Dynamic Analysis of the Stick-Slip Phenomenon in an Automotive Water Pump

In this paper, we present a study on the stick-slip torsional vibration of the spinning shaft in an automotive water pump. We propose a dynamic rotor model with a pulley, an impeller, a mechanical seal and a shaft to analyze the stick-slip vibration of a water pump. The dynamic states of the mechanical seal are classified into stick and slip states depending on whether the seal and mating rings of the mechanical seal have relative motion or not. We derived the partial differential equations of motion and the corresponding boundary conditions for each state of the seal. In addition, we established a judgement criterion for the stick and slip states of the seal. After the equations of motion were discretized by a proposed finite element procedure, the dynamic responses of the rotor system of a water pump were computed by using the generalized-a time integration method. Furthermore, we analyzed the effects of various system parameters on stick-slip vibration, including the mass moment of inertia for the pulley, the drag torque at the impeller, the external torque at the pulley, and the normal force between the seal and mating rings.