【作者】 钱敏；

【导师】 冯志华；

【作者基本信息】 中国科学技术大学 ， 仪器科学与技术， 2022， 博士

【摘要】 金属微粒检测技术对于维护和延长机械设备的健康稳定运行至关重要。电磁感应式金属微粒检测器(IDM)因其结构紧凑、成本低、测量速度快、可提供丰富的金属微粒信息等优点,在工业界得到了广泛应用。然而,由于IDM中分辨率与流量的制约关系,在保证大流量的前提下很难实现传感器的高分辨率,各种噪声干扰也限制了传感器的分辨率,当前的技术无法满足实际设备的在线监控需求。本文以电磁感应式金属微粒检测器为研究对象,开展了一系列研究工作,旨在提高其对金属微粒的检测分辨率,及在不降低检测分辨率的情况下提高检测液体流量。本文的主要研究内容与创新点包括:一、基于金属微粒的磁偶极子等效模型,建立了传统三线圈式IDM的输出响应数学表达式,并在理论分析的基础上,借助有限元仿真系统地研究了激励参数和探头参数对传感器输出特性的影响,为后续的高分辨率IDM设计提供理论指导。提出了 IDM的技术因子和空间分辨率的概念,有利于完善IDM的性能评价体系。二、针对传统三线圈式IDM中分辨率与流量的制约问题,首次提出了一款基于高Q值谐振法的并联式高灵敏探头,为高分辨率IDM的实现提供有效手段。特殊设计的大电感与感应线圈、外部电容组成的高Q值谐振回路适用于小流道探测,可以显著提高探头灵敏度,从而实现IDM对金属微粒的高检测分辨率,同时并联式的多流道设计也满足了传感器的大流量需求。研制的传感器样机中单个探测流道的外径为3 mm,7个探测流道并联后流量为148.4 L/min,谐振回路Q值为104。该样机能检测小至23 μm的铁微粒和64 μm的铜微粒,技术因子高达434,远高于现有文献中的技术水平。三、在全面分析IDM系统噪声以及大电流激励特点的基础上,首次提出了一种间歇式电流激励方法和设计实现了基于间歇激励的高分辨率电路系统,进一步提高了 IDM的分辨率、量程和温度稳定性。详细介绍了基于间歇激励的高分辨率电路系统的设计过程,并通过实验获得了其检测性能。所制作的传感器样机温度稳定性良好,在外径为10 mm的探测流道内能够检测48 μm-1426 μm的铁微粒和112 μm-3802μm的铜微粒,技术因子为208.3。相比于传统的连续激励式传感器,采用新型间歇激励的传感器在分辨率、量程和稳定性方面均有明显优势。四、对于IDM中几种常见的干扰源,详细分析了其干扰噪声产生机理并提出相应的干扰噪声抑制措施。首先对于杂质干扰,提出了一种新型的低压激励方案,对其进行了理论分析和实验验证。实验结果证明该方案能在不牺牲金属微粒检测性能的情况下,有效抑制水滴、气泡等杂质引起的干扰噪声;对单自由度隔振系统进行了理论分析和仿真计算,设计了双层隔振系统以保持IDM在外部机械振动条件下的工作稳定性;最后探索了在探头、电路和传输线缆设计中的电磁干扰降噪措施,从而提高IDM对金属微粒的检测分辨率以及检测可靠性。本文系统地研究了 IDM分辨率的影响因素,给出了探头输出与多种关联参数的关系,本文的研究成果有助于进一步提高利用IDM进行机械设备状态检测与故障诊断的水平,同时也可为其他原理的微粒检测传感器研究提供新思路。更多还原

【Abstract】 Metal debris detection technology is essential for maintaining and extending the healthy and stable operation of mechanical equipment.Inductive debris monitors(IDMs)have been widely used in the industry due to their compact structure,low cost,fast measurement speed,and rich information on metal debris.However,due to the restricted relationship between the resolution and the flow rate of IDMs,it is difficult to achieve high resolution under the premise of ensuring a high flow rate.Various noise interference also limits the sensor resolution.The current technology cannot meet the online monitoring requirements of actual equipment.This dissertation takes the IDM as the research object and carries out a series of research work,aiming to improve its detection resolution of metal particles and increase the flow rate of detected liquid without reducing the detection resolution.The main research contents and innovations of this dissertation include:1)Based on the equivalent model of metal particles,the mathematical expression of the output response of the three-coil sensor is established.On the basis of theoretical analysis,the influence of excitation parameters and probe parameters on sensor performance is systematically studied with the help of finite element simulation,which provides theoretical guidance for the subsequent design of the high-resolution IDM.The concept of the technical factor and spatial resolution of the IDM is proposed,which is beneficial to improve the performance evaluation system of the IDM.2)Aiming at the limitation of the resolution and flow rate in the IDM with the traditional three-coil probe,a parallel high-sensitivity probe based on the high-Q resonance method is proposed for the first time,which provides an effective means for the realization of the high-resolution IDM.The high-Q resonant circuit composed of a specially designed large inductance,sensing coils,and an external capacitor is suitable for debris detection in a small channel,which can significantly improve the sensitivity of the probe,thereby realizing the high-resolution IDM.At the same time,the parallel multi-channel design also meets the large flow requirements of the sensor.Every detection channel in the developed sensor prototype has an outer diameter of 3 mm,and the flow rate of 7 channels in parallel is 148.4 L/min;the Q value is up to 104.The sensor can detect iron particles as small as 23 μm and copper particles as small as 64μm,with a technical factor as high as 434,which is much higher than the technical level in the existing literature.3)On the basis of comprehensive analysis of IDM system noise and high current excitation characteristics,an intermittent current excitation method is developed for the first time and a high-resolution circuit system based on intermittent excitation is designed and implemented,which further improves the detection resolution,range,and temperature stability of the IDM.The design process of the circuit system based on intermittent excitation is introduced in detail,and its detection performance is obtained by experiments.The sensor prototype has good temperature stability and can detect iron particles of 48 μm-1426 μm and copper particles of 112 μm-3802 μm in a detection channel with an outer diameter of 10 mm.The technical factor is 208.3.Compared with the traditional constant excitation sensor,the sensor using intermittent excitation has obvious advantages in detection resolution,range,and stability.4)For several common interference sources in the IDM,the generation mechanism of interference noise is analyzed in detail and corresponding noise suppression measures are proposed.Firstly,for impurity interference,a new low-voltage excitation scheme is proposed,which is theoretically analyzed and experimentally verified.The experimental results show that the scheme can effectively suppress the interference noise caused by impurities such as water droplets and bubbles without sacrificing the detection sensitivity of metal particles.The theoretical calculation and simulation analysis of the single-degree-of-freedom vibration isolation system are carried out,and a double-layer vibration isolation system is designed to maintain the working stability of the IDM under external mechanical vibration conditions.Finally,the electromagnetic noise suppression measures in the design of probes,circuits,and transmission cables are explored to improve the detection resolution and reliability of IDM for metal debris.In this dissertation,the influencing factors of the detection resolution of the IDM are systematically studied,and the relationship between the output of the sensor probe and various related parameters is given.The research results help to further improve the level of mechanical equipment health monitoring and fault diagnosis using IDM,and also provide new ideas for the research of metal debris detection sensors based on other principles.更多还原