The working principle and overview of piston accumulator

Piston accumulator working principle:
Piston accumulators work on the principle of accumulating liquid by utilizing the compressibility of a gas (nitrogen). Piston accumulators consist of an oil part and a gas part with a piston acting as a gas-tight spacer. The air cavity is pre-filled with nitrogen, and the oil part is connected with the hydraulic circuit, so when the pressure rises, the accumulator absorbs the liquid and the gas is compressed; when the pressure drops, the compressed gas expands, and the accumulated pressure Hydraulic oil enters the hydraulic circuit.

Piston accumulators Overview:
HXQ series piston accumulator is an important hydraulic auxiliary part of the hydraulic system, which has the functions of storing energy, stabilizing pressure, compensating capacity, absorbing shock, and boosting pressure. The piston accumulators produced by our company have complete specifications, novel structure, low noise, no vibration, good sealing performance, no leakage, long service life, high efficiency of hydraulic equipment, and convenient maintenance.
1. Definition of parameters for Chinese Hydraulic Accumulator calculation of piston accumulator:
P0=precharge pressure P1=minimum working pressure P2=maximum working pressure
V0=effective gas volume V1=gas volume at P1 V2=gas volume at P2
t0=pre-air gas temperature tmin=minimum working temperature tmax=maximum working temperature
①The piston accumulator is pre-charged with nitrogen. The piston rests against the lower end cap and closes the port.
②The minimum working pressure should be about 5bar higher than the pre-charge pressure, so as to prevent the piston from hitting the lower end cover every time the oil is output and the oil pressure leaking out. ③The effective capacity ΔV in the accumulator after reaching the maximum working pressure: ΔV= V1－V2 .
2. Selection of pre-charge pressure
The volume of the accumulator is determined according to the selection of the precharge pressure. To fully utilize the accumulator volume, the following precharge pressures are recommended:
P0, tmin ≥2bar (piston type 2) P0, tmin ≥10bar (piston type 1) P0, tmin ≤P1 - 5bar
In extreme cases, the pre-charge pressure P0 ≥ P1 can be selected after detailed calculation for slow inflation (isothermal) and rapid release (adiabatic). None of the accumulators are delivered uncharged or with a reserve pressure of 2 bar.
3. Accumulator calculation formula
The compression and expansion process in the accumulator should follow the law of changing gas state. The ideal gas is: P0×V0n= P1×V1n=P2×V2n
Among them, we should pay attention to the influence of the polytropic exponent "n". The slow expansion and compression state changes are close to isothermal, and the polytropic exponent can be n=1, while the rapid expansion and compression process undergoes adiabatic state changes, and the polytropic exponent n= k=1.4 (nitrogen for diatomic gas). At pressures above 200 bar, the actual gas properties are significantly different, thus reducing the effective capacity. In this case, a correction should be made, taking into account changing the value of k. The gas volume required for various applications can be calculated using the following formula, where pressures below 10 bar are always used as absolute pressures.
Piston accumulator ordering instructions:
1. The full name of the model code must be specified when ordering, such as: the nominal pressure is 20MPa, the nominal volume is 32L, the piston accumulator with threaded connection, and the working medium is hydraulic oil: HXQ-L32/20-Y.
2. If you have special requirements for piston accumulators, please negotiate with our company.
3. The company reserves the right to modify the design without prior notice.