Anti-interference structure of mechanical wave intensity measuring ambient noise device

Abstract

The utility model provides a kind of anti-interference structure of mechanical wave intensity measurement environmental noise device belongs to anti-interference structure technical field, and the anti-interference structure of mechanical wave intensity measurement environmental noise device wherein, including: annular inertia pendulum, three-point ball head hinge group, device main body and limit protection cover;Annular inertia pendulum is the solid metal body of whole circular ring, and its outer peripheral surface is continuous smooth surface;Three-point ball head hinge group is made of three ball head hinges;Device main body is the disc-like shell with radial flange being equipped in bottom outer edge, and the lower surface of flange is equipped with three ball socket socket, respectively with the ball head of ball head rod Form swingable ball joint;The limit protection cover is inverted bowl-shaped shell;Centroid of annular inertia pendulum is below ball head hinge group articulation plane, to cut off the transmission path of ground microvibration to measurement device main body in pure mechanical way, and prevent low-frequency false vibration signal from mixing into mechanical wave intensity measurement result.

Description

Technical Field

[0001] This utility model belongs to the field of anti-interference structure technology, specifically, it relates to an anti-interference structure for an environmental noise device for measuring mechanical wave intensity. Background Technology

[0002] In the field of mechanical wave intensity measurement, environmental noise is often considered as an interference source other than the "object being measured." A mechanical wave intensity measurement environmental noise device refers to a device used at factory boundaries, along rail transit lines, or in large power stations to simultaneously capture airborne sound waves and structural vibration signals using sound pressure level sensors, accelerometers, or strain gauge vibration pickups. These signals are then converted into a unified "mechanical wave intensity" index to evaluate the impact of equipment radiated noise on the surrounding environment. To ensure that the measured data accurately reflects the source of concern, such devices must have an integrated "interference-proof structure"—a mechanical isolation system that excludes irrelevant inputs such as ground micro-vibrations, support frame shaking, wind and rain impacts, and electromagnetic stray emissions.

[0003] Traditional anti-interference structures generally employ a "rigid bracket + elastic gasket" approach: the sensor is first fixed to the top of a lightweight alloy or carbon fiber support rod, the bottom of the rod is connected to the foundation via several rubber gaskets, and then a windproof cover secures the entire sensor. Designers hope that the rubber gaskets provide low-frequency vibration isolation, and the windproof cover isolates airflow noise, thereby obtaining a "clean" signal. However, in actual operation, the static compression of the rubber gasket changes continuously with temperature aging, and the vibration isolation frequency drifts, causing the low-frequency ground vibration that should have been isolated to still be transmitted upward along the support rod. The lightweight support rod itself has a small mass and weak inertial reference, and will sway as a whole when it encounters instantaneous impact, forming additional acceleration, which is recorded by the sensor as a "valid signal". Although the windproof cover can block wind and dust, it becomes a new sound reflector. The reverberation inside the cover superimposed and acted back on the sensor, causing the high-frequency components to be artificially amplified. More seriously, the entire support system has a local point-to-surface contact with the foundation. When heavy vehicles pass by or the equipment starts and stops, the foundation surface undergoes micron-level elastic fluctuations. The support system is repeatedly bent like a "seesaw". The bending wave is rapidly transmitted to the sensor in bending mode, forming a false "pseudo-mechanical wave" that overlaps with the frequency band of the real environmental noise but is phase-independent. Utility Model Content

[0004] In view of this, the present invention provides an anti-interference structure for an environmental noise device for measuring mechanical wave intensity, which cuts off the transmission path of ground micro-vibration to the main body of the measuring device in a purely mechanical manner, thereby preventing low-frequency false vibration signals from mixing into the mechanical wave intensity measurement results.

[0005] This utility model is implemented as follows:

[0006] This utility model provides an anti-interference structure for an environmental noise measurement device for mechanical wave intensity measurement, comprising: a ring-shaped inertial pendulum, a three-point ball-head hinge assembly, a device body, and a limiting protective cover; the ring-shaped inertial pendulum is a solid metal body in the shape of a ring, with a continuous smooth curved surface on its outer circumference and a radially inwardly extending annular support on its inner circumference; the three-point ball-head hinge assembly consists of three ball-head hinges, with the ball sockets of each ball-head hinge fixed at equal intervals along the circumference to the upper surface of the annular support, and the ball-head rods extending upward; the device body has a bottom outer edge with The device comprises a disc-shaped shell with radial flanges. The lower surface of the flanges has three ball joints that form swingable ball joints with the ball head of the ball joint, allowing the main body of the device to be suspended and supported above the annular pendulum. The limiting protective cover is an inverted bowl-shaped shell, with its lower end rigidly connected to the outer periphery of the annular pendulum and its upper end having a circular opening at the center for the main body of the device to extend upward. An annular gap is maintained between the opening and the main body of the device. The center of mass of the annular pendulum is located below the hinge plane of the ball joint assembly, forming a downward pendulum-type inertial stabilization structure.

[0007] The diameter of the circular opening at the top of the limiting protective cover is 8–12 mm larger than the outer diameter of the corresponding section of the device body, so that an equal-width annular gap is formed between the opening and the device body. This gap remains open in both the radial and axial directions, allowing the device body to make conical swinging movements within ±3° relative to the protective cover, while preventing fingers or tools from being inserted inside.

[0008] Based on the above technical solution, the anti-interference structure of the mechanical wave intensity measurement environmental noise device of this utility model can be further improved as follows:

[0009] The outer contour of the cross-section of the annular inertial pendulum is an arc surface, and the inner contour is a stepped surface. The lower section of the stepped surface protrudes inward to form the annular support platform, and the top of the stepped surface contracts inward to form a limiting stop, which is used to limit the maximum swing angle of the device body relative to the annular inertial pendulum.

[0010] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the outer arc of the pendulum cross section and the inner step support and the edge are integrated into the contour, so that the flange is mechanically limited once it touches the edge during swing. This not only prevents the ball head from detaching due to excessive swing angle, but also concentrates the return torque at the root of the step, making it less prone to loosening during long-term operation. The entire limiting function is achieved by casting the contour alone, without the need for additional parts, resulting in a very simple structure and high reliability.

[0011] Furthermore, the surface of the ball joint is covered with an elastic damping sleeve, the outer diameter of which is smaller than the inner diameter of the ball socket, to provide flexible damping buffer when the ball joint hinge swings.

[0012] The elastic damping sleeve is a silicone rubber tube with a wall thickness of 1–1.5 mm and an inner diameter that is 0.2–0.3 mm smaller than the outer diameter of the club head. It uses an interference fit to cover the entire club head and can provide 0.5–1 N·mm / (°) torsional damping when the club head swings.

[0013] Furthermore, the lower surface of the flange of the main body of the device is provided with a downwardly extending annular retaining ring. The annular retaining ring is located outside the ball socket and forms a vertical gap with the upper surface of the annular support platform to prevent foreign objects from entering the ball joint hinge area.

[0014] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the annular retaining ring added to the lower surface of the flange of the main body of the device surrounds the ball socket and forms a labyrinth-like lateral gap with the support surface, which can prevent dust and droplets from entering the ball joint area radially, keep the grease clean, and thus maintain a low friction and low wear state for a long time. Moreover, the retaining ring is integrally formed with the main body and does not occupy additional axial space.

[0015] Furthermore, a flexible sealing ring is embedded in the inner edge of the circular opening of the limiting protective cover. The inner circumference of the flexible sealing ring slides in cooperation with the outer circumferential surface of the device body, which is used to close the internal space while maintaining the degree of freedom of swing.

[0016] The flexible sealing ring is made of nitrile rubber O-ring with a Shore A hardness of 30-40. Its inner diameter is 1-1.5 mm smaller than the outer diameter of the corresponding section of the device body. It is embedded in the rectangular groove of the limit protection cover opening and maintains a sliding seal with the outer circumference of the device body.

[0017] Furthermore, the bottom surface of the annular inertial pendulum is provided with evenly distributed hemispherical support feet, and the spherical part of the support feet is used to make point contact with the ground to reduce the transmission of ground micro-vibrations to the annular inertial pendulum through surface contact.

[0018] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the pendulum bottom surface is evenly distributed with hemispherical support feet, and the three spherical surfaces make point contact with the ground, changing the original surface contact into theoretical point contact, cutting off the shear transmission path of the ground's lateral micro-vibration, and the spherical surface of the support feet can adapt to unevenness, without the need for additional leveling shims, and can be used on site, simplifying the deployment process.

[0019] Furthermore, the top surface of the main body of the device is provided with an upwardly protruding mounting column, and the outer peripheral surface of the mounting column is a conical surface, which is used to form a conical self-centering connection with an external measuring device.

[0020] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the conical mounting column on the top surface of the main body of the device automatically centers and wedges the external measuring device when it is inserted, eliminating the additional stress caused by uneven bolt preload in traditional flange connections, ensuring that the sensor axis is coaxial with the center of the pendulum, thereby avoiding additional bending moment from being transmitted to the measuring element through the housing, improving signal purity, and installation only requires one step of "insertion-light pressure".

[0021] Furthermore, the annular pendulum has an annular cavity inside, and the cross-section of the annular cavity is arc-shaped, which is used to increase the mass of the pendulum while keeping the external dimensions unchanged.

[0022] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the arc-shaped cavity inside the pendulum concentrates the mass on the outer ring while keeping the outer dimensions unchanged, increases the moment of inertia, and enhances the pendulum's resistance to low-frequency vibration. The cavity structure reduces the amount of material used, reduces the overall weight and cost, and achieves the effect of "heavy but not bulky". It is formed in one piece during casting and does not require subsequent counterweight.

[0023] Furthermore, the ball joint of the three-point ball joint assembly is fixed to the annular support by a radially adjustable screw. The axis of the radially adjustable screw extends radially along the annular inertial pendulum, and is used to adjust the radial position of the ball joint assembly relative to the center of the annular inertial pendulum, so as to change the suspension center of the main body of the device.

[0024] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the ball joint seat is fixed to the support platform by a radially adjustable screw, and the center of the ball joint can be moved slightly after assembly, thereby changing the static balance position of the main body of the device. When the ground on site is tilted for a long time or the center of gravity is offset, it can be quickly adjusted back to the neutral position without disassembling the main body, ensuring that the axis of symmetry of the pendulum is consistent with the direction of gravity and maintaining the best vibration isolation posture. The adjustment process only requires tightening and loosening the screw and sliding the seat, which can be operated by a single person.

[0025] Furthermore, the inner wall of the limiting protective cover is attached with a sound-absorbing layer, which has a wavy porous structure to absorb internal mechanical noise and reduce the interference of sound wave reflection on the measuring device.

[0026] The sound-absorbing layer is made of 2–4 mm thick open-cell melamine foam plastic, with the surface hot-pressed into a continuous sinusoidal wave shape, with a peak height of 4–6 mm and a wave pitch of 8–10 mm. It is then attached to the inner wall of the limiting protective cover with flame-retardant acrylic pressure-sensitive adhesive.

[0027] Compared with the prior art, the beneficial effect of the anti-interference structure of the mechanical wave intensity measurement environmental noise device provided by this utility model is that the anti-interference structure proposed by this utility model integrates the three elements of "mass-hinge-limit" into a coaxial circular space, so that there is no longer any rigid short path between the main body of the device and the foundation. The circular inertial pendulum naturally possesses self-stabilizing characteristics due to its concentrated mass and center of mass being far below the hinge plane. When a micro-vibration occurs in any direction on the ground, the pendulum first follows slowly in a "hysteresis" manner, while the main body of the device maintains its original state due to inertia. False vibrations are "cut off" at the hinge interface, and the sensor only detects the real ambient sound waves. The three-point ball joint hinge changes the traditional surface contact, resulting in extremely low frictional damping. It does not amplify high-frequency jitter and avoids performance drift caused by rubber aging. The flexible seal between the limiting protective cover and the main body, along with the annular retaining ring, forms a two-way isolation, preventing external airflow and dust from entering the ball joint area. The internal lubricating grease remains clean over a long period, ensuring the hinge maintains constant damping characteristics throughout its lifespan. At the same time, the wave-shaped sound-absorbing layer attached inside the cover absorbs potential mechanical noise multiple times, eliminating the risk of the cover itself becoming a secondary sound source. The adjustable ball socket allows for fine-tuning of the suspension center on-site without disassembling the main body. Even if the foundation experiences slow settlement or long-term tilting, it can be readjusted within minutes. By restoring the neutral position and ensuring that the pendulum's axis of symmetry is aligned with the direction of gravity, the entire system requires no electronic servo or external power supply, achieving "maintenance-free after installation" through purely mechanical means. Since all functional components are stacked along the same axis of rotation, forming a flat, disc-like shape, they can be stacked vertically during transport. On-site, simply placing it on a hardened surface automatically creates three-point support, eliminating the need for anchor bolts or leveling shims. Deployment time is reduced from several hours to just a few minutes, significantly lowering preparation costs before on-site measurements. More importantly, this structure integrates four functions—vibration isolation, limiting, sealing, and sound absorption—within just the pendulum and protective cover, drastically reducing the number of parts and simplifying the assembly process to three steps: "insertion—cover fastening—locking." This reduces the accumulation of manufacturing errors and minimizes potential failure points, providing the mechanical wave intensity measurement device with a self-stabilizing, self-sealing, and self-silencing purely mechanical anti-interference platform for the first time. This provides a reliable hardware foundation for environmental noise enforcement, enterprise self-inspection, and scientific research comparison. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A diagram of an infinitely positioned protective cover for an anti-interference structure of an environmental noise measurement device for mechanical wave intensity measurement.

[0030] Figure 2 A cross-sectional view of the anti-interference structure of an environmental noise measurement device for mechanical wave intensity measurement;

[0031] Figure 3 for Figure 2 Enlarged view of section A in the middle;

[0032] The attached diagram lists the components represented by each number as follows:

[0033] 10. Circular inertial pendulum; 11. Circular support platform; 12. Support leg; 20. Three-point ball joint hinge assembly; 30. Limiting protective cover; 40. Main body of the device; 41. Mounting column. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0035] like Figures 1-3 The diagram shown is an example of the anti-interference structure of an environmental noise measurement device for mechanical wave intensity provided by this utility model, including: a ring-shaped inertial pendulum 10, a three-point ball joint hinge assembly 20, a device body 40, and a limiting protective cover 30; the ring-shaped inertial pendulum 10 is a solid metal body in the shape of a ring, with a continuous smooth curved surface on its outer circumference and a radially inwardly extending annular support 11 on its inner circumference; the three-point ball joint hinge assembly 20 consists of three ball joints, with the ball sockets of each ball joint fixed at equal intervals along the circumference to the upper surface of the annular support 11, and the ball joint rods extending upward; the device body 40... 0 is a disc-shaped shell with a radial flange on the outer edge of the bottom. The lower surface of the flange has three ball sockets, which are respectively connected to the ball head of the ball head rod to form a swingable ball joint, so that the main body of the device 40 is suspended and supported above the annular inertial pendulum 10. The limiting protective cover 30 is an inverted bowl-shaped shell. Its lower end is rigidly connected to the outer periphery of the annular inertial pendulum 10, and its upper end has a circular opening at the center for the main body of the device 40 to extend upward. An annular gap is maintained between the opening and the main body of the device 40. The center of mass of the annular inertial pendulum 10 is located below the hinge plane of the ball head hinge group, forming a downward pendulum inertial stabilization structure.

[0036] The ball socket is fixed to the upper surface of the annular support by radially adjustable screws. These screws pass through the ball socket and screw into the inside of the annular support, thus achieving fixation. The lower end of the limiting protective cover is rigidly connected to the outer periphery of the annular inertial pendulum by bolts or other fasteners, ensuring that the cover is firmly fixed to the pendulum.

[0037] The diameter of the circular opening at the top of the limiting protective cover is 8–12 mm larger than the outer diameter of the corresponding section of the device body, so that an equal-width annular gap is formed between the opening and the device body. This gap remains open in both the radial and axial directions, allowing the device body to make conical swinging movements within ±3° relative to the protective cover, while preventing fingers or tools from being inserted inside.

[0038] In the above technical solution, the outer contour of the cross-section of the annular inertial pendulum 10 is an arc surface, and the inner contour is a stepped surface. The lower section of the stepped surface protrudes inward to form an annular support platform 11, and the top of the stepped surface contracts inward to form a limiting stop, which is used to limit the maximum swing angle of the device body 40 relative to the annular inertial pendulum 10.

[0039] Operating steps for the limit stop:

[0040] First, the main body of the device is suspended and installed onto the annular support via a three-point ball joint;

[0041] When the main body of the device swings due to lateral force, the outer periphery of its flange will approach the top of the stepped surface and contract inward to form a limiting stop.

[0042] Once the swing angle reaches the design limit, the lower surface of the flange contacts the cylindrical surface of the limiting stop, and the mechanical block continues to swing, thereby limiting the further swing of the main body of the device and locking the maximum swing angle within the range of ±3°.

[0043] After the external force is removed, the main body of the device automatically returns to the center by the gravity torque of the pendulum, and the flange and the limiting stop separate again, restoring the free suspension state.

[0044] Furthermore, in the above technical solution, the surface of the ball head is covered with an elastic damping sleeve, the outer diameter of which is smaller than the inner diameter of the ball socket, to provide flexible damping buffer when the ball head hinge swings.

[0045] The elastic damping sleeve is a silicone rubber tube with a wall thickness of 1–1.5 mm and an inner diameter that is 0.2–0.3 mm smaller than the outer diameter of the club head. It uses an interference fit to cover the entire club head and can provide 0.5–1 N·mm / (°) torsional damping when the club head swings.

[0046] Furthermore, in the above technical solution, the lower surface of the flange of the main body 40 of the device is also provided with a downwardly extending annular retaining ring. The annular retaining ring is located outside the ball socket and forms a vertical gap with the upper surface of the annular support 11 to prevent foreign objects from entering the ball joint hinge area.

[0047] Furthermore, in the above technical solution, a flexible sealing ring is embedded in the inner edge of the circular opening of the limiting protective cover 30. The inner circumference of the flexible sealing ring slides in cooperation with the outer circumference of the device body 40, which is used to close the internal space while maintaining the degree of freedom of swing.

[0048] The flexible sealing ring is made of nitrile rubber O-ring with a Shore A hardness of 30-40. Its inner diameter is 1-1.5 mm smaller than the outer diameter of the corresponding section of the device body. It is embedded in the rectangular groove of the limit protection cover opening and maintains a sliding seal with the outer circumference of the device body.

[0049] Furthermore, in the above technical solution, the bottom surface of the annular inertial pendulum 10 is provided with evenly distributed hemispherical support feet 12. The spherical part of the support foot 12 is used to make point contact with the ground to reduce the transmission of ground micro-vibrations to the annular inertial pendulum 10 through surface contact.

[0050] Furthermore, in the above technical solution, the top surface of the main body 40 of the device is provided with an upwardly protruding mounting column 41, and the outer peripheral surface of the mounting column 41 is a conical surface, which is used to form a conical self-centering connection with the external measuring device.

[0051] Furthermore, in the above technical solution, the annular inertial pendulum 10 has an annular cavity inside, and the cross-section of the annular cavity is arc-shaped, which is used to increase the mass of the pendulum while keeping the external dimensions unchanged.

[0052] The ring-shaped pendulum has an internal cavity. By using a higher density material to manufacture the pendulum, the mass can be concentrated in the outer ring without significantly increasing the volume, thereby increasing the mass, improving the moment of inertia of the pendulum, and enhancing its isolation effect against low-frequency vibrations.

[0053] Furthermore, in the above technical solution, the ball socket of the three-point ball joint assembly 20 is fixed to the annular support 11 by a radially adjustable screw. The axis of the radially adjustable screw extends radially along the annular inertial pendulum 10 to adjust the radial position of the ball joint assembly relative to the center of the annular inertial pendulum 10, so as to change the suspension center of the device body 40.

[0054] Furthermore, in the above technical solution, the inner wall of the limiting protective cover 30 is attached with a sound-absorbing layer. The sound-absorbing layer has a wavy porous structure, which is used to absorb internal mechanical noise and reduce the interference of sound wave reflection on the measuring device.

[0055] The sound-absorbing layer is made of 2–4 mm thick open-cell melamine foam plastic, with the surface hot-pressed into a continuous sinusoidal wave shape, with a peak height of 4–6 mm and a wave pitch of 8–10 mm. It is then attached to the inner wall of the limiting protective cover with flame-retardant acrylic pressure-sensitive adhesive.

[0056] Specific Implementation Example 1: This embodiment uses an anti-interference structure for a boundary noise monitoring station under an urban rail transit viaduct. The piers are spaced 24 meters apart. When a train passes, the bridge deck experiences vertical and horizontal micron-level vibrations, with frequencies concentrated between 10 Hz and 30 Hz. Traditional supports directly amplify these vibrations into sensor acceleration signals, resulting in measured values ​​that are nearly 10 decibels higher than the actual ambient noise.

[0057] The base was placed on a hardened floor. The annular pendulum, with an outer diameter of 400 mm, was made of cast brass and had three hemispherical stainless steel support feet evenly distributed on its bottom, forming three-point contact with the floor. The main body of the device was a disc-shaped aluminum alloy shell with three ball-and-socket sockets evenly distributed on its bottom flange, which interlocked with the ball head rod on the pendulum support, forming three-point suspension. The limiting protective cover was made of fiberglass and was fixed to the outer periphery of the pendulum with bolts after being upside down. The outer diameter of the limiting protective cover was larger than that of the annular pendulum and was fixed to the outer periphery of the annular pendulum with bolts, clips or other fasteners through its lower edge. The top circular opening maintained an eight-mm annular gap with the main body of the device, with an embedded nitrile rubber sealing ring, which allowed the main body to swing conically while preventing piston air from entering when a train passed. The inner wall of the cover was covered with a wavy melamine foam sound-absorbing layer, 3 mm thick, to absorb the high-frequency screeching sound of the wheel and rail and prevent reverberation inside the cover.

[0058] Installation requires no anchor bolts; simply push the base directly under the bridge deck, positioning the support legs between the two expansion joints. The sensor is fixed to the conical mounting column on the top of the main unit, and the cable is led to the data acquisition instrument along the groove on the outer wall of the enclosure. When a train passes, the bridge deck vibration is first converted into point contact slippage by the hemispherical support legs. Subsequently, the pendulum lags behind due to its center of mass being lower than the hinge plane, and the main unit remains almost stationary. Actual measurements show that the effective acceleration value output by the sensor does not have a significant abrupt change during the train's passage and coincides with the background curve, proving that spurious vibrations are isolated. The sealing and sound-absorbing structure ensures that the difference between the sound field inside the enclosure and the external free field is less than one decibel, meeting the accuracy requirements for boundary noise monitoring. This embodiment is suitable for outdoor scenarios where there is long-term unattended operation and continuous micro-vibration of the bridge structure. Deployment can be completed within five minutes, and maintenance-free for ten years.

[0059] Specific Implementation Example 2: In this example, the same base is scaled down and used on a precision motor factory test bench. The test bench is located in the second-floor assembly workshop, where forklifts frequently operate below. The floor slab experiences structural resonance around 20 Hz. The intensity of the mechanical waves radiated by the motor itself is only one-third of the background vibration. Traditional rubber pad vibration isolation cannot prevent the floor slab vibration from propagating along the steel frame of the test bench, resulting in excessive measurement uncertainty.

[0060] The circular inertial pendulum was replaced with a ductile iron component with an outer diameter of 200 mm, accounting for 60% of the total mass of the device. The bottom still retains three hemispherical support feet, but their diameter is reduced to 10 mm, allowing it to be placed directly on a marble plate on the test bench. The main body of the device is a stainless steel disc with an outer diameter of 160 mm. The bottom flange ball socket mates with the pendulum support ball head rod to form coaxial suspension. The limiting protective cover was replaced with a thin-walled aluminum tensile component, with a 5 mm gap between the top opening and the main body, and an embedded silicone rubber sealing ring. The inner wall of the cover is lined with a wavy, perforated polyurethane foam, 2 mm thick, to absorb the high-frequency eddy current noise generated by the motor cooling airflow.

[0061] The test procedure is as follows: First, place the base in the center of the marble slab, then fix the motor under test on the conical mounting column on the top surface of the main body of the device. Before starting the motor, loosen the radially adjustable screws, manually push the main body lightly, and observe whether the pendulum returns to center freely. After confirming that there is no problem, tighten the screws. During the motor speed-up process, the floor vibration caused by the passing forklift below is isolated by the inertial lag of the pendulum, and the sensor only outputs the mechanical wave signal of the motor itself. After the measurement is completed, the entire device can be moved away from the base without interfering with the installation of the next motor. This embodiment is suitable for indoor industrial scenarios with limited space and frequent replacement of the tested object. By using the scaling and material replacement within the same set of claims, repeatable low-uncertainty measurement results can be obtained in a strong background vibration environment.

[0062] Specifically, the principle of this invention is as follows: This invention follows the coupling principle of "inertial lag - gravity reset - flexible enclosure". The ring-shaped inertial pendulum has a larger moment of inertia relative to the main body of the device, and its center of mass is deliberately placed below the plane of the ball joint hinge, forming a physical pendulum effect. According to d'Alembert's principle, when the foundation is subjected to micro-vibration excitation, the low-position geometric characteristics of the pendulum's center of mass cause its angular acceleration response to lag behind the ground motion. Since the main body of the device has a smaller mass and is suspended above the hinge, it is almost not directly driven by the same excitation, thus generating a relative angular displacement at the hinge interface. The vibration energy is consumed by the micro-rolling friction between the ball joint and the socket, achieving the isolation effect of "large mass blocking the outside, small mass remaining stationary". The three-point ball joint provides a single motion channel, and its isotropic degrees of freedom ensure that the isolation mechanism remains effective regardless of whether the ground excitation comes from the vertical, horizontal, or coupling direction. An elastic damping sleeve forms a viscoelastic ring on the ball joint's outer surface. As the relative oscillation speed increases, the sleeve's shear deformation converts mechanical energy into heat energy, providing velocity-dependent damping and preventing continuous micro-oscillations due to "zero-crossing friction." The limiting protective cover, through its inverted bowl-shaped stiffness, transforms the rigid collision between the pendulum and the external environment into elastic deformation of the cover. The geometric interference between the limiting stop and the device flange only occurs linearly at large oscillation angles. Upon contact, a restoring torque pointing towards the rotation axis is instantly generated, causing the pendulum to return to its neutral position, achieving a springless and electromagnetically independent gravity-based reset. The flexible sealing ring and the annular retaining ring form a double barrier: the sealing ring is slightly compressed radially, forming a continuous surface seal that allows the main conical pendulum without leaving straight gaps; the annular retaining ring leaves a curved channel axially, requiring dust and droplets to undergo multiple refractions before reaching the ball joint, significantly reducing the probability of lubrication failure. The sound-absorbing layer is made of open-cell foam material. Its wavy profile causes the incident sound wave to reflect multiple times between adjacent troughs. Each reflection is accompanied by frictional energy dissipation between the air and the pore walls, and the sound energy is gradually attenuated, preventing reverberation inside the enclosure from being back-coupled to the sensor. The entire system uses a pendulum as an "inertial reference frame," a ball joint as a "motion gate," and sealing and sound absorption as an "environmental barrier." The functions of these three components are superimposed but physically separated. Wear or aging of any single part will not cause the overall isolation function to fail. Since the entire principle relies only on mass distribution, geometry, and material internal friction, without the need for external energy or control algorithms, it can operate reliably for a long time in extreme temperature and humidity, strong electromagnetic interference, and flammable and explosive environments. This provides a purely mechanical technical path for mechanical wave intensity measurement that "suppresses false signals at the source."

Claims

1. An anti-interference structure for an environmental noise measurement device for mechanical wave intensity, characterized in that, include: The device comprises a ring-shaped inertial pendulum, a three-point ball-joint hinge assembly, a main body, and a limiting protective cover. The ring-shaped inertial pendulum is a solid metal body in the shape of a ring, with a continuous smooth curved surface on its outer circumference and a radially inwardly extending annular support on its inner circumference. The three-point ball-joint hinge assembly consists of three ball-joint hinges, with the ball joints of each hinge evenly spaced circumferentially on the upper surface of the annular support, and the ball joints extending upward. The main body is a disc-shaped shell with a radial flange on its bottom outer edge. The device has three ball joints, which are respectively connected to the ball head of the ball joint to form a swingable ball joint, so that the main body of the device is suspended and supported above the annular inertial pendulum. The limiting protective cover is an inverted bowl-shaped shell, the lower end of which is rigidly connected to the outer periphery of the annular inertial pendulum, and the upper end has a circular opening at the center for the main body of the device to extend upward. An annular gap is maintained between the opening and the main body of the device. The center of mass of the annular inertial pendulum is located below the hinge plane of the ball joint assembly, forming a downward pendulum inertial stabilization structure.

2. The anti-interference structure of the mechanical wave intensity measurement environmental noise device according to claim 1, characterized in that, The outer contour of the cross-section of the annular inertial pendulum is an arc surface, and the inner contour is a stepped surface. The lower section of the stepped surface protrudes inward to form the annular support platform, and the top of the stepped surface contracts inward to form a limiting stop, which is used to limit the maximum swing angle of the device body relative to the annular inertial pendulum.

3. The anti-interference structure of the mechanical wave intensity measurement environmental noise device according to claim 2, characterized in that, The surface of the ball joint is covered with an elastic damping sleeve, the outer diameter of which is smaller than the inner diameter of the ball socket, to provide flexible damping and cushioning when the ball joint hinge swings.

4. The anti-interference structure of the mechanical wave intensity measurement environmental noise device according to claim 3, characterized in that, The lower surface of the flange of the main body of the device is also provided with a downwardly extending annular retaining ring. The annular retaining ring is located outside the ball socket and forms a vertical gap with the upper surface of the annular support, which is used to prevent foreign objects from entering the ball joint hinge area.

5. The anti-interference structure of the mechanical wave intensity measurement environmental noise device according to claim 4, characterized in that, The inner edge of the circular opening of the limiting protective cover is fitted with a flexible sealing ring. The inner circumference of the flexible sealing ring slides in conjunction with the outer circumference of the device body, which is used to close the internal space while maintaining the degree of freedom of swing.

6. The anti-interference structure of the mechanical wave intensity measurement environmental noise device according to claim 5, characterized in that, The bottom surface of the annular inertial pendulum is provided with evenly distributed hemispherical support feet. The spherical part of the support feet is used to make point contact with the ground to reduce the transmission of ground micro-vibrations to the annular inertial pendulum through surface contact.

7. The anti-interference structure of the mechanical wave intensity measurement environmental noise device according to claim 6, characterized in that, The device body has an upwardly protruding mounting column at the center of its top surface. The outer circumferential surface of the mounting column is a conical surface, which is used to form a conical self-centering connection with an external measuring device.

8. The anti-interference structure of the mechanical wave intensity measurement environmental noise device according to claim 7, characterized in that, The annular pendulum has an annular cavity inside, and the cross-section of the annular cavity is arc-shaped.

9. The anti-interference structure of the mechanical wave intensity measurement environmental noise device according to claim 8, characterized in that, The ball joint of the three-point ball joint assembly is fixed to the annular support by a radially adjustable screw. The axis of the radially adjustable screw extends radially along the annular inertial pendulum and is used to adjust the radial position of the ball joint assembly relative to the center of the annular inertial pendulum, so as to change the suspension center of the main body of the device.

10. The anti-interference structure of the mechanical wave intensity measurement environmental noise device according to claim 9, characterized in that, The inner wall of the limiting protective cover is attached with a sound-absorbing layer, which has a wavy porous structure to absorb internal mechanical noise and reduce the interference of sound wave reflection on the measuring device.

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