The structural mechanism of main pump in nitrogen oxides(NO

x

)sensors is elucidated

and the COMSOL Multiphysics software is utilized to conduct finite element analysis(FEA)of the main pump model.Influence of different dimensions of chamber(the first diffusion channel and the first cavity)on the oxygen pumping efficiency of the main pump is studied and structural size optimization is performed.The results demonstrate that changes in the dimensions of the first diffusion channel and the first cavity affect the oxygen(O

2

)concentration within the first cavity.After optimization

the maximum difference of O

2

concentration within the first cavity of the main pump model is reduced from the initial value of 6460.8×10

-6

to 245.7×10

-6

a decrease of 26.3 times

significantly improve oxygen pumping efficiency of the main pump

ensuring accurate measurement of NO

x

in subsequent stages.Although the optimized main pump model exhibits a slight increase in oxygen pumping response time

with the longest being 0.38s

this duration has minimal impact on the overall operational response time of the NO

x

sensor.