CN202522583U - Resistance strain transducer type device for detecting current speed in pipeline - Google Patents

Abstract

The utility model relates to a resistance strain type transducer used for detecting the current speed in a pipeline, especially to a resistance strain transducer type device for detecting the current speed in a pipeline. The resistance strain transducer type device for detecting the current speed in the pipeline is characterized in that the device comprises the resistance strain type transducer arranged in the bottom of the pipeline, wherein the resistance strain type transducer comprises a constant flow source bridge circuit and an operational amplification circuit which are connected in series. The device of the utility model is simple in structure and reasonable in design.

Description

The sensor-type pipe flow speed pick-up unit of a kind of resistance-strain

(1) technical field

The utility model relates to a kind of resistance strain type sensor that in pipeline, is used to detect flow velocity, the sensor-type pipe flow speed pick-up unit of particularly a kind of resistance-strain.

(2) background technology

Along with industrialized development, liquid such as oil, water are used widely because of its economy, security and reliability in ducted transmission, so just very important to its detection at the transmission flow velocity of pipeline.

Owing to industrial expansion, to oil, the demand of resources such as water rises rapidly in recent years., economy pipeline transmission complete, reliable as Jian in the liquid transmission more and more comes into one's own.Yet because the relative leakproofness and the security requirement of its pipeline transportation make us remove to measure the flow velocity of these liquid as measuring river water speed.Traditional flow measurement mode is to adopt the ultrasonic Doppler discharge method to measure; Its measuring principle is hyperacoustic Doppler effect; Carry out the mensuration of flow velocity by the frequency difference of incident wave and reflection wave; The incident frequency of ultrasonic is fixed, and this just need measure the frequency of sound wave that reflects accurately.Yet reflective sound wave is submerged among a large amount of noises, so the error that causes is bigger.

(3) summary of the invention

The utility model provides a kind of simple in structure, practical and convenient resistance-strain sensor-type pipe flow speed pick-up unit in order to remedy the deficiency of prior art.

The utility model is realized through following technical scheme:

The sensor-type pipe flow speed pick-up unit of a kind of resistance-strain is characterized in that: comprise the resistance strain type sensor that is arranged at duct bottom, resistance strain type sensor comprises the constant current source bridge diagram and amplification computing circuit that is in series.

The optimal case of the utility model is:

Said constant current source bridge diagram output has voltage V _iSaid voltage V _iPass through resistance R ₅Connect the negative pole of voltage amplifier, the positive pole of voltage amplifier passes through resistance R _pVirtual earth connects, and the output terminal of voltage amplifier is connected with output voltage V behind the diode _o, voltage V _oThe place passes through resistance R _lGround connection, voltage V _oBe connected to tail end and be connected in resistance R ₅And the open feedback circuit between the voltage amplifier; Said open feedback circuit is the resistance R that connects successively ₃With in-phase multiplier 12.

The beneficial effect of the utility model is: this utility model simple in structure, according to existing resistance strain type sensor design, know by Bernoulli equation; In the ideal case; Suppose that static pressure is identical, promptly liquid is full of pipeline, and flow velocity v's is square linear with its pressure p to pipeline; Utilize resistance strain-gauge transducer that the pressure that obtains is converted into electric signal, utilize the evolution circuit to obtain the linear relationship of measured voltage values and flow velocity again.Detect the flow velocity of liquid in the closed conduit thus; Resistance strain-gauge transducer is because measurement range is wide, precision is high; As force cell, can survey 10 ^-2: 10 ⁷The power of N, precision reach more than the 0.05%FS; As pressure transducer, can survey 10 ^-2: 10 ⁷The pressure of Pa, precision can reach 0.1%FS; Stable and reliable for performance; Long service life, advantage such as can under harsh environmental conditions, work adopts flow rate of fluid in the resistance strain type sensor measuring channel; And use simulation evolution circuit to make measured voltage values and flow velocity linear, be suitable for wide popularization and application.

(4) description of drawings

Below in conjunction with accompanying drawing the utility model is further described.

Accompanying drawing 1 is the structural representation of the utility model;

Accompanying drawing 2 is the constant current source bridge diagram structural representation of the utility model;

Accompanying drawing 3 is the amplification computing circuit structure synoptic diagram of the utility model;

Among the figure, 1 pipeline, 2 resistance strain type sensors, 3 constant current source bridge diagrams, 4 voltage V _i, 5 resistance R ₅, 6 voltage amplifiers, 7 resistance R _p, 8 diodes, 9 output voltage V _o, 10 resistance R _l, 11 resistance R ₃, 12 in-phase multiplier.

(5) embodiment

Accompanying drawing is a kind of specific embodiment of the utility model.This embodiment comprises the resistance strain type sensor 2 that is arranged at pipeline 1 bottom, and resistance strain type sensor 2 comprises the constant current source bridge diagram 3 and amplification computing circuit that is in series; Said constant current source bridge diagram 3 outputs have voltage V _i4; Said voltage V _i4 pass through resistance R ₅5 connect the negative pole of voltage amplifier 6, and the positive pole of voltage amplifier 6 passes through resistance R _p7 virtual earths connect, and the output terminal of voltage amplifier 6 is connected with diode 8 back output voltage V _o9, voltage V _o9 places pass through resistance R _l10 ground connection, voltage V _o9 are connected to tail end is connected in resistance R ₅5 and voltage amplifier 6 between open feedback circuit; Said open feedback circuit is the resistance R that connects successively ₃11 with in-phase multiplier 12.

Adopt the sensor-type pipe flow speed pick-up unit of resistance-strain of the utility model, according to Bernoulli equation, flow velocity is high more, and pressure is more little.Because deformation takes place in the size of the mechanically deform that strain resistor R1 resistance wire resistance is born with it, be 0 and liquid when being full of pipeline at flow velocity, the pressure of pipeline 1 bottom is maximum, i.e. static pressure.If this moment, the pressure on the unit area was: R=R '+Δ R ', the resistance value when wherein R ' does not receive any pressure for resistance P1 foil gauge, Δ R ' for resistance R 1 because 1. resistance change value when receiving static pressure.When flow rate of liquid in the pipeline 1 was not 0, the pressure ratio fluid that foil gauge receives was little when static, and the foil gauge resistance will reduce to some extent, established resistance change this moment amount to be-Δ R, and the R value will change, and this signal is through the voltage V in the constant current source bridge diagram 3 _iTake out, and make flow velocity and voltage linear through the evolution circuit.

1. " sensor construction and circuit.

Accompanying drawing 1, strain-gauge transducer stick on pipeline 1 inside bottom, and concrete cementing agent and condition are decided according to actual conditions.In fluid is full of pipeline and when static, the stressed maximum of foil gauge, resistance value is maximum, and when flow velocity was accelerated, resistance value reduced.In order to reduce nonlinearity erron, we adopt constant current source electric bridge working method, accompanying drawing 2:

Add in the constant current source power supply at illustrated equal arm bridge; If R ₁=R ₂=R ₃=R ₄=R, wherein, R ₁Be responsive original paper, have:

$\mathrm{\&epsiv;}=\frac{\mathrm{\&Delta;}{R}_1}{{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="HSA00000654197100011.png,HSA00000654197100012.png"\; state="\{\{state\}\}">R</figure-callout>}}_1}=\frac{\mathrm{\&Delta;R}}{R}$

$V_i=\frac{R_1{R}_4-R_2{R}_3}{R_1+R_2+R_3+R_4}{I}_s$

Work as R ₁→ R ₁-Δ R has:

$V_i=-\frac{\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="HSA00000654197100011.png,HSA00000654197100012.png"\; state="\{\{state\}\}">R</figure-callout>}}_1\&CenterDot;R}{4R-\mathrm{\&Delta;}{R}_1}{I}_s=-\frac{\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="HSA00000654197100011.png,HSA00000654197100012.png"\; state="\{\{state\}\}">R</figure-callout>}}_1/R}{4(1-\frac{\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="HSA00000654197100011.png,HSA00000654197100012.png"\; state="\{\{state\}\}">R</figure-callout>}}_1}{4R})}\&CenterDot;{\mathrm{RI}}_s=-\frac{\mathrm{\&epsiv;}}{4(1-\frac{\mathrm{\&epsiv;}}{4})}{U}_s\&ap;-\frac{\mathrm{\&epsiv;}}{4}(1+\frac{\mathrm{\&epsiv;}}{4})U_s$

Ideal is output as:

$V_{\mathrm{is}}=-\frac{\mathrm{\&epsiv;}}{4}{U}_s$

Nonlinearity is:

${\mathrm{\&delta;}}_f=-\frac{\mathrm{\&epsiv;}}{4}$

Sensitivity is:

$K_{\mathrm{us}}=-\frac{1}{4}{U}_s$

In pipeline, under the ideal situation, rate of flow of fluid and pressure are determined by Bernoulli equation:

In actual field, because ρ gh and const are definite value, so pressure p and water flow velocity υ's is square linear, in order to make measured value and actual value linear, in constant current source bridge diagram 3 output voltage V _iAdd a simulation squaring circuit after 4, as shown in Figure 3:

Utilize the feedback network of power operation circuit, just constitute the extraction of square root computing circuit as amplifier, as shown in Figure 3, R=R ₅=R ₃Have according to the virtual earth notion:

$\frac{V_2}{R}+\frac{V_i}{R}=0$

Or V ₂=-V ₁

Obtain according to multiplier circuit again

${\mathrm{KV}}_0^2={\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="HSA00000654197100011.png"\; state="\{\{state\}\}">V</figure-callout>}}_2=-V_i$

$V_o=\sqrt{-\frac{V_i}{K}}$

With the output terminal of input termination constant current source bridge diagram 3 of extraction of square root circuit, the adjustment circuit parameter makes flow velocity v and output voltage V _o9 is linear, so just can draw flow velocity v by the voltage table reading easily.

Claims (4)

1. sensor-type pipe flow speed pick-up unit of resistance-strain is characterized in that: comprise the resistance strain type sensor (2) that is arranged at pipeline (1) bottom, resistance strain type sensor (2) comprises the constant current source bridge diagram (3) and amplification computing circuit that is in series.

2. the sensor-type pipe flow speed pick-up unit of resistance-strain according to claim 1 is characterized in that: said constant current source bridge diagram (3) output has voltage V _i(4).

3. the sensor-type pipe flow speed pick-up unit of resistance-strain according to claim 1 and 2 is characterized in that: said voltage V _i(4) pass through resistance R ₅(5) negative pole of connection voltage amplifier (6), the positive pole of voltage amplifier (6) passes through resistance R _p(7) virtual earth connects, and the output terminal of voltage amplifier (6) is connected with diode (8) back output voltage V _o(9), voltage V _o(9) locate through resistance R _l(10) ground connection, voltage V _o(9) be connected to tail end and be connected in resistance R ₅(5) and the open feedback circuit between the voltage amplifier (6).

4. the sensor-type pipe flow speed pick-up unit of resistance-strain according to claim 3 is characterized in that: resistance R 3 (11) and the in-phase multiplier (12) of said open feedback circuit for connecting successively.

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