JP6852581B2 - Metal impurity measuring device and metal impurity measuring method - Google Patents

Description

The present invention relates to a metal impurity measuring device for measuring metal impurities contained in a sample and a metal impurity measuring method.

Large machines such as large construction machines and mining machines are operating in various environments around the world. In order to operate such a large machine safely and stably, the lubricating oil (gear oil, engine oil, etc.) is analyzed regularly, and the lubricating oil is replaced or replenished as necessary, and the mechanical parts are replaced. Needs maintenance.
Nanoparticles (for example, metal components such as iron (Fe) and copper (Cu)) may be gradually mixed in the lubricating oil by operating a large machine. If the amount of nanoparticles mixed in increases, the performance as a lubricating oil is impaired, and as a result, it leads to malfunction of a large machine.
Therefore, it is necessary to determine the progress of wear of the drive unit of a large machine by analyzing the degree of impurities mixed in the lubricating oil, and to determine the maintenance timing of the lubricating oil and the necessary items for maintenance.

For the analysis of the degree of contamination of the lubricating oil, for example, mass spectrometry, emission spectroscopic analysis, fluorescent X-ray analysis, or the like can be used.
Further, for the analysis of the degree of mixing of metal impurities such as nanoparticles in the lubricating oil, for example, the magnetic powder concentration measuring technique described in Patent Document 1 can be used. This technology uses a detection coil arranged at a position where the combined magnetic field of two exciting coils facing each other becomes zero, and when a sample mixed with magnetic powder is inserted inside one of the exciting coils, the detection coil The concentration of the magnetic powder contained in the sample is measured based on the induced voltage induced in.

Japanese Patent No. 3377348

In recent years, the concentration of metal impurities contained in lubricating oil has been reduced due to the demand for higher performance of engines. Along with this, high sensitivity is also required for measuring instruments, and for example, high measurement accuracy for low-concentration metal impurities of 100 ppm or less is required.
However, in the technique described in Patent Document 1, the inside of the exciting coil is hollow, and the generated magnetic flux is substantially a leakage flux. Therefore, when the concentration of metal impurities in the sample mixed with magnetic powder is small, the fluctuation of the magnetic balance of the synthetic magnetic field by the pair of exciting coils is easily affected by the surrounding environment. For example, the influence of the change in inductance due to temperature fluctuation cannot be ignored, and the value of the induced voltage generated in the detection coil also fluctuates greatly. Therefore, the technique described in Patent Document 1 could not measure the concentration of metal impurities contained in the sample with high sensitivity. In particular, it was not possible to accurately measure low-concentration metal impurities as described above.
Therefore, it is an object of the present invention to provide a metal impurity measuring device and a metal impurity measuring method capable of measuring metal impurities contained in a sample with high sensitivity and accuracy.

In order to solve the above problems, one aspect of the metal impurity measuring device according to the present invention is a first exciting portion formed by winding a first exciting coil around a core material and a second exciting portion around the core material. A second exciting portion formed by winding a coil, a detecting portion formed by winding a detection coil around a core material, and located between the first exciting portion and the second exciting portion. Both ends of the first connecting portion that connects both ends of the core material of the first exciting portion and the core material of the detecting portion to each other, and both ends of the core material of the second exciting portion and the core material of the detecting portion. The first, so that the directions of the second connecting portions that connect the two to each other, the direction of the magnetic field generated by the first exciting coil, and the direction of the magnetic field generated by the second exciting coil are opposite to each other. A high-frequency power supply connected to the exciting coil and the second exciting coil, a notch portion formed in the first connecting portion and provided with a sample holding portion for holding a sample containing a metal impurity, and the notch portion described above. It is provided with a measuring unit for measuring an induced voltage or an induced current generated in the detection coil.

With such a configuration, when a sample holding part for holding a sample containing metal impurities is installed in the notch, the induced voltage induced in the detection coil changes, and the measuring part appropriately changes the change. It is possible to measure. Here, the first exciting coil and the second exciting coil are each wound around a core material and are not hollow coils. Therefore, the leakage of the magnetic flux in each exciting coil is small, and the magnetic flux density is large even in the notch. Therefore, even if the concentration of metal impurities contained in the sample is low, the change in electromagnetic induction in the detection coil when the sample holding portion is inserted into the notch portion is relatively remarkable. That is, it is possible to measure the change in the dielectric voltage according to the concentration of metal impurities in the sample with high sensitivity. It is also possible to measure the change in the induced current according to the concentration of metal impurities in the sample with high sensitivity.

Further, in the above-mentioned metal impurity measuring device, based on the change in the measurement result by the measuring unit between the time when the sample is not installed in the notch and the case where the sample is installed in the notch. Further, an analysis processing unit for analyzing the degree of mixing of metal impurities in the sample may be further provided.
For example, when the sample is a lubricating oil for a machine, the wear state of the mechanical part of the machine can be determined by analyzing the degree of mixing of metal impurities in the sample. Therefore, based on the analysis result, it is possible to determine the necessity of maintenance such as inspection (replacement) of mechanical parts and replacement of lubricating oil, and to predict the timing of maintenance.

Further, in the above-mentioned metal impurity measuring device, the detection coil may be adjusted so that an induced voltage is not generated when the sample is not installed in the cutout portion. That is, in a state where the sample is not installed in the notch portion, the magnetic fields generated by the first exciting coil and the second exciting coil may cancel each other out and the magnetism may be balanced.
In this case, since the sample containing metal impurities is placed in the notch, the above magnetic balance is lost, and the measuring unit measures the induced voltage or induced current according to the concentration of metal impurities in the sample. Become. Therefore, the metal impurity concentration of the sample can be easily analyzed by directly converting the measurement result by the measuring unit when the sample is installed in the notch portion. Further, since the voltage change from the state where the induced voltage generated in the detection coil is zero can be measured, easy and inexpensive measurement becomes possible.

Furthermore, in the above-mentioned metal impurity measuring device, the high-frequency power source may be a constant current AC power source. In this case, even if the winding resistance changes due to a change in the ambient temperature or the heat generated by the coil itself, the fluctuation of the magnetic field is suppressed by the constant current control, and the accuracy of the measurement result by the measuring unit can be improved. ..
Further, in the above-mentioned metal impurity measuring device, the notch portion may be configured such that a sample holder for accommodating the sample can be installed as the sample holding portion. In this way, when the sample holder is used as the sample holder, it is transferred to another bottle or the like when the sample is sent to a different analysis base for more precise measurement after the measurement by the metal impurity measuring device. The sample holder can be transferred as it is without any problem.
Further, in the above-mentioned metal impurity measuring device, the notch portion may be configured as the sample holding portion so that a tube through which the liquid sample passes can be set. As described above, when the tube is used as the sample holding portion, when the sample is a fluid, the metal impurity concentration can be continuously measured.

Further, in the metal impurity measuring device, the first exciting part, the second exciting part, the detecting part, the first connecting part, the second connecting part, the notch part, and the cutout part. A magnetic shield member made of a magnetic material that surrounds the sample holding portion that holds the sample installed in the notch portion may be further provided. In this case, the magnetic shield member can prevent the influence of disturbance noise.
Further, in the above-mentioned metal impurity measuring device, a second notch portion formed in the second connecting portion and having the same shape as the notch portion may be further provided. In this case, it becomes easy to balance the magnetism of the first exciting coil and the second exciting coil.

Further, one aspect of the metal impurity measuring method according to the present invention is formed by winding a first exciting coil around a core material to form a first exciting portion and winding a second exciting coil around a core material. A detection portion formed by winding a detection coil around a core material is arranged between the second exciting portion, and both ends of the core material of the first exciting portion and the core material of the detection portion. Are connected to each other by the first connecting portion, both ends of the core material of the second exciting portion and the core material of the detecting portion are connected to each other by the second connecting portion, and by the first exciting coil. The first exciting coil and the second exciting coil are connected to a high frequency power source so that the direction of the generated magnetic field and the direction of the magnetic field generated by the second exciting coil are opposite to each other. When a sample holding portion for holding a sample containing a metal impurity is installed in the notch formed in the connecting portion of the above, the induced voltage or induced current generated in the detection coil is measured, and the measured induction is performed. The degree of mixing of metal impurities in the sample is analyzed based on the voltage or the induced current.
This makes it possible to measure the change in the dielectric voltage according to the concentration of metal impurities contained in the sample with high sensitivity.

The metal impurity measuring device of the present invention can measure metal impurities contained in a sample with high sensitivity and accuracy.

It is a schematic block diagram of the metal impurity measuring apparatus in this embodiment. It is a figure which shows the insertion example of an oil sample. FIG. 2 is a cross-sectional view taken along the line AA of FIG. This is another configuration example of the metal impurity measuring device. It is a schematic block diagram of the metal impurity measuring apparatus of a comparative example. It is a figure which shows the measurement result in the metal impurity measuring apparatus of the comparative example. It is a figure which shows the measurement result in the metal impurity measuring apparatus in this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First Embodiment)
FIG. 1 is a schematic configuration diagram of the metal impurity measuring device 10 according to the present embodiment.
The metal impurity measuring device 10 is a device for measuring metal impurities contained in a sample. In the present embodiment, the metal impurity measuring device 10 is a metal of the lubricating oil (engine oil, gear oil, etc.) used in the large machine at the site where the large machine (construction machine, mining machine, etc.) is used. A case where the device measures impurities will be described. Here, the measurement of metal impurities in lubricating oil means measuring the degree of mixing of nanoparticles (metal impurities) in the lubricating oil.

The metal impurity measuring device 10 includes a housing 11. The housing 11 includes a sample holder accommodating portion 11a in which a sample holder 20 accommodating a part of the lubricating oil as an oil sample (sample containing metal impurities) 23 to be measured can be installed.
Here, the sample holder 20 has a bottom portion, for example, a cylindrical main body portion 21, and a lid portion 22 configured to be removable from the opening of the main body portion 21. The main body 21 is made of a non-metal material such as a resin instead of a magnetic material. Further, the material constituting the lid portion 22 may be the same as or different from that of the main body portion 21.

The oil sample (hereinafter, also simply referred to as “sample”) 23 collected from a large machine is inserted into the accommodation space inside the main body 21 through the opening of the main body 21 of the sample holder 20, and is sealed by the lid 22. Will be done. The diameter of the lid portion 22 is larger than the diameter of the main body portion 21, and when the lid portion 22 is attached to the main body portion 21, the peripheral portion of the lid portion 22 becomes the flange portion of the sample holder 20.
The sample holder accommodating portion 11a is formed of a hole corresponding to the shape of the main body 21 of the sample holder 20, and the main body 21 of the sample holder 20 is a sample from the holder insertion hole 11b formed on the upper surface of the housing 11. It is inserted into the holder accommodating portion 11a and accommodated. Here, the holder insertion hole portion 11b is formed to be smaller than the flange portion (lid portion 22) of the sample holder 20. Therefore, when the sample holder 20 is inserted into the sample holder accommodating portion 11a, the sample holder 20 is positioned at a predetermined position by the flange portion and the upper surface of the housing 11. This predetermined position is a position where at least a part of the main body 21 of the sample holder 20 is arranged between the notches 125 of the core material described later.

An element unit 12 and a circuit unit 13 are provided inside the housing 11.
The element portion 12 has a first exciting portion formed by winding a first exciting coil 121b around a core material 121a and a second exciting portion formed by winding a second exciting coil 122b around a core material 122a. A portion and a detection portion formed by winding a detection coil 123b around a core material 123a are provided. Further, the element unit 12 detects the first connecting portion 124a that connects both ends of the core material 121a of the first exciting portion and the core material 123a of the detecting portion to each other, and the core material 122a of the second exciting portion. A second connecting portion 124b for connecting both ends of the portion to the core material 123a to each other is provided.
The core materials 121a, 122a and 123a, and the connecting portions 124a and 124b are all made of a magnetic material. As the material of the core materials 121a, 122a and 123a, and the connecting portions 124a and 124b, for example, ferrite can be used.

As described above, in the present embodiment, a core material having a figure eight shape such as an EI core shape or an EE core shape is used. Then, the first exciting coil 121b is wound around one end side of the figure eight core, the second excitation coil 122b is wound around the other end side of the figure eight core, and the detection is performed at the center of the figure eight core. The coil 123b is wound around.
A notch 125 is provided in a part of the figure eight core. In the present embodiment, the case where the cutout portion 125 is formed in the first connecting portion 124a that connects the core material 121a of the first exciting portion and the core material 123a of the detecting portion will be described. The cutout portion 125 in the present embodiment is a hole in which the main body portion 21 of the sample holder 20 is installed, and has a gap having at least the same size (for example, several tens of mm) as the main body portion 21 of the sample holder 20. Have. That is, it is different from the core gap generally provided in the core material for suppressing magnetic saturation. The size of the notch portion 125 is preferably the size that the sample holder 20 can be inserted into.

The circuit unit 13 includes a high frequency power supply (PS) 131, an adjustment circuit 132, and a measurement unit (M) 133.
The high frequency power supply 131 is connected to the exciting coils 121b and 122b, respectively. Here, the exciting coils 121b and 122b and the high-frequency power supply 131 are arranged so that the directions of the magnetic fields generated in the first exciting coil 121b and the directions of the magnetic fields generated in the second exciting coil 122b are opposite to each other. It is connected.

The adjusting circuit 132 adjusts the detection coil 123b so that an induced voltage is not generated when the sample 23 is not installed in the cutout portion 125. Specifically, the adjustment circuit 132 adjusts the detection coil 123b so that an induced voltage is not generated in a state where an empty sample holder 20 in which the sample 23 is not housed is installed in the cutout portion 125.
When the sample 23 is not installed in the notch 125 due to the setting of the circuit parameters of the exciting coils 121b and 122b and the high frequency power supply 131 (the number of turns of the exciting coils 121b and 122b, the high frequency frequency, etc.), the detection coil It is preferable to adjust to some extent so that the induced voltage is not generated at 123b. In this case, the adjustment by the adjustment circuit 132 becomes easy. Further, if it is possible to adjust the detection coil 123b so that the induced voltage is not generated when the sample 23 is not installed in the cutout portion 125 by setting the circuit parameters, the adjustment by the adjusting circuit 132 is unnecessary. ..

The measuring unit 133 measures the induced voltage or induced current generated in the detection coil 123b, and outputs the measurement result to the external device 30. In this embodiment, the case where the measuring unit 133 is an AC voltmeter will be described.
The external device 30 includes an analysis processing unit that analyzes the degree of mixing of metal impurities in the sample 23 based on the measurement result output from the measurement unit 133. The external device 30 can be configured by, for example, a portable tablet terminal, a cloud computer, or the like.
One of the causes of impairing the lubricating performance of the lubricating oil is the mixing of impurities such as metal particles into the lubricating oil. The degree of mixing of metal impurities in this lubricating oil increases as the mechanical parts of large machines wear out. Therefore, the external device 30 analyzes the degree of mixing of metal impurities in the sample 23 to analyze how much the wear has progressed, and whether maintenance such as inspection or replacement of mechanical parts is necessary and necessary in the future. Predict the maintenance time.

When a part of the main body 21 of the sample holder 20 that holds the sample 23 is arranged in the notch 125, the balance of the combined magnetic field by the exciting coils 121b and 122b is lost, and an electromagnetic induction phenomenon occurs in the detection coil 123b. To do. That is, the induced voltage is induced by the detection coil 123b. Then, at this time, the above-mentioned induced voltage is measured by the measuring unit 133, which is an AC voltmeter.
The induced voltage measured by the measuring unit 133 corresponds to the fluctuation of the magnetic balance according to the concentration of metal impurities (concentration of magnetic powder) contained in the sample 23. Therefore, by converting the amount of change in the measurement result by the measuring unit 133 between when the sample 23 is not installed in the notch 125 and when the sample 23 is installed in the notch 125, the sample 23 is obtained. The concentration of metal impurities contained is required.

Here, in the present embodiment, the detection coil 123b is adjusted so that the induced voltage is not generated when the sample 23 is not installed in the cutout portion 125. Therefore, the metal impurity concentration can be easily obtained by directly converting the induced voltage measured by the measuring unit 133 when the sample 23 is installed in the notch portion 123. In this way, since the voltage change from the state where the induced voltage generated by the detection coil 123b is zero can be measured, the detection system can be simplified and inexpensive measurement becomes possible.

In the metal impurity measuring device 10 of the present embodiment, the exciting coils 121b and 122b and the detection coil 123b are not hollow coils but have a core material penetrating inside. Further, the core material has a closed structure except for the cutout portion 125 in which the sample holder 20 is installed. Therefore, the leakage of the magnetic flux in each coil is small, and the magnetic flux density is large even in the notch portion 125.
Therefore, even if the concentration of metal impurities contained in the sample 23 in the sample holder 20 inserted into the cutout portion 125 is low, the generation of electromagnetic induction in the detection coil 123b due to the fluctuation of the magnetic balance becomes relatively remarkable. That is, a relatively high dielectric voltage can be obtained even if the metal impurity concentration of the sample 23 is low. In this way, the influence of fluctuations in the surrounding environment such as temperature fluctuations can be reduced, and the metal impurity concentration can be measured with high accuracy.

Here, the high-frequency power source 131 described above may be an AC voltage source or an AC current source, but is particularly preferably a constant current AC power source. Even if the winding resistance changes due to the above-mentioned change in the environmental temperature or the heat generated by the coil itself, in the case of a constant current AC power supply, constant current control is performed, and as a result, fluctuations in the magnetic field are suppressed, and the detection coil 123b The accuracy of the measurement result of is improved.

Further, it is preferable that the element portion 12 arranged in the housing 11 and the periphery of the sample holder 20 inserted into the notch portion 125 (around the sample holder accommodating portion 11a) are surrounded by a magnetic shield member. .. This magnetic shield member can prevent the influence of disturbance noise. As the material of the magnetic shield member, for example, iron, permalloy tape, or the like can be used. The housing 11 may be made of a magnetic shield member.
With such a configuration, the shape and magnetic flux density of the magnetic field generated by the element unit 12 are suppressed from fluctuating due to the influence of the surrounding members, and the measurement result of the detection coil 123b is stable.

Further, in the present embodiment, the case where the sample holder 20 containing the sample 23 is inserted into the cutout portion 125 from above FIG. 1 (from the direction perpendicular to the upper surface of the housing 11) has been described. The insertion direction of the sample holder 20 is not limited to the above. For example, the sample holder 20 may be inserted into the cutout portion 125 from a direction perpendicular to the side surface of the housing 11.

Further, in the present embodiment, the case where the sample holder 20 containing the sample 23 is installed in the cutout portion 125 has been described, but a tube through which the liquid sample 23 flows may be installed. FIG. 2 is a view when the tube 24 through which the liquid sample 23 flows is installed with respect to the cutout portion 125 from the direction perpendicular to the side surface of the housing 11, and FIG. 3 is a view taken along the line AA in FIG. It is a sectional view. With this configuration, when the sample 23 is a fluid, the metal impurity concentration can be continuously measured.
When the sample holder 20 is used as in the above embodiment, the measurement in the metal impurity measuring device 10 is the primary measurement, and when the sample 23 is sent to a different analysis base for more precise measurement, the sample 23 is sent. There is an effect that the sample holder 20 can be transferred as it is without being transferred to another bottle or the like. In this case, the time and effort required to transfer the sample 23 to a transfer bottle or the like can be reduced, and undesired contamination of impurities at the time of transfer can be avoided.

Further, in the present embodiment, the case where the cutout portion 125 is formed in the first connecting portion 124a has been described, but as shown in FIG. 4, the second connecting portion 124b is also cut in the same manner as the cutout portion 125. The notch 126 may be formed. In this case, the magnetic balance of the combined magnetic field by the exciting coils 121b and 122b becomes easy, and the adjustment by the adjusting circuit 132 becomes easy. Although the sample 23 is not installed in the cutout portion 126, an empty sample holder 20 that does not contain the sample 23 may be installed.

(Example)
Hereinafter, examples carried out for confirming the effects of the present invention will be described.
The inventors measured the metal impurity concentration in the sample 23 by using the metal impurity measuring device 10 in the above embodiment and the metal impurity measuring device as a comparative example.
Here, as the metal impurity measuring device as a comparative example, the metal impurity measuring device 100 shown in FIG. 5 was used.
The metal impurity measuring device 100 has a configuration in which a pair of equivalent exciting coils L1 and L2 connected in series in a housing 101 are arranged on a vertical common axis P. The exciting coils L1 and L2 are connected to the power supply device PS so that the magnetic fields face each other. Further, the detection coil L3 is arranged at a position on the common shaft core P where the combined magnetic field of the pair of exciting coils L1 and L2 becomes zero. An iron core FC is screwed into the detection coil L3. An exciting current of several tens of kHz is supplied to the exciting coils L1 and L2 from the power supply device PS.

Here, when the sample holder 20 holding the sample 23 is inserted into the exciting coil L1, the balance of the combined magnetic field by the pair of exciting coils L1 and L2 is lost, and an induced voltage is induced in the detection coil L3. This induced voltage is measured by the measuring unit M, which is an AC voltmeter. Since this induced voltage corresponds to the fluctuation of the magnetic balance due to the change in the magnetic permeability inside the exciting coil L1 according to the concentration of metal impurities contained in the sample 23, the metal contained in the sample 23 can be converted by converting the induced voltage. Impurity concentration is required.

FIG. 6 shows the measurement results of the metal impurity measuring device 100 shown in FIG.
The samples to be measured are an iron powder-added sample obtained by mixing iron powder with diesel engine oil (CD-30 manufactured by Pulseter) and an oil sample containing metal impurities (nanoparticles) collected from a construction machine. (Sample 23) and was used. Then, the iron powder concentration of each sample was obtained in advance, and the relationship between the iron powder concentration and the induced voltage value generated in the detection coil was investigated. The iron powder concentration in the oil sample was determined by inductively coupled plasma mass spectrometry (ICP-MS). Further, a high frequency voltage of 1 kHz and 0.5 V was applied to the exciting coils L1 and L2 by the power supply device PS.

Here, the horizontal axis of FIG. 6 is the iron powder concentration [ppm] in the sample, and the vertical axis is the induced voltage (voltage [mV]) generated by the detection coil L3. The plot shown by the white square in FIG. 6 is the measurement result obtained by the measuring unit M detecting the induced voltage generated in the detection coil L3 when the iron powder-added sample is used, and the plot shown by the black diamond is the oil sample. This is a measurement result obtained by detecting the induced voltage generated in the detection coil L3 when (Sample 23) is used by the measuring unit M.

As is clear from FIG. 6, in the iron powder-added sample, the relationship between the iron powder concentration and the measured voltage is almost linear in the iron powder concentration range of 100 ppm to 2800 ppm. However, for oil samples collected from construction machinery, no linearity could be confirmed between the iron powder concentration and the measured voltage. It is probable that the linearity could not be confirmed in the oil sample because metal impurities (magnetic materials) other than iron powder were mixed in the oil sample.

Furthermore, it can be seen that the relationship between the iron powder concentration and the measured voltage fluctuates remarkably, especially when the iron powder concentration is 300 ppm or less. This is because in the metal impurity measuring device 100 of FIG. 5, since each coil is an air-core coil, when the magnetic flux density in the coil is small and the iron powder concentration is small, the magnetism of the combined magnetic field by the pair of exciting coils L1 and L2 It is considered that the balance fluctuation is greatly affected by the ambient environmental conditions such as the ambient temperature. This effect is considered to be larger than the effect of mixing metal impurities (magnetic materials) other than iron powder. Therefore, in the region where the value of the induced voltage generated by the detection coil L3 is 300 ppm or less in the iron powder concentration, It seems that the value of the induced voltage fluctuates greatly.

FIG. 7 shows the measurement results of the metal impurity measuring device 10 in the above embodiment.
As the sample to be measured, an iron powder-added sample and an oil sample (sample 23) similar to those of the metal impurity measuring device 100 described above were used. Then, the iron powder concentration of each sample was obtained in advance, and the relationship between the iron powder concentration and the induced voltage value generated in the detection coil was investigated. Here, a high frequency voltage of 1 kHz and 0.5 V was applied to the exciting coils 121b and 122b from the high frequency power supply 131.

The purpose of the measurement with the metal impurity measuring device 10 was to confirm whether or not it is possible to measure the iron powder concentration of 100 ppm or less with a certain degree of accuracy.
The horizontal axis of FIG. 7 is the iron powder concentration [ppm] in the sample, and the vertical axis is the measurement result (voltage [mV]) of the induced voltage generated by the detection coil 123b detected by the measuring unit 133. Since the value of the induced voltage becomes small in the measurement of the concentration of 100 ppm or less, the induced voltage generated in the detection coil 123b is amplified by a well-known amplification means and then detected by the measuring unit 133. Therefore, the vertical axis of FIG. 6 and the vertical axis of FIG. 7 do not correspond to each other.

As is clear from FIG. 7, in the iron powder-added sample, the relationship between the iron powder concentration and the measured voltage is almost linear even at a low concentration of 100 ppm or less. In addition, the oil sample collected from the construction machine does not show the clear linearity of the iron powder-added sample, but shows relatively good linearity. That is, it was confirmed that the metal impurity measuring device 10 can accurately measure metal impurities even in a low concentration region of iron powder concentration of 100 ppm or less.

In FIG. 7, the induced voltage when the iron powder concentration of the oil sample is 0 ppm is not 0 mV because metal impurities (magnetic materials) other than iron powder are mixed in the oil sample. Be done.
Further, using the metal impurity measuring device 100 of the comparative example, the induced voltage was amplified by the amplification means and detected by the measuring unit M in the low concentration region of the iron powder concentration of 100 ppm or less in the case of the oil sample. It was impossible to measure because of the noise. That is, it was not possible to discriminate the signal corresponding to the target induced voltage.

As described above, it was confirmed that the metal impurity measuring device 10 in the present embodiment can accurately measure the metal impurity concentration even when the metal impurity concentration mixed in the sample 23 is as small as 100 ppm or less. ..
In recent years, in response to a demand for higher performance of an engine, for example, the lubricating oil is replaced when the metal impurity concentration is about 70 ppm. As described above, since it is possible to accurately measure low-concentration metal impurities of 100 ppm or less, it is possible to appropriately cope with the improvement of engine performance.

(Modification example)
In the above embodiment, the case where the detection coil 123b is adjusted so that the induced voltage is not generated when the sample 23 is not installed in the cutout portion 125 has been described. However, it suffices if the amount of change in electromagnetic induction generated in the detection coil 123b can be detected when the sample 23 is installed in the notch 125 from the state in which the sample 23 is not installed in the notch 125. It is not always necessary to adjust the detection coil 123b so that the induced voltage is not generated when the sample 23 is not installed in the cutout portion 125.

Further, in the above embodiment, the case where the metal impurity measuring device 10 measures the lubricating oil of a large machine has been described, but the measurement target is not limited to the lubricating oil, and may be seawater, for example. Seawater may contain sulfur, cadmium, mercury and the like. Therefore, the metal impurity measuring device 10 may be configured as a seawater measuring device to measure metal impurities in seawater.

10 ... Metal impurity measuring device, 11 ... Housing, 12 ... Element part, 13 ... Circuit part, 20 ... Sample holder, 23 ... Oil sample (sample containing metal impurities), 30 ... External device, 121a ... Core material, 121b ... First exciting coil, 122a ... core material, 122b ... second exciting coil, 123a ... core material, 123b ... detection coil, 124a ... first connecting part, 124b ... second connecting part, 131 ... high frequency power supply, 132 ... Adjustment circuit, 133 ... Measurement unit

Claims (9)

A first exciting part formed by winding a first exciting coil around a core material, and
A second exciting part formed by winding a second exciting coil around the core material, and
A detection unit formed by winding a detection coil around a core material and located between the first exciting part and the second exciting part,
A first connecting portion that connects both ends of the core material of the first exciting portion and the core material of the detecting portion to each other, and
A second connecting portion that connects both ends of the core material of the second exciting portion and the core material of the detecting portion to each other, and
Connected to the first exciting coil and the second exciting coil so that the direction of the magnetic field generated by the first exciting coil and the direction of the magnetic field generated by the second exciting coil are opposite to each other. High frequency power supply and
A notch formed in the first connecting portion and provided with a sample holding portion for holding a sample containing metal impurities, and a notch portion.
A metal impurity measuring device including a measuring unit for measuring an induced voltage or an induced current generated in the detection coil. The degree of mixing of metal impurities in the sample is based on the change in the measurement result by the measuring unit between when the sample is not installed in the notch and when the sample is installed in the notch. The metal impurity measuring apparatus according to claim 1, further comprising an analysis processing unit for analyzing the above. The metal impurity measuring apparatus according to claim 1 or 2, wherein the detection coil is adjusted so that an induced voltage is not generated when the sample is not installed in the cutout portion. The metal impurity measuring device according to any one of claims 1 to 3, wherein the high-frequency power source is a constant current AC power source. The metal impurity measuring apparatus according to any one of claims 1 to 4, wherein the cutout portion is configured such that a sample holder for accommodating the sample can be installed as the sample holding portion. The metal impurity measurement according to any one of claims 1 to 4, wherein the notch portion is configured such that a tube through which the liquid sample passes can be set as the sample holding portion. apparatus. Holds the first exciting part, the second exciting part, the detecting part, the first connecting part, the second connecting part, the notch part, and the sample installed in the notch part. The metal impurity measuring apparatus according to any one of claims 1 to 6, further comprising a magnetic shield member made of a magnetic material that surrounds the sample holding portion. The metal impurity measuring apparatus according to any one of claims 1 to 7, further comprising a second notch portion formed in the second connecting portion and having the same shape as the notch portion. .. In the core material, between the first exciting part formed by winding the first exciting coil around the core material and the second exciting part formed by winding the second exciting coil around the core material. A detection unit formed by winding the detection coil is arranged, and both ends of the core material of the first excitation unit and the core material of the detection unit are connected to each other by the first connecting portion, respectively, and the second Both ends of the core material of the exciting part and the core material of the detection part are connected to each other by a second connecting part, respectively.
The first exciting coil and the second exciting coil are used as a high-frequency power source so that the direction of the magnetic field generated by the first exciting coil and the direction of the magnetic field generated by the second exciting coil are opposite to each other. Connect to
When a sample holding portion for holding a sample containing metal impurities is installed in the notch formed in the first connecting portion, the induced voltage or induced current generated in the detection coil is measured.
A method for measuring metal impurities, which comprises analyzing the degree of mixing of metal impurities in the sample based on the measured induced voltage or the induced current.

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