A static equilibrium condition for the steady-state analysis of variable-stroke swash plate mechanism

Abstract

Variable-stoke swash plate mechanisms are widely used for compressors in automotive air-conditioning systems, but the dynamics of the system has not been investigated sufficiently. In the present study, we derived a dynamic equation based on the Lagrangian mechanics for the mechanism and solved it numerically. The solutions were compared with the ones obtained from the commercial multibody dynamics software, DAFUL. We proposed a static function that can be conveniently used to predict the steady-state behavior of the system without conducting a full dynamic analysis of the variable-stoke swash mechanism. Using the static function, for example, we showed why the stroke of the variable-stoke swash tends to increase with the driving speed and showed a simple way to reverse the tendency. Especially, we observed that the system can have multiple steady-state solutions depending on initial conditions. Based on this observation, we theoretically showed that a hysteresis phenomenon can occur in the variable-stoke swash mechanism so that the behavior of the system can depend on the operation history of the system.