TECHNICAL FIELD

The present invention relates to a control device for an internal combustion engine.

BACKGROUND ART

In recent years, in order to improve fuel efficiency of vehicles, it is necessary to reduce power consumption of vehicles. One of the means is to reduce a pressure of a fuel sent from a fuel tank to a fuel injection valve. That is, a valve closing force of the fuel injection valve is determined by the sum of an elastic force of an elastic body such as a spring that biases a valve body of the fuel injection valve in a valve closing direction and the pressure of the fuel. Accordingly, when the pressure of the fuel is reduced, driving power of the fuel injection valve can be reduced, which is effective in reducing the power consumption. Further, a supply pressure or friction of a fuel pump that sends a fuel from the fuel tank to the fuel injection valve can be reduced, and a seating noise generated at the time of valve closing can be also reduced by reducing the valve closing force of the fuel injection valve.

However, when the pressure of the fuel is reduced too much, the oil-tightness of the fuel injection valve decreases, and thus, there is a concern that fuel leakage may occur. Therefore, it is necessary to appropriately adjust the pressure of the fuel according to the valve closing force so that the valve closing force is not less than a valve closing force by which the oil-tightness of the fuel injection valve can be secured.

PTL 1 is known regarding a reduction of a drive current when a fuel injection valve is opened or closed. PTL 1 discloses a technique of detecting a collision of a movable core driven when the fuel injection valve is opened or closed by an in-cylinder pressure sensor that detects a pressure inside a cylinder in which the fuel injection valve is installed, and reducing a drive current according to a detection result.

CITATION LIST

Patent Literature

PTL 1: JP 2016-217180 A

SUMMARY OF INVENTION

Technical Problem

According to the technique disclosed in PTL 1, it is possible to detect the opening or closing of the fuel injection valve. However, it is not possible to appropriately adjust a pressure of a fuel according to a valve closing force of the fuel injection valve.

Therefore, the present invention is made inconsideration of the above-mentioned problems, and an object of the present invention is to appropriately adjust the pressure of the fuel according to the valve closing force of the fuel injection valve.

Solution to Problem

According to an aspect of the present invention, there is provided a control device for an internal combustion engine including: a fuel pressure control unit that controls a pressure of a fuel supplied to a fuel injection valve that injects the fuel to an internal combustion engine, in which the fuel injection valve has a valve body, a drive unit that drives the valve body, and a fuel injection hole that is opened or closed according to drive of the valve body, a cylinder pressure sensor that detects an in-cylinder pressure which is a pressure in a combustion chamber of the internal combustion engine is attached to the internal combustion engine, and the fuel pressure control unit controls the pressure of the fuel based on a pressure difference between the in-cylinder pressure detected by the cylinder pressure sensor before the valve body is separated from a valve seat and the in-cylinder pressure detected by the cylinder pressure sensor when the valve body is separated from the valve seat.

Advantageous Effects of Invention

According to the present invention, a pressure of a fuel can be appropriately adjusted according to a valve closing force of a fuel injection valve.

