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Bubbles in working fluids have much influence on the performance of fluid power systems. One of the authors has developed a novel device for bubble elimination capable of eliminating bubbles and decreasing dissolved gases using swirl flow. In this paper, performance of bubble removal in oil flow is studied through numerical analysis of the swirl flow in the device. This paper also documents a reduction of oil temperature rise and removal of entrained air from the working fluid in the hydraulic circuit by use of the device. It has been confirmed that the device is effective keeping the oil temperature low in the fluid power system.

This paper describes the Nippondenso in-line pump system designed for U.S. 1991 emissions regulation for medium duty diesel engines. With the combined use of the further improved in-line pump, NB-S and the multi-hole nozzle with a smaller orifice diameter, the required injection pressure of 100 MPa to 120 MPa at the nozzle can be achieved. However, some problems to be resolved exist in the subject fuel injection system: (1) secondary injection, (2) cavitation erosion of injection pipe, (3) higher pressure sealing of fuel, (4) undesirable fuel delivery curve vs. pump speed (called “Trumpet Shape” fuel delivery curve) Thus technical measures to cope with those problems are explained in details.