An oil detection sensor based on LC passive wireless sensing and its manufacturing method

Abstract

The invention discloses an oil detection sensor based on LC passive wireless sensing and a manufacturing method thereof, belonging to the technical field of oil detection of mechanical equipment, comprising: an internal induction coil placed inside an oil pipeline to be tested, sensing metal abrasive particles in the oil pipeline to be tested and generating impedance changes; a capacitor connected in series with the internal induction coil to form an LC resonance unit; an external readout coil for collecting impedance value changes of the internal induction coil, and an oil pipeline in which the internal induction coil is placed; the oil pipeline comprises a port I and a port II; the port I and the port II are respectively connected to the oil pipeline to be tested, and the LC passive wireless sensing technology is applied to the field of oil detection. Compared with a traditional inductive sensor, the invention improves the detection sensitivity of the oil detection sensor without destroying the original complete structure of the pipeline, and realizes wireless detection of metal abrasive particles in the oil pipeline.

Description

Technical Field

[0001] The present invention relates to the technical field of oil detection of mechanical equipment, and in particular to an oil detection sensor based on LC passive wireless sensing and a manufacturing method thereof. Background Art

[0002] Hydraulic systems are widely used in marine vessels, aircraft, wind power generation and other mechanical devices. In order to avoid failure of hydraulic equipment and ensure the normal operation of hydraulic equipment, it is necessary to monitor the operating status of the equipment. Since the oil contains rich information about the aging and wear of moving parts, analyzing the oil of mechanical equipment has become an important means of fault warning and life diagnosis of mechanical equipment. According to research, when the hydraulic equipment is in normal operation, the concentration of wear particles in the oil is constant at a low level and the particle size is usually 10 to 20 microns. When the hydraulic equipment is abnormally worn, the concentration of abrasive particles in the oil will increase significantly, and the particle size will increase to more than 100 microns, which will affect the accuracy and stability of the hydraulic system. In severe cases, it will cause the shutdown of mechanical equipment. Therefore, detecting the information of wear particles in the oil plays an important role in maintaining the healthy operation of the hydraulic system.

[0003] There are usually two ways to detect oil in traditional mechanical equipment. One is to place the inductor coil outside the oil pipeline. Due to the influence of the wall thickness of the oil pipeline, the inductor coil is far away from the wear particles passing through, which reduces the sensitivity of the sensor. The second is to place the inductor coil inside the oil pipeline, so that the inductor coil is closer to the wear particles passing through, and the sensor detection sensitivity is higher. However, since the inductor coil inside the oil pipeline needs to be connected to the signal detection unit outside the pipeline through a wire, this will destroy the integrity of the oil pipeline. When the oil pressure is high, it will cause stress concentration at the wire connection, which may cause oil leakage in the long run. Summary of the invention

[0004] The present invention provides an oil detection sensor based on LC passive wireless sensing, comprising:

[0005] An internal induction coil placed inside the tested oil pipeline, sensing the metal abrasive particles in the tested oil pipeline and generating impedance changes;

[0006] A capacitor connected in series with the internal induction coil to form an LC resonance unit;

[0007] An external readout coil collects changes in impedance value of the internal induction coil.

[0008] Further, it includes an oil pipeline in which the internal induction coil is placed;

[0009] The oil pipeline comprises a port I and a port II; the port I and the port II are respectively connected to the oil pipeline to be tested.

[0010] Further: it includes an excitation and detection unit for giving excitation to the external readout coil and reading the change of the signal of the external readout coil.

[0011] Furthermore: the internal induction coil is a coil wound with multiple turns of double-strand wires.

[0012] Furthermore: the centers of the external readout coil, the internal induction coil and the oil pipeline are on the same axis.

[0013] Furthermore: the oil pipeline is made of high magnetic permeability metal material.

[0014] Further: the excitation frequency applied to the external readout coil is slightly greater than the resonant frequency of the LC resonant unit, and the calculation formula of the resonant frequency f is as follows:

[0015]

[0016] L and C are the inductance of the internal induction coil and the capacitance of the series capacitor respectively.

[0017] A method for manufacturing an oil detection sensor based on LC passive wireless sensing comprises the following steps:

[0018] S1: First, use a vernier caliper to measure the size parameters of the selected external readout coil and internal induction coil;

[0019] S2: Making a fixture for the external readout coil and the internal induction coil through 3D modeling and 3D printing, and then placing the external readout coil and the internal induction coil into the fixture and fixing them;

[0020] S3: Use a capacitor in series with the internal induction coil and weld them to form an LC resonance unit;

[0021] S4: Put an oil pipeline of a certain thickness into the fixture, so that the oil pipeline is placed between the external readout coil and the internal induction coil, and the external readout coil is close to the outer wall of the oil pipeline, and the internal induction coil and the capacitor are close to the inner wall of the oil pipeline, and the inner wall of the oil pipeline serves as a flow channel for the oil to pass through;

[0022] S5: Adjust the positions of the internal induction coil, the external readout coil and the oil pipeline so that their centers are aligned;

[0023] S6: Connect the external readout coil to the excitation and detection unit.

[0024] The present invention provides an oil detection sensor based on LC passive wireless sensing and a manufacturing method thereof, which applies LC passive wireless sensing technology to the field of oil detection. Compared with traditional inductive sensors, the present invention improves the detection sensitivity of the oil detection sensor without destroying the original complete structure of the pipeline, realizes wireless detection of metal abrasive particles in the oil pipeline, and provides technical support for online detection of metal abrasive particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 Design diagram for LC passive wireless sensor;

[0027] Figure 2 This is the LC passive wireless structure diagram;

[0028] Figure 3 The signal-to-noise ratio of 40 μm iron particles is shown in Figure 2.

[0029] Figure 4 The signal-to-noise ratio of 110 μm copper particles.

[0030] In the figure: 1. Port I, 2. Internal induction coil, 3. External readout coil, 4. Excitation and detection unit, 5. Capacitor, 6. Oil pipeline, 7. Port II, 8. Metal abrasive particles. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0033] Figure 1 Design diagram of LC passive wireless sensor; An oil detection sensor based on LC passive wireless sensing, comprising: an internal induction coil 2, an external readout coil 3 and a capacitor 5;

[0034] The internal induction coil 2 is placed inside the oil pipeline to be tested, sensing the metal abrasive particles 8 in the oil pipeline to be tested and generating impedance changes; the metal abrasive particles 8 are pollutants; the internal induction coil 2 is placed close to the inner wall of the oil pipeline 6,

[0035] The sensor may also include an oil pipeline 6 in which the internal induction coil 2 is placed;

[0036] The capacitor 5 is connected in series with the internal induction coil 2 to form an LC resonance unit; the capacitor 5 is a 0805, 0603 or 0402 chip;

[0037] The external readout coil 3 collects the change of the impedance value of the internal induction coil 2. The external readout coil 3 is placed close to the outer wall of the oil pipeline 6 and has no electrical connection with the internal induction coil 2. Through the magnetic field coupling with the internal induction coil 2,

[0038] The change in impedance value can determine the nature and size of the metal abrasive particles; the nature of the metal abrasive particles can be iron, copper, etc.

[0039] Since the magnetization effect of iron particles is dominant and copper particles are affected by the eddy current effect, the signals of the two are in opposite directions.

[0040] The oil pipeline 6 includes port I1 and port II7; port I1 and port II7 are respectively an oil inlet and an oil outlet, the oil inlet is the entrance for the oil to enter the sensor, and the oil outlet is the outlet for the oil after passing through the sensor; the tested oil sample enters the detection area of ​​the sensor through the oil inlet and is discharged from the sensor through the oil outlet.

[0041] The port I1 and the port II7 are respectively connected to the oil pipeline to be tested.

[0042] The sensor further comprises an excitation and detection unit 4 for giving excitation to the external readout coil 3 and reading the signal change of the external readout coil 3 .

[0043] The internal induction coil 2 is a coil wound with multiple turns of bifilar wire and connected to a chip capacitor of a certain specification to form an LC resonant circuit;

[0044] The external readout coil 3 is a multi-turn solenoid coil and is connected to an external excitation and detection unit 4; an existing software, such as LabVIEW software, is installed on the computer of the excitation and detection unit 4; LabVIEW is a data acquisition and instrument control software that can control our excitation and detection unit to apply excitation to the external readout coil and collect its signal changes.

[0045] There is no electrical connection between the external readout coil 3 and the internal induction coil 2. The signal change of the external readout coil is detected by the excitation and detection unit 4, thereby realizing wireless detection of pollutants passing through the oil pipeline.

[0046] The excitation and detection unit 4 uses the resonant frequency of the internal induction coil and capacitor as the excitation frequency to apply excitation to the external readout coil. Excitation is to give the external coil an alternating current so that it can generate an alternating magnetic field and work normally. This alternating current must have a certain frequency requirement, because the internal coil 2 and capacitor 5 form a resonant unit. The following formula can calculate their resonant frequency. When it is near this frequency, its detection effect will be better. The excitation frequency we apply to the external coil 3 is slightly greater than the resonant frequency f;

[0047]

[0048] Wherein: L and C are the inductance of the internal induction coil and the capacitance of the series capacitor respectively; the excitation frequency is related to the direction of the iron particles and the copper particles; when the excitation frequency is less than the resonant frequency, the iron particle signal is upward and the copper signal is downward. When the excitation frequency is greater than the resonant frequency, the iron signal is downward and the copper signal is upward. Because when the excitation frequency is within a relatively close range to the resonant frequency, the detection sensitivity of the sensor is the highest. In addition, the excitation frequency used in this embodiment is greater than the resonant frequency, so "slightly greater than" is used. Because the excitation frequency used in this embodiment is greater than the resonant frequency, the generated iron particle signal is downward and the copper particle signal is upward.

[0049] The centers of the external readout coil 3 , the internal induction coil 2 and the oil pipeline 6 are on the same axis.

[0050] The oil pipeline 6 is made of a high magnetic permeability metal material, which is equivalent to a magnetic core, thereby increasing the magnetic field strength in the sensor detection area and improving the sensor detection sensitivity.

[0051] A method for manufacturing an oil detection sensor based on LC passive wireless sensing comprises the following steps:

[0052] S1: First, use a vernier caliper to measure the size parameters of the selected external readout coil 3 and internal induction coil 2;

[0053] S2: Making a fixture for the external readout coil 3 and the internal induction coil 2 by three-dimensional modeling and 3D printing, and then placing the external readout coil 3 and the internal induction coil 2 into the fixture and fixing them;

[0054] S3: Use capacitor 5 and internal induction coil 2 to be connected in series and welded to form an LC resonance unit; S4: Put a certain thickness of oil pipeline into the fixture, so that the oil pipeline 6 is placed between the external readout coil 3 and the internal induction coil 2, and the external readout coil 3 is close to the outer wall of the oil pipeline, the internal induction coil 2 and capacitor 5 are close to the inner wall of the oil pipeline 6, and the inner wall of the oil pipeline 6 serves as a flow channel for the oil; wherein: the thickness is the radius difference between the inner and outer coils, and the thickness used in the embodiment is 0.5mm;

[0055] S5: Adjust the positions of the internal induction coil 2, the external readout coil 3 and the oil pipeline 6 so that their centers are aligned;

[0056] S6 : Connect the external readout coil 3 to the excitation and detection unit 4 .

[0057] A double-strand coil with a wire diameter of 0.1 mm is set as the internal induction coil 2, which is placed close to the inner wall of the oil pipeline 6 to detect pollutants passing through the oil and generate impedance changes; a multi-turn coil with a wire diameter of 0.4 mm is set as the external readout coil 4, which is placed close to the outer wall of the oil pipeline to capture the impedance change of the internal induction coil through magnetic field coupling with the internal induction coil 2; an excitation and detection unit 3 is set to be connected to the external readout coil 4, and provides excitation to the external readout coil 4, and reads its signal changes at the same time; a capacitor 5 with a specification of 0402 is set to be placed on the inner wall of the oil pipeline 6, and is connected in series with the internal induction coil to form an LC resonance unit. In this embodiment, the resonance frequency of the resonance unit is 410 kHz, and the excitation frequency we apply is 420 kHz.

[0058] Figure 2 This is the LC passive wireless structure diagram; combined Figure 2 To further illustrate the invented sensor in an embodiment, metal particles 8 enter the sensor through the oil inlet of the sensor; when the metal particles pass through the internal induction coil 2, the inductance of the internal induction coil 2 will be changed due to the magnetization effect and eddy current effect, thereby changing the impedance of the internal induction coil 2. Due to the magnetic field coupling between the external readout coil 3 and the internal induction coil 2, the impedance change of the internal induction coil 2 will be captured by the external readout coil 3, and its signal change will be transmitted to the excitation and detection unit 4, completing the detection of metal abrasive particles in the oil.

[0059] By using the sensor of the present invention and giving high-frequency alternating current excitation to the external readout coil 3 through the excitation and detection unit 4, it is possible to detect 60-micron iron particles and 130-micron copper particles. The sensitivity of the sensor is tested using the resonant frequency of the LC resonant unit as the excitation frequency, and 40-micron iron particles and 110-micron copper particles are tested respectively. It can be found that at this excitation frequency, the sensor still has a high signal-to-noise ratio for 40-micron iron particles and 110-micron copper particles; Figure 3 The signal-to-noise ratio of 40 μm iron particles is shown in Figure 2. Figure 4 The signal-to-noise ratio of 110 μm copper particles.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An oil detection sensor based on LC passive wireless sensing, characterized in that: include: An internal induction coil placed inside the oil pipeline and not electrically connected to the outside of the pipeline, sensing metal abrasive particles in the oil pipeline and generating impedance changes; a capacitor connected in series with the internal induction coil to form an LC resonance unit; an external readout coil placed outside the oil pipeline, wirelessly reading the impedance change of the internal induction coil; an excitation and detection unit that excites the external readout coil and reads the signal change of the external readout coil; The manufacturing method of the LC passive wireless sensing oil detection sensor comprises the following steps: S1: First, use a vernier caliper to measure the size parameters of the selected external readout coil and internal induction coil; S2: Making a fixture for the external readout coil and the internal induction coil through 3D modeling and 3D printing, and then placing the external readout coil and the internal induction coil into the fixture and fixing them; S3: Use a capacitor in series with the internal induction coil and weld them to form an LC resonance unit; S4: Put an oil pipeline of a certain thickness into the fixture, so that the oil pipeline is placed between the external readout coil and the internal induction coil, and the external readout coil is closely attached to the outer wall of the oil pipeline, and the internal induction coil and the capacitor are closely attached to the inner wall of the oil pipeline, and the inner wall of the oil pipeline serves as a flow channel for the oil to pass through; S5: Adjust the positions of the internal induction coil, the external readout coil and the oil pipeline so that their centers are aligned; S6: Connect the external readout coil to the excitation and detection unit.

2. The oil detection sensor based on LC passive wireless sensing according to claim 1 is characterized in that: including an oil pipeline in which an internal induction coil is placed; The oil pipeline comprises a port I and a port II; the port I and the port II are respectively connected to the oil pipeline to be tested.

3. The oil detection sensor based on LC passive wireless sensing according to claim 1 is characterized in that: The internal induction coil is a coil wound with multiple turns of bifilar wire.

4. The oil detection sensor based on LC passive wireless sensing according to claim 2 is characterized in that: The centers of the external sensing coil, the internal induction coil and the oil pipeline are on the same axis.

5. The oil detection sensor based on LC passive wireless sensing according to claim 2 is characterized in that: The oil pipeline is made of high magnetic permeability metal material.

6. The oil detection sensor based on LC passive wireless sensing according to claim 1, characterized in that: The excitation frequency applied to the external readout coil is slightly greater than the resonant frequency of the LC resonant unit. The calculation formula is as follows: L and C are the inductance of the internal induction coil and the capacitance of the series capacitor respectively.

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