Online monitoring instrument and method for concentration and height of urea solution of automobile SCR system

Abstract

The invention provides an online monitoring instrument and method for the concentration and the height of a urea solution of an automobile SCR system. Based on the magnetic coupling resonance principle, the monitoring instrument comprises a high-frequency signal generation module, a monitoring mode selecting module, a data collecting and processing module, a coil design module, a power module and an automotive urea tank. Measuring coils are arranged on the bottom side of the urea tank and arranged in a staggered manner and do not make contact with the urea solution. A self-resonance mode and a dislocation impedance matching technology of the coils are adopted, the sensitivity of the self-resonance frequency and parameters S11 of the coils to the changes of the height and the concentration of the urea solution is improved, and therefore the signal-to-noise ratio of detection signals is increased. High-frequency signal input is conducted on the coil design module through the high-frequency signal generation module, collection and voltage conversion are conducted on the self-resonance frequency and the parameters S11 of the coils through the data collecting and processing module, and the system development efficiency is improved. The self-resonance frequency of the detection coils is detected so that the height of the urea liquid level can be achieved, and monitoring of the urea concentration is achieved by detecting the parameters S11 of the coils.

Description

technical field [0001] The invention relates to an on-line monitoring system for automobiles, in particular to an on-line monitor for concentration and height of urea solution in an automobile selective catalytic reduction (SCR for short) system based on the principle of magnetic coupling resonance and a monitoring method. Background technique [0002] In order to meet the requirements of automobile engine emission regulations, selective catalytic reduction (SCR) has become an essential aftertreatment system for heavy-duty diesel engines. The device sprays 32.5% urea solution into the engine exhaust pipe to reduce the NO in the engine exhaust X Revert to N 2 , so as to realize diesel engine emission NO X reduction. [0003] In the OBD regulations, two requirements are put forward for the engine system equipped with SCR: 1. It must be able to realize the online monitoring (height monitoring) of the insufficient carrying capacity of the urea aqueous solution; 2. It must be ...

AI Technical Summary

Problems solved by technology

This kind of scheme realizes the measurement of urea solution, but it does not realize the monitoring of the insufficient carrying amount of urea solution required in OBD regulations, that is, it does not realize the height monitoring of urea solution, and the self-resonance mode of the coil is adopted to increase the sensitivity to the change of urea concentration This method will greatly increase the difficulty of coil design

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