Fuel injection control device

A fuel injection control device that is applied to a fuel injection valve to operate for valve opening a valve body to open and close an injection hole to inject a fuel by an electric actuator, controls a valve opening time of the valve body by controlling the operation of the electric actuator, and thus controls an injection quantity injected per one time valve opening of the valve body, the fuel injection control device comprising:

• a conduction time calculation unit to calculate a conduction time of the electric actuator corresponding to a requested injection quantity that is an injection quantity requested during partial lift injection in which the valve body starts valve closing operation before the valve body reaches a maximum valve opening position after the valve body starts valve opening operation;
• a detection unit to detect a physical quantity having a correlation with an actual injection quantity that is an injection quantity injected actually during the partial lift injection;
• an estimation unit to estimate the actual injection quantity on the basis of a detection result of the detection unit;
• a correction unit to correct the requested injection quantity by a correction quantity corresponding to a deviation between the actual injection quantity estimated by the estimation unit and the requested injection quantity;
• a sudden change determination unit to determine whether or not the correction quantity is in a sudden change state on the basis of whether or not the correction quantity has changed from a previous value by a prescribed quantity or more;
• and
• a reflection speed setting unit to set a reflection speed at which the correction unit reflects the correction quantity on the requested injection quantity gradually for a prescribed period of time, wherein
• the reflection speed setting unit sets the reflecting speed when the sudden change determination unit determines a correction quantity to be in the sudden change state at a speed higher than a speed when the correction quantity is determined not to be in the sudden change state.