Hydraulic accumulator is an important part in the hydraulic control process, and its application is becoming more and more extensive, expanding to many emerging fields, and accumulator products are also increasing, but its main functions are still in the following aspects: 1 . Auxiliary energy, 2. Absorb pulsation, 3. Emergency power source, 4. Volume compensation, 5. Pressure compensation, 6. Counterweight, 7. Absorb shock, 8. Absorb pulsation, 9. Hydraulic spring, 10. Fluid transmission, etc. , which will be explained separately below.
1. Auxiliary energy
If the flow changes in the hydraulic circuit in a short period of time, the use of accumulators allows the use of smaller pumps and motors, thereby reducing equipment and operating costs.
If an accumulator is applied, oil is stored during the time periods (t2-t1) and (t4-t3), so little or no oil flow is required at this time. When the required flow rate is higher than the pumping quantity Q1, the accumulator can be used to supply oil during the periods t1 and t3-t2. The selection of pumping volume Q1 must satisfy v1+v2≤v3+v4.
2. Absorb pulsation
Piston and diaphragm pumps inevitably generate pulsations in the hydraulic circuit during operation, which is detrimental to both operation and the service life of the components.
A capsule accumulator is installed on the pressure side close to the pump to moderate the vibration and reduce the vibration to a satisfactory level. Typical uses are for quantitative pumps and plunger pumps with fewer pistons.
3. Emergency power source
In the event of a sudden loss of power, such as pipe or joint failure, pump damage, etc., the accumulator can provide enough energy to complete the operation cycle or restore the transmission mechanism, valve, etc. to a safe position, thereby preventing damage to equipment or product.
In addition, in some cases, it is necessary to obtain an emergency power source, such as the hydraulic power source required for closing safety doors, electrical switches, safety valves, emergency brakes, etc. Another typical use is the emergency supply of fuel oil to boilers in power plants. The fault at B, shown in FIG. 3, which causes energy loss, can be eliminated by manually operating electronic valve A, in which case the energy stored in the accumulator is used.
4. Volume compensation
In a closed fluid circuit, a rise in temperature causes a rise in pressure due to thermal expansion. An in-line installed accumulator compensates for oil volume changes to protect valves, gaskets, pressure gauges, etc. from failure. Oil refineries and long-distance oil pipelines have their typical uses.
5. Pressure compensation
An accumulator is essential when constant static pressure is required over a long period of time, as it will compensate for pressure losses due to leaks in joints, seals, etc., as well as balance pressure peaks that may occur during an operating cycle. Typical uses are clamping systems, Figure 7, load platforms, road presses, beds, lubrication systems, etc.
Balancing a force or weight can be achieved by hydraulic pistons driven by accumulators, thus avoiding counterweight footprints and reducing weight. Typical uses are machine tools, winches, etc.
7. Absorb shock
Fast valve closing creates shock waves (water hammer) that can damage pipes, fittings, valves, etc. Using the proper accumulators can greatly reduce shocks. Typical uses are water pipes, long-distance pipelines for Bladder accumulator fuel and oil, washing equipment, etc.
8. Absorb pulsation
Mechanical vibration energy in hydraulic equipment is absorbed by accumulators. It can be used in the drive and suspension system of fork lifts, mobile cranes, stone crushers, etc.
9. Hydraulic spring
Bladder accumulators can replace mechanical springs, such as the die set used for deep drawing (Figure 11). Adjusting the oil pressure makes it easier and more precise to adjust the mold pressure over a wide range without using a spring.
10. Fluid transfer
Capsule accumulators are an effective solution to a system where an increase in fluid pressure acting on one side of the circuit must be transferred to the fluid on the other side of the circuit without mixing the two fluids. The accumulator's capsule acts as a flexible shield between liquid or gas-liquid, providing a transient response without reducing system pressure.