Doc. dr. Franc Majdič, univ. dipl. inž., Univerza v Ljubljani, Fakulteta za strojništvo

Abstract​:
Hydraulic accumulators are installed in numerous HS for various tasks, but mostly to add pressurized hydraulic liquid (HL) in HS. In some HS, a large, far above-average amount of pressurized liquid HL is required for a few briefly recurring working movements of one or two hydraulic cylinders (HC) or hydromotors (HM) within a longer working process of machinery. It would be nonsensical and impractical to design appropriate high displacement pumps for very short periods of exceptionally large quantities HL.
Figure 3 is used to illustrate very briefly the thermodynamic basis for pressure and volume changes inside HA, simplified for ideal gas.
The paper presents the four typical pressures and associated volumes during working processes of piston and bladder types of HA. The physical principles during the working phases of the accumulator are also briefly described.
The 4th figure in the paper shows an example of the hydraulic scheme of a hydraulic cicuit with HA. The method and mathematical model for calculating the required volume V0 of HA will be presented in the next issue of periodical magazine Ventil.

Keywords:
power-control hydraulics (PCH), hydraulic system (HS), hydraulic accumulator (HA), hydraulic component, hydraulic liquid (HL), thermodynamic