Hydropneumatic receivers

Hydropneumatic receivers have the task of collecting and storing hydraulic energy, and then releasing it on demand. This type of receiver is used in conjimction with injection moulding machines with very rapid injection (with accumulator). Here, a high volume flow which can be partially accessed from the receiver is required periodically for brief intervals. The benefits in the application of a hydropneumatic receiver are in the use of relatively small pumps, drive motors and oil reservoirs. 

The working principle of a receiver is that it is virtually impossible to compress the hydraulic fluid. If it is nevertheless to be stored under pressure, a gas is utilised, in this case nitrogen. The gas is compressed in a pressure reservoir by the hydraulic fluid and decompresses as needed through the release of fluid. In order to ensure that the gas does not mix with the hydraulic fluid, the pressure reservoir is divided into two chambers by an elastic separation wall (membrane). A hydropneumatic receiver symbol is shown in Figure 5.14. 

---