Using the urea pump（a cycloid pump） of SCR exhaust emission system as the object of study

the stress and deformations of the pump during the operation process by using the finite element method and the ANSYS program are analyzed.According to the research

it shows that the two kinds of load which the rotor received are respectively the torque of the input shaft of the inner rotor and the hydraulic load resulted from the pressure of the liquid between the tooth displacement chambers.The tooth stresses are not even and both the strain and deformation trends are different are also discovered.Therefore

the axial gap between teeth and radial clearance between the pump body and rotor occur which leads to the internal leakage of pump and seriously influence the pump working pressure and the volume efficiency and life of the pump.Least but not last the paper illustrates a way to determining the load range for pump: the loading of the pump should not higher than stress(equal to the maximum pressure stress of PEEK

that is

and at the same time

the radial clearance and the axial clearance should not exceed the extreme values and assumed for a particular size of the pump

that is and.