Influence of Compressibility of Oil on the Step Response of a Hydraulic Servomechanism 3rd Report The Response under Inertial Loading

抄録

Step response of a hydraulic servomechanism under inertial loading is studied. Conclusions obtained from this study are summerised as follows : (1) If the hydraulic servomechanism is geometrically symmetric, free from external leakage, and if compressibility of oil is constant, then nondimensional pressures in cylinder chambers satisfy the relation P₁+P₂=1. This relation is lost when a cavitation appears in one of the cylinder chambers. (2) The stability becomes inferior with smaller bulk modulus and larger inertial load. (3) The stability becomes superior with internal leakage and viscous and/or Coulomb friction. (4) Asymmetricity A₁≠A₂ causes asymmetric response depending on input direction. (5) The step response is influenced significsntly by air bubbles dispersed in the oil. Effective compressibility of the oil is reduced by the air bubbles. The form of basic equations used today to study the hydraulic servomechanism is conserved in spite of presence of the air bubbles if the tangential bulk modulus is used.