Anti-interference mounting structure of inductive sensor

Abstract

The application discloses an anti-interference installation structure of an inductive sensor, and aims to solve the technical problems of insufficient installation space and limited application scenarios caused by the requirement of a large anti-interference distance of the metal around the existing TURCK NI100U-K90SR-VP4X2 type inductive sensor, the structure comprises a metal protection box, an electromagnetic shielding assembly and a sensor body; the electromagnetic shielding assembly is two electromagnetic shielding films with the size of 25*10*0.5mm, which are respectively attached to the two sides above the sensor body; the top of the metal protection box is provided with an opaque anti-aging plastic cover plate, one end is provided with a through hole for connecting the wire, the bottom inner wall is provided with a sensor installation blind hole, and the outer wall is provided with a device fixing guide hole; the application shortens the anti-interference distance of the metal around the sensor to 18.5mm through local electromagnetic shielding, ensures the non-attenuation of the vertical detection distance of the sensor, and realizes the sealing protection of the sensor through the protection box, which significantly expands the application scenarios of the inductive sensor with high detection distance, and is especially suitable for mechanical equipment in narrow space.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of inductive sensor installation, and relates to an anti-interference installation structure of an inductive sensor, and particularly to the installation of a high-detection-distance inductive sensor such as a TURCK NI100U-K90SR-VP4X2 type inductive sensor in a narrow space mechanical device. BACKGROUND

[0002] In the field of industrial automation, inductive sensors are widely used in metal object position detection, counting and other scenarios due to their high detection accuracy and strong environmental adaptability. Among them, the NI100U-K90SR-VP4X2 type inductive sensor produced by TURCK company has a rated switching distance (detection distance Sn) of up to 100mm (metal signal detection above), which can meet the use requirements in a larger range of error scenarios and has high application value in various mechanical devices.

[0003] However, this type of sensor has significant use limitations: according to official technical data, when there are metal objects around the sensor, the interference-free distance between the metal and the sensor needs to be no less than 2xSn (i.e. 200mm). This requirement directly leads to a total installation space of the sensor of 490mm, which cannot meet the interference-free distance requirement due to the limited installation space of a large number of mechanical devices in the mechanical industry (such as small conveying devices, precision machining machines, etc.), greatly limiting the application scenarios of the high-detection-distance sensor.

[0004] At the same time, if the sensor is directly installed at the use position of the mechanical device, the sensor will be exposed to the external environment and face the risk of wind, sun, foreign matter collision, etc., which is easy to cause damage; if a protective box is configured for the sensor, the existing protective box made of metal material can provide sufficient protection, but the metal material will trigger the interference problem of the sensor, further exacerbating the contradiction of insufficient installation space; if a non-metal material protective box is used, its protection performance cannot meet the use requirements in harsh industrial environments.

[0005] In order to solve the above problems, relevant technical personnel try to reduce interference by shielding the metal around, but this method needs to use a large amount of electromagnetic shielding material, and is extremely sensitive to the position and distance of the metal around, and will also cause the detection distance attenuation rate of the sensor to exceed 70%, which seriously violates the original intention of using a high-detection-distance sensor, and cannot be practically applied. Therefore, in order to solve the above technical problems, the technical scheme of the present application is set. SUMMARY

[0006] The present application aims at overcoming the defects of the existing TURCK NI100U-K90SR-VP4X2 inductive sensor, which is limited in application due to the large metal interference-free distance, high installation space requirement and difficulty in protection, and provides an anti-interference installation structure of inductive sensor to achieve the following objectives:

[0007] 1. The metal interference-free distance around the sensor is shortened from 200mm to 18.5mm, meeting the installation requirement in narrow space;

[0008] 2. The vertical (upper) detection distance of the sensor is guaranteed without attenuation, maintaining the rated detection performance of 100mm;

[0009] 3. The sensor is provided with sealing, anti-aging and anti-collision protection effect, suitable for harsh industrial environment;

[0010] 4. The structure is simple, convenient to disassemble and assemble, and convenient for later maintenance and replacement.

[0011] The technical scheme adopted by the present application is as follows:

[0012] An anti-interference installation structure of inductive sensor, comprising a sensor body, an electromagnetic shielding assembly and a metal protection box;

[0013] The sensor body is a TURCK NI100U-K90SR-VP4X2 inductive sensor, and the rated detection distance Sn of the sensor body is 100mm;

[0014] The electromagnetic shielding assembly comprises two electromagnetic shielding films, each electromagnetic shielding film has a size of 25mmx10mmx0.5mm, and the two electromagnetic shielding films are attached to the left and right sides above the sensor body, and the length direction of the electromagnetic shielding film is consistent with the length direction of the sensor body;

[0015] The metal protection box is a box structure with an open top, and the internal cavity size of the metal protection box is matched with the overall size of the sensor body and the electromagnetic shielding assembly, and the metal protection box is used for accommodating the sensor body and the electromagnetic shielding assembly; The top of the metal protection box is detachably connected with an opaque anti-aging plastic cover plate, the material of the cover plate is polycarbonate (PC) or acrylonitrile-butadiene-styrene copolymer (ABS); One end of the metal protection box is provided with a through hole for connecting the lead wire, and the through hole is provided with a detachable sealing sleeve which can move along the lead wire, and the material of the sealing sleeve is oil-resistant rubber; The bottom inner wall of the metal protection box is provided with at least two sensor installation blind holes, and the hole diameter of the blind hole is matched with the installation screw hole at the bottom of the sensor body; The bottom outer wall of the metal protection box is provided with at least two equipment fixing guide holes, each equipment fixing guide hole is provided with a waterproof sealing ring, and the axis of the equipment fixing guide hole is parallel to the axis of the sensor installation blind hole.

[0016] Further, the electromagnetic shielding film is a ferrite wave-absorbing film, the magnetic permeability of which is greater than or equal to 800 mu0 (mu0 is the magnetic permeability of air), and the electromagnetic wave absorption efficiency in the frequency range of 100 kHz-1 MHz is greater than or equal to 85%.

[0017] Further, the metal protective box is made of 304 stainless steel, the wall thickness is 1.5-2 mm, the length of the internal cavity of the box body is the length of the sensor body+2 mm, the width is the width of the sensor body+2 mm, and the height is the height of the sensor body+the thickness of the electromagnetic shielding film+1 mm.

[0018] Further, the connection mode of the opaque anti-aging plastic cover plate and the metal protective box is screw connection, the edge of the cover plate is provided with a sealing rubber strip, and the sealing rubber strip is made of ethylene propylene diene rubber (EPDM).

[0019] Further, the hole diameter of the wire connecting through hole is the outer diameter of the sensor body wire+0.5-1 mm, the inner hole of the sealing sleeve is provided with an annular protrusion matched with the wire, and the number of the annular protrusions is 2-3.

[0020] Further, the depth of the sensor mounting blind hole is 5-8 mm, and the inner wall of the blind hole is provided with an internal thread, and the specification of the internal thread is consistent with the specification of the mounting screw hole at the bottom of the sensor body (such as M4 or M5).

[0021] Further, the hole diameter of the equipment fixing guide hole is the outer diameter of the fastening screw+0.2-0.3 mm, the cross section of the waterproof sealing ring is O-shaped, and the inner diameter of the sealing ring is matched with the outer diameter of the fastening screw, and the outer diameter is matched with the hole diameter of the equipment fixing guide hole.

[0022] The application also discloses the application of the above-mentioned anti-interference mounting structure in a drum-type conveying equipment, and the specific application mode is as follows:

[0023] The sensor body is fixed in the sensor mounting blind hole on the inner wall at the bottom of the metal protective box through a screw, so that the detection end of the sensor body faces upward, and the wire is led out from the wire connecting through hole at one end of the metal protective box, and the sealing of the wire and the through hole is realized through the sealing sleeve.

[0024] The opaque anti-aging plastic cover plate is fixed on the top of the metal protective box through a screw, so that the sealing rubber strip is compressed, and the sealing of the protective box is realized.

[0025] The whole mounting structure is fixed on the rack of the drum-type conveying equipment through the equipment fixing guide hole at the bottom of the metal protective box, and the detection end of the sensor body faces the lower part of the conveying drum, and the detection distance (the distance from the detection end of the sensor to the surface of the drum) is 100 mm.

[0026] Turn on the power supply of the sensor body, adjust the running speed of the conveying device (0.5-2 m / s), the sensor body can normally detect the metal objects conveyed on the surface of the roller, and the distance between the inner wall of the metal protection box and the sensor body is 18.5 mm, without interference phenomenon.

[0027] The working principle of the present application is as follows: based on the electromagnetic induction principle of the inductive sensor, the dual functions of anti-interference and protection are realized through the cooperative design of local electromagnetic shielding and the metal protection box, and the specific working principle is as follows:

[0028] The core working principle of the inductive sensor is: after the sensor body is powered on, the internal coil generates alternating current, and then forms an alternating magnetic field; when the metal object enters the range of the alternating magnetic field, the surface of the metal object will induce eddy current, and the reverse alternating magnetic field generated by the eddy current will weaken the original alternating magnetic field of the sensor; the sensor can judge whether there is a metal object nearby by detecting the change of the original alternating magnetic field (such as the change of inductance).

[0029] The anti-interference principle of the electromagnetic shielding assembly is: the electromagnetic shielding film (ferrite wave-absorbing film) attached to the two sides above the sensor body can absorb part of the alternating magnetic field radiated by the sensor to the surrounding; since the shielding film is only arranged on the two sides above the sensor, it will not affect the upward (detection direction) alternating magnetic field radiation of the sensor, so the detection ability (detection distance, sensitivity) of the sensor to the metal object above is not attenuated; at the same time, the magnetic field absorbed by the shielding film cannot reach the inner wall of the metal protection box, so that the inner wall (the metal around) of the metal protection box will not induce eddy current, thereby eliminating the interference of the metal around the sensor, and greatly shortening the interference-free distance (from 200 mm to 18.5 mm).

[0030] The protection principle of the metal protection box is: the metal protection box is made of 304 stainless steel material, which can resist collision of foreign matters and erosion of dust; the opaque anti-aging plastic cover plate (PC / ABS material) at the top has excellent anti-ultraviolet and anti-aging properties, which can avoid the aging of the sensor caused by direct sunlight; the sealing rubber strip at the edge of the cover plate, the sealing sleeve at the wire through hole, and the waterproof sealing ring in the equipment fixing guide hole jointly form a sealing structure, which prevents rainwater, oil stains and the like from entering the inside of the protection box, and ensures that the sensor is in a dry and clean working environment; the sensor mounting blind hole at the bottom and the equipment fixing guide hole respectively realize the stable connection of the sensor and the protection box, and the protection box and the equipment, and ensure the stability of the mounting structure.

[0031] In summary, due to the adoption of the above technical scheme, the present application has the following advantages:

[0032] 1. An anti-interference installation structure of an inductive sensor, which shortens the metal interference-free distance around the sensor from the official requirement of 200 mm to 18.5 mm, only 9.25% of the original distance, by attaching a specific size electromagnetic shielding film (25x10x0.5mm) on both sides above the sensor, successfully solving the core problem that a large number of narrow space equipment in the mechanical industry (such as small conveying roller, precision machine tool) cannot adapt to the high detection distance sensor.

[0033] 2. In the present application, the electromagnetic shielding film only absorbs the redundant magnetic field radiated by the sensor to the four directions, without affecting the magnetic field radiation in the vertical direction (detection direction) of the sensor. The vertical direction detection distance of the sensor is still maintained at 100 mm, with a decay rate of less than 5%, completely retaining the core advantage of the sensor "large detection range adapting error scene", avoiding the drawbacks of traditional full shielding scheme leading to more than 70% attenuation of detection distance.

[0034] 3. In the present application, the metal protection box (304 / 316 stainless steel) combines with the opaque anti-aging plastic cover plate (PC / ABS), EPDM / fluororubber sealing strip, oil-resistant rubber sealing sleeve and O-shaped waterproof sealing ring to build an IP65-IP68 level sealing protection system, which can resist rain, oil stains, dust, ultraviolet rays and slight impact, solving the problem of easy damage of the sensor directly installed, prolonging its service life to 2-3 times of the original scheme.

[0035] 4. In the present application, the present installation structure is not only suitable for roller conveying equipment, but also can be extended to chain conveyors, elevators, stamping equipment and other scenes that need metal detection, especially in small and medium-sized equipment with limited installation space, making the originally unable to use due to insufficient space (such as electronic component micro-conveying line, automobile parts precision assembly machine) can adapt to the high detection distance sensor.

[0036] 5. In the present application, through the 316 stainless steel protection box, UV-resistant cover plate and double-layer waterproof design, the structure can stably operate in the temperature range of-30℃ to 80℃, outdoor rainy days, oil-stained workshops and other harsh environments, breaking the limitation of traditional sensors that can only be used in indoor clean environment, expanding the application boundary of industrial automation detection.

[0037] 6. In the present application, there is no need to make large-scale structural modification (such as expanding the installation space, replacing the equipment model) to the existing equipment to adapt to the sensor, only need to be fixed directly through the installation structure, the modification cost is reduced by 60%-80%, especially suitable for the equipment upgrading needs of small and medium-sized enterprises.

[0038] 7. In the present application, the sealing protection design reduces the frequency of replacing the sensor due to damage and moisture, and the cover plate, sealing sleeve and other components can be individually disassembled, so that the maintenance time is shortened to 1 / 3 of the original scheme, and the annual maintenance cost is reduced by more than 50%. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings, wherein:

[0040] Figure 1 is a structural schematic diagram of the present application (the opaque anti-aging plastic cover plate is in a perspective state);

[0041] Figure 2 is a top view of the structure of the present application (the opaque anti-aging plastic cover plate is also in a perspective state);

[0042] Figure 3 is a front view of the structure of the present application (the sensor body, metal protective box and opaque anti-aging plastic cover plate are all in a perspective state);

[0043] Figure 4 is a three-dimensional view of the structure of the present application (the opaque anti-aging plastic cover plate is also in a perspective state);

[0044] Figure 5 is a three-dimensional view of the structure of the present application applied to a conveying device;

[0045] Marked in the figure: 1-sensor body, 2-metal protective box, 3-electromagnetic shielding film, 4-opaque anti-aging plastic cover plate, 5-through hole, 6-sensor mounting blind hole, 7-mounting screw hole, 8-equipment fixing guide hole. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the present application more clear and explicit, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described here are only used to explain the present application, and are not used to limit the present application, that is, the described examples are only some of the embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0047] The following detailed description of embodiments of the application in the drawings provided is not intended to limit the scope of the application claimed, but merely represents selected embodiments of the application. Based upon these embodiments of the application, those skilled in the art will be able to arrive at additional embodiments of the application, without the exercise of inventive capacity, and it is the intent of the present application that all such embodiments within the scope of the claims are covered.

[0048] It should be noted that the relational terms herein, such as first and second, and the like, are used solely to distinguish one from another entity or action, without necessarily requiring or implying any actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0049] The features and benefits of the present application will be further described in the following detailed description of embodiments.

[0050] Embodiment One

[0051] The anti-interference mounting structure of an inductive sensor of the present application, as shown in Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 includes a sensor body 1, an electromagnetic shielding assembly, and a metal protective box 2.

[0052] The sensor body 1 is a TURCK NI100U-K90SR-VP4X2 type inductive sensor, with a rated detection distance Sn of 100 mm.

[0053] The electromagnetic shielding assembly includes two electromagnetic shielding films 3, each of which has a size of 25 mm x 10 mm x 0.5 mm. The two electromagnetic shielding films 3 are respectively attached to the left and right sides above the sensor body 1, and the length direction of the electromagnetic shielding film 3 is consistent with the length direction of the sensor body 1.

[0054] The metal protective box 2 is a top-open box structure, the internal cavity size is matched with the overall size of the sensor body 1 and the electromagnetic shielding assembly, and is used for accommodating the sensor body 1 and the electromagnetic shielding assembly; the top of the metal protective box 2 is detachably connected with an opaque anti-aging plastic cover plate 4; one end of the metal protective box 2 is provided with a through hole 5 for connecting a wire, and the through hole 5 is provided with a detachable sealing sleeve which can move along the wire; the bottom inner wall of the metal protective box 2 is provided with at least two sensor mounting blind holes 6, the hole diameter of the sensor mounting blind hole 6 is matched with the mounting screw hole 7 at the bottom of the sensor body 1; the bottom outer wall of the metal protective box 2 is provided with at least two device fixing guide holes 8, each device fixing guide hole 8 is provided with a waterproof sealing ring, and the axis of the device fixing guide hole 8 is parallel to the axis of the sensor mounting blind hole 6.

[0055] The electromagnetic shielding film 3 is a ferrite wave-absorbing film, the magnetic permeability μ is greater than or equal to 800 μ0, and the electromagnetic wave absorption efficiency in the frequency range of 100 kHz-1 MHz is greater than or equal to 85%.

[0056] The material of the metal protective box 2 is 304 stainless steel and the wall thickness is 1.5-2 mm, the length of the internal cavity of the metal protective box 2 is the length of the sensor body 1+2 mm, the width is the width of the sensor body 1+2 mm, and the height is the height of the sensor body 1+the thickness of the electromagnetic shielding film 3+1 mm.

[0057] The material of the opaque anti-aging plastic cover plate 4 is polycarbonate or acrylonitrile-butadiene-styrene copolymer, and the connection mode of the opaque anti-aging plastic cover plate 4 and the metal protective box 2 is screw connection, the edge of the opaque anti-aging plastic cover plate 4 is provided with a sealing rubber strip, and the material of the sealing rubber strip is ethylene-propylene-diene rubber.

[0058] The cross-sectional size of the sealing rubber strip is 2-4 mm x 2-4 mm, and the bonding surface of the opaque anti-aging plastic cover plate 4 and the metal protective box 2 is coated with waterproof sealing glue.

[0059] The hole diameter of the through hole 5 is the outer diameter of the wire of the sensor body 1+0.5-1 mm, the inner hole of the sealing sleeve is provided with an annular protrusion matched with the wire, the number of the annular protrusions is 2-3, and the height of the annular protrusion is 0.5-1 mm.

[0060] The depth of the sensor mounting blind hole 6 is 5-8 mm, and the inner wall of the sensor mounting blind hole 6 is provided with an internal thread, the specification of the internal thread is consistent with the specification of the mounting screw hole 7 at the bottom of the sensor body 1, and the specification is M4 or M5.

[0061] The hole diameter of the device fixing guide hole 8 is the outer diameter of the fastening screw+0.2-0.3 mm, the cross section of the waterproof sealing ring is O-shaped, the inner diameter of the waterproof sealing ring is matched with the outer diameter of the fastening screw, the outer diameter of the waterproof sealing ring is matched with the hole diameter of the device fixing guide hole 8, and the material of the waterproof sealing ring is ethylene-propylene-diene rubber, fluoroelastomer or silicone rubber.

[0062] The distance between the inner wall of the metal protective box 2 and the sensor body 1 is 18.5 mm, and the detection distance of the sensor body 1 in the vertical direction is maintained at 100 mm, and the detection distance attenuation rate is ≤5%.

[0063] The specific implementation of the embodiment is a mounting structure suitable for a light roller conveying device

[0064] The embodiment is directed to a light roller conveying device (such as an electronic component production line) with a conveying weight ≤50 kg, and the specific structural parameters are as follows:

[0065] Sensor body: TURCK NI100U-K90SR-VP4X2 type, length 60 mm, width 30 mm, height 25 mm;

[0066] Electromagnetic shielding film: ferrite wave-absorbing film, size 25 mm x 10 mm x 0.5 mm, magnetic permeability 1000 μ0, absorption efficiency 90% at 100 kHz frequency;

[0067] Metal protective box: 304 stainless steel material, wall thickness 1.5 mm, internal cavity size 62 mm x 32 mm x 26 mm (length x width x height), 2 M4 sensor mounting blind holes (depth 5 mm) are arranged on the inner wall of the bottom, 2 M6 device fixing guide holes (hole diameter 6.3 mm) are arranged on the outer wall of the bottom, and O-shaped waterproof sealing rings (material EPDM) are arranged in the guide holes;

[0068] Cover plate: PC material opaque anti-aging cover plate, thickness 3 mm, edge EPDM sealing rubber strip (cross-sectional size 2 mm x 2 mm), connected with the protective box through 4 M3 screws;

[0069] Wire through hole: hole diameter 8 mm (adapted to the outer diameter of the sensor wire 7.5 mm), sealing sleeve is oil-resistant rubber material, and 2 annular protrusions (height 0.5 mm) are arranged in the inner hole.

[0070] Application mode: the mounting structure is fixed on the conveying device rack, the sensor detection end is 100 mm away from the surface of the roller, and the conveying speed is 0.5 m / s. Through testing, the sensor detection accuracy is 100%, the interference-free distance around is 18.5 mm, the protective box has no water inlet phenomenon in the IP65 environment, and there is no fault in continuous operation for 3000 hours.

[0071] Embodiment two

[0072] The specific implementation of the embodiment is a mounting structure for an inductive sensor, as shown in Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 ​

[0073] Mounting structure for medium-sized roller conveying equipment

[0074] This embodiment is aimed at medium-sized roller conveying equipment (such as automobile parts production line) conveying weight of 50-200 kg, and the specific structural parameters are as follows:

[0075] Sensor body: TURCK NI100U-K90SR-VP4X2 type, size same as embodiment 1;

[0076] Electromagnetic shielding film: ferrite wave-absorbing film, size 25 mm x 10 mm x 0.5 mm, magnetic permeability 1200 μ0, absorption efficiency 92% at 500 kHz frequency;

[0077] Metal protection box: 304 stainless steel material, wall thickness 2 mm, internal cavity size 62 mm x 32 mm x 26 mm, 2 M5 sensor mounting blind holes (depth 8 mm) are arranged on the bottom inner wall, 2 M8 equipment fixing guide holes (hole diameter 8.3 mm) are arranged on the bottom outer wall, and O-shaped waterproof sealing rings (fluorine rubber material) are arranged in the guide holes;

[0078] Cover plate: ABS material opaque anti-aging cover plate, thickness 4 mm, fluorine rubber sealing rubber strip (cross-sectional size 3 mm x 3 mm) is arranged on the edge, and the cover plate is connected with the protection box through 4 M4 screws;

[0079] Wire through hole: hole diameter 9 mm (adapted to the outer diameter 8 mm of the sensor wire), sealing sleeve is fluorine rubber material, and 3 annular protrusions (height 0.8 mm) are arranged in the inner hole.

[0080] Application mode: the mounting structure is fixed on the reinforced beam of the conveying equipment rack, the sensor detection end is 100 mm away from the roller surface, and the conveying speed is 1.5 m / s. Test shows that the sensor detection accuracy is 100%, the interference-free distance around is 18.5 mm, the protection box has no water and oil ingress phenomenon in IP67 environment, and has no failure in continuous operation for 5000 hours, and can resist slight vibration (vibration frequency 50 Hz, amplitude 0.1 mm).

[0081] Embodiment three

[0082] The mounting structure of the inductive sensor is shown in Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 The specific implementation mode of the embodiment is as follows:

[0083] Mounting structure for outdoor roller conveying equipment

[0084] This embodiment is directed to a roller conveying device for outdoor use (such as a building material production line), and the specific structural parameters are as follows:

[0085] Sensor body: TURCK NI100U-K90SR-VP4X2 type, size same as example 1;

[0086] Electromagnetic shielding film: ferrite wave-absorbing film, size 25mmx10mmx0.5mm, magnetic permeability 1500μ0, absorption efficiency 95% at 1MHz frequency;

[0087] Metal protective box: 316 stainless steel material (corrosion resistant), wall thickness 2mm, internal cavity size 62mmx32mmx26mm, 2 M4 sensor mounting blind holes (depth 6mm) are arranged on the inner wall of the bottom, 4 M6 device fixing guide holes (hole diameter 6.3mm) are arranged on the outer wall of the bottom, double-layer O-shaped waterproof sealing rings (silicone rubber material) are arranged in the guide holes;

[0088] Cover plate: PC+UV-resistant coating opaque cover plate, thickness 5mm, silicone rubber sealing rubber strip (cross-sectional size 4mmx4mm) is arranged on the edge, connected with the protective box through 6 M3 screws, and the joint surface of the cover plate and the protective box is coated with waterproof sealing glue;

[0089] Wire through hole: hole diameter 10mm (adapted to the outer diameter of the sensor wire 9mm), the sealing sleeve is made of silicone rubber material, 3 annular protrusions (height 1mm) are arranged in the inner hole, and a metal waterproof connector (type PG9) is arranged outside the through hole.

[0090] Application mode: fix the mounting structure in the rain cover of the outdoor conveying device, the sensor detection end is 100mm away from the surface of the roller, and the conveying speed is 2m / s. After testing, the sensor detection accuracy is 100%, the interference-free distance is 18.5mm, the protective box has no water ingress phenomenon in IP68 environment (immersed in 1m water depth for 30 minutes), and can resist temperature changes from-30℃ to 80℃, and has no failure after continuous operation for 8000 hours.

[0091] Experimental example one

[0092] I. Experimental basic conditions

[0093] Experimental sample: TURCK NI100U-K90SR-VP4X2 type sensor (n=5), 304 stainless steel protective box (wall thickness 1.8mm, inner wall distance from sensor 18.5mm), ferrite wave-absorbing film (25mmx10mmx0.5mm, μ=1200μ0);

[0094] Interference source: Q235 steel block (100mmx100mmx20mm, simulating industrial equipment metal parts);

[0095] Detection equipment: spectrum analyzer (Agilent N9320B, 100 kHz-1 MHz), laser range finder (accuracy ±0.1 mm), high and low temperature test box (-40℃~100℃);

[0096] Control group: ① No shielding scheme (sensor directly exposed); ② Full shielding scheme (sensor four sides with the same specification ferrite film).

[0097] II. Core experimental data and analysis

[0098] 1. Interference-free distance verification experiment

[0099] Scheme type Interference source material Minimum distance of false triggering (mm) Standard deviation (mm) Reduction rate from official requirement (200 mm) Local shielding of the invention Q235 steel 18.5 ≤0.3 90.75% No shielding scheme Q235 steel 50.2 ≤0.5 74.90% Full shielding scheme Q235 steel 22.1 ≤0.4 88.95% Experimental description: Taking the continuous 3 false triggering of the sensor (output signal without metal detection) as the judgment standard, the interference-free distance of the invention scheme is only 18.5 mm, which is better than the full shielding scheme and far lower than the official requirement of 200 mm, meeting the installation requirements in narrow space.

[0100] Table 1

[0101] 2. Detection distance attenuation rate experiment

[0102] Scheme type Test frequency (kHz) Rated detection distance (mm) Actual detection distance (mm) Attenuation rate Detection accuracy (metal block passing response time) Local shielding of the invention 100 100 99.8 0.2% ≤10 ms Local shielding of the invention 500 100 98.5 1.5% ≤12 ms Local shielding of the invention 1000 100 95.3 4.7% ≤15 ms Full shielding scheme 100 100 28.1 71.9% ≤30 ms No shielding scheme 100 100 97.2 2.8% ≤11 ms Experimental description: Within 100 kHz-1 MHz (sensor working main frequency range), the attenuation rate of the invention scheme is always ≤5%, and the detection response speed is close to the no shielding scheme; while the full shielding scheme completely loses the advantage of high detection distance due to blocking the detection direction magnetic field, with an attenuation rate exceeding 70%.

[0103] Table 2

[0104] 3. Electromagnetic shielding effectiveness experiment (100 kHz-1 MHz frequency band)

[0105] Test frequency band (kHz) Ferrite film absorption rate (%) Ferrite film reflectivity (%) Shielding attenuation of metal protection box (dB) Overall shielding effectiveness (dB) 100 89.2 8.5 42.3 50.8 500 92.5 6.1 45.1 51.2 1000 94.7 4.3 47.8 52.1 Experimental description: Using the "absorption + shielding" synergistic mechanism, the ferrite film absorbs more than 85% of the redundant magnetic field, and the remaining magnetic field is shielded by the metal protection box (attenuation of more than 42 dB), with an overall shielding effectiveness of more than 50 dB, which is much higher than the industrial equipment electromagnetic compatibility (EMC) Class B level requirement (≤30 dB).

[0106] Table 3

[0107] 4. Environmental adaptability supplementary experiment

[0108] Environmental conditions Experimental duration (h) Detection distance change (mm) False alarm rate Sealing performance (IP level) -30℃~80℃ high and low temperature cycle 1000 95.3→94.8（-0.5%） 0% IP68 (no water ingress) 10-500Hz vibration (amplitude 0.5mm) 500 95.3→95.1（-0.2%） 0% No shedding of sealing rubber strip Oil immersion (5# mechanical oil) 200 95.3→95.0（-0.3%） 0% No swelling of sealing sleeve Experimental description: In the industrial harsh environment, the structural stability and shielding performance do not show significant attenuation, verifying the reliability of the 304 stainless steel protection box and the EPDM sealing element.

[0109] Table 4

[0110] III. Technical mechanism verification conclusion

[0111] Local shielding effectiveness: only attach ferrite film on both sides above the sensor, can directional absorption of redundant magnetic field (absorption rate ≥85%), avoid metal protective box induced eddy current, make interference-free distance from 200mm to 18.5mm;

[0112] Detection performance retention: no shielding is set in the detection direction (vertically upward), the magnetic field radiation is not interrupted, the detection distance attenuation rate is ≤5%, completely retains 100mm rated detection capability;

[0113] Synergistic protection advantage: metal protective box and shielding film form a "physical protection + electromagnetic shielding" double system, shielding effectiveness is more than 50dB, at the same time meet IP68 sealing and anti-aging requirements.

[0114] The above merely describes preferred embodiments, experimental examples of the present application, and is not intended to limit the protection scope of the present application, and any modification, equivalent replacement and improvement made by any skilled person within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An anti-interference mounting structure of an inductive sensor, characterized by: It comprises a sensor body (1), an electromagnetic shielding assembly and a metal protective box (2); The sensor body (1) is a TURCK NI100U-K90SR-VP4X2 inductive sensor, and the rated detection distance Sn is 100 mm; The electromagnetic shielding assembly comprises two electromagnetic shielding films (3), each of which has a size of 25 mm x 10 mm x 0.5 mm, and is attached to the left and right sides above the sensor body (1), and the length direction of the electromagnetic shielding film (3) is consistent with the length direction of the sensor body (1). The metal protective box (2) is a box structure with an open top, and the internal cavity size is adapted to the overall size of the sensor body (1) and the electromagnetic shielding assembly for accommodating the sensor body (1) and the electromagnetic shielding assembly; the top of the metal protective box (2) is detachably connected with an opaque anti-aging plastic cover plate (4); one end of the metal protective box (2) is provided with a through hole (5) for connecting the lead, and the through hole (5) is provided with a detachable sealing sleeve which can move along the lead; the bottom inner wall of the metal protective box (2) is provided with at least two sensor mounting blind holes (6), the hole diameter of the sensor mounting blind hole (6) is adapted to the mounting screw hole (7) at the bottom of the sensor body (1); the bottom outer wall of the metal protective box (2) is provided with at least two device fixing guide holes (8), each of which is provided with a waterproof sealing ring, and the axis of the device fixing guide hole (8) is parallel to the axis of the sensor mounting blind hole (6).

2. An anti-interference mounting structure for an inductive sensor according to claim 1, characterized in that: The electromagnetic shielding film (3) is a ferrite wave-absorbing film, and its magnetic permeability μ is greater than or equal to 800μ0, and the electromagnetic wave absorption efficiency in the frequency range of 100 kHz-1 MHz is greater than or equal to 85%.

3. An anti-interference mounting structure for an inductive sensor according to claim 2, characterized in that: The material of the metal protective box (2) is 304 stainless steel with a wall thickness of 1.5-2 mm, the length of the internal cavity of the metal protective box (2) is the length of the sensor body (1) + 2 mm, the width is the width of the sensor body (1) + 2 mm, and the height is the height of the sensor body (1) + the thickness of the electromagnetic shielding film (3) + 1 mm.

4. An anti-interference mounting structure for an inductive sensor according to claim 1, characterized in that: The material of the opaque anti-aging plastic cover plate (4) is polycarbonate or acrylonitrile-butadiene-styrene copolymer, and the connection between the opaque anti-aging plastic cover plate (4) and the metal protective box (2) is screw connection, the edge of the opaque anti-aging plastic cover plate (4) is provided with a sealing rubber strip, and the material of the sealing rubber strip is ethylene-propylene-diene rubber.

5. An anti-interference mounting structure for an inductive sensor according to claim 4, characterized in that: The cross-sectional size of the sealing rubber strip is 2-4 mm x 2-4 mm, and the bonding surface between the opaque anti-aging plastic cover plate (4) and the metal protective box (2) is coated with waterproof sealant.

6. An anti-interference mounting structure for an inductive sensor according to claim 1, characterized in that: The hole diameter of the through hole (5) is the outer diameter of the lead of the sensor body (1) + 0.5-1 mm, the inner hole of the sealing sleeve is provided with an annular protrusion adapted to the lead, the number of the annular protrusions is 2-3, and the height of the annular protrusion is 0.5-1 mm.

7. An anti-interference mounting structure for an inductive sensor according to claim 1, characterized in that: The depth of the sensor mounting blind hole (6) is 5-8 mm, and the inner wall of the sensor mounting blind hole (6) is provided with internal threads, the specification of the internal threads is consistent with the specification of the mounting screw hole (7) at the bottom of the sensor body (1), and the specification is M4 or M5.

8. An anti-interference mounting structure for an inductive sensor according to claim 1, characterized in that: The hole diameter of the equipment fixing guide hole (8) is the outer diameter of the fastening screw + 0.2-0.3 mm, the fastening screw is used to install the metal protection box (2) on the mechanical equipment to be used, the cross section of the waterproof sealing ring is O-shaped, the inner diameter of the waterproof sealing ring is matched with the outer diameter of the fastening screw, the outer diameter of the waterproof sealing ring is matched with the hole diameter of the equipment fixing guide hole (8), and the material of the waterproof sealing ring is ethylene propylene rubber, fluorine rubber or silicone rubber.

9. An anti-interference mounting structure for an inductive sensor according to any one of claims 1 to 8, characterized in that: The distance between the inner wall of the metal protection box (2) and the sensor body (1) is 18.5 mm, and the vertical detection distance of the sensor body (1) is maintained at 100 mm, and the detection distance attenuation rate is less than or equal to 5%.

Images