Electric-controlled natural gas engine operating system and control method thereof

Abstract

The invention provides a working system of an electrically controlled natural gas engine. A natural gas supply system comprises a natural gas storage tank, a switch electromagnetic valve and a pressure reducing valve which are connected in turn, and a natural gas introducing device introduces natural gas into a gas intake manifold; the natural gas introducing device is an electronic adjusting valve or an ejector and is controlled by an ECU; the ECU comprises a natural gas introducing control program, an ignition control program and an idle speed control program; in addition, a gas storage tank with function of stabilizing pressure is arranged between the pressure reducing valve and the ejector, so that the natural gas engine and an electronic control system thereof run more stably; the control of the natural gas introducing amount is achieved through the control of output pulse width; a self-absorption system has the advantages of stable performance and lower cost, and is comparatively suitable for refit of old gasoline engines and diesel engines; and a direct injection type system has the advantages of good performance, good acceleration performance and high efficiency, and can meet higher discharge normative requirement.

Description

technical field [0001] The invention belongs to the technical field of automobile electronics, and relates to an electronically controlled natural gas engine working system and a control method thereof. Background technique [0002] The main component of natural gas is CH4, which is a high-quality clean fuel. Natural gas can be used without complicated refining process and additives during production, so the price is definitely cheaper than gasoline and diesel; the worldwide shortage of oil resources makes the operation of gasoline and diesel vehicles Costs are increasing; while natural gas is easy to achieve complete combustion, its emissions are much lower than gasoline or diesel. Natural gas is therefore a fuel with many advantages. Exhaust gas from fuel vehicles is an important cause of increasing air pollution. In large and medium-sized cities, 70% of air pollution comes from vehicles. The outstanding advantage of natural gas is that it burns very completely, and the ...

AI Technical Summary

Problems solved by technology

There are two types of regulating valves, one is a manual regulating valve, which cannot be changed during operation after one-time adjustment, because the air intake volume changes greatly under different working conditions when the vehicle is running, and the natural gas entering through the fixed valve cannot It is adjusted with the intake air volume, so that only a suitable "air-fuel ratio" can be formed at a certain point. In most working conditions, it is either too lean or too rich, and the gas consumption, power, and emissions are not good.

The other is to use an electronic regulating valve to control the flow, but because the inertia of the regulating valve cannot follow the change of the throttle opening in time, and because of the change of the negative pressure of the intake manifold (the negative pressure varies with the engine speed and the throttle opening The change of two variables) is not detected, and the pressure formed at the outlet of the regulating valve is constantly changing and unknown, which will cause inaccurate control of the natural gas intake, so the air-fuel ratio cannot be well controlled, and the control effect is not good.

[0006] 2. Injection type: For the EFI gasoline engine, the following scheme is adopted for the manufacture: the original gasoline EFI control system is basically unchanged, and an electromagnetic injection valve is connected to each intake manifold of the engine, and the natural gas passes through the pressure reducing valve After decompression, the injection quantity of gas is controlled by the added solenoid valve, and the signal of the original electronic injection unit (ECU) controlling the fuel injector is linearly expanded through a control unit to control the solenoid valve. The sensor detects the operating state to obtain the optimal fuel injection quantity, but the optimal air-fuel ratio of the gasoline engine is different from that of natural gas, and the operating state of the engine produced by the fuel with the same calorific value of natural gas and gasoline is also different , so the control of natural gas intake volume by this method is also inaccurate

In addition, the ignition signal of the original ECU is the ignition advance angle calculated by using gasoline as fuel. The ignition point and combustion speed of gasoline and natural gas are very different, and the difference in ignition advance angle is very large. The ignition advance angle of gasoline state is used for natural gas. Emissions, dynamics, efficiency have a huge impact

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