High temperature hydraulic pump and flow control based on frequency conversion technology

Considering the viscosity of the hydraulic oil, seal materials, and oil properties, oil temperature is usually controlled by means of oil coolers, heaters or increase the volume of oil reservoir in most equipment. But for specific machines such as tank vehicles, air crafts or space crafts, high power density is needed. These machines have to endure high oil temperature over 403K. Among common hydraulic pumps, gear pump is easier to improve for high temperature, for its simple structure, low cost, and higher reliability. A gear pump was redesigned, mathematical model of the pump was established and analyzed, and some structure parameters, seals and bearings were revised to fit high temperature environment. Due to the difficulty of the variable displacement, a control system was designed based on frequency conversion technology. Experiments showed that the volumetric efficiency of the pump was 85% at pressure 15MPa, and the flow rate control accurate was about 4%, and the setting time of the flow control was about 20s. Based on this system, a hydraulic station with 4 pumps to supply pressure oil at temperature 398K for tank vehicles lubrication and hydraulic system test was built, and all important state parameters of the oil supply system were measured and control by PLC and remote computer.