Ignition-mode-variable diesel/natural gas dual-fuel engine and control method thereof

Abstract

The invention discloses an ignition-mode-variable diesel / natural gas dual-fuel engine. The engine is provided with an air inlet valve and an exhaust valve. An original diesel injecting system is not changed, a spark plug igniting system is newly added, and a spark plug installing hole is reserved in a cylinder cover. A spark plug is in threaded connection with a cylinder, and the spark plug and a diesel injector are oppositely arranged relative to the center of the cylinder. An engine electronic control unit judges the work condition of the engine according to the opening degree of a throttle valve; when it is judged that the work condition of the engine is in a low-load state, the electronic control unit transmits a signal to an ignition controller, the spark plug is controlled to perform ignition, and natural gas mixtures in the cylinder are ignited; when it is judged that the work condition of the engine is in the high-load state, the electronic control unit performs calculation, controls the diesel injector to inject diesel and controls the injection amount, the diesel is compressed so that multi-point ignition can be achieved, and the natural gas mixtures in the cylinder are ignited.

Description

technical field [0001] The invention relates to an engine, in particular to a diesel / natural gas dual-fuel engine with two ignition modes of spark plug ignition and diesel ignition and a variable control method for the ignition mode. Background technique [0002] Due to the high compression ratio, multiple ignition points, and rapid combustion, the diesel-ignited natural gas engine has the economical advantages of low fuel consumption rate, but under the condition of small load and lean mixture, the cylinder pressure is low, the combustion temperature is low, the thermal efficiency is low, and the HC emission is high. This results in deterioration of the engine's economy and emissions. [0003] If all diesel fuel is used under low-load conditions, there will be a process of switching from all-diesel conditions to dual-fuel conditions. Due to the lag in fuel supply, the engine speed fluctuates greatly during this process and the emissions deteriorate, making it difficult to m...

AI Technical Summary

Problems solved by technology

[0002] Due to the high compression ratio, multiple ignition points, and rapid combustion, the diesel-ignited natural gas engine has the economical advantages of low fuel consumption rate, but under the condition of small load and lean mixture, the cylinder pressure is low, the combustion temperature is low, the thermal efficiency is low, and the HC emission is high. This results in deterioration of the engine's economy and emissions

[0003] If all diesel fuel is used under low-load conditions, there will be a process of switching from all-diesel conditions to dual-fuel conditions. Due to the lag in fuel supply, the engine speed fluctuates greatly during this process and the emissions deteriorate, making it difficult to meet future higher requirements. The requirements of economic and emission regulations and the improvement of natural gas substitution rate at low and medium loads

[0004] If only natural gas is used as fuel, although the spark ignition lean-burn natural gas engine can form a leaner combustible mixture, which is beneficial to improve fuel economy and emissions by using lean combustion, but the combustion cycle change is the problem faced by the natural gas engine when burning a lean mixture. The main problem is that it will affect the combustion efficiency and emissions of lean-burn natural gas engines to a certain extent

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