Study On The Quality Evaluation And Measurement Uncertainty Of Water Pump

Water pumps, one kind of important electromechanical product, are widely used in various fields, from industry, agriculture to household applications. Although with different run-condition and standards, all of the production has some common demands, such as quality and reliability. The study on their quality evaluation, i.e. the study on their sampling plan, property test and its measurement uncertainty, reliability theories and reliability test, are very important to the estimate of their quality and reliability.The two kinds of mistakes existing in sampling inspection are analyzed and the characteristics of two kinds of sampling inspection are discussed in the dissertation. Under the condition of the inevitable mistakes, the viewpoint that the risk assumed by manufacture side should be controlled chiefly is come up with. To solve the problems existing in current sampling inspection when non-conforming items are used as quality index, Sampling procedures and tables for pump products are designed on the small probability principle of statistics.Based on the theory of error, the article analyses the present situation of measuring technology of pump. Point out that high precision measurement can be realized by the methods and channels, such as using high precision meters, and adjusting them in working position, applying 16 bit A/D transformer, introducing computer to process data, etc. The measurement precision of pump efficiency can be limited to the range from 0.3% to 0.5%. In this paper, the processing methods for pump property data are discussed. A new processing method is put forward that orthogonal polynomial is used to fit the characteristic curves of pump with random data to avoid the ill-conditioned system of equations that probably appears in ordinary polynomial fitting. The Forsythe Recurrence Method is adopted to generate the orthogonal polynomial, and the degree of the polynomial is determined by significance test rather than by experience.The sources of measurement uncertainty in the common pump property tests are discussed and evaluation methods of measurement uncertainty for different indexes are detailedly analyzed in the paper. Meanwhile, the evaluation procedure is given.Because that water pump is one kind of long-life, repairable, complex item, its reliability test plans are different from those of others. In this paper, the distribution ofthe pumps' failure rate is verified, the reliability indexes and failures' criterions are put forward, and the reliability test methods and their test programs are introduced.