Multiple combustion mode engine with ammonia fuel and control method thereof
Disclosed is a multiple combustion mode engine with ammonia fuel including an cylinder head, a cylinder sleeve, a piston, a main combustion chamber, an inlet valve and an exhaust valve, and further including a jet ignition device arranged on the cylinder head and used for providing an ignition source for the main combustion chamber, and an ammonia injector used for providing ammonia/air mixture gas for the main combustion chamber. Also disclosed is a control method of the multiple combustion mode engine with ammonia fuel. The time sequence of ammonia injection of the main combustion chamber and jet flame generation of the pre-chamber is controlled, the mixed state of the fuel/air in the main combustion chamber before ignition can be controlled, and finally different combustion modes, i.e. a premixed combustion mode and a diffusion combustion mode, are formed in the main combustion chamber.
1. A control method of a multiple combustion mode engine with ammonia fuel, comprising:
a premixed combustion mode: under starting, idling and small-load working condition of the engine, upon predetermining a first timing when a jet flame of a pre-chamber comprised in the engine is generated, enabling a second timing when an ammonia injector comprised in the engine injects ammonia gas in a main combustion chamber comprised in the engine to be earlier than the first timing when the jet flame of the pre-chamber is generated in the main combustion chamber; mixing the ammonia gas entering the main combustion chamber with air in the main combustion chamber to form homogeneous premixed gas; under a compression action of a piston comprised in the engine, igniting the homogeneous premixed gas by the jet flame of the pre-chamber near a top dead center of the compression stroke of the engine, spreading and developing a flame of the homogeneous premixed gas, and completing a combustion process by the engine; and
a diffusion combustion mode: upon the engine operating under middle-or-high load working condition, injecting the ammonia gas to the main combustion chamber near the top dead center of the compression stroke of the engine by the ammonia injector; enabling the second timing when the ammonia injector injects the ammonia gas to be slightly later than the first timing when the jet flame of the pre-chamber is generated, or injecting the ammonia gas by the ammonia injector at the first timing when the jet flame of the pre-chamber is generated; and synchronously performing injection of the ammonia gas in the main combustion chamber and mixture of the ammonia gas injected by the ammonia injector with the air in the main combustion chamber, wherein the ammonia gas and the air in the main combustion chamber are in a non-premixed state.
2. The control method of a multiple combustion mode engine with ammonia fuel according to claim 1 , before the jet flame of the pre-chamber is generated, the method further comprising adjusting gas in the pre-chamber to be equivalent mixed gas, wherein adjusting gas in the pre-chamber to be equivalent mixed gas comprises:
allowing gas in the main combustion chamber to enter the pre-chamber through a jet hole comprised in the engine; in response to an excess air coefficient of mixed gas in the main combustion chamber being smaller than 1, forming first mixed gas that is over-rich in the pre-chamber, injecting fresh air into the pre-chamber by an air injector of a jet ignition device comprised in the engine until the first mixed gas in the pre-chamber is the equivalent mixed gas; and
in response to the excess air coefficient of the mixed gas in the main combustion chamber being larger than 1, leaving the air injector not work, and injecting fuel into the pre-chamber by a fuel injector comprised in the engine to increase concentration of second mixed gas in the pre-chamber until the second mixed gas in the pre-chamber is the equivalent mixed gas.