Hydraulic System Accumulator

Table of Contents

• What is a Hydraulic System Accumulator?
• What are the Roles and Functions of Accumulators in Hydraulic Systems?
• Different Types of Accumulators and Their Applications
  • Weighted Accumulator
  • Spring Accumulator
  • Gas Accumulator
    • Non-Separating Gas Accumulator
    • Separating Gas Accumulator
  • Bladder Accumulator
  • Diaphragm Accumulator
  • Piston Accumulator
• Applications of Accumulator Systems in the Machinery Industry

What is a Hydraulic System Accumulator?

A hydraulic system accumulator is a reservoir equipped with a membrane or piston that contains an inert pressurized gas (usually nitrogen) and is used to store energy. The hydraulic fluid is held outside the reservoir, on the other side of the membrane or piston.

What are the Roles and Functions of Accumulators in Hydraulic Systems?

Accumulators act similarly to a car battery, except that instead of storing electrical energy, they store hydraulic energy through pressurized fluid. They help to:

• Maintain system pressure.
• Supplement the pump’s flow.
• Reduce the pump's capacity. Additionally, accumulators are used to:
• Control and minimize pressure fluctuations and shocks in closed hydraulic systems.
• Provide auxiliary hydraulic power during emergencies.

The use of accumulators significantly enhances the efficiency of hydraulic systems.

Different Types of Accumulators and Their Applications

There are currently three main types of hydraulic accumulators:

1. Weighted Accumulators
2. Spring Accumulators
3. Gas Accumulators

These accumulators are categorized based on their operating mechanisms. Below is a detailed explanation of each type.

Weighted Accumulator

As the name suggests, this type uses a piston and weight mechanism to store potential energy. The movement of the piston within the cylinder applies pressure to the hydraulic fluid.

Applications: Due to their large size, weighted accumulators are primarily used in limited applications with high volume requirements, such as heavy presses.

Spring Accumulator

This type consists of a spring-loaded piston inside a cylinder. Hydraulic fluid enters the accumulator reservoir from the opposite side of the cylinder, and the fluid is stored under the pressure generated by the spring.

The pressure reaches its peak when the spring is fully compressed. Conversely, when the spring is fully extended, the pressure on the fluid is minimized.

Applications: Spring accumulators are typically used in situations with space constraints and for operations involving smaller volumes, such as mobile and motorized systems.

Gas Accumulator

Gas accumulators use gas as the fluid medium. These accumulators, also known as hydropneumatic accumulators, are divided into two types:

1. Non-Separating Gas Accumulators
2. Separating Gas Accumulators

Non-Separating Gas Accumulator

In this type, gas under pressure enters the cylinder, creating pressure in the accumulator. As the pressure increases, the oil port opens, allowing oil to enter the cylinder, reducing the gas volume. This pressure continues to build until the cylinder moves due to the force exerted by the pressurized fluid.

Separating Gas Accumulator

In this type, a piston acts as a barrier between the hydraulic fluid and the gas. When hydraulic oil applies pressure on the piston, the gas is compressed automatically.

Main Types of Separating Gas Accumulators

1. Bladder Accumulator This type uses a bladder as a flexible separator between the gas and the hydraulic oil. The bladder is housed within a steel shell and equipped with a valve at the inlet.
2. Diaphragm Accumulator As the name suggests, this type uses a diaphragm as the elastic separator. The diaphragm is fully enclosed between the walls of the pressurized tank.
3. Piston Accumulator In this type, the piston serves as the separator between the hydraulic oil and the compressed gas. Its structure is similar to a spring accumulator, except that compressed gas is used instead of a spring.

Applications of Accumulator Systems in the Machinery Industry

Accumulator systems are widely used in industrial hydraulic devices, such as hydraulic guillotine shears. In the hydraulic section of these machines, hydraulic oil is used to move pistons.

Traditional System: In conventional methods, piston movement is entirely powered by hydraulic fluid during both the forward and return strokes. Continuous operation causes the oil to overheat, damaging hydraulic components and reducing oil density, which in turn decreases the cutting power of the machine.

Modern System: The modern hydraulic system incorporates an accumulator in conjunction with a nitrogen gas system. During the downward stroke of the machine’s upper blade, nitrogen gas is compressed and the stored energy assists the hydraulic system in the return stroke. This method prevents overheating, as the hydraulic system disengages during the upward movement, with nitrogen pressure raising the upper blade.

Why Use Nitrogen Gas? Nitrogen is used due to its stability and non-reactivity with pressurized or heated oil.

This method, implemented by Grand Dayyani Machine Manufacturing , demonstrates technical expertise and efficiency, though it is costlier than traditional systems. Many manufacturers avoid adopting this method due to limited technical knowledge and higher initial costs.

To learn more about the specifications of the hydraulic guillotine shears byGrand Dayyani Machine Manufacturing , click here.

Finally, a video showcasing the introduction and operation of various accumulators in hydraulic systems, along with practical examples, is provided for further understanding.