CN103471737A - Thermocouple temperature detection system - Google Patents

Abstract

The invention provides a thermocouple temperature detection system which comprises a thermocouple detection loop, a temperature acquisition module and a loop voltage pull-up module, wherein the thermocouple detection loop is composed of two conductors made of different materials, and one end of the thermocouple detection loop is in contact with an object to be detected so as to generate a thermoelectric signal; the temperature acquisition module is used for receiving the thermoelectric signal through a detection point at the other end of the thermocouple detection loop and calculating the temperature of the object to be detected according to the thermoelectric signal; and the loop voltage pull-up module is used for providing bias voltage for the detection point of the thermocouple detection loop. By using the loop voltage pull-up module to provide bias voltage for the detection point, the thermocouple temperature detection system can correctly judge abnormal open circuit and normal temperature change of a thermocouple.

Description

The electric thermo-couple temperature detection system

Technical field

The present invention relates to industrial control field, particularly relate to a kind of electric thermo-couple temperature detection system.

Background technology

In the application of industrial control equipment, often use the temperature of thermocouple measurement controlled device.But the abnormal conditions of open circuit occur in thermopair sometimes, if at this moment the direct input temp acquisition modules in thermopair two ends (comprising difference A/D converter), thermopair heat outputting electromotive force reduces, now the electric thermo-couple temperature detection system can't judge that normal temperature changes or abnormal open circuit, thereby causes electric thermo-couple temperature detection system feedback extremely to lose efficacy.When serious, may cause the superheated of controlled device and burning apparatus exists fire to suffer from.

Therefore, be necessary to provide a kind of electric thermo-couple temperature detection system, to solve the existing problem of prior art.

Summary of the invention

The purpose of embodiments of the invention is to provide a kind of electric thermo-couple temperature detection system, can't change and be judged the abnormal open circuit of thermopair and normal temperature to solve electric thermo-couple temperature detection system in prior art, thereby cause the electric thermo-couple temperature detection system to lose efficacy or the technical matters of burning apparatus.

For addressing the above problem, technical scheme provided by the invention is as follows:

A kind of electric thermo-couple temperature detection system is provided, and it comprises:

Thermopair detects loop, the conductor of two kinds of unlike materials, consists of, and the end that described thermopair detects loop contacts with measured object, with the generation pyroelectric signal;

Temperature collect module, for detect the check point of the other end in loop by described thermopair, receive described pyroelectric signal, and calculate the temperature of described measured object according to described pyroelectric signal; And

Drawing-die piece on loop voltage, provide bias voltage for the check point of detecting loop to described thermopair.

In electric thermo-couple temperature detection system of the present invention, the first check point that described temperature collect module detects the other end in loop with described thermopair respectively is connected with the second check point, and on described loop voltage, the drawing-die piece comprises:

The first pull-up unit, provide bias voltage for giving described the first check point.

In electric thermo-couple temperature detection system of the present invention, described the first pull-up unit comprises pull-up resistor R1 and divider resistance R2, the end of described pull-up resistor R1 is connected with power supply, the other end of described pull-up resistor R1 is connected with described the first check point, the end of described divider resistance R2 is connected with described the first check point, the other end ground connection of described divider resistance R2.

In electric thermo-couple temperature detection system of the present invention, described the first pull-up unit also comprises adjusting resistance R3, and described divider resistance R2 is by described adjusting resistance R3 ground connection.

In electric thermo-couple temperature detection system of the present invention, | (R2+R3)/(R1+R2+R3) * Vcc| > Max(|Vs1-Vs2|), wherein Vcc is for providing the voltage source of bias voltage, and Vs1-Vs2 is the pyroelectric signal that the measured object temperature produces.

In electric thermo-couple temperature detection system of the present invention, on described loop voltage, the drawing-die piece also comprises:

The second pull-up unit, provide bias voltage for giving described the second check point.

In electric thermo-couple temperature detection system of the present invention, described the second pull-up unit comprises pull-up resistor R4 and divider resistance R5, the end of described pull-up resistor R4 is connected with power supply, the other end of described pull-up resistor R4 is connected with described the second check point, the end of described divider resistance R5 is connected with described the second check point, the other end ground connection of described divider resistance R5.

In electric thermo-couple temperature detection system of the present invention, | R5/ (R4+R5) * Vcc| > Max(|Vs1-Vs2|), wherein Vcc is for providing the voltage source of bias voltage, and Vs1-Vs2 is the pyroelectric signal that the measured object temperature produces.

In electric thermo-couple temperature detection system of the present invention, | (R2+R3)/(R1+R2+R3) * Vcc-R5/ (R4+R5) * Vcc| > Max(|Vs1-Vs2|), wherein Vcc is for providing the voltage source of bias voltage, and Vs1-Vs2 is the pyroelectric signal that the measured object temperature produces.

In electric thermo-couple temperature detection system of the present invention, described pull-up resistor R1 is greater than 100Rs, and described divider resistance R2 and described adjusting resistance R3 sum are greater than 100Rs;

Described pull-up resistor R4 is greater than 100Rs, and described divider resistance R5 is greater than 100Rs, and wherein Rs is the resistance that described thermopair detects loop.

Compared to prior art, electric thermo-couple temperature detection system of the present invention provides bias voltage by drawing-die piece on loop voltage to check point, can abnormal open circuit and the normal temperature variation of thermopair correctly be judged; Having solved temperature monitoring system in the prior art can't change and be judged the abnormal open circuit of thermopair and normal temperature, thereby causes the technical matters of temperature monitoring thrashing or burning apparatus.

The accompanying drawing explanation

The structural representation of the preferred embodiment that Fig. 1 is electric thermo-couple temperature detection system of the present invention;

The physical circuit figure of the preferred embodiment that Fig. 2 is electric thermo-couple temperature detection system of the present invention;

Wherein, description of reference numerals is as follows:

10,20: the electric thermo-couple temperature detection system;

11,21: thermopair detects loop;

12,22: temperature collect module;

13,23: drawing-die piece on loop voltage;

131,231: the first pull-up units;

132,232: the second pull-up units.

Embodiment

Below the explanation of each embodiment be with reference to additional graphic, can be in order to the specific embodiment of implementing in order to illustration the present invention.

The ultimate principle of thermocouple temperature measurement is that the material conductor of two kinds of different components forms closed-loop path, when there is thermograde in two ends, just having electric current in loop passes through, now between two ends, just there is electromotive force---thermopower, so-called Seebeck effect that Here it is (Seebeck effect).The homogeneous conductor of two kinds of different components is thermode, and a tested end is working end, and the other end is free end, and free end is usually under certain stationary temperature.

Please refer to Fig. 1, the structural representation of the preferred embodiment that Fig. 1 is electric thermo-couple temperature detection system of the present invention.The electric thermo-couple temperature detection system 10 of this preferred embodiment comprises that thermopair detects drawing-die piece 13 on loop 11, temperature collect module 12 and loop voltage.Wherein thermopair detection loop 11 consists of the conductor of two kinds of unlike materials, and the end (working end) that this thermopair detects loop 11 contacts with measured object, to produce pyroelectric signal.Temperature collect module 12, for the first check point and second check point of the other end (free end) that detects loop 11 by thermopair, receives pyroelectric signal, and calculates the temperature of measured object according to this pyroelectric signal.

On loop voltage, drawing-die piece 13 comprises the first pull-up unit 131 and the second pull-up unit 132, wherein the first pull-up unit 131 provides bias voltage for the first check point that detects loop 11 to thermopair, and the second pull-up unit 132 provides bias voltage for the second check point that detects loop 11 to thermopair.

When the electric thermo-couple temperature detection system of this preferred embodiment is worked, open loop state appears in the first check point one side that detects loop 11 as thermopair, the first pull-up unit 131 can be pulled to the voltage of the first check point one stable magnitude of voltage, at this moment temperature collect module 12 can receive first a fixing pyroelectric signal, and open loop state appears in the first check point one side that temperature collect module 12 can detect loop 11 according to this first pyroelectric signal judgement thermopair.

Open loop state appears in the second check point one side that detects loop 11 as thermopair, the second pull-up unit 132 can be pulled to the voltage of the second check point one stable magnitude of voltage, at this moment temperature collect module 12 can receive fixing second pyroelectric signal (this second pyroelectric signal generally is different from the first pyroelectric signal) equally, and temperature collect module 12 can judge that open loop state appears in second check point one side in this thermopair detection loop 11 according to this second pyroelectric signal.

Open loop state all appears in the first check point one side and the second check point one side that detect loop as thermopair, the first pull-up unit 131 is pulled to a stable magnitude of voltage by the voltage of the first check point, the second pull-up unit 132 is pulled to a stable magnitude of voltage by the voltage of the second check point, at this moment temperature collect module 12 can receive fixing the 3rd pyroelectric signal (the 3rd pyroelectric signal should be different from the first pyroelectric signal and the second pyroelectric signal) equally, temperature collect module 12 can judge that open loop state appears in the first check point and second check point in this thermopair detection loop 11 simultaneously according to the 3rd pyroelectric signal.

While as thermopair, detecting the loop normal operation, the first pull-up unit 131 is pulled to a stable magnitude of voltage by the voltage of the first check point, the second pull-up unit 132 is pulled to a stable magnitude of voltage by the voltage of the second check point, at this moment the common mode voltage of the first check point and the second check point is roughly zero, and temperature collect module 12 can detect the temperature that the actual pyroelectric signal detected in loop 11 calculates measured object according to thermopair.

The electric thermo-couple temperature detection system 10 of this preferred embodiment provides bias voltage by 13 pairs of check points of drawing-die piece on loop voltage, can abnormal open circuit and the normal temperature variation of thermopair correctly be judged.

Illustrate the principle of work of electric thermo-couple temperature detection system of the present invention below by Fig. 2.The physical circuit figure of the preferred embodiment that Fig. 2 is electric thermo-couple temperature detection system of the present invention.

In this preferred embodiment, the first pull-up unit 231 comprises pull-up resistor R1, divider resistance R2 and adjusting resistance R3, the end of pull-up resistor R1 is connected with power supply, the other end of pull-up resistor R1 is connected with the first check point A, the end of divider resistance R2 is connected with the first check point A, and the other end of divider resistance R2 is by adjusting resistance R3 ground connection.Wherein the resistance of pull-up resistor R1 is substantially equal to the resistance of divider resistance R2, and the resistance of the resistance of pull-up resistor R1, divider resistance R2 and the resistance of adjusting resistance R3 detect the resistance Rs1 in loop 21 much larger than thermopair.The resistance of preferred adjusting resistance R3 is less than the resistance of pull-up resistor R1, as R3=0.5R1.

The second pull-up unit 232 comprises pull-up resistor R4 and divider resistance R5, the end of pull-up resistor R4 is connected with power supply, the other end of pull-up resistor R4 is connected with the second check point B, and the end of divider resistance R5 is connected with the second check point B, the other end ground connection of divider resistance R5.Wherein the resistance of pull-up resistor R4 is substantially equal to the resistance of divider resistance R5, and the resistance of the resistance of pull-up resistor R4 and divider resistance R5 detects the resistance Rs2 in loop 21 much larger than thermopair.

When the electric thermo-couple temperature detection system 20 of this preferred embodiment is worked, the far-end that thermopair detects loop 21 contacts with measured object, and to produce pyroelectric signal, the near-end that thermopair detects loop 21 is connected with temperature collect module 22.Because the conductor of thermopair detection loop 21 by two kinds of unlike materials forms, therefore this pyroelectric signal can be meaned by Vs1 and Vs2, this pyroelectric signal can exert an influence to the electric potential difference of the first check point A and the second check point B, and temperature collect module 22 calculates the temperature of measured object by the electric potential difference of calculating the first check point A and the second check point B.

When thermopair detects loop 21 normal operation, from Fig. 2, calculated:

${\mathrm{<figure-callout\; id="1"\; label="I\; s"\; filenames="HDA0000376102370000012.png"\; state="\{\{state\}\}">I</figure-callout>}}_s=\frac{V_A-V_{s1}}{R_{s1}}---\left(1\right)$

$I_{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="HDA0000376102370000012.png"\; state="\{\{state\}\}">s</figure-callout>}1}+\frac{V_A}{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="HDA0000376102370000012.png"\; state="\{\{state\}\}">R</figure-callout>}}_2+R_3}=\frac{V_{\mathrm{cc}}-V_A}{R_1}---\left(2\right)$

By (1) substitution (2), obtain (3)

$(\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="R\; S"\; filenames="HDA0000376102370000012.png"\; state="\{\{state\}\}">R</figure-callout>}}_S}+\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="HDA0000376102370000012.png"\; state="\{\{state\}\}">R</figure-callout>}}_1}+\frac{1}{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="HDA0000376102370000012.png"\; state="\{\{state\}\}">R</figure-callout>}}_2+R_3})V_A=\frac{{\mathrm{<figure-callout\; id="1"\; label="V\; cc\; R"\; filenames="HDA0000376102370000012.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{cc}}}{R_{}}+\frac{V_{S1}}{R_{S1}}---\left(3\right)$

Due to

?

can ignore, pull-up resistor R1 is greater than 100Rs1 here, and divider resistance R2 and adjusting resistance R3 sum are greater than 100Rs, obtain (4)

$\frac{V_A-V_{s1}}{V_{\mathrm{cc}}}=\frac{R_{s1}}{R_1}---\left(4\right)$

Resistance R due to thermopair detection loop 21 _s1<<R ₁,

level off to 0, obtain V _a≈ V _s1;

In like manner for the B point,

$I_{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="HDA0000376102370000012.png"\; state="\{\{state\}\}">s</figure-callout>}2}=\frac{V_{s2}-V_B}{R_{s2}}---\left(5\right)$

$I_{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="HDA0000376102370000012.png"\; state="\{\{state\}\}">s</figure-callout>}2}+\frac{V_{\mathrm{cc}}-V_B}{R_4}=\frac{V_B}{R_5}---\left(6\right)$

By (5) substitution (6), obtain (7)

$\frac{V_{s2}-V_B}{V_B-{2V}_{\mathrm{cc}}}=\frac{R_{s2}}{R_4}---\left(7\right)$

Resistance R due to thermopair detection loop 21 _s2<<R ₄, pull-up resistor R4 is greater than 100Rs2, and divider resistance R5 is greater than 100Rs2;

level off to 0, obtain V _b≈ V _s2; A, B point common mode voltage is about 0, the pyroelectric signal (Vs1 and Vs2) that normal output is produced by the measured object temperature, and wherein on loop voltage, drawing-die piece 23 does not exert an influence to this pyroelectric signal.

When open loop state appears in first check point A mono-side in thermopair detection loop 21, from Fig. 2, calculated:

The A point voltage is promoted to (R2+R3)/(R1+R2+R3) * Vcc, | (R2+R3)/(R1+R2+R3) * Vcc| > Max(|Vs1-Vs2|), wherein Vcc is for providing the voltage source of bias voltage, Vs1-Vs2 is the pyroelectric signal that the measured object temperature produces, still in the 0V left and right, (it is less that thermopair detects the normal output potential in loop 21 to the B point voltage, in the microvolt level), now between A, B, voltage difference is about (R2+R3)/(R1+R2+R3) * Vcc, far above normal output, thereby temperature collect module 22 is learnt the first check point A mono-side that thermopair detects loop 21 and open loop state occurred.

When open loop state appears in second check point B mono-side in thermopair detection loop 21, from Fig. 2, calculated:.

The B point voltage is promoted to R5/ (R4+R5) * Vcc, | R5/ (R4+R5) * Vcc| > Max(|Vs1-Vs2|), wherein Vcc is for providing the voltage source of bias voltage, Vs1-Vs2 is the pyroelectric signal that the measured object temperature produces, the A point voltage is still in the 0V left and right, be about-R5/ of voltage difference (R4+R5) * Vcc between A, B now, also far above normal output.And different, same when open loop state appears in the first check point A mono-side that between A, B, voltage difference and above-mentioned thermopair detect loop 21, temperature collect module 22 learns that open loop state appears in the second check point B mono-side that thermopair detects loop 21.

When thermopair detects first check point A mono-side in loop 21 and the second check point B mono-side and all open loop state occurs, from Fig. 2, calculated:

The A point voltage is promoted to (R2+R3)/(R1+R2+R3) * Vcc, be promoted to-R5/ of B point voltage (R4+R5) * Vcc, and between A, B point, voltage difference is (R2+R3)/(R1+R2+R3) * Vcc-R5/ (R4+R5) * Vcc.Only need to meet | (R2+R3)/(R1+R2+R3) * Vcc-R5/ (R4+R5) * Vcc| > max (| Vs1-Vs2|), this value can be distinguished with all normal output valves, and temperature collect module 22 can judge that open loop state all appears in the first check point A mono-side and second check point B mono-side in thermopair detection loop 21.

When the electric thermo-couple temperature detection system 20 of this preferred embodiment is used, as different open circuit situation appears, temperature collect module 22 can be exported different exceptional values, these exceptional values are not conflicted fully with the normal output valve of temperature collect module 22, so the electric thermo-couple temperature detection system 20 of this preferred embodiment can correctly judge abnormal open circuit and the normal temperature variation of thermopair.

Electric thermo-couple temperature detection system of the present invention provides bias voltage by drawing-die piece on loop voltage (i.e. a simple resistor voltage divider circuit) to check point, can abnormal open circuit and the normal temperature variation of thermopair correctly be judged, method is simple and reliable, realizes that cost is low; Having solved temperature monitoring system in the prior art can't change and be judged the abnormal open circuit of thermopair and normal temperature, thereby causes the technical matters of temperature monitoring thrashing or burning apparatus.

In sum; although the present invention discloses as above with preferred embodiment; but above preferred embodiment is not in order to limit the present invention; those of ordinary skill in the art; without departing from the spirit and scope of the present invention; all can do various changes and retouching, so the scope that protection scope of the present invention defines with claim is as the criterion.

Claims (10)

1. an electric thermo-couple temperature detection system, is characterized in that, comprising:

Thermopair detects loop, the conductor of two kinds of unlike materials, consists of, and the end that described thermopair detects loop contacts with measured object, with the generation pyroelectric signal;

Temperature collect module, for detect the check point of the other end in loop by described thermopair, receive described pyroelectric signal, and calculate the temperature of described measured object according to described pyroelectric signal; And

Drawing-die piece on loop voltage, provide bias voltage for the check point of detecting loop to described thermopair.

2. electric thermo-couple temperature detection system according to claim 1, is characterized in that, the first check point that described temperature collect module detects the other end in loop with described thermopair respectively is connected with the second check point, and on described loop voltage, the drawing-die piece comprises:

The first pull-up unit, provide bias voltage for giving described the first check point.

3. electric thermo-couple temperature detection system according to claim 2, it is characterized in that, described the first pull-up unit comprises pull-up resistor R1 and divider resistance R2, the end of described pull-up resistor R1 is connected with power supply, the other end of described pull-up resistor R1 is connected with described the first check point, the end of described divider resistance R2 is connected with described the first check point, the other end ground connection of described divider resistance R2.

4. electric thermo-couple temperature detection system according to claim 3, is characterized in that, described the first pull-up unit also comprises adjusting resistance R3, and described divider resistance R2 is by described adjusting resistance R3 ground connection.

5. electric thermo-couple temperature detection system according to claim 4, is characterized in that,

| (R2+R3)/(R1+R2+R3) * Vcc| > Max(|Vs1-Vs2|), wherein Vcc is for providing the voltage source of bias voltage, and Vs1-Vs2 is the pyroelectric signal that the measured object temperature produces.

6. electric thermo-couple temperature detection system according to claim 4, is characterized in that, on described loop voltage, the drawing-die piece also comprises:

The second pull-up unit, provide bias voltage for giving described the second check point.

7. electric thermo-couple temperature detection system according to claim 6, it is characterized in that, described the second pull-up unit comprises pull-up resistor R4 and divider resistance R5, the end of described pull-up resistor R4 is connected with power supply, the other end of described pull-up resistor R4 is connected with described the second check point, the end of described divider resistance R5 is connected with described the second check point, the other end ground connection of described divider resistance R5.

8. electric thermo-couple temperature detection system according to claim 7, is characterized in that,

| R5/ (R4+R5) * Vcc| > Max(|Vs1-Vs2|), wherein Vcc is for providing the voltage source of bias voltage, and Vs1-Vs2 is the pyroelectric signal that the measured object temperature produces.

9. electric thermo-couple temperature detection system according to claim 7, is characterized in that,

| (R2+R3)/(R1+R2+R3) * Vcc-R5/ (R4+R5) * Vcc| > Max(|Vs1-Vs2|), wherein Vcc is for providing the voltage source of bias voltage, and Vs1-Vs2 is the pyroelectric signal that the measured object temperature produces.

10. electric thermo-couple temperature detection system according to claim 8, is characterized in that, described pull-up resistor R1 is greater than 100Rs, and described divider resistance R2 and described adjusting resistance R3 sum are greater than 100Rs;

Described pull-up resistor R4 is greater than 100Rs, and described divider resistance R5 is greater than 100Rs, and wherein Rs is the resistance that described thermopair detects loop.

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