An internal combustion engine includes a crankcase that defines a crank chamber, a crankshaft that has a crank housed in the crank chamber and is rotatably supported on the crankcase, a cylinder block that is joined to the crankcase and defines a plurality of cylinders in a horizontally-opposed arrangement, a to-be-detected body that rotates integrally with the crankshaft, and a detection sensor that extends through the crankcase from an upper face of the crankcase, is made to face a trajectory of the to-be-detected body, and generates a pulse signal in response to movement of the to-be-detected body. Thus, in a so-called horizontally-opposed internal combustion engine, a structure for disposing a detection sensor that can detect the angular velocity of a crankshaft with high precision is provided.

An engine includes an engine block with at least one cylinder bank including cylinder bores formed therein. A piston is reciprocatingly disposed in each of the cylinder bores. A crankshaft is rotatably mounted to the engine block. Connecting rods are rotatably attached to the crankshaft and are coupled to the piston. A cylinder head with intake valves and exhaust valves in fluid communication with the cylinder bores is mounted to each cylinder bank. At least one permanent magnet is disposed in a skirt of each piston. At least one electromagnet is positioned adjacent to the permanent magnet(s). A control system selectively provides an electrical current to the electromagnets to produce a desired magnetic field, wherein the magnetic field of the electromagnets cooperates with a magnetic field of the permanent magnets to affect a motion of the piston in respect of the engine block.

An engine includes an engine block with at least one cylinder bank including cylinder bores formed therein. A piston is reciprocatingly disposed in each of the cylinder bores. A crankshaft is rotatably mounted to the engine block. Connecting rods are rotatably attached to the crankshaft and are coupled to the piston. A cylinder head with intake valves and exhaust valves in fluid communication with the cylinder bores is mounted to each cylinder bank. At least one permanent magnet is disposed in a skirt of each piston. At least one electromagnet is positioned adjacent to the permanent magnet(s). A control system selectively provides an electrical current to the electromagnets to produce a desired magnetic field, wherein the magnetic field of the electromagnets cooperates with a magnetic field of the permanent magnets to affect a motion of the piston in respect of the engine block.

An internal combustion engine condition determination apparatus includes a storage device; and an execution device. The storage device stores mapping data that defines a mapping. The execution device is configured to execute an acquisition process of acquiring an internal combustion engine state variable every time a crankshaft of an internal combustion engine rotates by a predetermined angle, and a determination process of determining a condition of the internal combustion engine based on an output obtained through the mapping using the internal combustion engine state variable as an input. The mapping data is trained by machine learning. The execution device is configured to prohibit the determination process when a rotation speed of the crankshaft is equal to or higher than a predetermined threshold.

An internal combustion engine condition determination apparatus includes a storage device; and an execution device. The storage device stores mapping data that defines a mapping. The execution device is configured to execute an acquisition process of acquiring an internal combustion engine state variable every time a crankshaft of an internal combustion engine rotates by a predetermined angle, and a determination process of determining a condition of the internal combustion engine based on an output obtained through the mapping using the internal combustion engine state variable as an input. The mapping data is trained by machine learning. The execution device is configured to prohibit the determination process when a rotation speed of the crankshaft is equal to or higher than a predetermined threshold.

A multi-cylinder internal combustion engine is configured to perform an all-cylinder operation and a partial-cylinder operation. The ignition timing controller executes a process that sets a knock control amount and a knock learning value, a process that determines whether knocking is occurring, a process that updates a value of the knock control amount in accordance with whether knocking is occurring, a process that updates the knock learning value such that the knock learning value gradually approaches a knock control operated amount, a process that operates ignition timing of each cylinder based on the knock control amount and the knock learning value, and a process that limits update of the knock learning value such that a followability of the knock learning value to the knock control operated amount is lower during the partial-cylinder operation than during the all-cylinder operation.

A multi-cylinder internal combustion engine is configured to perform an all-cylinder operation and a partial-cylinder operation. The ignition timing controller executes a process that sets a knock control amount and a knock learning value, a process that determines whether knocking is occurring, a process that updates a value of the knock control amount in accordance with whether knocking is occurring, a process that updates the knock learning value such that the knock learning value gradually approaches a knock control operated amount, a process that operates ignition timing of each cylinder based on the knock control amount and the knock learning value, and a process that limits update of the knock learning value such that a followability of the knock learning value to the knock control operated amount is lower during the partial-cylinder operation than during the all-cylinder operation.

When a performance flag of a temperature raising process becomes “1”, a CPU increases an injection amount for first, third and fourth cylinders from a base injection amount for making an air-fuel ratio of an air-fuel mixture equal to a theoretical air-fuel ratio, by an increase amount, and stops combustion control in a second cylinder. The CPU gradually increases a ratio of the increase amount to the base injection amount, at the start of the temperature raising process.

When a performance flag of a temperature raising process becomes “1”, a CPU increases an injection amount for first, third and fourth cylinders from a base injection amount for making an air-fuel ratio of an air-fuel mixture equal to a theoretical air-fuel ratio, by an increase amount, and stops combustion control in a second cylinder. The CPU gradually increases a ratio of the increase amount to the base injection amount, at the start of the temperature raising process.

Methods and systems are provided for detection of cylinder misfire in an engine. In one example, a system may comprise a first cylinder and second cylinder of the engine having exhaust flows combined together in an exhaust system before being combined with other cylinders of the engine. The first cylinder and second cylinder may share an exhaust gas sensor mounted in the exhaust in a position to sense exhaust from the first cylinder and second cylinder, and being positioned before exhaust from other cylinders is combined with sensed exhaust from the first cylinder and second cylinder. The system may further include a control system with instructions stored therein to indicate detected misfire in one or more of the first and second sensors based on an output from the exhaust gas sensor.