Design And Study Of The Vacuum-Pump Deaerating Device For Hydraulic Oil

The main negative influences of entrapped air on the hydraulic system are reducing the bulk-modulus and the rigidity of the oil so making the response characteristic worse, wasting energy to compress the oil and increasing the oil temperature for the increased compressibility of the oil, causing cavitation erosion so aggravating denudation on the surface of the components also producing vibration and noise in the system, oxidizing the oil so making the lubricating ability of the oil decreasing but the acid number and the sediment increasing, destroying the oil film between the pairing element so picking up attrition wear. Thus, in the process of design and manufacture of the hydraulic system, some efficient ways should be taken to reduce the entrapped air.In this paper, a vacuum-pump deaerating device for hydraulic oil is discussed. The piston pressure accumulator of the divice can make the liquid surface of the closed oil tank descending, then use a vacuum pump to take out vacuum to the supper space of the tank. In the hydurulic oil there is great difference between the seperating pressure of the air, water content and volatile substance from said oil and the saturated vapor pressure of said oil. With the vacuuming technique, the air, water content and volatile substance which are sealed in a tank can be seperated and exhausted. In addition, the vacuum-pump deaerating device can force pressure on the tank and produce a comparatively stable backing pressure when the hydraulic system works.The work is following as:In chapter 1, elaborate the bubble forming and its damage to the hydraulic system. The history and current research status of gas/oil seperating are introduced based on a lot of the publications and conference papers. Consequently, the research and the goal of the project are brought forward.In chapter 2, the velocity of bubbles rising in oil and its influencing factors are discussed. Then carry on principle design of the vacuum-pump deaerating device, some core parameters are fixed on, which make sure the device work reliably. At last, introduce the choice of system components and the integration design.In chapter 3, introduce the function of the vacuum-pump deaerating device in forcing and balancing the tank's pressure. Do AMEsim simulation analysis of the pressue tank under the variable loads, and the result shows if the total start-pressure of the cylinder and the accumulator is lower than 0.5bar, the oil tank can work normally. Carry on low friction structure design of the cylinder and the piston pressure accumulator.In chapter 4, carry on some experimental researches around the device. The total start-pressure of the cylinder and piston pressure accumulator is lower than 0.2bar, and the leakage of the accumulator is small. The piston pressure accumulator and the low-pressure accumulator connected with the tank can control the tank's pressure fluctuation easily. And the results prove that the vacuum-pumping deaerating device can reduce the entrapped air efficiently.In chapter 5, the conclusions are reached and the new views are put forward.