Application Research On Standard Bench Cycle In Rapid Aging Test Of Automotive Catalytic Converter

Three-way catalytic converters are widely used in gasoline vehicles because of their high conversion efficiency for the main pollutants CO,NO_X and HC of gasoline engines near the theoretical air-to-fuel ratio of the engine.However,Catalyst conversion efficiency will be reduced with the increase of the using time.The research on aging properties of three-way catalytic converters has important practical significance to ensure long-term stable working.The light vehicle emission regulations GB18352.5 are puts forward requirements on durability of pollutant emission control device.There are two methods to test the durability of pollutant control device,one is by the method of vehicle test on the road,the other is by the method of vehicle test on the drum.By both of the two methods the vehicle must travel 160000 kilometers.The cost of vehicle test method is high and the test risk is high too.So we’ve been thinking about a new method.The light vehicle emission regulation(GB18352.5)proposed the Standard Bench Cycle test method for rapid aging of catalytic converter(hereinafter referred to as SBC).SBC test method is based on the catalysts are mainly the principle of thermal aging,aging by increasing reaction temperature to improve catalysts aging strength so as to shorten the aging time.At present,the rapid aging method of SBC has not been widely applied.Although this method can save the aging test time,there are many test items involved in the test process and the test process is complex.It is urgent to study the application of the test method through complete test.In this paper,through vehicle test and engine test,the test process of rapid aging method of SBC is studied,including rapid aging principle analysis,vehicle SRC catalysts temperature field research and the construction method of engine test bench to meet the requirements of regulations,study on engine condition adjustment method to meet the requirement of SBC,the selection method of different engine working condition of SBC scheme,bench rapid aging results analysis,etc.The experimental results show that the temperature of the back part of the SRC circulating test catalytic converter is higher than that of the front part,and the highest temperature is located near the edge of the back part of the catalytic converter.The construction of SBC bench mainly depends on selecting suitable engine as exhaust gas generator and designing air injection device.Engine speed,load,air-fuel ratio and ignition advance angle are all factors that influence the temperature of catalytic converter.Compared with the ignition advance angle,the air-fuel ratio and secondary air injection have greater influence on the temperature of catalytic converters,and under the condition of secondary air injection of catalytic converters,the adjustment of engine air-fuel ratio will have a significant influence on the temperature of catalytic converters.Therefore,the technical method of air fuel ratio adjustment is preferred to meet SBC engine condition debugging.Through the comparative analysis of the aging results,the deterioration coefficient obtained by the rapid aging of SBC is higher than that obtained by the vehicle test,but it can still meet the requirements of the regulations.The rapid aging method of SBC is the preferred method to shorten the certification test time and reduce the test cost in the future.