Hydraulic accumulators

Description

When using hydraulic clamping systems, internal leaks and volume changes (eg. because of temperature fluctuations) must be balanced. These tasks are performed by the hydraulic accumulator. In intermittent applications, the attached pressure generator fills the hydraulic accumulator during the interruptions. As a result, a short-term high volume flow is achieved, which can be used, as required, to reduce power at the pressure generator. As volume storage, the hydraulic accumulators are also suitable as a source of pressure oil upon failure of the pressure oil supply at the hydraulic pump. When using hydraulic accumulators, the system must be equipped with additional security elements (see safety information). Only qualified personnel may work on the hydraulic accumulator.

Applications:

Balancing internal system leaks
In hydraulic clamping systems, the pressure generator usually operates in off mode. A pressure switch thereby controls the switching operations of the drive motor. If elements that cause a leak due to their construction are connected to the system for example a rotary valve coupling, this causes frequent switching. The hydraulic accumulator substantially reduces the on and off cycles of the drive motor, thus saving energy and reducing wear and tear.

Balancing volume changes
In uncoupled clamping systems, temperature fluctuations may arise. These will inevitably lead to substantial changes in the clamping pressure (± 10 bar at ± 1° C). The installation of a hydraulic accumulator in the system equalises volume, thus preventing undesirable fluctuations in pressure.

• available in three standard sizes

• can be mounted in any position

• discharge of hydraulic components for pressure fluctuations/surges

• helps to conserve energy

• reduces wear

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Functioning:

The membrane is pressurized with nitrogen. The integrated valve plate closes the opening of the oil inlet, thus preventing damage to the membrane. At minimal operating pressure, a small amount of pressure oil must remain in the vessel so that the membrane does
not close during discharge due to the pressure on the valve plate; p0 must therefore always be set lower than p1. The stored amount of liquid corresponds to the volume change ΔV between the position at minimum and maximum operating pressure.

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Safety instructions:

In Germany, hydraulic accumulators are subject to the rules and regulations of the TRB (Technische Regeln Druckbehälter /
technical rules for pressure vessels). Accordingly, the following supplementary equipment is required when using hydraulic accumulators:

- pressure gauge
- relief device
- pressure relief valve
- shut-off valve (optional)
- test pressure gauge connection

Outside of Germany, the national rules and regulations on the use of pressure vessels of the respective country apply.