Downsizing of Oil Reservoir by Bubble Eliminator

In mobile hydraulic systems such as commercial vehicles, hydraulic fluids are splashed and agitated in the reservoirs. To overcome air entrainment in oils, the overall dimensions should enclose a sufficient volume of oil to permit air bubbles to escape passively during the resident time of the fluid in the reservoir. However, in view point of environmental compatibility, energy saving, cost saving and safety, one trend in fluid power systems is to be designed in a more compact fashion and requiring less fluid in the reservoir. One of the authors has developed a newly device using swirl flow for bubble elimination capable of eliminating bubbles and of decreasing dissolved gases. This device is called the bubble eliminator. In this paper we focus on the technical issue of oil degradation for the air bubbles and oil temperature rise in the reservoir of a test hydraulic circuit. In our experiments, surrounding air is intentionally introduced from the oil surface by vibration of the reservoir in the hydraulic circuit. The bubble eliminator solves many problems concerning the air entrainment in hydraulic systems.