to open the fuel injection valve, and the Ihold2 current is predetermined to hold the fuel injection valve open,
• the valve open time is extended to control the providing current to the fuel injection valve to reach to the Ipeak current when the boost voltage of the booster circuit is below a predefined normal voltage V0, and
• the controller has a predefined threshold value V1 at which a control signal is transmitted to decrease the number of multiple injections of the fuel injection valve or halt the fuel injection valve when there is a further decrease in the boost voltage.

An engine control unit for an internal-combustion engine driving a fuel injection valve electromagnetically to provide fuel injection multiple number of times per operation cycle to a combustion chamber of the internal-combustion engine, the engine control unit comprising:

• a microcomputer outputting a valve open time for opening the fuel injection valve and an injection time for injecting the fuel injection valve;
• a booster circuit that boosts the voltage of the battery to generate a boost voltage for the engine control unit;
• a voltage driver which controls the supply of an Ipeak current generated by the boost voltage and an Ihold1 current generated by the boost voltage and an Ihold1 current generated by the boost voltage or the battery voltage smaller than the Ipeak current to the fuel injection valve according to the valve opening time, and controls the supply of an Ihold2 current generated by the battery voltage smaller than the Ihold1 current to the fuel injection valve according to the fuel injection time, wherein
• the Ipeak current and the Ihold1 current are predetermined to open the fuel injection valve, and the Ihold2 current is predetermined to hold the fuel injection valve open,
• the valve open time is extended to control the providing current to the fuel injection valve to reach to the Ipeak current when the boost voltage of the booster circuit is below a predefined normal voltage V0, and
• the controller transmits a command signal concerning an injection time Ti, which starts simultaneously with the valve open time Pi of the fuel injection valve to keep the fuel injection valve open, to either the boost voltage driver or the battery voltage drive through the driver IC.

An engine control unit for an internal-combustion engine driving a fuel injection valve electromagnetically to provide fuel injection multiple number of times per operation cycle to a combustion chamber of the internal-combustion engine, the engine control unit comprising:

• a microcomputer outputting a valve open time for opening the fuel injection valve and an injection time for injecting the fuel injection valve;
• a booster circuit that boosts the voltage of the battery to generate a boost voltage for the engine control unit;
• a voltage driver which controls the supply of an Ipeak current generated by the boost voltage and an Ihold1 current generated by the boost voltage or the battery voltage smaller than the Ipeak current to the fuel injection valve according to the valve opening time, and controls the supply of an Ihold2 current generated by the battery voltage smaller than the Ihold1 current to the fuel injection valve according to the fuel injection time, wherein
• the Ipeak current and the Ihold1 current are predetermined to open the fuel injection valve, and the Ihold2 current is predetermined to hold the fuel injection valve open,
• the valve open time is extended to control the providing current to the fuel injection valve to reach to the Ipeak current when the boost voltage of the booster circuit is below a predefined normal voltage V0, and
• the engine control unit includes a fuel injection control circuit having the booster circuit, the boost voltage driver, the battery voltage drive and the driver IC.

An engine control unit for an internal-combustion engine driving a fuel injection valve electromagnetically to provide fuel injection multiple number of times per operation cycle to a combustion chamber of the internal-combustion engine, the engine control unit comprising:

• a microcomputer outputting a valve open time for opening the fuel injection valve and an injection time for injecting the fuel injection valve;
• a booster circuit that boosts the voltage of the battery to generate a boost voltage for the engine control unit;
• a voltage driver which controls the supply of an Ipeak current generated by the boost voltage and an Ihold1 current generated by the boost voltage or the battery voltage smaller than the Ipeak current to the fuel injection valve according to the valve opening time, and controls the supply of an Ihold2 current generated by the battery voltage smaller than the Ihold1 current to the fuel injection valve according to the fuel injection time, wherein
• the Ipeak current and the Ihold1 current are predetermined to open the fuel injection valve, and the Ihold2 current is predetermined to hold the fuel injection valve open,
• the valve open time is extended to control the providing current to the fuel injection valve to reach to the Ipeak current when the boost voltage of the booster circuit is below a predefined normal voltage V0, and
• the driver IC includes a booster circuit drive section, which drives the booster circuit, and a driver drive section, which drives the boost voltage driver or the battery voltage driver.

A method of controlling an engine control unit for an internal-combustion engine driving a fuel injection valve electromagnetically to provide fuel injection multiple number of times per operation cycle to a combustion chamber of the internal-combustion engine, the method comprising the steps of:

• outputting a valve open time for opening the fuel injection valve and a injection time for injecting the fuel injection valve;
• causing the engine control unit to monitor a boost voltage obtained by boosting the voltage of the battery;
• controlling the supply of an Ipeak current generated by the boost voltage, and an Ihold1 current generated by the boost voltage or the battery voltage smaller than the Ipeak current to the fuel injection valve according to the valve opening time;
• controlling the supply of an Ihold2 current generated by the battery voltage smaller than the Ihold1 current to the fuel injection valve according to the fuel injection time;
• the Ipeak current and the Ihold1 current are predetermined to open the fuel injection valve, and the Ihold2 current is predetermined to hold the fuel injection valve open;
• and
• the valve open time is extended to control the providing current to the fuel injection valve to reach to the Ipeak current when the boost voltage is below a predefined normal voltage V0.

An engine control unit for an internal-combustion engine driving a fuel injection valve electromagnetically to provide fuel injection multiple number of times per operation cycle to a combustion chamber of the internal-combustion engine, the engine control unit comprising:

• a microcomputer outputting a valve open time for opening the fuel injection valve and an injection time for injecting the fuel injection valve;
• a booster circuit that boosts the voltage of the battery to generate a boost voltage for the engine control unit;
• a voltage driver which controls the supply of an Ipeak current generated by the boost voltage and an Ihold1 current generated by the boost voltage or the battery voltage smaller than the Ipeak current to the fuel injection valve according to the valve opening time, and controls the supply of an Ihold2 current generated by the battery voltage smaller than the Ihold1 current to the fuel injection valve according to the fuel injection time, wherein
• the Ipeak current and the Ihold1 current are predetermined to open the fuel injection valve, and the Ihold2 current is predetermined to hold the fuel injection valve open;
• and
• the valve open time is extended to control the providing current to the fuel injection valve to reach to the Ipeak current when the boost voltage of the booster circuit is below a predefined normal voltage V0, and
• the extended valve open time Pi is provided in inverse proportion to the boost voltage monitored before injection.