Anti-interference mounting structure of inductive sensor

Abstract

The invention discloses an anti-interference mounting structure of an inductive sensor, and aims to solve the technical problems of insufficient mounting space and limited application scene caused by high requirement on interference-free distance of peripheral metal of the conventional TURCKNI100U-K90SR-VP4X2 type inductive sensor, the structure comprises a metal protection box, an electromagnetic shielding assembly and a sensor body; the electromagnetic shielding assembly comprises two electromagnetic shielding films with the size of 25 * 10 * 0.5 mm, and the two electromagnetic shielding films are attached to the two sides of the upper portion of the sensor body respectively. The top of the metal protection box is provided with a non-transparent anti-aging plastic cover plate, one end is provided with a through hole for wire connection, the inner wall of the bottom is provided with a sensor mounting blind hole, and the outer wall is provided with an equipment fixing guide hole. The metal interference-free distance around the sensor is shortened to 18.5 mm through local electromagnetic shielding, meanwhile, it is guaranteed that the detection distance of the sensor in the vertical direction is not attenuated, sealing protection of the sensor is achieved through the protection box, the application scene of the high-detection-distance inductive sensor is remarkably expanded, and the high-detection-distance inductive sensor is particularly suitable for mechanical equipment in a narrow space.

Description

Technical Field

[0001] This invention belongs to the technical field of inductive sensor installation, and relates to an anti-interference installation structure for inductive sensors, which is particularly suitable for the installation and use of TURCKNI100U-K90SR-VP4X2 type constant height detection distance inductive sensors in mechanical equipment in confined spaces. Background Technology

[0002] In the field of industrial automation, inductive sensors are widely used in scenarios such as position detection and counting of metal objects due to their advantages such as high detection accuracy and strong environmental adaptability. Among them, the NI100U-K90SR-VP4X2 inductive sensor produced by TURCK has a rated switching distance (detection distance Sn) of up to 100mm (detecting metal signals from above), which can meet the needs of use under a wide range of error conditions and has high application value in various mechanical equipment.

[0003] However, this sensor model has significant limitations: according to official technical data, when there are metal objects around the sensor, the interference-free distance between the metal and the sensor must be no less than 2×Sn (i.e., 200mm). This requirement directly results in a total installation space of 490mm for the sensor. However, the installation space of many mechanical equipment in the machinery industry (such as small conveying equipment, precision machine tools, etc.) is limited, making it impossible to meet this interference-free distance requirement. This greatly limits the application scenarios of this high detection distance sensor.

[0004] Meanwhile, if the sensor is directly installed at the location of the mechanical equipment, it will be exposed to the external environment and face risks such as wind, sun and foreign object collisions, which can easily cause damage. If a protective box is configured for the sensor, the existing protective box made of metal can provide sufficient protection, but the metal material can trigger interference problems for the sensor, further exacerbating the contradiction of insufficient installation space. If a non-metallic protective box is used, its protective performance cannot meet the needs of use in harsh industrial environments.

[0005] To solve the above problems, relevant technicians attempted to reduce interference by shielding the surrounding metal. However, this method requires a large amount of electromagnetic shielding material and is extremely sensitive to the position and distance of the surrounding metal. It also causes the sensor detection distance to decrease by more than 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 solution of this application was proposed. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing TURCKNI100U-K90SR-VP4X2 type inductive sensors, which suffer from large interference-free distances around the sensor, high installation space requirements, and difficulties in protection, thus limiting their application. This invention provides an anti-interference installation structure for inductive sensors, achieving the following objectives:

[0007] 1. The interference-free distance around the sensor metal has been reduced from 200mm to 18.5mm to meet the installation requirements in confined spaces;

[0008] 2. Ensure that the vertical (upward) detection distance of the sensor does not decrease, maintaining the rated detection performance of 100mm;

[0009] 3. Provides sensors with sealing, anti-aging, and impact protection, adapting to harsh industrial environments;

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

[0011] The technical solution adopted in this invention is as follows:

[0012] An anti-interference mounting structure for an inductive sensor includes a sensor body, an electromagnetic shielding assembly, and a metal protective box.

[0013] The sensor body is a TURCKNI100U-K90SR-VP4X2 type inductive sensor with a rated detection distance Sn of 100mm.

[0014] The electromagnetic shielding assembly includes two electromagnetic shielding films, each measuring 25mm × 10mm × 0.5mm. The two electromagnetic shielding films are respectively attached to the left and right sides above the sensor body, and the length direction of the electromagnetic shielding films is consistent with the length direction of the sensor body.

[0015] The metal protective box is an open-top box structure. Its internal cavity size is adapted to the overall size of the sensor body and electromagnetic shielding components to accommodate them. The top of the metal protective box is detachably connected to an opaque anti-aging plastic cover made of polycarbonate (PC) or acrylonitrile-butadiene-styrene copolymer (ABS). One end of the metal protective box has a through hole for wire connection, and a detachable and movable sealing sleeve made of oil-resistant rubber is installed inside the through hole. The bottom inner wall of the metal protective box has at least two blind holes for sensor mounting, the diameter of which is adapted to the mounting screw holes on the bottom of the sensor body. The bottom outer wall of the metal protective box has at least two equipment fixing guide holes, each of which has a waterproof sealing ring, and the axis of the equipment fixing guide hole is parallel to the axis of the sensor mounting blind hole.

[0016] Furthermore, the electromagnetic shielding film is a ferrite absorbing film with a permeability μ≥800μ0 (μ0 is the permeability of air) and an electromagnetic wave absorption efficiency ≥85% in the frequency range of 100kHz-1MHz.

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

[0018] Furthermore, the opaque anti-aging plastic cover is connected to the metal protective box by screws, and the edge of the cover is equipped with a sealing strip made of ethylene propylene diene monomer (EPDM) rubber.

[0019] Furthermore, the diameter of the through hole for connecting the wire is the outer diameter of the sensor body wire + 0.5-1mm, and the inner hole of the sealing sleeve is provided with annular protrusions that are adapted to the wire, with 2-3 annular protrusions.

[0020] Furthermore, the depth of the sensor mounting blind hole is 5-8mm, and the inner wall of the blind hole is provided with internal thread. 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] Furthermore, the diameter of the equipment fixing guide hole is the outer diameter of the fastening screw + 0.2-0.3mm, the cross-section of the waterproof sealing ring is O-shaped, and the inner diameter of the sealing ring is adapted to the outer diameter of the fastening screw, while the outer diameter is adapted to the diameter of the equipment fixing guide hole.

[0022] This invention also discloses the application of the above-mentioned anti-interference installation structure in a roller conveyor, specifically in the following manner:

[0023] The sensor body is fixed to the sensor mounting blind hole on the bottom inner wall of the metal protective box with screws, ensuring that the detection end of the sensor body is facing upwards, and the wires are passed out from the wire connection through hole at one end of the metal protective box. The wires and the through hole are sealed by the sealing sleeve.

[0024] An opaque, anti-aging plastic cover is fixed to the top of the metal protective box with screws, which presses the sealing strip to achieve a seal on the protective box.

[0025] The entire mounting structure is fixed to the frame of the roller conveyor by passing fastening screws through the equipment fixing guide holes at the bottom of the metal protective box, with the detection end of the sensor body facing directly below the conveyor roller, and the detection distance (the distance from the sensor detection end to the roller surface) being 100mm.

[0026] When the power supply to the sensor body is turned on and the operating speed of the conveyor is adjusted (0.5-2m / 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 protective box and the sensor body is 18.5mm, with no interference.

[0027] The working principle of this invention is as follows: Based on the electromagnetic induction principle of inductive sensors, this invention achieves the dual functions of anti-interference and protection through the coordinated design of local electromagnetic shielding and a metal protective box. The specific working principle is as follows:

[0028] The core working principle of an inductive sensor is as follows: When the sensor body is energized, its internal coil generates an alternating current, which in turn forms an alternating magnetic field. When a metal object enters the range of this alternating magnetic field, eddy currents are induced on the surface of the metal object. The reverse alternating magnetic field generated by the eddy currents weakens the original alternating magnetic field of the sensor. By detecting the change in the original alternating magnetic field (such as the change in inductance), the sensor can determine whether a metal object is approaching.

[0029] The anti-interference principle of the electromagnetic shielding component: The electromagnetic shielding film (ferrite absorbing film) attached to both sides above the sensor body can absorb part of the alternating magnetic field radiated by the sensor in all directions. Since the shielding film is only set on both sides above the sensor, it will not affect the upward (detection direction) alternating magnetic field radiation of the sensor. Therefore, the sensor's detection capability (detection distance, sensitivity) of the metal object above it is not attenuated. At the same time, the magnetic field absorbed by the shielding film cannot reach the inner wall of the metal protective box, so that the inner wall of the metal protective box (the surrounding metal) will not induce eddy currents, thereby eliminating the interference of the surrounding metal to the sensor and greatly shortening the interference-free distance (from 200mm to 18.5mm).

[0030] The protective principle of the metal protective box: The metal protective box is made of 304 stainless steel, which can resist the collision of foreign objects and the corrosion of dust. The opaque anti-aging plastic cover (PC / ABS material) on the top has excellent anti-ultraviolet and anti-aging properties, preventing direct sunlight from aging the sensor. The sealing strip on the edge of the cover, the sealing sleeve at the wire through hole, and the waterproof sealing ring in the equipment fixing guide hole together form a sealing structure to prevent rainwater, oil and other contaminants from entering the protective box, ensuring that the sensor is in a dry and clean working environment. The sensor mounting blind hole and the equipment fixing guide hole at the bottom respectively realize the stable connection between the sensor and the protective box, and between the protective box and the equipment, ensuring the stability of the installation structure.

[0031] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0032] 1. An anti-interference mounting structure for an inductive sensor, which reduces the interference-free distance of the metal around the sensor from the officially required 200mm to 18.5mm by attaching electromagnetic shielding films of a specific size (25×10×0.5mm) to both sides above the sensor, which is only 9.25% of the original distance. This successfully solves the core problem that many small-space equipment in the machinery industry (such as small conveyor rollers and precision machine tools) cannot be adapted to this high detection distance sensor.

[0033] 2. In this invention, the electromagnetic shielding film only absorbs the redundant magnetic field radiated by the sensor in all directions, without affecting the magnetic field radiation in the vertical direction (detection direction). According to actual measurements, the vertical detection distance of the sensor still maintains the rated value of 100mm, and the attenuation rate is ≤5%. This fully preserves the core advantage of the sensor in "adapting to error scenarios with a large detection range" and avoids the drawback of the traditional full shielding solution that causes the detection distance to decrease by more than 70%.

[0034] 3. In this invention, a metal protective box (304 / 316 stainless steel) is combined with an opaque anti-aging plastic cover (PC / ABS), EPDM / fluororubber sealing strips, oil-resistant rubber sealing sleeves, and O-ring waterproof sealing rings to construct an IP65-IP68 level sealing protection system, which can resist rain, oil, dust, ultraviolet rays and minor impacts. This solves the problem of easy damage when the sensor is directly installed, and extends its service life to 2-3 times that of the original solution.

[0035] 4. In this invention, the installation structure is not only applicable to roller conveyor equipment, but can also be extended to scenarios requiring metal detection such as chain conveyors, elevators, and stamping equipment. It has significant advantages, especially in small and medium-sized equipment with limited installation space, enabling equipment that could not be used due to insufficient space (such as micro conveyor lines for electronic components and precision assembly machines for automotive parts) to be compatible with this high detection distance sensor.

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

[0037] 6. In this invention, there is no need to carry out large-scale structural modifications to existing equipment (such as expanding the installation space or changing the equipment model) to adapt to the sensor. It can be directly fixed by this installation structure, reducing the modification cost by 60%-80%, which is especially suitable for the equipment upgrade needs of small and medium-sized enterprises.

[0038] 7. In this invention, the sealed protection design reduces the frequency of sensor replacement due to damage or moisture. At the same time, components such as the cover plate and sealing sleeve can be disassembled and installed separately, and the entire protective box does not need to be disassembled during maintenance. The maintenance time is shortened to 1 / 3 of the original solution, and the annual maintenance cost is reduced by more than 50%. Attached Figure Description

[0039] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort, wherein:

[0040] Figure 1 This is a structural schematic diagram of the present invention (the opaque anti-aging plastic cover is in a transparent state).

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

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

[0043] Figure 4 This is a three-dimensional diagram of the structure of the present invention (the opaque anti-aging plastic cover is also in a transparent state).

[0044] Figure 5 This is a three-dimensional diagram of the structure of the present invention applied to a transmission device;

[0045] The markings in the diagram are: 1-Sensor body, 2-Metal protective box, 3-Electromagnetic shielding film, 4-Opaque anti-aging plastic cover, 5-Through hole, 6-Sensor mounting blind hole, 7-Mounting screw hole, 8-Equipment fixing guide hole. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0047] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0048] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0049] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0050] Example 1

[0051] This invention provides an anti-interference mounting structure for an inductive sensor, such as... Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown, it includes a sensor body 1, an electromagnetic shielding assembly, and a metal protective box 2;

[0052] The sensor body 1 is a TURCKNI100U-K90SR-VP4X2 type inductive sensor with a rated detection distance Sn of 100mm;

[0053] The electromagnetic shielding assembly includes two electromagnetic shielding films 3, each with a size of 25mm×10mm×0.5mm. 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 box structure with an open top. The internal cavity size is adapted to the overall size of the sensor body 1 and the electromagnetic shielding assembly to accommodate the sensor body 1 and the electromagnetic shielding assembly. An opaque anti-aging plastic cover 4 is detachably connected to the top of the metal protective box 2. One end of the metal protective box 2 has a through hole 5 for wire connection. A detachable and movable sealing sleeve is provided in the through hole 5. The bottom inner wall of the metal protective box 2 has at least two sensor mounting blind holes 6. The diameter of the sensor mounting blind holes 6 is adapted to the mounting screw holes 7 at the bottom of the sensor body 1. The bottom outer wall of the metal protective box 2 has at least two equipment fixing guide holes 8. Each equipment fixing guide hole 8 is provided with a waterproof sealing ring, and the axis of the equipment 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 absorbing film with a permeability μ≥800μ0 and an electromagnetic wave absorption efficiency ≥85% in the frequency range of 100kHz-1MHz.

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

[0057] The opaque anti-aging plastic cover 4 is made of polycarbonate or acrylonitrile-butadiene-styrene copolymer, and the opaque anti-aging plastic cover 4 is connected to the metal protective box 2 by screws. The edge of the opaque anti-aging plastic cover 4 is provided with a sealing strip, and the sealing strip is made of EPDM rubber.

[0058] The sealing strip has a cross-sectional size of 2-4mm × 2-4mm, and the mating surface between the opaque anti-aging plastic cover 4 and the metal protective box 2 is coated with waterproof sealant.

[0059] The diameter of the through hole 5 is the outer diameter of the wire of the sensor body 1 + 0.5-1mm. The inner hole of the sealing sleeve is provided with annular protrusions that are adapted to the wire. There are 2-3 annular protrusions and the height of the annular protrusions is 0.5-1mm.

[0060] The depth of the sensor mounting blind hole 6 is 5-8mm, and the inner wall of the sensor mounting blind hole 6 is provided with 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, which is M4 or M5.

[0061] The diameter of the equipment fixing guide hole 8 is the outer diameter of the fastening screw + 0.2-0.3mm. The cross-section of the waterproof sealing ring is O-shaped. The inner diameter of the waterproof sealing ring is adapted to the outer diameter of the fastening screw, and the outer diameter of the waterproof sealing ring is adapted to the diameter of the equipment fixing guide hole 8. The material of the waterproof sealing ring is EPDM rubber, fluororubber, or silicone rubber.

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

[0063] The specific implementation method of this embodiment is: an installation structure suitable for lightweight roller conveyor equipment.

[0064] This embodiment is for a lightweight roller conveyor (such as an electronic component production line) that conveys a weight of ≤50kg. The specific structural parameters are as follows:

[0065] Sensor body: TURCKNI100U-K90SR-VP4X2 type, length 60mm, width 30mm, height 25mm;

[0066] Electromagnetic shielding film: Ferrite absorbing film, dimensions 25mm×10mm×0.5mm, permeability 1000μ0, absorption efficiency 90% at 100kHz frequency;

[0067] Metal protective box: made of 304 stainless steel, with a wall thickness of 1.5mm and an internal cavity size of 62mm×32mm×26mm (length×width×height). The bottom inner wall has two blind holes for mounting M4 sensors (5mm deep) and the bottom outer wall has two guide holes for fixing equipment (6.3mm in diameter). The guide holes are equipped with O-ring waterproof seals (material EPDM).

[0068] Cover: Opaque anti-aging cover made of PC material, 3mm thick, with EPDM sealing strips (2mm×2mm cross-section) at the edges, and connected to the protective box by 4 M3 screws;

[0069] Through-hole for wires: 8mm in diameter (compatible with 7.5mm outer diameter of sensor wires), the sealing sleeve is made of oil-resistant rubber, and the inner hole has two annular protrusions (0.5mm in height).

[0070] Application method: The mounting structure is fixed to the frame of the conveyor equipment, with the sensor detection end 100mm from the roller surface and the conveying speed 0.5m / s. Testing showed that the sensor detection accuracy was 100%, the interference-free distance around the sensor was 18.5mm, the protective box showed no water ingress under IP65 conditions, and it operated continuously for 3000 hours without failure.

[0071] Example 2

[0072] This invention provides an anti-interference mounting structure for an inductive sensor, such as... Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown, the specific implementation method of this embodiment is as follows:

[0073] Installation structure suitable for medium-sized roller conveyors

[0074] This embodiment is for medium-sized roller conveyors (such as those used in automotive parts production lines) that can convey weights of 50-200 kg. Specific structural parameters are as follows:

[0075] Sensor body: TURCKNI100U-K90SR-VP4X2 type, with the same dimensions as in Example 1;

[0076] Electromagnetic shielding film: Ferrite absorbing film, dimensions 25mm×10mm×0.5mm, permeability 1200μ0, absorption efficiency 92% at 500kHz;

[0077] Metal protective box: made of 304 stainless steel, with a wall thickness of 2mm and an internal cavity size of 62mm×32mm×26mm. The bottom inner wall has two blind holes for mounting M5 sensors (8mm deep) and the bottom outer wall has two guide holes for fixing equipment (8.3mm in diameter). The guide holes are equipped with O-ring waterproof seals (made of fluororubber).

[0078] Cover: Opaque anti-aging cover made of ABS material, 4mm thick, with fluororubber sealing strips (3mm×3mm cross-section) at the edges, and connected to the protective box by 4 M4 screws;

[0079] Through-hole for wires: 9mm diameter (compatible with 8mm outer diameter of sensor wires), the sealing sleeve is made of fluororubber, and the inner hole has 3 annular protrusions (0.8mm in height).

[0080] Application method: The mounting structure is fixed to the reinforcing beam of the conveyor frame, with the sensor detection end 100mm from the roller surface and the conveying speed 1.5m / s. Testing showed that the sensor detection accuracy was 100%, the interference-free distance around the sensor was 18.5mm, the protective box showed no water or oil ingress under IP67 conditions, it operated continuously for 5000 hours without failure, and it could withstand slight vibration (vibration frequency 50Hz, amplitude 0.1mm).

[0081] Example 3

[0082] This invention provides an anti-interference mounting structure for an inductive sensor, such as... Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown, the specific implementation method of this embodiment is as follows:

[0083] Installation structure suitable for outdoor roller conveyor equipment

[0084] This embodiment is for outdoor roller conveyor equipment (such as building material production lines), and the specific structural parameters are as follows:

[0085] Sensor body: TURCKNI100U-K90SR-VP4X2 type, with the same dimensions as in Example 1;

[0086] Electromagnetic shielding film: Ferrite absorbing film, dimensions 25mm×10mm×0.5mm, permeability 1500μ0, absorption efficiency 95% at 1MHz frequency;

[0087] Metal protective box: 316 stainless steel (corrosion resistant), wall thickness 2mm, internal cavity size 62mm×32mm×26mm, bottom inner wall has 2 M4 sensor mounting blind holes (6mm deep), bottom outer wall has 4 M6 equipment fixing guide holes (6.3mm in diameter), and the guide holes are equipped with double O-ring waterproof sealing rings (made of silicone rubber).

[0088] Cover: Opaque cover made of PC with anti-UV coating, 5mm thick, with silicone rubber sealing strips (4mm×4mm cross-section) at the edges, connected to the protective box by 6 M3 screws, and the mating surfaces of the cover and the protective box are coated with waterproof sealant;

[0089] Through-hole for wires: 10mm in diameter (fits sensor wires with an outer diameter of 9mm), the sealing sleeve is made of silicone rubber, the inner hole has 3 annular protrusions (1mm in height), and a metal waterproof connector (model PG9) is provided on the outside of the through-hole.

[0090] Application method: The mounting structure is fixed inside the rainproof cover of the outdoor conveyor equipment, with the sensor detection end 100mm from the roller surface and the conveying speed 2m / s. Testing showed that the sensor detection accuracy was 100%, the interference-free distance around the device was 18.5mm, the protective box showed no water ingress under IP68 conditions (immersion in 1 meter of water for 30 minutes), and it can withstand temperature changes from -30℃ to 80℃, operating continuously for 8000 hours without failure.

[0091] Experimental Example 1

[0092] I. Basic Experimental Conditions

[0093] Experimental samples: TURCKNI100U-K90SR-VP4X2 type sensor (n=5), 304 stainless steel protective box (wall thickness 1.8mm, distance between inner wall and sensor 18.5mm), ferrite absorbing film (25mm×10mm×0.5mm, μ=1200μ0).

[0094] Interference source: Q235 steel block (100mm×100mm×20mm, simulating metal parts of industrial equipment);

[0095] Testing equipment: spectrum analyzer (Agilent N9320B, 100kHz-1MHz), laser rangefinder (accuracy ±0.1mm), high and low temperature test chamber (-40℃~100℃).

[0096] Control group: ① Unshielded solution (sensor directly exposed); ② Fully shielded solution (sensor surrounded by ferrite film of the same specification).

[0097] II. Core Experimental Data and Analysis

[0098] 1. Interference-free distance verification experiment

[0099] Solution Type Interference source material Minimum distance for accidental triggering (mm) Standard deviation (mm) Reduction rate compared to official requirement (200mm) This invention provides partial shielding Q235 steel 18.5 ≤0.3 90.75% Unshielded solution Q235 steel 50.2 ≤0.5 74.90% Full shielding solution Q235 steel 22.1 ≤0.4 88.95% Experimental results: Based on the criterion of three consecutive false triggers of the sensor (output signal when no metal is detected), the interference-free distance of the present invention is only 18.5mm, which is better than the fully shielded solution and far lower than the official requirement of 200mm, meeting the installation requirements in confined spaces.

[0100] Table 1

[0101] 2. Distance attenuation rate detection experiment

[0102] Solution Type Test frequency (kHz) Rated detection distance (mm) Actual detection distance (mm) Attenuation rate Detection accuracy (response time for metal block to pass) This invention provides partial shielding 100 100 99.8 0.2% ≤10ms This invention provides partial shielding 500 100 98.5 1.5% ≤12ms This invention provides partial shielding 1000 100 95.3 4.7% ≤15ms Full shielding solution 100 100 28.1 71.9% ≤30ms Unshielded solution 100 100 97.2 2.8% ≤11ms Experimental results show that within the range of 100kHz-1MHz (the sensor's operating frequency), the attenuation rate of the proposed solution is always ≤5%, and the detection response speed is close to that of the unshielded solution; while the fully shielded solution, due to blocking the magnetic field in the detection direction, has an attenuation rate of over 70%, completely losing its advantage of high detection distance.

[0103] Table 2

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

[0105] Test frequency band (kHz) Ferrite membrane absorption rate (%) Ferrite film reflectance (%) Metal protective box shielding attenuation (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 results show that by adopting a "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 protective box (attenuation of more than 42dB). The overall shielding effectiveness exceeds 50dB, which is far higher than the Class B requirement (≤30dB) for electromagnetic compatibility (EMC) of industrial equipment.

[0106] Table 3

[0107] 4. Supplementary Environmental Adaptability Experiment

[0108] Environmental conditions Experiment duration (h) Change in detection distance (mm) False alarm rate Sealing performance (IP rating) -30℃~80℃ high and low temperature cycling 1000 95.3→94.8（-0.5%） 0% IP68 (No water ingress) Vibration of 10-500Hz (amplitude 0.5mm) 500 95.3→95.1（-0.2%） 0% The sealing strip did not fall off. Soaked in oil (No. 5 machine oil) 200 95.3→95.0（-0.3%） 0% The sealing sleeve does not swell. Experimental results show that the structural stability and shielding performance did not significantly decrease under harsh industrial environments, verifying the reliability of the 304 stainless steel protective box and EPDM rubber seals.

[0109] Table 4

[0110] III. Technical Mechanism Verification Conclusions

[0111] Local shielding effectiveness: Ferrite films are attached only to the two sides above the sensor, which can directionally absorb redundant magnetic fields from all sides (absorption rate ≥85%), avoid induced eddy currents in the metal protective box, and shorten the 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 unblocked, the detection distance attenuation rate is ≤5%, and the rated detection capability of 100mm is fully retained;

[0113] Synergistic protection advantages: The metal protective box and shielding film form a dual system of "physical protection + electromagnetic shielding", with a shielding effectiveness of over 50dB, while meeting the IP68 sealing and anti-aging requirements.

[0114] The above description is merely a preferred embodiment or experimental example of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An anti-interference mounting structure for an inductive sensor, characterized in that: Includes the sensor body (1), electromagnetic shielding components and metal protective box (2); The sensor body (1) is a TURCKNI100U-K90SR-VP4X2 type inductive sensor with a rated detection distance Sn of 100mm; The electromagnetic shielding assembly includes two electromagnetic shielding films (3), each of which has a size of 25mm×10mm×0.5mm. 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). The metal protective box (2) is a box structure with an open top. The internal cavity size is adapted to the overall size of the sensor body (1) and the electromagnetic shielding component, and is used to accommodate the sensor body (1) and the electromagnetic shielding component. The top of the metal protective box (2) is detachably connected to an opaque anti-aging plastic cover plate (4). One end of the metal protective box (2) is provided with a through hole (5) for wire connection. The through hole (5) is provided with a detachable and movable sealing sleeve 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 diameter of the sensor mounting blind holes (6) is adapted to the mounting screw holes (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 equipment fixing guide holes (8). Each equipment fixing guide hole (8) is provided with a waterproof sealing ring, and the axis of the equipment fixing guide hole (8) is parallel to the axis of the sensor mounting blind hole (6).

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

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

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

5. The anti-interference mounting structure for an inductive sensor according to claim 4, characterized in that: The cross-sectional dimensions of the sealing strip are 2-4mm × 2-4mm, and the mating surfaces of the opaque anti-aging plastic cover (4) and the metal protective box (2) are coated with waterproof sealant.

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

7. The 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 5-8mm, 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.

8. The anti-interference mounting structure for an inductive sensor according to claim 1, characterized in that: The diameter of the device fixing guide hole (8) is the outer diameter of the fastening screw + 0.2-0.3mm. The fastening screw is used to install the metal protective box (2) onto 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 adapted to the outer diameter of the fastening screw. The outer diameter of the waterproof sealing ring is adapted to the diameter of the device fixing guide hole (8). The material of the waterproof sealing ring is EPDM rubber, fluororubber or silicone rubber.

9. An anti-interference mounting structure for an inductive sensor according to any one of claims 1-8, characterized in that: The distance between the inner wall of the metal protective 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, with a detection distance attenuation rate of ≤5%.

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