EGR rate measurement method and device based on oxygen sensor signal

Abstract

The invention relates to an EGR rate measurement method and device based on an oxygen sensor signal. The method is characterized by comprising the steps: an oxygen concentration value of an air inlet side is obtained according to an oxygen concentration signal collected by an oxygen sensor disposed on an air inlet side pipeline; an exhaust side oxygen concentration value is obtained according to an oxygen concentration signal collected by an oxygen sensor arranged on an exhaust side pipeline; and an EGR rate is calculated based on the intake side oxygen concentration value and the exhaust side oxygen concentration value. The problems in related technologies are solved, the application range of EGR rate measurement is expanded, and the measurement precision is improved.

Description

technical field [0001] The invention relates to the technical field of engine control, in particular to an EGR rate measurement method and device based on an oxygen sensor signal. Background technique [0002] EGR is the abbreviation of Exhaust Gas Re-circulation, that is, the abbreviation of exhaust gas recirculation. The EGR rate is defined as the ratio of the amount of recirculated exhaust gas to the total amount of intake air inhaled into the cylinder. A reasonable control of the EGR rate has the effect of purifying nitrogen oxides. And the emission of the whole machine is extremely important. A method is needed to quantify the EGR rate during the calibration test to judge the impact of exhaust gas recirculation on engine performance. The current mainstream solution is to install pressure or differential pressure sensors and temperature sensors before and after the EGR valve. Use the one-dimensional isentropic fluid formula to calculate the exhaust gas flow through the ...

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Problems solved by technology

[0003] However, the existing technology has certain defects in the measurement range and robustness: due to the special dependence on the pressure difference before and after the EGR valve, when the pressure ratio (pressure after the valve / pressure before the valve) is greater than 0.95, the one-dimensional isentropic Assumptions will no longer be satisfied, i.e. fluid calculation formulas will no longer be accurate

This will cause the engine to fail to obtain accurate EGR rates when the pressure ratio is greater than 0.95

At the same time, the flow formula also needs to use the effective flow area of ​​the EGR valve at different openings. Due to the manufacturing error of the single throttle area in the EGR valve manufacturing process, there is a deviation between the position output by the sensor and the theoretical position. , coupled with carbon deposits on the valve body, the effective flow area is also very different, resulting in large deviations in flow estimation and poor robustness

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