Abstract
The swash plate type variable delivery axial piston pump is commonly applied in construction machinery and other types of machinery as a power source for hydrostatic transmissions. To guarantee vehicle safety, it is necessary for the swash plate to stop at exactly zero angle, regardless of the control methods of the swash plate angle. Especially, it is required that the swash plate returns to zero angle naturally during manual control.
It is already known that a small moment acts on the swash plate restoring it to zero angle when the swash plate angle is near zero. Studies of this phenomenon, however, have not been performed and the principle of occurrence of the zero angle restoring moment is still not well understood.
The objectives of this study are to clarify the principle of occurrence and improve the characteristics of the zero angle restoring moment.
In this report, the inner states of the pump were investigated experimentally, and a model for analysis was proposed. Furthermore, supplemental experiments were performed and it was ascertained that the experimental results are in good agreement with forecasted results based on the model.
