Types of accumulator
Weight loaded accumulator
It consists of a piston which is loaded with a dead weight and moving within a cylinder this tends to exert pressure on the hydraulic fluid. Potential energy to compress the fluid is generated by the dead weight present on the piston. Concrete block, iron or steel is generally used as dead weight. The piston is made to move in the accumulator in precision fit in order to reduce the leakage. One side of the accumulator is connected to the fluid source and other to the machine.
The ram is at the lower most position at the beginning of a cycle. The fluid is admitted continuously inside the cylinder during the idling period where the drive is provided by the machine. This makes the ram to reach the top most position, thus the piston or the plunger gains its potential energy. During the working stroke the accumulator is discharged to drive the machine.
Spring loaded accumulator
This type of accumulators is similar to that of the dead weight loaded type of accumulator. Spring loaded consists of spring in place of the dead.it is preloaded with the help of compression spring. It consists of a cylindrical body, a movable plunger and a compression spring.
In the beginning the spring is in a compressed stage which makes the hydraulic fluid to flow inside the cylinder of the accumulator. Load of the spring is responsible for the pressure inside the cylinder.as the spring gets compressed the pressure inside the accumulator gets increased. When the fluid gets discharged out of the cylinder the spring gets expanded.in this method also the pressure exerted on the fluid is not constant as that of weight loaded type
Gas loaded type accumulator
This type of accumulator is also called as hydro pneumatic accumulator. This accumulator is widely used in many types of industries. This is classified into two types. They are,
Non-separator type accumulator
It consists of fully enclosed shell containing pneumatic-loaded actuator, gas charging port in the op and oil port at the bottom. The gas is occupied on the top and the hydraulic fluid is present at the bottom since there is no membrane to separate the gas and the hydraulic fluid it is called as non-separator type accumulator.
In this type of accumulator pressurization is achieved by the entry of pressurized gas into the cylinder. When the pressure of the machine increases the oil port opens and the oil enters the cylinder and the volume of the gas is reduced. This reduction in volume of the gas increases the pressure. This pressure gap or potential energy is used to drive the accumulator.
Separator type accumulator
the construction of the outer parts are similar to that of the non-separator type except that it consists of an additional piston separator or seal.
The piston serves as the barrier between the gas and the hydraulic fluid. The working is similar to that of the non-separator type of accumulator. The gas gets compressed when the charged oil pushes the piston against it. The reduction in volume of the gas increases the pressure. This pressure gap or potential energy is used to force the oil out of cylinder when it is required in the circuit.