Control device and control method for fuel pump

A control method for a motor-driven fuel pump adapted for an internal combustion engine, the internal combustion engine including a fuel injection valve configured to inject fuel into a cylinder, the fuel pump being configured to supply fuel to a fuel pipe connected to the fuel injection valve, the fuel pump including (i) a cylinder, (ii) a mover configured to slide in the cylinder, and (iii) an electric actuator configured to move the mover, the control method comprising:

• controlling energization of the electric actuator so as to reciprocate the mover so that the fuel pump draws in and discharges fuel;
• controlling a discharge count and a unit discharge amount based on an operating state of the internal combustion engine, the discharge count being a number of fuel discharge operations of the fuel pump to the fuel pipe during a period between a first fuel injection from the fuel injection valve and a second subsequent fuel injection, and the unit discharge amount being an amount of fuel of one fuel discharge operation from the fuel pump;
• setting the discharge count to one when a target discharge amount is less than a specified amount, the target discharge amount being a target value of discharge amount of fuel from the fuel pump to the fuel pipe;
• and
• setting the discharge count to two or more when the target discharge amount is equal to or greater than the specified amount.

A control device for a motor-driven fuel pump adapted for an internal combustion engine, the internal combustion engine including a fuel injection valve configured to inject fuel into a cylinder, the fuel pump being configured to supply fuel to a fuel pipe connected to the fuel injection valve, the fuel pump including (i) a cylinder, (ii) a mover configured to slide in the cylinder, and (iii) an electric actuator configured to move the mover, the control device comprising processing circuitry configured to:

• control energization of the electric actuator so as to reciprocate the mover so that the fuel pump draws in and discharges fuel;
• control a discharge count and a unit discharge amount based on an operating state of the internal combustion engine, the discharge count being a number of fuel discharge operations of the fuel pump to the fuel pipe during a period between a first fuel injection from the fuel injection valve and a second subsequent fuel injection, and the unit discharge amount being an amount of fuel of one fuel discharge operation from the fuel pump;
• and
• control the fuel pump to discharge fuel only within the period between the first fuel injection from the fuel injection valve and the second subsequent fuel injection in response to a difference between an actual value of fuel pressure in the fuel pipe and a target value of fuel pressure in the fuel pipe being less than a predetermined pressure.