Detection instrument for detecting quality of lubricating oil by capacity effect and detection method thereof

Abstract

The invention relates to a detection instrument for detecting the quality of lubricating oil by a capacity effect and a detection method thereof. The detection instrument comprises: a control module, an analog-to-digital conversion module and an electronic switch circuit which are connected with the control module, a comparison circuit an output end of which is connected with the control module, a conversion module, a working power supply and a detected capacitor which are connected with the electronic switch circuit, and a reference voltage connected with the analog-to-digital conversion module and an input end of the comparison circuit, wherein the detected capacitor is connected with the electronic switch circuit and further connected with the input end of the comparison circuit, one end of the detected capacitor is connected with the conversion module, and the output end of the conversion module is connected with the analog-to-digital conversion module. The detection instrument ofthe invention is simple in structure and fast in detection ways; the high-speed analog-to-digital conversion circuit is arranged to implement synchronous sampling and the detected capacitor is connected with a virtual earth end of a charge amplification circuit, thereby eliminating stray capacitances at two ends of the detected capacitor; the electronic switch is arranged for realizing switching-on and switching-off respectively, thereby removing the influence caused by charge injection, and environmental influence is corrected in software to result in high resolution and high precision.

Description

technical field [0001] The invention relates to a lubricating oil detection technology, in particular to a detector and a detection method for detecting the quality of lubricating oil by using capacitance effect. Background technique [0002] At present, professional organizations can be invited to detect the change in the dielectric constant of lubricating oil after a certain period of use, but the detection cycle is longer. The similar detection technology on the market has shortened the service cycle, but it is relatively backward and the accuracy is not high. For example, there is one that uses a constant voltage to charge the measured capacitor through a series resistor and modulates it through a 555 timer to obtain a square wave of charge and discharge. Waveform, and then filter to obtain a voltage signal that can be measured by analog technology. The measurement is not accurate and can only achieve 5% accuracy. Its disadvantages are as follows: [0003] 1. It is not ...

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Problems solved by technology

The similar detection technology on the market has shortened the service cycle, but it is relatively backward and the accuracy is not high. For example, there is one that uses a constant voltage to charge the measured capacitor through a series resistor and modulates it through a 555 timer to obtain a square wave of charge and discharge. Waveform, and then filter to obtain a voltage signal that can be measured by analog technology. The measurement is not accurate and can only achieve 5% accuracy. Its disadvantages are as follows:

[0003] 1. It is not constant current charging, and a linear charging curve cannot be obtained, resulting in inaccurate test results;

[0004] 2. The measured capacitance is very small, about a dozen pF, so the charging is very fast, and the waveform of the charging process is very narrow, resulting in inaccurate detection results;

[0005] 3. In the process of charging the measured capacitor, it is inevitable to charge the surrounding stray capacitors at the same time, resulting in the interference part in the obtained charging waveform;

[0006] 4. The temperature parameter is not considered in the calculation technology, and the influence of temperature and humidity changes is not eliminated, resulting in large errors

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