High pressure fuel supplying apparatus for internal combustion engine and method for controlling the apparatus

A high pressure fuel supplying apparatus, which pressurizes fuel supplied from a fuel supply source and sends the pressurized fuel to a fuel injection system of an internal combustion engine, the apparatus comprising:

• a fuel pump having a pressurizing chamber, wherein the fuel pump repeats a pressurizing stroke and a suction stroke in accordance with rotation of the engine, wherein, during each suction stroke, the fuel pump draws fuel from the fuel supply source to the pressurizing chamber, and wherein, during each pressurizing stroke, the fuel pump pressurizes fuel in the pressurizing chamber and sends the pressurized fuel to the fuel injection system;
• an electromagnetic valve that selectively connects and disconnects the pressurizing chamber with the fuel supply source, wherein the electromagnetic valve is actuated by electricity supplied from a power supply, wherein the electromagnetic valve includes a valve body located in the pressurizing chamber, wherein a valve seat is provided at a part of an inner wall of the pressurizing chamber that faces the valve body, wherein the valve body is urged away from the valve seat by an urging member, wherein, when supply of current to the electromagnetic valve is started, the valve body is moved toward and contacts the valve seat against the force of the urging member, and wherein, when current to the electromagnetic valve is stopped, the valve body is moved toward the interior of the pressurizing chamber away from the valve seat by the force of the urging member;
• a rotational phase detecting device, which detects a rotational phase of the engine;
• a voltage detecting device, which detects a voltage of the power supply;
• a controller, which controls the electromagnetic valve, wherein, to adjust an amount of fuel to be supplied to the fuel injection system, the controller determines opening and closing timing of the electromagnetic valve based on a rotational phase of the engine, wherein, when the rotational phase of the engine is not identified, the controller executes a duty control to cyclically repeats supplying and stopping of current to the electromagnetic valve, and wherein the controller extends a current supplying period in each cycle of the duty control as the voltage detected by the voltage detecting device is lowered.

A method for controlling a high pressure fuel supplying apparatus for an internal combustion engine, wherein the apparatus includes a fuel pump having a pressurizing chamber and an electromagnetic valve, wherein the fuel pump repeats a pressurizing stroke and a suction stroke in accordance with rotation of the engine, wherein, during each suction stroke, the fuel pump draws fuel from a fuel supply source to the pressurizing chamber, and wherein, during each pressurizing stroke, the fuel pump pressurizes fuel in the pressurizing chamber and sends the pressurized fuel to a fuel injection system of the engine, wherein the electromagnetic valve is actuated by electricity supplied from a power supply to selectively connect and disconnect the pressurizing chamber with the fuel supply source, the method comprising:

• determining opening and closing timing of the electromagnetic valve based on a rotational phase of the engine, thereby adjusting an amount of fuel to be supplied to the fuel injection system;
• executing a duty control to cyclically repeats supplying and stopping of current to the electromagnetic valve when the rotational phase of the engine is not identified;
• and
• extending a current supplying period in each cycle of the duty control as the voltage of the power supply is lowered.