Natural gas engine gas quality adaptive control method

Abstract

The invention discloses a natural gas engine gas quality adaptive control method. The natural gas engine gas quality adaptive control method comprises the steps of bench testing, parameter table pre-storing, gas quality adaptation, gas quality adaptive condition setting, gas quality adaptation enabling, parameter information comparison, gas quality adaptation factor obtaining, correction parameterobtaining, gas quality adaptation persistence and the like. Information of an oxygen sensor is detected in real time through an electronic control unit (ECU); a corresponding gas quality adaptation factor is determined after analysis; and a gas injection quantity correction coefficient, an air demand quantity correction coefficient, a fire angle correction degree and an EGR correction rate whichneed to be adjusted are determined according to the gas quality adaptation factor and act on an engine through corresponding execution parts. The influence of the change of the quality of natural gason the Lambda stability is eliminated, the stability control of engine emission results is facilitated, the performance stability control is facilitated, and the operation safety of the whole system is finally improved.

Description

technical field [0001] The invention relates to the technical field of natural gas engine operation control, in particular to an adaptive control method for natural gas engine gas quality. Background technique [0002] At present, the composition of natural gas used for engine operation in the market is quite different, because a certain proportion of inert gases such as ethane, propane and nitrogen are mixed in various qualities of natural gas, and the content of the above inert gases in different qualities of natural gas is also different. Among them, the calorific value of ethane, propane and other components is relatively high. Their addition changes the calorific value of pure natural gas when it is burned, resulting in a change in the combustion speed of the gas mixed with oxygen, which in turn affects the actual EGR rate of the engine mixture. The actual EGR rate is greater than the EGR rate calculated by the engine control unit ECU, so the risk of engine misfire is i...

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Problems solved by technology

Among them, the calorific value of ethane, propane and other components is relatively high. Their addition changes the calorific value of pure natural gas when it is burned, resulting in a change in the combustion speed of the gas mixed with oxygen, which in turn affects the actual EGR rate of the engine mixture. The actual EGR rate is greater than the EGR rate calculated by the engine control unit ECU, thus increasing the risk of engine misfire

In addition, the difference in natural gas composition will also affect the control accuracy of the engine Lambda. In the traditional method, the closed-loop control of the oxygen sensor is used to adjust the control accuracy of the Lambda. However, affected by the above-mentioned various inert gases, it is found that , simply relying on the closed-loop control of the oxygen sensor cannot guarantee the control accuracy of the engine Lambda, and will eventually affect the operating state of the engine

[0003] In addition, the difference in natural gas composition will also affect the consistency of the engine's net power, which will change the combustion in the engine cylinder, resulting in the net power of the engine not meeting the requirements of relevant regulations. The fixed emission and power are consistent. After using the mixed gas with inconsistent combustion speed, the consistency of engine emission and power will be destroyed, and it is easy to aggravate the occurrence of engine knocking. In severe cases, it may even be damaged due to knocking. engine

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