Abstract: A controller is used for an internal combustion engine including a cylinder and a direct injection valve that injects gaseous fuel into the cylinder. A CPU of the controller executes acquisition of an in-cylinder pressure that is a pressure in the cylinder during one combustion cycle and a supply fuel pressure that is a pressure of the gaseous fuel supplied to the direct injection valve, and calculation of a backflow rate that is an amount of combustion gas flowing into the direct injection valve from the cylinder during one combustion cycle of the cylinder. In the calculation of the backflow rate, the CPU calculates the backflow rate such that the backflow rate becomes larger as the in-cylinder pressure increases and the backflow rate becomes larger as the supply fuel pressure decreases.

Abstract: An internal combustion engine includes an asynchronous injection valve configured to inject water into an intake port when one or more intake valves are closed and a synchronous injection valve configured to inject water into the intake port when the one or more intake valves are open. The asynchronous injection valve and the synchronous injection valve are configured to have injection characteristics that are different between the asynchronous injection valve and the synchronous injection valve.

Abstract: A controller for an internal combustion engine is configured to calculate a water collection amount based on a temperature of intake air flowing through an intake passage, the water collection amount being an amount of water that collects on a wall surface of the intake passage, cause a water injection valve to inject water to the intake passage when an intake valve is open, and cause the water injection valve to inject water when the intake valve is closed in addition to when the intake valve is open in a case in which the water collection amount is less than a specified value that has been defined in advance.

Abstract: A guiding portion of an intake valve head includes a specific tangent line, which, when the intake valve is in a fully open state, intersects with at least one selected from an ignition plug and a closed exhaust valve. A line segment that agrees with a tangent line contacting the guiding portion and extends from a contact point of the tangent line with the guiding portion to an intersection point of the tangent line with a central axis of the head is defined as a first line segment, a line segment that agrees with the central axis and extends from the intersection point toward the intake passage is defined as a second line segment, and an angle formed by the first second line segments is defined as a specific angle. The tangent line that minimizes the specific angle is the specific tangent line.

Abstract: A controller for an internal combustion engine is configured to execute: a pressure calculation process that calculates pressure of gas in a crank chamber based on a running state of the internal combustion engine; a first injection process that causes a water injection valve to inject a first injection amount of water when an intake valve is open; and a second injection process that causes the water injection valve to inject a second injection amount of water when the intake valve is closed. The controller is further configured to set a ratio of the first injection amount to a sum of the first injection amount and the second injection amount to a smaller value when the pressure is greater than or equal to a specified value than when the pressure is less than the specified value.

Abstract: A guiding portion of an intake valve head includes a specific tangent line, which, when the intake valve is in a fully open state, intersects with at least one selected from an ignition plug and a closed exhaust valve. A line segment that agrees with a tangent line contacting the guiding portion and extends from a contact point of the tangent line with the guiding portion to an intersection point of the tangent line with a central axis of the head is defined as a first line segment, a line segment that agrees with the central axis and extends from the intersection point toward the intake passage is defined as a second line segment, and an angle formed by the first second line segments is defined as a specific angle. The tangent line that minimizes the specific angle is the specific tangent line.

Abstract: A controller for an internal combustion engine is configured to execute a first injection process that causes a water injection valve to inject water when an intake valve is open and a second injection process that causes the water injection valve to inject water when the intake valve is closed. The controller is further configured to set a pressure of the water supplied to the water injection valve to be higher in the second injection process than in the first injection process.

Abstract: An engine includes water injection valves that inject water to intake ports connected to a cylinder. A controller for the engine is configured to selectively execute, for each of the intake ports, a synchronous injection that causes the water injection valve to inject water only during a valve opening period of the intake valve and an asynchronous injection that causes the water injection valve to inject water during a valve closing period of the intake valve. The controller is configured to perform, when executing a synchronous/asynchronous concurrent injection in which the intake ports includes an intake port in which the synchronous injection is executed and an intake port in which the asynchronous injection is executed, a switching process of switching the intake port in which the asynchronous injection is executed.

Abstract: An engine controller, an engine control method, and a storage medium are provided. An intake valve closes after a compression stroke starts. One of a predetermined period before the compression stroke starts and a predetermined period after the intake valve closes is a first injection period and the other one is a second injection period. A pre-ignition prevention injection process controls an injector such that fuel corresponding to a requested injection amount is injected by dividing an injection period into the first injection period and the second injection period when a period required for fuel injection corresponding to the requested injection amount is longer than the first injection period.

Abstract: A controller for an internal combustion engine is configured to execute: a pressure calculation process that calculates pressure of gas in a crank chamber based on a running state of the internal combustion engine; a first injection process that causes a water injection valve to inject a first injection amount of water when an intake valve is open; and a second injection process that causes the water injection valve to inject a second injection amount of water when the intake valve is closed. The controller is further configured to set a ratio of the first injection amount to a sum of the first injection amount and the second injection amount to a smaller value when the pressure is greater than or equal to a specified value than when the pressure is less than the specified value.

Abstract: A controller for an internal combustion engine is configured to calculate a water collection amount based on a temperature of intake air flowing through an intake passage, the water collection amount being an amount of water that collects on a wall surface of the intake passage, cause a water injection valve to inject water to the intake passage when an intake valve is open, and cause the water injection valve to inject water when the intake valve is closed in addition to when the intake valve is open in a case in which the water collection amount is less than a specified value that has been defined in advance.

Abstract: A controller for an internal combustion engine is configured to execute a first injection process that causes a water injection valve to inject water when an intake valve is open and a second injection process that causes the water injection valve to inject water when the intake valve is closed. The controller is further configured to set a pressure of the water supplied to the water injection valve to be higher in the second injection process than in the first injection process.

Abstract: An internal combustion engine includes an asynchronous injection valve configured to inject water into an intake port when one or more intake valves are closed and a synchronous injection valve configured to inject water into the intake port when the one or more intake valves are open. The asynchronous injection valve and the synchronous injection valve are configured to have injection characteristics that are different between the asynchronous injection valve and the synchronous injection valve.

Abstract: An engine includes water injection valves that inject water to intake ports connected to a cylinder. A controller for the engine is configured to selectively execute, for each of the intake ports, a synchronous injection that causes the water injection valve to inject water only during a valve opening period of the intake valve and an asynchronous injection that causes the water injection valve to inject water during a valve closing period of the intake valve. The controller is configured to perform, when executing a synchronous/asynchronous concurrent injection in which the intake ports includes an intake port in which the synchronous injection is executed and an intake port in which the asynchronous injection is executed, a switching process of switching the intake port in which the asynchronous injection is executed.

Abstract: A protector protects a high-pressure fuel pump for an internal combustion engine. A metal collar is insert-molded into a plate-shaped fiber reinforced plastic portion made of a fiber reinforced plastic of the protector. An outer circumferential surface of the collar includes an uneven portion and a smooth surface. The uneven portion includes recesses and projections arranged alternately in a thickness direction of the fiber reinforced plastic portion. The smooth portion includes a smooth surface parallel to the thickness direction of the fiber reinforced plastic portion. The uneven portion and the smooth portion are arranged in the thickness direction on the outer circumferential surface of the collar.

Abstract: A protector protects a high-pressure fuel pump of an internal combustion engine. The protector and the high-pressure fuel pump are fastened to an engine body by a bolt inserted through a metal collar. The protector further includes an elastic insulating layer located between the collar and a carbon fiber reinforced plastic portion. The collar is embedded in the carbon fiber reinforced plastic portion with the insulating layer compressed.

Abstract: A high-pressure fuel pump and a protector are coupled to an outer side of an engine body of an internal combustion engine. A wall plate surrounds the high-pressure fuel pump to protect the high-pressure fuel pump. A cover of the high-pressure fuel pump has a flange. The engine body has a mounting surface. The bottom plate and the flange are fastened to the mounting surface by a bolt with the bottom plate held between the flange and the mounting surface.

Abstract: A fuel pipe includes a tubular header pipe and a socket coupled to the header pipe and supplied with fuel from the header pipe. The header pipe and the socket form a joining portion therebetween. The joining portion is shaped to be elongated in a first direction. The joining portion includes a communication hole that connects an inner region of the header pipe and an inner region of the socket. The communication hole is an elongated hole elongated in the first direction.

Abstract: A protector protects a high-pressure fuel pump for an internal combustion engine. A metal collar is insert-molded into a plate-shaped fiber reinforced plastic portion made of a fiber reinforced plastic of the protector. An outer circumferential surface of the collar includes an uneven portion and a smooth surface. The uneven portion includes recesses and projections arranged alternately in a thickness direction of the fiber reinforced plastic portion. The smooth portion includes a smooth surface parallel to the thickness direction of the fiber reinforced plastic portion. The uneven portion and the smooth portion are arranged in the thickness direction on the outer circumferential surface of the collar.

Abstract: A high-pressure fuel pump and a protector are coupled to an outer side of an engine body of an internal combustion engine. A wall plate surrounds the high-pressure fuel pump to protect the high-pressure fuel pump. A cover of the high-pressure fuel pump has a flange. The engine body has a mounting surface. The bottom plate and the flange are fastened to the mounting surface by a bolt with the bottom plate held between the flange and the mounting surface.