The functions of accumulators are mainly divided into four categories: energy storage, hydraulic shock absorption, pulse elimination and energy recovery.

The first category: energy storage. This kind of function can be subdivided into: ① as an auxiliary power source to reduce the installed capacity; ② Compensate for leakage; ③ Thermal expansion compensation '; ④ As an emergency power source; ⑤ Constitute a constant pressure oil source.

The above five functions have basically the same principle, and they all mainly apply the function that the accumulator can store a large amount of energy. The main difference is that the parameter selection is different, and different parameter selection formulas can be used to achieve the required functions and meet the required requirements.

The second type: absorbing hydraulic shock. Sudden reversing of the reversing valve and sudden stop of the movement of the actuating element will produce pressure impact in the hydraulic system, making the system pressure rise rapidly in a short time, causing damage to instruments, elements and sealing devices, as well as vibration and noise. To ensure the absorption effect, the accumulator should be set near the impact point, so the accumulator is generally installed in front of the impact source such as the control valve or hydraulic cylinder, which can well absorb and buffer the hydraulic impact.

The third category: eliminating pulsation and reducing noise. For the hydraulic system with a small number of pistons and a plunger pump, the periodic change of pump flow makes the system vibrate. The accumulator can absorb a large amount of energy in the pulsating pressure and flow within one cycle of the flow pulsation. Part of the oil with the instantaneous flow higher than the average flow is absorbed by the accumulator, and the part with the instantaneous flow lower than the average flow is supplemented by the accumulator, which absorbs the energy in the pulsation, reduces the pulsation, and reduces the damage to sensitive instruments and equipment.

The fourth category: energy recovery. The energy recovery with accumulator is a field of more research at present. Energy recovery can improve energy utilization, and is an important way to save energy. Accumulators can be used to recover multiple kinetic energy and position potential energy because they can store energy temporarily. The main researches in this area are as follows: ① Recover vehicle braking energy; ② Recover the potential energy of the boom mechanism of construction machinery; ③ Recover braking energy of hydraulic excavator turntable; ④ Recover the falling gravity potential energy of oil workover rig and drill pipe; ⑤ Recover the downward gravity potential energy of elevator.