Many people may not know that many failures of the hydraulic system are caused by insufficient inflation or leakage of the accumulator.

Many people may not know that many failures of the hydraulic system are caused by insufficient inflation or leakage of the accumulator

     The accumulator, as the name suggests, is used to store energy and is an energy storage device in a hydraulic starting system. Leakage or insufficient pressure of the gas-filled accumulator will have a great impact on the hydraulic system, which is a failure mode of the hydraulic system that many people may overlook.

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Accumulator structure and classification

      Accumulators can be divided into gravity accumulators, spring accumulators and gas-filled accumulators according to the loading mode.

      At present, gas-filled accumulators are more commonly used. Because hydraulic oil is incompressible, it needs to rely on other media to convert and accumulate hydraulic energy. Because nitrogen is stable and easy to obtain, nitrogen is usually used as the accumulator medium. Today we mainly discuss the impact of insufficient inflation of the inflatable accumulator on the hydraulic system

     Inflatable accumulators include: bladder accumulators, piston accumulators and diaphragm accumulators, etc. These are also the most commonly used.

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The role of accumulator in hydraulic system

1. As an auxiliary pressure source

  The actuators of some hydraulic systems act intermittently, and the total working time is very short. Although the actuators of some hydraulic systems do not act intermittently, the speed varies greatly within a working cycle (or within a stroke). After the accumulator is installed in this system, a pump with lower power can be used to reduce the power of the main drive, so that the entire hydraulic system is small in size, light in weight, and inexpensive.

2. As an emergency power source

 For some systems, it is required that when the pump fails or the power fails (the oil supply to the actuator is suddenly interrupted), the actuator should continue to complete the necessary actions. For example, for safety, the piston rod of a hydraulic cylinder must be retracted into the cylinder. In this case, an accumulator with appropriate capacity is required as an emergency power source.

3. Replenish leakage and maintain constant pressure

  For systems where the actuator does not operate for a long time, but to maintain a constant pressure, an accumulator can be used to compensate for leakage, so that the pressure is constant.

4. Absorb hydraulic shock

 Due to the sudden change of the direction of the reversing valve, the sudden stop of the hydraulic pump, the sudden stop of the movement of the actuator, or even the artificial need for emergency braking of the actuator, etc., the liquid flow in the pipeline will change sharply, resulting in shock pressure (oil hit). Although there is a safety valve in the system, it is still inevitable to produce a short-term surge and shock of pressure. This shock pressure often causes failures or even damage of the instruments, components, and sealing devices in the system, or rupture of the pipeline, and also causes the system to produce obvious vibrations. If an accumulator is installed before the shock source of the control valve or hydraulic cylinder, the shock can be absorbed and alleviated.

5. Absorb pulsation and reduce noise

 The pulsating flow of the pump will cause pressure pulsation, causing uneven movement speed of the actuator, causing vibration and noise. Connect a sensitive and small inertia accumulator in parallel at the outlet of the pump to absorb flow and pressure pulsations and reduce noise.

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The influence of insufficient charge or leak of accumulator on hydraulic system

1. When the accumulator is used as an auxiliary pressure source, if the air leakage results in insufficient inflation pressure, the accumulator will not provide enough hydraulic energy, which will cause the hydraulic pump motor to start and stop frequently, fail to save energy, and even cause The risk that the actuator cannot obtain the required hydraulic energy in time

2. When the accumulator is used as an emergency power source, if the air leakage causes insufficient inflation pressure, the accumulator will not provide enough energy to return the actuator

3. When the accumulator is used for the purpose of absorbing hydraulic shock, if the air leakage leads to insufficient inflation pressure, there is not enough compressible gas in the accumulator to absorb the hydraulic shock. When the hydraulic shock occurs, the shock energy that can be absorbed Limited, there is still a risk of damage to hydraulic parts

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Precaution

The new accumulator performs pre-charge pressure testing to ensure that the pre-charge pressure meets the design requirements.

Perform regular air pressure detection on the accumulator according to the operating hydraulic system, and replenish the pressure in time when the pressure is insufficient,

Ensure the efficient operation of the hydraulic system