| How to effectively control the contaminant content in the aviation hydraulic system to improve the system reliability and component life is an advanced subject of the international aviation field.In this dissertation,the general situation of research on aviation oil contamination control technology is first reviewed.The focus of the dissertation lies in reducing the contaminant content in the system.Based on the technical methods of real-time detection of oil contaminant content,isolating system form the external environment and efficiently purification of the main contaminants in the system,a systematically research has been made on the active control of oil contamination technology from both theoretical research and system design.In view of the main problems in the existing aircraft ground maintenance equipment,the relationship between the main contaminant content and the life of hydraulic components in aircraft hydraulic system was discussed,and influence of contaminant active control technology on the contaminant content in the system was clarified.The innovative active control system of oil contamination was designed to realize the efficient maintenance of aviation hydraulic system,and thus providing a new technology and method to improve the reliability of the system and the service life of components.The main original conclusions of this work are drawn.(1)The sources and hazards of the main contaminants in the aviation hydraulic system were systematically studied.The existing forms,sources and hazards of water,gas and solid particulate in 2-5μm which are ignored by the existing research were analyzed emphatically.It was clarified that the solid particles in 2-5μm,water and gas are the main factors that affect the life of aircraft hydraulic system in this dissertation,and the main research object of oil purification technology were revealed.(2)The generation rate of main contaminants in the system were quantitatively analyzed,and the system purification model and the pattern of the active control system were established.Based on the quantitative analysis of the generation rate of the main contaminants,one of the main reasons for the lack of purification capability of existing ground maintenance systems is the neglect of the contaminant generation rate.The relationship between the purification ratio of the system and the design parameters was calculated.The purification ratio the system was calculated by establishing the system purification mathematical model.The method of combining the vacuum purification method with the centrifugal purification method was determined to be the effective purification method by the comparison of existing targeted purification method.The pattern of active control system was established with a closed elastic tank and a vacuum centrifugal purification equipment,and the maintenance circuit was redesigned as a closed circuit.It is clarified that the effective method to improve reliability and service life of the system is reducing the contaminant generation rate while improving the equipment purification ability.(3)The active control system of oil contamination and its main modules were designed.Based on the main deficiencies of the open tank,a closed elastic tank was designed to reduce the rate of contaminant invasion.The force and movement of the contaminant particulate in the centrifugal environment was calculated.The key technical parameters of the high-speed vacuum centrifuge were also calculated based on the purification ratio and other parameters.The equipment model was established and optimized to ensure their structural strength and the purification efficiency.The model of the entire active control system was established,and the experimental platform based on the system was tested.Experiments results show that compared with the existing ground maintenance equipment,the active control system of oil contamination can effectively and thoroughly reduce the content of three main contaminants in the oil,thus solve the problem of low purification capacity of the existing maintenance equipment.(4)The contaminant detection device and the automatic control unit of the system were designed.After comparing the detection method of three kinds of main contaminant,the contaminant detection device was designed based on the automatic particle counting method and the image acquisition analysis technology to realize the rapid and accurate detection of the three kinds of contaminant in real time.The main components of the automatic control unit were selected and the general schematic of the system was designed.System control program was written in accordance with the system purification process.The system function of automatically detection and selfrunning is realized by these designs,thus simplifying the operation of on-site maintenance personnel. |
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