KR100375026B1 - Detection apparatus which measures and detects physical quantity of structure by transformational detector applied from strain gauge - Google Patents

Abstract

The present invention relates to a detection device for measuring the physical quantity of the structure by using a strain gage applied strain strain.

A fine voltage is output by connecting a summing box conditioner box having a temperature calibrate sensor to a strain transformer including a strain gauge formed in the structure, and outputting the output voltage. Indicator) converts the analog voltage into digital and simultaneously outputs a signal to remotely control by counting the output value and outputs a signal on the computer to measure the physical quantity of the structure. In addition to compensating for the fluctuating value, the output error due to the temperature change along the lead length from the strain detector to the indigate can be actively compensated.

In the present invention, since the strain detection part or the lead wire is compensated precisely by temperature change, it is precisely measured so that it is non-destructive to measure the quantity of contents stored in a large-capacity storage container or physical structure of a large structure such as a bridge with high reliability. Information on physical properties such as bending, deflection, fatigue, yield, internal stress, etc. can be obtained stably and continuously.In addition, accurate measurement of inventory can be used to accurately introduce inventory and thus prevent loss due to measurement errors. It can prevent, reduce costs, and accurately grasp the physical properties of the structure to prevent large accidents in advance and reflect them in the design, which can greatly contribute to industrial development.

Description

Detection apparatus which measures and detects physical quantity of structure by transformational detector applied from strain gauge}

The present invention relates to a detection device for measuring a physical quantity of a structure by using a strain gage applying strain gauge, and more specifically, a temperature compensation sensor (Temperature calibrate sensor) in a strain transformer including a strain gage formed in the structure Connect a summing box conditioner box with a signal to output a fine voltage, and convert the output value into an amplification of the analog voltage to the digital signal at the indicator and simultaneously process the output value to remotely control the signal. In order to measure the physical quantity of the structure by transmitting the signal as an image on a computer, the temperature change according to the lead wire length from the strain detector to the indigate, as well as compensating for the variation value changed by the temperature change Physical error by actively compensating output error The present invention relates to an apparatus for contributing accuracy to the detection of.

The strain gauge is also called a strain or displacement gauge. When strain is applied to a resistor of a metal or a semiconductor, its resistance is changed and the voltage output by the Wheatstone bridge effect is applied. As a use, it is widely used for the measurement of a differential pressure, a pressure transmitter, a vortex flowmeter, a torque meter, and other real stresses.

In this way, the method of measuring the load using the strain gauge, the method of measuring the stress of the bolt, the sensor installed in the vehicle to detect the impact, the scale using the load cell (Load cell), the method of measuring the pressure when writing In many ways, it is widely used to measure stress.

In general, bridges need to be maintained for more than a few decades, so the beams and columns are installed in the bridges to keep the bridges in view of the continuously repeated loads.

Although bridges are designed and constructed to last for more than a few decades, bridges, dynamic loads, or oxidation, which are continuously applied, sometimes fail to maintain as originally designed and collapse. The collapse of the bridge causes a catastrophic disaster, so the manager checks it once, but measures the strength due to the appearance or repulsion at the time by using an external abnormality or a tester, and internal fatigue, yield state, stress The physical quantity such as the state is difficult to measure, and considering the size of the bridge, it is measured by the tester.However, it is difficult to measure several parts continuously in succession. There was a difficulty in grasping.

In addition, it is common to make a structure with a support structure that supports and supports a large tank to store grain or powdered powder, and when the grain or powder stored in the storage tank is withdrawn for some time, the tank Not only are the amounts unknown for the residuals within, but the devices displaying capacity in the existing volume have a large difference in mass when the internal filling state is uneven or the upper and lower filling densities are differently accumulated. In addition, even when the pupils are formed in the gate portion during the emission, the amount and mass of the contents are inaccurate by simply volume.

In particular, a factory that purchases cheap rice paddies includes a process of drying moisture while storing it in a tank for a long time, so it is not easy to grasp the final stock, and since the commerce is carried out by weight instead of being shipped in volume, the actual quantity and assumed Cause a noticeable difference in volume.

So, the developed level was introduced to the structure by using a weight leveler (Weighing leveler) using a deformation sensor, a low-precision leveler that measures the load of the structure has been introduced and used, but the change of output according to the temperature, such as the temperature deviation between the structure and the sensor Due to the low accuracy of the measurement and the extremely limited use range, it has not escaped the basic leveler stage. In addition, the method of analyzing the structure by directly attaching the strain gauge to the structure has been developed and distributed.However, the cost is high due to limitations in the adhesion state between the structure and the gauge, the temperature compensation problem between the circuits, the heat treatment problem, the insulation and airtightness, and the proficiency and knowledge experience of the implementer At the same time, the problem of precision accuracy is pointed out because of inefficiency and lack of reliability between individuals.

Accordingly, an object of the present invention is to solve the above-mentioned conventional problems, and to maximize performance by dissecting electrical circuits and mechanical mechanisms, and analyzing and controlling the output change factors according to temperature. In addition, it is invented to increase the range of use in consideration of special conditions in the field, and its purpose is to be unified and standardized so that even a beginner can easily install and operate it, so that it can be spread as a universal detector sensor.

In order to achieve the above object, the present invention provides a strain detection unit for measuring a physical quantity of a structure by using a strain gauge, strain detection unit having a plurality of sensors for generating a voltage according to the resistance change of the strain gauge, and A plurality of sensors are installed in different positions, and provided with a temperature compensation sensor for compensating for errors in the outputs of the sensors according to the minute temperature difference between the installation positions, the input and output lines of the deformation detection unit and the temperature compensation sensor Compensating for the error of the outputs of the sensors by connecting the input and output lines of the indicator and the input and output lines of the indicator, and compensating for the error of the outputs of the sensors according to the lead wire length to the strain detection unit and the indicator And the error according to the installation position and the lead wire length The indicator for receiving the analog output voltages of the compensated sensors, converting the analog output voltages into amplification and digital values, and transmitting the digital values remotely using a predetermined communication standard; and the digital value from the indicator. It characterized in that it comprises a computer for processing the display on the monitor.

1 is a flow diagram of a system of the present invention.

2A, 2B, and 2C are basic circuit diagrams for constructing the strain detector of the present invention.

3 is a circuit diagram of a strain detector which is a main part of the present invention.

4 is a schematic diagram of a synthetic condition junction box which is a part of the present invention.

Figure 5a, Figure 5b is a state diagram used in accordance with an embodiment of the present invention

Figure 6 is an example perspective view of the deformation detection gauge used in the present invention

7 is a cross-sectional view of the deformation detection gauge of FIG.

* Description of Signs of Major Parts of Drawings *

1. Deformation detection unit 2. Temperature compensation sensor

3. Synthetic condition connection box 4. Indicator

5. Lead wire 6. Computer

11. Deformation detection gauge 12. Mounting groove

13. Cohesion 14. Bracket

15. Horizontal structure 15 '. Vertical structure

Hereinafter, the configuration of the present invention in detail with reference to the accompanying drawings as follows.

1 is an overall flowchart of a system of the present invention, FIGS. 2A, 2B and 2C are basic circuit diagrams for constructing the strain detector circuit of the present invention, and FIG. 3 is a circuit diagram of a deformation detector which is a main part of the present invention. 4 is a circuit diagram of a synthetic condition junction box which is a part of the present invention, and FIGS. 5A and 5B are state diagrams applied to a horizontal structure and a vertical structure, respectively, as a use state diagram according to an embodiment of the present invention.

As shown in Fig. 1, the system of the present invention comprises means for constituting a deformation detection unit 1 by connecting several sensors including a strain gauge in an interlocked manner; Means for compensating for the unprocessed output value by a change in temperature in the sensor by connecting a composite condition junction box (3) in which a temperature compensation sensor (2) is formed to be linked to the deformation detection unit (1); The output value includes: an indicator (indicator) means for amplifying and converting an analog voltage into a digital signal and simultaneously outputting a signal for totally controlling the output value for remote control; The output value by the signal is constituted by means for causing the image of the computer to be derived.

On the other hand, even if the strain detection unit (1) and the indicator (4) is made of a specially selected conductor, the standard lead wire (5) at the time of manufacturing temperature compensation, but due to the length of the wire depending on the site conditions due to the resistance component depending on the wire length Due to the temperature deviation factor, the existing Wheatstone bridge application circuit cannot control the output factors according to the temperature change. Therefore, a special circuit is constructed as shown in FIG. 3 to control the temperature deviation factor below a certain level regardless of the lead wire length. I could do it.

When the deformation detection unit 1 is firmly fixed by selecting an appropriate position of a structure (15, 15 ': see FIG. 5) such as a support for supporting a proper position of the bottom of the bridge and a storage container and a filling hopper having a large capacity, etc. do.

As shown in FIG. 2A, the sensor formed in the strain detection unit 1 has two sets in the direction of increasing resistance when the load increases in the strain gauge to the base portion of the deformation detecting unit, and two sets in the direction of decreasing resistance when the load increases. Attach the basic circuit by adhering the strain detection unit and the strain gauge to the same deformation condition.

Initially in this state

if i _g = 0

R ₁ = R ₂ , R ₃ = R ₄ i ₁ = i ₂ , i ₃ = i ₄

i ₁ R ₁ = i ₃ R ₃ , i ₂ R ₂ = i ₄ R ₄

At zero parallel condition and Ohm's law

… … … … … … … … … … ①

Is a strain gage and is an active element for displacement.

Each resistance changes.

Substituting this into ① Is As it becomes

… … … … … … … … ②

Where initial And this Expressed as When the load increases, attach it in the direction of decreasing resistance, When the load increases, the adhesive is attached in the direction of increasing the resistance ego, to be.

Substituting this into ②

… … … … … … … … … … ③

In the initial state, all the resistors are the same = 0V,

≠ Back side (the opposite direction of resistance component) ≠ 0.

here, Changes in resistance due to load strain And change of resistance due to temperature influence Can be represented by Is , Is displayed.

Wow Using the same material, the same manufacturing lot (LOT) with the same temperature characteristics, the same temperature characteristics Is displayed.

… … … … … … … … … … ④

Due to load strain effect on no-load condition Is 0 A self-compensation circuit with 0 is established to achieve temperature compensation over a wide range.

In ④ above Wow If you can design the structure with parts of the same size and different components, and you can glue strain gauge

Can be simplified.

Since the compensation of the temperature under load is not made in the basic circuit, it can be compensated by selecting a gauge sensitive to temperature sensitivity change in the existing circuit.

For example, a strain detector composed of a basic circuit as shown in FIG. 2A was mounted where the temperature was rapidly changed from 20 ° C. to −20 ° C., and the indication value was 50,000 kg at 20 ° C. FIG. At that time, the strain of the part to be detected ) Is 750μ, look at the load when the output is not compensated at -20 ℃,

* Resistance change by load strain at 20 ℃ ) : Applied Voltage -----------------: : Strain gauge 20 ℃ Resistance-: 350Ω : Gauge Factor ------: 2.0 : Load strain -------------: * Load strain (ε) at -20 ℃ : Thermo-elastic coefficient -----------: -220PPM / ℃ : Temperature difference --------------------: 40 ℃ : 20 ℃ Load Strain --------: * The resistance (R) of the strain gauge due to the linear expansion coefficient of the material to be detected at -20 ℃ : Strain gauge 20 ℃ Resistance-: 350Ω : Linear expansion coefficient to be detected ------: -11PPM / ℃ : Temperature difference --------------------: 40 ℃ *, Resistance change by load strain at -20 ℃ ) only) Is assumed to be constant. * Resistance change of strain gauge by temperature change at -20 ℃ : -------------------------------: 350Ω : Temperature gauge of constant gauge-: -11PPM / ℃ : Temperature difference -------------------------: 40 ℃ So the voltage output at 20 ℃ is ( ) If you substitute from * Voltage output at -20 ℃ ) If you substitute from

As described above, if 1.5mV is indicated at 50,000 ° C. and expressed as 50,000 kg, 1.48mV is indicated at −20 ° C. and expressed as 49,300 kg and an error of 700 kg of a load load occurs. This causes an error factor of 1.4% so that the output compensation can be made only when the temperature output compensation circuit is inserted in the basic circuit. Precision machine for use in inventory management The temperature output compensation circuit is a necessary condition. In addition, the applied voltage in the strain detection circuit Even if the constant is applied from the indicator, the applied voltage changes rapidly due to the temperature resistance change of the lead wire, so a compensation circuit is required.

In addition to the temperature output change in the basic circuit using the strain gauge, the output change according to the length of the lead wire is as follows.

In general, the temperature compensation at the time of no load of the strain detector and the temperature compensation for the output at the load are completely done, and even if the detector is manufactured, it is usually composed of 100m to 300m lead wires from the detector to the indicator during the installation process according to the conditions of the site.

When the lead wire is generally composed of an interlocking wire of 54.7 kW / 1 km, the resistance coefficients T, C, and R depending on temperature are 4,000 PPM. Therefore, assuming 200m lead wire, the wire resistance of lead wire is = 54.7 kW / km x 0.2 = 10.94 kW, and when DC1V is applied to the detection a, d terminals in Fig. 2C, the detection circuit portions b, c drop because of the line resistance Re, and a voltage of 0.94V is applied.

In addition, if the strain detector is installed where the installation condition changes from -15 ℃ to 40 ℃, the voltage drop along the lead wire is as follows.

The line resistance of -15 ℃ is lower than 20 ℃

∴ = 10.94-1.5316 = 9.408Ω

At 40 ℃

∴ = 10.94Ω + 0.875Ω = 11.81Ω

Therefore, resistance change of lead wire by temperature

As a result, the output change caused by voltage drop causes 2.44% output change in 55 ℃ deviation. Therefore, the precision grade that can be used for inventory management should be maintained at a level of 0.1%, so it is necessary to compensate the output by the lead wires, and moreover, actively compensate for the length of the lead wires.

As described above, the circuit is improved as shown in FIG. 3 to compensate for the output error according to the lead wire length.

Specifically, a voltage is applied across a and b in FIG. Since is an active strain gage, the resistance changes to produce an output at the output g, h.

Is the compensation gauge for the temperature of the output under load Is the shunt resistance, Is the resistance along the lead wire length.

For example, when wiring 200m of 20 ℃ AWG No22 copper wire Is the standard resistance, and the detector used at -15 ℃ to 40 ℃ is the maximum deviation resistance ( )silver

to be.

Therefore, assuming that the resistance change by the lead wire is a maximum of 4.8 Ω at both ends of a and d, and the output change by this is a standard resistance of 430 구 as follows.

Where n is the output ratio

Silver input resistance

Rs is the maximum resistance change,

therefore, N = 0.989

In particular, if a lead wire resistance occurs at a temperature of 4.8 kΩ across a and d, an output drop of 1.1% occurs at the output g, h.

And input voltage is applied to b, c Strain If you derive the change value according to the temperature when outputting

ego

At 20 ℃ to be.

Strain gauge resistance at 40

At that time, strain by load

The change of strain gauge resistance by strain

∴

Therefore, ①

Produces an output

On the other hand, at -15 ℃

From above

Therefore, ①

하면 If voltage is applied at both ends of -15 ℃ and 40 ℃ at both ends of b, c, output voltage rises from 1.4668mV / V to 1.4808mV / V.

If this is expressed as a percentage

Therefore, where the voltage output g, h is changed from -15 ℃ to 40 ℃ in the a, b, c, d sections, the output drop by the lead wire is -1.1% and the output increase by 0.95% is combined. Is generated, and this It is within the controllable range and can be satisfied within 0.1% of possible precision for inventory control of strain detectors.

Therefore, the temperature compensation along the line length is compensated to the precision level by the circuit.

The strain gage circuit configured as described above is mounted in the mounting groove 12 of the deformation detection gauge 11, and the deformation detection part is fixed at an appropriate position of a bridge or a large storage container, and the material of the structure and the deformation detector to be fixed. In consideration of the material, shape and load state, as shown in FIG. 5, the structure 15 is fixed using the bracket 14. Only by changing the shape and length of the bracket, the best output can be obtained, and the special scope of the site can be reflected to extend the range of use, thereby providing flexibility for installation.

In the same way as described above, the output value of the strain detection part according to the temperature change can be directly compensated after operation in the untreated part, and precise output value can be obtained even with the length of the lead wire and the temperature change along the length.

In addition, the strain detection part and the lead wire are compensated for the temperature change, so that accurate measurement is possible, so it is stable and reliable in the long term. Therefore, it is possible to stably and continuously obtain information such as physical properties such as bending, deflection, fatigue, yield, internal stress state by measuring the amount of contents stored in a large storage container or non-destructive physical properties of large structures such as bridges. Automated introduction can be made by accurately grasping inventory, preventing loss due to measurement errors, reducing costs, and accurately understanding the physical properties of structures to prevent large accidents and reflect them in design Therefore, there is a characteristic that can greatly contribute to industrial development.

Claims (4)

In the detection device for measuring the physical quantity of the structure with a strain detector applied strain strain, Deformation detection unit having a plurality of sensors for generating a voltage according to the resistance change of the strain gauge, and the plurality of sensors are installed in different positions, And a temperature compensation sensor for compensating for errors in the outputs of the sensors due to a minute temperature difference between the installation positions, and connecting the input / output lines of the deformation detection unit, the input / output lines of the temperature compensation sensor, and the input / output lines of the indicator. A synthetic condition wiring for compensating and outputting errors of the outputs of the sensors; A circuit for compensating for errors in the outputs of the sensors according to lead lengths to the strain detection unit and the indicator; Receives analog output voltages of the sensors compensated for the error of the installation position and the length of the lead wire, amplifies and converts the analog output voltages into digital values, and remotely converts the digital values using a predetermined communication standard. The indicator to be transmitted to, And a computer for processing and displaying the digital values from the indicator on a monitor. The method of claim 1, A circuit for compensating for errors in the outputs of the sensors along the lead wire length may change a connection of a bridge circuit including a plurality of strain gauges provided inside each of the sensors so as to be independent of an amount of resistance change according to the lead wire length. Apparatus characterized in that consisting of. The method of claim 1, wherein each of the plurality of sensors are mounted in a deformation detection gauge having a mounting groove, the deformation detection gauge mounted to the sensor has an agglomeration portion by the mounting groove, and fixed to the structure to be measured using a bracket Apparatus characterized in that the. The method of claim 2, The connection change includes the first strain gage R1 and the fourth strain gage R4, the resistance of which decreases as the load increases, and the second strain gage R2 and the third strain gage, which increases the resistance when the load increases. In the bridge circuit formed of R3), a lead wire for measuring voltage is connected to a contact point between the first strain gage and the second strain gage, and a contact point for connecting the third strain gage and the fourth strain gage. And separates and connects the lead wires of the other side to each other.