Metallic abrasive grain detection sensor based on radial annular uniform magnetic field and calibration method

Abstract

The application discloses a metal abrasive particle detection sensor based on a radial annular uniform magnetic field and a calibration method thereof. A magnetic shielding shell is internally provided with a magnetic conducting cylinder, the bottom of the magnetic conducting cylinder is provided with a magnetic conducting sleeve, the center of the magnetic conducting sleeve is provided with a magnetic pole rod, the top end of the magnetic pole rod is processed with an annular first magnetic head, the magnetic pole rod is sleeved with an internal oil guiding part, an induction coil is arranged between the internal oil guiding part and the magnetic pole rod, the internal oil guiding part is sleeved with an external oil pipe, the lateral wall of the external oil pipe is processed with an oil conveying hole which is communicated with an annular oil cavity, the external oil pipe is sleeved with a magnetic pole sleeve, the inner side of the end of the magnetic pole sleeve which is close to the magnetic pole rod is provided with an annular second magnetic head, a magnetic exciting coil is arranged between the magnetic pole sleeve and the magnetic conducting cylinder, and an oil pipe joint is sequentially fixedly connected with the oil conveying hole on the external oil pipe through the through holes on the magnetic shielding shell and the magnetic conducting cylinder. The application detects the number, size and material attribute of the metal abrasive particles in the oil through the radial uniform magnetic field, effectively monitors the wear state of the equipment, and judges the abnormal wear failure and predicts the remaining service life of the equipment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of online oil abrasive particle monitoring, and particularly relates to a metal abrasive particle detection sensor based on a radial annular uniform magnetic field and a calibration method. BACKGROUND

[0002] Friction pair wear failure is one of the main reasons for mechanical equipment failure. The running environment of mechanical equipment is extremely harsh, and excessive wear will cause serious damage to the key components inside the equipment, and the sudden failure caused will increase the use cost of mechanical equipment, and even cause unnecessary personnel and property loss. Vibration monitoring and oil abrasive particle monitoring are necessary means to avoid sudden mechanical failure, among which vibration monitoring signal is easy to obtain and analyze quickly, and is effective for local crack failure of friction pair, but it is easily disturbed by background noise caused by external excitation and resonance, and is not sensitive to early wear failure of mechanical equipment. As a useful supplement to vibration monitoring technology, online oil abrasive particle monitoring technology can represent the detailed characteristics of equipment wear process in real time according to the concentration, size, shape and material characteristics of abrasive particles in lubricating oil, judge and find early wear failure of equipment. Due to its unique anti-interference ability and good practicability, it has attracted much attention.

[0003] The key of online oil abrasive particle monitoring technology is the design and research of metal abrasive particle sensor. At present, common metal abrasive particle sensors can be divided into resistance type, magnetic induction type, electrostatic induction type, ultrasonic type, photoelectric and image type, among which the magnetic induction type abrasive particle sensor has the characteristics of high sensitivity, fast detection speed and strong anti-interference ability, and has become a research hotspot. The most representative MetalSCAN magnetic induction type abrasive particle sensor developed by GasTops company in Canada has the ability to identify ferromagnetic and non-ferromagnetic abrasive particles, and can calculate the concentration and particle size distribution of abrasive particles. The sensor technology is not affected by oil flow and transparency, and has been widely used in the wear online monitoring of equipment such as transmission system of aircraft and wind power gear box. Pratt & Whitney company even applies military-grade MetalScan to monitor the wear of bearings and gears of F22 falcon fighter jet engine.

[0004] Many domestic researchers try to break through the technical bottleneck by using various innovative structural principles and methods to improve the oil flow capacity and detection accuracy of the magnetic induction abrasive particle sensor, and expect to obtain practicality. In order to realize the online monitoring of ferromagnetic and non-ferromagnetic abrasive particles in lubricating oil, the patent CN201810449933.7 discloses an online metal particle monitoring sensor and monitoring method based on axial high gradient magnetic field, which can realize metal abrasive particle monitoring under a larger oil flow capacity by generating a high gradient magnetic field distribution on the circular cross section of the oil pipe through the single wedge angle annular magnetic pole. However, the magnetic induction intensity of most abrasive particle detection areas is less than 100mT, and the uneven distribution of the high gradient magnetic field of such sensor in the radial direction of the oil pipe not only reduces the sensitivity and detection accuracy of the sensor, but also easily causes the misjudgment of the size of the abrasive particle. Therefore, the patent CN202011448946.6 proposes a metal abrasive particle detection sensor structure and detection method based on a planar induction coil, which makes the oil pipe as close as possible to the magnetic leakage gap area of the single wedge angle magnetic pole to increase the magnetic induction intensity of the abrasive particle detection area and improve the sensitivity and detection accuracy of the sensor. However, this inevitably requires reducing the cross-sectional area of the oil pipe, which cannot achieve the purpose of increasing the oil flow capacity of the sensor. In summary, most abrasive particle sensors are still in the laboratory application stage and are difficult to adapt to complex industrial sites and military fields, and cannot meet the needs of online monitoring of equipment wear state and abnormal wear fault diagnosis. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and provide a metal abrasive particle detection sensor based on a radial annular uniform magnetic field and a calibration method. The number, size and material properties of metal abrasive particles in oil are detected by a radial uniform magnetic field, the wear state of equipment is effectively monitored, and abnormal wear failure is judged and the remaining service life of equipment is predicted.

[0006] The technical solution adopted to solve the above technical problems is: a metal abrasive particle detection sensor based on a radial annular uniform magnetic field, a magnetic shielding shell is provided with a magnetic conducting cylinder, a magnetic conducting sleeve is arranged at the bottom of the magnetic conducting cylinder, a magnetic pole rod is installed at the center of the magnetic conducting sleeve, an annular first magnetic head is processed at the top end of the magnetic pole rod, an inner oil guide is sleeved on the magnetic pole rod, an induction coil is arranged between the inner oil guide and the magnetic pole rod, an outer oil pipe is sleeved on the inner oil guide, one end of the inner oil guide and one end of the outer oil pipe are integrated, and the other end of the inner oil guide and the inner wall of the outer oil pipe have a certain gap, forming an annular oil cavity, an oil delivery hole communicating with the annular oil cavity is processed on the side wall of the outer oil pipe, a magnetic pole sleeve is sleeved on the outer oil pipe, an annular second magnetic head is arranged on the inner side of one end of the magnetic pole sleeve close to the magnetic pole rod, the thickness of the second magnetic head is the same as that of the first magnetic head, the second magnetic head is aligned with the first magnetic head, an excitation coil is arranged between the magnetic pole sleeve and the magnetic conducting cylinder, through holes are processed on the magnetic shielding shell and the magnetic conducting cylinder at positions corresponding to the oil delivery hole of the outer oil pipe, and an oil pipe joint is connected and fixed with the oil delivery hole of the outer oil pipe through the through holes of the magnetic shielding shell and the magnetic conducting cylinder.

[0007] As a preferred technical scheme, the other end of the inner oil guide is conical, and the gap width between the inner oil guide and the inner wall of the outer oil pipe between the first magnetic head and the second magnetic head is 0.5-20 mm.

[0008] As a preferred technical scheme, the end face of the one end of the outer oil pipe provided with the inner oil guide is provided with a sealing washer between the inner bottom face of the magnetic conducting cylinder.

[0009] As a preferred technical scheme, the distance between the first magnetic head and the second magnetic head is 1-30 mm; the radial cross-sectional shape of the first magnetic head is isosceles trapezoidal or rectangular, and the bottom angle is 5°-90°; the radial cross-sectional shape of the second magnetic head is isosceles trapezoidal or rectangular, and the bottom angle is 5°-90°.

[0010] As a preferred technical scheme, the magnetic shielding shell is: an end cover is arranged at the open end of the cylindrical main shell, the center of the end cover is processed with an outer oil pipe mounting thread hole, and two copper rings are arranged on the inner wall of the main shell, and the inner diameter of the copper ring is equal to the outer diameter of the magnetic conducting cylinder.

[0011] The application also provides a magnetic pole centering and adjusting method of a metal abrasive particle detection sensor based on a radial annular uniform magnetic field, which consists of the following steps:

[0012] S1. energizing the excitation coil, and generating a uniform radial annular magnetic field between the first magnetic head and the second magnetic head as an excitation source;

[0013] S2. when the metal abrasive particle enters the gap between the inner oil guide and the outer oil pipe inner wall where the radial annular magnetic field is located, the magnetic flux in the excitation loop changes, the inductive coil detects the change of the magnetic flux in the magnetic pole rod, and generates an induced voltage signal, and the theoretical value of the induced voltage U is

[0014]

[0015] In the formula, r is the radius of the metal abrasive particle, N is the number of turns of the excitation coil, N D is the number of turns of the inductive coil, I is the current intensity of the excitation coil, μ t is the relative magnetic permeability of the abrasive particle, μ0 is the magnetic permeability in vacuum, v is the moving speed of the metal abrasive particle in the oil, and l s (x) is the length of the s-th radial magnetic force line;

[0016] The length l s (x) of the s-th radial magnetic force line is

[0017]

[0018] wherein, γ is the magnetic field line angle between the first magnetic head and the second magnetic head relative to the radial direction, x is the coordinate position of the s-th magnetic field line in the axial direction, θ is the polar angle of the point x in the polar coordinate, l b is the distance between the first magnetic head 6 and the second magnetic head;

[0019] S3. A non-metallic fiber line is placed in the detection area between the first magnetic head and the second magnetic head, and ferromagnetic metal balls with a diameter of 10-1000 μm are arranged on the non-metallic fiber line at equal intervals, so that the fiber line moves at a certain speed, the rotating magnetic pole rod is adjusted to change the induced voltage amplitude detected by the inductive coil of the detection sensor;

[0020] If the induced voltage amplitude is close to or equal to the maximum value U max , it can be considered that the center lines of the first magnetic head and the second magnetic head coincide and are aligned, and the magnetic pole sleeve and the magnetic pole rod are centered.

[0021] The beneficial effects of the present application are as follows:

[0022] First, the annular oil cavity is formed by embedding the outer sensor oil pipe into the conical inner oil guide, and the oil flow amount of the sensor oil pipe is effectively increased by increasing the cross-sectional area of the annular oil cavity.

[0023] Second, the structure of the two magnetic pole magnetic heads is used to generate a radial uniform magnetic field, and a high-strength magnetic flux density is formed in the abrasive particle detection area in the oil pipe annular oil cavity, thereby improving the sensitivity and accuracy of the ferromagnetic and non-ferromagnetic abrasive particle detection in the online oil abrasive particle monitoring process.

[0024] Third, uneven magnetic field distribution will cause differences in induced voltage when the same size abrasive particle passes through different positions of the oil pipe cross section, resulting in inaccurate detection results. The metal abrasive particle detection sensor of the present application can form an approximately uniform magnetic field distribution in the abrasive particle detection area, ensuring that the consistency of the induced voltage signals obtained when the abrasive particle passes through the oil pipe annular cross section is good, so as to improve the accuracy of the abrasive particle detection of the sensor.

[0025] Fourth, the overall structure of the sensor of the present application is compact, and the installation and disassembly are simple and convenient. The magnetic pole centering adjustment method involved can provide a scientific basis for sensor assembly, so that the magnetic flux density of the abrasive particle detection area of the sensor is stronger, the magnetic field distribution is more uniform, the abrasive particle detection result is accurate and reliable, and the sensor can be applied to online oil abrasive particle monitoring in different detection environments. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is the sectional view of the metal abrasive particle detection sensor of the present application based on the radial annular uniform magnetic field;

[0027] Figure 2is the exploded view of the metal abrasive grain detection sensor based on the radial annular uniform magnetic field of the present application;

[0028] Figure 3 is the magnetic field distribution along the axial direction of the oil pipe in the annular oil cavity between the outer oil pipe 7 and the inner oil guide 8 of the sensor of the present application;

[0029] Figure 4 is the magnetic field distribution in the radial cross section of the center of the air gap between the first magnetic head 6 and the second magnetic head 5 of the sensor of the present application;

[0030] Figure 5 is the magnetic field distribution curve along the axial direction of the annular oil cavity of the sensor of the present application;

[0031] Figure 6 is the induced voltage change of the spherical iron particles passing through the oil pipe of the sensor in the embodiment of the present application;

[0032] Figure 7 is the induced voltage change of the spherical copper particles passing through the oil pipe of the sensor in the embodiment of the present application;

[0033] Wherein: magnetic shielding shell 1; end cover 1-1; main shell 1-2; copper ring 1-3; magnetic conducting cylinder 2; excitation coil 3; magnetic pole sleeve 4; second magnetic head 5; first magnetic head 6; outer oil pipe 7; inner oil guide 8; sealing washer 9; magnetic conducting sleeve 10; magnetic pole rod 11; induction coil 12; oil pipe joint 13. DETAILED DESCRIPTION

[0034] In order to facilitate those skilled in the art to more clearly understand the advantages and features of the present application, the present application will be further described in detail below in conjunction with the drawings and examples, but the present application is not limited to the following embodiments.

[0035] Example 1

[0036] In Figure 1 and Figure 2In the embodiment, the magnetic shielding shell 1 of the metal abrasive particle detection sensor based on the radial annular uniform magnetic field is provided with an end cover 1-1 on the open end of a barrel-shaped main shell 1-2, a threaded through hole for mounting an outer oil pipe 7 is formed in the center of the end cover 1-1, two copper rings 1-3 are arranged on the inner wall of the barrel-shaped main shell 1-2, the inner diameter of the copper ring 1-3 is equal to the outer diameter of the magnetic conducting cylinder 2, the magnetic conducting cylinder 2 is mounted in the barrel-shaped main shell 1-2 and fixed by the two copper rings 1-3, so that the magnetic conducting cylinder 2 is in an annular space state, which is conducive to magnetic shielding, a magnetic conducting sleeve 10 is mounted on the inner bottom of the magnetic conducting cylinder 2, a magnetic pole rod 11 is mounted on the center of the magnetic conducting sleeve 10 through threaded connection, the magnetic pole rod 11 and the magnetic conducting sleeve 10 can rotate relative to each other, an annular first magnetic head 6 is formed on the top end of the magnetic pole rod 11, the radial cross-sectional shape of the first magnetic head 6 is isosceles trapezoidal, the bottom angle is 45°, the first magnetic head 6 is integrated with the magnetic pole rod 11, an inner oil guiding piece 8 is mounted on the magnetic pole rod 11, an induction coil 12 is wound and mounted between the magnetic pole rod 11 and the inner oil guiding piece 8, the outer oil pipe 7 is sleeved on the inner oil guiding piece 8 and threadedly connected to one end of the outer oil pipe 7, a sealing washer 9 is mounted between the end face of the one end of the outer oil pipe 7, where the inner oil guiding piece 8 is mounted, and the inner bottom surface of the magnetic conducting cylinder 2, the other end of the inner oil guiding piece 8 is tapered, which is used for shunting the liquid entering the outer oil pipe 7, an annular oil cavity is formed between the tapered end of the inner oil guiding piece 8 and the inner wall of the outer oil pipe 7, an oil delivery hole is formed in the side wall of the outer oil pipe 7, an oil pipe joint 13 is threadedly and sealingly fixed on the oil delivery hole, the other end of the oil pipe joint 13 extends out of the magnetic shielding shell 1 through a through hole formed in the magnetic conducting cylinder 2, a magnetic pole sleeve 4 is sleeved on the outer oil pipe 7, an annular second magnetic head 5 is formed on the inner side of the end of the magnetic pole sleeve 4 close to the magnetic pole rod 11, the radial cross-sectional shape of the second magnetic head 5 is isosceles trapezoidal, the bottom angle is 45°, the thickness of the second magnetic head 5 is the same as that of the first magnetic head 6, the second magnetic head 5 is integrated with the magnetic pole sleeve 4, the second magnetic head 5 is aligned with the first magnetic head 6 on the top end of the magnetic pole rod 11, the distance between the first magnetic head 6 and the second magnetic head 5 is 6 mm, the gap width between the inner oil guiding piece 8 and the inner wall of the outer oil pipe 7 clamped between the first magnetic head 6 and the second magnetic head 5 is 4 mm, which is the abrasive particle detection area, the width of the abrasive particle detection area along the oil pipe axis is equal to the thickness of the second magnetic head 5, and an excitation coil 3 is wound and mounted between the magnetic pole sleeve 4 and the magnetic conducting cylinder 2.

[0037] The magnetic pole centering and adjusting method of the metal abrasive particle detection sensor based on the radial annular uniform magnetic field of the embodiment comprises the following steps:

[0038] S1. The excitation coil 3 is energized, and the first magnetic head 6 and the second magnetic head 5 of the detection sensor generate an approximately uniform radial annular magnetic field as an excitation source;

[0039] S2. When the metal abrasive enters the gap between the inner oil guide 8 and the outer oil tube 7, the magnetic flux in the excitation circuit changes, the induction coil 12 detects the change of the magnetic flux in the magnetic pole rod 11 and generates an induced voltage signal, the theoretical value of the induced voltage U is

[0040]

[0041] In the formula, r is the radius of the metal abrasive, r = 0.5 mm, N is the number of turns of the excitation coil 3, N = 1000 turns, N D is the number of turns of the induction coil 12, N D = 6500 turns, I is the current intensity of the excitation coil 3, I = 0.6 A, μ t is the relative permeability of the abrasive, μ t = 2.0 × 10 -3 H / m, μ0 is the magnetic permeability in vacuum, μ0 = 1.26 × 10 -6 H / m, v is the moving speed of the metal abrasive in the oil, v = 1.0 m / s, l s (x) is the length of the s-th radial magnetic force line;

[0042] The length l s (x) of the s-th radial magnetic force line is

[0043]

[0044] In the formula, γ is the magnetic force line deflection angle between the first magnetic head 6 and the second magnetic head 5 relative to the radial direction, γ = 45°, x is the coordinate position of the s-th magnetic force line in the axial direction, the interval range of x is [-2.5, 2.5], θ is the polar angle of the point x in the polar coordinates, the interval range of θ is [0, 45°], l b is the distance between the first magnetic head 6 and the second magnetic head 5, l b = 6 mm;

[0045] S3. A non-metallic fiber line is placed in the detection area between the first magnetic head 6 and the second magnetic head 5, and ferromagnetic metal balls with a diameter of 10-1000 μm are arranged at equal intervals on the non-metallic fiber line, so that the fiber line moves at a certain speed, the magnetic pole rod 11 is rotated to change the induced voltage amplitude detected by the induction coil 12 of the detection sensor;

[0046] If the induced voltage amplitude is close to or approximately equal to the maximum value U max calculated theoretically at a certain speed, it can be considered that the center lines of the first magnetic head 6 and the second magnetic head 5 coincide and are aligned, and the magnetic pole sleeve 4 and the magnetic pole rod 11 are centered. Finally, the locking screw is installed to fix the position of the magnetic pole rod 11, and the magnetic pole centering adjustment is completed.

[0047] To further illustrate the magnetic field distribution within the metal abrasive particle detection sensor based on a radially annular uniform magnetic field in this embodiment, and the induced voltage generated within the induction coil 12 when abrasive particles flow through the sensor, a finite element analysis of the metal abrasive particle detection sensor in this embodiment was performed using the electromagnetic analysis software Ansoft Maxwell.

[0048] When an electromagnetic force of 600 AN is applied to the excitation coil, the axial distribution of the magnetic field between the outer oil pipe 7 and the inner oil guide 8 is as follows: Figure 3 As shown, the maximum magnetic induction intensity B at the center line of magnetic pole sleeve 4 and magnetic pole rod 11 is 3.0 × 10⁻⁶. -1 The magnetic field strength (B) gradually decreases towards both ends of the Tesla sensor, and the magnetic field strength at the edge of the abrasive particle detection area is greater than 2.428 × 10⁻⁶. -1 The magnetic field distribution in the abrasive detection area along the oil pipe axis is relatively uniform, as seen in the Tesla model. Figure 4 The radial distribution of the magnetic induction intensity generated between the first magnetic head 6 and the second magnetic head 5 within the annular oil cavity shows good uniformity in the radial distribution. The magnetic induction intensity near the end of the second magnetic head 5 is 2.687 × 10⁻⁶. -1 Tesla's magnetic field strength gradually increases inwards, reaching a maximum of 3.136 × 10⁻⁶ at the tip closest to the first magnetic head. -1 Tesla; Figure 5 With the center line of the aligned first magnetic head 6 and second magnetic head 5 as the 0 mark, the change of the magnetic induction intensity curve in the annular oil cavity of the sensor along the axial direction shows that the magnetic field follows a normal distribution. The extreme value of the magnetic induction intensity in the abrasive detection area is about 300mT. The magnetic induction intensity changes significantly when approaching the magnetic head, and the magnetic field intensity is about 0mT when away from the magnetic head. Therefore, the magnetic flux of the induction coil 12 will only change drastically when the abrasive passes through the abrasive detection area at the ends of the first and second magnetic heads. This helps to improve the sensitivity and accuracy of abrasive detection.

[0049] A spherical iron particle with a diameter of 0.5 mm is bonded and fixed to a non-metallic fiber thread. When a DC motor pulls the fiber thread at a speed of 1 m / s through the sensor at a constant speed, the curve of the induced voltage change over time detected by the induction coil 12 is as follows. Figure 6 As shown in the figure, when the abrasive particle enters the detection area, the induced voltage first increases positively until it reaches a peak value of approximately 120mV, then decreases negatively to a trough value of approximately -50mV. When the abrasive particle moves away from the detection area, the induced voltage signal curve gradually converges, and the voltage amplitude tends to 0. Correspondingly, when a spherical copper particle with a diameter of 0.5mm is bonded and fixed to a non-metallic fiber wire, and a DC motor pulls the fiber wire through the sensor at the same constant speed, the curve of the detected induced voltage change is shown in the figure. Figure 7The change process of the induced voltage of the copper particles is shown in the figure. It can be seen that the change process of the induced voltage of the copper particles is just opposite to that of the iron particles, that is, when the abrasive particles enter the detection area, the induced voltage first decreases negatively, then gradually increases to positive voltage, and slowly oscillates to 0. At this time, the peak value of the induced voltage generated by the copper particles during movement is about 16 mV, and the valley value is about -30 mV. It is thus illustrated that the change of the induced voltage amplitude generated by the metal abrasive particle detection sensor based on the radial annular uniform magnetic field in the embodiment can reflect the size of the abrasive particles, and the shape change of the induced voltage signal curve can effectively distinguish ferromagnetic and non-ferromagnetic abrasive particles; under the same size condition, the induced voltage amplitude of the ferromagnetic abrasive particles is greater than that of the non-ferromagnetic abrasive particles.

[0050] Example 2

[0051] In this embodiment, the magnetic shielding shell 1 is provided with a magnetic conducting cylinder 2, a magnetic conducting sleeve 10 is arranged at the inner bottom of the magnetic conducting cylinder 2, a magnetic pole rod 11 is arranged at the center of the magnetic conducting sleeve 10 through threaded connection, an annular first magnetic head 6 is processed at the top end of the magnetic pole rod 11, the radial cross-sectional shape of the first magnetic head 6 is isosceles trapezoidal, the bottom angle is 5°, the first magnetic head 6 is integrated with the magnetic pole rod 11, an inner oil guiding piece 8 is arranged on the magnetic pole rod 11, an induction coil 12 is wound and arranged between the magnetic pole rod 11 and the inner oil guiding piece 8, an outer oil pipe 7 is sleeved on the inner oil guiding piece 8 and is threadedly connected with one end of the outer oil pipe 7, a sealing washer 9 is arranged between the end face of the one end of the outer oil pipe 7, to which the inner oil guiding piece 8 is arranged, and the inner bottom surface of the magnetic conducting cylinder 2, the other end of the inner oil guiding piece 8 is tapered, which is used for shunting the liquid entering the outer oil pipe 7, an annular oil cavity is formed between the tapered end of the inner oil guiding piece 8 and the inner wall of the outer oil pipe 7, a magnetic pole sleeve 4 is sleeved on the outer oil pipe 7, an annular second magnetic head 5 is processed on the inner side of the one end of the magnetic pole sleeve 4 close to the magnetic pole rod 11, the radial cross-sectional shape of the second magnetic head 5 is isosceles trapezoidal, the bottom angle is 5°, the thickness of the second magnetic head 5 is the same as that of the first magnetic head 6, the second magnetic head 5 is integrated with the magnetic pole sleeve 4, the second magnetic head 5 is aligned with the first magnetic head 6 at the top end of the magnetic pole rod 11, the distance between the first magnetic head 6 and the second magnetic head 5 is 1 mm, and the gap width between the inner oil guiding piece 8 and the inner wall of the outer oil pipe 7 clamped between the first magnetic head 6 and the second magnetic head 5 is 0.5 mm, which is the abrasive particle detection area. The other components and the connection relationship of the components are the same as those in Example 1.

[0052] Example 3

[0053] In the embodiment, the magnetic shielding shell 1 is provided with a magnetic conducting cylinder 2, a magnetic conducting sleeve 10 is arranged at the bottom of the magnetic conducting cylinder 2, a magnetic pole rod 11 is arranged at the center of the magnetic conducting sleeve 10 through threaded connection, an annular first magnetic head 6 is arranged at the top end of the magnetic pole rod 11, the radial cross section of the first magnetic head 6 is rectangular, the first magnetic head 6 is integrated with the magnetic pole rod 11, an inner oil guiding part 8 is arranged on the magnetic pole rod 11, an induction coil 12 is wound and arranged between the magnetic pole rod 11 and the inner oil guiding part 8, the inner oil guiding part 8 is sleeved with an outer oil pipe 7 and is threadedly connected with one end of the outer oil pipe 7, a sealing washer 9 is arranged between the end face of the outer oil pipe 7, which is arranged with the inner oil guiding part 8, and the inner bottom surface of the magnetic conducting cylinder 2, the other end of the inner oil guiding part 8 is tapered, which is used for shunting the liquid entering the outer oil pipe 7, an annular oil cavity is formed between the tapered end of the inner oil guiding part 8 and the inner wall of the outer oil pipe 7, a magnetic pole sleeve 4 is sleeved on the outer oil pipe 7, an annular second magnetic head 5 is arranged at the inner side of one end of the magnetic pole sleeve 4 close to the magnetic pole rod 11, the radial cross section of the second magnetic head 5 is rectangular, the thickness of the second magnetic head 5 is the same as that of the first magnetic head 6, the second magnetic head 5 is integrated with the magnetic pole sleeve 4, the second magnetic head 5 is aligned with the first magnetic head 6 at the top end of the magnetic pole rod 11, the distance between the first magnetic head 6 and the second magnetic head 5 is 30 mm, the gap width between the inner oil guiding part 8 and the inner wall of the outer oil pipe 7, which are clamped between the first magnetic head 6 and the second magnetic head 5, is 20 mm, which is used as a grinding grain detection area. The other components and the connection relationship of the components are the same as those in Embodiment 1.

[0054] The above embodiments are only used for describing the technical solutions of the present application, but not for limiting the protection scope of the present application, any modification of the present application without departing from the scope and purpose of the technical solutions is equivalent to replacement, improvement, etc., which are all covered in the protection scope of the claims of the present application.

Claims

1. A metal abrasive grain detection sensor based on a radial annular uniform magnetic field, characterized by: The magnetic shielding shell (1) is provided with a magnetic conducting cylinder (2), the bottom of the magnetic conducting cylinder (2) is provided with a magnetic conducting sleeve (10), the magnetic conducting sleeve (10) is provided with a magnetic pole rod (11) in the center, the top end of the magnetic pole rod (11) is provided with a ring-shaped first magnetic head (6), the magnetic pole rod (11) is provided with an inner oil guiding part (8), the inner oil guiding part (8) and the magnetic pole rod (11) are provided with an induction coil (12), the inner oil guiding part (8) is provided with an outer oil pipe (7), one end of the inner oil guiding part (8) and one end of the outer oil pipe (7) are integrated, the other end of the inner oil guiding part (8) and the inner wall of the outer oil pipe (7) are provided with a gap, forming a ring-shaped oil cavity, the side wall of the outer oil pipe (7) is provided with an oil conveying hole connected with the ring-shaped oil cavity, the outer oil pipe (7) is provided with a magnetic pole sleeve (4), the inner side of the end of the magnetic pole sleeve (4) close to the magnetic pole rod (11) is provided with a ring-shaped second magnetic head (5), the thickness of the second magnetic head (5) is the same as that of the first magnetic head (6), the second magnetic head (5) is aligned with the first magnetic head (6), the magnetic pole sleeve (4) and the magnetic conducting cylinder (2) are provided with an excitation coil (3), the magnetic shielding shell (1) and the magnetic conducting cylinder (2) are provided with through holes at positions corresponding to the oil conveying hole of the outer oil pipe (7), and an oil pipe joint (13) passes through the through holes of the magnetic shielding shell (1) and the magnetic conducting cylinder (2) in sequence and is connected and fixed with the oil conveying hole of the outer oil pipe (7).

2. The radial ring-shaped uniform magnetic field-based metal abrasive grain detection sensor according to claim 1, characterized in that: The other end of the inner oil guiding part (8) is tapered, the gap between the inner oil guiding part (8) and the inner wall of the outer oil pipe (7) between the first magnetic head (6) and the second magnetic head (5) is 0.5-20mm.

3. The radial ring-shaped uniform magnetic field-based metal abrasive grain detection sensor according to claim 1, characterized in that: The end face of the end of the outer oil pipe (7) provided with the inner oil guiding part (8) and the inner bottom surface of the magnetic conducting cylinder (2) are provided with a sealing washer (9).

4. The radial ring-shaped uniform magnetic field-based metal abrasive grain detection sensor according to claim 1, characterized in that: The distance between the first magnetic head (6) and the second magnetic head (5) is 1-30mm, the radial cross-sectional shape of the first magnetic head (6) is isosceles trapezoidal or rectangular, and the bottom angle is 5-90°, the radial cross-sectional shape of the second magnetic head (5) is isosceles trapezoidal or rectangular, and the bottom angle is 5-90°.

5. The radial ring-shaped uniform magnetic field-based metal abrasive grain detection sensor according to claim 1, wherein The magnetic shielding shell (1) is: the opening end of the cylindrical main shell (1-2) is provided with an end cover (1-1), the center of the end cover (1-1) is provided with an outer oil pipe (7) mounting thread hole, the inner wall of the main shell (1-2) is provided with two copper rings (1-3), and the inner diameter of the copper ring (1-3) is equal to the outer diameter of the magnetic conducting cylinder (2).

6. The method of centering the poles of a metal abrasive grain detection sensor based on a radial annular uniform magnetic field according to any one of claims 1 to 5, characterized in that The method comprises the following steps: S1. energize the excitation coil (3), a uniform radial annular magnetic field is generated between the first magnetic head (6) and the second magnetic head (5) as an excitation source; S2. when the metal abrasive particles enter the outer oil pipe (7) and pass through the gap between the inner oil guiding part (8) and the inner wall of the outer oil pipe (7) where the radial annular magnetic field is located, the magnetic flux in the excitation circuit changes, the induction coil (12) detects the change of the magnetic flux in the magnetic pole rod (11) and generates an induced voltage signal, and the theoretical value of the induced voltage U is where r is the radius of the metal abrasive particle, N is the number of turns of the magnet coil (3), N D is the number of turns of the induction coil (12), I is the current intensity of the magnet coil (3), μ t is the relative permeability of the abrasive particle, μ0 is the permeability in vacuum, v is the moving speed of the metal abrasive particle in the oil, l s (x) is the length of the s-th radial magnetic force line; the length l of the s-th radial magnetic force line s (x) is where γ is the angle of the magnetic field lines between the first magnetic head (6) and the second magnetic head (5) with respect to the radial direction, x is the coordinate position of the s-th magnetic field line in the axial direction, θ is the polar angle of the point x in the polar coordinates, l b is the distance between the first magnetic head (6) and the second magnetic head (5); S3. A non-metallic fiber line is placed in the detection area between the first magnetic head (6) and the second magnetic head (5), and ferromagnetic metal balls with a diameter of 10-1000 μm are arranged at equal intervals on the fiber line, so that the fiber line moves at a constant speed in a straight line, and the rotating adjustment magnetic pole rod (11) is used to change the amplitude of the induced voltage detected by the detection sensor through the induction coil (12); If the amplitude of the induced voltage is close to or equal to the maximum value U max It can be considered that the first magnetic head (6) coincides and is aligned with the center line of the second magnetic head (5), and then the pole sleeve (4) is centered with the pole rod (11).

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