Method and device for detecting oxygen storage capacity of three-way catalyst

Abstract

The invention discloses a method for detecting oxygen storage capacity. The method comprises the following steps of: absorbing oxygen in a saturation way by a catalyst when a vehicle runs; after the catalyst absorbs oxygen in a saturation way, obtaining an engine intake flow of a special moment based on a preset sampling period starting from the front oxygen reaction moment; utilizing the obtained engine intake flow to calculate the oxygen storage quantity of the catalyst at each sampling moment; accumulating the oxygen storage capacities starting from the front oxygen reaction moment to the ending of the rear oxygen reaction moment, wherein the front oxygen reaction moment is the moment that the voltage of a front oxygen sensor signal rises up to pass through the first preset value, and the rear oxygen reaction moment is the moment that the voltage of a rear oxygen sensor signal rises up to pass through the second preset value. The device for detecting oxygen storage capacity of the three-way catalyst comprises an intake flow sampling unit, a multiplier and an accumulator. With the adoption of the method and a device provided by the invention, the successful rate of detection is improved, and the measuring accuracy of the oxygen storage capacity of the catalyst is improved, thus, better reliability of the detection result of the catalyst can be ensured.

Description

technical field [0001] The invention relates to a detection method and a detection device for the oxygen storage capacity of a three-way catalytic converter. Background technique [0002] With the continuous improvement of environmental protection requirements, the displacement of the engine is gradually reduced and the efficiency is gradually increased. At the same time, the on-board system (OBD) is required to effectively report the failure of any parts on the vehicle that may cause vehicle emissions to exceed the standard. question. In particular, when the efficiency of the three-way catalytic converter, which is a catalytic conversion device for vehicle emissions, is low, the on-board fault detection system must report a fault. [0003] At present, the detection method of the three-way catalytic converter by the on-board detection system includes: under the idling condition, the fuel is leaned / richly controlled for the engine; To judge the efficiency, the specific meth...

AI Technical Summary

Problems solved by technology

[0017] 1. Due to the small intake air volume MAF(t), for the same catalytic converter, since the oxygen storage capacity OSC(grams O2)T is the same, the detection time t_OSC0 will become longer when the equivalent air-fuel ratio during the measurement process remains unchanged. , thus affecting the detection speed

[0018] 2. Due to the small intake air volume MAF(t), the measurement accuracy of the intake air volume is poor, and the measurement error of the intake air volume can reach 10% in the case of a small air intake volume, resulting in a larger dispersion of the measurement result OSC(grams O2)T, Make the measurement accuracy worse

[0019] 3. Lean / rich control of the air-fuel ratio under the condition of small intake air volume will make the combustion in the engine cylinder worse, resulting in poor engine stability and excessive speed fluctuations, which will cause the risk of engine flameout

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