A composite magnetic field sensor structure for lubricating oil particle detection, and methods of making and using the same

Abstract

The application belongs to the field of mechanical equipment state detection, and particularly relates to a composite magnetic field sensor structure for lubricating oil particle detection, and a manufacturing method and a using method thereof. The composite magnetic field sensor comprises a permanent magnet ring, an induction coil, a shell, an end cover, a terminal, a first excitation coil and a second excitation coil. The permanent magnet ring, the induction coil, the first excitation coil and the second excitation coil are arranged in the shell. The induction coil is arranged on the outer circumferential side surface of the permanent magnet ring. The gap region in the shell is filled with pouring sealant, and a cavity is arranged for lubricating oil flow. The end cover is provided with the terminal for supplying power to the excitation coil and outputting the signal collected by the induction coil. The shell is provided with two threaded holes on the left and right surfaces for connecting the oil pipe. The application can clearly detect the distribution of metal particles in the oil, especially the ferromagnetic and non-ferromagnetic particles, which makes the detection range larger and more accurate.

Description

Technical Field

[0001] This invention belongs to the field of mechanical equipment condition monitoring, and specifically relates to a composite magnetic field sensor structure for detecting abrasive particles in lubricating oil, its manufacturing method, and its usage method. Background Technology

[0002] During operation, mechanical equipment inevitably experiences wear due to friction between component surfaces. As operating time increases, the amount of wear also gradually increases. Excessive wear can lead to various adverse events in the equipment. Statistics show that wear failure accounts for nearly 80% of the failure modes of general mechanical parts. Therefore, understanding and monitoring the wear condition of machine parts is crucial. The addition of oil can significantly reduce friction. Moreover, as the oil flows through the mechanical system, it carries information about various abrasive particles generated by friction. By analyzing and detecting the characteristics such as the type, size, shape, and quantity of these abrasive particles, the wear condition of the equipment can be determined, facilitating healthy operation and maintenance management.

[0003] Currently, many types of abrasive particle detection sensors have been developed both domestically and internationally. They can be classified according to changes in the magnetic permeability, acousto-optic transmission characteristics, and dielectric constant of the lubricating oil. Among these, inductive sensors have become the mainstream method for abrasive particle detection. Electromagnetic sensors, on the other hand, have low response frequencies, making them unsuitable for rapid dynamic measurements. Furthermore, they struggle to distinguish and display aliased abrasive particle signals with different characteristics, and their structure is susceptible to interference from magnetic field disturbances, severely impacting the generation and final display of abrasive particle signals. Summary of the Invention

[0004] In summary, the purpose of this invention is to design a composite magnetic field sensor structure for detecting abrasive particles in lubricating oil, as well as its manufacturing and usage methods, to detect ferromagnetic and non-ferromagnetic particles in oil. This invention provides a composite magnetic field sensor structure, manufacturing method, and detection method for detecting abrasive particles in lubricating oil.

[0005] One aspect of the present invention provides a composite magnetic field sensor structure for detecting abrasive particles in lubricating oil, comprising: a housing, an end cap, a permanent magnet ring, an induction coil, a first excitation coil, a second excitation coil, and a connector;

[0006] The upper surface of the housing is provided with a first mounting groove, and the end cap is adapted to the upper surface of the first mounting groove;

[0007] The permanent magnet ring, induction coil, first excitation coil, and second excitation coil are disposed in the first mounting groove;

[0008] The end cap is provided with a first through hole that extends vertically. A connector is fixedly installed in the first through hole. The connector is electrically connected to the induction coil, the first excitation coil, and the second excitation coil through wires.

[0009] The left and right sides of the housing are respectively provided with a first threaded hole and a second threaded hole that communicate with the first mounting groove.

[0010] The first mounting groove is filled with potting compound to form a filling area; a second through hole is provided on the left side of the filling area;

[0011] The induction coil is fixedly arranged on the outer side of the circumference of the permanent magnet ring, and the outer diameter of the permanent magnet ring is adapted to the inner diameter of the induction coil.

[0012] The second through hole passes through the inner circumference of the first excitation coil, the induction coil, and the second excitation coil from left to right to form a cavity;

[0013] The second through hole corresponds to the first threaded hole and the second threaded hole on the left and right, respectively.

[0014] Preferably, the diameter of the second through hole is the same as the inner diameter of the first excitation coil, the permanent magnet ring, and the second excitation coil.

[0015] Preferably, the first mounting groove is a cylindrical groove or a square groove.

[0016] Preferably, the first threaded hole and the second threaded hole have the same diameter as the second through hole.

[0017] Preferably, the first excitation coil and the second excitation coil are distributed on the left and right sides of the permanent magnet ring and are symmetrical to each other.

[0018] Preferably, the first excitation coil and the second excitation coil are connected in series.

[0019] Preferably, the distance between the induction coil and the first excitation coil and the second excitation coil is 0~10mm.

[0020] Another aspect of the present invention provides a method for fabricating a composite magnetic field sensor structure for detecting abrasive particles in lubricating oil. The method, used to fabricate the aforementioned composite magnetic field sensor structure for detecting abrasive particles in lubricating oil, includes:

[0021] S1: The first mounting groove is set on the housing using laser cutting technology;

[0022] S2: Use thread milling to drill threaded holes on the right and left sides of the housing respectively;

[0023] S3: The induction coil is fixedly set on the outer side of the circumference of the permanent magnet ring, and the outer diameter of the permanent magnet ring is adapted to the inner diameter of the induction coil;

[0024] S4: The permanent magnet ring, induction coil, first excitation coil, and second excitation coil are arranged in the first mounting groove; the first excitation coil and the second excitation coil are distributed on the left and right sides of the permanent magnet ring and are symmetrical to each other;

[0025] S5: Using a polytetrafluoroethylene rod, pass through the first threaded hole, the first excitation coil, the permanent magnet ring, the induction coil, the second excitation coil, and the second threaded hole from left to right in sequence;

[0026] S6: Fill the first mounting groove with potting compound and form a filling area after the potting compound solidifies; then remove the polytetrafluoroethylene rod to form a cavity in the filling area, and put the end cap on the top of the first mounting groove to complete the fabrication of the composite magnetic field sensor mechanism.

[0027] Another aspect of the present invention provides a method of using a composite magnetic field sensor structure for detecting abrasive particles in lubricating oil, the method being applied to the aforementioned composite magnetic field sensor structure for detecting abrasive particles in lubricating oil, comprising:

[0028] S1: Connect oil pipes to the external oil pipes through the threaded holes on the left and right sides of the housing, and input lubricating grease into the composite magnetic field sensor structure through the oil pipes;

[0029] S2: AC power is input to the excitation coil through the connector, with a frequency range of 100kHz~500kHz;

[0030] S3: Obtain the induced electrical signal of the induction coil through the wiring connector;

[0031] S4: Based on the frequency of the input AC power, set the protection bandwidth, the maximum frequency of the low-frequency abrasive induced signal, the minimum frequency of the high-frequency abrasive induced signal, and the maximum frequency of the high-frequency abrasive induced signal, and use the bandpass sampling principle to determine the minimum bandpass sampling frequency of the abrasive induced electrical signal.

[0032] Preferably, determining the minimum bandpass sampling frequency of the abrasive particle induced electrical signal using the bandpass sampling principle includes:

[0033] According to the protection bandwidth The maximum frequency of low-frequency abrasive induction signal Minimum frequency value of high-frequency abrasive particle induction signal and the maximum frequency value of high-frequency abrasive induction signal Set constraints for the bandpass sampling principle;

[0034] By taking the largest even number within the range of n, the minimum bandpass sampling frequency of the abrasive particle induction signal can be obtained. .

[0035] S5: Based on the minimum bandpass sampling frequency of the abrasive induced electrical signal, perform distortion-free undersampling of the induced electrical signal to detect the specific situation of ferromagnetic and non-ferromagnetic abrasive particles.

[0036] The present invention has at least the following beneficial effects

[0037] This invention utilizes a permanent magnet ring and two excitation coils to create an eddy current magnetic field and a static magnetic field within the sensor. When non-ferromagnetic metal abrasive particles pass through the cavity, the particles are influenced by the eddy current magnetic field, transmitting the resulting changes to the induction coil. When ferromagnetic abrasive particles pass through the permanent magnet ring, the ring provides a constant static magnetic field, preventing the influence of current on the induced voltage signal of the induction coil. By placing the permanent magnet ring inside the induction coil and generating a static magnetic field, the change in magnetic flux caused by the metal abrasive particles is amplified, thus improving detection accuracy. This invention is compact, easy to install, and adaptable to various monitoring environments. It can simultaneously measure both ferromagnetic and non-ferromagnetic abrasive particles, enhancing the sensor's detection range for different types of abrasive particles. Attached Figure Description

[0038] Figure 1 This is a cross-sectional view of the composite magnetic field sensor mechanism of the present invention;

[0039] Figure 2 This is an exploded view of the composite magnetic field sensor mechanism of the present invention;

[0040] Figure 3 This is a schematic diagram of the composite magnetic field sensor mechanism of the present invention detecting the induced voltage of ferromagnetic abrasive particles;

[0041] Figure 4 This is a schematic diagram of the composite magnetic field sensor mechanism of the present invention for detecting the induced voltage of non-ferromagnetic abrasive particles.

[0042] Among them, 1. housing, 11. first mounting groove, 2. first excitation coil, 3. induction coil, 4. end cap, 41. first through hole, 5. filling area, 51. second through hole, 6. second excitation coil, 7. permanent magnet ring, 8. first threaded hole, 9. connector, 10. second threaded hole. Detailed Implementation

[0043] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0044] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures, and should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0045] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0046] Please see Figure 1 and Figure 2 This invention provides a composite magnetic field sensor structure for detecting abrasive particles in lubricating oil, comprising:

[0047] 1. Housing; 4. End cap; 7. Permanent magnet ring; 3. Induction coil; 2. First excitation coil; 6. Second excitation coil; 9. Terminal block;

[0048] The housing 1 is provided with a first mounting groove 11 on its upper surface, and the end cap 4 is adapted to the upper surface of the first mounting groove 11.

[0049] The permanent magnet ring 7, the induction coil 3, the first excitation coil 2, and the second excitation coil 6 are disposed in the first mounting groove 11;

[0050] The end cap 4 is provided with a first through hole 41 that extends vertically. A connector 9 is fixedly installed in the first through hole 41. The connector 9 is electrically connected to the induction coil 3, the first excitation coil 2, and the second excitation coil 6 respectively through wires.

[0051] The left and right sides of the housing 1 are respectively provided with a first threaded hole 8 and a second threaded hole 10 that communicate with the first mounting groove 11.

[0052] The first mounting groove 11 is filled with potting compound to form a filling object area 5; a second through hole 51 is provided on the left side of the filling object area 5;

[0053] The induction coil 3 is fixedly disposed on the outer side of the circumference of the permanent magnet ring 7, and the outer diameter of the permanent magnet ring 7 is adapted to the inner diameter of the induction coil 3.

[0054] The second through hole 51 passes through the inner circumference of the first excitation coil 2, the induction coil 3 and the second excitation coil 6 from left to right to form a cavity;

[0055] The second through hole 51 corresponds to the first threaded hole 8 and the second threaded hole 10 on the left and right sides, respectively.

[0056] The first excitation coil 2 and the second excitation coil 6 are connected to an external AC power supply via wires, forming an eddy current magnetic field. When non-ferromagnetic abrasive particles in the lubricating oil pass through, they disturb the magnetic field, causing a change in the induction coil 3. This change is transmitted through the wires connected to the induction coil 3, and the minimum frequency is obtained through minimum bandpass sampling, displaying the waveform on the screen. The permanent magnet ring 7 forms a static magnetic field. When ferromagnetic abrasive particles in the lubricating oil pass through, they disturb the magnetic field, causing a change in the induction coil 3, which is transmitted through the wires connected to the induction coil 3.

[0057] Preferably, the diameter of the second through hole 51 is the same as the inner diameter of the first excitation coil 2, the permanent magnet ring 7, and the second excitation coil 6. This ensures a complete fit with the formed oil passage, thereby improving the detection of abrasive particles in the oil.

[0058] Preferably, the first mounting groove 11 is a cylindrical groove or a square groove.

[0059] Preferably, the first threaded hole 8 and the second threaded hole 10 have the same diameter as the second through hole 51.

[0060] Preferably, the first excitation coil 2 and the second excitation coil 6 are distributed on the left and right sides of the permanent magnet ring and are symmetrical to each other to ensure that the disturbance formed by the induction coil 3 is eliminated.

[0061] Preferably, the first excitation coil 2 and the second excitation coil 6 are connected in series to form a circuit with an external AC power supply, and an eddy current magnetic field is formed when energized.

[0062] Preferably, the distance between the induction coil 3 and the first excitation coil 2 and the second excitation coil 6 is 0~10mm, which can more clearly show the waveform characteristics of different abrasive grains.

[0063] Based on the same idea as the composite magnetic field sensor structure for detecting abrasive particles in lubricating oil in the above embodiments, the present invention also provides a method for fabricating a composite magnetic field sensor structure for detecting abrasive particles in lubricating oil. This method can be used to fabricate the aforementioned composite magnetic field sensor structure for detecting abrasive particles in lubricating oil, comprising:

[0064] S1: A first mounting groove 11 is set on the housing 1 using laser cutting technology;

[0065] S2: Threaded holes 10 are drilled on the right and left sides of the housing 1 using the thread milling method;

[0066] S3: The induction coil 3 is fixedly set on the outer side of the circumference of the permanent magnet ring 7, and the outer diameter of the permanent magnet ring 7 is adapted to the inner diameter of the induction coil 3.

[0067] S4: The permanent magnet ring 7, the induction coil 3, the first excitation coil 2, and the second excitation coil 6 are placed in the first mounting groove 11; the first excitation coil 2 and the second excitation coil 6 are distributed on the left and right sides of the permanent magnet ring and are symmetrical to each other;

[0068] S5: Using a polytetrafluoroethylene rod, pass it from left to right through the first threaded hole 8, the first excitation coil 2, the permanent magnet ring 7, the induction coil 3, the second excitation coil 6, and the second threaded hole 10 in sequence.

[0069] S6: Fill the first mounting groove 11 with potting compound. After the potting compound solidifies, a filling area 5 is formed. Then, remove the polytetrafluoroethylene rod 8 to form a cavity in the filling area 5. Finally, cover the top of the first mounting groove 11 with the end cap 4 to complete the fabrication of the composite magnetic field sensor mechanism.

[0070] Based on the same idea as the composite magnetic field sensor structure for detecting abrasive particles in lubricating oil in the above embodiments, the present invention also provides a method for using the composite magnetic field sensor structure for detecting abrasive particles in lubricating oil. The method is applied to the composite magnetic field sensor structure for detecting abrasive particles in lubricating oil, comprising:

[0071] S1: Connect oil pipes to the external oil pipes through the threaded holes on the left and right sides of the housing, and input lubricating grease into the composite magnetic field sensor structure through the oil pipes;

[0072] S2: AC power is input to the excitation coil through the connector, with a frequency range of 100kHz~500kHz;

[0073] S3: Obtain the induced electrical signal of the induction coil through the wiring connector;

[0074] S4: Based on the frequency of the input AC power, set the protection bandwidth, the maximum frequency of the low-frequency abrasive induced signal, the minimum frequency of the high-frequency abrasive induced signal, and the maximum frequency of the high-frequency abrasive induced signal, and use the bandpass sampling principle to determine the minimum bandpass sampling frequency of the abrasive induced electrical signal.

[0075] Preferably, determining the minimum bandpass sampling frequency of the abrasive particle induced electrical signal using the bandpass sampling principle includes:

[0076] According to the protection bandwidth The maximum frequency of low-frequency abrasive induction signal Minimum frequency value of high-frequency abrasive particle induction signal and the maximum frequency value of high-frequency abrasive induction signal Set constraints for the bandpass sampling principle;

[0077] By taking the largest even number within the range of n, the minimum bandpass sampling frequency of the abrasive particle induction signal can be obtained. .

[0078] S5: Based on the minimum bandpass sampling frequency of the abrasive induced electrical signal, perform distortion-free undersampling of the induced electrical signal to detect the specific situation of ferromagnetic and non-ferromagnetic abrasive particles.

[0079] Example 1

[0080] In a preferred embodiment, we employ a Ferromagnetic abrasives and a When non-ferromagnetic abrasive particles flow uniformly past the sensor at a speed of 1 m / s, dynamic simulation is performed on the detection coil. First, this invention inputs AC current to the excitation coil, and connects external AC circuits to the excitation coils on both sides of the sensor as excitation sources to generate eddy current magnetic fields. Based on bandpass sampling, the abrasive particle-induced signal is undersampled without distortion at a frequency of 100 kHz, with GB set to 0.5 kHz. Set to 1kHz, 99 kHz Given a frequency of 100 kHz and n = 32 kHz, according to the constraints:

[0081]

[0082] This yields the minimum value of the bandpass sampling frequency of the abrasive particle induction signal. The frequency is 6.092 kHz. Connect the corresponding data acquisition card at the connector wire. When non-ferromagnetic metal abrasive particles pass through the sensor's oil circuit, they disturb the magnetic field within the channel, thereby changing the magnetic flux of the induction coil and generating an induced voltage that reflects the characteristics of the abrasive particles. This allows for the acquisition of the abrasive particle induction signal with the minimum bandpass sampling frequency. The sensor's central part uses a permanent magnet ring to apply a static magnetic field along the axial direction of the oil pipe as an excitation source to form a static magnetic field. When ferromagnetic metal abrasive particles pass through the sensor's oil circuit, they disturb the magnetic field within the channel, thereby changing the magnetic flux of the detection coil and generating an induced voltage that reflects the characteristics of the abrasive particles, thus obtaining the signal. Figure 4 and Figure 3 Curves of the change of induced voltage of abrasive particles with time are established for non-ferromagnetic and ferromagnetic abrasive particles, with the time of abrasive particle movement as the abscissa and the induced voltage generated during the movement of abrasive particles as the ordinate.

[0083] When metal abrasive particles pass through the sensor, different types of abrasive particles are affected by eddy current magnetic fields and static magnetic fields, which in turn affect the change in magnetic flux and thus the change in induced voltage. The winding direction of the coil and the direction of the current determine the direction of the magnetic field. That is, the change in induced voltage is related to the winding direction of the coil and the direction of the current. This can be determined by the right-hand screw theorem and Lenz's law, which will not be elaborated here.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for fabricating a composite magnetic field sensor structure for detecting abrasive particles in lubricating oil, characterized in that, The composite magnetic field sensor structure includes: Housing (1), end cap (4), permanent magnet ring (7), induction coil (3), first excitation coil (2), second excitation coil (6), terminal block (9); The housing (1) is provided with a first mounting groove (11) on its upper surface, and the end cap (4) is adapted to the upper surface of the first mounting groove (11); The permanent magnet ring (7), induction coil (3), first excitation coil (2), and second excitation coil (6) are disposed in the first mounting groove (11); The end cap (4) is provided with a first through hole (41) that runs vertically through the top and bottom. A connector (9) is fixedly installed in the first through hole (41). The connector (9) is electrically connected to the induction coil (3), the first excitation coil (2), and the second excitation coil (6) respectively through wires. The first excitation coil (2) and the second excitation coil (6) are connected in series. The left and right sides of the housing (1) are respectively provided with a first threaded hole (8) and a second threaded hole (10) that communicate with the first mounting groove (11). The first mounting groove (11) is filled with potting compound to form a filling object area (5); a second through hole (51) is provided on the left side of the filling object area (5). The induction coil (3) is fixedly arranged on the outer circumference of the permanent magnet ring (7), and the outer diameter of the permanent magnet ring (7) is adapted to the inner diameter of the induction coil (3); The second through hole (51) passes through the inner circumference of the first excitation coil (2), the induction coil (3), and the second excitation coil (6) from left to right to form a cavity; The second through hole (51) corresponds to the first threaded hole (8) and the second threaded hole (10) on the left and right respectively; The fabrication methods for the composite magnetic field sensor structure include: S1: The induction coil (3) is fixedly set on the outer side of the circumference of the permanent magnet ring (7), and the outer diameter of the permanent magnet ring (7) is adapted to the inner diameter of the induction coil (3); S2: The permanent magnet ring (7), the induction coil (3), the first excitation coil (2), and the second excitation coil (6) are placed in the first mounting groove (11); the first excitation coil (2) and the second excitation coil (6) are distributed on the left and right sides of the permanent magnet ring and are symmetrical to each other; S3: Using a polytetrafluoroethylene rod, pass through the first threaded hole (8), the first excitation coil (2), the permanent magnet ring (7), the induction coil (3), the second excitation coil (6), and the second threaded hole (10) from left to right. S4: Fill the first mounting groove (11) with potting compound and form a filling area (5) after the potting compound solidifies; and remove the polytetrafluoroethylene rod (8) to form a cavity in the filling area (5), and put the end cap (4) on the top of the first mounting groove (11) to complete the fabrication of the composite magnetic field sensor.

2. The method for fabricating a composite magnetic field sensor structure for detecting abrasive particles in lubricating oil according to claim 1, characterized in that, The diameter of the second through hole (51) is the same as the inner diameter of the first excitation coil (2), the permanent magnet ring (7), and the second excitation coil (6).

3. The method for fabricating a composite magnetic field sensor structure for detecting abrasive particles in lubricating oil according to claim 1, characterized in that, The first mounting groove (11) is a cylindrical groove or a square groove.

4. The method for fabricating a composite magnetic field sensor structure for detecting abrasive particles in lubricating oil according to claim 1, characterized in that, The first threaded hole (8) and the second threaded hole (10) have the same diameter as the second through hole (51).

5. The method for fabricating a composite magnetic field sensor structure for detecting abrasive particles in lubricating oil according to claim 1, characterized in that, The first excitation coil (2) and the second excitation coil (6) are distributed on the left and right sides of the permanent magnet ring and are symmetrical to each other.

6. The method for fabricating a composite magnetic field sensor structure for detecting abrasive particles in lubricating oil according to claim 1, characterized in that, The distance between the induction coil (3) and the first excitation coil (2) and the second excitation coil (6) is 0~10mm.

7. A method of using a composite magnetic field sensor structure for detecting abrasive particles in lubricating oil, the method being applied to the fabrication method of the composite magnetic field sensor structure for detecting abrasive particles in lubricating oil as described in any one of claims 1-6, characterized in that... include: S1: Connect oil pipes to the external oil pipes through the threaded holes on the left and right sides of the housing, and input lubricating grease into the composite magnetic field sensor structure through the oil pipes; S2: AC power is input to the excitation coil through the connector, with a frequency range of 100kHz~500kHz; S3: Obtain the induced electrical signal of the induction coil through the wiring connector; S4: Based on the frequency of the input AC power, set the protection bandwidth, the maximum frequency of the low-frequency abrasive induced signal, the minimum frequency of the high-frequency abrasive induced signal, and the maximum frequency of the high-frequency abrasive induced signal, and use the bandpass sampling principle to determine the minimum bandpass sampling frequency of the abrasive induced electrical signal. S5: Based on the minimum bandpass sampling frequency of the abrasive induced electrical signal, perform distortion-free undersampling of the induced electrical signal to detect the specific situation of ferromagnetic and non-ferromagnetic abrasive particles.

8. The method of using the composite magnetic field sensor structure for detecting abrasive particles in lubricating oil according to claim 7, characterized in that, The determination of the minimum bandpass sampling frequency of the abrasive particle induced electrical signal using the bandpass sampling principle includes: According to the protection bandwidth The maximum frequency of low-frequency abrasive induction signal Minimum frequency value of high-frequency abrasive particle induction signal and the maximum frequency value of high-frequency abrasive induction signal Set constraints for the bandpass sampling principle; The minimum bandpass sampling frequency of the abrasive particle induction signal is obtained by taking the largest even number within the range of n. .

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