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CHAPTER 6.3 (ACCESSORIES) - Coggle Diagram
CHAPTER 6.3 (ACCESSORIES)
Accumulators
hydraulic accumulator is a pressure vessel used for storing fluid (Potential energy)
Function
To meet peak demands of power
To provide emergency power sources
To smooth out pressure surges
Types
Spring Loaded Type
Not suitable for high cycle rates operation
Potential energy provided by compressed spring. Pressure exerted on fluid is not constant.
Similar to weight loaded, except piston is pre-loaded with a spring
Weight Loaded / Gravity Type
Consist of a cylinder, piston and dead weight
Oldest Design
Provide constant fluid pressure throughout full volume output regardless of rate and quantity output
Bulky Design
Gravity force provides potential energy in the accumulator
Gas Loaded Type
operates with Boyle's law of gases (constant temperature process, the pressure of gas varies inversely with its volume.)
2 Main Categories
Separator Type
Diaphragm
Disadvantage
Limited application
Advantage
Small weight-to-volume ratio
Bladder Type
Advantages
Lightweight bladder provides quick response for pressure regulating, pump pulsation and shock dampening applications.
Secure sealing between the gas and oil chambers
Piston Type
Disadvantages
Limited practical size
Expensive to manufacture
Leakage occurs when used over long periods
Piston and seal friction problem in low pressure system
Advantages
Ability to operate at high temperature
Ability to operate at high pressure
Non-Separator Type
More practical than weight and spring loaded
Intensifier
Pressure intensifiers
act as a booster to increase the fluid pressure available from the supply source.A cost saving measurement.
Example : Punch press system
Role of pressure intensifier
Eliminate the need for a high pressure/ low flow pump
Operation
intensifier should be installed near the cylinder to keep high pressure lines as short as possible.
a pilot check valve is used instead of a regular check valve to permit retraction of the cylinder
high pressure output of intensifier closes the pilot check valve and pressurizes the blank end of cylinder to perform punching operation
when pressure in cylinder reaches the sequence valve pressure setting, intensifier starts operate