An internal combustion engine comprising: a main combustion chamber comprising at least one intake valve and at least one exhaust valve, wherein at least one intake port fluidically connected to an intake manifold is configured to supply an air and/or an air-fuel-mixture to the main combustion chamber via the at least one intake valve, and a pre-chamber which is in fluid connection with the main combustion chamber, wherein the pre-chamber is in fluid connection with the intake port and/or the intake manifold through a supply line, wherein at least one fuel injector is configured to enrich the air and/or air-fuel-mixture supplied to the main combustion chamber to have a lower ignition delay than an air-fuel-mixture supplied to the pre-chamber and/or air or air-fuel-mixture can be supplied to the pre-chamber to have a higher ignition delay than an air-fuel-mixture supplied to the main combustion chamber.

A fuel supply controlling device includes: an auxiliary chamber fuel supply valve that supplies a gaseous fuel to an auxiliary chamber; a non-return valve between the auxiliary chamber fuel supply valve and the auxiliary chamber, the non-return valve blocking a reverse flow from the auxiliary chamber; a valve state detector that detects an operating state of the non-return valve; a rotation angle detector that detects a rotation angle within an engine cycle; and a controller that determines an operation command value of the auxiliary chamber fuel supply valve. The controller measures an actual operating state of the non-return valve based on signals from the valve state detector and the rotation angle detector in association with the detected rotation angle, and corrects the operation command value of the auxiliary chamber fuel supply valve such that the measured actual operating state is brought close to a target operating state.

An internal combustion engine comprising: a main combustion chamber comprising at least one intake valve and at least one exhaust valve, wherein at least one intake port fluidically connected to an intake manifold is configured to supply an air and/or an air-fuel-mixture to the main combustion chamber via the at least one intake valve, and a pre-chamber which is in fluid connection with the main combustion chamber, wherein the pre-chamber is in fluid connection with the intake port and/or the intake manifold through a supply line, wherein at least one fuel injector is configured to enrich the air and/or air-fuel-mixture supplied to the main combustion chamber to have a lower ignition delay than an air-fuel-mixture supplied to the pre-chamber and/or air or air-fuel-mixture can be supplied to the pre-chamber to have a higher ignition delay than an air-fuel-mixture supplied to the main combustion chamber.