CN103163183B - The detection method of iron or liquid water content in a kind of lubricating oil - Google Patents

Abstract

In order to solve the problems of the prior art detection method of iron and water content in lubricating oil, which are greatly influenced by human factors, low analysis speed, expensive equipment, high experiment cost and low detection accuracy, the present invention proposes a method to detect iron or water content in lubricating oil. The detection method uses the excitation current with set frequency and intensity to measure the impedance value of the lubricating oil, and uses the cubic equation y=aa ₁ x+a ₂ x ² -a ₃ x ³ to calculate the content of iron or water in the lubricating oil, where , y is the content of iron or water in the lubricating oil, the unit is %, x is the resistance value of the lubricating oil, the unit is Ω, a, a ₁ , a ₂ , a ₃ are coefficients. The beneficial effect of the method for detecting iron or water content in lubricating oil of the present invention is that the iron or water content in lubricating oil is detected by equipment with low cost, the measurement speed is fast, the operation is simple and convenient, and the measurement result is accurate, reliable and repeatable good.

Description

A detection method of iron or water content in lubricating oil

technical field

The invention relates to a detection technology for iron or water content in lubricating oil, in particular to a detection method for iron or water content in lubricating oil.

Background technique

Generally, lubricating oil is used as a lubricant in the transmission mechanism or speed change mechanism of mechanical devices. When it is used, the lubricating oil is placed in a closed or circulating system to lubricate the shafts and gears of the transmission mechanism or speed change mechanism. Because the shaft or gear in the transmission mechanism or speed change mechanism of the mechanical device will be worn, the particles made of the shaft or gear made of iron or metal will be suspended in the lubricating oil, that is, the mechanical impurities in the lubricating oil will increase, especially The content of iron or metals will increase. At this time, not only the lubricating effect of the lubricating oil will decrease rapidly, but the particles suspended in the lubricating oil will also form hard abrasive particles, which will have a very adverse effect on the transmission mechanism or speed change mechanism. In addition, during the storage, transportation and use of lubricating oil, water in the air or cooling water may be mixed into the lubricating oil, which may cause loss of additives in the lubricating oil, oxidation of the lubricating oil, reduction of the thickness of the lubricating oil film, and microbial contamination. Breeding, etc., may also cause corrosion to mechanical parts. Therefore, when the iron content or water content in the lubricating oil exceeds a certain value, it will have a very adverse effect. The national standard GB/T260 has formulated detailed indicators for the replacement of lubricating oil, among which the content of iron and water in the lubricating oil is an important indicator.

Existing methods for detecting iron content in lubricating oil mainly include on-line ferrography, spectroscopic analysis and electrical methods. Among them, on-line ferrography uses magnetic gradient and gravity gradient to separate metal abrasive particles from Size-arranged oil detection technology, this method can determine the size and type of wear particles in the oil, but quantitative ferrography has its inaccuracy, and wear particle analysis mainly depends on the knowledge level and practical experience of the operator. The human factors are greatly affected, the sampling is not representative, and it takes a long time to make ferrography, and the analysis speed is low; spectral analysis methods include atomic emission spectrometry, atomic absorption spectrometry, infrared spectroscopic analysis and X-ray fluorescence spectrometry Generally, the oil does not need pretreatment, the reading is accurate, and the repeatability is good, but this kind of spectrometer is generally expensive, the installation conditions are strict, the experiment cost is high, and it is difficult to popularize in the production site; the electrical monitoring methods include conductivity and capacitance methods. The detection accuracy of the two measurement methods is not very high. The methods for detecting water content in lubricating oils in the prior art mainly include laboratory analysis methods, spectral analysis methods and electrical methods, etc., wherein the laboratory analysis methods mainly include gravimetric method, distillation method and Karl Fischer method, although the method The method is widely used, but its determination process is complicated, time-consuming, and has defects such as inaccurate detection results, high cost, and not suitable for on-line measurement; spectral analysis methods include atomic emission spectrometry, atomic absorption spectrometry, infrared spectroscopic analysis and Although X-ray fluorescence spectrometry has the advantages of no need for pretreatment of oil, accurate readings and good repeatability, it has the disadvantages of expensive equipment, strict installation conditions and high experimental costs; the monitoring of electrical methods includes conductivity and capacitance methods. , the detection accuracy of these two measurement methods is not very high. Apparently, the prior art method for detecting iron and water content in lubricating oil has problems such as greater influence of human factors, low analysis speed, expensive equipment, high experiment cost and low detection accuracy.

Contents of the invention

In order to solve the problems of the prior art detection method of iron and water content in lubricating oil, which are greatly influenced by human factors, low analysis speed, expensive equipment, high experiment cost and low detection accuracy, the present invention proposes a method to detect iron or water content in lubricating oil. detection method. The detection method of iron or water content in lubricating oil of the present invention adopts the excitation current of set frequency and intensity to measure the impedance value of lubricating oil, adopts cubic equation y=aa ₁ x+a ₂ x ² -a ₃ x ³ to calculate the iron in lubricating oil or water content, where, y is the content of iron or water in lubricating oil, unit %, x is the resistance value of lubricating oil, unit is Ω, a, a ₁ , a ₂ , a ₃ are coefficients; when detecting lubricating oil When the iron content is low, the set frequency is 2kHz to 10kHz, and the excitation current intensity is 1mA-20mA; when the water content in lubricating oil is detected, the set frequency is 5kHz to 10kHz, and the excitation current intensity The measuring temperature is 20°C to 25°C, the measuring container is a cylinder with a diameter of 38.0mm and a height of 50.0mm, and the measuring electrode is a disc with a diameter of 38.0mm. The measuring electrode is symmetrically placed in the geometric center of the container, and the measuring electrode The spacing is 3.0mm; where,

When the impedance value of the lubricating oil is measured by an exciting current with a frequency of 4910.0Hz and a current intensity of 20mA, the iron content in the lubricating oil is calculated using the following formula:

y ₁ =75184.6-0.6x ₁ +1.2×10 ^-6 x ₁ ² -9.7×10 ^-13 x ₁ ³

_In the formula: _y1 is the iron content value, the unit is %, x1 is the lubricating oil resistance value, the unit is Ω;

When the impedance value of the lubricating oil is measured by an exciting current with a frequency of 10494.0Hz and a current intensity of 20mA, the water content in the lubricating oil is calculated using the following formula:

y ₂ =200803.48-10439.04x ₂ +2452.86x ₂ ² -219.83x ₂ ³

In the formula: y ₂ is the water content value, the unit is %, x ₂ is the lubricating oil resistance value, the unit is Ω.

Further, the detection method of iron or water content in lubricating oil of the present invention comprises the following steps:

S1. Take the lubricating oil to be tested and put it into a measuring container, place the measuring container on an ultrasonic oscillator and mix for more than 10 minutes, so that the iron particles are evenly suspended in the lubricating oil; the measuring container has a diameter of 38.0mm and a height of 50.0mm the cylindrical shape;

S2. Place the measuring electrodes in the lubricating oil. The measuring electrodes are symmetrically placed in the geometric center of the measuring container. The measuring electrodes are discs with a diameter of 38.0 mm, and the distance between the measuring electrodes is 3.0 mm;

S3. The impedance value of the lubricating oil is tested with the excitation current of the set frequency, and the measurement temperature is 20°C to 25°C; when the iron content in the lubricating oil is detected, the set frequency is 2kHz to 10kHz, and the excitation current The intensity is 1mA-20mA; when detecting the water content in the lubricating oil, the set frequency is 5kHz to 10kHz, and the excitation current intensity is 1mA-20mA;

S4. Use the cubic equation y=aa ₁ x+a ₂ x ² -a ₃ x ³ to calculate the content of iron or water in the lubricating oil, where y is the content of iron or water in the lubricating oil, in %, and x is the resistance of the lubricating oil value, the unit is Ω, a, a ₁ , a ₂ , a ₃ are coefficients; among them,

When the impedance value of the lubricating oil is measured by an exciting current with a frequency of 4910.0Hz and a current intensity of 20mA, the iron content in the lubricating oil is calculated using the following formula:

y ₁ =75184.6-0.6x ₁ +1.2×10 ^-6 x ₁ ² -9.7×10 ^-13 x ₁ ³

_In the formula: _y1 is the iron content value, the unit is %, x1 is the lubricating oil resistance value, the unit is Ω;

When the impedance value of the lubricating oil is measured by an exciting current with a frequency of 10494.0Hz and a current intensity of 20mA, the water content in the lubricating oil is calculated using the following formula:

y ₂ =200803.48-10439.04x ₂ +2452.86x ₂ ² -219.83x ₂ ³

In the formula: y ₂ is the water content value, the unit is %, x ₂ is the lubricating oil resistance value, the unit is Ω.

The beneficial effect of the method for detecting iron or water content in lubricating oil of the present invention is that the iron or water content in lubricating oil is detected by equipment with low cost, the measurement speed is fast, the operation is simple and convenient, and the measurement result is accurate, reliable and repeatable good.

Description of drawings

Fig. 1 is the detection step schematic diagram of the detection method of iron or water content in lubricating oil of the present invention;

Fig. 2 is the impact curve of excitation current intensity on the impedance value of lubricating oil with different iron contents;

Fig. 3 is the impact curve of excitation current intensity on the impedance value of lubricating oil with different water contents;

Fig. 4 is the influence curve of setting frequency on the impedance value of lubricating oil with different iron contents;

Fig. 5 is the influence curve of setting frequency on the impedance value of lubricating oil with different water contents;

Fig. 6 is a cubic relationship curve between lubricating oil resistance value and iron content concentration.

The method for detecting iron or water content in lubricating oil of the present invention will be further described below in combination with specific embodiments and accompanying drawings.

Detailed ways

Fig. 1 is the detection step schematic diagram of the detection method of the iron content in the lubricating oil of the present invention, as can be seen from the figure, the detection method of the iron or water content in the lubricating oil of the present invention adopts the exciting current of setting frequency and intensity to measure the lubricating oil impedance value, adopts The cubic equation y=aa ₁ x+a ₂ x ² -a ₃ x ³ calculates the content of iron or water in the lubricating oil, where y is the content of iron or water in the lubricating oil, in %, and x is the resistance value of the lubricating oil, in is Ω, a, a ₁ , a ₂ , and a ₃ are coefficients; when detecting the iron content in lubricating oil, the set frequency is 2kHz to 10kHz, and the excitation current intensity is 1mA-20mA; when detecting lubricating oil When the water content in the medium is high, the set frequency is 5kHz to 10kHz, the excitation current intensity is 1mA-20mA; the measurement temperature is 20°C to 25°C, and the measurement container is a cylinder with a diameter of 38.0mm and a height of 50.0mm. The electrode is a disc with a diameter of 38.0mm, and the measuring electrodes are symmetrically placed in the geometric center of the container, and the distance between the measuring electrodes is 3.0mm; among them,

When the impedance value of the lubricating oil is measured by an exciting current with a frequency of 4910.0Hz and a current intensity of 20mA, the iron content in the lubricating oil is calculated using the following formula:

y ₁ =75184.6-0.6x ₁ +1.2×10 ^-6 x ₁ ² -9.7×10 ^-13 x ₁ ³

_In the formula: _y1 is the iron content value, the unit is %, x1 is the lubricating oil resistance value, the unit is Ω;

When the impedance value of the lubricating oil is measured by an exciting current with a frequency of 10494.0Hz and a current intensity of 20mA, the water content in the lubricating oil is calculated using the following formula:

y ₂ =200803.48-10439.04x ₂ +2452.86x ₂ ² -219.83x ₂ ³

In the formula: y ₂ is the water content value, the unit is %, x ₂ is the lubricating oil resistance value, the unit is Ω.

Further, the detection method of iron or water content in lubricating oil of the present invention comprises the following steps:

S1. Take the lubricating oil to be tested and put it into a measuring container, place the measuring container on an ultrasonic oscillator and mix for more than 10 minutes, so that the iron particles are evenly suspended in the lubricating oil; the measuring container has a diameter of 38.0mm and a height of 50.0mm the cylindrical shape;

S2. Place the measuring electrodes in the lubricating oil. The measuring electrodes are symmetrically placed in the geometric center of the measuring container. The measuring electrodes are discs with a diameter of 38.0 mm, and the distance between the measuring electrodes is 3.0 mm;

S3. The impedance value of the lubricating oil is tested with the excitation current of the set frequency, and the measurement temperature is 20°C to 25°C; when the iron content in the lubricating oil is detected, the set frequency is 2kHz to 10kHz, and the excitation current The intensity is 1mA-20mA; when detecting the water content in the lubricating oil, the set frequency is 5kHz to 10kHz, and the excitation current intensity is 1mA-20mA;

S4. Use the cubic equation y=aa ₁ x+a ₂ x ² -a ₃ x ³ to calculate the content of iron or water in the lubricating oil, where y is the content of iron or water in the lubricating oil, in %, and x is the resistance of the lubricating oil Value, the unit is Ω, a, a ₁ , a ₂ , a ₃ are coefficients; among them,

When the impedance value of the lubricating oil is measured by an exciting current with a frequency of 4910.0Hz and a current intensity of 20mA, the iron content in the lubricating oil is calculated using the following formula:

y ₁ =75184.6-0.6x ₁ +1.2×10 ^-6 x ₁ ² -9.7×10 ^-13 x ₁ ³

_In the formula: _y1 is the iron content value, the unit is %, x1 is the lubricating oil resistance value, the unit is Ω;

When the impedance value of the lubricating oil is measured by an exciting current with a frequency of 10494.0Hz and a current intensity of 20mA, the water content in the lubricating oil is calculated using the following formula:

y ₂ =200803.48-10439.04x ₂ +2452.86x ₂ ² -219.83x ₂ ³

In the formula: y ₂ is the water content value, the unit is %, x ₂ is the lubricating oil resistance value, the unit is Ω.

In order to illustrate the feasibility of the method for detecting iron or water content in lubricating oil of the present invention, first, the influence of excitation current intensity on the impedance value of lubricating oil with different iron or water content is studied. The samples of artificially prepared iron-containing or water lubricating oil were used, the iron contents were 0.025%, 1.0% and 2.0% respectively, and the water contents were 0.1%, 1.25% and 2.5% respectively. After fully stirring and mixing evenly, under the condition that the set frequency is 1KHz and 10KHz respectively, the impedance value of the sample is measured from 0 to 20mA with different excitation current intensities. The measurement results are shown in Figure 2 and Figure 3 Show. The curves in Figure 2 correspond to iron contents of 0.025%, 1.0% and 2.0% from top to bottom, and the curves in Figure 3 correspond to water contents of 0.1% and 1.25% from top to bottom. and 2.5%. It can be seen from accompanying drawings 2 and 3 that although the contents of iron or water in the samples are different, when the excitation current intensity is greater than 1mA, the fluctuation of the lubricating oil resistance value is small. Also, the larger the excitation current, the smaller the fluctuation of the impedance value. That is, when the excitation current is large enough, the detected impedance value is basically a constant value. It shows that when the excitation current is greater than 1mA, no matter how the content of iron or water in the lubricating oil is, the impedance value can be measured to a certain value. The above test is performed when the measuring container is a cylinder with a diameter of 38.0mm and a height of 50.0mm; the measuring electrodes are symmetrically placed at the geometric center of the measuring container, the measuring electrodes are discs with a diameter of 38.0mm, and the distance between the measuring electrodes is 3.0mm; the measuring temperature is 20 under the condition of ℃ to 25℃.

Under the same experimental conditions, the impedance value of the iron-containing lubricating oil sample was measured from 2KHz to 10KHz with different frequency settings under the condition of the excitation current intensity of 20mA, and from 5KHz to 10KHz with different settings. The impedance value of the water-containing lubricating oil sample was measured at a constant frequency, and the measurement results are shown in accompanying drawings 4 and 5. The curves in accompanying drawing 4 correspond to iron contents of 0.025%, 1.0% and 2.0% respectively from top to bottom, and the curves in accompanying drawing 5 correspond to water contents of 0.1% and 1.25% respectively from top to bottom and 2.5%. As can be seen from accompanying drawings 4 and 5, in the frequency range used in the experiment, although the impedance value of each sample decreases with the increase of frequency, the impedance value of the sample and its iron or water content have a good correlation. It can be seen that when detecting the iron content in lubricating oil, an excitation current with a frequency of 2kHz to 10kHz and a current intensity of 1mA-20mA can be used to measure the impedance value of the iron-containing lubricating oil sample; when detecting the water content in lubricating oil , the impedance value of the water-containing lubricating oil sample can be measured by using an exciting current with a frequency of 5kHz to 10kHz and a current intensity of 1mA-20mA.

In addition, the above measurement results also show that the impedance values of lubricating oils with different iron or water contents all decrease with the increase of frequency, and there are significant differences among them. Therefore, the relationship between the iron or water content in the lubricating oil and the impedance value can be determined. Since there is a good correlation between the iron content and the impedance value in the frequency range from 2kHz to 10kHz, any one of the above frequencies can be selected as the characteristic frequency value to analyze the relationship between the lubricating oil impedance value and the iron or water content. The excitation current with a frequency of 4910.0Hz and a current intensity of 20mA was selected for detection, and a mathematical model of the relationship between lubricating oil impedance and iron content concentration was established. There was a cubic curve relationship between impedance value and iron content concentration, so cubic curve fitting was used. Accompanying drawing 6 is the cubic relationship curve between the lubricating oil impedance value and the iron content concentration, in the figure, the ordinate is the iron content y ₁ in the lubricating oil, the unit is %, and the abscissa is the lubricating oil impedance value x ₁ , the unit is Ω . From this, the cubic equation relationship between the lubricating oil impedance value and the iron content concentration can be obtained when the excitation current with a frequency of 4910.0 Hz and a current intensity of 20 mA is used for detection:

y ₁ =75184.6-0.6x ₁ +1.2×10 ^-6 x ₁ ² -9.7×10 ^-13 x ₁ ³

In the formula: y ₁ is the iron content value, the unit is %, x ₁ is the lubricating oil resistance value, the unit is Ω.

In the same way, the cubic equation relationship between the lubricating oil impedance value and the water content concentration can be obtained when the excitation current with a frequency of 10494.0Hz and a current intensity of 20mA is used for detection:

y ₂ =200803.48-10439.04x ₂ +2452.86x ₂ ² -219.83x ₂ ³

In the formula: y ₂ is the water content value, the unit is %, x ₂ is the lubricating oil resistance value, the unit is Ω.

As mentioned above, when detecting the iron content in the lubricating oil, the impedance value of the iron-containing lubricating oil sample has a good correlation with the iron content in the frequency range of 2kHz to 10kHz; when detecting the water in the lubricating oil When the frequency is in the range of 5kHz to 10kHz, the impedance value of the water-containing lubricating oil sample has a good correlation with its water content. Therefore, the cubic equation y=aa ₁ x+a ₂ x ² -a ₃ x ³ can be used to calculate the content of iron or water in lubricating oil, where y is the content of iron or water in lubricating oil in %, and x is lubricating oil Impedance value, unit is Ω, a, a ₁ , a ₂ , a ₃ are coefficients.

Specific embodiment 1

For verifying the accuracy and the reliability of the detection method of iron content in the lubricating oil of the present invention, adopt artificially prepare the sample of iron-containing lubricating oil, its iron content is respectively 0.15%, 0.5%, 0.75%, 1% and 2%, After fully stirring evenly, the impedance value of the above-mentioned sample is detected by the detection method of the present invention, and the detection iron content value is calculated, wherein, the set frequency is 4910.0Hz, and the excitation current is 20mA, and the detection results are as follows in Table 1 shown.

Table 1: Test results of test samples under the conditions of 4910.0Hz and 20mA

1 2 3 4 5 Remark Theoretical iron content 0.15% 0.5% 0.75% 1% 2% Check iron content 0.141% 0.493% 0.734% 0.971% 1.935%

From the results shown in Table 1, it can be seen that the actual detection of the iron content in the lubricating oil of the present invention is obtained by the iron content and the iron content added when making the sample, that is, the theoretical iron content is basically the same, and has a smaller error range .

Specific embodiment 2

Using basically the same detection conditions as those in Embodiment 1, only setting the frequency at 1.91kHz and the excitation current at 20mA, the detection results are shown in Table 2 below.

Table 2: Detection results of test samples under the conditions of 1.91kHz and 20mA

1 2 3 4 5 Remark Theoretical iron content 0.15% 0.5% 0.75% 1% 2% Check iron content 0.131% 0.473% 0.725% 0.912% 1.867%

From the results shown in Table 2, it can be seen that the actual detection of the iron content in the lubricating oil of the present invention is obtained by the iron content and the iron content added when making the sample, that is, the theoretical iron content is basically the same, and has a smaller error range . In this embodiment the frequency is set at a lower value and the excitation current is set at a higher value.

Specific embodiment 3

Using basically the same detection conditions as in Embodiment 1, only setting the frequency at 9.2kHz and the excitation current at 2mA, the detection results are shown in Table 3 below.

Table 3: Detection results of test samples under the conditions of 9.2kHz and 2mA

1 2 3 4 5 Remark Theoretical iron content 0.15% 0.5% 0.75% 1% 2% Check iron content 0.134% 0.475% 0.732% 0.946% 1.923%

From the results shown in Table 3, it can be seen that although the set frequency and excitation current have changed, the method for detecting iron content in lubricating oil of the present invention can still obtain relatively accurate detection results, and has a small error range. In this embodiment the frequency is set to a higher value and the excitation current to a lower value.

Specific embodiment 4

Using basically the same detection conditions as in Embodiment 1, only setting the frequency at 4.82kHz and the excitation current at 9.5mA, the detection results are shown in Table 4 below.

Table 4: Detection results of test samples under the conditions of 4.82kHz and 9.5mA

1 2 3 4 5 Remark Theoretical iron content 0.15% 0.5% 0.75% 1% 2% Check iron content 0.138% 0.478% 0.736% 0.96% 1.95%

From the results shown in Table 4, it can be seen that although the set frequency and excitation current have changed, the detection method of iron content in lubricating oil according to the present invention can still obtain relatively accurate detection results, and has a small error range. In this embodiment, both the set frequency and the excitation current are intermediate values.

Specific embodiment 5

In order to verify the accuracy and reliability of the detection method of the water content in the lubricating oil of the present invention, adopt artificially prepare the sample of water-containing lubricating oil, its water content is respectively 0.1%, 0.2%, 0.5%, 0.75%, 1.25%, 2.5%, 5%, after fully stirring evenly, the impedance value of the above-mentioned sample is detected by the detection method of the present invention, and the detection water content value is calculated, wherein, the set frequency is 10494.0Hz, the excitation current is 20mA, The test results are shown in Table 4 below.

Table 5: Detection results of test samples under the conditions of 10494.0Hz and 20mA

1 2 3 4 5 6 7 Remark Theoretical water content 0.1% 0.2% 0.5% 0.75% 1.25% 2.5% 5% Check water content 0.108% 0.231% 0.523% 0.761% 1.231% 2.403% 5.012%

As can be seen from the results shown in Table 5, the water content obtained by the actual detection of the detection method for water content in lubricating oil of the present invention is substantially the same as the water content added when making the sample, i.e. the theoretical water content, and has a smaller error scope.

Specific embodiment 6

Using basically the same detection conditions as in Embodiment 5, only setting the frequency at 5.165 kHz and the excitation current at 2 mA, the detection results are shown in Table 6 below.

Table 6: Detection results of test samples under the conditions of 5.165kHz and 20mA

1 2 3 4 5 6 7 Remark Theoretical water content 0.1% 0.2% 0.5% 0.75% 1.25% 2.5% 5% Check water content 0.119% 0.250% 0.547% 0.786% 1.319% 2.243% 5.032%

As can be seen from the results shown in Table 6, the water content obtained through the actual detection of the detection method for water content in lubricating oil of the present invention is substantially the same as the water content added when making the sample, that is, the theoretical water content, and has a smaller error scope. In this embodiment the frequency is set at a lower value and the excitation current is set at a higher value.

Specific embodiment 7

Using basically the same detection conditions as in Embodiment 5, only setting the frequency at 8.146kHz and the excitation current at 2mA, the detection results are shown in Table 7 below.

Table 7: Detection results of test samples under the conditions of 8.146kHz and 2mA

1 2 3 4 5 6 7 Remark Theoretical water content 0.1% 0.2% 0.5% 0.75% 1.25% 2.5% 5% Check water content 0.149% 0.284% 0.570% 0.717% 1.953% 2.203% 5.066%

It can be seen from the results shown in Table 7 that although the set frequency and excitation current have changed, the detection method for water content in lubricating oil of the present invention can still obtain relatively accurate detection results, and has a small error range. In this embodiment the frequency is set to a higher value and the excitation current to a lower value.

Specific embodiment 8

Using basically the same detection conditions as in Embodiment 5, only setting the frequency at 4.82kHz and the excitation current at 9.5mA, the detection results are shown in Table 8 below.

Table 8: Detection results of test samples under the conditions of 10494kHz and 9.5mA

1 2 3 4 5 6 7 Remark Theoretical water content 0.1% 0.2% 0.5% 0.75% 1.25% 2.5% 5% Check water content 0.110% 0.264% 0.407% 0.744% 1.804% 2.264% 5.017%

From the results shown in Table 8, it can be seen that although the set frequency and excitation current have changed, the method for detecting water content in lubricating oil of the present invention can still obtain relatively accurate detection results, and has a small error range. In this embodiment, both the set frequency and the excitation current are intermediate values.

Obviously, the beneficial effect of the method for detecting iron or water content in lubricating oil of the present invention is that the equipment with lower cost is used to detect the iron content or water content in lubricating oil, the measurement speed is fast, the operation is simple and convenient, and the measurement result is accurate, reliable and reliable. Good repeatability.

Claims (2)

1. A detection method for iron or water content in lubricating oil, characterized in that: the impedance value of the lubricating oil is measured by an exciting current with a set frequency and intensity, and the cubic equation y=aa ₁ x+a ₂ x ² -a is used ₃ x ³ calculates the content of iron or water in lubricating oil, in the formula, y is the content of iron or water in lubricating oil, the unit is %, x is the impedance value of lubricating oil, the unit is Ω, a, a ₁ , a ₂ , a ₃ are coefficient; when detecting the iron content in lubricating oil, the set frequency is 2kHz to 10kHz, and the excitation current intensity is 1mA-20mA; when detecting the water content in lubricating oil, the set frequency is 5kHz to 10kHz, the excitation current intensity is 1mA-20mA; the measurement temperature is 20°C to 25°C, the measurement container is a cylinder with a diameter of 38.0mm and a height of 50.0mm, and the measurement electrode is a disc with a diameter of 38.0mm, and the measurement electrodes are symmetrically placed in the container The geometric center of , the distance between the measuring electrodes is 3.0mm; among them, When the impedance value of the lubricating oil is measured by an exciting current with a frequency of 4910.0Hz and a current intensity of 20mA, the iron content in the lubricating oil is calculated using the following formula: y ₁ =75184.6-0.6x ₁ +1.2×10 ^-6 x ₁ ² -9.7×10 ^-13 x ₁ ³ _In the formula: _y1 is the iron content value, the unit is %, x1 is the lubricating oil resistance value, the unit is Ω; When the impedance value of the lubricating oil is measured by an exciting current with a frequency of 10494.0Hz and a current intensity of 20mA, the water content in the lubricating oil is calculated using the following formula: y ₂ =200803.48-10439.04x ₂ +2452.86x ₂ ² -219.83x ₂ ³ In the formula: y ₂ is the water content value, the unit is %, x ₂ is the lubricating oil resistance value, the unit is Ω. 2. according to the detection method of iron or water content in the described lubricating oil of claim 1, it is characterized in that: the method comprises the following steps: S1. Take the lubricating oil to be tested and put it into a measuring container, place the measuring container on an ultrasonic oscillator and mix for more than 10 minutes, so that the iron particles are evenly suspended in the lubricating oil; the measuring container has a diameter of 38.0mm and a height of 50.0mm the cylindrical shape; S2. Place the measuring electrodes in the lubricating oil. The measuring electrodes are symmetrically placed in the geometric center of the measuring container. The measuring electrodes are discs with a diameter of 38.0 mm, and the distance between the measuring electrodes is 3.0 mm; S3. The impedance value of the lubricating oil is tested with the excitation current of the set frequency, and the measurement temperature is 20°C to 25°C; when the iron content in the lubricating oil is detected, the set frequency is 2kHz to 10kHz, and the excitation current The intensity is 1mA-20mA; when detecting the water content in the lubricating oil, the set frequency is 5kHz to 10kHz, and the excitation current intensity is 1mA-20mA; S4. Use the cubic equation y=aa ₁ x+a ₂ x ² -a ₃ x ³ to calculate the content of iron or water in the lubricating oil, where y is the content of iron or water in the lubricating oil, in %, and x is the resistance of the lubricating oil value, the unit is Ω, a, a ₁ , a ₂ , a ₃ are coefficients; among them, When the impedance value of the lubricating oil is measured by an exciting current with a frequency of 4910.0Hz and a current intensity of 20mA, the iron content in the lubricating oil is calculated using the following formula: y ₁ =75184.6-0.6x ₁ +1.2×10 ^-6 x ₁ ² -9.7×10 ^-13 x ₁ ³ _In the formula: _y1 is the iron content value, the unit is %, x1 is the lubricating oil resistance value, the unit is Ω; When the impedance value of the lubricating oil is measured by an exciting current with a frequency of 10494.0Hz and a current intensity of 20mA, the water content in the lubricating oil is calculated using the following formula: y ₂ =200803.48-10439.04x ₂ +2452.86x ₂ ² -219.83x ₂ ³ In the formula: y ₂ is the water content value, the unit is %, x ₂ is the lubricating oil resistance value, the unit is Ω.