Accumulators and Intensifiers

 An accumulator is basically a pressure storage reservoir in which a non-compressible hydraulic fluid is retained under pressure from an external source.

Chapter: 9

Accumulators and Intensifiers

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- Jackson Brawn. Jr.

"However far moderne science and techniques have fallen short of their inherent possibilities, they have taught mankind at least one lesson: Nothing is impossible."

- Lewis Mumford

"Men who accomplish great things in the industrial world are the ones who have faith in the money producing power of ideas.

- Charles Fillmore.

Learning Objectives

While reading and after studying this chapter, you will be able to:

• Understand and appreciate the functions and applications of accumulators.

• Discuss the purpose, construction, and operation of various types of accumulators.

• Calculate the capacity and sizing of the accumulators for an application.

• Describe the construction and operation of various accumulator circuits.

• Understand and appreciate the functions and applications of pressure intensifier.

• Explain the construction and operation of a pressure booster.

• Describe the construction and operation of various intensifier circuits.

ACCUMULATORS

1. What are Accumulators?

• An accumulator is basically a pressure storage reservoir in which a non-compressible hydraulic fluid is retained under pressure from an external source.

• In other words, hydraulic accumulator is a device used to store the energy of liquid under pressure and make this energy available as a quick secondary source of power to hydraulic machines (such as presses, lifts, and cranes).

• Example: In case of hydraulic crane or lift, the liquid under pressure needs to be supplied only during the upward motion of the load. This energy is supplied from hydraulic accumulator. But when the lift is moving downward, no large external energy is required and during that period the energy from the pump is stored in the accumulator.

• Thus the function of hydraulic accumulator is analogous to that of the flywheel of a reciprocating engine and a capacitor in an electronic circuit.

• Definition: A hydraulic accumulator is a device that stores the potential energy of an incompressible fluid held under pressure by an external source (such as pump) against some dynamic force (such as weight or gravity, mechanical force by springs, or pressurised gas).

2. Suitability and Applications of Accumulators

• Suitability: Accumulators are suitable for the following types of applications:

1. For hydraulic shock suppression.

2. For fluid make-up in a closed hydraulic system.

3. For leakage compensation.

4. For source of emergency power in case of power failure.

5. For holding high pressures for long periods of time without keeping the pump unit in operation.

• Applications: Accumulators in conjunction with hydraulic systems are used on large hydraulic presses, hydraulic lifts, hydraulic cranes, farm machinery, power brakes and landing gear mechanisms on airplanes, diesel engine starters, and other devices and machinery.

3. Types of Accumulators

Accumulators are classified in terms of the manner in which the load is applied. Various types of accumulators used in hydraulic systems are presented in Fig.9.1.