The purpose of the accumulator
(1) Used as an auxiliary power source to reduce installed capacity. The executive components of some hydraulic systems act intermittently, and their total working time is very short. After the system is equipped with an accumulator, the pump will charge the accumulator during the non-working period. During the working period, the pump and the accumulator The actuators supply oil to the actuators together, so that a smaller pump and power machine can be used to complete the work, reducing the power of the power machine. Although some hydraulic systems are not intermittent, the speed varies greatly within a working cycle. If the accumulator is not installed, the pump must be selected according to the maximum flow required by the system. After the accumulator is installed, the pump can be selected according to the average flow required by the system, which can also reduce the power of the power machine.
(2) Eliminate pulsation and reduce noise. If a plunger pump is used in the hydraulic system and the number of plungers is small, the pressure, flow and other parameters of the system will fluctuate greatly, which will cause vibration and noise in the hydraulic system. The installation of an accumulator in the system can significantly reduce the pulsation, thereby greatly reducing the damage of instruments and valves that are sensitive to vibration, and can significantly reduce the noise at the same time.
(3) Absorb hydraulic shock. The sudden change of direction of the reversing valve and the sudden stop of the movement of the actuator will generate pressure shock waves in the hydraulic system. This pressure shock will cause a significant increase in system pressure, cause damage to the instruments, components and sealing devices in the system, and generate vibration and noise. Installing an accumulator before shock sources such as control valves or hydraulic cylinders can absorb and buffer this hydraulic shock.
(4) Compensation for leakage. For hydraulic systems that need to maintain pressure for a long time, it is not economical to continuously operate the pump to compensate for internal leakage. The accumulator can be used to compensate for internal leakage to maintain the required pressure and unload the pump, which can extend the service life of the pump and reduce energy consumption.
(5) For thermal expansion compensation. In some closed hydraulic systems, when the system is heated, the hydraulic oil will expand in volume, causing the pressure of the entire system to rise. Installing an accumulator in the system will absorb the increase in oil volume and limit the system pressure within a safe range.
(6) As an emergency power source. Some systems require that when the hydraulic pump fails or power failure, the actuator can continue to complete the necessary work. The installed accumulator can be used as this kind of emergency power source, and the stored energy can be released immediately when needed. Applications include closing gate valves in smelters or power stations.
(7) It constitutes a constant pressure oil source. The oil source of most hydraulic control systems in engineering is a constant pressure oil source. The accumulator can form a constant pressure oil source for this type of system with a constant pressure pump. The accumulator can also form a constant pressure network for the secondary regulation system with a constant pressure pump. , The speed regulation of this type of system is achieved by changing the displacement of the variable motor.
(8) Application of accumulator in energy recovery. Energy recovery is an important way to save energy. The kinetic energy and positional potential energy of many fields can be recycled, thereby improving the effective utilization of energy.
The most important maintenance of the accumulator is to maintain proper inflation pressure. With the passage of time, the charging pressure of all accumulators will drop, so it should be checked regularly according to the requirements of use and charged to the specified value. After the accumulator is charged, the gas temperature and pressure increase. After 5 to 10 minutes the temperature stabilizes, check the pressure again.
Proper charging pressure is very important to prolong the service life of the accumulator. When used to store energy, the inflation pressure of the bladder-type accumulator is 80% of the lowest working pressure of the system, and the inflation pressure of the piston-type accumulator is 0.7MPa lower than the lowest working pressure of the system. The inflation pressure is too high or reduced If the minimum working pressure of the system does not reduce the charging pressure accordingly, it will cause operational problems or damage the accumulator. For piston accumulators, too high charging pressure makes the accumulator too close to the piston when the system is discharged at the lowest working pressure. The end cover even hits the end cover, which will cause damage to the piston and the piston seal. In this case, the sound of the piston hitting the end cover can often be heard. For airbag accumulators, excessive inflation pressure will push the airbag into the poppet valve, which will cause fatigue damage to the poppet valve assembly and damage to the airbag. Excessive inflation pressure is the most common cause of airbag damage. . Too low inflation pressure and increasing system pressure did not increase correspondingly
The charging pressure will also accelerate the damage of the accumulator. For a piston accumulator, if the charging pressure is zero, the piston will be pushed to the end cap at the end of the gas, and an impact will also occur. For airbag accumulators, if the inflation pressure is zero or too low, the airbag will be squeezed into the inflation valve and damaged. Generally speaking, this kind of improper charging pressure will damage the piston accumulator to a lesser degree.