A vibrating wire inclinometer

Abstract

This utility model relates to the field of tilt measurement technology, specifically to a vibrating wire tiltmeter, comprising a housing, inside which are two symmetrically arranged steel wires, each with a support at both ends. The support is divided into an upper support and a lower support, with the ends of the steel wires fixed to the upper and lower support via wire clamps. The lower support is connected to the upper support via an elastic hinge. Support seats are fixed on both sides of the lower support for fixing the coil. A counterweight is fixed at the lower end of the lower support. Utilizing the characteristics of the vibrating wire sensor, namely that its output signal natural frequency is determined only by its physical parameters such as tension, length, and linear density and does not require power supply, this sensor exhibits strong long-term stability, strong anti-interference ability, low temperature drift and zero drift, and minimal influence from electrical parameters, enabling it to adapt to long-term observation and long-distance testing under harsh conditions.

Description

Technical Field

[0001] This utility model relates to the field of tilt measurement technology, specifically to a vibrating wire tilt meter. Background Technology

[0002] Inclinometers are used in the construction industry to monitor the tilt of high-rise buildings, ancient buildings, and renovated buildings, providing early warnings of structural deformation caused by foundation settlement and load changes. In bridge and tunnel engineering, they monitor the tilt of bridge main beams, piers, temporary supports, and tunnel linings, assessing load balance and surrounding rock stability to prevent cracking or collapse. In slope and foundation pit engineering, they monitor the tilt trends of slopes at different depths and foundation pit support structures to provide early warnings of landslide and foundation pit collapse risks. In the field of tall structures, they monitor the tilt of transmission towers, wind turbine towers, etc., in real time, combining environmental data to ensure their safety. In special equipment, they are integrated into cranes, tower cranes, and other equipment, triggering alarms when tilt exceeds limits to prevent operational accidents. With its high-precision real-time monitoring, inclinometers provide early warnings for structural safety in various industries and are a key tool for preventing instability accidents. Inclination monitoring is widely used in safety monitoring and inspection across various industries.

[0003] Currently, in the field of structural safety monitoring, tilt angle monitoring of structures mostly adopts inclinometers based on MEMS principles. This involves using mature MEMS chips, along with acquisition and data processing circuits, to acquire the tilt angle over time. However, this technology currently has the following problems:

[0004] (1) There is currently a lack of high-precision tilt measurement chips in China;

[0005] (2) Since MEMS chips are active sensors, they cannot avoid the influence of low-frequency electrical noise (especially 1 / f noise) on signal accuracy. This is a major obstacle to improving the accuracy of MEMS chip tilt measurement. The coupling between the sensitive structure of MEMS sensor (such as micro-mechanical pendulum, capacitor plate, etc.) and the circuit part may also introduce additional low-frequency noise, further aggravating this problem.

[0006] (3) MEMS chips are susceptible to time drift and temperature drift, and their long-term stability is a major factor limiting their application in high-precision measurement scenarios. Summary of the Invention

[0007] In response to the problems raised in the background art, this utility model provides a vibrating wire inclinometer to solve them, and the following will further elaborate on this utility model.

[0008] A vibrating wire inclinometer includes a housing, inside which two symmetrically arranged steel wires are provided. Support members are provided at both ends of the steel wires. The support members are divided into an upper support member and a lower support member. Both ends of the steel wires are fixed to the upper support member and the lower support member by wire clamps. The lower support member is connected to the upper support member by an elastic hinge. Support seats are fixed on both sides of the lower support member for fixing the coil. A counterweight is fixed at the lower end of the lower support member.

[0009] Preferably, a sealing block is provided at the lower end of the counterweight, and a damping arm is fixedly provided at the lower end of the counterweight, the damping arm being immersed in grease provided inside the sealing block.

[0010] Preferably, a notch is provided inside the upper support member, and a lightning arrester is installed inside the notch.

[0011] Preferably, a temperature sensor is provided at the upper end of the surge protector.

[0012] Preferably, both the upper support and the sealing block are connected to the inner side of the outer casing via sealing rings.

[0013] Preferably, sealant is applied to the ends of the outer casing.

[0014] Preferably, a cable is provided at the upper end of the housing.

[0015] Preferably, the outer casing is made of stainless steel.

[0016] Preferably, the cable is a twisted pair.

[0017] Preferably, the cable is connected to the notch of the upper support member via a sealing ring.

[0018] Beneficial effects: Compared with the prior art, this utility model utilizes the characteristics of vibrating wire sensors, namely, the natural frequency of its output signal is determined only by its physical parameters such as tension, length, and linear density, and does not require power supply. These parameters have strong long-term stability, strong anti-interference ability, small temperature drift and zero drift, and are less affected by electrical parameters. It can adapt to long-term observation and long-distance testing under harsh conditions, and can use the same multi-channel device for multi-sensor measurement. Compared with MEMS inclinometers, it has more advantages in the field of structural safety monitoring and can solve the problems of accuracy, drift, and cost encountered by MEMS inclinometers in the field of structural safety monitoring. Attached Figure Description

[0019] Figure 1 : A schematic diagram of the structure of this utility model;

[0020] In the diagram: 1. Steel string; 2. Coil; 3. Elastic hinge; 4. String clamp; 5. Support base; 6. Support piece; 7. Counterweight; 8. Damping arm; 9. Grease; 10. Sealant; 11. Sealing ring; 12. Lightning arrester; 13. Temperature sensor; 14. Housing; 15. Cable. Detailed Implementation

[0021] Next, we will combine the appendix Figure 1 A specific embodiment of this utility model will be described in detail below.

[0022] A vibrating wire inclinometer includes a housing 14, inside which two symmetrically arranged steel wires 1 are provided. The steel wires 1 serve as sensitive elements for sensing tension. When the inclinometer changes angle, its tension also changes synchronously. The use of two steel wires to form a differential working structure improves the working sensitivity by 100%. At the same time, the symmetrical arrangement of the structure also improves the consistency of bidirectional measurement of the inclinometer. The diameter of the steel wires 1 is 0.2~0.5mm, and the length-to-diameter ratio of the steel wires is generally not less than 200. Support members 6 are provided at both ends of the steel wires 1. The support members 6 are divided into upper support members and lower support members. Both ends of the steel wires 1 are fixed to the upper support members and lower support members by wire clamps 4. The lower support member and the upper support member are connected by an elastic hinge 3. The elastic hinge 3 is an integrated metal structure with a circular arc notch. It can be used for limited angular displacement of complex motion around an axis, and its elastic deformation is reversible. At the same time, it is a precise micro-displacement hinge that can both support and guide. This hinge is made from a single piece of metal, offering high displacement resolution and guiding accuracy. Its main function is to connect the upper and lower supporting components. When the hinge tilts externally, it is subjected to the horizontal gravitational torque component of the counterweight, resulting in a minute horizontal displacement.

[0023] Support seats 5 are fixed on both sides of the lower support member. The support seats 5 are used to fix the coil 2. The natural frequency signal of the vibrating wire sensor needs to be excited by the coil 2 to pick up the signal after the wire starts to vibrate. The center position of the coil 2 is the center position of the wire 1, which is conducive to exciting the first natural frequency.

[0024] A counterweight 7 is fixedly provided at the lower end of the lower support member.

[0025] A sealing block is provided at the lower end of the counterweight 7, and a damping arm 8 is fixedly provided at the lower end of the counterweight 7. The damping arm 8 is immersed in grease 9 located inside the sealing block. The grease medium, a semi-solid material, relies on the viscous resistance of the medium to attenuate the kinetic energy of the moving mechanism, thus shortening the mechanical oscillation or movement time. When there is vibration in the external environment, it quickly stops the pendulum's vibration to avoid affecting the stability of the data. High-viscosity silicone grease, such as silicone-based damping paste, can be used in conjunction with the damping arm to improve the damping effect and enhance the inclinometer's vibration resistance.

[0026] In this embodiment, a notch is provided inside the upper support member, and a surge protector 12 is installed inside the notch. The grounding pin of the surge protector is connected to the metal casing of the inclinometer. Since the inclinometer is generally installed on an outdoor structure, its signal cable is easily affected by induced lightning, which can damage the coil inside the sensor. Therefore, its function is to provide a certain surge absorption capacity to protect the coil from surge damage. The surge protector generally uses a GDT gas discharge tube as the secondary protection inside the inclinometer, which has a large current carrying capacity and strong impact resistance. Although the inclinometer is equipped with a surge protector inside, in some lightning-prone areas and when the inclinometer is installed in an open area, it is necessary to install a special surge protector on the external cable of the sensor to further protect the sensor.

[0027] A temperature sensor 13 is provided at the upper end of the surge protector 12. The temperature sensor is used to measure the change of ambient temperature of the inclinometer and is mainly used for data analysis when some abnormal external environmental parameters change.

[0028] In this embodiment, both the upper support and the sealing block are connected to the inner side of the outer casing 14 via sealing rings 11. Sealant 10 is applied to the ends of the outer casing 14. The sealing rings and sealant 10 primarily serve a waterproof function, while also withstanding certain water pressure, thus improving the reliability, durability, and environmental adaptability of the inclinometer.

[0029] Sealant 10 must meet the requirements of waterproofing and corrosion resistance, and also adhere reliably to the stainless steel casing. Silicone rubber sealant or epoxy resin sealant can be used.

[0030] The choice of sealing ring material needs to take into account the operating environment, such as temperature, medium, pressure, and wear resistance. Generally, nitrile rubber or fluororubber O-rings can be selected.

[0031] In this embodiment, a cable 15 is provided at the upper end of the housing 14. Since the inclinometer is generally installed outdoors, it needs a certain degree of rust resistance. That is, the housing 14 is made of stainless steel. The cable 15 is generally a twisted pair or a shielded twisted pair. It is mainly used to connect the coil and temperature sensor inside the inclinometer. It is generally a six-core cable, in which two coils use two pairs of core wires and one temperature sensor uses one pair of core wires.

[0032] The cable 15 is connected to the notch of the upper support member through the sealing ring 11.

[0033] This vibrating wire inclinometer is used as follows:

[0034] (1) First, the support is divided into upper and lower parts, and the upper support and the lower support are connected together by an elastic hinge;

[0035] (2) The upper support and the lower support are then constrained together by two steel wires respectively. The steel wires are held by a wire clamp, which is fixed to the upper and lower support. The two steel wires are arranged symmetrically. The counterweight is used to configure the working sensitivity of the inclinometer and is fixed to the lower support. The weight of the counterweight is also constrained by the tension of the two steel wires.

[0036] (3) When assembling the inclinometer device, the two steel wires are respectively set with initial tension, which is used as a reference parameter;

[0037] (4) The counterweight deflects under the influence of gravitational torque, which is transmitted to the vibrating string through the elastic hinge. At this time, the gravitational torque is M = MgLsinθ (M: mass of the counterweight, L: distance from the center of gravity of the counterweight to the center of the elastic hinge, g is the acceleration due to gravity), and the restoring torque of the elastic hinge is Me = K⋅δ (K: hinge stiffness, δ: deformation of the elastic hinge). According to the equilibrium condition of forces, we get: MgLsinθ = Kδ. From the formula, we can see that the tilt angle θ and the deformation of the elastic hinge δ have a functional relationship. When θ is very small, such as θ < ±2°, sinθ ≈ θ, and the relationship can be linearized to: MgLθ ≈ Kδ. At this time, the tilt angle θ and the deformation of the elastic hinge δ have a linear functional relationship. Therefore, as long as the deformation of the elastic hinge δ can be measured, the tilt angle θ can be obtained.

[0038] (5) Since the two steel strings are symmetrically arranged and operate in differential mode, when the tension of one steel string increases, the tension of the other steel string decreases, and the magnitude of the tension change of the two steel strings is the same. The purpose of using two steel strings is to improve the sensitivity of the sensor and obtain high-precision tilt angle data by using differential calculation. The tension of the steel string is T=4*m*l2*f2 (where m is the mass per unit length of the steel string, l is the effective length of the steel string, and f is the first natural frequency of the steel string). The change in tension is proportional to the deformation of the elastic hinge, i.e., ΔT∝δ; the change in tension ΔT is also proportional to the change in the first natural frequency f2 of the steel string, so f2∝ΔT∝sinθ. As long as the frequency value of the steel string can be measured, the corresponding angle value θ can be obtained. At the same time, at small angles (θ<±2°), the first natural frequency f2 of the steel string has a linear relationship with the angle value θ; when the angle increases, nonlinear fitting can also be used to obtain accurate angle values.

[0039] (6) Data calculation: After the sensor is installed, the initial frequency of the two steel strings needs to be measured as the initial parameter of the inclinometer. In subsequent continuous measurements, the square difference between each frequency measurement value and the initial frequency value is calculated, and then multiplied by the sensitivity coefficient to obtain the angle value of the sensor.

[0040] When measuring small angles where θ < ±2°, a linear model can be used, meaning the squared difference of the frequencies and the angle value θ have a linear relationship, which can be expressed by the formula:

[0041]

[0042] Where k is the sensitivity coefficient, which is calibrated using a standard inclinometer calibration device. , The initial frequency of the two steel strings when the inclinometer is first installed; , The frequency of the two steel strings after the inclinometer starts working.

[0043] When measuring a large angle, a nonlinear model (polynomial equation) can be used to calculate a more accurate angle value:

[0044]

[0045] Where A, B, and C are polynomial coefficients.

[0046] Compared with existing technologies, this invention utilizes the characteristics of vibrating wire sensors, namely, the inherent frequency of its output signal is determined only by its physical parameters such as tension, length, and linear density, and does not require power supply. These parameters have strong long-term stability, strong anti-interference ability, small temperature drift and zero drift, and are less affected by electrical parameters. It can adapt to long-term observation and long-distance testing under harsh conditions, and can use the same multi-channel device for multi-sensor measurement. Compared with MEMS inclinometers, it has more advantages in the field of structural safety monitoring and can solve the problems of accuracy, drift, and cost encountered by MEMS inclinometers in the field of structural safety monitoring.

[0047] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A vibrating wire inclinometer, characterized in that: Includes an outer shell (14), inside which are two symmetrically arranged steel strings (1), and at both ends of the steel strings (1) are support members (6), the support members (6) are divided into an upper support member and a lower support member, at both ends of the steel strings (1) are fixed to the upper support member and the lower support member by a string clamp (4), the lower support member is connected to the upper support member by an elastic hinge (3), and a support seat (5) is fixed on both sides of the lower support member, the support seat (5) is used to fix the coil (2), and a counterweight (7) is fixed at the lower end of the lower support member.

2. The vibrating wire inclinometer according to claim 1, characterized in that: A sealing block is provided at the lower end of the counterweight (7), and a damping arm (8) is fixedly provided at the lower end of the counterweight (7). The damping arm (8) is immersed in the grease (9) provided inside the sealing block.

3. The vibrating wire inclinometer according to claim 1, characterized in that: A notch is provided inside the upper support member, and a surge protector (12) is provided inside the notch.

4. A vibrating wire inclinometer according to claim 3, characterized in that: A temperature sensor (13) is provided at the upper end of the surge protector (12).

5. A vibrating wire inclinometer according to claim 2, characterized in that: Both the upper support and the sealing block are connected to the inner side of the outer shell (14) via a sealing ring (11).

6. A vibrating wire inclinometer according to claim 1, characterized in that: Sealant (10) is applied to the ends of the outer casing (14).

7. A vibrating wire inclinometer according to claim 1, characterized in that: A cable (15) is provided at the upper end of the housing (14).

8. A vibrating wire inclinometer according to claim 1, characterized in that: The outer casing (14) is made of stainless steel.

9. A vibrating wire inclinometer according to claim 7, characterized in that: The cable (15) is a twisted pair.

10. A vibrating wire inclinometer according to claim 7, characterized in that: The cable (15) is connected to the notch of the upper support through a sealing ring (11).

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