Rexroth hydraulic accumulators save energy and improve manufacturing efficiency by using the accumulator as a storage device to store hydraulic pump output flow when system demand is low and supplement output when demand is high.

RexrothAccumulator2

Rexroth hydraulic accumulators are used to:

  • Store power for intermittent duty cycles, economizing hydraulic pump drive power
  • Provide emergency or standby power
  • Compensate for leakage loss
  • Provide suspension in vehicles
  • Dampen pulsations and shocks of a periodic nature

The majority of applications use accumulators to store energy for intermittent duty cycles or to provide a source of emergency power. In either case, the problem is determining the optimum size and pre-charge of the accumulator.

Accumulator sizing is based on the gas charge. The change in gas volume and pressure determines the amount of liquid that can be added or withdrawn. However, unlike mechanical springs, compressing a gas tends to heat it, raising the pressure above what would be expected from compression alone. Expanding a gas tends to cool it, reducing the pressure below that caused by expansion alone. Either of these effects can substantially affect accumulator sizing. Expansion (or compression) of a gas resulting in a change of gas temperature produces adiabatic expansion. When an accumulator is discharged rapidly, there is not enough time for sufficient heat transfer through the accumulator walls and adiabatic expansion occurs

If the expansion (or compression) occurs slowly, there is sufficient time for heat to be added (or subtracted) by the accumulator wall to maintain a constant gas temperature and isothermal expansion occurs. The median of these two states of expansion can be partially "adiabatic".