1、英文原文Development of in-line Oil Contamination Sensor for Lubricant of Scraper Conveyor ReducerZhengduo Pang Nianfeng Shi Guoying Meng1 Wei LiInstitute of Mechanical Electronic & Information Engineering, China University of Mining & Technology, BeijingNo. 11, College Road, Haidian District, Beijing, C
2、hinaDepartment of Computer and Information Engineering, Luoyang Institute of Science and TechnologyNo. 90 Wangcheng Dadao, Luolong District, Luoyang City, Henan Province, ChinaAbstract The development of in-line oil contamination sensor for N320 Lubricant used in scraper conveyor reducer is describe
3、d. The sensor can detect the NAS contamination level of the lubricant and prompt the replacement of oil when the oil contamination level exceeds the indicator of the exchanging standard of L-CKC industrial closed gear oil. This paper describes the sensors design requirements, principle of operation,
4、 selection of wavelength, mechanical structure design and test calibration. The shortcomings of the sensor and relevant solutions are also pointed out in this article. Keywords in-line sensor, mechanical structure design, oil contamination, sensor calibration, optical fiber, scraper conveyor.I. INTR
5、ODUCTIONWear and bad lubrication is the main reason for the failure or major damage of mechanical equipments. Shells latest research data shows that about 35% of the running fault and 38.5% of the gear failure of the diesel engine is generated as a result of improper lubrication 1, 2. Wear particles
6、 is the main source of oil contamination. At present, the application of oil detection used in the industry is based on the early spectrometric analysis and cerography analysis, and use offline methods which cannot meet the requirement of modern industry for condition monitoring and fault diagnosis.
7、 It is therefore necessary to develop an in-line oil contamination detector which can remind operators to adopt filtering devices and replace the oil when the oil contamination level is higher than the prescriptive standard. Among many types of the oil contamination detection techniques, method usin
8、g optical measurement has the advantages of non-contact, real-time and in-line measurement.II. PRINCIPLE OF OPERATIONThe principle of the sensor is based on optical absorption method. It uses optical fiber as the transmission medium and has a lot of advantages such as being anti-interference, free f
9、rom temperature and electromagnetic.Only small particles exist in the oil under the equipments normal wear status. The emergence of large wear particles might damage the equipment in a short period of time. Therefore, on-line monitoring the concentration and size of the wear particles in the lubrica
10、nt can effectively prevent the occurrence of fault. The nature and cause of the wear particles in the oil falls into three categories3,4: mental wear particles, which are both a product of equipment friction and an important indication of serious wear and failure; Non-metallic wear particles which r
11、esult from combustion and failure of the seal and filter device; Environmental pollutant particles, including various particles in the air, especially seen in open systems, where the contamination level is higher and the contaminant usually exists as oxide. The sizes of these particles are between 1
12、-40m, and those between 20-30 m have the greatest impact on the equipment, while those below 1m have no effect on the equipment 5. As a result the sensor should be most sensitive to particles of size between 1-40m.The suspended particles in the oil have a significant impact on the oils optical prope
13、rties. Turbidity can be used to describe the impact of the particles on the light transmittance character of the oil. The connection between the turbidity and contamination level allows this level to be semi-quantitatively determined by measuring the turbidity. Figure 1 shows the schematic of the op
14、tical fiber sensor. The light emitted from the semiconductor laser passes through the optical fiber and fiber-optic collimator and then enters the oil pool of interest. The photo detector collects the photons transmitted and reflected and transforms them into voltage, which conveys information of th
15、e solid particle contamination in the oil.SYSTEMYSTEM PRINCIPLEWhen the light passes through the oil that contains contaminants, part of the light gets scattered and the other absorbed. When a beam of parallel monochromatic light with intensity passes through the oil, its intensity gets reduced to I
16、 as a function of penetration depth L, following the Beer-Lambert 6, 7 law as below:This is the mathematical expression of Lambert Law in the homogeneous media, where is absorption coefficient. When the media is solution, its absorption coefficient is proportional to its concentration c:Where a is a constant independent of the concentration and only decided by the molecular characteristics of the absorbing material. From (1), (2) we c
