Internal combustion engine with external circulation system and working method thereof

A method of operating the internal combustion engine with an external circulation system, wherein the external circulation system includes:

• the external circulation system communicated with an intake port and an exhaust port of the internal combustion engine;
• the external circulation system comprises:
• an intake heating assembly, an exhaust assembly, and a connecting assembly;
• the intake heating assembly is communicated with the intake port of the internal combustion engine and/or the connecting assembly through connecting pipelines;
• the intake heating assembly comprises a heater, a fan, an air filter, and an intake connecting pipeline group communicated with an outlet of the fan;
• the fan is communicated with the intake port of the internal combustion engine and/or the connecting assembly through the intake connecting pipeline group;
• the exhaust assembly includes an exhaust after-treatment device and has an exhaust pipe communicated with the exhaust port of the internal combustion engine;
• a gas output by the intake heating assembly and/or the exhaust port of the internal combustion engine is discharged through the exhaust pipe of the exhaust assembly;
• and
• the connecting assembly comprises a connecting assembly pipeline and a first flow regulation valve disposed in the connecting assembly pipeline, and the connecting assembly is connected to the intake heating assembly and the exhaust assembly,
• wherein an output of the heater is connected to the intake port and to the connecting assembly pipeline, wherein the connecting assembly pipeline bypasses the engine and couples the output of the heater to a catalyst of the exhaust after-treatment device, and wherein the connecting assembly pipeline includes the first flow regulation valve between the output of the heater and the catalyst;
• the heater is an electric heater, the internal combustion engine with the external circulation system further comprises a second flow regulation valve and a third flow regulation valve and wherein the method comprises:
• while the engine is not running, opening the electric heater and fully opening the first flow regulation valve;
• after a temperature of the electric heater reaches a temperature configured for igniting a fuel injected by a fuel injector, injecting the fuel by the fuel injector such that the fuel starts to combust due to the temperature of the electric heater, and such that the temperature of the electric heater and a temperature of an intake oxidation catalyst are increased by heat released from the fuel;
• opening the fan to feed circulating air while injecting the fuel, wherein an amount of the circulating air fed is adapted to an amount of the fuel injected, and wherein under an action of continuous electric heating and fuel combustion, an intake temperature of the engine rises, and a temperature of the catalyst of the exhaust after-treatment device continuously increases causing the engine to start to run;
• before the engine starts, closing the third flow regulation valve and opening the electric heater;
• while the fuel injector injects the fuel, opening the fan for air supply, wherein an air volume of the fan facilitates the fuel combustion, and the fuel in a combusted gas formed after said continuous electric heating and the fuel combustion is sufficiently oxidized by the intake oxidation catalyst to release heat that raises a gas temperature of the gas;
• while engine is not running, entering, by the combusted gas, the exhaust pipe of the external circulation system through the first flow regulation valve to reach the exhaust after-treatment device such that the catalyst of the exhaust after-treatment device is heated;
• raising a temperature of air reaching the connecting assembly pipeline, wherein the engine starts to run when the temperature of the air reaching the connecting assembly pipeline reaches a first preset temperature, and the first flow regulation valve is closed;
• after the engine runs for a plurality of cycles and a temperature of an exhaust gas discharged from the engine reaches a second preset temperature injecting the fuel at an end of a compression stroke in a cylinder of the engine;
• after the engine starts up and runs and the temperature of the exhaust gas discharged from the exhaust port of the engine further raises, passing the exhaust gas through the exhaust pipe to reach the exhaust after-treatment device for a treatment, opening the third flow regulation valve and closing the second flow regulation valve;
• passing intake air through a heat exchanger such that the intake air is heated by exhaust in the heat exchanger to obtain heated air, and
• passing the heated air through a pipeline so that the heated air reaches the electric heater;
• in response to a temperature of air passing through a first intake connecting pipeline having reached or exceeded the first preset temperature, stopping heating by the electric heater such that the intake temperature of the engine reaches the first preset temperature due to exhaust of the engine to heat the intake air;
• adjusting a heating effect of the exhaust of the engine on the intake air by delaying a fuel injection start time to regulate an exhaust temperature so that the gas temperature of the gas that reaches the intake port of the engine is maintained above the first preset temperature;
• after the low compression ratio engine enters a predetermined load state, fully or partially closing the third flow regulation valve and opening the second flow regulation valve to regulate the intake temperature so that the intake temperature is maintained at the first preset temperature;
• before the engine is started, and after the electric heater is opened, the first flow regulation valve is fully opened and the fan is opened, said injecting, by the fuel injector, includes injecting the fuel onto a surface of the electric heater, such that the fuel combusts and is oxidized by the intake oxidation catalyst, which is adjacent to the electric heater, such that the fuel completely combusts or is oxidized to release heat that raises a temperature of the intake air, and
• controlling a flow rate of the intake air by an operation of the fan;
• heating the intake air by the electric heater and by the heat released from the fuel completely combusting or from oxidation of the fuel by the intake oxidation catalyst to form the exhaust gas, wherein the passing the exhaust case includes passing the exhaust gas through the first flow regulation valve and the exhaust pipe to reach the exhaust after-treatment device for heating of the exhaust gas;
• and
• when the temperature of the catalyst of the exhaust after-treatment device reaches a treatment temperature for treating a product in the exhaust gas discharged from the engine, stopping injecting of the fuel by the fuel injector and closing the first flow regulation valve.