[Problem] To provide, in an engine provided with two cylinder rows, a technology that, while suppressing a cost increase, can suppress a difference in combustion performance between the cylinder rows.

[Solution] An exemplary engine includes: a first cylinder row having plural cylinders arranged in a front and rear direction; a second cylinder row arranged parallel to the first cylinder row; plural first injectors provided for the respective cylinders of the first cylinder row, plural second injectors provided for respective cylinders of the second cylinder row; and a fuel pump having a first discharge port to discharge a fuel to the plural first injectors and a second discharge port to discharge a fuel to the plural second injectors. The fuel pump is placed between the first cylinder row and the second cylinder row in a plan view from an up and down direction.

A fuel injection control device includes processing circuitry, which executes an estimating process to estimate pressure in first and second fuel storage members connected to first and second fuel injection valves. The estimating process includes: estimating the pressure in the first fuel storage member based on a detection value of a pressure sensor that detects the pressure in the first fuel storage member and a cycle of pulsation in the first fuel storage member, which is determined in accordance with an interval of fuel injections in a first bank; and estimating the pressure in the second fuel storage member by assuming that a phase of a periodic fluctuation of the pressure in the second fuel storage member and a phase of a periodic fluctuation of the pressure in the first fuel storage member are in antiphase.

An electronic control unit is configured to switch a drive mode of a first high-pressure fuel pump and a second high-pressure fuel pump, in accordance with an operating state of an internal combustion engine, either to a twin-drive mode, in which both the first high-pressure fuel pump and the second high-pressure fuel pump are driven, or to a single-drive mode, in which either one of the first high-pressure fuel pump and the second high-pressure fuel pump is driven. The electronic control unit is configured to determine whether or not a pump ambient temperature, which is the ambient temperature of the first high-pressure fuel pump and the second high-pressure fuel pump, is equal to or higher than a predetermined first temperature. In a case where the pump ambient temperature is equal to or higher than the first temperature, the electronic control unit turns ON a twin-drive mode request flag.

A multi-cylinder engine includes a plurality of cylinders that are fired at uneven intervals. A controller is configured or programmed to overlap a time period that a plunger increases a pressure in a pressurizing chamber and a time period that an electromagnetic valve remains opened in at least the longest one of the intervals at which the firing is conducted in the plurality of cylinders.

A fuel injection control device includes processing circuitry, which executes an estimating process to estimate pressure in first and second fuel storage members connected to first and second fuel injection valves. The estimating process includes: estimating the pressure in the first fuel storage member based on a detection value of a pressure sensor that detects the pressure in the first fuel storage member and a cycle of pulsation in the first fuel storage member, which is determined in accordance with an interval of fuel injections in a first bank; and estimating the pressure in the second fuel storage member by assuming that a phase of a periodic fluctuation of the pressure in the second fuel storage member and a phase of a periodic fluctuation of the pressure in the first fuel storage member are in antiphase.

A valve assembly for a fuel pump is disclosed. In certain aspect, the valve assembly includes a housing defining a valve chamber, a valve inlet in fluid communication with the valve chamber, a valve outlet in fluid communication with the valve chamber, a valve seat; a valve body movably disposed within the valve chamber, a retainer sealingly engaging the housing and defining a cavity between the base portion of the valve body and the retainer, wherein the retainer comprises one or more control orifices formed therein and configured to provide fluid communication to the cavity to regulate a position of the valve body based on at least a pressure difference between the valve chamber and the cavity, and a spring member disposed between the retainer and the valve body, wherein the spring member is configured to bias the valve body.

A valve assembly for a fuel pump is disclosed. In certain aspect, the valve assembly includes a housing defining a valve chamber, a valve inlet in fluid communication with the valve chamber, a valve outlet in fluid communication with the valve chamber, a valve seat; a valve body movably disposed within the valve chamber, a retainer sealingly engaging the housing and defining a cavity between the base portion of the valve body and the retainer, wherein the retainer comprises one or more control orifices formed therein and configured to provide fluid communication to the cavity to regulate a position of the valve body based on at least a pressure difference between the valve chamber and the cavity, and a spring member disposed between the retainer and the valve body, wherein the spring member is configured to bias the valve body.