The bladder-type accumulator contains an elastic barrier between the oil and gas as shown in the cross-sectional view in (Figure 7.20).
The bladder is fitted to the accumulator by means of a vulcanized gas-valve element that can be installed or removed through the shell opening at the poppet valve. The poppet valve closes the inlet when the bladder is fully expanded. This prevents the bladder from being pressed into the opening. A shock-absorbing device, protects the valve against accidental shocks, during a quick opening.
The greatest advantage with these accumulators is the positive sealing between the gas and oil chambers. The Ughtweight bladder provides a quick pressure response for pressure regulation as well as applications involving pump pulsations and shock dampening.
Figure 7.21 illustrates the functioning of a bladder-type accumulator.
The hydrauhc pump delivers oil to the accumulator and deforms the bladder. As the pressure increases, the volume of gas decreases. This results in the storing of hydraulic energy. Whenever additional oil is required by the system, it is supplied by the accumulator even as the pressure in the system drops by a corresponding amount.