Control system and control method of oil-air dual-fuel engine supplied by mechanical pump

Abstract

The invention discloses a control system and method of an oil and gas dual-fuel engine with oil supplied by a mechanical pump. The control system comprises a sensor part, an executor and a dual-fuel ECU which collects signals of the sensor part and controls the executor to operate. According to the control system, the diesel oil amount is controlled through the accelerator executor, the fuel gas amount is controlled through a fuel gas control nozzle, the air inlet amount is controlled through an electronic throttle body, and the work air-fuel ratio of the engine is controlled through detection of a universal exhaust gas oxygen sensor and closed-loop feedback control. According to the control method, the engine can be switched between a pure fuel oil work mode and a fuel oil/fuel gas dual-fuel work mode, the engine is controlled to operate well, the jet amount of diesel oil can be precisely controlled according to the different work states of the diesel engine, meanwhile, the jet moment and jet duration of gas fuel, the air inlet amount and the air-fuel ratio can be controlled, and therefore safe and smooth operating of the dual-fuel engine is guaranteed, fuel consumption is reduced, and tail gas emissions are reduced.

Description

technical field [0001] The invention belongs to the technical field of engine control, and in particular relates to a control system and a control method of an oil-air dual-fuel engine supplied by a mechanical pump. Background technique [0002] With the increasingly tense oil resources, the world's fuel prices have soared again and again, and my country's oil prices have also risen again and again. Gas fuels such as natural gas, which are abundant in the earth, have a price advantage compared with gasoline and diesel, and have better environmental protection. Its use can effectively reduce the cost of using diesel engines, alleviate energy shortages, and solve problems such as emission pollution. Therefore, it is necessary to develop gas fuel engines. And diesel / gas fuel dual-fuel engine (abbreviation oil-gas dual-fuel engine) is exactly a kind of gas fuel engine. Existing diesel / gas fuel dual fuel engines, such as diesel / natural gas dual fuel engines and diesel / liquefied p...

AI Technical Summary

Problems solved by technology

Existing diesel / gas fuel dual fuel engines, such as diesel / natural gas dual fuel engines and diesel / liquefied petroleum gas (LPG) dual fuel engines, are usually equipped with gas fuel control systems on the basis of diesel engines and diesel electronic control systems And obtain, there are three aspects problems usually in this engine, the one, the control problem of pilot diesel oil quantity, usually the pilot fuel quantity of mechanical pump control accounts for 20~30% of total fuel quantity, promptly requires to pass the control of mechanical pump The fuel injection quantity makes it work in a state of small fuel quantity, and the stability of the fuel quantity control of the mechanical pump working in this state is very poor, so the change of the pilot fuel quantity will affect the stability, reliability and performance of the dual-fuel engine. , in order to improve this situation, it is necessary to increase the amount of pilot fuel, and increasing the amount of pilot fuel means reducing the diesel substitution rate, and reducing the substitution rate means reducing the fuel economy performance of the engine; Compared with the original diesel engine, after the engine burns gaseous fuel, there is no evaporation and heat absorption process in the cylinder of the gaseous fuel, and some gaseous fuels such as natural gas have a slow burning speed, resulting in post-combustion, and the compression ratio of the dual-fuel engine generally remains higher than that of the original diesel engine. Compression ratio, these factors lead to high heat load of dual-fuel engine and affect the life of the engine; third, some gaseous fuels such as natural gas have high methane emissions. For example, the main component of natural gas is methane, and the ignition temperature of methane is about 630 ℃, which is much higher It is higher than 260°C of diesel, and when the dual-fuel engine is partially loaded, the mixture in the cylinder is relatively lean, and the temperature in the cylinder is low, which leads to the inability of methane in some low-temperature areas to burn, resulting in high methane emissions, and causing methane waste and affecting the engine. economic performance

The use of electronically controlled unit pumps and common rail technology can optimize fuel injection timing and pilot injection volume compared with mechanical pumps, improve the stability of pilot fuel volume control, and improve performance. However, the above-mentioned latter two problems still exist and affect engine operation. Safety and reliability, while increasing fuel consumption and exhaust emissions

Images