An internal combustion engine system for a vehicle includes an internal combustion engine, ICE, operable on a low cetane fuel and having a cylinder at least partly defining a combustion chamber and an ignition source for the low cetane fuel; a fuel injector for injecting the low cetane fuel into the combustion chamber; an ignition improver device in fluid communication with the fuel injector and further configured to supply an ignition improver fluid to the low cetane fuel; a control unit configured to selectively operate the ICE in a spark ignition, SI, mode and a compression ignition, CI, mode. The control unit determines an ICE operating condition and controls the ignition improver device to supply a given amount of ignition improver fluid to the low cetane fuel on the basis of said determined ICE operating condition.

An engine operable in a premixed combustion system and a diffusion combustion system. The engine includes a main fuel injection valve, a pilot fuel injection valve, a liquid fuel tank, a main fuel supply path, a pilot fuel supply path, a pilot fuel filter, a pilot fuel high-pressure pump, a pilot fuel tank, and a pilot fuel supply pump. The pilot fuel tank stores pilot fuel sent from the pilot fuel high-pressure pump and not injected by the pilot fuel injection valve. This pilot fuel is sent to an automatic backwash filter and a pilot fuel filter while not passing through the liquid fuel tank.

A thermal choke, includes (1) a body, comprising a heat conductive material, (2) an electric heater, on or in the body, (3) a temperature sensor, on or in the body, and (4) a fin, in a channel surrounded by the body. The thermal choke is configured to fit between a throttle assembly and a cylinder of a spark ignition engine.

An engine operable in a premixed combustion system and a diffusion combustion system. The engine includes a main fuel injection valve, a pilot fuel injection valve, a liquid fuel tank, a main fuel supply path, a pilot fuel supply path, a pilot fuel filter, a pilot fuel high-pressure pump, a pilot fuel tank, and a pilot fuel supply pump. The pilot fuel tank stores pilot fuel sent from the pilot fuel high-pressure pump and not injected by the pilot fuel injection valve. This pilot fuel is sent to an automatic backwash filter and a pilot fuel filter while not passing through the liquid fuel tank.

An engine including a main fuel injection valve, a pilot fuel injection valve, a liquid fuel supply rail pipe, and a pilot fuel supply rail pipe. The main fuel injection valve supplies liquid fuel from the liquid fuel supply rail pipe to a combustion chamber during combustion in a diffusion combustion system. The pilot fuel injection valve supplies pilot fuel from the pilot fuel supply rail pipe to the combustion chamber in order to ignite gaseous fuel during combustion in a premixed combustion system. The liquid fuel supply rail pipe is disposed at one side of an imaginary vertical plane (P1) including an axis of a crank shaft. The pilot fuel supply rail pipe is disposed at the side of the imaginary vertical plane at which the liquid fuel supply rail pipe is disposed.

When the geometric compression ratio of an engine body is set to 13:1 or more and the engine body operates in a preset high load region, the effective compression ratio of the engine body is set to 12:1 or more with a difference from the geometric compression ratio being within 2, a gas to be introduced into a combustion chamber is supercharged by a supercharging system, fuel is injected at least in a compression stroke by an injector, and after the fuel injection is finished, an air-fuel mixture in the combustion chamber is ignited by an ignition device before the compression top dead center and is thus burned by flame propagation in the engine body, and then the unburned air-fuel mixture is burned by compression ignition.

When the geometric compression ratio of an engine body is set to 13:1 or more and the engine body operates in a preset high load region, the effective compression ratio of the engine body is set to 12:1 or more with a difference from the geometric compression ratio being within 2, a gas to be introduced into a combustion chamber is supercharged by a supercharging system, fuel is injected at least in a compression stroke by an injector, and after the fuel injection is finished, an air-fuel mixture in the combustion chamber is ignited by an ignition device before the compression top dead center and is thus burned by flame propagation in the engine body, and then the unburned air-fuel mixture is burned by compression ignition.

When an incremental amount of a steering angle exceeds a reference incremental amount, an ECU 60 executes vehicle attitude control of reducing an output torque of an engine, and, in a given operating range, drives a spark plug 16 in a manner allowing an air-fuel mixture to be self-ignited at a given timing, thereby executing SPCCI combustion. When there is a request for an additional deceleration from the vehicle attitude control (#12: YES), and the SPCCI combustion is performed (#13: YES), the ECU 60 executes fuel amount reduction control of reducing the amount of fuel to be supplied into a cylinder 2 (#14), so as to attain torque reduction for the vehicle attitude control. On the other hand, when the SPCCI combustion is not performed (#13: NO), the ECU 60 executes ignition retardation control of retarding an ignition timing of the spark plug 16 (#15).

When an incremental amount of a steering angle exceeds a reference incremental amount, an ECU 60 executes vehicle attitude control of reducing an output torque of an engine, and, in a given operating range, drives a spark plug 16 in a manner allowing an air-fuel mixture to be self-ignited at a given timing, thereby executing SPCCI combustion. When there is a request for an additional deceleration from the vehicle attitude control (#12: YES), and the SPCCI combustion is performed (#13: YES), the ECU 60 executes fuel amount reduction control of reducing the amount of fuel to be supplied into a cylinder 2 (#14), so as to attain torque reduction for the vehicle attitude control. On the other hand, when the SPCCI combustion is not performed (#13: NO), the ECU 60 executes ignition retardation control of retarding an ignition timing of the spark plug 16 (#15).

An engine including a main fuel injection valve, a pilot fuel injection valve, a liquid fuel supply rail pipe, and a pilot fuel supply rail pipe. The main fuel injection valve supplies liquid fuel from the liquid fuel supply rail pipe to a combustion chamber during combustion in a diffusion combustion system. The pilot fuel injection valve supplies pilot fuel from the pilot fuel supply rail pipe to the combustion chamber in order to ignite gaseous fuel during combustion in a premixed combustion system. The liquid fuel supply rail pipe is disposed at one side of an imaginary vertical plane including an axis of a crank shaft. The pilot fuel supply rail pipe is disposed at the side of the imaginary vertical plane at which the liquid fuel supply rail pipe is disposed.